Science.gov

Sample records for polymethyl methacrylate bone

  1. Ageing and moisture uptake in polymethyl methacrylate (PMMA) bone cements☆

    PubMed Central

    Ayre, Wayne Nishio; Denyer, Stephen P.; Evans, Samuel L.

    2014-01-01

    Bone cements are extensively employed in orthopaedics for joint arthroplasty, however implant failure in the form of aseptic loosening is known to occur after long-term use. The exact mechanism causing this is not well understood, however it is thought to arise from a combination of fatigue and chemical degradation resulting from the hostile in vivo environment. In this study, two commercial bone cements were aged in an isotonic fluid at physiological temperatures and changes in moisture uptake, microstructure and mechanical and fatigue properties were studied. Initial penetration of water into the cement followed Fickian diffusion and was thought to be caused by vacancies created by leaching monomer. An increase in weight of approximately 2% was experienced after 30 days ageing and was accompanied by hydrolysis of poly(methyl methacrylate) (PMMA) in the outermost layers of the cement. This molecular change and the plasticising effect of water resulted in reduced mechanical and fatigue properties over time. Cement ageing is therefore thought to be a key contributor in the long-term failure of cemented joint replacements. The results from this study have highlighted the need to develop cements capable of withstanding long-term degradation and for more accurate test methods, which fully account for physiological ageing. PMID:24445003

  2. Thermoforming polymethyl methacrylate.

    PubMed

    Jagger, R G; Okdeh, A

    1995-11-01

    This study characterized a range of commercially available polymethyl methacrylate sheets with respect to molecular weight, residual monomer content, and glass transition temperature and then developed a thermoforming procedure that produced visually satisfactory thermoformed polymethyl methacrylate specimens. Molecular weight values of Perspex material were considerably greater than those of the other materials. All materials but Diakon had residual monomer concentrations of less than 1% and glass transition temperature values greater than 100 degrees C. Perspex material was selected for further investigation. It was necessary to preheat Perspex sheets in an oven at 160 degrees C for at least 30 minutes before heating and forming on the thermoforming apparatus to obtain acceptable specimens.

  3. Bioactivity of Ceftazidime and Fluconazole Included in Polymethyl Methacrylate Bone Cement for Use in Arthroplasty.

    PubMed

    Martínez-Moreno, J; Merino, V; Nácher, A; Rodrigo, J L; Bonet Yuste, Blanca B; Merino-Sanjuán, M

    2017-10-01

    The microorganisms that most frequently cause prosthetic joint infection are methicillin-resistant Staphylococcus aureus and gram-negative aerobic bacillus. Studies have documented the efficacy of mixing antibiotics with polymethyl methacrylate, but that of antifungal drugs has not received much attention. The objective of this in vitro study was to characterize the elution profile and bioactivity of ceftazidime and fluconazole when incorporated into bone cement in proportions intended for prophylaxis and treatment of bone infections. Antibiotic-loaded bone cement cylinders in a proportion of 1:40 and 4:40 (ratio of grams of antibiotic to grams of cement) were assayed. Drug delivery was investigated in a flow-through dissolution apparatus (SotaxCE7). To assess bioactivity, antibiotic concentrations were simulated in the joint space of 1000 patients. Antibacterial properties were evaluated by counting colony forming units and the inhibition-halo test. The ratio of released ceftazidime and fluconazole was 453% and 648%, respectively, higher when used for treatment proportions than prophylaxis proportions. A bioactivity simulation exercise showed that the efficacy of ceftazidime/fluconazole determined as the amount of drug is released at the active site in the first 3 days after surgery would depend on the sensitivity of the microorganism and would increase substantially after drain removal. The microbiology study showed that biofilm formation by Pseudomonas aeruginosa could be a problem when ceftazidime was used in treatment or prophylaxis proportions. Our in vitro findings suggest that ceftazidime and fluconazole can be added into polymethyl methacrylate for the prevention/treatment of infections associated to joint surgery. Their efficacy depends on the sensitivity of the microorganism causing the infection. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Comparison of human mesenchymal stem cells proliferation and differentiation on poly(methyl methacrylate) bone cements with and without mineralized collagen incorporation.

    PubMed

    Wu, Jingjing; Xu, Suju; Qiu, Zhiye; Liu, Peng; Liu, Huiying; Yu, Xiang; Cui, Fu-Zhai; Chunhua, Zhao Robert

    2016-01-01

    Poly(methyl methacrylate) bone cement is widely used in vertebroplasty, joint replacement surgery, and other orthopaedic surgeries, while it also exposed many problems on mechanical property and biocompatibility. Better performance in mechanical match and bone integration is highly desirable. Recently, there reported that incorporation of mineralized collagen into poly(methyl methacrylate) showed positive results in mechanical property and osteointegration ability in vivo. In the present study, we focused on the comparison of osteogenic behavior between mineralized collagen incorporated in poly(methyl methacrylate) and poly(methyl methacrylate). Human marrow mesenchymal stem cells are used in this experiment. Adhesion and proliferation were used to characterize biocompatibility. Activity of alkaline phosphatase was used to assess the differentiation of human marrow mesenchymal stem cells into osteoblasts. Real-time PCR was performed to detect the expression of osteoblast-related markers at messenger RNA level. The results show that osteogenic differentiation on mineralized collagen incorporated in poly(methyl methacrylate) bone cement is more than two times higher than that of poly(methyl methacrylate) after culturing for 21 days. Thus, important mechanism on mineralized collagen incorporation increasing the osteogenetic ability of poly(methyl methacrylate) bone cement may be understood in this concern.

  5. Preparation of Calcium Phosphate Cement and Polymethyl Methacrylate for Biological Composite Bone Cements

    PubMed Central

    Yang, Jun; Zhang, Kairui; Zhang, Sheng; Fan, Jiping; Guo, Xinhui; Dong, Weiqiang; Wang, Shengnan; Chen, Yirong; Yu, Bin

    2015-01-01

    Background We studied the biological safety, biomechanics, and tissue compatibility of calcium phosphate cement and Polymethyl Methacrylate composite bone cement mixed in different ratios. Material/Methods CPC and PMMA were mixed in different ratios (3: 1, 2: 1, 1: 1, 1: 2, 1: 5, 1: 10, 1: 15, and 1: 20). PMMA solvent is a general solvent containing a dissolved preparation of the composite bone cement specific to a given specimen to determine biological safety, biomechanics, and tissue compatibility. Results The CPC/PMMA (33%) group, CPC/PMMA (50%) group, CPC/PMMA (67%) group, and CPC/PMMA (75%) group were more in line with the composite bone cement without cytotoxicity requirements. The compressive strength of the CPC/PMMA (67%) group and CPC/PMMA (75%) group was 20Mpa–30Mpa, while that of the CPC/PMMA (4.8%) group, CPC/PMMA (6.25%) group, CPC/PMMA (9.1%) group, CPC/PMMA (16.7%) group, CPC/PMMA (33%) group, and CPC/PMMA (50%) group was 40Mpa–70Mpa. Curing time was longer in the CPC group (more than 11 min) and shorter in the PMMA group (less than 2 min). The results of weight loss rate showed that there were no significant differences between the CPC/PMMA group (4.8%, 6.25%, 9.1%, 16.7%, 33%) and PMMA control group (p>0.05). With the decrease of CPC content, the rate of weight loss gradually decreased. Conclusions The CPC/PMMA (50%) group, CPC/PMMA (67%) group, and CPC/PMMA (75%) group provide greater variability and selectivity for the composite bone cement in obtaining better application. PMID:25904398

  6. Treatment methods for neoplastic metastates and tumor-like changes in the bodies and epiphyses of long bones using polymethyl methacrylate cement and bone grafting.

    PubMed

    Mrozek, Tomasz; Spindel, Jerzy; Miszczyk, Leszek; Koczy, Bogdan; Chrobok, Adam; Pilecki, Bolesław; Tomasik, Patryk; Matysiakiewicz, Jacek

    2005-10-30

    Background. The objective of our study was to evaluate the stabilization of reconstructed long bones after metastatic tumor resection and defect filling with polymethyl methacrylate (PMMA) or bone allograft. Material and methods. We studied a group of 107 patients who underwent surgery between 1996 and 2004 (55 females and 46 males). A primary neoplasmatic focus was found after histopathological examination in 58 cases, in 29 the histopathology was not evident, and in 20 cases no neoplastic tissue was found. Metastases were found within the femur in 73 cases, in the humerus in 19 cases, and in the tibia in 15 cases. Stabilization was performed using the traditional AO method, intramedullary nailing, or DHS/DCS fixation. Results. Taking into consideration clinical and radiological assessment, outcomes varied from fair to good. Better outcome was obtained in cases treated by polymethyl methacrylate (PMMA) filling combined with intramedullary nailing or DCS/DHS than in cases treated with traditional AO plating. For tumor-like lesions, complete bone graft consolidation was found after bone allograft filling in 14 of 20 cases. Conclusions. The 2 methods of long bone stabilization mentioned above, combined with polymethyl methacrylate (PMMA) or bone allograft filling, is the method of choice. Deep frozen bone grafting is possible only in cases of total tumor resection with the possibility of non-malignant tumor. The effect of reconstruction, besides fair or good outcome, included improved quality of life, less consumption of analgesics, and in many cases successful avoidance of pathological fracture.

  7. Phase holograms in polymethyl methacrylate

    NASA Technical Reports Server (NTRS)

    Maker, P. D.; Muller, R. E.

    1992-01-01

    A procedure is described for the fabrication of complex computer-generated phase holograms in polymethyl methacrylate (PMMA) by means of partial-exposure e-beam lithography and subsequent carefully controlled partial development. Following the development, the pattern appears (rendered in relief) in the PMMA, which then acts as the phase-delay medium. The devices fabricated were designed with 16 equal phase steps per retardation cycle, were up to 3 mm square, and consisted of up to 10 millions of 0.3-2.0-micron square pixels. Data files were up to 60 Mb-long, and the exposure times ranged to several hours. A Fresnel phase lens was fabricated with a diffraction-limited optical performance of 83-percent efficiency.

  8. Just a drop of cement: a case of cervical spine bone aneurysmal cyst successfully treated by percutaneous injection of a small amount of polymethyl-methacrylate cement

    PubMed Central

    Fahed, Robert; Clarençon, Frédéric; Riouallon, Guillaume; Cormier, Evelyne; Bonaccorsi, Raphael; Pascal-Mousselard, Hugues; Chiras, Jacques

    2014-01-01

    Aneurysmal bone cyst (ABC) is a benign hemorrhagic tumor, commonly revealed by local pain. The best treatment for this lesion is still controversial. We report the case of a patient with chronic neck pain revealing an ABC of the third cervical vertebra. After percutaneous injection of a small amount of polymethyl-methacrylate bone cement, the patient experienced significant clinical and radiological improvement. PMID:25498806

  9. Photolithography with polymethyl methacrylate (PMMA)

    NASA Astrophysics Data System (ADS)

    Carbaugh, Daniel J.; Wright, Jason T.; Parthiban, Rajan; Rahman, Faiz

    2016-02-01

    Polymethyl methacrylate (PMMA) is widely used as an electron beam resist but is not used as a photoresist because of its insensitivity to electromagnetic radiation with wavelengths longer than about 300 nm. In this paper we describe a technique for performing conventional photolithography with high molecular weight PMMA at the widely used 365 nm i-line wavelength. The technique involves photosensitizing PMMA with Irgacure 651—a commercially available photo-initiator that can cause PMMA strands to cross-link. Optimum amount of Irgacure can produce a negative tone photoresist with adequate photosensitivity and plasma etch resistance. We describe this technique in detail with complete processing conditions and discuss the effects of varying Irgacure 651 concentration in PMMA as well as changes in UV exposure dose. We also show example structures patterned with commonly available materials and equipment. Finally, we show that it is possible to carry out gradient lithography with this approach, in order to produce structures in relief in photosensitive PMMA.

  10. The long-term in vivo behavior of polymethyl methacrylate bone cement in total hip arthroplasty

    PubMed Central

    2011-01-01

    Background and purpose The long-term success of cemented total hip arthroplasty (THA) has been well established. Improved outcomes, both radiographically and clinically, have resulted mainly from advances in stem design and improvements in operating techniques. However, there is concern about the durability of bone cement in vivo. We evaluated the physical and chemical properties of CMW1 bone cements retrieved from patients undergoing revision THA. Methods CMW1 cements were retrieved from 14 patients who underwent acetabular revision because of aseptic loosening. The time in vivo before revision was 7–30 years. The bending properties of the retrieved bone cement were assessed using the three-point bending method. The molecular weight and chemical structure were analyzed by gel permeation chromatography and Fourier-transform infrared spectroscopy. The porosity of the bone cements was evaluated by 3-D microcomputer tomography. Results The bending strength decreased with increasing time in vivo and depended on the density of the bone cement, which we assume to be determined by the porosity. There was no correlation between molecular weight and time in vivo. The infrared spectra were similar in the retrieved cements and in the control CMW1 cements. Interpretation Our results indicate that polymer chain scission and significant hydrolysis do not occur in CMW1 cement after implantation in vivo, even in the long term. CMW1 cement was stable through long-term implantation and functional loading. PMID:22103279

  11. Contemporary adjuvant polymethyl methacrylate cementation optimally limits recurrence in primary giant cell tumor of bone patients compared to bone grafting: a systematic review and meta-analysis.

    PubMed

    Zuo, Dongqing; Zheng, Longpo; Sun, Wei; Fu, Dong; Hua, Yingqi; Cai, Zhengdong

    2013-07-16

    Reports of recurrence following restructuring of primary giant cell tumor (GCT) defects using polymethyl methacrylate (PMMA) bone cementation or allogeneic bone graft with and without adjuvants for intralesional curettage vary widely. Systematic review and meta-analysis were conducted to investigate efficacy of PMMA bone cementation and allogeneic bone grafting following intralesional curettage for GCT. Medline, EMBASE, Google Scholar, and Cochrane databases were searched for studies reporting GCT of bone treatment with PMMA cementation and/or bone grafting with or without adjuvant therapy following intralesional curettage of primary GCTs. Pooled risk ratios and 95% confidence intervals (CIs) for local recurrence risks were calculated by fixed-effects methods. Of 1,690 relevant titles, 6 eligible studies (1,293 patients) spanning March 2008 to December 2011 were identified in published data. Treatment outcomes of PMMA-only (n = 374), bone graft-only (n = 436), PMMA with or without adjuvant (PMMA + adjuvant; n = 594), and bone graft filling with or without adjuvant (bone graft + adjuvant; n = 699) were compared. Bone graft-only patients exhibited higher recurrence rates than PMMA-treated patients (RR 2.09, 95% CI (1.64, 2.66), Overall effect: Z = 6.00; P <0.001), and bone graft + adjuvant patients exhibited higher recurrence rates than PMMA + adjuvant patients (RR 1.66, 95% CI (1.21, 2.28), Overall effect: Z = 3.15, P = 0.002). Local recurrence was minimal in PMMA cementation patients, suggesting that PMMA is preferable for routine clinical restructuring in eligible GCT patients. Relationships between tumor characteristics, other modern adjuvants, and recurrence require further exploration.

  12. Contemporary adjuvant polymethyl methacrylate cementation optimally limits recurrence in primary giant cell tumor of bone patients compared to bone grafting: a systematic review and meta-analysis

    PubMed Central

    2013-01-01

    Background Reports of recurrence following restructuring of primary giant cell tumor (GCT) defects using polymethyl methacrylate (PMMA) bone cementation or allogeneic bone graft with and without adjuvants for intralesional curettage vary widely. Systematic review and meta-analysis were conducted to investigate efficacy of PMMA bone cementation and allogeneic bone grafting following intralesional curettage for GCT. Methods Medline, EMBASE, Google Scholar, and Cochrane databases were searched for studies reporting GCT of bone treatment with PMMA cementation and/or bone grafting with or without adjuvant therapy following intralesional curettage of primary GCTs. Pooled risk ratios and 95% confidence intervals (CIs) for local recurrence risks were calculated by fixed-effects methods. Results Of 1,690 relevant titles, 6 eligible studies (1,293 patients) spanning March 2008 to December 2011 were identified in published data. Treatment outcomes of PMMA-only (n = 374), bone graft-only (n = 436), PMMA with or without adjuvant (PMMA + adjuvant; n = 594), and bone graft filling with or without adjuvant (bone graft + adjuvant; n = 699) were compared. Bone graft-only patients exhibited higher recurrence rates than PMMA-treated patients (RR 2.09, 95% CI (1.64, 2.66), Overall effect: Z = 6.00; P <0.001), and bone graft + adjuvant patients exhibited higher recurrence rates than PMMA + adjuvant patients (RR 1.66, 95% CI (1.21, 2.28), Overall effect: Z = 3.15, P = 0.002). Conclusions Local recurrence was minimal in PMMA cementation patients, suggesting that PMMA is preferable for routine clinical restructuring in eligible GCT patients. Relationships between tumor characteristics, other modern adjuvants, and recurrence require further exploration. PMID:23866921

  13. Effects of porosity on the fatigue performance of polymethyl methacrylate bone cement: an analytical investigation.

    PubMed

    Evans, S L

    2006-01-01

    Porosity has been shown to affect the fatigue life of bone cements, but, although vacuum mixing is widely used to reduce porosity in the clinical setting, results have been mixed and the effects of porosity are not well understood. The aim of this study was to investigate the effects of porosity using stress analysis and fracture mechanics techniques. The stress concentrations arising at voids in test specimens were found using analytical solutions and boundary element methods. The fatigue life of specimens containing voids of various sizes was predicted using fracture mechanics techniques. For spherical voids that do not occupy a significant proportion of the cross-section, the resulting stress concentration is independent of void size and too small to account for the observed crack initiation. Cracks must therefore initiate at additional stress raisers such as radiopacifier particles or additional voids. For large voids, the stress increases as the remaining cross-section of the specimen decreases, and this may account for much of the observed reduction in fatigue strength in hand-mixed cement. Although crack initiation may be largely independent of void size, there is an effect on crack growth rate. Cracks are predicted to grow faster around larger voids, since they remain in the stress concentration around the void for longer. This effect may account for the relationship between porosity and fatigue life that has been observed in samples without large voids. Since porosity appears to affect crack growth more than initiation, it may be less damaging in high-cycle clinical fatigue, which may be predominantly initiation controlled, than in short laboratory tests.

  14. Dimensional accuracy of thermoformed polymethyl methacrylate.

    PubMed

    Jagger, R G

    1996-12-01

    Thermoforming of polymethyl methacrylate sheet is used to produce a number of different types of dental appliances. The purpose of this study was to determine the dimensional accuracy of thermoformed polymethyl methacrylate specimens. Five blanks of the acrylic resin were thermoformed on stone casts prepared from a silicone mold of a brass master die. The distances between index marks were measured both on the cast and on the thermoformed blanks with an optical comparator. Measurements on the blanks were made again 24 hours after processing and then 1 week, 1 month, and 3 months after immersion in water. Linear shrinkage of less than 1% (range 0.37% to 0.52%) was observed 24 hours after removal of the blanks from the cast. Immersion of the thermoformed specimens in water resulted in an increase in measured dimensions, but after 3 months' immersion these increases were still less than those of the cast (range 0.07% to 0.18%). It was concluded that it is possible to thermoform Perspex polymethyl methacrylate accurately.

  15. Synthesis and characterization of poly(methyl methacrylate)-based experimental bone cements reinforced with TiO2-SrO nanotubes.

    PubMed

    Khaled, S M Z; Charpentier, Paul A; Rizkalla, Amin S

    2010-08-01

    In an attempt to overcome existing limitations of experimental bone cements we here demonstrate a simple approach to synthesizing strontium-modified titania nanotubes (n-SrO-TiO(2) tubes) and functionalize them using the bifunctional monomer methacrylic acid. Then, using 'grafting from' polymerization with methyl methacrylate, experimental bone cements were produced with excellent mechanical properties, radiopacity and biocompatibility. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive spectroscopy mapping and backscattered SEM micrographs revealed a uniform distribution of SrO throughout the titanium matrix, with retention of the nanotubular morphology. Nanocomposites were then reinforced with 1, 2, 4 and 6 wt.% of the functionalized metal oxide nanotubes. Under the mixing and dispersion regime employed in this study, 2 wt.% appeared optimal, exhibiting a more uniform dispersion and stronger adhesion of the nanotubes in the poly(methyl methacrylate) matrix, as shown by TEM and SEM. Moreover, this optimum loading provided a significant increase in the fracture toughness (K(IC)) (20%) and flexural strength (40%) in comparison with the control matrix (unfilled) at P<0.05. Examination of the fracture surfaces by SEM showed that toughening was provided by the nanotubes interlocking with the acrylic matrix and crack bridging during fracture. On modifying the n-TiO(2) tubes with strontium oxide the nanocomposites exhibited a similar radiopacity to a commercial bone cement (CMW 1), while exhibiting a significant enhancement of osteoblast cell proliferation (242%) in vitro compared with the control at P<0.05.

  16. Four-year follow-up of a polymethyl methacrylate-based bone cement graft for optimizing esthetics in maxillary anterior implants: a case report.

    PubMed

    Torres, Érica Miranda De; Naldi, Luis Fernando; Bernades, Karina Oliveira; Carvalho, Alexandre Leite

    2017-01-01

    Tooth loss promotes bone and gingival tissue remodeling, thus breaking the harmony between the residual ridge and natural teeth. This is critical in the anterior region of the mouth, and the integration of several dental specialties is often essential to successful rehabilitation with implants. This article describes a multidisciplinary approach to implant-supported oral rehabilitation in the maxillary anterior region, presenting a new technique for optimizing esthetics in implants. A 19-year-old woman was missing her central and lateral incisors and had 2 dental implants in the lateral incisor sites. The patient exhibited deficient thickness of the alveolar edge, loss of lip support, and absence of gingival architecture, and the implants were improperly placed. A multidisciplinary team created a correct emergence profile through a polymethyl methacrylate-based bone cement graft along with connective tissue grafts. This technique may be a useful therapeutic adjunct in dental implantology, showing good predictability and regular healing procedures.

  17. The Effect of Polymethyl Methacrylate Augmentation on the Primary Stability of Cannulated Bone Screws in an Anterolateral Plate in Osteoporotic Vertebrae: A Human Cadaver Study

    PubMed Central

    Rüger, Matthias; Sellei, Richard M.; Stoffel, Marcus; von Rüden, Christian

    2015-01-01

    Study Design Cohort study. Objective Expandable anterolateral plates facilitate the reduction of posttraumatic deformities of thoracolumbar spine injuries and are commonly used in cases of unstable injuries or compromised bone quality. In this in vitro study, the craniocaudal yield load of the osseous fixation of an anterior angular stable plate fixation system and the effect of polymethyl methacrylate (PMMA) screw augmentation on the primary stability of the screw–bone interface during kyphosis reduction was evaluated in 12 osteoporotic human thoracolumbar vertebrae. Methods The anterolateral stabilization device used for this study is comprised of two swiveling flanges and an expandable midsection. It facilitates the controlled reduction of kyphotic deformities in situ with a geared distractor. Single flanges were attached to 12 thoracolumbar vertebrae. Six specimens were augmented with PMMA by means of cannulated bone screws. The constructs were subjected to static, displacement-controlled craniocaudal loading to failure in a servohydraulic testing machine. Results The uncemented screws cut out at a mean 393 ± 66 N, whereas the cemented screws showed significantly higher yield load of 966 ± 166 N (p < 0.02). We detected no significant correlation between bone mineral density and yield load in this setting. Conclusion Our results indicate that PMMA augmentation is an effective method to increase two- to threefold the primary stability of the screw–bone interface of an anterolateral spine stabilization system in osteoporotic bone. We recommend it in cases of severely compromised bone quality to reduce the risk of screw loosening during initial kyphosis correction and to increase long-term construct stability. PMID:26835201

  18. The Effect of Polymethyl Methacrylate Augmentation on the Primary Stability of Cannulated Bone Screws in an Anterolateral Plate in Osteoporotic Vertebrae: A Human Cadaver Study.

    PubMed

    Rüger, Matthias; Sellei, Richard M; Stoffel, Marcus; von Rüden, Christian

    2016-02-01

    Study Design Cohort study. Objective Expandable anterolateral plates facilitate the reduction of posttraumatic deformities of thoracolumbar spine injuries and are commonly used in cases of unstable injuries or compromised bone quality. In this in vitro study, the craniocaudal yield load of the osseous fixation of an anterior angular stable plate fixation system and the effect of polymethyl methacrylate (PMMA) screw augmentation on the primary stability of the screw-bone interface during kyphosis reduction was evaluated in 12 osteoporotic human thoracolumbar vertebrae. Methods The anterolateral stabilization device used for this study is comprised of two swiveling flanges and an expandable midsection. It facilitates the controlled reduction of kyphotic deformities in situ with a geared distractor. Single flanges were attached to 12 thoracolumbar vertebrae. Six specimens were augmented with PMMA by means of cannulated bone screws. The constructs were subjected to static, displacement-controlled craniocaudal loading to failure in a servohydraulic testing machine. Results The uncemented screws cut out at a mean 393 ± 66 N, whereas the cemented screws showed significantly higher yield load of 966 ± 166 N (p < 0.02). We detected no significant correlation between bone mineral density and yield load in this setting. Conclusion Our results indicate that PMMA augmentation is an effective method to increase two- to threefold the primary stability of the screw-bone interface of an anterolateral spine stabilization system in osteoporotic bone. We recommend it in cases of severely compromised bone quality to reduce the risk of screw loosening during initial kyphosis correction and to increase long-term construct stability.

  19. Elution of antibiotics from poly(methyl methacrylate) bone cement after extended implantation does not necessarily clear the infection despite susceptibility of the clinical isolates.

    PubMed

    Swearingen, Matthew C; Granger, Jeffrey F; Sullivan, Anne; Stoodley, Paul

    2016-02-01

    Chronic orthopedic infections are commonly caused by bacterial biofilms, which are recalcitrant to antibiotic treatment. In many cases, the revision procedure for periprosthetic joint infection or trauma cases includes the implantation of antibiotic-loaded bone cement to kill infecting bacteria via the elution of a strong local dose of antibiotic(s) at the site. While many studies have addressed the elution kinetics of both non-absorbable and absorbable bone cements both in vitro and in vivo, the potency of ALBC against pathogenic bacteria after extended implantation time is not clear. In this communication, we use two case studies, a Viridans streptococci infected total knee arthroplasty (TKA) and a MRSA-polymicrobial osteomyelitis of a distal tibial traumatic amputation (TA) to demonstrate that an antibiotic-loaded poly(methyl methacrylate) (ALPMMA) coated intermedullary rod implanted for 117 days (TKA) and three ALPMMA suture-strung beads implanted for 210 days (TA) retained killing ability against Pseudomonas aeruginosa and Staphylococcus aureus in vitro, despite different clinical efficacies. The TKA infection resolved and the patient progressed to an uneventful second stage. However, the TA infection only resolved after multiple rounds of debridement, IV vancomycin and removal of the PMMA beads and placement of vancomycin and tobramycin loaded calcium sulfate beads.

  20. Pseudoplasticity and setting properties of two-solution bone cement containing poly(methyl methacrylate) microspheres and nanospheres for kyphoplasty and vertebroplasty.

    PubMed

    Rodrigues, D C; Gilbert, J L; Hasenwinkel, J M

    2009-10-01

    The viscosity and setting parameters of acrylic bone cements used for restoring vertebral compression fractures are critical factors in vertebroplasty and kyphoplasty procedures. Cements exhibiting lower viscosities and longer setting times are desired to overcome the difficulty of forcing the dough through small gauge needles and to reduce the risk of cementing them during surgery. However, cement extravasation is of great concern and can result when cements exhibiting lower viscosities are used. Therefore, the viscosity of cements should also be highly pseudoplastic to simultaneously facilitate flow through needles (shear-thinning) and inhibit potentially deleterious extravasation by viscosity recovery at the delivery sites. The viscosity of two-solution bone cement can be manipulated by changes in the polymer-to-monomer ratio and by the incorporation of cross-linked poly(methyl methacrylate), (PMMA), microspheres or nanospheres in the polymer phase. In this study, the effect of the addition of cross-linked PMMA particles to the linear polymer-monomer solution with particle sizes ranging from 20-100 microm (microspheres) and 300-330 nm (nanospheres) is evaluated in terms of cement rheological properties and setting behavior. The addition of cross-linked PMMA particles was observed to reduce the viscosity in comparison to the standard formulation while keeping the pseudoplastic characteristics, and to improve the setting properties by increasing curing time and reducing maximum exotherm significantly.

  1. Elution of antibiotics from poly(methyl methacrylate) bone cement after extended implantation does not necessarily clear the infection despite susceptibility of the clinical isolates

    PubMed Central

    Swearingen, Matthew C.; Granger, Jeffrey F.; Sullivan, Anne; Stoodley, Paul

    2015-01-01

    Chronic orthopedic infections are commonly caused by bacterial biofilms, which are recalcitrant to antibiotic treatment. In many cases, the revision procedure for periprosthetic joint infection or trauma cases includes the implantation of antibiotic-loaded bone cement to kill infecting bacteria via the elution of a strong local dose of antibiotic(s) at the site. While many studies have addressed the elution kinetics of both non-absorbable and absorbable bone cements both in vitro and in vivo, the potency of ALBC against pathogenic bacteria after extended implantation time is not clear. In this communication, we use two case studies, a Viridans streptococci infected total knee arthroplasty (TKA) and a MRSA-polymicrobial osteomyelitis of a distal tibial traumatic amputation (TA) to demonstrate that an antibiotic-loaded poly(methyl methacrylate) (ALPMMA) coated intermedullary rod implanted for 117 days (TKA) and three ALPMMA suture-strung beads implanted for 210 days (TA) retained killing ability against Pseudomonas aeruginosa and Staphylococcus aureus in vitro, despite different clinical efficacies. The TKA infection resolved and the patient progressed to an uneventful second stage. However, the TA infection only resolved after multiple rounds of debridement, IV vancomycin and removal of the PMMA beads and placement of vancomycin and tobramycin loaded calcium sulfate beads. PMID:26527622

  2. DEGRADATION OF POLY(METHYL METHACRYLATE) IN SOLUTION

    EPA Science Inventory

    The rate of degradation of poly(methyl methacrylate) (PMMA) to methyl methacrylate (MMA) was investigated in the liquid phase with toluene as the solvent. The degradation experiments were carried out in a tubular flow reactor at 1000 psig (6.8 MPa) and at four different temperat...

  3. Poly(methyl methacrylate)-cellulose nitrate copolymers. I. Preparation

    SciTech Connect

    Badran, B.M.; Sherif, S.; Abu-Sedira, A.A.

    1981-03-01

    Poly(methyl methacrylate)-cellulose nitrate copolymers were prepared in the form of rods and sheets by bulk polymerization using benzoyl peroxide as initiator. Suspension polymerization did not succeed in preparing poly(methyl methacrylate)-cellulose nitrate copolymers, especially when cellulose nitrate of 11.4% nitrogen content was used. The parameters such as cellulose nitrate concentration, nitrogen content of cellulose nitrate, the amount of initiator and the reaction time, and the temperature are discussed. The prepared copolymers were irradiated for specified periods of up to 11.83 Mrad. It was found that poly(methyl methacrylate)-cellulose nitrate copolymers did not dissolve in any conventional solvent, but they swelled. Swelling decreases with increasing cellulose nitrate concentrations, nitrogen content of cellulose nitrate, and irradiation dose, indicating the crosslinked structure of the prepared copolymers.

  4. Optimization of a novel two-solution poly(methyl methacrylate) bone cement: Effect of composition on material properties and polymerization kinetics

    NASA Astrophysics Data System (ADS)

    Hasenwinkel, Julie Miller

    A novel two-solution poly(methyl methacrylate) bone cement was developed as an alternative to powder/liquid cements, which are used clinically for the fixation of total joint replacements. This material polymerizes via a free radical mechanism, initiated by the redox reaction of benzoyl peroxide (BPO) and N,N dimethyl-p-toluidine (DMPT). The two-solution concept is advantageous over powder/liquid formulations because it minimizes sources of porosity, produces a homogeneous microstructure, simplifies the mixing and delivery process, and reduces the dependence of material properties on surgical techniques. Experiments were performed to determine the effect of initiation chemistry on the material properties and polymerization kinetics of twelve cement compositions. Select material properties were also evaluated with respect to polymer/monomer ratio and initial polymer molecular weight. The results confirm the hypothesis that initiation chemistry affects material properties via the polymerization kinetics and resulting microstructural properties. The exotherm, setting time, flexural mechanical properties, fracture toughness, fatigue behavior, and residual monomer were evaluated, with respect to initiation chemistry. The flexural strength, modulus, and exotherm were maximized, while the residual monomer was minimized at a BPO:DMPT molar ratio of 1:1. High DMPT concentrations resulted in sub-optimal properties, with short setting times and reduced ductility, fracture toughness, and fatigue strength. Initial polymer molecular weight had no significant effect on the material properties. Polymer conversion and free radical concentration were measured by infrared (FTIR) and electron paramagnetic resonance (EPR) spectroscopy. These data were used to calculate the polymerization reaction rates and kinetic rate constants for each composition. Stoichiometric concentrations of BPO and DMPT maximized the radical concentration and conversion. The BPO and DMPT concentrations

  5. Reconstruction of large cranial defect with alloplastic material (bone cement-cold cure polymethyl-methacrylate resin).

    PubMed

    Hallur, Neelakamal; Goudar, Gayatri; Sikkerimath, Basavaraj; Gudi, Santosh S; Patil, Ravi S

    2010-06-01

    A 40-years-old male patient reported to our department with a chief complaint of persistent palatal fluid discharge and large depressed forehead defect. He gave a history of trauma 20 months back due to head on collision to electric pole and underwent surgery twice for open reduction and fixation of facial skeletal fractures. After 9 months of surgery again a third surgery was performed for the removal of frontal bone due to infection and osteomyelitis at the same site. Extra-oral examination revealed a large fronto-cranial defect extending from superior border of frontal bone to supra-orbital margins bilaterally in length, and from frontal right lateral to frontal left lateral side in width, measuring 8.0 cm in length, 10.5 cm in width and 1.5 to 2.0 cm in depth. Intra-oral sinus fluid discharge was from left posterior palatal region. Preoperative CT was taken and reconstruction of fronto-cranial defect was successfully performed with bone cement. Alloplastic implant reconstruction achieved an excellent esthetic result without any complications.

  6. Two Stage Repair of Composite Craniofacial Defects with Antibiotic Releasing Porous Poly(methyl methacrylate) Space Maintainers and Bone Regeneration

    NASA Astrophysics Data System (ADS)

    Spicer, Patrick

    Craniofacial defects resulting from trauma and resection present many challenges to reconstruction due to the complex structure, combinations of tissues, and environment, with exposure to the oral, skin and nasal mucosal pathogens. Tissue engineering seeks to regenerate the tissues lost in these defects; however, the composite nature and proximity to colonizing bacteria remain difficult to overcome. Additionally, many tissue engineering approaches have further hurdles to overcome in the regulatory process to clinical translation. As such these studies investigated a two stage strategy employing an antibiotic-releasing porous polymethylmethacrylate space maintainer fabricated with materials currently part of products approved or cleared by the United States Food and Drug Administration, expediting the translation to the clinic. This porous space maintainer holds the bone defect open allowing soft tissue to heal around the defect. The space maintainer can then be removed and one regenerated in the defect. These studies investigated the individual components of this strategy. The porous space maintainer showed similar soft tissue healing and response to non-porous space maintainers in a rabbit composite tissue defect. The antibiotic-releasing space maintainers showed release of antibiotics from 1-5 weeks, which could be controlled by loading and fabrication parameters. In vivo, space maintainers releasing a high dose of antibiotics for an extended period of time increased soft tissue healing over burst release space maintainers in an infected composite tissue defect model in a rabbit mandible. Finally, stabilization of bone defects and regeneration could be improved through scaffold structures and delivery of a bone forming growth factor. These studies illustrate the possibility of the two stage strategy for repair of composite tissue defects of the craniofacial complex.

  7. Effect of modification degree of nanohydroxyapatite on biocompatibility and mechanical property of injectable poly(methyl methacrylate)-based bone cement.

    PubMed

    Quan, Changyun; Tang, Yong; Liu, Zhenzhen; Rao, Minyu; Zhang, Wei; Liang, Peiqing; Wu, Nan; Zhang, Chao; Shen, Huiyong; Jiang, Qing

    2016-04-01

    The objective of this study is to prepare a biocompatible nanohydroxyapatite/poly(methyl methacrylate) (HA/PMMA) composite bone cement, which has good mechanical property and can be used for vertebroplasty. Up to 40 wt % of nanohydroxyapatite (nano-HA) in the power, which was surface modified with poly(methylmethacrylate-co-γ-methacryloxypropyl timethoxysilane) [P(MMA-co-MPS)] copolymer, was incorporated into the composite bone cement. The content of P(MMA-co-MPS) on the surface of nano-HA (18.7%, 22.8%, and 26%) was determined through thermogravimetric analysis (TGA). The morphology of biomineralized surface of composite bone cement was observed under scanning electron microscope (SEM). The mechanical measurements of the composite cements implied that the interfacial interaction between the HA and PMMA matrix may be greatly enhanced after surface modification of HA. Biochemical assays indicated that the HA/PMMA bone cement had no cytotoxicity and induced no hemolysis. The cell adhesion and alkaline phosphatase (ALP) activity assays indicated that the biocompatibility of HA/PMMA bone cement could be promoted, demonstrating that it can be used as an ideal weight-bearing bone repair materials on clinical application.

  8. Hardness of irradiated poly(methyl methacrylate) at elevated temperatures

    SciTech Connect

    Lu, K.-P.; Lee, Sanboh; Cheng, Cheu Pyeng

    2001-08-15

    The decrease in hardness induced by gamma irradiation in poly(methyl methacrylate) (PMMA) has been investigated. The hardness is assumed to decrease linearly with the concentration of radiation-induced defects. Annealing at high temperatures induces defect annihilation as tracked by an increase in hardness. The annihilation follows first-order kinetics during isothermal annealing. The dependence of hardness on the reciprocal of the time constant satisfies the Arrhenius equation, and the corresponding activation energy of the kinetic process decreases with increasing dose. The hardness of postannealed PMMA decreases linearly with increasing dose. {copyright} 2001 American Institute of Physics.

  9. Physical properties of agave cellulose graft polymethyl methacrylate

    SciTech Connect

    Rosli, Noor Afizah; Ahmad, Ishak; Abdullah, Ibrahim; Anuar, Farah Hannan

    2013-11-27

    The grafting polymerization of methyl methacrylate and Agave cellulose was prepared and their structural analysis and morphology were investigated. The grafting reaction was carried out in an aqueous medium using ceric ammonium nitrate as an initiator. The structural analysis of the graft copolymers was carried out by Fourier transform infrared and X-ray diffraction. The graft copolymers were also characterized by field emission scanning electron microscopy (FESEM). An additional peak at 1732 cm{sup −1} which was attributed to the C=O of ester stretching vibration of poly(methyl methacrylate), appeared in the spectrum of grafted Agave cellulose. A slight decrease of crystallinity index upon grafting was found from 0.74 to 0.68 for cellulose and grafted Agave cellulose, respectively. Another evidence of grafting showed in the FESEM observation, where the surface of the grafted cellulose was found to be roughed than the raw one.

  10. Physical properties of agave cellulose graft polymethyl methacrylate

    NASA Astrophysics Data System (ADS)

    Rosli, Noor Afizah; Ahmad, Ishak; Abdullah, Ibrahim; Anuar, Farah Hannan

    2013-11-01

    The grafting polymerization of methyl methacrylate and Agave cellulose was prepared and their structural analysis and morphology were investigated. The grafting reaction was carried out in an aqueous medium using ceric ammonium nitrate as an initiator. The structural analysis of the graft copolymers was carried out by Fourier transform infrared and X-ray diffraction. The graft copolymers were also characterized by field emission scanning electron microscopy (FESEM). An additional peak at 1732 cm-1 which was attributed to the C=O of ester stretching vibration of poly(methyl methacrylate), appeared in the spectrum of grafted Agave cellulose. A slight decrease of crystallinity index upon grafting was found from 0.74 to 0.68 for cellulose and grafted Agave cellulose, respectively. Another evidence of grafting showed in the FESEM observation, where the surface of the grafted cellulose was found to be roughed than the raw one.

  11. Positron annihilation investigations on poly(methyl methacrylate)

    NASA Astrophysics Data System (ADS)

    Mohamed, Hamdy F. M.; Abd-Elsadek, Gomaa G.

    2000-06-01

    Positron lifetime and Doppler broadened annihilation radiation were measured for seven different samples of poly(methyl methacrylate) at room temperature in vacuum. The polymerisation of methyl methacrylate was carried out as a bulk polymerisation in the presence of benzoyl peroxide as an initiator. The effect of the amount of the initiator on the viscosity-average molecular weight was studied. It was found that the viscosity-average molecular weight decreased with increasing amount of the initiator. The average lifetime and intensity of ortho-positronium ( o-Ps) increased with increasing viscosity-average molecular weight up to 6.85 × 10 4 and remained constant after that. The S-parameter showed a similar behaviour as that of the o-Ps intensity.

  12. Porous conductive polyblends of polyaniline in poly(methyl methacrylate)

    NASA Astrophysics Data System (ADS)

    Price, Aaron D.; Naguib, Hani E.

    2008-03-01

    The conductive polymer polyaniline is typically blended with conventional industrial thermoplastics in order to obtain an electrically conductive polymer blend with adequate mechanical properties. Processing these polyblends into foams yields a porous conductive material that exhibits immense application potential such as dynamic separation media and low-density electrostatic discharge protection. In the current study, the morphology of a thermally-processable blend consisting of an electrically conductive polyaniline-dodecylbenzene sulfonic acid complex and poly(methyl methacrylate) is explored using a two-phase batch foaming setup. The effect of blend composition and processing parameters on the resulting cellular morphology is investigated. Finally, the impact of the underlying microstructure on the frequency dependent electrical conductivity is elucidated.

  13. A review of methods used to reinforce polymethyl methacrylate resin.

    PubMed

    Vallittu, P K

    1995-09-01

    Various methods to reinforce acrylic denture base material have been used to repair fractures in complete dentures. Metal wires and plates have been tested as reinforcement of polymethyl methacrylate (PMMA) resin. The contributions of the studies conducted on this biphase composite system are discussed in this review article. The literature has reported that even thin metal wires incorporated into the PMMA matrix increased the transverse strength of the PMMA construction. Metal mesh inserted into PMMA resin had negligible effects on the transverse strength of the restoration. macroscopic retention of the metal strengtheners to the PMMA had only a minor effect on the strength in contrast to microscopic retention, which showed a more marked effect. Chemical bonding between the PMMA and metal reinforcer enhanced the strength of the prosthesis with some exceptions.

  14. Degradation of poly(methyl methacrylate) in solution

    SciTech Connect

    Madras, G.; Smith, J.M.; McCoy, B.J.

    1996-06-01

    The rate of degradation of poly(methyl methacrylate) (PMMA) to methyl methacrylate (MMA) was investigated in the liquid phase with toluene as the solvent. The degradation experiments were carried out in a tubular flow reactor at 1,000 psig (6.8 MPa) and at four different temperatures (200, 225, 275, and 300 C). The polymer concentration was varied by 1 to 4 g/L. A discrete model for the first-order rate of polymer degradation was derived and compared to the continuous kinetics approach. Both models lead to the same expression for monomer concentration increasing linearly with time. Rate constants were evaluated using the moments of the molecular weight distributions of the reacted and unreacted polymer. The rate was first order in polymer concentration, and the activation energy was 8.4 kcal/mol (34 kJ/mol). This activation energy suggests that the rate controlling step for the thermal degradation of PMMA is the depropagation process.

  15. Antibacterial Adhesion of Polymethyl Methacrylate Modified by Borneol Acrylate.

    PubMed

    Sun, Xueli; Qian, Zhiyong; Luo, Lingqiong; Yuan, Qipeng; Guo, Ximin; Tao, Lei; Wei, Yen; Wang, Xing

    2016-10-07

    Polymethyl methacrylate (PMMA) is a widely used biomaterial. But there is still a challenge facing its unwanted bacterial adhesion, because the subsequent biofilm formation usually leads to failure of related implants. Herein, we present a borneol-modified PMMA based on a facile and effective stereochemical strategy, generating antibacterial copolymer named as P(MMA-co-BA). It was synthesized by free radical polymerization and studied with different ratio between methyl methacrylate (MMA) and borneol acrylate (BA) monomers. NMR, GPC and EA etc. were used to confirm their chemical features. Their films were challenged with Escherichia coli (Gram-negative) and Bacillus subtilis (Gram-positive), showing a BA content-dependent antibacterial performance. The minimum effective dose should be 10%. Then in vivo subcutaneous implantations in mice demonstrated their biocompatibilities through routine histotomy and HE staining. Therefore, P(MMA-co-BA)s not only exhibited their unique antibacterial character, but also suggested a potential for the safe usage of borneol-modified PMMA frame and devices for further implantation.

  16. Improvement of holographic thermal stability in phenanthrenequinone-doped poly(methyl methacrylate-co-methacrylic acid) photopolymer

    NASA Astrophysics Data System (ADS)

    Yu, Dan; Liu, Hongpeng; Wang, Heng; Wang, Jian; Jiang, Yongyuan; Sun, Xiudong

    2011-08-01

    Experimental studies of holographic thermal stability in phenanthrenequinone (PQ)-doped poly(methyl methacrylate-co-methacrylic acid) [P(MMA-co-MAA)] photopolymers are presented. A possibility to improve the thermal stability of holograms is demonstrated by doping methacrylic acid (MAA) into the poly(methyl methacrylate) (PMMA) polymer matrix. MAA as a copolymerization monomer can form a more stable polymer matrix with methyl methacrylate (MMA) monomer and increase average molecular weight of photoproducts, which finally depress the diffusion of photoproduct. The optimized MAA concentration copolymerized into P(MMA-co-MAA) polymer matrix can bring nearly a month's lifetime of gratings, which is obviously an improvement over the usual PQ-PMMA material under thermal treatment.

  17. Thermal Properties of Polymethyl Methacrylate Composite Containing Copper Nanoparticles.

    PubMed

    Yu, Wei; Xie, Huaqing; Xin, Sha; Yin, Junshan; Jiang, Yitong; Wang, Mingzhu

    2015-04-01

    Thermal functional Materials have wide applications in thermal management fields, and inserting highly thermal conductive materials is effective in enhancing thermal conductivity of matrix. In this paper, copper nanoparticles were selected as the additive to prepare polymethyl methacrylate (PMMA) based nanocomposite with enhanced thermal properties. Uniform copper nanoparticles with pure face-centered lattice were prepared by liquid phase reduction method. Then, they were added into PMMA/N, N-Dimethylmethanamide (DMF) solution according to the different mass fraction for uniform dispersion. After DMF was evaporated, Cu-PMMA nanocomposites were gained. The thermal analysis measurement results showed that the decomposition temperature of nanocomposites decreased gradually with the increasing particle loadings. The thermal conductivity of the Cu-PMMA nanocomposites rose with the increasing contents of copper nanoparticles. With a 20 vol.% addition, the thermal conductivity was up to 1.2 W/m · K, a 380.5% increase compared to the pure PMMA. The results demonstrate that copper nanoparticles have great potential in enhancing thermal transport properties of polymer.

  18. Wettability interpretation of oxygen plasma modified poly(methyl methacrylate).

    PubMed

    Chai, Jinan; Lu, Fuzhi; Li, Baoming; Kwok, Daniel Y

    2004-12-07

    Poly(methyl methacrylate) (PMMA) has been modified via a dc pulsed oxygen plasma for different treatment times. The modified surfaces were characterized by X-ray photoelectron spectroscopy (XPS), optical profilometer, zeta potential, and advancing contact angle measurements. The measured advancing contact angles of water decreased considerably as a function of discharge. Several oxygen-based functionalities (carbonyl, carboxyl, carbonate, etc.) were detected by XPS, while zeta potential measurements confirmed an increase in negative charge for the treated PMMA surface. Evaluating the correlation between the concentration of polar chemical species and zeta potential, we found that increase in surface hydrophilicity results from the coeffect due to incorporation of oxygen functional groups and creation of charge states. The electrical double layer (EDL) effect was also considered in contact angle interpretation by introducing an additional surface tension term into Young's equation. We also found that EDL contribution to the solid-liquid interfacial tension is negligible and can be safely ignored for the systems considered here.

  19. Development of an anthropomorphic head phantom using dolomite and polymethyl methacrylate for dosimetry in computed tomography

    NASA Astrophysics Data System (ADS)

    Ximenes, R. E.; Silva, A.; Balbino, D.; Poletti, M. E.; Maia, A. F.

    2015-12-01

    A real human skull was selected to be a mold for the construction of an anthropomorphic head phantom with a mixture of dolomite and polymethyl methacrylate (PMMA). Using linear attenuation coefficients, we show that it is possible to use dolomite as a bone simulator as long as the proportion of the mixture is 1:1. Acrylic tubes were placed in the phantom constructed to enable the insertion of the ionization chamber to estimate the effective dose. Values for a typical head computed tomography examination found in the literature vary from 0.9 to 4.0 mSv. Dosimetric studies showed that the effective dose for the anthropomorphic phantom was (2.70±0.03) mSv and for the geometric PMMA phantom (3.67±0.04) mSv, values which are in agreement with the intervals reported in the literature. The investment to produce the phantom was approximately US160.00.

  20. Effect of methacrylic acid:methyl methacrylate monomer ratios on polymerization rates and properties of polymethyl methacrylates.

    PubMed

    Chen, T; Kusy, R P

    1997-08-01

    Five binary formulations were prepared from methyl methacrylate (MMA) and methacrylic acid (MAA) monomers, and six ternary formulations were prepared from polysols of 30% wt polymethyl methacrylate (PMMA)/MMA and MAA. Using thermal analyses (DSC and TGA) the polymerization kinetics, condition of postcuring, relative amount of residual monomers, and glass transition temperature (Tg) were determined. From bar-shaped samples, 25 x 5 x 0.9 mm in dimensions, mechanical properties [flexural moduli (E) and maximum strengths (sigma)] were measured in three-point bending. Polymerization kinetics of binary formulations improved over pure PMMA (from 15 to 4 min) as a result of over a 60-fold increase in propagation-to-termination constants (Kp/Kt) of MAA/MMA. The further addition of PMMA increased the viscosity, slowed down termination, and, consequently, improved the polymerization kinetics twofold. These enhancements occurred without a substantive change in the Tg of the ternary system (ca. 107 degrees C) over pure PMMA (ca. 112 degrees C). Moreover, the Es of the four ternary formulations averaged 2.94 GPa, which was comparable with many values reported in the literature. In contrast the sigma s of these same formulations averaged 97 MPa, which was about 25% better than earlier investigations of pure acrylic. When a thermoplastic material is required for pultruding profiles that cure fast and have good thermal-mechanical properties, ternaries of PMMA/MMA/MAA should be considered.

  1. Toughening epoxy resin with poly(methyl methacrylate)-grafted natural rubber

    SciTech Connect

    Rezaifard, A.H.; Hodd, K.A.; Barton, J.M.

    1993-12-31

    A novel rubber, poly(methyl methacrylate)-g-natural rubber (Hevea-plus MG), has been studied as a toughening agent for bisphenol A diglycidyl ether (Shell 828 epoxy resin) cured with piperidine. Effective dispersions of the rubber, in concentrations of 2-10 parts per hundred parts resin, were achieved by adjusting the solubility parameter of the epoxy to approximate that of poly(methyl methacrylate) by adding bisphenol A. The fracture energy of the rubber-modified resin was determined by compact tension tests (in the temperature range -60 to +40{degrees}C) and by Charpy impact tests. The poly(methyl methacrylate)-g-natural rubber was found to be an effective toughening agent for the epoxy resin at both low and high rates of strain. Possible fracture mechanisms are discussed. 22 refs., 16 figs., 5 tabs.

  2. The Mark-Houwink-Sakurada Relation for Poly(Methyl Methacrylate)

    NASA Astrophysics Data System (ADS)

    Wagner, Herman L.

    1987-04-01

    In this third review of a series, the literature values for the viscosity-molecular weight relationship (Mark-Houwink-Sakurada) for poly(methyl methacrylate) have been critically evaluated. Although most of the studies have been concerned with conventionally produced poly(methyl methacrylate), some work has also been done with the isotactic polymer. The Mark-Houwink relations for the following solvents are discussed: benzene, toluene, acetone, chloroform, 2-butanone, and tetrahydrofuran, as well as for several other infrequently used solvents. The values of the coefficient K in the relation [η]=KM0.5 for several theta solvents are also reported.

  3. The effect of poly(methyl methacrylate) surface treatments on the adhesion of silicone-based resilient denture liners.

    PubMed

    Cavalcanti, Yuri Wanderley; Bertolini, Martinna Mendonça; Cury, Altair Antoninha Del Bel; da Silva, Wander José

    2014-12-01

    Different surface treatment protocols of poly(methyl methacrylate) have been proposed to improve the adhesion of silicone-based resilient denture liners to poly(methyl methacrylate) surfaces. The purpose of this study was to evaluate the effect of different poly(methyl methacrylate) surface treatments on the adhesion of silicone-based resilient denture liners. Poly(methyl methacrylate) specimens were prepared and divided into 4 treatment groups: no treatment (control), methyl methacrylate for 180 seconds, acetone for 30 seconds, and ethyl acetate for 60 seconds. Poly(methyl methacrylate) disks (30.0 × 5.0 mm; n = 10) were evaluated regarding surface roughness and surface free energy. To evaluate tensile bond strength, the resilient material was applied between 2 treated poly(methyl methacrylate) bars (60.0 × 5.0 × 5.0 mm; n = 20 for each group) to form a 2-mm-thick layer. Data were analyzed by 1-way ANOVA and the Tukey honestly significant difference tests (α = .05). A Pearson correlation test verified the influence of surface properties on tensile bond strength. Failure type was assessed, and the poly(methyl methacrylate) surface treatment modifications were visualized with scanning electron microscopy. The surface roughness was increased (P < .05) by methyl methacrylate treatment. For the acetone and ethyl acetate groups, the surface free energy decreased (P < .05). The tensile bond strength was higher for the methyl methacrylate and ethyl acetate groups (P < .05). No correlation was found regarding surface properties and tensile bond strength. Specimens treated with acetone and methyl methacrylate presented a cleaner surface, whereas the ethyl acetate treatment produced a porous topography. The methyl methacrylate and ethyl acetate surface treatment protocols improved the adhesion of a silicone-based resilient denture liner to poly(methyl methacrylate). Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc

  4. Preparation of Optically Transparent Films of Poly(methyl methacrylate) (PMMA) and Montmorillonite

    DTIC Science & Technology

    2001-11-01

    methacrylate] [PMMA] and Montmorillonite DISTRIBUTION: Approved for public release, distribution unlimited This paper is part of the following report...Society V6.4 Preparation of Optically Transparent Films of Poly(methyl methacrylate) (PMMA) and Montmorillonite Elena Vasiliul, Chyi-Shan Wang"’ 2...exchanged with 1.40 meq/g of dimethyl dehydrogenated tallow ammonium from a sodium montmorillonite , Cloisite Na+ (CNa). Since the cation-exchange

  5. Customized Polymethyl Methacrylate Implants for the Reconstruction of Craniofacial Osseous Defects

    PubMed Central

    Fernandes da Silva, André Luis; Borba, Alexandre Meireles; Simão, Niverso Rodrigues; Pedro, Fábio Luis Miranda

    2014-01-01

    Craniofacial defects represent alterations in the anatomy and morphology of the cranial vault and the facial bones that potentially affect an individual's psychological and social well-being. Although a variety of techniques and restorative procedures have been described for the reconstruction of the affected area, polymethyl methacrylate (PMMA), a biocompatible and nondegradable acrylic resin-based implant, is the most widely used alloplastic material for such craniomaxillofacial reconstruction. The aim of this study was to describe a technique for aesthetic and functional preoperative customized reconstruction of craniofacial bone defects from a small series of patients offered by the Brazilian public health system. Three adult male patients attended consultation with chief complaints directly related to their individual craniofacial bone defects. With the aid of multislice computed tomography scans and subsequent fabrication of the three-dimensional craniofacial prototype, custom-made PMMA implants were fabricated preoperatively. Under general anesthesia, with access to the craniofacial defects with a coronal approach, the PMMA implants were adapted and fixated to the facial skeleton with titanium plates and screws. Postoperative evaluation demonstrated uneventful recovery and an excellent aesthetic result. Customized prefabricated PMMA implants manufactured over the rapid prototyping models proved to be effective and feasible. PMID:25093139

  6. The effect of processing conditions on the properties of poly(methyl methacrylate) fibers.

    PubMed

    Wright, Debra D; Lautenschlager, Eugene P; Gilbert, Jeremy L

    2002-01-01

    Brittle failure of bone cement remains a problem for the long-term stability of hip prostheses. Fibers have been developed from poly(methyl methacrylate) (PMMA) that retain the chemistry of bone cement, but improve the mechanical properties greatly. To fabricate the fibers, a polymer melt is extruded out of a small die (spinneret) and pulled onto a take-up wheel. Varying the speed of extrusion and temperature of the melt can control the viscosity of the molten polymer. This study examines the effect of melt viscosity on the resultant properties of fibers fabricated from PMMA. The goals are to optimize fiber processing and determine processing-structure--property relationships. Resultant fibers had moderate to high levels of retained molecular orientation, and ultimate tensile strengths (UTS) ranging from 60 to 225 MPa, moduli from 1.5 to 3.5 GPa, and strain to failure from 10 to 40%. Fibers fabricated at a constant viscosity and draw velocity had identical properties, whereas decreasing the viscosity generally increased the mechanical properties and retained orientation. Linear regression models were constructed to predict how the processing variables affect the structure (orientation) of the fiber and how the structure affects the UTS. This can be used to design efficient processing methods for PMMA fibers.

  7. Process for producing a well-adhered durable optical coating on an optical plastic substrate. [abrasion resistant polymethyl methacrylate lenses

    NASA Technical Reports Server (NTRS)

    Kubacki, R. M. (Inventor)

    1978-01-01

    A low temperature plasma polymerization process is described for applying an optical plastic substrate, such as a polymethyl methacrylate lens, with a single layer abrasive resistant coating to improve the durability of the plastic.

  8. Estimation of monomer content in polymethyl methacrylate contact lens materials by Raman spectroscopy.

    PubMed

    Kantarci, Z; Aksoy, S; Hasirci, N

    1997-07-01

    Polymethyl methacrylate is the most commonly used contact lens material due to its excellent optical properties. However the presence of residual monomer in the structure alters its transparency as well as its biocompatibility, thus, there is a need to detect any remaining methyl methacrylate. Raman spectroscopy is a rapid, sensitive, and non destructive method as compared to other spectroscopic, chromatographic or polarographic methods. In this study, the spectra of some lens materials (prepared from methyl methacrylate, 2-hydroxy ethyl methacrylate, Hexamethyl disiloxane and polypropylene glycol with or without the addition of crosslinker ethylene glycol dimethylacrylate) were obtained by Raman spectroscopy. It was observed that an amount of crosslinker present in the structure proves effective for the unpolymerized monomer content. None of the samples, except those containing nexamethyl disiloxane, demonstrated any monomer residue.

  9. Fabrication slab waveguide based polymethyl methacrylate (PMMA) with spin coating method

    NASA Astrophysics Data System (ADS)

    Andriawan, Alan; Pramono, Yono Hadi; Masoed, Asnawi

    2016-11-01

    Fabrication and characterization slab waveguide based polymethyl methacrylate (PMMA) has been carried out. Slab waveguide fabrication done by the spin coating method. Slab waveguide fabrication process carried out by the rotational speed of 1000, 2000, and 3000 rpm respectively played for 10 seconds. Then the slab waveguides heated using a hot plate. Heating process starting from room temperature then increased 5°C to 70°C with a 5 minute warm-up time interval. From the results of characterization fabricated slab waveguides to determine the film thickness is made. Then made observations on the waveguide by passing the light beam He-Ne laser on the thin layer through a single mode optical fiber. From the results of characterization is known that the fabrication of a slab waveguide with a layer thickness of 166 μm. From this research it is known that polymethyl methacrylate (PMMA) can be used as a waveguide with a spin coating method.

  10. Effect of epoxidation on 30% poly(methyl methacrylate)-grafted natural rubber polymer electrolytes

    SciTech Connect

    Nazir, Khuzaimah; Aziz, Ahmad Fairoz; Adam, Nurul Ilham; Yahya, Muhd Zu Azhan; Ali, Ab Malik Marwan

    2015-08-28

    Epoxidized 30% poly(methyl methacrylate)-grafted natural rubber (EMG 30) as a polymer host in solid polymer electrolytes (SPEs) has been investigated. EMG30 was synthesized via performicepoxidation method onto 30% poly(methyl methacrylate)-grafted natural rubber (MG30) and the formations of epoxy group were discussed. The EMG30 were characterized by proton nuclear magnetic resonance ({sup 1}HNMR) to investigate their chemical structure and differential scanning calorimeter to determine their crystallinity. A new peak in {sup 1}HNMR spectra (2.71 ppm) confirmed the appearance of epoxy group. SPE based on EMG30 doped with 40 wt% LiCF{sub 3}SO{sub 3} show the highest conductivity. The complexation between EMG30 and LiCF{sub 3}SO{sub 3} were confirmed by attenuated total reflection Fourier transform infrared (ATR-FTIR)

  11. Effect of epoxidation on 30% poly(methyl methacrylate)-grafted natural rubber polymer electrolytes

    NASA Astrophysics Data System (ADS)

    Nazir, Khuzaimah; Aziz, Ahmad Fairoz; Adam, Nurul Ilham; Yahya, Muhd Zu Azhan; Ali, Ab Malik Marwan

    2015-08-01

    Epoxidized 30% poly(methyl methacrylate)-grafted natural rubber (EMG 30) as a polymer host in solid polymer electrolytes (SPEs) has been investigated. EMG30 was synthesized via performicepoxidation method onto 30% poly(methyl methacrylate)-grafted natural rubber (MG30) and the formations of epoxy group were discussed. The EMG30 were characterized by proton nuclear magnetic resonance (1HNMR) to investigate their chemical structure and differential scanning calorimeter to determine their crystallinity. A new peak in 1HNMR spectra (2.71 ppm) confirmed the appearance of epoxy group. SPE based on EMG30 doped with 40 wt% LiCF3SO3 show the highest conductivity. The complexation between EMG30 and LiCF3SO3 were confirmed by attenuated total reflection Fourier transform infrared (ATR-FTIR).

  12. Poly(methyl methacrylate)-cellulose nitrate copolymers. II. Physical and mechanical properties

    SciTech Connect

    Badran, B.M.; Sherif, S.; El-Sheltawi, S.T.; Abu-Sedira, A.A.

    1981-03-01

    Poly(methyl methacrylate)-cellulose nitrate copolymers were prepared by bulk polymerization using benzoyl peroxide as initiator. Cellulose nitrates of two different nitrogen contents (11.4 and 12.2%) were used. The prepared copolymers were ..gamma..-irradiated for specified periods of up to 11.83 Mrad. Their physical and mechanical properties were measured before and after irradiation. The title copolymers showed lower modulus, tensile strength, and elongation at break than poly(methyl methacrylate) itself, but they showed better hardness and abrasian. Irradiation of up to 6.57 Mrad improved the modulus of the copolymers. Hardness and abrasion were improved by increasing cellulose nitrate content. The prepared copolymers that contained cellulose nitrate of 11.4% nitrogen showed secondary transition points. The increase of cellulose nitrate concentration shifted both first and second transition points to relatively higher values.

  13. Durability of Poly(Methyl Methacrylate) Lenses Used in Concentrating Photovoltaic Technology (Revised) (Presentation)

    SciTech Connect

    Miller, D. C.; Carloni, J. D.; Pankow, J. W.; Gjersing, E. L.; To, B.; Packard, C. E.; Kennedy, C. E.; Kurtz, S. R.

    2012-01-01

    Concentrating photovoltaic (CPV) technology recently gained interest based on its expected low levelized cost of electricity, high efficiency, and scalability. Many CPV systems employ Fresnel lenses composed of poly(methyl methacrylate) (PMMA) to obtain a high optical flux density on the cell. The optical and mechanical durability of these lenses, however, is not well established relative to the desired surface life of 30 years. Our research aims to quantify the expected lifetime of PMMA in key market locations (FL, AZ, and CO).

  14. Ultrasonic degradation of poly(methyl methacrylate-co-alkyl acrylate) copolymers.

    PubMed

    Konaganti, Vinod Kumar; Madras, Giridhar

    2010-02-01

    The copolymers, poly(methyl methacrylate-co-methyl acrylate) (PMMAMA), poly(methyl methacrylate-co-ethyl acrylate) (PMMAEA) and poly(methyl methacrylate-co-butyl acrylate) (PMMABA), of different compositions were synthesized and characterized. The effect of alkyl acrylate content, alkyl group substituents and solvents on the ultrasonic degradation of these copolymers was studied. A model based on continuous distribution kinetics was used to study the kinetics of degradation. The rate coefficients were obtained by fitting the experimental data with the model. The linear dependence of the rate coefficients on the logarithm of the vapor pressure of the solvent indicated that vapor pressure is the crucial parameter that controls the degradation process. The rate of degradation increases with an increase in the alkyl acrylate content. At any particular copolymer composition, the rate of degradation follows the order: PMMAMA>PMMAEA>PMMABA. It was observed that the degradation rate coefficient varies linearly with the mole percentage of the alkyl acrylate in the copolymer.

  15. Water absorption of poly(methyl methacrylate) measured by vertical interference microscopy.

    PubMed

    N'Diaye, Mambaye; Pascaretti-Grizon, Florence; Massin, Philippe; Baslé, Michel Felix; Chappard, Daniel

    2012-08-07

    PMMA (poly(methyl methacrylate)) is widely used to prepare orthopedic cements. They are in direct contact with cells and body fluids. PMMA, despite its hydrophobic nature, can absorb ~2% w/w water. We have evaluated by vertical interference microscopy if water absorption can produce a significant swelling in different types of PMMA blocks: pure, with a plasticizer, with a cross-linker, and in two types of commercial bone cements. Graphite rods which do not swell in water were used as internal standard. Hardness, indentation modulus, plastic, and elastic works were determined by nanoindentation under a 25mN fixed force. Vertical interference microscopy was used to image the polymer in the dry state and hydrated states (after 24 h in distilled water). On the surface of the polished polymers (before and after hydration), we measured roughness by the fractal dimension, the swelling in the vertical and the lateral directions. For each polymer block, four images were obtained and values were averaged. Comparison and standardization of the images in the dry and hydrated states were done with Matlab software. The average value measured on the graphite rod between the two images (dried and hydrated) was used for standardization of the images which were visualized in 3D. After grinding, a small retraction was noticeable between the surface of the rod and the polymers. A retraction ring was also visible around the graphite rod. After hydration, only the pure PMMA and bone cements had a significant swelling in the vertical direction. The presence of polymer beads in the cements limited the swelling in the lateral direction. Swelling parameters correlated with the nanoindentation data. PMMA can swell by absorbing a small amount of water and this induces a swelling that varies with the polymer composition and particle inclusions.

  16. Synthesis of poly(methyl urethane) acrylate oligomer using 2-isocyanatoethyl methacrylate for UV curable coating.

    PubMed

    Park, M N; Oh, S W; Ahn, B H; Moon, M J; Kang, Y S

    2009-02-01

    The poly(methyl urethane) acrylate oligomer was obtained by the reaction of methyl acrylate oligomer and 2-isocyanatoethyl methacrylate. Synthesis of poly(methyl urethane) acrylate oligomer was done with 2-mercaptoethanol (2-MEOH), methyl acrylate, 2,2'-azobisisobutyronitrile (AIBN, initiator) and dibutyltin dilaurate as a catalyst. Then 2-MEOH was used for functional chain transfer agent. The structure and property of the synthesized oligomers were characterized by FT-IR, FT-NMR, rheometer, and DSC. In this study, by synthetic method including the addition of 2-isocyanatoethyl methacrylate, thermal behavior of synthesized material was improved more than that reported in the previous study. Poly(methyl urethane) oligomer can be used for UV curable coatings, inks and adhesives. UV curable coating have high resistance against weather, ozone, aging, frictional wear, and heat. Besides they can absorb the shock and resist rust according to the thickness of film. It is used as an adhesive, paint, optical fiber coating agent, and waterproof agent because of these advantages at the present time.

  17. Pilot-scale synthesis and rheological assessment of poly(methyl methacrylate) polymers: perspectives for medical application.

    PubMed

    Linan, Lamia Zuniga; Nascimento Lima, Nádson M; Filho, Rubens Maciel; Sabino, Marcos A; Kozlowski, Mark T; Manenti, Flavio

    2015-06-01

    This work presents the rheological assessment of poly(methyl methacrylate) (PMMA) polymers synthesized in a dedicated pilot-scale plant. This material is to be used for the construction of scaffolds via Rapid Prototyping (RP). The polymers were prepared to match the physical and biological properties required for medical applications. Differential Scanning Calorimetry (DSC) and Size Exclusion Chromatography (SEC) measurements verified that the synthesized polymers were atactic, amorphous and linear in chains. Rheological properties such as viscosity, storage and loss modulus, beyond the loss factor, and creep and recovery were measured in a plate-plate sensor within the viscoelastic linear region. The results showed the relevant influence of the molecular weight on the viscosity and elasticity of the material, and how, as the molecular weight increases, the viscoelastic properties are getting closer to those of human bone. This article demonstrates that by using the implemented methodology it is possible to synthesize a polymer, with properties comparable to commercially-available PMMA.

  18. Hot embossing and thermal bonding of poly(methyl methacrylate) microfluidic chips using positive temperature coefficient ceramic heater.

    PubMed

    Wang, Xia; Zhang, Luyan; Chen, Gang

    2011-11-01

    As a self-regulating heating device, positive temperature coefficient ceramic heater was employed for hot embossing and thermal bonding of poly(methyl methacrylate) microfluidic chip because it supplied constant-temperature heating without electrical control circuits. To emboss a channel plate, a piece of poly(methyl methacrylate) plate was sandwiched between a template and a microscopic glass slide on a positive temperature coefficient ceramic heater. All the assembled components were pressed between two elastic press heads of a spring-driven press while a voltage was applied to the heater for 10 min. Subsequently, the embossed poly(methyl methacrylate) plate bearing negative relief of channel networks was bonded with a piece of poly(methyl methacrylate) cover sheet to obtain a complete microchip using a positive temperature coefficient ceramic heater and a spring-driven press. High quality microfluidic chips fabricated by using the novel embossing/bonding device were successfully applied in the electrophoretic separation of three cations. Positive temperature coefficient ceramic heater indicates great promise for the low-cost production of poly(methyl methacrylate) microchips and should find wide applications in the fabrication of other thermoplastic polymer microfluidic devices.

  19. Fracture resistance of Kevlar-reinforced poly(methyl methacrylate) resin: a preliminary study.

    PubMed

    Berrong, J M; Weed, R M; Young, J M

    1990-01-01

    The reinforcing effect of Kevlar fibers incorporated in processed poly(methyl methacrylate) resin samples was studied using 0% (controls), 0.5%, 1%, and 2% by weight of the added fibers. The samples were subjected to impact testing to determine fracture resistance, and sample groups were statistically compared using an ANOVA. Each reinforced sample had significantly greater fracture resistance (P less than 0.05) than the control, and no difference was found either within or between control groups. The use of reinforcing Kevlar fibers appears to enhance the fracture resistance of acrylic resin denture base materials.

  20. Emission from Polymethyl Methacrylate Irradiated by a Beam of Runaway Electrons of Subnanosecond Pulse Durations

    NASA Astrophysics Data System (ADS)

    Baksht, E. Kh.; Burachenko, A. G.; Beloplotov, D. V.; Tarasenko, V. F.

    2016-08-01

    Spectral and amplitude-temporal characteristics of emission from polymethyl methacrylate (fiberglass, PMMA) irradiated with a beam of runaway electrons of subnanosecond duration are investigated. It is found that at the beam current pulse duration within 200-600 ps at half maximum and the beam current density 10-200 A/cm2, the intensity maximum is registered at the wavelength ~490 nm and the emission pulse FWHM in the visible spectrum is ~1.5 ns at the half width. It is shown that the main contribution into the emission comes from luminescence.

  1. Turning electrospun poly(methyl methacrylate) nanofibers into graphitic nanostructures by in situ electron beam irradiation

    SciTech Connect

    Duan, H. G.; Xie, E. Q.; Han, L.

    2008-02-15

    Using ultrathin electrospun poly(methyl methacrylate) (PMMA) nanofibers as precursor, graphitic nanofibers, nanobridges, nanocones, and fullerenelike onions could be prepared by electron beam irradiation in a controlled manner. With the help of the high resolution transmission electron microscopy, the real time processing of the carbonization and graphitization of the PMMA nanofibers could be investigated. This way to obtain graphitic nanostructures has promising applications in graphitic carbon nanostructure electronics and devices. Because PMMA is a widely used standard high resolution electron resist, this graphitization could be combined with electron beam lithography to obtain high resolution patterned graphitic circuits.

  2. Surface smoothing of poly(methyl methacrylate) film by laser induced photochemical etching

    NASA Astrophysics Data System (ADS)

    Kang, JoonHyun; Lee, Song-ee; Park, Joon-Suh; Kim, Young-Hwan; Han, Il Ki

    2017-09-01

    The surface of poly(methyl methacrylate) (PMMA) film was etched by laser irradiation under O2 and vacuum conditions. By activating the O2 molecules near the rough surface, oxygen radicals will preferably etch the protrusions on the PMMA surface. Three lasers of different wavelengths were used for comparison. Laser irradiation at a short wavelength such as 325 nm resulted in high etch rates whereas a long wavelength such as 532 nm resulted in no effect on the surface profile. The PMMA surface was not etched under the vacuum condition, indicating the necessity of O2 molecules in etching.

  3. Properties of Eu3+ doped poly(methyl methacrylate) optical fiber

    NASA Astrophysics Data System (ADS)

    Miluski, Piotr; Kochanowicz, Marcin; Zmojda, Jacek; Dorosz, Dominik

    2017-02-01

    The proposition of trivalent europium as a luminescent dopant in poly(methyl methacrylate) (PMMA) host is presented. Optical characterization and fabrication technology of the Eu3+ doped polymeric fiber is shown. The proposed luminescent material exhibits an intense luminescence under 355- and 405-nm excitation. Additionally, the measured decay time (0.51 ms, D→F transition) at third harmonic Nd:YAG excitation showed low luminescence quenching in Eu3+ chelate doped PMMA. The luminescent properties and influence of spectral attenuations on the luminescence shape in fabricated fibers are also presented.

  4. Antibacterial properties of novel poly(methyl methacrylate) nanofiber containing silver nanoparticles.

    PubMed

    Kong, Hyeyoung; Jang, Jyongsik

    2008-03-04

    Poly(methyl methacrylate) (PMMA) nanofiber containing silver nanoparticles was synthesized by radical-mediated dispersion polymerization and applied to an antibacterial agent. UV-vis spectroscopic analysis indicated that the silver nanoparticles were continually released from the polymer nanofiber in aqueous solution. The antibacterial properties of silver/PMMA nanofiber against both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria were evaluated using minimum inhibitory concentration (MIC), the modified Kirby-Bauer method, and a kinetic test. The MIC test demonstrated that the silver/PMMA nanofiber had enhanced antimicrobial efficacy compared to that of silver sulfadiazine and silver nitrate at the same silver concentration.

  5. Femtosecond laser fabrication of tubular waveguides in poly(methyl methacrylate).

    PubMed

    Zoubir, Arnaud; Lopez, Cedric; Richardson, Martin; Richardson, Kathleen

    2004-08-15

    Femtosecond laser direct writing is employed for the fabrication of buried tubular waveguides in bulk poly(methyl methacrylate). A novel technique using selective chemical etching is presented to resolve the two-dimensional refractive-index profile of the fabrication structures. End-to-end coupling in the waveguides reveals a near-field intensity distribution that results from the superimposition of several propagating modes with different azimuthal symmetries. Mode analysis of the tubular waveguides is performed using the finite-difference method, and the possible propagating mode profiles are compared with the experimental data.

  6. Far infrared-assisted encapsulation of filter paper strips in poly(methyl methacrylate) for proteolysis.

    PubMed

    Chen, Qiwen; Bao, Huimin; Zhang, Luyan; Chen, Gang

    2016-02-01

    Filter paper strips were enclosed between two poly(methyl methacrylate) plates to fabricate paper-packed channel microchips under pressure in the presence of far infrared irradiation. After the enclosed paper strip was oxidized by periodate, trypsin was covalently immobilized in them to fabricate microfluidic proteolysis bioreactor. The feasibility and performance of the unique bioreactor were demonstrated by digesting BSA and lysozyme. The results were comparable to those of conventional in-solution proteolysis while the digestion time was significantly reduced to ∼18 s. The suitability of the microfluidic paper-based bioreactors to complex proteins was demonstrated by digesting human serum.

  7. Thermo-reversible gelation of atactic poly(methyl methacrylate) in poly(ethylene glycol) oligomers.

    PubMed

    Gao, Yun; Yu, Chunhong; Chen, Minzhi; Wang, Xiaoliang; Zhou, Dongshan; Xue, Gi

    2013-04-01

    The temperature-concentration behavior of physical gel by atactic poly(methyl methacrylate) (aPMMA) in poly(ethylene glycol) oligomer (PEG400) was investigated. A liquid-liquid demixing interferes with a glass transition during cooling. The combination of demixing and T g leads to the formation of amorphous gels at low temperature. We suggest that the gelation of aPMMA/PEG400 is a glassy gel, in which short-range attractive depletion interaction in the polymer/oligomer system was the driving force at molecular level.

  8. Preparation of poly(methyl methacrylate) grafted hydroxyapatite nanoparticles via reverse ATRP.

    PubMed

    Wang, Yan; Xiao, Yan; Huang, Xiujuan; Lang, Meidong

    2011-08-15

    Surface-initiated reverse atom transfer radical polymerization (reverse ATRP) technical was successfully employed to modify hydroxyapatite (HAP) nanoparticles with poly(methyl methacrylate) (PMMA). The peroxide initiator moiety for reverse ATRP was covalently attached to the HAP surface through the surface hydroxyl groups. Reverse ATRP of methyl methacrylate (MMA) from the initiator-functionalized HAP was carried out, and the end bromide groups of grafted PMMA initiated ATRP of MMA subsequently. Fourier transformation infrared (FTIR) spectroscopy, thermal gravimetric analysis (TGA) and transmission electron microscopy (TEM) were employed to confirm the grafting and to characterize the nanoparticle structure. The grafted PMMA gave HAP nanoparticles excellent dispersibility in MMA monomer. As the amount of grafted PMMA increased, the dispersibility of surface-grafted HAP and the compressive strength of HAP/PMMA composites were improved.

  9. Carbon black reinforced polymethyl methacrylate (PMMA)-based composite particles: preparation, characterization, and application

    NASA Astrophysics Data System (ADS)

    Liang, Tian; Yan, Chunjie; Zhou, Sen; Zhang, Yonghan; Yang, Bipeng

    2017-10-01

    Carbon black (CB) is an excellent filler to reinforce polymers because of its unique thermal and mechanical properties. Thus, a type of modified carbon black (MCB) was developed, which led to reduced filler aggregation in methyl methacrylate (MMA) monomers and resulted in homogeneous dispersion in the polymethyl methacrylate (PMMA) substrate. The PMMA-MCB composite particles that were prepared in this work possessed remarkable and stable properties. Therefore, they can be used as an ultra-lightweight proppant (ULWP). Fourier transform infrared spectroscopy showed that CB was successfully modified and the MCB was well dispersed in the PMMA matrix. Results of crushing rate and differential scanning calorimetry demonstrated that MCB could significantly enhance the thermal and mechanical performance of the ULWP. Heat treatment of the ULWP under a nitrogen atmosphere could also clearly enhance its performance in various aspects. The process of modifying CB, the approach of synthesizing PMMA-MCB composite particles, and their mechanism were systematically investigated in this work.

  10. Impact strength of denture polymethyl methacrylate reinforced with different forms of E-glass fibers.

    PubMed

    Dikbas, Idil; Gurbuz, Ozlem; Unalan, Fatma; Koksal, Temel

    2013-01-01

    The purpose of this in vitro study was to determine the reinforcing effect of different forms and concentrations of E-glass fibers on impact strength of denture polymethyl methacrylate. A total of 91 rectangular specimens (84 specimens for test groups and seven for control group) of a heat-cured acrylic resin were fabricated. The test specimens were prepared by modifying the polymethyl methacrylate with the addition of different concentrations (2.5%, 3%, 4%, 5% by volume) of three types (chopped strand mat, woven and continuous unidirectional fibers) of E-glass fibers. The impact strength was evaluated using the Charpy method. While the 5% continuous glass fiber added test group showed the highest mean impact strength, the lowest value belonged to the 2.5% woven glass fiber containing group. When the impact strength values of chopped strand mat and continuous unidirectional glass fiber added groups at all concentrations were compared with the control group, the differences were statistically significant. The impact strength values of the woven glass fiber added groups at all concentrations were higher than that of the control group. However, the difference was non-significant. The impact strength of PMMA was enhanced by including E-glass fibers, increasing parallel with the fiber concentration.

  11. Cellulose nanocrystals as a reinforcing material for electrospun poly(methyl methacrylate) fibers: formation, properties and nanomechanical characterization

    Treesearch

    Hong Dong; Kenneth E. Strawhecker; James A. Snyder; Joshua A. Orlicki; Richard S. Reiner; Alan W. Rudie

    2012-01-01

    Uniform fibers composed of poly(methyl methacrylate) (PMMA) reinforced with progressively increasing contents of cellulose nanocrystals (CNCs), up to 41 wt% CNCs, have been successfully produced by electrospinning. The morphological, thermal and nanomechanical properties of the composite sub-micron fibers were investigated. The CNCs derived from wood pulp by sulfuric...

  12. Formulation and characterization of antimicrobial quaternary ammonium dendrimer in poly(methyl methcarylate) bone cement.

    PubMed

    Abid, C K V Zainul; Jain, Swati; Jackeray, Richa; Chattopadhyay, Sruti; Singh, Harpal

    2017-04-01

    The use of novel antimicrobial molecules in bone cement can improve efficiency of recuperation after arthroplasty or joint replacement surgeries, avoiding the risks associated with antibiotic resistant antimicrobial agents. Nanomaterials particularly dendrimers are particularly useful for making broad spectrum killing agents owing to their large surface areas and functionalities. Therefore, we have synthesized generation 1 quaternary ammonium dendrimer of tripropylene glycol diacrylate (TPGDA) using octyl iodide (OI) [TPGDA G1.0 (=) quaternary octyl iodide (QOI)] and capitalized on their capabilities of contact killing based mechanism. We formulated different TPGDA G1.0 (=) QOI antimicrobial agent loaded liquid component composed of methyl methacrylate monomer and N,N-dimethyl-p-toluidine coinitiator. Different polymethyl methacrylate (PMMA) based experimental bone cement formulations were made and dendrimer concentration was optimized. Mechanical strength and compressive modulus of modified bone cement decreased on increasing concentrations and 10% was optimized for further analysis. The mechanical strength of bone cement yield the similar trend in wet conditions bone cement immersed in artificially created stimulated body fluids. Ten percent TPGDA G1.0 (=) QOI in bone cement was sufficient to kill gram positive and negative bacteria and its property is retained even after a period of 30 days. Thus novel dendritic structures show promise for clinical antimicrobial activity while retaining mechanical properties of bone cements. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 521-530, 2017.

  13. Enhanced surface segregation of poly(methyl methacrylate) end-capped with 2-perfluorooctylethyl methacrylate by introduction of a second block.

    PubMed

    Ni, Huagang; Gao, Jie; Li, Xuehua; Hu, Yanyan; Yan, Donghuan; Ye, XiuYun; Wang, Xinping

    2012-01-01

    New fluorinated copolymers of poly(methyl methacrylate)-b-poly(butyl methacrylate) or poly(n-octadecyl methacrylate) end-capped with 2-perfluorooctylethyl methacrylate (PMMA(x)-b-PBMA(y)-ec-PFMA(z) or PMMA(x)-b-PODMA(y)-ec-PFMA(z)) were synthesized by living atom transfer radical polymerization. Thin films made of PMMA(230)-b-PODMA(y)-ec-PFMA(1) were characterized by differential scanning calorimetry, angle-resolved X-ray photoelectron spectroscopy and X-ray diffraction. These films were found to exhibit robust surface segregation of the end groups. Furthermore, the fluorine enrichment factor at the film surface was found to increase linearly with increasing degree of polymerization of poly(n-octadecyl methacrylate) and its increasing fusion enthalpy in the second block, which enhances the segregation of the fluorinated moieties.

  14. Robust isocratic liquid chromatographic separation of functional poly(methyl methacrylate).

    PubMed

    Jiang, Xulin; Lima, Vincent; Schoenmakers, Peter J

    2003-11-07

    The separation of telechelic poly(methyl methacrylate) (PMMA) prepolymers based on the number of end-groups under critical liquid chromatography (LC) conditions has been studied using a bare-silica column, which can interact with polar functional groups. The critical solvent compositions for non-functional, mono-functional and bi-functional PMMAs were determined in normal-phase LC using mixtures of acetonitrile and dichloromethane (DCM) of varying composition as the mobile phase. The telechelic prepolymers were successfully separated according to hydroxyl (OH) functionality (with zero, one, or two OH groups, respectively) under the critical conditions, in which fast (5 min), base-line separations were obtained independent of molecular weight. Changing the column temperature, flow rate, and mobile-phase composition within a certain range did not affect the functionality separation. Therefore this isocratic LC separation method is quite robust. Evaporative light-scattering detector (ELSD) calibration curves were used for the quantitative analysis of functional PMMA prepolymers.

  15. Dry-adhesives based on hierarchical poly(methyl methacrylate) electrospun fibers

    NASA Astrophysics Data System (ADS)

    Sahay, Rahul; Baji, Avinash; Parveen, Hashina; Ranganath, Anupama Sargur

    2017-03-01

    Here, we combine electrospinning and replica-molding to produce hierarchical poly(methyl methacrylate) structures and investigate its adhesion behavior. Normal and shear adhesion of these biomimetic hierarchical structures was measured using nanoindentaton and a custom-built apparatus attached to Zwick tensile testing machine, respectively. Shear adhesion was measured by sliding the samples along the glass slide under a predefined normal preload. Normal adhesion was measured by indenting the surface of the sample with the help of a diamond indenter tip and retracting it back to determine the pull-off force needed to detach it from the sample. These experiments were also conducted on neat PMMA fibers to investigate the effect of hierarchy on the adhesion performance of the samples. Our results show that the shear adhesion strength and pull-off forces recorded for the hierarchical samples are higher than those recorded for neat fibers.

  16. Air plasma processing of poly(methyl methacrylate) micro-beads: Surface characterisations

    NASA Astrophysics Data System (ADS)

    Liu, Chaozong; Cui, Nai-Yi; Osbeck, Susan; Liang, He

    2012-10-01

    This paper reports the surface processing of poly(methyl methacrylate) (PMMA) micro-beads by using a rotary air plasma reactor, and its effects on surface properties. The surface properties, including surface wettability, surface chemistry and textures of the PMMA beads, were characterised. It was observed that the air plasma processing can improve the surface wettability of the PMMA microbeads significantly. A 15 min plasma processing can reduce the surface water contact angle of PMMA beads to about 50° from its original value of 80.3°. This was accompanied by about 8% increase in surface oxygen concentration as confirmed by XPS analysis. The optical profilometry examination revealed the air plasma processing resulted in a rougher surface that has a “delicate” surface texture. It is concluded that the surface chemistry and texture, induced by air plasma processing, co-contributed to the surface wettability improvement of PMMA micro-beads.

  17. [Formation of stereocomplexes in atactic poly(methyl methacrylate) studied by FTIR].

    PubMed

    Gu, Q; Shen, D

    2000-10-01

    The stereocomplexation of atactic poly(methyl methacrylate) (a-PMMA) films after isolated from acetone, benzene, and chloroform solution, respectively, was studied by Fourier transformation infrared (FTIR). The results of spectra showed that the stereocomplex was formed for the films cast from acetone and benzene solutions with the appearance of the characteristic bands for the stereocomplex. The population of trans-trans conformers for the i- and s-sequences increased and the side chain preferred to its energetically optimized conformation during the formation of stereocomplex. The stereocomplexes may be formed by the interactions between the i- and s-sequences in the same molecular chain. During the annealing process the self-aggregation of s-sequences played a role in the aggregation process of stereocomplex, which was a function of annealing temperature and annealing time.

  18. Electron capture of dopants in two-photonic ionization in a poly(methyl methacrylate) solid

    SciTech Connect

    Tsuchida, Akira; Sakai, Wataru; Nakano, Mitsuru; Yamamoto, Masahide

    1992-10-29

    Behavior of the electron produced by two-photonic excitation of an aromatic donor in a poly(methyl methacrylate) solid was studied by the addition of the electron scavengers to the system. According to the Perrin type analysis for the two-photonically ejected electron, the capture radii (R{sub c}) of the scavengers examined were estimated to be from 8 to 40 {Angstrom}. For the two-photonically ejected electrons, R{sub c} is a capture radius for thermalized electrons. In this case the parent electron donor is not necessarily within this radius. On the other hand, for the fluorescence quenching, the distance between the donor and acceptor is within the static quenching radius (R{sub q}) of the donor. 13 refs., 4 figs., 2 tabs.

  19. Network formation of nanofibrillated cellulose in solution blended poly(methyl methacrylate) composites.

    PubMed

    Littunen, Kuisma; Hippi, Ulla; Saarinen, Tapio; Seppälä, Jukka

    2013-01-02

    Composites of poly(methyl methacrylate) (PMMA) and nanofibrillated cellulose (NFC) were prepared by solution blending and further processed by injection and compression molding. To improve adhesion at the PMMA/NFC interface, the nanofibrils were covalently grafted with PMMA. Formation of a percolating nanofibril network was observed between 1 and 5 wt.% of NFC by dynamic rotational rheometry in molten state. This observation was further supported by the behavior of glass transition temperature which decreased at low NFC concentrations but recovered above the percolation threshold, indicating a decreased mobility of the matrix polymer. This effect was more pronounced with ungrafted NFC, possibly due to a stronger network. The unmodified NFC induced a minor degradation of the molar mass of PMMA. As thin plates, the composites were transparent at low NFC concentrations but became partially aggregated at the highest NFC concentrations. Despite the continuous NFC network, tensile testing showed no improvement of the mechanical properties. Copyright © 2012 Elsevier Ltd. All rights reserved.

  20. Tensile behaviour of blends of poly(vinylidene fluoride) with poly(methyl methacrylate)

    NASA Technical Reports Server (NTRS)

    Cebe, Peggy; Chung, Shirley Y.

    1990-01-01

    Blends of poly(vinylidene fluoride) (PVF2) and poly(methyl methacrylate) (PMMA) were prepared over a wide concentration range and tested in tension at the same relative temperature below the glass transition. In nearly all blends, under conditions favoring disentanglement, (decrease in strain rate, or increase in test temperature), the yield stress and drawing stress decreased while the breaking strain increased. For materials with about the same degree of crystallinity, those with a higher proportion of amorphous PVF2 exhibited brittle-like behavior as a result of interlamellar tie molecules. In the semicrystalline blends, yield stress remains high as the test temperature approaches Tg, whereas in the amorphous blends the yield stress falls to zero near Tg. Results of physical aging support the role of interlamellar ties which cause semicrystalline blends to exhibit aging at temperatures above Tg.

  1. Raman spectra of bilayer graphene covered with Poly(methyl methacrylate) thin film

    SciTech Connect

    Xia Minggang; Su Zhidan; Zhang Shengli

    2012-09-15

    The Raman spectra of bilayer graphene covered with poly(methyl methacrylate) (PMMA) were investigated. Both the G and 2D peaks of PMMA-coated graphene were stiff and broad compared with those of uncovered graphene. This could be attributed to the residual strain induced by high-temperature baking during fabrication of the nanodevice. Furthermore, the two 2D peaks stiffened and broadened with increasing laser power, which is just the reverse to uncovered graphene. The stiffness is likely caused by graphene compression induced by the circular bubble of the thin PMMA film generated by laser irradiation. Our findings may contribute to the application of PMMA in the strain engineering of graphene nanodevices.

  2. Computational investigation of intermolecular interactions in polymer mixtures: Polycarbonate and poly(methyl methacrylate)

    SciTech Connect

    Fitzwater, S.

    1993-12-31

    Molecular modeling and semiempirical quantum mechanical calculations on model compounds can give us detailed information about specific interactions in polymer mixtures. This study examines interactions between a poly(methyl methacrylate) (PMMA) tetramer and the polycarbonate (PC) repeat unit. The results suggested that PC-PMMA mixtures are stabilizing by hydrogen bonds between a carbonyl oxygen on one polymer and a proton or protons on the other. Multiple hydrogen bonds occur; stabilized generally increases with the number of hydrogen bonds. Several configurations had a PMMA carbonyl O H-bonded to a PC ring H, and the adjacent PC carbyonyl O H-bonded to PMMA methyl and methylene H`s. This suggests that the reduced PC mobility observed in PC-PMMA mixtures arises from suppression of both ring flips and carbonate group motion.

  3. Solid state dye lasers based on LDS 698 doped in modified polymethyl methacrylate.

    PubMed

    Fan, Rongwei; Xia, Yuanqin; Chen, Deying

    2008-06-23

    Broad band solid state dye lasers based on LDS 698 doped in modified polymethyl methacrylate (MPMMA) with laser wavelength about 650 nm were demonstrated. It was demonstrated that the fluorescence spectra of LDS 698 in solid host MPMMA displays an obvious blue shift about 50 nm comparing with that in ethanol solution. The dye concentration has great effect on the laser's performance including laser slope efficiency and lifetime. The lifetime increased dramatically with the increase of the LDS 698 concentration. With pump repetition rate of 10 Hz and intensity of 0.1 J/cm(2), the maximum lifetime 300,000 shots corresponding normalized photostability 102 GJ/mol was obtained with LDS 698 at 1.5 x 10(-4)mol/L.

  4. Corneal endothelial response to refitting polymethyl methacrylate wearers with rigid gas-permeable lenses.

    PubMed

    McLaughlin, R; Schoessler, J

    1990-05-01

    Thirteen persons who had been wearing only polymethyl methacrylate (PMMA) contact lenses for 3 years or more were switched to a contact lens material providing greater oxygen transmissibility (Itafocon A) while keeping other contact lens parameters the same. Monitoring of corneal endothelial cells during the first 4 months of the rigid gas-permeable (RGP) lens daily wear showed no significant change in the coefficient of variation of cell area (polymegethism) or percentage of hexagonal endothelial cells at the end of 4 months. However, paired data did show a small, but significant, decrease in cell density at the end of 4 months (3174 to 2908 cells/mm2). The results suggest that a sudden shift in the general corneal environment toward more available oxygen may have some early effect on endothelial cell density, but changes in endothelial cell size variation and form are not determined.

  5. Facile fabrication of superhydrophobic poly(methyl methacrylate) substrates using ultrasonic imprinting

    NASA Astrophysics Data System (ADS)

    Cho, Young Hak; Seo, Young Soo; Moon, In Yong; Kim, Bo Hyun; Park, Keun

    2013-05-01

    Superhydrophobic surfaces (SHSs) have received increasing attention in the last decade, and have been generally developed from hydrophobic materials. In this study, a facile fabrication method based on ultrasonic imprinting is proposed to develop SHSs from a hydrophilic polymer, poly(methyl methacrylate) (PMMA). To fabricate SHSs on PMMA substrates, micro electrical discharge machining, micromachining and ultrasonic imprinting were sequentially used. The ultrasonic imprinting was performed for various channel designs and imprinting conditions, and the resulting water contact angles were measured for the replicated samples. As a result, superhydrophobic characteristics could be obtained on a hydrophilic PMMA replica without any chemical treatments. The effects of nanoscale roughness on the replicated channel as well as composition change are discussed with respect to the analyses using an atomic force microscope, x-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy.

  6. Synthesis, characterization and stability of chitosan and poly(methyl methacrylate) grafted carbon nanotubes.

    PubMed

    Carson, Laura; Hibbert, Kemar; Akindoju, Feyisayo; Johnson, Chevaun; Stewart, Melisa; Kelly-Brown, Cordella; Beharie, Gavannie; Fisher, Tavis; Stone, Julia; Stoddart, Dahlia; Oki, Aderemi; Neelgund, Gururaj M; Regisford, Gloria; Traisawatwong, Pasakorn; Zhou, Jianren; Luo, Zhiping

    2012-10-01

    The single walled carbon nanotubes (CNTs) were effectively functionalized through grafting with chitosan (CTS) and poly(methyl methacrylate) (PMMA). Prior to grafting reaction, the carboxylated SWNCTs (SWNCTs-COOH) were obtained by treating pristine CNTs with a mixture of 3:1 (v/v) H(2)SO(4) and HNO(3), and the successive treatment of SWNCTs-COOH with SOCl(2) yielded the acylated CNTs (CNTs-COCl). The functionalized derivatives of CNTs were characterized using Fourier transform infrared spectroscopy, thermogravimetric analysis, atomic force microscopy, scanning electron microscopy and transmission electron microscopy. Both CTS and PMMA grafted CNTs showed better dispersability in acetic acid and tetrahydrofuran, in addition to higher stability in solution.

  7. Synthesis, characterization and stability of chitosan and poly(methyl methacrylate) grafted carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Carson, Laura; Hibbert, Kemar; Akindoju, Feyisayo; Johnson, Chevaun; Stewart, Melisa; Kelly-Brown, Cordella; Beharie, Gavannie; Fisher, Tavis; Stone, Julia; Stoddart, Dahlia; Oki, Aderemi; Neelgund, Gururaj M.; Regisford, Gloria; Traisawatwong, Pasakorn; Zhou, Jianren; Luo, Zhiping

    2012-10-01

    The single walled carbon nanotubes (CNTs) were effectively functionalized through grafting with chitosan (CTS) and poly(methyl methacrylate) (PMMA). Prior to grafting reaction, the carboxylated SWNCTs (SWNCTs-COOH) were obtained by treating pristine CNTs with a mixture of 3:1 (v/v) H2SO4 and HNO3, and the successive treatment of SWNCTs-COOH with SOCl2 yielded the acylated CNTs (CNTs-COCl). The functionalized derivatives of CNTs were characterized using Fourier transform infrared spectroscopy, thermogravimetric analysis, atomic force microscopy, scanning electron microscopy and transmission electron microscopy. Both CTS and PMMA grafted CNTs showed better dispersability in acetic acid and tetrahydrofuran, in addition to higher stability in solution.

  8. Nanolubrication of poly(methyl methacrylate) films on Si for microelectromechanical systems applications

    NASA Astrophysics Data System (ADS)

    Satyanarayana, N.; Lau, K. H.; Sinha, S. K.

    2008-12-01

    Polymers, such as poly(methyl methacrylate) (PMMA), are important structural materials for microsystems because of their excellent mechanical properties; however, they suffer from severe problems of adhesion, friction, and wear [B. Bhushan, J. N. Israelachvili, and U. Landman, Nature (London) 374, 607 (1995)]. We report a simple process of O2 plasma treatment on a PMMA film, followed by overcoating with an ultrathin layer of perfluoropolyether (PFPE) which improved tribological performance of the film. O2 plasma on PMMA film has formed unique wavy nanotextured surface and increased the hardness and the elastic modulus of the film, which, together with the nanolurbication by PFPE, has increased the wear life of PMMA film by more than five orders of magnitude.

  9. Tensile behaviour of blends of poly(vinylidene fluoride) with poly(methyl methacrylate)

    NASA Technical Reports Server (NTRS)

    Cebe, Peggy; Chung, Shirley Y.

    1990-01-01

    Blends of poly(vinylidene fluoride) (PVF2) and poly(methyl methacrylate) (PMMA) were prepared over a wide concentration range and tested in tension at the same relative temperature below the glass transition. In nearly all blends, under conditions favoring disentanglement, (decrease in strain rate, or increase in test temperature), the yield stress and drawing stress decreased while the breaking strain increased. For materials with about the same degree of crystallinity, those with a higher proportion of amorphous PVF2 exhibited brittle-like behavior as a result of interlamellar tie molecules. In the semicrystalline blends, yield stress remains high as the test temperature approaches Tg, whereas in the amorphous blends the yield stress falls to zero near Tg. Results of physical aging support the role of interlamellar ties which cause semicrystalline blends to exhibit aging at temperatures above Tg.

  10. Thermal assisted ultrasonic bonding method for poly(methyl methacrylate) (PMMA) microfluidic devices.

    PubMed

    Zhang, Zongbo; Wang, Xiaodong; Luo, Yi; He, Shengqiang; Wang, Liding

    2010-06-15

    A thermal assisted ultrasonic bonding method for poly(methyl methacrylate) (PMMA) microfluidic devices has been presented. The substrates were preheated to 20-30 degrees C lower than glass transition temperature (T(g)) of the polymer. Then low amplitude ultrasonic vibration was employed to generate facial heat at the interface of PMMA substrates. PMMA microfluidic chips were successfully bonded with bulk temperature well below T(g) of the material and with pressure two orders lower than conventional thermal bonding, which was of great benefit to reduce the deformation of microstructures. The bonding process was optimized by Taguchi method. This bonding technique showed numerous superiorities including high bonding strength (0.95MPa), low dimension loss (0.3-0.8%) and short bonding time. Finally, a micromixer was successfully bonded by this method and its performance was demonstrated.

  11. Characteristics and crosstalk of optical waveguides fabricated in polymethyl methacrylate polymer circuit board.

    PubMed

    Hamid, Hanan H; Rüter, Christian E; Thiel, David V; Fickenscher, Thomas

    2016-11-10

    Electro-optical circuit boards should provide simple and cost-effective coupling techniques and crosstalk levels of less than -30  dB. A dicing saw was used to create waveguide grooves with a surface roughness of less than 183 nm in a 1.6-mm-thick polymethyl methacrylate polymer (PMMA) substrate. The buried optical waveguides were made from SU-8 in a PMMA substrate covered with a 1-mm PMMA sheet. The propagation loss for a 500  μm×570  μm straight waveguide was 0.9 dB/cm at 1310 nm. The coupling between parallel waveguides was measured at separation distances from 45 to 595 μm. The crosstalk was less than -40  dB for 65-mm-long waveguides. This fabrication method shows potential for dense optical interconnects with very low crosstalk.

  12. Monitoring of acid-base status of workers at a methyl methacrylate and polymethyl methacrylate production plant in Bulgaria.

    PubMed

    Prakova, Gospodinka R

    2003-01-01

    This study was carried out on 104 workers at three work operations and a control (nonproduction) area, within a methyl methacrylate (MMA)/polymethyl methacrylate (PMMA) production facility in Bulgaria. Airborne monitoring was conducted over a 10-year period for MMA and the reactant chemicals methanol and acetone cyanhydrine at the MMA operation, and MMA was monitored at the PMMA operation. Acid-base status of the workers was evaluated using traditional criteria (pH, pCO(2), pO(2), and HCO(3) in plasma). Data from retrospective monitoring of air levels of the chemicals were compared with the acid-base status of workers at the plant. In some cases air concentrations exceeded the threshold limit value, with the highest percentage of overexposure occurring with airborne MMA in the PMMA production operation. Acid-base disruption indicated by reductions in plasma pH and HCO(3) was found for all groups except the control population. The highest percentage reduction was associated with PMMA production workers. Additionally, respiratory acidosis, indicated by increased pCO(2), was noted in the MMA production and maintenance groups, implying that the response to MMA exposure may involve both the metabolic and respiratory acidosis component. This study was unique in that the combined exposure to MMA and the precursor chemical (methanol) were shown to produce the same effects in workers. It is suggested that when combined exposure occurs, disruption of acid-base status may occur. Enforcement of PPM requirements for coveralls and gloves should prevent skin contamination. Additionally, improvement of equipment in MMA and PMMA production areas is recommended: (1) automation of some manual operations; (2) use of respiratory protection during equipment cleaning; and (3) installation of local ventilation when applicable.

  13. Formation of poly(methyl methacrylate) thin films onto wool fiber surfaces by vapor deposition polymerization.

    PubMed

    Hassan, M Mahbubul; McLaughlin, J Robert

    2013-03-13

    Chemical vapor deposition (CVD) polymerization is a useful technique because of the possibility of forming very thin film of pure polymers on substrates with any geometric shape. In this work, thin films of poly(methyl methacrylate) or PMMA were formed on the surfaces of wool fabrics by a CVD polymerization process. Various polymerization initiators including dicumyl peroxide, tert-butyl peroxide, and potassium peroxydisulfate have been investigated to polymerize methyl methacrylate onto the surfaces of wool by the CVD polymerization. The wool fabrics were impregnated with initiators and were then exposed to MMA monomer vapor under vacuum at the boiling temperature of the monomer. Wool fabrics with vapor-deposited PMMA surfaces were characterized by elemental analysis, TGA, FTIR, disperse dye absorption, contact angles measurement, AFM, and SEM. PMMA-coated wool fabrics showed higher contact angle and absorbed more dyes than that of the control wool. It was evident from the results obtained by various characterization techniques that MMA was successfully polymerized and formed thin films on the surfaces of wool fabrics by all initiators investigated but the best results were achieved with tert-butyl peroxide.

  14. High efficiency platinum acetylide nonlinear absorption chromophores covalently linked to poly(methyl methacrylate).

    PubMed

    Shelton, Abigail H; Price, Randi S; Brokmann, Luisa; Dettlaff, Barbara; Schanze, Kirk S

    2013-08-28

    We report three platinum acetylide acrylate monomers containing known two-photon absorption (TPA) chromophores and their covalent incorporation into polymers via free radical polymerization with methyl methacrylate. The photophysical properties of the platinum acetylide monomers and resulting poly(methyl methacrylate) (PMMA) copolymers were investigated to determine if the one- and two-photon photophysical properties of the chromophores were maintained in the copolymers. The photophysical properties of the series of copolymers were studied in solution and solid state with minimum shifts exhibited in the ground state absorption, photoluminescence, and triplet-triplet transient absorption spectra. The polymer films displayed markedly stronger phosphorescence and longer triplet excited state lifetimes than the polymers in solution or the monomers. The incorporation of the platinum acetylide chromophores into the PMMA copolymers allows the materials to be cast as thin films or into free-standing monoliths. Films with ~3.6 μm in thickness and monoliths with 1 mm path length were fabricated and examined. The nonlinear absorption responses of the polymers in solution were measured via the nanosecond z-scan method, and the solid state polymer monoliths were measured via nonlinear transmittance. Both measurements indicate that the polymers exhibited strong transmittance attenuation at input pulse energies exceeding 100 μJ.

  15. Inhalation study of polymethyl methacrylate following radiologist exposure during percutaneous vertebroplasty.

    PubMed

    Amoretti, Nicolas; Coco, Lucia; Nouri, Yasir; Marcy, Pierre-Yves; Ianessi, Antoine; Amoretti, Marie-Eve; Hauger, Olivier

    2013-02-01

    To assess the atmospheric concentrations of methyl methacrylate (MMA) vapors during percutaneous vertebroplasty for the interventional radiologist and the other operating room staff. During percutaneous vertebroplasty, a polymethyl methacrylate (PMMA) mixture (about 20 mL) was prepared with a mixing system in a normally ventilated room. Atmospheric concentrations of MMA vapors were measured by a gas absorbent badge for individual exposure (GABIE) passive sampler attached to the surgical gowns of the interventional radiologist and the other operating room staff over a period of 460 min. Active sampling was performed over 15 min with an individual pump placed near the breathing zone of the radiologist. MMA vapor concentrations were then measured using gas chromatography and activated charcoal tubes. Mean MMA vapor concentrations measured by the GABIEs over the period of 460 min were 0.51 parts per million (ppm) for the radiologist and 0.22 ppm for the other operating room staff. The emission peaks measured by using charcoal tubes over 15 min were 3.7 ppm. MMA vapor concentrations during percutaneous vertebroplasty were well below the recommended maximum exposure of 100 ppm over the course of an 8-h workday.

  16. Low-cost fabrication of poly(methyl methacrylate) microchips using disposable gelatin gel templates.

    PubMed

    Chen, Zhi; Yu, Zhengyin; Chen, Gang

    2010-06-15

    A simple method based on disposable gelatin gel templates has been developed for the low-cost fabrication of poly(methyl methacrylate) (PMMA) microfluidic chips. Gelatin was dissolved in glycerol aqueous solution under heat to prepare a thermally reversible impression material. The molten gel was then sandwiched between a glass plate and a SU-8 template bearing negative relief of microstructure. After cooling, the negative SU-8 template could be easily separated from the solidified gelatin gel and a layer of gelatin template bearing positive relief of the microstructure was left on the glass plate. Subsequently, prepolymerized methyl methacrylate molding solution containing a UV-initiator was sandwiched between the gel template and a PMMA plate and was allowed to polymerize under UV light to fabricate PMMA channel plate at room temperature. Complete microchips could be obtained by bonding the channel plates with covers using plasticizer-assisted thermal bonding at 90 degrees C. Gelatin gel template can be mass-produced and will find application in the mass production of PMMA microchips at low cost. The prepared microfluidic microchips have been successfully employed in the capillary electrophoresis analysis of several ions in connection with contactless conductivity detection.

  17. Poly(methyl methacrylate)-titania hybrid materials by sol-gel processing

    SciTech Connect

    Zhang, J.; Luo, S.; Gui, L.; Tang, Y.

    1996-12-31

    Sol-gel derived Poly(methyl methacrylate)-titania hybrid materials were synthesized by using acrylic acid or allyl acetylacetone (3-allyl-2,4-pentanedione) as coupling agents. Titanium butoxide modified with acrylic acid (or titanium isopropoxide modified with allyl acetylacetone) was hydrolyzed to produce a titania network, and then poly (methyl methacrylate) (PMMA) chains formed in situ through a radical polymerization were chemically bonded to the forming titania network to synthesize a hybrid material. Transparent hybrid materials with different contents of titania were achieved. With the increase of the titania content, the colors of the products changed form yellow to dark red. The synthesis process was investigated step by step by using FTIR spectroscopy, and the experimental results demonstrated that acrylate or acetylacetonato groups bound to titanium remain in the final hybrid materials. The thermal stability of the hybrid materials was considerably improved relative to pure PMMA. Field emission scanning electron microscopy (FE-SEM) analyses showed the hybrid materials are porous and pore diameters vary from 10nm to 100nm. The hybrid materials using allyl acetylacetone as the coupling agent exhibited thermochromic effects that both pure PMMA and titania do not have.

  18. Effect of Nanoclay on Thermal Conductivity and Flexural Strength of Polymethyl Methacrylate Acrylic Resin

    PubMed Central

    Ghaffari, Tahereh; Barzegar, Ali; Hamedi Rad, Fahimeh; Moslehifard, Elnaz

    2016-01-01

    Statement of the Problem The mechanical and thermal properties of polymethyl methacrylate (PMMA) acrylic resin should be improved to counterweigh its structural deficiencies. Purpose The aim of this study was to compare the flexural strength and thermal conductivity of conventional acrylic resin and acrylic resin loaded with nanoclay. Materials and Method The methacrylate monomer containing the 0.5, 1 and 2 wt% of nanoclay was placed in an ultrasonic probe and mixed with the PMMA powder. Scanning electron microscopy was used to verify homogeneous distribution of particles. Twenty-four 20×20×200-mm cubic samples were prepared for flexural strength test; 18 samples containing nanoclay and 6 samples for the control group. Another 24 cylindrical samples of 38×25 mm were prepared for thermal conductivity test. One-way ANOVA was used for statistical analysis, followed by multiple-comparison test (Scheffé’s test). Statistical significance was set at p< 0.05. Results Increasing the concentration of nanoclay incorporated into the acrylic resin samples increased thermal conductivity but decreased flexural strength (p< 0.05). Conclusion Based on the results of this study, adding nanoclay particles to PMMA improved its thermal conductivity, while it had a negative effect on the flexural strength. PMID:27284557

  19. Red-NIR luminescent hybrid poly(methyl methacrylate) containing covalently linked octahedral rhenium metallic clusters.

    PubMed

    Molard, Yann; Dorson, Frederick; Brylev, Konstantin A; Shestopalov, Michael A; Le Gal, Yann; Cordier, Stéphane; Mironov, Yuri V; Kitamura, Noboru; Perrin, Christiane

    2010-05-17

    The embedding of functional inorganic entities into polymer matrices has become an intense field of investigation in which the main challenges are to keep the added value of the inorganic entities while preventing their self-aggregation within the organic matrix. We present a simple way to obtain a homogeneous highly red-NIR luminescent hybrid copolymer that contains covalently bonded nanometric-sized {Re(6)} octahedral clusters. The [Re(6)Se(i)(8)(OH)(a)(6)](4-) cluster complexes are primarily functionalized in two steps with tert-butylpyridine (TBP) and methacrylic acid (MAC) to give neutral [Re(6)Se(8)(TBP)(4)(MAC)(2)] building blocks that are copolymerized with methyl methacrylate (MMA) either in solution or in bulk in the presence of azobisisobutyronitrile as an initiator. Several samples containing 0, 0.025, 0.05, and 0.1 wt % of functionalized {Re(6)} clusters were prepared. As the {Re(6)} cluster/MMA ratio is very low, the obtained copolymers keep the entire processability of pure poly(methyl methacrylate) (PMMA), as demonstrated by differential scanning calorimetry and thermogravimetric analysis. Voltammetric and luminescence studies also indicate that the intrinsic properties of the clusters are preserved within the polymer matrix. All the samples show a bright (emission quantum yield=0.07), broad, and structureless emission band, which extends from lambda=600 nm to more than lambda=950 nm, with the maximum wavelength centered around lambda(em)=710 nm either in solution or in the solid state. Moreover, the high stability of the incorporated inorganic phosphors prevents the material from photobleaching, and thus the luminescence properties are kept entirely even after nine months of ageing.

  20. Effect of additive particles on mechanical, thermal, and cell functioning properties of poly(methyl methacrylate) cement

    PubMed Central

    Khandaker, Morshed; Vaughan, Melville B; Morris, Tracy L; White, Jeremiah J; Meng, Zhaotong

    2014-01-01

    The most common bone cement material used clinically today for orthopedic surgery is poly(methyl methacrylate) (PMMA). Conventional PMMA bone cement has several mechanical, thermal, and biological disadvantages. To overcome these problems, researchers have investigated combinations of PMMA bone cement and several bioactive particles (micrometers to nanometers in size), such as magnesium oxide, hydroxyapatite, chitosan, barium sulfate, and silica. A study comparing the effect of these individual additives on the mechanical, thermal, and cell functional properties of PMMA would be important to enable selection of suitable additives and design improved PMMA cement for orthopedic applications. Therefore, the goal of this study was to determine the effect of inclusion of magnesium oxide, hydroxyapatite, chitosan, barium sulfate, and silica additives in PMMA on the mechanical, thermal, and cell functional performance of PMMA. American Society for Testing and Materials standard three-point bend flexural and fracture tests were conducted to determine the flexural strength, flexural modulus, and fracture toughness of the different PMMA samples. A custom-made temperature measurement system was used to determine maximum curing temperature and the time needed for each PMMA sample to reach its maximum curing temperature. Osteoblast adhesion and proliferation experiments were performed to determine cell viability using the different PMMA cements. We found that flexural strength and fracture toughness were significantly greater for PMMA specimens that incorporated silica than for the other specimens. All additives prolonged the time taken to reach maximum curing temperature and significantly improved cell adhesion of the PMMA samples. The results of this study could be useful for improving the union of implant-PMMA or bone-PMMA interfaces by incorporating nanoparticles into PMMA cement for orthopedic and orthodontic applications. PMID:24920906

  1. Dynamic mechanical thermal analysis of dental polymers. I. Heat-cured poly(methyl methacrylate)-based materials.

    PubMed

    Clarke, R L

    1989-09-01

    The visco-elastic characteristics of homogeneous, heterogeneous and fibre-reinforced poly(methyl methacrylate) for use as denture base resins were measured by a dynamic mechanical thermal analyser in the frequency range 0.033-90 Hz. Dynamic Young's modulus of both polyethylene woven yarn and the polyaramid plain fabric-reinforced acrylics showed considerable improvement over the conventional denture base, whereas the carbon fibre-reinforced acrylic produced results lower than expected. From the loss tangent curves of the homogeneous and heterogeneous methacrylates their transition temperatures were recorded and the reciprocals of both the alpha and beta absorption temperatures were plotted against frequency to obtain their respective activation energies.

  2. A simple sonochemical method for fabricating poly(methyl methacrylate)/stearic acid phase change energy storage nanocapsules.

    PubMed

    Wang, Guxia; Xu, Weibing; Hou, Qian; Guo, Shengwei

    2015-11-01

    In this study, stearic acid suitable for thermal energy storage applications was nanoencapsulated in a poly(methyl methacrylate) shell. The nanocapsules were prepared using a simple ultrasonically initiated in situ polymerization method. The morphology and particle size of the poly(methyl methacrylate)/stearic acid phase change energy storage nanocapsules (PMS-PCESNs) were analyzed using transmission electron microscopy, scanning electron microscopy, atomic force microscopy and dynamic light scattering. The latent heat storage capacities of stearic acid and the PMS-PCESNs were determined using differential scanning calorimetry. The chemical composition of the nanocapsules was characterized using Fourier transform infrared spectroscopy. All of the results show that the PMS-PCESNs were synthesized successfully and that the latent heat storage capacity and encapsulation efficiency were 155.6 J/g and 83.0%, respectively, and the diameter of each nanocapsule was 80-90 nm.

  3. Poly(methyl methacrylate) coating of soft magnetic amorphous and crystalline Fe,Co-B nanoparticles by chemical reduction.

    PubMed

    Fernández Barquín, L; Yedra Martínez, A; Rodríguez Fernández, L; Rojas, D P; Murphy, F J; Alba Venero, D; Ruiz González, L; González-Calbet, J; Fdez-Gubieda, M L; Pankhurst, Q A

    2012-03-01

    The structural and magnetic properties of a collection of nanoparticles coated by Poly(methyl methacrylate) through a wet chemical synthesis have been investigated. The particles display either an amorphous (M = Fe, Co) M-B arrangement or a mixed structure bcc-Fe and fcc-Co + amorphous M-B. Both show the presence of a metal oxi-hydroxide formed in aqueous reduction. The organic coating facilitates technological handling. The cost-effective synthesis involves a reduction in a Poly(methyl methacrylate) aqueous solution of iron(II) or cobalt(II) sulphates (< 0.5 M) by sodium borohydride (< 0.5 M). The particles present an oxidized component, as deduced from X-ray diffraction, Mössbauer and Fe- and Co K-edge X-ray absorption spectroscopy and electron microscopy. For the ferrous alloys, this Fe-oxide is alpha-goethite, favoured by the aqueous solution. The Poly(methyl methacrylate) coating is confirmed by Fourier transform infrared spectroscopy. In pure amorphous core alloys there is a drastic change of the coercivity from bulk to around 30 Oe in the nanoparticles. The mixed structured alloys also lie in the soft magnetic regime. Magnetisation values at room temperature range around 100 emu/g. The coercivity stems from multidomain particles and their agglomeration, triggering the dipolar interactions.

  4. Kinetics and mechanisms of flash pyrolysis of poly(methyl methacrylate) (PMMA)

    SciTech Connect

    Arisawa, H.; Brill, T.B.

    1997-05-01

    Flash pyrolysis (600--1,000 C/s) of a film of anionically polymerized poly(methyl methacrylate) (PMMA) was conducted at controlled temperatures in the 380--600 C range by T-jump/FTIR spectroscopy. In the endothermic decomposition process, the methyl methacrylate monomer (MMA {ge} 90%) and CO{sub 2} ({le} 10%) are the only pyrolysis products detected. Arrhenius parameters for evolution of MMA and CO{sub 2} were determined under a pressure of 2 and 11 atm Ar for PMMA with MW = 2,000 and 131,000. A zeroth-order rate model was used. A slope break occurs at 460--500 C in the Arrhenius plots. Below this range for MMA, E{sub a} = 43--66 kcal/mol and In(A/s) = 26--44, which are comparable to previous reports for random C-C scission kinetics. For CO{sub 2}, E{sub a} = 39--46 kcal/mol and In(A/s) = 23--27, which are comparable to the decarboxylation rates of other organic compounds. Above 460--500 C, increased control of the rates by desorption/diffusion of MMA and CO{sub 2} is suggested by the lower values of E{sub a} in the 12--30 kcal/mol range and In(A/s) in the 5.7--17 range. Thus, the limiting temperature of pyrolysis of PMMA is about 500 C before the deconsolidation rate of the pyrolysis products begins to take control from the bulk decomposition rate in determining the rate of product evolution.

  5. Characterization of highly oriented organoclay/ poly(methyl methacrylate) moulded nanocomposites.

    PubMed

    Realinho, V; Velasco, J I; Antunes, M; Sánchez-Soto, M S; Maspoch, M Ll

    2010-02-01

    In the present paper, the effects of nanoparticles' content and orientation were studied on the structure, phase morphology and thermo-mechanical properties of highly oriented montmorillonite/ poly(methyl methacrylate) moulded nanocomposites. The nanocomposites were compounded using a co-rotating high-shear twin-screw extruder. Square plates were prepared by a two-stage compression-moulding process from the previously extruded materials, with the test specimens being directly machined in both parallel and perpendicular directions with respect to the plate's surface. Wide-angle X-ray diffraction (WAXD) revealed a highly-ordered structure of silicate platelets parallel to the plate's surface. Observations by transmission electron microscopy (TEM) supported this analysis, demonstrating the high anisotropy degree of the nanocomposites. Dynamic mechanical thermal analysis (DMTA) showed that the perpendicular specimens were stiffer than the parallel ones, with the presence of the oriented nanoparticles decreasing PMMA's mobility during the glass transition, although no significant differences were registered in the T(g) temperatures with increasing the amount of clay content or with orientation. Remarkable improvements regarding the fracture energy were observed for the perpendicular specimens, with the 20 wt% oMMT nanocomposite showing a fracture energy almost 10 times that of pure PMMA.

  6. Polymethyl-methacrylate-sorbitol-based capsules as local drug delivery vehicles: a preliminary study.

    PubMed

    Frank, Dorottya; Cseh, Gellért; Nagy, Tamás; Pótó, László; Kocsis, Béla; Miseta, Attila

    2011-05-01

    Local delivery of antibiotics via PMMA (polymethyl-methacrylate) has been widely used in the treatment of chronic osteomyelitis for over 40 years. Unfortunately, PMMA is water insoluble, which seriously limits antibiotic delivery. In addition, the polymerization temperature of PMMA is high, and consequently, only heat-stable antibiotics can be used. Therefore our aim has been to develop an effective antibiotic delivery system, which can be loaded with a wide variety of drugs and deliver the molecules in a predictable manner. Capsules with wall thicknesses of 0.3-0.6 mm from PMMA mixtures containing 40-70 w/w% (weight percent) of sorbitol were prepared and their permeability tested with BPB (Bromophenol Blue). Sorbitol content and wall thickness correlated with the BPB release. SEM (scanning electron microscopy) showed that the canalization of capsules also was well correlated with both sorbitol content and wall thickness. The PMMA-sorbitol-based capsule can potentially be a versatile tool in assuring effective delivery of antibiotics and other substances.

  7. Reinforcement of poly(methyl methacrylate) denture base with glass flake.

    PubMed

    Franklin, Paul; Wood, David J; Bubb, Nigel L

    2005-04-01

    Since the introduction of poly(methyl methacrylate) as a denture base material, it has suffered from having relatively poor mechanical properties. Many methods of improving its strength and toughness have been investigated. Most of these have not been adopted due to: increased cost, the need for specialist processing equipment or increased laboratory time due to more complicated procedures. Glass flake has been used as a reinforcing agent in many industrial polymers, but is as yet untested with denture base acrylic materials. The aim of this study is to evaluate the effect of adding glass flake to denture base acrylic powder on the fracture toughness of the set material. Glass flake was added in 5, 10 or 20% w/w to Trevalon denture base powder. The material was mixed, flasked, packed and processed in a manner typical for a denture base material. Fracture toughness was determined using a double torsion test technique. The addition of glass flake gave up to a 69% increase in fracture toughness compared to plain Trevalon material. The addition of 5% glass flake lead to an improvement in fracture toughness that was statistically significant compared to both plain Trevalon and the 10 and 20% groups. The significant improvement in fracture toughness of a denture base acrylic material using glass flake is an extremely promising result. Other mechanical properties will require testing before glass flake can be recommended as a reinforcing agent for denture base acrylic materials.

  8. Bioactivity and architecture of Candida albicans biofilms developed on poly(methyl methacrylate) resin surface.

    PubMed

    da Silva, Wander José; Seneviratne, Jayampath; Samaranayake, Lakshman Perera; Del Bel Cury, Altair Antoninha

    2010-07-01

    The aim of this study was to evaluate the bioactivity and architecture of Candida albicans biofilms developed on the surface of poly(methyl methacrylate) (PMMA) resin. To do this, surface roughness (SR) and surface free energy of PMMA specimens were measured. Next, the biofilms of two different C. albicans strains (ATCC 90028 and SC5314) were allowed to develop on the PMMA surface and evaluated at 24, 48, and 72 h after adhesion. The bioactivity of the biofilms was measured by the XTT reduction assay. Biofilm topography was evaluated by scanning electron microscopy. Confocal microscopy was used to evaluate the architectural properties of bio-volume, average thickness, biofilm roughness, surface area/volume ratio and the proportion of live/dead cells in the different biofilm development stages. SR and SFE had no influence on biofilm development. Each strain exhibited a different biofilm activity (P < 0.001). Confocal images showed different architectures for the different biofilm development stages. We conclude that the main differences detected in biofilm bioactivity and architecture were related to the characteristics of each C. albicans strain and to biofilm development time.

  9. Absorption behavior of poly(methyl methacrylate)-multiwalled carbon nanotube composites: effects of UV irradiation.

    PubMed

    Hsu, Je-Chuan; Cao, Wenxin; Yang, Fuqian; Yang, Tsong-Jen; Lee, Sanboh

    2017-03-08

    Understanding the effects of carbon nanotubes (CNTs) and ultraviolet (UV) irradiation on solvent transport in polymers is of practical importance for the applications of polymer-CNT composites in electronics and photonics. The transport behavior of methanol in poly(methyl methacrylate)-multiwalled carbon nanotube (PMMA-MWCNT) composites with and without UV light irradiation has been studied. The anomalous transport has been investigated as a function of the weight percentage of MWCNTs and UV dose in the temperature range of 30-50 °C. The anomalous transport consists of Case I (controlled by concentration gradient) and Case II (controlled by stress relaxation) transport; both UV irradiation and the addition of MWCNTs in PMMA enhance the transport of methanol. The activation energies for Case I and Case II transport decrease with the increase of UV dose for the PMMA-MWCNT plates with the same weight percentage of MWCNTs. Without UV irradiation, the activation energy for Case I transport of methanol decreases with the increase of the weight percentage of MWCNTs, and the activation energy for Case II transport increases with the increase of the weight percentage of MWCNTs.

  10. Segmental and local dynamics of stacked thin films of poly(methyl methacrylate)

    NASA Astrophysics Data System (ADS)

    Hayashi, Tatsuhiko; Fukao, Koji

    2014-02-01

    The glass transition temperature and the dynamics of the α and β processes have been investigated using differential scanning calorimetry and dielectric relaxation spectroscopy during successive annealing processes above the glass transition temperature for stacked thin films of poly(methyl methacrylate) (PMMA) of various thicknesses. The glass transition temperature and the dynamics of the α process (segmental motion) of as-stacked PMMA thin films exhibit thin-film-like behavior, insofar as the glass transition temperature is depressed and the dynamics of the α process are faster than those of the bulk system. Annealing at high temperature causes the glass transition temperature to increase from the reduced value and causes the dynamics of the α process to become slower approaching those of the bulk. Contrary to the segmental motion, the relaxation time of the β process (local motion) of the stacked PMMA thin films is almost equal to that of the bulk PMMA and is unaffected by the annealing process. However, the relaxation strengths of both the α process and β process show a strong correlation between each other. The sum of the relaxation strengths remains almost unchanged, while the individual relaxation strengths change during the annealing process. The fragility index of the stacked PMMA thin films increases with annealing, which suggests that the glassy state of the stacked thin films changes from strong to fragile.

  11. Evaluation of polymethyl methacrylate resin mechanical properties with incorporated halloysite nanotubes

    PubMed Central

    2016-01-01

    PURPOSE This study inspects the effect of incorporating halloysite nanotubes (HNTs) into polymethyl methacrylate (PMMA) resin on its flexural strength, hardness, and Young's modulus. MATERIALS AND METHODS Four groups of acrylic resin powder were prepared. One group without HNTs was used as a control group and the other three groups contained 0.3, 0.6 and 0.9 wt% HNTs. For each one, flexural strength, Young's modulus and hardness values were measured. One-way ANOVA and Tukey's test were used for comparison (P<.05). RESULTS At lower concentration (0.3 wt%) of HNT, there was a significant increase of hardness values but no significant increase in both flexural strength and Young's modulus values of PMMA resin. In contrast, at higher concentration (0.6 and 0.9 wt%), there was a significant decrease in hardness values but no significant decrease in flexural strength and Young's modulus values compared to those of the control group. CONCLUSION Addition of lower concentration of halloysite nanotubes to denture base materials could improve some of their mechanical properties. Improving the mechanical properties of acrylic resin base material could increase the patient satisfaction. PMID:27350849

  12. Combination photo and electron beam lithography with polymethyl methacrylate (PMMA) resist.

    PubMed

    Carbaugh, Daniel J; Pandya, Sneha G; Wright, Jason T; Kaya, Savas; Rahman, Faiz

    2017-09-12

    We describe techniques for performing photolithography and electron beam lithography in succession on the same resist-covered substrate. Larger openings are defined in the resist film through photolithography whereas smaller openings are defined through conventional electron beam lithography. The two processes are carried out one after the other and without an intermediate wet development step. At the conclusion of the two exposures, the resist film is developed once to reveal both large and small openings. Interestingly, these techniques are applicable to both positive and negative tone lithographies with both optical and electron beam exposure. Polymethyl methacrylate (PMMA), by itself or mixed with a photocatalytic cross-linking agent, is used for this purpose. We demonstrate that such resists are sensitive to both ultraviolet (UV) and electron beam irradiation. All four possible combinations, consisting of optical and electron beam lithographies, carried out in positive and negative tone modes have been described. Demonstration grating structures have been shown and process conditions have been described for all four cases. © 2017 IOP Publishing Ltd.

  13. Fabrication of superhydrophilic and antireflective silica coatings on poly(methyl methacrylate) substrates

    SciTech Connect

    Geng, Zhi; He, Junhui; Xu, Ligang

    2012-06-15

    Graphical abstract: Self-cleaning and antireflection properties were successfully achieved by assembling (PDDA/S-20){sub n} coatings on PMMA substrates followed by oxygen plasma treatment. Highlights: ► Porous silica coatings were created by layer-by-layer assembly on PMMA substrates. ► Silica coatings were treated by oxygen plasma. ► Porous silica coatings were highly antireflective and superhydrophilic on PMMA substrates. -- Abstract: Silica nanoparticles of ca. 20 nm in size were synthesized, from which hierarchically porous silica coatings were fabricated on poly(methyl methacrylate) (PMMA) substrates via layer-by-layer (LbL) assembly followed by oxygen plasma treatment. These porous silica coatings were highly transparent and superhydrophilic. The maximum transmittance reached as high as 99%, whereas that of the PMMA substrate is only 92%. After oxygen plasma treatment, the time for a water droplet to spread to a contact angle of lower than 5° decreased to as short as 0.5 s. Scanning and transmission electron microscopy were used to observe the morphology and structure of nanoparticles and coating surfaces. Transmission and reflection spectra were recorded on UV–vis spectrophotometer. Surface wettability was studied by a contact angle/interface system. The influence of mesopores on the transmittance and wetting properties of coatings was discussed on the basis of experimental observations.

  14. Facile control of surface wettability in TiO2/poly(methyl methacrylate) composite films.

    PubMed

    Yang, Mengjin; Di, Zengfeng; Lee, Jung-Kun

    2012-02-15

    A facile method to produce very hydrophobic surface was developed simply using the mixture of TiO(2) nanoparticles and poly(methyl methacrylate) (PMMA). When the volume ratio of TiO(2) to PMMA is between 35 vol.% and 50 vol.%, the mixture of two hydrophilic materials became very hydrophobic. Analysis of the molecular structure by infrared spectroscopy shows that the preferential orientation and attachment of a carbonyl group of a polymer molecule to the surface of TiO(2) nanoparticles play a critical role in the appearance of the strong hydrophobicity. When this composite was exposed to UV light, PMMA on the surface of the mixture film was decomposed through a photocatalytic reaction and the very hydrophobic surface turned to the superhydrophilic one. The superhydrophilic property of UV-irradiated composite lasts as long as several months. This long lasting superhydrophilicity is ascribed to the porous structure, which provides high roughness and strong capillary interaction. Easy transition from strong hydrophobicity to superhydrophilicity in TiO(2)/PMMA composites could be applied to designing high contrast hydrophilic/hydrophobic patterns.

  15. Surface characterization of poly(methyl methacrylate) microgrooved for contact guidance of mammalian cells.

    PubMed

    Alaerts, J A; De Cupere, V M; Moser, S; Van den Bosh de Aguilar, P; Rouxhet, P G

    2001-06-01

    High-resolution patterns of grooves have been made in poly(methyl methacrylate) films, PMMA, by an electron-beam microlithographic process. The surface of films processed over a large width was characterized in terms of chemical composition (X-ray photoelectron spectroscopy (XPS). time of flight secondary ion mass spectroscopy), wettability (sessile drop) and topography (atomic force microscopy). Collagen adsorption was also studied (radiocounting, XPS) as such or in competition with Pluronic F68. The chemical alteration of the surface induced by the electron-beam irradiation disappeared after the dissolution involved in the development process. W138 human fibroblasts cultivated on microgrooved substrata (grooves 1 microm deep and 0.5-10 microm wide) showed a strong orientation parallel to the grooves. The contact guidance is induced by the topography of the surface and not by the alternation of zones with different physico-chemical properties. It may be explained in terms of probability of successful substratum contact by cell protrusions.

  16. Photochemically patterned poly(methyl methacrylate) surfaces used in the fabrication of microanalytical devices.

    PubMed

    Wei, Suying; Vaidya, Bikas; Patel, Ami B; Soper, Steven A; McCarley, Robin L

    2005-09-08

    We report here the photochemical surface modification of poly(methyl methacrylate), PMMA, microfluidic devices by UV light to yield pendant carboxylic acid surface moieties. Patterns of carboxylic acid sites can be formed from the micrometer to millimeter scale by exposure of PMMA through a contact mask, and the chemical patterns allow for further functionalization of PMMA microdevice surfaces to yield arrays or other structured architectures. Demonstrated here is the relationship between UV exposure time and PMMA surface wettability, topography, surface functional group density, and electroosmotic flow (EOF) of aqueous buffer solutions in microchannels made of PMMA. It is found that the water contact angle on PMMA surfaces decreases from 70 degrees to 24 degrees after exposure to UV light as the result of the formation of carboxylic acid sites. However, upon rinsing with 2-propanol, the water contact angle increases to approximately 80 degrees , and this increase is attributed to changes in surface roughness resulting from removal of low molecular weight PMMA formed from scission events. In addition, the surface roughness and surface coverage of carboxylic acid groups exhibit a characteristic trend with UV exposure time. Electroosmotic flow (EOF) in PMMA microchannels increases upon UV modification and is pH dependent. The possible photolysis mechanism for formation of carboxylic acid groups on PMMA surfaces under the conditions outlined in this work is discussed.

  17. Dimensional accuracy and stability of polymethyl methacrylate reinforced with metal wire or with continuous glass fiber.

    PubMed

    Vallittu, P K

    1996-06-01

    The aim of this study was to determine the dimensional accuracy and stability of denture base polymethyl methacrylate (PMMA), which was reinforced in various ways. Autopolymerizing PMMA and heat-cured PMMA were reinforced either with semicircular steel wire or with a prefabricated experimental reinforcement made of continuous E-glass fiber. Control specimens had no reinforcement. The width of each U-shaped test specimen was measured with a digital micrometer under a light microscope immediately after the test specimen was cured and when stored in water for 1, 2, 7, and 14 days. The results revealed that both the type of PMMA and the type of reinforcement affected the dimensional accuracy of the test specimens, especially after 7 and 14 days in water storage (p < 0.001). The greatest dimensional accuracy was found with the unreinforced test specimen made from autopolymerizing PMMA and with test specimens reinforced with the metal wire made from heat-cured PMMA. In terms of the width of the test specimens, the lowest dimensional accuracy was found in unreinforced and glass fiber reinforced specimens made from heat-cured PMMA. Storage in water did not affect the stability of the width (p > 0.1). The results suggest that the polymerization shrinkage of PMMA causes lower dimensional accuracy of the test specimens reinforced with glass fiber. This should be considered when glass-fiber reinforcement is used clinically.

  18. Homogeneously aligned liquid crystal molecules on reformed poly(methyl methacrylate) via ion-beam irradiation

    NASA Astrophysics Data System (ADS)

    Jeong, Hae-Chang; Park, Hong-Gyu; Lee, Ju Hwan; Jang, Sang Bok; Oh, Byeong-Yun; Han, Jeong-Min; Seo, Dae-Shik

    2016-04-01

    We demonstrated uniform LC alignment using IB-irradiated poly(methyl methacrylate) (PMMA) as an alignment layer. We confirmed the topographical changes on PMMA caused by IB irradiation. Moreover, the wettability and chemical modification of the PMMA surface were investigated as functions of incidence angle. The results show that PMMA irradiated with IB at an incidence angle of 30° had a higher molecular polarity than PMMA irradiated with IB at other incidence angles, resulting in strong van der Waals interactions between the surface and LC molecules. The LC cells containing PMMA irradiated with IB at an incidence angle of 30° exhibited good thermal stability (180°) compared with LC cells containing conventional rubbing PI (150°). In addition, LC molecules on PMMA irradiated with IB at an incidence angle of 30° were observed to switch faster than those on conventional rubbing PI. Therefore, PMMA irradiated with IB under the optimal conditions may allow for PMMA to be applied in advanced LC devices as an alternative alignment layer.

  19. Nanopillar formation from two-shot femtosecond laser ablation of poly-methyl methacrylate

    NASA Astrophysics Data System (ADS)

    Baset, F.; Popov, K.; Villafranca, A.; Alshehri, A. M.; Guay, J.-M.; Ramunno, L.; Bhardwaj, V. R.

    2015-12-01

    We present experimental and numerical studies on the morphological evolution and dynamics of femtosecond laser ablation of bulk poly-methyl methacrylate (PMMA) irradiated with a pair of pulses. We show that a nanopillar-like structure is formed in the middle of the ablation crater for pulse energies below single-shot ablation threshold. The nanopillar is ∼400 nm long, lies adjacent to a nanopore, and protrudes ∼150 nm above the sample surface. As the pulse energy is increased gradually, the nanopillar disappears and the nanopore inside the ablation crater becomes larger. At higher pulse energies, a volcanic eruption like structure appears in the middle of the crater whose size and height increases with energy. 2D molecular dynamics simulations reveal that a nanojet and other features observed at higher pulse energies can be formed when the reflection of a shockwave, induced by the second laser pulse, causes density pinching in the middle of the interaction region that rapidly pushes out molten material towards the surface. The shockwave is reflected from the cold boundaries of a modified region created by the first laser pulse.

  20. Adsorption of doxorubicin on poly(methyl methacrylate)-chitosan-heparin-coated activated carbon beads.

    PubMed

    Miao, Jianjun; Zhang, Fuming; Takieddin, Majde; Mousa, Shaker; Linhardt, Robert J

    2012-03-06

    Extracorporeal filter cartridges, filled with an activated carbon bead (ACB) adsorbent, have been used for removal of overdosed cancer drugs from the blood. Coatings on adsorbent matrices, poly(methyl methacrylate) (PMMA)/activated carbon bead and PMMA/chitosan/heparin/ACB composites, were tested to improve their biocompatibility and blood compatibility. PMMA coating on ACBs was accomplished in a straightforward manner using a PMMA solution in ethyl acetate. A one-step hybrid coating of ACBs with PMMA-anticoagulant heparin required the use of acetone and water co-solvents. Multilayer coatings with three components, PMMA, chitosan, and heparin, involved three steps: PMMA was first coated on ACBs; chitosan was then coated on the PMMA-coated surface; and finally, heparin was covalently attached to the chitosan coating. Surface morphologies were studied by scanning electron microscopy. X-ray photoelectron spectroscopy confirmed the -SO(3)(-) group. Adsorption, of a chemotherapy drug (doxorubicin) from both water and phosphate-buffered saline, by the coated ACBs was examined. The adsorption isotherm curves were fitted using the Freundlich model. The current adsorption system might find potential applications in the removal of high-dose regional chemotherapy drugs while maintaining high efficiency, biocompatibility, and blood compatibility.

  1. Water absorption of poly(methyl methacrylate) containing 4-methacryloxyethyl trimellitic anhydride.

    PubMed

    Unemori, Masako; Matsuya, Yoko; Matsuya, Shigeki; Akashi, Akane; Akamine, Akifumi

    2003-04-01

    The amount of water absorption of poly(methyl methacrylate) (PMMA) containing 0, 1, 3 and 5 wt% of an adhesive monomer, 4-methacryloxyethyl trimellitic anhydride (4-META), was measured at 7 degrees C, 37 degrees C and 60 degrees C. After the water uptake reached equilibrium in specimens, they were desorbed to obtain a constant value and the absorption process was repeated. Mass changes in the second desorption were recorded for the storage temperatures of 37 degrees C and 60 degrees C. Multiple regression analyses were conducted on three independent variables, 4-META concentration, storage temperature and absorption-desorption cycle. A statistically significant relationship was found between the maximum water uptake and 4-META concentration, while there was no relationship between the maximum water uptake and diffusion coefficient obtained using the Fick's law. The negative relationship in the latter did not support the free space theory. The significant and positive relationship between the maximum water uptake and 4-META concentration demonstrates that water molecules diffuse through the formation of a hydrogen bond at polar sites. The maximum water uptake was not influenced by temperature, while the diffusion coefficient increased with the rise in temperature. The activation energy was 41-47 and 50-53 kJ/mol in the first and second absorption tests, respectively.

  2. Evaluation of polymethyl methacrylate resin mechanical properties with incorporated halloysite nanotubes.

    PubMed

    Abdallah, Reham M

    2016-06-01

    This study inspects the effect of incorporating halloysite nanotubes (HNTs) into polymethyl methacrylate (PMMA) resin on its flexural strength, hardness, and Young's modulus. Four groups of acrylic resin powder were prepared. One group without HNTs was used as a control group and the other three groups contained 0.3, 0.6 and 0.9 wt% HNTs. For each one, flexural strength, Young's modulus and hardness values were measured. One-way ANOVA and Tukey's test were used for comparison (P<.05). At lower concentration (0.3 wt%) of HNT, there was a significant increase of hardness values but no significant increase in both flexural strength and Young's modulus values of PMMA resin. In contrast, at higher concentration (0.6 and 0.9 wt%), there was a significant decrease in hardness values but no significant decrease in flexural strength and Young's modulus values compared to those of the control group. Addition of lower concentration of halloysite nanotubes to denture base materials could improve some of their mechanical properties. Improving the mechanical properties of acrylic resin base material could increase the patient satisfaction.

  3. Morphological study of polymethyl methacrylate microcapsules filled with self-healing agents

    NASA Astrophysics Data System (ADS)

    Ahangaran, Fatemeh; Hayaty, Mehran; Navarchian, Amir H.

    2017-03-01

    Polymethyl methacrylate (PMMA) microcapsules filled with epoxy prepolymer, 3-aminomethyl-3,5,5-trimethylcyclohexylamine, and pentaerythritol tetrakis (3-mercaptopropionate) as healing agents have been prepared separately through internal phase separation method for self-healing purposes. PMMA with two different molecular weights (M bar1 = 36,000 g/mol and M bar2 = 550,000 g/mol) were used with two types of different emulsifiers (ionic and polymeric) to prepare microcapsules. The morphology of healing agent microcapsules was investigated using field emission scanning electron microscopy (FESEM). It was found that PMMA microcapsules separately filled with epoxy and amine had core-shell morphologies with smooth surfaces. The mercaptan/PMMA particles exhibited core-shell and acorn-shape morphologies. The surface morphology of mercaptan microcapsules changed from holed to plain in different emulsion systems. The spreading coefficient (S) of phases in the prepared emulsion systems were calculated from interfacial tension (σ) and contact angle (θ) measurements. The theoretical equilibrium morphology of PMMA microcapsules was predicted according to spreading coefficient values of phases in emulsion systems. It was also found that the surface morphology of PMMA microcapsules depended strongly on the nature of the core, molecular weight of PMMA, type and concentration of emulsifier.

  4. Pulse laser-induced particle separation from polymethyl methacrylate: a mechanistic study

    NASA Astrophysics Data System (ADS)

    Arif, S.; Armbruster, O.; Kautek, W.

    2013-04-01

    The separation mechanism of opaque and transparent model micro-particles, graphite and polystyrene copolymer spheres, respectively, from polymethyl methacrylate (PMMA) substrates were investigated employing a ns-pulse laser radiating at 532 nm. The particles transparent in the visible wavelength range could be removed from PMMA efficiently in a very narrow fluence range between 1 and 2 J/cm2 according to a simple 1D thermal expansion model. Above this fluence region, with single pulses, the transparent microspheres caused local ablation of the PMMA substrate in the optical microlens nearfield. This process led to removal of the particles themselves due to the expansion of the ablation plasma. The irregularly shaped graphite particles shaded the underlying substrate from the incoming radiation so that no optical nearfield damage mechanism could be observed. Therefore, a substantial cleaning window between 0.5 and more than 16 J/cm2 was provided. The graphite data suggest an ablation mechanism of the particulates themselves due to a high optical absorption coefficient.

  5. Molecular dynamics of poly(methyl methacrylate) determined by dielectric relaxation spectroscopy

    NASA Astrophysics Data System (ADS)

    Seki, Yuki; Kita, Rio; Shinyashiki, Naoki; Yagihara, Shin; Yoneyama, Masaru

    2013-02-01

    We performed broadband dielectric measurements for poly(methyl methacrylate) [PMMA], poly(vinyl alcohol) [PVA], and PVA-fibroin blend films in the temperature range of -50 °C to 200 °C, -120 °C to 200 °C, and -120 °C to 25 °C, respectively, in the frequency range of 10 mHz to 10 MHz. For PMMA, three relaxation processes were observed: process α at low frequency, the secondary process β at intermediate frequency, and the last process γ at high frequency. The symmetrically shaped three relaxation processes (α, β, γ) are described by the Cole-Cole equation. Near room temperature, process γ merges with process β. Similarly, at higher temperatures which close to Tg (103 °C for PMMA), process α merges with processes β and γ. For PVA-fibroin blend film, we observe the three relaxation processes (β, γ, δ), and the contribution of dc conductivity is larger than that of PMMA and PVA films.

  6. On the role of chemical reactions in initiating ultraviolet laser ablation in poly(methyl methacrylate)

    SciTech Connect

    Prasad, Manish; Conforti, Patrick F.; Garrison, Barbara J.

    2007-05-15

    The role of chemical reactions is investigated versus the thermal and mechanical processes occurring in a polymer substrate during irradiation by a laser pulse and subsequent ablation. Molecular dynamics simulations with an embedded Monte Carlo based reaction scheme were used to study ultraviolet ablation of poly(methyl methacrylate) at 157 nm. We discuss the onset of ablation, the mechanisms leading to ablation, and the role of stress relaxation of the polymer matrix during ablation. Laser induced heating and chemical decomposition of the polymer substrate are considered as ablation pathways. It is shown that heating the substrate can set off ablation via mechanical failure of the material only for very short laser pulses. For longer pulses, the mechanism of ejection is thermally driven limited by the critical number of bonds broken in the substrate. Alternatively, if the photon energy goes towards direct bond breaking, it initiates chemical reactions, polymer unzipping, and formation of gaseous products, leading to a nearly complete decomposition of the top layers of substrates. The ejection of small molecules has a hollowing out effect on the weakly connected substrates which can lead to lift-off of larger chunks. Excessive pressure buildup upon the creation of gaseous molecules does not lead to enhanced yield. The larger clusters are thermally ejected, and an entrainment of larger polymer fragments in gaseous molecules is not observed.

  7. Effect of physical aging on stress relaxation of poly/methyl methacrylate/

    NASA Technical Reports Server (NTRS)

    Cizmecioglu, M.; Fedors, R. F.; Hong, S. D.; Moacanin, J.

    1981-01-01

    A study was made on the stress relaxation behavior at 25 C of poly(methyl methacrylate) in uniaxial tension as a function of physical aging at both room temperature and 60 C. Test specimens were compression molded at 165 C, then quenched to room temperature and allowed to age for up to 30 days prior to testing. Stress relaxation curves measured after different aging times could be superposed to a single master curve for each aging temperature. Superposition was achieved by applying vertical and horizontal shifts. Hence, the shape of the response curves was not changed by aging. This is in accordance with observations made by Struik for tensile creep curves. Volume changes as a function of physical aging were also determined. Simple exponential relationships were observed between volume and both horizontal and vertical shifts. The horizontal shift implies a shift in the effective time scale caused by a change in free volume. The vertical shifts could be correlated with changes in Young's modulus caused by a change in density. For the range of aging studied, the response time scale varied over nearly two decades of log-time. For the same conditions modulus varied by 30 percent.

  8. Crystallization behavior of single isotactic poly(methyl methacrylate) chains visualized by atomic force microscopy.

    PubMed

    Anzai, Takahiro; Kawauchi, Mariko; Kawauchi, Takehiro; Kumaki, Jiro

    2015-01-08

    We have, for the first time, successfully visualized the crystallization behavior of a single isolated polymer chain at the molecular level by atomic force microscopy (AFM). Previously, we found that isotactic poly(methyl methacrylate) (it-PMMA) formed two-dimensional folded chain crystals composed of double-stranded helices upon compression of its Langmuir monolayer on a water surface, and the molecular images of the crystals deposited on mica were clearly visualized by AFM (Kumaki, J.; et al. J. Am. Chem. Soc. 2005, 127, 5788). In the present study, a high-molecular-weight it-PMMA was diluted in a monolayer of an it-PMMA oligomer which cannot crystallize at the experimental temperature due to its low molecular weight. At a low surface pressure, isolated amorphous chains of the high-molecular-weight it-PMMA solubilized in the oligomer monolayer were observed. On compression, the isolated chains converted to crystals composed of a single chain, typically some small crystallites linked by an amorphous chain like a necklace. Detailed AFM observations of the crystals indicated that the crystalline nuclei preferentially formed at the ends of the chains, and the size of the nuclei was almost independent of the molecular weight of it-PMMA over a wide range. At an extremely slow compression, crystallization was promoted, resulting in crystallization of the whole chain. The crystallization behavior of a single isolated chain provides new insights in understanding the polymer crystallization process.

  9. Comparison of computed tomography dose index in polymethyl methacrylate and nylon dosimetry phantoms

    PubMed Central

    Sookpeng, Supawitoo; Cheebsumon, Patsuree; Pengpan, Thanyawee; Martin, Colin

    2016-01-01

    The use of computed tomography (CT) scanning has been growing steadily. Therefore, CT dose measurement is becoming increasingly important for patient protection and optimization. A phantom is an important tool for dose measurement. This paper focuses on the evaluation of a CT dosimetry phantom made from nylon, instead of the standard polymethyl methacrylate (PMMA), which is not readily available or is too expensive in some countries. Comparison between phantoms made from the two materials is made in terms of measurements of the CT dose indices (CTDI). These were measured for four different beam widths and kVp settings at the center and periphery in head and body phantoms made from both materials and weighted CTDIs (CTDIw) were calculated. CT numbers along the z-axis of the phantom were also measured at the center and four peripheral positions of each scanned slice to check phantom homogeneity. Results showed that values for the CTDIw measured in the nylon phantoms were slightly higher than those from the PMMA while CT numbers for nylon were lower than those of PMMA. This is because the mass attenuation coefficient of the nylon is higher. Nylon could be used as a substitute material for CT dosimetry phantom to enable measurements and adjustment factors are given which could be used to estimate PMMA values for making comparisons with displayed values. PMID:27051170

  10. Enhanced room temperature excitonic luminescence in ZnO/polymethyl methacrylate nanocomposites prepared by bulk polymerization

    NASA Astrophysics Data System (ADS)

    Paramo, J. Antonio; Strzhemechny, Yuri M.; Anžlovar, Alojz; Žigon, Majda; Orel, Zorica Crnjak

    2010-07-01

    Homogeneous ZnO/polymethyl methacrylate (PMMA) nanocomposites were prepared by incorporating ZnO nanoparticles synthesized in various diols into a PMMA matrix by the free-radical bulk polymerization. Room temperature photoluminescence spectra of the as-grown and PMMA-embedded ZnO nanoparticles exhibit an excitonic band-gap emission at 3.3 eV, a near band-gap emission at ˜3.1 eV and a broad defect band centered at ˜2.4 eV. Relative intensity of the defect versus band-gap luminescence depends on the parameters of ZnO preparation as well as the average particle size. However, PMMA-embedded particles produce a much stronger excitonic luminescence, whereas the ratio of the 3.1 to 2.4 eV remains approximately constant. There is no indication of random lasing threshold pointing to the ZnO/PMMA interfacial origin of the enhanced band-gap emission.

  11. Dielectric properties and fluctuating relaxation processes of poly(methyl methacrylate) based polymeric nanocomposite electrolytes

    NASA Astrophysics Data System (ADS)

    Sengwa, R. J.; Choudhary, Shobhna

    2014-06-01

    Solid polymer nanocomposite electrolytes (SPNEs) consisted of poly(methyl methacrylate) (PMMA) and lithium perchlorate (LiClO4) of molar ratio C=O:Li+=4:1 with varying concentration of montmorillonite (MMT) clay as nanofiller have been prepared by classical solution casting and high intensity ultrasonic assisted solution casting methods. The dielectric/electrical dispersion behaviour of these electrolytes was studied by dielectric relaxation spectroscopy at ambient temperature. The dielectric loss tangent and electric modulus spectra have been analyzed for relaxation processes corresponding to the side groups rotation and the segmental motion of PMMA chain, which confirm their fluctuating behaviour with the sample preparation methods and also with change of MMT concentration. The feasibility of these relaxation fluctuations has been explained using a transient complex structural model based on Lewis acid-base interactions. The low permittivity and moderate dc ionic conductivity at ambient temperature suggest the suitability of these electrolytes in fabrication of ion conducting electrochromic devices and lithium ion batteries. The amorphous behaviour and the exfoliated/intercalated MMT structures of these nanocomposite electrolytes were confirmed by X-ray diffraction measurements.

  12. Oriented growth of rat Schwann cells on aligned electrospun poly(methyl methacrylate) nanofibers.

    PubMed

    Xia, Haijian; Sun, Xiaochuan; Liu, Dan; Zhou, Yudong; Zhong, Dong

    2016-10-15

    Transplanted Schwann cells have the potential to serve as a support for regenerating neurites after spinal cord injury. However, implanted Schwann cells die off rapidly once transplanted partly owing to the absence of a proper matrix support, with a glia scar and a cavity being present instead at the injury site. For this report, we evaluated aligned electrospun poly(methyl methacrylate) nanofibers as a Schwann cell-loading scaffold in vitro. By monitoring the fluorescence of green fluorescence protein-containing Schwann cells cultured on nanofibers, we found that aligned nanofibers provided better support for the cells than did non-aligned nanofibers. The cells elongated along the long axes of the aligned nanofibers and formed longer cell processes than when the substrate was non-aligned nanofibers. By coculturing Schwann cells with dorsal root ganglion neurons, it was also found that Schwann cells and neurites of dorsal root ganglion neurons could share and both elongate along the orientation of aligned nanofibers and thus they had a higher chance of colocalization than cocultured on film and non-aligned fibers, which might be beneficial to the ensuring process of myelination. The results of the study indicate that aligned electrospun nanofibers may serve as a Schwann cell-loading scaffold for future implantation research. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. A Classification System for the Spread of Polymethyl Methacrylate in Vertebral Bodies Treated with Vertebral Augmentation

    PubMed Central

    Frankl, Joseph; Sakata, Michael P.; Choudhary, Gagandeep; Hur, Seung; Peterson, Andrew; Hennemeyer, Charles T.

    2016-01-01

    In this study, we develop a classification system for describing polymethyl methacrylate (PMMA) spread in vertebral bodies after kyphoplasty or vertebroplasty for vertebral compression fractures (VCFs) and for assessing whether PMMA spread varies between operators, VCF etiology, or vertebral level. Intraoperative fluoroscopic images of 198 vertebral levels were reviewed in 137 patients (women, 84; men, 53; mean age, 75.8 ± 12.5; and those with a diagnosis of osteoporosis, 63%) treated with kyphoplasty between January 01, 2015 and May 31, 2015 at a single center to create a 5-class descriptive system. PMMA spread patterns in the same images were then classified by 2 board-certified radiologists, and a third board-certified radiologist resolved conflicts. A total of 2 primary PMMA spread patterns were identified, namely, acinar and globular, with subtypes of localized acinar, diffuse globular, and mixed, to describe an equal combination of patterns. Interrater reliability using the system was moderate (κ = 0.47). After resolving conflicts, the most common spread class was globular (n = 63), followed by mixed (n = 58), diffuse globular (n = 30), acinar (n = 27), and localized acinar (n = 20). The spread class after treatment by the 2 most frequent operators differed significantly (n1 = 63, n2 = 70; P < .0001). There was no difference in the spread class between VCF etiologies or vertebral levels. PMMA spread may, therefore, be a modifiable parameter that affects kyphoplasty and vertebroplasty efficacy and adverse events. PMID:27795998

  14. Durability of Poly(Methyl Methacrylate) Lenses Used in Concentrating Photovoltaic Modules: Preprint

    SciTech Connect

    Miller, D. C.; Gedvilas, L. M.; To, B.; Kennedy, C. E.; Kurtz, S. R.

    2010-08-01

    Concentrating photovoltaic (CPV) technology has recently gained interest based on their expected low levelized cost of electricity, high efficiency, and scalability. Many CPV systems use Fresnel lenses made of poly(methyl methacrylate)(PMMA) to obtain a high optical flux density. The optical and mechanical durability of such components, however, are not well established relative to the desired service life of 30 years. Specific reliability issues may include: reduced optical transmittance, discoloration, hazing, surface erosion, embrittlement, crack growth, physical aging, shape setting (warpage), and soiling. The initial results for contemporary lens- and material-specimens aged cumulatively to 6 months are presented. The study here uses an environmental chamber equipped with a xenon-arc lamp to age specimens at least 8x the nominal field rate. A broad range in the affected characteristics (including optical transmittance, yellowness index, mass loss, and contact angle) has been observed to date, depending on the formulation of PMMA used. The most affected specimens are further examined in terms of their visual appearance, surface roughness (examined via atomic force microscopy), and molecular structure (via Fourier transform infrared spectroscopy).

  15. Transient gratings in thin films and bulk azo-dye-containing poly(methyl methacrylate) matrix

    NASA Astrophysics Data System (ADS)

    Luo, Duanbin; Lu, Wei; Wu, Shuizhu

    2005-02-01

    Using holographic recording technology, two kinds of transient diffraction gratings were demonstrated in azo-dye doped Poly(methyl methacrylate) (PMMA) films and bulk matrices respectively. In PMMA films containing azo-dye Disperse Red 13 (DR13), the refractive index gratings came from the reorientation of azo-dye molecules in different areas with different polarization distribution of recording beams. The characteristics of the transient gratings in films samples which were recorded by two mutually parallel polarization beams (PP and SS) as well as orthogonal linear polarization beams (PS and +/-45°) from an Ar ion laser (514nm) were investigated by monitoring the first order diffraction intensity of the readout He-Ne laser beam (632.8nm). With the interaction of bi-photonic lights at 514nm and 632.8nm, the transient gratings in azo-dye DR13 doped PMMA bulk matrices was a kind of population gratings of Trans and Cis isomers, which was attributed to the weak absorption of Cis isomers at 632.8nm and the positive dichroism of Trans isomers at 514nm. Furthermore, the all-optical switching behavior of the two kinds of transient holographic gratings were observed repeatedly by turning on and off the writing beams, and a response time at the magnitude of ten milliseconds order could be obtained.

  16. Responses of Vascular Endothelial Cells to Photoembossed Topographies on Poly(Methyl Methacrylate) Films

    PubMed Central

    Qiu, Lin; Hughes-Brittain, Nanayaa F.; Bastiaansen, Cees W. M.; Peijs, Ton; Wang, Wen

    2016-01-01

    Failures of vascular grafts are normally caused by the lack of a durable and adherent endothelium covering the graft which leads to thrombus and neointima formation. A promising approach to overcome these issues is to create a functional, quiescent monolayer of endothelial cells on the surface of implants. The present study reports for the first time on the use of photoembossing as a technique to create polymer films with different topographical features for improved cell interaction in biomedical applications. For this, a photopolymer is created by mixing poly(methyl methacrylate) (PMMA) and trimethylolpropane ethoxylate triacrylate (TPETA) at a 1:1 ratio. This photopolymer demonstrated an improvement in biocompatibility over PMMA which is already known to be biocompatible and has been extensively used in the biomedical field. Additionally, photoembossed films showed significantly improved cell attachment and proliferation compared to their non-embossed counterparts. Surface texturing consisted of grooves of different pitches (6, 10, and 20 µm) and heights (1 µm and 2.5 µm). The 20 µm pitch photoembossed films significantly accelerated cell migration in a wound-healing assay, while films with a 6 µm pitch inhibited cells from detaching. Additionally, the relief structure obtained by photoembossing also changed the surface wettability of the substrates. Photoembossed PMMA-TPETA systems benefited from this change as it improved their water contact angle to around 70°, making it well suited for cell adhesion. PMID:27941669

  17. Durability of poly(methyl methacrylate) lenses used in concentrating photovoltaic modules

    NASA Astrophysics Data System (ADS)

    Miller, David C.; Gedvilas, Lynn M.; To, Bobby; Kennedy, Cheryl E.; Kurtz, Sarah R.

    2010-08-01

    Concentrating photovoltaic (CPV) technology has recently gained interest based on their expected low levelized cost of electricity, high efficiency, and scalability. Many CPV systems use Fresnel lenses made of poly(methyl methacrylate) (PMMA) to obtain a high optical flux density. The optical and mechanical durability of such components, however, are not well established relative to the desired service life of 30 years. Specific reliability issues may include: reduced optical transmittance, discoloration, hazing, surface erosion, embrittlement, crack growth, physical aging, shape setting (warpage), and soiling. The initial results for contemporary lens- and material-specimens aged cumulatively to 6 months are presented. The study here uses an environmental chamber equipped with a xenon-arc lamp to age specimens at least 8x the nominal field rate. A broad range in the affected characteristics (including optical transmittance, yellowness index, mass loss, and contact angle) has been observed to date, depending on the formulation of PMMA used. The most affected specimens are further examined in terms of their visual appearance, surface roughness (examined via atomic force microscopy), and molecular structure (via Fourier transform infrared spectroscopy).

  18. Poly(methyl methacrylate)-graft-oligoamines as low cytotoxic and efficient nonviral gene vectors.

    PubMed

    Wang, Yong-Qiang; Sun, Yun-Xia; Hong, Xin-Lin; Zhang, Xian-Zheng; Zhang, Gao-Yong

    2010-01-01

    A series of poly(methyl methacrylate)-graft-oligoamines (PMMA-g-oligoamines), including PMMA-g-DETA, PMMA-g-TETA and PMMA-g-TEPA, were synthesized through aminolysis of the PMMA with diethylenetriamine, triethylenetetramine and tetraethylenepentamine. Agarose gel retardation assay indicated that PMMA-g-oligoamines had good binding capability with plasmid DNA, and the binding capability increased with increasing length of oligoamines and content of nitrogen (N%). The results of particle size, zeta potential and morphology observation further showed that the PMMA-g-oligoamines could condense DNA efficiently and the PMMA-g-oligoamine/DNA complexes were uniform nanospheres. The in vitro cell viability indicated that PMMA-g-oligoamines were less toxic than 25 kDa PEI, though the cytotoxicity of PMMA-g-oligoamines increased slightly with increasing length of oligoamines as well as the N% of PMMA-g-oligoamines. The transfection efficiency of PMMA-g-oligoamines/DNA complexes in 293 T and HeLa cells demonstrated that PMMA-g-oligoamines could transfect cells efficiently with increasing the length of oligoamines, especially PMMA-g-TEPA with highest N%, and showed similar transfection capability as 25 kDa PEI. The cellular uptake study showed that the distribution of YOYO-1 labeled DNA in the cytoplasm and nuclei increased gradually with increasing length of oligoamines.

  19. Preparation of superhydrophobic poly(methyl methacrylate)-silicon dioxide nanocomposite films

    NASA Astrophysics Data System (ADS)

    Wang, Jinyan; Chen, Xinhua; Kang, Yingke; Yang, Guangbin; Yu, Laigui; Zhang, Pingyu

    2010-12-01

    Superhydrophobic poly(methyl methacrylate)-SiO 2 (coded as PMMA-SiO 2) nanocomposite films with micro-nanohierarchical structure were prepared via a simple approach in the absence of low surface-energy compounds. By spin-coating the suspension of hydrophobic silica (SiO 2) nanoparticles dispersed in PMMA solution, target nanocomposite films were obtained on glass slides. The wetting behavior of PMMA-SiO 2 nanocomposite films was investigated in relation to the dosage of SiO 2 nanoparticles dispersed in PMMA solution. It was found that hydrophilic PMMA film was transferred to superhydrophobic PMMA-SiO 2 nanocomposite films when hydrophobic SiO 2 nanoparticles were introduced into the PMMA solution at a high enough dosage (0.2 g and above). Resultant PMMA-SiO 2 nanocomposite films had a static water contact angle of above 162°, showing promising applications in selfcleaning and waterproof for outer wall of building, outer covering for automobile, sanitary wares, and so forth.

  20. Dynamic mechanical analysis of single walled carbon nanotubes/polymethyl methacrylate nanocomposite films

    NASA Astrophysics Data System (ADS)

    Ali, Badawi; Al Hosiny, N.

    2015-10-01

    Dynamic mechanical properties of nanocomposite films with different ratios of single walled carbon nanotubes/polymethyl methacrylate (SWCNTs/PMMA) are studied. Nanocomposite films of different ratios (0, 0.5, 1.0, and 2.0 weight percent (wt%)) of SWCNTs/PMMA are fabricated by using a casting technique. The morphological and structural properties of both SWCNT powder and SWCNTs/PMMA nanocomposite films are investigated by using a high resolution transmission electron microscope and x-ray diffractometer respectively. The mechanical properties including the storage modulus, loss modulus, loss factor (tan δ) and stiffness of the nanocomposite film as a function of temperature are recorded by using a dynamic mechanical analyzer at a frequency of 1 Hz. Compared with pure PMMA film, the nanocomposite films with different ratios of SWCNTs/PMMA are observed to have enhanced storage moduli, loss moduli and high stiffness, each of which is a function of temperature. The intensity of the tan δ peak for pure PMMA film is larger than those of the nanocomposite films. The glass transition temperature (Tg) of SWCNTs/PMMA nanocomposite film shifts towards the higher temperature side with respect to pure PMMA film from 91.2 °C to 99.5 °C as the ratio of SWCNTs/PMMA increases from 0 to 2.0 wt%. Project supported by Taif University (Grant No. 1/435/3524).

  1. Hot-Press Molded Poly(Methyl Methacrylate) Matrix for Solid-State Dye Lasers

    NASA Astrophysics Data System (ADS)

    Yee, Kwong-Cheong; Tou, Teck-Yong; Ng, Seik-Weng

    1998-09-01

    A hot-press molding method was used to fabricate dye-doped poly(methyl methacrylate) (PMMA) slabs. Three rhodamine dyes, Rh640 (ClO 4 ), Rh6G(ClO 4 ), and Rh6G (Cl), were impregnated into the PMMA matrix first by dissolving the dye and granular PMMA in a solvent mixture of chloroform and methanol and then heating the mixture in vacuo at 175 C to obtain a spongy preform. The powdered preform was molded into slabs at 175 C and at 1 mbar, to eliminate the formation of bubbles in the slabs. We annealed the slabs for several hours to improve its optical homogeneity and hence its lasing efficiency. When pumped by a 1.5-mJ nitrogen laser, we obtained peak lasing efficiencies of 8% and 7.8%, respectively, for Rh6G (ClO 4 ) and Rh640 (ClO 4 ) in PMMA matrices. The lasing efficiency of Rh6G (ClO 4 )-doped PMMA suffered a reduction rate of 0.012% shot compared with 0.15% shot for Rh640 (ClO 4 )-doped PMMA. In contrast, Rh6G (Cl) in a hot-press molded PMMA slab suffered thermal bleaching that resulted in a low lasing efficiency of 1%; this can be explained by its absorption and fluorescence characteristics.

  2. Comparison of decentration and tilt between one piece and three piece polymethyl methacrylate intraocular lenses

    PubMed Central

    Hayashi, K.; Hayashi, H.; Nakao, F.; Hayashi, F.

    1998-01-01

    BACKGROUND—The extent of the decentration and tilt was prospectively compared between one piece polymethyl methacrylate (PMMA) and three piece PMMA intraocular lenses (IOLs) which were implanted in the capsular bag after performing continuous curvilinear capsulorhexis.
METHODS—91 patients underwent a one piece PMMA IOL implantation in one eye as well as the implantation of the three piece PMMA IOL with polyvinylidene fluoride loops in the opposite eye. The length of the lens decentration and the angle of the tilt were quantitated using the anterior eye segment analysis system (EAS-1000) at 1 week as well as 1, 3, and 6 months postoperatively.
RESULTS—The mean length of the decentration in the one piece IOL was smaller than that in the three piece IOL at 1 week (p=0.0092), 1 month (p=0.0044), 3 months (p=0.0069), and 6 months (p=0.0010) postoperatively. However, no significant difference was found in the degree of the tilt between the two types of IOLs throughout the observation periods.
CONCLUSION—These results clarified that the one piece PMMA IOL with rigid PMMA haptics implanted in the capsular bag provides a better centration than the three piece PMMA IOL with flexible haptics, whereas the tilt was the same between the two types of IOLs.

 Keywords: intraocular lens; decentration; tilt; continuous curvilinear capsulorhexis PMID:9640193

  3. Customized Cranioplasty Implants Using Three-Dimensional Printers and Polymethyl-Methacrylate Casting

    PubMed Central

    Kim, Bum-Joon; Hong, Ki-Sun; Park, Kyung-Jae; Park, Dong-Hyuk; Chung, Yong-Gu

    2012-01-01

    Objective The prefabrication of customized cranioplastic implants has been introduced to overcome the difficulties of intra-operative implant molding. The authors present a new technique, which consists of the prefabrication of implant molds using three-dimensional (3D) printers and polymethyl-methacrylate (PMMA) casting. Methods A total of 16 patients with large skull defects (>100 cm2) underwent cranioplasty between November 2009 and April 2011. For unilateral cranial defects, 3D images of the skull were obtained from preoperative axial 1-mm spiral computed tomography (CT) scans. The image of the implant was generated by a digital subtraction mirror-imaging process using the normal side of the cranium as a model. For bilateral cranial defects, precraniectomy routine spiral CT scan data were merged with postcraniectomy 3D CT images following a smoothing process. Prefabrication of the mold was performed by the 3D printer. Intraoperatively, the PMMA implant was created with the prefabricated mold, and fit into the cranial defect. Results The median operation time was 184.36±26.07 minutes. Postoperative CT scans showed excellent restoration of the symmetrical contours and curvature of the cranium in all cases. The median follow-up period was 23 months (range, 14-28 months). Postoperative infection was developed in one case (6.2%) who had an open wound defect previously. Conclusion Customized cranioplasty PMMA implants using 3D printer may be a useful technique for the reconstruction of various cranial defects. PMID:23346326

  4. The use of polymethyl-methacrylate (Artecoll) as an adjunct to facial reconstruction

    PubMed Central

    Mok, David; Schwarz, Jorge

    2004-01-01

    BACKGROUND: Injectable polymethyl-methacrylate (PMMA) microspheres, or Artecoll, has been used for the last few years in aesthetic surgery as long-term tissue filler for the correction of wrinkles and for lip augmentation. This paper presents three cases of the use of PMMA microsphere injection for reconstructive patients with defects of varying etiologies. These cases provide examples of a novel adjunct to the repertoire of the reconstructive surgeon. OBJECTIVES: To evaluate the effectiveness (short- and long-term) of PMMA injection for the correction of small soft tissue defects of the face. METHODS: Three case histories are presented. They include the origin of the defect; previous reconstructions of the defect; and area, volume, timing and technical particularities of PMMA administration. RESULTS: All three cases showed improvement of the defect with the PMMA injection with respect to both objective evidence and patient satisfaction. The improvements can still be seen after several years. CONCLUSIONS: PMMA microsphere injection can be effectively used to correct selected small facial defects in reconstructive cases and the results are long lasting. PMID:24115873

  5. Rapid Prototyping of Poly(methyl methacrylate) Microfluidic Systems Using Solvent Imprinting and Bonding

    PubMed Central

    Sun, Xiuhua; Peeni, Bridget A.; Yang, Weichun; Becerril, Hector A.

    2011-01-01

    We have developed a method for rapid prototyping of hard polymer microfluidic systems using solvent imprinting and bonding. We investigated the applicability of patterned SU-8 photoresist on glass as an easily fabricated template for solvent imprinting. Poly(methyl methacrylate) (PMMA) exposed to acetonitrile for 2 min then had an SU-8 template pressed into the surface for 10 min, which provided appropriately imprinted channels and a suitable surface for bonding. After a PMMA cover plate had also been exposed to acetonitrile for 2 min, the imprinted and top PMMA pieces could be bonded together at room temperature with appropriate pressure. The total fabrication time was less than 15 min. Under the optimized fabrication conditions, nearly 30 PMMA chips could be replicated using a single patterned SU-8 master with high chip-to-chip reproducibility. Relative standard deviations were 2.3% and 5.4% for the widths and depths of the replicated channels, respectively. Fluorescently labeled amino acid and peptide mixtures were baseline separated using these PMMA microchips in <15 s. Theoretical plate numbers in excess of 5000 were obtained for a ~3 cm separation distance, and the migration time relative standard deviation for an amino acid peak was 1.5% for intra-day and 2.2% for inter-day analysis. This new solvent imprinting and bonding approach significantly simplifies the process for fabricating microfluidic structures in hard polymers such as PMMA. PMID:17466320

  6. Biomolecular functionalization for enhanced cell–material interactions of poly(methyl methacrylate) surfaces

    PubMed Central

    Punet, Xavier; Mauchauffé, Rodolphe; Rodríguez-Cabello, José C.; Alonso, Matilde; Engel, Elisabeth; Mateos-Timoneda, Miguel A.

    2015-01-01

    The integration of implants or medical devices into the body tissues requires of good cell–material interactions. However, most polymeric materials used for these applications lack on biological cues, which enhanced mid- and long-term implant failure due to weak integration with the surrounding tissue. Commonly used strategies for tissue–material integration focus on functionalization of the material surface by means of natural proteins or short peptides. However, the use of these biomolecules involves major drawbacks such as immunogenic problems and oversimplification of the constructs. Here, designed elastin-like recombinamers (ELRs) are used to enhance poly(methyl methacrylate) surface properties and compared against the use of short peptides. In this study, cell response has been analysed for different functionalization conditions in the presence and absence of a competing protein, which interferes on surface–cell interaction by unspecific adsorption on the interface. The study has shown that ELRs can induce higher rates of cell attachment and stronger cell anchorages than short peptides, being a better choice for surface functionalization. PMID:26816640

  7. Quantum-classical calculations of X-ray photoelectron spectra of polymers-Polymethyl methacrylate revisited.

    PubMed

    Löytynoja, T; Harczuk, I; Jänkälä, K; Vahtras, O; Ågren, H

    2017-03-28

    In this work, we apply quantum mechanics/molecular mechanics (QM/MM) approach to predict core-electron binding energies and chemical shifts of polymers, obtainable via X-ray photoelectron spectroscopy(XPS), using polymethyl methacrylate as a demonstration example. The results indicate that standard parametrizations of the quantum part (basis sets, level of correlation) and the molecular mechanics parts (decomposed charges, polarizabilities, and capping technique) are sufficient for the QM/MM model to be predictive for XPS of polymers. It is found that the polymer environment produces contributions to the XPS binding energies that are close to monotonous with the number of monomer units, totally amounting to approximately an eV decrease in binding energies. In most of the cases, the order of the shifts is maintained, and even the relative size of the differential shifts is largely preserved. The coupling of the internal core-hole relaxation to the polymer environment is found to be weak in each case, amounting only to one or two tenths of an eV. The main polymeric effect is actually well estimated already at the frozen orbital level of theory, which in turn implies a substantial computational simplification. These conclusions are best represented by the cases where the ionized monomer and its immediate surrounding are treated quantum mechanically. If the QM region includes only a single monomer, a couple of anomalies are spotted, which are referred to the QM/MM interface itself and to the neglect of a possible charge transfer.

  8. Hydrogen peroxide filled poly(methyl methacrylate) microcapsules: potential oxygen delivery materials.

    PubMed

    Mallepally, Rajendar R; Parrish, Chance C; Mc Hugh, Mark A M; Ward, Kevin R

    2014-11-20

    This paper describes the synthesis of H₂O₂-H₂O filled poly(methyl methacrylate) (PMMA) microcapsules as potential candidates for controlled O₂ delivery. The microcapsules are prepared by a water-in-oil solvent emulsion and evaporation method. The results of this study describe the effect of process parameters on the characteristics of the microcapsules and on their in vitro performance. The size of the microcapsules, as determined from scanning electron microscopy, ranges from ∼5 to 30 μm and the size distribution is narrow. The microcapsules exhibit an internal morphology with entrapped H₂O₂-H₂O droplets randomly distributed in the PMMA continuous phase. In vitro release studies of 4.5 wt% H₂O₂-loaded microcapsules show that ∼70% of the H₂O₂ releases in 24h. This corresponds to a total O₂ production of ∼12 cc/gram of dry microcapsules. Shelf-life studies show that the microcapsules retain ∼84 wt% of the initially loaded H₂O₂ after nine months storage at 2-8 °C, which is an attractive feature for clinical applications.

  9. Electrospinning of functional poly(methyl methacrylate) nanofibers containing cyclodextrin-menthol inclusion complexes

    NASA Astrophysics Data System (ADS)

    Uyar, Tamer; Nur, Yusuf; Hacaloglu, Jale; Besenbacher, Flemming

    2009-03-01

    Electrospinning of nanofibers with cyclodextrin inclusion complexes (CD-ICs) is particularly attractive since distinct properties can be obtained by combining the nanofibers with specific functions of the CD-ICs. Here we report on the electrospinning of poly(methyl methacrylate) (PMMA) nanofibers containing cyclodextrin-menthol inclusion complexes (CD-menthol-ICs). These CD-menthol-IC functionalized nanofibers were developed with the purpose of producing functional nanofibers that contain fragrances/flavors with high temperature stability, and menthol was used as a model fragrance/flavor material. The PMMA nanofibers were electrospun with CD-menthol-ICs using three type of CD: α-CD, β-CD, and γ-CD. Direct pyrolysis mass spectrometry (DP-MS) studies showed that the thermal evaporation of menthol occurred over a very high and a broad temperature range (100-355 °C) for PMMA/CDmenthol-IC nanowebs, demonstrating the complexation of menthol with the CD cavity and its high temperature stability. Furthermore, as the size of CD cavity increased in the order α-CD<β-CD<γ-CD, the thermal evolution of menthol shifted to higher temperatures, suggesting that the strength of interaction between menthol and the CD cavity is in the order γ-CD>β-CD>α-CD.

  10. Chitosan-functionalized poly(methyl methacrylate) particles by spinning disk processing for lipase immobilization.

    PubMed

    Jenjob, Somkieath; Sunintaboon, Panya; Inprakhon, Pranee; Anantachoke, Natthinee; Reutrakul, Vichai

    2012-07-01

    Chitosan-functionalized poly(methyl methacrylate) (PMMA-CH) particles were prepared by complexation between the negatively charged PMMA particles and the positively charged chitosan via a spinning disk processing. Processing parameters; feed rate and spinning speed, were optimized, which were traced by size distribution profiles of the formed PMMA-CH particles. Their sizes and net surface charges were found to be affected by MWs of chitosan (45, 100, and 230 kDa) used. Microscopic evidences were used to confirm their core-shell morphology. Chemical characteristics and thermal stability of such particles were determined by FTIR and TGA, respectively. Then, their ability to immobilize lipase (EC 3.1.1.3) was conducted and followed through zeta potential measurement. The percentage of lipase adsorption capacity increased with increasing lipase content, but the value decreased when the size of PMMA-CH particles increased. Also, the activity of lipase attached on PMMA-CH particles' surface was preserved and increased with lipase loading.

  11. Preparation, characterization, and oral delivery of insulin loaded carboxylated chitosan grafted poly(methyl methacrylate) nanoparticles.

    PubMed

    Cui, Fuying; Qian, Feng; Zhao, Ziming; Yin, Lichen; Tang, Cui; Yin, Chunhua

    2009-05-11

    To improve the efficiency of insulin via oral administration, pH-sensitive carboxylated chitosan grafted poly(methyl methacrylate) nanoparticles (CCGN) were prepared. CCGN were characterized by (1)H NMR, dynamic light scattering, zeta potential, and transmission electron microscopy, and the hypoglycemic effect of insulin loaded CCGN via the oral route was evaluated in normal and diabetic rats. CCGN exhibited a homogeneous morphology and a spherical shape with core-shell structure. They were aggregated in simulated gastric fluid while separated in simulated intestinal fluid. Insulin was mainly located in the shell of the CCGN via hydrogen bonding, electrostatic interaction, and Van der Waals force. Insulin release from the CCGN exhibited a pH-sensitive property in that it had a slow release rate at pH 2.0 and a fast release rate at pH 6.8 and 7.4. The pharmacological bioavailability after oral administration of insulin loaded CCGN at a dose of 25 IU/kg was found to be 9.7%. Besides, CCGN showed desirable tissue and blood compatibility. Therefore, the CCGN would be a promising delivery carrier for protein drugs via the oral route.

  12. Water sorption and solubility of glass fiber-reinforced denture polymethyl methacrylate resin.

    PubMed

    Miettinen, V M; Vallittu, P K; Docent, D T

    1997-05-01

    Polymethyl methacrylate (PMMA) absorbs water slowly over a period of time, primarily because of the polar properties of the resin molecules. The aim of this study was to determine the water sorption and solubility of heat-cured and chemical-cured glass fiber (GF) PMMA composite used in dentures. The test specimens (n = 5) were fabricated from experimental, unidirectional, continuous GF reinforcement; the GF concentration of the test specimens was approximately 11% by weight. Water sorption and solubility were tested in accordance with International Standards Organization specification No. 1567. The results revealed that the type of acrylate had more of an effect on water sorption than did the presence of GF reinforcement in the test specimen (p = 0.001 and p = 0.049, respectively). In the GF-reinforced test specimens the type of PMMA also affected the water sorption values (p = 0.006). GF reinforcement affected the solubility values of the test specimen (p = 0.002), but the type of acrylate had no effect on solubility (p = 0.585). The results of this study suggest that the water sorption and solubility of unreinforced PMMA and PMMA reinforced with GF are in accordance with International Standards Organization specification No. 1567.

  13. Sequential interpenetrating polymer networks produced from vegetable oil based polyurethane and poly(methyl methacrylate).

    PubMed

    Kong, Xiaohua; Narine, Suresh S

    2008-08-01

    Sequential interpenetrating polymer networks (IPNs) were prepared using polyurethane produced from a canola oil based polyol with primary terminal functional groups and poly(methyl methacrylate) (PMMA). The properties of the material were studied and compared to the IPNs made from commercial castor oil using dynamic mechanical analysis, differential scanning calorimetry, as well as tensile measurements. The morphology of the IPNs was investigated using scanning electron microscopy and transmission electron microscopy. The chemical diversity of the starting materials allowed the evaluation of the effects of dangling chains and graftings on the properties of the IPNs. The polymerization process of canola oil based IPNs was accelerated because of the utilization of polyol with primary functional groups, which efficiently lessened the effect of dangling chains and yielded a higher degree of phase mixing. The mechanical properties of canola oil based IPNs containing more than 75 wt % PMMA were comparable to the corresponding castor oil based IPNs; both were superior to those of the constituent polymers due to the finely divided rubber and plastic combination structures in these IPNs. However, when PMMA content was less than 65 wt %, canola oil based IPNs exhibited a typical mechanical behavior of rigid plastics, whereas castor oil based IPNs showed a typical mechanical behavior of soft rubber. It is proposed that these new IPN materials with high performance prepared from alternative renewable resources can prove to be valuable substitutes for existing materials in various applications.

  14. Traumatic fracture of a polymethyl methacrylate patient-specific cranioplasty implant.

    PubMed

    Ko, Andrew L; Nerva, John D; Chang, Jason J J; Chesnut, Randall M

    2014-01-01

    To present a case of a traumatic fracture of a polymethyl methacrylate (PMMA) patient-specific implant (PSI) for cranioplasty. A 14-year-old boy with a history of right decompressive hemicraniectomy and reconstructive cranioplasty with a PMMA PSI presented after an unhelmeted bicycle accident with somnolence, confusion, seizures, left hemiparesis, and an obviously deformed cranium. Computed tomography scan showed a comminuted, depressed fracture of the implant and cerebral contusions. The implant was seen to be shattered, resulting in displaced, overriding fragments and significant damage to underlying brain. The patient remained neurologically stable. To minimize the number of operations, intervention was delayed while a polyetheretherketone PSI was fabricated. During surgery, it was noted that the fractured pieces of the implant had caused dural lacerations, and some pieces were embedded in brain parenchyma. The fractured PMMA was removed, and the new implant was placed. The patient remained hemiparetic and was later transferred to an inpatient rehabilitation facility. PMMA PSIs are commonly used for large defects and generally have good outcomes with low rates of revision. The case report described involves a shattered PMMA PSI after a traumatic impact, which resulted in hemiparesis. The question arises if this type of complication can be easily avoided with the addition of titanium onlay to restrict displacement in the event of fracture. This onlay represents a minor change of technique that could prevent migration of fracture fragments. Copyright © 2014 Elsevier Inc. All rights reserved.

  15. Poly(methyl methacrylate)-supported polydiacetylene films: unique chromatic transitions and molecular sensing.

    PubMed

    Parambath Kootery, Kaviya; Jiang, Hao; Kolusheva, Sofiya; Vinod, T P; Ritenberg, Margarita; Zeiri, Leila; Volinsky, Roman; Malferrari, Danilo; Galletti, Paola; Tagliavini, Emilio; Jelinek, Raz

    2014-06-11

    Polydiacetylenes (PDAs) constitute a family of conjugated polymers exhibiting unique colorimetric and fluorescence transitions, and have attracted significant interest as chemo- and biosensing materials. We spin-coated PDA films upon poly(methyl methacrylate) (PMMA), and investigated the photophysical properties and sensing applications of the new PDA configuration. Specifically, the as-polymerized blue PDA layer underwent distinct transformations to purple, red, and yellow phases, which could be quantified through conventional color scanning combined with application of image analysis algorithms. Furthermore, we recorded a reversible red-purple PDA transition that was induced by ultraviolet irradiation, a phenomenon that had not been reported previously in PDA film systems. We show that distinct color and fluorescence transitions were induced in the PMMA-supported PDA films by amphiphilic substances-surfactants and ionic liquids-and that the chromatic transformations were correlated to the analyte structures and properties. Overall, this study presents a new chromatic PDA film system in which noncovalent interactions between the PMMA substrate and spin-coated PDA give rise to distinct chromatic properties and molecular sensing capabilities.

  16. Nonlinear optical properties of poly(methyl methacrylate) thin films doped with Bixa Orellana dye

    NASA Astrophysics Data System (ADS)

    Zongo, S.; Kerasidou, A. P.; Sone, B. T.; Diallo, A.; Mthunzi, P.; Iliopoulos, K.; Nkosi, M.; Maaza, M.; Sahraoui, B.

    2015-06-01

    Natural dyes with highly delocalized π-electron systems are considered as promising organic materials for nonlinear optical applications. Among these dyes, Bixa Orellana dye with extended π-electron delocalization is one of the most attractive dyes. Bixa Orellana dye-doped Poly(methyl methacrylate) (PMMA) thin films were prepared through spin coating process for linear and nonlinear optical properties investigation. Atomic force microscopy (AFM) was used to evaluate the roughness of the thin films. The optical constants n and k were evaluated by ellipsometric spectroscopy. The refractive index had a maximum of about 1.456 at 508.5, 523.79 and 511.9 nm, while the maximum of k varies from 0.070 to 0.080 with the thickness. The third order nonlinear optical properties of the hybrid Bixa Orellana dye-PMMA polymer were investigated under 30 ps laser irradiation at 1064 nm with a repetition rate of 10 Hz. In particular the third-order nonlinear susceptibility has been determined by means of the Maker Fringes technique. The nonlinear third order susceptibility was found to be 1.00 × 10-21 m2 V-2 or 0.72 × 10-13 esu. Our studies provide concrete evidence that the hybrid-PMMA composites of Bixa dye are prospective candidates for nonlinear material applications.

  17. Fabrication and characterization of carbon nanotube reinforced poly(methyl methacrylate) nanocomposites.

    PubMed

    Yu, Suzhu; Juay, Yang Kang; Young, Ming Shyan

    2008-04-01

    Multiwall carbon nanotube (CNT) reinforced poly(methyl methacrylate) (PMMA) nanocomposites have been successfully fabricated with melt blending. Two melt blending approaches of batch mixing and continuous extrusion have been used and the properties of the derived nanocomposites have been compared. The interaction of PMMA and CNTs, which is crucial to greatly improve the polymer properties, has been physically enhanced by adding a third party of poly(vinylidene fluoride) (PVDF) compatibilizer. It is found that the electrical threshold for both PMMA/CNT and PMMA/PVDF/CNT nanocomposites lies between 0.5 to 1 wt% of CNTs. The thermal and mechanical properties of the nanocomposites increase with CNTs and they are further increased by the addition of PVDF For 5 wt% CNT reinforced PMMA/PVDF/CNT nanocomposite, the onset of decomposition temperature is about 17 degrees C higher and elastic modulus is about 19.5% higher than those of neat PMMA. Rheological study also shows that the CNTs incorporated in the PMMA/PVDF/CNT nanocomposites act as physical cross-linkers.

  18. Dispersion characteristics and properties of poly(methyl methacrylate)/multi-walled carbon nanotubes nanocomposites.

    PubMed

    Vaudreuil, Sébastien; Labzour, Asmae; Sinha-Ray, Suprakas; El Mabrouk, Khalil; Bousmina, Mosto

    2007-07-01

    The preparation, characterization, and properties of poly(methyl methacrylate) (PMMA)/multi-walled carbon nanotubes (MWCNTs) nanocomposites are described. Nanocomposites have been prepared by melt-blending in a batch mixer. Both unmodified and surface modified MWCNTs have been used for the nanocomposites preparation. Using both unmodified and modified MWCNTs, the effect of surface modification in nanocomposites is investigated by focusing on three major aspects: dispersion characteristics, mechanical properties, and electrical conductivity measurements. Dispersion of the MWCNTs in the PMMA matrix is examined by scanning and transmission electron microscopy that revealed a homogeneous distribution-dispersion of MWCNTs in the PMMA matrix for both unmodified and modified MWCNTs. Thermomechanical behavior is studied by dynamic mechanical analyzer and results showed a substantial improvement in the mechanical properties of PMMA in conjunction to an increase in the elastic behavior. The tensile properties of neat PMMA moderately improved after nanocomposites preparation with both modified and unmodified MWCNTs, however, electrical conductivity of neat PMMA significantly improved after nanocomposites preparation with 2 wt% unmodified MWCNTs. For example, the through plane conductivity increased from 3.6 x 10(-12) S x cm(-1) for neat PMMA to 3.6 x 10(-9) S x cm(-1) for nanocomposite. The various property measurements have been conducted and results have shown that, in overall, surface modifications have very little or no effect on final properties of neat PMMA.

  19. A Sol-Gel-Modified Poly(methyl methacrylate) Electrophoresis Microchip with a Hydrophilic Channel Wall

    SciTech Connect

    Chen, Gang; Xu, Xuejiao; Lin, Yuehe; Wang, Joseph

    2007-07-27

    A sol-gel method was employed to fabricate a poly(methyl methacrylate) (PMMA) electrophoresis microchip that contains a hydrophilic channel wall. To fabricate such a device, tetraethoxysilane (TEOS) was injected into the PMMA channel and was allowed to diffuse into the surface layer for 24 h. After removing the excess TEOS, the channel was filled with an acidic solution for 3 h. Subsequently, the channel was flushed with water and was pretreated in an oven to obtain a sol-gel-modified PMMA microchip. The water contact angle for the sol-gel-modified PMMA was 27.4° compared with 66.3° for the pure PMMA. In addition, the electro-osmotic flow increased from 2.13×10-4 cm2 V-1 s-1 for the native-PMMA channel to 4.86×10-4 cm2 V-1 s-1 for the modified one. The analytical performance of the sol-gel-modified PMMA microchip was demonstrated for the electrophoretic separation of several purines, coupled with amperometric detection. The separation efficiency of uric acid increased to 74 882.3 m-1 compared with 14 730.5 m-1 for native-PMMA microchips. The result of this simple modification is a significant improvement in the performance of PMMA for microchip electrophoresis and microfluidic applications.

  20. Superparamagnetic poly(methyl methacrylate) beads for nattokinase purification from fermentation broth.

    PubMed

    Yang, Chengli; Xing, Jianmin; Guan, Yueping; Liu, Huizhou

    2006-09-01

    An effective method for purification of nattokinase from fermentation broth using magnetic poly(methyl methacrylate) (PMMA) beads immobilized with p-aminobenzamidine was proposed in this study. Firstly, magnetic PMMA beads with a narrow size distribution were prepared by spraying suspension polymerization. Then, they were highly functionalized via transesterification reaction with polyethylene glycol. The surface hydroxyl-modified magnetic beads obtained were further modified with chloroethylamine to transfer the surface amino-modified magnetic functional beads. The morphology and surface functionality of the magnetic beads were examined by scanning electron microscopy and Fourier transform infrared. An affinity ligand, p-aminobenzamidine was covalently immobilized to the amino-modified magnetic beads by the glutaraldehyde method for nattokinase purification directly from the fermentation broth. The purification factor and the recovery of the enzyme activity were found to be 8.7 and 85%, respectively. The purification of nattokinase from fermentation broth by magnetic beads only took 40 min, which shows a very fast purification of nattokinase compared to traditional purification methods.

  1. Effect of ZnO on the Thermal Degradation Behavior of Poly(Methyl Methacrylate) Nanocomposites.

    PubMed

    Japić, Dajana; Marinšek, Marjan; Crnjak Orel, Zorica

    2016-01-01

    The influence of ZnO nanoparticles on the thermal degradation behavior of poly(methyl methacrylate) (PMMA) was tested using thermoanalytical techniques. The studied materials were investigated using TG, DTA, EGA, XRD, SEM and TEM. The ZnO nanoparticles were synthesized via precipitation by adding LiOH into Zn2+ water/ethylene glycol solutions. The ZnO-PMMA nanocomposites were prepared by adding the appropriate amount of ZnO into MMA and subsequent MMA radical polymerization. According to the experimental results and model-free isoconversional activation energy calculations, the addition of ZnO into PMMA played a double role. The ZnO concentrations up to 0.15% stabilized the composite by shifting the degradation interval toward higher temperatures and increasing the apparent activation energy relative to pure PMMA. At higher concentrations, the catalytic effect of ZnO started to prevail and was reflected in the lower temperature intervals of intense PMMA degradation and lower apparent activation energy. The addition of ZnO generally did not change the nature of the PMMA decomposition process.

  2. Characterization and electrolytic cleaning of poly(methyl methacrylate) residues on transferred chemical vapor deposited graphene.

    PubMed

    Sun, Jianbo; Finklea, Harry O; Liu, Yuxin

    2017-03-24

    Poly(methyl methacrylate) (PMMA) residue has long been a critical challenge for practical applications of the transferred chemical vapor deposited (CVD) graphene. Thermal annealing is empirically used for the removal of the PMMA residue; however experiments imply that there are still small amounts of residues left after thermal annealing which are hard to remove with conventional methods. In this paper, the thermal degradation of the PMMA residue upon annealing was studied by Raman spectroscopy. The study reveals that post-annealing residues are generated by the elimination of methoxycarbonyl side chains in PMMA and are believed to be absorbed on graphene via the π-π interaction between the conjugated unsaturated carbon segments and graphene. The post-annealing residues are difficult to remove by further annealing in a non-oxidative atmosphere due to their thermal and chemical stability. An electrolytic cleaning method was shown to be effective in removing these post-annealing residues while preserving the underlying graphene lattice based on Raman spectroscopy and atomic force microscopy studies. Additionally, a solution-gated field effect transistor was used to study the transport properties of the transferred CVD graphene before thermal annealing, after thermal annealing, and after electrolytic cleaning, respectively. The results show that the carrier mobility was significantly improved, and that the p-doping was reduced by removing PMMA residues and post-annealing residues. These studies provide a more in-depth understanding on the thermal annealing process for the removal of the PMMA residues from transferred CVD graphene and a new approach to remove the post-annealing residues, resulting in a residue-free graphene.

  3. Characterization and electrolytic cleaning of poly(methyl methacrylate) residues on transferred chemical vapor deposited graphene

    NASA Astrophysics Data System (ADS)

    Sun, Jianbo; Finklea, Harry O.; Liu, Yuxin

    2017-03-01

    Poly(methyl methacrylate) (PMMA) residue has long been a critical challenge for practical applications of the transferred chemical vapor deposited (CVD) graphene. Thermal annealing is empirically used for the removal of the PMMA residue; however experiments imply that there are still small amounts of residues left after thermal annealing which are hard to remove with conventional methods. In this paper, the thermal degradation of the PMMA residue upon annealing was studied by Raman spectroscopy. The study reveals that post-annealing residues are generated by the elimination of methoxycarbonyl side chains in PMMA and are believed to be absorbed on graphene via the π–π interaction between the conjugated unsaturated carbon segments and graphene. The post-annealing residues are difficult to remove by further annealing in a non-oxidative atmosphere due to their thermal and chemical stability. An electrolytic cleaning method was shown to be effective in removing these post-annealing residues while preserving the underlying graphene lattice based on Raman spectroscopy and atomic force microscopy studies. Additionally, a solution-gated field effect transistor was used to study the transport properties of the transferred CVD graphene before thermal annealing, after thermal annealing, and after electrolytic cleaning, respectively. The results show that the carrier mobility was significantly improved, and that the p-doping was reduced by removing PMMA residues and post-annealing residues. These studies provide a more in-depth understanding on the thermal annealing process for the removal of the PMMA residues from transferred CVD graphene and a new approach to remove the post-annealing residues, resulting in a residue-free graphene.

  4. Bacterial Adhesion and Surface Roughness for Different Clinical Techniques for Acrylic Polymethyl Methacrylate

    PubMed Central

    das Neves, Flávio Domingues; da Mota, Adérito Soares

    2016-01-01

    This study sought to assess the effect of different surface finishing and polishing protocols on the surface roughness and bacterial adhesion (S. sanguinis) to polymethyl methacrylates (PMMA). Fifty specimens were divided into 5 groups (n = 10) according to their fabrication method and surface finishing protocol: LP (3 : 1 ratio and laboratory polishing), NF (Nealon technique and finishing), NP (Nealon technique and manual polishing), MF (3 : 1 ratio and manual finishing), and MP (3 : 1 ratio and manual polishing). For each group, five specimens were submitted to bacterial adhesion tests and analyzed by scanning electron microscopy (SEM). Two additional specimens were subjected to surface topography analysis by SEM and the remaining three specimens were subjected to surface roughness measurements. Data were compared by one-way ANOVA. The mean bacterial counts were as follows: NF, 19.6 ± 3.05; MP, 5.36 ± 2.08; NP, 4.96 ± 1.93; MF, 7.36 ± 2.45; and LP, 1.56 ± 0.62 (CFU). The mean surface roughness values were as follows: NF, 3.23 ± 0.15; MP, 0.52 ± 0.05; NP, 0.60 ± 0.08; MF, 2.69 ± 0.12; and LP, 0.07 ± 0.02 (μm). A reduction in the surface roughness was observed to be directly related to a decrease in bacterial adhesion. It was verified that the laboratory processing of PMMA might decrease the surface roughness and consequently the adhesion of S. sanguinis to this material. PMID:27516775

  5. Bacterial Adhesion and Surface Roughness for Different Clinical Techniques for Acrylic Polymethyl Methacrylate.

    PubMed

    Dantas, Lucas Costa de Medeiros; da Silva-Neto, João Paulo; Dantas, Talita Souza; Naves, Lucas Zago; das Neves, Flávio Domingues; da Mota, Adérito Soares

    2016-01-01

    This study sought to assess the effect of different surface finishing and polishing protocols on the surface roughness and bacterial adhesion (S. sanguinis) to polymethyl methacrylates (PMMA). Fifty specimens were divided into 5 groups (n = 10) according to their fabrication method and surface finishing protocol: LP (3 : 1 ratio and laboratory polishing), NF (Nealon technique and finishing), NP (Nealon technique and manual polishing), MF (3 : 1 ratio and manual finishing), and MP (3 : 1 ratio and manual polishing). For each group, five specimens were submitted to bacterial adhesion tests and analyzed by scanning electron microscopy (SEM). Two additional specimens were subjected to surface topography analysis by SEM and the remaining three specimens were subjected to surface roughness measurements. Data were compared by one-way ANOVA. The mean bacterial counts were as follows: NF, 19.6 ± 3.05; MP, 5.36 ± 2.08; NP, 4.96 ± 1.93; MF, 7.36 ± 2.45; and LP, 1.56 ± 0.62 (CFU). The mean surface roughness values were as follows: NF, 3.23 ± 0.15; MP, 0.52 ± 0.05; NP, 0.60 ± 0.08; MF, 2.69 ± 0.12; and LP, 0.07 ± 0.02 (μm). A reduction in the surface roughness was observed to be directly related to a decrease in bacterial adhesion. It was verified that the laboratory processing of PMMA might decrease the surface roughness and consequently the adhesion of S. sanguinis to this material.

  6. Impact ionisation spectra from hypervelocity impacts using aliphatic poly(methyl methacrylate) microparticle projectiles.

    PubMed

    Burchell, Mark J; Armes, Steven P

    2011-02-28

    We report impact ionisation spectra from spherical poly(methyl methacrylate) (PMMA) microparticles of 724 nm diameter impacting a rhodium target. These projectiles were coated with an ultrathin (~11 nm) overlayer of polypyrrole, an electrically conducting organic polymer; this enabled the accumulation of sufficient surface charge to allow electrostatic acceleration up to speeds of 4 to 8 km s(-1) using a high-voltage Van de Graaff instrument. A grid above the target (held at 3.33 kV cm(-1) with respect to the target) accelerated the cations that were generated during the hypervelocity impacts, and these ions then drifted to a charge detector. By measuring the collected charge vs. time and assuming only single ionisation events, time-of-flight mass spectra were obtained. Strong signals were observed for cationic species with ions of m/z 41, 65 and 115. There were also minor contributions from cations with masses ranging from m/z 29 to 142. The three major signals are assigned to fragment ions (C(3)H(5)(+), C(4)H(5)O(+)/C(5)H(9)(+) and C(6)H(11)O(2)(+)) which are known to be associated with the decomposition of PMMA. These impact ionisation spectra differ significantly from those reported earlier using polystyrene (PS) microparticles. The aliphatic PMMA microparticles generate small (m/z <100) fragment ions more readily at lower speeds than the predominantly aromatic PS microparticles, where speeds of at least 10 km s(-1) are typically required for substantial yields of low-mass fragment ions. This correlates well with the well-known greater chemical and thermal fragility of PMMA compared to PS. The PMMA microparticles should prove useful synthetic mimics for aliphatic carbonaceous micrometeorites. Copyright © 2011 John Wiley & Sons, Ltd.

  7. Polymer PCF Bragg grating sensors based on poly(methyl methacrylate) and TOPAS cyclic olefin copolymer

    NASA Astrophysics Data System (ADS)

    Johnson, Ian. P.; Webb, David J.; Kalli, Kyriacos; Yuan, Wu; Stefani, Alessio; Nielsen, Kristian; Rasmussen, Henrik K.; Bang, Ole

    2011-05-01

    Fibre Bragg grating (FBG) sensors have been fabricated in polymer photonic crystal fibre (PCF). Results are presented using two different types of polymer optical fibre (POF); first multimode PCF with a core diameter of 50μm based on poly(methyl methacrylate) (PMMA) and second, endlessly single mode PCF with a core diameter of 6μm based on TOPAS cyclic olefin copolymer. Bragg grating inscription was achieved using a 30mW continuous wave 325nm helium cadmium laser. Both TOPAS and PMMA fibre have a large attenuation of around 1dB/cm in the 1550nm spectral region, limiting fibre lengths to no longer than 10cm. However, both have improved attenuation of under 10dB/m in the 800nm spectral region, thus allowing for fibre lengths to be much longer. The focus of current research is to utilise the increased fibre length, widening the range of sensor applications. The Bragg wavelength shift of a grating fabricated in PMMA fibre at 827nm has been monitored whilst the POF is thermally annealed at 80°C for 7 hours. The large length of POF enables real time monitoring of the grating, which demonstrates a permanent negative Bragg wavelength shift of 24nm during the 7 hours. This creates the possibility to manufacture multiplexed Bragg sensors in POF using a single phase mask in the UV inscription manufacturing. TOPAS holds certain advantages over PMMA including a much lower affinity for water, this should allow for the elimination of cross-sensitivity to humidity when monitoring temperature changes or axial strain, which is a significant concern when using PMMA fibre.

  8. Terminal-Selective Transesterification of Chlorine-Capped Poly(Methyl Methacrylate)s: A Modular Approach to Telechelic and Pinpoint-Functionalized Polymers.

    PubMed

    Ogura, Yusuke; Terashima, Takaya; Sawamoto, Mitsuo

    2016-04-20

    Terminal-selective transesterification of chlorine-capped poly(methyl methacrylate)s (PMMA-Cl) with alcohols was developed as a modular approach to create telechelic and pinpoint-functionalized polymers. Being sterically less hindered and electronically activated, both the α-end ethyl ester and ω-end methyl ester of PMMA-Cl were efficiently and selectively transesterified with diverse alcohols in the presence of a titanium alkoxide catalyst, while retaining the pendent esters intact, to almost quantitatively give various chlorine-capped telechelic PMMAs. In sharp contrast to conventional telechelic counterparts, the telechelic polymers obtained herein yet carry a chlorine atom at the ω-terminal to further work as a macroinitiator in living radical polymerization. The iterative process of living radical polymerization and terminal-selective transesterification successfully afforded unique pinpoint-functionalized polymers where a single functional monomer unit was introduced into the desired site of the polymer chains.

  9. Simple, green, and clean removal of a poly(methyl methacrylate) film on chemical vapor deposited graphene

    NASA Astrophysics Data System (ADS)

    Park, J.-H.; Jung, W.; Cho, D.; Seo, J.-T.; Moon, Y.; Woo, S. H.; Lee, C.; Park, C.-Y.; Ahn, J. R.

    2013-10-01

    The clean removal of a poly(methyl methacrylate) (PMMA) film on graphene has been an essential part of the process of transferring chemical vapor deposited graphene to a specific substrate, influencing the quality of the transferred graphene. Here we demonstrate that the clean removal of PMMA can be achieved by a single heat-treatment process without the chemical treatment that was adopted in other methods of PMMA removal. The cleanness of the transferred graphene was confirmed by four-point probe measurements, synchrotron radiation x-ray photoemission spectroscopy, optical images, and Raman spectroscopy.

  10. Performance comparison of four kinds of flat nonimaging Fresnel lenses made of polycarbonates and polymethyl methacrylate for concentrated photovoltaics

    NASA Astrophysics Data System (ADS)

    Languy, Fabian; Habraken, Serge

    2011-07-01

    Solar concentrators made of a single refractive primary optics are limited to a concentration ratio of about 1000× [Opt. Express19, A280 (2011)], due only to longitudinal chromatic aberration, while mirrors are limited to ˜46,000× by the angular size of the Sun. To reduce the chromatic aberration while keeping cost-effective systems for concentrated photovoltaics, a study of four different kinds of flat Fresnel doublets made of polycarbonates and polymethyl methacrylate is presented. It reveals that Fresnel doublets may have fewer optical losses than non-Fresnel doublets, with a lower lateral chromatic split allowing for even higher concentration ratio.

  11. Synthesis and properties of poly(methyl methacrylate-2-acrylamido-2-methylpropane sulfonic acid)/PbS hybrid composite

    SciTech Connect

    Preda, N.; Rusen, E.; Musuc, A.; Enculescu, M.; Matei, E.; Marculescu, B.; Fruth, V.; Enculescu, I.

    2010-08-15

    The synthesis of a new hybrid composite based on PbS nanoparticles and poly(methyl methacrylate-2-acrylamido-2-methylpropane sulfonic acid) [P(MMA-AMPSA)] copolymer is reported. The chemical synthesis consists in two steps: (i) a surfactant-free emulsion copolymerization between methyl methacrylate and 2-acrylamido-2-methylpropane sulfonic acid and (ii) the generation of PbS particles in the presence of the P(MMA-AMPSA) latex, from the reaction between lead nitrate and thiourea. The composite was studied by scanning electron microscopy (SEM), X-ray diffraction, FTIR spectroscopy, thermogravimetric analysis and differential scanning calorimetry. The microstructure observed using SEM proves that the PbS nanoparticles are well dispersed in the copolymer matrix. The X-ray diffraction measurements demonstrate that the PbS nanoparticles have a cubic rock salt structure. It was also found that the inorganic semiconductor nanoparticles improve the thermal stability of the copolymer matrix.

  12. The dynamic volume changes of polymerising polymethyl methacrylate bone cement.

    PubMed

    Muller, Scott D; Green, Sarah M; McCaskie, Andrew W

    2002-12-01

    The Swedish hip register found an increased risk of early revision of vacuum-mixed cemented total hip replacements. The influence of cement mixing technique on the dynamic volume change in polymerising PMMA is not well understood and may be relevant to this observation. Applying Archimedes' principle, we have investigated the dynamic volume changes in polymerising cement and determined the influence of mixing technique. All specimens showed an overall volume reduction: hand-mixed 3.4% and vacuum-mixed 6.0%. Regression analysis of sectional porosity and volume reduction showed a highly significant relationship. Hand-mixed porous cement showed a transient volume increase before solidification. However, vacuum-mixed cement showed a progressive volume reduction throughout polymerisation. Transient expansion of porous cement occurs at the critical time of micro-interlock formation, possibly improving fixation. Conversely, progressive volume reduction of vacuum-mixed cement throughout the formation of interlock may damage fixation. Stable fixation of vacuum-mixed cement may depend on additional techniques to offset the altered volumetric behaviour of vacuum-mixed cement.

  13. Synthesis and characterisation of macroporous poly(methyl methacrylate) with plasma-polymerised hydrophilic coating

    NASA Astrophysics Data System (ADS)

    Serrano Aroca, Angel

    This thesis focuses on the synthesis and characterisation of a new macroporous biomatenal made of poly(methyl methacrylate) and plasma-polymerised poly(hydroxyethyl acrylate). A series of porous and non-porous PMMA networks with different degrees of porosity and cross-linker contents were synthesised by polymerisation in the presence of ethanol and bulk polymerisation. Macroporous PMMA was allowed to adsorb 2-hydroxyethyl acrylate monomer vapour. The absence of thermal or photoinitiators makes difficult the initiation of the polymerisation process of the adsorbed monomer. However, by plasma treatment this problem can be solved. This method of forming a pure hydrophilic coating by plasma polymerisation is very interesting because the porosity of the scaffold hardly changes at the end of the process. The DMS spectrum shows that these materials are a new kind of macroporous hydrogel with a high mechanical modulus at room temperature and able to adsorb water while keeping their mechanical properties. Takayanagi's block model was applied to these results to characterise the biphasic behaviour of these systems. Porosity measurements were performed to determine the volume fraction of pores in the samples before and after the plasma treatment. The structure and morphology of these macroporous systems were observed by Scanning Electron Microscope (SEM). The nature, homogeneity and stability of the hydrophilic coating was studied by DSC, ATR FTIR, TGA and immersion in water. It was found that the plPHEA is very stable and only in very drastic conditions (boiling water) can suffer hydrolytic degradation. The water sorption and diffusion properties of these biomaterials were studied by dynamic desorption, contact angle, equilibrium sorption isotherms and immersion experiments. Thermal analysis of water in the hydrophilic layer was performed by DSC. All these experimental techniques suggested that the plasma-polymerised PHEA is more homogeneously interpenetrated with

  14. The wettability of polytetrafluoroethylene and polymethyl methacrylate by aqueous solution of two cationic surfactants mixture.

    PubMed

    Szymczyk, Katarzyna; Zdziennicka, Anna; Jańczuk, Bronisław; Wójcik, Wiesław

    2006-01-01

    Advancing contact angle (theta) measurements were carried out for aqueous solutions of cetyltrimethylammonium bromide (CTAB) and cetylpyridinium bromide (CPyB) mixtures on polytetrafluoroethylene (PTFE) and polymethyl methacrylate (PMMA). The obtained results indicate that the wettability of PTFE and PMMA by aqueous solutions of CTAB and CPyB mixtures depends on the composition and concentration of the mixture; however, synergism in the wettability does not exist. In the range of low concentrations of aqueous solution mixtures there is a linear dependence between the contact angle and composition of the mixtures, but at a concentration close to CMC a deviation from linear dependence is observed. In contrast to Zisman, there is no linear dependence between costheta and the surface tension of aqueous solution of CTAB and CPyB mixtures, but a linear dependence exists between the adhesional and surface tension, and these lines have a slope -1 and -0.34 for PTFE and PMMA, respectively, which suggests that adsorption of CTAB and CPyB mixtures at water-air and PTFE-water is the same, and the orientation of the CTAB and CPyB molecules at both interfaces in the saturated monolayer should also be the same. Adsorption of these mixtures at water-air interface is considerably higher than at PMMA-water interface, and CTAB and CPyB molecules should be parallelly oriented to PMMA surface in the saturated monolayer. Extrapolation of the straight lines to the points corresponding to the surface tension of aqueous solution, which completely spreads over the PTFE and PMMA surface, gives a critical surface tension of wetting equal to 23.44 and 33.13 mN/m, respectively. The value of 23.44 mN/m is higher than that of the surface tension of PTFE, but the value of 33.13 is lower than that of Lifshitz-van der Waals components of PMMA surface tension. On the basis of the critical surface tension, the surface tension of PTFE and PMMA, the Young equation, and thermodynamic analysis of the

  15. Rechargeable microbial anti-adhesive polymethyl methacrylate incorporating silver sulfadiazine-loaded mesoporous silica nanocarriers.

    PubMed

    Jo, Jeong-Ki; El-Fiqi, Ahmed; Lee, Jung-Hwan; Kim, Dong-Ae; Kim, Hae-Won; Lee, Hae-Hyoung

    2017-10-01

    Even though polymethyl methacrylate (PMMA) resin is widely used as a dental material, it has poor microbial anti-adhesive properties, which accelerates oral infections. In this investigation, silver-sulfadiazine (AgSD)-loaded mesoporous silica nanoparticles (Ag-MSNs) were incorporated into PMMA to introduce long-term microbial anti-adhesive effects and to make PMMA a rechargeable resin. After characterization of the Ag-MSNs in terms of their mesoporous characteristics and drug loading capacity, the 3 point flexural test and hardness were evaluated in PMMA incorporating Ag-MSNs (0.5, 1, 2.5 and 5%). Anti-adhesive effects were observed for Candida albicans and Streptococcus oralis with experimental specimens for up to 28days and after recharging with AgSD. A typical spherical morphology and high mesoporosity were observed for the MSNs used for loading AgSD. Incorporation of Ag-MSNs into PMMA (0.5, 1, 2.5 and 5%) sustained its flexural strength but increased its surface hardness. Anti-adhesive effects were observed after 1h of exposure to both microbial species, and the effects accelerated with increasing Ag-MSN incorporation into PMMA. Long-term microbial anti-adhesive effects were observed for up to 14 days, and further long-term (7 days) anti-adhesive effects were observed after reloading the Ag-MSN-incorporated PMMA (aged for 28 days) with AgSD; these effects were largely caused by released silver ions and partially by changes in surface hydrophilicity. No cytotoxicity to keratinocytes was observed. The improved mechanical properties and the prolonged microbial anti-adhesive effects, which lasted after reloading of the drug, suggest the potential usefulness of Ag-MSN-incorporated PMMA as a microbial anti-adhesive dental material. Ag-MSN-incorporated PMMA can be used as a microbial anti-adhesive dental material for dentures, orthodontic devices and provisional restorative materials. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All

  16. IN VITRO WEAR RESISTANCE OF THREE TYPES OF POLYMETHYL METHACRYLATE DENTURE TEETH

    PubMed Central

    Reis, Katia Rodrigues; Bonfante, Gerson; Pegoraro, Luiz Fernando; Conti, Paulo Cesar Rodrigues; de Oliveira, Pedro Cesar Garcia; Kaizer, Osvaldo Bazzan

    2008-01-01

    The wear resistance of denture teeth is important to the longevity of removable prostheses of edentulous patients. The ability of denture teeth to maintain a stable occlusal relationship over time may be influenced by this property. The purpose of this in vitro study was to evaluate the wear resistance of polymethyl methacrylate (PMMA) denture teeth based on their chemical composition when opposed by a ceramic antagonist. The maxillary canines (n=10) of 3 PMMA denture teeth (Trubyte Biotone, cross-linked PMMA; Trilux, highly cross-linked IPN (interpenetrating polymer network)-PMMA; and Vivodent, highly cross-linked PMMA) were secured in an in vitro 2-body wear-testing apparatus that produced sliding contact of the specimens (4.5 cycles/s, sliding distance of 20 mm, under 37°C running water) against glazed or airborne particle abraded ceramic. Wear resistance was measured as height loss (mm) under 300 g (sliding force) after 100,000 cycles, using a digital measuring microscope. Mean values were analyzed by 2-way ANOVA and Tukey's test (α=0.05). The wear of Trubyte Biotone (0.93 ± 0.14 mm) was significantly higher than that of both other types of teeth tested against abraded ceramic (p<0.05). The Vivodent tooth (0.64 ± 0.17 mm) exhibited the best wear resistance among the denture teeth tested against airborne particle abraded ceramic. There were no statistically significant differences (p>0.05) in wear among the 3 denture teeth evaluated against glazed ceramic. Trilux and Vivodent teeth tested against either glazed or airborne particle abraded ceramic did not differ significantly from each other (p<0.05). All teeth showed significantly more wear against airborne particle abraded ceramic than against glazed ceramic (p<0.05). In conclusion, the three types of PMMA denture teeth presented significantly different wear resistance against the abraded ceramic. The high-strength PMMA denture teeth were more wear-resistant than the conventional PMMA denture tooth. PMID

  17. Modulating fibroblast cell proliferation with functionalized poly(methyl methacrylate) based copolymers: chemical composition and monomer distribution effect.

    PubMed

    El Khadali, Fatima; Hélary, Gérard; Pavon-Djavid, Graciela; Migonney, Véronique

    2002-01-01

    Poly(methyl methacrylate)-based terpolymers bearing sulfonate and carboxylate groups have been synthesized by radical copolymerization leading to polymers with random distributions of ionic monomer units. Fibroblast cells were seeded on terpolymers of various molar compositions of ionic groups. Kinetics of the cell proliferation were examined and systematically compared to the nonfunctionalized control polymer, poly(methyl methacrylate). Modulation of cell proliferation was observed on 15% ionic monomer content copolymers of various compositions (R = COO(-)/(COO(-) + SO(3)(-)) and varies from 0 to 1). The inhibition percentage of cell proliferation calculated for each polymer by comparison to the cell proliferation on the control was plotted against R and gave a maximum value for R close to 0.55. Copolymers with ionic group contents higher or lower than 15% exhibit inhibition percentages fitting with those previously observed for the same R values, showing that the hydrophilic properties are not sufficient to explain the modulation effect of this material toward cells. Moreover, for each polymer tested, cells, even if inhibited in growth, were shown to be viable, indicating that the synthesized terpolymers exhibit cytostatic properties excluding any cytotoxic effect. Such polymers may be used for the fabrication of biocompatible intraocular lenses and prevent secondary cataract.

  18. Preparation and properties of the nanocomposites based on poly(methyl methacrylate-co-butyl acrylate) and multiwalled carbon nanotube.

    PubMed

    Jin, Sung-Hun; Lee, Dai-Soo

    2008-09-01

    Nanocomposites, based on multiwalled carbon nanotube (MWCNT) and various acrylic copolymers of poly(methyl methacrylate-co-butyl acrylate)s, were prepared and the effects of the copolymer compositions on the electrical and the dynamic mechanical properties of the nanocomposites investigated. Latices of the acrylic copolymer were prepared by emulsion polymerization, and then mixed with MWCNT dispersed in N-methylpyrrolidone to prepare the nanocomposites. The electrical resistivities of the nanocomposites showed threshold decreases with increasing MWCNT content, due to percolation. The critical MWCNT content (Pc) in the nanocomposites for percolation showed minimum with increasing butyl acrylate content within the poly(methyl methacrylate-co-butyl acrylate). Specifically, the nanocomposites of the acrylic copolymer with a butyl acrylate content of 20-40 wt% showed the lowest Pc value of all the nanocomposites investigated. The nanocomposites showed large increases in the storage moduli in the rubbery plateau region. A decrease in the glass transition temperature (Tg) was observed with the nanocomposites and attributed to the characteristics of the nanocomposites, where the large surface area of MWCNT makes the matrix polymers similar to those of free stand thin film polymers.

  19. Osteo-odonto-keratoprosthesis (OOKP) and the testing of three different adhesives for bonding bovine teeth with optical poly-(methyl methacrylate) (PMMA) cylinder.

    PubMed

    Weisshuhn, K; Berg, I; Tinner, D; Kunz, C; Bornstein, M M; Steineck, M; Hille, K; Goldblum, D

    2014-07-01

    Preparation of the lamina during osteo-odonto-keratoprosthesis (OOKP) design is complex, and its longevity and watertightness important. To date, only acrylic bone cements have been used for bonding the optical cylinder to the tooth dentine. Our aim was to evaluate different dental adhesives for OOKP preparation. Specimens of bovine teeth were produced by preparing 1.5-mm thick dentine slices with holes having a diameter of 3.5 mm. Each group (n=10 per group) was luted with either classic poly-(methyl methacrylate) (PMMA) bone cement, universal resin cement or glass ionomer cement. All specimens underwent force measurement using a uniaxial traction machine. The highest mean force required to break the bond was measured for PMMA bone cement (128.2 N) followed by universal resin cement (127.9 N), with no statistically significant difference. Glass ionomer cement showed significantly lower force resistance (78.1 N). Excellent bonding strength combined with easy application was found for universal resin cement, and thus, it is a potential alternative to acrylic bone cement in OOKP preparation. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  20. Molecular Dynamics Simulations of Hugoniot Relations for Poly[methyl methacrylate

    DTIC Science & Technology

    2011-11-01

    Molecular Dynamics Simulations of Hugoniot Relations for Poly[ methyl methacrylate ] by Tanya L. Chantawansri, Edward F. C. Byrd, Betsy M. Rice...Ground, MD 21005-5066 ARL-TR-5819 November 2011 Molecular Dynamics Simulations of Hugoniot Relations for Poly[ methyl methacrylate ...4. TITLE AND SUBTITLE Molecular Dynamics Simulations of Hugoniot Relations for Poly[ methyl methacrylate ] 5a. CONTRACT NUMBER 5b. GRANT NUMBER

  1. Evaluation of an injectable hydrogel and polymethyl methacrylate in restoring mechanics to compressively fractured spine motion segments.

    PubMed

    Balkovec, Christian; Vernengo, Andrea J; Stevenson, Peter; McGill, Stuart M

    2016-11-01

    Compressive fracture can produce profound changes to the mechanical profile of a spine segment. Minimally invasive repair has the potential to restore both function and structural integrity to an injured spine. Use of both hydrogels to address changes to the disc, combined with polymethyl methacrylate (PMMA) to address changes to the vertebral body, has the potential to facilitate repair. The purpose of this investigation was to determine if the combined use of hydrogel injection and PMMA could restore the mechanical profile of an axially injured spinal motion segment. This is a basic science study evaluating a combination of hydrogel injection and vertebroplasty on restoring mechanics to compressively injured porcine spine motion segments. Fourteen porcine spine motion segments were subject to axial compression until fracture using a dynamic servohydraulic testing apparatus. Rotational and compressive stiffness was measured for each specimen under the following conditions: initial undamaged, fractured, fatigue loading under compression, hydrogel injection, PMMA injection, and fatigue loading under compression. Group 1 received hydrogel injection followed by PMMA injection, whereas Group 2 received PMMA injection followed by hydrogel injection. This study was funded under a Natural Sciences and Engineering Research Council of Canada discovery grant. PMMA injection was found to alter the compressive stiffness properties of axially injured spine motion segments, restoring values from Groups 1 and 2 to 89.3%±29.3% and 81%±27.9% of initial values respectively. Hydrogel injection was found to alter the rotational stiffness properties, restoring specimens in Groups 1 and 2 to 151.5%±81% and 177.2%±54.9% of initial values respectively. Prolonged restoration of function was not possible, however, after further fatigue loading. Using this repair technique, replication of the mechanism of injury appears to cause a rapid deterioration in function of the motion segments

  2. I Situ Laser Interferometry and Fluorescence Quenching Measurements of Poly(methyl Methacrylate) Thin Film Dissolution.

    NASA Astrophysics Data System (ADS)

    Wang, Fei

    The dissolution mechanisms of poly(methyl methacrylate) (PMMA) thin films in selected organic solvents was investigated. The dissolution was monitored using an in situ laser interferometry and fluorescence quenching (LIFQ) technique. Phenanthrene -labeled PMMA (Phe-PMMA) was used as a probe. Solutions of PMMA in toluene were spin-coated onto sapphire substrate to form films approximately 1 μm thick. The LIFQ results show that for PMMA film dissolution the transition layer thickness increases until the dissolution reaches its steady state. Then this final transition layer thickness (FTL) does not change until solvent vanguard molecules reach the surface of the substrate. Thermal history effects on PMMA film dissolution were examined. The dissolution rate decreases with increasing baking temperature and reaches a constant value for annealing at 150^circC. The results show that the thermal history has negligible effect on the factor of reduction f obtained from interferometry measurements. Fluorescence quenching measurements, by contrast, suggest that transition layer thickness decreases with increasing baking temperature. This suggests that the fluorescence quenching part of the LIFQ experiment is sensitive to the Fickian precursor portion of the solvent concentration profile in the film. The dissolution of PMMA films in acetone, 2-butanone, and 2-pentanone was studied. The results show that the dissolution rate decreases significantly with increasing solvent molecular size. Significant differences are found for FTL values calculated from LIFQ experiments and those calculated from f obtained by laser interferometry. Values of f are essentially identical in three solvents used. The effect of non-solvent on PMMA dissolution was studied by using 2-propanol and 2-butanone mixtures as solvents. The dissolution rate decreases with increasing non-solvent content. This indicates a strong thermodynamic effect, especially at high concentration of non-solvent. Molecular weight

  3. Fracture-induced mechanophore activation and solvent healing in poly(methyl methacrylate)

    NASA Astrophysics Data System (ADS)

    Celestine, Asha-Dee N.

    Damage detection is a highly desirable functionality in engineering materials. The potential of using mechanophores, stress-sensitive molecules, as material stress sensors has been established through tensile, compressive and shear tests. Spiropyran (SP) has been the chosen mechanophore and this molecule undergoes a ring opening reaction (activation) upon the application of mechanical stress. This activation is accompanied by a change in color and fluorescence as the colorless SP is converted to the highly colored merocyanine (MC) form. One requirement for SP activation in bulk polymers is large scale plastic deformation. In order to induce this plastic deformation during fracture testing of SP-linked brittle polymers such as poly(methyl methacrylate) (PMMA), rubber nanoparticles can be incorporated into the matrix material. These nanoparticles facilitate the increased shear yielding necessary for SP activation during mechanical testing. Cross-linked SP-PMMA, containing 7.3 wt% rubber nanoparticles is synthesized via a free radical polymerization. Specimens of this material are fabricated for Single Edge Notch Tension (SENT) testing. The rubber toughened SP-PMMA specimens are first prestretched to approximately 35% axial strain to align the spiropyran molecules in the direction of applied force and thus increase the likelihood of fracture-induced activation. After prestretching the specimens are pre-notched and irradiated with 532 nm wavelength light to revert the colored merocyanine to the colorless spiropyran form. Specimens are then fracture tested to failure using the SENT test. The evolution of mechanophore activation is monitored via in situ fluorescence imaging and inspection of the specimens after testing. Activation of the SP is observed ahead of the crack tip and along the propagated crack. Also, the degree of activation is found to increase with crack growth and the size of the activation zone is linearly correlated to the size of the plastic zone ahead

  4. A Room-Temperature Operation Formaldehyde Sensing Material Printed Using Blends of Reduced Graphene Oxide and Poly(methyl methacrylate)

    PubMed Central

    Chuang, Wen-Yu; Yang, Sung-Yuan; Wu, Wen-Jong; Lin, Chih-Ting

    2015-01-01

    This work demonstrates a printable blending material, i.e., reduced graphene oxide (RGO) mixed with poly(methyl methacrylate) (PMMA), for formaldehyde sensing. Based on experimental results, 2% RGO/10% PMMA is an optimal ratio for formaldehyde detection, which produced a 30.5% resistance variation in response to 1000 ppm formaldehyde and high selectivity compared to different volatile organic compounds (VOCs), humidity, CO, and NO. The demonstrated detection limit is 100 ppm with 1.51% resistance variation. Characterization of the developed formaldehyde sensing material was performed by Fourier-transform infrared (FTIR) spectrometry, scanning electron microscopy (SEM), and Raman spectroscopy. Based on Raman spectroscopy, the basic sensing mechanism is the band distortion of RGO due to blending with PMMA and the adsorption of formaldehyde. This work establishes insights into the formaldehyde sensing mechanism and explores a potential printable sensing material for diverse applications. PMID:26580624

  5. DIELECTRIC PROPERTIES OF POLYVINYL ALCOHOL, POLY(METHYL METHACRYLATE), POLYVINYL BUTYRAL RESIN AND POLYIMIDE AT LOW TEMPERATURES

    SciTech Connect

    Tuncer, Enis; Sauers, Isidor; James, David Randy; Ellis, Alvin R

    2008-01-01

    Performance of materials and their compatibility determine the size of the electrical insulation in power equipment. For this reason dielectric properties of electrical insulation materials are needed for low temperature power applications. In this work we report the dielectric properties of four polymers: polyvinyl alcohol (PVA), poly(methyl methacrylate) (PMMA), polyvinyl butyral resin (PVB), and polyimide (PI--Kapton\\textregistered). The dielectric measurements are performed with an electrical impedance analyzer in the frequency domain. The impedances are recorded in a cryocooler in the temperature range from 45K to 350K. The dielectric breakdown characteristics of the polymers are measured in a liquid nitrogen bath at atmospheric pressure. It is observed that PI and \\pmma\\ dissolved in toluene have the lowest dielectric losses for temperatures lower than $100\\ \\kelvin$. \\Blx\\ and PI have the smallest spread in their breakdown strength data.

  6. Biconvex intraocular lenses and Nd:YAG capsulotomy: Experimental comparison of surface damage with different poly(methyl methacrylate) formulations

    SciTech Connect

    Downing, J.E.; Alberhasky, M.T. )

    1990-11-01

    Biconvex posterior chamber lenses have optical advantages and decrease the risk of capsular opacification, but they are more likely to be pitted during ND:YAG capsulotomy because of apposition of the lens to the capsule. This study reports the likelihood of surface damage to different formulations of poly(methyl methacrylate) at the energy levels required to open posterior capsules. Molded lenses are more easily damaged than higher molecular weight lathe-cut materials (P less than .01), as expected. However, by keeping energy output low, even injection-molded lenses showed minimal damage, with mean pit size 39 +/- 39 microns at 1 mJ. By using a converging contact lens, low power, and keeping the focus behind the capsule, damage to all materials tested should be clinically insignificant.

  7. In situ Poly(methyl methacrylate)/Graphene Composite Gel Electrolytes for Highly Stable Dye-Sensitized Solar Cells.

    PubMed

    Kang, Yu-il; Moon, Jun Hyuk

    2015-11-01

    Dye-sensitized solar cells (DSCs) with long-term stability are produced using polymer-gel electrolytes (PGEs). In this study, we introduce the formation of PGEs using in situ gelation with poly(methyl methacrylate) (PMMA) particles and graphene fillers that are pre-deposited on the counter electrodes. We obtain a high concentration PMMA-based PGEs (i.e., over 10 wt%). A DSC composed of a PMMA/graphene composite PGEs exhibits an 8.49% photon-to-electric conversion efficiency, which is comparable to conventional liquid electrolyte DSCs. This finding is attributed to increased ion diffusivity and conductivity of the PMMA-based PGEs resulting from the incorporation of graphene nanofillers. The PMMA-based PGE DSCs exhibit highly stable long-term efficiencies, maintaining up to 90% of their initial efficiency during thermal soaking, whereas the efficiencies of liquid electrolyte cells decrease significantly, by up to 60%.

  8. Detonation Characteristics of Plastic Explosives Based on Attractive Nitramines with Polyisobutylene and Poly(methyl methacrylate) Binders

    NASA Astrophysics Data System (ADS)

    Elbeih, Ahmed; Pachman, Jiri; Zeman, Svatopluk; Vávra, Pavel; Trzciński, Waldemar A.; Akštein, zbyněk

    2012-10-01

    Four highly brisant nitramines, RDX (1,3,5-trinitro-1,3,5-triazinane), HMX (1,3,5,7-tetranitro-1,3,5,7-tetrazocane), BCHMX (cis-1,3,4,6-tetranitro-octahydroimidazo-[4,5-d]imidazole), and ɛ-HNIW (ɛ-2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane), were studied as extruded plastic explosives bonded by two plastic matrices based on polyisobutylene (C4 matrix) and poly-methylmethacrylate (plasticized by dioctyl-adipate) binders. The detonation velocities, D, were measured experimentally. Detonation parameters were also calculated by means of the Kamlet and Jacobs method and CHEETAH and EXPLO5 codes. These detonation parameters showed that plastic-bonded explosives (PBXs) based on BCHMX are more powerful explosives than those based on RDX. The Urizar coefficient for poly(methyl methacrylate) binder was also calculated.

  9. Autophobic dewetting of a poly(methyl methacrylate) thin film on a silicon wafer treated in good solvent vapor.

    PubMed

    Xue, Longjian; Han, Yanchun

    2009-05-05

    The wettability of thin poly(methyl methacrylate) (PMMA) films on a silicon wafer with a native oxide layer exposed to solvent vapors is dependent on the solvent properties. In the nonsolvent vapor, the film spread on the substrate with some protrusions generated on the film surface. In the good solvent vapor, dewetting happened. A new interface formed between the anchored PMMA chains and the swollen upper part of the film. Entropy effects caused the upper movable chains to dewet on the anchored chains. The rim instability depended on the surface tension of solvent (i.e., the finger was generated in acetone vapor (gamma(acetone) = 24 mN/m), not in dioxane vapor (gamma(dioxane) = 33 mN/m)). The spacing (lambda) that grew as an exponential function of film thickness h scaled as approximately h(1.31), whereas the mean size (D) of the resulting droplets grew linearly with h.

  10. Effect of Solvent on the Dielectric Properties of Nanocomposite Poly(methyl methacrylate)-Doped Titanium Dioxide Dielectric Films

    NASA Astrophysics Data System (ADS)

    Nyl Ismail, Lyly; Hafizah Nik Mohamad, Nik Noor; Salleh Shamsudin, Muhamad; Zulkefle, Habibah; Hanapiah Abdullah, Mohd; Herman, Sukreen Hana; Rusop, Mohamad

    2012-06-01

    A poly(methyl methacrylate)-doped titanium dioxide (PMMA:TiO2) nanocomposite film was obtained by spin coating the nanocomposite solution onto a silicon substrate. The nanocomposite solutions were prepared by dissolving the PMMA and TiO2 nanopowder in three different types of organic solvent, namely, toluene, tetrahydrofuran (THF), and acetone. We found that the dielectric properties of the PMMA:TiO2 nanocomposite are dependent on the type of solvent used. The dielectric properties measured at a frequency of 1 kHz showed that acetone gives the highest dielectric constant and capacitance compared with toluene and THF. Toluene gives the lowest dielectric loss among the three. The topography and roughness of the PMMA:TiO2 nanocomposite indicate that a particular solvent results in a different kind of surface morphology.

  11. Electrical detection of spin precession in freely suspended graphene spin valves on cross-linked poly(methyl methacrylate).

    PubMed

    Neumann, Ingmar; Van de Vondel, Joris; Bridoux, German; Costache, Marius V; Alzina, Francesc; Sotomayor Torres, Clivia M; Valenzuela, Sergio O

    2013-01-14

    Spin injection and detection is achieved in freely suspended graphene using cobalt electrodes and a nonlocal spin-valve geometry. The devices are fabricated with a single electron-beam-resist poly(methyl methacrylate) process that minimizes both the fabrication steps and the number of (aggressive) chemicals used, greatly reducing contamination and increasing the yield of high-quality, mechanically stable devices. As-grown devices can present mobilities exceeding 10(4) cm(2) V(-1) s(-1) at room temperature and, because the contacts deposited on graphene are only exposed to acetone and isopropanol, the method is compatible with almost any contacting material. Spin accumulation and spin precession are studied in these nonlocal spin valves. Fitting of Hanle spin precession data in bilayer and multilayer graphene yields a spin relaxation time of ∼125-250 ps and a spin diffusion length of 1.7-1.9 μm at room temperature.

  12. Fabrication of ordered poly(methyl methacrylate) nanobowl arrays using SiO2 colloidal crystal templates.

    PubMed

    Deng, Lier; Fu, Ming; Tao, Yinglei; Guo, Xiaoyun

    2014-06-01

    A simple approach is presented for the fabrication of poly(methyl methacrylate) (PMMA) nanobowl arrays over cm2 areas using SiO2 colloidal crystal templates. SiO2 colloidal crystal templates were prepared on a clean glass substrate by self-assembled SiO2 spheres of 410 nm in diameter. The air between the silica spheres was filled by the superfluous monomer of PMMA that can be subsequently polymerized. After infiltration, the SiO2-PMMA templates were immersed in a 3 wt% hydrofluoric acid (HF) aqueous solution. After 24 h, silica spheres were etched and a free-standing nanobowl sheet was obtained. The size of the nanobowls could be controlled by the size of the SiO2 spheres and the area of the nanobowl sheet could be altered by the size of the glass substrate.

  13. Influence of fabrication conditions on characteristics of phenanthrenequinone-doped poly(methyl methacrylate) photopolymer for holographic memory

    NASA Astrophysics Data System (ADS)

    Lin, Shiuan Huei; Cho, Sheng-Lung; Lin, June-Hua; Hsu, Ken Y.; Chi, Sien

    2014-06-01

    In this paper, we experimentally investigate the influence of the fabrication conditions on holographic characteristics in phenanthrenequinone-doped poly(methyl methacrylate) (PQ:PMMA) bulk photopolymer. In our investigation, the PQ:PMMA bulk samples are fabricated by use of a two-step thermo-polymerization method. We firstly propose to monitor relative viscosity of the monomer solution during the sample preparation to obtain a reliable criterion for material fabrication. We then compare experimentally characteristics of 2-mm thick samples fabricated with different conditions for holographic memory. The results show that the conditions in the first step play a important rule for fabricating bulk PQ:PMMA samples with good optical uniformity. In addition, the conditions in the second step play the rule for controlling the concentration of residual monomer and determine holographic characteristics. These results can provide a useful rule for fabricating bulk PQ:PMMA photopolymers for further applications on volume holographic data storage.

  14. Kinetic study of Candida antarctica lipase B immobilization using poly(methyl methacrylate) nanoparticles obtained by miniemulsion polymerization as support.

    PubMed

    Valério, Alexsandra; Nicoletti, Gabrieli; Cipolatti, Eliane P; Ninow, Jorge L; Araújo, Pedro H H; Sayer, Cláudia; de Oliveira, Débora

    2015-03-01

    With the objective to obtain immobilized Candida antarctica lipase B (CalB) with good activity and improved utilization rate, this study evaluated the influence of enzyme and crodamol concentrations and initiator type on the CalB enzyme immobilization in nanoparticles consisting of poly(methyl methacrylate) (PMMA) obtained by miniemulsion polymerization. The kinetic study of immobilized CalB enzyme in PMMA nanoparticles was evaluated in terms of monomer conversion, particle size, zeta potential, and relative activity. The optimum immobilization condition for CalB was compared with free enzyme in the p-NPL hydrolysis activity measurement. Results showed a higher CalB enzyme stability after 20 hydrolysis cycles compared with free CalB enzyme; in particular, the relative immobilized enzyme activity was maintained up to 40%. In conclusion, PMMA nanoparticles proved to be a good support for the CalB enzyme immobilization and may be used as a feasible alternative catalyst in industrial processes.

  15. Interfacial chemistry of poly(methyl methacrylate) arising from exposure to vacuum-ultraviolet light and atomic oxygen.

    PubMed

    Yuan, Hanqiu; Killelea, Daniel R; Tepavcevic, Sanja; Kelber, Scott I; Sibener, S J

    2011-04-28

    We herein report on the chemical and physical changes that occur in thin films of poly(methyl methacrylate), PMMA, induced by exposure to high-energy vacuum ultraviolet radiation and a supersonic beam of neutral, ground electronic state O((3)P) atomic oxygen. A combination of in situ quartz crystal microbalance and in situ Fourier-transform infrared reflection-absorption spectroscopy were used to determine the photochemical reaction kinetics and mechanisms during irradiation. The surface morphological changes were measured with atomic force microscopy. The results showed there was no enhancement in the mass loss rate during simultaneous exposure of vacuum ultraviolet (VUV) radiation and atomic oxygen. Rather, the rate of mass loss was impeded when the polymer film was exposed to both reagents. This study elucidates the kinetics of photochemical and oxidative reaction for PMMA, and shows that the synergistic effect involving VUV irradiation and exposure to ground state atomic oxygen depends substantially on the relative fluxes of these reagents.

  16. Thermal and Mechanical Properties of Poly(methyl methacrylate)/Poly(vinylidene fluoride-r-hexafluoro propylene) Blends

    NASA Astrophysics Data System (ADS)

    Lee, Steven; Conway, Maeve; Rende, Deniz; Ozisik, Rahmi

    Poly(vinylidene fluoride), PVDF, is a highly crystalline and rigid polymer, and is used in many applications where chemical inertness, resistance to various solvents and environmental degradation are required. Copolymerization of PVDF with hexafluoropropylene (HFP) tends to decrease the amount of crystallinity, thereby, resulting in a more flexible polymer, which provides new applications for PVDF. Various studies were undertaken to investigate the structure and properties of miscible blends of PVDF and poly(methyl methacrylate), PMMA; however, no studies were performed on the blends of P(VDF-HFP) random copolymers and PMMA. In the current study, we investigate the miscibility, and thermal and mechanical properties of P(VDF-HFP)/PMMA blends via differential scanning calorimetry, thermogravimetric analysis, and nanoindentation. Results indicate that increasing PMMA concentration leads to decreased crystallinity and shifting of the crystallization onset temperature during cooling to lower values. This material is based upon work supported by the National Science Foundation under Grant No. CMMI-1538730.

  17. Biconvex intraocular lenses and Nd:YAG capsulotomy: experimental comparison of surface damage with different poly(methyl methacrylate) formulations.

    PubMed

    Downing, J E; Alberhasky, M T

    1990-11-01

    Biconvex posterior chamber lenses have optical advantages and decrease the risk of capsular opacification, but they are more likely to be pitted during ND:YAG capsulotomy because of apposition of the lens to the capsule. This study reports the likelihood of surface damage to different formulations of poly(methyl methacrylate) at the energy levels required to open posterior capsules. Molded lenses are more easily damaged than higher molecular weight lathe-cut materials (P less than .01), as expected. However, by keeping energy output low, even injection-molded lenses showed minimal damage, with mean pit size 39 +/- 39 microns at 1 mJ. By using a converging contact lens, low power, and keeping the focus behind the capsule, damage to all materials tested should be clinically insignificant.

  18. Aqueous-based initiator attachment and ATRP grafting of polymer brushes from poly(methyl methacrylate) substrates.

    PubMed

    Balamurugan, Sreelatha S; Subramanian, Balamurugan; Bolivar, Jowell G; McCarley, Robin L

    2012-10-09

    Many polymers, such as PMMA, are very susceptible to swelling or dissolution by organic solvents. Growing covalently attached polymer brushes from these surfaces by atom-transfer radical polymerization (ATRP) is challenging because of the typical requirement of organic solvent for initiator immobilization. We report an unprecedented, aqueous-based route to graft poly(N-isopropylacrylamide), PNIPAAm, from poly(methyl methacrylate), PMMA, surfaces by ATRP, wherein the underlying PMMA is unaffected. Successful attachment of the ATRP initiator, N-hydroxysuccinimidyl-2-bromo-2-methylpropionate, on amine-bearing PMMA surfaces was confirmed by XPS. From this surface-immobilized initiator, thermoresponsive PNIPAAm brushes were grown by aqueous ATRP to yield optically transparent PNIPAAm-grafted PMMA surfaces. This procedure is valuable, as it can be applied for the aqueous-based covalent attachment of ATRP initiator on any amine-functionalized surface, with subsequent polymerization of a variety of monomers.

  19. Aqueous-Based Initiator Attachment and ATRP Grafting of Polymer Brushes from Poly(methyl methacrylate) Substrates

    PubMed Central

    Balamurugan, Sreelatha S.; Subramanian, Balamurugan; Bolivar, Jowell G.; McCarley, Robin L.

    2012-01-01

    Many polymers, such as PMMA, are very susceptible to swelling or dissolution by organic solvents. Growing covalently attached polymer brushes from these surfaces by ATRP is challenging because of the typical requirement of organic solvent for initiator immobilization. We report an unprecedented, aqueous-based route to graft poly(N-isopropylacrylamide), PNIPAAm, from poly(methyl methacrylate), PMMA, surfaces by atom-transfer radical polymerization (ATRP), wherein the underlying PMMA is unaffected. Successful attachment of the ATRP initiator, N-hydroxysuccinimidyl-2-bromo-2-methylpropionate, on amine-bearing PMMA surfaces was confirmed by XPS. From this surface-immobilized initiator, thermoresponsive PNIPAAm brushes were grown by aqueous ATRP to yield optically transparent PNIPAAm-grafted PMMA surfaces. This procedure is valuable, as it can be applied for the aqueous-based covalent attachment of ATRP initiator on any amine-functionalized surface, with subsequent polymerization of a variety of monomers. PMID:22967226

  20. The formation of hollow poly(methyl methacrylate)/multiwalled carbon nanotube nanocomposite cylinders by microwave irradiation

    NASA Astrophysics Data System (ADS)

    Wang, Huan; Feng, Jiyun; Hu, Xijun; Ng, Ka Ming

    2009-03-01

    Poly(methyl methacrylate) (PMMA)/multiwalled carbon nanotube (MWCNT) nanocomposite particles with 1, 2 and 4 wt% of MWCNTs were prepared by mechanical grinding of PMMA and MWCNT powders in a mortar at room temperature. Both scanning electron microscopy and Raman scattering characterizations revealed that these nanocomposite particles consist of a PMMA core and a MWCNT shell. The PMMA/MWCNT nanocomposite particles were used to fabricate the corresponding nanocomposites in the form of a hollow cylinder with various diameters and heights under 700 W microwave irradiation within 1 min. A mechanism for the fast microwave assisted forming process is proposed. These experimental results may lead to a new technology for forming hollow polymeric articles that is different from the conventional injection and blowing process.

  1. The formation of hollow poly(methyl methacrylate)/multiwalled carbon nanotube nanocomposite cylinders by microwave irradiation.

    PubMed

    Wang, Huan; Feng, Jiyun; Hu, Xijun; Ming Ng, Ka

    2009-03-04

    Poly(methyl methacrylate) (PMMA)/multiwalled carbon nanotube (MWCNT) nanocomposite particles with 1, 2 and 4 wt% of MWCNTs were prepared by mechanical grinding of PMMA and MWCNT powders in a mortar at room temperature. Both scanning electron microscopy and Raman scattering characterizations revealed that these nanocomposite particles consist of a PMMA core and a MWCNT shell. The PMMA/MWCNT nanocomposite particles were used to fabricate the corresponding nanocomposites in the form of a hollow cylinder with various diameters and heights under 700 W microwave irradiation within 1 min. A mechanism for the fast microwave assisted forming process is proposed. These experimental results may lead to a new technology for forming hollow polymeric articles that is different from the conventional injection and blowing process.

  2. High optical and switching performance electrochromic devices based on a zinc oxide nanowire with poly(methyl methacrylate) gel electrolytes

    SciTech Connect

    Chun, Young Tea; Chu, Daping; Neeves, Matthew; Placido, Frank; Smithwick, Quinn

    2014-11-10

    High performance electrochromic devices have been fabricated and demonstrated utilizing a solid polymer electrolyte and zinc oxide (ZnO) nanowire (NW) array counter electrode. The poly(methyl methacrylate) based polymer electrolyte was spin coated upon hydrothermally grown ZnO NW array counter electrodes, while electron beam evaporated NiO{sub x} thin films formed the working electrodes. Excellent optical contrast and switching speeds were observed in the fabricated devices with active areas of 2 cm{sup 2}, exhibiting an optical contrast of 73.11% at the wavelength of 470 nm, combined with a fast switching time of 0.2 s and 0.4 s for bleaching and coloration, respectively.

  3. Synthesis of poly(methyl methacrylate)-block-poly(L-histidine) and its use as a hybrid silver nanoparticle conjugate.

    PubMed

    Shin, Nam Ho; Lee, Jin Kyu; Li, Haiqing; Ha, Chang-Sik; Shchipunov, Yury A; Kim, Il

    2010-10-01

    Poly[(methyl methacrylate)-block-poly(L-histidine)] (PMMA-b-PHIS) was synthesized by combining atom transfer radical polymerization and living ring-opening polymerization of alpha-amino acid-N-carboxyanhydride. The resulting hybrid block copolymer forms reverse micelles in the mixture solution of water and N,N-dimethylformamide (DMF) and self-assembles into PHIS/PMMA core/shell spheres with controllable size in the range of 80 to 250 nm depending on the micellization temperature. The self-assembly of PMMA-b-PHIS was carried out in H2O/DMF (3/7) mixture in the presence of AgNO3. Reduction of the resulting Ag ions encapsulated inside of the reverse micelles yielded an attractive Ag nanoparticle core/polymer shell conjugate system.

  4. Athermal silicon nitride ring resonator by photobleaching of Disperse Red 1-doped poly(methyl methacrylate) polymer.

    PubMed

    Qiu, Feng; Yu, Feng; Spring, Andrew M; Yokoyama, Shiyoshi

    2012-10-01

    To fabricate athermal silicon nitride waveguides, the dimensions of both the core and cladding, refractive index, and thermo-optic coefficients must be controlled precisely. We present a simple and effective method for the postfabrication trimming of silicon nitride ring resonators that overcomes the highly demanding fabrication. In order to manipulate the polymer's refractive index and thermo-optic coefficient, we bleached the Disperse Red 1-doped poly(methyl methacrylate) (DR1/PMMA) top cladding using UV irradiation. After a suitable bleaching time, the temperature-dependent wavelength shift of the ring resonator was reduced from -9.8 to -0.018 pm/°C, which is the lowest shift that we are aware of for an athermal waveguide realized by overlaying a polymer cladding to date.

  5. Current bistability and carrier transport mechanisms of organic bistable devices based on hybrid Ag nanoparticle-polymethyl methacrylate polymer nanocomposites

    NASA Astrophysics Data System (ADS)

    Kim, Won Tae; Jung, Jae Hun; Kim, Tae Whan; Son, Dong Ick

    2010-06-01

    The current bistability and the carrier transport mechanisms of organic bistable devices (OBDs) using Ag nanoparticle-polymethyl methacrylate (PMMA) nanocomposites have been investigated. Current-voltage measurements at 300 K on the Al/Ag nanoparticles embedded in the PMMA layer/indium-tin-oxide devices exhibit a current bistability with an ON/OFF ratio of 103. Write-read-erase-read sequence results demonstrate the switching characteristics of the OBD. The cycling endurance number of the ON/OFF switching for the OBD is above 7×104. The current bistability and carrier transport mechanisms of the OBD fabricated utilizing hybrid Ag nanoparticle-PMMA polymer nanocomposites are described on the basis of the experimental data.

  6. The effect of surfactant chain length on the morphology of poly(methyl methacrylate) microcapsules for fragrance oil encapsulation.

    PubMed

    Tasker, Alison Louise; Hitchcock, James Paul; He, Ling; Baxter, Elaine Alice; Biggs, Simon; Cayre, Olivier Jean

    2016-12-15

    The solvent evaporation method for producing microcapsules relies upon the correct wetting conditions between the three phases involved in the synthesis to allow core-shell morphologies to form. By measuring the interfacial tensions between the oil, polymer and aqueous phases, spreading coefficients can be calculated, allowing the capsule morphology to be predicted. In this work we explore the effect of surfactant chain length on capsule morphology using poly(methyl methacrylate) as the polymer and hexadecane as the core. We compared the predicted morphologies obtained using the polymer as a solid, and the polymer dissolved in dichloromethane to represent the point at which capsule formation begins. We found that using the polymer in its final, solid form gave predictions which were more consistent with our observations. The method was applied to successfully predict the capsule morphologies obtained when commercial fragrance oils were encapsulated. Copyright © 2016. Published by Elsevier Inc.

  7. UV-laser-assisted modification of poly(methyl methacrylate) and its application to capillary-driven-flow immunoassay

    NASA Astrophysics Data System (ADS)

    Fuchiwaki, Y.; Takaoka, H.

    2015-07-01

    A concave microchannel surface was formed by nanosecond pulse laser ablation to allow antibody immobilization on a capillary flow immunoassay chip. Microscopic analysis showed that UV laser ablation of poly(methyl methacrylate) at 193 nm and 1.76 J · cm-2 allowed excellent immobilization of Cy5 conjugated antibody. The concave structure was 10 µm deep and 260 µm wide and supported uniform antibody printing on the microchannel surface. The characteristics of immobilized antibodies on this surface and on a commercially available polymer coating were comparable. Quantitative analysis of procollagen type I C-peptide (PICP) at different concentrations provided a linear relationship in the range 0-600 ng ml-1 PICP, which is sufficient for clinical estimation of PICP in the blood. The results may provide a new benchmark for a mechatronic antibody immobilization-based capillary flow immunoassay chip.

  8. Study of the water structure in poly(methyl methacrylate-block-2-hydroxyethyl methacrylate) and its relationship to platelet adhesion on the copolymer surface.

    PubMed

    Mochizuki, Akira; Namiki, Takahiro; Nishimori, Yusuke; Ogawa, Haruki

    2015-01-01

    The water structure and platelet compatibility of poly(methyl methacrylate (MMA)-block-2-hydroxyethyl methacrylate (HEMA)) were investigated. The molecular weight (Mn) of the polyHEMA segment was kept constant (average: 9600), while the Mn of the polyMMA segment was varied from 1340 to 7390. The equilibrium water content of the copolymers was found to be mainly governed by the HEMA content. The water structure in the copolymers was characterized in terms of the amounts of non-freezing and freezing water (abbreviated as Wnf and Wfz, respectively) using differential scanning calorimetry. It was found that the Wnf for the copolymers were higher than those estimated from the Wnf for the HEMA and MMA homopolymers and that the amount of excess non-freezing water depended on the polyMMA segment length. In addition, X-ray diffraction analysis revealed that some of the copolymers had cold-crystallizable water. These facts suggested that the polyMMA segments were involved in determining the water structures in the copolymers. Furthermore, the platelet compatibility of the copolymers was improved as compared to that of the HEMA homopolymer. It was therefore concluded that the platelet compatibility of the copolymer was related to the amount of excess non-freezing water.

  9. [Study on interface compatibility and fracture resistance of polyglycidyl methacrylate pre-impregnated quartz fiber reinforced polymethyl methacrylate denture base resin].

    PubMed

    Xu, Ming-ming; Yan, Xu; Deng, Xu-ling

    2015-02-18

    To explore the reinforcement of polyglycidyl methacrylate (PGMA) pre-impregnated quartz fiber mesh in denture base materials by investigation of interface compatibility and fracture resistance. 1-layer, 2-layer, 3-layer PGMA pre-impregnated quartz fiber meshes, electrolyzed cobalt-chromium alloy mesh and cobalt-chromium alloy mesh conditioned by metal primer were integrated in polymethyl methacrylate (PMMA) resin by sandwich embedding method. Block samples of 5 groups were prepared (40 mm×15 mm×2 mm). Fracture resistance was determined in a 3-point bending test at 2 mm/min. Scanning electron microscope (SEM), micrographs were taken from the fractured surfaces to analyze the bonding interface compatibility. The group of 3-layer PGMA pre-impregnated quartz fiber mesh presented the highest elastic modulus of 6 406 MPa and flexural strength of 227 MPa among the five groups, while the 1-layer and 2-layer expressed the similar elastic modulus and flexural strength to the pure PMMA group. The metal groups demonstrated better mechanical properties, while the metal surface conditioner played much better. The metal surface conditioner pre-impregnated cobalt-chromium alloy and PGMA pre-impregnated quartz fiber mesh showed compatible interface with PMMA. The mechanical properties were improved by the increasing of the fiber by adding the more meshed. Although the benign interface did help the compatibility, the quantity of the fibers played an important role in the strength.

  10. Preparation and characterization of pH-sensitive and antifouling poly(vinylidene fluoride) microfiltration membranes blended with poly(methyl methacrylate-2-hydroxyethyl methacrylate-acrylic acid).

    PubMed

    Ju, Junping; Wang, Chao; Wang, Tingmei; Wang, Qihua

    2014-11-15

    Functional terpolymer of poly(methyl methacrylate-2-hydroxyethyl methacrylate-acrylic acid) (P(MMA-HEMA-AA)) was synthesized via a radical polymerization method. The terpolymer could be directly blended with poly(vinylidene fluoride) (PVDF) to prepare the microfiltration (MF) membranes via phase separate process. The synthesized polymers were characterized by Fourier transform infrared (FTIR), the nuclear magnetic resonance proton spectra ((1)H NMR). The membrane had the typical asymmetric structure and the hydrophilic side chains tended to aggregate on the membrane surface. The surface enrichment of amphiphilic copolymer and morphology of MF membranes were characterized by Fourier transform infrared attenuated total reflection spectroscopy (FTIR-ATR) and scanning electron microscopy (SEM). The contact angle (CA) and water uptake were also tested to assess the hydrophilicity and wetting characteristics of the polymer surface. The water filtration properties were measured. It was found the modified membranes showed excellent pH-sensitivity and pH-reversibility behavior. Furthermore, the hydrophilicity of the blended membranes increased, and the membranes showed good protein antifouling property. Copyright © 2014 Elsevier Inc. All rights reserved.

  11. Polystyrene nanoparticles based on poly(butyl methacrylate-g-methoxypoly(ethylene glycol)) and poly(methyl methacrylate-g-methoxypoly(ethylene glycol)) graft copolymers.

    PubMed

    Horgan, Adrian; Vincent, Brian

    2003-06-15

    The solubilization of styrene by poly(butyl methacrylate-g-methoxypoly(ethylene glycol)) and poly(methyl methacrylate-g-methoxypoly(ethylene glycol)) graft copolymers has been examined. From turbidity measurements the solubility limit of the monomer in the micelles was obtained and the distribution coefficients were evaluated. Dynamic light scattering revealed that below the solubility limit, solubilization leads to a slight increase in micelle size, while above the solubility limit, there is a dramatic increase in particle size and turbidity as oil-in-water emulsions are formed through coalescence of monomer-swollen micelles. Polymerizations carried out below the solubility limit using the graft copolymer micelles as templates resembled microemulsion polymerizations in nature and led to very fine sterically stabilized polystyrene latex particles. Through careful control of the monomer concentration and the polymerization temperature it was possible to obtain spherical nanosize latex particles with similar size to those of the micelle precursors (10 nm) up to 11% monomer by weight. Polymerizations above the solubility limit, on the other hand, showed similarities with emulsion polymerizations and resulted in larger particles with higher polydispersity.

  12. Biomechanical evaluation of polymethyl methacrylate with the addition of various doses of cefazolin, vancomycin, gentamicin, and silver microparticles.

    PubMed

    Ficklin, Michael G; Kunkel, Kevin A R; Suber, Jonathan T; Gerard, Patrick D; Kowaleski, Michael P

    2016-09-20

    Numerous studies have examined the biomechanics of polymethyl methacrylate (PMMA) with added antibiotics, but direct comparison between studies is difficult. Our purpose was to evaluate the effects of the addition of antibiotic drugs and silver on compressive and bending strength of PMMA. Our null hypothesis was that there would be no significant difference in the compressive strength or bending strength of PMMA with the addition of silver or varying amounts of antibiotic drugs. Polymethyl methacrylate was mixed with cefazolin, gentamicin, vancomycin, or silver; the control was PMMA alone. Antibiotic groups contained 20 g PMMA and 0.5 g, 1 g, 2 g, or 3 g of antibiotic. Silver groups had 0.25 g silver powder alone added to 20 g PMMA or silver with PMMA and 0, 0.5 g or 1 g of antibiotic. Samples underwent four-point bending and compression testing in air at room temperature and prevailing humidity. Pairwise comparisons between groups and to the ASTM and ISO standards were performed. Compression: All antibiotic and silver groups were weaker than the control. Samples with cefazolin tended to be stronger than other antibiotic groups with equivalent doses of antibiotic. All groups were above the ASTM standard, except 3 g vancomycin. Four-point bending: The addition of antibiotics did not significantly affect bending strength in groups with lower doses of antibiotics. The silver + PMMA group was weaker than the control. No groups were significantly below the ISO standard except the 3 g vancomycin group. The addition of antibiotic or silver decreased the biomechanical strength in all samples, but not below the ASTM or ISO standard for most groups. The addition of cefazolin appears to affect strength the least, while high doses of vancomycin alter strength the most.

  13. Analytical strategy for the molecular weight determination of random copolymers of poly(methyl methacrylate) and poly(methacrylic acid).

    PubMed

    Giordanengo, Rémi; Viel, Stéphane; Hidalgo, Manuel; Allard-Breton, Béatrice; Thévand, André; Charles, Laurence

    2010-06-01

    Molecular weight characterization of random amphiphilic copolymers currently represents an analytical challenge. In particular, molecules composed of methacrylic acid (MAA) and methyl methacrylate (MMA) as the repeat units raise issues in commonly used techniques. The present study shows that when random copolymers cannot be properly ionized by MALDI, and hence detected and measured in MS, one possible analytical strategy is to transform them into homopolymers, which are more amenable to this ionization technique. Then, by combining the molecular weight of the so-obtained homopolymers, as measured by MS, with the relative molar proportion of the MMA and MMA units, as given by (1)H NMR spectrum, one can straightforwardly estimate the molecular weight of the initial copolymer. A methylation reaction was performed to transform MAA-MMA copolymer samples into PMMA homopolymers, using trimethylsilyldiazomethane as a derivatization agent. Weight average molecular weight (M(w)) parameters of the MAA-MMA copolymers could then be derived from M(w) values obtained for the methylated MAA-MMA molecules by MALDI, which were also validated by pulsed gradient spin echo (PGSE) NMR. An alkene function in one of the studied copolymer end-groups was also shown to react with the methylation agent, giving rise to MMA-like polymeric by-products characterized by tandem mass spectrometry and which could be avoided by adjusting the amount of the trimethylsilyldiazomethane in the reaction medium.

  14. Dependence of ultraviolet nanosecond laser polymer ablation on polymer molecular weight: Poly(methyl methacrylate) at 248 nm

    NASA Astrophysics Data System (ADS)

    Bounos, Giannis; Selimis, Alexandros; Georgiou, Savas; Rebollar, Esther; Castillejo, Marta; Bityurin, Nikita

    2006-12-01

    We rely on a methodology demonstrated previously for assessing the temperature evolution and polymer viscosity changes in the 248nm irradiation of poly(methyl methacrylate)s (PMMAs) with molecular weights (Mw) ranging from 2.5to996kDa. Briefly, this methodology [G. Bounos et al., J. Appl. Phys. 98, 084317 (2005)] relies on monitoring the formation of aryl products in the irradiation of polymer doped with iodonaphthalene or iodophenanthrene. The results demonstrate that higher temperatures are attained with increasing Mw. The surface temperatures at the corresponding ablation thresholds are estimated to be ˜850-900K for Mw⩾120kDa vs ˜600K for 2.5kDa PMMA. In addition, for all Mw's, melting is demonstrated (viscosity values of ≈101Pas), but it lasts longer for high Mw PMMAs. We ascribe these differences to the fact that low Mw PMMAs dissociate efficiently to desorbing monomers/oligomers, thereby resulting in more efficient energy removal. Even so, the ablation threshold of the high Mw PMMAs is attained at higher fluences. This can be ascribed to the higher fraction of bonds that is required to be broken, and also plausibly to the higher gaseous product pressures that must be attained, for material ejection to be effected. The results are overall well accounted by the bulk photothermal model.

  15. Surface modification of magnesium aluminum hydroxide nanoparticles with poly(methyl methacrylate) via one-pot in situ polymerization

    NASA Astrophysics Data System (ADS)

    Guo, Xiaojun; Zhao, Leihua; Zhang, Li; Li, Jing

    2012-01-01

    Hydrophobic magnesium aluminum hydroxide composite particles (PMMA-MAH) were obtained by means of grafting poly(methyl methacrylate) (PMMA) onto the surface of magnesium aluminum hydroxide(MAH) nanoparticles after a novel type of phosphate coupling agent (DN-27) modification. The introduction of functional double bonds was firstly conducted on the surface of nanoparticles by DN-27 modification, followed by one-pot in situ polymerization on the particles surface using methyl methacrylate (MMA) as monomer, azoisobutyronitrile (AIBN) as initiator and sodium dodecyl sulfate (SDS) as stabilizer to graft PMMA on the surface of DN-27-modified MAH particles. The obtained composite particles were characterized by field-emission scanning electron microscope (FESEM), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), X-ray powder diffraction (XRD). The results show that the organic macromolecule PMMA could be successfully grafted on the surface of DN-27-modified MAH nanoparticles and the thermal stability of the PMMA-MAH composite particles had been improved. Compared with unmodified blank MAH sample, the product obtained with this method possesses better hydrophobic properties such as a higher water contact angle of 108° and a well dispersion.

  16. Dependence of ultraviolet nanosecond laser polymer ablation on polymer molecular weight: Poly(methyl methacrylate) at 248 nm

    SciTech Connect

    Bounos, Giannis; Selimis, Alexandros; Georgiou, Savas; Rebollar, Esther; Castillejo, Marta; Bityurin, Nikita

    2006-12-01

    We rely on a methodology demonstrated previously for assessing the temperature evolution and polymer viscosity changes in the 248 nm irradiation of poly(methyl methacrylate)s (PMMAs) with molecular weights (M{sub w}) ranging from 2.5 to 996 kDa. Briefly, this methodology [G. Bounos et al., J. Appl. Phys. 98, 084317 (2005)] relies on monitoring the formation of aryl products in the irradiation of polymer doped with iodonaphthalene or iodophenanthrene. The results demonstrate that higher temperatures are attained with increasing M{sub w}. The surface temperatures at the corresponding ablation thresholds are estimated to be {approx}850-900 K for M{sub w}{>=}120 kDa vs {approx}600 K for 2.5 kDa PMMA. In addition, for all M{sub w}'s, melting is demonstrated (viscosity values of {approx_equal}10{sup 1} Pa s), but it lasts longer for high M{sub w} PMMAs. We ascribe these differences to the fact that low M{sub w} PMMAs dissociate efficiently to desorbing monomers/oligomers, thereby resulting in more efficient energy removal. Even so, the ablation threshold of the high M{sub w} PMMAs is attained at higher fluences. This can be ascribed to the higher fraction of bonds that is required to be broken, and also plausibly to the higher gaseous product pressures that must be attained, for material ejection to be effected. The results are overall well accounted by the bulk photothermal model.

  17. Influence of the volumes of bis-acryl and poly(methyl methacrylate) resins on their exothermic behavior during polymerization.

    PubMed

    Ha, Jung-Yun; Kim, Sung-Hun; Kim, Kyo-Han; Kwon, Tae-Yub

    2011-01-01

    This study aimed to evaluate the influence of the volumes of a bis-acryl resin (Luxatemp) and a poly(methyl methacrylate) resin (Jet) on their exothermic behaviors during polymerization based on vinyl group conversion. The number of vinyl groups reacted and exotherm were determined based on weight percent of methacrylate groups using FTIR spectroscopy. Temperature changes during polymerization at 23°C were recorded for 20 minutes using a multiple cavity mold overlying a thermocouple. The number of vinyl groups reacted and exotherm of Luxatemp were consistently lower than those of Jet at each resin volume. Mean peak temperature rises of Luxatemp and Jet were in the range of 2.0-6.6°C and 4.2-11.6°C respectively, with Luxatemp and Jet taking 2 and 10 minutes respectively to reach their peak temperatures. As their resin volumes increased, their peak temperatures and total peak areas were also observed to increase significantly (p<0.01).

  18. Novel poly(methyl methacrylate)-based semi-interpenetrating polyelectrolyte gels for rechargeable lithium batteries

    NASA Astrophysics Data System (ADS)

    Kalapala, Saibabu; Easteal, Allan J.

    Novel semi-interpenetrating polymer gel electrolytes designed for use in rechargeable lithium polymer batteries are synthesised from methyl methacrylate and the lithium salt of 2-acrylamido-2-methylpropanesulfonic acid (LiAMPS). The gels are made by first synthesising linear chains of poly(LiAMPS) by free radical polymerisation of LiAMPS dissolved in dimethyl acetamide (DMA) or DMA/ethylene carbonate mixtures, then co-polymerisation of methyl methacrylate and a cross-linking monomer (tetraethyleneglycol diacrylate) to form the semi-interpenetrating network. The electrical conductivity of the gels is determined as a function of LiAMPS and methyl methacrylate (MMA) concentrations, cross-link density, and solvent composition. The conductivity ( σ) is found to be in the range 0.2 ≤ σ ≤ 0.8 mS cm -1 at ambient temperature (20 ± 1 °C).

  19. Temperature dependent luminescence of a europium complex incorporated in poly(methyl methacrylate).

    PubMed

    Liang, Hao; Xie, Fang; Ren, Xiaojun; Chen, Yifa; Chen, Biao; Guo, Fuquan

    2013-12-01

    An europium β-diketonate complex with a dipyrazolyltriazine derivative ligand, Eu(TTA)3DPBT, has been incorporated into poly(methyl methacryate) (PMMA). The influence of temperature on its luminescence properties has been investigated. The fluorescence emission spectra and luminescence lifetimes showed temperature sensitivity. The analysis of the relative intensity ratio (R) of (5)D0 → (7)F2 to (5)D0 → (7)F1 transition and Judd-Ofelt experimental intensity parameters Ω2 indicated that the local structure and asymmetry in the vicinity of europium ions show no obvious change when the temperature is increased.

  20. Preparation and Characterization of Poly(methyl methacrylate)-functionalized Carboxyl Multi-walled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Meng, Qing-jie; Zhang, Xing-xiang; Bai, Shi-he; Wang, Xue-chen

    2007-12-01

    An in situ polymerization process was used to prepare poly (methyl methacrylate) (PMMA)-functionalized carboxyl multi-walled carbon nanotubes using carboxylate carbon nanotubes and methyl methacrylate as reactants and benzoyl peroxide as an initiator agent. The functionalized multi-walled carbon nanotubes were characterized using transmission electron microscope, scanning electron microscope, nuclear magnetic resonance, Fourier transform infrared spectroscopy, thermogravimetric analysis and Raman. The results indicate that the PMMA chains are covalently linked with the surface of carboxylate carbon nanotubes. The surface morphology is controlled by the content of carboxylate carbon nanotubes in the reactants. The PMMA functionalized multi-walled carbon nanotubes are soluble in deuterated chloroform. The storage modulus and tanδ magnitude increase as the content of CCNTs increases up to 0.3%.

  1. Fabrication of Poly(methyl Methacrylate) microfluidic chips by redox-initiated polymerization

    SciTech Connect

    Chen, Jiang; Lin, Yuehe; Chen, Gang

    2007-08-16

    In this report, a method based on the redox-initiated polymerization of methyl methacrylate (MMA) has been developed for the rapid fabrication of PMMA microfluidic chips.The new fabrication approach obviates the need for special equipment and significantly simplifies the process of fabricating microdevices. The attractive performance of the novel PMMA microchips has been demonstrated in connection with contactless conductivity detection for the separation and detection of ionic species.

  2. Flexible fiber-reinforced composites with improved interfacial adhesion by mussel-inspired polydopamine and poly(methyl methacrylate) coating.

    PubMed

    Yi, Mi; Sun, Hongyang; Zhang, Hongcheng; Deng, Xuliang; Cai, Qing; Yang, Xiaoping

    2016-01-01

    To obtain a kind of light-curable fiber-reinforced composite for dental restoration, an excellent interfacial adhesion between the fiber and the acrylate resin matrix is quite essential. Herein, surface modification on glass fibers were carried out by coating them with poly(methyl methacrylate) (PMMA), polydopamine (PDA), or both. The PMMA or PDA coating was performed by soaking fibers in PMMA/acetone solution or dopamine aqueous solution. PDA/PMMA co-coated glass fibers were obtained by further soaking PDA-coated fibers in PMMA/acetone solution. These modified fibers were impregnated with bisphenol A glycidyl methacrylate (Bis-GMA)/triethylene glycol dimethacrylate (TEGDMA) (5:5, w/w) dental resin at a volume fraction of 75%, using unmodified fibers as reference. Light-cured specimens were submitted to evaluations including flexural properties, morphological observation, dynamic mechanical thermal analysis (DMTA) and pull-out test. In comparison with unmodified glass fibers, all the modified glass fibers showed enhancements in flexural strength and modulus of Bis-GMA/TEGDMA resin composites. Results of DMTA and pull-out tests confirmed that surface modification had significantly improved the interfacial adhesion between the glass fiber and the resin matrix. Particularly, the PDA/PMMA co-coated glass fibers displayed the most efficient reinforcement and the strongest interfacial adhesion due to the synergetic effects of PDA and PMMA. It indicated that co-coating method was a promising approach in modifying the interfacial compatibility between inorganic glass fiber and organic resin matrix. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Nano-engineered optical properties of iodine doped poly(methyl methacrylate)

    SciTech Connect

    Mehta, Sheetal Das, Kallol; Keller, Jag Mohan

    2016-05-23

    Poly (methyl methacrylate) (PMMA) and Iodine hybrid matrixes have been prepared and characterized. The optical properties of the prepared I-PMMA hybrid composites were characterized by linear absorption studies and these composites have been found to contain embedded Iodine nanoparticles. The size of the nanoparticles was found to be a function of the Iodine content of PMMA. Refractive index measurements were undertaken for different wavelengths. The results showed that the refractive index of the composite is dependent on thermal annealing and also varies nonlinearly with the doping concentration at low Iodine concentration or in the region of nanoparticles formation.

  4. Crosslinked superhydrophobic films fabricated by simply casting poly(methyl methacrylate-butyl acrylate-hydroxyethyl methacrylate)-b-poly(perfluorohexylethyl methacrylate) solution

    NASA Astrophysics Data System (ADS)

    Wen, Xiufang; Ye, Chao; Cai, Zhiqi; Xu, Shouping; Pi, Pihui; Cheng, Jiang; Zhang, Lijuan; Qian, Yu

    2015-06-01

    This study focuses on the preparation of superhydrophobic films by crosslinkable polymer material-Poly(methyl methacrylate-butyl acrylate-hydroxyethyl methacrylate)-b-Poly(perfluorohexylethyl methacrylate) (P (MMA-BA-HEMA)-b-PFMA) with a simple one-step casting process. Nanoscale micelle particles with core-shell structure was obtained by dissolving the polymer and curing agent in the mixture of acetone and 1H, 1H, 5H octafluoropentyl-1,1,2,2 tetrafluoroethyl ether (FHT). Superhydrophobic films were fabricated by casting the micelle solution on the glass slides. By controlling the polymer concentration and acetone/FHT volume ratio, superhydrophobic polymer film with water contact angle of 153.2 ± 2.1° and sliding angle of 4° was obtained. By introducing a curing agent into the micelle solution, mechanical properties of the films can be improved. The adhension grade and hardness of the crosslinked superhydrophobic films reached 2 grade and 3H, respectively. The hydrophobicity is attributed to the synergistic effect of micro-submicro-nano-meter scale roughness by nanoscale micelle particles and low surface energy of fluoropolymer. This procedure makes it possible for widespread applications of superhydrophobic film due to its simplicity and practicability.

  5. Binding of leachable components of polymethyl methacrylate (PMMA) and peptide on modified SPR chip

    NASA Astrophysics Data System (ADS)

    Szaloki, M.; Vitalyos, G.; Harfalvi, J.; Hegedus, Cs

    2013-12-01

    Many types of polymers are often used in dentistry, which may cause allergic reaction, mainly methyl methacrylate allergy due to the leachable, degradable components of polymerized dental products. The aim of this study was to investigate the interaction between the leachable components of PMMA and peptides by Fourier-transform Surface Plasmon Resonance (FT SPR). In our previous work binding of oligopeptides (Ph.D.-7 and Ph.D.-12 Peptide Library Kit) was investigated to PMMA surface by phage display technique. It was found that oligopeptides bounded specifically to PMMA surface. The most common amino acids were leucine and proline inside the amino acids sequences of DNA of phages. The binding of haptens, as formaldehyde and methacrylic acid, to frequent amino acids was to investigate on the modified gold SPR chip. Self assembled monolayer (SAM) modified the surface of gold chip and ensured the specific binding between the haptens and amino acids. It was found that amino acids bounded to modified SPR gold and the haptens bounded to amino acids by creating multilayer on the chip surface. By the application of phage display and SPR modern bioanalytical methods the interaction between allergens and peptides can be investigated.

  6. Controllable surface morphology and properties via mist polymerization on a plasma-treated polymethyl methacrylate surface.

    PubMed

    Wan, S J; Wang, L; Xu, X J; Zhao, C H; Liu, X D

    2014-02-14

    Surface modification by grafting polymers on solid materials is an important strategy used to improve surface properties. This article reports that under appropriate conditions, very thin layers with desired morphologies may be constructed on a plasma-treated substrate by feeding a small quantity of a monomer with a mist stream carrying droplets produced from monomer solutions. We investigate the effects of process parameters that affect layer morphology, including exposure time to the mist stream, concentration of the monomer solution, and solvent selectivity. For a methyl methacrylate solution in ethanol, nanoparticles are uniformly grown with increasing monomer concentration or exposure time and finally form a porous layer at 3.65 mol L(-1) for 30 min. Decreasing solvent polarity not only affects surface morphology, but also increases hydrophobicity of the resulting surface. With 2,2,3,4,4,4-hexafluorobutyl methacrylate as the monomer, SEM and AFM micrographs indicated that mist polymerization results in numerous microspheres on the activated surface. These experimental results were interpreted by a mechanism in terms of an in situ polymerization accompanied by a phase transformation of the resulting polymer. Specifically, plasma treatment provides highly active cations and radicals to initiate very rapid polymerization, and the resulting polymers are consequently deposited from the liquid onto the surface under phase transition mechanisms.

  7. Characterization of γ-irradiated polymethyl methacrylate by means of mechanical properties and positron annihilation lifetime spectroscopy

    NASA Astrophysics Data System (ADS)

    Rubiolo, G. H.; Somoza, A.; Goyanes, S. N.; Consolati, G.; Marzocca, A. J.

    1999-08-01

    An experimental investigation was undertaken to assess the effect of γ irradiation on the ``structural'' state and the corresponding inelastic deformation behavior of polymethyl methacrylate (PMMA). Uniaxial and constant strain rate compression tests were conducted over a range of strain rates at room temperature on glassy polymer specimens of PMMA subjected to different γ-irradiation doses. Measurements of positron annihilation lifetime spectroscopy were performed on samples before the compression test in an attempt to correlate free volume content with yield stress. A kinetic law of plastic flow considering a local shear transformation in a small volume Ω is used to represent the observed mechanical behavior. The density and size of the clusters are found for the material subjected to different irradiation dose. Positron annihilation lifetime spectroscopy was also used to estimate the size and number density of free volume sites in the polymer specimens. The dependence of both magnitudes with the irradiation dose follows those of the plastic cluster of volume Ω. Both results provide experimental evidence that the density and the size of high free volume sites can be used as an internal state variable for characterizing the mechanical state of glassy polymers.

  8. Thermo-mechanical response of poly(methyl methacrylate) (PMMA) large volumes exposed to time-dependent environmental conditions

    NASA Astrophysics Data System (ADS)

    Fraldi, M.; Esposito, L.; Perrella, G.; Cutolo, A.

    2014-02-01

    Low thermal conductivity and elevated absorbance of large bulky volumes of poly(methyl methacrylate) (PMMA) exposed to moderately aggressive environmental conditions may cooperate to determine critical mechanical conditions, kindling unexpected high thermal stresses values which lead the material to failure. From the engineering point of view, this can be explained as the result of two concomitant phenomena which activate a cascade of events: very sharp thermal gradients engendered by transient thermal processes induced by cyclic environmental conditions, combined with significant bulk heat generation due to the high thermal inertia of massive PMMA volumes, in turn aggravating the steepness of the thermal gradients, may in fact ingenerate severe stress regimes, potentially undermining the structural stability of the material. Moving from these considerations, the present study is aimed to investigate possible rupture of PMMA blocks experiencing heating processes as a consequence of their exposure to outdoor cyclic environmental conditions. The problem is approached by means of both rigorous analytical arguments and the Finite Element based numerical methods, finally exploiting the theoretical outcomes to formulate a hypothesis which might explain the still unclear phenomenon of the sudden breaking of the PMMA structure, named Huge Wine Glass and designed by the world famous Japanese architect Toyo Ito, which occurred in Pescara (Italy) in 2009.

  9. Polymethyl-methacrylate-sorbitol-based capsules as local drug delivery vehicles: an in vitro antibiotic elution study.

    PubMed

    Frank, Dorottya; Cseh, Gellért; Kocsis, Béla; Nagy, Tamás; Borsiczky, Balázs; Tokés-Füzesi, Margit; Miseta, Attila

    2011-03-01

    A PMMA (polymethyl-methacrylate)-sorbitol-based capsule system was recently developed, and the permeability of 16 types of capsules with different wall thicknesses and sorbitol contents tested. By optimizing these two parameters, we showed that capsule permeability could be controlled. Promising preliminary data obtained using BPB (Bromophenol Blue) as diffusion marker prompted us to further investigate the antibiotic release of capsules showing the most appropriate release characteristics. PMMA-sorbitol capsules were prepared with wall thickness of 0.5 or 0.6 mm and 60 or 70 w/w% (weight percent) of sorbitol content. In vitro gentamicin, amikacin, tobramycin releases were determined by using a microbiological agar plate diffusion assay. Capsules released 70-100% of their gentamicin load, substantially superior to Septopal, and showed preferable, extended release profiles when compared with the beads. The release kinetics of amikacin and tobramycin closely resembled those of gentamicin. PMMA-sorbitol capsules have been developed and tested, which make them promising devices for local antibiotic delivery.

  10. Superparamagnetic poly(methyl methacrylate) nanoparticles surface modified with folic acid presenting cell uptake mediated by endocytosis

    NASA Astrophysics Data System (ADS)

    Feuser, Paulo Emilio; Jacques, Amanda Virtuoso; Arévalo, Juan Marcelo Carpio; Rocha, Maria Eliane Merlin; dos Santos-Silva, Maria Claudia; Sayer, Claudia; de Araújo, Pedro H. Hermes

    2016-04-01

    The encapsulation of superparamagnetic nanoparticles (MNPs) in polymeric nanoparticles (NPs) with modified surfaces can improve targeted delivery and induce cell death by hyperthermia. The goals of this study were to synthesize and characterize surface modified superparamagnetic poly(methyl methacrylate) with folic acid (FA) prepared by miniemulsion polymerization (MNPsPMMA-FA) and to evaluate their in vitro cytotoxicity and cellular uptake in non-tumor cells, murine fibroblast (L929) cells and tumor cells that overexpressed folate receptor (FR) β, and chronic myeloid leukemia cells in blast crisis (K562). Lastly, hemolysis assays were performed on human red blood cells. MNPsPMMA-FA presented an average mean diameter of 135 nm and a saturation magnetization (Ms) value of 37 emu/g of iron oxide, as well as superparamagnetic behavior. The MNPsPMMA-FA did not present cytotoxicity in L929 and K562 cells. Cellular uptake assays showed a higher uptake of MNPsPMMA-FA than MNPsPMMA in K562 cells when incubated at 37 °C. On the other hand, MNPsPMMA-FA showed a low uptake when endocytosis mechanisms were blocked at low temperature (4 °C), suggesting that the MNPsPMMA-FA uptake was mediated by endocytosis. High concentrations of MNPsPMMA-FA showed hemocompatibility when incubated for 24 h in human red blood cells. Therefore, our results suggest that these carrier systems can be an excellent alternative in targeted drug delivery via FR.

  11. Effects of coating with different ceromers on the impact strength, transverse strength and elastic modulus of polymethyl methacrylate.

    PubMed

    Gül, Esma Başak; Atala, Mustafa Hayati; Eşer, Bekir; Polat, Nilüfer Tülin; Asiltürk, Meltem; Gültek, Ahmet

    2015-01-01

    The aim of this study was to evaluate the mechanical properties of polymethyl methacrylate (PMMA) after coating with different ceromers. For transverse strength and modulus of elasticity tests, specimens of 65×10×2.5 mm dimensions were prepared (5 groups, n=10). For impact strength test, specimens of 60×7.5×4 mm dimensions were prepared (5 groups, n=10). Test group specimens were coated with one of four different types of ceromers, and specimens in the control group were not coated. After specimens were tested for transverse and impact strengths, the data were analyzed with Kruskal-Wallis and Conover post hoc tests (p<0.05). GLYMOTEOS-TiO2 and A174-TEOS significantly increased the transverse strength of PMMA. All ceromers caused a statistically significant increase in the elastic modulus of PMMA. While GLYMO-TEOS-ZrO2 significantly decreased the impact strength, the other ceromers did not cause any statistically significant difference in impact strength. Coating with ceromers substantially improved the mechanical properties of PMMA.

  12. The Potential Role of Polymethyl Methacrylate as a New Packaging Material for the Implantable Medical Device in the Bladder

    PubMed Central

    Kim, Su Jin; Choi, Bumkyoo; Kim, Kang Sup; Bae, Woong Jin; Hong, Sung Hoo; Lee, Ji Youl; Hwang, Tae-Kon; Kim, Sae Woong

    2015-01-01

    Polydimethylsiloxane (PDMS) is used in implantable medical devices; however, PDMS is not a completely biocompatible material for electronic medical devices in the bladder. To identify novel biocompatible materials for intravesical implanted medical devices, we evaluated the biocompatibility of polymethyl methacrylate (PMMA) by analyzing changes in the levels of macrophages, macrophage migratory inhibitory factor (MIF), and inflammatory cytokines in the bladder. A ball-shaped metal coated with PMMA or PDMS was implanted into the bladders of rats, and after intravesical implantation, the inflammatory changes induced by the foreign body reaction were evaluated. In the early period after implantation, increased macrophage activity and MIF in the urothelium of the bladder were observed. However, significantly decreased macrophage activity and MIF in the bladder were observed after implantation with PMMA- or PDMS-coated metal in the later period. In addition, significantly decreased inflammatory cytokines such as IL-1β, IL-6, and TNF-α were observed with time. Based on these results, we suggest that MIF plays a role in the foreign body reaction and in the biocompatible packaging with PMMA for the implanted medical devices in the bladder. PMID:25705692

  13. Dynamic modification of poly(methyl methacrylate) chips using poly(vinyl alcohol) for glycosaminoglycan disaccharide isomer separation.

    PubMed

    Zhang, Yong; Ping, Guichen; Kaji, Noritada; Tokeshi, Manabu; Baba, Yoshinobu

    2007-09-01

    We describe a microchip electrophoresis (MCE) method for the assay of unsaturated disaccharides of chondroitin sulfates, dermatan sulfates, and hyaluronic acid (HA). Poly(vinyl alcohol) (PVA) could be irreversibly adsorbed onto poly(methyl methacrylate) (PMMA) substrates and this approach was applicable for dynamic coating. The characteristics of the PMMA surface with PVA coating were evaluated in terms of the wettability, EOF, and adsorption of 2-aminoacridone (AMAC)-labeled disaccharide. The water contact angle decreased from 73 degrees on a pristine PMMA surface to 37.5 degrees on a PVA-coated surface, indicating that the PVA coating increased hydrophilicity. EOF was reduced approximately twofold and was relatively stable. Scanning electron microscopy and fluorescence microscopy images showed that adsorption of AMAC-labeled disaccharides was dramatically suppressed. Using the PVA coating, baseline separation of two pairs of glycosaminoglycan (GAG) disaccharide isomers, DeltaDi-diS(B)/DeltaDi-diS(D) and DeltaDi-0S/DeltaDi-HA, was achieved in Tris-borate buffer within 130 s by MCE.

  14. Some aspects of the tensile strength of undirectional glass fibre-polymethyl methacrylate composite used in dentures.

    PubMed

    Vallittu, P K

    1998-02-01

    The aim of this study was to determine the tensile strength and E-modulus of unidirectional denture glass fibre-polymethyl methacrylate (GF-PMMA) composite with various fibre contents. The experimental values of tensile strength and E-modulus were compared with values obtained by a theoretical calculation. Autopolymerized PMMA test specimens (n = 6, per group) were reinforced with unidirectional E-glass fibres which had been wetted in a mixture of PMMA powder and monomer liquid. After storing the test specimens for 40 days in water at 37 degrees C, the tensile strength and E-modulus of the test specimens were measured. The increased amount of fibres in the PMMA matrix (up to 14.8% by weight) increased the mean tensile strength of the test specimens from 40.5 MPa to 91.2 MPa (P < 0.001) and the E-modulus from 2057 MPa to 3751 MPa (P < 0.001). The experimental tensile strength and Emodulus values were considerably lower than those based on the theoretical calculations. This was assumed to be due to the percentage of glass fibres unimpregnated with the PMMA resin. The presence of unimpregnated glass fibres was determined using light microscopy. The results of this study suggest that a new method of incorporating the glass fibres into the PMMA resin matrix should be developed in order to obtain a well-impregnated fibre composite reinforcement with high durability.

  15. Poly(methyl methacrylate) and thiophene-coated single-walled carbon nanotubes for volatile organic compound discrimination

    NASA Astrophysics Data System (ADS)

    Muangrat, Worawut; Chodjarusawad, Thanawee; Maolanon, Rungroj; Pratontep, Sirapat; Porntheeraphat, Supanit; Wongwiriyapan, Winadda

    2016-02-01

    Poly(methyl methacrylate) (PMMA) and thiophene-coated single-walled carbon nanotubes (SWNTs) were fabricated for use in volatile organic compound (VOC) detection. Pristine SWNTs were separately coated with PMMA (PMMA/SWNTs) and thiophene (thiophene/SWNTs) by spin-coating. Pristine SWNTs showed the highest response to methanol, while PMMA/SWNTs enabled 5.4-fold improved dichloromethane detection and thiophene/SWNTs enabled 1.4-fold improved acetone detection compared with pristine SWNTs. The sensor response of PMMA/SWNTs to dichloromethane and that of thiophene/SWNTs to acetone can be attributed to the Hildebrand solubility parameter (HSP). The more similar the HSP, the higher the sensor response. The sensor response of pristine SWNTs to methanol is related to the diffusion coefficient and molecular size. The relationships between the vapor concentration and sensor response of PMMA/SWNTs to dichloromethane and thiophene/SWNTs to acetone are based on Henry’s adsorption isotherm, while that of pristine SWNTs to methanol is based on the Henry-clustering model. Principal component analysis (PCA) results show that dichloromethane, acetone, and methanol were successfully discriminated.

  16. Solvent quality effects on scaling behavior of poly(methyl methacrylate) brushes in the moderate- and high-density regimes.

    PubMed

    Moh, Lionel C H; Losego, Mark D; Braun, Paul V

    2011-04-05

    Herein, we give a detailed experimental analysis for scaling law behavior in the "moderately dense" and "high-density" brush regimes for poly(methyl methacrylate) brushes swollen in a range of solvent conditions. This expansive experimental analysis aims to validate decades of mean field theory predictions on power law scaling behavior of grafted polymer chains. Brushes with grafting densities (σ) ranging from 0.1 to 0.8 nm(-2) are prepared by atom-transfer radical polymerization. The swollen thickness (h) is characterized using liquid cell ellipsometry, and the solvent quality is varied using mixtures of acetone and methanol. In a good solvent, the exponential scaling behavior (h ∝ σ(n)) has the typical n = 1/3 dependency for grafting densities of σ ≤ 0.4 nm(-2). For grafting densities of >0.4 nm(-2), n increases, indicating the transition from the moderately dense to the high-density brush regime. However, in a poor solvent, the scaling behavior is independent of σ and scales as h ∝ σ(0.80), approaching the theoretical expectations of h ∝ σ(1). An abrupt transition between these scaling law behaviors occurs at the Θ-solvent condition of ∼45% (v/v) methanol in acetone. While our experimental results parallel trends predicted by mean field theory, differences are observed and appear to be attributed to self-solvation of the polymer, polydispersity in the molecular weight, and chain termination.

  17. Synthesis of ZnPc loaded poly(methyl methacrylate) nanoparticles via miniemulsion polymerization for photodynamic therapy in leukemic cells.

    PubMed

    Feuser, Paulo Emilio; Gaspar, Pamela Cristina; Jacques, Amanda Virtuoso; Tedesco, Antônio Claudio; Santos Silva, Maria Claudia Dos; Ricci-Júnior, Eduardo; Sayer, Claudia; de Araújo, Pedro Henrique Hermes

    2016-03-01

    The goal of this work was to synthesize and characterize ZnPc loaded poly(methyl methacrylate) (PMMA) nanoparticles (NPs) by miniemulsion polymerization. Biocompatibility assays were performed in murine fibroblast (L929) cells and human peripheral blood lymphocytes (HPBL). Finally, photobiological assays were performed in two leukemic cells: chronic myeloid leukemia in blast crisis (K562) and acute lymphoblastic leukemia (Jurkat). ZnPc loaded PMMA NPs presented an average diameter of 97±2.5 nm with a low polydispersity index and negative surface charge. The encapsulation efficiency (EE %) of ZnPc PMMA NPs was 87%±2.12. The release of ZnPc from PMMA NPs was slow and sustained without the presence of burst effect, indicating homogeneous drug distribution in the polymeric matrix. NP biocompatibility was observed on the treatment of peripheral blood lymphocytes and L929 fibroblast cells. Phototoxicity assays showed that the ZnPc loaded in PMMA NPs was more phototoxic than ZnPc after activation with visible light at 675 nm, using a low light dose of 2J/cm(2) in both leukemic cells (Jurkat and K562). The results from fluorescence microscopy (EB/OA) and DNA fragmentation suggest that the ZnPc loaded PMMA NPs induced cell death by apoptosis. Based on presented results, our study suggests that PDT combined with the use of polymeric NPs, may be an excellent alternative for leukemia treatment. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Flexural properties of poly(methyl methacrylate) resin reinforced with oil palm empty fruit bunch fibers: a preliminary finding.

    PubMed

    John, Jacob; Ann Mani, Shani; Palaniswamy, Kalpana; Ramanathan, Anand; Razak, Abdul Aziz Abdul

    2015-04-01

    The purpose of this preliminary study was to evaluate the flexural properties of poly(methyl methacrylate) (PMMA) reinforced with oil palm empty fruit bunch (OPEFB) fiber. The flexural strength and flexural modulus of three OPEFB fiber-reinforced PMMA were compared with a conventional and a commercially available reinforced PMMA. The three test groups included OPEFB fibers of 0.5 mm thickness, 2.0 mm thickness, and OPEFB cellulose. All test group specimens demonstrated improved flexural strength and flexural modulus over conventional PMMA. Reinforcement with OPEFB cellulose showed the highest mean flexural strength and flexural modulus, which were statistically significant when compared to the conventional and commercially reinforced PMMA used in this study. OPEFB fiber in the form of cellulose and 0.5 mm thickness fiber significantly improved flexural strength and flexural modulus of conventional PMMA resin. Further investigation on the properties of PMMA reinforced with OPEFB cellulose is warranted. Natural OPEFB fibers, especially OPEFB in cellulose form, can be considered a viable alternative to existing commercially available synthetic fiber reinforced PMMA resin. © 2014 by the American College of Prosthodontists.

  19. Electric field poled polymeric nonlinear optical systems: molecular dynamics simulations of poly(methyl methacrylate) doped with disperse red chromophores.

    PubMed

    Tu, Yaoquan; Zhang, Qiong; Agren, Hans

    2007-04-12

    We demonstrate a complete procedure for simulations of electric field poled polymeric nonlinear optical systems with the purpose to evaluate the macroscopic electro-optic coefficients. The simulations cover the electric field poling effects on the chromophore order at the liquid state, the cooling procedure from the liquid to the solid state in the presence of the poling field, and the back-relaxation of the system after the removal of the field. We use Disperse Red chromophore molecules doped in a poly(methyl methacrylate) matrix for a numerical demonstration of the total procedure. On the basis of the simulation results, the polymer mobility and the static properties of the dopant chromophores are derived. In the liquid state, the chromophore molecules are closer to the side chains than to the backbones of the polymer matrix, and after the simulated annealing, the polymer matrix tends to be closely packed, leading to a significant change in the polymer structure around the chromophore molecules. Besides predicting the absolute macroscopic electro-optic coefficient values, the results are used to derive the microscopic origin of these values in terms of geometric and electronic structure, loading, poling, and back-relaxation effects, thereby aiding to establish design principles for optimum guest-host configurations.

  20. Prediction of Three-Dimensional Downward Flame Spread Characteristics over Poly(methyl methacrylate) Slabs in Different Pressure Environments.

    PubMed

    Zhao, Kun; Zhou, Xiao-Dong; Liu, Xue-Qiang; Lu, Lei; Wu, Zhi-Bo; Peng, Fei; Ju, Xiao-Yu; Yang, Li-Zhong

    2016-11-22

    The present study is aimed at predicting downward flame spread characteristics over poly(methyl methacrylate) (PMMA) with different sample dimensions in different pressure environments. Three-dimensional (3-D) downward flame spread experiments on free PMMA slabs were conducted at five locations with different altitudes, which provide different pressures. Pressure effects on the flame spread rate, profile of pyrolysis front and flame height were analyzed at all altitudes. The flame spread rate in the steady-state stage was calculated based on the balance on the fuel surface and fuel properties. Results show that flame spread rate increases exponentially with pressure, and the exponent of pressure further shows an increasing trend with the thickness of the sample. The angle of the pyrolysis front emerged on sample residue in the width direction, which indicates a steady-burning stage, varies clearly with sample thicknesses and ambient pressures. A global non-dimensional equation was proposed to predict the variation tendency of the angle of the pyrolysis front with pressure and was found to fit well with the measured results. In addition, the dependence of average flame height on mass burning rate, sample dimension and pressure was proposed based on laminar diffusion flame theory. The fitted exponent of experimental data is 1.11, which is close to the theoretical value.

  1. Investigation of cross-linking poly(methyl methacrylate) as a guiding material in block copolymer directed self-assembly

    NASA Astrophysics Data System (ADS)

    Seidel, Robert; Rincon Delgadillo, Paulina; Ramirez-Hernandez, Abelardo; Wu, Hengpeng; Her, Youngjun; Yin, Jian; Nealey, Paul; de Pablo, Juan; Gronheid, Roel

    2014-03-01

    Directed self-assembly (DDSA) of block copolymers ((BCP) is attracting a growing amount of interest as a techhnique to expand traditional lithography beyond its current limits. It has reecently been demonstrated that chemoepitaxy can be used to successfully ddirect BCP assembly to form large arrays off high-density features. The imec DSA LiNe flow uses lithography and trim-etch to produce a "prepattern" of cross-linked polystyrene (PS) stripes, which in turn guide the formation of assembled BCPP structures. Thhe entire process is predicated on the preferential interaction of the respective BCP domains with particular regionss of the underlying prepattern. The use of polystyrene as the guiding material is not uniquely required, however, and in fact may not even be preferable. This study investigates an alternate chemistry -- crosslinked poly(methyl methacrylate), X-PMMA, -- as the underlying polymer mat, providing a route to higher auto-affinity and therefore a stronger guiding ability. In addition to tthe advantages of the chemistry under investigation, this study explores the broader theme of extending BCP DSA to other materials.

  2. Poly(methyl methacrylate) Surface Modification for Surfactant-Free Real-Time Toxicity Assay on Droplet Microfluidic Platform.

    PubMed

    Ortiz, Raphael; Chen, Jian Lin; Stuckey, David C; Steele, Terry W J

    2017-04-19

    Microfluidic droplet reactors have many potential uses, from analytical to synthesis. Stable operation requires preferential wetting of the channel surface by the continuous phase which is often not fulfilled by materials commonly used for lab-on-chip devices. Here we show that a silica nanoparticle (SiNP) layer coated onto a Poly(methyl methacrylate) (PMMA) and other thermoplastics surface enhances its wetting properties by creating nanoroughness, and allows simple grafting of hydrocarbon chains through silane chemistry. Using the unusual stability of silica sols at their isoelectric point, a dense SiNP layer is adsorbed onto PMMA and renders the surface superhydrophilic. Subsequently, a self-assembled dodecyltrichlorosilane (DTS) monolayer yields a superhydrophobic surface that allows the repeatable generation of aqueous droplets in a hexadecane continuous phase without surfactant addition. A SiNP-DTS modified chip has been used to monitor bacterial viability with a resazurin assay. The whole process involving sequential reagents injection, and multiplexed droplet fluorescence intensity monitoring is carried out on chip. Metabolic inhibition of the anaerobe Enterococcus faecalis by 30 mg L(-1) of NiCl2 was detected in 5 min.

  3. Facile synthesis of graphene by pyrolysis of poly(methyl methacrylate) on nickel particles in the confined microzones

    SciTech Connect

    Hong, Ningning; Yang, Wei; Bao, Chenlu; Jiang, Saihua; Song, Lei; Hu, Yuan

    2012-12-15

    Graphical abstract: Display Omitted Highlights: ► The GNWs with few defects were synthesized by pyrolyzing PMMA on nickel particles. ► PMMA as carbon source was easily prepared and safe to handle. ► Nickel microparticles were directly used as catalysts without any pre-treatment. ► The method can be used for the low cost and bulk production of graphene. -- Abstract: In this work, multi-layer graphene has been prepared by pyrolyzing poly(methyl methacrylate) (PMMA) on nickel microparticles in the confined microzones formed by organophilic montmorillonite (OMT). Gram-scale of product can be obtained per day by using this method. The obtained graphene was evaluated by scanning and transmission electron microscopy, X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and thermogravimetric analysis. Pyrolytic conditions such as the system composition of the composites, reaction temperature and the size of catalyst are important parameters affecting the morphology and yield of the final product. Based on the experimental observations and reported literatures, a possible formation process is discussed. The synthesis method of graphene is simple, low-cost, and scalable, which is promising for the application in many fields.

  4. Surface Modification of Poly(methyl methacrylate) by Hydrogen-Plasma Exposure and Its Sputtering Characteristics by Ultraviolet Light Irradiation

    NASA Astrophysics Data System (ADS)

    Yoshimura, Satoru; Ikuse, Kazumasa; Sugimoto, Satoshi; Murai, Kensuke; Honjo, Kuniaki; Kiuchi, Masato; Hamaguchi, Satoshi

    2013-09-01

    Surface modification of poly(methyl methacrylate) (PMMA) films by hydrogen-plasma exposure has been studied in the light of sputtering resistance of polymer-based materials in plasma etching processes. Surface measurements of PMMA were performed with X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, and spectroscopic ellipsometry. It has been found that oxygen atoms are preferentially removed from the surface when a PMMA film is subjected to hydrogen-plasma exposure, with the depth of modification being about 40 nm in the case we examined. Hydrogen-plasma exposure is also found to reduce the sputtering yields of PMMA by ultraviolet light irradiation, as in the case of Ar+ ion irradiation [S. Yoshimura et al.: J. Vac. Soc. Jpn. 56 (2013) 129]. The results suggest that PMMA films become hardened and more sputtering resistant due to the formation of a thick (i.e., 40 nm in the case of this study) amorphous carbon layer by hydrogen-plasma exposure. Hydrogen-plasma exposure is thus an effective technique to increase etching resistance of polymer films.

  5. A nanoscale conical polymethyl methacrylate (PMMA) sub-wavelength structure with a high aspect ratio realized by a stamping method.

    PubMed

    Kim, Dae-Seon; Kim, Dong-Hyun; Jang, Jae-Hyung

    2013-04-08

    A high aspect ratio conical sub-wavelength structure (SWS) was designed by using rigorous coupled-wave analysis (RCWA) method and was realized on polymethyl methacrylate (PMMA) film using a stamping technique. The silicon template containing a hexagonal array of conical holes with a period of 350 nm and an aspect ratio of 2.8 was fabricated by electron-beam (e-beam) lithography followed by a two-step etching process. The SWS with a high aspect ratio was easily transferred from the fabricated silicon template to PMMA film using the stamping method. The replicated PMMA SWS has an array of cones with nanoscale tips and an aspect ratio higher than 2.8. The average reflectance and transmittance of the PMMA film with the conical SWS in the wavelength ranging from 500 and 1500 nm was improved from 7.1 and 91.1% to 4.3 and 94.2%, respectively, as compared to flat PMMA film.

  6. Poly(methyl methacrylate) as a self-assembled gate dielectric for graphene field-effect transistors

    SciTech Connect

    Sanne, A.; Movva, H. C. P.; Kang, S.; McClellan, C.; Corbet, C. M.; Banerjee, S. K.

    2014-02-24

    We investigate poly(methyl methacrylate) (PMMA) as a low thermal budget organic gate dielectric for graphene field effect-transistors (GFETs) based on a simple process flow. We show that high temperature baking steps above the glass transition temperature (∼130 °C) can leave a self-assembled, thin PMMA film on graphene, where we get a gate dielectric almost for “free” without additional atomic layer deposition type steps. Electrical characterization of GFETs with PMMA as a gate dielectric yields a dielectric constant of k = 3.0. GFETs with thinner PMMA dielectrics have a lower dielectric constant due to decreased polarization arising from neutralization of dipoles and charged carriers as baking temperatures increase. The leakage through PMMA gate dielectric increases with decreasing dielectric thickness and increasing electric field. Unlike conventional high-k gate dielectrics, such low-k organic gate dielectrics are potentially attractive for devices such as the proposed Bilayer pseudoSpin Field-Effect Transistor or flexible high speed graphene electronics.

  7. The potential role of polymethyl methacrylate as a new packaging material for the implantable medical device in the bladder.

    PubMed

    Kim, Su Jin; Choi, Bumkyoo; Kim, Kang Sup; Bae, Woong Jin; Hong, Sung Hoo; Lee, Ji Youl; Hwang, Tae-Kon; Kim, Sae Woong

    2015-01-01

    Polydimethylsiloxane (PDMS) is used in implantable medical devices; however, PDMS is not a completely biocompatible material for electronic medical devices in the bladder. To identify novel biocompatible materials for intravesical implanted medical devices, we evaluated the biocompatibility of polymethyl methacrylate (PMMA) by analyzing changes in the levels of macrophages, macrophage migratory inhibitory factor (MIF), and inflammatory cytokines in the bladder. A ball-shaped metal coated with PMMA or PDMS was implanted into the bladders of rats, and after intravesical implantation, the inflammatory changes induced by the foreign body reaction were evaluated. In the early period after implantation, increased macrophage activity and MIF in the urothelium of the bladder were observed. However, significantly decreased macrophage activity and MIF in the bladder were observed after implantation with PMMA- or PDMS-coated metal in the later period. In addition, significantly decreased inflammatory cytokines such as IL-1β, IL-6, and TNF-α were observed with time. Based on these results, we suggest that MIF plays a role in the foreign body reaction and in the biocompatible packaging with PMMA for the implanted medical devices in the bladder.

  8. Poly(methyl methacrylate) microchip device integrated with gold nanoelectrode ensemble for in-column biochemical reaction and electrochemical detection.

    PubMed

    Liao, Kuo-Tang; Chen, Chun-Mao; Huang, Hsuan-Jung; Lin, Che-Hsin

    2007-09-21

    This paper proposes a poly(methyl methacrylate) (PMMA) based microchip with an integrated gold nanoelectrode ensemble (GNEE) and a quartet-T loading channel for in-column urea/urease reactions and electrochemical detections. The on-chip GNEE electrode is fabricated using an electrodeless deposition process on a thin polycarbonate (PC) film and bonded directly onto a PMMA substrate to carry out high-performance electrochemical detections. The in-column bio-catalytic reaction of urea/urease is successfully demonstrated utilizing a novel approach based on the different electrokinetic mobilities of urea and urease in capillary electrophoresis (CE) channel. The experimental results significantly show that the GNEE electrode provides a better detection response for the reaction product of ammonia (NH(4)(+)) than a conventional planar gold electrode. The detection results demonstrate a satisfactory determination coefficient (R(2) value) and high reproducibility with a detection limit of 14.8 and 62.8 microM while detecting standard ammonia solution and the urea/urease reaction product of NH(4)(+), respectively. These results confirm the capability of the proposed device for the high-resolution CE-electrochemical detection (CE-ED) of bioanalytical reactions.

  9. Prediction of Three-Dimensional Downward Flame Spread Characteristics over Poly(methyl methacrylate) Slabs in Different Pressure Environments

    PubMed Central

    Zhao, Kun; Zhou, Xiao-Dong; Liu, Xue-Qiang; Lu, Lei; Wu, Zhi-Bo; Peng, Fei; Ju, Xiao-Yu; Yang, Li-Zhong

    2016-01-01

    The present study is aimed at predicting downward flame spread characteristics over poly(methyl methacrylate) (PMMA) with different sample dimensions in different pressure environments. Three-dimensional (3-D) downward flame spread experiments on free PMMA slabs were conducted at five locations with different altitudes, which provide different pressures. Pressure effects on the flame spread rate, profile of pyrolysis front and flame height were analyzed at all altitudes. The flame spread rate in the steady-state stage was calculated based on the balance on the fuel surface and fuel properties. Results show that flame spread rate increases exponentially with pressure, and the exponent of pressure further shows an increasing trend with the thickness of the sample. The angle of the pyrolysis front emerged on sample residue in the width direction, which indicates a steady-burning stage, varies clearly with sample thicknesses and ambient pressures. A global non-dimensional equation was proposed to predict the variation tendency of the angle of the pyrolysis front with pressure and was found to fit well with the measured results. In addition, the dependence of average flame height on mass burning rate, sample dimension and pressure was proposed based on laminar diffusion flame theory. The fitted exponent of experimental data is 1.11, which is close to the theoretical value. PMID:28774066

  10. Hydrophilic surface modification of poly(methyl methacrylate)-based ocular prostheses using poly(ethylene glycol) grafting.

    PubMed

    Ko, JaeSang; Cho, Kanghee; Han, Sang Won; Sung, Hyung Kyung; Baek, Seung Woon; Koh, Won-Gun; Yoon, Jin Sook

    2017-07-08

    Ocular prostheses are custom-made polymeric inserts that can be placed in anophthalmic sockets for cosmetic rehabilitation. Prosthetic eye wearers have reduced tear amount, and they often experience dry eye symptoms including dryness, irritation, discomfort, and discharge. Most modern ocular prostheses are made of poly(methyl methacrylate) (PMMA), which is highly hydrophobic. Previous research has shown that improving the wettability of contact lens materials decreases its wearers discomfort by increasing lubrication. Therefore, hydrophilic modification of PMMA-based ocular prostheses might also improve patient discomfort by improving lubrication. We modified the surfaces of PMMA-based ocular prostheses using poly(ethylene glycol) (PEG), which is hydrophilic. To do this, we used two strategies. One was a "grafting from" method, whereby PEG was polymerized from the PMMA surface. The other was a "grafting to" method, which involved PEG being covalently bonded to an amine-functionalized PMMA surface. Assessments involving the water contact angle, ellipsometry, and X-ray photoelectron spectroscopy indicated that PEG was successfully introduced to the PMMA surfaces using both strategies. Scanning electron microscopy and atomic force microscopy images revealed that neither strategy caused clinically significant alterations in the PMMA surface morphology. In vitro bacterial adhesion assessments showed that the hydrophilic modifications effectively reduced bacterial adhesion without inducing cytotoxicity. These results imply that hydrophilic surface modifications of conventional ocular prostheses may decrease patient discomfort and ocular prosthesis-related infections. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Adsorption Analysis of Lactoferrin to Titanium, Stainless Steel, Zirconia, and Polymethyl Methacrylate Using the Quartz Crystal Microbalance Method.

    PubMed

    Yoshida, Eiji; Hayakawa, Tohru

    2016-01-01

    It is postulated that biofilm formation in the oral cavity causes some oral diseases. Lactoferrin is an antibacterial protein in saliva and an important defense factor against biofilm development. We analyzed the adsorbed amount of lactoferrin and the dissociation constant (K(d)) of lactoferrin to the surface of different dental materials using an equilibrium analysis technique in a 27 MHz quartz crystal microbalance (QCM) measurement. Four different materials, titanium (Ti), stainless steel (SUS), zirconia (ZrO2) and polymethyl methacrylate (PMMA), were evaluated. These materials were coated onto QCM sensors and the surfaces characterized by atomic force microscopic observation, measurements of surface roughness, contact angles of water, and zeta potential. QCM measurements revealed that Ti and SUS showed a greater amount of lactoferrin adsorption than ZrO2 and PMMA. Surface roughness and zeta potential influenced the lactoferrin adsorption. On the contrary, the K(d) value analysis indicated that the adsorbed lactoferrin bound less tightly to the Ti and SUS surfaces than to the ZrO2 and PMMA surfaces. The hydrophobic interaction between lactoferrin and ZrO2 and PMMA is presumed to participate in better binding of lactoferrin to ZrO2 and PMMA surfaces. It was revealed that lactoferrin adsorption behavior was influenced by the characteristics of the material surface.

  12. Influences of the calcination temperature and polymethyl methacrylate templates to characteristic pore membrane of bioceramic titanium dioxide

    NASA Astrophysics Data System (ADS)

    Ady, Jan; Viandari, Eka; Hasanah, Dewi W.

    2017-05-01

    The synthesis of the bioceramics titanium dioxide on its template by polymethyl methacrylate to be a sample with forming TiO2/PMMA was made with sol-gel process, and its pore membrane characteristics has also been studied. Different calcination temperatures 500°C, 550°C, and 600°C were given to sample for 17 hours. This purpose themselves was to fill TiO2 fissures with PMMA on different concentrations of 0.0, 2.0 wt%, 3.0 wt%, 4.0 wt%. Template leaching technique was used to remove PMMA from samples, and it was then sequentially found of the pore size of the membrane in approximate ranges (1900 nm - 2000 nm), (860.5 nm - 1669 nm), (312.8 nm-382.5 nm), and (136.1 nm - 269.7 nm). SEM test using and fourth it has average thickness in about 6.7 nm with Ellipsometer measurement. The percentage values of titanium and oxygen atoms are found by SEM-EDX from 3.03 at.% up to 66.81 at.% and there is amount 99.99% of the sample in anatase phase forming at 550 0C with angle of diffraction is 25.410 and it was prepared by XRD measurement.

  13. Simplified ab externo fixation technique to treat late dislocation of scleral-sutured polymethyl methacrylate intraocular lenses

    PubMed Central

    Lyu, J; Zhao, P-q

    2016-01-01

    Purpose We report a simplified ab externo scleral fixation technique to manage the late dislocation of scleral-sutured polymethyl methacrylate (PMMA) intraocular lenses (IOLs) in the absence of capsule support. Materials and methods The technique was performed on five eyes of five patients. Symmetrical scleral pocket tunnels without conjunctival peritomy were created. An anterior vitrectomy via a limbal approach with an anterior chamber infusion or a 3-port pars plana vitrectomy was performed to rescue the dislocated IOL. A long straight suture needle and 23-gauge vitreoretinal forceps were used to conveniently reposition the IOL and loop sutures through the IOL positioning eyelets without externalizing IOL haptics. The outside suture knots were buried under the roof of the scleral tunnels. Results The patients were followed for 5–14 months after surgery. All the operated eyes quickly recovered with negligible corneal endothelial cell loss and mild inflammation. Visual acuity improvement and IOL centration were achieved in all eyes with no major complications. Conclusion The simplified ab externo scleral fixation technique offers an effective and minimally invasive surgical alternative to salvage dislocated previously scleral-sutured PMMA IOLs. PMID:26795420

  14. Triple-junction InGaP/GaAs/Ge solar cells integrated with polymethyl methacrylate subwavelength structure

    NASA Astrophysics Data System (ADS)

    Kim, Dae-Seon; Jeong, Yonkil; Jeong, Hojung; Jang, Jae-Hyung

    2014-11-01

    GaAs-based triple-junction tandem solar cells incorporating an antireflection coating (ARC) consisting of a subwavelength structure (SWS) and bilayer thin films are reported. A high aspect ratio SWS was realized on polymethyl methacrylate (PMMA) using a two-step etched silicon template and a stamping method. The fabricated PMMA SWS consisting of a two-dimensional array of nanoscale needles with a period of 300 nm and an aspect ratio exceeding 2.3 exhibited significantly improved optical performance. The average reflectance of the PMMA SWS was reduced from 7.1 to 4.4% as compared to that of the bare PMMA film, which resulted in an improvement of the transmittance from 90.7 to 92.9% in the wavelength range between 300 and 1700 nm. By integrating the PMMA SWS together with a TiO2/Al2O3 bilayer AR coating onto the top of an InGaP/GaAs/Ge triple-junction solar cell, the surface reflection of the solar cell could be minimized. The integrated PMMA SWS on the bilayer thin film ARC enhanced the power-conversion efficiency (η) of the triple-junction solar cell from 30.2 to 31.6% and from 37.8 to 40.8% under 1 and 157 sun condition, respectively.

  15. Celebrating Soft Matter's 10th Anniversary: Influencing the charge of poly(methyl methacrylate) latexes in nonpolar solvents.

    PubMed

    Smith, Gregory N; Hallett, James E; Eastoe, Julian

    2015-11-07

    Sterically-stabilized poly(methyl methacrylate) (PMMA) latexes dispersed in nonpolar solvents are a classic, well-studied system in colloid science. This is because they can easily be synthesized with a narrow size distribution and because they interact essentially as hard spheres. These PMMA latexes can be charged using several methods (by adding surfactants, incorporating ionizable groups, or dispersing in autoionizable solvents), and due to the low relative permittivity of the solvents (εr ≈ 2 for alkanes to εr ≈ 8 for halogenated solvents), the charges have long-range interactions. The number of studies of these PMMA particles as charged species has increased over the past ten years, after few studies immediately following their discovery. A large number of variations in both the physical and chemical properties of the system (size, concentration, surfactant type, or solvent, as a few examples) have been studied by many groups. By considering the literature on these particles as a whole, it is possible to determine the variables that have an effect on the charge of particles. An understanding of the process of charge formation will add to understanding how to control charge in nonaqueous solvents as well as make it possible to develop improved technologically relevant applications for charged polymer nanoparticles.

  16. A novel process for separation of polycarbonate, polyvinyl chloride and polymethyl methacrylate waste plastics by froth flotation.

    PubMed

    Wang, Chong-Qing; Wang, Hui; Huang, Luo-Luo

    2017-04-08

    A novel process was proposed for separation of ternary waste plastics by froth flotation. Pretreatment of plastics with potassium permanganate (KMnO4) solution was conducted to aid flotation separation of polycarbonate (PC), polyvinyl chloride (PVC) and polymethyl methacrylate (PMMA) plastics. The effect of pretreatment parameters including KMnO4 concentration, treatment time, temperature and stirring rate on flotation recovery were investigated by single factor experiments. Surface treatment with KMnO4 changes selectively the flotation behavior of PC, PVC and PMMA, enabling separation of the plastics by froth flotation. Mechanism of surface treatment was studied by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray photoelectron spectrum (XPS). Effect of frother concentration and flotation time on flotation behavior of plastic mixtures was further studied for flotation separation. The optimized conditions for separation of PC are KMnO4 concentration 2mmolL(-1), treatment time 10min, temperature 60°C, stirring rate 300rpm, flotation time 1min and frother concentration 17.5mgL(-1). Under optimum conditions, PVC and PMMA mixtures are also separated efficiently by froth flotation associated with KMnO4 treatment. The purity of PC, PVC and PMMA is up to 100%, 98.41% and 98.68%, while the recovery reaches 96.82%, 98.71% and 98.38%, respectively. Economic analysis manifests remarkable profits of the developed process. Reusing KMnO4 solution is feasible, enabling the process greener.

  17. Fabrication of poly(methyl methacrylate)-MoS{sub 2}/graphene heterostructure for memory device application

    SciTech Connect

    Shinde, Sachin M.; Tanemura, Masaki; Kalita, Golap

    2014-12-07

    Combination of two dimensional graphene and semi-conducting molybdenum disulfide (MoS{sub 2}) is of great interest for various electronic device applications. Here, we demonstrate fabrication of a hybridized structure with the chemical vapor deposited graphene and MoS{sub 2} crystals to configure a memory device. Elongated hexagonal and rhombus shaped MoS{sub 2} crystals are synthesized by sulfurization of thermally evaporated molybdenum oxide (MoO{sub 3}) thin film. Scanning transmission electron microscope studies reveal atomic level structure of the synthesized high quality MoS{sub 2} crystals. In the prospect of a memory device fabrication, poly(methyl methacrylate) (PMMA) is used as an insulating dielectric material as well as a supporting layer to transfer the MoS{sub 2} crystals. In the fabricated device, PMMA-MoS{sub 2} and graphene layers act as the functional and electrode materials, respectively. Distinctive bistable electrical switching and nonvolatile rewritable memory effect is observed in the fabricated PMMA-MoS{sub 2}/graphene heterostructure. The developed material system and demonstrated memory device fabrication can be significant for next generation data storage applications.

  18. Adsorption Analysis of Lactoferrin to Titanium, Stainless Steel, Zirconia, and Polymethyl Methacrylate Using the Quartz Crystal Microbalance Method

    PubMed Central

    Yoshida, Eiji; Hayakawa, Tohru

    2016-01-01

    It is postulated that biofilm formation in the oral cavity causes some oral diseases. Lactoferrin is an antibacterial protein in saliva and an important defense factor against biofilm development. We analyzed the adsorbed amount of lactoferrin and the dissociation constant (Kd) of lactoferrin to the surface of different dental materials using an equilibrium analysis technique in a 27 MHz quartz crystal microbalance (QCM) measurement. Four different materials, titanium (Ti), stainless steel (SUS), zirconia (ZrO2) and polymethyl methacrylate (PMMA), were evaluated. These materials were coated onto QCM sensors and the surfaces characterized by atomic force microscopic observation, measurements of surface roughness, contact angles of water, and zeta potential. QCM measurements revealed that Ti and SUS showed a greater amount of lactoferrin adsorption than ZrO2 and PMMA. Surface roughness and zeta potential influenced the lactoferrin adsorption. On the contrary, the Kd value analysis indicated that the adsorbed lactoferrin bound less tightly to the Ti and SUS surfaces than to the ZrO2 and PMMA surfaces. The hydrophobic interaction between lactoferrin and ZrO2 and PMMA is presumed to participate in better binding of lactoferrin to ZrO2 and PMMA surfaces. It was revealed that lactoferrin adsorption behavior was influenced by the characteristics of the material surface. PMID:26998486

  19. Charging of poly(methyl methacrylate) (PMMA) colloids in cyclohexyl bromide: locking, size dependence, and particle mixtures.

    PubMed

    van der Linden, Marjolein N; Stiefelhagen, Johan C P; Heessels-Gürboğa, Gülşen; van der Hoeven, Jessi E S; Elbers, Nina A; Dijkstra, Marjolein; van Blaaderen, Alfons

    2015-01-13

    We studied suspensions of sterically stabilized poly(methyl methacrylate) (PMMA) particles in the solvent cyclohexyl bromide (CHB; εr = 7.92). We performed microelectrophoresis measurements on suspensions containing a single particle species and on binary mixtures, using confocal microscopy to measure the velocity profiles of the particles. We measured the charge of so-called locked PMMA particles, for which the steric stabilizer, a comb-graft stabilizer of poly(12-hydroxystearic acid) (PHSA) grafted on a backbone of PMMA, was covalently bonded to the particle, and for unlocked particles, for which the stabilizer was adsorbed to the surface of the particle. We observed that locked particles had a significantly higher charge than unlocked particles. We found that the charge increase upon locking was due to chemical coupling of 2-(dimethylamino)ethanol to the PMMA particles, which was used as a catalyst for the locking reaction. For particles of different size we obtained the surface potential and charge from the electrophoretic mobility of the particles. For locked particles we found that the relatively high surface potential (∼ +5.1 kBT/e or +130 mV) was roughly constant for all particle diameters we investigated (1.2 μm < σ < 4.4 μm), and that the particle charge was proportional to the square of the diameter.

  20. Human Fetal Osteoblast Response on Poly(Methyl Methacrylate)/Polystyrene Demixed Thin Film Blends: Surface Chemistry Vs Topography Effects.

    PubMed

    D'Sa, Raechelle A; Raj, Jog; Dickinson, Peter J; McCabe, Fiona; Meenan, Brian J

    2016-06-22

    Recent advances in materials sciences have allowed for the development and fabrication of biomaterials that are capable of providing requisite cues to instigate cells to respond in a predictable fashion. We have developed a series of poly(methyl methacrylate)/polystyrene (PMMA/PS) polymer demixed thin films with nanotopographies ranging from nanoislands to nanopits to study the response of human fetal osteoblast cells (hFOBs). When PMMA was in excess in the blend composition, a nanoisland topography dominated, whereas a nanopit topography dominated when PS was in excess. PMMA was found to segregate to the top of the nanoisland morphology with PS preferring the substrate interface. To further ascertain the effects of surface chemistry vs topography, we plasma treated the polymer demixed films using an atmospheric pressure dielectric barrier discharge reactor to alter the surface chemistry. Our results have shown that hFOBs did not have an increased short-term cellular response on pristine polymer demixed surfaces. However, increasing the hydrophilicty/wettability of the surfaces by oxygen functionalization causes an increase in the cellular response. These results indicate that topography alone is not sufficient to induce a positive cellular response, but the underlying surface chemistry is also important in regulating cell function.

  1. Synthesis and characterization of poly(methyl methacrylate-butyl acrylate)/nano-titanium oxide composite particles.

    PubMed

    Guo, Gang; Yu, Jie; Luo, Zhu; Zhou, LiangXue; Liang, Hang; Luo, Feng; Qian, ZhiYong

    2011-06-01

    Poly(methyl methacrylate-butyl acrylate) [P(MMA-BA)]/nanosized titanium oxide (nano-TiO2) composite particles were prepared via insitu emulsion polymerization of MMA and BA in presence of nano-TiO2 particles. Before polymerization, the nano-TiO2 particles were modified by coupling agent. The structure and thermal properties of the obtained P(MMA-BA)/nano-TiO2 composite particles were characterized by Fourier transform infrared spectra (FTIR), wide-angle X-ray diffraction (WAXD) and thermogravimetric analysis (TGA). The results showed that there are covalent bond bindings between P(MMA-BA) and nano-TiO2 particles, meaning that P(MMA-BA) and nano-TiO2 particles were not simply blended or mixed up and that there is a strong interaction between P(MMA-BA) and nano-TiO2 particles. TGA and DSC measurements indicated an enhancement of thermal stability. Transmission electron microscopy (TEM) results showed that P(MMA-BA) enhanced the dispersibility of nano-TiO2 particles. The dispersion stabilization of modified nano-TiO2 particles in aqueous system was significantly improved due to the introduction of grafted polymer on the surface of nano-particles.

  2. Morphology control through hierarchical phase separation in Langmuir monolayers of poly(methyl methacrylate)-b-poly(n-butyl acrylate).

    PubMed

    Watanabe, Atsushi; Kumaki, Jiro

    2017-01-15

    Precise morphology control of ultrathin films is one of the important issues in nanotechnology. To this end, we describe that various controlled morphologies of hierarchical phase separation can be attained using poly(methyl methacrylate)-b-poly(n-butyl acrylate) (PMMA-b-PBA) monolayers spread on a water surface. At a low surface pressure, they were miscible, but upon compression, phase separated with a monolayer of the major component block spreading on the water surface, on top of which the minor component block separated out (hierarchical phase separation). The morphology of the minor component block separated out on top of the monolayer varied from a sphere/short string mixture, to long strings, and a mesh-like structure having a regular domain-domain spacing with the increasing content of the minor block, and the hierarchical phase separation was reversible depending on the surface pressure. However, these well-ordered hierarchical phase separations were observed only in the PBA-rich polymers, and a clear morphology was not observed in the PMMA-rich polymers, because of insufficient domain growth after the hierarchical phase separation for the PMMA-rich block copolymers which are more rigid than the PBA-rich polymers. Although the clear hierarchical phase separation was limited in flexible composition, we noted that the hierarchical phase separation provided a unique well-controlled morphology in the Langmuir monolayers. Copyright © 2016 Elsevier Inc. All rights reserved.

  3. Construction of wettability gradient surface on copper substrate by controlled hydrolysis of poly(methyl methacrylate-butyl acrylate) films

    NASA Astrophysics Data System (ADS)

    Zhang, Yong; Cheng, Jiang; Yang, Zhuo-ru

    2014-10-01

    We report a gradient wettability surface on copper slide prepared by a simple controlled ester group hydrolysis procedure of poly(methyl methacrylate-butyl acrylate) [P (MMA-BA)] films coated on the copper substrate. In the method, sodium hydroxide solutions are selected to prepare surface gradient wettability on P (MMA-BA) films. The P (MMA-BA) copolymers with different MMA contents are first synthesized by a conventional free atom radical solution polymerization method. The transfer of surface chemical composition from the ester group to acid salt is achieved by hydrolysis in NaOH solution. The effects of different concentrations of NaOH solution and reaction times on the physicochemical properties of the resulting surfaces are studied. The field-emission scanning electron microscopy (FESEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) results show that the varying concentration along the substrate length is only attributed to the hydrolysis reaction of ester groups. The hydrolysis causes insignificant change on the morphology of the original film on the copper substrate. In addition, it is found that the MMA copolymer content has a significant influence on the concentration of ester groups on the outermost surface and thus important for forming the slope gradients.

  4. Antifouling properties of poly(methyl methacrylate) films grafted with poly(ethylene glycol) monoacrylate immersed in seawater.

    PubMed

    Iguerb, O; Poleunis, C; Mazéas, F; Compère, C; Bertrand, P

    2008-11-04

    Biofouling of all structures immersed in seawater constitutes an important problem, and many strategies are currently being developed to tackle it. In this context, our previous work shows that poly(ethylene glycol) monoacrylate (PEGA) macromonomer grafted on preoxidized poly(methyl methacrylate) (PMMAox) films exhibits an excellent repellency against the bovine serum albumin used as a model protein. This study aims to evaluate the following: (1) the prevention of a marine extract material adsorption by the modified surfaces and (2) the antifouling property of the PEGA-g-PMMAox substrates when immersed in natural seawater during two seasons (season 1: end of April-beginning of May 2007, and season 2: end of October-beginning of November 2007). The antifouling performances of the PEGA-g-PMMAox films are investigated for different PEG chain lengths and macromonomer concentrations into the PEGA-based coatings. These two parameters are followed as a function of the immersion time, which evolves up to 14 days. The influence of the PEGA layer on marine compounds (proteins and phospholipids) adsorption is evidenced by time-of-flight secondary ion mass spectrometry (ToF-SIMS) and X-ray photoelectron spectroscopy (XPS). It was found that the antifouling efficiency of the PEGA-grafted surfaces increases with both PEGA concentration and PEG chain length.

  5. Effects of nystatin, fluconazole and propolis on poly(methyl methacrylate) resin surface.

    PubMed

    da Silva, Wander José; Rached, Rodrigo Nunes; Rosalen, Pedro Luis; Del bel Cury, Altair Antoninha

    2008-01-01

    The prevalence of candidosis in denture wearers is as well established as its treatment with antifungal agents (AAs). However, little research has been done regarding the effects of AAs on denture base surfaces. Therefore, the aim of this study was to evaluate the effects of fluconazole (FLU), nystatin (NYS) and propolis orabase gel (PRO) on poly (methyl-methacrylate) (PMMA) surfaces. Deionized water and orabase gel without any active component were used as control groups. Conventional heat-polymerized (Clássico) and microwave-polymerized (Onda Cryl) acrylic resins were used. After polymerization, the specimens were polished and had their surfaces evaluated for roughness, free energy and Knoop hardness. Subsequently, specimens were immersed in AAs and controls for 14 days at 35+/-2 degrees C and all variables were measured again. Data were analyzed statistically by 2-way ANOVA followed by Tukey's test (alpha=0.05). Roughness results showed similar behavior for both PMMA resins, with PRO reaching the highest values and differing significantly from the other AAs (p<0.05). No statistically significant differences (p>0.05) were found between the two PMMA resins or between NYS and FLU as regards surface free energy. In conclusion, PRO was able to induce changes in PMMA surface properties, such as roughness, which could be related to microbial adhesion.

  6. Hydrophobic modification of polymethyl methacrylate as intraocular lenses material to improve the cytocompatibility.

    PubMed

    Wang, Bailiang; Lin, Quankui; Shen, Chenghui; Tang, Junmei; Han, Yuemei; Chen, Hao

    2014-10-01

    The development of posterior capsule opacification (PCO) after intraocular lenses (IOL) implantation for dealing with cataract is mainly due to the severe loss of the human lens epithelial cells (HLECs) during surgery contact. A novel poly (hedral oligomeric silsesquioxane-co-methyl methacrylate) copolymer (allyl POSS-PMMA) was synthesized by free radical polymerization method to promote the adhesion of HLECs. FT-IR and (1)H NMR measurements indicated the existence of POSS cage in the product, which demonstrated the successful synthesis of allyl POSS-PMMA copolymer. Effect of allyl POSS in the hybrids on crystal structure, surface wettability and morphology, optical transmission, thermodynamic properties and cytocompatibility was investigated in detail. X-ray diffraction peaks at 2θ∼11° and 12° indicated that POSS molecules had aggregated and crystallized. Thermogravimetric analysis-differential scanning calorimeter and optical transmission measurements confirmed that the allyl POSS-PMMA copolymer had high glass transition temperatures (more than 100°C) and good transparency. The hydrophilicity and morphology of PMMA and copolymers surfaces were characterized by static water contact angle and atomic force microscopy. The results revealed that the surface of the allyl POSS-PMMA copolymer displayed higher hydrophobicity and higher roughness than that of pure PMMA. The surface biocompatibility was evaluated by morphology and activity measurement with HLECs in vitro. The results verified that the surface of allyl POSS-PMMA copolymer films had more HLECs adhesion and better spreading morphology than that of PMMA film.

  7. Development characteristics of polymethyl methacrylate in alcohol/water mixtures. A lithography and Raman spectroscopy study

    SciTech Connect

    Ocola, Leonidas E.; Costales, Maya; Gosztola, David J.

    2015-12-10

    Poly methyl methacrylate (PMMA) is the most widely used resist in electron beam lithography. This paper reports on a lithography and Raman spectroscopy study of development characteristics of PMMA in methanol, ethanol and isopropanol mixtures with water as developers. We have found that ethanol/water mixtures at a 4:1 volume ratio are an excellent, high resolution, non-toxic, developer for exposed PMMA. We also have found that the proper methodology to use so that contrast data can be compared to techniques used in polymer science is not to rinse the developed resist but to immediately dry with nitrogen. Our results show how powerful simple lithographic techniques can be used to study ternary polymer solvent solutions when compared to other techniques used in the literature. Raman data shows that there both tightly bonded –OH groups and non-hydrogen bonded –OH groups play a role in the development of PMMA. Tightly hydrogen bonded –OH groups show pure Lorentzian Raman absorption only in the concentration ranges where ethanol/water and IPA/water mixtures are effective developers of PMMA. The impact of the understanding these interactions may open doors to a new developers of other electron beam resists that can reduce the toxicity of the waste stream.

  8. Development Characteristics of Polymethyl Methacrylate in Alcohol/Water Mixtures: a Lithography and Raman spectroscopy study

    SciTech Connect

    Ocola, Leonidas E.; Costales, Maya S.; Gosztola, David J.

    2016-01-22

    Poly methyl methacrylate (PMMA) is the most widely used resist in electron beam lithography. This paper reports on a lithography and Raman spectroscopy study of development characteristics of PMMA in methanol, ethanol and isopropanol mixtures with water as developers. We have found that ethanol/water mixtures at a 4:1 volume ratio are an excellent, high resolution, non-toxic, developer for exposed PMMA. We also have found that the proper methodology to use so that contrast data can be compared to techniques used in polymer science is not to rinse the developed resist but to immediately dry with nitrogen. Our results show how powerful simple lithographic techniques can be used to study ternary polymer solvent solutions when compared to other techniques used in the literature. Raman data shows that there both tightly bonded –OH groups and non-hydrogen bonded –OH groups play a role in the development of PMMA. Tightly hydrogen bonded –OH groups show pure Lorentzian Raman absorption only in the concentration ranges where ethanol/water and IPA/water mixtures are effective developers of PMMA. The impact of the understanding these interactions may open doors to a new developers of other electron beam resists that can reduce the toxicity of the waste stream.

  9. Development characteristics of polymethyl methacrylate in alcohol/water mixtures: a lithography and Raman spectroscopy study

    NASA Astrophysics Data System (ADS)

    Ocola, Leonidas E.; Costales, Maya; Gosztola, David J.

    2016-01-01

    Poly methyl methacrylate (PMMA) is the most widely used resist in electron beam lithography. This paper reports on a lithography and Raman spectroscopy study of development characteristics of PMMA in methanol, ethanol and isopropanol mixtures with water as developers. We have found that ethanol/water mixtures at a 4:1 volume ratio are an excellent, high resolution, non-toxic developer for exposed PMMA. We have also found that the proper methodology to use so that contrast data can be compared to techniques used in polymer science is not to rinse the developed resist but to immediately dry with nitrogen. Our results show how powerful simple lithographic techniques can be used to study ternary polymer solvent solutions when compared to other techniques used in the literature. Raman data show that both tightly bonded -OH groups and non-hydrogen bonded -OH groups play a role in the development of PMMA. Tightly hydrogen bonded -OH groups show pure Lorentzian Raman absorption only in the concentration ranges where ethanol/water and IPA/water mixtures are effective developers of PMMA, pointing to possible ordering or reduced amorphization due to the liquid state. The impact of understanding these interactions may open doors to a new developers of other electron beam resists that can reduce the toxicity of the waste stream.

  10. Synthesis of ultrathin poly(methyl methacrylate) model coatings bound via organosilanes to zinc and investigation of their delamination kinetics.

    PubMed

    Iqbal, Danish; Rechmann, Julian; Sarfraz, Adnan; Altin, Abdulrahman; Genchev, Georgi; Erbe, Andreas

    2014-10-22

    Polymer coatings are widely used to protect metals from corrosion. Coating adhesion to the base material is critical for good protection, but coatings may fail because of cathodic delamination. Most of the experimental studies on cathodic delamination use polymers to study the corrosion behavior under conditions where the interfacial chemistry at the metal(oxide)/polymer interface is not well-defined. Here, ultrathin linear and cross-linked poly(methyl methacrylate) [PMMA] coatings that are covalently bound to oxide-covered zinc via a silane linker have been prepared. For preparation, zinc was functionalized with vinyltrimethoxysilane (VTS), yielding a vinyl monomer-covered surface. These samples were subjected to thermally initiated free radical polymerization in the presence of methyl methacrylate (MMA) to yield surface-bound ultrathin PMMA films of 10-20 nm thickness, bound to the surface via Zn-O-Si bonds. A similar preparation was also carried out in the presence of different amounts of the cross-linkers ethylene glycol diacrylate and hexanediol diacrylate. Functionalized and polymer-coated zinc samples were characterized by infrared (IR) spectroscopy, secondary ion mass spectrometry (SIMS), ellipsometry, and X-ray photoelectron spectroscopy (XPS). Coating stability toward cathodic delamination has been evaluated by scanning Kelvin probe (SKP) experiments. In all cases, the covalently linked coatings show lower delamination rates of 0.02-0.2 mm h(-1) than coatings attached to the surface without covalent bonds (rates ∼10 mm h(-1)). Samples with a higher fraction of cross-linker delaminate slower, with rates down to 0.03-0.04 mm h(-1), compared to ∼0.3 mm h(-1) without cross-linker. Samples with longer hydrophobic alkyl chains also delaminate slower, with the lowest observed delamination rate of 0.028 mm h(-1) using hexanediol diacrylate. For the coatings studied here, delamination kinetics is not diffusion limited, but the rate is controlled by a chemical

  11. Preparation and characterization of poly(methyl methacrylate) - iron (III) oxide microparticles using a modified solvent evaporation method.

    PubMed

    Morello, A Peter; Burrill, Roxanne; Mathiowitz, Edith

    2007-08-01

    At present, there is widespread interest in developing new, biocompatible microparticles made from polymers such as poly(methyl methacrylate) (PMMA) that could have applications ranging from diagnostic imaging to drug delivery. In these experiments, there were two primary objectives: (1) to stabilize a suspension of iron (III) oxide (alpha-Fe(2)O(3); mean diameter = 100 nm) nanoparticles in a solution of PMMA by using an emulsifier and different mixtures of two miscible solvents; and (2) to fabricate PMMA-alpha-Fe(2)O(3) microparticles by using an oil-in-water (o/w) solvent evaporation method. By accomplishing the first objective, it was hypothesized that the encapsulation efficiency of alpha-Fe(2)O(3) within PMMA microparticles would improve and induce the clustering of alpha-Fe(2)O(3) along the circumferential edges of the microparticles. Of the seven emulsifiers tested, Tween 80 was selected primarily for its hydrophilicity and its ability to produce a stable alpha-Fe(2)O(3) dispersion. As a result, 22 batches of microspheres (11 with Tween 80 and 11 without) were made and the solvent (dichloromethane) to co-solvent (ethyl acetate) ratios were varied. Particles made with solvent mixtures of >50% ethyl acetate (<50% dichloromethane) were more likely to be hollow and had larger mean volumetric particle diameters (>5 microns) than particles made with mixtures containing >50% dichloromethane. Particles made with Tween 80 were larger, more porous, and had alpha-Fe(2)O(3) aligned along the circumferential edges of the particles. The use of solvent mixtures did not improve the encapsulation efficiency of alpha-Fe(2)O(3) but the use of ethyl acetate helped to induce the clustering of alpha-Fe(2)O(3) along the peripheries of the microparticles.

  12. Surface structures of poly(methyl methacrylate) films influenced by chain entanglement in the corresponding film-formation solution.

    PubMed

    Xu, Jianquan; Liu, Yingjun; He, Jinsheng; Zhang, Rongping; Zuo, Biao; Wang, Xinping

    2014-11-28

    The effects of the properties of casting solution on the surface structure of poly(methyl methacrylate) (PMMA) films were systematically investigated. It was observed that the hydrophobicity of PMMA films increased with increasing viscosity of the corresponding polymer solution regardless of the film-formation techniques that were utilized. The ratio of the C-H symmetric stretching vibrations of methylene groups (hydrophobic components, with a peak at 2910 cm(-1)) to those of the ester methyl groups (relative hydrophilic components, with a peak at 2955 cm(-1)) from sum frequency generation (SFG) vibrational spectra, A2910/A2955, was used as a parameter to evaluate the structure on the film surface, which was related to the surface wettability of the films. The results showed that A2910/A2955 of cast PMMA films increased linearly with ηsp(0.3) (ηsp, the specific viscosity of the casting solution), whereas that of the corresponding spin-coated films showed a linear relationship defined as ηsp(0.3)E(0.26), where E is the average number of entanglement points per molecule (E = Mw/Me). These results indicate that a relative equilibrium conformation on the PMMA film surface, adopted from the perspective of thermodynamics, was easily achieved during film formation, when the conformation of the polymer chains in the corresponding casting solution was close to that in the bulk. For the spin-coated films, the chain entanglement structure in the casting solution was a more important factor for the resulting film to reach a relative equilibrium state, since this structure was in favor of maintaining the pristine conformation in casting solution under centrifugal force during spin-coating. This work may help to enhance the fundamental understanding of the formation of the film surface structure from polymer solution to the resulting solid film, which will affect not only the corresponding surface properties, but also the dynamics of the resulting thin films.

  13. Molecular structure of poly(methyl methacrylate) surface II: Effect of stereoregularity examined through all-atom molecular dynamics.

    PubMed

    Jha, Kshitij C; Zhu, He; Dhinojwala, Ali; Tsige, Mesfin

    2014-11-04

    Utilizing all-atom molecular dynamics (MD), we have analyzed the effect of tacticity and temperature on the surface structure of poly(methyl methacrylate) (PMMA) at the polymer-vacuum interface. We quantify these effects primarily through orientation, measured as the tilt with respect to the surface normal, and the surface number densities of the α-methyl, ester-methyl, carbonyl, and backbone methylene groups. Molecular structure on the surface is a complex interplay between orientation and number densities and is challenging to capture through sum frequency generation (SFG) spectroscopy alone. Independent quantification of the number density and orientation of chemical groups through all-atom MD presents a comprehensive model of stereoregular PMMA on the surface. SFG analysis presented in part I of this joint publication measures the orientation of molecules that are in agreement with MD results. We observe the ester-methyl groups as preferentially oriented, irrespective of tacticity, followed by the α-methyl and carbonyl groups. SFG spectroscopy also points to ester-methyl being dominant on the surface. The backbone methylene groups show a very broad angular distribution, centered along the surface plane. The surface number density ratios of ester-methyl to α-methyl groups show syndiotactic PMMA having the lowest value. Isotactic PMMA has the highest ratios of ester- to α-methyl. These subtle trends in the relative angular orientation and number densities that influence the variation of surface structure with tacticity are highlighted in this article. A more planar conformation of the syndiotactic PMMA along the surface (x-y plane) can be visualized through the trajectories from all-atom MD. Results from conformation tensor calculations for chains with any of their segments contributing to the surface validate the visual observation.

  14. Bond strength of poly(methyl methacrylate) denture base material to cast titanium and cobalt-chromium alloy.

    PubMed

    Matsuda, Yasuhiro; Yanagida, Hiroaki; Ide, Takako; Matsumura, Hideo; Tanoue, Naomi

    2010-06-01

    The shear bond strength of an auto-polymerizing poly(methyl methacrylate) denture base resin material to cast titanium and cobalt-chromium alloy treated with six conditioning methods was investigated. Disk specimens (10 mm in diameter and 2.5 mm in thickness) were cast from pure titanium and cobalt-chromium alloy. The specimens were wet ground to a final surface finish of 600 grit, air dried, and treated with the following bonding systems: 1) air abraded with 50-70-microm-grain alumina (SAN); 2) air abraded with 50-70-microm-grain alumina + conditioned with Alloy Primer (ALP); 3) air abraded with 50-70-microm-grain alumina + conditioned with AZ Primer (AZP); 4) air abraded with 50-70-microm-grain alumina + conditioned with Estenia Opaque Primer (EOP); 5) air abraded with 50-70-microm-grain alumina + conditioned with Metal Link Primer (MLP), and 6) treated with ROCATEC system (ROC). A denture base material (Palapress Vario) was then applied to each metal specimen. Shear bond strengths were determined before and after 10,000 thermocycles. The strengths decreased after thermocycling in all combinations. Among the treatment methods assessed, groups 2 and 4 showed significantly (p < 0.05) enhanced shear bond strengths for both metals. In group 4, the strength in MPa (n = 7) after thermocycling for cobalt-chromium alloy was 38.3, which was statistically (p < 0.05) higher than that for cast titanium (34.7). Air abrasion followed by the application of two primers containing a hydrophobic phosphate monomer (MDP) effectively improved the strength of the bond of denture base material to cast titanium and cobalt-chromium alloy.

  15. Poly(methyl methacrylate) particles for local drug delivery using shock wave lithotripsy: In vitro proof of concept experiment.

    PubMed

    Shaked, Eliav; Shani, Yoav; Zilberman, Meital; Scheinowitz, Mickey

    2015-08-01

    To leverage current local drug delivery systems methodology, there is vast use of polymeric particles serving as drug carriers to assure minimal invasive therapy with little systemic distribution of the released drug. There is an increasing interest in poly(methyl methacrylate) (PMMA) serving as carriers in drug delivery. The study aims to develop PMMA carriers for localized drug delivery and release system, combining innovative biomaterial technology and shock wave lithotripsy (SWL), and to study the effect of SWL on various concentrations of PMMA particles. We prepared PMMA particles that contain horseradish peroxidase (HRP) using a double emulsion technique, and investigated the mechanism of in vitro drug release from the carriers following exposure to SWL. We investigated the correlation between production method modifications, concentrations of the carriers subjected to SWL, and shock wave patterns. We successfully produced PMMA particles as drug carriers and stimulated the release of their contents by SWL; their polymeric shell can be shattered externally by SWL treatment, leading to release of the encapsulated drug. HRP enzyme activity was maintained following the encapsulation process and exposure to high dose of SWL pulses. Increased shock wave number results in increased shattering and greater fragmentation of PMMA particles. The results demonstrate a dose-response release of HRP; quantitation of the encapsulated HRP from the carriers rises with the number of SWL. Moreover, increased concentration of particles subjected to the same dose of SWL results in a significant increase of the total HRP release. Our research offers novel technique and insights into new, site-specific drug delivery and release systems.

  16. Surgical Removal of Circumferentially Leaked Polymethyl Methacrylate in the Epidural Space of the Thoracic Spine after Percutaneous Vertebroplasty

    PubMed Central

    Kita, Kenichiro; Takata, Yoichiro; Higashino, Kosaku; Yamashita, Kazuta; Tezuka, Fumitake; Sakai, Toshinori; Nagamachi, Akihiro; Sairyo, Koichi

    2017-01-01

    Background  The major complication of percutaneous vertebroplasty (PVP) using polymethyl methacrylate (PMMA) is epidural leakage of PMMA that damages the spinal cord. Methods  This is a case report. Result  A 77-year-old man presented to our institution with a 6-month history of muscle weakness and an intolerable burning sensation of both lower limbs after PVP with PMMA for thoracic compression fracture at T7 at another hospital. His past medical history was significant for hypertension. He had no history of smoking and alcohol. Computed tomography revealed massive leakage of PMMA into the T6 and T7 spinal canal circumferentially surrounding the spinal cord that caused marked encroachment of the thecal sac. Magnetic resonance images revealed cord compression and intramedullary signal change from T6 to T7 level. After we verified that the leaked PMMA could be easily detached from the dura mater in the cadaveric lumbar spine, surgical decompression and removal of epidural PMMA was performed. The leaked PMMA was carefully thinned down with a high-speed diamond burr. Eight pieces of PMMA were detached from the dura mater easily without causing a dural tear. No neurologic deterioration was observed in the postoperative period. The burning sensation resolved, but the muscle weakness remained unchanged. One and a half years postoperatively, the muscle weakness has improved to ⅘ on the manual muscle strength test, but he could not walk without an aid because of spasticity. Conclusion  This report demonstrates the catastrophic epidural extrusion of PMMA following PVP. Extravasated PMMA can be removed through a working space created by means of laminectomy and subtraction of the affected pedicle. Spine surgeons should recognize the possible neurologic complications of PVP and be prepared to treat them using suitable approaches. PMID:28825011

  17. Synthesis of poly(methyl methacrylate) core/chitosan-mixed-polyethyleneimine shell nanoparticles and their antibacterial property.

    PubMed

    Inphonlek, Supharat; Pimpha, Nuttaporn; Sunintaboon, Panya

    2010-06-01

    The core-shell nanoparticles possessing poly(methyl methacrylate) (PMMA) core coated with chitosan (CS), polyethyleneimine (PEI), and chitosan-mixed-polyethyleneimine (CS/PEI) shells were synthesized in this work. The emulsifier-free emulsion polymerization triggered by a redox initiating system from t-butylhydroperoxide (TBHP) and amine groups on CS and/or PEI was used as a synthetic method. In the CS/PEI systems, the amount of CS was kept constant (0.5g), while the amount of PEI was varied from 0.1 to 0.5g. The surface and physico-chemical properties of prepared nanoparticles were then examined. FTIR spectra indicated the presence of grafted PMMA on CS and/or PEI, and the weight fraction of incorporated PEI in the CS/PEI nanoparticles. All nanoparticles were spherical in shape with uniform size distribution illustrated by scanning electron microscopy (SEM). The introduction of PEI to CS nanoparticles yielded the higher monomer conversion, grafting efficiency, and grafting percentage compared with the CS nanoparticles. The size of CS/PEI nanoparticles was smaller than the original CS and PEI nanoparticles, and tended to decrease with increasing amount of PEI introduced. The introduction of PEI also brought the higher colloidal stability to the nanoparticles as indicated by zeta-potential measurement and isoelectric point analysis. The nanoparticles exhibited a promising antibacterial activity against Staphylococcus aureus and Escherichia coli. The nanoparticle-bacteria interaction was studied via SEM. The results suggested that they would be useful as effective antibacterial agents.

  18. Nd:YAG laser capsulotomy rates following implantation of square-edged intraocular lenses: polymethyl methacrylate versus silicone versus acrylic.

    PubMed

    Ram, Jagat; Kumar, Sunil; Sukhija, Jaspreet; Severia, Saurabh

    2009-04-01

    To study the influence of square-edged intraocular lenses (IOLs) on the development of posterior capsule opacification (PCO) and the requirement for laser capsulotomy. Retrospective study. Three hundred seventy-seven eyes of 377 patients were included. All these patients underwent phacoemulsification and implantation of square polymethyl methacrylate (PMMA) (Aurolab), silicone (Tecnis Z9000), acrylic hydrophobic (AcrySof MA60AC and Sensar Optiedge), or acrylic hydrophilic (Akreos Adapt) IOLs with a minimum of 2 years' follow-up. Only those cases in which Nd:YAG laser capsulotomy had been performed for visually significant PCO were evaluated. Three hundred seventy-seven eyes of 377 patients were included in the study. Follow-up duration ranged from 24 to 54 (mean 40.27, SD 8.42) months. The incidence of PCO requiring Nd:YAG laser capsulotomy was found to be significantly less in the silicone lens group: 1.4% as compared with an incidence of 11.7% in the PMMA lens group (p = 0.018). In the square-edged acrylic group, visually significant PCO requiring Nd:YAG laser capsulotomy was observed in 3.6%, 4.8%, and 6.8% of eyes implanted with AcrySof MA60AC, Sensar Optiedge, and Akreos Adapt IOLs, respectively. In 5 of the 7 eyes (71.4%) exhibiting PCO in the PMMA group, the condition developed within the first 6 months. In the silicone and acrylic group, development of PCO was delayed. The rate of visually significant PCO as well as the need for Nd:YAG laser capsulotomy is influenced by IOL biomaterial in addition to square edge. It is significantly delayed with square-edged foldable acrylic and silicone IOLs compared with square-edged PMMA IOLs.

  19. Evaluation of different nonspecific binding blocking agents deposited inside poly(methyl methacrylate) microfluidic flow-cells.

    PubMed

    Le, Nam Cao Hoai; Gubala, Vladimir; Gandhiraman, Ram P; Daniels, Stephen; Williams, David E

    2011-07-19

    Poly(methyl methacrylate) (PMMA) flow-cells containing microwells were deposited with different nonspecific binding blocking agents, namely, bovine serum albumin (BSA), cationic lipid (DOTAP:DOPE) and diethylene glycol dimethyl ether (DEGDME). Water contact angle (WCA) and atomic force microscope (AFM) measurements were carried out to confirm the successful depositions of BSA, DOTAP, and DEGDME onto the PMMA surfaces. Fluorescent intensity measurements were performed to evaluate the degree of nonspecific adsorption of Cy5-labeled anti-IgG proteins onto plain and oxygen plasma-treated (PT) PMMA flow-cells as well as PMMA flow-cells deposited with different above-mentioned blocking agents. We then employed a label-free detection method called total internal reflection ellipsometry (TIRE) to evaluate the stability of the deposited blocking agents inside the PMMA flow-cells. It was found that, while DOTAP:DOPE was the best agent for blocking the nonspecific adsorption, it could be removed from the PMMA surfaces of the flow-cells upon rinsing with phosphate buffered saline (PBS) and later deposited back onto the Au-coated glass sensing substrate of the TIRE. The removal of the blocking agents from PMMA surfaces and their deposition onto the sensing substrate were further manifested by measuring the kinetics and the amount of adsorbed anti-α-hCG proteins. Overall, the dry DEGDME coating by plasma-enhanced chemical vapor deposition (PECVD) showed very good blocking and excellent stability for subsequent assay inside the microwells. Our results could be useful when one considers what blocking agents should be used for PMMA-based microfluidic immunosensor or biosensor devices by looking at both the blocking efficiency and the stability of the blocking agent.

  20. Biodegradable inorganic-organic hybrids of methacrylate star polymers for bone regeneration.

    PubMed

    Chung, Justin J; Fujita, Yuki; Li, Siwei; Stevens, Molly M; Kasuga, Toshihiro; Georgiou, Theoni K; Jones, Julian R

    2017-03-08

    Hybrids that are molecular scale co-networks of organic and inorganic components are promising biomaterials, improving the brittleness of bioactive glass and the strength of polymers. Methacrylate polymers have high potential as the organic source for hybrids since they can be produced, through controlled polymerization, with sophisticated polymer architectures that can bond to silicate networks. Previous studies showed the mechanical properties of hybrids can be modified by polymer architecture and molar mass (MM). However, biodegradability is critical if hybrids are to be used as tissue engineering scaffolds, since the templates must be remodelled by host tissue. Degradation by-products have to either completely biodegrade or be excreted by the kidneys. Enzyme, or bio-degradation is preferred to hydrolysis by water uptake as it is expected to give a more controlled degradation rate. Here, branched and star shaped poly(methyl methacrylate-co-3-(trimethoxysilyl)propyl methacrylate) (poly(MMA-co-TMSPMA)) were synthesized with disulphide based dimethacrylate (DSDMA) as a biodegradable branching agent. Biodegradability was confirmed by exposing the copolymers to glutathione, a tripeptide which is known to cleave disulphide bonds. Cleaved parts of the star polymer from the hybrid system were detected after 2weeks of immersion in glutathione solution, and MM was under threshold of kidney filtration. The presence of the branching agent did not reduce the mechanical properties of the hybrids and bone progenitor cells attached on the hybrids in vitro. Incorporation of the DSDMA branching agent has opened more possibilities to design biodegradable methacrylate polymer based hybrids for regenerative medicine.

  1. Identification and Quantitation of Volatile Organic Compounds in Poly(methyl methacrylate) Kitchen Utensils by Headspace Gas Chromatography/Mass Spectrometry.

    PubMed

    Ohno, Hiroyuki; Mutsuga, Motoh; Kawamura, Yoko

    2014-01-01

    A headspace GC/MS method was developed for identification and quantitation of residual volatile organic compounds in poly(methyl methacrylate) (PMMA) kitchen utensils. A sample was cut into small pieces, then N,N-dimethylacetamide was added in a headspace vial and sealed. After storing for more than 1 day at room temperature, the vial was incubated for 1 h at 90°C, and the headspace gas was analyzed by GC/MS. In 24 PMMA kitchen utensils, 16 volatile organic compounds including methyl methacrylate, methyl acrylate, toluene, 2-methyl-1-butene, 2-methyl-2-butene, 2-methylpropanal, methyl propionate, methyl isobutyrate, trans-3-heptene, heptane, cis-3-heptene, trans-2-heptene, cis-2-heptene, 2,4,4-trimethyl-1-pentene, 2,4,4-trimethyl-2-pentene, and 1-octene were identified and quantitated. These 15 volatile compounds except methyl methacrylate were found for the first time in PMMA kitchen utensils. Recovery rates from spiked samples were 97.4-104.0% with CV values of 2.8-9.6%. Samples contained 190-7900 μg/g of methyl methacrylate, 26-810 μg/g of methyl acrylate, and 2-1300 μg/g of toluene; other compounds were at levels less than 100 μg/g. Methyl methacrylate was the main monomer of PMMA and methyl acrylate was a comonomer; toluene should be used as a solvent.

  2. Increased cellular uptake of lauryl gallate loaded in superparamagnetic poly(methyl methacrylate) nanoparticles due to surface modification with folic acid.

    PubMed

    Feuser, Paulo Emilio; Arévalo, Juan Marcelo Carpio; Junior, Enio Lima; Rossi, Gustavo Rodrigues; da Silva Trindade, Edvaldo; Rocha, Maria Eliane Merlin; Jacques, Amanda Virtuoso; Ricci-Júnior, Eduardo; Santos-Silva, Maria Claudia; Sayer, Claudia; de Araújo, Pedro H Hermes

    2016-12-01

    Lauryl gallate loaded in superparamagnetic poly(methyl methacrylate) nanoparticles surface modified with folic acid were synthesized by miniemulsion polymerization in just one step. In vitro biocompatibility and cytotoxicity assays on L929 (murine fibroblast), human red blood, and HeLa (uterine colon cancer) cells were performed. The effect of folic acid at the nanoparticles surface was evaluated through cellular uptake assays in HeLa cells. Results showed that the presence of folic acid did not affect substantially the polymer particle size (~120 nm), the superparamagnetic behavior, the encapsulation efficiency of lauryl gallate (~87 %), the Zeta potential (~38 mV) of the polymeric nanoparticles or the release profile of lauryl gallate. The release profile of lauryl gallate from superparamagnetic poly(methyl methacrylate) nanoparticles presented an initial burst effect (0-1 h) followed by a slow and sustained release, indicating a biphasic release system. Lauryl gallate loaded in superparamagnetic poly(methyl methacrylate) nanoparticles with folic acid did not present cytotoxicity effects on L929 and human red blood cells. However, free lauryl gallate presented significant cytotoxic effects on L929 and human red blood cells at all tested concentrations. The presence of folic acid increased the cytotoxicity of lauryl gallate loaded in nanoparticles on HeLa cells due to a higher cellular uptake when HeLa cells were incubated at 37 °C. On the other hand, when the nanoparticles were incubated at low temperature (4 °C) cellular uptake was not observed, suggesting that the uptake occurred by folate receptor mediated energy-dependent endocytosis. Based on presented results our work suggests that this carrier system can be an excellent alternative in targeted drug delivery by folate receptor.

  3. Synthesis of tetraaza bromide macrocyclic and studies of its effect on poly(methyl methacrylate) grafted natural rubber (MG49) - lithium tertrafluoroborate (LiBF4) films

    NASA Astrophysics Data System (ADS)

    Mariam, Siti Nor; Yamin, Bohari M.; Ahmad, Azizan

    2013-11-01

    Good Poly(Methyl Methacrylate) Grafted natural Rubber (MG49) films with homogeneous and smooth surface were obtained in the presence of Lithium Tertrafluoroborate (LiBF4) and 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-7,14-dienium bromide, (Me6N4H4)Br2 as dopants. The conductivity was found to be 3.63×10-6 S/cm an increase by seven fold compare to the undoped MG49.

  4. Synthesis of tetraaza bromide macrocyclic and studies of its effect on poly(methyl methacrylate) grafted natural rubber (MG49) - lithium tertrafluoroborate (LiBF{sub 4}) films

    SciTech Connect

    Mariam, Siti Nor; Yamin, Bohari M.; Ahmad, Azizan

    2013-11-27

    Good Poly(Methyl Methacrylate) Grafted natural Rubber (MG49) films with homogeneous and smooth surface were obtained in the presence of Lithium Tertrafluoroborate (LiBF{sub 4}) and 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-7,14-dienium bromide, (Me{sub 6}N{sub 4}H{sub 4})Br{sub 2} as dopants. The conductivity was found to be 3.63×10{sup −6} S/cm an increase by seven fold compare to the undoped MG49.

  5. CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: Solid State Dye Lasers Based on Coumarin 440 and Pyrromethene 567 Codoped Polymethyl Methacrylate

    NASA Astrophysics Data System (ADS)

    Fan, Rong-Wei; Li, Xiao-Hui; Xia, Yuan-Qin; Jiang, Yu-Gang; He, Wei-Ming; Chen, De-Ying

    2008-05-01

    Laser dye coumarin 440(C440) is codoped with pyrromethene 567 (PM567) into polymethyl methacrylate (PMMA). The effects of C440 concentration on the performance of the solid state dye medium, including spectra property, slope efficiency and photostability, are studied. When C440 is codoped with PM567 at the same concentration 1 × 10-4 mol/L, the highest efficiency and photostability can be obtained. Compared with the medium based on pure PM567 doped PMMA, about 50% increase in slope efficiency and at least five-fold enhancement in the photostability are observed.

  6. Preparation of a new micro-porous poly(methyl methacrylate)-grafted polyethylene separator for high performance Li secondary battery

    NASA Astrophysics Data System (ADS)

    Gwon, Sung-Jin; Choi, Jae-Hak; Sohn, Joon-Yong; Ihm, Young-Eon; Nho, Young-Chang

    2009-10-01

    In this study, micro-porous poly(methyl methacrylate)-grafted polyethylene separators (PE-g-PMMA) were prepared by a radiation-induced graft polymerization of methyl methacrylate onto a conventional PE separator followed by a phase inversion. After the phase inversion, the micro-pores were generated in the grafted PMMA layer. The prepared micro-porous PE-g-PMMA separators showed an improved electrolyte uptake and ionic conductivity due to their improved affinity with a liquid electrolyte and the presence of pores in the grafted PMMA layer. The PE-g-PMMA separators exhibited a lower thermal shrinkage compared to the original PE separator. The PE-g-PMMA separators showed a better oxidation stability up to 5.0 V when compared to the original PE separator (4.5 V).

  7. In situ synthesis of poly(methyl methacrylate)/MgAl layered double hydroxide nanocomposite with high transparency and enhanced thermal properties

    NASA Astrophysics Data System (ADS)

    Chen, Wei; Feng, Li; Qu, Baojun

    2004-04-01

    A novel poly(methyl methacrylate)/MgAl layered double hydroxide (LDH) nanocomposite (PMMA-MgAl NC) with high transparency and enhanced thermal properties was synthesized in situ by adding sodium hydroxide aqueous solution to an emulsion consisting of metal ion aqueous solution, sodium dodecyl sulfate, methyl methacrylate, and benzoyl peroxide, then followed by the thermal initiation polymerization. The basal spacing of PMMA-MgAl NC was 2.72 nm determined by X-ray diffraction measurement. The intercalated MgAl LDH particles of 60-120 nm width and 25-40 nm thickness were well dispersed at molecular level in the PMMA matrix. When the 50% weight loss was selected as a comparison point, the decomposition temperature of PMMA-MgAl NC sample with 30 wt% MgAl LDH (including dodecyl sulfate) was ca. 45 °C higher than that of pure PMMA.

  8. The role of adsorption of sodium bis(2-ethylhexyl) sulfosuccinate in wetting of glass and poly(methyl methacrylate) surface

    NASA Astrophysics Data System (ADS)

    Harkot, Joanna; Jańczuk, Bronisław

    2008-02-01

    Advancing contact angles, θ, for aqueous solutions of the anionic surfactant, sodium bis(2-ethylhexyl) sulfosuccinate (AOT) were measured on glass and poly(methyl methacrylate) (PMMA) surface. Using the obtained results we determined the properties of aqueous AOT solutions in wetting of these surfaces. It occurs that the wettability of glass and PMMA by these solutions depends on the concentration of AOT in solution. There is almost linear dependence between the contact angle ( θ) and concentration of AOT (log C) in the range from 5 × 10 -4 to 2.5 × 10 -3 M/dm 3 (value of the critical micelle concentration of AOT—CMC) both for glass and PMMA surface. For calculations of AOT adsorption at solid (glass, PMMA)-solution drop-air system interfaces the relationship between the adhesion tension ( γLV cos θ) and surface tension ( γLV) and the Gibbs and Young equations were taken into account. From the measurement and calculation results the slope of the γLV cos θ - γ LV curve was found to be constant and equal 0.7 for glass and -0.1 for PMMA over the whole range of AOT concentration in solution. From this fact it can be concluded that if ΓSV is equal zero then ΓSL > 0 for the PMMA-solution and ΓSL < 0 for glass-solution systems. It means that surfactant concentration excess at PMMA-solution interface is considerably lower than at solution-air interface, but this excess of AOT concentration at glass-solution interface is lower than in the bulk phase. By extrapolating the linear dependence between the adhesion and surface tension the value of the critical surface tension ( γc) of wetting for glass and PMMA was also determined, that equaled 25.9 and 25.6 mN/m for glass and PMMA, respectively. Using the value of the glass and PMMA surface tension as well as the measured surface tension of aqueous AOT solutions in Young equation, the solid-liquid interface tension ( γSL) was found. There was a linear dependence between the γSL and γLV both for glass and PMMA

  9. Influence of incorporation of ZrO2 nanoparticles on the repair strength of polymethyl methacrylate denture bases.

    PubMed

    Gad, Mohammed M; Rahoma, Ahmed; Al-Thobity, Ahmad M; ArRejaie, Aws S

    Repeated fracture of the denture base is a common problem in prosthodontics, and it represents a nuisance and a time sink for the clinician. Therefore, the possibility of increasing repair strength using new reinforcement materials is of great interest to prosthodontists. This study aimed to evaluate the effects of incorporation of zirconia nanoparticles (nano-ZrO2) on the flexural strength and impact strength of repaired polymethyl methacrylate (PMMA) denture bases. One hundred eighty specimens of heat-polymerized acrylic resin were fabricated (90 for each test) and divided into three main groups: one control group (intact specimens) and two groups divided according to surface design (45° bevels and butt joints), in which specimens were prepared in pairs to create 2.5 mm gaps. Nano-ZrO2 was added to repair resin in 2.5 wt%, 5 wt%, and 7.5 wt% concentrations of acrylic powder. A three-point bending test was used to measure flexural strength, and a Charpy-type test was used to measure impact strength. Scanning electron microscopy was used to analyze the fracture surfaces and nano-ZrO2 distribution. The results were analyzed with a paired sample t-test and an unpaired t-test, with a P-value of ≤0.05 being significant. Incorporation of nano-ZrO2 into the repair resin significantly increased flexural strength (P<0.05). The highest value was found in the bevel group reinforced with 7.5% nano-ZrO2, whereas the lowest value was found in the butt group reinforced with 2.5% nano-ZrO2. The impact strength values of all repaired groups were significantly lower than those of the control group (P<0.05). Among repaired groups, the higher impact strength value was seen in the butt group reinforced with 2.5% nano-ZrO2. The bevel joint demonstrated mainly cohesive failure, whereas the butt joint demonstrated mainly adhesive failure. Incorporation of nano-ZrO2 into the repair resin improved the flexural strength of repaired denture bases, whereas it decreased impact strength

  10. Properties of electrospun CdS and CdSe filled poly(methyl methacrylate) (PMMA) nanofibres

    SciTech Connect

    Mthethwa, T.P.; Moloto, M.J.; De Vries, A.; Matabola, K.P.

    2011-04-15

    Graphical abstract: SEM images of CdS/PMMA showing coiling as loading of CdS nanoparticles is increased. Thermal stability is increased with increase in %loading of both CdS and CdSe nanoparticles. Research highlights: {yields} TOPO-capped CdS and HDA-capped CdSe nanoparticles were synthesized and fully characterized. {yields} The nanoparticles were mixed with the polymer, PMMA using electrospinning technique using 2, 5 and 10% weight loadings. {yields} The mixture was spun to produce fibres with optical and thermal properties showing significant change and also the increase in loading causing bending or spiraling. {yields} Both TEM images for nanoparticles and SEM for fibres shows the morphology and sizes of the particles. -- Abstract: Electrospinning technique was used to fabricate poly(methyl methacrylate) (PMMA) fibres incorporating CdS and CdSe quantum dots (nanoparticles). Different nanoparticle loadings (2, 5 and 10 wt% with respect to PMMA) were used and the effect of the quantum dots on the properties of the fibres was studied. The optical properties of the hybrid composite fibres were investigated by photoluminescence and UV-vis spectrophotometry. Scanning electron microscopy (SEM), X-ray diffraction and FTIR spectrophotometry were also used to investigate the morphology and structure of the fibres. The optical studies showed that the size-tunable optical properties can be achieved in the polymer fibres by addition of quantum dots. SEM images showed that the morphologies of the fibres were dependent on the added amounts of quantum dots. A spiral type of morphology was observed with an increase in the concentration of CdS and CdSe nanoparticles. Less beaded structures and bigger diameter fibres were obtained at higher quantum dot concentrations. X-ray diffractometry detected the amorphous peaks of the polymer and even after the quantum dots were added and the FTIR analysis shows that there was no considerable interaction between the quantum dots and the

  11. Influence of incorporation of ZrO2 nanoparticles on the repair strength of polymethyl methacrylate denture bases

    PubMed Central

    Gad, Mohammed M; Rahoma, Ahmed; Al-Thobity, Ahmad M; ArRejaie, Aws S

    2016-01-01

    Background Repeated fracture of the denture base is a common problem in prosthodontics, and it represents a nuisance and a time sink for the clinician. Therefore, the possibility of increasing repair strength using new reinforcement materials is of great interest to prosthodontists. Aim of the study This study aimed to evaluate the effects of incorporation of zirconia nanoparticles (nano-ZrO2) on the flexural strength and impact strength of repaired polymethyl methacrylate (PMMA) denture bases. Materials and methods One hundred eighty specimens of heat-polymerized acrylic resin were fabricated (90 for each test) and divided into three main groups: one control group (intact specimens) and two groups divided according to surface design (45° bevels and butt joints), in which specimens were prepared in pairs to create 2.5 mm gaps. Nano-ZrO2 was added to repair resin in 2.5 wt%, 5 wt%, and 7.5 wt% concentrations of acrylic powder. A three-point bending test was used to measure flexural strength, and a Charpy-type test was used to measure impact strength. Scanning electron microscopy was used to analyze the fracture surfaces and nano-ZrO2 distribution. The results were analyzed with a paired sample t-test and an unpaired t-test, with a P-value of ≤0.05 being significant. Results Incorporation of nano-ZrO2 into the repair resin significantly increased flexural strength (P<0.05). The highest value was found in the bevel group reinforced with 7.5% nano-ZrO2, whereas the lowest value was found in the butt group reinforced with 2.5% nano-ZrO2. The impact strength values of all repaired groups were significantly lower than those of the control group (P<0.05). Among repaired groups, the higher impact strength value was seen in the butt group reinforced with 2.5% nano-ZrO2. The bevel joint demonstrated mainly cohesive failure, whereas the butt joint demonstrated mainly adhesive failure. Conclusion Incorporation of nano-ZrO2 into the repair resin improved the flexural strength

  12. Quasi-elastic Raman scattering and free volume in isotropic pressure-densified atactic poly(methyl methacrylate) glasses

    NASA Astrophysics Data System (ADS)

    Schmidt, M.; Brodin, A.; Jacobsson, P.; Maurer, F. H. J.

    2000-01-01

    We have made a series of isotropic pressure-densified atactic poly(methyl methacrylate) (PMMA) glasses with densities ranging from 1.1823 g/cm3 to 1.1963 g/cm3, in order to investigate how the glassy dynamics, measured by Raman scattering in the frequency range of 0.1-10 THz, depends on the thermomechanical history of the glasses. In particular, we investigate whether there is a correlation between the strength of the fast relaxation dynamics and the free-volume characteristics, such as the average free-volume size and the free-volume fraction. The fast relaxation strength is deduced from the quasielastic light scattering (QES) intensity; the free-volume size is measured with positron annihilation lifetime spectroscopy (PALS); and the free-volume fraction is determined from pressure-volume-temperature (PVT) data and the Simha-Somcynsky equation-of-state (EOS) theory. Our temperature-dependent Raman and PALS measurements show that both the QES intensity and the ortho-positronium (o-Ps) lifetime increase smoothly with the temperature. On the other hand, the relaxation strength of the densified glasses at room temperature is, within experimental error, independent of the density, whereas both the o-Ps lifetime from PALS and the free volume fraction from the PVT data decrease significantly with pressure densification. We therefore conclude that the fast relaxation intensity cannot be explained on the basis of free-volume quantities, contrary to a recently suggested correlation between the QES intensity and the free volume [V. N. Novikov et al., J. Chem. Phys. 107, 1057 (1997)]. On the other hand, the observed behavior is consistent with another recently suggested model [V. N. Novikov, Phys. Rev. B 58, 8367 (1998)] which attributes the fast relaxations to vibration anharmonicity. Moreover, we show that the measured increase in the refractive index of the pressure-densified glasses fits the Lorentz-Lorenz equation and compares well to predictions of the relative change

  13. One-pot synthesis of biocompatible boronic acid-functionalized poly(methyl methacrylate) nanoparticles at sub-100 nm scale for glucose sensing

    NASA Astrophysics Data System (ADS)

    Sakalak, Huseyin; Ulasan, Mehmet; Yavuz, Emine; Camli, Sevket Tolga; Yavuz, Mustafa Selman

    2014-12-01

    Poly(methyl methacrylate) nanoparticles containing 4-vinylphenyl boronic acid were synthesized in one pot by surfactant-free emulsion polymerization. The nanoparticles were characterized by scanning electron microscopy and dynamic light scattering. Boron content in the nanoparticles was confirmed by electron-dispersive X-ray spectroscopy. In polymerization process, several co-monomer ratios were studied in order to obtain optimum nanoparticle size. Average hydrodynamic diameter and polydispersity index of nanoparticles versus variation of acetone percentage in the solvent mixture and total monomer concentration were investigated. The effect of boronic acid concentration in the monomer mixture on nanoparticle size and size distribution was also reported. Without further functionalization to the nanoparticles, the catechol dye, alizarin red S, was bound to boronic acid-containing nanoparticles. These nanoparticles behave as a nanosensor by which glucose or fructose can be easily detected. Dye-containing nanoparticles were undertaken displacement reaction by glucose or fructose. The glucose or fructose content was also monitored by UV-Visible spectrophotometer. Furthermore, cytotoxicity studies of boronic acid-carrying poly(methyl methacrylate) nanoparticles were carried out in 3T3 cells, which showed no toxicity effect on the cells.

  14. Characterization of new acrylic bone cement based on methyl methacrylate/1-hydroxypropyl methacrylate monomer.

    PubMed

    Pascual, B; Goñi, I; Gurruchaga, M

    1999-01-01

    New formulations of acrylic bone cement based on methyl methacrylate/1-hydroxypropyl methacrylate (MMA/HPMA) monomers were developed with the purpose of obtaining more ductile materials with reduced polymerization shrinkage. In this way, the ductility of such materials increased, but the introduction of high percentages of the hydrophilic component produced an important decrease in Young's modulus and strength. To ascertain the reason for the deterioration of the tensile parameters, an analysis by scanning electron microscopy of these formulations was carried out; it revealed poor adhesion between the matrix and poly(MMA) beads. We also observed that the polymerization shrinkage increased as the amount of hydrophilic monomer in the formulation decreased, and the 50% (v/v) HPMA modified bone cement compensated for this volume reduction with its water uptake swelling. Measurements taken on the setting time and polymerization exotherm showed a decrease in the former and an increase in the latter, because of the introduction of a more reactive monomer in the bone cement formulation.

  15. Effect of emulsion polymerization and magnetic field on the adsorption of albumin on poly(methyl methacrylate)-based biomaterial surfaces.

    PubMed

    Nita, Loredana E; Chiriac, Aurica P

    2010-08-01

    The adsorption of bovine serum albumin (BSA) onto the surfaces of poly(methyl methacrylate) (PMMA) and of methyl methacrylate copolymer with 2,3-epoxypropyl methacrylate, it was investigated. The polymeric matrices were obtained through radical emulsion polymerization with and without the presence of a continuous external magnetic field (MF) of 1,500 Gs intensity. Two types of surfactant agents were used for polymers' synthesis: a classic one sodium lauryl sulphate (SLS) and beta-cyclodextrin (CD). The protein adsorption was conducted in the presence as well as in the absence of MF, by varying the coupling conditions, respectively, the temperature, pH and albumin/polymer ratio. The study underlines the assistance of MF during the adsorption process, materialized into growth of the BSA adsorbed quantity. Thus, MF presence during adsorption determines the doubling of the BSA adsorbed quantity onto the surface of polymers prepared in the MF. The adsorption process was also related to the tensioactive used for the synthesis of polymeric matrices. The higher content of the adsorbed BSA corresponds to the polymers with CD instead of SLS. The fact was attributed to the catalytic activity of the MF, which determines the molecules distortions, the growth of distance interactions and the modifications of the angles between bonds, with benefit effect upon adsorption.

  16. Synthesis of branched poly(methyl methacrylate)s via controlled/living polymerisations exploiting ethylene glycol dimethacrylate as branching agent.

    PubMed

    Isaure, Francoise; Cormack, Peter A G; Graham, Susan; Sherrington, David C; Armes, Steven P; Bütun, Vural

    2004-05-07

    With appropriate choice of reaction composition and conditions, copolymerisation of methyl methacrylate and ethylene glycol dimethacrylate using Cu-based ATRP or GTP methodologies yields soluble branched polymers in facile one-pot reactions.

  17. Modified acrylic bone cement with high amounts of ethoxytriethyleneglycol methacrylate.

    PubMed

    Pascual, B; Gurruchaga, M; Ginebra, M P; Gil, F J; Planell, J A; Vázquez, B; San Román, J; Goñi, I

    1999-03-01

    One cause of arthroplasty failure is the brittle mechanical behavior of bone cements. However, the improvement of cement formulations must also be accompanied by the maintenance of a wide variety of characteristics. New bone cements were obtained by the substitution of high percentages, up to 60% (v/v), of methyl methacrylate (MMA) by a higher molecular weight and more hydrophilic monomer, ethoxytriethyleneglycol methacrylate (TEG). The essential advantages of these materials were the decrease of maximum temperature together with a decrease in the residual monomer content with respect to conventional cement formulations. The water absorption process obeyed diffusion laws and the equilibrium water content increased by the introduction of higher percentages of the hydrophilic component. This characteristic had an appreciable effect on the viscoelastic behavior analyzed by DMTA. These modified bone cements had reduced polymerization shrinkage and similar levels of porosity. Tensile test revealed that the introduction of TEGMA gave rise to an important modification of the mechanical behavior, with a noticeable increase in the fracture strain. This fact was also confirmed by means of the analysis of the fracture surfaces by SEM.

  18. Close-packed poly(methyl methacrylate) nanoparticle arrays-coated polyethylene separators for high-power lithium-ion polymer batteries

    NASA Astrophysics Data System (ADS)

    Park, Jang-Hoon; Park, Woong; Kim, Jong Hun; Ryoo, Dongjo; Kim, Hoon Sik; Jeong, Yeon Uk; Kim, Dong-Won; Lee, Sang-Young

    In an endeavor to improve the discharge C-rate performance of lithium-ion polymer batteries targeting high-power applications, we develop a novel gel polymer electrolyte-coated separator, which is based on introduction of close-packed poly(methyl methacrylate) (PMMA) nanoparticle arrays onto a polyethylene (PE) separator. In contrast to a conventional PMMA dense coating layer, a noticeable feature of the PMMA nanoparticle array coating layer is its highly ordered nanoporous structure, i.e. well-connected interstitial voids formed between the close-packed PMMA nanoparticles. This unique morphology allows for not only favorable liquid electrolyte wettability but also facile ionic conduction of the PMMA nanoparticle arrays-coated separator, both of which play crucial roles in improving the discharge C-rate performance of cells assembled with the separator.

  19. Polarity-indicative two-dimensional periodic relief gratings of tethered poly(methyl methacrylate) on silicon surfaces for visualization in volatile organic compound sensing

    NASA Astrophysics Data System (ADS)

    Chen, Jem-Kun; Wang, Jing-Hong; Cheng, Chih-Chia; Chang, Jia-Yaw; Chang, Feng-Chih

    2013-04-01

    We grafted poly(methyl methacrylate) (PMMA) from a 200 nm-resolution hole array of photoresist on a silicon substrate as a pillar array of two-dimensional periodic relief grating (2DPRG). The resulting 2DPRGs have been used as detectors of organic solvents in surrounding media, based upon structure change of the 2DPRG as a consequence of the solvent induced reversible swelling-deswelling of PMMA chains, through effective refractive index. Dramatic colors change, purple, green, yellow, and red, was observed by naked eyes along an incident angle of 60°-70° as the surrounding media of PMMA-modified 2DPRG was acetone, tetrahydrofuran, dioxane, and chloroform, respectively.

  20. Ionogels Based on Poly(methyl methacrylate) and Metal-Containing Ionic Liquids: Correlation between Structure and Mechanical and Electrical Properties

    PubMed Central

    Zehbe, Kerstin; Kollosche, Matthias; Lardong, Sebastian; Kelling, Alexandra; Schilde, Uwe; Taubert, Andreas

    2016-01-01

    Ionogels (IGs) based on poly(methyl methacrylate) (PMMA) and the metal-containing ionic liquids (ILs) bis-1-butyl-3-methlimidazolium tetrachloridocuprate(II), tetrachloride cobaltate(II), and tetrachlorido manganate(II) have been synthesized and their mechanical and electrical properties have been correlated with their microstructure. Unlike many previous examples, the current IGs show a decreasing stability in stress-strain experiments on increasing IL fractions. The conductivities of the current IGs are lower than those observed in similar examples in the literature. Both effects are caused by a two-phase structure with micrometer-sized IL-rich domains homogeneously dispersed an IL-deficient continuous PMMA phase. This study demonstrates that the IL-polymer miscibility and the morphology of the IGs are key parameters to control the (macroscopic) properties of IGs. PMID:26999112

  1. On the correlation between the photoexcitation pathways and the critical energies required for ablation of poly(methyl methacrylate): A molecular dynamics study

    SciTech Connect

    Conforti, Patrick F.; Prasad, Manish; Garrison, Barbara J.

    2008-05-15

    The energetics initiating ablation in poly(methyl methacrylate) (PMMA) are studied using molecular dynamics (MD) simulation. The critical energy to initiate ablation in PMMA following the absorption of photons is investigated for two penetration depths along a range of fluences using a coarse-grained, hybrid Monte Carlo-MD scheme. Both heating and direct bond scission are simulated separately after photon absorption with additional transformation of material occurring via chemical reactions following the photochemical bond cleavage. For a given type of absorption and reaction channel, a critical energy can well describe the amount of energy required to initiate ablation. The simulations show a decrease in the critical energy when a greater amount of photochemistry is introduced in the system. The simulations complement experimental studies and elucidate how enhanced photochemistry lowers ablation thresholds in polymer substrates.

  2. Polymethyl methacrylate intraocular lens opacification 20 years after cataract surgery: A case report in a tertiary eye hospital in Saudi Arabia

    PubMed Central

    Al-Otaibi, Abdullah G.; Al-Qahtani, Elham S.

    2011-01-01

    Snowflake degeneration is a slow progressive opacification of polymethyl methacrylate (PMMA) intraocular lenses (IOLs). This late postoperative complication can occur a decade or later after implantation. The deposits are composed of IOL materials that tend to aggregate centrally. There is a relative paucity of the literature on snowflake degeneration of IOLs. Symptoms can range from mild visual disturbance to significant loss of visual acuity. In cases of opacification after IOL implantation, the different diagnosis should include snowflake degeneration to prevent surgical intervention such as lens exchange or explantation unless clinically warranted. We report a case of late optical opacification of a PMMA IOL, the clinical diagnosis and treatment that increased best corrected vision. PMID:23960977

  3. Self-assembly between graphene sheets and cationic poly(methyl methacrylate) (PMMA) particles: preparation and characterization of PMMA/graphene composites

    NASA Astrophysics Data System (ADS)

    Yang, Jintao; Yan, Xiaohui; Wu, Minjie; Chen, Feng; Fei, Zhengdong; Zhong, Mingqiang

    2012-01-01

    In this study, we presented a simple approach to prepare poly(methyl methacrylate) (PMMA)/graphene composites based on the self-assembly between graphene oxide (GO) sheets and cationic PMMA emulsion particles. Briefly, cationic PMMA emulsion particles were first synthesized by a soap-free emulsion polymerization process, in which methacryloyloxyethyl trimethyl ammonium chloride was used as the emulsifier, and then blended with the aqueous solution of GO. Through electrostatic attraction, the exfoliated GO sheets were tightly adhered on the PMMA particles. The GO sheets could be reduced in situ into graphene sheets by a chemical method, without the aggregation. The structure of the prepared composites and the influences of GO and graphene sheets on the properties of PMMA were investigated. Both GO and graphene sheets can increase the glass transition temperature and storage modulus of PMMA. Moreover, graphene sheets provided a more significant reinforcement effect.

  4. Synthesis of Well-Defined Miktoarm Star Copolymer composed of Poly(3-hexylthiophene) and Poly(methyl methacrylate) via combining anionic polymerization and click reaction

    NASA Astrophysics Data System (ADS)

    Park, Jicheol; Moon, Hong Chul; Kim, Jin Kon

    2013-03-01

    We synthesized well-defined miktoarm star copolymer composed of regioregular poly(3-hexylthiophene) and poly(methyl methacrylate) ((P3HT)2- b-PMMA) by combining anionic polymerization and click reaction. First, we synthesized PMMA terminated with 1,3,5-tris(bromomethy)lbenzene (PMMA-(br)2) by anionic polymerization. Then, the bromide end groups transformed to azide group (PMMA-(N3)2) . For the synthesis (P3HT)2- b-PMMA, click reaction between ethynyl-capped P3HT and PMMA-(N3)2 was performed. The optical property and thin film morphology of (P3HT)2- b-PMMA were investigated by using UV-Vis spectra and atomic force microscopy, respectively.

  5. Effect of mixing mode and emulsifying agents on micro/nanoencapsulation of low viscosity self-healing agents in polymethyl methacrylate shell

    NASA Astrophysics Data System (ADS)

    Ahangaran, Fatemeh; Navarchian, Amir H.; Hayaty, Mehran; Esmailpour, Karim

    2016-09-01

    In this study, epoxy prepolymer (EC 157) and pentaerythritol tetrakis (3-mercaptopropionate) (PETMP) as hardener were encapsulated separately in polymethyl methacrylate (PMMA) shells through an internal phase separation method. Chemical structures, morphologies, and thermal properties of healing agent micro/nanocapsules were characterized by Fourier transform infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FESEM), and thermal gravimetric analysis (TGA) respectively. The effects of encapsulation processing conditions such as mechanical mixing rate, ultrasonication, emulsifier type, and co-emulsifier concentration on encapsulation yield, capsule mean diameter and core content were studied using the Taguchi experimental design approach. The results indicated that the main significant factors affecting the yield of encapsulation are emulsifier type and ultrasonication. The most important factors which affect the mean diameter of capsules are emulsifier type and mechanical mixing rate. The core content was influenced by ultrasonication and mechanical mixing rate. The relative optimum condition of encapsulation was also determined using overall evaluation criteria.

  6. Carrier transport in flexible organic bistable devices of ZnO nanoparticles embedded in an insulating poly(methyl methacrylate) polymer layer

    NASA Astrophysics Data System (ADS)

    Son, Dong-Ick; Park, Dong-Hee; Choi, Won Kook; Cho, Sung-Hwan; Kim, Won-Tae; Kim, Tae Whan

    2009-05-01

    The bistable effects of ZnO nanoparticles embedded in an insulating poly(methyl methacrylate) (PMMA) polymer single layer by using flexible polyethylene terephthalate (PET) substrates were investigated. Transmission electron microscopy (TEM) images revealed that ZnO nanoparticles were formed inside the PMMA polymer layer. Current-voltage (I-V) measurement on the Al/ZnO nanoparticles embedded in an insulating PMMA polymer layer/ITO/PET structures at 300 K showed a nonvolatile electrical bistability behavior with a flat-band voltage shift due to the existence of the ZnO nanoparticles, indicative of trapping, storing, and emission of charges in the electronic states of the ZnO nanoparticles. The carrier transport mechanism of the bistable behavior for the fabricated organic bistable device (OBD) structures is described on the basis of the I-V results by analyzing the effect of space charge.

  7. Effects of the novel poly(methyl methacrylate) (PMMA)-encapsulated organic ultraviolet (UV) filters on the UV absorbance and in vitro sun protection factor (SPF).

    PubMed

    Wu, Pey-Shiuan; Huang, Lan-Ni; Guo, Yi-Cing; Lin, Chih-Chien

    2014-02-05

    Sunscreens are thought to protect skin from many of the harmful effects of ultraviolet (UV) light and the photostability of sunscreens is thus an important concern in their application. Therefore, to discover new UV filters or to modify well-known UV filters are presents an important way for development of sunscreens. In this study, we presented several novel poly(methyl methacrylate) (PMMA) encapsulated organic UV filters, including encapsulated benzophenone-3 (TB-MS), avobenzone (TA-MS), octyl methoxycinnamate (TO-MS) and diethylamino hydroxybenzoyl hexyl benzoate (TD-MS). Our results have demonstrated that PMMA-encapsulated UV filters have improved safety, photoprotective ability and photostability. We proposed therefore that these PMMA-encapsulated UV filters can be used as ingredients for sunscreen products in the future. Copyright © 2014 Elsevier B.V. All rights reserved.

  8. Sensitive electrochemical detection of superoxide anion using gold nanoparticles distributed poly(methyl methacrylate)-polyaniline core-shell electrospun composite electrode.

    PubMed

    Santhosh, Padmanabhan; Manesh, Kalayil Manian; Lee, Se-Hee; Uthayakumar, Sivaperumal; Gopalan, Anantha Iyengar; Lee, Kwang-Pill

    2011-04-21

    In the present communication, a novel composite nanofibrous electrode is developed for the detection of superoxide anion (O(2)˙(-)) in phosphate buffered saline (PBS). The composite fiber electrode is fabricated by dispersing gold nanoparticles onto poly(methyl methacrylate) (PMMA)-polyaniline (PANI) core-shell electrospun nanofibers. The constructed architecture is proven to be a favorable environment for the immobilization of the enzyme, superoxide dismutase (SOD). Direct electron transfer is achieved between SOD and the electrode with an electron transfer rate constant of 8.93 s(-1). At an applied potential of +300 mV, PMMA/PANI-Au(nano)/SOD-ESCFM shows highly sensitive detection of O(2)˙(-). In addition to this, quantification of different activities of SOD is realized at PMMA/PANI-Au(nano)/SOD-ESCFM. These analytical features offer great potential for construction of the third-generation O(2)˙(-) biosensor.

  9. Real-time measurement of photo-induced effects in 9,10-phenanthrenequinone-doped poly(methyl methacrylate) photopolymer by phase-modulated ellipsometry

    NASA Astrophysics Data System (ADS)

    Chuang, Chun-I.; Hsiao, Yi-Nan; Lin, Shiuan-Huei; Chao, Yu-Faye

    2010-09-01

    The photo-induced effects in 9,10-phenanthrenequinone-doped (PQ-doped) poly(methyl methacrylate) (PMMA) photopolymer were studied by phase-modulated ellipsometry and polarimetry in real time. The PQ-doped PMMA was exposed to an Ar/Kr tunable laser at the wavelength of 488 nm and measured by a HeNe laser (632.8 nm). We measured the induced birefringence and the variation of the refractive index separately during exposure; there was a difference of three orders of magnitude between these two effects. This suggested that the physical mechanism of holographic recording in PQ-doped PMMA is mainly due to the photo-induced variation in the refractive index.

  10. Surface modification of silk fibroin fibers with poly(methyl methacrylate) and poly(tributylsilyl methacrylate) via RAFT polymerization for marine antifouling applications.

    PubMed

    Buga, Mihaela-Ramona; Zaharia, Cătălin; Bălan, Mihai; Bressy, Christine; Ziarelli, Fabio; Margaillan, André

    2015-06-01

    In this study, silk fibroin surface containing hydroxyl and aminogroups was firstly modified using a polymerizable coupling agent 3-(trimethoxysilyl) propyl methacrylate (MPS), in order to induce vinyl groups onto the fiber surface. The reversible addition-fragmentation chain transfer (RAFT)-mediated polymerization of methyl methacrylate (MMA) and tributylsilyl methacrylate (TBSiMA) through the immobilized vinyl bond on the silk fibroin surface in the presence of 2-cyanoprop-2-yl dithiobenzoate (CPDB) as chain-transfer agent and 2,2'-azobis(isobutyronitrile) (AIBN) as initiator was conducted in toluene solution at 70°C for 24h. The structure and properties of the modified fiber were characterized by Fourier Transform Infrared Spectroscopy, (13)C, (29)Si Nuclear Magnetic Resonance (NMR) spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS), confirming the presence of the coupling molecule and the methacrylate groups onto the silk fibroin fiber surface. Molecular weight distributions were assessed by triple detection size exclusion chromatography (TD-SEC) in order to verify the livingness of the polymerization.

  11. Preparation and characterization of poly(methyl methacrylate) and poly(maleic anhydride-co-diallyl phthalate) grafted carbon black through γ-ray irradiation

    NASA Astrophysics Data System (ADS)

    Bo, Yang; Cui, Jiayang; Cai, Yangben; Xu, Shiai

    2016-02-01

    In this study, the grafting polymerization of methyl methacrylate (MMA) monomer and maleic anhydride/diallyl phthalate (MAH/DAP) co-monomer onto the surface of carbon black (CB) were carried out at room temperature and normal pressure by γ-ray irradiation. The surface chemistry of grafted CBs were characterized by infrared spectroscopy (IR), thermo-gravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). The results show that there are some remanent polymers on the surface of modified CBs after extract for 48 h, indicating that poly(methyl methacrylate) (PMMA) and poly(MAH-co-DAP) have been successfully grafted onto the surface of CB without using initiator due to the high energy of γ-ray irradiation. Dynamic light scattering (DLS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) reveal that the grafted CBs have smaller average aggregate size and better dispersibility than that of CB in absolute ethanol. In addition, it was found that the amount of oxygen groups and the irradiation doses/dose rates have little effect on the grafting degree of CB.

  12. Synthesis of zinc oxide-encapsulated poly(methyl methacrylate)-chitosan core-shell hybrid particles and their electrochemical property.

    PubMed

    Petchthanasombat, Chayannan; Tiensing, Tinnakorn; Sunintaboon, Panya

    2012-03-01

    The synthesis of hybrid materials possessing zinc oxide nanoparticles encapsulated in core-shell polymer particles having poly(methyl methacrylate) core and chitosan shell (PMMA-CS/ZnO) was carried out via an emulsifier-free emulsion polymerization. The ZnO nanoparticles modified by 3-(trimethoxysilyl)propyl methacrylate (TPMZnO) were first prepared before being charged to the polymerization system. The effects of polymerization time (from 2 h to 6 h) and the amount of TPMZnO added (0.018 g, 0.020 g, and 0.030 g) were studied. It was found that the polymerization time of 5 h yielded colloidally stable hybrid latex with% MMA conversion up to 90%. Moreover, the increase in the amount of TPMZnO resulted in a decrease in% MMA conversion from 90% to 80%. It was also found from TGA analysis that the amount of TPMZnO added affected the percentage of TPMZnO encapsulation. PMMA-CS/ZnO particles with the size ranging from 173 to 245 nm were observed by TEM. In addition, the PMMA-CS/ZnO hybrid latexes possessed high positive charges in the range of 40-51 mV. The electrochemical property of the electrodes fabricated from PMMA-CS/ZnO nanoparticles was illustrated by cyclic voltammetry.

  13. Poly(methyl methacrylate)/layered zinc sulfide nanocomposites: Preparation, characterization and the improvements in thermal stability, flame retardant and optical properties

    SciTech Connect

    Wang, Biao; Zhou, Keqing; Jiang, Saihua; Shi, Yongqian; Wang, Bibo; Gui, Zhou; Hu, Yuan

    2014-08-15

    Highlights: • Layered zinc sulfide (LZnS) was synthesized successfully via hydrothermal method. • We prepare PMMA/LZnS nanocomposites by in situ bulk polymerization of MMA. • PMMA/LZnS nanocomposites were investigated by TGA, DSC, MCC, UV–vis and PL test. • The thermal stability, flame retardant and optical properties of PMMA are improved. - Abstract: Layered zinc sulfide (LZnS) was synthesized successfully via hydrothermal method and poly(methyl methacrylate) (PMMA)/layered zinc sulfide nanocomposites were obtained by in situ bulk polymerization of methyl methacrylate (MMA). X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to characterize the as-synthesized layered zinc sulfide and PMMA/layered zinc sulfide nanocomposites. Microscale combustion calorimeter (MCC), differential scanning calorimeter (DSC) and thermogravimetric analysis (TGA) were used to test the thermal properties of the composites. Ultraviolet visible (UV–vis) transmittance spectra and photoluminence (PL) spectra were obtained to investigate the optical properties of the composites. From the results, the thermal degradation temperature is increased by 20–50 °C, the peak of heat release rate (pHRR) and total heat release (THR) are both decreased by above 30%, and the photoluminence intensity is enhanced with the increasing loading of layered zinc sulfide.

  14. Surface segregation of fluorinated moieties on poly(methyl methacrylate-ran-2-perfluorooctylethyl methacrylate) films during film formation: Entropic or enthalpic influences.

    PubMed

    Ye, Xiuyun; Zuo, Biao; Deng, Mao; Hei, Yanlin; Ni, Huagang; Lu, Xiaolin; Wang, Xinping

    2010-09-01

    The effects of solvents, fluorinated monomer content and film-formation methods on the surface structures of random copolymers composed of methyl methacrylate (MMA) and 2-perfluorooctylethyl methacrylate (FMA) were investigated by contact angle goniometry, X-ray photoelectron spectroscopy, sum frequency generation (SFG) vibrational spectroscopy and surface tension measurement. It is found that, with cyclohexanone as the solvent, there is a critical FMA content of 9mol%, below which the copolymer films by spin coating have a more surface segregation extent of fluorinated moieties than those by solution casting; above which the copolymer films by solution casting have a more surface segregation extent of fluorinated moieties than those by spin coating. However, with toluene as solvent, the critical FMA content lowers down to 3mol%. We believe that the solvent nature and the content of fluorinated moieties in the random copolymer have the great effect because the combined effect of these two factors can determine the random copolymer chain conformations and their thermodynamic dominating factors in the solution and at the solution-air interface. A thermodynamic analysis combining the entropic and enthalpic effects is suggested to explain the observed phenomenon. This research is believed to obtain an enhanced understanding of the surface formation mechanism of the polymer films and thus demonstrate how to promote the segregation of fluorinated moieties at the polymer film surfaces.

  15. Relationship between water structure and properties of poly(methyl methacrylate-b-2-hydroxyethyl methacrylate) by solid-state NMR.

    PubMed

    Mochizuki, Akira; Miwa, Yuko; Miyoshi, Riko; Namiki, Takahiro

    2017-03-22

    We previously reported that the platelet compatibility of methyl methacrylate (MMA)-2-hydroxyethyl methacrylate (HEMA) diblock copolymers is related to the characteristic water structure in the copolymer, as the copolymer has an excess amount of nonfreezing water when compared with that estimated from the amounts of water in HEMA and MMA homopolymers. Thus, in this study, the relationship between water structure and polymer structure, including the heterogeneity and mobility of the copolymer, was investigated using differential scanning calorimetry (DSC) and nuclear magnetic resonance (NMR) spectroscopy. The prepared copolymers were classified into two groups: copolymers with a short, constant polyMMA segment length (Mn = ~2900) and copolymers with a constant polyHEMA segment length (Mn = ~9500), whereas the lengths of the counter segments varied. DSC analysis showed that when the polyMMA and polyHEMA segment lengths are similar, the amount of nonfreezing water increases, regardless of the total molecular weight of the copolymer. NMR analysis showed that heterogeneity of the copolymer is enhanced and the mobility of the copolymer decreases when the segment lengths are similar. These findings suggested that the excess amount of nonfreezing water is formed when the properties of water near the HEMA unit change from freezing to nonfreezing owing to interactions with the MMA unit. In addition, it is suggested that the heterogeneity of the copolymer structure or the mobility of the polymer are involved in the generation of excess nonfreezing water.

  16. Methylation of acidic moieties in poly(methyl methacrylate-co-methacrylic acid) copolymers for end-group characterization by tandem mass spectrometry.

    PubMed

    Giordanengo, Rémi; Viel, Stéphane; Hidalgo, Manuel; Allard-Breton, Béatrice; Thévand, André; Charles, Laurence

    2010-07-30

    The complete structural characterization of a copolymer composed of methacrylic acid (MAA) and methyl methacrylate (MMA) units was achieved using tandem mass spectrometry. In a first step, collision-induced dissociation (CID) of sodiated MAA-MMA co-oligomers allowed us to determine the co-monomeric composition, the random nature of the copolymer and the sum of the end-group masses. However, dissociation reactions of MAA-based molecules mainly involve the acidic pendant groups, precluding individual characterization of the end groups. Therefore, methylation of all the acrylic acid moieties was performed to transform the MAA-MMA copolymer into a PMMA homopolymer, for which CID mainly proceeds via backbone cleavages. Using trimethylsilyldiazomethane as a derivatization agent, this methylation reaction was shown to be complete without affecting the end groups. Using fragmentation rules established for PMMA polymers together with accurate mass measurements of the product ions and knowledge of reagents used for the studied copolymer synthesis, a structure could be proposed for both end groups and it was found to be consistent with signals obtained in nuclear magnetic resonance spectra.

  17. Poly(butyl methacrylate-g-methoxypoly(ethylene glycol)) and poly(methyl methacrylate-g-methoxypoly(ethylene glycol)) graft copolymers: preparation and aqueous solution properties.

    PubMed

    Horgan, Adrian; Saunders, Brian; Vincent, Brian; Heenan, Richard K

    2003-06-15

    A series of water-soluble, amphiphilic graft copolymers has been prepared by free-radical copolymerization of methoxypoly(ethylene glycol) macromonomers, with either methyl methacrylate or butyl methacrylate as the comonomers, in water/ethanol solvent mixtures. Lower molecular weight copolymers were obtained by increasing the concentration of the initiator, azobisisobutyronitrile (AIBN), used in the polymerization reaction. However, the route used also led to the formation of significant quantities of tetramethylsuccinodinitrile, a toxic byproduct resulting from the cage reaction of AIBN. Static fluorescence measurements using pyrene as a probe, along with 1H NMR experiments, showed that the graft copolymers form aggregates in water at very low concentrations (approximately 0.01 g l(-1)) with the pendant hydrophilic graft chains forming a stabilizing shell around the hydrophobic backbone. An increase in the hydrophile-lipophile balance of the graft copolymers was found to lead to smaller aggregates with lower aggregation numbers and highly swollen hydrophilic shells, as revealed by small angle neutron scattering (SANS).

  18. Effect of the different chain transfer agents on molecular weight and optical properties of poly(methyl methacrylate)

    NASA Astrophysics Data System (ADS)

    Çetinkaya, Onur; Demirci, Gökhan; Mergo, Paweł

    2017-08-01

    Investigation of molecular weight and optical properties of poly(methyl metacrylate) (PMMA) polymerized in house with different chain transfer agents was studied. Isopropyl alcohol (IPA), n-butyl mercaptan (nBMC) and pentamethyl disilane (PMDS) were used as chain transfer agents. The molecular weight (Mw) of PMMA samples were measured by Ostwald viscometer. Mw of bulk polymer samples were decreased with increase the concentration of chain transfer agents (CTA). Since reactivity of used CTAs is not same, molecular weights of samples which were produced with different type of CTA but same concentration of CTA was varied. Higher concentration of n-BMC showed higher scattering. Transmission of samples could not be correlated with different concentration of CTA. Refractive index of samples was not affected by concentration of CTA nevertheless higher molecular weight of CTA showed higher refractive index.

  19. Ablation of poly(methyl methacrylate) and poly(2-hydroxyethyl methacrylate) by 308, 222 and 193 nm excimer-laser radiation

    NASA Astrophysics Data System (ADS)

    Costela, A.; Figuera, J. M.; Florido, F.; García-Moreno, I.; Collar, E. P.; Sastre, R.

    1995-03-01

    Data on the ablation of Poly(Methyl MetAcylate) (PMMA) and Poly(2-Hydroxyethyl MetAcylate) (PHEMA) with 0%, 1% and 20% of Ethylene Glycol DiMethAcrylate (EGDMA) as crosslinking monomer by 193, 222 and 308 nm laser radiation are presented. Direct photoetching of PMMA at 308 nm is demonstrated for laser fluences ranging from 2 to 18 J/cm2. The ablation rate of PHEMA is lower than the corresponding to PMMA and decreases when the amount of EGDMA increases. The determination of the absorbed energy density required to initiate significant ablation suggests that the photoetching mechanism is similar for all the polymers studied and is a function of the irradiation wavelength. The Beer-Lambert law, the Srinivasan, Smrtic and Babu (SSB) theory and the kinetic model of the moving interface are used to analyze the experimental results. It is shown that only the moving interface theory fits well the etch rate for all the selected polymers at the three radiation wavelengths.

  20. Surface modification of glycidyl-containing poly(methyl methacrylate) microchips using surface-initiated atom-transfer radical polymerization.

    PubMed

    Sun, Xuefei; Liu, Jikun; Lee, Milton L

    2008-02-01

    Fabrication of microfluidic systems from polymeric materials is attractive because of simplicity and low cost. Unfortunately, the surfaces of many polymeric materials can adsorb biological samples. Therefore, it is necessary to modify their surfaces before these polymeric materials can be used for separation and analysis. Oftentimes it is difficult to modify polymeric surfaces because of their resistance to chemical reaction. Recently, we introduced a surface-reactive acrylic polymer, poly(glycidyl methacrylate-co-methyl methacrylate) (PGMAMMA), which can be modified easily and is suitable for fabrication of microfluidic devices. Epoxy groups on the surface can be activated by air plasma treatment, hydrolysis, or aminolysis. In this work, the resulting hydroxyl or amino groups were reacted with 2-bromoisobutylryl bromide to introduce an initiator for surface-initiated atom-transfer radical polymerization (SI-ATRP). Polyethylene glycol (PEG) layers grown on the surface using this method were uniform, hydrophilic, stable, and resistant to protein adsorption. Contact angle measurement and X-ray photoelectron spectroscopy (XPS) were used to characterize activated polymer surfaces, initiator-bound surfaces, and PEG-grafted surfaces. We obtained excellent capillary electrophoresis (CE) separations of proteins and peptides with the PEG-modified microchips. A separation efficiency of 4.4 x 10(4) plates for a 3.5 cm long separation channel was obtained.

  1. Two-dimensional folded chain crystals composed of a single isotactic poly(methyl methacrylate) chain observed by atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Kumaki, Jiro; Anzai, Takahiro

    2014-03-01

    We successfully visualized crystallization behavior of a single isolated polymer chain at a molecular level by atomic force microscopy (AFM). Previously, we found that isotactic poly(methyl methacrylate) (it-PMMA) formed two-dimensional folded chain crystals upon compression of its Langmuir monolayer on a water surface, and the molecular images of the crystals deposited on mica were clearly visualized by AFM (Kumaki, et al. JACS 2005, 127, 5788; J. Phys. Chem. B 2013, 117, 5594). In the present study, a high-molecular-weight it-PMMA was diluted in a monolayer of an it-PMMA oligomer which cannot crystallize due to the low molecular weight. At a low surface pressure, isolated amorphous chains of the high-molecular-weight it-PMMA solubilized in the oligomer monolayer were observed. On compression, the isolated chains converted to crystals composed of a single chain. Detailed AFM observations of the crystals indicated that the crystalline nuclei preferably formed at the ends of the chains, and the size of the nuclei was almost independent on the molecular weight of the it-PMMA in a wide range.

  2. Effect of Storage in Distilled Water for Three Months on the Antimicrobial Properties of Poly(methyl methacrylate) Denture Base Material Doped with Inorganic Filler.

    PubMed

    Chladek, Grzegorz; Basa, Katarzyna; Mertas, Anna; Pakieła, Wojciech; Żmudzki, Jarosław; Bobela, Elżbieta; Król, Wojciech

    2016-04-29

    The colonization of poly(methyl methacrylate) (PMMA) denture base materials by pathogenic microorganisms is a major problem associated with the use of prostheses, and the incorporation of antimicrobial fillers is a method of improving the antimicrobial properties of these materials. Numerous studies have demonstrated the initial in vitro antimicrobial effectiveness of this type of material; however, reports demonstrating the stability of these fillers over longer periods are not available. In this study, silver sodium hydrogen zirconium phosphate was introduced into the powder component of a PMMA denture base material at concentrations of 0.25%, 0.5%, 1%, 2%, 4%, and 8% (w/w). The survival rates of the gram-positive bacterium Staphylococcus aureus, gram-negative bacterium Escherichia coli and yeast-type fungus Candida albicans were established after fungal or bacterial suspensions were incubated with samples that had been previously stored in distilled water. Storage over a three-month period led to the progressive reduction of the initial antimicrobial properties. The results of this study suggest that additional microbiological tests should be conducted for materials that are treated with antimicrobial fillers and intended for long-term use. Future long-term studies of the migration of silver ions from the polymer matrix and the influence of different media on this ion emission are required.

  3. External Electric Field Effects on Excited-State Intramolecular Proton Transfer in 4'-N,N-Dimethylamino-3-hydroxyflavone in Poly(methyl methacrylate) Films.

    PubMed

    Furukawa, Kazuki; Hino, Kazuyuki; Yamamoto, Norifumi; Awasthi, Kamlesh; Nakabayashi, Takakazu; Ohta, Nobuhiro; Sekiya, Hiroshi

    2015-09-17

    The external electric field effects on the steady-state electronic spectra and excited-state dynamics were investigated for 4'-N,N-(dimethylamino)-3-hydroxyflavone (DMHF) in a poly(methyl methacrylate) (PMMA) film. In the steady-state spectrum, dual emission was observed from the excited states of the normal (N*) and tautomer (T*) forms. Application of an external electric field of 1.0 MV·cm(-1) enhanced the N* emission and reduced the T* emission, indicating that the external electric field suppressed the excited-state intramolecular proton transfer (ESIPT). The fluorescence decay profiles were measured for the N* and T* forms. The change in the emission intensity ratio N*/T* induced by the external electric field is dominated by ESIPT from the Franck-Condon excited state of the N* form and vibrational cooling in potential wells of the N* and T* forms occurring within tens of picoseconds. Three manifolds of fluorescent states were identified for both the N* and T* forms. The excited-state dynamics of DMHF in PMMA films has been found to be very different from that in solution due to intermolecular interactions in a rigid environment.

  4. Close-packed SiO 2/poly(methyl methacrylate) binary nanoparticles-coated polyethylene separators for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Park, Jang-Hoon; Cho, Joo-Hyun; Park, Woong; Ryoo, Dongjo; Yoon, Su-Jin; Kim, Jong Hun; Jeong, Yeon Uk; Lee, Sang-Young

    In an endeavour to improve not only the thermal shrinkage but also the electrochemical performance of separators in lithium-ion batteries, a novel composite separator is developed, i.e., a close-packed SiO 2/poly(methyl methacrylate) (PMMA) binary nanoparticles-coated polyethylene (PE) separator. The introduction of SiO 2 nanoparticles to the coating layer effectively suppresses thermal shrinkage of the composite separator. In contrast to a SiO 2/PMMA coating layer having a film-shaped PMMA binder, the SiO 2/PMMA binary nanoparticle coating layer employs PMMA particles as a binder. As a consequence, a highly porous structure, i.e., well-connected interstitial voids, is formed between the binary SiO 2 and PMMA nanoparticles. The unique porous morphology allows favourable liquid electrolyte wettability and facile ionic conduction, which play a crucial role in improving cell performance such as the discharge capacity and the C-rate capability of the composite separator.

  5. Approach to knowledge of the interaction between the constituents of contact lenses and ocular tears: mixed monolayers of poly(methyl methacrylate) and dipalmitoyl phosphatidyl choline.

    PubMed

    Miñones Conde, M; Conde, O; Trillo, J M; Miñones, J

    2011-04-05

    Mixed monolayers of poly(methyl methacrylate) (PMMA), the main component of hard contact lenses, and dipalmitoyl phosphatidyl choline (DPPC), a characteristic phospholipidic constituent of ocular tear films, were selected as an in vitro model in order to observe the behavior of contact lenses on the eye. Using Langmuir monolayer and Brewster angle microscopy (BAM) techniques, the interaction between both components was analyzed from the data of surface pressure-area isotherms, compressional modulus-surface pressure, and relative film thickness versus time elapsed from the beginning of compression, together with BAM images. Regardless of the surface pressure at which the molecular/monomer areas (A(m)) were recorded, the A(m) mole fractions of PMMA (X(PMMA)) plots show that the experimental results match the theoretical values calculated from additivity rule A(m) = X(PMMA)A(PMMA) + X(DPPC)A(DPPC). The application of the Crisp phase rule to the phase diagram of the PMMA-DPPC system can explain the existence of a mixed monolayer made up of miscible components with ideal behavior at surface pressures below 25 mN/m. However, at very high surface pressures, when collapse is reached (at 60 mN/m), the single collapsed components are segregated into two independent phases. These results allows us to argue that PMMA hard contact lenses in the eye do not alter the structural characteristics of the phospholipid (DPPC) in tears.

  6. Encapsulation of Fe 3O 4 magnetic nanoparticles with poly(methyl methacrylate) via surface functionalized thiol-lactam initiated radical polymerization

    NASA Astrophysics Data System (ADS)

    Bach, Long Giang; Islam, Md. Rafiqul; Kim, Jong Tae; Seo, SungYong; Lim, Kwon Taek

    2012-01-01

    Poly(methyl methacrylate) (PMMA) was grafted onto Fe3O4 magnetic nanoparticles (MNPs) by using a thiol-lactam initiated radical polymerization (TLIRP) via grafting from approach. The surface of the MNPs was treated with the (3-mercaptopropyl)trimethoxysilane coupling agent to give thiol functionalized MNPs (MNPs-SH). Subsequently, the polymerization of MMA performed in the presence of the MNPs-SH and butyrolactam efficiently afforded PMMA-g-MNPs. The grafting of PMMA on the surface of the MNPs was investigated by FT-IR, 1H NMR, TGA, XPS, and EDX analyses. The morphology of the core/shell type PMMA-g-MNPs was confirmed by HR-TEM. GPC analysis showed that the molecular weight of PMMA and monomer conversion increased with the reaction time. The amount of the grafted polymer on the surface of the MNPs was found to be ca. 82.5% as estimated from TGA analysis. The MNPs and PMMA-g-MNPs were subjected to magnetic property investigation by SQUID, and the PMMA-g-MNPs showed relatively high saturated magnetization (53.3 emu/g) without any remanence or coercivity, which made the nanocomposites easily separable from solid-liquid phases suggesting their superparamagnetic character. The magnetic nanocomposites had an exceptionally good dispersibility in organic solvents as demonstrated by UV-Vis spectroscopy as well as time-dependent digital photographic monitoring.

  7. Applications of a new type of poly(methyl methacrylate)/TiO2 nanocomposite as an antibacterial agent and a reducing photocatalyst.

    PubMed

    Salabat, Alireza; Mirhoseini, Farid

    2015-09-26

    A new type of poly(methyl methacrylate) (PMMA)/TiO2 nanocomposite film sensitized by ionic liquids with a low dosage of TiO2 nanoparticles was prepared based on a microemulsion method. The photocatalytic activity, via the photoreduction of 4-nitrophenole (4-NP) to 4-aminophenole (4-AP) by NaBH4, and the photocatalytic-based antibacterial activity, for the destruction of Escherichia coli and Staphylococcus aureus, of the prepared nanocomposite film were investigated. The conditions for the maximum efficiency in the presence of visible light irradiation have been evaluated. The rate constant of the photoreduction of 4-NP to 4-AP was calculated and the maximum rate constant was found with the 0.01 wt% of TiO2 dosage in the photocatalyst and a solution pH of 7.5. The photocatalytic antibacterial maximum activity against Gram-negative bacteria was also obtained for the 0.01 wt% of TiO2 concentration of the photocatalyst. A notable result of this work is that PMMA/TiO2 nanocomposite films show efficient photocatalytic activity at very low loadings of TiO2, in contrast to other previous reports.

  8. Simultaneous encapsulation of magnetic nanoparticles and zinc phthalocyanine in poly(methyl methacrylate) nanoparticles by miniemulsion polymerization and in vitro studies.

    PubMed

    Feuser, Paulo Emilio; Fernandes, Andrielle Castilho; Nele, Marcio; Viegas, Alexandre da Cas; Ricci-Junior, Eduardo; Tedesco, Antônio Claudio; Sayer, Claudia; de Araújo, Pedro Henrique Hermes

    2015-11-01

    The aim of this work was the simultaneous encapsulation of magnetic nanoparticles (MNPs) and zinc(II) phthalocyanine (ZnPc) in poly(methyl methacrylate) (PMMA) (MNPsZnPc-PMMA) nanoparticles (NPs) by miniemulsion polymerization and to evaluate the photobiological activity and/or hyperthermia (HPT) against human glioblastoma cells (U87MG). MNPsZnPc-PMMA NPs presented an average diameter of 104 ± 2.5 nm with a polydispersity index (PdI) of 0.14 ± 0.03 and negative surface charge - 47 ± 2.2 mV (pH 7.4 ± 0.1). The encapsulation efficiency (EE%) of ZnPc was 85.7% ± 1.30. The release of ZnPc from PMMA NPs was slow and sustained without the presence of burst effect, indicating a homogeneous distribution of the drug in the polymeric matrix. In the biological assay, MNPsZnPc-PMMA NPs showed considerable cytotoxic effect on U87MG cells only after activation with visible light at 675 nm (photodynamic therapy, PDT) or after application of an alternating magnetic field. The simultaneous encapsulation of MNPs and ZnPc in a drug delivery system with sustained release can be a new alternative for cancer treatment leading to significant tumor regression after minimum doses of heat dissipation and light. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Experimental and Numerical Study on Effect of Sample Orientation on Auto-Ignition and Piloted Ignition of Poly(methyl methacrylate)

    PubMed Central

    Peng, Fei; Zhou, Xiao-Dong; Zhao, Kun; Wu, Zhi-Bo; Yang, Li-Zhong

    2015-01-01

    In this work, the effect of seven different sample orientations from 0° to 90° on pilot and non-pilot ignition of PMMA (poly(methyl methacrylate)) exposed to radiation has been studied with experimental and numerical methods. Some new and significant conclusions are drawn from the study, including a U-shape curve of ignition time and critical mass flux as sample angle increases for pilot ignition conditions. However, in auto-ignition, the ignition time and critical mass flux increases with sample angle α. Furthermore, a computational fluid dynamic model have been built based on the Fire Dynamics Simulator (FDS6) code to investigate the mechanisms controlling the dependence on sample orientation of the ignition of PMMA under external radiant heating. The results of theoretical analysis and modeling results indicate the decrease of total incident heat flux at sample surface plays the dominant role during the ignition processes of auto-ignition, but the volatiles gas flow has greater influence for piloted ignition conditions. PMID:28793421

  10. Custom CAD-CAM healing abutment and impression coping milled from a poly(methyl methacrylate) block and bonded to a titanium insert.

    PubMed

    Proussaefs, Periklis

    2016-11-01

    This article describes a technique in which a custom-made computer-aided design and computer-aided manufacturing (CAD-CAM) healing abutment milled from a poly(methyl methacrylate) (PMMA) block is fabricated and bonded to a titanium metal insert. An impression is made during dental implant surgery, and the CAD-CAM custom-made healing abutment is fabricated before second-stage surgery while appropriate healing time is allowed for the dental implant to osseointegrate. The contours of the healing abutment are based on the contours of a tentatively designed definitive prosthesis. The healing tissue obtains contours that will be compatible with the contours of the definitive prosthesis. After the milling process is complete, a titanium metal insert is bonded to the healing abutment. Placement of the custom-made CAD-CAM healing abutment at second-stage surgery allows the tissue to obtain contours similar to those of the definitive prosthesis. A custom-made CAD-CAM impression coping milled from a PMMA block and with a titanium insert is used for the definitive impression after the soft tissue has healed. This technique allows guided soft tissue healing by using a custom-made CAD-CAM healing abutment and impression coping.

  11. Multidetector thermal field-flow fractionation as a unique tool for the tacticity-based separation of poly(methyl methacrylate)-polystyrene block copolymer micelles.

    PubMed

    Greyling, Guilaume; Pasch, Harald

    2015-10-02

    Poly(methyl methacrylate)-polystyrene (PMMA-PS) micelles with isotactic and syndiotactic coronas are prepared in acetonitrile and subjected to thermal field-flow fractionation (ThFFF) analysis at various conditions of increasing temperature gradients. It is shown for the first time that multidetector ThFFF provides comprehensive information on important micelle characteristics such as size (Dh), shape (Rg/Rh), aggregation number (Z), thermal diffusion (DT) and Soret coefficients (ST) as a function of temperature from a single injection. Moreover, it is found that micelles exhibit a unique decreasing trend in DT as a function of temperature which is independent of the tacticity of the corona and the micelle preparation method used. It is also demonstrated that ThFFF can monitor micelle to vesicle transitions as a function of temperature. In addition to ThFFF, it is found from DLS analysis that the tacticity of the corona influences the critical micelle concentration and the magnitude to which micelles expand/contract with temperature. The tacticity does not, however, influence the critical micelle temperature. Furthermore, the separation of micelles based on the tacticity of the corona highlight the unique capabilities of ThFFF.

  12. Direct photo-etching of poly(methyl methacrylate) using focused extreme ultraviolet radiation from a table-top laser-induced plasma source

    SciTech Connect

    Barkusky, Frank; Peth, Christian; Bayer, Armin; Mann, Klaus

    2007-06-15

    In order to perform material interaction studies with intense extreme ultraviolet (EUV) radiation, a Schwarzschild mirror objective coated with Mo/Si multilayers was adapted to a compact laser-based EUV plasma source (pulse energy 3 mJ at {lambda}=13.5 nm, plasma diameter {approx}300 {mu}m). By 10x demagnified imaging of the plasma a pulse energy density of {approx}75 mJ/cm{sup 2} at a pulse length of 6 ns can be achieved in the image plane of the objective. As demonstrated for poly(methyl methacrylate) (PMMA), photoetching of polymer surfaces is possible at this EUV fluence level. This paper presents first results, including a systematic determination of PMMA etching rates under EUV irradiation. Furthermore, the contribution of out-of-band radiation to the surface etching of PMMA was investigated by conducting a diffraction experiment for spectral discrimination from higher wavelength radiation. Imaging of a pinhole positioned behind the plasma accomplished the generation of an EUV spot of 1 {mu}m diameter, which was employed for direct writing of surface structures in PMMA.

  13. Alpha and recoil track detection in poly(methyl methacrylate) (PMMA)—Towards a method for in vitro assessment of radiopharmaceuticals internalized in cancer cells

    SciTech Connect

    Myhra, S. Chakalova, R.; Falzone, N.

    2014-03-15

    A method for detection and characterization of single MeV α-particle and recoil tracks in PMMA photoresist by atomic force microscopy (AFM) analysis has been demonstrated. The energy deposition along the track is shown to lead to a latent pattern in the resist due to contrast reversal. It has been shown that the pattern, consisting of conical spikes, can be developed by conventional processing as a result of the dissolution rate of poly(methyl methacrylate) (PMMA) being greater than that for the modified material in the cylindrical volume of the track core. The spikes can be imaged and counted by routine AFM analysis. Investigations by angular-resolved near-grazing incidence reveal additional tracks that correspond to recoil tracks. The observations have been correlated with modelling, and shown to be in qualitative agreement with prevailing descriptions of collision cascades. The results may be relevant to technologies that are based on detection and characterization of single energetic ions. In particular, the direct visualization of the collision cascade may allow more accurate estimates of the actual interaction volume, which in turn will permit more precise assessment of dose distribution of α-emitting radionuclides used for targeted radiotherapy. The results could also be relevant to other diagnostic or process technologies based on interaction of energetic ions with matter.

  14. Accurate dosimetry in scanning transmission X-ray microscopes via the cross-linking threshold dose of poly(methyl methacrylate).

    PubMed

    Leontowich, Adam F G; Hitchcock, Adam P; Tyliszczak, Tolek; Weigand, Markus; Wang, Jian; Karunakaran, Chithra

    2012-11-01

    The sensitivity of various polymers to radiation damage by soft X-rays has been measured previously with scanning transmission X-ray microscopes. However, the critical dose values reported by different groups for the same material differ by more than 100%. Possible sources of this variability are investigated here for poly(methyl methacrylate) (PMMA) using controlled exposure to monochromatic soft X-rays at 300 eV. Radiation sensitivity, judged by several different criteria, was evaluated as a function of dose rate, pre-exposure thermal treatments and X-ray polarization. Both the measured critical dose and the dose required to initiate negative mode (cross-linking) were observed to depend only on dose, not the other factors explored. A method of determining detector efficiency from the dose required to initiate negative mode in PMMA is outlined. This method was applied to many of the soft X-ray STXMs presently operating to derive the efficiencies of their transmitted X-ray detectors in the C 1s absorption-edge region.

  15. Highly conductive poly(methyl methacrylate) (PMMA)-reduced graphene oxide composite prepared by self-assembly of PMMA latex and graphene oxide through electrostatic interaction.

    PubMed

    Pham, Viet Hung; Dang, Thanh Truong; Hur, Seung Hyun; Kim, Eui Jung; Chung, Jin Suk

    2012-05-01

    We report a simple, environmentally friendly approach for preparing highly conductive poly(methyl methacrylate)-reduced graphene oxide (PMMA-RGO) composites by self-assembly of positively charged PMMA latex particles and negatively charged graphene oxide sheets through electrostatic interactions, followed by hydrazine reduction. The PMMA latex was prepared by surfactant-free emulsion polymerization using a cationic free radical initiator, which created the positive charges on the surface of the PMMA particle. By mixing PMMA latex with a graphene oxide dispersion, positively charged PMMA particles easily assembled with negatively charged graphene oxide sheets through electrostatic interaction. The obtained PMMA-RGO exhibited excellent electrical properties with a percolation threshold as low as 0.16 vol % and an electrical conductivity of 64 S/m at only 2.7 vol %. Moreover, the thermomechanical properties of PMMA-RGO were also significantly improved. The storage modulus of PMMA-RGO increased by about 30% at 4.0 wt % RGO at room temperature while the glass transition temperature of PMMA-RGO increased 15 °C at only 0.5 wt % RGO.

  16. Straightforward fabrication of stable white LEDs by embedding of inorganic UV-LEDs into bulk polymerized polymethyl-methacrylate doped with organic dyes

    NASA Astrophysics Data System (ADS)

    di Martino, Daniela; Beverina, Luca; Sassi, Mauro; Brovelli, Sergio; Tubino, Riccardo; Meinardi, Francesco

    2014-03-01

    Stable white-emitting down-converted LEDs are straightforwardly prepared by bulk polymerization of an organic dye doped polymethyl-methacrylate (PMMA) shell directly on top of a highly efficient commercial blue-emitting InGaN LED. Our optimized polymerization procedure allows for extending the form factor of achievable luminescence converter (LUCO) material beyond the conventional thin film form and to directly produce devices with light bulb design. The selected organic dyes, the blue-emitting Coumarin 30 and a red-emitting diketopyrrolopyrrole derivative, exhibit high compatibility with the free radical polymerization reaction of the PMMA matrix and ensure high stability of the final hybrid device. The control of both the thickness of the PMMA shell and the concentration of the dopant dyes allow for fine tuning of the emission color of the LUCO LED and to obtain white light with CIE chromatic coordinates x = 0.32 and y = 0.33, with rendering index as high as 80. This simple and versatile procedure is not dye-exclusive and is therefore extendable to other molecular systems for color-tunable efficient solid-state lighting sources.

  17. Effect of temperature on segmental mobility is reduced, but not eliminated during constant strain rate deformation of poly(methyl methacrylate) glasses

    NASA Astrophysics Data System (ADS)

    Hebert, Kelly; Bending, Benjamin; Ricci, Josh; Ediger, M. D.

    2015-03-01

    Deformation of polymer glasses is typically nonlinear and not understood at a molecular level. During deformation, segmental motion in polymer glasses can be accelerated by over a factor of 1000. While temperature has a big impact on the segmental motion of polymer glasses in the absence of deformation, some workers suggest that segmental mobility in polymer glasses undergoing deformation should be independent of temperature. We have measured segmental mobility in poly(methyl methacrylate) glasses during constant strain rate deformation at four different temperatures using a probe reorientation method. We find that during deformation, the dependence of segmental mobility on temperature is significantly reduced, though not eliminated. This is in qualitative agreement with the work of Chen and Schweizer. We also find that the KWW β parameter increases during deformation, indicating a narrower distribution of segmental relaxation times. At a given strain rate, this increase of the KWW β parameter is larger at lower temperature. We thank the National Science Foundation (DMR-1404614) for support of this research.

  18. Straightforward fabrication of stable white LEDs by embedding of inorganic UV-LEDs into bulk polymerized polymethyl-methacrylate doped with organic dyes.

    PubMed

    Di Martino, Daniela; Beverina, Luca; Sassi, Mauro; Brovelli, Sergio; Tubino, Riccardo; Meinardi, Francesco

    2014-03-18

    Stable white-emitting down-converted LEDs are straightforwardly prepared by bulk polymerization of an organic dye doped polymethyl-methacrylate (PMMA) shell directly on top of a highly efficient commercial blue-emitting InGaN LED. Our optimized polymerization procedure allows for extending the form factor of achievable luminescence converter (LUCO) material beyond the conventional thin film form and to directly produce devices with light bulb design. The selected organic dyes, the blue-emitting Coumarin 30 and a red-emitting diketopyrrolopyrrole derivative, exhibit high compatibility with the free radical polymerization reaction of the PMMA matrix and ensure high stability of the final hybrid device. The control of both the thickness of the PMMA shell and the concentration of the dopant dyes allow for fine tuning of the emission color of the LUCO LED and to obtain white light with CIE chromatic coordinates x = 0.32 and y = 0.33, with rendering index as high as 80. This simple and versatile procedure is not dye-exclusive and is therefore extendable to other molecular systems for color-tunable efficient solid-state lighting sources.

  19. Atmospheric-pressure DBD plasma-assisted surface modification of polymethyl methacrylate: A study on cell growth/proliferation and antibacterial properties

    NASA Astrophysics Data System (ADS)

    Rezaei, Fatemeh; Shokri, Babak; Sharifian, M.

    2016-01-01

    This paper reports polymethyl methacrylate (PMMA) surface modification by atmospheric-pressure oxygen dielectric barrier discharge (DBD) plasma to improve its biocompatibility and antibacterial effects. The role of plasma system parameters, such as electrode gap, treatment time and applied voltage, on the surface characteristics and biological responses was studied. The surface characteristics of PMMA films before and after the plasma treatments were analyzed by water contact angle (WCA) goniometry, atomic force microscopy (AFM) and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). Also, acid-base approach was used for evaluation of surface free energy (SFE) and its components. Stability of plasma treatment or aging effect was examined by repeating water contact angle measurements in a period of 9 days after treatment. Moreover, the antibacterial properties of samples were investigated by bacterial adhesion assay against Escherichia coli. Additionally, all samples were tested for the biocompatibility by cell viability assay of mouse embryonic fibroblast. WCA measurements indicated that the surface wettability of PMMA films was improved by increasing surface free energy via oxygen DBD plasma treatments. AFM measurement revealed that surface roughness was slightly increased after treatments, and ATR-FTIR analysis showed that more polar groups were introduced on the plasma-treated PMMA film surface. The results also demonstrated an enhancement of antibacterial performance of the modified surfaces. Furthermore, it was observed that plasma-treated samples exhibited significantly better biocompatibility, comparing to the pristine one.

  20. Outcome of in-the-bag implanted square-edge polymethyl methacrylate intraocular lenses with and without primary posterior capsulotomy in pediatric traumatic cataract

    PubMed Central

    Verma, Neelam; Ram, Jagat; Sukhija, Jaspreet; Pandav, Surinder S.; Gupta, Amit

    2011-01-01

    Purpose: To study the outcome of in-the-bag implanted square-edge polymethyl methacrylate (PMMA) intraocular lenses (IOL) with and without primary posterior capsulotomy in pediatric traumatic cataract. Materials and Methods: The study was undertaken in a tertiary care center. Thirty eyes of 30 children ranging in age from 4 to 16 years with traumatic cataract which underwent cataract extraction with capsular bag implantation of IOL were prospectively evaluated. Group A included 15 eyes of 15 children where primary posterior capsulotomy (PPC) and anterior vitrectomy with capsular bag implantation of square-edge PMMA IOL (Aurolab SQ3602, Madurai, Tamil Nadu, India) was performed. Group B comprised 15 eyes of 15 children in which the posterior capsule was left intact. Postoperative visual acuity, visual axis opacification (VAO) and possible complications were analyzed. Results: Best corrected visual acuity (BCVA) of 20/40 or better was achieved in 12 of 15 eyes in both groups. Amblyopia was the cause of no improvement in visual acuity in the remaining eyes. Visual axis opacification was significantly high in Group B as compared to Group A (P=0.001). Postoperative fibrinous uveitis occurred in most of the eyes in both groups. Pupillary capture was observed in one eye in each group. Conclusion: Primary posterior capsulotomy and anterior vitrectomy with capsular bag implantation of square-edge PMMA significantly helps to maintain a clear visual axis in children with traumatic cataract. PMID:21836338

  1. Online transient isotachophoresis concentration by the pseudo-terminating electrolyte buffer for the separation of DNA-aptamer and its thrombin complex in poly(methyl methacrylate) microchip.

    PubMed

    Wang, Jun; Zhang, Yong; Okamoto, Yukihiro; Kaji, Noritada; Tokeshi, Manabu; Baba, Yoshinobu

    2011-03-21

    Online automatic transient isotachophoresis concentration of DNA-aptamer and its thrombin complex by using one kind of pseudo-terminating electrolyte buffer in a cross-channel poly(methyl methacrylate) microchip is reported. Sample injection, transient concentration and separation were done continuously and controlled by a sequential voltage switching program, time-consuming steps and complicated chip design were not required. Peak resolution between DNA-aptamer and its thrombin complex was influenced by this novel pseudo-terminating electrolyte buffer, which was prepared by the addition of chemical component with slow mobility into the same buffer as leading electrolyte buffer. 1100-fold signal enhancement of thrombin complex was achieved by this transient isotachophoresis on a standard cross-form microchip. The concentration effect or standing time of transient isotachophoresis was proved to be influenced by the concentration of leading electrolyte ion and the concentration of pseudo-terminating electrolyte buffer ion (glycine). The transient concentration was followed by on-chip nondenaturing gel electrophoresis in methylcellulose solution for the size-based separation. The detection limit, taken as the lowest thrombin concentration at threefold S/N, was determined to be 0.5 amol in mass by this method. This journal is © The Royal Society of Chemistry 2011

  2. Solid phase extraction of DNA from biological samples in a post-based, high surface area poly(methyl methacrylate) (PMMA) microdevice.

    PubMed

    Reedy, Carmen R; Price, Carol W; Sniegowski, Jeff; Ferrance, Jerome P; Begley, Matthew; Landers, James P

    2011-05-07

    This work describes the performance of poly(methyl methacrylate) (PMMA) microfluidic DNA purification devices with embedded microfabricated posts, functionalized with chitosan. PMMA is attractive as a substrate for creating high surface area (SA) posts for DNA capture because X-ray lithography can be exploited for extremely reproducible fabrication of high SA structures. However, this advantage is offset by the delicate nature of the posts when attempting bonding to create a closed system, and by the challenge of functionalizing the PMMA surface with a group that invokes DNA binding. Methods are described for covalent functionalization of the post surfaces with chitosan that binds DNA in a pH-dependent manner, as well as for bonding methods that avoid damaging the underlying post structure. A number of geometric posts designs are explored, with the goal of identifying post structures that provide the requisite surface area without a concurrent rise in fluidic resistance that promotes device failure. Initial proof-of-principle is shown by recovery of prepurified human genomic DNA (hgDNA), with real-world utility illustrated by purifying hgDNA from whole blood and demonstrating it to be PCR-amplifiable.

  3. Experimental and Numerical Study on Effect of Sample Orientation on Auto-Ignition and Piloted Ignition of Poly(methyl methacrylate).

    PubMed

    Peng, Fei; Zhou, Xiao-Dong; Zhao, Kun; Wu, Zhi-Bo; Yang, Li-Zhong

    2015-07-02

    In this work, the effect of seven different sample orientations from 0° to 90° on pilot and non-pilot ignition of PMMA (poly(methyl methacrylate)) exposed to radiation has been studied with experimental and numerical methods. Some new and significant conclusions are drawn from the study, including a U-shape curve of ignition time and critical mass flux as sample angle increases for pilot ignition conditions. However, in auto-ignition, the ignition time and critical mass flux increases with sample angle α. Furthermore, a computational fluid dynamic model have been built based on the Fire Dynamics Simulator (FDS6) code to investigate the mechanisms controlling the dependence on sample orientation of the ignition of PMMA under external radiant heating. The results of theoretical analysis and modeling results indicate the decrease of total incident heat flux at sample surface plays the dominant role during the ignition processes of auto-ignition, but the volatiles gas flow has greater influence for piloted ignition conditions.

  4. An investigation of self-reinforced poly(methyl methacrylate) denture base acrylic resin using scanning electron and atomic force microscopy.

    PubMed

    Jagger, D C; Harrison, A; Jandt, K D

    2000-01-01

    The aim of this study was to examine the interfacial region of poly(methyl methacrylate) (PMMA) reinforced with untreated and surface-treated PMMA fibers in both chopped and continuous form using scanning electron and atomic force microscopy. Acrylic resin specimens incorporating untreated and surface-treated (with butadiene styrene latex emulsion) PMMA fibers were examined using a scanning electron microscope and an atomic force microscope. There was evidence of random arrangement of untreated and surface-treated chopped fibers throughout specimens with areas of dense fiber aggregation and other areas containing few or no fibers. For the untreated and surface-treated fibers in continuous forms (a single and 2 unidirectional layers), there was evidence of fiber displacement and buckling, together with variation in interfiber spacing. For the specimens containing surface-treated continuous fibers in a cross-ply arrangement that had demonstrated a substantial improvement in the modulus of rupture, there was no evidence of fiber buckling, and the layer of butadiene styrene was consistently thin and even in comparison to weaker specimens. The thickness of the rubber layer and the fiber arrangement (in terms of fiber displacement and interfiber spacing) may be important factors in the success of the reinforcement.

  5. Facile Synthesis of Thick Films of Poly(methyl methacrylate), Poly(styrene), and Poly(vinyl pyridine) from Au Surfaces

    PubMed Central

    Saha, Sampa

    2011-01-01

    Atom transfer radical polymerization (ATRP) is commonly used to grow polymer brushes from Au surfaces, but the resulting film thicknesses are usually significantly less than with ATRP from SiO2 substrates. On Au, growth of poly(methyl methacrylate) (PMMA) blocks from poly(tert-butyl acrylate) brushes occurs more rapidly than growth of PMMA from initiator monolayers, suggesting that the disparity between growth rates from Au and SiO2 stems from the Au surface. Radical quenching by electron transfer from Au is probably not the termination mechanism because polymerization from thin, cross-linked initiators gives film thicknesses that are essentially the same as the thicknesses of films grown from SiO2 under the same polymerization conditions. However, this result is consistent with termination through desorption of thiols from non-cross-linked films, and reaction of these thiols with growing polymer chains. The enhanced stability of cross-linked initiators allows ATRP at temperatures up to ~100 °C and enables the growth of thick films of PMMA (350 nm), polystyrene (120 nm) and poly(vinyl pyridine) (200 nm) from Au surfaces in 1 hour. At temperatures >100 °C, the polymer brush layers delaminate as large area films. PMID:21728374

  6. Preparation and characterization of lithium ion conducting polymer electrolytes based on a blend of poly(vinylidene fluoride-co-hexafluoropropylene) and poly(methyl methacrylate).

    PubMed

    Gebreyesus, Merhawi Abreha; Purushotham, Y; Kumar, J Siva

    2016-07-01

    Ion conducting polymer electrolytes composed of poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP), poly(methyl methacrylate) (PMMA) and lithium triflate (LiTf) were prepared using the solution casting method. Structural change and complex formation in the blend electrolyte systems were confirmed from the X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) studies. Thermal properties of the samples were investigated by the differential scanning calorimetry (DSC) technique. The ionic conductivity of these polymer electrolytes was studied by impedance spectroscopy at various temperatures ranging from 303-393 K. The results reveal that the ionic conductivity of the polymer blend electrolytes depends on the PVdF-HFP:PMMA composition as well as the temperature. Maximum room temperature conductivity of [Formula: see text] S cm(-1) was achieved with 22.5 wt.% PMMA. The blending of PVdF-HFP with PMMA improved the thermal stability and ionic conductivity of the polymer electrolyte. Estimated transference numbers suggest the charge transport is predominantly ionic.

  7. Alpha and recoil track detection in poly(methyl methacrylate) (PMMA)—Towards a method for in vitro assessment of radiopharmaceuticals internalized in cancer cells

    NASA Astrophysics Data System (ADS)

    Myhra, S.; Falzone, N.; Chakalova, R.

    2014-03-01

    A method for detection and characterization of single MeV α-particle and recoil tracks in PMMA photoresist by atomic force microscopy (AFM) analysis has been demonstrated. The energy deposition along the track is shown to lead to a latent pattern in the resist due to contrast reversal. It has been shown that the pattern, consisting of conical spikes, can be developed by conventional processing as a result of the dissolution rate of poly(methyl methacrylate) (PMMA) being greater than that for the modified material in the cylindrical volume of the track core. The spikes can be imaged and counted by routine AFM analysis. Investigations by angular-resolved near-grazing incidence reveal additional tracks that correspond to recoil tracks. The observations have been correlated with modelling, and shown to be in qualitative agreement with prevailing descriptions of collision cascades. The results may be relevant to technologies that are based on detection and characterization of single energetic ions. In particular, the direct visualization of the collision cascade may allow more accurate estimates of the actual interaction volume, which in turn will permit more precise assessment of dose distribution of α-emitting radionuclides used for targeted radiotherapy. The results could also be relevant to other diagnostic or process technologies based on interaction of energetic ions with matter.

  8. On-demand degrafting and the study of molecular weight and grafting density of poly(methyl methacrylate) brushes on flat silica substrates.

    PubMed

    Patil, Rohan R; Turgman-Cohen, Salomon; Šrogl, Jiří; Kiserow, Douglas; Genzer, Jan

    2015-03-03

    We report on degrafting of surface-anchored poly(methyl methacrylate) (PMMA) brushes from flat silica-based substrates using tetrabutylammonium fluoride (TBAF) and determining their molecular weight distribution (MWD) using size exclusion chromatography (SEC). The grafted PMMA layer was synthesized using surface-initiated atom transfer radical polymerization (SI-ATRP) of MMA for polymerization times ranging from 6 to 24 h. X-ray photoelectron spectroscopy, ellipsometry, and time-of-flight secondary ion mass spectrometry were employed in tandem to characterize the degrafting process. The SEC eluograms were fit to various polymer distributions, namely Zimm-Schulz, ATRP in continuous stirred tank reactor, Wesslau, Schulz-Flory, and Smith et al. The ATRP model gives the best fit to the experimental data. The dry PMMA brush thickness and the number-average molecular weight (obtained from the MWD) suggest that the grafting density of the PMMA grafts is independent of polymerization time, indicating well-controlled/living growth of MMA. The observed polydispersity index (PDI) was higher than that generally observed in bulk grown polymers under similar conditions, indicating an effect due to chain confinement and crowding. We detect small but noticeable dependence of the polymer brush grafting density on the inhibitor/catalyst ratio. Higher inhibitor/catalyst ratio offers better control with lower early terminations, which results in a small increase in the apparent grafting density of the chains.

  9. An investigation, over the range of conditions occurring in radiation processing plants, of the performance of routine dosimeters of the type based on polymethyl methacrylate, part 2

    NASA Astrophysics Data System (ADS)

    Barett, J. H.; Sharpe, P. H. G.; Stuart, I. P.

    1981-01-01

    Polymethyl methacrylate (Perspex) in the form of thin strips is used as a dosimeter in the 5 to 50kGy range. Two distinct types of systems were developed, both of which depend on a radiation induced change in optical absorption as the means of assessing absorbed dose. Perspex HX(+) is, in principle, the simpler of the systems. Polymerization of a monomer without additives is initiated by benzoyl peroxide and is continued until a specified (low) amount of residual monomer remains. On irradiation degradation products of the polymer build up in the matrix and optical density measurement in the 300 to 320 nm region allows their concentration to be determined. Red 4034 Perspex typifies the second type of system although other formulations were developed. Dye molecules are incorporated into the polymer during manufacture and on irradiation polymer radicals react with dye molecules to produce optical absorption in the visible region of the spectrum (600 to 650 nm in the case of Red 4034).

  10. One-Pot Synthesis of Hydrophilic Superparamagnetic Fe3O4/Poly(methyl methacrylate-acrylic acid) Composite Nanoparticles with High Magnetization.

    PubMed

    Ma, Shaohua; Lan, Fang; Yang, Qi; Xie, Liqin; Wu, Yao; Gu, Zhongwei

    2015-01-01

    Uniform superparamagnetic Fe3O4/poly(methyl methacrylate-acrylic acid) (P(MMA-AA)) composite nanoparticles with high saturation magnetization and good hydrophilicity were successfully and directly synthesized via a facile one-pot miniemulsion polymerization approach. The mixture of the ferrofluids, MMA and AA monomers, surfactants and initiator was co-sonicated and emulsified to prepare stable miniemulsion for polymerization. The as-prepared products were characterized by SEM, TEM, FT-IR, XRD, TGA and VSM. The results of SEM indicated that the morphology of the Fe3O4/P(MMA-AA) composite nanoparticles all assumed near spherical geometry with diameters about 60 nm, 60 nm, and 100 nm respectively corresponding to the weight ratios of Fe3O4 to MMA and AA at 1:8, 1:4, and 1:2. The TEM images implied that the Fe3O4/P(MMA-AA) composite nanoparticles showed a perfect core-shell structure with a polymeric shell of about 2 nm thickness and a core encapsulating uniform and close packed Fe3O4 nanoparticles. TGA and VSM showed that the Fe3O4/P(MMA-AA) composite nanoparticles with a maximum saturation magnetization up to 45 emu g(-1) corresponding to the magnetite content of 78% exhibited superparamagntism. The hydrophilic modification and the high saturation magnetization impart a promising potential for biomedical applications to the as-synthesized composite nanoparticles.

  11. Dynamics of a poly(ethylene oxide) tracer in a poly(methyl methacrylate) matrix: remarkable decoupling of local and global motions.

    PubMed

    Haley, Jeffrey C; Lodge, Timothy P

    2005-06-15

    The tracer diffusion coefficient of unentangled poly(ethylene oxide) (PEO, M=1000 gmol) in a matrix of poly(methyl methacrylate) (PMMA, M=10 000 gmol) has been measured over a temperature range from 125 to 220 degrees C with forced Rayleigh scattering. The dynamic viscosities of blends of two different high molecular weight PEO tracers (M=440 000 and 900 000 gmol) in the same PMMA matrix were also measured at temperatures ranging from 160 to 220 degrees C; failure of time-temperature superposition was observed for these systems. The monomeric friction factors for the PEO tracers were extracted from the diffusion coefficients and the rheological relaxation times using the Rouse model. The friction factors determined by diffusion and rheology were in good agreement, even though the molecular weights of the tracers differed by about three orders of magnitude. The PEO monomeric friction factors were compared with literature data for PEO segmental relaxation times measured directly with NMR. The monomeric friction factors of the PEO tracer in the PMMA matrix were found to be from two to six orders of magnitude greater than anticipated based on direct measurements of segmental dynamics. Additionally, the PEO tracer terminal dynamics are a much stronger function of temperature than the corresponding PEO segmental dynamics. These results indicate that the fastest PEO Rouse mode, inferred from diffusion and rheology, is completely separated from the bond reorientation of PEO detected by NMR. This result is unlike other blend systems in which global and local motions have been compared.

  12. Novel polymer monolith microextraction using a poly-(methyl methacrylate-co-ethylene dimethacrylate) monolith and its application to the determination of polychlorinated biphenyls in water samples.

    PubMed

    Liu, Lu; Cheng, Jing; Matsadiq, Guzalnur; Li, Jun-Kai

    2011-05-01

    A novel and simple method based on polymer monolith microextraction (PMME) coupled to gas chromatography with electron-capture detection (GC-ECD) was developed for the determination of six polychlorinated biphenyls (PCBs) residues in water samples. The proposed method used poly-(methyl methacrylate-co-ethylene dimethacrylate) (MMA-co-EDMA) monolith as extraction media. Several factors affecting experiments such as sample flow rate, sample volume, the type of eluent, eluent volume, eluent flow rate, effect of salt addition and carry over effect were investigated and optimized systematically. The limits of detection (LODs) for six PCBs were 0.028-0.043 ng mL(-1) in water samples. The intra-day and inter-day precisions (R.S.D.) were less than 9.2% and 9.6%, respectively. The proposed method was successfully applied to the determination of six PCBs in tap water, lake water and industrial waste water and the trueness has been evaluated by recovery experiments. The obtained relative recoveries were in the range of 63.3-105.6%.

  13. Graphene functionalized with poly(vinyl alcohol) as a Pickering stabilizer for suspension polymerization of poly(methyl methacrylate).

    PubMed

    Erdenedelger, Gansukh; Dao, Trung Dung; Jeong, Han Mo

    2016-08-15

    Two types of thermally reduced graphenes (TRGs) having different lateral sizes were non-covalently modified with poly(vinyl alcohol) to endow water-dispersibility. The modified TRGs were examined as Pickering stabilizers for the suspension polymerization of methyl methacrylate (MMA). They were effective graphene-based Pickering stabilizers for the system with almost all of the polymerized composite microparticles having a regular spherical shape. The particle size of the composite microparticles was tunable by the size or the amount of modified TRG used as stabilizer. The almost perfect core-shell structure of the composite microparticles effectively enhanced the thermal stability of the core PMMA. In addition, when the core-shell microparticles were compression molded into a monolith, the obtained composite exhibited an ultra-low percolation threshold of electrical conductivity of around 0.04vol%.

  14. Use of hydrophobically modified inulin for the preparation of polymethyl methacrylate/polybutyl acrylate latex particles using a semicontinuous reactor.

    PubMed

    Obiols-Rabasa, M; Ramos, J; Forcada, J; Esquena, J; Solans, C; Levecke, B; Booten, K; Tadros, Tharwat F

    2010-06-01

    The seeded semicontinuous emulsion copolymerization of methyl methacrylate (MMA) and butyl acrylate (BuA) stabilized with a graft polymeric surfactant based on inulin, INUTEC SP1, as well as its mixture with sodium lauryl sulfate (SLS) is described. The mixture of SLS and Brij58 (alcohol ethoxylated) and the mixture of SLS and Pluronic P85 (block copolymer PEO-PPO-PEO) are also used as surfactant systems. The addition of methacrylic acid (MAA) or acrylic acid (AA) as comonomers is also studied. Previous results proved this inulin-derivative surfactant, INUTEC SP1, to be very effective on synthesizing latexes using a very low surfactant concentration. The kinetic features of the emulsion polymerization (instantaneous conversion and total conversion) were gravimetrically determined along the reactions. Latex dispersions were characterized by photon correlation spectroscopy (PCS) and transmission electron microscopy (TEM) to obtain the average particle size, the particle size distributions (PSDs) as well as the polydispersity index (PdI). The stability was determined by turbidimetry measurements and expressed in terms of critical coagulation concentration. The results showed that the use of the graft polymeric surfactant allowed obtaining highly stable nanoparticles, at low surfactant concentrations and high solid contents (up to 37 wt %). This is an improvement with respect to previous works, in which a mixture of the graft polymeric surfactant with another surfactant was required to obtain stable nanoparticles with low polydispersity, at high solid content. In the present work, low polydispersity was achieved using INUTEC as the only emulsifier, which was related to the absence of secondary nucleations. When a mixture of INUTEC SP1 and SLS is used, a wider PSD is obtained due to secondary nucleations. Replacing INUTEC SP1 by other nonionic surfactants such as Brij58 or Pluronic P85 leads to an increase of average particle size and wider PSD.

  15. Significant melting point depression of two-dimensional folded-chain crystals of isotactic poly(methyl methacrylate)s observed by high-resolution in situ atomic force microscopy.

    PubMed

    Takanashi, Yuma; Kumaki, Jiro

    2013-05-09

    The properties of polymer ultrathin films are a subject of intense study from both practical and academic viewpoints. Previously, we found that upon compression, an isotactic poly(methyl methacrylate) (it-PMMA) Langmuir monolayer crystallized to form a two-dimensional (2D) folded-chain crystal, and the molecular image of the crystal with chain folding and tie chains was clearly visualized by atomic force microscopy (AFM). In the present study, the melting behaviors of the it-PMMA 2D crystals were successfully observed in situ by high-temperature AFM at the molecular lever for the first time. The chain-chain distances (~1.2 nm) of the crystals were clearly resolved even at temperatures close to the melting temperatures (Tm) of the 2D crystals. We found that the Tm of the 2D crystals was at most 90 °C lower than the bulk crystals. The Tm depression strongly depended on the molecular weight, while the molecular weight dependence of the bulk Tm was negligible in the molecular weight regime studied. The Tm depression also depended on the substrates, a slightly larger depression being observed on a sapphire substrate compared to that on a mica. The large Tm depressions of the 2D crystals could not be explained by a simple Thomson-Gibbs argument, theoretical developments are necessary to understand the melting of the 2D crystals.

  16. Surface Molecularly Imprinted Polymer of Chitosan Grafted Poly(methyl methacrylate) for 5-Fluorouracil and Controlled Release

    PubMed Central

    Zheng, Xue-Fang; Lian, Qi; Yang, Hua; Wang, Xiuping

    2016-01-01

    The molecular surface imprinted graft copolymer of chitosan with methyl methacrylate (MIP-CS-g-PMMA) were prepared by free radical polymerization with 5-fluorouracil (5-FU) as the template molecule using initiator of ammonium persulfate as adsorption system. MIPs were characterized by FTIR, X-ray diffraction, thermo-gravimetric analysis, 1H NMR and SEM. The mechanism of graft copolymerization and factors affected graft reaction were studied in details, and the optimum reaction conditions (to the highest %G and %E as the standard) were obtained at [MMA] 1.2 mol/L, [Chitosan] 16.67 mol/L, [initiator] 0.0062 mol/L, temperature 60 °C and reaction time 7 h. MIPs exhibited high recognition selectivity and excellent combining affinity to template molecular. The in vitro release of the 5-FU was highly pH-dependent and time delayed. The release behavior showed that the drugs did not release in simulated gastric fluid (pH = 1.0), and the drug release was small in the simulated small intestinal fluid (pH = 6.8), and drug abrupt release will be produced in the simulated colon fluid (pH = 7.4), indicating excellent colon-specific drug delivery behavior. PMID:26892676

  17. Sidechain Dynamics Explain Dissimilar Strength of Nanoconfinement Effect in Polystyrene and Poly(methyl methacrylate) Free Standing Thin Films

    NASA Astrophysics Data System (ADS)

    Hsu, David; Xia, Wenjie; Song, Jake; Keten, Sinan

    Despite substantially similar bulk glass transition temperature (Tg) and other bulk properties, polystyrene (PS) and poly(methyl-methacrylate) (PMMA) exhibit characteristically different Tg depression in the free-standing ultrathin film configuration. The mechanism for this disparate Tg-nanoconfinement effect due to the free surfaces has not been fully explained. Here we utilize recently established chemically specific coarse grain (CG) models to qualitatively reproduce contrasting thickness dependent Tg and length scale of enhanced chain relaxation gradient in the interfacial layer. Vibrational mode analysis is utilized to uncover a relationship between the amplitude and frequency of sidechain fluctuations of reduced order models and the degree of Tg-nanoconfinement. By systematic variation of the distribution of mass in the sidechain versus the backbone, we demonstrate inertia-driven differences in sidechain fluctuations and Tg-nanoconfinement in the CG model. We hypothesize that mass distribution and sidechain flexibility are governing factors causing PS and PMMA free surface effect differences and also provide insight into broader nanoconfinement phenomena from past experiments. D.H., W.X., J.S., and S.K. acknowledge support by the University Partnership Initiative between Northwestern University and The Dow Chemical Company.

  18. Surface Molecularly Imprinted Polymer of Chitosan Grafted Poly(methyl methacrylate) for 5-Fluorouracil and Controlled Release.

    PubMed

    Zheng, Xue-Fang; Lian, Qi; Yang, Hua; Wang, Xiuping

    2016-02-19

    The molecular surface imprinted graft copolymer of chitosan with methyl methacrylate (MIP-CS-g-PMMA) were prepared by free radical polymerization with 5-fluorouracil (5-FU) as the template molecule using initiator of ammonium persulfate as adsorption system. MIPs were characterized by FTIR, X-ray diffraction, thermo-gravimetric analysis, (1)H NMR and SEM. The mechanism of graft copolymerization and factors affected graft reaction were studied in details, and the optimum reaction conditions (to the highest %G and %E as the standard) were obtained at [MMA] 1.2 mol/L, [Chitosan] 16.67 mol/L, [initiator] 0.0062 mol/L, temperature 60 °C and reaction time 7 h. MIPs exhibited high recognition selectivity and excellent combining affinity to template molecular. The in vitro release of the 5-FU was highly pH-dependent and time delayed. The release behavior showed that the drugs did not release in simulated gastric fluid (pH = 1.0), and the drug release was small in the simulated small intestinal fluid (pH = 6.8), and drug abrupt release will be produced in the simulated colon fluid (pH = 7.4), indicating excellent colon-specific drug delivery behavior.

  19. Interchain coupled chain dynamics of poly(ethylene oxide) in blends with poly(methyl methacrylate): Coupling model analysis

    NASA Astrophysics Data System (ADS)

    Ngai, K. L.; Wang, Li-Min

    2011-11-01

    Quasielastic neutron scattering and molecular dynamics simulation data from poly(ethylene oxide) (PEO)/poly(methyl methacrylate) (PMMA) blends found that for short times the self-dynamics of PEO chain follows the Rouse model, but at longer times past tc = 1-2 ns it becomes slower and departs from the Rouse model in dependences on time, momentum transfer, and temperature. To explain the anomalies, others had proposed the random Rouse model (RRM) in which each monomer has different mobility taken from a broad log-normal distribution. Despite the success of the RRM, Diddens et al. [Eur. Phys. Lett. 95, 56003 (2011)] extracted the distribution of friction coefficients from the MD simulations of a PEO/PMMA blend and found that the distribution is much narrower than expected from the RRM. We propose a simpler alternative explanation of the data by utilizing alone the observed crossover of PEO chain dynamics at tc. The present problem is just a special case of a general property of relaxation in interacting systems, which is the crossover from independent relaxation to coupled many-body relaxation at some tc determined by the interaction potential and intermolecular coupling/constraints. The generality is brought out vividly by pointing out that the crossover also had been observed by neutron scattering from entangled chains relaxation in monodisperse homopolymers, and from the segmental α-relaxation of PEO in blends with PMMA. The properties of all the relaxation processes in connection with the crossover are similar, despite the length scales of the relaxation in these systems are widely different.

  20. Kinetics for the Sequential Infiltration Synthesis of Alumina in Poly(methyl methacrylate): An Infrared Spectroscopic Study

    SciTech Connect

    Biswas, Mahua; Libera, Joseph A.; Darling, Seth B.; Elam, Jeffrey W.

    2015-01-01

    Sequential infiltration synthesis (SIS) is a method for growing inorganic materials within polymers in an atomically controlled fashion. This technique can increase the etch resistance of optical, electron-beam, and block copolymer (BCP) lithography resists and is also a flexible strategy for nanomaterials synthesis. Despite this broad utility, the kinetics of SIS remain poorly understood, and this knowledge gap must be bridged in order to gain firm control over the growth of inorganic materials inside polymer films at a large scale. In this paper, we explore the reaction kinetics for Al2O3 SIS in PMMA using in situ Fourier transform infrared spectroscopy. First, we establish the kinetics for saturation adsorption and desorption of trimethyl aluminum (TMA) in PMMA over a range of PMMA film thicknesses deposited on silicon substrates. These observations guide the selection of TMA dose and purge times during SIS lithography to achieve robust organic/inorganic structures. Next, we examine the effects of TMA desorption on BCP lithography by performing SIS on silicon surfaces coated with polystyrene-block-poly(methyl methacrylate) films. After etching the organic components, the substrates are examined using scanning electron microcopy to evaluate the resulting Al2O3 patterns. Finally, we examine the effects of temperature on Al2O3 SIS in PMMA to elucidate the infiltration kinetics. The insights provided by these measurements will help extend SIS lithography to larger substrate sizes for eventual commercialization and expand our knowledge of precursor-polymer interactions that will benefit the SIS of a wide range of inorganic materials in the future.

  1. Interchain coupled chain dynamics of poly(ethylene oxide) in blends with poly(methyl methacrylate): coupling model analysis.

    PubMed

    Ngai, K L; Wang, Li-Min

    2011-11-21

    Quasielastic neutron scattering and molecular dynamics simulation data from poly(ethylene oxide) (PEO)/poly(methyl methacrylate) (PMMA) blends found that for short times the self-dynamics of PEO chain follows the Rouse model, but at longer times past t(c) = 1-2 ns it becomes slower and departs from the Rouse model in dependences on time, momentum transfer, and temperature. To explain the anomalies, others had proposed the random Rouse model (RRM) in which each monomer has different mobility taken from a broad log-normal distribution. Despite the success of the RRM, Diddens et al. [Eur. Phys. Lett. 95, 56003 (2011)] extracted the distribution of friction coefficients from the MD simulations of a PEO/PMMA blend and found that the distribution is much narrower than expected from the RRM. We propose a simpler alternative explanation of the data by utilizing alone the observed crossover of PEO chain dynamics at t(c). The present problem is just a special case of a general property of relaxation in interacting systems, which is the crossover from independent relaxation to coupled many-body relaxation at some t(c) determined by the interaction potential and intermolecular coupling/constraints. The generality is brought out vividly by pointing out that the crossover also had been observed by neutron scattering from entangled chains relaxation in monodisperse homopolymers, and from the segmental α-relaxation of PEO in blends with PMMA. The properties of all the relaxation processes in connection with the crossover are similar, despite the length scales of the relaxation in these systems are widely different.

  2. Influence of molecular weight of polymethyl(methacrylate) beads on the properties and structure of cross-linked denture base polymer.

    PubMed

    Kawaguchi, Tomohiro; Lassila, Lippo V J; Tokue, Ai; Takahashi, Yutaka; Vallittu, Pekka K

    2011-11-01

    Denture base polymers are multiphase polymers made of polymethyl(methacrylate) (PMMA) beads and monomers containing methylmethacrylate and cross-linking agent. The cross-linking agent is typically dimethacrylate but methacrylated dendrimers have been tested. The aim of this study was to investigate the influence of the molecular weight of the PMMA beads on the mechanical properties of cross-linked denture base polymers. Resin powder with three different molecular weights (Mw 120,000, 350,000, and 996,000) and a commercial autopolymerizing denture base resin (Palapress, Mw 220,000) were tested. The resin monomer liquid was applied with a methylmethacrylate mixture containing 4.6 vol% dendrimer (DD1, VTT Processes). To investigate the flexural properties, the surface microhardness of the PMMA beads, and the thickness of the swollen interpenetrating polymer network (IPN) layer on the PMMA beads, test specimens (3.3×10×65 mm) were fabricated from autopolymerizing resin using a powder/liquid ratio of 10 g/7 ml. The specimens were polymerized in distilled water maintained at 55 °C under 0.4 MPa pressure for 20 min. The flexural strength and flexural modulus (n=8/group) were measured with a three-point bending test at a crosshead speed of 5 mm/min. The Vickers hardness of the area of the polymer with PMMA beads (n=10/group) was tested using a load of 98.12 mN for 5 s. In addition, the thickness of the swollen layer on the PMMA beads was measured (n=10/group). Statistical analysis was performed using a one-way ANOVA and Tukey's test. The flexural strength of the specimens with Mw 220,000 and 350,000 PMMA beads was significantly higher than the strength of specimens with beads having other molecular weights. The flexural modulus of specimens with Mw 120,000 PMMA beads was the lowest. There was no difference in the surface microhardness among all groups. The thickness of the swollen IPN layer on specimens with 120,000 Mw PMMA beads was significantly higher than in the

  3. Dynamics of a poly(ethylene oxide) tracer in a poly(methyl methacrylate) matrix: Remarkable decoupling of local and global motions

    NASA Astrophysics Data System (ADS)

    Haley, Jeffrey C.; Lodge, Timothy P.

    2005-06-01

    The tracer diffusion coefficient of unentangled poly(ethylene oxide) (PEO, M =1000g/mol) in a matrix of poly(methyl methacrylate) (PMMA, M =10000g/mol) has been measured over a temperature range from 125to220°C with forced Rayleigh scattering. The dynamic viscosities of blends of two different high molecular weight PEO tracers (M =440000 and 900000g/mol) in the same PMMA matrix were also measured at temperatures ranging from 160to220°C; failure of time-temperature superposition was observed for these systems. The monomeric friction factors for the PEO tracers were extracted from the diffusion coefficients and the rheological relaxation times using the Rouse model. The friction factors determined by diffusion and rheology were in good agreement, even though the molecular weights of the tracers differed by about three orders of magnitude. The PEO monomeric friction factors were compared with literature data for PEO segmental relaxation times measured directly with NMR. The monomeric friction factors of the PEO tracer in the PMMA matrix were found to be from two to six orders of magnitude greater than anticipated based on direct measurements of segmental dynamics. Additionally, the PEO tracer terminal dynamics are a much stronger function of temperature than the corresponding PEO segmental dynamics. These results indicate that the fastest PEO Rouse mode, inferred from diffusion and rheology, is completely separated from the bond reorientation of PEO detected by NMR. This result is unlike other blend systems in which global and local motions have been compared.

  4. Interactions between polymers and lipid monolayers at the air/water interface: surface behavior of poly(methyl methacrylate)-cholesterol mixed films.

    PubMed

    Miñones Conde, M; Conde, O; Trillo, J M; Miñones, J

    2010-08-26

    The behavior of mixed monolayers of cholesterol and poly(methyl methacrylate) (PMMA) with molecular weights of M(w) = 120,000 g/mol and M(w) = 15,000 g/mol was investigated at the air/water interface using Langmuir and Brewster angle microscopy techniques. From the data of surface pressure (pi)-area (A) isotherms, compressional modulus-surface pressure (C(s)(-1)-pi) curves, and film thickness, complemented with Brewster angle microscopy images, the interaction between the components was analyzed. Regardless of the surface pressure (pi = 10, 20, or 30 mN/m) at which the mean molecular/monomer areas (Am) were calculated, the Am-mole fraction plots (corresponding to X(PMMA) = 0.1, 0.3, 0.5, 0.7, and 0.9) show that all the experimental points obtained are placed on the theoretical straight line calculated according to the additivity rule. This fact, together with the existence of two collapses in the mixed monolayers and with the fact that the surface pressure of the liquid-expanded LE-L'E phase transition of PMMA does not change with the monolayer composition, demonstrates the immiscibility of the film components at the interface. The application of the Crisp phase rule to the phase diagram of PMMA-cholesterol mixed monolayers helps to explain the existence of a biphasic system, regardless of their composition and surface pressure. Besides, Brewster angle microscopy (BAM) images showed the existence of heterogeneous cholesterol domains with high reflectivity immersed in a homogeneous polymer separate phase with low reflectivity.

  5. Dynamics of poly(ethylene oxide) in a blend with poly(methyl methacrylate): A quasielastic neutron scattering and molecular dynamics simulations study

    SciTech Connect

    Genix, A.-C.; Arbe, A.

    2005-09-01

    In this paper, we have addressed the question of the dynamic miscibility in a blend characterized by very different glass-transition temperatures, T{sub g}, for the components: poly(ethylene oxide) and poly(methyl methacrylate) (PEO/PMMA). The combination of quasielastic neutron scattering with isotopic labeling and fully atomistic molecular dynamics simulations has allowed us to selectively investigate the dynamics of the two components in the picosecond--10 nanoseconds scale at temperatures close and above the T{sub g} of the blend. The main focus was on the PEO component, i.e., that of the lowest T{sub g}, but first we have characterized the dynamics of the other component in the blend and of the pure PEO homopolymer as reference. In the region investigated, the dynamics of PMMA in the blend is strongly affected by the {alpha}-methyl rotation; an additional process detected in the experimental window 65 K above the blend-T{sub g} can be identified as the merged {alpha}{beta} process of this component that shows strong deviations from Gaussian behavior. On the other hand, pure PEO displays entropy driven dynamics up to very large momentum transfers. Such kind of motion seems to freeze when the PEO chains are in the blend. There, we have directly observed a very heterogeneous and moreover confined dynamics for the PEO component. The presence of the hardly moving PMMA matrix leads to the creation of little pockets of mobility where PEO can move. The characteristic size of such confined islands of mobility might be estimated to be of {approx_equal}1 nm. These findings are corroborated by the simulation study, which has been an essential support and guide in our data analysis procedure.

  6. Comparison of bacterial adhesion to dental materials of polyethylene terephthalate (PET) and polymethyl methacrylate (PMMA) using atomic force microscopy and scanning electron microscopy.

    PubMed

    Fang, Jie; Wang, Chuanyong; Li, Yifei; Zhao, Zhihe; Mei, Li

    2016-11-01

    The aim of this study was to compare the bacterial adhesion to denture materials of polyethylene terephthalate (PET) and polymethyl methacrylate (PMMA) using atomic force microscopy and scanning electron microscopy. The adhesion forces of living Streptococcus sanguinis and Streptococcus mutans to PET and PMMA were directly measured using atomic force microscopy (AFM) in liquid. Streptococcal biofilms formed on the two material surfaces were investigated and compared using scanning electron microscopy (SEM) and colony-forming units (CFU) counting. Surface roughness and hydrophobicity of PET and PMMA were also measured. The results showed that PET surfaces were significantly smoother and more hydrophilic than PMMA surfaces both with and without a salivary film (p < 0.01). The adhesion forces of S. sanguinis and S. mutans to PET surfaces were significantly stronger than to PMMA surfaces in the absence of a salivary film (p < 0.01). In the presence of a salivary film, the adhesion forces of both bacterial strains to PET and PMMA were significantly decreased (p < 0.01). The adhesion forces of S. mutans to PET surfaces (0.14 nN) were still significantly stronger than to PMMA surfaces (0.09 nN) (p < 0.01). The biofilm formed on PET surfaces was also significantly denser and more than on PMMA surfaces (p < 0.05). In conclusion, the bacterial adhesion to PMMA was significantly less in comparison with PET. PMMA may be preferable for patients who have poor oral hygiene, caries susceptibility, periodontosis, and halitosis. SCANNING 38:665-670, 2016. © 2016 Wiley Periodicals, Inc.

  7. Fabrication of a cyclic olefin copolymer planar waveguide embedded in a multi-channel poly(methyl methacrylate) fluidic chip for evanescence excitation.

    PubMed

    Okagbare, Paul I; Emory, Jason M; Datta, Proyag; Goettert, Jost; Soper, Steven A

    2010-01-07

    The fabrication and characterization of a novel cyclic olefin copolymer (COC) waveguide embedded in a poly(methyl methacrylate), PMMA, fluidic chip configured in a multi-channel format with an integrated monolithic prism for evanescent fluorescence excitation are reported. The fabrication approach allowed the embedded waveguide to be situated orthogonal to a series of fluidic channels within the PMMA wafer to sample fluorescent solutions in these channels using the evanescence properties of the waveguide. Construction of the device was achieved using several fabrication techniques including high precision micromilling, hot embossing and stenciling of a polymer melt to form the waveguide and coupling prism. A waveguide channel was fabricated in the fluidic chip's cover plate, also made from PMMA, and was loaded with a COC solution using a pre-cast poly(dimethylsiloxane), PDMS, stencil containing a prism-shaped recess. The PMMA substrate contained multiple channels (100 microm wide x 30 microm deep with a pitch of 100 microm) that were situated orthogonal to the waveguide to allow penetration of the evanescent field into the sampling solution. The optical properties of the waveguide in terms of its transmission properties and penetration depth of the evanescent field in the adjacent solution were evaluated. Finally, the device was used for laser-induced fluorescence evanescent excitation of a dye solution hydrodynamically flowing through multiple microfluidic channels in the chip and processed using a microscope equipped with a charge-coupled device (CCD) for parallel readout. The device and optical system were able to image 11 channels simultaneously with a limit-of-detection of 7.1 x 10(-20) mol at a signal-to-noise ratio of 2. The waveguide was simple to manufacture and could be scaled to illuminate much higher channel numbers making it appropriate for high-throughput measurements using evanescent excitation.

  8. A novel functionalisation process for glucose oxidase immobilisation in poly(methyl methacrylate) microchannels in a flow system for amperometric determinations.

    PubMed

    Cerqueira, Marcos Rodrigues Facchini; Grasseschi, Daniel; Matos, Renato Camargo; Angnes, Lucio

    2014-08-01

    Different materials like glass, silicon and poly(methyl methacrylate) (PMMA) are being used to immobilise enzymes in microchannels. PMMA shows advantages such as its low price, biocompatibility and attractive mechanical and chemical properties. Despite this, the introduction of reactive functional groups on PMMA is still problematic, either because of the complex chemistry or extended reaction time involved. In this paper, a new methodology was developed to immobilise glucose oxidase (GOx) in PMMA microchannels, with the benefit of a rapid immobilisation process and a very simple route. The new procedure involves only two steps, based on the reaction of 5.0% (w/w) polyethyleneimine (PEI) with PMMA in a dimethyl sulphoxide medium, followed by the immobilisation of glucose oxidase using a solution containing 100U enzymes and 1.0% (v/v) glutaraldehyde. The reactors prepared in this way were evaluated by a flowing system with amperometric detection (+0.60V) based on the oxidation of the H2O2 produced by the reactor. The microreactor proposed here was able to work with high bioconversion and a frequency of 60 samples h(-1), with detection and quantification limits of 0.50 and 1.66µmol L(-1), respectively. Michaelis-Menten parameters (Vmax and KM) were calculated as 449±47.7nmol min(-1) and 7.79±0.98mmol. Statistical evaluations were done to validate the proposed methodology. The content of glucose in natural and commercial coconut water samples was evaluated using the developed method. Comparison with spectrophotometric measurements showed that both methodologies have a very good correlation (tcalculated, 0.05, 4=1.35

  9. Dynamics of poly(ethylene oxide) in a blend with poly(methyl methacrylate): a quasielastic neutron scattering and molecular dynamics simulations study.

    PubMed

    Genix, A-C; Arbe, A; Alvarez, F; Colmenero, J; Willner, L; Richter, D

    2005-09-01

    In this paper, we have addressed the question of the dynamic miscibility in a blend characterized by very different glass-transition temperatures, Tg, for the components: poly(ethylene oxide) and poly(methyl methacrylate) (PEO/PMMA). The combination of quasielastic neutron scattering with isotopic labeling and fully atomistic molecular dynamics simulations has allowed us to selectively investigate the dynamics of the two components in the picosecond-10 nanoseconds scale at temperatures close and above the Tg of the blend. The main focus was on the PEO component, i.e., that of the lowest Tg, but first we have characterized the dynamics of the other component in the blend and of the pure PEO homopolymer as reference. In the region investigated, the dynamics of PMMA in the blend is strongly affected by the alpha-methyl rotation; an additional process detected in the experimental window 65 K above the blend-Tg can be identified as the merged alphabeta process of this component that shows strong deviations from Gaussian behavior. On the other hand, pure PEO displays entropy driven dynamics up to very large momentum transfers. Such kind of motion seems to freeze when the PEO chains are in the blend. There, we have directly observed a very heterogeneous and moreover confined dynamics for the PEO component. The presence of the hardly moving PMMA matrix leads to the creation of little pockets of mobility where PEO can move. The characteristic size of such confined islands of mobility might be estimated to be of approximately 1 nm. These findings are corroborated by the simulation study, which has been an essential support and guide in our data analysis procedure.

  10. Poly(methyl methacrylate-co-ethyl acrylate) latex particles with poly(ethylene glycol) grafts: structure and film formation.

    PubMed

    Schantz, Staffan; Carlsson, Hans T; Andersson, Thomas; Erkselius, Stefan; Larsson, Anders; Karlsson, Ola J

    2007-03-27

    Water-based copolymer dispersions were prepared using methyl methacrylate (MMA), ethyl acrylate (EA) (MMA/EA = 1:2), and a series of nonionic polymerizable surfactants, i.e., "surfmers" based on poly(ethylene glycol)-(meth)acrylates. The latexes were compared with the behavior of a conventionally stabilized (nonionic nonylphenol ethoxylate, NP100 with 84 ethylene oxide units) dispersion with the same MMA-EA composition (PMMAEA). A number of techniques were employed in order to characterize structure, dynamics, and film formation properties: solution/solid-state NMR, dynamic/static light scattering (DLS/SLS), differential scanning calorimetry (DSC), tensile/shear mode dynamic mechanical thermal analysis (DMTA), and atomic force microscopy (AFM). The surfmers were found to be miscible with the MMA-EA copolymer at room temperature, with 46-85 mol % of the reacted surfmer detected at the particle surfaces, and the remaining part buried in the particle bulk. In contrast, the NP100 surfactant formed a separate interphase between the copolymer particles with no mixing detected at room temperature or at 90 degrees C. For a 4.0% dry weight concentration, NP100 phase separated and further crystallized at room temperature over a period of several months. Composition fluctuations related to a limited blockiness on a length scale above approximately 2 nm were detected for PMMAEA particles, whereas the surfmer particles were found to be homogeneous also below this limit. On a particle-particle level, the dispersions tended to form colloidal crystals unless hindered by a broadened particle size distribution or, in the case of PMMAEA, by the action of NP100. Finally, a surface roughness (Rq) master plot was constructed for data above the glass transition temperature (Tg) from Tg + 11 degrees C to Tg + 57 degrees C and compared with the complex shear modulus over 11 frequency decades. Shift factors from the 2 methods obeyed the same Williams-Landel-Ferry (WLF) temperature

  11. A Novel, Minimally-Invasive Approach to Repair Degenerative Disk Disease in an Ovine Model Using Injectable Polymethyl-Methacrylate and Bovine Collagen (PMMA/BC)

    PubMed Central

    Feldman, Erica; Narayan, Anisha; Taylor, William

    2016-01-01

    Background : The natural, inflammatory repair processes of an injured intervertebral degenerative disc can propagate further injury and destruction. While there are many different treatment modalities of the pain related to degenerative disc disease, none are actually reparative in nature. Treatment strategies to repair a degenerative disc without inducing a destructive inflammatory milieu have been elusive.  Purpose: The purpose of this experiment is to discover the feasibility of reconstructing an injured intervertebral disc using an injected, inert polymer as the foundation for endogenous collagen growth. Study Design: In this ovine model of six subjects in total, we introduce a modality where a large inert polymer, polymethyl methacrylate (PMMA), in conjunction bovine collagen (BC) is injected into the intervertebral disc. Following six months of observation, histologic specimens were evaluated macroscopically and microscopically for evidence of a benefit of the injectable PMMA/BC. Methods: We obtained six merino sheep for this study. Concentric injuries were made to four of their lumbar intervertebral discs. Two of those levels were treated with a percutaneous injection of 0.3 cc of PMMA/BC. The remaining lumbar levels were left untreated and were our controls. After six months, all subjects were sacrificed. Their four levels were extracted and were examined macroscopically and microscopically. Results: All subjects tolerated the lumbar injury and percutaneous injection of PMMA/BC well. After the six month interval, all subjects have demonstrated an intact architecture of their lumbar disc height at the macroscopic and microscopic level. Microscopically, there was no evidence of external migration of the PMMA/BC microspheres, nor was there any evidence of an inflammatory response by its presence. Notably, the PMMA/BC microspheres were well-incorporated into the concentric disc tears and had undergone endogenous collagen formation in its environment

  12. Spatiotemporal temperature and density characterization of high-power atmospheric flashover discharges over inert poly(methyl methacrylate) and energetic pentaerythritol tetranitrate dielectric surfaces

    NASA Astrophysics Data System (ADS)

    Tang, V.; Grant, C. D.; McCarrick, J. F.; Zaug, J. M.; Glascoe, E. A.; Wang, H.

    2012-03-01

    A flashover arc source that delivered up to 200 mJ on the 100s-of-ns time-scale to the arc and a user-selected dielectric surface was characterized for studying high-explosive kinetics under plasma conditions. The flashover was driven over thin pentaerythritol tetranitrate (PETN) and poly(methyl methacrylate) (PMMA) dielectric films and the resultant plasma was characterized in detail. Time- and space-resolved temperatures and electron densities of the plasma were obtained using atomic emission spectroscopy. The hydrodynamics of the plasma was captured through fast, visible imaging. Fourier transform infrared spectroscopy (FTIR) was used to characterize the films pre- and post-shot for any chemical alterations. Time-resolved infrared spectroscopy (TRIR) provided PETN depletion data during the plasma discharge. For both types of films, temperatures of 1.6-1.7 eV and electron densities of ˜7-8 × 1017/cm3 ˜570 ns after the start of the discharge were observed with temperatures of 0.6-0.7 eV persisting out to 15 μs. At 1.2 μs, spatial characterization showed flat temperature and density profiles of 1.1-1.3 eV and 2-2.8 × 1017/cm3 for PETN and PMMA films, respectively. Images of the plasma showed an expanding hot kernel starting from radii of ˜0.2 mm at ˜50 ns and reaching ˜1.1 mm at ˜600 ns. The thin films ablated or reacted several hundred nm of material in response to the discharge. First TRIR data showing the in situ reaction or depletion of PETN in response to the flashover arc were successfully obtained, and a 2-μs, 1/e decay constant was measured. Preliminary 1 D simulations compared reasonably well with the experimentally determined plasma radii and temperatures. These results complete the first steps to resolving arc-driven PETN reaction pathways and their associated kinetic rates using in situ spectroscopy techniques.

  13. Spatiotemporal temperature and density characterization of high-power atmospheric flashover discharges over inert poly(methyl methacrylate) and energetic pentaerythritol tetranitrate dielectric surfaces

    SciTech Connect

    Tang, V.; Grant, C. D.; McCarrick, J. F.; Zaug, J. M.; Glascoe, E. A.; Wang, H.

    2012-03-01

    A flashover arc source that delivered up to 200 mJ on the 100s-of-ns time-scale to the arc and a user-selected dielectric surface was characterized for studying high-explosive kinetics under plasma conditions. The flashover was driven over thin pentaerythritol tetranitrate (PETN) and poly(methyl methacrylate) (PMMA) dielectric films and the resultant plasma was characterized in detail. Time- and space-resolved temperatures and electron densities of the plasma were obtained using atomic emission spectroscopy. The hydrodynamics of the plasma was captured through fast, visible imaging. Fourier transform infrared spectroscopy (FTIR) was used to characterize the films pre- and post-shot for any chemical alterations. Time-resolved infrared spectroscopy (TRIR) provided PETN depletion data during the plasma discharge. For both types of films, temperatures of 1.6-1.7 eV and electron densities of {approx}7-8 x 10{sup 17}/cm{sup 3}{approx}570 ns after the start of the discharge were observed with temperatures of 0.6-0.7 eV persisting out to 15 {mu}s. At 1.2 {mu}s, spatial characterization showed flat temperature and density profiles of 1.1-1.3 eV and 2-2.8 x 10{sup 17}/cm{sup 3} for PETN and PMMA films, respectively. Images of the plasma showed an expanding hot kernel starting from radii of {approx}0.2 mm at {approx}50 ns and reaching {approx}1.1 mm at {approx}600 ns. The thin films ablated or reacted several hundred nm of material in response to the discharge. First TRIR data showing the in situ reaction or depletion of PETN in response to the flashover arc were successfully obtained, and a 2-{mu}s, 1/e decay constant was measured. Preliminary 1 D simulations compared reasonably well with the experimentally determined plasma radii and temperatures. These results complete the first steps to resolving arc-driven PETN reaction pathways and their associated kinetic rates using in situ spectroscopy techniques.

  14. Inhibitory effect of zirconium oxide nanoparticles on Candida albicans adhesion to repaired polymethyl methacrylate denture bases and interim removable prostheses: a new approach for denture stomatitis prevention.

    PubMed

    Gad, Mohammed M; Al-Thobity, Ahmad M; Shahin, Suliman Y; Alsaqer, Badar T; Ali, Aiman A

    2017-01-01

    of zirconia nanoparticles to cold-cured acrylic resin is an effective method for reducing Candida adhesion to repaired polymethyl methacrylate (PMMA) denture bases and cold-cured removable prosthesis. Based on the results of the current study, zirconia nanoparticles have an antifungal effect, which could be incorporated in the repair material for repairing denture bases and in PMMA removable prostheses as a possible approach for denture stomatitis prevention.

  15. Toward the treatment for Alzheimer's disease: adsorption is primary mechanism of removing amyloid β protein with hollow-fiber dialyzers of the suitable materials, polysulfone and polymethyl methacrylate.

    PubMed

    Kawaguchi, Kazunori; Saigusa, Akira; Yamada, Shinji; Gotoh, Takehiro; Nakai, Shigeru; Hiki, Yoshiyuki; Hasegawa, Midori; Yuzawa, Yukio; Kitaguchi, Nobuya

    2016-06-01

    The accumulation of amyloid β protein (Aβ) in the brain reflects cognitive impairment in Alzheimer's disease. We hypothesized that the rapid removal of Aβ from the blood by an extracorporeal system may act as a peripheral Aβ sink from the brain. The present study aimed to determine the optimal materials and modality for Aβ removal by hemodialyzers. In a batch analysis, hollow-fiber fragments of polysulfone (PSf) and polymethyl methacrylate (PMMA) showed greater removal efficiency of Aβ than did other materials, such as cellulose-triacetates and ethylene-vinyl alcohol copolymer (PSf:PMMA at 30 min, 98.6 ± 2.4 %:97.8 ± 0.4 % for Aβ1-40 and 96.6 ± 0.3 %:99.0 ± 1.0 % for Aβ1-42). In a modality study, the Aβ solution was applied to PSf dialyzers and circulated in the dialysis and Air-filled adsorption-mode (i.e., the outer space of the hollow fibers was filled with air) or phosphate-buffered saline (PBS)-filled adsorption modes. The Aβ1-40 removal efficiency of the pre/post dialyzer in the Air-filled adsorption-mode was the highest (62.4 ± 12.6 %, p = 0.007). In a flow rate study in the Air-filled adsorption-mode, 200 mL/min showed the highest Aβ1-40 reduction rate of pool solution (97.3 ± 0.8 % at 15 min) compared with 20 mL/min (p = 0.00001) and 50 mL/min (p = 0.00382). PMMA dialyzers showed similar high reduction rates. Thus, the optimal modality for Aβ removal was the adsorption-mode with PSf or PMMA hollow fibers at around 50 mL/min flow rate, which seems to be suitable for clinical use.

  16. Electronic energy migration on different time scales: concentration dependence of the time-resolved anisotropy and fluorescence quenching of Lumogen Red in poly(methyl methacrylate).

    PubMed

    Colby, Kathryn A; Burdett, Jonathan J; Frisbee, Robert F; Zhu, Lingyan; Dillon, Robert J; Bardeen, Christopher J

    2010-03-18

    Electronic energy transfer plays an important role in many types of organic electronic devices. Forster-type theories of exciton diffusion provide a way to calculate diffusion constants and lengths, but their applicability to amorphous polymer systems must be evaluated. In this paper, the perylenediimide dye Lumogen Red in a poly(methyl methacrylate) host matrix is used to test theories of exciton motion over Lumogen Red concentrations (C(LR)'s) ranging from 1 x 10(-4) to 5 x 10(-2) M. Two experimental quantities are measured. First, time-resolved anisotropy decays in films containing only Lumogen Red provide an estimate of the initial energy transfer rate from the photoexcited molecule. Second, the Lumogen Red lifetime decays in mixed systems where the dyes Malachite Green and Rhodamine 700 act as energy acceptors are measured to estimate the diffusive quenching of the exciton. From the anisotropy measurements, it is found that theory accurately predicts both the C(LR)(-2) concentration dependence of the polarization decay time tau(pol), as well as its magnitude to within 30%. The theory also predicts that the diffusive quenching rate is proportional to C(LR)(alpha), where alpha ranges between 1.00 and 1.33. Experimentally, it is found that alpha = 1.1 +/- 0.2 when Malachite Green is used as an acceptor, and alpha = 1.2 +/- 0.2 when Rhodamine 700 is the acceptor. On the basis of the theory that correctly describes the anisotropy data, the exciton diffusion constant is projected to be 4-9 nm(2)/ns. By use of several different analysis methods for the quenching data, the experimental diffusion constant is found to be in the range of 0.32-1.20 nm(2)/ns. Thus the theory successfully describes the early time anisotropy data but fails to quantitatively describe the quenching experiments which are sensitive to motion on longer time scales. The data are consistent with the idea that orientational and energetic disorder leads to a time-dependent exciton migration rate

  17. Novel Molecular Spectroscopic Multimethod Approach for Monitoring Water Absorption/Desorption Kinetics of CAD/CAM Poly(Methyl Methacrylate) Prosthodontics.

    PubMed

    Wiedemair, Verena; Mayr, Sophia; Wimmer, Daniel S; Köck, Eva Maria; Penner, Simon; Kerstan, Andreas; Steinmassl, Patricia-Anca; Dumfahrt, Herbert; Huck, Christian W

    2016-12-12

    Water absorbed to poly(methyl methacrylate) (PMMA)-based CAD/CAM (computer-assisted design/computer-assisted manufacturing) prosthodontics can alter their properties including hardness and stability. In the present contribution, water absorption and desorption kinetics under defined experimental conditions were monitored employing several supplementary and advanced Fourier transform infrared (FT-IR) spectroscopic techniques in combination with multivariate analysis (MVA). In this synergistic vibrational spectroscopic multimethod approach, first a novel near-infrared (NIR) diffuse fiber optic probe reflection spectroscopic method was established for time-resolved analysis of water uptake within seven days under controlled conditions. Near-infrared water absorbance spectra in a wavenumber range between 5288-5100 cm(-1) (combination band) and 5424-5352 cm(-1) (second overtone) were used establishing corresponding calibration and validation models to quantify the amount of water in the milligram range. Therefore, 14 well-defined samples exposed to prior optimized experimental conditions were taken into consideration. The average daily water uptake conducting reference analysis was calculated as 22 mg/day for one week. Additionally, in this study for the first time NIR two-dimensional correlation spectroscopy (2D-COS) was conducted to monitor and interpret the spectral dynamics of water absorption on the prosthodontics in a wavenumber range of 5100-5300 cm(-1) For sensitive time-resolved recording of water desorption, a recently developed high-temperature, high-pressure FT-IR reaction cell with water-free ultra-dry in situ and operando operation was applied. The reaction cell, as well as the sample holder, was fully made of quartz glass, with no hot metal or ceramic parts in the vicinity of the high temperature zone. Applying a temperature gradient in the range of 25-150 ℃, mid-infrared (MIR) 2D-COS was successfully conducted to get insights into the dynamic

  18. The role of adsorption of dodecylethyldimethylammonium bromide and benzyldimethyldodecylammonium bromide surfactants in wetting of polytetrafluoroethylene and poly(methyl methacrylate) surfaces

    NASA Astrophysics Data System (ADS)

    Harkot, Joanna; Jańczuk, Bronisław

    2009-01-01

    The role of adsorption of dodecylethyldimethylammonium bromide (C 12(EDMAB)) and benzyldimethyldodecylammonium bromide (BDDAB) at water-air and polytetrafluoroethylene (PTFE)-water and poly(methyl methacrylate) (PMMA)-water interface, in wetting of PTFE and PMMA surface, was established from the measured values of the contact angle ( θ) of aqueous C 12(EDMAB) and BDDAB solutions in PTFE (PMMA)-solution drop-air system, and from the measured values of the surface tension of aqueous C 12(EDMAB) and BDDAB solutions. Adsorption of C 12(EDMAB) and BDDAB at water-air interface was determined earlier from the Gibbs equation. Adsorption at solid-water interface was deduced from the Lucassen-Reynders equation based on the relationship between adhesion tension ( γLV cos θ) and surface tension ( γLV). The slope of the γLV cos θ- γLV curve was found to be constant and equal to -1, and about -0.3 for PTFE and PMMA surface, respectively (in the case of both surfactant studied: C 12(EDMAB) and BDDAB, and in the whole range of surfactants concentration in solution). It means that the amount of the surfactant adsorbed at the PTFE-water interface, ΓSL, was essentially equal to its amount adsorbed at water-air interface, ΓLV. However, ΓSL at the PMMA-water interface was about three times smaller as compared to that at water-air interface. By extrapolating the linear dependence between γLV cos θ- γLV and dependence between cos θ- γLV and cos θ = 1 we determined the value of the critical surface tension of PTFE and PMMA surface wetting, γc. The obtained values of γc for PTFE surface were equal 23.4 and 23.8 mN/m, 23.1 and 23.2 mN/m for C 12(EDMAB) and BDDAB, respectively and they were higher than the surface tension of PTFE (20.24 mN/m). On the other hand, the obtained values of γc for PMMA surface were equal 31.4 and 30.9 mN/m, 31.7 and 31.3 mN/m for C 12(EDMAB) and BDDAB, respectively and they were smaller than the surface tension of PMMA (39.21 mN/m). Using the

  19. Physicochemical, mechanical, and biological properties of bone cements prepared with functionalized methacrylates.

    PubMed

    Sabino, Marco A; Ajami, Diana; Salih, Vehid; Nazhat, Showan N; Vargas-Coronado, Rossana; Cauich-Rodríguez, Juan V; Ginebra, Ma Pau

    2004-10-01

    Bone cements prepared with methyl methacrylate (MMA) as a base monomer and either methacrylic acid (MAA) or diethyl amino ethyl methacrylate (DEAEMA) as comonomers were characterized in terms of curing behavior, mechanical properties, and their in vitro biocompatibility. The curing time and setting temperature were found to be composition dependent while the residual monomer was not greatly affected by the presence of either acidic or alkaline comonomers in the bone cements. For samples with MAA comonomer, a faster curing time and higher setting temperature were observed when compared to the cement with DEAEMA comonomer. In terms of mechanical properties, the highest compressive strength was exhibited by formulations containing MAA, while the highest impact strength was shown by the formulations prepared with DEAEMA. There were no differences observed between the two formulations for tensile, shear, and bending strength values. Similarly, fatigue crack propagation studies did not reveal differences with the addition of either DEAEMA or MAA.No differences were observed in the initial number of attached primary rat femur osteoblasts on the different bone cements and positive controls. However, after 48 h there was a reduced proliferation in the cells grown on bone cements containing MAA.

  20. Photoimaging of the multiple filamentation of femtosecond laser pulses in poly(methyl methacrylate) doped with 2,2-difluoro-4-(9-anthracyl)-6-methyl-1,3,2-dioxaborine

    SciTech Connect

    Kulchin, Yu N; Vitrik, O B; Chekhlenok, A A; Zhizhchenko, A Yu; Proschenko, D Yu; Mirochnik, A G; Lyu Guohui

    2013-12-31

    We have studied the filamentation of femtosecond laser pulses (λ = 800 nm, ∼42 fs pulse duration) in poly(methyl methacrylate) doped with 2,2-difluoro-4-(9-anthracyl)-6-methyl-1,3,2- dioxaborine and the associated photomodification of the material. The results demonstrate that multiple filamentation occurs at pulse energies above 5 μJ. At a pulse energy of 1.5 mJ, it is accompanied by supercontinuum generation. The average filament length in PMMA is 9 mm and the filament diameter is ∼10 μm. An incident power density of ∼10{sup 12} W cm{sup -2} ensures inscription of the filament pattern owing to two-photon photochemical processes. Preliminary exposure to continuous light at λ = 400 nm enables an ordered filament pattern to be written. (interaction of laser radiation with matter)

  1. Electrical stabilities and memory mechanisms of organic bistable devices fabricated utilizing a poly(3,4-ethylene-dioxythiophene): Poly(styrenesulfonate) layer with a poly(methyl methacrylate) buffer layer

    NASA Astrophysics Data System (ADS)

    Min Son, Jung; Seung Song, Woo; Ho Yoo, Chan; Yeol Yun, Dong; Whan Kim, Tae

    2012-04-01

    Organic bistable devices (OBDs) based on a poly(3,4-ethylene-dioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) layer with a poly(methyl methacrylate) (PMMA) buffer layer were fabricated on indium-tin-oxide (ITO)-coated polyethylene terephthalate (PET) flexible substrates. Current-voltage curves for the Al/PEDOT:PSS/PMMA/ITO/PET device showed current bistabilities with an ON/OFF current ratio of 1 × 103, indicative of a significant enhancement of memory storage. The endurance number of the ON/OFF switchings for the OBDs was above 1 × 105 cycles showing high potential applications in read only memory devices. The memory mechanisms for the OBDs on the basis of oxidation and reduction operations were attributed to the filament processes.

  2. Fabrication of a microfluidic system for capillary electrophoresis using a two-stage embossing technique and solvent welding on poly(methyl methacrylate) with water as a sacrificial layer.

    PubMed

    Koesdjojo, Myra T; Tennico, Yolanda H; Remcho, Vincent T

    2008-04-01

    Methods for fabricating poly(methyl methacrylate) microchips using a novel two-stage embossing technique and solvent welding to form microchannels in microfluidic devices are presented. The hot embossing method involves a two-stage process to create the final microchip design. In its simplest form, a mold made of aluminum is fabricated using CNC machining to create the desired microchannel design. In this work, two polymer substrates with different glass transition temperatures (Tg), polyetherimide (PEI) and poly(methyl methacrylate) (PMMA), were used to make the reusable secondary master and the final chip. First, the aluminum mold was used to emboss the PEI, a polymeric substrate with Tg approximately 216 degrees C. The embossed PEI was then used as a secondary mold for embossing PMMA, a polymeric substrate with a lower Tg ( approximately 105 degrees C). The resulting PMMA substrate possessed the same features as those of the aluminum mold. Successful feature transfer from the aluminum mold to the PMMA substrate was verified by profilometry. Bonding of the embossed layer and a blank PMMA layer to generate the microchip was achieved by solvent welding. The embossed piece was first filled with water that formed a solid sacrificial layer when frozen. The ice layer prevented channel deformation when the welding solvent (dichloroethane) was applied between the two chips during bonding. Electrophoretic separations of fluorescent dyes, rhodamine B (Rh B) and fluorescein (FL), were performed on PMMA microchips to demonstrate the feasibility of the fabrication process for microreplication of useful devices for separations. The PMMA micro-chip was tested under an electric field strength of 705 V cm-1. Separations of the test mixture of Rh B and FL generated 55 500 and 66 300 theoretical plates/meter, respectively.

  3. Facile Synthesis of Novel Polyethylene-Based A-B-C Block Copolymers Containing Poly(methyl methacrylate) Using a Living Polymerization System.

    PubMed

    Song, Xiangyang; Ma, Qiong; Cai, Zhengguo; Tanaka, Ryo; Shiono, Takeshi; Grubbs, Robert B

    2016-02-01

    Ethylene-propylene-methyl methacrylate (MMA) and ethylene-hexene-MMA A-B-C block copolymers with high molecular weight (>100,000) are synthesized using fluorenylamide-ligated titanium complex activated by modified methylaluminoxane and 2,6-di-tert-butyl-4-methylphenol for the first time. After diblock copolymerization of olefin is conducted completely, MMA is added and activated by aluminum Lewis acid to promote anionic polymerization. The length of polyolefin and poly (methyl methacrylate) (PMMA) is controllable precisely by the change of the additive amount of olefin and polymerization time, respectively. A soft amorphous polypropylene or polyhexene segment is located between two hard segments of semicrystalline polyethylene and glassy PMMA blocks.

  4. Visualisation of methacrylate-embedded human bone sections by infrared nanoscopy.

    PubMed

    Geith, Tobias; Amarie, Sergiu; Milz, Stefan; Bamberg, Fabian; Keilmann, Fritz

    2014-06-01

    A recently developed ultra-resolving near-field infrared nanoscope is applied to investigate methyl methacrylate embedded, un-decalcified human bone sections. Results show detail at a resolution of 30 nm. Specific contrasting of mineral components is enabled by choosing an appropriate infrared wavelength, here 9.47 μm, in the phosphate vibrational band. The method is surface-sensitive, probing to a depth of about 30 nm into the surface. The obtained infrared images are presented in direct comparison with optical and electron micrographs of the identical specimen. Lamellar bone organization, peri-cellular mineral deposition, and regional differences in mineral content are clearly detectable. Individual fibrils are resolved. - Infrared nanoscopy requires just standard hard tissue preparation techniques combined with section surface polishing. It can be integrated into existing laboratory environments without impeding subsequent routine staining and evaluation methods.

  5. The tissue response to an alkylene bis(dilactoyl)-methacrylate bone adhesive.

    PubMed

    Heiss, Christian; Hahn, Niels; Wenisch, Sabine; Alt, Volker; Pokinskyj, Peter; Horas, Uwe; Kilian, Olaf; Schnettler, Reinhard

    2005-04-01

    Gluing is an attractive technique to fix small bone fragments. However, to date no bone adhesive could be established successfully for all day clinical use. The purpose of this experimental study was to investigate the biocompatibility of a new bone glue based on alkylene bis(dilactoyl)-methacrylate in 36 rabbits. Monocondylar osteotomy of the distal femur was performed and bone glue was applied into the osteotomy gap in 24 rabbits. The remaining 12 animals served as controls. In all rabbits the osteotomy was subsequently stabilized by K-wire osteosynthesis. Six animals of the glue group and 3 controls were euthanized after 7, 21, 42, and 84 days, respectively. Fracture healing and degradation pattern of the glue was studied using histological, histomorphometrical, scanning electron microscopical, and radiological methods. Good resorption of the glue by mononuclear and multinucleated giant cells without prolonged inflammatory processes was observed in the glue group. Histomorphometrical analysis did not reveal any significant differences in fracture healing between the glue and control group at any time. Complete remodelling of the former osteotomy gap was found in all rabbits after 84 days. This bioresorbable bone adhesive exhibited good biocompatibility and its degradation did not interfere with physiological fracture healing.

  6. Enhancement of light harvesting efficiency of silicon solar cell utilizing arrays of poly(methyl methacrylate-co-acrylic acid) nano-spheres and nano-spheres with embedded silver nano-particles

    NASA Astrophysics Data System (ADS)

    Lee, Chee-Leong; Goh, Wee-Sheng; Chee, Swee-Yong; Yik, Lai-Kuan

    2017-02-01

    An array of uniformly distributed monolayer of poly(methyl methacrylate-co-acrylic acid) nano-spheres were deposited onto an amorphous silicon photovoltaic cell utilizing dip coating technique. The electrical characteristics of the coated photovoltaic cell reveal that the nano-spheres with an average diameter size of 101 nm exhibits excellent light harvesting characteristics if compared to the nano-spheres of other sizes. The power conversion efficiency from such integration of the nano-structures (i.e. 3.14% per PV cell) indicates that at least 1.6 times of improvement (or relative enhancement of 57%) can be achieved comparatively to the uncoated photovoltaic cell (i.e. 2% per PV cell). Further increment of the power conversion efficiency of the solar cell has been attained with the incorporation of the silver nano-particles into the nano-spheres of similar average size. With the inclusion of the silver nano-particles into such nano-spheres, the power conversion efficiency of the solar cell has attained 5.57% per PV cell, which is about 2.8 times (or relative enhancement of 179%) if compared to the uncoated samples. Hence, this novel and controllable technique of fabricating omnidirectional light-harvesting nano-spheres with embedded silver nano-particles will indubitably be beneficial to various types of optoelectronic devices.

  7. Facile transfer of thickness controllable poly(methyl methacrylate) patterns on a nanometer scale onto SiO2 substrates via microcontact printing combined with simplified Langmuir-Schaefer technique.

    PubMed

    Kim, Yong-Kwan; Kim, Dae-Il; Park, Jaehyun; Shin, Gunchul; Kim, Gyu Tae; Ha, Jeong Sook

    2008-12-16

    We report on the facile patterning of poly(methyl methacrylate) (PMMA) layers onto SiO2 substrates via microcontact printing combined with the simplified Langmuir-Schaefer (LS) technique. Langmuir film of PMMA was formed just by dropping a dilute PMMA solution onto the air/water surface in a glass Petri dish via self-assembly, and it was used as an ink for the patterned poly(dimethylsilioxane) (PDMS) stamp. The transferred film properties were systematically investigated with variation of postannealing temperature, molecular weight of PMMA, and the inking number. The patterned PMMA film surface was smooth with no vacancy defect in a few micrometers scale AFM images over the whole film area after post-annealing process. The thickness of the PMMA patterns was controlled on the nanometer scale by the number of inkings of the LS layer of PMMA on the PDMS stamp. By using the PMMA patterns as a barrier and a sacrificial layer against the chemical etching and metal deposition, SiO2 and metal patterns were fabricated, respectively. The PMMA layers also worked as a passivation layer against the patterning of V2O5 nanowires and the selective adsorption of single-walled carbon nanotubes (SWCNTs). We also fabricated thin film transistors using patterned SWCNTs with different percolation states and investigated the electrical properties.

  8. Surface functionalization of BiFeO3: A pathway for the enhancement of dielectric and electrical properties of poly(methyl methacrylate)-BiFeO3 composite films

    NASA Astrophysics Data System (ADS)

    Mishra, Mukesh Kumar; Moharana, Srikanta; Behera, Banarji; Mahaling, Ram Naresh

    2017-03-01

    A novel two-phase composite film is prepared by the solvent casting method employing poly(methyl methacrylate) (PMMA) as polymer matrix and bismuth ferrite (BFO) as ceramic filler. The surfaces of BFO are functionalized by proper hydroxylating agents to activate their chemical nature. The structural analysis of the composite films confirms that the composites made up of functionalized BFO (BFO-OH) have a distorted rhombohedral structure. The morphological analysis shows that BFO-OH particles are equally distributed over the polymer matrix. The -OH functionality of BFO-OH is confirmed by FTIR. The dielectric and electrical studies at a frequency range from 100 Hz to 1 MHz reveal that PMMA-(BFO-OH) composites have enhanced dielectric constant as well as electrical conductivities, much higher than that of unmodified composites. According to the ferroelectric measurement result, the hydroxylated composite film shows a superior ferroelectric behavior than that of the unmodified one, with a remanent polarization (2 P r) of 2.764 μC/cm2.

  9. Poly(methyl methacrylate-acrylonitrile-ethyl acrylate) terpolymer based gel electrolyte for LiNi0.5Mn1.5O4 cathode of high voltage lithium ion battery

    NASA Astrophysics Data System (ADS)

    Sun, Ping; Liao, Youhao; Xie, Huili; Chen, Tingting; Rao, Mumin; Li, Weishan

    2014-12-01

    A novel gel polymer electrolyte (GPE), based on poly(methyl methacrylate-acrylonitrile-ethyl acrylate) (P(MMA-AN-EA)) terpolymer, is designed to match LiNi0.5Mn1.5O4 cathode of 5 V lithium ion battery. The performances of the synthesized P(MMA-AN-EA) terpolymer and the corresponding membrane and GPE are investigated by scanning electron microscope, energy dispersive spectroscopy, nuclear magnetic resonance spectra, Fourier transform infrared spectra, thermogravimetric analyzer, electrochemical impedance spectroscopy, linear sweep voltammetry, and charge/discharge test. It is found that the pore structure of P(MMA-AN-EA) membrane is affected by the dose of pore forming agent, polyethylene glycol (PEG400). The membrane with 3 wt% PEG400 presents the best pore structure, in which pores are dispersed uniformly and interconnected, and exhibits the largest electrolyte uptake, resulting in the highest ionic conductivity of 3.82 × 10-3 S cm-1 for the corresponding GPE at room temperature. The GPE has improved compatibility with lithium anode and is electrochemically stable up to 5.2 V (vs. Li/Li+). The high voltage LiNi0.5Mn1.5O4 cathode using the resulting GPE exhibits excellent cyclic stability, maintaining 97.9% of its initial discharge capacity after 100 cycles compared to that of 79.7% for the liquid electrolyte at 0.5 C.

  10. Monolayer and Brewster angle microscopy studies of poly(methyl methacrylate)-monopalmitin mixed systems at the air-water interface.

    PubMed

    Miñones Conde, Mercedes; Trillo, J M; Conde, Olga; Miñones, Jose

    2010-03-04

    Mixed monolayers of poly(methyl metacrylate) (PMMA) and monopalmitin (Mp) were used for the study of their interactions. A thorough analysis of surface pressure (pi)-area (A) isotherms with the Langmuir monolayer technique, complemented with Brewster angle microscopy (BAM) images was performed. Mixed films show two phase transitions at a surface pressure of 14.5 mN/m and at 20-21 mN/m, respectively. Moreover, mixed monolayers show two well-defined collapses: one, corresponding to the lipid (at surface pressures of 50-51 mN/m) and the another one, ascribed to the PMMA, at surface pressure values of 57-58 mN/m. When the mean molecular areas of the mixed films (A(1,2)) were plotted versus film composition (X(1) or X(2)), positive deviations from the ideal behavior were observed at surface pressures below 15 mN/m, which were mainly attributed to a change in the conformation of the PMMA molecules at the surface. However, at higher surface pressures, the areas per monomer unit of the mixed monolayers obey the additivity rule, attributed to the fact that the film components form an immiscible system in these conditions.

  11. Fluorescence-based Sensing of 2,4,6-Trinitrotoluene (TNT) Using a Multi-channeled Poly(methyl methacrylate) (PMMA) Microimmunosensor

    PubMed Central

    Charles, Paul T.; Adams, Andre A.; Howell, Peter B.; Trammell, Scott A.; Deschamps, Jeffrey R.; Kusterbeck, Anne W.

    2010-01-01

    Fluorescence immunoassays employing monoclonal antibodies directed against the explosive 2,4,6-trinitrotoluene (TNT) were conducted in a multi-channel microimmunosensor. The multi-channel microimmunosensor was prepared in poly (methyl methacrylate) (PMMA) via hot embossing from a brass molding tool. The multi-channeled microfluidic device was sol-gel coated to generate a siloxane surface that provided a scaffold for antibody immobilization. AlexaFluor-cadaverine-trinitrobenzene (AlexaFluor-Cad-TNB) was used as the reporter molecule in a displacement immunoassay. The limit of detection was 1–10 ng/mL (ppb) with a linear dynamic range that covered three orders of magnitude. In addition, antibody crossreactivity was investigated using hexahydro-1,3,5-triazine (RDX), HMX, 2,4-dinitrotoluene (DNT), 4-nitrotoluene (4-NT) and 2-amino-4,6-DNT. PMID:22315573

  12. Synthesis and characterization of TiO2/poly(methyl methacrylate) nanocomposites via surface thiol-lactam initiated radical polymerization.

    PubMed

    Bach, Long Giang; Islam, M Rafiqul; Gal, Yeong Soon; Lim, Kwon Taek

    2012-07-01

    An approach to the surface modification of TiO2 nanoparticles was described based on the thiol functionalization of TiO2 followed by thiol-lactam initiated radical polymerization (TLIRP) of methyl methacrylate (MMA). FT-IR, XRD and XPS analyses confirmed the grafting of the polymer on the TiO2 surface. TGA analysis revealed superior thermal stability of PMMA-g-TiO2 compared with PMMA. TEM measurements and time-dependent phase monitoring suggested much higher colloidal stability of PMMA-g-TiO2 than TiO2 in toluene. The controlled nature of the TLIRP of MMA from the surface of TiO2 was determined by GPC analysis.

  13. Laser-ablated poly(methyl methacrylate) microdevices for sub-microliter DNA amplification suitable for micro-total analysis systems

    NASA Astrophysics Data System (ADS)

    Lounsbury, Jenny A.; Poe, Brian L.; Do, Michael; Landers, James P.

    2012-08-01

    Biochemical techniques, such as the polymerase chain reaction (PCR), can take up to 3.5 h for completion using a commercial bench-top instrument, creating a bottleneck in sample preparation processes. PCR has been successfully adapted to microfluidic devices, reducing the time needed to as little as 7-10 min. Recently, a trend in the field is to use alternative substrates, such as poly(methyl methacyrlate) (PMMA), for the fabrication of microfluidic devices. PMMA has several advantages over more expensive substrates including rigidity without fragility, disposability, and it is easy to fabricate, using techniques such as hot embossing or CO2 laser ablation. Here, we report the fabrication of PMMA microdevices to explore their effectiveness for PCR amplification. Several types of PMMA microdevices were fabricated using a CO2 laser ablation system, with two or three PMMA layers of different thicknesses. Bonding of the microdevices was significantly improved through the use of a grid system etched into the device, allowing for trapped air to escape, eliminating leakage. Using infrared thermal cycling, the ramping rates were determined to be dependent on the thickness of the PMMA used in fabrication, allowing for customization of cycling conditions. Further reduction of the thermal mass by isolation of the chambers provided a significant increase in the heating and cooling rates (up to 6.19 (±0.32 °C s-1) and -7.99 (±0.06 °C s-1), respectively). Bubble formation, a chronic problem in microfluidic systems in general and problematic during the heating phase of PCR, was minimized through the use of a biocompatible adhesive/manifold combination to seal the reservoirs. Finally, successful PCR amplification was demonstrated with both a fragment from the β-globin gene and 15 tetra-nucleotide repeat regions with a sex-typing marker in a conventional STR kit with the latter facilitated by the dynamic coating of the fluidic architecture with poly(ethylene glycol) (PEG).

  14. Cold acetone fixation and methacrylate embedding. A suitable method for routine processing of bone marrow biopsies.

    PubMed

    Hantschick, M; Stosiek, P

    1998-01-01

    Here we report that acetone fixation at -18 degrees C with subsequent embedding in methyl-/butylmethacrylate is a reliable method for the routine processing of bone marrow biopsies. This method allows good conventional histological visualization of morphological details, which is comparable with other fixation procedures. The essential advantage of this method is that a wide range of monoclonal antibodies and polyclonal antisera can be used for immunohistochemical investigations for diagnostic and scientific purposes. The addition of 5% polyethylene glycol 400 to the acetone minimizes freeze-related artefacts. The immunohistochemical demonstration of a number of antigens is mostly affected by the medium used for slide preparation and to a lesser extent by the concentration of benzoylperoxide used for polymerization. Performing polymerization at 4 degrees C and using N, N-dimethyl-p-toluidine as accelerator allows the concentration of benzoylperoxide to be reduced to 0.2 g% (8.3 mmol). Under these conditions the methacrylate embedding procedure has only minimal effects on the quality of immuno- and enzyme histochemistry. Additionally, the simplified method for removing the polymerization inhibitor from the methacrylate components and the shortened impregnation step are further advantages of the embedding method described here.

  15. Preparation and Characterization of Injectable Brushite Filled-Poly (Methyl Methacrylate) Bone Cement

    PubMed Central

    Rodriguez, Lucas C.; Chari, Jonathan; Aghyarian, Shant; Gindri, Izabelle M.; Kosmopoulos, Victor; Rodrigues, Danieli C.

    2014-01-01

    Powder-liquid poly (methyl methacrylate) (PMMA) bone cements are widely utilized for augmentation of bone fractures and fixation of orthopedic implants. These cements typically have an abundance of beneficial qualities, however their lack of bioactivity allows for continued development. To enhance osseointegration and bioactivity, calcium phosphate cements prepared with hydroxyapatite, brushite or tricalcium phosphates have been introduced with rather unsuccessful results due to increased cement viscosity, poor handling and reduced mechanical performance. This has limited the use of such cements in applications requiring delivery through small cannulas and in load bearing. The goal of this study is to design an alternative cement system that can better accommodate calcium-phosphate additives while preserving cement rheological properties and performance. In the present work, a number of brushite-filled two-solution bone cements were prepared and characterized by studying their complex viscosity-versus-test frequency, extrusion stress, clumping tendency during injection through a syringe, extent of fill of a machined void in cortical bone analog specimens, and compressive strength. The addition of brushite into the two-solution cement formulations investigated did not affect the pseudoplastic behavior and handling properties of the materials as demonstrated by rheological experiments. Extrusion stress was observed to vary with brushite concentration with values lower or in the range of control PMMA-based cements. The materials were observed to completely fill pre-formed voids in bone analog specimens. Cement compressive strength was observed to decrease with increasing concentration of fillers; however, the materials exhibited high enough strength for consideration in load bearing applications. The results indicated that partially substituting the PMMA phase of the two-solution cement with brushite at a 40% by mass concentration provided the best combination of the

  16. Adhesion work and wettability of polytetrafluorethylene and poly(methyl methacrylate) by aqueous solutions of cetyltrimethylammonium bromide and Triton X-100 mixture with ethanol.

    PubMed

    Bielawska, Magdalena; Jańczuk, Bronisław; Zdziennicka, Anna

    2013-08-15

    The contact angle measurements of the aqueous solutions of p-(1,1,3,3-tetramethylbutyl)phenoxypoly(ethylene glycol) (TX-100) and cetyltrimethylammonium bromide (CTAB) mixture with ethanol on polytetrafluoroethylene (PTFE) and poly (methyl methacrylate) (PMMA) were carried out in the range of the total concentration of TX-100 and CTAB mixture from 1×10(-6) to 1×10(-3) M and in the whole range of ethanol concentration. In the surfactant mixture, the mole fraction of TX-100 was equal to 0.2; 0.4; 0.6 and 0.8, respectively. From the obtained results, the critical surface tension of PTFE and PMMA wetting and the adhesion work of the solutions to the polymer surface were established. The PMMA surface tension was calculated from the Neumann's equation. It appeared that for the ethanol concentration higher than that corresponding to the association of its molecules, the surface tension of PMMA calculated from the Neumann's equation is close to the critical surface tension of PMMA wetting. It also appeared that it is possible to predict the work of adhesion of the studied solutions to the PMMA surface by using the PMMA surface tension data determined on the basis of the van Oss et al. approach to the interfacial tension and those from the Neumann's equation.

  17. Characterization and ion-induced degradation of cross-linked poly(methyl methacrylate) studied using time of flight secondary ion mass spectrometry

    NASA Astrophysics Data System (ADS)

    Wagner, M. S.; Lenghaus, K.; Gillen, G.; Tarlov, M. J.

    2006-12-01

    In this study, a series of random copolymers of methyl methacrylate (MMA) and ethylene glycol dimethacrylate (EGDMA) were prepared as surface-initiated polymer (SIP) films on silicon substrates using atom transfer radical polymerization. Positive and negative ion static time-of-flight secondary ion mass spectrometry (ToF-SIMS) was used to characterize SIP films with different MMA/EGDMA monomer ratios in an attempt to quantify their surface composition. However, matrix effects in the positive and negative ion modes led to preferential secondary ion generation from the EGDMA monomer and suppression of secondary ions characteristic of the MMA monomer, precluding accurate quantification using standard linear quantification methods. Ion-induced degradation of these films under 5 keV SF 5+ bombardment was also examined to determine the effect of cross-linking on the accumulation of ion-induced damage. Increasing incorporation of the EGDMA cross-linker in the SIP films decreased the sputter rate and increased the rate of damage accumulation under extended (>10 14 ions/cm 2) 5 keV SF 5+ bombardment. Comparison of the ion bombardment data with thermal degradation of cross-linked PMMA suggests that the presence of the cross-linker impedes degradation by depolymerization, resulting in ion-induced damage accumulation. The increased rate of ion-induced damage accumulation with increased cross-link density also suggests that polymers that can form cross-links during ion bombardment are less amenable to depth profiling using polyatomic primary ions.

  18. Synthesis and Self-Assembly of Rod2Coil Miktoarm Star Copolymers of Poly(3-dodecxylthiophene) and Poly(methyl methacrylate) with high rod fractions

    NASA Astrophysics Data System (ADS)

    Park, Jicheol; Moon, Hong Chul; Choi, Chung-Royng; Kim, Jin Kon

    2015-03-01

    Poly(3-dodecylthiophene)-b-poly(methyl methacrylate) diblock copolymer (P3DDT- b-PMMA) can self-assembled into various microdomains such as spheres, cylinders, and lamellae depending on weight fraction of P3DDT. However, only filbril morphology was formed when weight fraction of P3DDT (wP 3 DDT) was major (wP 3 DDT ~ 0.76). Here, we introduce a new approach to obtain microdomain structures even at high wP 3 DDT by using well-defined A2B miktoarm star copolymer composed of P3DDT and PMMA ((P3DDT)2PMMA. We found via small angle X-ray scattering and transmission electron microscopy that (P3DDT)2PMMA showed PMMA cylinder packed hexagonally in the matrix of P3DDT and body-centered-cubic spheres of PMMA for wP 3 DDT of 0.66 and 0.75, respectively. This because of much reduction of the rod-rod interaction in (P3DDT)2PMMA compared with P3DDT- b-PMMA diblock copolymers.

  19. Acrylic AB and ABA block copolymers based on poly(2-ethylhexyl acrylate) (PEHA) and poly(methyl methacrylate) (PMMA) via ATRP.

    PubMed

    Haloi, Dhruba J; Ata, Souvik; Singha, Nikhil K; Jehnichen, Dieter; Voit, Brigitte

    2012-08-01

    Acrylic block copolymers have several advantages over conventional styrenic block copolymers, because of the presence of a saturated backbone and polar pendant groups. This investigation reports the preparation and characterization of di- and triblock copolymers (AB and ABA types) of 2-ethylhexyl acrylate (EHA) and methyl methacrylate (MMA) via atom transfer radical polymerization (ATRP). A series of block copolymers, PEHA-block-PMMA(AB diblock) and PMMA-block-PEHA-block-PMMA(ABA triblock) were prepared via ATRP at 90 °C using CuBr as catalyst in combination with N,N,N',N″,N″-pentamethyl diethylenetriamine (PMDETA) as ligand and acetone as additive. The chemical structure of the macroinitiators and molar composition of block copolymers were characterized by (1)H NMR analysis, and molecular weights of the polymers were analyzed by GPC analysis. DSC analysis showed two glass transition temperatures (T(g)), indicating formation of two domains, which was corroborated by AFM analysis. Small-angle X-ray scattering (SAXS) analysis of AB and ABA block copolymers showed scattering behavior inside the measuring limits indicating nanophase separation. However, SAXS pattern of AB diblock copolymers indicated general phase separation only, whereas for ABA triblock copolymer an ordered or mixed morphology could be deduced, which is assumed to be the reason for the better mechanical properties achieved with ABA block copolymers than with the AB analogues.

  20. Bond strength of an alkylene bis(dilactoyl)-methacrylate bone adhesive: a biomechanical evaluation in sheep.

    PubMed

    Heiss, Christian; Schettler, Nicky; Wenisch, Sabine; Cords, Sven; Schilke, Frank; Lips, Katrin Susanne; Alt, Volker; Schnettler, Reinhard

    2010-01-01

    The purpose of this study is to assess the mechanical efficacy of an alkylene bis(dilactoyl)-methacrylate-based degradable bone adhesive in 36 sheep. Bone segmentation with osteotomies of the metaphyseal ulna was performed and adhesive was applied into the osteotomy gaps in 18 sheep. The remaining 18 animals served as controls. The segment was subsequently stabilized without any osteosynthesis in all sheep. Six animals of the adhesive group and 6 controls were killed after 21, 42 and 84 days, respectively. Bond strength of the adhesive and quality of fracture healing was studied using biomechanical, histological and radiological methods. There were no significant differences in biomechanical analysis between both groups at any time. However, an increase of in vivo bond strength with the highest stiffness of 102.83 N/mm(2) was observed in the adhesive group after 84 days. In vitro analysis showed non-significant differences in bond strength during polymerization time. Histomorphometric investigations revealed significant differences in osteotomy cross-section area after 84 days, with higher areas of callus in the control. After 84 days the X-ray examinations showed completely bridged gaps in four of six animals in the adhesive and in five animals in the control group. This bone adhesive exhibited good in vivo and in vitro bond strength and mechanical efficiency in both the short and long term without impairment of physiological fracture healing.

  1. Control of methyl methacrylate during the preparation of orthopedic bone cements.

    PubMed

    Ungers, Leslie J; Vendrely, Timothy G; Barnes, C Lowry

    2007-04-01

    The use of methyl methacrylate (MMA) bone cement during orthopedic procedures has been seen as a potential exposure hazard to health care professionals. However, that assessment is based on a number of investigations with problems in experimental design, analysis, and data interpretation. The current investigation quantified differences in MMA vapors produced during the preparation of competing bone cements using various methods of preparation. Unlike previous investigations, this effort employs modern validated sampling and analytical methods, and considers the affect of censored results. Measurements of sufficient quality and number were collected to allow for a statistical treatment of the data. The ability of two controlled preparation techniques to reduce MMA emissions were compared with a traditional open container. The results confirmed that the preparation of bone cement releases MMA vapors into the breathing zone of the preparer. One preparation technique (Stryker Bowl) controlled emissions during mixing and curing and affected a 73% reduction in measured MMA concentrations. In addition to mixing and curing, the second technique (UltraMix System) also controlled the MMA during pouring of the monomer and affected a 90% reduction in MMA concentrations. An ANOVA test of interaction indicates that the reductions are attributable to the preparation technique regardless of the type of cement being used. Both a Fisher's PLSD and Games/Howell post hoc test of the results indicate that the mean differences between the uncontrolled open container and the controlled preparation techniques are significant (p < 0.05).

  2. Promotion of osteoblast differentiation in 3D biomaterial micro-chip arrays comprising fibronectin-coated poly(methyl methacrylate) polycarbonate.

    PubMed

    Altmann, Brigitte; Steinberg, Thorsten; Giselbrecht, Stefan; Gottwald, Eric; Tomakidi, Pascal; Bächle-Haas, Maria; Kohal, Ralf-Joachim

    2011-12-01

    Due to the architecture of solid body tissues including bone, three-dimensional (3D) in vitro microenvironments appear favorable, since herein cell growth proceeds under more physiological conditions compared to conventional 2D systems. In the present study we show that a 3D microenvironment comprising a fibronectin-coated PMMA/PC-based micro-chip promotes differentiation of primary human osteoblasts as reflected by the densely-packed 3D bone cell aggregates and expression of biomarkers indicating osteoblast differentiation. Morphogenesis and fluorescence dye-based live/dead staining revealed homogenous cell coverage of the microcavities of the chip array, whereat cells showed high viability up to 14 days. Moreover, Azur II staining proved formation of uniform sized multilayered aggregates, exhibiting progressive intracellular deposition of extracellular bone matrix constituents comprising fibronectin, osteocalcin and osteonectin from day 7 on. Compared to 2D monolayers, osteoblasts grown in the 3D chip environment displayed differential mostly higher gene expression for osteocalcin, osteonectin, and alkaline phosphatase, while collagen type I remained fairly constant in both culture environments. Our results indicate that the 3D microenvironment, based on the PMMA biomaterial chip array promotes osteoblast differentiation, and hereby renders a promising tool for tissue-specific in vitro preconditioning of osteoblasts designated for clinically-oriented bone augmentation or regeneration. Copyright © 2011 Elsevier Ltd. All rights reserved.

  3. Long-Term Safety and Longevity of a Mixture of Polymethyl Methacrylate and Cross-Linked Dextran (Lipen-10®) after Penile Augmentation: Extension Study from Six to 18 Months of Follow-Up

    PubMed Central

    Kim, Ma Tae; Ko, Kyungtae; Lee, Won Ki; Kim, Sae Chul

    2015-01-01

    Purpose The goal of this study was to investigate the long-term efficacy and safety of a mixture of polymethyl methacrylate (PMMA) and cross-linked dextran Lipen-10® used for penile augmentation under the physical impact generated during sexual intercourse. Materials and Methods From March 2010 to October 2011, a total of 20 patients with a mean age of 44 years (interquartile range, 20~70 years) who requested penile augmentation participated in this study. Lipen-10® filler is a mixture of 75% cross-linked dextran, 15% PMMA, and 10% hypromellose solution. With the patient in the supine position, Lipen-10® was injected into the subcutaneous tissue between the dartos fascia and Buck's fascia of the penis using a fanning technique. Penile length and circumference were measured before the procedure and six, 12, and 18 months after the procedure. Values were compared using the Student's t-test and the paired t-test. Results A total of 15 patients completed this study. The increases in circumference and length observed six months after the procedure were found to have been maintained without change at 12 and 18 months of follow-up. At 12 and 18 months of follow-up, no abnormal findings were observed. Pelvic magnetic resonance imaging conducted at 18 months of follow-up showed no trace of the injected filler having migrated to other sites, and the volume was well maintained. Conclusions Lipen-10®, a mixture of PMMA and cross-linked dextran, showed good durability and tolerability over 18 months of follow-up during which the participants were sexually active. PMID:26770941

  4. Usefulness of a quick decalcification of bone sections embedded in methyl methacrylate[corrected]: an improved method for immunohistochemistry.

    PubMed

    Gomes, Samirah Abreu; dos Reis, Luciene Machado; de Oliveira, Ivone Braga; Noronha, Irene de Lourdes; Jorgetti, Vanda; Heilberg, Ita Pfeferman

    2008-01-01

    Immunohistochemistry of undecalcified bone sections embedded in methyl methacrylate (MMA) is not commonly employed because of potential destruction of tissue antigenicity by highly exothermic polymerization. The aim of the present study was to describe a new technique in which a quick decalcification of bone sections embedded in MMA improves the results for immunohistochemistry. The quality of interleukin 1alpha (IL-1alpha) immunostaining according to the present method was better than the conventional one. Immunostaining for osteoprotegerin (OPG) and the receptor activator of NF-kappaB ligand (RANKL) in bone sections of chronic kidney disease patients with mineral bone disorders (CKD-MBD) was stronger than in controls (postmortem healthy subjects). The present study suggested that this method is easy, fast, and effective to perform both histomorphometry and immunohistochemistry in the same bone fragment, yielding new insights into pathophysiological aspects and therapeutic approaches in bone disease.

  5. Histochemistry and immunohistochemistry on bone marrow biopsies. A rapid procedure for methyl methacrylate embedding.

    PubMed

    Lebeau, A; Muthmann, H; Sendelhofert, A; Diebold, J; Löhrs, U

    1995-03-01

    Starting from previous methodical approaches a procedure for low temperature methyl methacrylate (MMA) embedding of bone marrow biopsies is introduced, which allows routine application of enzyme and immunohistochemistry without loss of morphological quality by retaining fixation in Schaffer's solution. Survival of enzyme activity and antigen determinants is achieved by washing the fixed specimens in 70% methanol and dehydration in acetone in ascending concentrations at 4 degrees C. Modifications of the plastic embedding technique used in this study simplify and shorten the procedure, so that embedding according to this routine method is complete after two days of preparation. Additionally, a rapid embedding variant is introduced, which enables tissue preparation within one day if necessary. Results are demonstrated using markers for myeloid, lymphoid and epithelial cells as well as immunoglobulins and the proliferation associated antigen Ki-67. The investigation of a panel of monoclonal and polyspecific antibodies in 31 cases shows the eventually reduced immunoreactivity of a few markers after prolonged fixation. As a consequence it seems essential to ensure short fixation periods, especially when the specimens are sent by mail.

  6. Biocompatibility of calcium phosphate bone cement with optimised mechanical properties: an in vivo study.

    PubMed

    Palmer, Iwan; Nelson, John; Schatton, Wolfgang; Dunne, Nicholas J; Buchanan, Fraser; Clarke, Susan A

    2016-12-01

    This work establishes the in vivo performance of modified calcium phosphate bone cements for vertebroplasty of spinal fractures using a lapine model. A non-modified calcium phosphate bone cement and collagen-calcium phosphate bone cements composites with enhanced mechanical properties, utilising either bovine collagen or collagen from a marine sponge, were compared to a commercial poly(methyl methacrylate) cement. Conical cement samples (8 mm height × 4 mm base diameter) were press-fit into distal femoral condyle defects in New Zealand White rabbits and assessed after 5 and 10 weeks. Bone apposition and tartrate-resistant acid phosphatase activity around cements were assessed. All implants were well tolerated, but bone apposition was higher on calcium phosphate bone cements than on poly(methyl methacrylate) cement. Incorporation of collagen showed no evidence of inflammatory or immune reactions. Presence of positive tartrate-resistant acid phosphatase staining within cracks formed in calcium phosphate bone cements suggested active osteoclasts were present within the implants and were actively remodelling within the cements. Bone growth was also observed within these cracks. These findings confirm the biological advantages of calcium phosphate bone cements over poly(methyl methacrylate) and, coupled with previous work on enhancement of mechanical properties through collagen incorporation, suggest collagen-calcium phosphate bone cement composite may offer an alternative to calcium phosphate bone cements in applications where low setting times and higher mechanical stability are important.

  7. Surface characterisation of various bone cements prepared with functionalised methacrylates/bioactive ceramics in relation to HOB behaviour.

    PubMed

    Salih, Vehid; Mordan, Nicky; Abou Neel, Ensanya A; Armitage, David A; Jones, Frances H; Knowles, Jonathan C; Nazhat, Showan N; Vargas-Coronado, R; Cauich-Rodriguez, Juan V

    2006-03-01

    This study reports the relationship between the biocompatibility and surface properties of experimental bone cements. The effect of hydroxyapatite (HA) or alpha-tri-calcium phosphate (alpha-TCP) incorporated into bone cements prepared with methyl methacrylate as base monomer and either methacrylic acid or diethyl amino ethyl methacrylate (DEAEMA) as comonomers was investigated. The in vitro biocompatibility of these composite cements was assessed in terms of the interaction of primary human osteoblasts grown on the materials over a period of 5 days and compared with a control surface. These results were related to the surface properties investigated through a number of techniques, namely Fourier transform infrared, contact angle measurements, X-ray photoelectron spectroscopy and energy dispersive analysis of X-rays. Complementary techniques of thermal analysis and ion chromatography were also performed. Biocompatibility results showed that the addition of alpha-TCP improves biocompatibility regardless of comonomer type. This is in contrast to HA-based cements where cell proliferation was significantly lower. Surface characterisations showed that structural integrity of the materials was maintained in the presence of the acid and base comonomers, and water contact angles were reduced particularly in DEAEMA containing materials. Furthermore, ion chromatography confirmed higher Ca2+ and PO4(3-) ion release by both types of ceramics, particularly for those containing DEAEMA. In conclusion, the incorporation of acidic and basic comonomers to either HA or alpha-TCP ceramics containing bone cements can have differential effects upon the attachment and proliferation of bone cells in vitro. Moreover, those cements consisting of alpha-TCP and containing DEAEMA comonomer indicated the most favourable biocompatibility.

  8. Methacrylic resin having a high solar radiant energy absorbing property and process for producing the same

    SciTech Connect

    Abe, K.; Kamada, K.; Nakai, Y.

    1981-10-20

    A methacrylic resin having a high solar radiant energy absorbing property wherein an organic compound (A) containing cupric ion and a compound (B) having at least one p-o-h bond in a molecule are contained into the methacrylic resin selected from poly(Methyl methacrylate) or methacrylic polymers containing at least 50% by weight of a methyl methacrylate unit. A process for producing said methacrylic resin is also disclosed.

  9. Thermomechanical behavior of amorphous tactic methacrylate polymers

    NASA Technical Reports Server (NTRS)

    Kiran, E.; Gillham, J. K.; Gipstein, E.

    1974-01-01

    Dynamic mechanical spectra of amorphous stereoregular poly(methyl methacrylate)s and poly(t-butyl methacrylate)s with assigned microtacticities are presented and discussed. An intermolecular argument is invoked to account for the higher glass transition temperature of syndiotactic vis a vis isotactic PMMA, in spite of the higher density of the latter at 30 C. An argument is presented to show that the ratio of glassy-region relaxation temperature to glass transition temperature is not only a measure of the degree of coupling of the beta and glass transition processes, but also of the degree to which intermolecular factors influence these processes. The greater extent of the low-temperature irreversibilities observed in the thermomechanical spectra of poly(t-butyl methacrylate)s is attributed to the brittle character induced by the bulky side groups which presumably weaken cohesive forces.

  10. Osteoconductive Amine-Functionalized Graphene-Poly(methyl methacrylate) Bone Cement Composite with Controlled Exothermic Polymerization.

    PubMed

    Sharma, Rakesh; Kapusetti, Govinda; Bhong, Sayali Yashwant; Roy, Partha; Singh, Santosh Kumar; Singh, Shikha; Balavigneswaran, Chelladurai Karthikeyan; Mahato, Kaushal Kumar; Ray, Biswajit; Maiti, Pralay; Misra, Nira

    2017-09-20

    Bone cement has found extensive usage in joint arthroplasty over the last 50 years; still, the development of bone cement with essential properties such as high fatigue resistance, lower exothermic temperature, and bioactivity has been an unsolved problem. In our present work, we have addressed all of the mentioned shortcomings of bone cement by reinforcing it with graphene (GR), graphene oxide (GO), and surface-modified amino graphene (AG) fillers. These nanocomposites have shown hypsochromic shifts, suggesting strong interactions between the filler material and the polymer matrix. AG-based nanohybrids have shown greater osteointegration and lower cytotoxicity compared to other nanohybrids as well as pristine bone cement. They have also reduced oxidative stress on cells, resulting in calcification within 20 days of the implantation of nanohybrids into the rabbits. They have significantly reduced the exothermic curing temperature to body temperature and increased the setting time to facilitate practitioners, suggesting that reaction temperature and settling time can be dynamically controlled by varying the concentration of the filler. Thermal stability and enhanced mechanical properties have been achieved in nanohybrids vis-à-vis pure bone cement. Thus, this newly developed nanocomposite can create natural bonding with bone tissues for improved bioactivity, longer sustainability, and better strength in the prosthesis.

  11. Bone Repair and Military Readiness

    DTIC Science & Technology

    2013-10-19

    resin superior to polymethyl methacrylate (PNMA) with many improved properties such as significantly less polymerization stress although an...heat generation. We have developed a silorane based resin superior to polymethyl methacrylate (PMMA) with many improved properties such as significantly...less polymerization stress without an associated reduction in mechanical properties. These new resins do not generate cytotoxicity, antigenicity

  12. Silver nanoparticle based antibacterial methacrylate hydrogels potential for bone graft applications

    PubMed Central

    González-Sánchez, M. Isabel; Perni, Stefano; Tommasi, Giacomo; Morris, Nathanael Glyn; Hawkins, Karl; López-Cabarcos, Enrique; Prokopovich, Polina

    2015-01-01

    Infections are frequent and very undesired occurrences after orthopedic procedures; furthermore, the growing concern caused by the rise in antibiotic resistance is progressively dwindling the efficacy of such drugs. Artificial bone graft materials could solve some of the problems associated with the gold standard use of natural bone graft such as limited bone material, pain at the donor site and rejections if donor tissue is used. We have previously described new acrylate base nanocomposite hydrogels as bone graft materials. In the present paper, we describe the integration of silver nanoparticles in the polymeric mineralized biomaterial to provide non-antibiotic antibacterial activity against Staphylococcus epidermidis and Methicillin-resistant Staphylococcus aureus. Two different crosslinking degrees were tested and the silver nanoparticles were integrated into the composite matrix by means of three different methods: entrapment in the polymeric hydrogel before the mineralization; diffusion during the process of calcium phosphate crystallization and adsorption post-mineralization. The latter being generally the most effective method of encapsulation; however, the adsorption of silver nanoparticles inside the pores of the biomaterial led to a decreasing antibacterial activity for adsorption time longer than 2 days. PMID:25746278

  13. Silver nanoparticle based antibacterial methacrylate hydrogels potential for bone graft applications.

    PubMed

    González-Sánchez, M Isabel; Perni, Stefano; Tommasi, Giacomo; Morris, Nathanael Glyn; Hawkins, Karl; López-Cabarcos, Enrique; Prokopovich, Polina

    2015-05-01

    Infections are frequent and very undesired occurrences after orthopedic procedures; furthermore, the growing concern caused by the rise in antibiotic resistance is progressively dwindling the efficacy of such drugs. Artificial bone graft materials could solve some of the problems associated with the gold standard use of natural bone graft such as limited bone material, pain at the donor site and rejections if donor tissue is used. We have previously described new acrylate base nanocomposite hydrogels as bone graft materials. In the present paper, we describe the integration of silver nanoparticles in the polymeric mineralized biomaterial to provide non-antibiotic antibacterial activity against Staphylococcus epidermidis and Methicillin-resistant Staphylococcus aureus. Two different crosslinking degrees were tested and the silver nanoparticles were integrated into the composite matrix by means of three different methods: entrapment in the polymeric hydrogel before the mineralization; diffusion during the process of calcium phosphate crystallization and adsorption post-mineralization. The latter being generally the most effective method of encapsulation; however, the adsorption of silver nanoparticles inside the pores of the biomaterial led to a decreasing antibacterial activity for adsorption time longer than 2 days.

  14. Release of gentamicin sulphate from a modified commercial bone cement. Effect of (2-hydroxyethyl methacrylate) comonomer and poly(N-vinyl-2-pyrrolidone) additive on release mechanism and kinetics.

    PubMed

    Frutos, P; Diez-Peña, E; Frutos, G; Barrales-Rienda, J M

    2002-09-01

    The influence of the (2-hydroxyethyl methacrylate) (HEMA) monomer addition as a comonomer to the cement liquid component and of a polymer, poly(N-vinyl-2-pyrrolidone) (PVP) to the solid component of a standard CMW-1 bone cement on gentamicin sulphate (GS) on its drug release properties have been studied. The addition of HEMA modifies the habit of the delivery curves. The incorporation of PVP into the cement matrix, apparently, did not very much modify the shape of the HEMA modified cement release curves, but led to a remarkable increase of the maximum amount of GS released. This effect was proportional to the PVP concentration incorporated. From the matrix composition and SEM data, a model based on the morphology of the matrix has been proposed. The cumulative amount of GS released by each slab Mt is most adequately fitted and represented by the equation Mt = c + at 1/2 + b[1 - exp(-nt)], which corroborates that the release occurs according to the model proposed. by means of three discrete mechanisms, namely: (i) a short-term initial elution due to the imperfections in the poly(methyl methacrylate) covering of the most external GS beads, burst effect by the buffer solution; (ii) followed by a fracture by stress cracking in an active media of the coated GS beads located on the external surface of the matrix where water molecules enter to dissolve GS molecules releasing them into the buffer solution by a diffusion-controlled process; and (iii) a third process in which the buffer solution penetrates into the internal voids and cracks creating a series of channels in a labyrinthic structure, which may facilitate the access of water molecules to the plastic-coated GS beads within the bulk matrix. This third process is enhanced by the incorporation of PVP beads as dissolved molecules within the matrix. This water-soluble additive is leachable, generating a highly porous structure in the cement. This HEMA and PVP modified cement may be used as a drug delivery system to

  15. Contact dermatitis to methyl methacrylate.

    PubMed

    Kassis, V; Vedel, P; Darre, E

    1984-07-01

    2 cases of contact dermatitis to methyl methacrylate monomer are presented. The patients are nurses who mixed bone cement at orthopedic operations. During the procedure, they used 2 pairs of gloves (latex). Butyl rubber gloves are recommended for methyl methacrylate monomer to avoid sensitization and/or cumulative irritant contact dermatitis on the hands.

  16. Novel glycidyl methacrylated dextran (Dex-GMA)/gelatin hydrogel scaffolds containing microspheres loaded with bone morphogenetic proteins: formulation and characteristics.

    PubMed

    Chen, Fa-Ming; Zhao, Yi-Min; Sun, Hai-Hua; Jin, Tao; Wang, Qin-Tao; Zhou, Wei; Wu, Zhi-Fen; Jin, Yan

    2007-03-12

    Novel thermomechanical hydrogel scaffolds containing our previously prepared microspheres loaded with bone morphogenetic proteins (BMP) were successfully generated by radical crosslinking and low dose gamma-irradiation from combination of two kind of biomaterials: glycidyl methacrylated dextran (Dex-GMA) and gelatin. The structure of those resulting smart hybrid hydrogels was evaluated by mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM) analyses, and as a function of the degree of Dex-GMA's substitution (DS), the proportion between Dex-GMA and gelatin, and the initial polyethyleneglycol (PEG) concentration used in the preparation of the hydrogels. The swelling and degradation properties and the temperature-sensitive drug release manner were determined by dynamic evaluation methods in vitro, and the gel content was also calculated. MIP analysis showed that by systematically altering the preparation parameters, the overall networks were clearly macroporous with pore sizes ranging from 5.6+/-4.2 to 37.7+/-13.7 microm. As expected, the pore size decreased as DS and initial PEG concentration increased, whereas the opposite was found for the gel content. Moreover, the porosity values ranged from 73.7+/-12.4% up to 89.6+/-6.3%. The SEM results also showed the inter-connective pores as well as microspheres encased into their porous structure of those hydrogels. The swelling and degradation properties of the resultant hydrogels varied according to the DS of Dex-GMA and initial PEG concentration, while the proportion between Dex-GMA and gelatin had no significant influence on those characterizations. By changing the composition ratio of the two precursors, the phase transition temperature (lower critical solution temperature, LSCT) of the hydrogel scaffolds could also be adjusted to be or near the body temperature, so BMP release from microsphere-hydrogel compounds could be accordingly controlled and the release period could be varied from 18 to

  17. Methyl methacrylate

    Integrated Risk Information System (IRIS)

    TOXICOLOGICAL REVIEW of METHYL METHACRYLATE ( CAS No . 80 - 62 - 6 ) In Support of Summary Information on the Integrated Risk Information System ( IRIS ) January 1998 U.S . Environmental Protection Agency Washington , DC TABLE OF CONTENTS DISCLAIMER . . . . . . . . . . . . . . . . . . . . . . . . .

  18. Silicate-substituted calcium phosphate as a bone void filler after kyphoplasty in a young patient with multiple compression fractures due to osteogenesis imperfecta variant: case report.

    PubMed

    Hardenbrook, Mitchell A; Lombardo, Sergio R

    2006-12-15

    Kyphoplasty can be used to treat compression fractures resulting from a variety of causes. The use of polymethyl methacrylate (PMMA) in conjunction with kyphoplasty has many risks and potential complications, however, particularly in the younger patient population. Silicate-substituted calcium phosphate (Actifuse Synthetic Bone Graft; Apatech, Ltd.) is an alternative to PMMA that provides immediate pain relief and the ability to heal and incorporate within the vertebral body.

  19. Dynamic void behavior in polymerizing polymethyl methacrylate cement.

    PubMed

    Muller, Scott D; McCaskie, Andrew W

    2006-02-01

    Cement mantle voids remain controversial with respect to survival of total hip arthroplasty. Void evolution is poorly understood, and attempts at void manipulation can only be empirical. We induced voids in a cement model simulating the constraints of the proximal femur. Intravoid pressure and temperature were recorded throughout polymerization, and the initial and final void volumes were measured. Temperature-dependent peak intravoid pressures and void volume increases were observed. After solidification, subatmospheric intravoid pressures were observed. The magnitude of these observations could not be explained by the ideal gas law. Partial pressures of the void gas at peak pressures demonstrated a dominant effect of gaseous monomer, thereby suggesting that void growth is a pressure-driven phenomenon resulting from temperature-dependent evaporation of monomer into existing trapped air voids.

  20. Craniofacial Prosthetic Reconstruction Using Polymethyl Methacrylate Implant: A Case Report.

    PubMed

    Simon, Paul; Mohan, Jayashree; Selvaraj, Sunantha; Saravanan, B S; Pari, Parikodaiarasan

    2014-12-01

    Large cranial defects of complex geometric shapes are challenging to reconstruct. The cranial implants has to be fabricated prior to the cranioplastic surgery. The ideal material for cranial implant has to be inert, light weight, easy to fit and adaptable to the defect, offering the best aesthetic and functional results. Here is a clinical case report of a patient who was operated for osteomyelitis in the parieto-temporal region. The defect was reconstructed with heat cure polymethylmethacrylate (PMMA). Operative closure of the defect was facilitated with ligature titanium wires with minimal prosthesis contouring. The heat cure PMMA cranial implant is a safe, easy and economic alternative with great adaptability to cranial vault defects. The cosmetic results in this patient was excellent. No post-operative complications occurred.

  1. Computational Studies of Ultraviolet Ablation of Poly(methyl methacrylate)

    DTIC Science & Technology

    2007-01-01

    simulations via an algorithm similar to the kinetic Monte Carlo (KMC) method [18]. The photochemical processes and the various exothermic radical...Appl. Phys. 88 1281 [7] Zhigilei L V, Leveugle E, Garrison B J, Yingling Y G and Zeifman M I 2003 Chem. Rev. 103 321 [8] Zhigilei L V, Kodali P B S...1631 [14] Zhigilei L V and Garrison B J 1999 Appl. Phys. A 69 S75 [15] Zhigilei L V, Kodali P B S and Garrison B J 1997 Chem. Phys. Lett. 276 269

  2. Ammonium methacrylate

    Integrated Risk Information System (IRIS)

    Ammonium methacrylate ; CASRN 16325 - 47 - 6 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcin

  3. Painful pathologic fracture of the humerus: percutaneous osteoplasty with bone marrow nails under hybrid computed tomography and fluoroscopic guidance.

    PubMed

    Anselmetti, Giovanni Carlo; Manca, Antonio; Chiara, Gabriele; Tutton, Sean; Iussich, Gabriella; Gino, Giancarlo; Grignani, Giovanni; Ortega, Cinzia; Moselli, Nora; Regge, Daniele

    2011-07-01

    A case of a 75-year-old patient with a painful pathologic humeral shaft fracture, with unacceptably high surgical risk and unsatisfactory analgesia is reported. In this case, impaired arm function and persistent pain with conservative management resulted in a poor quality of life. Palliation with image-guided percutaneous osteoplasty was considered. Because of potential cement leakage, inadequate fracture reduction, the site of the fracture, and the mobility of the joints in that area, image-guided percutaneous delivery of metallic bone marrow nails implanted together with polymethyl methacrylate (PMMA) osteoplasty was performed. This procedure achieved humeral shaft stabilization, bone fragment alignment, fracture reduction, and pain relief.

  4. Synthesis of photosensitive poly(methyl methacrylate-co-glycidyl methacrylate) for optical waveguide devices

    NASA Astrophysics Data System (ADS)

    Fei, Xu; Shi, Yuan; Cao, Yang

    2010-08-01

    Photosensitive poly(MMA-co-GMA) for optical waveguide was synthesized, and the refractive index of the polymer film was tuned in the range of 1.481-1.588 at 1550 nm by mixing with bis-phenol-A epoxy resin. The film, which was made by spinning coated the poly(MMA-co-GMA) with photo initiator, had good UV light lithograph sensitivity, high glass transition temperature ( T g : 153°C, after crosslinking) and good thermal stabilities ( T d : up to 324°C, after crosslinking). The optical waveguides with very smooth top surface were fabricated from the resulting polymer by direct UV exposure and chemical development. For waveguides with cladding, the propagation losses of the channel waveguides were measured to be below 3 dB/cm at 1550 nm.

  5. Surgical management of metastatic long bone fractures: principles and techniques.

    PubMed

    Scolaro, John Alan; Lackman, Richard D

    2014-02-01

    Management of metastatic long bone fractures requires identification of the lesion and the use of sound fracture fixation principles to relieve pain and restore function. The treating surgeon must understand the principles of pathologic fracture fixation before initiating treatment. Because these fractures occur in the context of a progressive systemic disease, management typically involves a multidisciplinary approach. When considering surgical stabilization of these fractures, the abnormal (or absent) healing environment associated with diseased bone and the overall condition of the patient must be taken into account. The goal of surgery is to obtain a rigid mechanical construct, which allows for early mobility and weight bearing. This can be achieved using internal fixation with polymethyl methacrylate cement or segmental resection and joint reconstruction. Prosthetic joint arthroplasty is a more reliable means of fracture management when insufficient bone is present for fixation. Prophylactic stabilization of impending pathologic fractures can reduce the morbidity associated with metastatic lesions.

  6. Methyl methacrylate levels in orthopedic surgery: comparison of two conventional vacuum mixing systems.

    PubMed

    Jelecevic, Jasmin; Maidanjuk, Stanislaw; Leithner, Andreas; Loewe, Kai; Kuehn, Klaus-Dieter

    2014-05-01

    Poly-methyl methacrylate bone cements contain methyl methacrylate (MMA), which is known for its sensitizing and toxic properties. Therefore, in most European countries and in the USA, guidelines or regulations exist for occupational exposures. The use of vacuum mixing systems can significantly reduce airborne MMA concentrations during bone setting. Our goal was to test two commonly used vacuum mixing systems (Palamix(®) and Optivac(®)) using Palacos(®) R bone cement for their effectiveness at preventing MMA vapor release in a series of standardized trials in a laboratory as well as in an operating theatre. MMA was quantified every second over a period of 3 min using a photoionization detector (MiniRAE(®) 3000) device positioned in the breathing area of the user. Significant differences in MMA mean vapor concentrations over 180 s were observed in the two experimental spaces, with the highest mean concentrations (7.61 and 7.98 ppm for Palamix(®) and Optivac(®), respectively) observed in a laboratory with nine air changes per hour and the lowest average concentrations (1.06 and 1.12 ppm for Palamix(®) and Optivac(®), respectively) in an operating theatre with laminar flow ventilation and 22 air changes per hour. No significant differences in overall MMA concentrations were found between the two vacuum mixing systems in either location. Though, differences were found between both systems during single mixing phases. Thus, typical handling of MMA in orthopedic procedures must be seen as not harmful as concentrations do not reach the short-term exposure limit of 100 ppm. Additionally, laminar airflow seems to have an influence on lowering MMA concentrations in operation theatres.

  7. Evidence of MRSE on a gentamicin and vancomycin impregnated polymethyl-methacrylate (PMMA) bone cement spacer after two-stage exchange arthroplasty due to periprosthetic joint infection of the knee

    PubMed Central

    2014-01-01

    Background Periprosthetic joint infections (PJI) are often treated by two stage exchange with the use of an antibiotic impregnated spacer. Most of the two-stage exchange algorithms recommend the implantation of an antibiotic-impregnated spacer during the first stage for a period of 2–24 weeks before reimplantation of the new prosthesis. For the spacer to have a therapeutic effect, the local antibiotic concentration must be greater than the minimal inhibition concentration (MIC) against the pathogens causing the PJI. It must remain so for the entire spacer period, otherwise recurrence of infection or resistances might occur. The question as to whether a sufficient concentration of antibiotics in vivo is reached for the entire spacer period has not been answered satisfactorily. Case presentation We here present a case of a histologically confirmed chronic PJI 20 month after primary arthroplasty. The primary knee arthroplasty was performed due to osteoarthritis of the joint. Initial assessment did not detect a causative pathogen, and two stage exchange with a vancomycin-gentamycin impregnated spacer was performed. At the time of reimplantation, sonication of the explanted spacer revealed a multi-resistant strain of staphylococcus epidermidis on the device and in the joint. Adaption of the therapy and prolonged treatment successfully eradicated the infection. Conclusion According to the authors’ knowledge, the case presented here confirms for the first time the surface contamination (proven through sonication) of a vancomycin-/gentamicin- impregnated Vancogenx®-spacer with a MRSE after ten weeks of implantation. This case study demonstrates the difficulties still associated with the diagnostics of PJI and the published different two stage treatment regimes with the use of antibiotic impregnated spacers. PMID:24641471

  8. Reconstruction of Frontal Bone With Custom-Made Prosthesis Using Rapid Prototyping.

    PubMed

    Florentino, Vinícius Gabriel Barros; Mendonça, Diego Santiago de; Bezerra, Ariel Valente; Silva, Leonardo de Freitas; Pontes, Rafael Figueirêdo; Melo, Carlos Vinícius Mota de; Mello, Manoel de Jesus Rodrigues; de Aguiar, Andréa Silvia Walter

    2016-06-01

    Frontal bone fracture treatment is still an issue of research in craniofacial surgery and neurosurgery. The aims of the treatment are to reduce the complication risks and to keep the aesthetic of the face. Before the management of this fracture type, it is necessary to consider the permanence or not of the frontal sinus function. Rapid prototyping has been an aid tool on planning and simulation of the surgical procedure, improving the diagnostic quality and the implant manufacture, beyond reducing the operative time. Among the used materials on treatment of these fractures, titanium mesh shows large versatility and ease of handling. Poly(methyl methacrylate) has been used in defects of partial thickness or irregularities on cranial surface. The aim of this study is to report a case of a patient presenting sequelae of large fracture of anterior wall of frontal bone, treated by a titanium mesh associated with the customized poly(methyl methacrylate) implant from the rapid prototyping. It could be concluded that the use of this technique showed itself effective on patient treatment, and rapid prototyping demonstrated being a valuable tool showing predictable and satisfactory results.

  9. Potent antimicrobial activity of bone cement encapsulating silver nanoparticles capped with oleic acid.

    PubMed

    Prokopovich, Polina; Köbrick, Mathias; Brousseau, Emmanuel; Perni, Stefano

    2015-02-01

    Bone cement is widely used in surgical treatments for the fixation for orthopaedic devices. Subsequently, 2-3% of patients undergoing these procedures develop infections that are both a major health risk for patients and a cost for the health service providers; this is also aggravated by the fact that antibiotics are losing efficacy because of the rising resistance of microorganisms to these substances. In this study, oleic acid capped silver nanoparticles (NP) were encapsulated into Poly(methyl methacrylate) (PMMA)-based bone cement samples at various ratios. Antimicrobial activity against Methicillin Resistant Staphylococcus aureus, S. aureus, Staphylococcus epidermidis, Acinetobacter baumannii was exhibited at NP concentrations as low as 0.05% (w/w). Furthermore, the mechanical properties and cytotoxicity of the bone cement containing these NP were assessed to guarantee that such material is safe to be used in orthopaedic surgical practice.

  10. Osteoblast cell death on methacrylate polymers involves apoptosis.

    PubMed

    Gough, J E; Downes, S

    2001-12-15

    The success of an implant depends on the implant-tissue interface. There are many causes of implant failure, one of which is tissue necrosis. The aim of this in vitro study was to determine whether cell death of primary human osteoblasts (implant site specific cells) occurred by apoptosis (a form of programmed cell death) on two methacrylate polymers. Cells were cultured on poly(ethyl methacrylate)/tetrahydrofurfuryl methacrylate and poly(methyl methacrylate in the form of 13-mm discs, in conditioned medium containing leachable monomer and in the presence of various concentrations of monomer itself in the culture medium. It was found that monomer and leached monomer caused apoptosis of human osteoblast cells in this system. Tetrahydrofurfuryl methacrylate monomer was found to be more toxic than currently used monomer methylmethacrylate. Preincubation of polymers in serum containing medium was found to increase the biocompatibility of the polymers. High levels of apoptosis occurred on polymer used directly after polymerization. Apoptosis levels were decreased after polymer was incubated at 60 degrees C overnight or for 3 days. Apoptosis therefore may occur in cells at the implant site in vivo.

  11. Impact strength of a modified continuous glass fiber--poly(methyl methacrylate).

    PubMed

    Vallittu, P K; Narva, K

    1997-01-01

    The effect of fiber reinforcement of autopolymerizing poly(methyl methacrylate) was investigated. The impact strength of continuous E-glass fiber-poly(methyl methacrylate) composite was determined. Rectangular test specimens (n = 10 per group) were modified by incorporating an additional fiber reinforcement of untreated E-glass fibers, silanized E-glass fibers, or aramid fibers in the test specimens. Controls were either unreinforced or reinforced from the middle of the test specimen only. The impact strength of the specimens was measured by using a charpy-type pendulum impact tester after the specimens had been stored in water at 37 degrees C for 4 weeks. After the impact strength test, the length of the delamination of poly(methyl methacrylate) from the fibers was measured and plotted to the impact strength of the test specimens by using a linear regression model. The impact strength of unreinforced autopolymerizing poly(methyl methacrylate) was 7.8 kl/m2, while incorporation of glass fiber reinforcement with a fiber concentration of 12.4 wt% increased the impact strength to 74.7 kl/m2 (P = .000). The additional fiber reinforcement of the test specimen did not affect the impact strength (P = .363). Delamination negatively correlated with the impact strength of the test specimens (r = -.72, P = .000). The results of this study suggest that glass fiber reinforcement enhanced the impact strength of autopolymerizing poly(methyl methacrylate), while the use of additional fiber reinforcement made of aramid or glass fibers in the test specimens did not have an effect on the impact strength.

  12. Levofloxacin loaded mesoporous silica microspheres/nano-hydroxyapatite/polyurethane composite scaffold for the treatment of chronic osteomyelitis with bone defects.

    PubMed

    Wang, Qi; Chen, Cheng; Liu, Wen; He, Xiaoqiang; Zhou, Nian; Zhang, Dongli; Gu, Hongchen; Li, Jidong; Jiang, Jiaxing; Huang, Wei

    2017-02-02

    Chronic osteomyelitis is a prolonged persistent disease accompanied by bone destruction and sequestrum formation, it is very difficult to treat. Antibiotic loaded polymethyl methacrylate (PMMA) has been used in clinical. However, when PMMA was implanted in the body, the deficiencies is that it is non-biodegradable and a second operation is needed. Here, we synthesize a novel levofloxacin loaded mesoporous silica microspheres/nano-hydroxyapatite/polyurethane composite scaffolds, and evaluated the therapeutic effect in treating chronic osteomyelitis with bone defects in rabbit model compared with bulk PMMA. X-ray, Micro CT, gross pathology as well as immunohistochemical staining were performed at predesignated time points (1, 3, 6 and 12 weeks). Our results demonstrated that the efficiency of mesoporous silica microspheres/nano-hydroxyapatite/polyurethane composite scaffolds loaded with 5 mg levofloxacin was much better at treating bone defects than the other groups. This novel synthetic scaffold may provide a solution for the treatment of chronic osteomyelitis.

  13. Levofloxacin loaded mesoporous silica microspheres/nano-hydroxyapatite/polyurethane composite scaffold for the treatment of chronic osteomyelitis with bone defects

    PubMed Central

    Wang, Qi; Chen, Cheng; Liu, Wen; He, Xiaoqiang; Zhou, Nian; Zhang, Dongli; Gu, Hongchen; Li, Jidong; Jiang, Jiaxing; Huang, Wei

    2017-01-01

    Chronic osteomyelitis is a prolonged persistent disease accompanied by bone destruction and sequestrum formation, it is very difficult to treat. Antibiotic loaded polymethyl methacrylate (PMMA) has been used in clinical. However, when PMMA was implanted in the body, the deficiencies is that it is non-biodegradable and a second operation is needed. Here, we synthesize a novel levofloxacin loaded mesoporous silica microspheres/nano-hydroxyapatite/polyurethane composite scaffolds, and evaluated the therapeutic effect in treating chronic osteomyelitis with bone defects in rabbit model compared with bulk PMMA. X-ray, Micro CT, gross pathology as well as immunohistochemical staining were performed at predesignated time points (1, 3, 6 and 12 weeks). Our results demonstrated that the efficiency of mesoporous silica microspheres/nano-hydroxyapatite/polyurethane composite scaffolds loaded with 5 mg levofloxacin was much better at treating bone defects than the other groups. This novel synthetic scaffold may provide a solution for the treatment of chronic osteomyelitis. PMID:28150731

  14. The effect of ethanol on acrylic bone cement.

    PubMed

    Bettencourt, A; Calado, A; Amaral, J; Vale, F M; Rico, J M T; Monteiro, J; Montemor, M F; Ferreira, M G S; Castro, M

    2002-07-08

    Prosthesis loosening is a major problem associated with the use of poly(methyl methacrylate) (PMMA) bone cement that may be related to a peri-implant vacuolisation commonly observed at bone-cement interface. Methyl methacrylate (MMA) monomer may be one of the cement components partly responsible for the mentioned vacuolisation due to a cytotoxic effect associated to this compound. Alcoholism has been related to bone necrosis in predisposed individuals. Furthermore, ethanol has been shown to clean material with adherent cement debris during cleaning procedure in laboratory. Consequently, we have decided to study whether ethanol will also be related to an increased liberation of MMA from the polymer matrix. 'In vitro' release studies using PMMA plates were conducted to access the role of ethanol on the liberation of the monomer. Contact angle measurements and surface tension estimation were also carried out in order to find a possible effect of ethanol on surface cement properties. Results suggest that ethanol, even in small quantities, enhances the leaching of the monomer from the polymer matrix, but does not considerably change the wettability properties of the cement surface.

  15. Nanotopographic Substrates of Poly (Methyl Methacrylate) Do Not Strongly Influence the Osteogenic Phenotype of Mesenchymal Stem Cells In Vitro

    PubMed Central

    Janson, Isaac A.; Kong, Yen P.; Putnam, Andrew J.

    2014-01-01

    The chemical, mechanical, and topographical features of the extracellular matrix (ECM) have all been documented to influence cell adhesion, gene expression, migration, proliferation, and differentiation. Topography plays a key role in the architecture and functionality of various tissues in vivo, thus raising the possibility that topographic cues can be instructive when incorporated into biomaterials for regenerative applications. In the literature, there are discrepancies regarding the potential roles of nanotopography to enhance the osteogenic phenotype of mesenchymal stem cells (MSC). In this study, we used thin film substrates of poly(methyl methacrylate) (PMMA) with nanoscale gratings to investigate the influence of nanotopography on the osteogenic phenotype of MSCs, focusing in particular on their ability to produce mineral similar to native bone. Topography influenced focal adhesion size and MSC alignment, and enhanced MSC proliferation after 14 days of culture. However, the osteogenic phenotype was minimally influenced by surface topography. Specifically, alkaline phosphatase (ALP) expression was not increased on nanotopographic films, nor was calcium deposition improved after 21 days in culture. Ca: P ratios were similar to native mouse bone on films with gratings of 415 nm width and 200 nm depth (G415) and 303 nm width and 190 nm depth (G303). Notably, all surfaces had Ca∶P ratios significantly lower than G415 films. Collectively, these data suggest that, PMMA films with nanogratings are poor drivers of an osteogenic phenotype. PMID:24594848

  16. Acrylates and Methacrylates,

    DTIC Science & Technology

    1987-09-15

    of ethylene and hydrocyanic acid through ethylene cyanohydrin. In the presence of basic catalysts ethylene oxide easily adds hydrocyanic acid with the...of synthesis of methacrylates. At present methacrylates are obtained in the industry by continuous method from acetone and hydrocyanic acid through...acetone cyanohydrin. The addition/connection to it of hydrocyanic acid with the formation of acetone cyanohydrin is one of the most important reactions

  17. Poly(methacrylic acid-co-methyl methacrylate) beads promote vascularization and wound repair in diabetic mice.

    PubMed

    Martin, Daniel C; Semple, John L; Sefton, Michael V

    2010-05-01

    Topical application of beads made from poly(methacrylic acid-co-methyl methacrylate) (45 mol % methacrylic acid, MAA) increased the number of blood vessels and improved 1.5 x 1.5 cm full thickness wound closure in a diabetic mouse (db/db) model. Three groups were compared: MAA beads, control poly(methyl methacrylate) beads (PMMA), and no bead blanks. MAA bead treatment significantly increased percent wound closure at all timepoints (7, 14, and 21 days) with MAA bead-treated wounds almost closed at day 21 (91 +/- 5.4% MAA vs. 79 +/- 3.2% PMMA or 76 +/- 4.8% no beads; p < 0.05). This was consistent with the expected significant increase in vascularity in the MAA group at days 7 and 14. For example at day 14, MAA bead-treated wounds had a vascular density of 22.7 +/- 2.6 vessels/hpf compared with 17.0 +/- 2.0 vessels/hpf in the PMMA bead group (p < 0.05). Epithelial gap and migration measurements suggested that the increased vascularity leads to enhanced epithelial cell migration as a principal means of wound closure. Although studies are underway to elucidate the mechanism of this angiogenic response, the results presented here support the notion that such materials, perhaps in other forms, may be useful in wound care or in other situations where vascularity is to be enhanced without the use of exogenous growth factors.

  18. Dual-Responsive pH and Temperature Sensitive Nanoparticles Based on Methacrylic Acid and Di(ethylene glycol) Methyl Ether Methacrylate for the Triggered Release of Drugs.

    PubMed

    Khine, Yee Yee; Jiang, Yanyan; Dag, Aydan; Lu, Hongxu; Stenzel, Martina H

    2015-08-01

    A series of thermo-and pH-responsive poly(methyl methacrylate)-block-poly[methacrylic acid-co-di(ethylene glycol) methyl ether methacrylate] PMMA-b-P[MAA-co-DEGMA] block copolymers were synthesized by RAFT polymerization and self-assembled into micelles. The molar ratio of MAA was altered from 0-12% in order to modulate the lower critical solution temperature (LCST) of PDEGMA. The release of the drug albendazole from the micelle was strongly dependent on the temperature and the LCST value of the polymer. Systems below the LCST released the drug slowly while increasing the temperature above the LCST or decreasing the pH value to 5 resulted in the burst-like release of the drug. ABZ delivered in this pH-responsive drug carrier had a higher toxicity than the free drug or the drug delivered in a non-responsive drug carrier.

  19. In vivo performance of a reduced-modulus bone cement

    NASA Astrophysics Data System (ADS)

    Forehand, Brett Ramsey

    Total joint replacement has become one of the most common procedures in the area of orthopedics and is often the solution in patients with diseased or injured hip joints. Component loosening is a significant problem and is primarily caused by bone resorption at the bone-cement interface in cemented implants. It is our hypothesis that localized shear stresses are responsible for the resorption. It was previously shown analytically that local stresses at the interface could be reduced by using a cement of lower modulus. A new reduced modulus cement, polybutyl methylmethacrylate (PBMMA), was developed to test the hypothesis. PBMMA was formulated to exist as polybutyl methacrylate filler in a polymethyl methacrylate matrix. The success of PBMMA cement is based largely on the fact that the polybutyl component of the cement will be in the rubbery state at body temperature. In vitro characterization of the cement was undertaken previously and demonstrated a modulus of approximately one-eighth that of conventional bone cement, polymethyl methacrylate (PMMA) and increased fracture toughness. The purpose of this experiment was to perform an in vivo comparison of the two cements. A sheep model was selected. Total hip arthroplasty was performed on 50 ewes using either PBMMA or PMMA. Radiographs were taken at 6 month intervals. At one year, the contralateral femur of each sheep was implanted so that each animal served as its own control, and the animals were sacrificed. The stiffness of the bone-cement interface of the femoral component within the femur was assessed by applying a torque to the femoral component and demonstrated a significant difference in loosening between the cements when the specimens were tested in external rotation (p < 0.007). Evaluation of the mechanical data also suggests that the PBMMA sheep had a greater amount of loosening for each subject, 59% versus 4% for standard PMMA. A radiographic analysis demonstrated more signs of loosening in the PMMA series

  20. Injectable acrylic bone cements for vertebroplasty with improved properties.

    PubMed

    Carrodeguas, Raúl García; Lasa, Blanca Vázquez; Del Barrio, Julio San Román

    2004-01-15

    Currently commercially available acrylic bone cements lack adequate radiopacity and viscosity when they are used in percutaneous vertebroplasty (PVP). In this work improved formulations of radiopaque and injectable poly(methyl methacrylate) bone cements were prepared with different amounts (10-50 wt.%) of BaTiO3 or SrTiO3 particles as the radiopaque agent. Two sets of cements were prepared by using untreated or silanated radiopaque particles, respectively. The influence of the content and nature of the radiopaque agent as well as its silanation with 3-(trimethoxysilyl) propyl methacrylate (gamma-MPS), on the curing parameters, residual monomer content, radiopacity, mechanical properties, and injectability of the resulting materials, was examined. Doughing and setting times, maximum temperature, and compressive strength of all formulations fulfilled the requirements of standard specifications, with values of peak temperature in the range 57-72 degrees C and those of compressive strength between 114 and 135 MPa. Formulations containing at least 20 wt.% BaTiO3 or SrTiO3 had radiopacities equal to or greater than that corresponding to 2 mm of Al as required for surgical plastics. Injectability of any of the formulations provided 75-80 wt.% of the total mass manually injected through a conventional biopsy needle 4 min after mixing. Silanation of the BaTiO3 or SrTiO3 particles led to formulations with improved mechanical properties and injectability compared to those obtained with the untreated fillers.

  1. Surface studies on acrylic bone cement.

    PubMed

    Bettencourt, A; Calado, A; Amaral, J; Alfaia, A; Vale, F M; Monteiro, J; Montemor, M F; Ferreira, M G S; Castro, M

    2004-06-18

    Poly(methyl methacrylate) (PMMA) is used to fill the gap between the prosthesis and the surrounding bone in cemented arthroplasties. Biocompatibility problems related to bone cement application limit the clinical success of these cemented arthroplasties. Being the cement surface in close connection with the living bone, it is reasonable to assume that surface properties such as, surface composition and surface energy, will play a role in the biomaterial performance. X-ray photoelectron spectroscopy (XPS) analysis and surface energy studies were carried out during 4 months, in order to assess a possible correlation between aging time and surface changes. The aging of PMMA, in a biological model fluid, strongly influences the composition and wettability of the cement surface. These changes may be explained through the hydrolysis of PMMA ester groups and the subsequent hydrogen bonding. Although our study does not exactly reproduce the in vivo environment surrounding a prosthesis, it suggests that the changes in the composition and wettability of the surface may modulate the host response towards the implant, thus contributing to its loosening.

  2. Biodegradable beta-Tri-Calciumphosphate/hydroxyethyl methacrylate enhanced three component bone adhesive demonstrates biocompatibility without evidence of systemic toxicity in a rabbit model.

    PubMed

    Bauer, Natali B; Brinke, Nina; Heiss, Christian; Skorupa, Agnes B; Peters, Fabian; Kraus, Ralf; Schnettler, Reinhard; Moritz, Andreas

    2009-08-01

    Bone gluing is an attractive surgical technique; however, its use in patients is hampered by a variety of side effects. Therefore, it was the aim of this ethically approved study to evaluate a novel biodegradable beta-Tri-Calciumphosphate (beta-TCP, Cerasorb)-enhanced bone adhesive regarding its toxicity and biocompatibility in a rabbit model. Fifty healthy New Zealand White rabbits were assigned in the study (n = 21) and sham-operated control group (n = 29). In the study group, a cylindrical part (4.6 x 10.0 mm) of the proximal tibia and distal femur was removed, reimplanted, and bone adhesive was applied. Blinded physical examination and sampling for hematology, clinical chemistry, and acute phase proteins (haptoglobin, C-reactive protein (CRP)) was performed before surgery and after 12, 24, 48, 72, 240, and 504 h. Significant findings of the physical examination included a slightly higher grading of warmth (p = 0.0019) and pain (p < 0.0001) of the wound 240 h after surgery in the study group. No significant differences between albumin, haptoglobin, CRP, and urea concentrations in both groups were evident, whereas the study group demonstrated significantly lower leukocyte count, total protein, and globulin concentrations (p < 0.0001). As expected, both groups showed a marked transient increase in muscle enzymes (Creatine Kinase and Aspartate Aminotransferase) following the surgery (p < 0.0001). Twelve to 24 h after surgery, a significant decrease in ionized calcium from 1.38 +/- 0.12 mmol/L to 1.06 +/- 0.13 mmol/L was noted in the study group (p < 0.0001). The results clearly indicated that the novel beta-TCP-enhanced bone adhesive showed good biocompatibility without significant evidence of acute or subacute local or systemic toxicity.

  3. Scaffolds of hydroxyl apatite nanoparticles disseminated in 1, 6-diisocyanatohexane-extended poly(1, 4-butylene succinate)/poly(methyl methacrylate) for bone tissue engineering.

    PubMed

    Kaur, Kulwinder; Singh, K J; Anand, Vikas; Bhatia, Gaurav; Kaur, Raminderjit; Kaur, Manpreet; Nim, Lovedeep; Arora, Daljit Singh

    2017-02-01

    Poly(1, 4-butyl succinate) extended 1, 6-diisocyanatohexane (PBSu-DCH) polymers and Polymethylmethacrylate (PMMA) scaffolds decorated with nano hydroxyl apatite have been prepared and characterized for regeneration of bone in cranio-maxillofacial region. Synthesized scaffolds revealed good response in bone regeneration and excellent cell viability in comparison to commercial available glass plate, which lead to better proliferation of MG-63 cell lines. Additionally, they demonstrate high porosity and excellent water retention ability. Moreover, controlled degradation (in pH=7.4) and sustained drug release in pH (4.5 and 7.4) are advantages of these scaffolds to serve as delivery vehicles for therapeutic drugs. Samples also provide the protection against Escherichia coli and Methicillin Resistant Staphylococcus aureus microorganisms which can be helpful for quick recovery of the patient. In-vitro inflammatory response has been assessed via adsorption of human plasma/serum proteins on the surface of the scaffolds. Results suggest that prepared scaffolds have good bone regeneration ability and provide friendly environment for the cell growth with the additional advantage of protection of the surrounding tissues from microbial infection. With all these features, it is speculated that these scaffolds will have wide utility in the area of tissue engineering and regenerative medicine.

  4. Bone attachment to glass-fibre-reinforced composite implant with porous surface.

    PubMed

    Mattila, R H; Laurila, P; Rekola, J; Gunn, J; Lassila, L V J; Mäntylä, T; Aho, A J; Vallittu, P K

    2009-06-01

    A method has recently been developed for producing fibre-reinforced composites (FRC) with porous surfaces, intended for use as load-bearing orthopaedic implants. This study focuses on evaluation of the bone-bonding behaviour of FRC implants. Three types of cylindrical implants, i.e. FRC implants with a porous surface, solid polymethyl methacrylate (PMMA) implants and titanium (Ti) implants, were inserted in a transverse direction into the intercondular trabeculous bone area of distal femurs and proximal tibias of New Zealand White rabbits. Animals were sacrificed at 3, 6 and 12 weeks post operation, and push-out tests (n=5-6 per implant type per time point) were then carried out. At 12 weeks the shear force at the porous FRC-bone interface was significantly higher (283.3+/-55.3N) than the shear force at interfaces of solid PMMA/bone (14.4+/-11.0 N; p<0.001) and Ti/bone (130.6+/-22.2N; p=0.001). Histological observation revealed new bone growth into the porous surface structure of FRC implants. Solid PMMA and Ti implants were encapsulated mostly with fibrous connective tissue. Finite element analysis (FEA) revealed that porous FRC implants had mechanical properties which could be tailored to smooth the shear stress distribution at the bone-implant interface and reduce the stress-shielding effect.

  5. Development of advanced biantibiotic loaded bone cement spacers for arthroplasty associated infections.

    PubMed

    Parra-Ruíz, F J; González-Gómez, A; Fernández-Gutiérrez, M; Parra, J; García-García, J; Azuara, G; De la Torre, B; Buján, J; Ibarra, B; Duocastella-Codina, L; Molina-Crisol, M; Vázquez-Lasa, B; San Román, J

    2017-02-28

    The incidence increase of infections in patients with hip or knee implants with resistant pathogens (mainly some S. coagulase-negative and gram positive bacteria) demands advanced antibiotic loaded formulations. In this paper, we report the design of new biantibiotic acrylic bone cements for in situ delivery. They include a last generation antibiotic (daptomycin or linezolid) in combination with vancomycin and are performed based on a novel modification of the Palacos R(®) acrylic bone cement, which is based on two components, a liquid (methyl methacrylate) and a solid (polymeric phase). Hence, the solid component of the experimental formulations include 45wt% of microparticles of poly(D,L-lactic-co-glycolic) acid, 55wt% of poly(methyl methacrylate) beads and supplements (10wt-% each) of antibiotics. These formulations provide a selective and excellent control of the local release of antibiotics during a long time period (up to 2 months), avoiding systemic dissemination. The antimicrobial activity of the advanced spacers tested against S. aureus shows that single doses would be enough for the control of the infection. In vitro biocompatibility of cements on human osteoblasts is ensured. This paper is mainly focused on the preparation and characterization of cements and the studies of elution kinetics and bactericidal effects. Developed formulations are proposed as spacers for the treatment of infected arthroplasties, but also, they could be applied in other antibiotic devices to treat relevant bone-related infection diseases.

  6. Basic study of a new denture base resin applying hydrophobic methacrylate monomer.

    PubMed

    Umemoto, K; Kurata, S

    1997-06-01

    To improve the water sorption of poly(methyl methacrylate), new hydrophobic monomers, such as norbonyl and phenyl methacrylate, were studied to determine the resin with lower water sorption with no decrease in mechanical property. Water sorption of the copolymers of the hydrophobic monomers and MMA decreased with the increase in the concentration of the monomers. Compressive and bending strength of the copolymers were higher than that of PMMA, and the elastic modulus in bending was the same as that of PMMA. In addition, the transverse-deflection values satisfied ADA specifications. Dynamic mechanical thermal analysis of the copolymers showed a similar tendency to that of PMMA in spite of the introduction of bulky groups, such as norbonyl and phenyl, in the polymer molecule. The polymerization shrinkage in volume was in the following order: norbonyl < phenyl < methyl methacrylate.

  7. Evaluation of alternate routes for the synthesis of methyl methacrylate

    SciTech Connect

    Spivey, J.J.; Gogate, M.R.; Zoeller, J.R.; Colberg, R.D.; Choi, G.N.

    1998-12-31

    The use of coal-derived syngas to produce high value chemicals is an important means of upgrading this resource. One example of a chemical that can be produced from coal-derived syngas is methyl methacrylate (MMA). Poly-methyl methacrylate is widely used in coatings and in various industrial molded products. The most widely practiced commercial technology for the synthesis of MMA is the acetone cyanohydrin (ACH) process. This process requires handling of large quantities of toxic hydrogen cyanide and generates one mole of ammonium bisulfate waste per mole of MMA. This bisulfate must either be regenerated or discarded, either of which substantially increases the cost. The ACH technology is thus environmentally and economically untenable for any new MMA plant expansions that would be needed to meet increasing demand. The RTI-Eastman-Bechtel research team is developing an alternative, environmentally benign route to MMA consisting of three steps; (step 1) synthesis of a propionate from ethylene, carbon monoxide, and steam, (step 2) condensation of this propionate with formaldehyde, and (step 3) esterification of resulting methacrylic acid with methanol to form MMA. This paper describes the preliminary economics of the overall process compared to other emerging processes, and focuses on step 2, including long term testing of catalysts for the condensation of propionic acid with formaldehyde to form MAA.

  8. Silver methenamine staining for scanning electron microscopy of bone sections containing biomaterials.

    PubMed

    Frayssinet, P; Hanker, J S; Rouquet, N; Primout, I; Giammara, B

    1999-01-01

    Sections of tissue containing orthopedic materials are currently used to study the compatibility of those materials and to perform electron probe microanalysis at the material-tissue interface. Identification of the cells in contact with the material by Scanning electron microscopy (SEM) is of interest. We have developed a method for staining cells and tissue structures embedded in polymethyl methacrylate with silver methenamine once the sections have been obtained. Sections were prepared by grinding, and the silver methenamine was applied after oxidation with periodic acid. The procedure was carried out in a microwave oven. Backscatter SEM showed staining of the cell nucleus membrane, chromatin, the nuclear organizers, and the chromosomes of dividing cells. The cytoplasm and the cytoplasmic membrane were also stained. Collagen fibers of the extracellular matrix and the mineralized matrix of bone were labeled. Material particles in the macrophages were easily recognizable and Energy-Dispersive Spectrometer were not impaired by the presence of silver in the preparation.

  9. Antibiotic-eluting hydrophilized PMMA bone cement with prolonged bactericidal effect for the treatment of osteomyelitis.

    PubMed

    Oh, Eun Jo; Oh, Se Heang; Lee, In Soo; Kwon, Oh Soo; Lee, Jin Ho

    2016-05-01

    Osteomyelitis is still considered to be one of the major challenges for orthopedic surgeons despite advanced antiseptic surgical procedures and pharmaceutical therapeutics. In this study, hydrophilized poly(methyl methacrylate) (PMMA) bone cements containing Pluronic F68 (EG79PG28EG79) as a hydrophilic additive and vancomycin (F68-VAcements) were prepared to allow the sustained release of the antibiotic for adequate periods of time without any significant loss of mechanical properties. The compressive strengths of the bone cements with Pluronic F68 compositions less than 7 wt% were not significantly different compared with the control vancomycin-loaded bone cement (VAcement). TheF68 (7 wt%)-VAcement showed sustained release of the antibiotic for up to 11 weeks and almost 100% release from the bone cement. It also prohibited the growth ofS. aureus(zone of inhibition) over six weeks (the required period to treat osteomyelitis), and it did not show any notable cytotoxicity. From an animal study using a femoral osteomyelitis rat model, it was observed that theF68 (7 wt%)-VAcement was effective for the treatment of osteomyelitis, probably as a result of the prolonged release of antibiotic from the PMMA bone cement. On the basis of these findings, it can be suggested that the use of Pluronic F68 as a hydrophilic additive for antibiotic-eluting PMMA bone cement can be a promising strategy for the treatment of osteomyelitis.

  10. Biomimetic potential of some methacrylate-based copolymers: a comparative study.

    PubMed

    Zecheru, Teodora; Filmon, Robert; Rusen, Edina; Mărculescu, Bogdan; Zerroukhi, Amar; Cincu, Corneliu; Chappard, Daniel

    2009-11-01

    Preparation of new biocompatible materials for bone recovery has consistently gained interest in the last few decades. Special attention was given to polymers that contain negatively charged groups, such as phosphate, carboxyl, and sulfonic groups toward calcification. This present paper work demonstrates that other functional groups present also potential application in bone pathology. New copolymers of 2-hydroxyethyl methacrylate with diallyldimethylammonium chloride (DADMAC), glycidyl methacrylate (GlyMA), methacrylic acid (MAA), 2-methacryloyloxymethyl acetoacetate (MOEAA), 2-methacryloyloxyethyltriethylammonium chloride (MOETAC), and tetrahydrofurfuryl methacrylate (THFMA) were obtained. The copolymers were characterized by FTIR, swelling potential, and they were submitted to in vitro tests for calcification and cytotoxicity evaluation. GlyMA and MOETAC-containing copolymers show promising results for further in vivo mineralization tests, as a potential alternative to the classical bone grafts, in bone tissue engineering.

  11. Influence of the modification of P/L ratio on a new formulation of acrylic bone cement.

    PubMed

    Pascual, B; Gurruchaga, M; Ginebra, M P; Gil, F J; Planell, J A; Goñi, I

    1999-03-01

    The use of smaller powder/liquid (P/L) ratio favours the handling and wetting of poly(methyl methacrylate) (PMMA) beads in bone cement formulations. In this paper a P/L ratio of 1.86 is tested to overcome adhesion problems found in hydroxypropyl methacrylate (HPMA) modified bone cements and the influence on bone cement characteristics was analysed. The reduction of the P/L ratio leads to higher temperature peaks and shorter setting times, whereas the residual monomer content increases slightly. Water uptake obeys the diffusion laws, and the introduction of a more hydrophilic monomer gives rise to an increase of this parameter, which does not present significant changes with modification of the P/L ratio. Polymerization shrinkage is slightly greater because of the introduction of higher proportions of monomer in the formulation. Mechanical properties are similar to those obtained with conventional P/L ratios. The analysis of scanning electron microscopy (SEM) reveals an improvement of the adhesion between phases with respect to P/L = 2 formulations.

  12. In Situ Electrosynthesis of Polymethyl Methacrylate Within Ceramic Launch Pad Materials

    NASA Technical Reports Server (NTRS)

    Acevedo, Raul; Cardenas, Henry

    2012-01-01

    Electrokinetic deposition of methylmethacrylate is used to mitigate corrosion in reinforced concrete. The methylmethacrylate (MMA) monomer deposits in the pores in the concrete where it is converted into its polymer, polymethylmethacrylate, thus creating a barrier that also enhances the mechanical properties of the concrete. Previous to the MMA treatment an Electrokinetic deposition is used to transport calcium, sodium and potassium hydroxide particles through the capillary pores of concrete directly to the concrete reinforcement. The intent is to use these compounds as a sacrificial electrode layer during the electrokinetic deposition of methylmethacrylate monomer. Cylindrical reinforced concrete specimens were subjected to electrokinetic treatment and the specimens were tested to characterize porosity reduction and tensile splitting strength showing an increase in the tensile strength. In addition, nine specimens treated electro-kinetically and in long-term atmospheric exposure testing at NASA's Kennedy Space Center, seaside atmospheric exposure test site were tested to determine their corrosion rate.

  13. Fracture toughness of Kevlar 29/poly(methyl methacrylate) composite materials for surgical implantations.

    PubMed

    Pourdeyhimi, B; Robinson, H H; Schwartz, P; Wagner, H D

    1986-01-01

    A study of the fracture behaviour of Kevlar 29 reinforced dental cement is undertaken using both linear elastic and nonlinear elastic fracture mechanics techniques. Results from both approaches--of which the nonlinear elastic is believed to be more appropriate--indicate that a reinforcing effect is obtained for the fracture toughness even at very low fibre content. The flexural strength and modulus are apparently not improved, however, by the incorporation of Kevlar 29 fibres in the PMMA cement, probably because of the presence of voids, the poor fibre/matrix interfacial bonding and unsatisfying cement mixing practice. When compared to other PMMA composite cements, the present system appears to be probably more effective than carbon/PMMA, for example, in terms of fracture toughness. More experimental and analytical work is needed so as to optimize the mechanical properties with respect to structural parameters and cement preparation technique.

  14. Cavitation erosion characteristics of poly(methyl methacrylate) in a rotating disk device

    NASA Technical Reports Server (NTRS)

    Veerabhadra Rao, P.; Rao, N. S. L.; Rao, B. C. S.

    1983-01-01

    The cavitation erosion behavior including the initiation, dynamics and mechanism of damage process on perspex and epoxy resin specimens tested in a rotating disk device were discussed with respect to exposure time. The inception of erosion always took place at the location nearest to the center of rotation of the disk. Subsequently, as exposure time increased, erosion initiated at other locations as well. Light optical photographs and scanning electron micrographs clearly indicate that most of the material loss appears to occur form the networks of cracks due to their interaction and pits indicate particle debris. The optical degradation (loss of transmittance) on perspex was observed to be more on the rear side than on the front side. Previously announced in STAR as N83-11329

  15. Polymethyl methacrylate glow under the influence of runaway electron beams generated in a gas diode

    NASA Astrophysics Data System (ADS)

    Tarasenko, V. F.; Baksht, E. Kh.; Burachenko, A. G.; Beloplotov, D. V.; Kozyrev, A. V.

    2016-11-01

    Spectral and amplitude-time characteristics of PMMA radiation under the impact of runaway electrons with subnanosecond duration are studied. The PMMA radiation spectra for a subnanosecond electron beam pulse duration are determined for the first time. The studies show that radiation of the band with a maximum at about 490 nm the intensity of which decreases toward the short-wave spectral region is recorded in the glow spectra. The glow intensity of this band varies proportionally to the number of electrons in the beam, which allows the possibility of using this radiation for determination of the number of high energy electrons in electron beams.

  16. Biological protein-resistance layer construction of recombinant hirudin on polymethyl methacrylate IOL surface.

    PubMed

    Zheng, Zhiwen; Jiao, Yan; Ren, Li; Wang, Yingjun

    2015-03-01

    In this article, the surface of intraocular len material PMMA was first aminated for activation on which some polar groups generated such as C-N, COO(-), -OH, NH3(+), etc. Then the anticoagulant drugs recombinant hirudin (rH) was grafted with amido bonds to look forward to resist the adsorption of nonspecific protein or cells in tear, even the cataract. The detailed analysis and discussion about the grafting quantity, molography, wettability, electric charges, chemical structure, and the dynamic adsorption of protein Fn on the material surface were carried on by the technology of ultraviolet photometric, contact angle, solid Zeta potential, X-ray photoelectron spectroscopy, and quartz crystal microbalance. The surface with a certain amount of rH modification existed more hydrophilic due to the amphiphilic structure than before, on which the protein adsorption was the most unstable. The results indicated that the rH modification improved the resistance of PMMA to nonspecific adsorption of protein Fn to achieve the expectative effect.

  17. Structure-activity relationship for quaternary ammonium compounds hybridized with poly(methyl methacrylate).

    PubMed

    Melo, Leticia D; Palombo, Renata R; Petri, Denise F S; Bruns, Michael; Pereira, Edla M A; Carmona-Ribeiro, Ana M

    2011-06-01

    Hybrid films from poly (methylmethacrylate) (PMMA) and dioctadecyldimethylammonium bromide (DODAB), cetyltrimethylammonium bromide (CTAB), or tetrapropylammonium bromide (TPAB) were characterized by determination of wettability, ellipsometry, atomic force microscopy, active compounds diffusion to water, X-ray photoelectron spectroscopy (XPS) with determination of atomic composition on the films surface, and biocidal activity against Pseudomonas aeruginosa or Staphylococcus aureus. QAC mobility in the films increased from DODAB to CTAB to TPAB. Diffusion and optimal hydrophobic-hydrophilic balance imparted the highest bioactivity to CTAB. DODAB sustained immobilization at the film surface killed bacteria upon contact. TPAB ability to diffuse was useless because of its unfavorable hydrophobic-hydrophilic balance for bioactivity.

  18. Effect of residual monomer on radiochemical and light radiation processes in polymethyl methacrylate

    SciTech Connect

    Khamidova, L.G.; Zhdanov, G.S.; Milinchuk, V.K.

    1988-03-01

    The radiochemical yield of paramagnetic centers at 77 K varies from 1.2 in a polymer with a 0.2% weight concentration of MMA to 2.35 in a polymer containing 6.3% MMA. At 273 K, the radiochemical yield of macroradicals varies from 1.7 (0.2% MMA) to 3.2 (2.4% MMA). The high radiochemical yield of binding of residual monomer (G/sub MMA/ = 5.6 x 10/sup 2/ and 2.4 x 10/sup 2/ at 300 and 77 K) indicates the existence of associates of molecules of the monomer. It was hypothesized that radiation damage initially develops in defective regions of the polymer where the molecules of the monomer are primarily concentrated.

  19. Photophysical degradation of poly(1-vinylnaphthalene) and poly(methyl methacrylate) blends

    SciTech Connect

    Li, Ching Shan; Lopelman, R. )

    1990-03-08

    A reversible photophysical degradation of P1VN/PMMA blends is observed at 77 K upon prolonged irradiation. In the dilute blends, the ratio of singlet excimer to monomer emission increases as exposure time increases. However, thermal annealing even below the glass transition temperature can restore the original ratio of singlet excimer to monomer.

  20. Thermomechanical Properties of Poly(methyl methacrylates) Containing Tethered and Untethered Polyhedral Oligomeric Silsesquioxanes (POSS)

    DTIC Science & Technology

    2006-05-31

    temperature were performed in a Siemens 2D Small Angle Diffractometer configured in Wide Angle mode using a 12kW rotating anode; these samples (powders...Cp) Si O Si Si SiO O O Si O Si Si SiO O O O O O O R R R R R R R R CH3 R OO CH3 O CH3 O Si O Si Si Si O O O Si O Si Si Si O O O O O O O R R R R R R nx

  1. Cobalt iron-oxide nanoparticle modified poly(methyl methacrylate) nanodielectrics

    SciTech Connect

    Tuncer, Enis; Rondinone, Adam Justin; Woodward, Jonathan; Sauers, Isidor; James, David Randy; Ellis, Alvin R

    2009-01-01

    In this paper, we report the dielectric properties of composite systems (nanodielectrics) made of small amounts of mono dispersed magnetic nanoparticles embedded in a polymer matrix. It is observed from the transmission electron microscope images that the matrix polymeric material is confined in approximately $100\\ \

  2. Free volume distribution of branched poly(methyl methacrylates): Conformational probes study

    NASA Astrophysics Data System (ADS)

    Kamalova, D. I.; Remizov, A. B.

    2016-12-01

    In this work we studied the free volume distribution of the branched poly (methylmethacrylates) by the method of conformational probes. The freezing temperatures of the conformational transitions of the probes introduced into branched polymers were determined by FTIR spectra. The influence of covalently connected fullerene C60 on the freezing temperatures of conformational transitions was shown.

  3. Some Properties of Poly(Methyl Methacrylate) Studied by Radiation Degradation: An Interdisciplinary Student Experiment.

    ERIC Educational Resources Information Center

    Hill, D. J. T.; O'Donnell, J. H.

    1981-01-01

    Describes an interdisciplinary student experiment based upon the radiation effects on polymers, integrating some of the fundamentals of radiation chemistry, polymer chemistry, and material science. Also demonstrates how the information gained in the experiment has direct commercial application in product manufacture or processing. (CS)

  4. Solution Spraying of Poly(methyl methacrylate) Blends to Fabricate Micro-textured, Superoleophobic Surfaces (PREPRINT)

    DTIC Science & Technology

    2011-01-01

    was performed using a XL30 FEG Enviromental Scanning Electron Microscope (FEI/Philips). The shear viscosities of the polymer/fluoroPOSS solutions...2007;292(4):407- 414. 10. Medeiros ES, Glenn GM, Klamczynski AP, Orts WJ, and Mattoso LHC. Journal of Applied Polymer Science 2009;113(4):2322-2330...450-452. 22. Tuteja A, Choi W, Ma M, Mabry JM, Mazzella SA, Rutledge GC, McKinley GH, and Cohen RE. Science 2007;318(5856):1618. 23. Tuteja A

  5. Photochemistry in polymer solids. Decay of benzophenone phosphorescence in poly(methyl methacrylate)

    NASA Astrophysics Data System (ADS)

    Horie, Kazuyuki; Mita, Itaru

    1982-11-01

    Decay curves and lifetimes of benzophenone phosphorescence in PMMA at 80-433 K significantly reflect the change in molecular motion of the matrix polymer such as glass transition, α' transition, and β transition. The non-exponential decay observed at temperatures between Tβ and Tg is attributed to the intermolecular quenching of benzophenone triplet by carbonyl group in the side chain of PMMA.

  6. Rheological properties of silica dispersions stabilized by stereoregular poly(methyl methacrylate).

    PubMed

    Carriere, Pascal; Feller, Jean-François; Dupuis, Dominique; Grohens, Yves

    2004-04-01

    The adsorption of stereoregular polymers and its effect on the conformation and dynamics of the polymer at interfaces are only poorly understood. 1H NMR has revealed a lowering of the peaks assigned to isotactic sequences whatever the PMMA tacticity, which provides evidence of stereospecific adsorption of the isotactic segments on silica. Entropic factors are therefore assumed to control the configuration of the adsorbed layer. Tacticity-dependent rheological behavior is revealed by dynamic investigations carried out on silica dispersions. The driving forces likely to induce the stereoselective adsorption and tacticity-dependent rheology of suspensions are discussed.

  7. Femtosecond laser surface ablation of polymethyl-methacrylate with position control through z-scan

    NASA Astrophysics Data System (ADS)

    Florian, C.; Caballero-Lucas, F.; Fernández-Pradas, J. M.; Bosch, S.; Morenza, J. L.; Serra, P.

    2015-08-01

    Spatial resolution of laser micromachining of polymers can be improved with the use of femtosecond laser pulses. Due to the short interaction time, thermal effects are significantly reduced. Additionally, the non-linear character of the interaction of ultrashort laser pulses with transparent materials allows the modification inside their bulk also. However, this creates the challenge to accurately focus the laser beam in the surface when only surface ablation is required. Thus, this work presents a study of the laser ablation of a transparent polymer at different pulse energies and focusing positions controlled through z-scan transmittance measurements. Experiments were performed using an Yb:KYW laser with 450 fs pulses and 1027 nm wavelength. Morphological analysis of the polymer surface after irradiation was performed using scanning electron microscopy. Similar ablation craters were found for a range of sample positions around the beam waist. However, focused ion beam cross-sections of the craters unveil significant inner modifications under most of the focusing conditions leading to surface ablation. Hence, surface ablation without damaging the bulk material only occurs at critical positions where the beam waist is located slightly outside the sample. In situ monitoring of the sample position can be made through transmittance measurements.

  8. Highly photosensitive polymethyl methacrylate microstructured polymer optical fiber with doped core.

    PubMed

    Sáez-Rodríguez, D; Nielsen, K; Rasmussen, H K; Bang, O; Webb, D J

    2013-10-01

    In this Letter, we report the fabrication of a highly photosensitive, microstructured polymer optical fiber using benzyl dimethyl ketal as a dopant, as well as the inscription of a fiber Bragg grating in the fiber. A refractive index change in the core of at least 3.2×10(-4) has been achieved, providing a grating with a strong transmission rejection of -23 dB with an inscription time of only 13 min. The fabrication method has a big advantage compared to doping step index fiber since it enables doping of the fiber without using extra dopants to compensate for the index reduction in the core introduced by the photosensitive agent.

  9. Directive Evidence for the Creation of Micropores in UV-Irradiated Poly(Methyl Methacrylate)

    DTIC Science & Technology

    1990-05-31

    behavior of photochromic labels allows the study of processes such as physical aging. plasticization. and volume dilation caused by glassy deformation... photochromic labels [15. 16]. In this work. azobenzene was used as a molecular label to study the formation of micropores in irradiated PMMA film. Trans...the polymer matrix could be probed by the use of photochromic labels [13-161. Analysis of the photoisomerization behavior of photochromic labels

  10. Optical and dielectric properties of ion beam irradiated Ag/polymethyl methacrylate nanocomposites.

    PubMed

    Gavade, Chaitali; Singh, N L; Khanna, P K

    2014-08-01

    Changes in the dielectric, optical, structural and thermal properties of PMMA/silver nanocomposites of different concentrations of silver nanoparticles (5%, 10%, 15%) due to swift heavy ion irradiation were studied by means of impedance gain phase analyzer, UV-visible spectroscopy, X-ray diffraction and differential scanning calorimetry. Samples were irradiated with 120 MeV Si-ions at fluences of 1 x 10(11), 1 x 10(12) ions/cm2. Dependence of dielectric properties on frequency, ion beam fluence and filler concentration was studied. The results revealed the enhancement in dielectric properties after dopping nanoparticles and also upon irradiation. Optical properties like band gap was estimated for pure polymer and nanocomposite films from their optical absorption spectra in the wavelength region 200-800 nm. It was found that the band gap value shifted to lower energy (from 4.58 eV to 3.21 eV) on doping with silver nanoparticles. Differential scanning calorimetry analysis revealed a decrease in the glass transition temperature upon irradiation, which may be attributed to scissioning of polymer chain due to ion beam irradiation which is also confirmed with XRD analysis.

  11. Poly(methyl methacrylate)-grafted chitosan microspheres for controlled release of ampicillin.

    PubMed

    Changerath, Radhakumary; Nair, Prabha D; Mathew, Suresh; Nair, C P Reghunadhan

    2009-04-01

    Microspheres of 50-500 microm diameter were prepared from a blend of chitosan and chitosan-g-PMMA. Environmental scanning electron microscopic and SEM studies revealed that the microspheres are porous and the pores extend toward the inner core of the microspheres. The microspheres were also found to be hemocompatible and cytocompatible. A model drug ampicillin was used to evaluate the drug loading capacity and the controlled release properties of the microspheres. The system maintained a sustained release of ampicillin for a period of more than 8 days. The drug-loaded chitosan/chitosan-g-PMMA microspheres exhibited higher antibacterial activity for both the gram positive (ATCC 25923 S. aureus) and gram negative (ATCC 25922 E. coli) bacteria than the drug-loaded virgin chitosan microspheres. The percentage release and bioactivity of ampicillin was found to be higher for the chitosan/chitosan-g-PMMA microspheres than the virgin chitosan microspheres. Potential applications such as oral drug delivery, wound dressings, tissue engineering, and so forth, are envisaged from these microspheres.

  12. Use of Almond Shells and Rice Husk as Fillers of Poly(Methyl Methacrylate) (PMMA) Composites

    PubMed Central

    Sabbatini, Alessandra; Lanari, Silvia; Santulli, Carlo

    2017-01-01

    In recent years, wood fibres have often been applied as the reinforcement of thermoplastic materials, such as polypropylene, whereas their use in combination with thermosetting resin has been less widespread. This study concerns the production of PMMA-based composites by partly replacing alumina trihydrate (ATH) with wood waste fillers, namely rice husks and almond shells, which would otherwise be disposed by incineration. The amount of filler introduced was limited to 10% as regards rice husks and 10 or 15% almond shells, since indications provided by reactivity tests and viscosity measurements did not suggest the feasibility of total replacement of ATH. As a matter of fact, the introduction of these contents of wood waste filler in PMMA-based composite did not result in any significant deterioration of its mechanical properties (Charpy impact, Rockwell M hardness and flexural performance). Some reduction of these properties was only observed in the case of introduction of 15% almond shells. A further issue concerned the yellowing of the organic filler under exposure to UV light. On the other hand, a very limited amount of water was absorbed, never exceeding values around 0.6%, despite the significant porosity revealed by the filler’s microscopic evaluation. These results are particularly interesting in view of the application envisaged for these composites, i.e., wood replacement boards. PMID:28773234

  13. Highly transparent and toughened poly(methyl methacrylate) nanocomposite films containing networks of cellulose nanofibrils

    Treesearch

    Hong Dong; Yelena R. Sliozberg; James F. Snyder; Joshua Steele; Tanya L. Chantawansri; Joshua A. Orlicki; Scott D. Walck; Richard S. Reiner; Alan W. Rudie

    2015-01-01

    Cellulose nanofibrils (CNFs) are a class of cellulosic nanomaterials with high aspect ratios that can be extracted from various natural sources. Their highly crystalline structures provide the nanofibrils with excellent mechanical and thermal properties. The main challenges of CNFs in nanocomposite applications are associated with their high hydrophilicity, which makes...

  14. Impact strength of denture polymethyl methacrylate reinforced with continuous glass fibers or metal wire.

    PubMed

    Vallittu, P K; Vojtkova, H; Lassila, V P

    1995-12-01

    The impact strength of heat-cured acrylic resin test specimens that had been reinforced in various ways was compared in this study. Ten rectangular test specimens were fabricated for each test group. The strengtheners included 1.0-mm-diameter steel wire and continuous E-glass fibers. Both notched and unnotched test specimens were tested in a Charpy-type impact test. In a further analysis the concentration of glass fibers in the test specimens was determined and plotted against the impact strength of the test specimens. The results showed that, compared with the unreinforced specimens, both types of reinforcement increased the impact strength of the test specimens considerably (p < 0.001). There was no clear difference between the mean impact strength value of the test specimens reinforced with metal wire and that of the specimens reinforced with glass fiber. The correlation coefficient between the fiber concentration of the test specimens and their impact strength was 0.818 (p < 0.005). Specimens with fiber concentrations greater than 25 wt% yielded to the higher impact strength more readily than those with metal wire reinforcement did.

  15. Bosch-like method for creating high aspect ratio poly(methyl methacrylate) (PMMA) structures

    NASA Astrophysics Data System (ADS)

    Haiducu, Marius; Sameoto, Dan; Foulds, Ian; Johnstone, Robert W.; Parameswaran, Ash M.

    2012-03-01

    This paper presents a method for etching millimetre-deep trenches in commercial grade PMMA using deep-UV at 254 nm. The method is based on consecutive cycles of irradiation and development of the exposed areas, respectively. The exposure segment is performed using an inexpensive, in-house built irradiation box while the development part is accomplished using an isopropyl alcohol (IPA):H2O developer. The method was tested and characterized by etching various dimension square test structures in commercial grade, mirrored acrylic. The undercut of the sidewalls due to the uncollimated nature of the irradiation light was dramatically alleviated by using a honeycomb metallic grid in between the irradiation source and the acrylic substrate and by rotating the latter using a direct current (DC) motor-driven stage. By using an extremely affordable set-up and non-toxic, environmentally friendly materials and substances, this process represents an excellent alternative to microfabricating microfluidic devices in particular and high aspect ratio structures in general using PMMA as substrate.

  16. Some Properties of Poly(Methyl Methacrylate) Studied by Radiation Degradation: An Interdisciplinary Student Experiment.

    ERIC Educational Resources Information Center

    Hill, D. J. T.; O'Donnell, J. H.

    1981-01-01

    Describes an interdisciplinary student experiment based upon the radiation effects on polymers, integrating some of the fundamentals of radiation chemistry, polymer chemistry, and material science. Also demonstrates how the information gained in the experiment has direct commercial application in product manufacture or processing. (CS)

  17. Optical Properties of Nanocellulose Dispersions in Water, Dimethylformamide and Poly(Methyl Methacrylate)

    DTIC Science & Technology

    2013-10-01

    Cellulose is a carbohydrate building block obtained from many prevalent resources to include wood, hemp , ramie, cotton, and bacteria (Moon et al...Forest Products Laboratory in an aqueous dispersion (Reiner and Rudie, 2013). Softwood pulp was first treated with sulfuric acid. The acid solution was

  18. Hydrolysed microspheres from cross-linked polymethyl methacrylate (Hydrogel). A new embolic material for interventional neuroradiology.

    PubMed

    Rao, V R; Ravimandalam, K; Jayakrishnan, A; Thanoo, B C; Radhakrishnan, V V; Gupta, A K; Kumar, S; Joseph, S; Unni, M; Rao, A S

    1991-01-01

    Highly hydrophilic, perfectly smooth and spherical microspheres have been synthetized. These non-biodegradable microspheres absorb water in varying degrees and can be injected easily through microcatheters due to their slippery and compressible characteristics. The material was successfully used for embolization of 4 vascular intracranial tumours and 2 spinal vascular lesions in the cervical region, by superselective delivery. Histopathology confirmed absolute inertness of the microspheres.

  19. Protein immobilization on the surface of polydimethylsiloxane and polymethyl methacrylate microfluidic devices.

    PubMed

    Khnouf, Ruba; Karasneh, Dina; Albiss, Borhan Aldeen

    2016-02-01

    PDMS and PMMA are two of the most used polymers in the fabrication of lab-on-chip or microfluidic devices. In order to use these polymers in biological applications, it is sometimes essential to be able to bind biomolecules such as proteins and DNA to the surface of these materials. In this work, we have evaluated a number of processes that have been developed to bind protein to PDMS surfaces which include passive adsorption, passive adsorption with glutaraldehyde cross-linking, (3-aminopropyl) triethoxysilane functionalization followed by glutaraldehyde or 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride cross-linkers. It has been shown that the latter technique--using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride--results in more than twice the bonding of protein to the surface of PDMS microchannels than proteins binding passively. We have also evaluated a few techniques that have been tested for the functionalization of PMMA microchannels where we have found that the use of polyethyleneimine (PEI) has led to the strongest protein-PMMA microchannel bond. We finally demonstrated the effect of PDMS curing methodology on protein adsorption to its surface, and showed that increased curing time is the factor that reduces passive adsorption the most.

  20. Scattering studies on mixtures of poly(ethylene oxide) with poly(methyl methacrylate)

    SciTech Connect

    Russell, T.P.; Ito, H.; Wignall, G.D.

    1986-12-01

    Molten and semi-crystalline mixtures of PEO and PMMA have been investigated by small angle neutron and x-ray scattering. It has been found that the Flory Huggins interaction parameter, evaluated from the intermolecular scattering function, is quite small and is apparently dominated by entropic contributions. Scattering profiles from the semi-crystalline mixtures clearly show that the PMMA is incorporated within the amorphous phase between the crystalline PEO lamellae.

  1. Antimicrobial activity of bone cements embedded with organic nanoparticles

    PubMed Central

    Perni, Stefano; Thenault, Victorien; Abdo, Pauline; Margulis, Katrin; Magdassi, Shlomo; Prokopovich, Polina

    2015-01-01

    Infections after orthopedic surgery are a very unwelcome outcome; despite the widespread use of antibiotics, their incidence can be as high as 10%. This risk is likely to increase as antibiotics are gradually losing efficacy as a result of bacterial resistance; therefore, novel antimicrobial approaches are required. Parabens are a class of compounds whose antimicrobial activity is employed in many cosmetic and pharmaceutical products. We developed propylparaben nanoparticles that are hydrophilic, thus expanding the applicability of parabens to aqueous systems. In this paper we assess the possibility of employing paraben nanoparticles as antimicrobial compound in bone cements. The nanoparticles were embedded in various types of bone cement (poly(methyl methacrylate) [PMMA], hydroxyapatite, and brushite) and the antimicrobial activity was determined against common causes of postorthopedic surgery infections such as: Staphylococcus aureus, methicillin-resistant S. aureus, Staphylococcus epidermidis, and Acinetobacter baumannii. Nanoparticles at concentrations as low as 1% w/w in brushite bone cement were capable of preventing pathogens growth, 5% w/w was needed for hydroxyapatite bone cement, while 7% w/w was required for PMMA bone cement. No detrimental effect was determined by the addition of paraben nanoparticles on bone cement compression strength and cytocompatibility. Our results demonstrate that paraben nanoparticles can be encapsulated in bone cement, providing concentration-dependent antimicrobial activity; furthermore, lower concentrations are needed in calcium phosphate (brushite and hydroxyapatite) than in acrylic (PMMA) bone cements. These nanoparticles are effective against a wide spectrum of bacteria, including those already resistant to the antibiotics routinely employed in orthopedic applications, such as gentamicin. PMID:26487803

  2. Antimicrobial activity of bone cements embedded with organic nanoparticles.

    PubMed

    Perni, Stefano; Thenault, Victorien; Abdo, Pauline; Margulis, Katrin; Magdassi, Shlomo; Prokopovich, Polina

    2015-01-01

    Infections after orthopedic surgery are a very unwelcome outcome; despite the widespread use of antibiotics, their incidence can be as high as 10%. This risk is likely to increase as antibiotics are gradually losing efficacy as a result of bacterial resistance; therefore, novel antimicrobial approaches are required. Parabens are a class of compounds whose antimicrobial activity is employed in many cosmetic and pharmaceutical products. We developed propylparaben nanoparticles that are hydrophilic, thus expanding the applicability of parabens to aqueous systems. In this paper we assess the possibility of employing paraben nanoparticles as antimicrobial compound in bone cements. The nanoparticles were embedded in various types of bone cement (poly(methyl methacrylate) [PMMA], hydroxyapatite, and brushite) and the antimicrobial activity was determined against common causes of postorthopedic surgery infections such as: Staphylococcus aureus, methicillin-resistant S. aureus, Staphylococcus epidermidis, and Acinetobacter baumannii. Nanoparticles at concentrations as low as 1% w/w in brushite bone cement were capable of preventing pathogens growth, 5% w/w was needed for hydroxyapatite bone cement, while 7% w/w was required for PMMA bone cement. No detrimental effect was determined by the addition of paraben nanoparticles on bone cement compression strength and cytocompatibility. Our results demonstrate that paraben nanoparticles can be encapsulated in bone cement, providing concentration-dependent antimicrobial activity; furthermore, lower concentrations are needed in calcium phosphate (brushite and hydroxyapatite) than in acrylic (PMMA) bone cements. These nanoparticles are effective against a wide spectrum of bacteria, including those already resistant to the antibiotics routinely employed in orthopedic applications, such as gentamicin.

  3. Mechanical testing and osteointegration of titanium implant with calcium phosphate bone cement and autograft alternatives.

    PubMed

    Lin, Dan-Jae; Ju, Chien-Ping; Huang, Shu-Huei; Tien, Yin-Chun; Yin, Hsiang-Shu; Chen, Wen-Cheng; Chern Lin, Jiin-Huey

    2011-10-01

    The purpose of this study was to evaluate the osteointegration of a titanium (Ti) implant with the calcium phosphate cement (CPC) and autograft prostheses by pull-out test and histological examination. Stems of sixty Ti cylinders were bilaterally inserted into femoral medullary canals in 30 rabbits at the 1st, 4th, 12th, 26th and 70th postoperative weeks. The bone autograft and CPC were filled into the pre-trimmed bone marrow cavity with a polymethyl methacrylate retarder in the distal end, and then a Ti cylinder was inserted into femurs. The CPC group was significantly (p<0.05) associated with a larger pull-out force at 4th (37%) and 12th (62%) weeks compared to the autograft group. The bone area and the bone-to-implant contact ratios of the CPC groups were significantly higher than that of the autograft groups at early healing stage. The histological exams suggest that the CPC enhanced the earlier bone formation around the implant at a period not longer than 12 weeks postoperation. We conclude that CPC graft has the higher ability to facilitate the osteointegration and stabilize the Ti implant at a relatively early stage than the autograft in vivo. Copyright © 2011. Published by Elsevier Ltd.

  4. Flexural properties of ethyl or methyl methacrylate-UDMA blend polymers.

    PubMed

    Kanie, Takahito; Kadokawa, Akihiko; Arikawa, Hiroyuki; Fujii, Koichi; Ban, Seiji

    2010-10-01

    Light-curing polyethyl methacrylate (PEMA)-urethane dimethacrylate (UDMA) resins and polymethyl methacrylate (PMMA)-UDMA resins were prepared by two processes. For first step, PEMA or PMMA powders were fully dissolved in ethyl methacrylate (EMA) or methyl methacrylate (MMA) and then the PEMA-EMA/PMMA-MMA mixtures were mixed with UDMA. The flexural properties of cured PEMA-UDMA and PMMA-UDMA polymers were measured using two PEMA (Mw: 300,000-400,000 and 650,000-1,000,000) and three PMMA (Mw: 30,000-60,000, 350,000 and 650,000-1,000,000) powders with different molecular weight, four mixing ratios of PMMA-MMA, and three mixing ratios of PMMA-MMA mixture and UDMA oligomer. Polymers with PMMA(Mw: 350,000) MMA=25/50, and with PMMA(Mw: 350,000)-MMA/UDMA=1/2 and =1/1, showed no-fracture in a flexural test at 1 mm/min and flexural strength and flexural modulus showed no significant difference compared with those of commercially available heat- and self-curing acrylic resins (p>0.01). Within limitation of this investigation, methyl methacrylate-UDMA blend polymer of this composition is available for denture base resin.

  5. First cosmic-ray images of bone and soft tissue

    NASA Astrophysics Data System (ADS)

    Mrdja, Dusan; Bikit, Istvan; Bikit, Kristina; Slivka, Jaroslav; Hansman, Jan; Oláh, László; Varga, Dezső

    2016-11-01

    More than 120 years after Roentgen's first X-ray image, the first cosmic-ray muon images of bone and soft tissue are created. The pictures, shown in the present paper, represent the first radiographies of structures of organic origin ever recorded by cosmic rays. This result is achieved by a uniquely designed, simple and versatile cosmic-ray muon-imaging system, which consists of four plastic scintillation detectors and a muon tracker. This system does not use scattering or absorption of muons in order to deduct image information, but takes advantage of the production rate of secondaries in the target materials, detected in coincidence with muons. The 2D image slices of cow femur bone are obtained at several depths along the bone axis, together with the corresponding 3D image. Real organic soft tissue, polymethyl methacrylate and water, never seen before by any other muon imaging techniques, are also registered in the images. Thus, similar imaging systems, placed around structures of organic or inorganic origin, can be used for tomographic imaging using only the omnipresent cosmic radiation.

  6. Nanoparticulate drug delivery platforms for advancing bone infection therapies

    PubMed Central

    Uskoković, Vuk; Desai, Tejal A

    2015-01-01

    Introduction The ongoing surge of resistance of bacterial pathogens to antibiotic therapies and the consistently aging median member of the human race signal an impending increase in the incidence of chronic bone infection. Nanotechnological platforms for local and sustained delivery of therapeutics hold the greatest potential for providing minimally invasive and maximally regenerative therapies for this rare but persistent condition. Areas covered Shortcomings of the clinically available treatment options, including poly(methyl methacrylate) beads and calcium sulfate cements, are discussed and their transcending using calcium-phosphate/polymeric nanoparticulate composites is foreseen. Bone is a composite wherein the weakness of each component alone is compensated for by the strength of its complement and an ideal bone substitute should be fundamentally the same. Expert opinion Discrepancy between in vitro and in vivo bioactivity assessments is highlighted, alongside the inherent imperfectness of the former. Challenges entailing the cross-disciplinary nature of engineering a new generation of drug delivery vehicles are delineated and it is concluded that the future for the nanoparticulate therapeutic carriers belongs to multifunctional, synergistic and theranostic composites capable of simultaneously targeting, monitoring and treating internal organismic disturbances in a smart, feedback fashion and in direct response to the demands of the local environment. PMID:25109804

  7. A comparison of high viscosity bone cement and low viscosity bone cement vertebroplasty for severe osteoporotic vertebral compression fractures.

    PubMed

    Zhang, Liang; Wang, Jingcheng; Feng, Xinmin; Tao, Yuping; Yang, Jiandong; Wang, Yongxiang; Zhang, Shengfei; Cai, Jun; Huang, Jijun

    2015-02-01

    To compare the clinical outcome and complications of high viscosity and low viscosity poly-methyl methacrylate bone cement PVP for severe OVCFs. From December 2010 to December 2012, 32 patients with severe OVCFs were randomly assigned to either group H using high viscosity cement (n=14) or group L using low viscosity cement (n=18). The clinical outcomes were assessed by the Visual Analog Scale (VAS), Oswestry Disability Index (ODI), Short Form-36 General Health Survey (SF-36), kyphosis Cobb's angle, vertebral height, and complications. Significant improvement in the VAS, ODI, SF-36 scores, kyphosis Cobb's angle, and vertebral height were noted in both the groups, and there were no significant differences between the two groups. Cement leakage was seen less in group H. Postoperative assessment using computed tomography identified cement leakage in 5 of 17 (29.4%) vertebrae in group H and in 15 of 22 (68.2%) vertebrae in group L (P=0.025). The PVP using high viscosity bone cement can provide the same clinical outcome and fewer complications compared with PVP using low viscosity bone cement. Copyright © 2014. Published by Elsevier B.V.

  8. Effects of extracorporeal shockwaves on the stability of the interface between bone and polymethylmethacrylate: an in vitro study on human femoral segments.

    PubMed

    Braun, W; Claes, L; Rüter, A; Paschke, D

    1992-02-01

    The increasing number of revision procedures for failed total arthroplasty requiring difficult cement removal has led to various developments of new instruments and techniques to facilitate this procedure. In this in vitro study the effect of extracorporeal shockwaves on the bone-cement interface was investigated. At first the pressure reduction caused by the passage of shockwaves through compounds consisting of cortical bone-polymethyl-methacrylate and cancellous bone-polymethylmethacrylate by means of a needle pressure probe was measured. Secondly, the mechanical and morphological effects of extracorporeal shockwaves on the polymethylmethacrylate-bone interface of human femoral segments was tested. Using bone cement, stainless steel rods were implanted into cadaveric femoral segments and the polymethylmethacrylate-bone interface was treated with extracorporeal shockwaves. When comparing the treatment and control groups mechanically, radiologically, and microscopically it was not possible to demonstrate evidence of disruption of the interface caused by extracorporeal shockwaves. Instead it was shown that intravasation of bone marrow can be induced by shockwaves. Considering these facts, shockwaves seems not to be good clinical adjunct in revision surgery of failed arthroplasty.

  9. Bone

    NASA Astrophysics Data System (ADS)

    Helmberger, Thomas K.; Hoffmann, Ralf-Thorsten

    The typical clinical signs in bone tumours are pain, destruction and destabilization, immobilization, neurologic deficits, and finally functional impairment. Primary malignant bone tumours are a rare entity, accounting for about 0.2% of all malignancies. Also benign primary bone tumours are in total rare and mostly asymptomatic. The most common symptomatic benign bone tumour is osteoid osteoma with an incidence of 1:2000.

  10. Double-bond-containing polyallene-based triblock copolymers via phenoxyallene and (meth)acrylate

    PubMed Central

    Ding, Aishun; Lu, Guolin; Guo, Hao; Huang, Xiaoyu

    2017-01-01

    A series of ABA triblock copolymers, consisting of double-bond-containing poly(phenoxyallene) (PPOA), poly(methyl methacrylate) (PMMA), or poly(butyl acrylate) (PBA) segments, were synthesized by sequential free radical polymerization and atom transfer radical polymerization (ATRP). A new bifunctional initiator bearing azo and halogen-containing ATRP initiating groups was first prepared followed by initiating conventional free radical homopolymerization of phenoxyallene with cumulated double bond to give a PPOA-based macroinitiator with ATRP initiating groups at both ends. Next, PMMA-b-PPOA-b-PMMA and PBA-b-PPOA-b-PBA triblock copolymers were synthesized by ATRP of methyl methacrylate and n-butyl acrylate initiated by the PPOA-based macroinitiator through the site transformation strategy. These double-bond-containing triblock copolymers are stable under UV irradiation and free radical circumstances. PMID:28252049

  11. Double-bond-containing polyallene-based triblock copolymers via phenoxyallene and (meth)acrylate

    NASA Astrophysics Data System (ADS)

    Ding, Aishun; Lu, Guolin; Guo, Hao; Huang, Xiaoyu

    2017-03-01

    A series of ABA triblock copolymers, consisting of double-bond-containing poly(phenoxyallene) (PPOA), poly(methyl methacrylate) (PMMA), or poly(butyl acrylate) (PBA) segments, were synthesized by sequential free radical polymerization and atom transfer radical polymerization (ATRP). A new bifunctional initiator bearing azo and halogen-containing ATRP initiating groups was first prepared followed by initiating conventional free radical homopolymerization of phenoxyallene with cumulated double bond to give a PPOA-based macroinitiator with ATRP initiating groups at both ends. Next, PMMA-b-PPOA-b-PMMA and PBA-b-PPOA-b-PBA triblock copolymers were synthesized by ATRP of methyl methacrylate and n-butyl acrylate initiated by the PPOA-based macroinitiator through the site transformation strategy. These double-bond-containing triblock copolymers are stable under UV irradiation and free radical circumstances.

  12. Double-bond-containing polyallene-based triblock copolymers via phenoxyallene and (meth)acrylate.

    PubMed

    Ding, Aishun; Lu, Guolin; Guo, Hao; Huang, Xiaoyu

    2017-03-02

    A series of ABA triblock copolymers, consisting of double-bond-containing poly(phenoxyallene) (PPOA), poly(methyl methacrylate) (PMMA), or poly(butyl acrylate) (PBA) segments, were synthesized by sequential free radical polymerization and atom transfer radical polymerization (ATRP). A new bifunctional initiator bearing azo and halogen-containing ATRP initiating groups was first prepared followed by initiating conventional free radical homopolymerization of phenoxyallene with cumulated double bond to give a PPOA-based macroinitiator with ATRP initiating groups at both ends. Next, PMMA-b-PPOA-b-PMMA and PBA-b-PPOA-b-PBA triblock copolymers were synthesized by ATRP of methyl methacrylate and n-butyl acrylate initiated by the PPOA-based macroinitiator through the site transformation strategy. These double-bond-containing triblock copolymers are stable under UV irradiation and free radical circumstances.

  13. Novel antifouling oligo(ethylene glycol) methacrylate particles via surfactant-free emulsion polymerization.

    PubMed

    Buyukserin, Fatih; Camli, Sevket Tolga; Yavuz, Mustafa Selman; Budak, Gurer Guven

    2011-03-01

    The use of particle formulations with antifouling surface properties attracts increasing interest in several biotechnological applications. Majority of these studies utilize a poly(ethylene glycol) coating to render the corresponding surface nonrecognizable to biological macromolecules. Herein, we report a simple way to prepare novel antifouling colloids composed of oligo(ethylene glycol) backbones via surfactant-free emulsion polymerization. Monodisperse cross-linked poly(ethylene glycol) ethyl ether methacrylate particles were characterized by dynamic light scattering and transmission electron microscopy. The effects of monomer, cross-linker and initiator on particle characteristics were investigated. More importantly, a prominent blockage of bovine serum albumin adsorption was obtained for the poly(ethylene glycol)-based sub-micron (~200 nm) particles when compared with similar-sized poly(methyl methacrylate) counterparts.

  14. The Biocompatibility of Porous vs Non-Porous Bone Cements: A New Methodological Approach

    PubMed Central

    Dall’Oca, C.; Maluta, T.; Cavani, F.; Morbioli, G.P.; Bernardi, P.; Sbarbati, A.; Degl’Innocenti, D.; Magnan, B.

    2014-01-01

    Composite cements have been shown to be biocompatible, bioactive, with good mechanical properties and capability to bind to the bone. Despite these interesting characteristic, in vivo studies on animal models are still incomplete and ultrastructural data are lacking. The acquisition of new ultrastructural data is hampered by uncertainties in the methods of preparation of histological samples due to the use of resins that melt methacrylate present in bone cement composition. A new porous acrylic cement composed of polymethyl-metacrylate (PMMA) and β-tricalcium-phosphate (p-TCP) was developed and tested on an animal model. The cement was implanted in femurs of 8 New Zealand White rabbits, which were observed for 8 weeks before their sacrifice. Histological samples were prepared with an infiltration process of LR white resin and then the specimens were studied by X-rays, histology and scanning electron microscopy (SEM). As a control, an acrylic standard cement, commonly used in clinical procedures, was chosen. Radiographic ultrastructural and histological exams have allowed finding an excellent biocompatibility of the new porous cement. The high degree of osteointegration was demonstrated by growth of neo-created bone tissue inside the cement sample. Local or systemic toxicity signs were not detected. The present work shows that the proposed procedure for the evaluation of biocompatibility, based on the use of LR white resin allows to make a thorough and objective assessment of the biocompatibility of porous and non-porous bone cements. PMID:24998920

  15. Fabrication and characterization of a novel carbon fiber-reinforced calcium phosphate silicate bone cement with potential osteo-inductivity.

    PubMed

    Zheng, Jiangjiang; Xiao, Yu; Gong, Tianxing; Zhou, Shuxin; Troczynski, Tom; Yang, Quanzu; Bao, Chongyun; Xu, Xiaoming

    2015-12-23

    The repair of bone defects is still a pressing challenge in clinics. Injectable bone cement is regarded as a promising material to solve this problem because of its special self-setting property. Unfortunately, its poor mechanical conformability, unfavorable osteo-genesis ability and insufficient osteo-inductivity seriously limit its clinical application. In this study, novel experimental calcium phosphate silicate bone cement reinforced by carbon fibers (CCPSC) was fabricated and characterized. First, a compressive strength test and cell culture study were carried out. Then, the material was implanted into the femoral epiphysis of beagle dogs to further assess its osteo-conductivity using a micro-computed tomography scan and histological analysis. In addition, we implanted CCPSC into the beagles' intramuscular pouches to perform an elementary investigation of its osteo-inductivity. The results showed that incorporation of carbon fibers significantly improved its mechanical properties. Meanwhile, CCPSC had better biocompatibility to activate cell adhesion as well as proliferation than poly-methyl methacrylate bone cement based on the cell culture study. Moreover, pronounced biodegradability and improved osteo-conductivity of CCPSC could be observed through the in vivo animal study. Finally, a small amount of osteoid was found at the heterotopic site one month after implantation which indicated potential osteo-inductivity of CCPSC. In conclusion, the novel CCPSC shows promise as a bioactive bone substitute in certain load-bearing circumstances.

  16. A novel liposomal drug delivery system for PMMA bone cements

    PubMed Central

    Birchall, James C.; Evans, Samuel L.; Denyer, Stephen P.

    2015-01-01

    Abstract The population in developed countries is ageing and the number of people experiencing joint‐related conditions, such as osteoarthritis, is expected to increase. Joint replacements are currently the most effective treatment for severe joint conditions and although many of these procedures are successful, infection developing after the procedure is still an issue, requiring complex and expensive revisions. Whilst incorporating a powdered antibiotic within the bone cement can reduce infection rates, the powder frequently agglomerates, resulting in poor antibiotic release characteristics and compromised mechanical performance of the cement. To overcome these issues, a novel delivery system consisting of antibiotic‐loaded nano‐sized liposomes was developed for inclusion into polymethyl methacrylate (PMMA) bone cement. This system was tested in a commercial cement (Palacos R) and consistently delivered a higher percentage (22%) of the incorporated antibiotic when compared to the powdered antibiotic cement (9%), meaning less antibiotic needs to be incorporated than with conventional cement. The novel system resulted in a controlled and gradual release of antibiotic over a longer, 30‐day period and enhanced the toughness, bending strength and Vickers hardness of the cement, without altering its polymerization or molecular structure. This new material has the potential to significantly reduce infections in cemented joint replacements leading to enhanced patient quality of life and reduced healthcare costs. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1510–1524, 2016. PMID:26256271

  17. Effect of fixation and embedding on Raman spectroscopic analysis of bone tissue.

    PubMed

    Yeni, Y N; Yerramshetty, J; Akkus, O; Pechey, C; Les, C M

    2006-06-01

    Raman spectroscopy provides valuable information on the physicochemical properties of hard tissues. While the technique can analyze tissues in their native state, analysis of fixed, embedded, and sectioned specimens may be necessary on certain occasions. The information on the effects of fixatives and embedding media on Raman spectral properties is limited. We examined the effect of ethanol and glycerol as fixatives and a variety of embedding media (Araldite, Eponate, Technovit, glycol methacrylate, polymethyl methacrylate, and LR white) on Raman spectral properties (mineralization, crystallinity, and carbonation) measured from the cortical bone of mouse humeri. Humeri were fixed in ethanol or glycerol, followed by embedding in one of the media. Nonfixed, freeze-dried, and fixed but not embedded sections were also examined. Periosteal, endosteal, and midosteal regions of the intracortical envelope were analyzed. Raman spectra of fixative solutions and embedding media were also recorded separately in order to examine the specifics of overlap between spectra. We found significant effects of fixation, embedding, and anatomical location on Raman spectral properties. The interference of ethanol with tissue seemed to be relatively less pronounced than that of glycerol. However, there was no single combination of fixation and embedding that left Raman spectral parameters unaltered. We conclude that careful selection of a fixation and embedding combination should be made based on the parameter of interest and the type of tissue. It may be necessary to process multiple samples from the tissue, each using a combination appropriate for the Raman parameter in question.

  18. Preparation of periodic surface structures on doped poly(methyl metacrylate) films by irradiation with KrF excimer laser

    PubMed Central

    2014-01-01

    In this work, we describe laser modification of poly(methyl methacrylate) films doped with Fast Red ITR, followed by dopant exclusion from the bulk polymer. By this procedure, the polymer can be modified under extremely mild conditions. Creation of surface ordered structure was observed already after application of 15 pulses and 12 mJ cm−2 fluence. Formation of grating begins in the hottest places and tends to form concentric semi-circles around them. The mechanism of surface ordered structure formation is attributed to polymer ablation, which is more pronounced in the place of higher light intensity. The smoothness of the underlying substrate plays a key role in the quality of surface ordered structure. Most regular grating structures were obtained on polymer films deposited on atomically ‘flat’ Si substrates. After laser patterning, the dopant was removed from the polymer by soaking the film in methanol. PMID:25386106

  19. The Use of Micro and Nano Particulate Fillers to Modify the Mechanical and Material Properties of Acrylic Bone Cement

    NASA Astrophysics Data System (ADS)

    Slane, Joshua A.

    Acrylic bone cement (polymethyl methacrylate) is widely used in total joint replacements to provide long-term fixation of implants. In essence, bone cement acts as a grout by filling in the voids left between the implant and the patient's bone, forming a mechanical interlock. While bone cement is considered the `gold standard' for implant fixation, issues such as mechanical failure of the cement mantle (aseptic loosening) and the development of prosthetic joint infection (PJI) still plague joint replacement procedures and often necessitate revision arthroplasty. In an effort to address these failures, various modifications are commonly made to bone cement such as mechanical reinforcement with particles/fibers and the addition of antibiotics to mitigate PJI. Despite these attempts, issues such as poor particle interfacial adhesion, inadequate drug release, and the development of multidrug resistant bacteria limit the effectiveness of bone cement modifications. Therefore, the overall goal of this work was to use micro and nanoparticles to enhance the properties of acrylic bone cement, with particular emphasis placed on improving the mechanical properties, cumulative antibiotic release, and antimicrobial properties. An acrylic bone cement (Palacos R) was modified with three types of particles in various loading ratios: mesoporous silica nanoparticles (for mechanical reinforcement), xylitol microparticles (for increased antibiotic release), and silver nanoparticles (as an antimicrobial agent). These particles were used as sole modifications, not in tandem with one another. The resulting cement composites were characterized using a variety of mechanical (macro to nano, fatigue, fracture, and dynamic), imaging, chemical, thermal, biological, and antimicrobial testing techniques. The primary outcomes of this dissertation demonstrate that: (1) mesoporous silica, as used in this work, is a poor reinforcement phase for acrylic bone cement, (2) xylitol can significantly

  20. Characterisation of poly(alkyl methacrylate)s by means of electrospray ionisation-tandem mass spectrometry (ESI-MS/MS)

    NASA Astrophysics Data System (ADS)

    Jackson, Anthony T.; Slade, Susan E.; Scrivens, James H.

    2004-11-01

    Electrospray ionisation-tandem mass spectrometry (ESI-MS/MS) has been employed for the characterisation of two poly(alkyl methacrylate) polymers, namely poly(methyl methacrylate) (PMMA) and poly(n-butyl methacrylate) (PBMA). Collision-induced dissociation (CID) experiments were performed in a quadrupole orthogonal time-of-flight (ToF) tandem mass spectrometer fitted with a nanospray source. Tandem mass spectra from singly, doubly and triply charged precursor ions (with alkali metals used for cationisation of the oligomers) are shown and the data are compared to those previously generated by means of matrix-assisted laser desorption/ionisation-collision-induced dissociation (MALDI-CID). These data indicate that cations with greater ionic radii may yield the most useful structural information as the mass-to-charge ratio of the precursor ion increases, whereas lithium or sodium ions are proposed to be ideal for obtaining spectra from lower molecular weight oligomers. Fragment ions at low mass-to-charge ratios dominate the spectra. Two series of peaks may be used to calculate the masses of the initiating and terminating end groups of the polymer. Ion peaks of greater mass-to-charge ratios form series that may be used to infer sequence information from the polymers.