Sample records for porous polymer coatings

  1. Porous polymer coatings on metal microneedles for enhanced drug delivery

    NASA Astrophysics Data System (ADS)

    Ullah, Asad; Kim, Chul Min; Kim, Gyu Man

    2018-04-01

    We present a simple method to coat microneedles (MNs) uniformly with a porous polymer (PLGA) that can deliver drugs at high rates. Stainless steel (SS) MNs of high mechanical strength were coated with a thin porous polymer layer to enhance their delivery rates. Additionally, to improve the interfacial adhesion between the polymer and MNs, the MN surface was modified by plasma treatment followed by dip coating with polyethyleneimine, a polymer with repeating amine units. The average failure load (the minimum force sufficient for detaching the polymer layer from the surface of SS) recorded for the modified surface coating was 25 N, whereas it was 2.2 N for the non-modified surface. Calcein dye was successfully delivered into porcine skin to a depth of 750 µm by the porous polymer-coated MNs, demonstrating that the developed MNs can pierce skin easily without deformation of MNs; additional skin penetration tests confirmed this finding. For visual comparison, rhodamine B dye was delivered using porous-coated and non-coated MNs in gelatin gel which showed that delivery with porous-coated MNs penetrate deeper when compared with non-coated MNs. Finally, lidocaine and rhodamine B dye were delivered in phosphate-buffered saline (PBS) medium by porous polymer-coated and non-coated MNs. For rhodamine B, drug delivery with the porous-coated MNs was five times higher than that with the non-coated MNs, whereas 25 times more lidocaine was delivered by the porous-coated MNs compared with the non-coated MNs.

  2. 21 CFR 888.3565 - Knee joint patellofemorotibial metal/polymer porous-coated uncemented prosthesis.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Knee joint patellofemorotibial metal/polymer... Devices § 888.3565 Knee joint patellofemorotibial metal/polymer porous-coated uncemented prosthesis. (a) Identification. A knee joint patellofemorotibial metal/polymer porous-coated uncemented prosthesis is a device...

  3. 21 CFR 888.3565 - Knee joint patellofemorotibial metal/polymer porous-coated uncemented prosthesis.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Knee joint patellofemorotibial metal/polymer... Devices § 888.3565 Knee joint patellofemorotibial metal/polymer porous-coated uncemented prosthesis. (a) Identification. A knee joint patellofemorotibial metal/polymer porous-coated uncemented prosthesis is a device...

  4. 21 CFR 888.3565 - Knee joint patellofemorotibial metal/polymer porous-coated uncemented prosthesis.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Knee joint patellofemorotibial metal/polymer... Devices § 888.3565 Knee joint patellofemorotibial metal/polymer porous-coated uncemented prosthesis. (a) Identification. A knee joint patellofemorotibial metal/polymer porous-coated uncemented prosthesis is a device...

  5. 21 CFR 888.3565 - Knee joint patellofemorotibial metal/polymer porous-coated uncemented prosthesis.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Knee joint patellofemorotibial metal/polymer... Devices § 888.3565 Knee joint patellofemorotibial metal/polymer porous-coated uncemented prosthesis. (a) Identification. A knee joint patellofemorotibial metal/polymer porous-coated uncemented prosthesis is a device...

  6. 21 CFR 888.3358 - Hip joint metal/polymer/metal semi-constrained porous-coated uncemented prosthesis.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Hip joint metal/polymer/metal semi-constrained... Devices § 888.3358 Hip joint metal/polymer/metal semi-constrained porous-coated uncemented prosthesis. (a) Identification. A hip joint metal/polymer/metal semi-constrained porous-coated uncemented prosthesis is a device...

  7. Static Corrosion Test of Porous Iron Material with Polymer Coating

    NASA Astrophysics Data System (ADS)

    Markušová-Bučková, Lucia; Oriňaková, Renáta; Oriňak, Andrej; Gorejová, Radka; Kupková, Miriam; Hrubovčáková, Monika; Baláž, Matej; Kováľ, Karol

    2016-12-01

    At present biodegradable implants received increased attention due to their use in various fields of medicine. This work is dedicated to testing of biodegradable materials which could be used as bone implants. The samples were prepared from the carbonyl iron powder by replication method and surface polymer film was produced through sol-gel process. Corrosion testing was carried out under static conditions during 12 weeks in Hank's solution. The quantity of corrosion products increased with prolonging time of static test as it can be concluded from the results of EDX analysis. The degradation of open cell materials with polyethylene glycol coating layer was faster compared to uncoated Fe sample. Also the mass losses were higher for samples with PEG coating. The polymer coating brought about the desired increase in degradation rate of porous iron material.

  8. 21 CFR 888.3670 - Shoulder joint metal/polymer/metal nonconstrained or semi-constrained porous-coated uncemented...

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Shoulder joint metal/polymer/metal nonconstrained... ORTHOPEDIC DEVICES Prosthetic Devices § 888.3670 Shoulder joint metal/polymer/metal nonconstrained or semi-constrained porous-coated uncemented prosthesis. (a) Identification. A shoulder joint metal/polymer/metal...

  9. "Thunderstruck": Plasma-Polymer-Coated Porous Silicon Microparticles As a Controlled Drug Delivery System.

    PubMed

    McInnes, Steven J P; Michl, Thomas D; Delalat, Bahman; Al-Bataineh, Sameer A; Coad, Bryan R; Vasilev, Krasimir; Griesser, Hans J; Voelcker, Nicolas H

    2016-02-01

    Controlling the release kinetics from a drug carrier is crucial to maintain a drug's therapeutic window. We report the use of biodegradable porous silicon microparticles (pSi MPs) loaded with the anticancer drug camphothecin, followed by a plasma polymer overcoating using a loudspeaker plasma reactor. Homogenous "Teflon-like" coatings were achieved by tumbling the particles by playing AC/DC's song "Thunderstruck". The overcoating resulted in a markedly slower release of the cytotoxic drug, and this effect correlated positively with the plasma polymer coating times, ranging from 2-fold up to more than 100-fold. Ultimately, upon characterizing and verifying pSi MP production, loading, and coating with analytical methods such as time-of-flight secondary ion mass spectrometry, scanning electron microscopy, thermal gravimetry, water contact angle measurements, and fluorescence microscopy, human neuroblastoma cells were challenged with pSi MPs in an in vitro assay, revealing a significant time delay in cell death onset.

  10. Influence of natural organic matter on transport and retention of polymer coated silver nanoparticles in porous media.

    PubMed

    Yang, Xinyao; Lin, Shihong; Wiesner, Mark R

    2014-01-15

    Interactions between organic matter (OM) and engineered polymer coatings as they affect the retention of polyvinylpyrrolidone (PVP) polymer-coated silver nanoparticles (AgNPs) were studied. Two distinct types of OM-cysteine representing low molecular weight multivalent functional groups, and Suwannee River Humic Acid (HA) representing high molecular weight polymers, were investigated with respect to their effects on particle stability in aggregation and deposition. Aggregation of the PVP coated AgNPs (PVP-AgNPs) was enhanced by cysteine addition at high ionic strengths, which was attributed to cysteine binding to the AgNPs and replacing the otherwise steric stabilizing agent PVP. In contrast the addition of HA did not increase aggregation rates and decreased PVP-AgNP deposition to the silica porous medium, consistent with enhanced electrosteric stabilization by the HA. Although cysteine also reduced deposition in the porous medium, the mechanisms of reduced deposition appear to be enhanced electric double layer (EDL) interaction at low ionic strengths. At higher ionic strengths, aggregation was favored leading to lower deposition due to smaller diffusion coefficients and single collector efficiencies despite the reduced EDL interactions. Copyright © 2013 Elsevier B.V. All rights reserved.

  11. Porous structures of polymer films prepared by spin coating with mixed solvents under humid condition.

    PubMed

    Park, Min Soo; Joo, Wonchul; Kim, Jin Kon

    2006-05-09

    We investigate the effects of interfacial energy between water and solvent as well as polymer concentration on the formation of porous structures of polymer films prepared by spin coating of cellulose acetate butyrate (CAB) in mixed solvent of tetrahydrofuran (THF) and chloroform under humid condition. The interfacial energy between water and the solvent was gradually changed by the addition of chloroform to the solvent. At a high polymer concentration (0.15 g/cm3 in THF), porous structures were limited only at the top surfaces of CAB films, regardless of interfacial energies, due to the high viscosity of the solution. At a medium concentration (approximately 0.08 g/cm3 in THF), CAB film had relatively uniform pores at the top surface and very small pores inside the film because of the mixing of the water droplets with THF solution. When chloroform was added to THF, pores at the inner CAB film had a comparable size with those at the top surface because of the reduced degree of the mixing between the water droplets and the mixed solvent. A further decrease in polymer concentration (0.05 g/cm3 in THF) caused the final films to have a two-layer porous structure, and the size of pores at each layer was almost the same.

  12. Porous palladium coated conducting polymer nanoparticles for ultrasensitive hydrogen sensors

    NASA Astrophysics Data System (ADS)

    Lee, Jun Seop; Kim, Sung Gun; Cho, Sunghun; Jang, Jyongsik

    2015-12-01

    Hydrogen, a clean-burning fuel, is of key importance to various industrial applications, including fuel cells and in the aerospace and automotive industries. However, hydrogen gas is odorless, colorless, and highly flammable; thus appropriate safety protocol implementation and monitoring are essential. Highly sensitive hydrogen leak detection and surveillance sensor systems are needed; additionally, the ability to maintain uniformity through repetitive hydrogen sensing is becoming increasingly important. In this report, we detail the fabrication of porous palladium coated conducting polymer (3-carboxylate polypyrrole) nanoparticles (Pd@CPPys) to detect hydrogen gas. The Pd@CPPys are produced by means of facile alkyl functionalization and chemical reduction of a pristine 3-carboxylate polypyrrole nanoparticle-contained palladium precursor (PdCl2) solution. The resulting Pd@CPPy-based sensor electrode exhibits ultrahigh sensitivity (0.1 ppm) and stability toward hydrogen gas at room temperature due to the palladium sensing layer.Hydrogen, a clean-burning fuel, is of key importance to various industrial applications, including fuel cells and in the aerospace and automotive industries. However, hydrogen gas is odorless, colorless, and highly flammable; thus appropriate safety protocol implementation and monitoring are essential. Highly sensitive hydrogen leak detection and surveillance sensor systems are needed; additionally, the ability to maintain uniformity through repetitive hydrogen sensing is becoming increasingly important. In this report, we detail the fabrication of porous palladium coated conducting polymer (3-carboxylate polypyrrole) nanoparticles (Pd@CPPys) to detect hydrogen gas. The Pd@CPPys are produced by means of facile alkyl functionalization and chemical reduction of a pristine 3-carboxylate polypyrrole nanoparticle-contained palladium precursor (PdCl2) solution. The resulting Pd@CPPy-based sensor electrode exhibits ultrahigh sensitivity (0.1 ppm

  13. Porous organic polymers with different pore structures for sensitive solid-phase microextraction of environmental organic pollutants.

    PubMed

    Huang, Zhoubing; Liu, Shuqin; Xu, Jianqiao; Yin, Li; Zheng, Juan; Zhou, Ningbo; Ouyang, Gangfeng

    2017-10-09

    Adsorption capacity is the major sensitivity-limited factor in solid-phase microextraction. Due to its light-weight properties, large specific surface area and high porosity, especially tunable pore structures, the utilization of porous organic polymers as solid-phase microextraction adsorbents has attracting researchers' attentions. However, these works mostly concentrated on the utilization of specific porous organic polymers for preparing high-performance solid-phase microextraction coatings. The relationship between pore structures and adsorption performance of the porous organic polymers still remain unclear. Herein, three porous organic polymers with similar properties but different pore distributions were prepared by condensation polymerization reaction of phloroglucinol and terephthalaldehyde, which were fabricated as solid-phase microextraction coatings subsequently. The adsorption capacity of the porous organic polymers-coated fibers were evaluated by using benzene and its derivatives (i.e.,benzene, toluene, ethylbenzene and m-xylene) and polycyclic aromatic hydrocarbons as the target analytes. The results showed that the different adsorption performance of these porous organic polymers was mainly caused by their different pore volumes instead of their surface areas or pore sizes. Finally, the proposed method by using the mesoporous organic polymer coating was successfully applied to the determination of benzene and its derivatives in environmental water samples. As for analytical performance, high pre-concentration factors (74-2984), satisfactory relative recoveries (94.5 ± 18.5-116.9 ± 12.5%), intraday precision (2.44-5.34%), inter-day precision (4.62-7.02%), low limit of detections (LODs, 0.10-0.29 ng L -1 ) and limit of quantifications (LOQs, 0.33-0.96 ng L -1 ) were achieved under the optimal conditions. This study provides an important idea in the rational design of porous organic polymers for solid-phase microextraction or other

  14. Thermal Spray Formation of Polymer Coatings

    NASA Technical Reports Server (NTRS)

    Coquill, Scott; Galbraith, Stephen L.; Tuss. Darren L.; Ivosevic, Milan

    2008-01-01

    This innovation forms a sprayable polymer film using powdered precursor materials and an in-process heating method. This device directly applies a powdered polymer onto a substrate to form an adherent, mechanically-sound, and thickness-regulated film. The process can be used to lay down both fully dense and porous, e.g., foam, coatings. This system is field-deployable and includes power distribution, heater controls, polymer constituent material bins, flow controls, material transportation functions, and a thermal spray apparatus. The only thing required for operation in the field is a power source. Because this method does not require solvents, it does not release the toxic, volatile organic compounds of previous methods. Also, the sprayed polymer material is not degraded because this method does not use hot combustion gas or hot plasma gas. This keeps the polymer from becoming rough, porous, or poorly bonded.

  15. Comparison on mechanical properties of single layered and bilayered chitosan-gelatin coated porous hydroxyapatite scaffold prepared through freeze drying method

    NASA Astrophysics Data System (ADS)

    Effendi, M. D.; Gustiono, D.; Lukmana; Ayu, D.; Kurniawati, F.

    2017-02-01

    Biopolymer coated porous hydroxyapatite (HA) scaffolds were prepared for tissue engineering trough freeze drying method and impregnation. in this study, to mimic the mineral and organic component of natural bone, synthetic hydroxapatite (HA) scaffolds coated by polymer were prepared. Highly porous Hap scaffolds, fabricated by synthetic HA impregnation method on polyurethane foam, were coated with polymer coating solution, consisting of chitosan, Gelatin, and bilayered chitosan-gelatin prepared by aging and impregnating technique. For the purpose of comparison, The bare scaffolds without polymer coating layer were investigated. The Bare scaffolds were highly porous and interconnected with a pore size of around 150 µm-714 µm, has porosity at around 67,7% -85,7%, and has mechanical strength at around 0.06 Mpa - 0.071 Mpa, which is suitable for osteoblast cell Proliferation. Chitosan coated porous HA scaffold and gelatin coated porous HA scaffold had mechanical strength at around 0.81-0.85 Mpa, and 1.32-1.34 Mpa, respectively, with weight ratio of biopolymer and Hap was around 18%-22%. To compare these results, the coating on the bare scaffold with gelatin and chitosan had been conducted. Based on the result of FTIR, it could be concluded that coating procedure applied on porous hydroxy apatite (HA) coated by gelatin, chitosan coated HA scaffold, and bilayered Gelatin-chitosan coated porous HA scaffold, confirming that for allsampleshad no significant chemical effect on the coating structure. The compressive strength of bilayered Gelatin-chitosan coated HA scaffold had middle values between the rest, at around 1,06-1.2 Mpa for the samples at the same weight ratio of biopolymer: HA (around 18% - 22%). These results also confirming that coating by gelatin on porous hydroxyapatite was highest compresive strength and can be applied to improve mechanical properties of porous hydroxyapatite bare scaffold

  16. Fabrication of porous hierarchical polymer/ceramic composites by electron irradiation of organic/inorganic polymers: route to a highly durable, large-area superhydrophobic coating.

    PubMed

    Lee, Eun Je; Kim, Jae Joon; Cho, Sung Oh

    2010-03-02

    Polymer/ceramic composite films with micro- and nanocombined hierarchical structures are fabricated by electron irradiation of poly(methyl methacrylate) (PMMA) microspheres/silicone grease. Electron irradiation induces volume contraction of PMMA microspheres and simultaneously transforms silicone grease into a ceramic material of silicon oxycarbide with many nanobumps. As a result, highly porous structures that consist of micrometer-sized pores and microparticles decorated with nanobumps are created. The fabricated films with the porous hierarchical structure exhibit good superhydrophobicity with excellent self-cleaning and antiadhesion properties after surface treatment with fluorosilane. In addition, the porous hierarchical structures are covered with silicon oxycarbide, and thus the superhydrophobic coatings have high hardness and strong adhesion to the substrate. The presented technique provides a straightforward route to producing large-area, mechanically robust superhydrophobic films on various substrate materials.

  17. Biocorrosion behavior and cell viability of adhesive polymer coated magnesium based alloys for medical implants

    NASA Astrophysics Data System (ADS)

    Abdal-hay, Abdalla; Dewidar, Montasser; Lim, Jae Kyoo

    2012-11-01

    The present study was ultimately aimed to design novel adhesive biodegradable polymer, poly(vinyl acetate) (PVAc), coatings onto Mg based alloys by the dip-coating technique in order to control the degradation rate and enhance the biocompatibility of magnesium alloys. The influence of various solvents on PVAc surface topography and their protection of Mg alloys were dramatically studied in vitro. Electrochemical polarization, degradation, and PVAc film cytocompatibility were also tested. Our results showed that the solvent had a significant effect on coating quality. PVAc/dichloromethane solution showed a porous structure and solution concentration could control the porous size. The coatings prepared using tetrahydrofuran and dimethylformamide solvents are exceptional in their ability to generate porous morphology even at low polymer concentration. In general, the corrosion performance appears to be different on different PVAc-solvent system. Immersion tests illustrated that the porous morphology on PVAc stabilized corrosion rates. A uniform corrosion attack in artificial simulation body fluid was also exhibited. The cytocompatibility of osteoblast cells (MC3T3) revealed high adherence, proliferation, and survival on the porous structure of PVAc coated Mg alloy, which was not observed for the uncoated samples. This novel PVAc coating is a promising candidate for biodegradable implant materials, which might widen the use of Mg based implants.

  18. Porous polymer media

    DOEpatents

    Shepodd, Timothy J.

    2002-01-01

    Highly crosslinked monolithic porous polymer materials for chromatographic applications. By using solvent compositions that provide not only for polymerization of acrylate monomers in such a fashion that a porous polymer network is formed prior to phase separation but also for exchanging the polymerization solvent for a running buffer using electroosmotic flow, the need for high pressure purging is eliminated. The polymer materials have been shown to be an effective capillary electrochromatographic separations medium at lower field strengths than conventional polymer media. Further, because of their highly crosslinked nature these polymer materials are structurally stable in a wide range of organic and aqueous solvents and over a pH range of 2-12.

  19. Porous and non-porous water soluble polymer nanospheres

    NASA Astrophysics Data System (ADS)

    Henselwood, Fred William

    Water soluble polymer nanospheres have been prepared from the photo-cross-linking of diblock copolymer micelles formed either in water or in N,N-dimethylformamide/water mixtures. The diblock copolymers utilized in this study were poly(2-cinnamoyl-ethyl methacrylate)-block-poly(acrylic acid), poly ((2-cinnamoylethyl methacrylate)-random-(2-octanoylethyl methacrylate)) -block-poly(acrylic acid), and poly ((2-cinnamoyl-ethyl methacrylate)-random-(2-oleoylethyl methacrylate)) -block-poly(acrylic acid). These polymers were synthesized by the functionalization of diblock copolymers prepared by anionic polymerization. The photo-cross-linking was achieved through the dimerization of cinnamoyl groups by ultraviolet irradiation. Transmission electron microscopy confirmed that the polymer nanospheres had an inner core region formed by the cinnamoyl containing polymer blocks, and an outer shell layer formed by the acrylic acid polymer blocks. The hydrodynamic radius of the polymer nanospheres in water was approximately 50 to 75 nm as determined by dynamic light scattering. It has been found that the polymer nanospheres, when in water, could be readily impregnated with organic molecules. Fluorescence measurements showed that the polymer nanospheres could uptake polyaromatic hydrocarbons by the direct mixing of polyaromatic hydrocarbons with the polymer nanospheres in water. Perylene was found to be between 2.0 × 10sp5 and 4.0 × 10sp5 times more soluble in the core region of the polymer nanospheres than in water. The addition of divalent cations was shown to induce aggregation of the polymer nanospheres and resulted in the precipitation of the polymer nanospheres along with any captured perylene. This suggests that the polymer nanospheres may be useful in water remediation. Porous polymer nanospheres were prepared by the incorporation of low molecular weight polymeric porogens within the core region of the polymer nanospheres. Following photo-cross-linking the polymeric

  20. Porous light-emitting compositions

    DOEpatents

    Burrell, Anthony K [Los Alamos, NM; McCleskey, Thomas Mark [Los Alamos, NM; Jia, Quanxi [Los Alamos, NM; Bauer, Eve [Los Alamos, NM; Mueller, Alexander H [Los Alamos, NM

    2012-04-17

    Light-emitting devices are prepared by coating a porous substrate using a polymer-assisted deposition process. Solutions of metal precursor and soluble polymers having binding properties for metal precursor were coated onto porous substrates. The coated substrates were heated at high temperatures under a suitable atmosphere. The result was a substrate with a conformal coating that did not substantially block the pores of the substrate.

  1. Silver/hydroxyapatite composite coatings on porous titanium surfaces by sol-gel method.

    PubMed

    Qu, Jie; Lu, Xiong; Li, Dan; Ding, Yonghui; Leng, Yang; Weng, Jie; Qu, Shuxin; Feng, Bo; Watari, Fumio

    2011-04-01

    Hydroxyapatite (HA) coatings loaded with nanosilver particles is an attractive method to impart the HA coating with antibacterial properties. Producing Ag/HA coatings on porous Ti substrates have been an arduous job since commonly used line-of-sight techniques are not able to deposit uniform coatings on the inner pore surfaces of the porous Ti. In this study, porous Ti scaffolds with high porosity and interconnected structures were prepared by polymer impregnating method. A sol-gel process was used to produce uniform Ag/HA composite coatings on the surfaces of porous Ti substrates. Ca(NO(3) )(2) ·4H(2) O and P(2) O(5) in an ethyl alcohol based system was selected to prepare the sol, which ensured the homogeneous distribution of Ag in the sol. The characterization revealed that silver particles uniformly distributed in the coatings without agglomeration. High antibacterial ratio (>95%), against E. coli and S. albus was expressed by the silver-containing coatings (Ag/HA 0.8 and 1.6 wt %). The biocompatibility of the Ag/HA 0.8 surfaces was as good as that of pure HA surface, as revealed by culturing osteoblasts on them. The results indicated that Ag/HA 0.8 had the good balance between the biocompatibility and antibacterial properties of the coatings. Copyright © 2011 Wiley Periodicals, Inc.

  2. Polymer-Coated Graphene Aerogel Beads and Supercapacitor Application.

    PubMed

    Ouyang, An; Cao, Anyuan; Hu, Song; Li, Yanhui; Xu, Ruiqiao; Wei, Jinquan; Zhu, Hongwei; Wu, Dehai

    2016-05-04

    Graphene aerogels are highly porous materials with many energy and environmental applications; tailoring the structure and composition of pore walls within the aerogel is the key to those applications. Here, by freeze casting the graphene oxide sheets, we directly fabricated freestanding porous graphene beads containing radially oriented through channels from the sphere center to its surface. Furthermore, we introduced pseudopolymer to make reinforced, functional composite beads with a unique pore morphology. We showed that polymer layers can be coated smoothly on both sides of the pore walls, as well as on the junctions between adjacent pores, resulting in uniform polymer-graphene-polymer sandwiched structures (skeletons) throughout the bead. These composite beads significantly improved the electrochemical properties, with specific capacitances up to 669 F/g and good cyclic stability. Our results indicate that controlled fabrication of homogeneous hierarchical structures is a potential route toward high performance composite electrodes for various energy applications.

  3. Mechanical properties of polymer-modified porous concrete

    NASA Astrophysics Data System (ADS)

    Ariffin, N. F.; Jaafar, M. F. Md.; Shukor Lim, N. H. Abdul; Bhutta, M. A. R.; Hussin, M. W.

    2018-04-01

    In this research work, polymer-modified porous concretes (permeable concretes) using polymer latex and redispersible polymer powder with water-cement ratio of 30 %, polymer-cement ratios of 0 to 10 % and cement content of 300 kg/m3 are prepared. The porous concrete was tested for compressive strength, flexural strength, water permeability and void ratio. The cubes size of specimen is 100 mm ×100 mm × 100 mm and 150 mm × 150 mm × 150 mm while the beam size is 100 mm × 100 mm × 500 mm was prepared for particular tests. The tests results show that the addition of polymer as a binder to porous concrete gives an improvement on the strength properties and coefficient of water permeability of polymer-modified porous concrete. It is concluded from the test results that increase in compressive and flexural strengths and decrease in the coefficient of water permeability of the polymer-modified porous concrete are clearly observed with increasing of polymer-cement ratio.

  4. Nanoparticle/Polymer Nanocomposite Bond Coat or Coating

    NASA Technical Reports Server (NTRS)

    Miller, Sandi G.

    2011-01-01

    This innovation addresses the problem of coatings (meant to reduce gas permeation) applied to polymer matrix composites spalling off in service due to incompatibility with the polymer matrix. A bond coat/coating has been created that uses chemically functionalized nanoparticles (either clay or graphene) to create a barrier film that bonds well to the matrix resin, and provides an outstanding barrier to gas permeation. There is interest in applying clay nanoparticles as a coating/bond coat to a polymer matrix composite. Often, nanoclays are chemically functionalized with an organic compound intended to facilitate dispersion of the clay in a matrix. That organic modifier generally degrades at the processing temperature of many high-temperature polymers, rendering the clay useless as a nano-additive to high-temperature polymers. However, this innovation includes the use of organic compounds compatible with hightemperature polymer matrix, and is suitable for nanoclay functionalization, the preparation of that clay into a coating/bondcoat for high-temperature polymers, the use of the clay as a coating for composites that do not have a hightemperature requirement, and a comparable approach to the preparation of graphene coatings/bond coats for polymer matrix composites.

  5. Preparation and Performance of Plasma/Polymer Composite Coatings on Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Bakhsheshi-Rad, H. R.; Hamzah, E.; Bagheriyan, S.; Daroonparvar, M.; Kasiri-Asgarani, M.; Shah, A. M.; Medraj, M.

    2016-09-01

    A triplex plasma (NiCoCrAlHfYSi/Al2O3·13%TiO2)/polycaprolactone composite coating was successfully deposited on a Mg-1.2Ca alloy by a combination of atmospheric plasma spraying and dip-coating techniques. The NiCoCrAlHfYSi (MCrAlHYS) coating, as the first layer, contained a large number of voids, globular porosities, and micro-cracks with a thickness of 40-50 μm, while the Al2O3·13%TiO2 coating, as the second layer, presented a unique bimodal microstructure with a thickness of 70-80 μm. The top layer was a hydrophobic polymer, which effectively sealed the porosities of plasma layers. The results of micro-hardness and bonding strength tests showed that the plasma coating presented excellent hardness (870 HV) and good bonding strength (14.8 MPa). However, the plasma/polymer coatings interface exhibited low bonding strength (8.6 MPa). The polymer coating formed thick layer (100-110 μm) that homogeneously covered the surface of the plasma layers. Contact angle measurement showed that polymer coating over plasma layers significantly decreased surface wettability. The corrosion current density ( i corr) of an uncoated sample (262.7 µA/cm2) decreased to 76.9 µA/cm2 after plasma coatings were applied. However, it was found that the i corr decreased significantly to 0.002 µA/cm2 after polymer sealing of the porous plasma layers.

  6. Development of PVA based micro-porous polymer electrolyte by a novel preferential polymer dissolution process

    NASA Astrophysics Data System (ADS)

    Subramania, A.; Kalyana Sundaram, N. T.; Sukumar, N.

    A micro-porous polymer electrolyte based on PVA was obtained from PVA-PVC based polymer blend film by a novel preferential polymer dissolution technique. The ionic conductivity of micro-porous polymer electrolyte increases with increase in the removal of PVC content. Finally, the effect of variation of lithium salt concentration is studied for micro-porous polymer electrolyte of high ionic conductivity composition. The ionic conductivity of the micro-porous polymer electrolyte is measured in the temperature range of 301-351 K. It is observed that a 2 M LiClO 4 solution of micro-porous polymer electrolyte has high ionic conductivity of 1.5055 × 10 -3 S cm -1 at ambient temperature. Complexation and surface morphology of the micro-porous polymer electrolytes are studied by X-ray diffraction and SEM analysis. TG/DTA analysis informs that the micro-porous polymer electrolyte is thermally stable upto 277.9 °C. Chronoamperommetry and linear sweep voltammetry studies were made to find out lithium transference number and stability of micro-porous polymer electrolyte membrane, respectively. Cyclic voltammetry study was performed for carbon/micro-porous polymer electrolyte/LiMn 2O 4 cell to reveal the compatibility and electrochemical stability between electrode materials.

  7. Porous Shape Memory Polymers

    PubMed Central

    Hearon, Keith; Singhal, Pooja; Horn, John; Small, Ward; Olsovsky, Cory; Maitland, Kristen C.; Wilson, Thomas S.; Maitland, Duncan J.

    2013-01-01

    Porous shape memory polymers (SMPs) include foams, scaffolds, meshes, and other polymeric substrates that possess porous three-dimensional macrostructures. Porous SMPs exhibit active structural and volumetric transformations and have driven investigations in fields ranging from biomedical engineering to aerospace engineering to the clothing industry. The present review article examines recent developments in porous SMPs, with focus given to structural and chemical classification, methods of characterization, and applications. We conclude that the current body of literature presents porous SMPs as highly interesting smart materials with potential for industrial use. PMID:23646038

  8. Microfluidic devices and methods including porous polymer monoliths

    DOEpatents

    Hatch, Anson V; Sommer, Gregory J; Singh, Anup K; Wang, Ying-Chih; Abhyankar, Vinay V

    2014-04-22

    Microfluidic devices and methods including porous polymer monoliths are described. Polymerization techniques may be used to generate porous polymer monoliths having pores defined by a liquid component of a fluid mixture. The fluid mixture may contain iniferters and the resulting porous polymer monolith may include surfaces terminated with iniferter species. Capture molecules may then be grafted to the monolith pores.

  9. Microfluidic devices and methods including porous polymer monoliths

    DOEpatents

    Hatch, Anson V.; Sommer, Gregory j.; Singh, Anup K.; Wang, Ying-Chih; Abhyankar, Vinay

    2015-12-01

    Microfluidic devices and methods including porous polymer monoliths are described. Polymerization techniques may be used to generate porous polymer monoliths having pores defined by a liquid component of a fluid mixture. The fluid mixture may contain iniferters and the resulting porous polymer monolith may include surfaces terminated with iniferter species. Capture molecules may then be grafted to the monolith pores.

  10. Compressibility of porous TiO2 nanoparticle coating on paperboard

    PubMed Central

    2013-01-01

    Compressibility of liquid flame spray-deposited porous TiO2 nanoparticle coating was studied on paperboard samples using a traditional calendering technique in which the paperboard is compressed between a metal and polymer roll. Surface superhydrophobicity is lost due to a smoothening effect when the number of successive calendering cycles is increased. Field emission scanning electron microscope surface and cross‒sectional images support the atomic force microscope roughness analysis that shows a significant compressibility of the deposited TiO2 nanoparticle coating with decrease in the surface roughness and nanoscale porosity under external pressure. PACS 61.46.-w; 68.08.Bc; 81.07.-b PMID:24160373

  11. Moisture sensor based on evanescent wave light scattering by porous sol-gel silica coating

    DOEpatents

    Tao, Shiquan; Singh, Jagdish P.; Winstead, Christopher B.

    2006-05-02

    An optical fiber moisture sensor that can be used to sense moisture present in gas phase in a wide range of concentrations is provided, as well techniques for making the same. The present invention includes a method that utilizes the light scattering phenomenon which occurs in a porous sol-gel silica by coating an optical fiber core with such silica. Thus, a porous sol-gel silica polymer coated on an optical fiber core forms the transducer of an optical fiber moisture sensor according to an embodiment. The resulting optical fiber sensor of the present invention can be used in various applications, including to sense moisture content in indoor/outdoor air, soil, concrete, and low/high temperature gas streams.

  12. Photoinitiated grafting of porous polymer monoliths and thermoplastic polymers for microfluidic devices

    DOEpatents

    Frechet, Jean M. J. [Oakland, CA; Svec, Frantisek [Alameda, CA; Rohr, Thomas [Leiden, NL

    2008-10-07

    A microfluidic device preferably made of a thermoplastic polymer that includes a channel or a multiplicity of channels whose surfaces are modified by photografting. The device further includes a porous polymer monolith prepared via UV initiated polymerization within the channel, and functionalization of the pore surface of the monolith using photografting. Processes for making such surface modifications of thermoplastic polymers and porous polymer monoliths are set forth.

  13. Porous carbon-coated graphite electrodes for energy production from salinity gradient using reverse electrodialysis

    NASA Astrophysics Data System (ADS)

    Lee, Su-Yoon; Jeong, Ye-Jin; Chae, So-Ryong; Yeon, Kyeong-Ho; Lee, Yunkyu; Kim, Chan-Soo; Jeong, Nam-Jo; Park, Jin-Soo

    2016-04-01

    Performance of graphite foil electrodes coated by porous carbon black (i.e., Vulcan) was investigated in comparison with metal electrodes for reverse electrodialysis (RED) application. The electrode slurry that was used for fabrication of the porous carbon-coated graphite foil is composed of 7.2 wt% of carbon black (Vulcan X-72), 0.8 wt% of a polymer binder (polyvinylidene fluoride, PVdF), and 92.0 wt% of a mixing solvent (dimethylacetamide, DMAc). Cyclic voltammograms of both the porous carbon (i.e., Vulcan)-coated graphite foil electrode and the graphite foil electrode without Vulcan showed good reversibility in the hexacyanoferrate(III) (i.e., Fe(CN)63-) and hexacyanoferrate(II) (i.e., Fe(CN)64-) redox couple and 1 M Na2SO4 at room temperature. However, anodic and cathodic current of the Vulcan-coated graphite foil electrode was much higher than those of the graphite foil electrode. Using a bench-scale RED stack, the current-voltage polarization curve of the Vulcan-coated graphite electrode was compared to that of metal electrodes such as iridium (Ir) and platinum (Pt). From the results, it was confirmed that resistance of four different electrodes increased with the following order: the Vulcan-coated graphite foilcoated titanium (Ti) meshcoated Ti platecoated graphite foil showed 5-10% higher power density than the metal mesh electrodes. From the polarization curve of the Vulcan-coated graphite foil electrode, it was found that total resistance decreased as thickness and geometric surface area of the electrode increased.

  14. Optical coatings on polymers

    NASA Astrophysics Data System (ADS)

    Bauer, Thomas

    2005-09-01

    Optical transparent polymers are used for technical optics for more than 50 years and currently replace glass as optical material in several application fields. Optical functional coatings like mirrors, filters, beam splitters and anti-reflection coatings gain increasingly in importance. New light sources and head mounted systems need light and effective reflector designs. The paper gives an overview about vacuum coating technologies for metal and dielectric layers on polymers for technical optics. Especially for polymers controlling the complete process chain from injection moulding to storing, coating and shipping decides on the technological and commercial success.

  15. Thiazolothiazole-linked porous organic polymers

    DOE PAGES

    Zhu, Xiang; Tian, Chengcheng; Jin, Tian; ...

    2014-10-07

    In this study, thiazolothiazole-linked porous organic polymers have been synthesized from a facile catalyst-free condensation reaction between aldehydes and dithiooxamide under solvothermal conditions. The resultant porous frameworks exhibit a highly selective uptake of CO 2 over N 2 under ambient conditions.

  16. Antibacterial polymer coatings.

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wilson, Mollye C.; Allen, Ashley N.; Barnhart, Meghan

    2009-09-01

    A series of poly(sulfone)s with quaternary ammonium groups and another series with aldehyde groups are synthesized and tested for biocidal activity against vegetative bacteria and spores, respectively. The polymers are sprayed onto substrates as coatings which are then exposed to aqueous suspensions of organisms. The coatings are inherently biocidal and do not release any agents into the environment. The coatings adhere well to both glass and CARC-coated coupons and they exhibit significant biotoxicity. The most effective quaternary ammonium polymers kills 99.9% of both gram negative and gram positive bacteria and the best aldehyde coating kills 81% of the spores onmore » its surface.« less

  17. Characterization of Porous, Dexamethasone-Releasing Polyurethane Coatings for Glucose Sensors

    PubMed Central

    Vallejo-Heligon, Suzana G.; Klitzman, Bruce; Reichert, William M.

    2014-01-01

    Commercially available implantable needle-type glucose sensors for diabetes management are robust analytically but can be unreliable clinically primarily due to tissue-sensor interactions. Here, we present the physical, drug release, and bioactivity characterization of tubular, porous dexamethasone (Dex) releasing polyurethane coatings designed to attenuate local inflammation in the tissue-sensor interface. Porous polyurethane coatings were produced by the salt-leaching/gas-foaming method. Scanning electron microscopy (SEM) and Micro-computed tomography (Micro-CT) showed a controlled porosity and coating thickness. In vitro drug release from coatings monitored over two weeks presented an initial fast release followed by a slower release. Total release from coatings was highly dependent on initial drug loading amount. Functional in vitro testing of glucose sensors deployed with porous coatings against glucose standards demonstrated that highly porous coatings minimally affected signal strength and response rate. Bioactivity of the released drug was determined by monitoring Dex-mediated, dose-dependent apoptosis of human peripheral blood derived monocytes in culture. Acute animal studies were used to determine the appropriate Dex payload for the implanted porous coatings. Pilot short-term animal studies showed that Dex released from porous coatings implanted in rat subcutis attenuated the initial inflammatory response to sensor implantation. These results suggest that deploying sensors with the porous, Dex-releasing coatings is a promising strategy to improve glucose sensor performance. PMID:25065548

  18. Porous silicon photonic crystals as hosts for polymers, biopolymers, and magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Li, Yang Yang

    This thesis describes the construction of one-dimensional photonic crystals of porous silicon by electrochemically etching and the use of these materials as hosts for polymers, biopolymers, and magnetic nanoparticles. The spectral features of the photonic crystals derive from a porosity gradient that is determined by the electrochemical etching parameters. Since the photonic crystals are constructed of a porous material, they can serve as hosts for other materials. The first chapter of the thesis provides an introduction to porous Si, templating techniques and the use of porous materials for controlled release of drugs. This latter section is added because much of the thesis work addresses the application of porous Si hosts for controlled release of drugs. In the second chapter, it is shown that the spectral properties of the porous Si photonic crystal template can be transferred to a variety of organic and biopolymers. It is demonstrated that these castings can be used as vapor sensors and as self-reporting, bioresorbable materials. If the template is not removed, porous Si polymer composites are formed. The third chapter discussed that by spray-coating a fine mist of polymer solution onto the porous Si film, robust and smooth micron-sized cylindrical photonic crystals suitable for bioassays can be prepared. The fourth chapter focuses on using porous Si photonic crystals as a host for magnetic nanoparticles. The magnetic nanoparticles in this work are found to adhere to the surface of the porous Si film as well to infiltrate the pore structure. In a demonstration of optical switching that may be useful for information display applications, flipping between the colored to dark sides by application of a magnetic field is found to occur at rates of as large as 175 Hz. As the host for soluble molecular species, porous Si photonic crystals can be impregnated from solution. The aggregates that form upon evaporation of solvent are found to scatter light from the resonant

  19. Fabrication of highly uniform and porous MgF2 anti-reflective coatings by polymer-based sol-gel processing on large-area glass substrates.

    PubMed

    Raut, Hemant Kumar; Dinachali, Saman Safari; Ansah-Antwi, Kwadwo Konadu; Ganesh, V Anand; Ramakrishna, Seeram

    2013-12-20

    Despite recent progress in the fabrication of magnesium fluoride (MgF2) anti-reflective coatings (ARCs), simple, effective and scalable sol-gel fabrication of MgF2 ARCs for large-area glass substrates has prospective application in various optoelectronic devices. In this paper, a polymer-based sol-gel route was devised to fabricate highly uniform and porous MgF2 ARCs on large-area glass substrates. A sol-gel precursor made of polyvinyl acetate and magnesium trifluoroacetate assisted in the formation of uniformly mesoporous MgF2 ARCs on glass substrates, leading to the attainment of a refractive index of ~1.23. Systematic optimization of the thickness of the ARC in the sub-wavelength regime led to achieving ~99.4% transmittance in the case of the porous MgF2 ARC glass. Precise control of the thickness of porous MgF2 ARC glass also resulted in a mere ~0.1% reflection, virtually eliminating reflection off the glass surface at the target wavelength. Further manipulation of the thickness of the ARC on either side of the glass substrate led to the fabrication of relatively broadband, porous MgF2 ARC glass.

  20. In Vitro Evaluation of PCL and P(3HB) as Coating Materials for Selective Laser Melted Porous Titanium Implants.

    PubMed

    Grau, Michael; Matena, Julia; Teske, Michael; Petersen, Svea; Aliuos, Pooyan; Roland, Laura; Grabow, Niels; Murua Escobar, Hugo; Gellrich, Nils-Claudius; Haferkamp, Heinz; Nolte, Ingo

    2017-11-23

    Titanium is widely used as a bone implant material due to its biocompatibility and high resilience. Since its Young's modulus differs from bone tissue, the resulting "stress shielding" could lead to scaffold loosening. However, by using a scaffold-shaped geometry, the Young's modulus can be adjusted. Also, a porous geometry enables vascularisation and bone ingrowth inside the implant itself. Additionally, growth factors can improve these effects. In order to create a deposit and release system for these factors, the titanium scaffolds could be coated with degradable polymers. Therefore, in the present study, synthetic poly-ε-caprolactone (PCL) and the biopolymer poly(3-hydroxybutyrate) (P(3HB)) were tested for coating efficiency, cell adhesion, and biocompatibility to find a suitable coating material. The underlying scaffold was created from titanium by Selective Laser Melting (SLM) and coated with PCL or P(3HB) via dip coating. To test the biocompatibility, Live Cell Imaging (LCI) as well as vitality and proliferation assays were performed. In addition, cell adhesion forces were detected via Single Cell Force Spectroscopy, while the coating efficiency was observed using environmental scanning electron microscopy (ESEM) and energy-dispersive X-ray (EDX) analyses. Regarding the coating efficiency, PCL showed higher values in comparison to P(3HB). Vitality assays revealed decent vitality values for both polymers, while values for PCL were significantly lower than those for blank titanium. No significant differences could be observed between PCL and P(3HB) in proliferation and cell adhesion studies. Although LCI observations revealed decreasing values in cell number and populated area over time on both polymer-coated scaffolds, these outcomes could be explained by the possibility of coating diluent residues accumulating in the culture medium. Overall, both polymers fulfill the requirements regarding biocompatibility. Nonetheless, since only PCL coating ensured the

  1. In Vitro Evaluation of PCL and P(3HB) as Coating Materials for Selective Laser Melted Porous Titanium Implants

    PubMed Central

    Grau, Michael; Matena, Julia; Teske, Michael; Petersen, Svea; Aliuos, Pooyan; Roland, Laura; Grabow, Niels; Murua Escobar, Hugo; Gellrich, Nils-Claudius; Haferkamp, Heinz; Nolte, Ingo

    2017-01-01

    Titanium is widely used as a bone implant material due to its biocompatibility and high resilience. Since its Young’s modulus differs from bone tissue, the resulting “stress shielding” could lead to scaffold loosening. However, by using a scaffold-shaped geometry, the Young’s modulus can be adjusted. Also, a porous geometry enables vascularisation and bone ingrowth inside the implant itself. Additionally, growth factors can improve these effects. In order to create a deposit and release system for these factors, the titanium scaffolds could be coated with degradable polymers. Therefore, in the present study, synthetic poly-ε-caprolactone (PCL) and the biopolymer poly(3-hydroxybutyrate) (P(3HB)) were tested for coating efficiency, cell adhesion, and biocompatibility to find a suitable coating material. The underlying scaffold was created from titanium by Selective Laser Melting (SLM) and coated with PCL or P(3HB) via dip coating. To test the biocompatibility, Live Cell Imaging (LCI) as well as vitality and proliferation assays were performed. In addition, cell adhesion forces were detected via Single Cell Force Spectroscopy, while the coating efficiency was observed using environmental scanning electron microscopy (ESEM) and energy-dispersive X-ray (EDX) analyses. Regarding the coating efficiency, PCL showed higher values in comparison to P(3HB). Vitality assays revealed decent vitality values for both polymers, while values for PCL were significantly lower than those for blank titanium. No significant differences could be observed between PCL and P(3HB) in proliferation and cell adhesion studies. Although LCI observations revealed decreasing values in cell number and populated area over time on both polymer-coated scaffolds, these outcomes could be explained by the possibility of coating diluent residues accumulating in the culture medium. Overall, both polymers fulfill the requirements regarding biocompatibility. Nonetheless, since only PCL coating

  2. Protection of alodine coatings from thermal aging by removable polymer coatings.

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wagstaff, Brett R.; Bradshaw, Robert W.; Whinnery, LeRoy L., Jr.

    2006-12-01

    Removable polymer coatings were evaluated as a means to suppress dehydration of Alodine chromate conversion coatings during thermal aging and thereby retain the corrosion protection afforded by Alodine. Two types of polymer coatings were applied to Alodine-treated panels of aluminum alloys 7075-T73 and 6061-T6 that were subsequently aged for 15 to 50 hours at temperatures between 135 F to 200 F. The corrosion resistance of the thermally aged panels was evaluated, after stripping the polymer coatings, by exposure to a standard salt-fog corrosion test and the extent of pitting of the polymer-coated and untreated panels compared. Removable polymer coatings mitigatedmore » the loss of corrosion resistance due to thermal aging experienced by the untreated alloys. An epoxide coating was more effective than a fluorosilicone coating as a dehydration barrier.« less

  3. Phospholipid arrays on porous polymer coatings generated by micro-contact spotting

    PubMed Central

    de Freitas, Monica; Tröster, Lea-Marie; Jochum, Tobias; Levkin, Pavel A; Hirtz, Michael; Fuchs, Harald

    2017-01-01

    Nanoporous poly(2-hydroxyethyl methacrylate-co-ethylene dimethacrylate) (HEMA-EDMA) is used as a 3D mesh for spotting lipid arrays. Its porous structure is an ideal matrix for lipid ink to infiltrate, resulting in higher fluorescent signal intensity as compared to similar arrays on strictly 2D substrates like glass. The embedded lipid arrays show high stability against washing steps, while still being accessible for protein and antibody binding. To characterize binding to polymer-embedded lipids we have applied Streptavidin as well as biologically important biotinylated androgen receptor binding onto 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine-N-(cap biotinyl) (Biotinyl Cap PE) and anti-DNP IgE recognition of 2,4-dinitrophenyl[1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine-N-[6-[(2,4-dinitrophenyl)amino]hexanoyl] (DNP)] antigen. This approach adds lipid arrays to the range of HEMA polymer applications and makes this solid substrate a very attractive platform for a variety of bio-applications. PMID:28487815

  4. Hydroxyapatite/poly(epsilon-caprolactone) composite coatings on hydroxyapatite porous bone scaffold for drug delivery.

    PubMed

    Kim, Hae-Won; Knowles, Jonathan C; Kim, Hyoun-Ee

    2004-01-01

    Hydroxyapatite (HA) porous scaffold was coated with HA and polycaprolactone (PCL) composites, and antibiotic drug tetracycline hydrochloride was entrapped within the coating layer. The HA scaffold obtained by a polymeric reticulate method, possessed high porosity ( approximately 87%) and controlled pore size (150-200 microm). Such a well-developed porous structure facilitated usage in a drug delivery system due to its high surface area and blood circulation efficiency. The PCL polymer, as a coating component, was used to improve the brittleness and low strength of the HA scaffold, as well to effectively entrap the drug. To improve the osteoconductivity and bioactivity of the coating layer, HA powder was hybridized with PCL solution to make the HA-PCL composite coating. With alteration in the coating concentration and HA/PCL ratio, the morphology, mechanical properties, and biodegradation behavior were investigated. Increasing the concentration rendered the stems thicker and some pores to be clogged; as well increasing the HA/PCL ratio made the coating surface be rough due to the large amount of HA particles. However, for all concentrations and compositions, uniform coatings were formed, i.e., with the HA particles being dispersed homogeneously in the PCL sheet. With the composite coating, the mechanical properties, such as compressive strength and elastic modulus were improved by several orders of magnitude. These improvements were more significant with thicker coatings, while little difference was observed with the HA/PCL ratio. The in vitro biodegradation of the composite coatings in the phosphate buffered saline solution increased linearly with incubation time and the rate differed with the coating concentration and the HA/PCL ratio; the higher concentration and HA amount caused the increased biodegradation. At short period (<2 h), about 20-30% drug was released especially due to free drug at the coating surface. However, the release rate was sustained for

  5. Porous polymers: enabling solutions for energy applications.

    PubMed

    Thomas, Arne; Kuhn, Pierre; Weber, Jens; Titirici, Maria-Magdalena; Antonietti, Markus

    2009-02-18

    A new generation of porous polymers was made for various energy-related applications, e.g., as fuel cell membranes, as electrode materials for batteries, for gas storage, partly from renewable resources. This review intends to catch this emerging field by reporting on a variety of different approaches to make high performing polymers porous. This includes template techniques, polymers with inherent microporosity, polymer frameworks by ionothermal polymerization, and the polymerization of carbon from appropriate precursors and by hydrothermal polymerization. In this process, we try to not only identify the current status of the field, but also point to open question and tasks to identify the potentially relevant progress. Copyright © 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Polymer as Permeability Modifier in Porous Media

    NASA Astrophysics Data System (ADS)

    Parsa, S.; Weitz, D.

    2017-12-01

    Polymer flow through porous media is of particular interest in applications such as enhanced oil recovery and ground water remediation. We measure the effects of polymer flow on the permeability and local velocity distribution of a single phase flow in 3D micromodel of porous media using confocal microscopy and bulk permeability measurement. Our measurements show considerable reduction in permeability and increased velocity fluctuations with fluid velocities being diverted in some pores after polymer flow. We also find that the average velocity in the medium at constant imposed flow rate scales with the inverse square root of permeability.

  7. Process to produce lithium-polymer batteries

    DOEpatents

    MacFadden, K.O.

    1998-06-30

    A polymer bonded sheet product is described suitable for use as an electrode in a non-aqueous battery system. A porous electrode sheet is impregnated with a solid polymer electrolyte, so as to diffuse into the pores of the electrode. The composite is allowed to cool, and the electrolyte is entrapped in the porous electrode. The sheet products composed have the solid polymer electrolyte composition diffused into the active electrode material by melt-application of the solid polymer electrolyte composition into the porous electrode material sheet. The solid polymer electrolyte is maintained at a temperature that allows for rapid diffusion into the pores of the electrode. The composite electrolyte-electrode sheets are formed on current collectors and can be coated with solid polymer electrolyte prior to battery assembly. The interface between the solid polymer electrolyte composite electrodes and the solid polymer electrolyte coating has low resistance. 1 fig.

  8. Process to produce lithium-polymer batteries

    DOEpatents

    MacFadden, Kenneth Orville

    1998-01-01

    A polymer bonded sheet product suitable for use as an electrode in a non-aqueous battery system. A porous electrode sheet is impregnated with a solid polymer electrolyte, so as to diffuse into the pores of the electrode. The composite is allowed to cool, and the electrolyte is entrapped in the porous electrode. The sheet products composed have the solid polymer electrolyte composition diffused into the active electrode material by melt-application of the solid polymer electrolyte composition into the porous electrode material sheet. The solid polymer electrolyte is maintained at a temperature that allows for rapid diffusion into the pores of the electrode. The composite electrolyte-electrode sheets are formed on current collectors and can be coated with solid polymer electrolyte prior to battery assembly. The interface between the solid polymer electrolyte composite electrodes and the solid polymer electrolyte coating has low resistance.

  9. Fabrication of Porous Ag/TiO2/Au Coatings with Excellent Multipactor Suppression

    PubMed Central

    Wu, Duoduo; Ma, Jianzhong; Bao, Yan; Cui, Wanzhao; Hu, Tiancun; Yang, Jing; Bai, Yuanrui

    2017-01-01

    Porous Ag/TiO2/Au coatings with excellent multipactor suppression were prepared by fabrication of porous Ag surface through two-step wet chemical etching, synthesis of TiO2 coatings by electroless-plating-like solution deposition and deposition of Au coatings via electroless plating. Porous structure of Ag surface, TiO2 coatings on porous Ag surface and Au coatings on porous Ag/TiO2 surface were verified by field-emission scanning electron microscopy, the composition and crystal type of TiO2 coatings was characterized by X-ray photoelectron spectroscopy and X-ray diffraction. Secondary electron yield (SEY) measurement was used to monitor the SEY coefficient of the porous Ag coatings and Ag/TiO2/Au coatings. The as-obtained porous Ag coatings were proved exhibiting low SEY below 1.2, and the process was highly reproducible. In addition, the porous Ag/TiO2/Au coatings showed excellent multipactor suppression with the SEY 1.23 and good environmental stability. It is worth mentioning that the whole preparation process is simple and feasible, which would provide a promising application in RF devices. PMID:28281546

  10. Enhanced transport of biodegradable polymer-coated nanoiron particles in sand columns

    NASA Astrophysics Data System (ADS)

    Jung, B.; O'Carroll, D.; Sleep, B.

    2009-05-01

    The use of nanoscale zerovalent iron has shown promise as a technology for remediation of subsurface contamination by chlorinated solvents. However, the delivery of nanoiron particles to target contaminated subsurface zones is hindered by the aggregation of particles due to magnetic attraction. To overcome the limitations of aggregation and increase nanoiron mobility in porous media, nanoiron particles have been coated with various polymers. Polymer adsorption onto nanoiron particles provides electrosteric stabilization, increases the mobility, and decreases the attachment onto the soil surface. Various polymers were investigated in this study, including carboxylmethyl cellulose (CMC) and guar gum, both of which are biodegradable. In sand column experiments the transport of nanoiron particles was investigated as a function of type of electrolyte, ionic strength, flow velocity, and nanoiron particle concentration. Settling curves showed the enhanced stability of polymer-coated nanoiron particles compared to bare commercial nanoiron particles (bare RNIP-10DS). A newly developed nanoparticle transport numerical model was used to quantify the attachment efficiency, as well as investigate dominant nanoparticle transport and removal mechanisms. Finally the particle-collector interaction energy was predicted using DLVO (Derjaguin-Landau-Verwey-Overbeek) theory.

  11. The flow around circular cylinders partially coated with porous media

    NASA Astrophysics Data System (ADS)

    Ruck, Bodo; Klausmann, Katharina; Wacker, Tobias

    2012-05-01

    There are indications that the flow resistance of bodies can be reduced by a porous coating or porous sheath. A few numerical investigations exists in this field, however, experimental evidence is lacking. In order to investigate this phenomenon, the drag resistance of cylinders with porous coating has been investigated qualitatively and quantitatively in wind tunnel experiments. The Reynolds number was systematically varied in the range from 104 to 1.3*105. The results show that the boundary layer over the porous surface is turbulent right from the beginning and thickens faster because of the possible vertical momentum exchange at the interface. The region of flow detachment is widened resulting in a broader area with almost vanishing low flow velocities. All in all, the measurements show that a full porous coating of the cylinders increase the flow resistance. However, the measurements show that a partial coating only on the leeward side can decrease the flow resistance of the body. This effect seems due to the fact that the recirculating velocity and the underpressure in the wake is reduced significantly through a leeward porous coating. Thus, combining a smooth non-permeable windward side with a porous-coated leeward side can lead to a reduction of the body's flow resistance. These findings can be applied advantageously in many technical areas, such as energy saving of moving bodies (cars/trains/planes) or in reducing fluid loads on submersed bodies.

  12. Electrocatalysts using porous polymers and method of preparation

    DOEpatents

    Liu, Di-Jia; Yuan, Shengwen; Goenaga, Gabriel A.

    2016-08-02

    A method of producing an electrocatalyst article using porous polymers. The method creates a porous polymer designed to receive transition metal groups disposed at ligation sites and activating the transition metals to form an electrocatalyst which can be used in a fuel cell. Electrocatalysts prepared by this method are also provided. A fuel cell which includes the electrocatalyst is also provided.

  13. Electrocatalysts using porous polymers and method of preparation

    DOEpatents

    Liu, Di-Jia; Yuan, Shengwen; Goenaga, Gabriel A.

    2015-04-21

    A method of producing an electrocatalyst article using porous polymers. The method creates a porous polymer designed to receive transition metal groups disposed at ligation sites and activating the transition metals to form an electrocatalyst which can be used in a fuel cell. Electrocatalysts prepared by this method are also provided. A fuel cell which includes the electrocatalyst is also provided.

  14. Spray forming polymer membranes, coatings and films

    DOEpatents

    McHugh, Kevin M.; Watson, Lloyd D.; McAtee, Richard E.; Ploger, Scott A.

    1993-01-01

    A method of forming a polymer film having controlled physical and chemical characteristics, wherein a plume of nebulized droplets of a polymer or polymer precursor is directed toward a substrate from a converging/diverging nozzle having a throat at which the polymer or a precursor thereof is introduced and an exit from which the nebulized droplets of the polymer or precursor thereof leave entrained in a carrier gas. Relative movement between the nozzle and the substrate is provided to form a polymer film. Physical and chemical characteristics can be controlled by varying the deposition parameters and the gas and liquid chemistries. Semipermeable membranes of polyphosphazene films are disclosed, as are a variety of other polymer systems, both porous and non-porous.

  15. Spray forming polymer membranes, coatings and films

    DOEpatents

    McHugh, K.M.; Watson, L.D.; McAtee, R.E.; Ploger, S.A.

    1993-10-12

    A method is described for forming a polymer film having controlled physical and chemical characteristics, wherein a plume of nebulized droplets of a polymer or polymer precursor is directed toward a substrate from a converging/diverging nozzle having a throat at which the polymer or a precursor thereof is introduced and an exit from which the nebulized droplets of the polymer or precursor thereof leave entrained in a carrier gas. Relative movement between the nozzle and the substrate is provided to form a polymer film. Physical and chemical characteristics can be controlled by varying the deposition parameters and the gas and liquid chemistries. Semipermeable membranes of polyphosphazene films are disclosed, as are a variety of other polymer systems, both porous and non-porous. 4 figures.

  16. Influence of biodegradable polymer coatings on corrosion, cytocompatibility and cell functionality of Mg-2.0Zn-0.98Mn magnesium alloy.

    PubMed

    Witecka, Agnieszka; Yamamoto, Akiko; Idaszek, Joanna; Chlanda, Adrian; Święszkowski, Wojciech

    2016-08-01

    Four kinds of biodegradable polymers were employed to prepare bioresorbable coatings on Mg-2.0Zn-0.98Mn (ZM21) alloy to understand the relationship between polymer characteristics, protective effects on substrate corrosion, cytocompatibility and cell functionality. Poly-l-lactide (PLLA), poly(3-hydroxybutyrate) (PHB), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) or poly(lactic-co-glycolic) acid (PLGA) was spin-coated on ZM21, obtaining a smooth, non-porous coating less than 0.5μm in thickness. Polymer coating characterization, a degradation study, and biocompatibility evaluations were performed. After 4 w of immersion into cell culture medium, degradation of PLGA and PLLA coatings were confirmed by ATR-FTIR observation. The coatings of PLLA, PHB and PHBV, which have lower water permeability and slower degradation than PLGA, provide better suppression of initial ZM21 degradation and faster promotion of human osteosarcoma cell growth and differentiation. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. The Evaluation of Hydroxyapatite (HA) Coated and Uncoated Porous Tantalum for Biomedical Material Applications

    NASA Astrophysics Data System (ADS)

    Safuan, Nadia; Sukmana, Irza; Kadir, Mohammed Rafiq Abdul; Noviana, Deni

    2014-04-01

    Porous tantalum has been used as an orthopedic implant for bone defects as it has a good corrosion resistance and fatigue behaviour properties. However, there are some reports on the rejection of porous Ta after the implantation. Those clinical cases refer to the less bioactivity of metallic-based materials. This study aims to evaluate hydroxyapatite coated and uncoated porous Tantalum in order to improve the biocompatibility of porous tantalum implant and osseointegration. Porous tantalum was used as metallic-base substrate and hydroxyapatite coating has been done using plasma-spraying technique. Scanning Electron Microscopy (SEM) and Field Emission Scanning Electron Microscopy (FESEM) techniques were utilizes to investigate the coating characteristics while Confocal Raman Microscopy to investigate the interface and image. The effect of coating to the corrosion behaviour was assessed by employing potentiodynamic polarization tests in simulated body fluid at 37±1 °C. Based on SEM and FESEM results, the morphologies as well the weight element consists in the uncoated and hydroxyapatite coated porous tantalum were revealed. The results indicated that the decrease in corrosion current density for HA coated porous Ta compared to the uncoated porous Ta. This study concluded that by coating porous tantalum with HA supports to decrease the corrosion rate of pure porous.

  18. 21 CFR 888.3358 - Hip joint metal/polymer/metal semi-constrained porous-coated uncemented prosthesis.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... substrates, beads of the same alloy, and in the case of Ti-6Al-4V substrates, fibers of commercially pure titanium or Ti-6Al-4V alloy. The porous coating has a volume porosity between 30 and 70 percent, an average... titanium-aluminum-vanadium (Ti-6Al-4V) alloy and an acetabular component composed of an ultra-high...

  19. 21 CFR 888.3358 - Hip joint metal/polymer/metal semi-constrained porous-coated uncemented prosthesis.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... substrates, beads of the same alloy, and in the case of Ti-6Al-4V substrates, fibers of commercially pure titanium or Ti-6Al-4V alloy. The porous coating has a volume porosity between 30 and 70 percent, an average... titanium-aluminum-vanadium (Ti-6Al-4V) alloy and an acetabular component composed of an ultra-high...

  20. 21 CFR 888.3358 - Hip joint metal/polymer/metal semi-constrained porous-coated uncemented prosthesis.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... substrates, beads of the same alloy, and in the case of Ti-6Al-4V substrates, fibers of commercially pure titanium or Ti-6Al-4V alloy. The porous coating has a volume porosity between 30 and 70 percent, an average... titanium-aluminum-vanadium (Ti-6Al-4V) alloy and an acetabular component composed of an ultra-high...

  1. 21 CFR 888.3358 - Hip joint metal/polymer/metal semi-constrained porous-coated uncemented prosthesis.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... substrates, beads of the same alloy, and in the case of Ti-6Al-4V substrates, fibers of commercially pure titanium or Ti-6Al-4V alloy. The porous coating has a volume porosity between 30 and 70 percent, an average... titanium-aluminum-vanadium (Ti-6Al-4V) alloy and an acetabular component composed of an ultra-high...

  2. A novel and facile strategy for highly flame retardant polymer foam composite materials: Transforming silicone resin coating into silica self-extinguishing layer.

    PubMed

    Wu, Qian; Zhang, Qian; Zhao, Li; Li, Shi-Neng; Wu, Lian-Bin; Jiang, Jian-Xiong; Tang, Long-Cheng

    2017-08-15

    In this study, a novel strategy was developed to fabricate highly flame retardant polymer foam composite materials coated by synthesized silicone resin (SiR) polymer via a facile dip-coating processing. Applying the SiR polymer coating, the mechanical property and thermal stability of SiR-coated polymer foam (PSiR) composites are greatly enhanced without significantly altering their structure and morphology. The minimum oxygen concentration to support the combustion of foam materials is greatly increased, i.e. from LOI 14.6% for pure foam to LOI 26-29% for the PSiR composites studied. Especially, adjusting pendant group to SiOSi group ratio (R/Si ratio) of SiRs produces highly flame retardant PSiR composites with low smoke toxicity. Cone calorimetry results demonstrate that 44-68% reduction in the peak heat release rate for the PSiR composites containing different R/Si ratios over pure foam is achieved by the presence of appropriate SiR coating. Digital and SEM images of post-burn chars indicate that the SiR polymer coating can be transformed into silica self-extinguishing porous layer as effective inorganic barrier effect, thus preserving the polymer foam structure from fire. Our results show that the SiR dip-coating technique is a promising strategy for producing flame retardant polymer foam composite materials with improved mechanical properties. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Characteristics of hydroxyapatite coated titanium porous coatings on Ti-6Al-4V substrates by plasma sprayed method.

    PubMed

    Yang, C Y; Chen, C R; Chang, E; Lee, T M

    2007-08-01

    A porous metal coating applied to solid substrate implants has been shown, in vivo, to anchor implants by bone ingrowth. Calcium phosphate ceramics, in particular hydroxyapatite [Ca(10)(PO(4))(6)(OH)(2), HA], are bioactive ceramics, which are known to be biocompatible and osteoconductive, and these ceramics deposited on to porous-coated devices may enhance bone ingrowth and implant fixation. In this study, bi-feedstock of the titanium powder and composite (Na(2)CO(3)/HA) powder were simultaneously deposited on a Ti-6Al-4V substrate by a plasma sprayed method. At high temperature of plasma torch, the solid state of Na(2)CO(3) would decompose to release CO(2) gas and then eject the molten Ti powder to induce the interconnected pores in the coatings. After cleaning and soaking in deionized water, the residual Na(2)CO(3) in the coating would dissolve to form the open pores, and the HA would exist at the surface of pores in the inner coatings. By varying the particle size of the composite powder, the porosity of porous coating could be varied from 25.0 to 34.0%, and the average pore size of the porous coating could be varied to range between 158.5 and 202.0 microm. Using a standard adhesive test (ASTM C-633), the bonding strength of the coating is between 27.3 and 38.2 MPa. By SEM, the HA was observed at the surface of inner pore in the porous coating. These results suggest that the method exhibits the potential to manufacture the bioactive ceramics on to porous-coated specimen to achieve bone ingrowth fixation for biomedical applications.

  4. Interpenetrating phase ceramic/polymer composite coatings: Fabrication and characterization

    NASA Astrophysics Data System (ADS)

    Craig, Bradley Dene

    The goals of this thesis research were to fabricate interpenetrating phase composite (IPC) ceramic/polymer coatings and to investigate the effect of the interconnected microstructure on the physical and wear properties of the coatings. IPC coatings with an interpenetrating phase microstructure were successfully fabricated by first forming a porous ceramic with an interconnected microstructure using a chemical bonding route (mainly reacting alpha-alumina (0.3 mum) with orthophosphoric acid to form a phosphate bond). Porosity within these ceramic coatings was easily controlled between 20 and 50 vol. % by phosphoric acid addition, and was measured by a new porosity measurement technique (thermogravimetric volatilization of liquids, or TVL) which was developed. The resulting ceramic preforms were infiltrated with a UV and thermally curable cycloaliphatic epoxide resin and cured. This fabrication route resulted in composite coatings with thicknesses ranging from ˜1mum to 100 mum with complete filling of open pore space. The physical properties of the composite coatings, including microhardness, flexural modulus and wear resistance, were evaluated as a function of processing variables, including orthophosphoric acid content and ceramic phase firing temperature, which affected the microstructure and interparticulate bonding between particles in the coatings. For example, microhardness increased from ˜30 on the Vicker's scale to well over 200 as interparticulate bonding was increased in the ceramic phase. Additionally, Taber wear resistance in the best TPC coatings was found to approach that of fully-densified alumina under certain conditions. Several factors were found to influence the wear mechanism in the IPC coating materials. Forming strong connections between ceramic particles led to up to an order of magnitude increase in the wear resistance. Additionally, coating microhardness and ceramic/polymer interfacial strength were studied and found to be important in

  5. Thermal Spraying of Bioactive Polymer Coatings for Orthopaedic Applications

    NASA Astrophysics Data System (ADS)

    Chebbi, A.; Stokes, J.

    2012-06-01

    Flame sprayed biocompatible polymer coatings, made of biodegradable and non-biodegradable polymers, were investigated as single coatings on titanium and as top coatings on plasma sprayed Hydroxyapatite. Biocompatible polymers can act as drug carriers for localized drug release following implantation. The polymer matrix consisted of a biodegradable polymer, polyhydroxybutyrate 98%/ polyhydroxyvalerate 2% (PHBV) and a non-biodegradable polymer, polymethylmethacrylate (PMMA). Screening tests were performed to determine the suitable range of spraying parameters, followed by a Design of Experiments study to determine the effects of spraying parameters on coating characteristics (thickness, roughness, adhesion, wettability), and to optimize the coating properties accordingly. Coatings characterization showed that optimized flame sprayed biocompatible polymers underwent little chemical degradation, did not produce acidic by-products in vitro, and that cells proliferated well on their surface.

  6. Thin film-coated polymer webs

    DOEpatents

    Wenz, Robert P.; Weber, Michael F.; Arudi, Ravindra L.

    1992-02-04

    The present invention relates to thin film-coated polymer webs, and more particularly to thin film electronic devices supported upon a polymer web, wherein the polymer web is treated with a purifying amount of electron beam radiation.

  7. Porous polymer networks and ion-exchange media and metal-polymer composites made therefrom

    DOEpatents

    Kanatzidis, Mercouri G; Katsoulidis, Alexandros

    2015-03-10

    Porous polymeric networks and composite materials comprising metal nanoparticles distributed in the polymeric networks are provided. Also provided are methods for using the polymeric networks and the composite materials in liquid- and vapor-phase waste remediation applications. The porous polymeric networks, are highly porous, three-dimensional structures characterized by high surface areas. The polymeric networks comprise polymers polymerized from aldehydes and phenolic molecules.

  8. Porous polymer networks and ion-exchange media and metal-polymer composites made therefrom

    DOEpatents

    Kanatzidis, Mercouri G.; Katsoulidis, Alexandros

    2016-10-18

    Porous polymeric networks and composite materials comprising metal nanoparticles distributed in the polymeric networks are provided. Also provided are methods for using the polymeric networks and the composite materials in liquid- and vapor-phase waste remediation applications. The porous polymeric networks, are highly porous, three-dimensional structures characterized by high surface areas. The polymeric networks comprise polymers polymerized from aldehydes and phenolic molecules.

  9. Durable polymer-aerogel based superhydrophobic coatings, a composite material

    DOEpatents

    Kissel, David J; Brinker, Charles Jeffrey

    2014-03-04

    Provided are polymer-aerogel composite coatings, devices and articles including polymer-aerogel composite coatings, and methods for preparing the polymer-aerogel composite. The exemplary article can include a surface, wherein the surface includes at least one region and a polymer-aerogel composite coating disposed over the at least one region, wherein the polymer-aerogel composite coating has a water contact angle of at least about 140.degree. and a contact angle hysteresis of less than about 1.degree.. The polymer-aerogel composite coating can include a polymer and an ultra high water content catalyzed polysilicate aerogel, the polysilicate aerogel including a three dimensional network of silica particles having surface functional groups derivatized with a silylating agent and a plurality of pores.

  10. Durable polymer-aerogel based superhydrophobic coatings: a composite material

    DOEpatents

    Kissel, David J.; Brinker, Charles Jeffrey

    2016-02-02

    Provided are polymer-aerogel composite coatings, devices and articles including polymer-aerogel composite coatings, and methods for preparing the polymer-aerogel composite. The exemplary article can include a surface, wherein the surface includes at least one region and a polymer-aerogel composite coating disposed over the at least one region, wherein the polymer-aerogel composite coating has a water contact angle of at least about 140.degree. and a contact angle hysteresis of less than about 1.degree.. The polymer-aerogel composite coating can include a polymer and an ultra high water content catalyzed polysilicate aerogel, the polysilicate aerogel including a three dimensional network of silica particles having surface functional groups derivatized with a silylating agent and a plurality of pores.

  11. Antithrombogenic Polymer Coating.

    DOEpatents

    Huang, Zhi Heng; McDonald, William F.; Wright, Stacy C.; Taylor, Andrew C.

    2003-01-21

    An article having a non-thrombogenic surface and a process for making the article are disclosed. The article is formed by (i) coating a polymeric substrate with a crosslinked chemical combination of a polymer having at least two amino substituted side chains, a crosslinking agent containing at least two crosslinking functional groups which react with amino groups on the polymer, and a linking agent containing a first functional group which reacts with a third functional group of the crosslinking agent, and (ii) contacting the coating on the substrate with an antithrombogenic agent which covalently bonds to a second functional group of the linking agent. In one example embodiment, the polymer is a polyamide having amino substituted alkyl chains on one side of the polyamide backbone, the crosslinking agent is a phosphine having the general formula (A).sub.3 P wherein A is hydroxyalkyl, the linking agent is a polyhydrazide and the antithrombogenic agent is heparin.

  12. Does hydroxyapatite coating have no advantage over porous coating in primary total hip arthroplasty? A meta-analysis.

    PubMed

    Chen, Yun-Lin; Lin, Tiao; Liu, An; Shi, Ming-Min; Hu, Bin; Shi, Zhong-Li; Yan, Shi-Gui

    2015-01-28

    There are some arguments between the use of hydroxyapatite and porous coating. Some studies have shown that there is no difference between these two coatings in total hip arthroplasty (THA), while several other studies have shown that hydroxyapatite has advantages over the porous one. We have collected the studies in Pubmed, MEDLINE, EMBASE, and the Cochrane library from the earliest possible years to present, with the search strategy of "(HA OR hydroxyapatite) AND ((total hip arthroplasty) OR (total hip replacement)) AND (RCT* OR randomiz* OR control* OR compar* OR trial*)". The randomized controlled trials and comparative observation trials that evaluated the clinical and radiographic effects between hydroxyapatite coating and porous coating were included. Our main outcome measurements were Harris hip score (HHS) and survival, while the secondary outcome measurements were osteolysis, radiolucent lines, and polyethylene wear. Twelve RCTs and 9 comparative observation trials were included. Hydroxyapatite coating could improve the HHS (p < 0.01), reduce the incidence of thigh pain (p = 0.01), and reduce the incidence of femoral osteolysis (p = 0.01), but hydroxyapatite coating had no advantages on survival (p = 0.32), polyethylene wear (p = 0.08), and radiolucent lines (p = 0.78). Hydroxyapatite coating has shown to have an advantage over porous coating. The HHS and survival was duration-dependent-if given the sufficient duration of follow-up, hydroxyapatite coating would be better than porous coating for the survival. The properties of hydroxyapatite and the implant design had influence on thigh pain incidence, femoral osteolysis, and polyethylene wear. Thickness of 50 to 80 μm and purity larger than 90% increased the thigh pain incidence. Anatomic design had less polyethylene wear.

  13. Flexural behavior of reinforced concrete beam with polymer coated pumice

    NASA Astrophysics Data System (ADS)

    Nainggolan, Christin Remayanti; Wijatmiko, Indradi; Wibowo, Ari

    2017-09-01

    Sustainable development has become an important issue due to the increasing consideration of preserving the nature. Many alternative for coarse aggregate replacement have been investigated ranging from natural and fabricated aggregates. In this study, natural aggregate pumice was investigated since it offers lower density that give paramount benefit in reducing total building weight and hence reducing the earthquake excitation effect and optimizing the structural dimension. However, the characteristic of porous surfaces of pumice causes excessive water absorption during concrete mixing process. Therefore, to reduce the additional water, the pumice aggregates were coated with polymer. The tested specimens consisted of normal concrete beams (NCB), uncoated pumice aggregate concrete beam (UPA) and polymer coated pumice aggregate concrete beam (PCP). The objective of the research was to obtain the effect of coating on the pumice aggregate to the flexural behavior of concrete beams. The lateral load-displacement behavior, ductility and collapse mechanism were studied. The results showed that there were only marginal drop on the load-carrying capacity of the pumice aggregate beam compared to those of normal beam. Additionally, the ductility coefficient of specimens UPA and PCP decreased of 11,97% and 14,03% respectively compared to NCB, and the ultimate load capacity decreased less than 1%. Overall, the pumice aggregate showed good characteristic for replacing normal coarse aggregate.

  14. Corrosion-protective coatings from electrically conducting polymers

    NASA Technical Reports Server (NTRS)

    Thompson, Karen Gebert; Bryan, Coleman J.; Benicewicz, Brian C.; Wrobleski, Debra A.

    1991-01-01

    In a joint effort between NASA Kennedy and LANL, electrically conductive polymer coatings were developed as corrosion protective coatings for metal surfaces. At NASA Kennedy, the launch environment consist of marine, severe solar, and intermittent high acid and/or elevated temperature conditions. Electrically conductive polymer coatings were developed which impart corrosion resistance to mild steel when exposed to saline and acidic environments. Such coatings also seem to promote corrosion resistance in areas of mild steel where scratches exist in the protective coating. Such coatings appear promising for many commercial applications.

  15. Dialysis on microchips using thin porous polymer membranes

    DOEpatents

    Singh, Anup K.; Kirby, Brian J.; Shepodd, Timothy J.

    2007-09-04

    Laser-induced phase-separation polymerization of a porous acrylate polymer is used for in-situ fabrication of dialysis membranes inside glass microchannels. A shaped 355 nm laser beam is used to produce a porous polymer membrane with a thickness of about 15 .mu.m, which bonds to the glass microchannel and form a semi-permeable membrane. Differential permeation through a membrane formed with pentaerythritol triacrylate was observed and quantified by comparing the response of the membrane to fluorescein and fluorescently tagging 200 nm latex microspheres. Differential permeation was observed and quantified by comparing the response to rhodamine 560 and lactalbumin protein in a membrane formed with SPE-methylene bisacrylamide. The porous membranes illustrate the capability for the present technique to integrate sample cleanup into chip-based analysis systems.

  16. 21 CFR 888.3670 - Shoulder joint metal/polymer/metal nonconstrained or semi-constrained porous-coated uncemented...

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... as cobalt-chromium-molybdenum (Co-Cr-Mo) and titanium-aluminum-vanadium (Ti-6Al-4V) alloys, and a... Ti-6Al-4V components, beads or fibers of commercially pure titanium or Ti-6Al-4V alloy, or... and Ti-6Al-4V. The humeral component and glenoid backing have a porous coating made of, in the case of...

  17. 21 CFR 888.3670 - Shoulder joint metal/polymer/metal nonconstrained or semi-constrained porous-coated uncemented...

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... as cobalt-chromium-molybdenum (Co-Cr-Mo) and titanium-aluminum-vanadium (Ti-6Al-4V) alloys, and a... Ti-6Al-4V components, beads or fibers of commercially pure titanium or Ti-6Al-4V alloy, or... and Ti-6Al-4V. The humeral component and glenoid backing have a porous coating made of, in the case of...

  18. 21 CFR 888.3670 - Shoulder joint metal/polymer/metal nonconstrained or semi-constrained porous-coated uncemented...

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... as cobalt-chromium-molybdenum (Co-Cr-Mo) and titanium-aluminum-vanadium (Ti-6Al-4V) alloys, and a... Ti-6Al-4V components, beads or fibers of commercially pure titanium or Ti-6Al-4V alloy, or... and Ti-6Al-4V. The humeral component and glenoid backing have a porous coating made of, in the case of...

  19. 21 CFR 888.3670 - Shoulder joint metal/polymer/metal nonconstrained or semi-constrained porous-coated uncemented...

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... as cobalt-chromium-molybdenum (Co-Cr-Mo) and titanium-aluminum-vanadium (Ti-6Al-4V) alloys, and a... Ti-6Al-4V components, beads or fibers of commercially pure titanium or Ti-6Al-4V alloy, or... and Ti-6Al-4V. The humeral component and glenoid backing have a porous coating made of, in the case of...

  20. Poly-ε-caprolactone Coated and Functionalized Porous Titanium and Magnesium Implants for Enhancing Angiogenesis in Critically Sized Bone Defects

    PubMed Central

    Roland, Laura; Grau, Michael; Matena, Julia; Teske, Michael; Gieseke, Matthias; Kampmann, Andreas; Beyerbach, Martin; Murua Escobar, Hugo; Haferkamp, Heinz; Gellrich, Nils-Claudius; Nolte, Ingo

    2015-01-01

    For healing of critically sized bone defects, biocompatible and angiogenesis supporting implants are favorable. Murine osteoblasts showed equal proliferation behavior on the polymers poly-ε-caprolactone (PCL) and poly-(3-hydroxybutyrate)/poly-(4-hydroxybutyrate) (P(3HB)/P(4HB)). As vitality was significantly better for PCL, it was chosen as a suitable coating material for further experiments. Titanium implants with 600 µm pore size were evaluated and found to be a good implant material for bone, as primary osteoblasts showed a vitality and proliferation onto the implants comparable to well bottom (WB). Pure porous titanium implants and PCL coated porous titanium implants were compared using Live Cell Imaging (LCI) with Green fluorescent protein (GFP)-osteoblasts. Cell count and cell covered area did not differ between the implants after seven days. To improve ingrowth of blood vessels into porous implants, proangiogenic factors like Vascular Endothelial Growth Factor (VEGF) and High Mobility Group Box 1 (HMGB1) were incorporated into PCL coated, porous titanium and magnesium implants. An angiogenesis assay was performed to establish an in vitro method for evaluating the impact of metallic implants on angiogenesis to reduce and refine animal experiments in future. Incorporated concentrations of proangiogenic factors were probably too low, as they did not lead to any effect. Magnesium implants did not yield evaluable results, as they led to pH increase and subsequent cell death. PMID:26703586

  1. Poly-ε-caprolactone Coated and Functionalized Porous Titanium and Magnesium Implants for Enhancing Angiogenesis in Critically Sized Bone Defects.

    PubMed

    Roland, Laura; Grau, Michael; Matena, Julia; Teske, Michael; Gieseke, Matthias; Kampmann, Andreas; Beyerbach, Martin; Murua Escobar, Hugo; Haferkamp, Heinz; Gellrich, Nils-Claudius; Nolte, Ingo

    2015-12-22

    For healing of critically sized bone defects, biocompatible and angiogenesis supporting implants are favorable. Murine osteoblasts showed equal proliferation behavior on the polymers poly-ε-caprolactone (PCL) and poly-(3-hydroxybutyrate)/poly-(4-hydroxybutyrate) (P(3HB)/P(4HB)). As vitality was significantly better for PCL, it was chosen as a suitable coating material for further experiments. Titanium implants with 600 µm pore size were evaluated and found to be a good implant material for bone, as primary osteoblasts showed a vitality and proliferation onto the implants comparable to well bottom (WB). Pure porous titanium implants and PCL coated porous titanium implants were compared using Live Cell Imaging (LCI) with Green fluorescent protein (GFP)-osteoblasts. Cell count and cell covered area did not differ between the implants after seven days. To improve ingrowth of blood vessels into porous implants, proangiogenic factors like Vascular Endothelial Growth Factor (VEGF) and High Mobility Group Box 1 (HMGB1) were incorporated into PCL coated, porous titanium and magnesium implants. An angiogenesis assay was performed to establish an in vitro method for evaluating the impact of metallic implants on angiogenesis to reduce and refine animal experiments in future. Incorporated concentrations of proangiogenic factors were probably too low, as they did not lead to any effect. Magnesium implants did not yield evaluable results, as they led to pH increase and subsequent cell death.

  2. Polymer brush coatings for DNA: fundamental polymer physics and nanofabrication applications

    NASA Astrophysics Data System (ADS)

    de Vries, Renko

    Recombinant DNA technology allows for the production of precisely defined self-assembling protein-based polymers. So far, the major applications for such protein-based polymers have been self-assembling hydrogels and micellar structures with biomedical application. Inspired by minimal models for the self-ssembly of rod-shaped viruses such as the tobacco mosaic virus, I have developed protein-polymers that co-assemble with DNA into rod-shaped virus-like particles, and protein-polymers that provide brush coatings around single DNA molecules. In this presentation I will focus on the latter, showing that on the one hand brush coated DNA is a rich model system for exploring the physics of bottle-brush polymers, while on the other hand brush coatings of DNA can also play an important practical role in nanofabrication. A key problem in the physics of bottle-brush polymers that I will address is the scale-dependence of bottle-brush elasticity. For long-wavelength thermal deformations probed by AFM imaging I will demonstrate that there is significant stiffening due to the brush coating, while for short wavelength thermal deformations probed by force spectroscopy, we find that stiffening due to the brush coating disappears completely. DNA brush coatings can also play an important practical role in nanofabrication by acting as a compatibilizer between chemically different building blocks. I will explore the example of DNA origami in combination with gold nanoparticles: while Mg2+ ions and high concentrations of monovalent salts are crucial for the stability of DNA origami, such solution conditions are typically incompatible with the colloidal stability of gold nanoparticles.I will show how DNA brush coatings can dramatically enhance the yield of formation of isolated DNA-gold nanoparticle composite nanostructures.

  3. Effect of bone sialoprotein coating of ceramic and synthetic polymer materials on in vitro osteogenic cell differentiation and in vivo bone formation.

    PubMed

    Schaeren, Stefan; Jaquiéry, Claude; Wolf, Francine; Papadimitropoulos, Adam; Barbero, Andrea; Schultz-Thater, Elke; Heberer, Michael; Martin, Ivan

    2010-03-15

    In this study, we addressed whether Bone Sialoprotein (BSP) coating of various substrates could enhance the in vitro osteogenic differentiation and in vivo bone formation capacity of human Bone Marrow Stromal Cells (BMSC). Moreover, we tested whether synthetic polymer-based porous scaffolds, despite the absence of a mineral component, could support ectopic bone formation by human BMSC if coated with BSP. Adsorption of recombinant human BSP on tissue culture-treated polystyrene (TCTP), beta-tricalcium phosphate (Osteologic) or synthetic polymer (Polyactive) substrates was dose dependent, but did not consistently accelerate or enhance in vitro BMSC osteogenic differentiation, as assessed by the mRNA expression of osteoblast-related genes. Similarly, BSP coating of porous beta-tricalcium phosphate scaffolds (Skelite) did not improve the efficiency of bone tissue formation following loading with BMSC and ectopic implantation in nude mice. Finally, Polyactive foams seeded with BMSC did not form bone tissue in the same ectopic assay, even if coated with BSP. We conclude that BSP coating of a variety of substrates is not directly associated with an enhancement of osteoprogenitor cell differentiation in vitro or in vivo, and that presentation of BSP on polymeric materials is not sufficient to prime BMSC functional osteoblastic differentiation in vivo. (c) 2009 Wiley Periodicals, Inc.

  4. Spray-Deposited Superconductor/Polymer Coatings

    NASA Technical Reports Server (NTRS)

    Wise, Stephanie A.; Tran, Sang Q.; Hooker, Matthew W.

    1993-01-01

    Coatings that exhibit the Meissner effect formed at relatively low temperature. High-temperature-superconductor/polymer coatings that exhibit Meissner effect deposited onto components in variety of shapes and materials. Simple, readily available equipment needed in coating process, mean coatings produced economically. Coatings used to keep magnetic fields away from electronic circuits in such cryogenic applications as magnetic resonance imaging and detection of infrared, and in magnetic suspensions to provide levitation and/or damping of vibrations.

  5. An instant multi-responsive porous polymer actuator driven by solvent molecule sorption.

    PubMed

    Zhao, Qiang; Dunlop, John W C; Qiu, Xunlin; Huang, Feihe; Zhang, Zibin; Heyda, Jan; Dzubiella, Joachim; Antonietti, Markus; Yuan, Jiayin

    2014-07-01

    Fast actuation speed, large-shape deformation and robust responsiveness are critical to synthetic soft actuators. A simultaneous optimization of all these aspects without trade-offs remains unresolved. Here we describe porous polymer actuators that bend in response to acetone vapour (24 kPa, 20 °C) at a speed of an order of magnitude faster than the state-of-the-art, coupled with a large-scale locomotion. They are meanwhile multi-responsive towards a variety of organic vapours in both the dry and wet states, thus distinctive from the traditional gel actuation systems that become inactive when dried. The actuator is easy-to-make and survives even after hydrothermal processing (200 °C, 24 h) and pressing-pressure (100 MPa) treatments. In addition, the beneficial responsiveness is transferable, being able to turn 'inert' objects into actuators through surface coating. This advanced actuator arises from the unique combination of porous morphology, gradient structure and the interaction between solvent molecules and actuator materials.

  6. Conducting polymer coated neural recording electrodes.

    PubMed

    Harris, Alexander R; Morgan, Simeon J; Chen, Jun; Kapsa, Robert M I; Wallace, Gordon G; Paolini, Antonio G

    2013-02-01

    Neural recording electrodes suffer from poor signal to noise ratio, charge density, biostability and biocompatibility. This paper investigates the ability of conducting polymer coated electrodes to record acute neural response in a systematic manner, allowing in depth comparison of electrochemical and electrophysiological response. Polypyrrole (Ppy) and poly-3,4-ethylenedioxythiophene (PEDOT) doped with sulphate (SO4) or para-toluene sulfonate (pTS) were used to coat iridium neural recording electrodes. Detailed electrochemical and electrophysiological investigations were undertaken to compare the effect of these materials on acute in vivo recording. A range of charge density and impedance responses were seen with each respectively doped conducting polymer. All coatings produced greater charge density than uncoated electrodes, while PEDOT-pTS, PEDOT-SO4 and Ppy-SO4 possessed lower impedance values at 1 kHz than uncoated electrodes. Charge density increased with PEDOT-pTS thickness and impedance at 1 kHz was reduced with deposition times up to 45 s. Stable electrochemical response after acute implantation inferred biostability of PEDOT-pTS coated electrodes while other electrode materials had variable impedance and/or charge density after implantation indicative of a protein fouling layer forming on the electrode surface. Recording of neural response to white noise bursts after implantation of conducting polymer-coated electrodes into a rat model inferior colliculus showed a general decrease in background noise and increase in signal to noise ratio and spike count with reduced impedance at 1 kHz, regardless of the specific electrode coating, compared to uncoated electrodes. A 45 s PEDOT-pTS deposition time yielded the highest signal to noise ratio and spike count. A method for comparing recording electrode materials has been demonstrated with doped conducting polymers. PEDOT-pTS showed remarkable low fouling during acute implantation, inferring good biostability

  7. Crosslinkable coatings from phosphorylcholine-based polymers.

    PubMed

    Lewis, A L; Cumming, Z L; Goreish, H H; Kirkwood, L C; Tolhurst, L A; Stratford, P W

    2001-01-01

    2-Methacryloyloxyethyl phosphorylcholine (MPC) was synthesised and then used in the preparation of crosslinked polymer membranes with lauryl methacrylate, hydroxypropyl methacrylate and trimethoxysilylpropyl methacrylate (crosslinker) comonomers. Some physical aspects of the membrane properties were evaluated in order to establish the basis for the synthesis of a series of post-crosslinkable polymers. These materials were made by copolymerisation of the constituent monomers via a free radical method, and characterised using NMR, FT-IR, viscometry and elemental analysis. The optimum crosslink density and conditions required for curing coatings of these polymers were investigated using atomic force microscopy (AFM) and showed the inclusion of 5 mol% silyl crosslinking agent to be ideal. A nanoindentation technique was employed to determine if the coating developed elasticity upon crosslinking. The biological properties of the coatings were evaluated using a variety of protein adsorption assays and blood contacting experiments, and an enzyme immunoassay was developed to detect E. coli in order to assess the level of bacterial adhesion to these biomaterials. Polymers of this type were shown to be very useful as coating materials for improving the biocompatibility of, or reducing the levels of adherent bacteria to medical devices.

  8. Influence of polymer coating morphology on microsensor response

    NASA Astrophysics Data System (ADS)

    Levit, Natalia; Pestov, Dmitry; Tepper, Gary C.

    2004-03-01

    Nanoscale polymeric coatings are used in a variety of sensor systems. The influence of polymer coating morphology on sensor response was investigated and it was determined that coating morphology plays a particularly important role in transducers based on optical or acoustic resonance such as surface acoustic wave (SAW) or surface plasmon resonance (SPR) devices. Nanoscale polymeric coatings were deposited onto a number of miniature devices using a "solvent-free" deposition technique known as Rapid Expansion of Supercritical Solutions (RESS). In RESS, the supercritical solvent goes into the vapor phase upon fast depressurization and separates from the polymer. Therefore, dry polymer particles are deposited from the gas phase. The average diameter of RESS precipitates is about two orders of magnitude smaller than the minimum droplet size achievable by the air-brush method. For rubbery polymers, such as PIB and PDMS, the nanoscale solute droplets produced by RESS agglomerate on the surface forming a highly-uniform continuous nanoscale film. For glassy and crstalline polymers, the RESS droplets produce uniform particulate coatings exhibiting high surface-to-volume ratio. The coating morphology can be changed by controlling the RESS processing conditions.

  9. Luminescent Porous Polymers Based on Aggregation-Induced Mechanism: Design, Synthesis and Functions.

    PubMed

    Dalapati, Sasanka; Gu, Cheng; Jiang, Donglin

    2016-12-01

    Enormous research efforts are focusing on the design and synthesis of advanced luminescent systems, owing to their diverse capability in scientific studies and technological developments. In particular, fluorescence systems based on aggregation-induced emission (AIE) have emerged to show great potential for sensing, bio-imaging, and optoelectronic applications. Among them, integrating AIE mechanisms to design porous polymers is unique because it enables the combination of porosity and luminescence activity in one molecular skeleton for functional design. In recent years rapid progress in exploring AIE-based porous polymers has developed a new class of luminescent materials that exhibit broad structural diversity, outstanding properties and functions and promising applications. By classifying the structural nature of the skeleton, herein the design principle, synthetic development and structural features of different porous luminescent materials are elucidated, including crystalline covalent organic frameworks (COFs), metal-organic frameworks (MOFs), and amorphous porous organic polymers (POPs). The functional exploration of these luminescent porous polymers are highlighted by emphasizing electronic interplay within the confined nanospace, fundamental issues to be addressed are disclosed, and future directions from chemistry, physics and materials science perspectives are proposed. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Surface Coatings for Gas Detection via Porous Silicon

    NASA Astrophysics Data System (ADS)

    Ozdemir, Serdar; Li, Ji-Guang; Gole, James

    2009-03-01

    Nanopore covered microporous silicon interfaces have been formed via an electrochemical etch for gas sensor applications. Rapid reversible and sensitive gas sensors have been fabricated. The fabricated porous silicon (PS) gas sensors display the advantages of operation at room temperature as well as at a single, readily accessible temperature with an insensitivity to temperature drift; operation in a heat-sunk configuration, ease of coating with gas-selective materials; low cost of fabrication and operation, and the ability to rapidly assess false positives by operating the sensor in a pulsed mode. The PS surface has been modified with unique coatings on the basis of a general theory in order to achieve maximum sensitivity and selectivity. Sensing of NH3, NOx and PH3 at or below the ppm level have been observed. A typical PS nanostructure coated microstructured hybrid configuration when coated with tin oxide (NOx, CO) and gold nanostructures (NH3) provides a greatly increased sensitivity to the indicated gases. Al2O3 coating of the porous silicon using atomic layer deposition and its effect on PH3 sensing has been investigated. 20-100 nm TiO2 nanoparticles have been produced using sol-gel methods to coat PS surfaces and the effects on the selectivity and the sensitivity have been studied.

  11. Detonation suppression in hydrogen-air mixtures using porous coatings on the walls

    NASA Astrophysics Data System (ADS)

    Bivol, G. Yu.; Golovastov, S. V.; Golub, V. V.

    2018-05-01

    We considered the problem of detonation suppression and weakening of blast wave effects occurring during the combustion of hydrogen-air mixtures in confined spaces. The gasdynamic processes during combustion of hydrogen, an alternative environmentally friendly fuel, were also considered. Detonation decay and flame propagation in hydrogen-air mixtures were experimentally investigated in rectangular cross-section channels with solid walls and two types of porous coatings: steel wool and polyurethane foam. Shock wave pressure dynamics inside the section with porous coating were studied using pressure sensors; flame front propagation was studied using photodiodes and high-speed camera visualization. For all mixtures, the detonation wave formed before entering the section with porous coating. For both porous materials, the steady detonation wave decoupled in the porous section of the channel into a shock wave and flame front propagating with a velocity around the Chapman-Jouguet acoustic velocity. By the end of the porous section, shock wave pressure reductions of 70 and 85% were achieved for the polyurethane foam and steel wool, respectively. The dependence of the flame velocity on the mixture composition (equivalence ratio) is presented.

  12. Organosiloxane-grafted natural polymer coatings

    DOEpatents

    Sugama, Toshifumi

    1998-01-01

    A new family of polysaccharide graft polymers are provided as corrosion resistant coatings having antimicrobial properties which are useful on light metals such as aluminum, magnesium, zinc, steel and their alloys. Methods of making the polysaccharide graft polymers are also included. The methods of making the polysaccharide graft polymers involve reacting a polysaccharide source with an antimicrobial agent under conditions of hydrolysis-condensation.

  13. Electrospun Fibro-porous Polyurethane Coatings for Implantable Glucose Biosensors

    PubMed Central

    Wang, Ning; Burugapalli, Krishna; Song, Wenhui; Halls, Justin; Moussy, Francis; Ray, Asim; Zheng, Yudong

    2012-01-01

    This study reports methods for coating miniature implantable glucose biosensors with electrospun polyurethane (PU) membranes, their effects on sensor function and efficacy as mass-transport limiting membranes. For electrospinning fibres directly on sensor surface, both static and dynamic collector systems, were designed and tested. Optimum collector configurations were first ascertained by FEA modelling. Both static and dynamic collectors allowed complete covering of sensors, but it was the dynamic collector that produced uniform fibro-porous PU coatings around miniature ellipsoid biosensors. The coatings had random fibre orientation and their uniform thickness increased linearly with increasing electrospinning time. The effects of coatings having an even spread of submicron fibre diameters and sub-100μm thicknesses on glucose biosensor function were investigated. Increasing thickness and fibre diameters caused a statistically insignificant decrease in sensor sensitivity for the tested electrospun coatings. The sensors’ linearity for the glucose detection range of 2 to 30mM remained unaffected. The electrospun coatings also functioned as mass-transport limiting membranes by significantly increasing the linearity, replacing traditional epoxy-PU outer coating. To conclude, electrospun coatings, having controllable fibro-porous structure and thicknesses, on miniature ellipsoid glucose biosensors were demonstrated to have minimal effect on pre-implantation sensitivity and also to have mass-transport limiting ability. PMID:23146433

  14. Conducting polymer coated neural recording electrodes

    NASA Astrophysics Data System (ADS)

    Harris, Alexander R.; Morgan, Simeon J.; Chen, Jun; Kapsa, Robert M. I.; Wallace, Gordon G.; Paolini, Antonio G.

    2013-02-01

    Objective. Neural recording electrodes suffer from poor signal to noise ratio, charge density, biostability and biocompatibility. This paper investigates the ability of conducting polymer coated electrodes to record acute neural response in a systematic manner, allowing in depth comparison of electrochemical and electrophysiological response. Approach. Polypyrrole (Ppy) and poly-3,4-ethylenedioxythiophene (PEDOT) doped with sulphate (SO4) or para-toluene sulfonate (pTS) were used to coat iridium neural recording electrodes. Detailed electrochemical and electrophysiological investigations were undertaken to compare the effect of these materials on acute in vivo recording. Main results. A range of charge density and impedance responses were seen with each respectively doped conducting polymer. All coatings produced greater charge density than uncoated electrodes, while PEDOT-pTS, PEDOT-SO4 and Ppy-SO4 possessed lower impedance values at 1 kHz than uncoated electrodes. Charge density increased with PEDOT-pTS thickness and impedance at 1 kHz was reduced with deposition times up to 45 s. Stable electrochemical response after acute implantation inferred biostability of PEDOT-pTS coated electrodes while other electrode materials had variable impedance and/or charge density after implantation indicative of a protein fouling layer forming on the electrode surface. Recording of neural response to white noise bursts after implantation of conducting polymer-coated electrodes into a rat model inferior colliculus showed a general decrease in background noise and increase in signal to noise ratio and spike count with reduced impedance at 1 kHz, regardless of the specific electrode coating, compared to uncoated electrodes. A 45 s PEDOT-pTS deposition time yielded the highest signal to noise ratio and spike count. Significance. A method for comparing recording electrode materials has been demonstrated with doped conducting polymers. PEDOT-pTS showed remarkable low fouling during

  15. Organosiloxane-grafted natural polymer coatings

    DOEpatents

    Sugama, Toshifumi

    1998-12-01

    A new family of polysaccharide graft polymers are provided as corrosion resistant coatings having antimicrobial properties which are useful on light metals such as aluminum, magnesium, zinc, steel and their alloys. Methods of making the polysaccharide graft polymers are also included. The methods of making the polysaccharide graft polymers involve reacting a polysaccharide source with an antimicrobial agent under conditions of hydrolysis-condensation. 17 figs.

  16. Nanoscale Reinforced, Polymer Derived Ceramic Matrix Coatings

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Rajendra Bordia

    The goal of this project was to explore and develop a novel class of nanoscale reinforced ceramic coatings for high temperature (600-1000 C) corrosion protection of metallic components in a coal-fired environment. It was focused on developing coatings that are easy to process and low cost. The approach was to use high-yield preceramic polymers loaded with nano-size fillers. The complex interplay of the particles in the polymer, their role in controlling shrinkage and phase evolution during thermal treatment, resulting densification and microstructural evolution, mechanical properties and effectiveness as corrosion protection coatings were investigated. Fe-and Ni-based alloys currently used in coal-firedmore » environments do not possess the requisite corrosion and oxidation resistance for next generation of advanced power systems. One example of this is the power plants that use ultra supercritical steam as the working fluid. The increase in thermal efficiency of the plant and decrease in pollutant emissions are only possible by changing the properties of steam from supercritical to ultra supercritical. However, the conditions, 650 C and 34.5 MPa, are too severe and result in higher rate of corrosion due to higher metal temperatures. Coating the metallic components with ceramics that are resistant to corrosion, oxidation and erosion, is an economical and immediate solution to this problem. Good high temperature corrosion protection ceramic coatings for metallic structures must have a set of properties that are difficult to achieve using established processing techniques. The required properties include ease of coating complex shapes, low processing temperatures, thermal expansion match with metallic structures and good mechanical and chemical properties. Nanoscale reinforced composite coatings in which the matrix is derived from preceramic polymers have the potential to meet these requirements. The research was focused on developing suitable material systems and

  17. Grafting of functionalized polymer on porous silicon surface using Grignard reagent

    NASA Astrophysics Data System (ADS)

    Tighilt, F.-Z.; Belhousse, S.; Sam, S.; Hamdani, K.; Lasmi, K.; Chazalviel, J. N.; Gabouze, N.

    2017-11-01

    Recently, considerable attention has been paid to the manipulation and the control of the physicochemical properties of porous silicon surfaces because of their crucial importance to the modern microelectronics industry. Hybrid structures consisting of deposited polymer on porous silicon surfaces are important to applications in microelectronics, photovoltaics and sensors (Ensafi et al., 2016; Kashyout et al., 2015; Osorio et al.; 2015; Hejjo et al., 2002) [1-4]. In many cases, the polymer can provide excellent mechanical and chemical protection of the substrate, changes the electrochemical interface characteristics of the substrate, and provides new ways to the functionalization of porous silicon surfaces for molecular recognition and sensing. In this work, porous silicon surface was modified by anodic treatment in ethynylmagnesium bromide electrolyte leading to the formation of a polymeric layer bearing some bromine substituents. Subsequently, the formed polymer is functionalized with amine molecules containing functional groups (carboxylic acid or pyridine) by a substitution reaction between bromine sites and amine groups (Hofmann reaction). The chemical composition of the modified porous silicon surfaces was investigated and the grafting of polymeric chains and functional groups on the porous silicon surface was confirmed by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) which displayed the principal characteristic peaks attributed to the different functional groups. Furthermore, the surface of the material was examined by scanning electron microscopy (SEM).

  18. Functional patterned coatings by thin polymer film dewetting.

    PubMed

    Telford, Andrew M; Thickett, Stuart C; Neto, Chiara

    2017-12-01

    An approach for the fabrication of functional polymer surface coatings is introduced, where micro-scale structure and surface functionality are obtained by means of self-assembly mechanisms. We illustrate two main applications of micro-patterned polymer surfaces obtained through dewetting of bilayers of thin polymer films. By tuning the physical and chemical properties of the polymer bilayers, micro-patterned surface coatings could be produced that have applications both for the selective attachment and patterning of proteins and cells, with potential applications as biomaterials, and for the collection of water from the atmosphere. In all cases, the aim is to achieve functional coatings using approaches that are simple to realize, use low cost materials and are potentially scalable. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Cysteine could change the transport mechanism of PVP-coated silver nanoparticles in porous media

    NASA Astrophysics Data System (ADS)

    Yang, X.; Lin, S.; Wiesner, M.

    2012-12-01

    Silver nanoparticles (AgNPs) can hardly be removed by wastewater treatment plant and have big potential to enter groundwater, jeopardizing the water quality & aquatic ecosystem. Most AgNPs have surface coatings such as polyvinylpyrrolidone (PVP) which dominate their transport in porous media. Our previous study shows that PVP may promote the deposition of AgNPs on silica surface by a bridging mechanism. This study further explored how cysteine, a natural organic matter type, may influence the role of the PVP coating on AgNP translocation. Dynamic Light Scattering (DLS) measurement (Figure 1A) shows that the PVP coating rendered the AgNP dispersion high stability during the measuring period (3hrs). Addition of 100 ppm cysteine to the dispersion resulted in a rapid decrease in particle size from 100nm to 52nm within one hour, following which no further decline in particle size occurred. Column experiment results (Figure 1B) show that corresponding to the particle size change was a substantial decrease in particle deposition rates: introduction of 100 ppm cysteine into the particle dispersion resulted in a decrease in AgNP attenuation by the porous medium from 67% to 26%. The decline in particle size suggested that cysteine may have displaced the macromolecular PVP from the particle surface. Desorption of PVP resulted in a weakening or vanish of polymer bridging effect which in turn lowered the deposition rates substantially. This study demonstrated an implication of environmental transformation of coated AgNPs to their mobility in saturated sand aquifers. Acknowledgment Xinyao Yang appreciates the Natural Science Foundation of China (Grant No.:41101475) for covering the registration fee and traveling costs.igure 1 Particle size measurement (A) and breakthrough curves (B) of PVP-coated silver nanoparticle in the absence and presence of cysteine: pH=7.0, ionic strength=1mM, flow rate=1ml/min.

  20. Preparation and release characteristics of polymer-coated and blended alginate microspheres.

    PubMed

    Lee, D W; Hwang, S J; Park, J B; Park, H J

    2003-01-01

    To prevent a rapid drug release from alginate microspheres in simulated intestinal media, alginate microspheres were coated or blended with polymers. Three polymers were selected and evaluated such as HPMC, Eudragit RS 30D and chitosan, as both coating materials and additive polymers for controlling the drug release. This study focused on the release characteristics of polymer-coated and blended alginate microspheres, varying the type of polymer and its concentration. The alginate microspheres were prepared by dropping the mixture of drug and sodium alginate into CaCl(2) solution using a spray-gun. Polymer-coated microspheres were prepared by adding alginate microspheres into polymer solution with mild stirring. Polymer-blended microspheres were prepared by dropping the mixture of drug, sodium alginate and additive polymer with plasticizer into CaCl(2) solution. In vitro release test was carried out to investigate the release profiles in 500 ml of phosphate buffered saline (PBS, pH 7.4). As the amount of polymer in sodium alginate or coating solution increase, the drug release generally decreased. HPMC-blended microspheres swelled but withstood the disintegration, showing an ideal linear release profiles. Chitosan-coated microspheres showed smooth and round surface and extended the release of drug. In comparison with chitosan-coated microspheres, HPMC-blended alginate microspheres can be easily made and used for controlled drug delivery systems due to convenient process and controlled drug release.

  1. Stress and structure development in polymeric coatings

    NASA Astrophysics Data System (ADS)

    Vaessen, Diane Melissa

    2002-09-01

    The main goal of this research is to measure the stress evolution in various polymer coating systems to establish the mechanisms responsible for stress development, stress relaxation, and defect formation. Investigated systems include ultraviolet (UV)-curable coatings, dense and porous coatings from polymer solutions, and latex coatings. Coating stress was measured using a controlled environment stress apparatus based on a cantilever deflection principle. For acrylate coatings, it was found that by cycling a UV-lamp on and off, keeping the total dose constant, coating stress was lowered by 60% by decreasing the cycle period. A stress minimum was also found to exist for a given dose of radiation. The lower stress is attributed to stress relaxation and/or slower reaction during dark periods. A viscoelastic stress model of this process was formulated and predicted stress values close to those observed experimentally. During drying of cellulose acetate (CA) coatings cast in acetone, final stress increased from 10 to 45 MPa as coating thickness decreased from 60 to 10 mum. This thickness dependent coating stress for a solvent-cast polymer coating is a new finding and is attributed to (1) less shrinkage in thicker coatings due to more trapped solvent (from skinning) and (2) greater amounts of polymer stress relaxation in thicker coatings. For porous CA coatings prepared by dry-cast phase separation, final in-plane stresses ranged from 20 MPa for coatings containing small pores (˜1 mum) to 5 MPa for coatings containing small pores and macrovoids (˜200 mum). For these coatings, a small amount of stress relaxation occurs due to capillary pressure relief. A stress plateau for the macrovoid-containing coating is likely caused by stress-induced rupture of the polymer-rich phase. Measured stress in pigment-free latex coatings was much lower (˜0.3 MPa) than UV-curable and solvent-cast polymer coatings and was found to increase with increasing latex glass transition

  2. Stem cell behavior on tailored porous oxide surface coatings.

    PubMed

    Lavenus, Sandrine; Poxson, David J; Ogievetsky, Nika; Dordick, Jonathan S; Siegel, Richard W

    2015-07-01

    Nanoscale surface topographies are known to have a profound influence on cell behavior, including cell guidance, migration, morphology, proliferation, and differentiation. In this study, we have observed the behavior of human mesenchymal stem cells cultured on a range of tailored porous SiO2 and TiO2 nanostructured surface coatings fabricated via glancing angle electron-beam deposition. By controlling the physical vapor deposition angle during fabrication, we could control systematically the deposited coating porosity, along with associated topographic features. Immunocytochemistry and image analysis quantitatively revealed the number of adherent cells, as well as their basic cellular morphology, on these surfaces. Signaling pathway studies showed that even with subtle changes in nanoscale surface structures, the behavior of mesenchymal stem cells was strongly influenced by the precise surface structures of these porous coatings. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Protective matching polymer powder coating of piezoelectric element

    NASA Astrophysics Data System (ADS)

    Gavrilova, V. A.; Fazlyyyakhmatov, M. G.; Kashapov, N. F.

    2013-12-01

    Objects of research are coatings and technology of their applying to the piezoelectric elements for ultrasound. Acoustic impedance and thicknesses of matching layers for medical ultrasound transducers have been defined. In this paper performance characteristics of coating systems with predetermined properties have been selected. The conditions for selection of polymer powder paint for quarter wave matching layer have been determined. Conditions of forming polymer powder coatings have been proposed.

  4. Spatial atomic layer deposition for coating flexible porous Li-ion battery electrodes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yersak, Alexander S.; Sharma, Kashish; Wallas, Jasmine M.

    Ultrathin atomic layer deposition (ALD) coatings on the electrodes of Li-ion batteries can enhance the capacity stability of the Li-ion batteries. To commercialize ALD for Li-ion battery production, spatial ALD is needed to decrease coating times and provide a coating process compatible with continuous roll-to-roll (R2R) processing. The porous electrodes of Li-ion batteries provide a special challenge because higher reactant exposures are needed for spatial ALD in porous substrates. This work utilized a modular rotating cylinder spatial ALD reactor operating at rotation speeds up to 200 revolutions/min (RPM) and substrate speeds up to 200 m/min. The conditions for spatial ALDmore » were adjusted to coat flexible porous substrates. The reactor was initially used to characterize spatial Al2O3 and ZnO ALD on flat, flexible metalized polyethylene terephthalate foils. These studies showed that slower rotation speeds and spacers between the precursor module and the two adjacent pumping modules could significantly increase the reactant exposure. The modular rotating cylinder reactor was then used to coat flexible, model porous anodic aluminum oxide (AAO) membranes. The uniformity of the ZnO ALD coatings on the porous AAO membranes was dependent on the aspect ratio of the pores and the reactant exposures. Larger reactant exposures led to better uniformity in the pores with higher aspect ratios. The reactant exposures were increased by adding spacers between the precursor module and the two adjacent pumping modules. The modular rotating cylinder reactor was also employed for Al2O3 ALD on porous LiCoO2 (LCO) battery electrodes. Uniform Al coverages were obtained using spacers between the precursor module and the two adjacent pumping modules at rotation speeds of 25 and 50 RPM. The LCO electrodes had a thickness of ~49 um and pores with aspect ratios of ~12-25. Coin cells were then constructed using the ALD-coated LCO electrodes and were tested to determine their battery

  5. Wetting of polymer melts on coated and uncoated steel surfaces

    NASA Astrophysics Data System (ADS)

    Vera, Julie; Contraires, Elise; Brulez, Anne-Catherine; Larochette, Mathieu; Valette, Stéphane; Benayoun, Stéphane

    2017-07-01

    A comparative study of the wetting of three different commercial polymer melts on various coated and uncoated steel surfaces is described in this report. The wettability of steel and coatings (three different titanium nitride coatings, TiN, TiNOx, TiNOy, a chromium coating, CrN, and a diamond-like carbon coating, DLC) used for mold in polymer processing is determined at different temperatures between 25 °C and 120 °C. Contact angle measurements of melted polypropylene (PP), Acrylonitrile Butadiene Styrene (ABS) and Polycarbonate (PC) on steel and on the different coatings were performed to investigate the wetting behavior under closer-to-processing conditions. Recommendations for good measurement conditions were proposed. Moreover, the surface free energy of each melt polymer was determined. The works of adhesion between all polymers and all substrates were established. Among all tested polymers, the lowest value of the works of adhesion is calculated for ABS and for PC thereafter, and the highest value is calculated for PP. These results will be particularly important for such applications as determining the extent to which these polymers can contribute to the replication quality in injection molding.

  6. Method for dialysis on microchips using thin porous polymer membrane

    DOEpatents

    Singh, Anup K [San Francisco, CA; Kirby, Brian J [San Francisco, CA; Shepodd, Timothy J [Livermore, CA

    2009-05-19

    Laser-induced phase-separation polymerization of a porous acrylate polymer is used for in-situ fabrication of dialysis membranes inside glass microchannels. A shaped 355 nm laser beam is used to produce a porous polymer membrane with a thickness of about 15 .mu.m, which bonds to the glass microchannel and forms a semi-permeable membrane. Differential permeation through a membrane formed with pentaerythritol triacrylate was observed and quantified by comparing the response of the membrane to fluorescein and fluorescently tagging 200 nm latex microspheres. Differential permeation was observed and quantified by comparing the response to rhodamine 560 and lactalbumin protein in a membrane formed with SPE-methylene bisacrylamide. The porous membranes illustrate the capability for the present technique to integrate sample cleanup into chip-based analysis systems.

  7. Shear Rheology of Suspensions of Porous Zeolite Particles in Concentrated Polymer Solutions

    NASA Astrophysics Data System (ADS)

    Olanrewaju, Kayode O.; Breedveld, Victor

    2008-07-01

    We present experimental data on the shear rheology of Ultem (polyetherimide)/NMP(l-methyl-2-pyrrolidinone) solutions with and without suspended surface-modified porous/nonporous zeolite (ZSM-5) particles. We found that the porous zeolite suspensions have relative viscosities that significantly exceed the Krieger-Dougherty predictions for hard sphere suspensions. The major origin of this discrepancy is the selective absorption of NMP solvent into the zeolite pores, which raises both the polymer concentration and the particle volume fraction, thus enhancing both the viscosity of the continuous phase Ultem/NMP polymer solution and the particle contribution to the suspension viscosity. Other factors, such as zeolite non-sphericity and specific interactions with Ultem polymer, contribute to the suspension viscosity to a lesser extent. We propose a predictive model for the viscosity of porous zeolite suspensions by incorporating an absorption parameter, α, into the Krieger-Dougherty model. We also propose independent approaches to determine α. The first one is indirect and based on zeolite density/porosity data, assuming that all pores will be filled with solvent. The other method is based on our experimental data, by comparing the viscosity data of porous versus non-porous zeolite suspensions. The different approaches are compared.

  8. Method for producing nanowire-polymer composite electrodes

    DOEpatents

    Pei, Qibing; Yu, Zhibin

    2017-11-21

    A method for producing flexible, nanoparticle-polymer composite electrodes is described. Conductive nanoparticles, preferably metal nanowires or nanotubes, are deposited on a smooth surface of a platform to produce a porous conductive layer. A second application of conductive nanoparticles or a mixture of nanoparticles can also be deposited to form a porous conductive layer. The conductive layer is then coated with at least one coating of monomers that is polymerized to form a conductive layer-polymer composite film. Optionally, a protective coating can be applied to the top of the composite film. In one embodiment, the monomer coating includes light transducing particles to reduce the total internal reflection of light through the composite film or pigments that absorb light at one wavelength and re-emit light at a longer wavelength. The resulting composite film has an active side that is smooth with surface height variations of 100 nm or less.

  9. Coated Porous Si for High Performance On-Chip Supercapacitors

    NASA Astrophysics Data System (ADS)

    Grigoras, K.; Keskinen, J.; Grönberg, L.; Ahopelto, J.; Prunnila, M.

    2014-11-01

    High performance porous Si based supercapacitor electrodes are demonstrated. High power density and stability is provided by ultra-thin TiN coating of the porous Si matrix. The TiN layer is deposited by atomic layer deposition (ALD), which provides sufficient conformality to reach the bottom of the high aspect ratio pores. Our porous Si supercapacitor devices exhibit almost ideal double layer capacitor characteristic with electrode volumetric capacitance of 7.3 F/cm3. Several orders of magnitude increase in power and energy density is obtained comparing to uncoated porous silicon electrodes. Good stability of devices is confirmed performing several thousands of charge/discharge cycles.

  10. New Polymer Coatings for Chemically Selective Mass Sensors

    NASA Technical Reports Server (NTRS)

    Sims, S. C.; Wright, Cassandra; Cobb, J.; McCalla, T.; Revelle, R.; Morris, V. R.; Pollack, S. K.

    1997-01-01

    There is a current need to develop sensitive and chemically specific sensors for the detection of nitric acid for in-situ measurements in the atmosphere. Polymer coatings have been synthesized and tested for their sensitivity and selectivity to nitric acid. A primary requirement for these polymers is detectability down to the parts per trillion range. The results of studies using these polymers as coatings for quartz crystal microbalances (QCM) and surface acoustic wave (SAW) devices will be presented.

  11. Facile Synthesis of Porous Silicon Nanofibers by Magnesium Reduction for Application in Lithium Ion Batteries.

    PubMed

    Cho, Daehwan; Kim, Moonkyoung; Hwang, Jeonghyun; Park, Jay Hoon; Joo, Yong Lak; Jeong, Youngjin

    2015-12-01

    We report a facile fabrication of porous silicon nanofibers by a simple three-stage procedure. Polymer/silicon precursor composite nanofibers are first fabricated by electrospinning, a water-based spinning dope, which undergoes subsequent heat treatment and then reduction using magnesium to be converted into porous silicon nanofibers. The porous silicon nanofibers are coated with a graphene by using a plasma-enhanced chemical vapor deposition for use as an anode material of lithium ion batteries. The porous silicon nanofibers can be mass-produced by a simple and solvent-free method, which uses an environmental-friendly polymer solution. The graphene-coated silicon nanofibers show an improved cycling performance of a capacity retention than the pure silicon nanofibers due to the suppression of the volume change and the increase of electric conductivity by the graphene.

  12. Osteostatin-coated porous titanium can improve early bone regeneration of cortical bone defects in rats.

    PubMed

    van der Stok, Johan; Lozano, Daniel; Chai, Yoke Chin; Amin Yavari, Saber; Bastidas Coral, Angela P; Verhaar, Jan A N; Gómez-Barrena, Enrique; Schrooten, Jan; Jahr, Holger; Zadpoor, Amir A; Esbrit, Pedro; Weinans, Harrie

    2015-05-01

    A promising bone graft substitute is porous titanium. Porous titanium, produced by selective laser melting (SLM), can be made as a completely open porous and load-bearing scaffold that facilitates bone regeneration through osteoconduction. In this study, the bone regenerative capacity of porous titanium is improved with a coating of osteostatin, an osteoinductive peptide that consists of the 107-111 domain of the parathyroid hormone (PTH)-related protein (PTHrP), and the effects of this osteostatin coating on bone regeneration were evaluated in vitro and in vivo. SLM-produced porous titanium received an alkali-acid-heat treatment and was coated with osteostatin through soaking in a 100 nM solution for 24 h or left uncoated. Osteostatin-coated scaffolds contained ∼0.1 μg peptide/g titanium, and in vitro 81% was released within 24 h. Human periosteum-derived osteoprogenitor cells cultured on osteostatin-coated scaffolds did not induce significant changes in osteogenic (alkaline phosphatase [ALP], collagen type 1 [Col1], osteocalcin [OCN], runt-related transcription factor 2 [Runx2]), or angiogenic (vascular endothelial growth factor [VEGF]) gene expression; however, it resulted in an upregulation of osteoprotegerin (OPG) gene expression after 24 h and a lower receptor activator of nuclear factor kappa-B ligand (RankL):OPG mRNA ratio. In vivo, osteostatin-coated, porous titanium implants increased bone regeneration in critical-sized cortical bone defects (p=0.005). Bone regeneration proceeded until 12 weeks, and femurs grafted with osteostatin-coated implants and uncoated implants recovered, respectively, 66% and 53% of the original femur torque strength (97±31 and 77±53 N·mm, not significant). In conclusion, the osteostatin coating improved bone regeneration of porous titanium. This effect was initiated after a short burst release and might be related to the observed in vitro upregulation of OPG gene expression by osteostatin in osteoprogenitor

  13. Pool boiling of nanofluids on rough and porous coated tubes: experimental and correlation

    NASA Astrophysics Data System (ADS)

    Cieśliński, Janusz T.; Kaczmarczyk, Tomasz Z.

    2014-06-01

    The paper deals with pool boiling of water-Al2O3 and water- Cu nanofluids on rough and porous coated horizontal tubes. Commercially available stainless steel tubes having 10 mm outside diameter and 0.6 mm wall thickness were used to fabricate the test heater. The tube surface was roughed with emery paper 360 or polished with abrasive compound. Aluminium porous coatings of 0.15 mm thick with porosity of about 40% were produced by plasma spraying. The experiments were conducted under different absolute operating pressures, i.e., 200, 100, and 10 kPa. Nanoparticles were tested at the concentration of 0.01, 0.1, and 1% by weight. Ultrasonic vibration was used in order to stabilize the dispersion of the nanoparticles. It was observed that independent of operating pressure and roughness of the stainless steel tubes addition of even small amount of nanoparticles augments heat transfer in comparison to boiling of distilled water. Contrary to rough tubes boiling heat transfer coefficient of tested nanofluids on porous coated tubes was lower compared to that for distilled water while boiling on porous coated tubes. A correlation equation for prediction of the average heat transfer coefficient during boiling of nanofluids on smooth, rough and porous coated tubes is proposed. The correlation includes all tested variables in dimensionless form and is valid for low heat flux, i.e., below 100 kW/m2.

  14. Polymer coating embolism from intravascular medical devices - a clinical literature review.

    PubMed

    Chopra, Amitabh M; Mehta, Monik; Bismuth, Jean; Shapiro, Maksim; Fishbein, Michael C; Bridges, Alina G; Vinters, Harry V

    Over the past three decades, lubricious (hydrophobic and/or hydrophilic) polymer-coated devices have been increasingly adopted by interventional physicians and vascular surgeons to access and treat a wider range of clinical presentations. Recent clinical literature highlights the presence of polymer coating emboli within the anatomy - a result of coating separation from an intravascular device - and associates it with a range of adverse clinical sequelae. The 2015 U.S. Food and Drug Administration safety communication titled "Lubricious Coating Separation from Intravascular Medical Devices" acknowledges these concerns and concludes that it will work with stakeholders to develop nonclinical test methodologies, establish performance criteria, and identify gaps in current national and international device standards for coating integrity performance. Despite this communication and multiple case reports from interventional physicians, pathologists, dermatologists and other involved physician specialties, polymer coating embolism remains clinically underrecognized. This article consolidates the available literature on polymer coating embolism (1986-2016) and highlights the following relevant information for the physician: (a) the history and elusive nature of polymer coating embolism; (b) potential incidence rates of this phenomenon; (c) reported histologic findings and clinical effects of polymer emboli in the anatomy; (d) the importance of the collaborative clinician-pathologist partnership to report polymer embolism findings; and (e) the importance to study particulate release from intravascular devices so as to further understand and potentially evolve coated interventional technologies. Preliminary research on coatings highlights the potential of using iterations of coatings on medical devices that attain the desired therapeutic result and mitigate or eliminate particulates altogether. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  15. Systems and strippable coatings for decontaminating structures that include porous material

    DOEpatents

    Fox, Robert V [Idaho Falls, ID; Avci, Recep [Bozeman, MT; Groenewold, Gary S [Idaho Falls, ID

    2011-12-06

    Methods of removing contaminant matter from porous materials include applying a polymer material to a contaminated surface, irradiating the contaminated surface to cause redistribution of contaminant matter, and removing at least a portion of the polymer material from the surface. Systems for decontaminating a contaminated structure comprising porous material include a radiation device configured to emit electromagnetic radiation toward a surface of a structure, and at least one spray device configured to apply a capture material onto the surface of the structure. Polymer materials that can be used in such methods and systems include polyphosphazine-based polymer materials having polyphosphazine backbone segments and side chain groups that include selected functional groups. The selected functional groups may include iminos, oximes, carboxylates, sulfonates, .beta.-diketones, phosphine sulfides, phosphates, phosphites, phosphonates, phosphinates, phosphine oxides, monothio phosphinic acids, and dithio phosphinic acids.

  16. Controlled release from drug microparticles via solventless dry-polymer coating.

    PubMed

    Capece, Maxx; Barrows, Jason; Davé, Rajesh N

    2015-04-01

    A novel solvent-less dry-polymer coating process employing high-intensity vibrations avoiding the use of liquid plasticizers, solvents, binders, and heat treatments is utilized for the purpose of controlled release. The main hypothesis is that such process having highly controllable processing intensity and time may be effective for coating particularly fine particles, 100 μm and smaller via exploiting particle interactions between polymers and substrates in the dry state, while avoiding breakage yet achieving conformal coating. The method utilizes vibratory mixing to first layer micronized polymer onto active pharmaceutical ingredient (API) particles by virtue of van der Waals forces and to subsequently mechanically deform the polymer into a continuous film. As a practical example, ascorbic acid and ibuprofen microparticles, 50-500 μm, are coated with the polymers polyethylene wax or carnauba wax, a generally recognized as safe material, resulting in controlled release on the order of seconds to hours. As a novelty, models are utilized to describe the coating layer thickness and the controlled-release behavior of the API, which occurs because of a diffusion-based mechanism. Such modeling would allow the design and control of the coating process with application for the controlled release of microparticles, particularly those less than 100 μm, which are difficult to coat by conventional solvent coating methods. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

  17. Distributed Pore Chemistry in Porous Organic Polymers

    NASA Technical Reports Server (NTRS)

    Koontz, Steven L. (Inventor)

    1999-01-01

    A method for making a biocompatible polymer article using a uniform atomic oxygen treatment is disclosed. The substrate may be subsequently optionally grated with a compatibilizing compound. Compatibilizing compounds may include proteins, phosphorylcholine groups, platelet adhesion preventing polymers, albumin adhesion promoters, and the like. The compatibilized substrate may also have a living cell layer adhered thereto. The atomic oxygen is preferably produced by a flowing afterglow microwave discharge. wherein the substrate resides in a sidearm out of the plasma. Also, methods for culturing cells for various purposes using the various membranes are disclosed as well. Also disclosed are porous organic polymers having a distributed pore chemistry (DPC) comprising hydrophilic and hydrophobic regions. and a method for making the DPC by exposing the polymer to atomic oxygen wherein the rate of hydrophilization is greater than the rate of mass loss.

  18. Distributed Pore Chemistry in Porous Organic Polymers

    NASA Technical Reports Server (NTRS)

    Koontz, Steven L. (Inventor)

    1998-01-01

    A method for making a biocompatible polymer article using a uniform atomic oxygen treatment is disclosed. The sub-strate may be subsequently optionally grated with a compatibilizing compound. Compatibilizing compounds may include proteins, phosphorylcholine groups, platelet adhesion preventing polymers, albumin adhesion promoters, and the like. The compatibilized substrate may also have a living cell layer adhered thereto. The atomic oxygen is preferably produced by a flowing afterglow microwave discharge, wherein the substrate resides in a sidearm out of the plasma. Also, methods for culturing cells for various purposes using the various membranes are disclosed as well. Also disclosed are porous organic polymers having a distributed pore chemistry (DPC) comprising hydrophilic and hydrophobic region, and a method for making the DPC by exposing the polymer to atomic oxygen wherein the rate of hydrophilization is greater than the rate of mass loss.

  19. Diagnostics of transparent polymer coatings of metal items

    NASA Astrophysics Data System (ADS)

    Varepo, L. G.; Ermakova, I. N.; Nagornova, I. V.; Kondratov, A. P.

    2017-08-01

    The methods of visual and instrumental express diagnostics of safety critical defects and non-uniform thickness of transparent mono- and multilayer polyolefin surface coating of metal items are analyzed in the paper. The instrumental diagnostics method relates to colorimetric measuring based on effects, which appear in the polarized light for extrusion polymer coatings. A color coordinates dependence (in the color system CIE La*b*) on both HDPE / PVC coating thickness fluctuation values (from average ones) and coating interlayer or adhesion layer delaminating is shown. A variation of color characteristics in the polarized light at a liquid penetration into delaminated polymer layers is found. Measuring parameters and critical uncertainties are defined.

  20. Modeling electrical response of polymer-coated SAW resonators by equivalent circuit representation.

    PubMed

    Kshetrimayum, Roshan; Yadava, R D S; Tandon, R P

    2011-07-01

    The paper presents an equivalent circuit model of the polymer coated surface acoustic wave (SAW) resonators by combining coupling-of-mode (COM) description of SAW resonators and perturbation calculation of SAW propagation under polymer loading. An expression for the motional load produced by polymer coating is deduced in terms of COM parameters and polymer characteristics. In addition, expressions for the shifts in resonance frequency and attenuation due to polymer loading are obtained. Simulation results are presented for one-port and two-port resonator devices coated with viscoelastic thin polymer film. The influence of polymer film on resonator response is studied with regard to variations in film thickness and shear modulus. The model simplifies understanding of polymer-coated SAW sensors. Copyright © 2010 Elsevier B.V. All rights reserved.

  1. Semipermeable polymers and method for producing same

    DOEpatents

    Buschmann, Wayne E [Boulder, CO

    2012-04-03

    A polyamide membrane comprising reaction product of an anhydrous solution comprising an anhydrous solvent, at least one polyfunctional secondary amine and a pre-polymer deposition catalyst; and an anhydrous, organic solvent solution comprising a polyfunctional aromatic amine-reactive reactant comprising one ring. A composite semipermeable membrane comprising the polyamide membrane on a porous support. A method of making a composite semipermeable membrane by coating a porous support with an anhydrous solution comprising an anhydrous solvent, a polyfunctional secondary amine and a pre-polymer deposition catalyst, to form an activated pre-polymer layer on the porous support and contacting the activated pre-polymer layer with an anhydrous, organic solvent solution comprising a polyfunctional amine-reactive reactant to interfacially condense the amine-reactive reactant with the polyfunctional secondary amine, thereby forming a cross-linked, interfacial polyamide layer on the porous support. A method of impregnating a composite semipermeable membrane with nanoparticles selected from heavy metals and/or oxides of heavy metals.

  2. Biodegradable polymer for sealing porous PEO layer on pure magnesium: An in vitro degradation study

    NASA Astrophysics Data System (ADS)

    Alabbasi, Alyaa; Mehjabeen, Afrin; Kannan, M. Bobby; Ye, Qingsong; Blawert, Carsten

    2014-05-01

    An attempt was made to seal the porous silicate-based plasma electrolytic oxidation (PEO) layer on pure magnesium (Mg) with a biodegradable polymer, poly(L-lactide) (PLLA), to delay the localized degradation of magnesium-based implants in body fluid for better in-service mechanical integrity. Firstly, a silicate-based PEO coating on pure magnesium was performed using a pulsed constant current method. In order to seal the pores in the PEO layer, PLLA was coated using a two-step spin coating method. The performance of the PEO-PLLA Mg was evaluated using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The EIS results showed that the polarization resistance (Rp) of the PEO-PLLA Mg was close to two orders of magnitude higher than that of the PEO Mg. While the corrosion current density (icorr) of the pure Mg was reduced by 65% with the PEO coating, the PEO-PLLA coating reduced the icorr by almost 100%. As expected, the Rp of the PEO-PLLA Mg decreased with increase in exposure time. However, it was noted that the Rp of the PEO-PLLA Mg even after 100 h was six times higher than that of the PEO Mg after 48 h exposure, and did not show any visible localized attack.

  3. Improvement of the compressive strength of a cuttlefish bone-derived porous hydroxyapatite scaffold via polycaprolactone coating.

    PubMed

    Kim, Beom-Su; Kang, Hyo Jin; Lee, Jun

    2013-10-01

    Cuttlefish bones (CBs) have emerged as attractive biomaterials because of their porous structure and components that can be converted into hydroxyapatite (HAp) via a hydrothermal reaction. However, their brittleness and low strength restrict their application in bone tissue engineering. Therefore, to improve the compressive strength of the scaffold following hydrothermal conversion to a HAp form of CB (CB-HAp), the scaffold was coated using a polycaprolactone (PCL) polymer at various concentrations. In this study, raw CB was successfully converted into HAp via a hydrothermal reaction. We then evaluated their surface properties and composition by scanning electron microscopy and X-ray diffraction analysis. The CB-HAp coated with PCL showed improved compressive performance and retained a microporous structure. The compressive strength was significantly increased upon coating with 5 and 10% PCL, by 2.09- and 3.30-fold, respectively, as compared with uncoated CB-HAp. However, coating with 10% PCL resulted in a reduction in porosity. Furthermore, an in vitro biological evaluation demonstrated that MG-63 cells adhered well, proliferated and were able to be differentiated on the PCL-coated CB-HAp scaffold, which was noncytotoxic. These results suggest that a simple coating method is useful to improve the compressive strength of CB-HAp for bone tissue engineering applications. Copyright © 2013 Wiley Periodicals, Inc.

  4. Acoustic emission during fatigue of porous-coated Ti-6Al-4V implant alloy.

    PubMed

    Kohn, D H; Ducheyne, P; Awerbuch, J

    1992-01-01

    Acoustic emission (AE) events and event intensities (e.g., event amplitude, counts, duration, and energy counts) were recorded and analyzed during fatigue loading of uncoated and porous-coated Ti-6Al-4V. AE source location, spatial filtering, event, and event intensity distributions were used to detect, monitor, analyze, and predict failures. AE provides the ability to spatially and temporally locate multiple fatigue cracks, in real time. Fatigue of porous-coated Ti-6Al-4V is governed by a sequential, multimode fracture process of: transverse fracture in the porous coating; sphere/sphere and sphere/substrate debonding; substrate fatigue crack initiation; slow and rapid substrate fatigue crack propagation. Because of the porosity of the coating, the different stages of fracture within the coating occur in a discontinuous fashion. Therefore, the AE events generated are intermittent and the onset of each mode of fracture in the porous coating can be detected by increases in AE event rate. Changes in AE event rate also correspond to changes in crack extension rate, and may therefore be used to predict failure. AE offers two distinct advantages over conventional optical and microscopic methods of analyzing fatigue cracks--it is more sensitive and it can determine the time history of damage progression. The magnitude of the AE event intensities increased with increasing stress. Failure mechanisms are best differentiated by analyzing AE event amplitudes. Intergranular fracture and microvoid coalescence generated the highest AE event amplitudes (100 dB), whereas, plastic flow and friction generated the lowest AE event amplitudes (55-65 dB). Fractures in the porous coating were characterized by AE event amplitudes of less than 80 dB.

  5. Surface-enhanced Raman spectroscopy using silver-coated porous glass-ceramic substrates.

    PubMed

    Pan, Z; Zavalin, A; Ueda, A; Guo, M; Groza, M; Burger, A; Mu, R; Morgan, S H

    2005-06-01

    Surface-enhanced Raman scattering (SERS) has been studied using a silver-coated porous glass-ceramic material as a new type of substrate. The porous glass-ceramic is in the CaO-TiO2-P2O5 system prepared by controlled crystallization and subsequent chemical leaching of the dense glass-ceramic, leaving a solid skeleton with pores ranging in size from 50 nm to submicrometer. Silver was coated on the surface of the porous glass-ceramic by radio frequency (RF) sputtering or e-beam evaporation in vacuum. SERS spectra of excellent quality were obtained from several dyes and carboxylic acid molecules, including rhodamine 6G, crystal violet, isonicotinic acid, and benzoic acid, using this new substrate. This new substrate showed a good compatibility with these molecules. The porous glass ceramic with a nanometer-structured surface accommodated both test molecules and silver film. The absorbed molecules were therefore better interfaced with silver for surface-enhanced Raman scattering.

  6. The shear strength of three-dimensional capillary-porous titanium coatings for intraosseous implants.

    PubMed

    Kalita, V I; Komlev, D I; Komlev, V S; Radyuk, A A

    2016-03-01

    A plasma spraying process for the deposition of three-dimensional capillary-porous titanium coatings using a wire has been developed. In this process, two additional dc arcs are discharged between plasmatron and both the wire and the substrate, resulting in additional activation of the substrate and the particles, particularly by increasing their temperature. The shear strength of the titanium coating with 46% porosity is 120.6 MPa. A new procedure for estimating the shear strength of porous coatings has been developed. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Polymer Brush-Functionalized Chitosan Hydrogels as Antifouling Implant Coatings.

    PubMed

    Buzzacchera, Irene; Vorobii, Mariia; Kostina, Nina Yu; de Los Santos Pereira, Andres; Riedel, Tomáš; Bruns, Michael; Ogieglo, Wojciech; Möller, Martin; Wilson, Christopher J; Rodriguez-Emmenegger, Cesar

    2017-06-12

    Implantable sensor devices require coatings that efficiently interface with the tissue environment to mediate biochemical analysis. In this regard, bioinspired polymer hydrogels offer an attractive and abundant source of coating materials. However, upon implantation these materials generally elicit inflammation and the foreign body reaction as a consequence of protein fouling on their surface and concomitant poor hemocompatibility. In this report we investigate a strategy to endow chitosan hydrogel coatings with antifouling properties by the grafting of polymer brushes in a "grafting-from" approach. Chitosan coatings were functionalized with polymer brushes of oligo(ethylene glycol) methyl ether methacrylate and 2-hydroxyethyl methacrylate using photoinduced single electron transfer living radical polymerization and the surfaces were thoroughly characterized by XPS, AFM, water contact angle goniometry, and in situ ellipsometry. The antifouling properties of these new bioinspired hydrogel-brush coatings were investigated by surface plasmon resonance. The influence of the modifications to the chitosan on hemocompatibility was assessed by contacting the surfaces with platelets and leukocytes. The coatings were hydrophilic and reached a thickness of up to 180 nm within 30 min of polymerization. The functionalization of the surface with polymer brushes significantly reduced the protein fouling and eliminated platelet activation and leukocyte adhesion. This methodology offers a facile route to functionalizing implantable sensor systems with antifouling coatings that improve hemocompatibility and pave the way for enhanced device integration in tissue.

  8. Safety, reliability, and operability of cochlear implant electrode arrays coated with biocompatible polymer.

    PubMed

    Kinoshita, Makoto; Kikkawa, Yayoi S; Sakamoto, Takashi; Kondo, Kenji; Ishihara, Kazuhiko; Konno, Tomohiro; Pawsey, Nick; Yamasoba, Tatsuya

    2015-04-01

    Polymer-coated electrodes can reduce surgically-induced trauma associated with the insertion of a cochlear implant (CI) electrode array. To evaluate if insertion trauma in CI surgery can be reduced by using electrode arrays coated with 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer. We analyzed characteristics of the Contour Advance electrode arrays coated with MPC polymer. To assess surgical trauma during electrode insertion, polymer-coated or uncoated (n = 5 each) animal electrode arrays were implanted in guinea pig cochleae and operability and electrophysiological and histological changes were assessed. Under light and scanning electron microscopy, polymer-coated electrodes did not appear different from uncoated electrodes, and no change was observed after mechanical stressing of the arrays. Electrode insertion was significantly easier when polymer-coated electrodes were used. Auditory brainstem response (ABR) thresholds did not differ between groups, but p1-n1 amplitudes of the coated group were larger compared with the uncoated group at 32 kHz at 28 days after surgery. The survival of outer hair cells and spiral ganglion cells was significantly greater in the polymer-coated group.

  9. In-syringe extraction using dissolvable layered double hydroxide-polymer sponges templated from hierarchically porous coordination polymers.

    PubMed

    Ghani, Milad; Frizzarin, Rejane M; Maya, Fernando; Cerdà, Víctor

    2016-07-01

    Herein we report the use of cobalt porous coordination polymers (PCP) as intermediates to prepare advanced extraction media based on layered double hydroxides (LDH) supported on melamine polymer foam. The obtained dissolvable Ni-Co LDH composite sponges can be molded and used as sorbent for the in-syringe solid-phase extraction (SPE) of phenolic acids from fruit juices. The proposed sorbent is obtained due to the surfactant-assisted self-assembly of Co(II)/imidazolate PCPs on commercially available melamine foam, followed by the in situ conversion of the PCP into the final dissolvable LDH coating. Advantageous features for SPE are obtained by using PCPs with hierarchical porosity (HPCPs). The LDH-sponge prepared using intermediate HPCPs (HLDH-sponge) is placed in the headspace of a glass syringe, enabling flow-through extraction followed by analyte elution by the dissolution of the LDH coating in acidic conditions. Three phenolic acids (gallic acid, p-hydroxybenzoic acid and caffeic acid) were extracted and quantified using high performance liquid chromatography. Using a 5mL sample volume, the obtained detection limits were 0.15-0.35μgL(-1). The proposed method for the preparation of HLDH-sponges showed a good reproducibility as observed from the intra- and inter-day RSD's, which were <10% for all analytes. The batch-to-batch reproducibility for three different batches of HLDH-sponges was 10.6-11.2%. Enrichment factors of 15-21 were obtained. The HLDH-sponges were applied satisfactorily to the determination of phenolic acids in natural and commercial fruit juices, obtaining relative recoveries among 89.7-95.3%. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Photocatalytic TiO2 nanoparticles enhanced polymer antimicrobial coating

    NASA Astrophysics Data System (ADS)

    Wei, Xiaojin; Yang, Zhendi; Tay, See Leng; Gao, Wei

    2014-01-01

    Copper (Cu) containing coatings can provide sustainable protection against microbial contamination. However, metallic Cu coatings have not been widely used due to the relatively high cost, poor corrosion resistance, and low compatibility with non-metal substrates. Titanium dioxide (TiO2) possesses antibacterial functions by its photocatalytic properties which can destroy bacteria or suppress their reproduction. TiO2 also has the function of improving the mechanical properties through particle dispersion strengthening. We have recently developed an innovative polymer based coating system containing fine particles of Cu and TiO2 nanoparticles. These polymer based coatings simultaneously display excellent antimicrobial and good mechanical properties. The results showed that the addition of TiO2 has improved the antimicrobial property under sunlight, which provides extended applications in outdoor environment. The elimination of 106 bacterial by contacting the coatings without TiO2 needs 5 h, while contacting with the Cu/TiO2- 1 wt.% TiO2 took only 2 h to kill the same amount of bacteria. The coatings also presented enhanced hardness and wear resistance after adding TiO2. The width of wear track decreased from 270 μm of the Cu-polymer coating to 206 μm of Cu/TiO2-polymer coatings with 10 wt.% TiO2. Synchrotron Infrared Microscopy was used to in-situ and in-vivo study the bacteria killing process at the molecular level. The real-time chemical images of bacterial activities showed that the bacterial cell membranes were damaged by the Cu and TiO2 containing coatings

  11. Production of porous coating on a prosthesis

    DOEpatents

    Sump, Kenneth R.

    1987-01-01

    Preselected surface areas of a prosthesis are covered by a blend of matching primary metallic particles and expendable particles. The particles are compressed and heated to assure that deformation and metallurgical bonding occurs between them and between the primary particles and the surface boundaries of the prosthesis. Porosity is achieved by removal of the expendable material. The result is a coating including discrete bonded particles separated by a network of interconnected voids presenting a homogeneous porous coating about the substrate. It has strength suitable for bone implant usage without intermediate adhesives, and adequate porosity to promote subsequent bone ingrowth.

  12. Porous coatings from wire mesh for bone implants

    DOEpatents

    Sump, Kenneth R.

    1986-01-01

    A method of coating areas of bone implant elements and the resulting implant having a porous coating are described. Preselected surface areas are covered by a preform made from continuous woven lengths of wire. The preform is compressed and heated to assure that diffusion bonding occurs between the wire surfaces and between the surface boundaries of the implant element and the wire surfaces in contact with it. Porosity is achieved by control of the resulting voids between the bonded wire portions.

  13. Optical ammonia gas sensor based on a porous silicon rugate filter coated with polymer-supported dye.

    PubMed

    Shang, Yunling; Wang, Xiaobo; Xu, Erchao; Tong, Changlun; Wu, Jianmin

    2011-01-24

    An ammonia gas sensor chip was prepared by coating an electrochemically-etched porous Si rugate filter with a chitosan film that is crosslinked by glycidoxypropyltrimethoxysilane (GPTMS). The bromothylmol blue (BTB), a pH indicator, was loaded in the film as ammonia-sensing molecules. White light reflected from the porous Si has a narrow bandwidth spectrum with a peak at 610 nm. Monitoring reflective optical intensity at the peak position allows for direct, real-time observation of changes in the concentration of ammonia gas in air samples. The reflective optical intensity decreased linearly with increasing concentrations of ammonia gas over the range of 0-100 ppm. The lowest detection limit was 0.5 ppm for ammonia gas. At optimum conditions, the full response time of the ammonia gas sensor was less than 15s. The sensor chip also exhibited a good long-term stability over 1 year. Therefore, the simple sensor design has potential application in miniaturized optical measurement for online ammonia gas detection. Copyright © 2010 Elsevier B.V. All rights reserved.

  14. Aqueous vinylidene fluoride polymer coating composition

    NASA Technical Reports Server (NTRS)

    Bartoszek, Edward J. (Inventor); Christofas, Alkis (Inventor)

    1978-01-01

    A water-based coating composition which may be air dried to form durable, fire resistant coatings includes dispersed vinylidene fluoride polymer particles, emulsified liquid epoxy resin and a dissolved emulsifying agent for said epoxy resin which agent is also capable of rapidly curing the epoxy resin upon removal of the water from the composition.

  15. Water Vapor Permeation of Metal Oxide/Polymer Coated Plastic Films

    NASA Astrophysics Data System (ADS)

    Numata, Yukihiro; Oya, Toshiyuki; Kuwahara, Mitsuru; Ito, Katsuya

    Barrier performance to water vapor permeation of ceramic coated layers deposited on flexible polymer films is of great interest to food packaging, medical device packaging and flat panel display industries. In this study, a new type film in which a ceramic layer is deposited on a polymer coated film was proposed for lower water vapor permeation. It is important how to control interfacial properties between each layer and film for good barrier performance. Several kinds of polymer coated materials were prepared for changing surface free energy of the films before and after depositing the ceramic layer. The ceramic layer, which is composed of mixed material of SiO2 and Al2O3, was adopted under the same conditions. The following results were obtained; 1) Water vapor permeation is not related to the surface energy of polymer coated films, 2) After depositing the ceramic layer, however, a strong correlation is observed between the water vapor permeation and surface free energy. 3) The phenomenon is considered that the polarity of the polymer layers plays a key role in changing the structure of ceramic coated layers.

  16. Structure and properties of polymer nanocomposite coatings applied by the HVOF process

    NASA Astrophysics Data System (ADS)

    Petrovicova, Elena

    1999-11-01

    A high velocity oxy-fuel (HVOF) combustion spray process was used to produce coatings from nylon 11 powders with average starting particle diameters of 30 and 60 gin. Silica and carbon black were used as nanosized reinforcements, and their nominal content was varied from 0 to 15 vol. %. Optimization of the HVOF processing parameters was based on an assessment of the degree of splatting of polymer particles, and was accomplished by varying the jet temperature (via the hydrogen/oxygen ratio). Gas mixtures with low hydrogen contents minimized polymer particle degradation. Analytical modeling of particle temperature profiles confirmed the effect of the gas velocity and temperature on the particle heating and resulting coating properties. The morphology of the polymer and the microstructure of the coatings depended on the reinforcement surface chemistry and the volume fraction of the reinforcement, as well as the initial nylon 11 particle size. Although all reinforced coatings had higher crystallinities than pure nylon 11 coatings, coatings produced from a smaller starting polymer particle size (30 mum) exhibited improved spatial distribution of the silica in the matrix and lower crystallinity. In addition, coatings produced from the smaller polymer particles had a higher density and lower porosity due to a higher degree of melting and splatting compared to coatings produced from larger particles (60 mum). Nanoreinforced coatings exhibited increased scratch and sliding wear resistance and improved mechanical and barrier properties. Improvements of up to 35% in scratch and 67% in wear resistance were obtained for coatings with nominal 15 vol. % contents of hydrophobic silica or carbon black, relative to nonreinforced coatings. Reinforcement of the polymer matrix resulted in increases of ca. 200% in the storage modulus both below and above the glass transition temperature. The increase in crystallinity seemed to further enhance the reinforcement provided by the

  17. Porous titanium construct cup compared to porous coated titanium cup in total hip arthroplasty. A randomised controlled trial.

    PubMed

    Salemyr, Mats; Muren, Olle; Eisler, Thomas; Bodén, Henrik; Chammout, Ghazi; Stark, André; Sköldenberg, Olof

    2015-05-01

    The purpose of this study was to determine if a new titanium cup with increased porosity resulted in different periacetabular bone loss and migration compared to a porous coated cup. Fifty-one patients with primary hip osteoarthritis were randomized to either a cup with porous titanium construct backside (porous titanium group, n = 25) or a conventional porous coated titanium cup (control group, n = 26). The primary outcome variable was change in periacetabular bone mineral density two years after surgery measured with dual energy X-ray absorptiometry (DXA). Secondary outcomes were implant fixation measured with radiostereometry (RSA) and clinical outcome scores. The pattern of bone remodelling was similar in the two groups with almost complete restoration to baseline values. BMD diminished in the two proximal zones and increased in the two distal zones. After minimal migration up to six months all implants in both groups became stable. We found no difference between the two groups in clinical outcome scores. In this prospective, randomized, controlled trial on a new porous titanium cup we found, compared to the control group, no clinically relevant differences regarding periacetabular bone preservation, implant fixation or clinical outcome up to two years postoperatively.

  18. Thermal Protective Coating for High Temperature Polymer Composites

    NASA Technical Reports Server (NTRS)

    Barron, Andrew R.

    1999-01-01

    The central theme of this research is the application of carboxylate-alumoxane nanoparticles as precursors to thermally protective coatings for high temperature polymer composites. In addition, we will investigate the application of carboxylate-alumoxane nanoparticle as a component to polymer composites. The objective of this research was the high temperature protection of polymer composites via novel chemistry. The significance of this research is the development of a low cost and highly flexible synthetic methodology, with a compatible processing technique, for the fabrication of high temperature polymer composites. We proposed to accomplish this broad goal through the use of a class of ceramic precursor material, alumoxanes. Alumoxanes are nano-particles with a boehmite-like structure and an organic periphery. The technical goals of this program are to prepare and evaluate water soluble carboxylate-alumoxane for the preparation of ceramic coatings on polymer substrates. Our proposed approach is attractive since proof of concept has been demonstrated under the NRA 96-LeRC-1 Technology for Advanced High Temperature Gas Turbine Engines, HITEMP Program. For example, carbon and Kevlar(tm) fibers and matting have been successfully coated with ceramic thermally protective layers.

  19. Bioresponsive polymer coated drug nanorods for breast cancer treatment

    NASA Astrophysics Data System (ADS)

    Laemthong, Tunyaboon; Kim, Hannah H.; Dunlap, Kelly; Brocker, Caitlin; Barua, Dipak; Forciniti, Daniel; Huang, Yue-Wern; Barua, Sutapa

    2017-01-01

    Ineffective drug release at the target site is among the top challenges for cancer treatment. This reflects the facts that interaction with the physiological condition can denature active ingredients of drugs, and low delivery to the disease microenvironment leads to poor therapeutic outcomes. We hypothesize that depositing a thin layer of bioresponsive polymer on the surface of drug nanoparticles would not only protect drugs from degradation but also allow the release of drugs at the target site. Here, we report a one-step process to prepare bioresponsive polymer coated drug nanorods (NRs) from liquid precursors using the solvent diffusion method. A thin layer (10.3 ± 1.4 nm) of poly(ε-caprolactone) (PCL) polymer coating was deposited on the surface of camptothecin (CPT) anti-cancer drug NRs. The mean size of PCL-coated CPT NRs was 500.9 ± 91.3 nm length × 122.7 ± 10.1 nm width. The PCL polymer coating was biodegradable at acidic pH 6 as determined by Fourier transform infrared spectroscopy. CPT drugs were released up to 51.5% when PCL coating dissolved into non-toxic carboxyl and hydroxyl groups. Trastuzumab (TTZ), a humanized IgG monoclonal antibody, was conjugated to the NR surface for breast cancer cell targeting. Combination treatments using CPT and TTZ decreased the HER-2 positive BT-474 breast cancer cell growth by 66.9 ± 5.3% in vitro. These results suggest effective combination treatments of breast cancer cells using bioresponsive polymer coated drug delivery.

  20. Glucose biosensors with enzyme entrapped in polymer coating.

    PubMed

    Yang, S; Atanasov, P; Wilkins, E

    1995-01-01

    The pursuit of reliable biosensors for measuring glucose levels has been ongoing for decades. Their importance lies partly in the development of the implantable artificial pancrease, which can be used to deliver insulin to diabetics without the need to test glucose levels externally, with automatic delivery based on physiologic demand. Glucose sensors can also be used in short-term monitoring of glucose levels in hospitals and clinical laboratories. Three types of glucose biosensors were studied. All were based on a two-electrode system: an insulated platinum wire as a hydrogen peroxide electrode, and a silver wire twisted around the platinum wire as both a reference and a counter electrode. Each was coated with the enzyme glucose oxidase entrapped in a polymer matrix of cellulose acetate (CA) or poly 2-hydroxyethyl methacrylate (HEMA), then dip-coated by an additional polymer coating of polyvinylchloride (PVC), polyurethane (PU), or HEMA. The experiments were designed mainly to study the effectiveness of polymer coatings as diffusion-limiting membranes. The effect of each coating on the linear response to glucose concentration was examined. It was shown that additional (multiple) coatings can increase the linearity of the sensor response. The best results were obtained when the sensor was PVC-dip-coated three times. This preparation had a linear response up to 600 mg/DL glucose concentration. The sensors coated with PU and HEMA have linearity up to 280 and 240 mg/DL glucose concentrations, respectively. It was also shown that the coatings reduce interference from certain body chemicals.

  1. Staphylococcal biofilm growth on smooth and porous titanium coatings for biomedical applications.

    PubMed

    Braem, Annabel; Van Mellaert, Lieve; Mattheys, Tina; Hofmans, Dorien; De Waelheyns, Evelien; Geris, Liesbet; Anné, Jozef; Schrooten, Jan; Vleugels, Jef

    2014-01-01

    Implant-related infections are a serious complication in prosthetic surgery, substantially jeopardizing implant fixation. As porous coatings for improved osseointegration typically present an increased surface roughness, their resulting large surface area (sometimes increasing with over 700% compared to an ideal plane) renders the implant extremely susceptible to bacterial colonization and subsequent biofilm formation. Therefore, there is particular interest in orthopaedic implantology to engineer surfaces that combine both the ability to improve osseointegration and at the same time reduce the infection risk. As part of this orthopaedic coating development, the interest of in vitro studies on the interaction between implant surfaces and bacteria/biofilms is growing. In this study, the in vitro staphylococcal adhesion and biofilm formation on newly developed porous pure Ti coatings with 50% porosity and pore sizes up to 50 μm is compared to various dense and porous Ti or Ti-6Al-4V reference surfaces. Multiple linear regression analysis indicates that surface roughness and hydrophobicity are the main determinants for bacterial adherence. Accordingly, the novel coatings display a significant reduction of up to five times less bacterial surface colonization when compared to a commercial state-of-the-art vacuum plasma sprayed coating. However, the results also show that a further expansion of the porosity with over 15% and/or the pore size up to 150 μm is correlated to a significant increase in the roughness parameters resulting in an ascent of bacterial attachment. Chemically modifying the Ti surface in order to improve its hydrophilicity, while preserving the average roughness, is found to strongly decrease bacteria quantities, indicating the importance of surface functionalization to reduce the infection risk of porous coatings. Copyright © 2013 Wiley Periodicals, Inc.

  2. Hydroxyapatite coatings deposited by liquid precursor plasma spraying: controlled dense and porous microstructures and osteoblastic cell responses.

    PubMed

    Huang, Yi; Song, Lei; Liu, Xiaoguang; Xiao, Yanfeng; Wu, Yao; Chen, Jiyong; Wu, Fang; Gu, Zhongwei

    2010-12-01

    Hydroxyapatite coatings were deposited on Ti-6Al-4V substrates by a novel plasma spraying process, the liquid precursor plasma spraying (LPPS) process. X-ray diffraction results showed that the coatings obtained by the LPPS process were mainly composed of hydroxyapatite. The LPPS process also showed excellent control on the coating microstructure, and both nearly fully dense and highly porous hydroxyapatite coatings were obtained by simply adjusting the solid content of the hydroxyapatite liquid precursor. Scanning electron microscope observations indicated that the porous hydroxyapatite coatings had pore size in the range of 10-200 µm and an average porosity of 48.26 ± 0.10%. The osteoblastic cell responses to the dense and porous hydroxyapatite coatings were evaluated with human osteoblastic cell MG-63, in respect of the cell morphology, proliferation and differentiation, with the hydroxyapatite coatings deposited by the atmospheric plasma spraying (APS) process as control. The cell experiment results indicated that the heat-treated LPPS coatings with a porous structure showed the best cell proliferation and differentiation among all the hydroxyapatite coatings. Our results suggest that the LPPS process is a promising plasma spraying technique for fabricating hydroxyapatite coatings with a controllable microstructure, which has great potential in bone repair and replacement applications.

  3. Preceramic Polymers for Use as Fiber Coatings

    NASA Technical Reports Server (NTRS)

    Heimann, P. J.; Hurwitz, F. I.; Wheeler, D.; Eldridge, J.; Baranwal, R.; Dickerson, R.

    1996-01-01

    Polymeric precursors to Si-C-O, SI-B-N and Si-C were evaluated for use as ceramic interfaces in ceramic matrix composites. Use of the preceramic polymers allows for easy dip coating of fibers from dilute solutions of a polymer, which are then pyrolyzed to obtain the ceramic. SCS-0 fibers (Textron Specialty Materials, Lowell, MA) were coated with polymers from three systems: polysilsesquioxanes, polyborosilazanes and polycarbosilanes. The polysilsesquioxane systems were shown to produce either silicon oxycarbide or silicon oxynitride, depending on the pyrolysis conditions, and demonstrated some promise in an RBSN (reaction-bonded silicon nitride) matrix model system. Polyborosilazanes were shown, in studies of bulk polymers, to give rise to oxidation resistant Si-B-N ceramics which remain amorphous to temperatures of 1600 C, and should therefore provide a low modulus interface. Polycarbosilanes produce amorphous carbon-rich Si-C materials which have demonstrated oxidation resistance.

  4. Outcomes of Newer Generation Cementless Total Knee Arthroplasty: Beaded Periapatite-Coated vs Highly Porous Titanium-Coated Implants.

    PubMed

    Harwin, Steven F; Patel, Nirav K; Chughtai, Morad; Khlopas, Anton; Ramkumar, Prem N; Roche, Martin; Mont, Michael A

    2017-07-01

    Newer generation cementless total knee arthroplasty (TKA) designs are available and have novel implant coatings. We evaluated and compared beaded periapatite (PA)-coated vs highly porous titanium-coated cementless TKAs. Specifically, we compared: (1) survivorship, (2) Knee Society Scores (KSSs) and range of motion, (3) complications, and (4) radiographic findings. There were 805 TKAs with beaded PA-coated tibial and patellar components (PA group; mean age 67 years; range 41-86 years), and 219 TKAs with highly porous titanium-coated tibial and patella components (mean age 66 years; range 34-88 years). Mean follow-up was 4.4 years (range 2-9 years; median 4 years). Implant survivorship was calculated using Kaplan-Meier curves. Student t-tests and chi-square tests were used as appropriate. Radiographic evaluation was performed using Knee Society Roentgenographic Evaluation and Scoring System. All-cause implant survivorship in beaded PA-coated group was 99.5% (95% CI, 97.9%-99.9%) and 99.5% (95% CI, 92.7%-99.9%) in highly porous titanium-coated group. There were no significant differences in the KSS for pain and function. Improvement in flexion and extension was similar in the 2 groups. Overall, complication rate (2.2% vs 2.3%; P = .274) and number of revisions (6 [0.8%] vs 2 [0.2%]; P = .936) were similar in the 2 groups. Excluding the aseptic and septic failures, there were no progressive radiolucencies or osteolysis on radiographic evaluation. This study has shown good clinical and patient-reported outcomes of cementless TKA for both implants. Future multicenter large scale clinical and cost-effectiveness studies are needed to determine the superiority of one cementless implant type over the other. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. Porous, Dexamethasone-loaded polyurethane coatings extend performance window of implantable glucose sensors in vivo.

    PubMed

    Vallejo-Heligon, Suzana G; Brown, Nga L; Reichert, William M; Klitzman, Bruce

    2016-01-01

    Continuous glucose sensors offer the promise of tight glycemic control for insulin dependent diabetics; however, utilization of such systems has been hindered by issues of tissue compatibility. Here we report on the in vivo performance of implanted glucose sensors coated with Dexamethasone-loaded (Dex-loaded) porous coatings employed to mediate the tissue-sensor interface. Two animal studies were conducted to (1) characterize the tissue modifying effects of the porous Dex-loaded coatings deployed on sensor surrogate implants and (2) investigate the effects of the same coatings on the in vivo performance of Medtronic MiniMed SOF-SENSOR™ glucose sensors. The tissue response to implants was evaluated by quantifying macrophage infiltration, blood vessel formation, and collagen density around implants. Sensor function was assessed by measuring changes in sensor sensitivity and time lag, calculating the Mean Absolute Relative Difference (MARD) for each sensor treatment, and performing functional glucose challenge test at relevant time points. Implants treated with porous Dex-loaded coatings diminished inflammation and enhanced vascularization of the tissue surrounding the implants. Functional sensors with Dex-loaded porous coatings showed enhanced sensor sensitivity over a 21-day period when compared to controls. Enhanced sensor sensitivity was accompanied with an increase in sensor signal lag and MARD score. These results indicate that Dex-loaded porous coatings were able to elicit an attenuated tissue response, and that such tissue microenvironment could be conducive towards extending the performance window of glucose sensors in vivo. In the present article, a coating to extend the functionality of implantable glucose sensors in vivo was developed. Our study showed that the delivery of an anti-inflammatory agent with the presentation of micro-sized topographical cues from coatings may lead to improved long-term glucose sensor function in vivo. We believe that

  6. Impaction durability of porous polyether-ether-ketone (PEEK) and titanium-coated PEEK interbody fusion devices.

    PubMed

    Torstrick, F Brennan; Klosterhoff, Brett S; Westerlund, L Erik; Foley, Kevin T; Gochuico, Joanna; Lee, Christopher S D; Gall, Ken; Safranski, David L

    2018-05-01

    Various surface modifications, often incorporating roughened or porous surfaces, have recently been introduced to enhance osseointegration of interbody fusion devices. However, these topographical features can be vulnerable to damage during clinical impaction. Despite the potential negative impact of surface damage on clinical outcomes, current testing standards do not replicate clinically relevant impaction loading conditions. The purpose of this study was to compare the impaction durability of conventional smooth polyether-ether-ketone (PEEK) cervical interbody fusion devices with two surface-modified PEEK devices that feature either a porous structure or plasma-sprayed titanium coating. A recently developed biomechanical test method was adapted to simulate clinically relevant impaction loading conditions during cervical interbody fusion procedures. Three cervical interbody fusion devices were used in this study: smooth PEEK, plasma-sprayed titanium-coated PEEK, and porous PEEK (n=6). Following Kienle et al., devices were impacted between two polyurethane blocks mimicking vertebral bodies under a constant 200 N preload. The posterior tip of the device was placed at the entrance between the polyurethane blocks, and a guided 1-lb weight was impacted upon the anterior face with a maximum speed of 2.6 m/s to represent the strike force of a surgical mallet. Impacts were repeated until the device was fully impacted. Porous PEEK durability was assessed using micro-computed tomography (µCT) pre- and postimpaction. Titanium-coating coverage pre- and postimpaction was assessed using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy. Changes to the surface roughness of smooth and titanium-coated devices were also evaluated. Porous PEEK and smooth PEEK devices showed minimal macroscopic signs of surface damage, whereas the titanium-coated devices exhibited substantial visible coating loss. Quantification of the porous PEEK deformation

  7. Electrically conductive polymer concrete coatings

    DOEpatents

    Fontana, J.J.; Elling, D.; Reams, W.

    1988-05-26

    A sprayable electrically conductive polymer concrete coating for vertical and overhead applications is described. The coating is permeable yet has low electrical resistivity (<10 ohm-cm), good bond strength to concrete substrates, and good weatherability. A preferred formulation contains about 60 wt% calcined coke breeze, 40 wt% vinyl ester resin with 3.5 wt% modified bentonite clay. Such formulations apply evenly and provide enough rigidity for vertical or overhead structures so there is no drip or sag. 4 tabs.

  8. Electrically conductive polymer concrete coatings

    DOEpatents

    Fontana, J.J.; Elling, D.; Reams, W.

    1990-03-13

    A sprayable electrically conductive polymer concrete coating for vertical d overhead applications is described. The coating is permeable yet has low electrical resistivity (<10 ohm-cm), good bond strength to concrete substrates, and good weatherability. A preferred formulation contains about 60 wt % calcined coke breeze, 40 wt % vinyl ester with 3.5 wt % modified bentonite clay. Such formulations apply evenly and provide enough rigidity for vertical or overhead structures so there is no drip or sag.

  9. Electrically conductive polymer concrete coatings

    DOEpatents

    Fontana, Jack J.; Elling, David; Reams, Walter

    1990-01-01

    A sprayable electrically conductive polymer concrete coating for vertical d overhead applications is described. The coating is permeable yet has low electrical resistivity (<10 ohm-cm), good bond strength to concrete substrates, and good weatherability. A preferred formulation contains about 60 wt % calcined coke breeze, 40 wt % vinyl ester with 3.5 wt % modified bentonite clay. Such formulations apply evenly and provide enough rigidity for vertical or overhead structures so there is no drip or sag.

  10. Amorphous-amorphous transition in a porous coordination polymer.

    PubMed

    Ohtsu, Hiroyoshi; Bennett, Thomas D; Kojima, Tatsuhiro; Keen, David A; Niwa, Yasuhiro; Kawano, Masaki

    2017-07-04

    The amorphous state plays a key role in porous coordination polymer and metal-organic framework phase transitions. We investigate a crystalline-to-amorphous-to-amorphous-to-crystalline (CAAC) phase transition in a Zn based coordination polymer, by X-ray absorption fine structure (XAFS) and X-ray pair distribution function (PDF) analysis. We show that the system shows two distinct amorphous phases upon heating. The first involves a reversible transition to a desolvated form of the original network, followed by an irreversible transition to an intermediate phase which has elongated Zn-I bonds.

  11. Photonic porous silicon as a pH sensor.

    PubMed

    Pace, Stephanie; Vasani, Roshan B; Zhao, Wei; Perrier, Sébastien; Voelcker, Nicolas H

    2014-01-01

    Chronic wounds do not heal within 3 months, and during the lengthy healing process, the wound is invariably exposed to bacteria, which can colonize the wound bed and form biofilms. This alters the wound metabolism and brings about a change of pH. In this work, porous silicon photonic films were coated with the pH-responsive polymer poly(2-diethylaminoethyl acrylate). We demonstrated that the pH-responsive polymer deposited on the surface of the photonic film acts as a barrier to prevent water from penetrating inside the porous matrix at neutral pH. Moreover, the device demonstrated optical pH sensing capability visible by the unaided eye.

  12. Manufacturing a Porous Structure According to the Process Parameters of Functional 3D Porous Polymer Printing Technology Based on a Chemical Blowing Agent

    NASA Astrophysics Data System (ADS)

    Yoo, C. J.; Shin, B. S.; Kang, B. S.; Yun, D. H.; You, D. B.; Hong, S. M.

    2017-09-01

    In this paper, we propose a new porous polymer printing technology based on CBA(chemical blowing agent), and describe the optimization process according to the process parameters. By mixing polypropylene (PP) and CBA, a hybrid CBA filament was manufactured; the diameter of the filament ranged between 1.60 mm and 1.75 mm. A porous polymer structure was manufactured based on the traditional fused deposition modelling (FDM) method. The process parameters of the three-dimensional (3D) porous polymer printing (PPP) process included nozzle temperature, printing speed, and CBA density. Porosity increase with an increase in nozzle temperature and CBA density. On the contrary, porosity increase with a decrease in the printing speed. For porous structures, it has excellent mechanical properties. We manufactured a simple shape in 3D using 3D PPP technology. In the future, we will study the excellent mechanical properties of 3D PPP technology and apply them to various safety fields.

  13. Molecular Design for Preparation of Hexagonal-Ordered Porous Films Based on Side-chain Type Liquid-Crystalline Star Polymer.

    PubMed

    Naka, Yumiko; Takayama, Hiromu; Koyama, Teruhisa; Le, Khoa V; Sasaki, Takeo

    2018-05-02

    Fabrication of regularly porous films by the breath-figure method has attracted much attention. The simple, low-cost technique uses the condensation of water droplets to produce these structures, but the phenomenon itself is complex, requiring control over many interacting parameters that change throughout the process. Developing a unified understanding for the molecular design of polymers to prepare ordered porous films is challenging, but required for further advancements. In this article, the effects of the chemical structure of polymers in the breath-figure technique were systematically explored using side-chain type liquid-crystalline (LC) star polymers. The formation of porous films was affected by the structure of the polymers. Although the entire film surface of poly(11-[4-(4-cyanobiphenyl)oxy]undecyl methacrylate) (P11CB) had a hexagonal ordered porous structure over a certain Mn value, regularly arranged holes did not easily form in poly(methyl methacrylate) (PMMA), even though the main chain of PMMA is similar to that of P11CB. Comparing P11CB and poly(11-[(1,1'-biphenyl)-4-yloxy]undecyl methacrylate) (P11B) (P11CB without cyano groups) showed that the local polar groups in hydrophobic polymers promoted the formation of ordered porous films. No holes formed in poly(4-cyanobiphenyl methacrylate) (P0CB) (P11CB without alkyl spacers) films due to its hydrophilicity. The introduction of alkyl chains in P0CB allowed the preparation of honeycomb-structured films by increasing the internal tension. However, alkyl chains in the side chain alone did not result in a porous structure, as in the case of poly(11-[(1,1'-biphenyl)-4-yloxy]undecyl methacrylate) (P11). Aromatic rings are also required to increase the Tg and improve film formability. In the present study, suitable molecular designs of polymers were found, specifically hydrophobic polymers with local polar groups, to form a regularly porous structure. Development of clear guidelines for the molecular

  14. A Molecularly Imprinted Polymer (MIP)-Coated Microbeam MEMS Sensor for Chemical Detection

    DTIC Science & Technology

    2015-09-01

    ARL-RP-0536 ● SEP 2015 US Army Research Laboratory A Molecularly Imprinted Polymer (MIP)- Coated Microbeam MEMS Sensor for...ARL-RP-0536 ● SEP 2015 US Army Research Laboratory A Molecularly Imprinted Polymer (MIP)- Coated Microbeam MEMS Sensor for Chemical...TITLE AND SUBTITLE A Molecularly Imprinted Polymer (MIP)-Coated Microbeam MEMS Sensor for Chemical Detection 5a. CONTRACT NUMBER 5b. GRANT NUMBER

  15. Polymer network/carbon layer on monolith support and monolith catalytic reactor

    DOEpatents

    Nordquist, Andrew Francis; Wilhelm, Frederick Carl; Waller, Francis Joseph; Machado, Reinaldo Mario

    2003-08-26

    The present invention relates to an improved monolith catalytic reactor and a monolith support. The improvement in the support resides in a polymer network/carbon coating applied to the surface of a porous substrate and a catalytic metal, preferably a transition metal catalyst applied to the surface of the polymer network/carbon coating. The monolith support has from 100 to 800 cells per square inch and a polymer network/carbon coating with surface area of from 0.1 to 15 m.sup.2 /gram as measured by adsorption of N.sub.2 or Kr using the BET method.

  16. Boron hydride polymer coated substrates

    DOEpatents

    Pearson, R.K.; Bystroff, R.I.; Miller, D.E.

    1986-08-27

    A method is disclosed for coating a substrate with a uniformly smooth layer of a boron hydride polymer. The method comprises providing a reaction chamber which contains the substrate and the boron hydride plasma. A boron hydride feed stock is introduced into the chamber simultaneously with the generation of a plasma discharge within the chamber. A boron hydride plasma of ions, electrons and free radicals which is generated by the plasma discharge interacts to form a uniformly smooth boron hydride polymer which is deposited on the substrate.

  17. Boron hydride polymer coated substrates

    DOEpatents

    Pearson, Richard K.; Bystroff, Roman I.; Miller, Dale E.

    1987-01-01

    A method is disclosed for coating a substrate with a uniformly smooth layer of a boron hydride polymer. The method comprises providing a reaction chamber which contains the substrate and the boron hydride plasma. A boron hydride feed stock is introduced into the chamber simultaneously with the generation of a plasma discharge within the chamber. A boron hydride plasma of ions, electrons and free radicals which is generated by the plasma discharge interacts to form a uniformly smooth boron hydride polymer which is deposited on the substrate.

  18. Utilization of star-shaped polymer architecture in the creation of high-density polymer brush coatings for the prevention of platelet and bacteria adhesion

    PubMed Central

    Totani, Masayasu; Terada, Kayo; Terashima, Takaya; Kim, Ill Yong; Ohtsuki, Chikara; Xi, Chuanwu; Tanihara, Masao

    2014-01-01

    We demonstrate utilization of star-shaped polymers as high-density polymer brush coatings and their effectiveness to inhibit the adhesion of platelets and bacteria. Star polymers consisting of poly(2-hydroxyethyl methacrylate) (PHEMA) and/or poly(methyl methacrylate) (PMMA), were synthesized using living radical polymerization with a ruthenium catalyst. The polymer coatings were prepared by simple drop casting of the polymer solution onto poly(ethylene terephthalate) (PET) surfaces and then dried. Among the star polymers prepared in this study, the PHEMA star polymer (star-PHEMA) and the PHEMA/PMMA (mol. ratio of 71/29) heteroarm star polymer (star-H71M29) coatings showed the highest percentage of inhibition against platelet adhesion (78–88% relative to noncoated PET surface) and Escherichia coli (94–97%). These coatings also showed anti-adhesion activity against platelets after incubation in Dulbecco's phosphate buffered saline or surfactant solution for 7 days. In addition, the PMMA component of the star polymers increased the scratch resistance of the coating. These results indicate that the star-polymer architecture provides high polymer chain density on PET surfaces to prevent adhesion of platelets and bacteria, as well as coating stability and physical durability to prevent exposure of bare PET surfaces. The star polymers provide a simple and effective approach to preparing anti-adhesion polymer coatings on biomedical materials against the adhesion of platelets and bacteria. PMID:25485105

  19. Tailored nanoporous coatings fabricated on conformable polymer substrates.

    PubMed

    Poxson, David J; Mont, Frank W; Cho, Jaehee; Schubert, E Fred; Siegel, Richard W

    2012-11-01

    Nanoporous coatings have become the subject of intense investigation, in part because they have been shown to have unique and tailorable physical properties that can depart greatly from their dense or macroscopic counterparts. Nanoporous coatings are frequently fabricated utilizing oblique-angle or glancing-angle physical vapor-phase deposition techniques. However, a significant limitation for such coatings exists; they are almost always deposited on smooth and rigid planar substrates, such as silicon and glass. This limitation greatly constrains the applicability, tailorability, functionality and even the economic viability, of such nanoporous coatings. Here, we report our findings on nanoporous/polymer composite systems (NPCS) fabricated by utilizing oblique-angle electron-beam methodology. These unique composite systems exhibit several favorable characteristics, namely, (i) fine-tuned control over coating nanoporosity and thickness, (ii) excellent adhesion between the nanoporous coating and polymer substrate, (iii) the ability to withstand significant and repeated bending, and (iv) the ability to be molded conformably on two and three-dimensional surfaces while closely retaining the composite system's designed nanoporous film structure and, hence, properties.

  20. Polymer Coatings Reduce Electro-osmosis

    NASA Technical Reports Server (NTRS)

    Herren, Blair J.; Snyder, Robert; Shafer, Steven G.; Harris, J. Milton; Van Alstine, James M.

    1989-01-01

    Poly(ethylene glycol) film controls electrostatic potential. Electro-osmosis in quartz or glass chambers reduced or reversed by coating inside surface of chambers with monomacromolecular layers of poly(ethylene glycol). Stable over long times. Electrostatic potential across surface of untreated glass or plastic chamber used in electro-phoresis is negative and attracts cations in aqueous electrolyte. Cations solvated, entrains flow of electrolyte migrating toward cathode. Electro-osmotic flow interferes with desired electrophoresis of particles suspended in electrolyte. Polymer coats nontoxic, transparent, and neutral, advantageous for use in electrophoresis.

  1. Photonic porous silicon as a pH sensor

    PubMed Central

    2014-01-01

    Chronic wounds do not heal within 3 months, and during the lengthy healing process, the wound is invariably exposed to bacteria, which can colonize the wound bed and form biofilms. This alters the wound metabolism and brings about a change of pH. In this work, porous silicon photonic films were coated with the pH-responsive polymer poly(2-diethylaminoethyl acrylate). We demonstrated that the pH-responsive polymer deposited on the surface of the photonic film acts as a barrier to prevent water from penetrating inside the porous matrix at neutral pH. Moreover, the device demonstrated optical pH sensing capability visible by the unaided eye. PMID:25177227

  2. Progress in the Development of SERS-Active Substrates Based on Metal-Coated Porous Silicon

    PubMed Central

    Girel, Kseniya V.; Panarin, Andrei; Terekhov, Sergei N.

    2018-01-01

    The present work gives an overview of the developments in surface-enhanced Raman scattering (SERS) with metal-coated porous silicon used as an active substrate. We focused this review on the research referenced to SERS-active materials based on porous silicon, beginning from the patent application in 2002 and enclosing the studies of this year. Porous silicon and metal deposition technologies are discussed. Since the earliest studies, a number of fundamentally different plasmonic nanostructures including metallic dendrites, quasi-ordered arrays of metallic nanoparticles (NPs), and metallic nanovoids have been grown on porous silicon, defined by the morphology of this host material. SERS-active substrates based on porous silicon have been found to combine a high and well-reproducible signal level, storage stability, cost-effective technology and handy use. They make it possible to identify and study many compounds including biomolecules with a detection limit varying from milli- to femtomolar concentrations. The progress reviewed here demonstrates the great prospects for the extensive use of the metal-coated porous silicon for bioanalysis by SERS-spectroscopy. PMID:29883382

  3. Progress in the Development of SERS-Active Substrates Based on Metal-Coated Porous Silicon.

    PubMed

    Bandarenka, Hanna V; Girel, Kseniya V; Zavatski, Sergey A; Panarin, Andrei; Terekhov, Sergei N

    2018-05-21

    The present work gives an overview of the developments in surface-enhanced Raman scattering (SERS) with metal-coated porous silicon used as an active substrate. We focused this review on the research referenced to SERS-active materials based on porous silicon, beginning from the patent application in 2002 and enclosing the studies of this year. Porous silicon and metal deposition technologies are discussed. Since the earliest studies, a number of fundamentally different plasmonic nanostructures including metallic dendrites, quasi-ordered arrays of metallic nanoparticles (NPs), and metallic nanovoids have been grown on porous silicon, defined by the morphology of this host material. SERS-active substrates based on porous silicon have been found to combine a high and well-reproducible signal level, storage stability, cost-effective technology and handy use. They make it possible to identify and study many compounds including biomolecules with a detection limit varying from milli- to femtomolar concentrations. The progress reviewed here demonstrates the great prospects for the extensive use of the metal-coated porous silicon for bioanalysis by SERS-spectroscopy.

  4. Current State of Bioabsorbable Polymer-Coated Drug-Eluting Stents

    PubMed Central

    Akinapelli, Abhilash; Chen, Jack P.; Roy, Kristine; Donnelly, Joseph; Dawkins, Keith; Huibregtse, Barbara; Hou, Dongming

    2017-01-01

    Drug-eluting stents (DES) have been shown to significantly reduce clinical and angiograph-ic restenosis compared to bare metal stents (BMS). The polymer coatings on DES elute antiproliferative drugs to inhibit intimal proliferation and prevent restenosis after stent implantation. Permanent poly-mers which do not degrade in vivo may increase the likelihood of stent-related delayed arterial healing or polymer hypersensitivity. In turn, these limitations may contribute to an increased risk of late clinical events. Intuitively, a polymer which degrades after completion of drug release, leaving an inert metal scaffold in place, may improve arterial healing by removing a chronic source of inflammation, neoath-erosclerosis, and/or late thrombosis. In this way, a biodegradable polymer may reduce late ischemic events. Additionally, improved healing after stent implantation could reduce the requirement for long-term dual antiplatelet therapy and the associated risk of bleeding and cost. This review will focus on bioabsorbable polymer-coated DES currently being evaluated in clinical trials.

  5. Controllable growth of porous structures from co-continuous polymer blend

    NASA Astrophysics Data System (ADS)

    Zhang, Wei

    To enable controllable generation of porous structures, a set of new fabrication techniques utilizing the annealing kinetics of co-continuous polymer blends were proposed and investigated. As the first step towards the creation of an organized porous material, a new technique based on regulating the thermal boundary conditions to controllably grow gradient porous structures was developed. In this technique, specially designed thermal boundaries were used to generate a well-defined temperature field inside a co-continuous polymer blend with fine phase structure. Because of the temperature dependency of zero-shear viscosity and its influence on phase coarsening rate, a graded phase size distribution was generated by this temperature field. After one component was selectively dissolved, a gradient porous structure was produced. To demonstrate the versatility of this technique, three different gradient porous structures were created. After the effectiveness of thermal boundary condition in developing organized porous materials was verified, the possibility of utilizing kinematic and dynamic boundary conditions to obtain extra controllability was investigated. Two types of kinematic boundary conditions, no-slip wall and 1D hard wall confinement were tested separately. It was found that no-slip wall could greatly slow down the phase coarsening rate of the nearby polymer blend. When a no-slip wall and a fully slip wall were applied at each side of a molten co-continuous blend, a pore size gradient was generated in the direction perpendicular to the wall surface with smaller pores near the no-slip wall. One directional hard wall confinement formed by a pair of fully slip parallel walls led to the formation of an aligned phase structure oriented in the vertical direction to the walls. Experiments regarding the effect of dynamic boundary condition were conducted by imposing different chemical potentials at the surface of molten blend. Fully dense surface and completely open

  6. Cyclic voltammetry study of PEO processing of porous Ti and resulting coatings

    NASA Astrophysics Data System (ADS)

    Shbeh, Mohammed; Yerokhin, Aleksey; Goodall, Russell

    2018-05-01

    Ti is one of the most commonly used materials for biomedical applications. However, there are two issues associated with the use of it, namely its bio-inertness and high elastic modulus compared to the elastic modulus of the natural bone. Both of these hurdles could potentially be overcome by introducing a number of pores in the structure of the Ti implant to match the properties of the bone as well as improve the mechanical integration between the bone and implant, and subsequently coating it with a biologically active ceramic coating to promote chemical integration. Hence, in this study we investigated the usage of cyclic voltammetry in PEO treatment of porous Ti parts with different amount of porosity produced by both Metal Injection Moulding (MIM) and MIM in combination with a space holder. It was found that porous samples with higher porosity and open pores develop much thicker surface layers that penetrate through the inner structure of the samples forming a network of surface and subsurface coatings. The results are of potential benefit in producing surface engineered porous samples for biomedical applications which do not only address the stress shielding problem, but also improve the chemical integration.

  7. Aqueous Polymer Dispersion Coating Used for Osmotic Pump Tablets: Membrane Property Investigation and IVIVC Evaluation.

    PubMed

    Cheng, Lizhen; Gai, Xiumei; Wen, Haoyang; Liu, Dandan; Tang, Xin; Wang, Yanyan; Wang, Tuanjie; Pan, Weisan; Yang, Xinggang

    2018-01-01

    The objective of this study was to investigate the fundamental properties of propranolol hydrochloride osmotic pump tablets coated by aqueous polymer dispersion, simultaneously exploring the in vitro and in vivo correlation of the tablet. The physicochemical properties and parameters of aqueous polymer dispersion membranes (SEM, water uptake, and water vapor transmission coefficient) were investigated. In addition, the release behavior and the in vitro release and in vivo absorption profiles of the tablets coated by aqueous polymer dispersion were investigated by comparing with propranolol hydrochloride osmotic pump tablets coated by an organic solvent. Results showed that the similarity factor (f 2 ) between cellulose acetate-coated tablet and Eudragit-coated tablet was 78.1, and f 2 between cellulose acetate-coated tablet and Kollicoat-coated tablet was 77.6. The linear IVIVC of Eudragit-coated and Kollicoat-coated osmotic pump tablets was determined, which confirmed excellent correlation between the absorption in vivo and the drug release in vitro. Consequently, the membrane coated by aqueous polymer dispersion or organic solvent has similar in vitro release rates of controlled release. Also, compared with organic solvent coating, aqueous polymer dispersion has numerous advantages, such as reduced toxicity and no environmental damage. Therefore, the aqueous polymer dispersion technology has enormous potential as a replacement of organic solvent coating.

  8. Protection of moisture-sensitive drugs with aqueous polymer coatings: importance of coating and curing conditions.

    PubMed

    Bley, O; Siepmann, J; Bodmeier, R

    2009-08-13

    The aim of this study was to better understand the importance of coating and curing conditions of moisture-protective polymer coatings. Tablets containing freeze-dried garlic powder were coated with aqueous solutions/dispersions of hydroxypropyl methylcellulose (HPMC), poly(vinyl alcohol), ethyl cellulose and poly(methacrylate-methylmethacrylates). The water content of the tablets during coating and during storage at different temperatures and relative humidities (RH) was determined gravimetrically. In addition, changes in the allicin (active ingredient in garlic powder) content were monitored. During the coating process, the water uptake was below 2.7% and no drug degradation was detectable. Thermally induced drug degradation occurred only at temperatures above the coating temperatures. Different polymer coatings effectively decreased the rate, but not the extent of water uptake during open storage at room temperature and 75% RH. Tablets coated with poly(vinyl alcohol) and poly(methacrylate-methylmethacrylates) showed the lowest moisture uptake rates (0.49 and 0.57%/d, respectively). Curing at elevated temperature after coating did not improve the moisture-protective ability of the polymeric films, but reduced the water content of the tablets. Drug stability was significantly improved with tablets coated with poly(vinyl alcohol) and poly(methacrylate-methylmethacrylates).

  9. Anti-icing Behavior of Thermally Sprayed Polymer Coatings

    NASA Astrophysics Data System (ADS)

    Koivuluoto, Heli; Stenroos, Christian; Kylmälahti, Mikko; Apostol, Marian; Kiilakoski, Jarkko; Vuoristo, Petri

    2017-01-01

    Surface engineering shows an increasing potential to provide a sustainable approach to icing problems. Currently, several passive anti-ice properties adoptable to coatings are known, but further research is required to proceed for practical applications. This is due to the fact that icing reduces safety, operational tempo, productivity and reliability of logistics, industry and infrastructure. An icing wind tunnel and a centrifugal ice adhesion test equipment can be used to evaluate and develop anti-icing and icephobic coatings for a potential use in various arctic environments, e.g., in wind power generation, oil drilling, mining and logistic industries. The present study deals with evaluation of icing properties of flame-sprayed polyethylene (PE)-based polymer coatings. In the laboratory-scale icing tests, thermally sprayed polymer coatings showed low ice adhesion compared with metals such as aluminum and stainless steel. The ice adhesion strength of the flame-sprayed PE coating was found to have approximately seven times lower ice adhesion values compared with metallic aluminum, indicating a very promising anti-icing behavior.

  10. Positron lifetime spectroscopy for investigation of thin polymer coatings

    NASA Technical Reports Server (NTRS)

    Singh, Jag J.; Sprinkle, Danny R.; Eftekhari, Abe

    1993-01-01

    In the aerospace industry, applications for polymer coatings are increasing. They are now used for thermal control on aerospace structures and for protective insulating layers on optical and microelectronic components. However, the effectiveness of polymer coatings depends strongly on their microstructure and adhesion to the substrates. Currently, no technique exists to adequately monitor the quality of these coatings. We have adapted positron lifetime spectroscopy to investigate the quality of thin coatings. Results of measurements on thin (25-micron) polyurethane coatings on aluminum and steel substrates have been compared with measurements on thicker (0.2-cm) self-standing polyurethane discs. In all cases, we find positron lifetime groups centered around 560 psec, which corresponds to the presence of 0.9-A(exp 3) free-volume cells. However, the number of these free-volume cells in thin coatings is larger than in thick discs. This suggests that some of these cells may be located in the interfacial regions between the coatings and the substrates. These results and their structural implications are discussed in this report.

  11. Water repellent porous silica films by sol-gel dip coating method.

    PubMed

    Rao, A Venkateswara; Gurav, Annaso B; Latthe, Sanjay S; Vhatkar, Rajiv S; Imai, Hiroaki; Kappenstein, Charles; Wagh, P B; Gupta, Satish C

    2010-12-01

    The wetting of solid surfaces by water droplets is ubiquitous in our daily lives as well as in industrial processes. In the present research work, water repellent porous silica films are prepared on glass substrate at room temperature by sol-gel process. The coating sol was prepared by keeping the molar ratio of methyltriethoxysilane (MTES), methanol (MeOH), water (H(2)O) constant at 1:12.90:4.74, respectively, with 2M NH(4)OH throughout the experiments and the molar ratio (M) of MTES/Ph-TMS was varied from 0 to 0.22. A simple dip coating technique is adopted to coat silica films on the glass substrates. The static water contact angle as high as 164° and water sliding angle as low as 4° was obtained for silica film prepared from M=0.22. The surface morphological studies of the prepared silica film showed the porous structure with pore sizes typically ranging from 200nm to 1.3μm. The superhydrophobic silica films prepared from M=0.22 retained their superhydrophobicity up to a temperature of 285°C and above this temperature the films became superhydrophilic. The porous and water repellent silica films are prepared by proper alteration of the Ph-TMS in the coating solution. The prepared silica films were characterized by surface profilometer, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier Transform Infrared (FT-IR) spectroscopy, humidity tests, chemical aging tests, static and dynamic water contact angle measurements. Copyright © 2010 Elsevier Inc. All rights reserved.

  12. Metal/fiber laminate and fabrication using a porous metal/fiber preform

    NASA Technical Reports Server (NTRS)

    Hales, Stephen J. (Inventor); Alexa, Joel A. (Inventor); Jensen, Brian J. (Inventor); Cano, Roberto J. (Inventor); Weiser, Erik S. (Inventor)

    2011-01-01

    A metal/fiber laminate has a plurality of adjacent layers. Each layer is porous and includes an arrangement of fibers. At least one of the layers has its fibers coated with a metal. A polymer matrix permeates each such arrangement.

  13. Metal/fiber laminate and fabrication using a porous metal/fiber preform

    NASA Technical Reports Server (NTRS)

    Hales, Stephen J. (Inventor); Alexa, Joel A. (Inventor); Jensen, Brian J. (Inventor); Cano, Roberto J. (Inventor); Weiser, Erik S. (Inventor)

    2010-01-01

    A metal/fiber laminate has a plurality of adjacent layers. Each layer is porous and includes an arrangement of fibers. At least one of the layers has its fibers coated with a metal. A polymer matrix permeates each such arrangement.

  14. Pseudoephedrine hydrochloride sustained-release pellets prepared by a combination of hot-melt subcoating and polymer coating.

    PubMed

    Yang, Zi Yi; Lu, Yan; Tang, Xing

    2008-12-01

    Pseudoephedrine hydrochloride is an active very highly water soluble substance. In order to control release of a drug with this property, we developed the application of a combination of hot-melt subcoating and polymer coating was developed. The main objective was to investigate the influence of this combination on the release of highly water soluble drug and how it works. Hot-melt subcoating was achieved by using a coating pan. Subsequently, the outer polymer coating was prepared by fluidized bed, and the drug release was determined by high-performance liquid chromatograph (HPLC) method. Hot-melt subcoating can form a barrier between the drug-loaded pellets and the polymer coating layer, which prevents migration of the drug during film application. Consequently, the level of polymer coating can be reduced significantly, and the effectiveness of the polymer coating increased. In this study, the release profile of pellets with a 10% hot-melt subcoating and 5% polymer coating weight gain met the dissolution requirement of USP29 for pseudoephedrine hydrochloride extended-release capsules. Compared with pellets only polymer coated (10% level), the polymer coating level of pellets prepared by this technology was reduced by half due to hot-melt subcoating. By means of this hot-melt subcoating and polymer coating, sustained-release pellets containing pseudoephedrine hydrochloride were successfully prepared.

  15. Highly aligned porous Ti scaffold coated with bone morphogenetic protein-loaded silica/chitosan hybrid for enhanced bone regeneration.

    PubMed

    Jung, Hyun-Do; Yook, Se-Won; Han, Cheol-Min; Jang, Tae-Sik; Kim, Hyoun-Ee; Koh, Young-Hag; Estrin, Yuri

    2014-07-01

    Porous Ti has been widely investigated for orthopedic and dental applications on account of their ability to promote implant fixation via bone ingrowth into pores. In this study, highly aligned porous Ti scaffolds coated with a bone morphogenetic protein (BMP)-loaded silica/chitosan hybrid were produced, and their bone regeneration ability was evaluated by in vivo animal experiments. Reverse freeze casting allowed for the creation of highly aligned pores, resulting in a high compressive strength of 254 ± 21 MPa of the scaffolds at a porosity level of ∼51 vol %. In addition, a BMP-loaded silica/chitosan hybrid coating layer with a thickness of ∼1 μm was uniformly deposited on the porous Ti scaffold, which enabled the sustained release of the BMP over a prolonged period of time up to 26 days. The cumulative amount of the BMP released was ∼4 μg, which was much higher than that released from the specimen without a hybrid coating layer. In addition, the bone regeneration ability of the porous Ti scaffold with a BMP-loaded silica/chitosan coating layer was examined by in vivo animal testing using a rabbit calvarial defect model and compared with those of the as-produced porous Ti scaffold and porous Ti scaffold with a silica/chitosan coating layer. After 4 weeks of healing, the specimen coated with a BMP-loaded silica/chitosan hybrid showed a much higher bone regeneration volume (∼36%) than the as-produced specimen (∼15%) (p < 0.005) and even the specimen coated with a silica/chitosan hybrid (∼25%) (p < 0.05). © 2013 Wiley Periodicals, Inc.

  16. Positron lifetime spectroscopy in thin polymer coatings

    NASA Technical Reports Server (NTRS)

    Singh, Jag J.; Eftekhari, Abe; Sprinkle, Danny R.

    1990-01-01

    Polymer coatings are finding increasing applications in aerospace industry. The effectiveness of coatings depends strongly on their microstructure and adhesion to the substrates. Currently, there is no technique for adequately monitoring the quality of the coatings. We adapted positron lifetime spectroscopy for the investigation of thin coatings. Results of measurements on 0.001-in-thick polyurethane coatings on aluminum and steel substrates and thicker (0.080-in.) self-standing polyurethane discs were compared. In all cases, we find positron lifetime groups centered around 560 ps, corresponding to the presence of 0.9 A exp 3 free volume cells. However, the number of free volume cells in thin coatings is larger, suggesting that the morphology of thin coatings is different from that of bulk polyurethane. These results and their structural implications are discussed.

  17. Cell-Culture Reactor Having a Porous Organic Polymer Membrane

    NASA Technical Reports Server (NTRS)

    Koontz, Steven L. (Inventor)

    2000-01-01

    A method for making a biocompatible polymer article using a uniform atomic oxygen treatment is disclosed. The substrate may be subsequently optionally grated with a compatibilizing compound. Compatibilizing compounds may include proteins, phosphory1choline groups, platelet adhesion preventing polymers, albumin adhesion promoters, and the like. The compatibilized substrate may also have a living cell layer adhered thereto. The atomic oxygen is preferably produced by a flowing afterglow microwave discharge, wherein the substrate resides in a sidearm out of the plasma. Also, methods for culturing cells for various purposes using the various membranes are disclosed as well. Also disclosed are porous organic polymers having a distributed pore chemistry (DPC) comprising hydrophilic and hydrophobic regions, and a method for making the DPC by exposing the polymer to atomic oxygen wherein the rate of hydrophilization is greater than the rate of mass loss.

  18. Comparison of Selective Laser Melted Titanium and Magnesium Implants Coated with PCL

    PubMed Central

    Matena, Julia; Petersen, Svea; Gieseke, Matthias; Teske, Michael; Beyerbach, Martin; Kampmann, Andreas; Escobar, Hugo Murua; Gellrich, Nils-Claudius; Haferkamp, Heinz; Nolte, Ingo

    2015-01-01

    Degradable implant material for bone remodeling that corresponds to the physiological stability of bone has still not been developed. Promising degradable materials with good mechanical properties are magnesium and magnesium alloys. However, excessive gas production due to corrosion can lower the biocompatibility. In the present study we used the polymer coating polycaprolactone (PCL), intended to lower the corrosion rate of magnesium. Additionally, improvement of implant geometry can increase bone remodeling. Porous structures are known to support vessel ingrowth and thus increase osseointegration. With the selective laser melting (SLM) process, defined open porous structures can be created. Recently, highly reactive magnesium has also been processed by SLM. We performed studies with a flat magnesium layer and with porous magnesium implants coated with polymers. The SLM produced magnesium was compared with the titanium alloy TiAl6V4, as titanium is already established for the SLM-process. For testing the biocompatibility, we used primary murine osteoblasts. Results showed a reduced corrosion rate and good biocompatibility of the SLM produced magnesium with PCL coating. PMID:26068455

  19. Three-dimensional iron(ii) porous coordination polymer exhibiting carbon dioxide-dependent spin crossover.

    PubMed

    Shin, Jong Won; Jeong, Ah Rim; Jeoung, Sungeun; Moon, Hoi Ri; Komatsumaru, Yuki; Hayami, Shinya; Moon, Dohyun; Min, Kil Sik

    2018-04-24

    We report a three-dimensional Fe(ii) porous coordination polymer that exhibits a spin crossover temperature change following CO2 sorption (though not N2 sorption). Furthermore, single crystals of the desolvated polymer with CO2 molecules at three different temperatures were characterised by X-ray crystallography.

  20. Uniform Deposition of Protein Incorporated Mineral Layer on Three-Dimensional Porous Polymer Scaffolds

    PubMed Central

    Segvich, Sharon; Smith, Hayes C.; Luong, Linh N.; Kohn, David H.

    2009-01-01

    Inorganic–organic hybrid materials designed to facilitate bone tissue regeneration use a calcium phosphate mineral layer to encourage cell adhesion, proliferation, and osteogenic differentiation. Mineral formed on porous materials is often discontinuous through the thickness of the scaffold. This study aimed to uniformly coat the pores of three-dimensional (3D) porous, polymer scaffolds with a bone-like mineral layer in addition to uniformly incorporating a model protein within this mineral layer. A filtration system designed to induce simulated body fluid flow through the interstices of 3D polylactic-co-glycolic acid scaffolds (10-mm diameter × 2-mm thickness) illustrated that a uniform, continuous mineral layer can be precipitated on the pore surfaces of a 3D porous structure within 5 days. MicroCT analysis showed increased mineral volume percent (MV%) (7.86 ± 3.25 MV%, p = 0.029) and continuous mineralization of filtered scaffolds compared with two static control groups (floating, 0.16 ± 0.26 MV% and submerged, 0.20 ± 0.01 MV%). Furthermore, the system was effective in coprecipitating a model protein, bone sialoprotein (BSA), within the mineral layer. A 10-fold increase in BSA incorporation was seen when coprecipitated filtered scaffolds (1308 ± 464 μg) were compared to a submerged static control group (139 ± 45 μg), p < 0.001. Confocal microscopy visually confirmed uniform coprecipitation of BSA throughout the thickness of the filtration scaffolds. The designed system enables 3D mineralization through the thickness of porous materials, and provides the option of including coprecipitated biomolecular cues within the mineral layer. This approach of providing a 3D conductive and osteoinductive environment could be conducive to bone tissue regeneration. PMID:17618505

  1. Biomimetic Coating on Porous Alumina for Tissue Engineering: Characterisation by Cell Culture and Confocal Microscopy

    PubMed Central

    Kolos, Elizabeth; Ruys, Andrew J

    2015-01-01

    In this study porous alumina samples were prepared and then coated using the biomimetic coating technique using a five times Simulated Body Fluid (5.0SBF) as the growth solution. A coating was achieved after pre-treatment with concentrated acid. From elemental analysis, the coating contained calcium and phosphorous, but also sodium and chlorine. Halite was identified by XRD, a sodium chloride phase. Sintering was done to remove the halite phase. Once halite was burnt off, the calcium phosphate crystals were not covered with halite and, therefore, the apatite phases can be clearly observed. Cell culturing showed sufficient cell attachment to the less porous alumina, Sample B, that has more calcium phosphate growth, while the porous alumina, Sample A, with minimal calcium phosphate growth attained very little cell attachment. This is likely due to the contribution that calcium phosphate plays in the attachment of bone-like cells to a bioinert ceramic such as alumina. These results were repeated on both SEM and confocal microscopy analysis. Confocal microscopy was a novel characterisation approach which gave useful information and was a visual aid.

  2. Surface biofunctionalization of three-dimensional porous poly(lactic acid) scaffold using chitosan/OGP coating for bone tissue engineering.

    PubMed

    Zeng, Sen; Ye, Jianhua; Cui, Zhixiang; Si, Junhui; Wang, Qianting; Wang, Xiaofeng; Peng, Kaiping; Chen, Wenzhe

    2017-08-01

    As one of the stimulators on bone formation, osteogenic growth peptide (OGP) improves both proliferation and differentiation of the bone cells in vitro and in vivo. The aim of this work was the preparation of three dimensional porous poly(lactic acid) (PLA) scaffold with high porosity from PLA-dioxane-water ternary system with the use of vacuum-assisted solvent casting, phase separation, solvent extraction and particle leaching methods. Then, by surface coating of PLA scaffold with chitosan (CS)/OGP solution, biofunctionalization of PLA scaffold had been completed for application in bone regeneration. The effects of frozen temperature (-20, -50, -80°C) and PLA solution concentration (10, 12, 14wt%) on the microstructure, water absorption, porosity, hydrophilicity, mechanical properties, and biocompatibility of PLA and CS/OGP/PLA scaffold were investigated. Results showed that both PLA and CS/OGP/PLA scaffolds have an interconnected network structure and a porosity of up to 96.1% and 91.5%, respectively. The CS/OGP/PLA scaffold exhibited better hydrophilicity and mechanical properties than that of uncoated PLA scaffold. Moreover, the results of cell culture test showed that CS/OGP coating could stimulate the proliferation and growth of osteoblast cells on CS/OGP/PLA scaffold. These finding suggested that the surface biofunctionalization by CS/OGP coating layer could be an effective method on enhancing cell adhesion to synthetic polymer-based scaffolds in tissue engineering application and the developed porous CS/OGP/PLA scaffold should be considered as alternative biomaterials for bone regeneration. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Polydopamine--a nature-inspired polymer coating for biomedical science.

    PubMed

    Lynge, Martin E; van der Westen, Rebecca; Postma, Almar; Städler, Brigitte

    2011-12-01

    Polymer coatings are of central importance for many biomedical applications. In the past few years, poly(dopamine) (PDA) has attracted considerable interest for various types of biomedical applications. This feature article outlines the basic chemistry and material science regarding PDA and discusses its successful application from coatings for interfacing with cells, to drug delivery and biosensing. Although many questions remain open, the primary aim of this feature article is to illustrate the advent of PDA on its way to become a popular polymer for bioengineering purposes.

  4. Nanocarbon-Coated Porous Anodic Alumina for Bionic Devices

    PubMed Central

    Aramesh, Morteza; Tong, Wei; Fox, Kate; Turnley, Ann; Seo, Dong Han; Prawer, Steven; Ostrikov, Kostya (Ken)

    2015-01-01

    A highly-stable and biocompatible nanoporous electrode is demonstrated herein. The electrode is based on a porous anodic alumina which is conformally coated with an ultra-thin layer of diamond-like carbon. The nanocarbon coating plays an essential role for the chemical stability and biocompatibility of the electrodes; thus, the coated electrodes are ideally suited for biomedical applications. The corrosion resistance of the proposed electrodes was tested under extreme chemical conditions, such as in boiling acidic/alkali environments. The nanostructured morphology and the surface chemistry of the electrodes were maintained after wet/dry chemical corrosion tests. The non-cytotoxicity of the electrodes was tested by standard toxicity tests using mouse fibroblasts and cortical neurons. Furthermore, the cell–electrode interaction of cortical neurons with nanocarbon coated nanoporous anodic alumina was studied in vitro. Cortical neurons were found to attach and spread to the nanocarbon coated electrodes without using additional biomolecules, whilst no cell attachment was observed on the surface of the bare anodic alumina. Neurite growth appeared to be sensitive to nanotopographical features of the electrodes. The proposed electrodes show a great promise for practical applications such as retinal prostheses and bionic implants in general. PMID:28793486

  5. A study on porous super austenitic stainless steel coating for improvement of bone ingrowth

    NASA Astrophysics Data System (ADS)

    Oh, Keun Taek; Park, Yong Soo

    1998-02-01

    In this study, the prostheses were provided with the bone ingrowth site by coating the super stainless steel powder on the same substrate (S32050) using plasma spraying method. Plasma current and powder feed rate varied in this study based on the optimum conditions of previous experiments. The optimum conditions for satisfying the requirements of the porous coatings were found. The characteristics of the coatings were observed according to the experimental parameters. It was found that plasma current influenced the chemical composition (the oxides, Cr component), melting and flattening degree of the sprayed particle (surface roughness, thickness of the splat, pores) and corrosion -resistance. The powder feed rate also influenced the coating thickness and efficiency. The amount of Cr was increased, but Ni, Mo, Fe were decreased with plasma current. An increase of Cr in the coating surface corresponded to an increase in the amount of the formed oxides. The coated specimen in 400A had a high corrosion-resistance owing to a dense coating. The coated specimen in 500A formed many types of oxides. In 300A current, the coating was rough with many pores, and corrosion-resistance of the coating showed a large variation according to the oxidation and compositional change. Specifically at 100 g/min powder feed rate in a 300A current, the coating was rough and porous, nevertheless, it had high corrosion resistance.

  6. Mechanistic modelling of drug release from polymer-coated and swelling and dissolving polymer matrix systems.

    PubMed

    Kaunisto, Erik; Marucci, Mariagrazia; Borgquist, Per; Axelsson, Anders

    2011-10-10

    The time required for the design of a new delivery device can be sensibly reduced if the release mechanism is understood and an appropriate mathematical model is used to characterize the system. Once all the model parameters are obtained, in silico experiments can be performed, to provide estimates of the release from devices with different geometries and compositions. In this review coated and matrix systems are considered. For coated formulations, models describing the diffusional drug release, the osmotic pumping drug release, and the lag phase of pellets undergoing cracking in the coating due to the build-up of a hydrostatic pressure are reviewed. For matrix systems, models describing pure polymer dissolution, diffusion in the polymer and drug release from swelling and eroding polymer matrix formulations are reviewed. Importantly, the experiments used to characterize the processes occurring during the release and to validate the models are presented and discussed. Copyright © 2011 Elsevier B.V. All rights reserved.

  7. Amphiphilic polymer based on fluoroalkyl and PEG side chains for fouling release coating

    NASA Astrophysics Data System (ADS)

    Cong, W. W.; Wang, K.; Yu, X. Y.; Zhang, H. Q.; Lv, Z.; Gui, T. J.

    2017-12-01

    Under static conditions, fouling release coating could not express good release property to marine organisms. Amphiphilic polymer with mixture of fluorinated monomer and short side group of polyethylene glycol (PEG) was synthesized. And also we studied the ability of amphiphilic polymer to influence the surface properties and how it controlled the adhesion of marine organisms to coated surfaces. By incorporating fluorinated monomer and PEG side chain into the polymer, the effect of incorporating both polar and non-polar groups on fouling-release coating could be studied. The dry surface was characterized by three-dimensional digital microscopy and scanning electron microscopy (SEM), and the morphology of the amphiphilic fouling release coating showed just like flaky petal. The amphiphilic polymer in fouling release coating tended to reconstruct in water, and the ability was examined by static contact angle, which was smaller than the PDMS (polydimethylsiloxane) fouling release coating. Also surface energy was calculated by three solvents, and surface energy of amphiphilic fouling release coating was higher than that of the PDMS fouling release coating. To understand more about its fouling release property, seawater exposure method was adopted in gulf of Qingdao port. Fewer diatoms Navicula were found in biofilm after using amphiphilic fouling release coating. In general, coating containing both PEG and fluorinated side chain possessed certain fouling release property.

  8. Application of hybrid organic/inorganic polymers as coatings on metallic substrates

    NASA Astrophysics Data System (ADS)

    Augustinho, T. R.; Motz, G.; Ihlow, S.; Machado, R. A. F.

    2016-09-01

    Acrylic polymers, particularly poly (methyl methacrylate) (PMMA), have certain specific properties, such as good film formation, transparency, and good mechanical properties, which have been widely used in paints, coatings and adhesives. However, the limited chemical and physical stability of these pure polymers limits their applications when exposed to hostile conditions, as in ship hulls, for example. A suitable way to enhance PMMA properties is the addition of silicon polymers with very good protective characteristics. In this study, a PMMA and HTT 1800 (commercial silazane) copolymer were applied on metallic substrate and compared to pure PMMA and HTT 1800. All the materials were applied as coatings. They were applied on stainless steel via dip-coating to investigate the coating properties. Thermal cycling was employed to analyze coating durability at high temperatures (50 °C to 600 °C). Optical microscopy (OM) and scanning electron microscopy (SEM) were used to characterize the coated surfaces, and the adhesion of pure PMMA, pure HTT 1800 and PMMA/HTT 1800 coatings on metallic substrate was investigated by Cross-Cut-Test (ASTM D 3359). The sessile drop method was used to determine the contact angle. PMMA coatings presented complete degradation from 250 °C, while hybrid coatings of PMMA and HTT 1800 have good protection until 400 °C. The adherence of the coating on metallic substrate showed improvement in all synthesized materials when compared to pure PMMA, obtaining the best adherence possible. The contact angle test showed that the hydrophobicity of the hybrid coatings is higher than that of the pure coatings.

  9. High-performance supercapacitors of Cu-based porous coordination polymer nanowires and the derived porous CuO nanotubes.

    PubMed

    Wu, Meng-Ke; Zhou, Jiao-Jiao; Yi, Fei-Yan; Chen, Chen; Li, Yan-Li; Li, Qin; Tao, Kai; Han, Lei

    2017-12-12

    Electrode materials for supercapacitors with one-dimensional porous nanostructures, such as nanowires and nanotubes, are very attractive for high-efficiency storage of electrochemical energy. Herein, ultralong Cu-based porous coordination polymer nanowires (copper-l-aspartic acid) were used as the electrode material for supercapacitors, for the first time. The as-prepared material exhibits a high specific capacitance of 367 F g -1 at 0.6 A g -1 and excellent cycling stability (94% retention over 1000 cycles). Moreover, porous CuO nanotubes were successfully fabricated by the thermal decomposition of this nanowire precursor. The CuO nanotube exhibits good electrochemical performance with high rate capacity (77% retention at 12.5 A g -1 ) and long-term stability (96% retention over 1000 cycles). The strategy developed here for the synthesis of porous nanowires and nanotubes can be extended to the construction of other electrode materials for more efficient energy storage.

  10. Polymer as permeability modifier in porous media for enhanced oil recovery

    NASA Astrophysics Data System (ADS)

    Parsa, Shima; Weitz, David

    2017-11-01

    We use confocal microscopy to directly visualize the changes in morphology and mobilization of trapped oil ganglia within a 3D micromodel of porous media upon polymer flooding. Enhanced oil recovery is achieved in polymer flooding with large molecular weight at concentrations close or higher than a critical concentration of polymer. We also measure the fluctuations of the velocity of the displacing fluid and show that the velocities change upon polymer flooding in the whole medium. The changes in the fluid velocities are heterogeneous and vary in different pores, hence only providing enough pressure gradient across a few of the trapped oil ganglia and mobilize them. Our measurements show that polymer flooding is an effective method for enhancing oil recovery due to retention of polymer on the solid surfaces and changing the resistances of the available paths to water.

  11. Antibacterial graphene oxide coatings on polymer substrate

    NASA Astrophysics Data System (ADS)

    Liu, Yiming; Wen, Jing; Gao, Yang; Li, Tianyang; Wang, Huifang; Yan, Hong; Niu, Baolong; Guo, Ruijie

    2018-04-01

    Graphene oxide (GO) was thought to be a promising antibacterial material. In this work, graphene oxide coatings on polymer substrate were prepared and the antibacterial activity against E. coli and S. aureus was investigated. It was demonstrated that the coatings exhibited stronger antibacterial activity against E. coli with thin membrane than S. aureus with thick membrane. Take into consideration the fact that the coatings presented smooth, sharp edges-free morphology and bonded parallelly to substrate, which was in mark contrast with their precursor GO nanosheets, oxidative stress mechanism was considered the main factor of antibacterial activity. The coatings, which are easy to recycle and have no inhalation risk, provide an alternative for application in antibacterial medical instruments.

  12. Dry particle coating of polymer particles for tailor-made product properties

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Blümel, C., E-mail: karl-ernst.wirth@fau.de; Schmidt, J., E-mail: karl-ernst.wirth@fau.de; Dielesen, A., E-mail: karl-ernst.wirth@fau.de

    2014-05-15

    Disperse polymer powders with tailor-made particle properties are of increasing interest in industrial applications such as Selective Laser Beam Melting processes (SLM). This study focuses on dry particle coating processes to improve the conductivity of the insulating polymer powder in order to assemble conductive devices. Therefore PP particles were coated with Carbon Black nanoparticles in a dry particle coating process. This process was investigated in dependence of process time and mass fraction of Carbon Black. The conductivity of the functionalized powders was measured by impedance spectroscopy. It was found that there is a dependence of process time, respectively coating ratiomore » and conductivity. The powder shows higher conductivities with increasing number of guest particles per host particle surface area, i.e. there is a correlation between surface functionalization density and conductivity. The assembled composite particles open new possibilities for processing distinct polymers such as PP in SLM process. The fundamentals of the dry particle coating process of PP host particles with Carbon Black guest particles as well as the influence on the electrical conductivity will be discussed.« less

  13. Mechanisms of chain adsorption on porous substrates and critical conditions of polymer chromatography.

    PubMed

    Cimino, Richard T; Rasmussen, Christopher J; Brun, Yefim; Neimark, Alexander V

    2016-11-01

    Polymer adsorption is a ubiquitous phenomenon with numerous technological and healthcare applications. The mechanisms of polymer adsorption on surfaces and in pores are complex owing to a competition between various entropic and enthalpic factors. Due to adsorption of monomers to the surface, the chain gains in enthalpy yet loses in entropy because of confining effects. This competition leads to the existence of critical conditions of adsorption when enthalpy gain and entropy loss are in balance. The critical conditions are controlled by the confining geometry and effective adsorption energy, which depends on the solvent composition and temperature. This phenomenon has important implications in polymer chromatography, since the retention at the critical point of adsorption (CPA) is chain length independent. However, the mechanisms of polymer adsorption in pores are poorly understood and there is an ongoing discussion in the theoretical literature about the very existence of CPA for polymer adsorption on porous substrates. In this work, we examine the mechanisms of chain adsorption on a model porous substrate using Monte Carlo (MC) simulations. We distinguish three adsorption mechanisms depending on the chain location: on external surface, completely confined in pores, and also partially confined in pores in so-called "flower" conformations. The free energies of different conformations of adsorbed chains are calculated by the incremental gauge cell MC method that allows one to determine the partition coefficient as a function of the adsorption potential, pore size, and chain length. We confirm the existence of the CPA for chain length independent separation on porous substrates, which is explained by the dominant contributions of the chain adsorption at the external surface, in particular in flower conformations. Moreover, we show that the critical conditions for porous and nonporous substrates are identical and depend only on the surface chemistry. The theoretical

  14. Polymer Coating of Carbon Nanotube Fibers for Electric Microcables

    PubMed Central

    Alvarez, Noe T.; Ochmann, Timothy; Kienzle, Nicholas; Ruff, Brad; Haase, Mark R.; Hopkins, Tracy; Pixley, Sarah; Mast, David; Schulz, Mark J.; Shanov, Vesselin

    2014-01-01

    Carbon nanotubes (CNTs) are considered the most promising candidates to replace Cu and Al in a large number of electrical, mechanical and thermal applications. Although most CNT industrial applications require macro and micro size CNT fiber assemblies, several techniques to make conducting CNT fibers, threads, yarns and ropes have been reported to this day, and improvement of their electrical and mechanical conductivity continues. Some electrical applications of these CNT conducting fibers require an insulating layer for electrical insulation and protection against mechanical tearing. Ideally, a flexible insulator such as hydrogenated nitrile butadiene rubber (HNBR) on the CNT fiber can allow fabrication of CNT coils that can be assembled into lightweight, corrosion resistant electrical motors and transformers. HNBR is a largely used commercial polymer that unlike other cable-coating polymers such as polyvinyl chloride (PVC), it provides unique continuous and uniform coating on the CNT fibers. The polymer coated/insulated CNT fibers have a 26.54 μm average diameter—which is approximately four times the diameter of a red blood cell—is produced by a simple dip-coating process. Our results confirm that HNBR in solution creates a few microns uniform insulation and mechanical protection over a CNT fiber that is used as the electrically conducting core. PMID:28344254

  15. Polymer Coating of Carbon Nanotube Fibers for Electric Microcables.

    PubMed

    Alvarez, Noe T; Ochmann, Timothy; Kienzle, Nicholas; Ruff, Brad; Haase, Mark R; Hopkins, Tracy; Pixley, Sarah; Mast, David; Schulz, Mark J; Shanov, Vesselin

    2014-11-04

    Carbon nanotubes (CNTs) are considered the most promising candidates to replace Cu and Al in a large number of electrical, mechanical and thermal applications. Although most CNT industrial applications require macro and micro size CNT fiber assemblies, several techniques to make conducting CNT fibers, threads, yarns and ropes have been reported to this day, and improvement of their electrical and mechanical conductivity continues. Some electrical applications of these CNT conducting fibers require an insulating layer for electrical insulation and protection against mechanical tearing. Ideally, a flexible insulator such as hydrogenated nitrile butadiene rubber (HNBR) on the CNT fiber can allow fabrication of CNT coils that can be assembled into lightweight, corrosion resistant electrical motors and transformers. HNBR is a largely used commercial polymer that unlike other cable-coating polymers such as polyvinyl chloride (PVC), it provides unique continuous and uniform coating on the CNT fibers. The polymer coated/insulated CNT fibers have a 26.54 μm average diameter-which is approximately four times the diameter of a red blood cell-is produced by a simple dip-coating process. Our results confirm that HNBR in solution creates a few microns uniform insulation and mechanical protection over a CNT fiber that is used as the electrically conducting core.

  16. Imidazolium salt-modified porous hypercrosslinked polymers for synergistic CO2 capture and conversion.

    PubMed

    Wang, Jinquan; Sng, Waihong; Yi, Guangshun; Zhang, Yugen

    2015-08-04

    A new type of imidazolium salt-modified porous hypercrosslinked polymer (BET surface area up to 926 m(2) g(-1)) was reported. These porous materials exhibited good CO2 capture capacities (14.5 wt%) and catalytic activities for the conversion of CO2 into various cyclic carbonates under metal-free conditions. The synergistic effect of CO2 capture and conversion was observed.

  17. Laser-induced porous graphene films from commercial polymers

    PubMed Central

    Lin, Jian; Peng, Zhiwei; Liu, Yuanyue; Ruiz-Zepeda, Francisco; Ye, Ruquan; Samuel, Errol L. G.; Yacaman, Miguel Jose; Yakobson, Boris I.; Tour, James M.

    2014-01-01

    Synthesis and patterning of carbon nanomaterials cost effectively is a challenge in electronic and energy storage devices. Here report a one-step, scalable approach for producing and patterning porous graphene films with 3-dimensional networks from commercial polymer films using a CO2 infrared laser. The sp3-carbon atoms are photothermally converted to sp2-carbon atoms by pulsed laser irradiation. The resulting laser-induced graphene (LIG) exhibits high electrical conductivity. The LIG can be readily patterned to interdigitated electrodes for in-plane microsupercapacitors with specific capacitances of >4 mF·cm−2 and power densities of ~9 mW·cm−2. Theoretical calculations partially suggest that enhanced capacitance may result from LIG’s unusual ultra-polycrystalline lattice of pentagon-heptagon structures. Combined with the advantage of one-step processing of LIG in air from commercial polymer sheets, which would allow the employment of a roll-to-roll manufacturing process, this technique provides a rapid route to polymer-written electronic and energy storage devices. PMID:25493446

  18. Effect of nano-hydroxyapatite coating on the osteoinductivity of porous biphasic calcium phosphate ceramics.

    PubMed

    Hu, Jianzhong; Zhou, Yongchun; Huang, Lihua; Liu, Jun; Lu, Hongbin

    2014-04-01

    Porous biphasic calcium phosphate (BCP) ceramics exhibit good biocompatibility and bone conduction but are not inherently osteoinductive. To overcome this disadvantage, we coated conventional porous BCP ceramics with nano-hydroxyapatite (nHA). nHA was chosen as a coating material due to its high osteoinductive potential. We used a hydrothermal deposition method to coat conventional porous BCP ceramics with nHA and assessed the effects of the coating on the physical and mechanical properties of the underlying BCP. Next, its effects on mesenchymal stem cell (MSC) attachment, proliferation, viability, and osteogenic differentiation were investigated. nHA formed a deposited layer on the BCP surface, and synthesized nHA had a rod-like shape with lengths ranging from ~50-200 nm and diameters from ~15-30 mm. The nHA coating did not significantly affect the density, porosity, flexural strength, or compressive strength of the underlying BCP (P > 0.1). Scanning electron microscopy showed MSC attachment to the scaffolds, with a healthy morphology and anchorage to nHA crystals via cytoplasmic processes. The densities of MSCs attached on BCP and nHA-coated BCP scaffolds were 62 ± 26 cells/mm2 and 63 ± 27 cells/mm2 (P > 0.1), respectively, after 1 day and 415 ± 62 cells/mm2 and 541 ± 35 cells/mm2 (P < 0.05) respectively, after 14 days. According to an MTT assay, MSC viability was higher on nHA-coated BCP scaffolds than on BCP scaffolds (P < 0.05). In addition, MSCs on nHA-coated BCP scaffolds produced more alkaline phosphatase, collagen type I, and osteocalcin than MSCs on BCP scaffolds (P < 0.05). Our results demonstrate that BCP scaffolds coated with nHA were more conducive for MSC adhesion, proliferation, and osteogenic differentiation than conventional, uncoated BCP scaffolds, indicating that nHA coating can enhance the osteoinductive potential of BCP ceramics, making this material more suitable for applications in bone tissue

  19. Electrochemical Impedance Spectroscopy of Conductive Polymer Coatings

    NASA Technical Reports Server (NTRS)

    Calle, Luz Marina; MacDowell, Louis G.

    1996-01-01

    Electrochemical impedance spectroscopy (EIS) was used to investigate the corrosion protection performance of twenty nine proprietary conductive polymer coatings for cold rolled steel under immersion in 3.55 percent NaCl. Corrosion potential as well as Bode plots of the data were obtained for each coating after one hour immersion, All coatings, with the exception of one, have a corrosion potential that is higher in the positive direction than the corrosion potential of bare steel under the same conditions. Group A consisted of twenty one coatings with Bode plots indicative of the capacitive behavior characteristic of barrier coatings. An equivalent circuit consisting of a capacitor in series with a resistor simulated the experimental EIS data for these coatings very well. Group B consisted of eight coatings that exhibited EIS spectra showing an inflection point which indicates that two time constants are present. This may be caused by an electrochemical process taking place which could be indicitive of coating failing. These coatings have a lower impedance that those in Group A.

  20. Toward compositional design of reticular type porous films by mixing and coating titania-based frameworks with silica

    NASA Astrophysics Data System (ADS)

    Kimura, T.

    2015-12-01

    A recently developed reticular type porous structure, which can be fabricated as the film through the soft colloidal block copolymer (e.g., PS-b-PEO) templating, is very promising as the porous platform showing high-performance based on its high surface area as well as high diffusivity of targeted organic molecules and effective accommodation of bulky molecules, but the compositional design of oxide frameworks has not been developed so enough to date. Here, I report reliable synthetic methods of the reticular type porous structure toward simple compositional variations. Due to the reproducibility of reticular type porous titania films from titanium alkoxide (e.g., TTIP; titanium tetraisopropoxide), a titania-silica film having similar porous structure was obtained by mixing silicon alkoxide (e.g., tetraethoxysilane) and TTIP followed by their pre-hydrolysis, and the mixing ratio of Ti to Si composition was easily reached to 1.0. For further compositional design, a concept of surface coating was widely applicable; the reticular type porous titania surfaces can be coated with other oxides such as silica. Here, a silica coating was successfully achieved by the simple chemical vapor deposition of silicon alkoxide (e.g., tetramethoxysilane) without water (with water at the humidity level), which was also utilized for pore filling with silica by the similar process with water.

  1. Multilayer polymer light-emitting diodes by blade coating method

    NASA Astrophysics Data System (ADS)

    Tseng, Shin-Rong; Meng, Hsin-Fei; Lee, Kuan-Chen; Horng, Sheng-Fu

    2008-10-01

    Multilayer polymer light-emitting diodes fabricated by blade coating are presented. Multilayer of polymers can be easily deposited by blade coating on a hot plate. The multilayer structure is confirmed by the total thickness and the cross section view in the scanning electron microscope. The film thickness variation is only 3.3% in 10cm scale and the film roughness is about 0.3nm in the micron scale. The efficiency of single layer poly(para-phenylene vinylene) copolymer Super Yellow and poly(9,9-dioctylfluorene) (PFO, deep blue) devices are 9 and 1.7cd/A, respectively, by blade coating. The efficiency of the PFO device is raised to 2.9cd/A with a 2-(4-tert-butylphenyl)-5-(4-biphenylyl)-1,3,4-oxadiazole (PBD) hole-blocking layer and to 2.3cd/A with a poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl))diphenylamine)] elec-tron-blocking layer added by blade coating.

  2. Porous-Hybrid Polymers as Platforms for Heterogeneous Photochemical Catalysis.

    PubMed

    Haikal, Rana R; Wang, Xia; Hassan, Youssef S; Parida, Manas R; Murali, Banavoth; Mohammed, Omar F; Pellechia, Perry J; Fontecave, Marc; Alkordi, Mohamed H

    2016-08-10

    A number of permanently porous polymers containing Ru(bpy)n photosensitizer or a cobaloxime complex, as a proton-reduction catalyst, were constructed via one-pot Sonogashira-Hagihara (SH) cross-coupling reactions. This process required minimal workup to access porous platforms with control over the apparent surface area, pore volume, and chemical functionality from suitable molecular building blocks (MBBs) containing the Ru or Co complexes, as rigid and multitopic nodes. The cobaloxime molecular building block, generated through in situ metalation, afforded a microporous solid that demonstrated noticeable catalytic activity toward hydrogen-evolution reaction (HER) with remarkable recyclability. We further demonstrated, in two cases, the ability to affect the excited-state lifetime of the covalently immobilized Ru(bpy)3 complex attained through deliberate utilization of the organic linkers of variable dimensions. Overall, this approach facilitates construction of tunable porous solids, with hybrid composition and pronounced chemical and physical stability, based on the well-known Ru(bpy)nor the cobaloxime complexes.

  3. Enhanced Physical Stability of Amorphous Drug Formulations via Dry Polymer Coating.

    PubMed

    Capece, Maxx; Davé, Rajesh

    2015-06-01

    Although amorphous solid drug formulations may be advantageous for enhancing the bioavailability of poorly soluble active pharmaceutical ingredients, they exhibit poor physical stability and undergo recrystallization. To address this limitation, this study investigates stability issues associated with amorphous solids through analysis of the crystallization behavior for acetaminophen (APAP), known as a fast crystallizer, using a modified form of the Avrami equation that kinetically models both surface and bulk crystallization. It is found that surface-enhanced crystallization, occurring faster at the free surface than in the bulk, is the major impediment to the stability of amorphous APAP. It is hypothesized that a novel use of a dry-polymer-coating process referred to as mechanical-dry-polymer-coating may be used to inhibit surface crystallization and enhance stability. The proposed process, which is examined, simultaneously mills and coats amorphous solids with polymer, while avoiding solvents or solutions, which may otherwise cause stability or crystallization issues during coating. It is shown that solid dispersions of APAP (64% loading) with a small particle size (28 μm) could be prepared and coated with the polymer, carnauba wax, in a vibratory ball mill. The resulting amorphous solid was found to have excellent stability as a result of inhibition of surface crystallization. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

  4. Electrochemical Deposition of Nanostructured Conducting Polymer Coatings on Neural Prosthetic Devices

    NASA Astrophysics Data System (ADS)

    Yang, Junyan; Martin, David

    2003-03-01

    Micromachined neural prosthetic devices facilitate the functional stimulation of and recording from the central nervous system (CNS). These devices have been fabricated to consist of silicon shanks that have gold or iridium sites along their surface. Our goal is to improve the biocompatibility and long-term performance of the neural prosthetic probes when they are implanted chronically in the brain. In our most recent efforts we have established that electrochemical polymerization can be used to deposit fuzzy coatings of conducting polymers specifically on the electrode sites. For neural prosthetic devices that are intended for long term implantation, we need to develop surfaces that provide intimate contact and promote efficient signal transport at the interface of the microelectrode array and brain tissue. We have developed methods to rapidly and reliably fabricate nanostructured conducting polymer coatings on the electrode probes using templated and surfactant-mediated techniques. Conducting polymer nanomushrooms and nanohairs of polypyrrole (PPy) were electrochemically polymerized onto the functional sites of neural probes by using either nanoporous block copolymers thin films, "track-etched" polycarbonate films or anodic aluminium oxide membranes as templates. Nanofibers of conducting polymers have also been successfully obtained by polymerizations in the presence of surfactants. The influence of current density, monomer concentration, surfactant concentration, and deposition charge on the thickness and morphology of the nanostructured conducting polymer coatings has been studied by optical, scanned probe, scanning electron and transmission electron microscopy. As compared with the normal nodular morphology of polypyrrole, the nanostructured morphologies grown from the neural electrode result in fuzzy coatings with extremely high surface area. The electrical properties of the polymer coatings were studied by Impedance Spectroscopy (IS) and Cyclic Voltammetry

  5. Ultra-Porous Nanoparticle Networks: A Biomimetic Coating Morphology for Enhanced Cellular Response and Infiltration

    PubMed Central

    Nasiri, Noushin; Ceramidas, Anthony; Mukherjee, Shayanti; Panneerselvan, Anitha; Nisbet, David R.; Tricoli, Antonio

    2016-01-01

    Orthopedic treatments are amongst the most common cause of surgery and are responsible for a large share of global healthcare expenditures. Engineering materials that can hasten bone integration will improve the quality of life of millions of patients per year and reduce associated medical costs. Here, we present a novel hierarchical biomimetic coating that mimics the inorganic constituent of mammalian bones with the aim of improving osseointegration of metallic implants. We exploit the thermally-driven self-organization of metastable core-shell nanoparticles during their aerosol self-assembly to rapidly fabricate robust, ultra-porous nanoparticle networks (UNN) of crystalline hydroxyapatite (HAp). Comparative analysis of the response of osteoblast cells to the ultra-porous nanostructured HAp surfaces and to the spin coated HAp surfaces revealed superior osseointegrative properties of the UNN coatings with significant cell and filopodia infiltration. This flexible synthesis approach for the engineering of UNN HAp coatings on titanium implants provides a platform technology to study the bone-implant interface for improved osseointegration and osteoconduction. PMID:27076035

  6. Porous inorganic-organic shape memory polymers.

    PubMed

    Zhang, Dawei; Burkes, William L; Schoener, Cody A; Grunlan, Melissa A

    2012-06-21

    Thermoresponsive shape memory polymers (SMPs) are a type of stimuli-sensitive materials that switch from a temporary shape back to their permanent shape upon exposure to heat. While the majority of SMPs have been fabricated in the solid form, porous SMP foams exhibit distinct properties and are better suited for certain applications, including some in the biomedical field. Like solid SMPs, SMP foams have been restricted to a limited group of organic polymer systems. In this study, we prepared inorganic-organic SMP foams based on the photochemical cure of a macromer comprised of inorganic polydimethylsiloxane (PDMS) segments and organic poly(ε-caprolactone) (PCL) segments, diacrylated PCL(40)-block-PDMS(37)-block-PCL(40). To achieve tunable pore size with high interconnectivity, the SMP foams were prepared via a refined solvent-casting/particulate-leaching (SCPL) method. By varying design parameters such as degree of salt fusion, macromer concentration in the solvent and salt particle size, the SMP foams with excellent shape memory behavior and tunable pore size, pore morphology, and modulus were obtained.

  7. The effect of sol-gel-formed calcium phosphate coatings on bone ingrowth and osteoconductivity of porous-surfaced Ti alloy implants.

    PubMed

    Nguyen, H Q; Deporter, D A; Pilliar, R M; Valiquette, N; Yakubovich, R

    2004-02-01

    Ti-6Al-4V implants formed with a sintered porous surface for implant fixation by bone ingrowth were prepared with or without the addition of a thin surface layer of calcium phosphate (Ca-P) formed using a sol-gel coating technique over the porous surface. The implants were placed transversely across the tibiae of 17 rabbits. Implanted sites were allowed to heal for 2 weeks, after which specimens were retrieved for morphometric assessment using backscattered scanning electron microscopy and quantitative image analysis. Bone formation along the porous-structured implant surface, was measured in relation to the medial and lateral cortices as an indication of implant surface osteoconductivity. The Absolute Contact Length measurements of endosteal bone growth along the porous-surfaced zone were greater with the Ca-P-coated implants compared to the non-Ca-P-coated implants. The Ca-P-coated implants also displayed a trend towards a significant increase in the area of bone ingrowth (Bone Ingrowth Fraction). Finally, there was significantly greater bone-to-implant contact within the sinter neck regions of the Ca-P-coated implants.

  8. Debonding of porous coating of a threaded acetabular component: retrieval analysis.

    PubMed

    Łapaj, Łukasz; Markuszewski, Jacek; Rybak, Tomasz; Wierusz-Kozłowska, Małgorzata

    2013-01-01

    This report presents a case of debonding of plasma sprayed porous titanium coating from a threaded acetabular component which caused aseptic loosening of the implant. Weight bearing after delamination caused abrasive damage of the acetabular shell, and particles of the coating embedded in the acetabular liner. Microscopic examination of periprosthetic tissues showed presence of metal particles and macrophage infiltration. Despite microscopic examination of the retrieved component the cause of debonding remains unclear. Copyright © 2012 Elsevier Ltd. All rights reserved.

  9. Porous biphasic calcium phosphate ceramics coated with nano-hydroxyapatite and seeded with mesenchymal stem cells for reconstruction of radius segmental defects in rabbits.

    PubMed

    Hu, Jianzhong; Yang, Zhiming; Zhou, Yongchun; Liu, Yong; Li, Kaiyang; Lu, Hongbin

    2015-11-01

    The osteoconduction of porous biphasic calcium phosphate (BCP) ceramics has been widely reported. In a previous study, we demonstrated that applying a nano-hydroxyapatite (nHA) coating enhances the osteoinductive potential of BCP ceramics, making these scaffolds more suitable for bone tissue engineering applications. The aim of the present study was to determine the effects of reconstructing radius defects in rabbits using nHA-coated BCP ceramics seeded with mesenchymal stem cells (MSCs) and to compare the bone regeneration induced by different scaffolds. Radius defects were created in 20 New Zealand rabbits, which were divided into four groups by treatment: porous BCP ceramics (Group A), nHA-coated porous BCP ceramics (Group B), porous BCP ceramics seeded with rabbit MSCs (Group C), and nHA-coated porous BCP ceramics seeded with rabbit MSCs (Group D). After in vitro incubation, the cell/scaffold complexes were implanted into the defects. Twelve weeks after implantation, the specimens were examined macroscopically and histologically. Both the nHA coating and seeding with MSCs enhanced the formation of new bone tissue in the BCP ceramics, though the osteoinductive potential of the scaffolds with MSCs was greater than that of the nHA-coated scaffolds. Notably, the combination of nHA coating and MSCs significantly improved the bone regeneration capability of the BCP ceramics. Thus, MSCs seeded into porous BCP ceramics coated with nHA may be an effective bone substitute to reconstruct bone defects in the clinic.

  10. Polymer coating for immobilizing soluble ions in a phosphate ceramic product

    DOEpatents

    Singh, Dileep; Wagh, Arun S.; Patel, Kartikey D.

    2000-01-01

    A polymer coating is applied to the surface of a phosphate ceramic composite to effectively immobilize soluble salt anions encapsulated within the phosphate ceramic composite. The polymer coating is made from ceramic materials, including at least one inorganic metal compound, that wet and adhere to the surface structure of the phosphate ceramic composite, thereby isolating the soluble salt anions from the environment and ensuring long-term integrity of the phosphate ceramic composite.

  11. Influence of implantation on the electrochemical properties of smooth and porous TiN coatings for stimulation electrodes

    NASA Astrophysics Data System (ADS)

    Meijs, S.; Sørensen, C.; Sørensen, S.; Rechendorff, K.; Fjorback, M.; Rijkhoff, N. J. M.

    2016-04-01

    Objective. To determine whether changes in electrochemical properties of porous titanium nitride (TiN) electrodes as a function of time after implantation are different from those of smooth TiN electrodes. Approach. Eight smooth and 8 porous TiN coated electrodes were implanted in 8 rats. Before implantation, voltage transients, cyclic voltammograms and impedance spectra were recorded in phosphate buffered saline (PBS). After implantation, these measurements were done weekly to investigate how smooth and porous electrodes were affected by implantation. Main results. The electrode capacitance of the porous TiN electrodes decreased more than the capacitance of the smooth electrodes due to acute implantation under fast measurement conditions (such as stimulation pulses). This indicates that protein adhesion presents a greater diffusion limitation for counter-ions for the porous than for the smooth electrodes. The changes in electrochemical properties during the implanted period were similar for smooth and porous TiN electrodes, indicating that cell adhesion poses a similar diffusion limitation for smooth and porous electrodes. Significance. This knowledge can be used to optimize the porous structure of the TiN film, so that the effect of protein adhesion on the electrochemical properties is diminished. Alternatively, an additional coating could be applied on the porous TiN that would prevent or minimize protein adhesion.

  12. Development of Anticorrosive Polymer Nanocomposite Coating for Corrosion Protection in Marine Environment

    NASA Astrophysics Data System (ADS)

    Mardare, L.; Benea, L.

    2017-06-01

    The marine environment is considered to be a highly aggressive environment for metal materials. Steels are the most common materials being used for shipbuilding. Corrosion is a major cause of structural deterioration in marine and offshore structures. Corrosion of carbon steel in marine environment becomes serious due to the highly corrosive nature of seawater with high salinity and microorganism. To protect metallic materials particularly steel against corrosion occurrence various organic and inorganic coatings are used. The most used are the polymeric protective coatings. The nanostructured TiO2 polymer coating is able to offer higher protection to steel against corrosion, and performed relatively better than other polymer coatings.

  13. Effect of nano-hydroxyapatite coating on the osteoinductivity of porous biphasic calcium phosphate ceramics

    PubMed Central

    2014-01-01

    Background Porous biphasic calcium phosphate (BCP) ceramics exhibit good biocompatibility and bone conduction but are not inherently osteoinductive. To overcome this disadvantage, we coated conventional porous BCP ceramics with nano-hydroxyapatite (nHA). nHA was chosen as a coating material due to its high osteoinductive potential. Methods We used a hydrothermal deposition method to coat conventional porous BCP ceramics with nHA and assessed the effects of the coating on the physical and mechanical properties of the underlying BCP. Next, its effects on mesenchymal stem cell (MSC) attachment, proliferation, viability, and osteogenic differentiation were investigated. Results nHA formed a deposited layer on the BCP surface, and synthesized nHA had a rod-like shape with lengths ranging from ~50–200 nm and diameters from ~15–30 mm. The nHA coating did not significantly affect the density, porosity, flexural strength, or compressive strength of the underlying BCP (P > 0.1). Scanning electron microscopy showed MSC attachment to the scaffolds, with a healthy morphology and anchorage to nHA crystals via cytoplasmic processes. The densities of MSCs attached on BCP and nHA-coated BCP scaffolds were 62 ± 26 cells/mm2 and 63 ± 27 cells/mm2 (P > 0.1), respectively, after 1 day and 415 ± 62 cells/mm2 and 541 ± 35 cells/mm2 (P < 0.05) respectively, after 14 days. According to an MTT assay, MSC viability was higher on nHA-coated BCP scaffolds than on BCP scaffolds (P < 0.05). In addition, MSCs on nHA-coated BCP scaffolds produced more alkaline phosphatase, collagen type I, and osteocalcin than MSCs on BCP scaffolds (P < 0.05). Conclusions Our results demonstrate that BCP scaffolds coated with nHA were more conducive for MSC adhesion, proliferation, and osteogenic differentiation than conventional, uncoated BCP scaffolds, indicating that nHA coating can enhance the osteoinductive potential of BCP ceramics, making this material more

  14. Laser-induced porous graphene films from commercial polymers

    NASA Astrophysics Data System (ADS)

    Lin, Jian; Peng, Zhiwei; Liu, Yuanyue; Ruiz-Zepeda, Francisco; Ye, Ruquan; Samuel, Errol L. G.; Yacaman, Miguel Jose; Yakobson, Boris I.; Tour, James M.

    2014-12-01

    The cost effective synthesis and patterning of carbon nanomaterials is a challenge in electronic and energy storage devices. Here we report a one-step, scalable approach for producing and patterning porous graphene films with three-dimensional networks from commercial polymer films using a CO2 infrared laser. The sp3-carbon atoms are photothermally converted to sp2-carbon atoms by pulsed laser irradiation. The resulting laser-induced graphene (LIG) exhibits high electrical conductivity. The LIG can be readily patterned to interdigitated electrodes for in-plane microsupercapacitors with specific capacitances of >4 mF cm-2 and power densities of ~9 mW cm-2. Theoretical calculations partially suggest that enhanced capacitance may result from LIG’s unusual ultra-polycrystalline lattice of pentagon-heptagon structures. Combined with the advantage of one-step processing of LIG in air from commercial polymer sheets, which would allow the employment of a roll-to-roll manufacturing process, this technique provides a rapid route to polymer-written electronic and energy storage devices.

  15. Double polymer sheathed carbon nanotube supercapacitors show enhanced cycling stability

    NASA Astrophysics Data System (ADS)

    Zhao, Wenqi; Wang, Shanshan; Wang, Chunhui; Wu, Shiting; Xu, Wenjing; Zou, Mingchu; Ouyang, An; Cao, Anyuan; Li, Yibin

    2015-12-01

    Pseudo-materials are effective in boosting the specific capacitance of supercapacitors, but during service their degradation may also be very strong, causing reduced cycling stability. Here, we show that a carbon nanotube sponge grafted by two conventional pseudo-polymer layers in sequence can serve as a porous supercapacitor electrode with significantly enhanced cycling stability compared with single polymer grafting. Creating conformal polymer coatings on the nanotube surface and the resulting double-sheath configuration are important structural factors leading to the enhanced performance. Combining different polymers as double sheaths as reported here might be a potential route to circumvent the dilemma of pseudo-materials, and to simultaneously improve the capacitance and stability for various energy storage devices.Pseudo-materials are effective in boosting the specific capacitance of supercapacitors, but during service their degradation may also be very strong, causing reduced cycling stability. Here, we show that a carbon nanotube sponge grafted by two conventional pseudo-polymer layers in sequence can serve as a porous supercapacitor electrode with significantly enhanced cycling stability compared with single polymer grafting. Creating conformal polymer coatings on the nanotube surface and the resulting double-sheath configuration are important structural factors leading to the enhanced performance. Combining different polymers as double sheaths as reported here might be a potential route to circumvent the dilemma of pseudo-materials, and to simultaneously improve the capacitance and stability for various energy storage devices. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr05978j

  16. Porous Polystyrene Monoliths and Microparticles Prepared from Core Cross-linked Star (CCS) Polymers-Stabilized Emulsions.

    PubMed

    Chen, Qijing; Shi, Ting; Han, Fei; Li, Zihan; Lin, Chao; Zhao, Peng

    2017-08-17

    A hydrophobic CCS polymer of poly(benzyl methacrylate) (PBzMA) was prepared in toluene by reversible addition-fragmentation chain transfer (RAFT)-mediated dispersion polymerization. The CCS polymer, with poly(benzyl methacrylate) as the arm and crosslinked N, N'-bis(acryloyl)cystamine (BAC) as the core, was confirmed by characterization with gel permeation chromatography (GPC) and nuclear magnetic resonance (NMR) spectroscopy. Three kinds of oils (toluene, anisole and styrene) were chosen to study the emulsification properties of PBzMA CCS polymer. The oils can be emulsified by CCS polymer to form water-in-oil (w/o) emulsions. Moreover, w/o high internal phase emulsions (HIPEs) can be obtained with the increase of toluene and styrene volume fractions from 75% to 80%. Porous polystyrene monolith and microparticles were prepared from the emulsion templates and characterized by the scanning electronic microscopy (SEM). With the internal phase volume fraction increased, open-pore porous monolith was obtained.

  17. Novel processing to produce polymer/ceramic nanocomposites by atomic layer deposition

    NASA Astrophysics Data System (ADS)

    Liang, Xinhua

    Polymeric materials can be greatly influenced by nanoscale inclusions of inorganic materials. The main goal of this thesis is to fabricate novel polymer/ceramic composite materials for two different applications using atomic layer deposition (ALD) or molecular layer deposition (MLD) methods. One is to produce well-dispersed polymer/ceramic nanocomposites with improved barrier properties for packaging applications. The other is to produce porous polymer/ceramic composites with improved bioactivity for tissue engineering applications. ALD has been successfully utilized for the conformal and uniform deposition of ultra-thin alumina and titania films on primary micron-sized polymer particles. The mechanism to initiate alumina and titania ALD on polymer particles without chemical functional groups was confirmed. A nucleation period was needed for both alumina and titania ALD on high density polyethylene (HDPE) particles and no nucleation period was needed for alumina ALD on polymethyl methacrylate particles. Titania ALD films deposited at low temperatures had an amorphous structure and showed much weaker photoactivity than common pigment-grade anatase TiO2 particles. Highly uniform and conformal ultra-thin aluminum alkoxide (alucone) polymer films were deposited on primary silica and titania nanoparticles using MLD in a fluidized bed reactor. The deposition chemistry and properties of alucone MLD films were investigated. The photoactivity of pigment-grade TiO2 particles was quenched after 20 cycles of an alucone MLD film, but the films shrank and decomposed in the presence of water, which decreased the passivation effect of the photoactivity of TiO2 particles. Well-dispersed polymer/ceramic nanocomposites were obtained by extruding alumina ALD coated HDPE particles. The diffusion coefficient of the fabricated nanocomposite membranes can be reduced by half with the inclusion of 7.3 vol.% alumina flakes. However, a corresponding increase in permeability was also observed

  18. Novel Bio-functional Magnesium Coating on Porous Ti6Al4V Orthopaedic Implants: In vitro and In vivo Study

    PubMed Central

    Li, Xiaokang; Gao, Peng; Wan, Peng; Pei, Yifeng; Shi, Lei; Fan, Bo; Shen, Chao; Xiao, Xin; Yang, Ke; Guo, Zheng

    2017-01-01

    Titanium and its alloys with various porous structures are one of the most important metals used in orthopaedic implants due to favourable properties as replacement for hard tissues. However, surface modification is critical to improve the osteointegration of titanium and its alloys. In this study, a bioactive magnesium coating was successfully fabricated on porous Ti6Al4V by means of arc ion plating, which was proved with fine grain size and high film/substrate adhesion. The surface composition and morphology were characterized by X-ray diffraction and SEM equipped with energy dispersive spectroscopy. Furthermore, the in vitro study of cytotoxicity and proliferation of MC3T3-E1 cells showed that magnesium coated porous Ti6Al4V had suitable degradation and biocompatibility. Moreover, the in vivo studies including fluorescent labelling, micro-computed tomography analysis scan and Van-Gieson staining of histological sections indicated that magnesium coated porous Ti6Al4V could significantly promote bone regeneration in rabbit femoral condylar defects after implantation for 4 and 8 weeks, and has better osteogenesis and osteointegration than the bare porous Ti6Al4V. Therefore, it is expected that this bioactive magnesium coating on porous Ti6Al4V scaffolds with improved osteointegration and osteogenesis functions can be used for orthopedic applications. PMID:28102294

  19. Self-healing antimicrobial polymer coating with efficacy in the presence of organic matter

    NASA Astrophysics Data System (ADS)

    Bastarrachea, Luis J.; Goddard, Julie M.

    2016-08-01

    A method to prepare a self-healing, antimicrobial polymer coating that retains efficacy against Escherichia coli O157:H7 in the presence of organic matter is reported. A coating composed of branched polyethyleneimine (PEI) and styrene maleic anhydride copolymer (SMA) was applied to a maleic anhydride functionalized polypropylene support. The chemistry of the polymer coating was designed to impart hydrophobicity due to the styrene subunits, intrinsic antimicrobial character (>99.9% reduction) from the cationic primary amine groups, and enhanced antimicrobial character (> 99.99% reduction) after chlorination of N-halamine forming groups. Antimicrobial effectiveness was demonstrated under conditions of increasing organic load. Up to 500 ppm horse serum, chlorinated coatings retained full antimicrobial character (>99.99% reduction). Even at 50,000 ppm of horse serum, the coating provided ∼90% reduction as prepared, and between ∼75% and ∼80% reduction in the form of N-halamines. Microscopy confirmed no evidence of bacterial adhesion on the coating surface. Finally, the coating exhibited self-healing properties after exposure to acid and alkaline solutions and restoration by heat, as confirmed through spectroscopy from the rebuilding of characteristic chemical bonds. Such robust antimicrobial polymer coatings with efficacy under conditions of increasing organic load may support reducing microbial cross-contamination in food and biomedical industries.

  20. Distributed Pore Chemistry in Porous Organic Polymers in Tissue Culture Flasks

    NASA Technical Reports Server (NTRS)

    Koontz, Steven L. (Inventor)

    1999-01-01

    A method for making a biocompatible polymer article using a uniform atomic oxygen treatment is disclose. The substrate may be subsequently optionally grated with a compatibilizing compound. Compatibilizing compounds may include proteins, phosphorylcholine groups, platelet adhesion preventing polymers, albumin adhesion promoters, and the like. The compatibilized substrate may also have a living cell layer adhered thereto. The atomic oxygen is preferably produced by a flowing afterglow microwave discharge, wherein the substrate resides in a sidearm out of the plasma. Also, methods for culturing cells for various purposes using the various membranes are disclosed as well. Also disclosed are porous organic polymers having a distributed pore chemistry (DPC) comprising hydrophilic and hydrophobic regions, and a method for making the DPC by exposing the polymer to atomic oxygen wherein the rate of hydrophilization is greater than the rate of mass loss.

  1. Transport of poly(acrylic acid) coated 2-line ferrihydrite nanoparticles in saturated aquifer sediments for environmental remediation

    NASA Astrophysics Data System (ADS)

    Xiang, Aishuang; Zhou, Sheng; Koel, Bruce E.; Jaffé, Peter R.

    2014-04-01

    Groundwater remediation using iron oxide and zero-valent iron nanoparticles (NPs) can be effective, but is limited in many applications due to the NP strong retention in groundwater-saturated porous media after injection, the passivation of the porous surface, and the high cost of nanomaterials versus macro scale iron. In this study, we investigated transport of bare and polymer-coated 2-line ferrihydrite NPs (30-300 nm) in saturated aquifer sediments. The influence of poly(acrylic acid) (PAA) polymer coatings was studied on the colloidal stability and transport in sediments packed column tests simulating groundwater flow in saturated sediments. In addition, the influence of calcium cations was investigated by transport measurements using sediments with calcium concentrations in the aqueous phase ranging from 0.5 (typical for most sediments) to 2 mM. Measurements were also made of zeta potential, hydrodynamic diameter, polymer adsorption and desorption properties, and bio-availability of PAA-coated NPs. We found that NP transport through the saturated aquifer sediments was improved by PAA coating and that the transport properties could be tuned by adjusting the polymer concentration. We further discovered that PAA coatings enhanced NP transport, compared to bare NPs, in all calcium-containing experiments tested, however, the presence of calcium always exhibited a negative effect on NP transport. In tests of bioavailability, the iron reduction rate of the coated and bare NPs by Geobacter sulfurreducens was the same, which shows that the PAA coating does not significantly reduce NP Fe(III) bioavailability. Our results demonstrate that much improved transport of iron oxide NP can be achieved in saturated aquifer sediments by introducing negatively charged polyelectrolytes and optimizing polymer concentrations, and furthermore, these coated NPs retain their bioavailability that is needed for applications in bio-environmental remediation.

  2. Polyaniline-coated freestanding porous carbon nanofibers as efficient hybrid electrodes for supercapacitors

    NASA Astrophysics Data System (ADS)

    Tran, Chau; Singhal, Richa; Lawrence, Daniel; Kalra, Vibha

    2015-10-01

    Three-dimensional, free-standing, hybrid supercapacitor electrodes combining polyaniline (PANI) and porous carbon nanofibers (P-CNFs) were fabricated with the aim to integrate the benefits of both electric double layer capacitors (high power, cyclability) and pseudocapacitors (high energy density). A systematic investigation of three different electropolymerization techniques, namely, potentiodynamic, potentiostatic, and galvanostatic, for electrodeposition of PANI on freestanding carbon nanofiber mats was conducted. It was found that the galvanostatic method, where the current density is kept constant and can be easily controlled facilitates conformal and uniform coating of PANI on three-dimensional carbon nanofiber substrates. The electrochemical tests indicated that the PANI-coated P-CNFs exhibit excellent specific capacitance of 366 F g-1 (vs. 140 F g-1 for uncoated porous carbon nanofibers), 140 F cm-3 volumetric capacitance, and up to 2.3 F cm-2 areal capacitance at 100 mV s-1 scan rate. Such excellent performance is attributed to a thin and conformal coating of PANI achieved using the galvanostatic electrodeposition technique, which not only provides pseudocapacitance with high rate capability, but also retains the double-layer capacitance of the underlying P-CNFs.

  3. Polymer composites and porous materials prepared by thermally induced phase separation and polymer-metal hybrid methods

    NASA Astrophysics Data System (ADS)

    Yoon, Joonsung

    The primary objective of this research is to investigate the morphological and mechanical properties of composite materials and porous materials prepared by thermally induced phase separation. High melting crystallizable diluents were mixed with polymers so that the phase separation would be induced by the solidification of the diluents upon cooling. Theoretical phase diagrams were calculated using Flory-Huggins solution thermodynamics which show good agreement with the experimental results. Porous materials were prepared by the extraction of the crystallized diluents after cooling the mixtures (hexamethylbenzene/polyethylene and pyrene/polyethylene). Anisotropic structures show strong dependence on the identity of the diluents and the composition of the mixtures. Anisotropic crystal growth of the diluents was studied in terms of thermodynamics and kinetics using DSC, optical microscopy and SEM. Microstructures of the porous materials were explained in terms of supercooling and dendritic solidification. Dual functionality of the crystallizable diluents for composite materials was evaluated using isotactic polypropylene (iPP) and compatible diluents that crystallize upon cooling. The selected diluents form homogeneous mixtures with iPP at high temperature and lower the viscosity (improved processability), which undergo phase separation upon cooling to form solid particles that function as a toughening agent at room temperature. Tensile properties and morphology of the composites showed that organic crystalline particles have the similar effect as rigid particles to increase toughness; de-wetting between the particle and iPP matrix occurs at the early stage of deformation, followed by unhindered plastic flow that consumes significant amount of fracture energy. The effect of the diluents, however, strongly depends on the identity of the diluents that interact with the iPP during solidification step, which was demonstrated by comparing tetrabromobisphenol-A and

  4. A novel surface modification technique for forming porous polymer monoliths in poly(dimethylsiloxane).

    PubMed

    Burke, Jeffrey M; Smela, Elisabeth

    2012-03-01

    A new method of surface modification is described for enabling the in situ formation of homogenous porous polymer monoliths (PPMs) within poly(dimethylsiloxane) (PDMS) microfluidic channels that uses 365 nm UV illumination for polymerization. Porous polymer monolith formation in PDMS can be challenging because PDMS readily absorbs the monomers and solvents, changing the final monolith morphology, and because PDMS absorbs oxygen, which inhibits free-radical polymerization. The new approach is based on sequentially absorbing a non-hydrogen-abstracting photoinitiator and the monomers methyl methacrylate and ethylene diacrylate within the walls of the microchannel, and then polymerizing the surface treatment polymer within the PDMS, entangled with it but not covalently bound. Four different monolith compositions were tested, all of which yielded monoliths that were securely anchored and could withstand pressures exceeding the bonding strength of PDMS (40 psi) without dislodging. One was a recipe that was optimized to give a larger average pore size, required for low back pressure. This monolith was used to concentrate and subsequently mechanical lyse B lymphocytes.

  5. Fabrication and Characterization of Conductive Conjugated Polymer-Coated Antheraea mylitta Silk Fibroin Fibers for Biomedical Applications.

    PubMed

    Gh, Darshan; Kong, Dexu; Gautrot, Julien; Vootla, Shyam Kumar

    2017-07-01

    Conductive polymers are interesting materials for a number of biological and medical applications requiring electrical stimulation of cells or tissues. Highly conductive polymers (polypyrrole and polyaniline)/Antheraea mylitta silk fibroin coated fibers are fabricated successfully by in situ polymerization without any modification of the native silk fibroin. Coated fibers characterized by scanning electron microscopy confirm the silk fiber surface is covered by conductive polymers. Thermogravimetric analysis reveals preserved thermal stability of silk fiber after coating process. X-ray diffraction of degummed fiber diffraction peaks at around 2θ = 20.4 and 16.5 confirms the preservation of the β-sheet structure typical of degummed silk II fibers. This phenomenon implies that both polypyrrole and polyaniline chains form interactions with peptide linkages in degummed fiber macromolecules, without significantly disrupting protein assembly. Fourier transform infrared spectroscopy of coated fibers indicates hydrogen bonding and electrostatic interactions exist between silk fibroin macromolecules and conductive polymers. Resulting fibers display good conductive properties compared to corresponding conjugated polymers. In vitro analysis (live/dead assay) of the behavior of human immortalized keratinocytes (HaCaTs) on coated fibers demonstrates improved cell-adhesive properties and viability after polymers coating. Hence, polypyrrole- and polyaniline-coated A. mylitta silk fibers are suitable for application in cell culture and for tissue engineering, where electrical conduction properties are required. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Enhanced fatigue performance of porous coated Ti6Al4V biomedical alloy

    NASA Astrophysics Data System (ADS)

    Apachitei, I.; Leoni, A.; Riemslag, A. C.; Fratila-Apachitei, L. E.; Duszczyk, J.

    2011-05-01

    Biofunctional coatings are necessary to improve integration of titanium implants in the host tissue but they may be detrimental for the implant fatigue properties. This study presents an attempt towards enhancement of the in vitro fatigue strength of plasma electrolytic oxidation coated Ti6Al4V alloy by applying shot peening process prior to coating. The electrolytic oxidation was performed in calcium acetate and calcium glycerophosphate electrolytes that allowed formation of porous oxide coatings with high surface free energy and apatite like ability. A deformed surface layer coupled with induced residual compressive stresses seem to affect oxide growth rate and fatigue behavior of the titanium alloy.

  7. Optimization of High Porosity Thermal Barrier Coatings Generated with a Porosity Former

    NASA Astrophysics Data System (ADS)

    Medřický, Jan; Curry, Nicholas; Pala, Zdenek; Vilemova, Monika; Chraska, Tomas; Johansson, Jimmy; Markocsan, Nicolaie

    2015-04-01

    Yttria-stabilized zirconia thermal barrier coatings are extensively used in turbine industry; however, increasing performance requirements have begun to make conventional air plasma sprayed coatings insufficient for future needs. Since the thermal conductivity of bulk material cannot be lowered easily; the design of highly porous coatings may be the most efficient way to achieve coatings with low thermal conductivity. Thus the approach of fabrication of coatings with a high porosity level based on plasma spraying of ceramic particles of dysprosia-stabilized zirconia mixed with polymer particles, has been tested. Both polymer and ceramic particles melt in plasma and after impact onto a substrate they form a coating. When the coating is subjected to heat treatment, polymer burns out and a complex structure of pores and cracks is formed. In order to obtain desired porosity level and microstructural features in coatings; a design of experiments, based on changes in spray distance, powder feeding rate, and plasma-forming atmosphere, was performed. Acquired coatings were evaluated for thermal conductivity and thermo-cyclic fatigue, and their morphology was assessed using scanning electron microscopy. It was shown that porosity level can be controlled by appropriate changes in spraying parameters.

  8. Synthesis and characterization of nanomagnetite particles and their polymer coated forms.

    PubMed

    Utkan, Guldem Guven; Sayar, Filiz; Batat, Pinar; Ide, Semra; Kriechbaum, Manfred; Pişkin, Erhan

    2011-01-15

    Superparamagnetic nanoparticles were prepared by coprecipitation of ferrous (Fe(2+)) and ferric (Fe(3+)) aqueous solution by a base. Nanomagnetite particles were coated with poly(St/PEG-EEM/DMAPM) and poly(St/PEG-MA/DMAPM) layer by emulsifier-free emulsion polymerization. Chemical structure of nanoparticles was characterized by both FTIR and (1)H NMR. Particle morphologies were determined by Zeta Sizer, DLS, XRD and SAXS. Structural analysis showed that after polymer coating nanomagnetite particles kept their superparamagnetic property. Besides the synthesized magnetites, polymer coated forms of these particles are more biocompatible, well dispersable and uniform. These properties make them a very strong candidate for bioengineering applications, such as bioseparation, gene transfer. Copyright © 2010 Elsevier Inc. All rights reserved.

  9. Preparation and characterization of PTFE coating in new polymer quartz piezoelectric crystal sensor for testing liquor products

    NASA Astrophysics Data System (ADS)

    Gu, Yu; Li, Qiang

    2015-07-01

    A new method was developed based on the electron beam vacuum dispersion (EBVD) technology to prepare the PTFE polymer coating of the new polymer quartz piezoelectric crystal sensor for testing liquor products. The new method was applied in the new EBVD equipment which we designed. A real-time system monitoring the polymer coating’s thickness was designed for the new EBVD equipment according to the quartz crystal microbalance (QCM) principle, playing an important role in preparing stable and uniform PTFE polymer coatings of the same thickness. 30 pieces of PTFE polymer coatings on the surface of the quartz crystal basis were prepared with the PTFE polymer ultrafine powder (purity ≥ 99.99%) as the starting material. We obtained 30 pieces of new PTFE polymer sensors. By using scanning electron microscopy (SEM), the structure of the PTFE polymer coating’s column clusters was studied. One sample from the 30 pieces of new PTFE polymer sensors was analysed by SEM in four scales, i.e., 400×, 1000×, 10000×, and 25000×. It was shown that under the condition of high bias voltage and low bias current, uniformly PTFE polymer coating could be achieved, which indicates that the new EBVD equipment is suitable for mass production of stable and uniform polymer coating. Project supported by the National High Technology Research and Development Program of China (Grant No. 2013AA030901).

  10. Reduced bleaching in organic nanofibers by bilayer polymer/oxide coating

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Tavares, L.; Kjelstrup-Hansen, J.; Rubahn, H.-G.

    2010-05-15

    Para-hexaphenylene (p-6P) molecules exhibit a characteristic photoinduced reaction (bleaching) resulting in a decrease in luminescence intensity upon UV light exposure, which could render the technological use of the nanofibers problematic. In order to investigate the photoinduced reaction in nanofibers, optical bleaching experiments have been performed by irradiating both pristine and coated nanofibers with UV light. Oxide coating materials (SiO{sub x} and Al{sub 2}O{sub 3}) were applied onto p-6P nanofibers. These treatments caused a reduction in the bleaching reaction but in addition, the nanofiber luminescence spectrum was significantly altered. It was observed that some polymer coatings [a statistical copolymer of tetrafluoroethylenemore » and 2,2-bis-trifluoromethyl-4,5-difluoro-1,3-dioxole, P(TFE-PDD), and poly(methyl methacrylate), PMMA] do not interfere with the luminescence spectrum from the p-6P but are not effective in stopping the bleaching. Bilayer coatings with first a polymer material, which should work as a protection layer to avoid modifications of the p-6P luminescence spectrum, and second an oxide layer used as oxygen blocker were tested and it was found that a particular bilayer polymer/oxide combination results in a significant reduction in bleaching without affecting significantly the emission spectrum from the nanofibers.« less

  11. Nitrogen-Rich Porous Polymers for Carbon Dioxide and Iodine Sequestration for Environmental Remediation.

    PubMed

    Abdelmoaty, Yomna H; Tessema, Tsemre-Dingel; Choudhury, Fatema Akthar; El-Kadri, Oussama M; El-Kaderi, Hani M

    2018-05-09

    The use of fossil fuels for energy production is accompanied by carbon dioxide release into the environment causing catastrophic climate changes. Meanwhile, replacing fossil fuels with carbon-free nuclear energy has the potential to release radioactive iodine during nuclear waste processing and in case of a nuclear accident. Therefore, developing efficient adsorbents for carbon dioxide and iodine capture is of great importance. Two nitrogen-rich porous polymers (NRPPs) derived from 4-bis-(2,4-diamino-1,3,5-triazine)-benzene building block were prepared and tested for use in CO 2 and I 2 capture. Copolymerization of 1,4-bis-(2,4-diamino-1,3,5-triazine)-benzene with terephthalaldehyde and 1,3,5-tris(4-formylphenyl)benzene in dimethyl sulfoxide at 180 °C afforded highly porous NRPP-1 (SA BET = 1579 m 2 g -1 ) and NRPP-2 (SA BET = 1028 m 2 g -1 ), respectively. The combination of high nitrogen content, π-electron conjugated structure, and microporosity makes NRPPs very effective in CO 2 uptake and I 2 capture. NRPPs exhibit high CO 2 uptakes (NRPP-1, 6.1 mmol g -1 and NRPP-2, 7.06 mmol g -1 ) at 273 K and 1.0 bar. The 7.06 mmol g -1 CO 2 uptake by NRPP-2 is the second highest value reported to date for porous organic polymers. According to vapor iodine uptake studies, the polymers display high capacity and rapid reversible uptake release for I 2 (NRPP-1, 192 wt % and NRPP-2, 222 wt %). Our studies show that the green nature (metal-free) of NRPPs and their effective capture of CO 2 and I 2 make this class of porous materials promising for environmental remediation.

  12. Rapid removal of organic micropollutants from water by a porous β-cyclodextrin polymer.

    PubMed

    Alsbaiee, Alaaeddin; Smith, Brian J; Xiao, Leilei; Ling, Yuhan; Helbling, Damian E; Dichtel, William R

    2016-01-14

    The global occurrence in water resources of organic micropollutants, such as pesticides and pharmaceuticals, has raised concerns about potential negative effects on aquatic ecosystems and human health. Activated carbons are the most widespread adsorbent materials used to remove organic pollutants from water but they have several deficiencies, including slow pollutant uptake (of the order of hours) and poor removal of many relatively hydrophilic micropollutants. Furthermore, regenerating spent activated carbon is energy intensive (requiring heating to 500-900 degrees Celsius) and does not fully restore performance. Insoluble polymers of β-cyclodextrin, an inexpensive, sustainably produced macrocycle of glucose, are likewise of interest for removing micropollutants from water by means of adsorption. β-cyclodextrin is known to encapsulate pollutants to form well-defined host-guest complexes, but until now cross-linked β-cyclodextrin polymers have had low surface areas and poor removal performance compared to conventional activated carbons. Here we crosslink β-cyclodextrin with rigid aromatic groups, providing a high-surface-area, mesoporous polymer of β-cyclodextrin. It rapidly sequesters a variety of organic micropollutants with adsorption rate constants 15 to 200 times greater than those of activated carbons and non-porous β-cyclodextrin adsorbent materials. In addition, the polymer can be regenerated several times using a mild washing procedure with no loss in performance. Finally, the polymer outperformed a leading activated carbon for the rapid removal of a complex mixture of organic micropollutants at environmentally relevant concentrations. These findings demonstrate the promise of porous cyclodextrin-based polymers for rapid, flow-through water treatment.

  13. Rapid removal of organic micropollutants from water by a porous β-cyclodextrin polymer

    NASA Astrophysics Data System (ADS)

    Alsbaiee, Alaaeddin; Smith, Brian J.; Xiao, Leilei; Ling, Yuhan; Helbling, Damian E.; Dichtel, William R.

    2016-01-01

    The global occurrence in water resources of organic micropollutants, such as pesticides and pharmaceuticals, has raised concerns about potential negative effects on aquatic ecosystems and human health. Activated carbons are the most widespread adsorbent materials used to remove organic pollutants from water but they have several deficiencies, including slow pollutant uptake (of the order of hours) and poor removal of many relatively hydrophilic micropollutants. Furthermore, regenerating spent activated carbon is energy intensive (requiring heating to 500-900 degrees Celsius) and does not fully restore performance. Insoluble polymers of β-cyclodextrin, an inexpensive, sustainably produced macrocycle of glucose, are likewise of interest for removing micropollutants from water by means of adsorption. β-cyclodextrin is known to encapsulate pollutants to form well-defined host-guest complexes, but until now cross-linked β-cyclodextrin polymers have had low surface areas and poor removal performance compared to conventional activated carbons. Here we crosslink β-cyclodextrin with rigid aromatic groups, providing a high-surface-area, mesoporous polymer of β-cyclodextrin. It rapidly sequesters a variety of organic micropollutants with adsorption rate constants 15 to 200 times greater than those of activated carbons and non-porous β-cyclodextrin adsorbent materials. In addition, the polymer can be regenerated several times using a mild washing procedure with no loss in performance. Finally, the polymer outperformed a leading activated carbon for the rapid removal of a complex mixture of organic micropollutants at environmentally relevant concentrations. These findings demonstrate the promise of porous cyclodextrin-based polymers for rapid, flow-through water treatment.

  14. Protective coatings for high-temperature polymer matrix composites

    NASA Technical Reports Server (NTRS)

    Harding, David R.; Sutter, James K.; Papadopoulos, Demetrios S.

    1993-01-01

    Plasma-enhanced chemical vapor deposition was used to deposit silicon nitride on graphite-fiber-reinforced polyimide composites to protect against oxidation at elevated temperatures. The adhesion and integrity of the coating were evaluated by isothermal aging (371 C for 500 hr) and thermal cycling. The amorphous silicon nitride (a-SiN:H) coating could withstand stresses ranging from approximately 0.18 GPa (tensile) to -1.6 GPa (compressive) and provided a 30 to 80 percent reduction in oxidation-induced weight loss. The major factor influencing the effectiveness of a-SiN:H as a barrier coating against oxidation is the surface finish of the polymer composite.

  15. Implantable devices having ceramic coating applied via an atomic layer deposition method

    DOEpatents

    Liang, Xinhua; Weimer, Alan W.; Bryant, Stephanie J.

    2016-03-08

    Substrates coated with films of a ceramic material such as aluminum oxides and titanium oxides are biocompatible, and can be used in a variety of applications in which they are implanted in a living body. The substrate is preferably a porous polymer, and may be biodegradable. An important application for the ceramic-coated substrates is as a tissue engineering scaffold for forming artificial tissue.

  16. Structural changes of polymer-coated microgranules and excipients on tableting investigated by microtomography using synchrotron X-ray radiation.

    PubMed

    Kajihara, Ryusuke; Noguchi, Shuji; Iwao, Yasunori; Suzuki, Yoshio; Terada, Yasuko; Uesugi, Kentaro; Itai, Shigeru

    2015-03-15

    Multiple-unit tablets consisting of polymer-coated microgranules and excipients have a number of advantageous pharmaceutical properties. Polymer-coated microgranules are known to often lose their functionality because of damage to the polymer coating caused by tableting, and the mechanism of polymer coating damage as well as the structural changes of excipients upon tableting had been investigated but without in-situ visualization and quantitative analysis. To elucidate the mechanism of coating damage, the internal structures of multiple-unit tablets were investigated by X-ray computed microtomography using synchrotron X-rays. Cross sectional images of the tablets with sub-micron spatial resolution clearly revealed that void spaces remained around the compressed excipient particles in the tablets containing an excipient composed of cellulose and lactose (Cellactose(®) 80), whereas much smaller void spaces remained in the tablets containing an excipient made of sorbitol (Parteck(®) SI 150). The relationships between the void spaces and the physical properties of the tablets such as hardness and disintegration were investigated. Damage to the polymer coating in tablets was found mainly where polymer-coated microgranules were in direct contact with each other in both types of tablets, which could be attributed to the difference in hardness of excipient particles and the core of the polymer-coated microgranules. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Porous Architecture of SPS Thick YSZ Coatings Structured at the Nanometer Scale (~50 nm)

    NASA Astrophysics Data System (ADS)

    Bacciochini, Antoine; Montavon, Ghislain; Ilavsky, Jan; Denoirjean, Alain; Fauchais, Pierre

    2010-01-01

    Suspension plasma spraying (SPS) is a fairly recent technology that is able to process sub-micrometer-sized or nanometer-sized feedstock particles and permits the deposition of coatings thinner (from 20 to 100 μm) than those resulting from conventional atmospheric plasma spraying (APS). SPS consists of mechanically injecting within the plasma flow a liquid suspension of particles of average diameter varying between 0.02 and 1 μm. Due to the large volume fraction of the internal interfaces and reduced size of stacking defects, thick nanometer- or sub-micrometer-sized coatings exhibit better properties than conventional micrometer-sized ones (e.g., higher coefficients of thermal expansion, lower thermal diffusivity, higher hardness and toughness, better wear resistance, among other coating characteristics and functional properties). They could hence offer pertinent solutions to numerous emerging applications, particularly for energy production, energy saving, etc. Coatings structured at the nanometer scale exhibit nanometer-sized voids. Depending upon the selection of operating parameters, among which plasma power parameters (operating mode, enthalpy, spray distance, etc.), suspension properties (particle size distribution, powder mass percentage, viscosity, etc.), and substrate characteristics (topology, temperature, etc.), different coating architectures can be manufactured, from dense to porous layers, from connected to non-connected network. Nevertheless, the discrimination of porosity in different classes of criteria such as size, shape, orientation, specific surface area, etc., is essential to describe the coating architecture. Moreover, the primary steps of the coating manufacturing process affect significantly the coating porous architecture. These steps need to be further understood. Different types of imaging experiments were performed to understand, describe and quantify the pore level of thick finely structured ceramics coatings.

  18. Modeling pressure-driven assembly of polymer coated nanoparticles

    NASA Astrophysics Data System (ADS)

    Lane, J. Matthew D.; Salerno, K. Michael; Grest, Gary S.; Fan, Hongyou

    2017-06-01

    High-pressure experiments have successfully produced a variety of gold nanostructures by compressing polymer coated spherical nanoparticles. We apply atomistic simulation to understand the role of the soft polymer response in determining the pressure-driven assembly of gold nanostructures. Quasi-isentropic experiments have shown that 1D, 2D and 3D nanostructures can be formed and recovered from dynamic compression of fcc superlattices of alkanethiol-coated gold nanocrystals on Sandia's Veloce pulsed power accelerator. Molecular modeling has shown that the dimensionality of the final structures depends on the orientation of the superlattice and the uniaxial loading. We describe the role of coating ligand length and grafting density, on ligand migration and deformation processes during pressure-driven coalescence of the cores into permanent nanowires, nanosheets and 3D structures. The role of uniaxial vs isotropic pressure and the effects of compression along various superlattice orientations will be discussed. Sandia National Laboratories is a multi-mission laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  19. Influence of a Polymer Coating and the Compacting Pressure on the Magnetic Properties of Cobalt-Based Amorphous Alloys

    NASA Astrophysics Data System (ADS)

    Skulkina, N. A.; Ivanov, O. A.; Mazeeva, A. K.; Kuznetsov, P. A.; Stepanova, E. A.; Blinova, O. V.; Mikhalitsyna, E. A.; Denisov, N. D.; Chekis, V. I.

    2017-12-01

    The influence of a polymer coating applied in the manufacture of magnetic shields on magnetic properties has been studied based on the example of ribbons of a cobalt-based soft magnetic alloy (Co-Fe-Ni-Cr-Mn-Si-B) with the saturation magnetostriction close to zero. The influence of polymer coating has been separated from the effect of the compacting pressure applied upon its formation. The polymer coating was formed on the ribbon in the states with different signs of the saturation magnetostriction. It has been shown that the compacting pressure and the polymer coating have opposite effects on the properties of the ribbon and that these impacts partly level off upon the formation of the coating. The degree of the influence of the polymer coating on the magnetic properties depends on the state of the ribbon and on the sign of the saturation magnetostriction in this state.

  20. Metal coated colloidosomes as carriers for an antibiotic

    NASA Astrophysics Data System (ADS)

    Sun, Qian; Zhao, Ziyan; Hall, Elizabeth A. H.; Routh, Alexander F.

    2018-06-01

    Colloidosomes are polymer shell microcapsules. They are stable and easy to prepare and have been used to encapsulate drugs for release at specific areas in the body. Traditional polymer shell capsules cannot totally seal drugs, since they are porous and small molecules diffuse through the polymer shell. In this paper, we report a method for encapsulating an antibiotic kanamycin using gold or silver coated colloidosomes. The colloidosomes are impermeable and can be triggered using ultrasound. To investigate the application of the capsules in a biological system, Escherichia Coli (E.coli) was chosen as a model organism. After triggering, the released antibiotic, as well as the metal shell fragments, kill E.coli. Both the silver and gold shells colloidosomes are toxic to this bacterial system and the gold coated colloidosomes can load a higher concentration of kanamycin.

  1. Round-patterned ZnO nanostructure coated with siloxane-based polymer for nerve agent detection

    NASA Astrophysics Data System (ADS)

    Choi, Hyun Ji; Lee, Ji Won; Jeong, Dong-Cheol; Ha, Seonggyun; Song, Changsik; Boo, Jin-Hyo

    2018-01-01

    The alignment of zinc oxide (ZnO) nanostructures is expected to improve device sensitivities due to large surface areas which can be utilized to capture significant quantities of gas particles. In this study, we investigated patterned ZnO nanorods modified with polystyrene monolayers synthesized directly onto a quartz crystal microbalance (QCM) cell to increase the coating surface area of the sensing material. Also, we designed and synthesized a siloxane-based polymer (S1 polymer) as a sensing material. The patterned ZnO nanorods coated with S1 polymers were fabricated and used for the detection of dimethyl methylphosphonate (DMMP). The resonance frequency of QCM was shifted due to the adsorption and desorption of a compound at the surface of the modified electrodes. We have synthesized an S1 polymer that exhibited high sensitivity to DMMP. The patterned ZnO nanorods coated with the polymer also exhibited improved sensitivity due to an enhanced surface area capable of adsorbing more DMMP vapor.

  2. Synthesis and surface characterization of electroactive conducting polymers and polyurethane coatings

    NASA Astrophysics Data System (ADS)

    Vang, Chur Kalec

    The direct electrodeposition of electroactive conducting polymers (ECPs) on active metals such as iron, steel, and aluminum is complicated by the concomitant metal oxidation that occurs at the positive potentials required for polymer formation. In the case of aluminum and its alloys, the oxide layer that forms is an insulator that blocks electron transfer and impedes polymer formation and deposition. As a result, only patchy, nonuniform polymer films are obtained. Electron transfer mediation is a well-known technique for overcoming kinetic limitations of electron transfer at metal electrodes. In this dissertation, we report the use of electron transfer mediation for the direct electrodeposition of polypyrrole onto aluminum and onto Al 2024-T3 alloy. The first few chapters focus on the electrochemistry and use of Tiron RTM (4,5-dihydroxy-1,3-benzenedisulfonic acid disodium salt) as the mediator. Electroactive conductive polymers (ECPs) were also being investigated for corrosion protection of Al alloys, with a view toward replacement of chromate-based coating systems. The use of electrochemical methods clearly indicated that the electrodeposited Ppy coatings had altered the corrosion behavior of the Al alloy. Degradation mechanisms for self-priming (unicoat), high-gloss, and fluorinated polyurethane aircraft coatings exposed to QUV/H2O radiation were carried out using linear and step-scan photoacoustic (S2-PA) FTIR spectroscopy (Chapters 7--9). FTIR spectroscopic analysis indicated that, as the depth of sampling increased from film-air to film-substrate, an increase of free carbonyl components was observed. These free carbonyl groups are indicative of polyurethane components. Exposure of the polyurethane coating to prolonged periods of extreme weathering conditions indicated a loss of both polyurethane/polyurea components at the air interface, which has lead to an increase of disordered hydrogen-bonding formations. Contact angle measurement further indicated that as

  3. Efficient CO 2 capture by a task-specific porous organic polymer bifunctionalized with carbazole and triazine groups

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhu, Xiang; Mahurin, Shannon M.; An, Shu-Hao

    2014-05-02

    We synthesized a porous triazine and carbazole bifunctionalized task-specific polymer using a facile Friedel–Crafts reaction. We found that the resultant porous framework exhibited excellent CO 2 uptake (18.0 wt%, 273 K and 1 bar) and good adsorption selectivity for CO 2 over N 2.

  4. Fabrication of mullite-bonded porous SiC ceramics from multilayer-coated SiC particles through sol-gel and in-situ polymerization techniques

    NASA Astrophysics Data System (ADS)

    Ebrahimpour, Omid

    second part of the project. Alumina sol was synthesized by the hydrolysis of Aluminum isopropoxide using the Yoldas method. Alumina sol was homogenous and had a needle-like shape with a thickness of 2--3 nm. Crystalline changes during the heating process of alumina sol were studied using XRD. In addition, Fourier transform infrared (FTIR) spectroscopy was performed to identify the functional groups on the alumina sol surface as a function of temperature. In the third part of the project, the feasibility of the in-situ polymerization technique was investigated to fabricate porous SiC ceramics. In this part, the mixture of SiC and calcined alumina powders were coated by polyethylene via in-situ polymerizing referred to as the polymerization compounding process in a slurry phase. The polymerization was conducted under very moderate operational conditions using the Ziegler-Natta catalyst system. Differential scanning calorimetry (DSC) and TGA analysis and morphological studies (SEM and TEM) revealed the presence of a high density of polyethylene on the surface of SiC and alumina powders. The amount of polymer was controlled by the polymerization reaction time. Most parts of particles were coated by a thin layer of polyethylene and polymer. The porous SiC ceramics, which were fabricated by these treated particles showed higher mechanical and physical properties compared to the samples made without any treatment. The relative intensity of mullite was higher compared to the samples prepared by the traditional process. The effects of the sintering temperature, forming pressure and polymer content were also studied on the physical and mechanical properties of the final product. In the last phase of this research work, the focus of the investigation was to take advantage of both the sol-gel processing and in-situ polymerization method to develop a new process to manufacture mullite-bonded porous SiC ceramic with enhanced mechanical and physical properties. Therefore, first the Si

  5. Porous biomorphic silicon carbide ceramics coated with hydroxyapatite as prospective materials for bone implants.

    PubMed

    Gryshkov, Oleksandr; Klyui, Nickolai I; Temchenko, Volodymyr P; Kyselov, Vitalii S; Chatterjee, Anamika; Belyaev, Alexander E; Lauterboeck, Lothar; Iarmolenko, Dmytro; Glasmacher, Birgit

    2016-11-01

    Porous and cytocompatible silicon carbide (SiC) ceramics derived from wood precursors and coated with bioactive hydroxyapatite (HA) and HA-zirconium dioxide (HA/ZrO2) composite are materials with promising application in engineering of bone implants due to their excellent mechanical and structural properties. Biomorphic SiC ceramics have been synthesized from wood (Hornbeam, Sapele, Tilia and Pear) using a forced impregnation method. The SiC ceramics have been coated with bioactive HA and HA/ZrO2 using effective gas detonation deposition approach (GDD). The surface morphology and cytotoxicity of SiC ceramics as well as phase composition and crystallinity of deposited coatings were analyzed. It has been shown that the porosity and pore size of SiC ceramics depend on initial wood source. The XRD and FTIR studies revealed the preservation of crystal structure and phase composition of in the HA coating, while addition of ZrO2 to the initial HA powder resulted in significant decomposition of the final HA/ZrO2 coating and formation of other calcium phosphate phases. In turn, NIH 3T3 cells cultured in medium exposed to coated and uncoated SiC ceramics showed high re-cultivation efficiency as well as metabolic activity. The recultivation efficiency of cells was the highest for HA-coated ceramics, whereas HA/ZrO2 coating improved the recultivation efficiency of cells as compared to uncoated SiC ceramics. The GDD method allowed generating homogeneous HA coatings with no change in calcium to phosphorus ratio. In summary, porous and cytocompatible bio-SiC ceramics with bioactive coatings show a great promise in construction of light, robust, inexpensive and patient-specific bone implants for clinical application. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Dynamic-template-directed multiscale assembly for large-area coating of highly-aligned conjugated polymer thin films

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mohammadi, Erfan; Zhao, Chuankai; Meng, Yifei

    Solution processable semiconducting polymers have been under intense investigations due to their diverse applications from printed electronics to biomedical devices. However, controlling the macromolecular assembly across length scales during solution coating remains a key challenge, largely due to the disparity in timescales of polymer assembly and high-throughput printing/coating. Herein we propose the concept of dynamic templating to expedite polymer nucleation and the ensuing assembly process, inspired by biomineralization templates capable of surface reconfiguration. Molecular dynamic simulations reveal that surface reconfigurability is key to promoting template–polymer interactions, thereby lowering polymer nucleation barrier. Employing ionic-liquid-based dynamic template during meniscus-guided coating results inmore » highly aligned, highly crystalline donor-acceptor polymer thin films over large area (41cm 2) and promoted charge transport along both the polymer backbone and the π-π stacking direction in field-effect transistors. We further demonstrate that the charge transport anisotropy can be reversed by tuning the degree of polymer backbone alignment.« less

  7. Dynamic-template-directed multiscale assembly for large-area coating of highly-aligned conjugated polymer thin films

    PubMed Central

    Mohammadi, Erfan; Zhao, Chuankai; Meng, Yifei; Qu, Ge; Zhang, Fengjiao; Zhao, Xikang; Mei, Jianguo; Zuo, Jian-Min; Shukla, Diwakar; Diao, Ying

    2017-01-01

    Solution processable semiconducting polymers have been under intense investigations due to their diverse applications from printed electronics to biomedical devices. However, controlling the macromolecular assembly across length scales during solution coating remains a key challenge, largely due to the disparity in timescales of polymer assembly and high-throughput printing/coating. Herein we propose the concept of dynamic templating to expedite polymer nucleation and the ensuing assembly process, inspired by biomineralization templates capable of surface reconfiguration. Molecular dynamic simulations reveal that surface reconfigurability is key to promoting template–polymer interactions, thereby lowering polymer nucleation barrier. Employing ionic-liquid-based dynamic template during meniscus-guided coating results in highly aligned, highly crystalline donor–acceptor polymer thin films over large area (>1 cm2) and promoted charge transport along both the polymer backbone and the π–π stacking direction in field-effect transistors. We further demonstrate that the charge transport anisotropy can be reversed by tuning the degree of polymer backbone alignment. PMID:28703136

  8. Dynamic-template-directed multiscale assembly for large-area coating of highly-aligned conjugated polymer thin films

    DOE PAGES

    Mohammadi, Erfan; Zhao, Chuankai; Meng, Yifei; ...

    2017-07-13

    Solution processable semiconducting polymers have been under intense investigations due to their diverse applications from printed electronics to biomedical devices. However, controlling the macromolecular assembly across length scales during solution coating remains a key challenge, largely due to the disparity in timescales of polymer assembly and high-throughput printing/coating. Herein we propose the concept of dynamic templating to expedite polymer nucleation and the ensuing assembly process, inspired by biomineralization templates capable of surface reconfiguration. Molecular dynamic simulations reveal that surface reconfigurability is key to promoting template–polymer interactions, thereby lowering polymer nucleation barrier. Employing ionic-liquid-based dynamic template during meniscus-guided coating results inmore » highly aligned, highly crystalline donor-acceptor polymer thin films over large area (41cm 2) and promoted charge transport along both the polymer backbone and the π-π stacking direction in field-effect transistors. We further demonstrate that the charge transport anisotropy can be reversed by tuning the degree of polymer backbone alignment.« less

  9. Process optimization of ultrasonic spray coating of polymer films.

    PubMed

    Bose, Sanjukta; Keller, Stephan S; Alstrøm, Tommy S; Boisen, Anja; Almdal, Kristoffer

    2013-06-11

    In this work we have performed a detailed study of the influence of various parameters on spray coating of polymer films. Our aim is to produce polymer films of uniform thickness (500 nm to 1 μm) and low roughness compared to the film thickness. The coatings are characterized with respect to thickness, roughness (profilometer), and morphology (optical microscopy). Polyvinylpyrrolidone (PVP) is used to do a full factorial design of experiments with selected process parameters such as temperature, distance between spray nozzle and substrate, and speed of the spray nozzle. A mathematical model is developed for statistical analysis which identifies the distance between nozzle and substrate as the most significant parameter. Depending on the drying of the sprayed droplets on the substrate, we define two broad regimes, "dry" and "wet". The optimum condition of spraying lies in a narrow window between these two regimes, where we obtain a film of desired quality. Both with increasing nozzle-substrate distance and temperature, the deposition moves from a wet state to a dry regime. Similar results are also achieved for solvents with low boiling points. Finally, we study film formation during spray coating with poly (D,L-lactide) (PDLLA). The results confirm the processing knowledge obtained with PVP and indicate that the observed trends are identical for spraying of other polymer films.

  10. Dry powder process for preparing uni-tape prepreg from polymer powder coated filamentary towpregs

    NASA Technical Reports Server (NTRS)

    Wilkinson, Steven P. (Inventor); Johnston, Norman J. (Inventor); Marchello, Joseph M. (Inventor)

    1997-01-01

    A process for preparing uni-tape prepreg from polymer powder coated filamentary towpregs is provided. A plurality of polymer powder coated filamentary towpregs are provided. The towpregs are collimated so that each towpreg is parallel. A material is applied to each side of the towpreg to form a sandwich. The sandwich is heated to a temperature wherein the polymer flows and intimately contacts the filaments and pressure is repeatedly applied perpendicularly to the sandwich with a longitudinal oscillating action wherein the filaments move apart and the polymer wets the filaments forming a uni-tape prepreg. The uni-tape prepreg is subsequently cooled.

  11. Synthesis and chromatographic characterization of dextran-coated zirconia high-performance liquid chromatographic stationary phases.

    PubMed

    Dunlap, C J; Carr, P W

    1996-10-11

    Porous zirconia particles made by the oil emulsion (OE) method and the polymerization-induced colloid aggregation (PICA) method have been coated with a small, carboxymethylated (approximately 5%) dextran polymer and crosslinked in place. The parameters of the coating process (dextran concentration, adsorption time and crosslinker concentration) have all been examined and an optimum value for each determined. The coated and uncoated materials were characterized by nitrogen sorptometry and size-exclusion chromatography (SEC) using solutes (polystyrenes and dextrans) of well-defined molecular masses. Nitrogen sorptometry results show that the PICA material has a much lower pore volume and smaller pore diameter than do the OE materials. Despite this, the elution volumes of the SEC probes change very little upon polymer coating the PICA material while the OE material shows a very large change upon coating.

  12. Conjunctivodacryocystorhinostomy using a high-density porous polyethylene-coated tear drain tube.

    PubMed

    Pushker, Neelam; Khurana, Saurbhi; Shrey, Dinesh; Bajaj, Mandeep S; Chawla, Bhavna; Chandra, Mahesh

    2013-08-01

    To evaluate the outcome of conjunctivodacryocystorhinostomy using a high-density porous polyethylene (HDPP)-coated tear drain tube. Patients with epiphora due to a proximal lacrimal system block were included in a prospective interventional case study. A total of 22 eyes were treated with lacrimal bypass surgery using the HDPP-coated tube. On follow-up (12-41 months), 21 eyes had a patent well-positioned tube with subjective relief of epiphora. In one eye, a loose sleeve was noted during surgery. The tube dislodged postoperatively and was removed. A high success rate with only a few minor complications is achievable using a HDPP-coated tear drain tube for lacrimal bypass surgery. Long-term follow-up is required to look for tube blockage due to conjunctival or nasal mucosal overgrowth.

  13. Composite polymer-containing coatings on Mg alloys perspective for industry and implant surgery

    NASA Astrophysics Data System (ADS)

    Gnedenkov, S. V.; Sinebryukhov, S. L.; Mashtalyar, D. V.; Imshinetskiy, I. M.; Gnedenkov, A. S.; Minaev, A. N.

    2017-09-01

    In order to improve the corrosion resistance of magnesium alloys the ways of composite protective coating formation were developed by means of plasma electrolytic oxidation (PEO) as well as electrophoretic deposition methods. Electrochemical, corrosion, tribological, and morphological properties of the MAS magnesium alloy composite coatings were studied. The composite polymer-containing coating decrease the corrosion current density values by three orders of magnitude (Ic = 2.0 . 10-10 A/cm2), in comparison with the base PEO-layer. These polymer-containing layers enable one to expand the practical usage area of Mg alloys. The application of such coatings provides the increasing the bioactivity and regulate the corrosion rate of resorbable magnesium implants.

  14. Bone Tissue Response to Porous and Functionalized Titanium and Silica Based Coatings

    PubMed Central

    Chaudhari, Amol; Braem, Annabel; Vleugels, Jozef; Martens, Johan A.; Naert, Ignace; Cardoso, Marcio Vivan; Duyck, Joke

    2011-01-01

    Background Topography and presence of bio-mimetic coatings are known to improve osseointegration. The objective of this study was to evaluate the bone regeneration potential of porous and osteogenic coatings. Methodology Six-implants [Control (CTR); porous titanium coatings (T1, T2); thickened titanium (Ti) dioxide layer (TiO2); Amorphous Microporous Silica (AMS) and Bio-active Glass (BAG)] were implanted randomly in tibiae of 20-New Zealand white rabbits. The animals were sacrificed after 2 or 4 weeks. The samples were analyzed histologically and histomorphometrically. In the initial bone-free areas (bone regeneration areas (BRAs)), the bone area fraction (BAF) was evaluated in the whole cavity (500 µm, BAF-500), in the implant vicinity (100 µm, BAF-100) and further away (100–500 µm, BAF-400) from the implant. Bone-to-implant contact (BIC-BAA) was measured in the areas where the implants were installed in contact to the host bone (bone adaptation areas (BAAs)) to understand and compare the bone adaptation. Mixed models were used for statistical analysis. Principal Findings After 2 weeks, the differences in BAF-500 for different surfaces were not significant (p>0.05). After 4 weeks, a higher BAF-500 was observed for BAG than CTR. BAF-100 for AMS was higher than BAG and BAF-400 for BAG was higher than CTR and AMS. For T1 and AMS, the bone regeneration was faster in the 100-µm compared to the 400-µm zone. BIC-BAA for AMS and BAG was lower after 4 than 2 weeks. After 4 weeks, BIC-BAA for BAG was lower than AMS and CTR. Conclusions BAG is highly osteogenic at a distance from the implant. The porous titanium coatings didn't stimulate bone regeneration but allowed bone growth into the pores. Although AMS didn't stimulate higher bone response, it has a potential of faster bone growth in the vicinity compared to further away from the surface. BIC-BAA data were inconclusive to understand the bone adaptation. PMID:21935382

  15. Quantitative fabrication, performance optimization and comparison of PEG and zwitterionic polymer antifouling coatings.

    PubMed

    Xing, Cheng-Mei; Meng, Fan-Ning; Quan, Miao; Ding, Kai; Dang, Yuan; Gong, Yong-Kuan

    2017-09-01

    A versatile fabrication and performance optimization strategy of PEG and zwitterionic polymer coatings is developed on the sensor chip of surface plasma resonance (SPR) instrument. A random copolymer bearing phosphorylcholine zwitterion and active ester side chains (PMEN) and carboxylic PEG coatings with comparable thicknesses were deposited on SPR sensor chips via amidation coupling on the precoated polydopamine (PDA) intermediate layer. The PMEN coating showed much stronger resistance to bovine serum albumin (BSA) adsorption than PEG coating at very thin thickness (∼1nm). However, the BSA resistant efficacy of PEG coating could exceed that of PMEN due to stronger steric repelling effect when the thickness increased to 1.5∼3.3nm. Interestingly, both the PEG and PMEN thick coatings (≈3.6nm) showed ultralow fouling by BSA and bovine plasma fibrinogen (Fg). Moreover, changes in the PEG end group from -OH to -COOH, protein adsorption amount could increase by 10-fold. Importantly, the optimized PMEN and PEG-OH coatings were easily duplicated on other substrates due to universal adhesion of the PDA layer, showed excellent resistance to platelet, bacteria and proteins, and no significant difference in the antifouling performances was observed. These detailed results can explain the reported discrepancy in performances between PEG and zwitterionic polymer coatings by thickness. This facile and substrate-independent coating strategy may benefit the design and manufacture of advanced antifouling biomedical devices and long circulating nanocarriers. Prevention of biofouling is one of the biggest challenges for all biomedical applications. However, it is very difficult to fabricate a highly hydrophilic antifouling coating on inert materials or large devices. In this study, PEG and zwitterion polymers, the most widely investigated polymers with best antifouling performance, are conveniently immobilized on different kinds of substrates from their aqueous solutions by

  16. Anti-biofilm effect of a butenolide/polymer coating and metatranscriptomic analyses.

    PubMed

    Ding, Wei; Ma, Chunfeng; Zhang, Weipeng; Chiang, Hoyin; Tam, Chunkit; Xu, Ying; Zhang, Guangzhao; Qian, Pei-Yuan

    2018-01-01

    Butenolide is an environmentally friendly antifouling natural product, but its efficiency and mechanism in preventing biofilm formation have not been examined. Furthermore, controlling the release of butenolide from paints into seawater is technically challenging. A coating was developed by mixing butenolide with a biodegradable polymer, poly (ε-caprolactone)-based polyurethane, and a one-month in situ anti-biofilm test was conducted in a subtidal area. The constant release of butenolide from the surface suggested that its release was well controlled. Direct observation and confocal microscope investigation indicated that the coating was effective against both biofilm formation and attachment of large fouling organisms. Metatranscriptomic analysis of biofilm samples implied that the coating selectively inhibited the adhesion of microbes from a variety of phyla and targeted particular functional pathways including energy metabolism, drug transport and toxin release. These integrated analyses demonstrated the potential application of this butenolide/polymer coating as an anti-biofilm material.

  17. Effect of calcium phosphate surface coating on bone ingrowth onto porous-surfaced titanium alloy implants in rabbit tibiae.

    PubMed

    Yang, Cheng

    2002-04-01

    The purpose of the present study was to determine whether calcium phosphate coating has a significant impact on bone ingrowth into a porous titanium implant. Porous-surfaced titanium alloy Ti-6Al-4V implants were prepared with or without the addition of a thin surface layer of calcium phosphate applied by sol-gel coating. Implants were placed into the tibiae of 16 rabbits. Implanted sites were allowed to heal for 2 weeks, after which specimens were retrieved for morphometric assessment using backscatter scanning electron microscopy. The data collected show that there is more extensive ingrowth into the porous regions of the calcium phosphate-coated implants than into the control implants. The weighted average ingrowth for the calcium phosphate-coated implants was 2.01, whereas that for the noncoated implants was 1.49; the difference is statistically significant (P <.01). The addition of a thin layer of calcium phosphate to these implants appears to promote a more extensive implant-to-bone interface by allowing the neck regions to become intimately ingrown with bone even after only 2 weeks of initial healing. Copyright 2002 American Association of Oral and Maxillofacial Surgeons

  18. Alkyl Passivation and Amphiphilic Polymer Coating of Silicon Nanocrystals for Diagnostic Imaging

    PubMed Central

    Hessel, Colin M.; Rasch, Michael R.; Hueso, Jose L.; Goodfellow, Brian W.; Akhavan, Vahid A.; Puvanakrishnan, Priyaveena; Tunnell, James W.

    2011-01-01

    We show a method to produce biocompatible polymer-coated silicon (Si) nanocrystals for medical imaging. Silica-embedded Si nanocrystals are formed by HSQ thermolysis. The nanocrystals are then liberated from the oxide and terminated with Si-H bonds by HF etching, followed by alkyl monolayer passivation by thermal hydrosilylation. The Si nanocrystals have an average diameter of 2.1 ± 0.6 nm and photoluminesce (PL) with a peak emission wavelength of 650 nm, which lies within the transmission window of 650–900 nm that is useful for biological imaging. The hydrophobic Si nanocrystals are then coated with an amphiphilic polymer for dispersion in aqueous media with pH ranging between 7 and 10 and ionic strength between 30 mM and 2 M, while maintaining a bright and stable PL and a hydrodynamic radius of only 20 nm. Fluorescence imaging of polymer-coated Si nanocrystals in a biological tissue host is demonstrated, showing the potential for in vivo imaging. PMID:20818646

  19. Simultaneous hyperthermia and doxorubicin delivery from polymer-coated magnetite nanoparticles

    NASA Astrophysics Data System (ADS)

    Iglesias, G. R.; Delgado, A. V.; González-Caballero, F.; Ramos-Tejada, M. M.

    2017-06-01

    In this work, the hyperthermia response, (i.e., heating induced by an externally applied alternating magnetic field) and the simultaneous release of an anti-cancer drug (doxorubicin) by polymer-coated magnetite nanoparticles have been investigated. After describing the setup for hyperthermia measurements in suspensions of magnetic nanoparticles, the hyperthermia (represented by the rate of suspension heating and, ultimately, by the specific absorption rate or SAR) of magnetite nanoparticles (both bare and polymer-coated as drug nanocarriers) is discussed. The effect of the applied ac magnetic field on doxorubicin release is also studied, and it is concluded that the field does not interfere with the release process, demonstrating the double functionality of the investigated particles.

  20. Salt-Driven Deposition of Thermoresponsive Polymer-Coated Metal Nanoparticles on Solid Substrates.

    PubMed

    Zhang, Zhiyue; Maji, Samarendra; da Fonseca Antunes, André B; De Rycke, Riet; Hoogenboom, Richard; De Geest, Bruno G

    2016-06-13

    Here we report on a simple, generally applicable method for depositing metal nanoparticles on a wide variety of solid surfaces under all aqueous conditions. Noble-metal nanoparticles obtained by citrate reduction followed by coating with thermoresponsive polymers spontaneously form a monolayer-like structure on a wide variety of substrates in presence of sodium chloride whereas this phenomenon does not occur in salt-free medium. Interestingly, this phenomenon occurs below the cloud point temperature of the polymers and we hypothesize that salt ion-induced screening of electrostatic charges on the nanoparticle surface entropically favors hydrophobic association between the polymer-coated nanoparticles and a hydrophobic substrate. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Development of a smart, anti-water polyurethane polymer hair coating for style setting.

    PubMed

    Liu, Y; Liu, Y J; Hu, J; Ji, F L; Lv, J; Chen, S J; Zhu, Y

    2016-06-01

    The goal of this work was to develop a novel polyurethane polymer coating for the surface of the hair that could be used for style setting via the shape memory effect (SME). The features of the films are in accordance with conventional hair styling methods used in the laboratory. In this study, a new polyurethane polymer was synthesized; the morphology and mechanical behaviour of the coated hair were systematically investigated using a scanning electron microscope (SEM) and an Instron 5566 (with a temperature oven). The SME of the hair was tested using a 35-g weight and over five washing and drying cycles. The experimental result shows that the polyurethane polymer has effects on the mechanical behaviour of the hair. It indicates that the fixed shape (at 22°C) and recover rate (at 60°C) of different casted thickness films are similar. And the stress of the film becomes larger with increasing film thickness. Furthermore, the shape memory ability could be endowed with the hair styling using this polymer; the hair fibre could recover to the 65% of its original shape after five cycle deformation by 35 g mass under the heat-treated condition; it could recover its original setting styling even after 5th water washing and drying. The SEM results indicated that the microsurface of the hair is coated with the polymer membrane; it contributes to the shape memory ability of the coated hair to keep and recover to the original setting styling. The styling hair can return to the original hair because the polyurethane polymer can be washed out by water with suitable strength and shampoo totally which does not leave any flake. The polyurethane polymer-based hair setting agent has been developed successfully, and it could be coated evenly on the human hair with good hand feeling and SMEs. The SME is highly related to the quantity of polyurethane polymer solution, and the effect could be improved by increasing the solution quantity. The maximum deformation of the coated hair could

  2. A Dry Powder Process for Preparing Uni-Tape Prepreg from Polymer Powder Coated Filamentary Towpregs

    NASA Technical Reports Server (NTRS)

    Wilkinson, Steven P. (Inventor); Johnston, Norman J. (Inventor); Marchello, Joseph M. (Inventor)

    1995-01-01

    A process for preparing uni-tape prepreg from polymer powder coated filamentary towpregs is provided. A plurality of polymer powder coated filamentary towpregs are provided. The towpregs are collimated so that each towpreg is parallel. The sandwich is heated to a temperature wherein the polymer flows and intimately contacts the filaments and pressure is repeatedly applied perpendicularly to the sandwich with a longitudinal oscillating action wherein the filaments move apart and the polymer wets the filaments forming a uni-tape prepreg. The uni-tape prepreg is subsequently cooled.

  3. Characterization of the gas sensors based on polymer-coated resonant microcantilevers for the detection of volatile organic compounds.

    PubMed

    Dong, Ying; Gao, Wei; Zhou, Qin; Zheng, Yi; You, Zheng

    2010-06-25

    The gas sensors based on polymer-coated resonant microcantilevers for volatile organic compounds (VOCs) detection are investigated. A method to characterize the gas sensors through sensor calibration is proposed. The expressions for the estimation of the characteristic parameters are derived. The effect of the polymer coating location on the sensor's sensitivity is investigated and the formula to calculate the polymer-analyte partition coefficient without knowing the polymer coating features is presented for the first time. Three polymers: polyethyleneoxide (PEO), polyethylenevinylacetate (PEVA) and polyvinylalcohol (PVA) are used to perform the experiments. Six organic solvents: toluene, benzene, ethanol, acetone, hexane and octane are used as analytes. The response time, reversibility, hydrophilicity, sensitivity and selectivity of the polymer layers are discussed. According to the results, highly sensitive sensors for each of the analytes are proposed. Based on the characterization method, a convenient and flexible way to the construction of electric nose system by the polymer-coated resonant microcantilevers can be achieved. Copyright 2010 Elsevier B.V. All rights reserved.

  4. A nanometallic nickel-coated, glass-fibre-based structural health monitoring system for polymer composites

    NASA Astrophysics Data System (ADS)

    Balaji, R.; Sasikumar, M.

    2017-09-01

    Glass-fibre-reinforced polymer matrix composites are widely used in various industries because of their unique high strength to weight ratio. Unlike metals, strain-induced and damage states of composites are complicated to predict under real-time loading due to their anisotropic nature. With that focus, a piezoresistive nanomaterial-based structural health monitoring system for laminated polymer composites is proposed to measure the strain induced in the composite under real-time loading. Nanometallic nickel-coated glass fibres are embedded into the polymer composites to monitor the strain and damage induced in them. The nanometallic nickel is coated over the glass fibre by a dip coating technique using epoxy as the binding agent. A microcontroller-based electrical resistance measurement system is used to measure the piezoresistive variation in the coated glass fibre under real-time loading. Using the piezoresistance variation of the embedded nanometallic nickel-coated glass fibre, the real-time strain and damage induced in the composite can be correlated. The piezoresistive response of the coated glass fibre is descibed in two phases, the deformation phase and the failure phase, which clearly show the various states of strain and damage induced in the composites.

  5. Synthesis of nanostructured porous silica coatings on titanium and their cell adhesive and osteogenic differentiation properties.

    PubMed

    Inzunza, Débora; Covarrubias, Cristian; Von Marttens, Alfredo; Leighton, Yerko; Carvajal, Juan Carlos; Valenzuela, Francisco; Díaz-Dosque, Mario; Méndez, Nicolás; Martínez, Constanza; Pino, Ana María; Rodríguez, Juan Pablo; Cáceres, Mónica; Smith, Patricio

    2014-01-01

    Nanostructured porous silica coatings were synthesized on titanium by the combined sol-gel and evaporation-induced self-assembly process. The silica-coating structures were characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and nitrogen sorptometry. The effect of the nanoporous surface on apatite formation in simulated body fluid, protein adsorption, osteoblast cell adhesion behavior, and osteogenic differentiation of human bone marrow mesenchymal stem cells (hBMSCs) is reported. Silica coatings with highly ordered sub-10 nm porosity accelerate early osteoblast adhesive response, a favorable cell response that is attributed to an indirect effect due to the high protein adsorption observed on the large-specific surface area of the nanoporous coating but is also probably due to direct mechanical stimulus from the nanostructured topography. The nanoporous silica coatings, particularly those doped with calcium and phosphate, also promote the osteogenic differentiation of hBMSCs with spontaneous mineral nodule formation in basal conditions. The bioactive surface properties exhibited by the nanostructured porous silica coatings make these materials a promising alternative to improve the osseointegration properties of titanium dental implants and could have future impact on the nanoscale design of implant surfaces. Copyright © 2013 Wiley Periodicals, Inc., a Wiley Company.

  6. Long-Term Stability of Polymer-Coated Surface Transverse Wave Sensors for the Detection of Organic Solvent Vapors.

    PubMed

    Stahl, Ullrich; Voigt, Achim; Dirschka, Marian; Barié, Nicole; Richter, Christiane; Waldbaur, Ansgar; Gruhl, Friederike J; Rapp, Bastian E; Rapp, Michael; Länge, Kerstin

    2017-11-03

    Arrays with polymer-coated acoustic sensors, such as surface acoustic wave (SAW) and surface transverse wave (STW) sensors, have successfully been applied for a variety of gas sensing applications. However, the stability of the sensors' polymer coatings over a longer period of use has hardly been investigated. We used an array of eight STW resonator sensors coated with different polymers. This sensor array was used at semi-annual intervals for a three-year period to detect organic solvent vapors of three different chemical classes: a halogenated hydrocarbon (chloroform), an aliphatic hydrocarbon (octane), and an aromatic hydrocarbon (xylene). The sensor signals were evaluated with regard to absolute signal shifts and normalized signal shifts leading to signal patterns characteristic of the respective solvent vapors. No significant time-related changes of sensor signals or signal patterns were observed, i.e., the polymer coatings kept their performance during the course of the study. Therefore, the polymer-coated STW sensors proved to be robust devices which can be used for detecting organic solvent vapors both qualitatively and quantitatively for several years.

  7. Polymer coated CaAl-layered double hydroxide nanomaterials for potential calcium supplement.

    PubMed

    Kim, Tae-Hyun; Lee, Jeong-A; Choi, Soo-Jin; Oh, Jae-Min

    2014-12-05

    We have successfully prepared layered double hydroxide (LDH) nanomaterials containing calcium and aluminum ions in the framework (CaAl-LDH). The surface of CaAl-LDH was coated with enteric polymer, Eudragit®L 100 in order to protect nanomaterials from fast dissolution under gastric condition of pH 1.2. The X-ray diffraction patterns, Fourier transform infrared spectroscopy, scanning electron and transmission electron microscopy revealed that the pristine LDH was well prepared having hydrocalumite structure, and that the polymer effectively coated the surface of LDH without disturbing structure. From thermal analysis, it was determined that only a small amount (less than 1%) of polymer was coated on the LDH surface. Metal dissolution from LDH nanomaterials was significantly reduced upon Eudragit®L 100 coating at pH 1.2, 6.8 and 7.4, which simulates gastric, enteric and plasma conditions, respectively, and the dissolution effect was the most suppressed at pH 1.2. The LDH nanomaterials did not exhibit any significant cytotoxicity up to 1000 μg/mL and intracellular calcium concentration significantly increased in LDH-treated human intestinal cells. Pharmacokinetic study demonstrated absorption efficiency of Eudragit®L 100 coated LDH following oral administration to rats. Moreover, the LDH nanomaterials did not cause acute toxic effect in vivo. All the results suggest the great potential of CaAl-LDH nanomaterials as a calcium supplement.

  8. Porous polymer film calcium ion chemical sensor and method of using the same

    DOEpatents

    Porter, M.D.; Chau, L.K.

    1991-02-12

    A method of measuring calcium ions is disclosed wherein a calcium sensitive reagent, calcichrome, is immobilized on a porous polymer film. The reaction of the calcium sensitive reagent to the Ca(II) is then measured and concentration determined as a function of the reaction. 1 figure.

  9. Investigating catalyst coated membrane equilibration time for polymer electrolyte membrane fuel cell manufacturing

    NASA Astrophysics Data System (ADS)

    Cote, Philippe

    Mercedes-Benz Canada Inc., Fuel Cell Division, manufactures polymer electrolyte membrane fuel cell stacks for use in vehicles. The manufacturing line is being optimized for efficiency and quality control, in order to uphold the high standards of Mercedes-Benz Inc. vehicles. In an operating polymer electrolyte membrane fuel cell, the catalyst coated membrane facilitates the electrochemical reaction that generates electricity. This research examines the equilibration of catalyst coated membrane rolls to controlled temperature and humidity conditions, before they are used in the manufacturing of polymer electrolyte membrane fuel cells. Equilibration involves allowing the water content in the catalyst coated membrane to stabilize at the controlled conditions, in order to reduce mechanical stress in the material for better manufacturability. Initial equilibration measurements were conducted on discrete catalyst coated membrane samples using novel electronic conductivity measurements of the catalyst layer, and compared to ionic conductivity measurements of the membrane. Electronic conductivity measurements are easier to implement in the manufacturing environment than the more complex ionic conductivity measurements. When testing discrete catalyst coated membrane samples in an environmental chamber, the equilibration trends for the measured ionic and electronic conductivity signals were similar enough to permit us to adapt the electronic conductivity measurements for catalyst coated membrane in roll form. Equilibration measurements of catalyst coated membrane rolls were optimized to achieve a robust and repeatable procedure which could be used in the manufacturing environment at Mercedes-Benz Canada Inc., Fuel Cell Division.

  10. Shear strength of a three-dimensional capillary-porous titanium coating for biomedical applications

    NASA Astrophysics Data System (ADS)

    Kalita, V. I.; Komlev, D. I.; Radyuk, A. A.; Ivannikov, A. Yu; Alpatov, A. V.; Komlev, V. S.; Mamonov, V. I.; Sevostyanov, M. A.; Baikin, A. S.

    2018-04-01

    The effect of pretreatment and plasma preheating of Ti-substrate on shear strength of three-dimensional capillary porous Ti-coating was studied. After sandblasting the shear strength of the plasma sprayed coating was 200 ± 2 MPa, and after additional matting it was 68 ± 4 MPa. The use of plasma preheating of the substrates for 9 seconds decreased difference between values of the shear strength to 249 ± 17 MPa and 229 ± 16 MPa, respectively. After plasma spraying the microhardness of the surface layer of the substrate was 4.34 ± 0.35 GPa, the microhardness of the boundary between the coating and the substrate was 8.08 ± 0.45 GPa, and the microhardness of the coating was 3.48 ± 0.25 GPa. High shear strength of the coating was attributed to the activation of the substrate by means of plasma preheating and hardening of the boundary between the coating and the substrate by oxides and nitrides.

  11. In Situ Porous Structures: A Unique Polymer Erosion Mechanism in Biodegradable Dipeptide-based Polyphosphazene and Polyester Blends Producing Matrices for Regenerative Engineering

    PubMed Central

    Deng, Meng; Nair, Lakshmi S.; Nukavarapu, Syam P.; Kumbar, Sangamesh G.; Jiang, Tao; Weikel, Arlin L.; Krogman, Nicholas R.; Allcock, Harry R.; Laurencin, Cato T.

    2011-01-01

    Synthetic biodegradable polymers serve as temporary substrates that accommodate cell infiltration and tissue in-growth in regenerative medicine. To allow tissue in-growth and nutrient transport, traditional three-dimensional (3D) scaffolds must be prefabricated with an interconnected porous structure. Here we demonstrated for the first time a unique polymer erosion process through which polymer matrices evolve from a solid coherent film to an assemblage of microspheres with an interconnected 3D porous structure. This polymer system was developed on the highly versatile platform of polyphosphazene-polyester blends. Co-substituting a polyphosphazene backbone with both hydrophilic glycylglycine dipeptide and hydrophobic 4-phenylphenoxy group generated a polymer with strong hydrogen bonding capacity. Rapid hydrolysis of the polyester component permitted the formation of 3D void space filled with self-assembled polyphosphazene spheres. Characterization of such self-assembled porous structures revealed macropores (10-100 μm) between spheres as well as micro- and nanopores on the sphere surface. A similar degradation pattern was confirmed in vivo using a rat subcutaneous implantation model. 12 weeks of implantation resulted in an interconnected porous structure with 82-87% porosity. Cell infiltration and collagen tissue in-growth between microspheres observed by histology confirmed the formation of an in situ 3D interconnected porous structure. It was determined that the in situ porous structure resulted from unique hydrogen bonding in the blend promoting a three-stage degradation mechanism. The robust tissue in-growth of this dynamic pore forming scaffold attests to the utility of this system as a new strategy in regenerative medicine for developing solid matrices that balance degradation with tissue formation. PMID:21789036

  12. Porous double-layer polymer tubing for the potential use in heterogeneous continuous flow reactions.

    PubMed

    Herwig, Gordon; Hornung, Christian H; Peeters, Gary; Ebdon, Nicholas; Savage, G Paul

    2014-12-24

    Functional polymer tubing with an OD of 1/16 or 1/8 in. was fabricated by a simple polymer coextrusion process. The tubing was made of an outer impervious polypropylene layer and an inner layer, consisting of a blend of a functional polymer, polyethylene-co-methacrylic acid, and a sacrificial polymer, polystyrene. After a simple solvent leaching step using common organic solvents, the polystyrene was removed, leaving behind a porous inner layer that contains functional carboxylic acid groups, which could then be used for the immobilization of target molecules. Solution-phase reactions using amines or isocyanates have proven successful for the immobilization of a series of small molecules and polymers. This flexible multilayered functional tubing can be easily cut to the desired length and connected via standard microfluidic fittings.

  13. Redox-active porous coordination polymer based on trinuclear pivalate: Temperature-dependent crystal rearrangement and redox-behavior

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lytvynenko, Anton S.; Kiskin, Mikhail A., E-mail: mkiskin@igic.ras.ru; Dorofeeva, Victoria N.

    2015-03-15

    Linking of trinuclear pivalate Fe{sub 2}NiO(Piv){sub 6} (Piv=O{sub 2}CC(CH{sub 3}){sub 3}) by 2,6-bis(4-pyridyl)-4-(1-naphthyl)pyridine (L) resulted in formation of 1D-porous coordination polymer Fe{sub 2}NiO(Piv){sub 6}(L)·Solv, which was characterized in two forms: DMSO solvate Fe{sub 2}NiO(Piv){sub 6}(L)(DMSO)·2.5DMSO (1) or water solvate Fe{sub 2}NiO(Piv){sub 6}(L)(H{sub 2}O) (2). X-ray structure of 1 was determined. Crystal lattice of 1 at 160 K contained open channels, filled by captured solvent, while temperature growth to 296 K led to the crystal lattice rearrangement and formation of closed voids. Redox-behavior of 2 was studied by cyclic voltammetry for a solid compound, deposited on glassy-carbon electrode. Redox-activity of Lmore » preserved upon incorporation in the coordination polymer. The presence of pores in desolvated sample Fe{sub 2}NiO(Piv){sub 6}(L) was confirmed by the measurements of N{sub 2} and H{sub 2} adsorption at 77 K. Potential barriers of the different molecules diffusion through pores were estimated by the means of molecular mechanics. - Graphical abstract: Redox-behavior of 1D-porous coordination polymer Fe{sub 2}NiO(Piv){sub 6}(L)(H{sub 2}O) was studied by cyclic voltammetry in thin film, deposited on glassy-carbon electrode. Redox-activity of L preserved upon incorporation in the coordination polymer. Potential barriers of different molecules diffusion through pores were estimated by the means of molecular mechanics. - Highlights: • Porous 1D coordination polymer was synthesized. • Temperature growth led to pores closing due to crystal lattice rearrangement. • Redox-activity of ligand preserved upon incorporation into coordination polymer. • Redox-properties of solid coordination polymer were studied in thin film. • Diffusion barriers were evaluated by molecular mechanics.« less

  14. MgF2-coated porous magnesium/alumina scaffolds with improved strength, corrosion resistance, and biological performance for biomedical applications.

    PubMed

    Kang, Min-Ho; Jang, Tae-Sik; Kim, Sung Won; Park, Hui-Sun; Song, Juha; Kim, Hyoun-Ee; Jung, Kyung-Hwan; Jung, Hyun-Do

    2016-05-01

    Porous magnesium (Mg) has recently emerged as a promising biodegradable alternative to biometal for bone ingrowth; however, its low mechanical properties and high corrosion rate in biological environments remain problematic. In this study, porous magnesium was implemented in a scaffold that closely mimics the mechanical properties of human bones with a controlled degradation rate and shows good biocompatibility to match the regeneration rate of bone tissue at the affected site. The alumina-reinforced Mg scaffold was produced by spark plasma sintering and coated with magnesium fluoride (MgF2) using a hydrofluoric acid solution to regulate the corrosion rate under physiological conditions. Sodium chloride granules (NaCl), acting as space holders, were leached out to achieve porous samples (60%) presenting an average pore size of 240 μm with complete pore interconnectivity. When the alumina content increased from 0 to 5 vol%, compressive strength and stiffness rose considerably from 9.5 to 13.8 MPa and from 0.24 to 0.40 GPa, respectively. Moreover, the biological response evaluated by in vitro cell test and blood test of the MgF2-coated porous Mg composite was enhanced with better corrosion resistance compared with that of uncoated counterparts. Consequently, MgF2-coated porous Mg/alumina composites may be applied in load-bearing biodegradable implants. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Role of nano-range amphiphilic polymers in seed quality enhancement of soybean and imidacloprid retention capacity on seed coatings.

    PubMed

    Adak, Totan; Kumar, Jitendra; Shakil, Najam A; Pandey, Sushil

    2016-10-01

    Nano-size and wide-range solubility of amphiphilic polymers (having both hydrophilic and hydrophobic blocks) can improve uniformity in seed coatings. An investigation was carried out to assess the positive effect of amphiphilic polymers over hydrophilic or hydrophobic polymers as seed coating agents and pesticide carriers. Amphiphilic polymers with 127.5-354 nm micelle size were synthesized in the laboratory using polyethylene glycols and aliphatic di-acids. After 6 months of storage, germination of uncoated soybean seeds decreased drastically from 97.80 to 81.55%, while polymer-coated seeds showed 89.44-95.92% germination. Similarly, vigour index-1 was reduced from 3841.10 to 2813.06 for control seeds but ranged from 3375.59 to 3844.60 for polymer-coated seeds after 6 months. The developed imidacloprid formulations retained more pesticide on soybean seed coatings than did a commercial formulation (Gaucho(®) 600 FS). The time taken for 50% release of imidacloprid from seed coatings in water was 7.12-9.11 h for the developed formulations and 0.41 h for the commercial formulation. Nano-range amphiphilic polymers can be used to protect soybean seeds from ageing. Formulations as seed treatments may produce improved and sustained efficacy with minimum environmental contamination. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  16. Reactive polymer coatings: A robust platform towards sophisticated surface engineering for biotechnology

    NASA Astrophysics Data System (ADS)

    Chen, Hsien-Yeh

    Functionalized poly(p-xylylenes) or so-called reactive polymers can be synthesized via chemical vapor deposition (CVD) polymerization. The resulting ultra-thin coatings are pinhole-free and can be conformally deposited to a wide range of substrates and materials. More importantly, the equipped functional groups can served as anchoring sites for tailoring the surface properties, making these reactive coatings a robust platform that can deal with sophisticated challenges faced in biointerfaces. In this work presented herein, surface coatings presenting various functional groups were prepared by CVD process. Such surfaces include aldehyde-functionalized coating to precisely immobilize saccharide molecules onto well-defined areas and alkyne-functionalized coating to click azide-modified molecules via Huisgen 1,3-dipolar cycloaddition reaction. Moreover, CVD copolymerization has been conducted to prepare multifunctional coatings and their specific functions were demonstrated by the immobilization of biotin and NHS-ester molecules. By using a photodefinable coating, polyethylene oxides were immobilized onto a wide range of substrates through photo-immobilization. Spatially controlled protein resistant properties were characterized by selective adsorption of fibrinogen and bovine serum albumin as model systems. Alternatively, surface initiator coatings were used for polymer graftings of polyethylene glycol) methyl ether methacrylate, and the resultant protein- and cell- resistant properties were characterized by adsorption of kinesin motor proteins, fibrinogen, and murine fibroblasts (NIH3T3). Accessibility of reactive coatings within confined microgeometries was systematically studied, and the preparation of homogeneous polymer thin films within the inner surface of microchannels was demonstrated. Moreover, these advanced coatings were applied to develop a dry adhesion process for microfluidic devices. This process provides (i) excellent bonding strength, (ii) extended

  17. Variation in Nutrient Release of Polymer-Coated Fertilizers

    Treesearch

    Douglass F. Jacobs

    2005-01-01

    Polymer-coated fertilizers (PCF) are used primarily in horticultural plant production. However, interest in using these fertilizers in forest tree nurseries has increased over the last decade. Compared to immediately-available forms of fertilizer and other controlled-release fertilizer types, PCF tend to release nutrients in a relatively consistent flow over time. This...

  18. Polymer-coated FBG sensor for simultaneous temperature and strain monitoring in composite materials under cryogenic conditions.

    PubMed

    Sampath, Umesh; Kim, Daegil; Kim, Hyunjin; Song, Minho

    2018-01-20

    A polymer-coated fiber Bragg grating (PCFBG) is examined for real-time temperature and strain monitoring in composite materials at cryogenic temperatures. The proposed sensor enables the simultaneous measurement of temperature and strain at extremely low temperatures by tracking the changes in the reflected center wavelengths from a pair of PCFBGs embedded in a composite material. The cryogenic temperature sensing was realized by introducing polymer coatings onto bare FBGs, which resulted in high temperature sensitivity under cryogenic conditions. A comparison of wavelength responses of the Bragg grating with and without a polymer coating toward temperatures ranging from 25°C to -180°C was performed. The polymer-coated FBG exhibited a sensitivity of 48 pm/°C, which is 10 times greater than that of the bare FBGs. In addition, the encapsulation of the FBG in a capillary tube made it possible to evaluate the strain accumulated within the composite during operation under cryogenic conditions.

  19. PEDOT-PSS coated ZnO/C hierarchical porous nanorods as ultralong-life anode material for lithium ion batteries

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Xu, Gui-Liang; Li, Yan; Ma, Tianyuan

    2015-11-01

    ZnO/C hierarchical porous nanorods were synthesized through one-pot wet-chemical reaction followed by thermal calcination. It was found that ZnO/C porous nanorods are composed of numerous nanograins, exhibiting a hierarchical micro/nanostructure. In-situ synchrotron high energy X-ray diffraction study revealed that ZnO/C hierarchical porous nanorods involve a two-step reversible lithiation mechanism during charge/discharge; and part of ZnO and Zn remains at the end of the first discharge and charge process, respectively, leading to a low coulombic efficiency in the initial few cycles. The electrochemical test demonstrated that the reversible capacity and the rate performance of ZnO/C hierarchical porous nanorods anode have beenmore » greatly improved by PEDOT-PSS coating, which could maintain a reversible capacity of 623.94 mA h g(-1) after 1500 cycles at 1 C. Its excellent high rate capability and long cycle stability were attributed to the high electronic conductivity of PEDOT-PSS coating layer and the hierarchical structures of ZnO/C porous nanorods. (C) 2015 Elsevier Ltd. All rights reserved.« less

  20. Trypsin coatings on electrospun and alcohol-dispersed polymer nanofibers for trypsin digestion column

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Jun, Seung-Hyun; Chang, Mun Seock; Kim, Byoung Chan

    2010-09-15

    The construction of a trypsin reactor in a chromatography column for rapid and efficient protein digestion in proteomics is described. Electrospun and alcohol-dispersed polymer nanofibers were used for the fabrication of highly stable trypsin coating, which was prepared by a two-step process of covalent attachment and enzyme crosslinking. In a comparative study with the trypsin coatings on asspun and non-dispersed nanofibers, it has been observed that a simple step of alcohol dispersion improved not only the enzyme loading but also the performance of protein digestion. In-column digestion of enolase was successfully performed in less than twenty minutes. By applying themore » alcohol dispersion of polymer nanofibers, the bypass of samples was reduced by filling up the column with well-dispersed nanofibers, and subsequently, interactions between the protein and the enzymes were improved yielding more complete and reproducible digestions. Regardless of alcohol-dispersion or not, trypsin coating showed better digestion performance and improved performance stability under recycled uses than covalently-attached trypsin. The combination of highly stable trypsin coating and alcoholdispersion of polymer nanofibers has opened up a new potential to develop a trypsin column for on-line and automated protein digestion.« less

  1. Polymer coating of glass microballoons levitated in a focused acoustic field

    NASA Technical Reports Server (NTRS)

    Young, A. T.; Lee, M. C.; Feng, I.-A.; Elleman, D. D.; Wang, T. G.

    1982-01-01

    Inertial confinement fusion (ICF) glass microballoons (GMBs) levitated in a focusing radiator acoustic device can be coated with liquid materials by deploying the liquid into the levitation field with a stepped-horn atomizer. The GMB can be forced to the center of the coating liquid with a strong acoustically generated centering force. Water solutions of organic polymers, UV-curable liquid organic monomers, and paraffin waxes have been used to prepare solid coatings on the surface of GMBs using this technique.

  2. Normal shock wave reflection on porous compressible material

    NASA Astrophysics Data System (ADS)

    Gvozdeva, L. G.; Faresov, Iu. M.; Brossard, J.; Charpentier, N.

    The present experimental investigation of the interaction of plane shock waves in air and a rigid wall coated with flat layers of expanded polymers was conducted in a standard shock tube and a diaphragm with an initial test section pressure of 100,000 Pa. The Mach number of the incident shock wave was varied from 1.1 to 2.7; the peak pressures measured on the wall behind polyurethane at various incident wave Mach numbers are compared with calculated values, with the ideal model of propagation, and with the reflection of shock waves in a porous material that is understood as a homogeneous mixture. The effect of elasticity and permeability of the porous material structure on the rigid wall's pressure pulse parameters is qualitatively studied.

  3. Apparatus and method for depositing coating onto porous substrate

    DOEpatents

    Isenberg, Arnold O.; Zymboly, Gregory E.

    1986-01-01

    Disclosed is an apparatus for forming a chemically vapor deposited coating on a porous substrate where oxygen from a first gaseous reactant containing a source of oxygen permeates through the pores of the substrate to react with a second gaseous reactant that is present on the other side of the substrate. The apparatus includes means for controlling the pressure and flow rate of each gaseous reactant, a manometer for measuring the difference in pressure between the gaseous reactants on each side of the substrate, and means for changing the difference in pressure between the gaseous reactants. Also disclosed is a method of detecting and closing cracks in the coating by reducing the pressure difference between the two gaseous reactants whenever the pressure difference falls suddenly after gradually rising, then again increasing the pressure difference on the two gases. The attack by the by-products of the reaction on the substrate are reduced by maintaining the flow rate of the first reactant through the pores of the substrate.

  4. Polymer thin film as coating layer to prevent corrosion of metal/metal oxide film

    NASA Astrophysics Data System (ADS)

    Sarkar, Suman; Kundu, Sarathi

    2018-04-01

    Thin film of polymer is used as coating layer and the corrosion of metal/metal oxide layer is studied with the variation of the thickness of the coating layer. The thin layer of polystyrene is fabricated using spin coating method on copper oxide (CuO) film which is deposited on glass substrate using DC magnetron sputtering technique. Thickness of the polystyrene and the CuO layers are determined using X-ray reflectivity (XRR) technique. CuO thin films coated with the polystyrene layer are exposed to acetic acid (2.5 v/v% aqueous CH3COOH solution) environments and are subsequently analyzed using UV-Vis spectroscopy and atomic force microscopy (AFM). Surface morphology of the film before and after interaction with the acidic environment is determined using AFM. Results obtained from the XRR and UV-Vis spectroscopy confirm that the thin film of polystyrene acts as an anticorrosion coating layer and the strength of the coating depends upon the polymer layer thickness at a constant acid concentration.

  5. Hierarchical multifunctional composites by conformally coating aligned carbon nanotube arrays with conducting polymer.

    PubMed

    Vaddiraju, Sreeram; Cebeci, Hülya; Gleason, Karen K; Wardle, Brian L

    2009-11-01

    A novel method for the fabrication of carbon nanotube (CNT)-conducting polymer composites is demonstrated by conformally coating extremely high aspect ratio vertically aligned-CNT (A-CNT) arrays with conducting polymer via oxidative chemical vapor deposition (oCVD). A mechanical densification technique is employed that allows the spacing of the A-CNTs to be controlled, yielding a range of inter-CNT distances between 20 and 70 nm. Using this morphology control, oCVD is shown to conformally coat 8-nm-diameter CNTs having array heights up to 1 mm (an aspect ratio of 10(5)) at all inter-CNT spacings. Three phase CNT-conducting polymer nanocomposites are then fabricated by introducing an insulating epoxy via capillary-driven wetting. CNT morphology is maintained during processing, allowing quantification of direction-dependent (nonisotropic) composite properties. Electrical conductivity occurs primarily along the CNT axial direction, such that the conformal conducting polymer has little effect on the activation energy required for charge conduction. In contrast, the conducting polymer coating enhanced the conductivity in the radial direction by lowering the activation energy required for the creation of mobile charge carriers, in agreement with variable-range-hopping models. The fabrication strategy introduced here can be used to create many multifunctional materials and devices (e.g., direction-tailorable hydrophobic and highly conducting materials), including a new four-phase advanced fiber composite architecture.

  6. Extreme Activity of Drug Nanocrystals Coated with A Layer of Non-Covalent Polymers from Self-Assembled Boric Acid

    NASA Astrophysics Data System (ADS)

    Zhan, Honglei; Liang, Jun F.

    2016-12-01

    Non-covalent polymers have remarkable advantages over synthetic polymers for wide biomedical applications. In this study, non-covalent polymers from self-assembled boric acid were used as the capping reagent to replace synthetic polymers in drug crystallization. Under acidic pH, boric acid self-assembled on the surface of drug nanocrystals to form polymers with network-like structures held together by hydrogen bonds. Coating driven by boric acid self-assembly had negligible effects on drug crystallinity and structure but resulted in drug nanocrystals with excellent dispersion properties that aided in the formation of a more stable suspension. Boric acid coating improved drug stability dramatically by preventing drug molecules from undergoing water hydrolysis in a neutral environment. More importantly, the specific reactivity of orthoboric groups to diols in cell glycocalyx facilitated a rapid cross-membrane translocation of drug nanocrystals, leading to efficient intracellular drug delivery, especially on cancer cells with highly expressed sialic acids. Boric acid coated nanocrystals of camptothecin, an anticancer drug with poor aqueous solubility and stability, demonstrated extreme cytotoxic activity (IC50 < 5.0 μg/mL) to cancer cells compared to synthetic polymer coated CPT nanocrystals and free CPT. Surface coating using non-covalent polymers from self-assembled boric acid will have wide biomedical applications especially in biomaterials and drug delivery field.

  7. Extreme Activity of Drug Nanocrystals Coated with A Layer of Non-Covalent Polymers from Self-Assembled Boric Acid.

    PubMed

    Zhan, Honglei; Liang, Jun F

    2016-12-09

    Non-covalent polymers have remarkable advantages over synthetic polymers for wide biomedical applications. In this study, non-covalent polymers from self-assembled boric acid were used as the capping reagent to replace synthetic polymers in drug crystallization. Under acidic pH, boric acid self-assembled on the surface of drug nanocrystals to form polymers with network-like structures held together by hydrogen bonds. Coating driven by boric acid self-assembly had negligible effects on drug crystallinity and structure but resulted in drug nanocrystals with excellent dispersion properties that aided in the formation of a more stable suspension. Boric acid coating improved drug stability dramatically by preventing drug molecules from undergoing water hydrolysis in a neutral environment. More importantly, the specific reactivity of orthoboric groups to diols in cell glycocalyx facilitated a rapid cross-membrane translocation of drug nanocrystals, leading to efficient intracellular drug delivery, especially on cancer cells with highly expressed sialic acids. Boric acid coated nanocrystals of camptothecin, an anticancer drug with poor aqueous solubility and stability, demonstrated extreme cytotoxic activity (IC 50  < 5.0 μg/mL) to cancer cells compared to synthetic polymer coated CPT nanocrystals and free CPT. Surface coating using non-covalent polymers from self-assembled boric acid will have wide biomedical applications especially in biomaterials and drug delivery field.

  8. Extreme Activity of Drug Nanocrystals Coated with A Layer of Non-Covalent Polymers from Self-Assembled Boric Acid

    PubMed Central

    Zhan, Honglei; Liang, Jun F.

    2016-01-01

    Non-covalent polymers have remarkable advantages over synthetic polymers for wide biomedical applications. In this study, non-covalent polymers from self-assembled boric acid were used as the capping reagent to replace synthetic polymers in drug crystallization. Under acidic pH, boric acid self-assembled on the surface of drug nanocrystals to form polymers with network-like structures held together by hydrogen bonds. Coating driven by boric acid self-assembly had negligible effects on drug crystallinity and structure but resulted in drug nanocrystals with excellent dispersion properties that aided in the formation of a more stable suspension. Boric acid coating improved drug stability dramatically by preventing drug molecules from undergoing water hydrolysis in a neutral environment. More importantly, the specific reactivity of orthoboric groups to diols in cell glycocalyx facilitated a rapid cross-membrane translocation of drug nanocrystals, leading to efficient intracellular drug delivery, especially on cancer cells with highly expressed sialic acids. Boric acid coated nanocrystals of camptothecin, an anticancer drug with poor aqueous solubility and stability, demonstrated extreme cytotoxic activity (IC50 < 5.0 μg/mL) to cancer cells compared to synthetic polymer coated CPT nanocrystals and free CPT. Surface coating using non-covalent polymers from self-assembled boric acid will have wide biomedical applications especially in biomaterials and drug delivery field. PMID:27934922

  9. Formulation and evaluation of press coated tablets for pulsatile drug delivery using hydrophilic and hydrophobic polymers.

    PubMed

    Rane, Ashish Babulal; Gattani, Surendra Ganeshlal; Kadam, Vinayak Dinkar; Tekade, Avinash Ramrao

    2009-11-01

    The aim of present investigation was to develop press coated tablet for pulsatile drug delivery of ketoprofen using hydrophilic and hydrophobic polymers. The drug delivery system was designed to deliver the drug at such a time when it could be most needful to patient of rheumatoid arthritis. The press coated tablets containing ketoprofen in the inner core was formulated with an outer shell by different weight ratio of hydrophobic polymer (micronized ethyl cellulose powder) and hydrophilic polymers (glycinemax husk or sodium alginate). The release profile of press coated tablet exhibited a lag time followed by burst release, in which outer shell ruptured into two halves. Authors also investigated factors influencing on lag time such as particle size and viscosity of ethyl cellulose, outer coating weight and paddle rpm. The surface morphology of the tablet was examined by a scanning electron microscopy. Differential scanning calorimeter and Fourier transformed infrared spectroscopy study showed compatibility between ketoprofen and coating material.

  10. Porous carbon derived via KOH activation of a hypercrosslinked porous organic polymer for efficient CO{sub 2}, CH{sub 4}, H{sub 2} adsorptions and high CO{sub 2}/N{sub 2} selectivity

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Modak, Arindam; Bhaumik, Asim, E-mail: msab@iacs.res.in

    2015-12-15

    Microporous carbon having Brunauer-Emmett-Teller (BET) surface area of 2186 m{sup 2} g{sup −1} and micropore volume of 0.85 cm{sup 3} g{sup −1} has been synthesized via KOH induced high temperature carbonization of a non-conjugated hypercrosslinked organic polymer. Owing to the templating and activation by KOH, we have succeeded in making a microporous carbon from this porous polymer and the resultant carbon material showed high uptake for CO{sub 2} (7.6 mmol g{sup −1}) and CH{sub 4} (2.4 mmol g{sup −1}) at 1 atm, 273 K together with very good selectivity for the CO{sub 2}/N{sub 2} (30.2) separation. Furthermore, low pressure (1more » atm) H{sub 2} (2.6 wt%, 77 K) and water uptake (57.4 wt%, 298 K) ability of this polymer derived porous activated carbon is noteworthy. - Graphical abstract: Microporous carbon with BET surface area of 2186 m{sup 2} g{sup −1} has been synthesized via KOH activation of a porous organic polymer and it showed high uptake for CO{sub 2} (7.6 mmol g{sup −1}), CH{sub 4} (2.4 mmol g{sup −1}) and H{sub 2} (2.6 wt%) at 1 atm together with very good selectivity for CO{sub 2}. - Highlights: • Porous carbon from hypercrosslinked organic polymer. • KOH activated carbon with BET surface area 2186 m{sup 2} g{sup −1}. • High CO2 uptake (7.6 mmol g{sup −1}) and CO{sub 2}/N{sub 2} selectivity (30.2). • Porous carbon also showed high H{sub 2} (2.6 wt%) and H{sub 2}O (57.4 wt%) uptakes.« less

  11. Heterotopic bone formation around sintered porous-surfaced Ti-6Al-4V implants coated with native bone morphogenetic proteins.

    PubMed

    Simon, Ziv; Deporter, Douglas A; Pilliar, Robert M; Clokie, Cameron M

    2006-09-01

    Coating endosseous dental implants with growth factors such as bone morphogenetic proteins (BMPs) may be one way to accelerate and/or enhance the quality of osseointegration. The purpose of this study was to investigate in the murine muscle pouch model whether sintered porous-surfaced titanium alloy implants coated with BMPs would lead to heterotopic bone formation around and within the implant surface geometry. Porous-surfaced dental implants were coated with partially purified native human BMPs, with or without a carrier of Poloxamer 407 (BASF Corp., Parsippany, NJ), placed in gelatin capsules and implanted into the hindquarter muscles of mice. Mice were euthanized after 28 days. Sections of retrieved specimens were subsequently prepared for morphometric analysis of bone formation using backscatter electron microscopic images. Human BMPs, either with or without the carrier of Poloxamer 407, led to bone formation within and outside of the sintered porous implant surface. When the sintered implant surface region was subdivided into inner and outer halves, similar levels of bone ingrowth and contact were seen in the 2 halves. Evidence of bone formation to the depth of the solid implant core (i.e., the deepest level possible) also was seen. Sintered porous-surfaced dental implants can be used as substrate for partially purified BMPs in the murine muscle pouch model. With the addition of these osteoinductive factors, the porous implant surface supported bone formation within the surface porosity provided, in some instances, all the way to the solid implant core. The addition of growth factors to a sintered porous surface may be an efficient method for altering locally the healing sequence and quality of bone associated with osseointegration of bone-interfacing implants.

  12. Development and characterization of polymer-coated liposomes for vaginal delivery of sildenafil citrate.

    PubMed

    Refai, Hanan; Hassan, Doaa; Abdelmonem, Rehab

    2017-11-01

    Vaginal administration of sildenafil citrate has shown recently to develop efficiently the uterine lining with subsequent successful embryo implantation following in vitro fertilization. The aim of the present study was to develop sildenafil-loaded liposomes coated with bioadhesive polymers for enhanced vaginal retention and improved drug permeation. Three liposomal formulae were prepared by thin-film method using different phospholipid:cholesterol ratios. The optimal liposomal formulation was coated with bioadhesive polymers (chitosan and HPMC). A marked increase in liposomal size and zeta potential was observed for all coated liposomal formulations. HPMC-coated liposomes showed the greater bioadhesion and higher entrapment efficiency than chitosan-coated formulae. The in vitro release studies showed prolonged release of sildenafil from coated liposomes as compared to uncoated liposomes and sildenafil solution. Ex vivo permeation study revealed the enhanced permeation of coated relative to uncoated liposomes. Chitosan-coated formula demonstrated highest drug permeation and was thus selected for further investigations. Transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR) confirmed the successful coating of the liposomes by chitosan. Histopathological in vivo testing proved the efficacy of chitosan-coated liposomes to improve blood flow to the vaginal endometrium and to increase endometrial thickness. Chitosan-coated liposomes can be considered as potential novel drug delivery system intended for the vaginal administration of sildenafil, which would prolong system's retention at the vaginal site and enhance the permeation of sildenafil to uterine blood circulation.

  13. Coating carbon nanotubes with a polystyrene-based polymer protects against pulmonary toxicity

    PubMed Central

    2011-01-01

    Background carbon nanotubes (CNT) can have adverse effects on health. Therefore, minimizing the risk associated with CNT exposure is of crucial importance. The aim of this work was to evaluate if coating multi-walled CNT (MWCNT) with polymers could modify their toxicity, thus representing a useful strategy to decrease adverse health effects of CNT. We used industrially-produced MWCNT uncoated (NT1) or coated (50/50 wt%) with acid-based (NT2) or polystyrene-based (NT3) polymer, and exposed murine macrophages (RAW 264.7 cell line) or Balb/c mice by intratracheal administration. Biological experiments were performed both in vitro and in vivo, examining time- and dose-dependent effects of CNT, in terms of cytotoxicity, expression of genes and proteins related to oxidative stress, inflammation and tissue remodeling, cell and lung tissue morphology (optical and transmission electron microscopy), and bronchoalveolar lavage fluid content analysis. Results extensive physico-chemical characterization of MWCNT was performed, and showed, although similar dimensions for the 3 MWCNT, a much smaller specific surface area for NT2 and NT3 as compared to NT1 (54.1, 34 and 227.54 m2/g respectively), along with different surface characteristics. MWCNT-induced cytotoxicity, oxidative stress, and inflammation were increased by acid-based and decreased by polystyrene-based polymer coating both in vitro in murine macrophages and in vivo in lung of mice monitored for 6 months. Conclusions these results demonstrate that coating CNT with polymers, without affecting their intrinsic structure, may constitute a useful strategy for decreasing CNT toxicity, and may hold promise for improving occupational safety and that of general the user. PMID:21255417

  14. Coating carbon nanotubes with a polystyrene-based polymer protects against pulmonary toxicity.

    PubMed

    Tabet, Lyes; Bussy, Cyrill; Setyan, Ari; Simon-Deckers, Angélique; Rossi, Michel J; Boczkowski, Jorge; Lanone, Sophie

    2011-01-21

    carbon nanotubes (CNT) can have adverse effects on health. Therefore, minimizing the risk associated with CNT exposure is of crucial importance. The aim of this work was to evaluate if coating multi-walled CNT (MWCNT) with polymers could modify their toxicity, thus representing a useful strategy to decrease adverse health effects of CNT. We used industrially-produced MWCNT uncoated (NT1) or coated (50/50 wt%) with acid-based (NT2) or polystyrene-based (NT3) polymer, and exposed murine macrophages (RAW 264.7 cell line) or Balb/c mice by intratracheal administration. Biological experiments were performed both in vitro and in vivo, examining time- and dose-dependent effects of CNT, in terms of cytotoxicity, expression of genes and proteins related to oxidative stress, inflammation and tissue remodeling, cell and lung tissue morphology (optical and transmission electron microscopy), and bronchoalveolar lavage fluid content analysis. extensive physico-chemical characterization of MWCNT was performed, and showed, although similar dimensions for the 3 MWCNT, a much smaller specific surface area for NT2 and NT3 as compared to NT1 (54.1, 34 and 227.54 m(2)/g respectively), along with different surface characteristics. MWCNT-induced cytotoxicity, oxidative stress, and inflammation were increased by acid-based and decreased by polystyrene-based polymer coating both in vitro in murine macrophages and in vivo in lung of mice monitored for 6 months. these results demonstrate that coating CNT with polymers, without affecting their intrinsic structure, may constitute a useful strategy for decreasing CNT toxicity, and may hold promise for improving occupational safety and that of general the user.

  15. Novel composite membrane coated with a poly(diallyldimethylammonium chloride)/urushi semi-interpenetrating polymer network for non-aqueous redox flow battery application

    NASA Astrophysics Data System (ADS)

    Cho, Eunhae; Won, Jongok

    2016-12-01

    Novel composite membranes of a semi-interpenetrating network (semi-IPN) coated on the surfaces of a porous Celgard 2400 support are prepared and investigate for application in a non-aqueous redox flow battery (RFB). A natural polymer, urushi, is used for the matrix because of its high mechanical robustness, and poly(diallyldimethylammonium chloride) (PDDA) provides anionic exchange sites. The PDDA/urushi (P/U) semi-IPN film is prepared by the photo polymerization of urushiol in the presence of PDDA. The thin layer composed of the P/U semi-IPN on the porous support provides selectivity while maintaining the ion conductivity. The coulombic and energy efficiencies increase with increasing amounts of PDDA in the P/U semi-IPN layer, and the values reach 69.5% and 42.5%, respectively, for the one containing 40 wt% of PDDA. These values are substantially higher than those of the Neosepta AHA membrane and the Celgard membrane, indicating that the selective layer reduces the crossover of the redox active species through the membrane. This result implies that the formation of composite membranes using semi-IPN selective layers on the dimensionally stable porous membrane enable the successful use of a non-aqueous RFB for future energy storage systems.

  16. Hyper-crosslinked cyclodextrin porous polymer: An efficient CO 2 capturing material with tunable porosity

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Meng, Bo; Li, Haiyang; East China Univ. of Science and Technology, Shanghai

    We designed and synthesized the cyclodextrin (CD)-based hyper-crosslinked porous polymers (HCPPs) for selective CO 2 adsorption and storage. We also explored the effect of monomer size on micropore formation, and determined a feasible way to tailor the porosity of the materials during the hyper-crosslinking process.

  17. Hyper-crosslinked cyclodextrin porous polymer: An efficient CO 2 capturing material with tunable porosity

    DOE PAGES

    Meng, Bo; Li, Haiyang; East China Univ. of Science and Technology, Shanghai; ...

    2016-11-11

    We designed and synthesized the cyclodextrin (CD)-based hyper-crosslinked porous polymers (HCPPs) for selective CO 2 adsorption and storage. We also explored the effect of monomer size on micropore formation, and determined a feasible way to tailor the porosity of the materials during the hyper-crosslinking process.

  18. Undercutting of defects in thin film protective coatings on polymer surfaces exposed to atomic oxygen

    NASA Technical Reports Server (NTRS)

    Rutledge, Sharon K.; Mihelcic, Judith A.

    1989-01-01

    Protection for polymeric surfaces is needed to make them durable in the low Earth orbital environment, where oxidation by atomic oxygen is the predominant failure mechanism. Thin film coatings of oxides such as silicon dioxide are viable candidates to provide this protection, but concern has been voiced over the ability of these coatings to protect when defects are present in the coating due to surface anomalies occurring during the deposition process, handling, or micrometeoroid and debris bombardment in low Earth orbit. When a defected coating protecting a polymer substrate is exposed to atomic oxygen, the defect provides a pathway to the underlying polymer allowing oxidation and subsequent undercutting to occur. Defect undercutting was studied for sputter deposited coatings of silicon dioxide on polyimide Kapton. Preliminary results indicate that undercutting may be limited as long as the coating remains intact with the substrate. Therefore, coatings may not need to be defect free to give protection to the underlying surface.

  19. Improving the quality of polymer-coated urea with recycled plastic, proper additives, and large tablets.

    PubMed

    Yang, Yue-Chao; Zhang, Min; Li, Yuncong; Fan, Xiao-Hui; Geng, Yu-Qing

    2012-11-14

    Polymer-coated urea (PCU) has great potential for increasing crop production and enhancing nitrogen (N) fertilizer use efficiency, benefiting the ecosystem. However, current PCUs are used only in a limited market, and the main obstacle to the wider use of PCUs is high cost compared to that of conventional N fertilizers. In this study, the low cost PCU and large tablet polymer-coated urea (LTPCU) were prepared by using recycling polystyrene foam and various sealants as the coating materials. The structural and chemical characteristics of the coating shells of the coated fertilizers were examined. The N release characteristics of coated fertilizers were determined in 25 °C water under laboratory conditions. The relationship between the N release longevity and the amount of coating material and the percentage of different sealants were evaluated. The results indicated that recycling polystyrene foam was the ideal coating material of the controlled release fertilizer. The polyurethane that was synthesized by the reaction of castor oil and isocyanate was better than the wax as the additive to delay the N release rate of coated urea. The coating material used for LTPCU was 70-80% less than those used for commercial PCUs under the same N release longevity. The cost of the recycling polystyrene foam used for coating one ton of pure N of the LTPCU was about one-seventh to one-eighth of the cost of the traditional polymer used for the commercial PCU. The experimental data showed that the LTPCU with good controlled-release capacities, being economical and eco-friendly, could be promising for wide use in agriculture and horticulture.

  20. Understanding Interfacial Alignment in Solution Coated Conjugated Polymer Thin Films

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Qu, Ge; Zhao, Xikang; Newbloom, Gregory M.

    Domain alignment in conjugated polymer thin films can significantly enhance charge carrier mobility. However, the alignment mechanism during meniscus-guided solution coating remains unclear. Furthermore, interfacial alignment has been rarely studied despite its direct relevance and critical importance to charge transport. In this study, we uncover a significantly higher degree of alignment at the top interface of solution coated thin films, using a donor–acceptor conjugated polymer, poly(diketopyrrolopyrrole-co-thiopheneco- thieno[3,2- b]thiophene-co-thiophene) (DPP2T-TT), as the model system. At the molecular level, we observe in-plane π–π stacking anisotropy of up to 4.8 near the top interface with the polymer backbone aligned parallel to the coatingmore » direction. The bulk of the film is only weakly aligned with the backbone oriented transverse to coating. At the mesoscale, we observe a well-defined fibril-like morphology at the top interface with the fibril long axis pointing toward the coating direction. Significantly smaller fibrils with poor orientational order are found on the bottom interface, weakly aligned orthogonal to the fibrils on the top interface. The high degree of alignment at the top interface leads to a charge transport anisotropy of up to 5.4 compared to an anisotropy close to 1 on the bottom interface. We attribute the formation of distinct interfacial morphology to the skin-layer formation associated with high Peclet number, which promotes crystallization on the top interface while suppressing it in the bulk. As a result, we further infer that the interfacial fibril alignment is driven by the extensional flow on the top interface arisen from increasing solvent evaporation rate closer to the meniscus front.« less

  1. Understanding Interfacial Alignment in Solution Coated Conjugated Polymer Thin Films

    DOE PAGES

    Qu, Ge; Zhao, Xikang; Newbloom, Gregory M.; ...

    2017-08-01

    Domain alignment in conjugated polymer thin films can significantly enhance charge carrier mobility. However, the alignment mechanism during meniscus-guided solution coating remains unclear. Furthermore, interfacial alignment has been rarely studied despite its direct relevance and critical importance to charge transport. In this study, we uncover a significantly higher degree of alignment at the top interface of solution coated thin films, using a donor–acceptor conjugated polymer, poly(diketopyrrolopyrrole-co-thiopheneco- thieno[3,2- b]thiophene-co-thiophene) (DPP2T-TT), as the model system. At the molecular level, we observe in-plane π–π stacking anisotropy of up to 4.8 near the top interface with the polymer backbone aligned parallel to the coatingmore » direction. The bulk of the film is only weakly aligned with the backbone oriented transverse to coating. At the mesoscale, we observe a well-defined fibril-like morphology at the top interface with the fibril long axis pointing toward the coating direction. Significantly smaller fibrils with poor orientational order are found on the bottom interface, weakly aligned orthogonal to the fibrils on the top interface. The high degree of alignment at the top interface leads to a charge transport anisotropy of up to 5.4 compared to an anisotropy close to 1 on the bottom interface. We attribute the formation of distinct interfacial morphology to the skin-layer formation associated with high Peclet number, which promotes crystallization on the top interface while suppressing it in the bulk. As a result, we further infer that the interfacial fibril alignment is driven by the extensional flow on the top interface arisen from increasing solvent evaporation rate closer to the meniscus front.« less

  2. Immobilization of Hg(II) in water with polysulfide-rubber (PSR) polymer-coated activated carbon.

    PubMed

    Kim, Eun-Ah; Seyfferth, Angelia L; Fendorf, Scott; Luthy, Richard G

    2011-01-01

    An effective mercury removal method using polymer-coated activated carbon was studied for possible use in water treatment. In order to increase the affinity of activated carbon for mercury, a sulfur-rich compound, polysulfide-rubber (PSR) polymer, was effectively coated onto the activated carbon. The polymer was synthesized by condensation polymerization between sodium tetrasulfide and 1,2-dichloroethane in water. PSR-mercury interactions and Hg-S bonding were elucidated from x-ray photoelectron spectroscopy, and Fourier transform infra-red spectroscopy analyses. The sulfur loading levels were controlled by the polymer dose during the coating process and the total surface area of the activated carbon was maintained for the sulfur loading less than 2 wt%. Sorption kinetic studies showed that PSR-coated activated carbon facilitates fast reaction by providing a greater reactive surface area than PSR alone. High sulfur loading on activated carbon enhanced mercury adsorption contributing to a three orders of magnitude reduction in mercury concentration. μ-X-ray absorption near edge spectroscopic analyses of the mercury bound to activated carbon and to PSR on activated carbon suggests the chemical bond with mercury on the surface is a combination of Hg-Cl and Hg-S interaction. The pH effect on mercury removal and adsorption isotherm results indicate competition between protons and mercury for binding to sulfur at low pH. Copyright © 2010. Published by Elsevier Ltd.

  3. Can deformation of a polymer film with a rigid coating model geophysical processes?

    NASA Astrophysics Data System (ADS)

    Volynskii, A. L.; Bazhenov, S. L.

    2007-12-01

    The structural and mechanical behavior of polymer films with a thin rigid coating is analyzed. The behavior of such systems under applied stress is accompanied by the formation of a regular wavy surface relief and by regular fragmentation of the coating. The above phenomena are shown to be universal. Both phenomena (stress-induced development of a regular wavy surface relief and regular fragmentation of the coating) are provided by the specific features of mechanical stress transfer from a compliant soft support to a rigid thin coating. The above phenomena are associated with a specific structure of the system, which is referred to as “a rigid coating on a soft substratum” system (RCSS). Surface microrelief in RCSS systems is similar to the ocean floor relief in the vicinity of mid-oceanic ridges. Thus, the complex system composed of a young oceanic crust and upper Earth's mantle may be considered as typically “a solid coating on a soft substratum” system. Specific features of the ocean floor relief are analyzed in terms of the approach advanced for the description of the structural mechanical behavior of polymer films with a rigid coating. This analysis allowed to estimate the strength of an ocean floor.

  4. Assessment of osteoinduction using a porous hydroxyapatite coating prepared by micro-arc oxidation on a new titanium alloy.

    PubMed

    Jing, Wensen; Zhang, Minghua; Jin, Lei; Zhao, Jian; Gao, Qing; Ren, Min; Fan, Qingyu

    2015-12-01

    Surface modification and material improvement is now an important way to improve the osseointegration between bone and uncemented prothesis. The purpose of this study was to investigate the bone ingrowth potential of porous hydroxyapatite (HA) coatings prepared by micro-arc oxidation (MAO) on Ti-3Zr-2Sn-3Mo-25Nb, a new titanium alloy. HA-coated specimens were implanted in the left proximal femoral medullary canal of beagles for 4, 12, and 24 weeks, and uncoated specimens were implanted in the right as a control. The surface morphology and phase composition were investigated with environmental scanning electron microscopy and X-ray diffractometry. The bone ingrowth was assessed by histomorphometry. A pull-out test was performed to assess the mechanical performance of the bone-implant interface. A porous coating was well prepared on the new titanium alloy by using the MAO method. The bone-to-implant contact was significantly higher for the HA-coated group compared to that in the uncoated group. Mechanical tests showed that the HA-coated group had significantly higher maximum force at the bone-implant interface compared to the uncoated specimens. MAO is a suitable coating approach for this new titanium alloy. The HA coating prepared by this approach can significantly promote bone ingrowth and the mechanical performance of the bone-implant interface. Copyright © 2015. Published by Elsevier Ltd.

  5. Fabricating porous materials using interpenetrating inorganic-organic composite gels

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Seo, Dong-Kyun; Volosin, Alex

    Porous materials are fabricated using interpenetrating inorganic-organic composite gels. A mixture or precursor solution including an inorganic gel precursor, an organic polymer gel precursor, and a solvent is treated to form an inorganic wet gel including the organic polymer gel precursor and the solvent. The inorganic wet gel is then treated to form a composite wet gel including an organic polymer network in the body of the inorganic wet gel, producing an interpenetrating inorganic-organic composite gel. The composite wet gel is dried to form a composite material including the organic polymer network and an inorganic network component. The composite materialmore » can be treated further to form a porous composite material, a porous polymer or polymer composite, a porous metal oxide, and other porous materials.« less

  6. Hydroxyapatite-silver nanoparticles coatings on porous polyurethane scaffold.

    PubMed

    Ciobanu, Gabriela; Ilisei, Simona; Luca, Constantin

    2014-02-01

    The present paper is focused on a study regarding the possibility of obtaining hydroxyapatite-silver nanoparticle coatings on porous polyurethane scaffold. The method applied is based on a combined strategy involving hydroxyapatite biomimetic deposition on polyurethane surface using a Supersaturated Calcification Solution (SCS), combined with silver ions reduction and in-situ crystallization processes on hydroxyapatite-polyurethane surface by sample immersing in AgNO3 solution. The morphology, composition and phase structure of the prepared samples were characterized by scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDX), X-ray diffraction (XRD), UV-Vis spectroscopy and X-ray photoelectron spectroscopy (XPS) measurements. The data obtained show that a layer of hydroxyapatite was deposited on porous polyurethane support and the silver nanoparticles (average size 34.71 nm) were dispersed among and even on the hydroxyapatite crystals. Hydroxyapatite/polyurethane surface acts as a reducer and a stabilizing agent for silver ions. The surface plasmon resonance peak in UV-Vis absorption spectra showed an absorption maximum at 415 nm, indicating formation of silver nanoparticles. The hydroxyapatite-silver polyurethane scaffolds were tested against Staphylococcus aureus and Escherichia coli and the obtained data were indicative of good antibacterial properties of the materials. © 2013.

  7. Studies of SERS efficiency of gold coated porous silicon formed on rough silicon backside

    NASA Astrophysics Data System (ADS)

    Dridi, H.; Haji, L.; Moadhen, A.

    2017-12-01

    Starting from a rough backside of silicon wafer, we have formed a porous layer by electrochemical anodization and then coated by a thin film of gold. The morphological characteristics of the porous silicon and in turn the metal film are governed by the anodization process and also by the starting surface. So, in order to investigate the Plasmonic aspect of such rough surface which combines roughness inherent to the porous nature and that due to rough starting surface, we have used a dye target molecule to study its SERS signal using a porous silicon layer obtained on the rough backside surface. The use of unusual backside of silicon wafer could be, beside the others, an interesting way to made SERS effective substrate thanks to reproducible rough porous gold on porous layer from this starting face. The morphological results correspond to the silicon rough surface as a function of the crystallographic orientation showed the presence of two different substrate structure. The optical reflectivity results obtained of gold deposited on oxidized porous silicon showed a dependence of its Localized Surface Plasmon band frequency of the deposit time. SERS results, obtained for a dye target molecule (Rhodamine 6G), show a higher intensities in the case of the 〈110〉 orientation, which characterized by the higher roughness surface. Voici "the most relevant and important aspects of our work".

  8. Porous coordination polymers as novel sorption materials for heat transformation processes.

    PubMed

    Janiak, Christoph; Henninger, Stefan K

    2013-01-01

    Porous coordination polymers (PCPs)/metal-organic frameworks (MOFs) are inorganic-organic hybrid materials with a permanent three-dimensional porous metal-ligand network. PCPs or MOFs are inorganic-organic analogs of zeolites in terms of porosity and reversible guest exchange properties. Microporous water-stable PCPs with high water uptake capacity are gaining attention for low temperature heat transformation applications in thermally driven adsorption chillers (TDCs) or adsorption heat pumps (AHPs). TDCs or AHPs are an alternative to traditional air conditioners or heat pumps operating on electricity or fossil fuels. By using solar or waste heat as the operating energy TDCs or AHPs can significantly help to minimize primary energy consumption and greenhouse gas emissions generated by industrial or domestic heating and cooling processes. TDCs and AHPs are based on the evaporation and consecutive adsorption of coolant liquids, preferably water, under specific conditions. The process is driven and controlled by the microporosity and hydrophilicity of the employed sorption material. Here we summarize the current investigations, developments and possibilities of PCPs/MOFs for use in low-temperature heat transformation applications as alternative materials for the traditional inorganic porous substances like silica gel, aluminophosphates or zeolites.

  9. Modelization of three-layered polymer coated steel-strip ironing process using a neural network

    NASA Astrophysics Data System (ADS)

    Sellés, M. A.; Schmid, S. R.; Sánchez-Caballero, S.; Seguí, V. J.; Reig, M. J.; Pla, R.

    2012-04-01

    An alternative to the traditional can manufacturing process is to use plastic laminated rolled steels as base stocks. This material consist of pre-heated steel coils that are sandwiched between one or two sheets of polymer. The heated sheets are then immediately quenched, which yields a strong bond between the layers. Such polymer-coated steels were investigated by Jaworski [1,2] and Sellés [3], and found to be suitable for ironing with carefully controlled conditions. A novel multi-layer polymer coated steel has been developed for container applications. This material presents an interesting extension to previous research on polymer laminated steel in ironing, and offers several advantages over the previous material (Sellés [3]). This document shows a modelization for the ironing process (the most crucial step in can manufacturing) done by using a neural network

  10. High-Sensitivity and Low-Hysteresis Porous MIM-Type Capacitive Humidity Sensor Using Functional Polymer Mixed with TiO2 Microparticles

    PubMed Central

    Liu, Ming-Qing; Wang, Cong; Kim, Nam-Young

    2017-01-01

    In this study, a high-sensitivity and low-hysteresis porous metal–insulator–metal-type capacitive humidity sensor is investigated using a functional polymer mixed with TiO2 microparticles. The humidity sensor consists of an optimally designed porous top electrode, a functional polymer humidity sensitive layer, a bottom electrode, and a glass substrate. The porous top electrode is designed to increase the contact area between the sensing layer and water vapor, leading to high sensitivity and quick response time. The functional polymer mixed with TiO2 microparticles shows excellent hysteresis under a wide humidity-sensing range with good long-term stability. The results show that as the relative humidity ranges from 10% RH to 90% RH, the proposed humidity sensor achieves a high sensitivity of 0.85 pF/% RH and a fast response time of less than 35 s. Furthermore, the sensor shows an ultra-low hysteresis of 0.95% RH at 60% RH, a good temperature dependence, and a stable capacitance value with a maximum of 0.17% RH drift during 120 h of continuous test. PMID:28157167

  11. Hierarchically porous organic polymers: highly enhanced gas uptake and transport through templated synthesis.

    PubMed

    Chakraborty, Sanjiban; Colón, Yamil J; Snurr, Randall Q; Nguyen, SonBinh T

    2015-01-01

    Porous organic polymers (POPs) possessing meso- and micropores can be obtained by carrying out the polymerization inside a mesoporous silica aerogel template and then removing the template after polymerization. The total pore volume (tpv) and specific surface area (ssa) can be greatly enhanced by modifying the template (up to 210% increase for tpv and 73% for ssa) as well as by supercritical processing of the POPs (up to an additional 142% increase for tpv and an additional 32% for ssa) to include larger mesopores. The broad range of pores allows for faster transport of molecules through the hierarchically porous POPs, resulting in increased diffusion rates and faster gas uptake compared to POPs with only micropores.

  12. Biopharmaceutical evaluation of time-controlled press-coated tablets containing polymers to adjust drug release.

    PubMed

    Halsas, M; Ervasti, P; Veski, P; Jürjenson, H; Marvola, M

    1998-01-01

    This paper deals with press-coated modified release tablets in which the drug dose is situated in the core or is divided between the core and the coat. The coat contains polymer (sodium alginate or hydroxypropylmethyl cellulose, HPMC) to control drug release. The main objective was to investigate how the pharmacokinetic profile of the model drug could be modified by altering the proportion of the drug between the core and the coat. The effect of the amount of the polymer in the coat was also studied. Bioavailability tests were carried out on healthy volunteers. In the absorption curves of the tablets containing 50%, 67% and 80% of the drug in the core and 180 mg HPMC in the coat a bimodal profile was observed. No bimodal release pattern in the in vitro dissolution studies was found. If the whole dose was incorporated in the core the absorption curve has only one clear t(max) value at about 10 h. Doubling the amount of HPMC in the coat dramatically decreased drug absorption. It was concluded that, if a slightly reduced t(max)-value was required, the viscosity grade of HPMC used should be lowered.

  13. Role of precursors and coating polymers in sol-gel chemistry toward enhanced selectivity and efficiency in solid phase microextraction.

    PubMed

    Bagheri, Habib; Piri-Moghadam, Hamed; Ahdi, Tayebeh

    2012-09-12

    To evaluate the selectivity and efficiency of solid phase microextraction (SPME) fiber coatings, synthesized by sol-gel technology, roles of precursors and coating polymers were extensively investigated. An on-line combination of capillary microextraction (CME) technique and high performance liquid chromatography (HPLC) was set up to perform the investigation. Ten different fiber coatings were synthesized in which five of them contained only the precursor and the rests were prepared using both the precursor and coating polymer. All the coatings were chemically bonded to the inner surface of copper tubes, intended to be used as the CME device and already functionalized by self-assembly monolayers of 3-(mercaptopropyl)trimethoxysilane (3MPTMOS). The selected precursors included tetramethoxysilane (TMOS), 3-(trimethoxysilyl)propylmethacrylate (TMSPMA), 3-(triethoxysilyl)-propylamine (TMSPA), 3MPTMOS, [3-(2,3-epoxypropoxy)-propyl]-trimethoxysilane (EPPTMOS) while poly(ethyleneglycol) (PEG) was chosen as the coating polymer. The effects of different precursors on the extraction efficiency and selectivity, was studied by selecting a list of compounds ranging from non-polar to polar ones, i.e. polycyclic aromatic hydrocarbon, herbicides, estrogens and triazines. The results from CME-HPLC analysis revealed that there is no significant difference between precursors, except TMOS, in which has the lowest extraction efficiency. Most of the selected precursors have rather similar interactions toward the selected analytes which include Van der Walls, dipole-dipole and hydrogen bond while TMOS has only dipole-dipole interaction and therefore the least efficiency. TMOS is silica but the other sorbents are organically modified silica (ORMOSIL). Our investigation revealed that it is rather impossible to prepare a selective coating using conventional sol-gel methodologies. The comparison study performed among the fiber coatings contained only a precursor and those synthesized by a

  14. Microarc oxidized TiO2 based ceramic coatings combined with cefazolin sodium/chitosan composited drug film on porous titanium for biomedical applications.

    PubMed

    Wei, Daqing; Zhou, Rui; cheng, Su; Feng, Wei; Li, Baoqiang; Wang, Yaming; Jia, Dechang; Zhou, Yu; Guo, Haifeng

    2013-10-01

    Porous titanium was prepared by pressureless sintering of titanium beads with diameters of 100, 200, 400 and 600 μm. The results indicated that the mechanical properties of porous titanium changed significantly with different bead diameters. Plastic deformations such as necking phenomenon and dimple structure were observed on the fracture surface of porous titanium sintered by beads with diameter of 100 μm. However, it was difficult to find this phenomenon on the porous titanium with a titanium bead diameter of 600 μm. The microarc oxidized coatings were deposited on its surface to improve the bioactivity of porous titanium. Furthermore, the cefazolin sodium/chitosan composited films were fabricated on the microarc oxidized coatings for overcoming the inflammation due to implantation, showing good slow-release ability by addition of chitosan. And the release kinetic process of cefazolin sodium in composited films could be possibly fitted by a polynomial model. Copyright © 2013 Elsevier B.V. All rights reserved.

  15. A technique for thick polymer coating of inertial-confinement-fusion targets

    NASA Technical Reports Server (NTRS)

    Lee, M. C.; Feng, I.-A.; Wang, T. G.; Kim, H.-G.

    1983-01-01

    A technique to coat a stalk-mounted inertial-confinement fusion (ICF) target with a thick polymer layer has been successfully demonstrated. The polymer solution is first atomized, allowed to coalesce into a droplet, and positioned in a stable acoustic levitating field. The stalk-mounted ICF target is then moved into the acoustic field by manipulating a 3-D positioner to penetrate the surface membrane of the droplet, thus immersing the target in the levitated coating solution. The target inside the droplet is maintained at the center of the levitated liquid using the 3-D positional information provided by two orthogonally placed TV cameras until the drying process is completed. The basic components of the experimental apparatus, including an acoustic levitator, liquid sample deployment device, image acquisition instrumentation, and 3-D positioner, are briefly described.

  16. Coating flexible probes with an ultra fast degrading polymer to aid in tissue insertion

    PubMed Central

    Wang, Shuwu; Singh, Sagar; Damodaran, Vinod B.; Kaplan, Hilton M.; Kohn, Joachim; Shreiber, David I.; Zahn, Jeffrey D.

    2016-01-01

    We report a fabrication process for coating neural probes with an ultrafast degrading polymer to create consistent and reproducible devices for neural tissue insertion. The rigid polymer coating acts as a probe insertion aid, but resorbs within hours post-implantation. Despite the feasibility for short term neural recordings from currently available neural prosthetic devices, most of these devices suffer from long term gliosis, which isolates the probes from adjacent neurons, increasing the recording impedance and stimulation threshold. The size and stiffness of implanted probes have been identified as critical factors that lead to this long term gliosis. Smaller, more flexible probes that match the mechanical properties of brain tissue could allow better long term integration by limiting the mechanical disruption of the surrounding tissue during and after probe insertion, while being flexible enough to deform with the tissue during brain movement. However, these small flexible probes inherently lack the mechanical strength to penetrate the brain on their own. In this work, we have developed a micromolding method for coating a non-functional miniaturized SU-8 probe with an ultrafast degrading tyrosine-derived polycarbonate (E5005(2K)). Coated, non-functionalized probes of varying dimensions were reproducibly fabricated with high yields. The polymer erosion/degradation profiles of the probes were characterized in vitro. The probes were also mechanically characterized in ex vivo brain tissue models by measuring buckling and insertion forces during probe insertion. The results demonstrate the ability to produce polymer coated probes of consistent quality for future in vivo use, for example to study the effects of different design parameters that may affect tissue response during long term chronic intra-cortical microelectrode neural recordings. PMID:25681971

  17. Coating flexible probes with an ultra fast degrading polymer to aid in tissue insertion.

    PubMed

    Lo, Meng-chen; Wang, Shuwu; Singh, Sagar; Damodaran, Vinod B; Kaplan, Hilton M; Kohn, Joachim; Shreiber, David I; Zahn, Jeffrey D

    2015-04-01

    We report a fabrication process for coating neural probes with an ultrafast degrading polymer to create consistent and reproducible devices for neural tissue insertion. The rigid polymer coating acts as a probe insertion aid, but resorbs within hours post-implantation. Despite the feasibility for short term neural recordings from currently available neural prosthetic devices, most of these devices suffer from long term gliosis, which isolates the probes from adjacent neurons, increasing the recording impedance and stimulation threshold. The size and stiffness of implanted probes have been identified as critical factors that lead to this long term gliosis. Smaller, more flexible probes that match the mechanical properties of brain tissue could allow better long term integration by limiting the mechanical disruption of the surrounding tissue during and after probe insertion, while being flexible enough to deform with the tissue during brain movement. However, these small flexible probes inherently lack the mechanical strength to penetrate the brain on their own. In this work, we have developed a micromolding method for coating a non-functional miniaturized SU-8 probe with an ultrafast degrading tyrosine-derived polycarbonate (E5005(2K)). Coated, non-functionalized probes of varying dimensions were reproducibly fabricated with high yields. The polymer erosion/degradation profiles of the probes were characterized in vitro. The probes were also mechanically characterized in ex vivo brain tissue models by measuring buckling and insertion forces during probe insertion. The results demonstrate the ability to produce polymer coated probes of consistent quality for future in vivo use, for example to study the effects of different design parameters that may affect tissue response during long term chronic intra-cortical microelectrode neural recordings.

  18. Modification of polymer velvet cathode via metallic Mo coating for enhancement of high-current electron emission performances

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Xiong, Ying; Wang, Bing; Yi, Yong

    2013-09-15

    The effect of surface Mo coating on the high-current electron emission performances for polymer velvet cathode has been investigated in a diode with A-K gap of 11.5 cm by the combination of time-resolved electrical diagnostic and temporal pressure variation. Compared with uncoated polymer velvet cathode under the single-pulsed emission mode, the Mo-coated one shows lower outgassing levels (∼0.40 Pa L), slower cathode plasma expansion velocity (∼2.30 cm/μs), and higher emission stability as evidences by the change in cathode current, temporal pressure variation, and diode perveance. Moreover, after Mo coating, the emission consistency of the polymer velvet cathode between two adjacentmore » pulses is significantly improved in double-pulsed emission mode with ∼500 ns interval between two pulses, which further confirms the effectiveness of Mo coating for enhancement of electron emission performance of polymer velvet cathodes. These results should be of interest to the high-repetitive high-power microwave systems with cold cathodes.« less

  19. Construction of surface HA/TiO2 coating on porous titanium scaffolds and its preliminary biological evaluation.

    PubMed

    Chen, Hongjie; Wang, Chunli; Yang, Xiao; Xiao, Zhanwen; Zhu, Xiangdong; Zhang, Kai; Fan, Yujiang; Zhang, Xingdong

    2017-01-01

    A simple approach to fabricating hydroxyxapatite/titanium dioxide (HA/TiO 2 ) coating on porous titanium (Ti) scaffolds was developed in the present study. Surface TiO 2 layer was firstly formed on porous Ti scaffolds with multi-scale pores by acid-alkali (AA) treatment. The outer HA layer was then formed on the TiO 2 layer by subsequent pulse electrochemical deposition (ED) technique. All the three main process parameters, i.e. deposition times, current density and mass transfer mode affected the properties of the HA coating notably. Under the conditions of 90 deposition cycles, -10mA/cm 2 of pulse current density and stirring, a thin layer of homogeneous and nanorod-like HA sediments was formed on the substrate surface of porous Ti scaffolds. The results of protein adsorption and cellular experiments showed that compared to the single TiO 2 surface, the HA/TiO 2 surface allowed more adsorption of serum proteins and further enhanced the alkaline phosphatase (ALP) activity of MC3T3-E1 osteoblasts. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Improving osteointegration and osteogenesis of three-dimensional porous Ti6Al4V scaffolds by polydopamine-assisted biomimetic hydroxyapatite coating.

    PubMed

    Li, Yong; Yang, Wei; Li, Xiaokang; Zhang, Xing; Wang, Cairu; Meng, Xiangfei; Pei, Yifeng; Fan, Xiangli; Lan, Pingheng; Wang, Chunhui; Li, Xiaojie; Guo, Zheng

    2015-03-18

    Titanium alloys with various porous structures can be fabricated by advanced additive manufacturing techniques, which are attractive for use as scaffolds for bone defect repair. However, modification of the scaffold surfaces, particularly inner surfaces, is critical to improve the osteointegration of these scaffolds. In this study, a biomimetic approach was employed to construct polydopamine-assisted hydroxyapatite coating (HA/pDA) onto porous Ti6Al4V scaffolds fabricated by the electron beam melting method. The surface modification was characterized with the field emission scanning electron microscopy, energy dispersive spectroscopy, water contact angle measurement, and confocal laser scanning microscopy. Attachment and proliferation of MC3T3-E1 cells on the scaffold surface were significantly enhanced by the HA/pDA coating compared to the unmodified surfaces. Additionally, MC3T3-E1 cells grown on the HA/pDA-coated Ti6Al4V scaffolds displayed significantly higher expression of runt-related transcription factor-2, alkaline phosphatase, osteocalcin, osteopontin, and collagen type-1 compared with bare Ti6Al4V scaffolds after culture for 14 days. Moreover, microcomputed tomography analysis and Van-Gieson staining of histological sections showed that HA/pDA coating on surfaces of porous Ti6Al4V scaffolds enhanced osteointegration and significantly promoted bone regeneration after implantation in rabbit femoral condylar defects for 4 and 12 weeks. Therefore, this study provides an alternative to biofunctionalized porous Ti6Al4V scaffolds with improved osteointegration and osteogenesis functions for orthopedic applications.

  1. In silico design of porous polymer networks: high-throughput screening for methane storage materials.

    PubMed

    Martin, Richard L; Simon, Cory M; Smit, Berend; Haranczyk, Maciej

    2014-04-02

    Porous polymer networks (PPNs) are a class of advanced porous materials that combine the advantages of cheap and stable polymers with the high surface areas and tunable chemistry of metal-organic frameworks. They are of particular interest for gas separation or storage applications, for instance, as methane adsorbents for a vehicular natural gas tank or other portable applications. PPNs are self-assembled from distinct building units; here, we utilize commercially available chemical fragments and two experimentally known synthetic routes to design in silico a large database of synthetically realistic PPN materials. All structures from our database of 18,000 materials have been relaxed with semiempirical electronic structure methods and characterized with Grand-canonical Monte Carlo simulations for methane uptake and deliverable (working) capacity. A number of novel structure-property relationships that govern methane storage performance were identified. The relationships are translated into experimental guidelines to realize the ideal PPN structure. We found that cooperative methane-methane attractions were present in all of the best-performing materials, highlighting the importance of guest interaction in the design of optimal materials for methane storage.

  2. Ion Exchange Polymeric Coatings for Selective Capacitive Deionization

    NASA Astrophysics Data System (ADS)

    Jain, Amit; Kim, Jun; Li, Qilin; Verduzco, Rafael

    Capacitive deionization (CDI) is an energy-efficient technology for adsorbing and removing scalants and foulants from water by utilizing electric potential between porous carbon electrodes. Currently, industrial application of CDI is limited to low salinity waters due to the limited absorption capacities of carbon electrodes. However, CDI can potentially be used as a low-cost approach to selectively remove divalent ions from high salinity water. Divalent ions such as sulfonates and carbonates cause scaling and thus performance deterioration of membrane-based desalination systems. In this work, we investigated ion-exchange polymer coatings for use in a membrane capacitive deionization (MCDI) process for selective removal of divalent ions. Poly-Vinyl Alcohol (PVA) base polymer was crosslinked and charged using sulfo-succinic acid (SSA) to give a cation exchange layer. 50 um thick standalone polymer films had a permeability of 4.25*10-7 cm2/s for 10mM NaCl feed. Experiments on electrodes with as low as 10 υm thick coating of cation exchange polymer are under progress and will be evaluated on the basis of their selective salt removal efficiency and charge efficiency, and in future we will extend this work to sulfonated block copolymers and anion exchange polymers.

  3. Durability of an inorganic polymer concrete coating

    NASA Astrophysics Data System (ADS)

    Wasserman, Kenneth

    The objective of the research program reported in this thesis is to evaluate the durability of an inorganic polymer composite coating exposed to freeze/thaw cycling and wet-dry cycling. Freeze/thaw cycling is performed following ASTM D6944-09 Standard Practice for Resistance of Cured Coatings to Thermal Cycling and wet/dry cycling is performed following guidelines set forth in a thesis written by Ronald Garon at Rutgers University. For both sets of experiments, four coating mixture proportions were evaluated. The variables were: silica/alumina ratio, mixing protocol using high shear and normal shear mixing, curing temperatures of 70 and 120 degrees Fahrenheit and use of nano size constituent materials. The mix with highest silica/alumina ratio was designated as Mix 1 and mixes with lower ratios were designated as Mix 2 and Mix 3. Mix 4 had nano silica particles. Four prisms were used for each variable including control that had no coating. The performance of the coating was evaluated using adhesion strength measured using: ASTM D7234 Test Method for Pull-Off Strength of Coatings on Concrete Using Portable Adhesion Testers. Tests were performed after every five consecutive cycles of thermal conditioning and six consecutive cycles of wet-dry exposure. Results from the thermal cycling and wet-dry testing demonstrate that all coating formulations are durable. The minimum adhesion strength was 300 psi even though a relatively weak base concrete surface was chosen for the study. The weak surface was chosen to simulate aged concrete surfaces present in actual field conditions. Due to the inherent nature of the test procedure the variation in test results is high. However, based on the test results, high shear mixer and high temperature curing are not recommended. As expected nano size constituent materials provide better performance.

  4. Honeycomb-like porous gel polymer electrolyte membrane for lithium ion batteries with enhanced safety.

    PubMed

    Zhang, Jinqiang; Sun, Bing; Huang, Xiaodan; Chen, Shuangqiang; Wang, Guoxiu

    2014-08-29

    Lithium ion batteries have shown great potential in applications as power sources for electric vehicles and large-scale energy storage. However, the direct uses of flammable organic liquid electrolyte with commercial separator induce serious safety problems including the risk of fire and explosion. Herein, we report the development of poly(vinylidene difluoride-co-hexafluoropropylene) polymer membranes with multi-sized honeycomb-like porous architectures. The as-prepared polymer electrolyte membranes contain porosity as high as 78%, which leads to the high electrolyte uptake of 86.2 wt%. The PVDF-HFP gel polymer electrolyte membranes exhibited a high ionic conductivity of 1.03 mS cm(-1) at room temperature, which is much higher than that of commercial polymer membranes. Moreover, the as-obtained gel polymer membranes are also thermally stable up to 350 °C and non-combustible in fire (fire-proof). When applied in lithium ion batteries with LiFePO4 as cathode materials, the gel polymer electrolyte demonstrated excellent electrochemical performances. This investigation indicates that PVDF-HFP gel polymer membranes could be potentially applicable for high power lithium ion batteries with the features of high safety, low cost and good performance.

  5. Honeycomb-like porous gel polymer electrolyte membrane for lithium ion batteries with enhanced safety

    NASA Astrophysics Data System (ADS)

    Zhang, Jinqiang; Sun, Bing; Huang, Xiaodan; Chen, Shuangqiang; Wang, Guoxiu

    2014-08-01

    Lithium ion batteries have shown great potential in applications as power sources for electric vehicles and large-scale energy storage. However, the direct uses of flammable organic liquid electrolyte with commercial separator induce serious safety problems including the risk of fire and explosion. Herein, we report the development of poly(vinylidene difluoride-co-hexafluoropropylene) polymer membranes with multi-sized honeycomb-like porous architectures. The as-prepared polymer electrolyte membranes contain porosity as high as 78%, which leads to the high electrolyte uptake of 86.2 wt%. The PVDF-HFP gel polymer electrolyte membranes exhibited a high ionic conductivity of 1.03 mS cm-1 at room temperature, which is much higher than that of commercial polymer membranes. Moreover, the as-obtained gel polymer membranes are also thermally stable up to 350°C and non-combustible in fire (fire-proof). When applied in lithium ion batteries with LiFePO4 as cathode materials, the gel polymer electrolyte demonstrated excellent electrochemical performances. This investigation indicates that PVDF-HFP gel polymer membranes could be potentially applicable for high power lithium ion batteries with the features of high safety, low cost and good performance.

  6. Honeycomb-like porous gel polymer electrolyte membrane for lithium ion batteries with enhanced safety

    PubMed Central

    Zhang, Jinqiang; Sun, Bing; Huang, Xiaodan; Chen, Shuangqiang; Wang, Guoxiu

    2014-01-01

    Lithium ion batteries have shown great potential in applications as power sources for electric vehicles and large-scale energy storage. However, the direct uses of flammable organic liquid electrolyte with commercial separator induce serious safety problems including the risk of fire and explosion. Herein, we report the development of poly(vinylidene difluoride-co-hexafluoropropylene) polymer membranes with multi-sized honeycomb-like porous architectures. The as-prepared polymer electrolyte membranes contain porosity as high as 78%, which leads to the high electrolyte uptake of 86.2 wt%. The PVDF-HFP gel polymer electrolyte membranes exhibited a high ionic conductivity of 1.03 mS cm−1 at room temperature, which is much higher than that of commercial polymer membranes. Moreover, the as-obtained gel polymer membranes are also thermally stable up to 350°C and non-combustible in fire (fire-proof). When applied in lithium ion batteries with LiFePO4 as cathode materials, the gel polymer electrolyte demonstrated excellent electrochemical performances. This investigation indicates that PVDF-HFP gel polymer membranes could be potentially applicable for high power lithium ion batteries with the features of high safety, low cost and good performance. PMID:25168687

  7. A Simple and Selective Fluorescent Sensor Chip for Indole-3-Butyric Acid in Mung Bean Sprouts Based on Molecularly Imprinted Polymer Coatings

    PubMed Central

    Chang, Jiahua; Bahethan, Bota; Muhammad, Turghun; Yakup, Burabiye; Abbas, Mamatimin

    2017-01-01

    In this paper, we report the preparation of molecularly imprinted polymer coatings on quartz chips for selective solid-phase microextraction and fluorescence sensing of the auxin, indole-3-butyric acid. The multiple copolymerization method was used to prepare polymer coatings on silylated quartz chips. The polymer preparation conditions (e.g., the solvent, monomer, and cross-linker) were investigated systemically to enhance the binding performance of the imprinted coatings. Direct solid-phase fluorescence measurements on the chips facilitated monitoring changes in coating performance. The average binding capacity of an imprinted polymer coated chip was approximately 152.9 µg, which was higher than that of a non-imprinted polymer coated chip (60.8 µg); the imprinted coatings showed the highest binding to IBA among the structural analogues, indicating that the coatings possess high selectivity toward the template molecule. The developed method was used for the determination of the auxin in mung bean extraction, and the recovery was found to be in the range of 91.5% to 97.5%, with an RSD (n = 3) of less than 7.4%. Thus, the present study provides a simple method for fabricating a fluorescent sensor chip for selective analysis. PMID:28837081

  8. On-chip sample pretreatment using a porous polymer monolithic column for solid-phase microextraction and chemiluminescence determination of catechins in green tea.

    PubMed

    Lin, Ling; Chen, Hui; Wei, Huibin; Wang, Feng; Lin, Jin-Ming

    2011-10-21

    A porous polymer monolithic column for solid-phase microextraction and chemiluminescence detection was integrated into a simple microfluidic chip for the extraction and determination of catechins in green tea. The porous polymer was prepared by poly(glycidyl methacrylate-co-ethylene dimethacrylate) and modified with ethylenediamine. Catechins can be concentrated in the porous polymer monolithic column and react with potassium permanganate to give chemiluminescence. The microfluidic chip is reusable with high sensitivity and very low reagent consumption. The on-line preconcentration and detection can be realized without an elution step. The enrichment factor was calculated to be about 20 for catechins. The relative chemiluminescence intensity increased linearly with concentration of catechin from 5.0 × 10(-9) to 1.0 × 10(-6) M and the limit of detection was 1.0 × 10(-9) M. The proposed method was applied to determine catechin in green tea. The recoveries are from 90% to 110% which benefits the actual application for green tea samples.

  9. Tough bonding of hydrogels to diverse non-porous surfaces

    NASA Astrophysics Data System (ADS)

    Yuk, Hyunwoo; Zhang, Teng; Lin, Shaoting; Parada, German Alberto; Zhao, Xuanhe

    2016-02-01

    In many animals, the bonding of tendon and cartilage to bone is extremely tough (for example, interfacial toughness ~800 J m-2 refs ,), yet such tough interfaces have not been achieved between synthetic hydrogels and non-porous surfaces of engineered solids. Here, we report a strategy to design tough transparent and conductive bonding of synthetic hydrogels containing 90% water to non-porous surfaces of diverse solids, including glass, silicon, ceramics, titanium and aluminium. The design strategy is to anchor the long-chain polymer networks of tough hydrogels covalently to non-porous solid surfaces, which can be achieved by the silanation of such surfaces. Compared with physical interactions, the chemical anchorage results in a higher intrinsic work of adhesion and in significant energy dissipation of bulk hydrogel during detachment, which lead to interfacial toughness values over 1,000 J m-2. We also demonstrate applications of robust hydrogel-solid hybrids, including hydrogel superglues, mechanically protective hydrogel coatings, hydrogel joints for robotic structures and robust hydrogel-metal conductors.

  10. Highly porous organic polymers bearing tertiary amine group and their exceptionally high CO{sub 2} uptake capacities

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gomes, Ruth; Bhaumik, Asim, E-mail: msab@iacs.res.in

    2015-02-15

    We report a very simple and unique strategy for synthesis of a tertiary amine functionalized high surface area porous organic polymer (POP) PDVTA-1 through the co-polymerization of monomers divinylbenzene (DVB) and triallylamine (TAA) under solvothermal reaction conditions. Two different PDVTA-1 samples have been synthesized by varying the molar ratio of the monomers. The porous polymeric materials have been thoroughly characterized by solid state {sup 13}C CP MAS-NMR, FT-IR and UV–vis spectroscopy, N{sub 2} sorption, HR TEM and FE SEM to understand its chemical environment, nanostructure, bonding, morphology and related surface properties. PDVTA-1 with higher amine content (DVB/TAA=4.0) showed exceptionally highmore » CO{sub 2} uptake capacity of 85.8 wt% (19.5 mmol g{sup −1}) at 273 K and 43.69 wt% (9.93 mmol g{sup −1}) at 298 K under 3 bar pressure, whereas relatively low amine loaded material (DVB/TAA=7.0) shows uptake capacity of 59.2 wt% (13.45 mmol g{sup −1}) at 273 K and 34.36 wt% (7.81 mmol g{sup −1}) at 298 K. Highly porous nanostructure together with very high surface area and basicity at the surface due to the presence of abundant basic tertiary amine N-sites in the framework of PDVTA-1 could be responsible for very high CO{sub 2} adsorption. - Graphical abstract: Exceptionally high CO2 uptake (85.8 wt % at 273 K) has been observed over a high surface area porous organic polymer PDVTA-1 synthesized through copolymerization of divinylbenzene and triallyl amine. - Highlights: • Designing the synthesis of a new N-rich cross-linked porous organic polymer PDVTA-1. • PDVTA-1 showed mesoporosity with very high surface area of 903 m{sup 2} g{sup −1}. • High surface area and presence of basic sites facilitates the CO{sub 2} uptake. • PDVTA-1 showed exceptionally high CO{sub 2} adsorption capacity of 85.8 wt% at 273 K, 3 bar pressure.« less

  11. Highly selective stir bar coated with dummy molecularly imprinted polymers for trace analysis of bisphenol A in milk.

    PubMed

    Zhan, Wen; Wei, Fangdi; Xu, Guanhong; Cai, Zheng; Du, Shuhu; Zhou, Xuemin; Li, Fei; Hu, Qin

    2012-04-01

    A water compatible molecularly imprinted polymers (MIPs) coated stir bar for bisphenol A(BPA) was prepared with 3,3',5,5'-tetrabromobisphenol A as the dummy template molecule in this study. The dummy molecularly imprinted polymers coated stir bar (DMIPs-SB) showed better selectivity than the bars coated with polydimethylsiloxane or non-imprinted polymers when used to extract BPA and its three analogues. The saturated adsorption amount of the DMIPs coating was 3.0 times over that of the non-imprinted polymers coating. To achieve the optimum extraction performance, several parameters, including extraction and desorption time, pH value, adsorption temperature and stirring speed were investigated. The high-performance liquid chromatography combined with the DMIPs-SB was employed in the analysis of BPA in aqueous solution. The linear range of BPA concentration in aqueous medium was 0.0228-2.28 ng/mL with correlation coefficient of 0.9994 and the detection limit was about 6.84 × 10(-3) ng/mL based on three times ratio of signal to noise. This method was directly applied to the determination of trace BPA in milk with satisfactory results. © 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Repair of oxidation protection coatings on carbon-carbon using preceramic polymers

    NASA Technical Reports Server (NTRS)

    Schwab, Stuart T.; Graef, Renee C.

    1991-01-01

    The paper describes a field-applicable technique for the repair of damage to SiC protective coatings on carbon/carbon composites, using commercial preceramic polymers, such as perhydropolysilazane developed by the Southwest Research Institute and several commercial polymers (NICALON, PS110, PS116, PS117, NCP-200, and PHPS were tested). After being applied on the damaged panel and oxidized at 1400 C, these polymers form either SiC or Si3N4 (or a mixture of both). It was found that impact damaged carbon/carbon specimens repaired with perhydropolysilazane exhibit substantial oxidation resistance. Many of the other tested preceramic polymer were found to be unsuitable for the purpose of repair due to either low ceramic yield, foaming, or intumescence.

  13. Porous, Hyper-cross-linked, Three-Dimensional Polymer as Stable, High Rate Capability Electrode for Lithium-Ion Battery.

    PubMed

    Mukherjee, Debdyuti; Gowda Y K, Guruprasada; Makri Nimbegondi Kotresh, Harish; Sampath, S

    2017-06-14

    Organic materials containing active carbonyl groups have attracted considerable attention as electrodes in Li-ion batteries due to their reversible redox activity, ability to retain capacity, and, in addition, their ecofriendly nature. Introduction of porosity will help accommodate as well as store small ions and molecules reversibly. In the present work, we introduce a mesoporous triptycene-related, rigid network polymer with high specific surface area as an electrode material for rechargeable Li-ion battery. The designed polymer with a three-dimensional (3D), rigid porous network allows free movement of ions/electrolyte as well as helps in interacting with the active anhydride moieties (containing two carbonyl groups). Considerable intake of Li + ions giving rise to very high specific capacity of 1100 mA h g -1 at a discharge current of 50 mA g -1 and ∼120 mA h g -1 at a high discharge current of 3 A g -1 are observed with excellent cyclability up to 1000 cycles. This remarkable rate capability, which is one of the highest among the reported organic porous polymers to date, makes the triptycene-related rigid 3D network a very good choice for Li-ion batteries and opens up a new method to design polymer-based electrode materials for metal-ion battery technology.

  14. Laser cladding of Inconel 625-based composite coatings reinforced by porous chromium carbide particles

    NASA Astrophysics Data System (ADS)

    Janicki, Damian

    2017-09-01

    Inconel 625/Cr3C2 composite coatings were produced via a laser cladding process using Cr3C2 reinforcing particles presenting an open porosity of about 60%. A laser cladding system used consisted of a direct diode laser with a rectangular beam spot and the top-hat beam profile, and an off-axis powder injection nozzle. The microstructural characteristics of the coatings was investigated with the use of scanning electron microscopy and X-ray diffraction. A complete infiltration of the porous structure of Cr3C2 reinforcing particles and low degree of their dissolution have been achieved in a very narrow range of processing parameters. Crack-free composite coatings having a uniform distribution of the Cr3C2 particles and their fraction up to 36 vol% were produced. Comparative erosion tests between the Inconel 625/Cr3C2 composite coatings and the metallic Inconel 625 coatings were performed following the ASTM G 76 standard test method. It was found that the composite coatings have a significantly higher erosion resistance to that of metallic coatings for both 30° and 90° impingement angles. Additionally, the erosion performances of composite coatings were similar for both the normal and oblique impact conditions. The erosive wear behaviour of composite coatings is discussed and related to the unique microstructure of these coatings.

  15. Polymeric coating of surface modified nitinol stent with POSS-nanocomposite polymer.

    PubMed

    Bakhshi, Raheleh; Darbyshire, Arnold; Evans, James Eaton; You, Zhong; Lu, Jian; Seifalian, Alexander M

    2011-08-01

    Stent angioplasty is a successful treatment for arterial occlusion, particularly in coronary artery disease. The clinical communities were enthusiastic about the use of drug-eluting stents; however, these stents have a tendency to be a contributory factor towards late stage thrombosis, leading to mortality in a significant number of patients per year. This work presents an innovative approach in self-expanding coronary stents preparation. We developed a new nanocomposite polymer based on polyhedral oligomeric silsesquioxanes (POSS) and poly(carbonate-urea)urethane (PCU), which is an antithrombogenic and a non-biodegradable polymer with in situ endothelialization properties. The aim of this work is to coat a NiTi stent alloy with POSS-PCU. In prolonged applications in the human body, the corrosion of the NiTi alloy can result in the release of deleterious ions which leads to unwanted biological reactions. Coating the nitinol (NiTi) surface with POSS-PCU can enhance surface resistance and improve biocompatibility. Electrohydrodynamic spraying was used as the polymer deposition process and thus a few experiments were carried out to compare this process with casting. Prior to deposition the NiTi has been surface modified. The peel strength of the deposit was studied before and after degradation of the coating. It is shown that the surface modification enhances the peel strength by 300%. It is also indicated how the adhesion strength of the POSS-PCU coating changes post-exposure to physiological solutions comprised of hydrolytic, oxidative, peroxidative and biological media. This part of the study shows that the modified NiTi presents far greater resistance to decay in peel strength compared to the non-modified NiTi. Copyright © 2011 Elsevier B.V. All rights reserved.

  16. Electrochemical impedance spectroscopy (EIS) as a tool for measuring corrosion of polymer-coated fasteners used in treated wood

    Treesearch

    Samuel L. Zelinka; Lorraine Ortiz-Candelaria; Donald S. Stone; Douglas R. Rammer

    2009-01-01

    Currently, many of the polymer-coated fasteners on the market are designed for improved corrosion performance in treated wood; yet, there is no way to evaluate their corrosion performance. In this study, a common technique for measuring the corrosion performance of polymer-coated metals, electrochemical impedance spectroscopy (EIS), was used to evaluate commercial...

  17. Charging/discharge events in coated spacecraft polymers during electron beam irradiation in a scanning electron microscope

    NASA Astrophysics Data System (ADS)

    Czeremuszkin, G.; Latrèche, M.; Wertheimer, M. R.

    2001-12-01

    Spacecraft, such as those operating in geosynchronous orbit (GEO), can be subjected to intense irradiation by charged particles, for example high-energy (e.g. 20 keV) electrons. The surfaces of dielectric materials (for example, polymers used as "thermal blankets") can therefore become potential sites for damaging electrostatic discharge (ESD) pulse events. We simulate these conditions by examining small specimens of three relevant polymers (polyimide, polyester and fluoropolymer), both bare and coated, in a scanning electron microscope (SEM). The coatings examined include commercial indium-tin oxide (ITO), and thin films of SiO 2 and a-Si:H deposited by plasma-enhanced chemical vapor deposition (PECVD). All coatings are found to greatly modify the observed ESD behavior, compared with that of the bare polymer counterparts. These observations are explained in terms of the model for ESD pulses proposed by Frederickson.

  18. Critical conditions of polymer adsorption and chromatography on non-porous substrates.

    PubMed

    Cimino, Richard T; Rasmussen, Christopher J; Brun, Yefim; Neimark, Alexander V

    2016-07-15

    We present a novel thermodynamic theory and Monte Carlo simulation model for adsorption of macromolecules to solid surfaces that is applied for calculating the chain partition during separation on chromatographic columns packed with non-porous particles. We show that similarly to polymer separation on porous substrates, it is possible to attain three chromatographic modes: size exclusion chromatography at very weak or no adsorption, liquid adsorption chromatography when adsorption effects prevail, and liquid chromatography at critical conditions that occurs at the critical point of adsorption. The main attention is paid to the analysis of the critical conditions, at which the retention is chain length independent. The theoretical results are verified with specially designed experiments on isocratic separation of linear polystyrenes on a column packed with non-porous particles at various solvent compositions. Without invoking any adjustable parameters related to the column and particle geometry, we describe quantitatively the observed transition between the size exclusion and adsorption separation regimes upon the variation of solvent composition, with the intermediate mode occurring at a well-defined critical point of adsorption. A relationship is established between the experimental solvent composition and the effective adsorption potential used in model simulations. Copyright © 2016 Elsevier Inc. All rights reserved.

  19. Recognition of Bread Key Odorants by Using Polymer Coated QCMs

    NASA Astrophysics Data System (ADS)

    Nakai, Takashi; Kouno, Shinji; Hiruma, Naoya; Shuzo, Masaki; Delaunay, Jean-Jacques; Yamada, Ichiro

    Polyisobutylene (PIB) polymer and methylphenylsiloxane (25%) diphenylsiloxane (75%) copolymer (OV25) were coated on Quartz Crystal Microbalance (QCM) sensors and used in recognition of bread key odorants. Representative compounds of key roasty odorants of bread were taken as 3-acetylpyridine and benzaldehyde, and representative key fatty odorants were hexanal and (E)-2-nonenal. Both OV25- and PIB-coated QCM fabricated sensors could detect concentration as low as 0.9 ppm of 3-acetylpyridine and 1.2 ppm of (E)-2-nonenal. The sensitivity to 3-acetylpyridine of the OV25-coated QCM was about 1000 times higher than that of ethanol, the major interference compound in bread key odorant analysis. Further, the OV25-coated QCM response was 5-6 times and 2-3 times larger than that of the PIB-coated QCM when exposed to roasty odorants and to fatty odorants, respectively. The difference in sensitivity of the OV25- and PIB-coated QCMs we fabricated made possible to discriminate roasty from fatty odorants as was evidenced by the odor recognition map representing the frequency shifts of the OV25-coated QCM against the frequency shift of the PIB-coated QCM. In conclusion, we found that the combination of an OV25-coated QCM and a PIB-coated QCM was successful in discriminating roasty odorants from fatty odorants at the ppm level.

  20. Engineering Polymer Nanocomoposite Aerogels for Energy Storage and Harvesting

    NASA Astrophysics Data System (ADS)

    Zheng, Qifeng

    piezoelectric properties of the CNFs, but also to the mechanoradicals generated by the porous PDMS coated on the surface of the CNF aerogel film, which can lead to a change in the electric dipole moments and consequently generate electric outputs. A series of systematic studies were carried out to substantiate this new mechanism. These systematic studies have demonstrated that high-performance NGs can be made from porous mechanoradical-generating polymer films. The elucidation of the mechanisms for this family of porous mechanoradical-generating polymers will lead to a new class of energy harvesting materials and high-performance flexible energy generation devices.

  1. Biodegradability of regenerated cellulose films coated with polyurethane/natural polymers interpenetrating polymer networks

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhang, L.; Zhou, J.; Huang, J.

    1999-11-01

    Interpenetrating polymer network (IPN) coatings synthesized from castor-oil-based polyurethane (PU) with chitosan, nitrocellulose, or elaeostearin were coated on regenerated cellulose (RC) film for curing at 80--100 C for 2--5 min, providing biodegradable, water-resistant cellulose films coded, respectively, as RCCH, RCNC, and RCEs. The coated films were buried in natural soil for decaying and inoculated with a spore suspension of fungi on the agar medium, respectively, to test biodegradability. The viscosity-average molecular weight, M{sub {eta}}, and the weight of the degraded films decreased sharply with the progress of degradation. The degradation half-lifes, t{sub 1/2}, of the films in soil at 30more » C were found to be 19 days for RC, 25 days for RCNC, 32 days for RCCH, and 45 days for the RCEs films. Scanning electron microscopy (SEM) showed that the extent of decay followed in the order RC {gt} RCNC {gt} RCCH {gt} RCEs. SEM, infrared (IR), high-performance liquid chromatography (HPLC), and CO{sub 2} evolution results indicated that the microorganisms directly attacked the water-resistant coating layer and then penetrated into the cellulose to speedily metabolize, while accompanying with producing CO{sub 2}, H{sub 2}O, glucose cleaved from cellulose, and small molecules decomposed from the coatings.« less

  2. Enhanced Cycling Stability of Sulfur Electrodes through Effective Binding of Pyridine-Functionalized Polymer

    DOE PAGES

    Tsao, Yuchi; Chen, Zheng; Rondeau-Gagne, Simon; ...

    2017-09-20

    Porous carbons have previously been widely used as host materials for sulfur (S) electrodes because of their high conductivity and high surface area. However, they generally lack strong chemical affinity to stabilize polysulfide species. Therefore, conducting polymers have been employed to stabilize S electrodes. Integrating conducting polymers with high-surface-area carbons can create a new materials platform and synergize their functions. However, the previously used conducting polymers were often insoluble, and coating them uniformly from solution onto a nonpolar carbon substrate is a challenge. Here, we report that solution-processable isoindigo-based polymers incorporating polar substituents provide critical features: the conjugated backbone providesmore » good conductivity; functional pyridine groups provide high affinity to polysulfide species; and they possess high solubility in organic solvents. Here, these lead to effective coating on various carbonaceous substrates to provide highly stable sulfur electrodes. Importantly, the electrodes exhibit good capacity retention (80% over 300 cycles) at sulfur mass loading of 3.2 mg/cm 2, which significantly surpasses the performance of others reported in polymer-enabled sulfur cathodes.« less

  3. Porous polymeric materials for hydrogen storage

    DOEpatents

    Yu, Luping; Liu, Di-Jia; Yuan, Shengwen; Yang, Junbing

    2013-04-02

    A porous polymer, poly-9,9'-spirobifluorene and its derivatives for storage of H.sub.2 are prepared through a chemical synthesis method. The porous polymers have high specific surface area and narrow pore size distribution. Hydrogen uptake measurements conducted for these polymers determined a higher hydrogen storage capacity at the ambient temperature over that of the benchmark materials. The method of preparing such polymers, includes oxidatively activating solids by CO.sub.2/steam oxidation and supercritical water treatment.

  4. The acetabulum: A prospective study of three-phase bone and indium white blood cell scintigraphy following porous-coated hip arthroplasty

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Oswald, S.G.; Van Nostrand, D.; Savory, C.G.

    1990-03-01

    Although few studies address the use of three-phase bone scanning (TPBS) and indium-111-labeled white blood cell scintigraphy ({sup 111}In-WBC) in hip arthroplasty utilizing a porous-coated prosthesis, the literature suggests that scintigraphic patterns in the uncomplicated patient may differ from that seen with the cemented prosthesis. In an attempt to determine the scintigraphic natural history, 25 uncomplicated porous-coated hip arthroplasties in 21 patients were prospectively studied with serial TPBS and {sup 111I}n-WBC at approximately 7 days, and 3, 6, 12, 18, and 24 mo postoperatively. This report deals with findings related to the acetabulum. All 25 prostheses (144 of 144 scans)more » demonstrated increased uptake on the bone-phase images. Although this activity decreased with time, 76% had persistent uptake at 24 mo. Twenty-three of 25 prostheses (126 of 140 scans) showed increased uptake on {sup 111}In-WBC scintigraphy, invariably decreasing with time, but with 37% having significant uptake at 24 mo. Scintigraphic patterns in the uncomplicated porous-coated hip arthroplasty patient appear to differ from patterns described in cemented prostheses.« less

  5. Semi-permeable coatings fabricated from comb-polymers efficiently protect proteins in vivo

    NASA Astrophysics Data System (ADS)

    Liu, Mi; Johansen, Pål; Zabel, Franziska; Leroux, Jean-Christophe; Gauthier, Marc A.

    2014-11-01

    In comparison to neutral linear polymers, functional and architecturally complex (that is, non-linear) polymers offer distinct opportunities for enhancing the properties and performance of therapeutic proteins. However, understanding how to harness these parameters is challenging, and studies that capitalize on them in vivo are scarce. Here we present an in vivo demonstration that modification of a protein with a polymer of appropriate architecture can impart low immunogenicity, with a commensurably low loss of therapeutic activity. These combined properties are inaccessible by conventional strategies using linear polymers. For the model protein L-asparaginase, a comb-polymer bio-conjugate significantly outperformed the linear polymer control in terms of lower immune response and more sustained bioactivity. The semi-permeability characteristics of the coatings are consistent with the phase diagram of the polymer, which will facilitate the application of this strategy to other proteins and with other therapeutic models.

  6. Multipositional silica-coated silver nanoparticles for high-performance polymer solar cells.

    PubMed

    Choi, Hyosung; Lee, Jung-Pil; Ko, Seo-Jin; Jung, Jae-Woo; Park, Hyungmin; Yoo, Seungmin; Park, Okji; Jeong, Jong-Ryul; Park, Soojin; Kim, Jin Young

    2013-05-08

    We demonstrate high-performance polymer solar cells using the plasmonic effect of multipositional silica-coated silver nanoparticles. The location of the nanoparticles is critical for increasing light absorption and scattering via enhanced electric field distribution. The device incorporating nanoparticles between the hole transport layer and the active layer achieves a power conversion efficiency of 8.92% with an external quantum efficiency of 81.5%. These device efficiencies are the highest values reported to date for plasmonic polymer solar cells using metal nanoparticles.

  7. Study and modeling of the ironing process on a multi-layered polymer coated low-carbon steel

    NASA Astrophysics Data System (ADS)

    Selles Canto, Miguel Angel

    The ironing process is the most crucial step in the manufacture of cans. Sheet steel covered by three polymer layers can be used as the starting material, but this coating must neither break nor fail in any manner in order to be considered as a viable and effective alternative to traditional practice. During ironing, the deformations are severe and high pressures exist at the tool-workpiece interface. Thickness reductions inherent in ironing require a large amount of surface generation. Deterioration of the coating in this delicate operation might enable direct contact of the stored food or drink with the metal. As can be appreciated, the key to the use of polymer-coated steel sheets in the manufacture of cans lies in the survival of these layers during the ironing process. Another important issue is the roughness of the newly-generated surface, because it should be possible to decorate the can without any difficulty. Changing the traditional manufacture of metallic containers such as cans and using this new coated material permits great reduction in environmental contaminants produced as a result of avoiding the formation of Volatile Organic Compounds (VOCs) during the manufacture of the polymer layers. This reduction is even greater because of not using additional lubricants due to the self-lubricanting property of the solid polymer coating layers during the drawing process. These objectives, together with the improvement of the mechanical characteristics and the adhesion of the painting or decorative priming, are realized by the use of the proposed material. In the existing bibliography about ironing processes on coated materials, some authors propose the use of the Upper Bound Theorem for modeling the material behavior. The present research shows for the first time the modeling of the ironing process on a three-layer polymer coated material. In addition, it takes into account the cases in which successful ironing is produced and those in which ones the ironing

  8. Corrosion resistant coating

    DOEpatents

    Wrobleski, D.A.; Benicewicz, B.C.; Thompson, K.G.; Bryan, C.J.

    1997-08-19

    A method of protecting a metal substrate from corrosion including coating a metal substrate of, e.g., steel, iron or aluminum, with a conductive polymer layer of, e.g., polyaniline, coating upon said metal substrate, and coating the conductive polymer-coated metal substrate with a layer of a topcoat upon the conductive polymer coating layer, is provided, together with the resultant coated article from said method.

  9. Corrosion resistant coating

    DOEpatents

    Wrobleski, Debra A.; Benicewicz, Brian C.; Thompson, Karen G.; Bryan, Coleman J.

    1997-01-01

    A method of protecting a metal substrate from corrosion including coating a metal substrate of, e.g., steel, iron or aluminum, with a conductive polymer layer of, e.g., polyaniline, coating upon said metal substrate, and coating the conductive polymer-coated metal substrate with a layer of a topcoat upon the conductive polymer coating layer, is provided, together with the resultant coated article from said method.

  10. Laminar flow drag reduction on soft porous media.

    PubMed

    Mirbod, Parisa; Wu, Zhenxing; Ahmadi, Goodarz

    2017-12-08

    While researches have focused on drag reduction of various coated surfaces such as superhydrophobic structures and polymer brushes, the insights tso understand the fundamental physics of the laminar skin friction coefficient and the related drag reduction due to the formation of finite velocity at porous surfaces is still relatively unknown. Herein, we quantitatively investigated the flow over a porous medium by developing a framework to model flow of a Newtonian fluid in a channel where the lower surface was replaced by various porous media. We showed that the flow drag reduction induced by the presence of the porous media depends on the values of the permeability parameter α = L/(MK) 1/2 and the height ratio δ = H/L, where L is the half thickness of the free flow region, H is the thickness and K is the permeability of the fiber layer, and M is the ratio of the fluid effective dynamic viscosity μ e in porous media to its dynamic viscosity μ. We also examined the velocity and shear stress profiles for flow over the permeable layer for the limiting cases of α → 0 and α → ∞. The model predictions were compared with the experimental data for specific porous media and good agreement was found.

  11. Complications of porous-coated press-fit cementless total hip replacement in dogs.

    PubMed

    Kidd, Scott W; Preston, Christopher A; Moore, George E

    2016-09-20

    To report postoperative complications using a commercially available porous-coated press-fit cementless total hip replacement (THR) system in dogs. Medical records were reviewed for client-owned dogs with hip pathologies requiring THR. A minimum of six-week postoperative orthopaedic examination and orthogonal pelvic radiographs were used to assess outcome and complications in the perioperative period. Referring veterinarian medical records, phone interviews with clients, or both were used to assess long-term functional outcome and complications. Bilateral THR was performed in 36 dogs, and unilateral in 147 dogs, making a total of 219 THR procedures in 183 dogs. A total complication rate of 31.1% (68/219) was observed. A catastrophic complication was observed in 8.2% (n = 18), a major complication in 9.6% (n = 21), and a minor complication in 13.2% (n = 29) of procedures. The most common complications were intra-operative femoral fissure (n = 46), diaphyseal femoral fracture (n = 15), and coxofemoral luxation (n = 9). Full return to function was achieved in 88.1% of procedures with a median follow-up period of 42 months. Porous-coated press-fit cementless collarless total hip replacements have a high complication rate. The majority of complications occur intra-operatively or perioperatively, with few complications occurring beyond 12 weeks postoperatively. Both fissure fractures and diaphyseal femoral fractures carry a favourable prognosis with immediate cerclage wiring and plate fixation, respectively.

  12. Versatile theranostics agents designed by coating ferrite nanoparticles with biocompatible polymers

    NASA Astrophysics Data System (ADS)

    Zahraei, M.; Marciello, M.; Lazaro-Carrillo, A.; Villanueva, A.; Herranz, F.; Talelli, M.; Costo, R.; Monshi, A.; Shahbazi-Gahrouei, D.; Amirnasr, M.; Behdadfar, B.; Morales, M. P.

    2016-06-01

    Three biocompatible polymers, polyethylene glycol (PEG), dextran and chitosan, have been used in this work to control the colloidal stability of magnetic nanoparticles (14 ± 5 nm in diameter) and to vary the aggregation state in order to study their effect on relaxometric and heating properties. Two different coating strategies have been deeply developed; one based on the formation of an amide bond between citric acid coated nanoparticles (NPs) and amine groups present on the polymer surface and the other based on the NP encapsulation. Relaxometric properties revealed that proton relaxation rates strongly depend on the coating layer hydrophilicity and the aggregation state of the particles due to the presence of magnetic interactions. Thus, while PEG coating reduces particle aggregation by increasing inter-particle spacing leading to reduction of both T1 and T2 relaxation, dextran and chitosan lead to an increase mainly in T2 values due to the aggregation of particles in bigger clusters where they are in close contact. Dextran and chitosan coated NPs have also shown a remarkable heating effect during the application of an alternating magnetic field. They have proved to be potential candidates as theranostic agents for cancer diagnosis and treatment. Finally, cytotoxicity of PEG conjugated NPs, which seem to be ideal for intravenous administration because of their small hydrodynamic size, was investigated resulting in high cell viability even at 0.2 mg Fe ml-1 after 24 h of incubation. This suspension can be used as drug/biomolecule carrier for in vivo applications.

  13. Evasion of the accelerated blood clearance phenomenon by coating of nanoparticles with various hydrophilic polymers.

    PubMed

    Ishihara, Tsutomu; Maeda, Taishi; Sakamoto, Haruka; Takasaki, Naoko; Shigyo, Masao; Ishida, Tatsuhiro; Kiwada, Hiroshi; Mizushima, Yutaka; Mizushima, Tohru

    2010-10-11

    The accelerated blood clearance (ABC) phenomenon is induced upon repeated injections of poly(ethylene glycol) (PEG)-coated colloidal carriers. It is essential to suppress this phenomenon in a clinical setting because the pharmacokinetics must be reproducible. In this study, we evaluated the induction of the ABC phenomenon using nanoparticles coated with various hydrophilic polymers instead of PEG. Nanoparticles encapsulating prostaglandin E1 were prepared by the solvent diffusion method from a blend of poly(lactic acid) (PLA) and block copolymers consisting of various hydrophilic polymers and PLA. Coating of nanoparticles with poly(N-vinyl-2-pyrrolidone) (PVP), poly(4-acryloylmorpholine), or poly(N,N-dimethylacrylamide) led to extended residence of the nanoparticles in blood circulation in rats, although they had a shorter half-life than the PEG-coated nanoparticles. The ABC phenomenon was not induced upon repeated injection of PVP-coated nanoparticles at various time intervals, dosages, or frequencies, whereas it was elicited by PEG-coated nanoparticles. In addition, anti-PVP IgM antibody, which is estimated to be one of the crucial factors for induction of the ABC phenomenon, was not produced after injection of PVP-coated nanoparticles. These results suggest that the use of PVP, instead of PEG, as a coating material for colloidal carriers can evade the ABC phenomenon.

  14. Surface coating with Ca(OH)2 for improvement of the transport of nanoscale zero-valent iron (nZVI) in porous media.

    PubMed

    Wei, Cai-jie; Li, Xiao-yan

    2013-01-01

    A novel thermal deposition method was developed to coat Ca(OH)2 on the surface of nanoscale zero-valent iron (nZVI). The nZVI particles with the Ca(OH)2 coating layer, nZVI/Ca(OH)2, had a clear core-shell structure based on the transmission electron microscopy observations, and the Ca(OH)2 shell was identified as an amorphous phase. The Ca(OH)2 coating shell would not only function as an effective protection layer for nZVI but also improve the mobility of nZVI in porous media for its use in environmental decontamination. A 10% Ca/Fe mass ratio was found to result in a proper thickness of the Ca(OH)2 shell on the nZVI surface. Based on the filtration tests in sand columns, the Ca(OH)2-based surface coating could greatly improve the mobility and transport of nZVI particles in porous media. In addition, batch experiments were conducted to evaluate the reactivity of Ca(OH)2-coated nZVI particles for the reduction of Cr(VI) and its removal from water.

  15. Porous polymeric materials for hydrogen storage

    DOEpatents

    Yu, Luping [Hoffman Estates, IL; Liu, Di-Jia [Naperville, IL; Yuan, Shengwen [Chicago, IL; Yang, Junbing [Westmont, IL

    2011-12-13

    Porous polymers, tribenzohexazatriphenylene, poly-9,9'-spirobifluorene, poly-tetraphenyl methane and their derivatives for storage of H.sub.2 prepared through a chemical synthesis method. The porous polymers have high specific surface area and narrow pore size distribution. Hydrogen uptake measurements conducted for these polymers determined a higher hydrogen storage capacity at the ambient temperature over that of the benchmark materials. The method of preparing such polymers, includes oxidatively activating solids by CO.sub.2/steam oxidation and supercritical water treatment.

  16. Evaluation of E. coli inhibition by plain and polymer-coated silver nanoparticles.

    PubMed

    Ashmore, D'Andrea; Chaudhari, Atul; Barlow, Brandi; Barlow, Brett; Harper, Talia; Vig, Komal; Miller, Michael; Singh, Shree; Nelson, Edward; Pillai, Shreekumar

    2018-01-01

    Escherichia coli causes various ailments such as septicemia, enteritis, foodborne illnesses, and urinary tract infections which are of concern in the public health field due to antibiotic resistance. Silver nanoparticles (AgNP) are known for their biocompatibility and antibacterial activity, and may prove to be an alternative method of treatment, especially as wound dressings. In this study, we compared the antibacterial efficacy of two polymer-coated silver nanoparticles either containing 10% Ag (Ag 10% + Polymer), or 99% Ag (AgPVP) in relation to plain uncoated silver nanoparticles (AgNP). Atomic force microscopy was used to characterize the nanoparticles, and their antibacterial efficacy was compared by the minimum inhibitory concentration (MIC) and bacterial growth curve assays, followed by molecular studies using scanning electron microscopy (SEM) and (qRT- PCR). AgNP inhibited the growth of E. coli only at 0.621 mg/mL, which was double the concentration required for both coated nanoparticles (0.312 mg/mL). Similarly, bacterial growth was impeded as early as 8 h at 0.156 mg/mL of both coated nanoparticles as compared to 0.312 mg/mL for plain AgNP. SEM data showed that nanoparticles damaged the cell membrane, resulting in bacterial cell lysis, expulsion of cellular contents, and complete disintegration of some cells. The expression of genes associated with the TCA cycle (aceF and frdB) and amino acid metabolism (gadB, metL, argC) were substantially downregulated in E. coli treated with nanoparticles. The reduction in the silver ion (Ag+) concentration of polymer-coated AgNP did not affect their antibacterial efficacy against E. coli.

  17. Erosion Resistant Coatings for Polymer Matrix Composites in Propulsion Applications

    NASA Technical Reports Server (NTRS)

    Sutter, James K.; Naik, Subhash K.; Horan, Richard; Miyoshi, Kazuhisa; Bowman, Cheryl; Ma, Kong; Leissler, George; Sinatra, Raymond; Cupp, Randall

    2003-01-01

    Polymer Matrix Composites (PMCs) offer lightweight and frequently low cost alternatives to other materials in many applications. High temperature PMCs are currently used in limited propulsion applications replacing metals. Yet in most cases, PMC propulsion applications are not in the direct engine flow path since particulate erosion degrades PMC component performance and therefore restricts their use in gas turbine engines. This paper compares two erosion resistant coatings (SANRES and SANPRES) on PMCs that are useful for both low and high temperature propulsion applications. Collaborating over a multi-year period, researchers at NASA Glenn Research Center, Allison Advanced Developed Company, and Rolls-Royce Corporation have optimized these coatings in terms of adhesion, surface roughness, and erosion resistance. Results are described for vigorous hot gas/particulate erosion rig and engine testing of uncoated and coated PMC fan bypass vanes from the AE 3007 regional jet gas turbine engine. Moreover, the structural durability of these coatings is described in long-term high cycle fatigue tests. Overall, both coatings performed well in all tests and will be considered for applications in both commercial and defense propulsion applications.

  18. Sulfur-Doped Laser-Induced Porous Graphene Derived from Polysulfone-Class Polymers and Membranes.

    PubMed

    Singh, Swatantra P; Li, Yilun; Zhang, Jibo; Tour, James M; Arnusch, Christopher J

    2018-01-23

    Graphene based materials have profoundly impacted research in nanotechnology, and this has significantly advanced biomedical, electronics, energy, and environmental applications. Laser-induced graphene (LIG) is made photothermally and has enabled a rapid route for graphene layers on polyimide surfaces. However, polysulfone (PSU), poly(ether sulfone) (PES), and polyphenylsulfone (PPSU) are highly used in numerous applications including medical, energy, and water treatment and they are critical components of polymer membranes. Here we show LIG fabrication on PSU, PES, and PPSU resulting in conformal sulfur-doped porous graphene embedded in polymer dense films or porous substrates using reagent- and solvent-free methods in a single step. We demonstrate the applicability as flexible electrodes with enhanced electrocatalytic hydrogen peroxide generation, as antifouling surfaces and as antimicrobial hybrid membrane-LIG porous filters. The properties and surface morphology of the conductive PSU-, PES-, and PPSU-LIG could be modulated using variable laser duty cycles. The LIG electrodes showed enhanced hydrogen peroxide generation compared to LIG made on polyimide, and showed exceptional biofilm resistance and potent antimicrobial killing effects when treated with Pseudomonas aeruginosa and mixed bacterial culture. The hybrid PES-LIG membrane-electrode ensured complete elimination of bacterial viability in the permeate (6 log reduction), in a flow-through filtration mode at a water flux of ∼500 L m -2 h -1 (2.5 V) and at ∼22 000 L m -2 h -1 (20 V). Due to the widespread use of PSU, PES, and PPSU in modern society, these functional PSU-, PES-, and PPSU-LIG surfaces have great potential to be incorporated into biomedical, electronic, energy and environmental devices and technologies.

  19. A 3D porous indium(III) coordination polymer involving in-situ ligand synthesis

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Han Zhengbo, E-mail: ceshzb@lnu.edu.c; Song Yongjuan; Ji Jianwei

    2009-11-15

    The hydrothermal reaction of In{sup 3+} and 1,2,4-benzenetricarboxylic acid with the presence of piperazine leads to the generation of a novel 3D porous coordination polymer, [H{sub 3}O][In{sub 2}(btc)(bdc)(OH){sub 2}].5.5H{sub 2}O (1), (btc=1,2,4-benzenetricarboxylate, bdc=1,4-benzenedicarboxylate). Compound 1 crystallizes in orthorhombic space group Pbca with a=16.216(7) A, b=13.437(6) A, c=31.277(14) A, and Z=8. It is interesting to find that the in-situ decarboxylation reaction of 1,2,4-benzenetricarboxylate (btc) partially transformed into 1,4-benzenedicarboxylate (bdc) occurs. The 16 indium(III) centers were linked by four btc, four bdc and two mu{sub 2}-OH ligands to form a box-girder. The adjacent box-girders are further connected by the bdc and btcmore » ligands to generate a novel porous metal-organic framework containing nanotubular open channel with a cross-section of approximately 11.5x11.3 A{sup 2}. The micropores are occupied by lattice water molecules, and the solvent-accessible volume of the unit cell was estimated to be 3658.6 A{sup 3}, which is approximately 53.7% of the unit-cell volume (6815.4 A{sup 3}). - Graphical Abstract: The hydrothermal reaction of In{sup 3+} and 1,2,4-benzenetricarboxylic acid with the presence of piperazine leads to the generation of a novel 3D porous coordination polymer, [H{sub 3}O][In{sub 2}(btc)(bdc)(OH){sub 2}].5.5H{sub 2}O, (btc=1,2,4-benzenetricarboxylate, bdc=1,4-benzenedicarboxylate).« less

  20. Composite materials obtained by the ion-plasma sputtering of metal compound coatings on polymer films

    NASA Astrophysics Data System (ADS)

    Khlebnikov, Nikolai; Polyakov, Evgenii; Borisov, Sergei; Barashev, Nikolai; Biramov, Emir; Maltceva, Anastasia; Vereshchagin, Artem; Khartov, Stas; Voronin, Anton

    2016-01-01

    In this article, the principle and examples composite materials obtained by deposition of metal compound coatings on polymer film substrates by the ion-plasma sputtering method are presented. A synergistic effect is to obtain the materials with structural properties of the polymer substrate and the surface properties of the metal deposited coatings. The technology of sputtering of TiN coatings of various thicknesses on polyethylene terephthalate films is discussed. The obtained composites are characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM), and scanning tunneling microscopy (STM) is shown. The examples of application of this method, such as receiving nanocomposite track membranes and flexible transparent electrodes, are considered.

  1. A highly durable fuel cell electrocatalyst based on double-polymer-coated carbon nanotubes.

    PubMed

    Berber, Mohamed R; Hafez, Inas H; Fujigaya, Tsuyohiko; Nakashima, Naotoshi

    2015-11-23

    Driven by the demand for the commercialization of fuel cell (FC) technology, we describe the design and fabrication of a highly durable FC electrocatalyst based on double-polymer-coated carbon nanotubes for use in polymer electrolyte membrane fuel cells. The fabricated electrocatalyst is composed of Pt-deposited polybenzimidazole-coated carbon nanotubes, which are further coated with Nafion. By using this electrocatalyst, a high FC performance with a power density of 375 mW/cm(2) (at 70 ˚C, 50% relative humidity using air (cathode)/H2(anode)) was obtained, and a remarkable durability of 500,000 accelerated potential cycles was recorded with only a 5% loss of the initial FC potential and 20% loss of the maximum power density, which were far superior properties compared to those of the membrane electrode assembly prepared using carbon black in place of the carbon nanotubes. The present study indicates that the prepared highly durable fuel cell electrocatalyst is a promising material for the next generation of PEMFCs.

  2. Novel Biocatalytic Polymer-Based Antimicrobial Coatings as Potential Ureteral Biomaterial: Preparation and In Vitro Performance Evaluation▿

    PubMed Central

    Dave, Rachna N.; Joshi, Hiren M.; Venugopalan, Vayalam P.

    2011-01-01

    Catheters and other indwelling devices placed inside human body are prone to bacterial infection, causing serious risk to patients. Infections associated with implants are difficult to resolve, and hence the prevention of bacterial colonization of such surfaces is quite appropriate. In this context, the development of novel antimicrobial biomaterials is currently gaining momentum. We describe here the preparation and antibacterial properties of an enzyme-embedded polycaprolactone (PCL)-based coating, coimpregnated with the antibiotic gentamicin sulfate (GS). The enzyme uses PCL itself as substrate; as a result, the antibiotic gets released at a rate controlled by the degradation of the PCL base. In vitro drug release studies demonstrated sustained release of GS from the PCL film throughout its lifetime. By modulating the enzyme concentration in the PCL film, we were able to vary the lifetime of the coating from 33 h to 16 days. In the end, the polymer is completely degraded, delivering the entire load of the antibiotic. The polymer exhibited antibacterial properties against three test isolates: Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus. Foley urinary catheters coated with the modified polymer exhibited sustained in vitro release of GS over a 60-h period. The results suggest that the antibiotic-plus-enzyme-loaded polymer can be used as tunable self-degrading antimicrobial biomaterial coating on catheters. PMID:21135190

  3. Fabrication and characterization of highly porous barium titanate based scaffold coated by Gel/HA nanocomposite with high piezoelectric coefficient for bone tissue engineering applications.

    PubMed

    Ehterami, Arian; Kazemi, Mansure; Nazari, Bahareh; Saraeian, Payam; Azami, Mahmoud

    2018-03-01

    It is well established that the piezoelectric effect plays an important physiological role in bone growth, remodeling and fracture healing. Barium titanate, as a well-known piezoelectric ceramic, is especially an attractive material as a scaffold for bone tissue engineering applications. In this regard, we tried to fabricate a highly porous barium titanate based scaffolds by foam replication method and polarize them by applying an external electric field. In order to enhance the mechanical and biological properties, polarized/non-polarized scaffolds were coated with gelatin and nanostructured HA and characterized for their morphologies, porosities, piezoelectric and mechanical properties. The results showed that the compressive strength and piezoelectric coefficient of porous scaffolds increased with the increase of sintering temperature. After being coated with Gel/HA nanocomposite, the interconnected porous structure and pore size of the scaffolds almost remain unchanged while the Gel/nHA-coated scaffolds exhibited enhanced compressive strength and elastic modulus compared with the uncoated samples. Also, the effect of polarizing and coating of optimal scaffolds on adhesion, viability, and proliferation of the MG63 osteoblast-like cell line was evaluated by scanning electron microscope (SEM) and MTT assay. The cell culture experiments revealed that developed scaffolds had good biocompatibility and cells were able to adhere, proliferate and migrate into pores of the scaffolds. Furthermore, cell density was significantly higher in the coated scaffolds at all tested time-points. These results indicated that highly porous barium titanate scaffolds coated with Gel/HA nanocomposite has great potential in tissue engineering applications for bone tissue repair and regeneration. Copyright © 2018 Elsevier Ltd. All rights reserved.

  4. Enhancing the mechanical and in vitro performance of robocast bioglass scaffolds by polymeric coatings: Effect of polymer composition.

    PubMed

    Motealleh, Azadeh; Eqtesadi, Siamak; Pajares, Antonia; Miranda, Pedro

    2018-08-01

    The effect of different polymeric coatings, including natural and synthetic compositions, on the mechanical performance of 45S5 bioglass robocast scaffolds is systematically analyzed in this work. Fully amorphous 45S5 bioglass robocast scaffolds sintered at 550 °C were impregnated with natural (gelatin, alginate, and chitosan) and synthetic (polycaprolactone, PCL and poly-lactic acid, PLA) polymers through a dip-coating process. Mechanical enhancement provided by these coatings in terms of both compressive strength and strain energy density was evaluated. Natural polymers, in general, and chitosan, in particular, were found to produce the greater reinforcement. The effect of these coatings on the in vitro bioactivity and degradation behavior of 45S5 bioglass robocast scaffolds was also investigated through immersion tests in simulated body fluid (SBF). Coatings from natural polymers, especially chitosan, are shown to have a positive effect on the bioactivity of 45S5 bioglass, accelerating the formation of an apatite-like layer. Besides, most coating compositions reduced the degradation (weight loss) rate of the scaffold, which has a positive impact on the evolution of their mechanical properties. Copyright © 2018 Elsevier Ltd. All rights reserved.

  5. Reversible and strong immobilization of proteins by ionic exchange on supports coated with sulfate-dextran.

    PubMed

    Fuentes, Manuel; Pessela, Benevides C C; Maquiese, Jorgette V; Ortiz, Claudia; Segura, Rosa L; Palomo, Jose M; Abian, Olga; Torres, Rodrigo; Mateo, Cesar; Fernández-Lafuente, Roberto; Guisán, J M

    2004-01-01

    New and strong ionic exchange resins have been prepared by the simple and rapid ionic adsorption of anionic polymers (sulfate-dextran) on porous supports activated with the opposite ionic group (DEAE/MANAE). Ionic exchange properties of such composites were strongly dependent on the size of the ionic polymers as well as on the conditions of the ionic coating of the solids with the ionic polymers (optimal conditions were 400 mg of sulfate-dextran 5000 kDa per gram of support). Around 80% of the proteins contained in crude extracts from Escherichia coli and Acetobacter turbidans could be adsorbed on these porous composites even at pH 7. This interaction was stronger than that using conventional carboxymethyl cellulose (CMC) and even others such as supports coated with aspartic-dextran polymer. By means of the sequential use of the new supports and supports coated with polyethyleneimine (PEI), all proteins from crude extracts could be immobilized. In fact, a large percentage (over 50%) could be immobilized on both supports. Finally, some industrially relevant enzymes (beta-galactosidases from Aspergillus oryzae, Kluyveromyces lactis, and Thermussp. strain T2, lipases from Candida antarctica A and B, Candida rugosa, Rhizomucor miehei, and Rhyzopus oryzae and bovine pancreas trypsin and chymotrypsin) have been immobilized on these supports with very high activity recoveries and immobilization rates. After enzyme inactivation, the protein could be fully desorbed from the support, and then the support could be reused for several cycles. Moreover, in some instances the enzyme stability was significantly improved, mainly in the presence of organic solvents, perhaps as a consequence of the highly hydrophilic microenvironment of the support.

  6. Hydrophilic Polymer Embolism: Implications for Manufacturing, Regulation, and Postmarket Surveillance of Coated Intravascular Medical Devices.

    PubMed

    Mehta, Rashi I; Mehta, Rupal I

    2018-03-19

    Hydrophilic polymers are ubiquitously applied as surface coatings on catheters and intravascular medical technologies. Recent clinical literature has heightened awareness on the complication of hydrophilic polymer embolism, the phenomenon wherein polymer coating layers separate from catheter and device surfaces, and may be affiliated with a range of unanticipated adverse reactions. Significant system barriers have limited and delayed reporting on this iatrogenic complication, the full effects of which remain underrecognized by healthcare providers and manufacturers of various branded devices. In 2015, the United States Food and Drug Administration acknowledged rising clinical concerns and stated that the agency would work with stakeholders to further evaluate gaps that exist in current national and international device standards for coated intravascular medical technologies. The present article reviews current knowledge on this complication as well as factors that played a role in delaying detection and dissemination of information and new knowledge once hazards and clinical risks were identified. Furthermore, organ-specific effects and adverse reaction patterns are summarized, along with implications for device manufacturing, safety assurance, and regulation. Qualitative and quantitative particulate testing are needed to optimize coated intravascular device technologies. Moreover, general enhanced processes for medical device surveillance are required for timely adverse event management and to ensure patient safety.

  7. Integrated TiN coated porous silicon supercapacitor with large capacitance per foot print

    NASA Astrophysics Data System (ADS)

    Grigoras, Kestutis; Grönberg, Leif; Ahopelto, Jouni; Prunnila, Mika

    2017-05-01

    We have fabricated a micro-supercapacitor with porous silicon electrodes coated with TiN by atomic layer deposition technique. The coating provides an efficient surface passivation and high electrical conductivity of the electrodes, resulting in stable and almost ideal electrochemical double layer capacitor behavior with characteristics comparable to the best carbon based micro-supercapacitors. Stability of the supercapacitor is verified by performing 50 000 voltammetry cycles with high capacitance retention obtained. Silicon microfabrication techniques facilitate integration of both supercapacitor electrodes inside the silicon substrate and, in this work, such in-chip supercapacitor is demonstrated. This approach allows realization of very high capacitance per foot print area. The in-chip micro-supercapacitor can be integrated with energy harvesting elements and can be used in wearable and implantable microdevices.

  8. In vitro performance of Ag-incorporated hydroxyapatite and its adhesive porous coatings deposited by electrostatic spraying.

    PubMed

    Gokcekaya, Ozkan; Webster, Thomas J; Ueda, Kyosuke; Narushima, Takayuki; Ergun, Celaletdin

    2017-08-01

    Bacterial infection of implanted materials is a significant complication that might require additional surgical operations for implant retrieval. As an antibacterial biomaterial, Ag-containing hydroxyapatite (HA) may be a solution to reduce the incidences of implant associated infections. In this study, pure, 0.2mol% and 0.3mol% Ag incorporated HA powders were synthesized via a precipitation method. Colloidal precursor dispersions prepared from these powders were used to deposit porous coatings onto titanium and stainless steel substrates via electrostatic spraying. The porous coating layers obtained with various deposition times and heat treatment conditions were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Scratch tests were conducted to assess the adhesion strength of the coating. Antibacterial activity of Ag-incorporated HA was tested towards Escherichia coli (E. coli) at various incubation times. Osteoblast adhesion on Ag-incorporated HA was evaluated to assess biocompatibility. Improvement in adhesion strength of the coating layer was observed after the heat treatment process due to mutual ionic diffusion at the interface. The Ag-incorporated HA killed all viable E. coli after 24h of incubation, whereas no antibacterial activity was detected with pure HA. In addition, in vitro cell culture tests demonstrated osteoblast adhesion similar to pure HA, which indicated good cytocompatibility. In summary, results of this study provided significant promise for the future study of Ag-incorporated HA for numerous medical applications. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Nanoparticle-Functionalized Porous Polymer Monolith Detection Elements for Surface-Enhanced Raman Scattering

    PubMed Central

    Liu, Jikun; White, Ian; DeVoe, Don L.

    2011-01-01

    The use of porous polymer monoliths functionalized with silver nanoparticles is introduced in this work for high-sensitivity surface-enhanced Raman scattering (SERS) detection. Preparation of the SERS detection elements is a simple process comprising the synthesis of a discrete polymer monolith section within a silica capillary, followed by physically trapping silver nanoparticle aggregates within the monolith matrix. A SERS detection limit of 220 fmol for Rhodamine 6G (R6G) is demonstrated, with excellent signal stability over a 24 h period. The capability of the SERS-active monolith for label-free detection of biomolecules was demonstrated by measurements of bradykinin and cyctochrome c. The SERS-active monoliths can be readily integrated into miniaturized micro-total-analysis systems for on-line and label-free detection for a variety of biosensing, bioanalytical, and biomedical applications. PMID:21322579

  10. An ecotoxicological study on tin- and bismuth-catalysed PDMS based coatings containing a surface-active polymer.

    PubMed

    Pretti, Carlo; Oliva, Matteo; Mennillo, Elvira; Barbaglia, Martina; Funel, Marco; Reddy Yasani, Bhaskar; Martinelli, Elisa; Galli, Giancarlo

    2013-12-01

    Novel films were prepared by condensation curing reaction of a poly(dimethyl siloxane) (PDMS) matrix with bismuth neodecanoate and dibutyltin diacetate catalysts. An ecotoxicological study was performed on the leachates of the coatings using the bacterium Vibrio fischeri, the unicellular alga Dunaliella tertiolecta, the crustacean Artemia salina and the fish Sparus aurata (larvae) as testing organisms. A copper-based self-polishing commercial paint was also tested as reference. The results showed that the tin-catalysed coatings and the copper paint were highly toxic against at least two of the four test organisms, whereas bismuth-catalysed coatings did not show any toxic effect. Moreover, the same biological assessment was also carried out on PDMS coatings containing a surface-active fluorinated polymer. The toxicity of the entire polymeric system resulted only from the tin catalyst used for the condensation curing reaction, as the bismuth catalysed coatings incorporating the surface-active polymer remained atoxic toward all the tested organisms. © 2013 Elsevier Inc. All rights reserved.

  11. Electrophoretic deposition of porous CaO-MgO-SiO2 glass-ceramic coatings with B2O3 as additive on Ti-6Al-4V alloy.

    PubMed

    Zhang, Wei; Chen, Xianchun; Liao, Xiaoming; Huang, Zhongbing; Dan, Xiuli; Yin, Guangfu

    2011-10-01

    The sub-micron glass-ceramic powders in CaO-MgO-SiO(2) system with 10 wt% B(2)O(3) additive were synthesized by sol-gel process. Then bioactive porous CaO-MgO-SiO(2) glass-ceramic coatings on Ti-6Al-4V alloy substrates were fabricated using electrophoretic deposition (EPD) technique. After being calcined at 850°C, the above coatings with thickness of 10-150 μm were uniform and crack-free, possessing porous structure with sub-micron and micron size connected pores. Ethanol was employed as the most suitable solvent to prepare the suspension for EPD. The coating porous appearance and porosity distribution could be controlled by adjusting the suspension concentration, applied voltage and deposition time. The heat-treated coatings possessed high crystalline and was mainly composed of diopside, akermanite, merwinite, calcium silicate and calcium borate silicate. Bonelike apatite was formed on the coatings after 7 days of soaking in simulated body fluid (SBF). The bonding strength of the coatings was needed to be further improved.

  12. Laser surface treatment for porous and textured Ca-P bio-ceramic coating on Ti-6Al-4V.

    PubMed

    Paital, Sameer R; Dahotre, Narendra B

    2007-12-01

    In the present paper the feasibility of depositing a porous calcium phosphate (CaP) bio-ceramic coating using a continuous wave Nd:YAG laser on a Ti-6Al-4V substrate has been demonstrated. The advantages offered by such porous bio-ceramic coating are its inertness combined with the mechanical stability of the highly convoluted interface that develops when bone grows into the pores of ceramic. The formation of different phases with varying laser fluences is studied using x-ray diffraction (XRD). A quantitative estimation of the crystallite size and relative amounts of Ti and other predominant phases such as TiO(2) and alpha-tricalcium phosphate (alpha-TCP) were obtained. An increase in the crystallite size with increasing laser fluence is observed for all the above three phases. It is observed that TiO(2) is the predominant phase for all laser fluences and there is an increase in the alpha-TCP phase with increasing laser fluence. Surface porosity measurements indicated a decreasing trend with increasing laser fluence. Microhardness measurements in the cross section of samples showed a maximum hardness within the coating. The bioactivity of the coatings was further demonstrated by the formation of an apatite-like layer on the surface of the sample after being immersed in a simulated biofluid.

  13. Gold coatings on polymer laser induced periodic surface structures: assessment as substrates for surface-enhanced Raman scattering.

    PubMed

    Rebollar, Esther; Sanz, Mikel; Pérez, Susana; Hernández, Margarita; Martín-Fabiani, Ignacio; Rueda, Daniel R; Ezquerra, Tiberio A; Domingo, Concepción; Castillejo, Marta

    2012-12-05

    We report on the fabrication of gold coated nanostructured polymer thin films and on their characterization as substrates for surface enhanced Raman spectroscopy (SERS). Laser induced periodic surface structures (LIPSS) were obtained on thin polymer films of poly(trimethylene terephthalate) (PTT) upon laser irradiation with the fourth harmonic of a Nd:YAG laser (266 nm, pulse duration 6 ns) resulting in a period close to the incident wavelength. The nanostructured polymer substrates were coated with a nanoparticle assembled gold layer by pulsed laser deposition using the fifth harmonic of a Nd:YAG laser (213 nm, pulse duration 15 ns). Different deposition times resulted in thicknesses from a few nanometres up to several tens of nanometres. Analysis by atomic force microscopy and grazing incident small angle X-ray scattering showed that gold coating preserved the LIPSS relief. The capabilities of the produced nanostructures as substrates for SERS have been investigated using benzenethiol as a test molecule. The SERS signal is substantially larger than that observed for a gold-coated flat substrate. Advantages of this new type of SERS substrates are discussed.

  14. 96X Screen-Printed Gold Electrode Platform to Evaluate Electroactive Polymers as Marine Antifouling Coatings.

    PubMed

    Brisset, Hugues; Briand, Jean-François; Barry-Martinet, Raphaëlle; Duong, The Hy; Frère, Pierre; Gohier, Frédéric; Leriche, Philippe; Bressy, Christine

    2018-04-17

    Several alternatives are currently investigated to prevent and control the natural process of colonization of any seawater submerged surfaces by marine organisms. Since few years we develop an approach based on addressable electroactive coatings containing conducting polymers or polymers with lateral redox groups. In this article we describe the use of a screen-printed plate formed by 96 three-electrode electrochemical cells to assess the potential of these electroactive coatings to prevent the adhesion of marine bacteria. This novel platform is intended to control and record the redox properties of the electroactive coating in each well during the bioassay (15 h) and to allow screening its antiadhesion activity with enough replicates to support significant conclusions. Validation of this platform was carried out with poly(ethylenedioxythiophene) (PEDOT) as electroactive coating obtained by electropolymerization of EDOT monomer in artificial seawater electrolyte on the working electrode of each electrochemical cell of the 96-well microplate.

  15. Cationic polymers for DNA origami coating - examining their binding efficiency and tuning the enzymatic reaction rates

    NASA Astrophysics Data System (ADS)

    Kiviaho, Jenny K.; Linko, Veikko; Ora, Ari; Tiainen, Tony; Järvihaavisto, Erika; Mikkilä, Joona; Tenhu, Heikki; Nonappa, Affc; Kostiainen, Mauri A.

    2016-06-01

    DNA origamis are fully tailored, programmable, biocompatible and readily functionalizable nanostructures that provide an excellent foundation for the development of sophisticated drug-delivery systems. However, the DNA origami objects suffer from certain drawbacks such as low cell-transfection rates and low stability. A great deal of studies on polymer-based transfection agents, mainly focusing on polyplex formation and toxicity, exists. In this study, the electrostatic binding between a brick-like DNA origami and cationic block-copolymers was explored. The effect of the polymer structure on the binding was investigated and the toxicity of the polymer-origami complexes evaluated. The study shows that all of the analyzed polymers had a suitable binding efficiency irrespective of the block structure. It was also observed that the toxicity of polymer-origami complexes was insignificant at the biologically relevant concentration levels. Besides brick-like DNA origamis, tubular origami carriers equipped with enzymes were also coated with the polymers. By adjusting the amount of cationic polymers that cover the DNA structures, we showed that it is possible to control the enzyme kinetics of the complexes. This work gives a starting point for further development of biocompatible and effective polycation-based block copolymers that can be used in coating different DNA origami nanostructures for various bioapplications.DNA origamis are fully tailored, programmable, biocompatible and readily functionalizable nanostructures that provide an excellent foundation for the development of sophisticated drug-delivery systems. However, the DNA origami objects suffer from certain drawbacks such as low cell-transfection rates and low stability. A great deal of studies on polymer-based transfection agents, mainly focusing on polyplex formation and toxicity, exists. In this study, the electrostatic binding between a brick-like DNA origami and cationic block-copolymers was explored. The

  16. Membrane-Based Technologies in the Pharmaceutical Industry and Continuous Production of Polymer-Coated Crystals/Particles.

    PubMed

    Chen, Dengyue; Sirkar, Kamalesh K; Jin, Chi; Singh, Dhananjay; Pfeffer, Robert

    2017-01-01

    Membrane technologies are of increasing importance in a variety of separation and purification applications involving liquid phases and gaseous mixtures. Although the most widely used applications at this time are in water treatment including desalination, there are many applications in chemical, food, healthcare, paper and petrochemical industries. This brief review is concerned with existing and emerging applications of various membrane technologies in the pharmaceutical and biopharmaceutical industry. The goal of this review article is to identify important membrane processes and techniques which are being used or proposed to be used in the pharmaceutical and biopharmaceutical operations. How novel membrane processes can be useful for delivery of crystalline/particulate drugs is also of interest. Membrane separation technologies are extensively used in downstream processes for bio-pharmaceutical separation and purification operations via microfiltration, ultrafiltration and diafiltration. Also the new technique of membrane chromatography allows efficient purification of monoclonal antibodies. Membrane filtration techniques of reverse osmosis and nanofiltration are being combined with bioreactors and advanced oxidation processes to treat wastewaters from pharmaceutical plants. Nanofiltration with organic solvent-stable membranes can implement solvent exchange and catalyst recovery during organic solvent-based drug synthesis of pharmaceutical compounds/intermediates. Membranes in the form of hollow fibers can be conveniently used to implement crystallization of pharmaceutical compounds. The novel crystallization methods of solid hollow fiber cooling crystallizer (SHFCC) and porous hollow fiber anti-solvent crystallization (PHFAC) are being developed to provide efficient methods for continuous production of polymer-coated drug crystals in the area of drug delivery. This brief review provides a general introduction to various applications of membrane technologies in

  17. Cicada-Wing-Inspired Self-Cleaning Antireflection Coatings on Polymer Substrates.

    PubMed

    Chen, Ying-Chu; Huang, Zhe-Sheng; Yang, Hongta

    2015-11-18

    The cicada has transparent wings with remarkable self-cleaning properties and high transmittance over the whole visible spectral range, which is derived from periodic conical structures covering the wing surface. Here we report a scalable self-assembly technique for fabricating multifunctional optical coatings that mimic cicada-wing structures. Spin-coated two-dimensional non-close-packed colloidal crystals are utilized as etching masks to pattern subwavelength-structured cone arrays directly on polymer substrates. The resulting gratings exhibit broadband antireflection performance and superhydrophobic properties after surface modification. The dependence of the cone shape and size on the antireflective and self-cleaning properties has also been investigated in this study.

  18. Chlorine-rich plasma polymer coating for the prevention of attachment of pathogenic fungal cells onto materials surfaces

    NASA Astrophysics Data System (ADS)

    Lamont-Friedrich, Stephanie J.; Michl, Thomas D.; Giles, Carla; Griesser, Hans J.; Coad, Bryan R.

    2016-07-01

    The attachment of pathogenic fungal cells onto materials surfaces, which is often followed by biofilm formation, causes adverse consequences in a wide range of areas. Here we have investigated the ability of thin film coatings from chlorinated molecules to deter fungal colonization of solid materials by contact killing of fungal cells reaching the surface of the coating. Coatings were deposited onto various substrate materials via plasma polymerization, which is a substrate-independent process widely used for industrial coating applications, using 1,1,2-trichloroethane as the process vapour. XPS surface analysis showed that the coatings were characterized by a highly chlorinated hydrocarbon polymer nature, with only a very small amount of oxygen incorporated. The activity of these coatings against human fungal pathogens was quantified using a recently developed, modified yeast assay and excellent antifungal activity was observed against Candida albicans and Candida glabrata. Plasma polymer surface coatings derived from chlorinated hydrocarbon molecules may therefore offer a promising solution to preventing yeast and mould biofilm formation on materials surfaces, for applications such as air conditioners, biomedical devices, food processing equipment, and others.

  19. Water-Based Assembly of Polymer-Metal Organic Framework (MOF) Functional Coatings

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    De, Souvik; Nandasiri, Manjula I.; Schaef, Herbert T.

    Metal organic frameworks (MOFs) have gained tremendous attention for their porosity, size selectivity, and structural diversity. There is a need for MOF-based coatings, particularly in applications such as separations, electronics and energy; yet forming thin, functional, conformal coatings is prohibitive because MOFs exist as a powder. Layer-by- layer assembly, a versatile thin film coating approach, offers a unique solution to this problem, but this approach requires MOFs that are water-dispersible and bear a surface charge. Here, we address these issues by examining water-based dispersions of MIL-101(Cr) that facilitate the formation of robust polymer-MOF hybrid coatings. Specifically, the substrate to bemore » coated is alternately exposed to an aqueous solution of poly(styrene sulfonate) and dispersion MIL-101(Cr), yielding linear film growth and coatings with a MOF content as high as 77 wt%.This approach is surface-agnostic, in which the coating is successfully applied to silicon, glass, flexible plastic, and even cotton fabric, conformally coating individual fibers. In contrast, prior attempts at forming MOF-coatings were severely limited to a handful of surfaces, required harsh chemical treatment, and were not conformal. The approach presented here unambiguously confirms that MOFs can be conformally coated onto complex and unusual surfaces, opening the door for a wide variety of applications.« less

  20. Room Temperature Sensing Achieved by GaAs Nanowires and oCVD Polymer Coating.

    PubMed

    Wang, Xiaoxue; Ermez, Sema; Goktas, Hilal; Gradečak, Silvija; Gleason, Karen

    2017-06-01

    Novel structures comprised of GaAs nanowire arrays conformally coated with conducting polymers (poly(3,4-ethylenedioxythiophene) (PEDOT) or poly(3,4-ethylenedioxythiophene-co-3-thiophene acetic acid) display both sensitivity and selectivity to a variety of volatile organic chemicals. A key feature is room temperature operation, so that neither a heater nor the power it would consume, is required. It is a distinct difference from traditional metal oxide sensors, which typically require elevated operational temperature. The GaAs nanowires are prepared directly via self-seeded metal-organic chemical deposition, and conducting polymers are deposited on GaAs nanowires using oxidative chemical vapor deposition (oCVD). The range of thickness for the oCVD layer is between 100 and 200 nm, which is controlled by changing the deposition time. X-ray diffraction analysis indicates an edge-on alignment of the crystalline structure of the PEDOT coating layer on GaAs nanowires. In addition, the positive correlation between the improvement of sensitivity and the increasing nanowire density is demonstrated. Furthermore, the effect of different oCVD coating materials is studied. The sensing mechanism is also discussed with studies considering both nanowire density and polymer types. Overall, the novel structure exhibits good sensitivity and selectivity in gas sensing, and provides a promising platform for future sensor design. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Polymer blends used for the aqueous coating of solid dosage forms: importance of the type of plasticizer.

    PubMed

    Lecomte, F; Siepmann, J; Walther, M; MacRae, R J; Bodmeier, R

    2004-09-14

    The aim of this study was to investigate the importance of the type of plasticizer in polymer blends used for the coating of solid dosage forms, comparing a lipophilic and a hydrophilic plasticizer (dibutyl sebacate (DBS) and triethyl citrate (TEC)). In vitro drug release from propranolol hydrochloride (propranolol HCl)-loaded pellets coated with blends of ethyl cellulose (EC) and Eudragit L (100:0, 75:25, 50:50, 25:75 and 0:100 w/w) was investigated at low as well as at high pH. To better understand the underlying mass transport mechanisms, the physicochemical properties of the film coatings (e.g. mechanical resistance, water uptake and dry weight loss behavior) were determined. Interestingly, drug release strongly depended on the type of plasticizer. Importantly, not only the slope but also the shape of the release curves was affected, indicating that the chemical nature of the plasticizer plays a major role for the underlying drug release mechanisms. Diffusion through the intact polymer coatings and/or through water-filled cracks was found to be dominating for the control of drug release. The relative importance of these pathways strongly depended on the polymer blend ratio and type of plasticizer. In contrast to DBS, TEC rapidly leached out of the coatings, resulting in decreasing mechanical resistances of the films and, thus, facilitated crack formation. In addition, the hydrophilicity of the plasticizer significantly affected the water uptake behavior of the film coatings and, hence, changes in the coatings' toughness and drug permeability. Also the relative affinity of the plasticizer to the different polymers was found to be of significance. In contrast to TEC, DBS has a higher affinity to EC than to Eudragit L, resulting in potential redistributions of this plasticizer within the polymeric systems and changes in the release profiles during storage. Importantly, these effects could be avoided with appropriate curing conditions and preparation techniques for

  2. Multi-Layer Coating of Ultrathin Polymer Films on Nanoparticles of Alumina by a Plasma Treatment

    DTIC Science & Technology

    2001-01-01

    Proc. Vol. 635 © 2001 Materials Research Society Multi-Layer Coating of Ultrathin Polymer Films on Nanoparticles of Alumina by a Plasma Treatment Donglu...interconnected organic and inorganic networks results in coatings with a very low permeability for gases and liquids. Hybrid materials are very suitable for... materials consist of a clear alcoholic solution that can easily be processed by classical application techniques such as dipping, spraying, or spin coating

  3. Anhydrous polymer-based coating with sustainable controlled release functionality for facile, efficacious impregnation, and delivery of antimicrobial peptides.

    PubMed

    Lim, Kaiyang; Saravanan, Rathi; Chong, Kelvin K L; Goh, Sharon H M; Chua, Ray R Y; Tambyah, Paul A; Chang, Matthew W; Kline, Kimberly A; Leong, Susanna S J

    2018-04-17

    Anhydrous polymers are actively explored as alternative materials to overcome limitations of conventional hydrogel-based antibacterial coating. However, the requirement for strong organic solvent in polymerization reactions often necessitates extra protection steps for encapsulation of target biomolecules, lowering encapsulation efficiency, and increasing process complexity. This study reports a novel coating strategy that allows direct solvation and encapsulation of antimicrobial peptides (HHC36) into anhydrous polycaprolactone (PCL) polymer-based dual layer coating. A thin 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) film is layered onto the peptide-impregnated PCL as a diffusion barrier, to modulate and enhance release kinetics. The impregnated peptides are eventually released in a controlled fashion. The use of 2,2,2-trifluoroethanol (TFE), as polymerization and solvation medium, induces the impregnated peptides to adopt highly stable turned conformation, conserving peptide integrity, and functionality during both encapsulation and subsequent release processes. The dual layer coating showed sustained antibacterial functionality, lasting for 14 days. In vivo assessment using an experimental mouse wounding model demonstrated good biocompatibility and significant antimicrobial efficacy of the coating under physiological conditions. The coating was translated onto silicone urinary catheters and showed promising antibacterial efficacy, even outperforming commercial silver-based Dover cather. This anhydrous polymer-based platform holds immense potential as an effective antibacterial coating to prevent clinical device-associated infections. The simplicity of the coating process enhances its industrial viability. © 2018 Wiley Periodicals, Inc.

  4. Optical coatings of variable refractive index and high laser-resistance from physical-vapor-deposited perfluorinated amorphous polymer

    DOEpatents

    Chow, Robert; Loomis, Gary E.; Thomas, Ian M.

    1999-01-01

    Variable index optical single-layers, optical multilayer, and laser-resistant coatings were made from a perfluorinated amorphous polymer material by physical vapor deposition. This was accomplished by physically vapor depositing a polymer material, such as bulk Teflon AF2400, for example, to form thin layers that have a very low refractive index (.about.1.10-1.31) and are highly transparent from the ultra-violet through the near infrared regime, and maintain the low refractive index of the bulk material. The refractive index can be varied by simply varying one process parameter, either the deposition rate or the substrate temperature. The thus forming coatings may be utilized in anti-reflectors and graded anti-reflection coatings, as well as in optical layers for laser-resistant coatings at optical wavelengths of less than about 2000 nm.

  5. In-situ Preparation of Polymer-Coated Zirconia Nanoparticles by Decomposition of Zirconium-Tert-Butoxide

    DTIC Science & Technology

    2003-01-01

    coated under conditions C are slightly yellow coloured. The zirconia powders collected at position 1 is white. Table I: Plasma parameters of the...pulsed) 99 1 39 40 2,5 2,5 379 400D. 2000 1000 - 20 0 40 4 140 20 [°1 Figure 2: XRD diffractrogram of zirconia powder coated with polymer Zirconia...wave nunter [crn"] Figure 3: FTIR spectra of plasma treated zirconia powders collected at position 2 (coated) prepared under A) continuous plasma B

  6. Spin-coated epoxy resin embedding technique enables facile SEM/FIB thickness determination of porous metal oxide ultra-thin films.

    PubMed

    Peña, B; Owen, G Rh; Dettelbach, K E; Berlinguette, C P

    2018-01-25

    A facile nonsubjective method was designed to measure porous nonconductive iron oxide film thickness using a combination of a focused ion beam (FIB) and scanning electron microscopy. Iron oxide films are inherently nonconductive and porous, therefore the objective of this investigation was to optimize a methodology that would increase the conductivity of the film to facilitate high resolution imaging with a scanning electron microscopy and to preserve the porous nature of the film that could potentially be damaged by the energy of the FIB. Sputter coating the sample with a thin layer of iridium before creating the cross section with the FIB decreased sample charging and drifting, but differentiating the iron layer from the iridium coating with backscattered electron imaging was not definitive, making accurate assumptions of the delineation between the two metals difficult. Moreover, the porous nature of the film was lost due to beam damage following the FIB process. A thin layer plastication technique was therefore used to embed the porous film in epoxy resin that would provide support for the film during the FIB process. However, the thickness of the resin created using conventional thin layer plastication processing varied across the sample, making the measuring process only possible in areas where the resin layer was at its thinnest. Such variation required navigating the area for ideal milling areas, which increased the subjectivity of the process. We present a method to create uniform thin resin layers, of controlled thickness, that are ideal for quantifying the thickness of porous nonconductive films with FIB/scanning electron microscopy. © 2018 The Authors Journal of Microscopy © 2018 Royal Microscopical Society.

  7. Iontophoretic transport of associates based on porous Keplerate-type cluster polyoxometalate Mo72Fe30 and containing biologically active substances

    NASA Astrophysics Data System (ADS)

    Ostroushko, A. A.; Gagarin, I. D.; Tonkushina, M. O.; Grzhegorzhevskii, K. V.; Danilova, I. G.; Gette, I. F.; Kim, G. A.

    2017-09-01

    The possibility of iontophoretic transport through the native membranes of biologically active substances (vitamin B1 and insulin) associated with porous clusters Mo72Fe30 polyoxometalate of the Keplerate type is demonstrated for the first time in an experimental setup. The diffusion coefficient is estimated. The possibility of transferring Keplerate ions with a protective coating of biocompatible polymer polyvinylpyrrolidone is also shown.

  8. A highly durable fuel cell electrocatalyst based on double-polymer-coated carbon nanotubes

    PubMed Central

    Berber, Mohamed R.; Hafez, Inas H.; Fujigaya, Tsuyohiko; Nakashima, Naotoshi

    2015-01-01

    Driven by the demand for the commercialization of fuel cell (FC) technology, we describe the design and fabrication of a highly durable FC electrocatalyst based on double-polymer-coated carbon nanotubes for use in polymer electrolyte membrane fuel cells. The fabricated electrocatalyst is composed of Pt-deposited polybenzimidazole-coated carbon nanotubes, which are further coated with Nafion. By using this electrocatalyst, a high FC performance with a power density of 375 mW/cm2 (at 70 ˚C, 50% relative humidity using air (cathode)/H2(anode)) was obtained, and a remarkable durability of 500,000 accelerated potential cycles was recorded with only a 5% loss of the initial FC potential and 20% loss of the maximum power density, which were far superior properties compared to those of the membrane electrode assembly prepared using carbon black in place of the carbon nanotubes. The present study indicates that the prepared highly durable fuel cell electrocatalyst is a promising material for the next generation of PEMFCs. PMID:26594045

  9. Ultrathin nickel hydroxide on carbon coated 3D-porous copper structures for high performance supercapacitors.

    PubMed

    Kang, Kyeong-Nam; Kim, Ik-Hee; Ramadoss, Ananthakumar; Kim, Sun-I; Yoon, Jong-Chul; Jang, Ji-Hyun

    2018-01-03

    An ultrathin nickel hydroxide layer electrodeposited on a carbon-coated three-dimensional porous copper structure (3D-C/Cu) is suggested as an additive and binder-free conductive electrode with short electron path distances, large electrochemical active sites, and improved structural stability, for high performance supercapacitors. The 3D-porous copper structure (3D-Cu) provides high electrical conductivity and facilitates electron transport between the Ni(OH) 2 active materials and the current collector of the Ni-plate. A carbon coating was applied to the 3D-Cu to prevent the oxidation of Cu, without degrading the electron transport behavior of the 3D-Cu. The 3D-Ni(OH) 2 /C/Cu exhibited a high specific capacitance of 1860 F g -1 at 1 A g -1 , and good cycling performance, with an 86.5% capacitance retention after 10 000 cycles. When tested in a two-electrode system, an asymmetric supercapacitor exhibited an energy density of 147.9 W h kg -1 and a power density of 37.0 kW kg -1 . These results open a new area of ultrahigh-performance supercapacitors, supported by 3D-Cu electrodes.

  10. Anodized porous titanium coated with Ni-CeO2 deposits for enhancing surface toughness and wear resistance

    NASA Astrophysics Data System (ADS)

    Zhou, Xiaowei; Ouyang, Chun

    2017-05-01

    In order to make large improvements of surface toughness and wear resistance for pure titanium (Ti) substrate, anodic titanium oxide (ATO) surface with nanoporous structure was coated with the Ni-CeO2 nanocomposite coatings. Regarding TiO2 barrier layer on Ti surface to inhibit its electrochemical activity, pre-treatments were successively processed with anodizing, sensitizing, activating, and then followed by electroless Ni-P film to be acted as an activated layer for electroplating Ni-CeO2 deposits. The existing Pd atoms around ATO nanopores were expected as the heterogeneous nucleation sites for supporting the growing locations of electroless Ni-P film. The innovative of interface design using porous structure was introduced for bonding pinholes to achieve a metallurgical adhesion interface between Ti substrate and surface coatings. Besides the objectives of this work were to elucidate how effects by the adding CeO2 nanoparticles on modifying microstructures and wear mechanisms of Ni-CeO2 nanocomposite coatings. Many efforts of XRD, FE-SEM, TEM and Nanoindentation tests were devoted to comparing different wear behaviors of Ni-CeO2 coatings relative to pure nickel. Results indicated that uniform-distributed Ti nanopores with an average diameter size of ∼200 nm was achieved using the Phosphate-type anodizing solution at DC 150 V. A worn surface without fatigue cracks was observed for TAO surface coated with Ni-CeO2 deposits, showing the existing Ce-rich worn products to be acted as a solid lubricant phase for making a self-healing effect on de-lamination failures. More important, this finding will be the guidelines for Ce-rich precipitations to be expected as the strengthening phase in anodized porous of Ti, Al and Mg alloys for intensifying their surface properties.

  11. Cationic polymers for DNA origami coating - examining their binding efficiency and tuning the enzymatic reaction rates.

    PubMed

    Kiviaho, Jenny K; Linko, Veikko; Ora, Ari; Tiainen, Tony; Järvihaavisto, Erika; Mikkilä, Joona; Tenhu, Heikki; Nonappa; Kostiainen, Mauri A

    2016-06-02

    DNA origamis are fully tailored, programmable, biocompatible and readily functionalizable nanostructures that provide an excellent foundation for the development of sophisticated drug-delivery systems. However, the DNA origami objects suffer from certain drawbacks such as low cell-transfection rates and low stability. A great deal of studies on polymer-based transfection agents, mainly focusing on polyplex formation and toxicity, exists. In this study, the electrostatic binding between a brick-like DNA origami and cationic block-copolymers was explored. The effect of the polymer structure on the binding was investigated and the toxicity of the polymer-origami complexes evaluated. The study shows that all of the analyzed polymers had a suitable binding efficiency irrespective of the block structure. It was also observed that the toxicity of polymer-origami complexes was insignificant at the biologically relevant concentration levels. Besides brick-like DNA origamis, tubular origami carriers equipped with enzymes were also coated with the polymers. By adjusting the amount of cationic polymers that cover the DNA structures, we showed that it is possible to control the enzyme kinetics of the complexes. This work gives a starting point for further development of biocompatible and effective polycation-based block copolymers that can be used in coating different DNA origami nanostructures for various bioapplications.

  12. Thermomechanical analysis and durability of commercial micro-porous polymer Li-ion battery separators

    NASA Astrophysics Data System (ADS)

    Love, Corey T.

    2011-03-01

    Static and dynamic thermomechanical analysis was performed with a dynamic mechanical analyzer (DMA) to identify thermal and mechanical transitions for commercially available polymer separators under mechanical loading. Clear transitions in deformation mode were observed at elevated temperatures. These transitions identified the onset of separator "shutdown" which occurred at temperatures below the polymer melting point. Mechanical loading direction was critical to the overall integrity of the separator. Anisotropic separators (Celgard 2320, 2400 and 2500) were mechanically limited when pulled in tensile in the transverse direction. The anisotropy of these separators is a result of the dry technique used to manufacture the micro-porous membranes. Separators prepared using the wet technique (Entek Gold LP) behaved more uniformly, or biaxially, where all mechanical properties were nearly identical within the separator plane. The information provided by the DMA can also be useful for predicting the long-term durability of polymer separators in lithium-ion batteries exposed to electrolyte (solvent and salt), thermal fluctuations and electrochemical cycling. Small losses in mechanical integrity were observed for separators exposed to the various immersion environments over the 4-week immersion time.

  13. Graphene Oxide-Copper Nanocomposite-Coated Porous CaP Scaffold for Vascularized Bone Regeneration via Activation of Hif-1α.

    PubMed

    Zhang, Wenjie; Chang, Qing; Xu, Ling; Li, Guanglong; Yang, Guangzheng; Ding, Xun; Wang, Xiansong; Cui, Daxiang; Jiang, Xinquan

    2016-06-01

    Graphene has been studied for its in vitro osteoinductive capacity. However, the in vivo bone repair effects of graphene-based scaffolds remain unknown. The aqueous soluble graphene oxide-copper nanocomposites (GO-Cu) are fabricated, which are used to coat porous calcium phosphate (CaP) scaffolds for vascularized bone regeneration. The GO-Cu nanocomposites, containing crystallized CuO/Cu2 O nanoparticles of ≈30 nm diameters, distribute uniformly on the surfaces of the porous scaffolds and maintain a long-term release of Cu ions. In vitro, the GO-Cu coating enhances the adhesion and osteogenic differentiation of rat bone marrow stem cells (BMSCs). It is also found that by activating the Erk1/2 signaling pathway, the GO-Cu nanocomposites upregulate the expression of Hif-1α in BMSCs, resulting in the secretion of VEGF and BMP-2 proteins. When transplanted into rat with critical-sized calvarial defects, the GO-Cu-coated calcium phosphate cement (CPC) scaffolds (CPC/GO-Cu) significantly promote angiogenesis and osteogenesis. Moreover, it is observed via histological sections that the GO-Cu nanocomposites are phagocytosed by multinucleated giant cells. The results suggest that GO-Cu nanocomposite coatings can be utilized as an attractive strategy for vascularized bone regeneration. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. The Development of a High-Throughput/Combinatorial Workflow for the Study of Porous Polymer Networks

    DTIC Science & Technology

    2012-04-05

    poragen composition , poragen level, and cure temperature. A total of 216 unique compositions were prepared. Changes in opacity of the blends as they cured...allowed for the identification of compositional variables and process variables that enabled the production of porous networks. Keywords: high...in polymer network cross-link density,poragen composition , poragen level, and cure temperature. A total of 216 unique compositions were prepared

  15. Porous silicon-cyclodextrin based polymer composites for drug delivery applications.

    PubMed

    Hernandez-Montelongo, J; Naveas, N; Degoutin, S; Tabary, N; Chai, F; Spampinato, V; Ceccone, G; Rossi, F; Torres-Costa, V; Manso-Silvan, M; Martel, B

    2014-09-22

    One of the main applications of porous silicon (PSi) in biomedicine is drug release, either as a single material or as a part of a composite. PSi composites are attractive candidates for drug delivery systems because they can display new chemical and physical characteristics, which are not exhibited by the individual constituents alone. Since cyclodextrin-based polymers have been proven efficient materials for drug delivery, in this work β-cyclodextrin-citric acid in-situ polymerization was used to functionalize two kinds of PSi (nanoporous and macroporous). The synthesized composites were characterized by microscopy techniques (SEM and AFM), physicochemical methods (ATR-FTIR, XPS, water contact angle, TGA and TBO titration) and a preliminary biological assay was performed. Both systems were tested as drug delivery platforms with two different model drugs, namely, ciprofloxacin (an antibiotic) and prednisolone (an anti-inflammatory), in two different media: pure water and PBS solution. Results show that both kinds of PSi/β-cyclodextrin-citric acid polymer composites, nano- and macro-, provide enhanced release control for drug delivery applications than non-functionalized PSi samples. Copyright © 2014 Elsevier Ltd. All rights reserved.

  16. Porous PZT ceramics for receiving transducers.

    PubMed

    Kara, Hudai; Ramesh, Rajamani; Stevens, Ron; Bowen, Chris R

    2003-03-01

    PZT-air (porous PZT) and PZT-polymer (polymer impregnated porous PZT) piezocomposites with varying porosity/polymer volume fractions have been manufactured. The composites were characterized in terms of hydrostatic charge (dh) and voltage (gh) coefficients, permittivity, hydrostatic figure of merit (dh.gh), and absolute sensitivity (M). With decreasing PZT ceramic volume, gh increased, and dh.gh had a broad maximum around 80 to 90% porosity/polymer content. The absolute sensitivity was also increased. In each case, PZT-air piezocomposites performed better than PZT-polymer piezocomposites. Hydrophones constructed from piezocomposites showed slightly lower measured receiving sensitivities than calculated values for piezocomposite materials, which was due to the loading effect of the cable and the low permittivity associated with the piezocomposites.

  17. Uniformly coated highly porous graphene/MnO2 foams for flexible asymmetric supercapacitors

    NASA Astrophysics Data System (ADS)

    Drieschner, Simon; von Seckendorff, Maximilian; del Corro, Elena; Wohlketzetter, Jörg; Blaschke, Benno M.; Stutzmann, Martin; Garrido, Jose A.

    2018-06-01

    Supercapacitors are called to play a prominent role in the newly emerging markets of electric vehicles, flexible displays and sensors, and wearable electronics. In order to compete with current battery technology, supercapacitors have to be designed with highly conductive current collectors exhibiting high surface area per unit volume and uniformly coated with pseudocapacitive materials, which is crucial to boost the energy density while maintaining a high power density. Here, we present a versatile technique to prepare thickness-controlled thin-film micro graphene foams (μGFs) with pores in the lower micrometer range grown by chemical vapor deposition which can be used as highly conductive current collectors in flexible supercapacitors. To fabricate the μGF, we use porous metallic catalytic substrates consisting of nickel/copper alloy synthesized on nickel foil by electrodeposition in an electrolytic solution. Changing the duration of the electrodeposition allows the control of the thickness of the metal foam, and thus of the μGF, ranging from a few micrometers to the millimeter scale. The resulting μGF with a thickness and pores in the micrometer regime exhibits high structural quality which leads to a very low intrinsic resistance of the devices. Transferred onto flexible substrates, we demonstrate a uniform coating of the μGFs with manganese oxide, a pseudocapacitively active material. Considering the porous structure and the thickness of the μGFs, square wave potential pulses are used to ensure uniform coverage by the oxide material boosting the volumetric and areal capacitance to 14 F cm‑3 and 0.16 F cm‑2. The μGF with a thickness and pores in the micrometer regime in combination with a coating technique tuned to the porosity of the μGF is of great relevance for the development of supercapacitors based on state-of-the-art graphene foams.

  18. Uniformly coated highly porous graphene/MnO2 foams for flexible asymmetric supercapacitors.

    PubMed

    Drieschner, Simon; Seckendorff, Maximilian von; Corro, Elena Del; Wohlketzetter, Jörg; Blaschke, Benno M; Stutzmann, Martin; Garrido, Jose A

    2018-06-01

    Supercapacitors are called to play a prominent role in the newly emerging markets of electric vehicles, flexible displays and sensors, and wearable electronics. In order to compete with current battery technology, supercapacitors have to be designed with highly conductive current collectors exhibiting high surface area per unit volume and uniformly coated with pseudocapacitive materials, which is crucial to boost the energy density while maintaining a high power density. Here, we present a versatile technique to prepare thickness-controlled thin-film micro graphene foams (μGFs) with pores in the lower micrometer range grown by chemical vapor deposition which can be used as highly conductive current collectors in flexible supercapacitors. To fabricate the μGF, we use porous metallic catalytic substrates consisting of nickel/copper alloy synthesized on nickel foil by electrodeposition in an electrolytic solution. Changing the duration of the electrodeposition allows the control of the thickness of the metal foam, and thus of the μGF, ranging from a few micrometers to the millimeter scale. The resulting μGF with a thickness and pores in the micrometer regime exhibits high structural quality which leads to a very low intrinsic resistance of the devices. Transferred onto flexible substrates, we demonstrate a uniform coating of the μGFs with manganese oxide, a pseudocapacitively active material. Considering the porous structure and the thickness of the μGFs, square wave potential pulses are used to ensure uniform coverage by the oxide material boosting the volumetric and areal capacitance to 14 F cm -3 and 0.16 F cm -2 . The μGF with a thickness and pores in the micrometer regime in combination with a coating technique tuned to the porosity of the μGF is of great relevance for the development of supercapacitors based on state-of-the-art graphene foams.

  19. Optical coatings of variable refractive index and high laser-resistance from physical-vapor-deposited perfluorinated amorphous polymer

    DOEpatents

    Chow, R.; Loomis, G.E.; Thomas, I.M.

    1999-03-16

    Variable index optical single-layers, optical multilayer, and laser-resistant coatings were made from a perfluorinated amorphous polymer material by physical vapor deposition. This was accomplished by physically vapor depositing a polymer material, such as bulk Teflon AF2400, for example, to form thin layers that have a very low refractive index (ca. 1.10--1.31) and are highly transparent from the ultra-violet through the near infrared regime, and maintain the low refractive index of the bulk material. The refractive index can be varied by simply varying one process parameter, either the deposition rate or the substrate temperature. The thus forming coatings may be utilized in anti-reflectors and graded anti-reflection coatings, as well as in optical layers for laser-resistant coatings at optical wavelengths of less than about 2000 nm. 2 figs.

  20. Femtosecond laser direct-write of optofluidics in polymer-coated optical fiber

    NASA Astrophysics Data System (ADS)

    Joseph, Kevin A. J.; Haque, Moez; Ho, Stephen; Aitchison, J. Stewart; Herman, Peter R.

    2017-03-01

    Multifunctional lab in fiber technology seeks to translate the accomplishments of optofluidic, lab on chip devices into silica fibers. a robust, flexible, and ubiquitous optical communication platform that can underpin the `Internet of Things' with distributed sensors, or enable lab on chip functions deep inside our bodies. Femtosecond lasers have driven significant advances in three-dimensional processing, enabling optical circuits, microfluidics, and micro-mechanical structures to be formed around the core of the fiber. However, such processing typically requires the stripping and recoating of the polymer buffer or jacket, increasing processing time and mechanically weakening the device. This paper reports on a comprehensive assessment of laser damage in urethane-acrylate-coated fiber. The results show a sufficient processing window is available for femtosecond laser processing of the fiber without damaging the polymer jacket. The fiber core, cladding, and buffer could be simultaneously processed without removal of the buffer jacket. Three-dimensional lab in fiber devices were successfully fabricated by distortion-free immersionlens focusing, presenting fiber-cladding optical circuits and progress towards chemically-etched channels, microfluidic cavities, and MEMS structure inside buffer-coated fiber.

  1. Coating and functionalization of high density ion track structures by atomic layer deposition

    NASA Astrophysics Data System (ADS)

    Mättö, Laura; Szilágyi, Imre M.; Laitinen, Mikko; Ritala, Mikko; Leskelä, Markku; Sajavaara, Timo

    2016-10-01

    In this study flexible TiO2 coated porous Kapton membranes are presented having electron multiplication properties. 800 nm crossing pores were fabricated into 50 μm thick Kapton membranes using ion track technology and chemical etching. Consecutively, 50 nm TiO2 films were deposited into the pores of the Kapton membranes by atomic layer deposition using Ti(iOPr)4 and water as precursors at 250 °C. The TiO2 films and coated membranes were studied by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray reflectometry (XRR). Au metal electrode fabrication onto both sides of the coated foils was achieved by electron beam evaporation. The electron multipliers were obtained by joining two coated membranes separated by a conductive spacer. The results show that electron multiplication can be achieved using ALD-coated flexible ion track polymer foils.

  2. Accelerated cell-surface interlocking on plasma polymer-modified porous ceramics.

    PubMed

    Rebl, Henrike; Finke, Birgit; Schmidt, Jürgen; Mohamad, Heba S; Ihrke, Roland; Helm, Christiane A; Nebe, J Barbara

    2016-12-01

    Excellent osseointegration of permanent implants is crucial for the long lasting success of the implantation. To improve the osseointegrative potential, bio-inert titanium alloy surfaces (Ti6Al4V) are modified by plasma chemical oxidation (PCO®) of the titanium-oxide layer to a non-stoichiometric, amorphous calcium phosphate layer. The native titanium-oxide film measuring only a few nanometers is converted by PCO® to a thick porous calcium phosphate layer of about 10μm. In a second step the PCO surface is combined with a cell adhesive plasma-polymerized allylamine (PPAAm) nano film (5 and 50nm). Independent of the PPAAm coating homogeneity, the human osteoblast-like MG-63 cells show a remarkable increase in cell size and well-developed filopodia. Analyses of the actin cytoskeleton reveal that the cells mold to the pore shape of the PPAAm-covered PCO, thereby establishing a strong attachment to the surface. Interestingly, we could demonstrate that even though our untreated PCO shows excellent hydrophilicity, this alone is not sufficient to facilitate fast cell spreading, but the positive surface charges mediated by PPAAm. This multilayer composite material guarantees enhanced interlocking of the cells with the porous surface. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Evaluation of coated metallic bipolar plates for polymer electrolyte membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Yoon, Wonseok; Huang, Xinyu; Fazzino, Paul; Reifsnider, Kenneth L.; Akkaoui, Michael A.

    Metallic bipolar plates for polymer electrolyte membrane (PEM) fuel cells typically require coatings for corrosion protection. Other requirements for the corrosion protective coatings include low electrical contact resistance, good mechanical robustness, low material and fabrication cost. The authors have evaluated a number of protective coatings deposited on stainless steel substrates by electroplating and physical vapor deposition (PVD) methods. The coatings are screened with an electrochemical polarization test for corrosion resistance; then the contact resistance test was performed on selected coatings. The coating investigated include Gold with various thicknesses (2 nm, 10 nm, and 1 μm), Titanium, Zirconium, Zirconium Nitride (ZrN), Zirconium Niobium (ZrNb), and Zirconium Nitride with a Gold top layer (ZrNAu). The substrates include three types of stainless steel: 304, 310, and 316. The results show that Zr-coated samples satisfy the DOE target for corrosion resistance at both anode and cathode sides in typical PEM fuel cell environments in the short-term, but they do not meet the DOE contact resistance goal. Very thin gold coating (2 nm) can significantly decrease the electrical contact resistance, however a relatively thick gold coating (>10 nm) with our deposition method is necessary for adequate corrosion resistance, particularly for the cathode side of the bipolar plate.

  4. Water Transport in the Micro Porous Layer and Gas Diffusion Layer of a Polymer Electrolyte Fuel Cell

    NASA Astrophysics Data System (ADS)

    Qin, C.; Hassanizadeh, S. M.

    2015-12-01

    In this work, a recently developed dynamic pore-network model is presented [1]. The model explicitly solves for both water pressure and capillary pressure. A semi-implicit scheme is used in updating water saturation in each pore body, which considerably increases the numerical stability at low capillary number values. Furthermore, a multiple-time-step algorithm is introduced to reduce the computational effort. A number of case studies of water transport in the micro porous layer (MPL) and gas diffusion layer (GDL) are conducted. We illustrate the role of MPL in reducing water flooding in the GDL. Also, the dynamic water transport through the MPL-GDL interface is explored in detail. This information is essential to the reduced continua model (RCM), which was developed for multiphase flow through thin porous layers [2, 3]. C.Z. Qin, Water transport in the gas diffusion layer of a polymer electrolyte fuel cell: dynamic pore-network modeling, J Electrochimical. Soci., 162, F1036-F1046, 2015. C.Z. Qin and S.M. Hassanizadeh, Multiphase flow through multilayers of thin porous media: general balance equations and constitutive relationships for a solid-gas-liquid three-phase system, Int. J. Heat Mass Transfer, 70, 693-708, 2014. C.Z. Qin and S.M. Hassanizadeh, A new approach to modeling water flooding in a polymer electrolyte fuel cell, Int. J. Hydrogen Energy, 40, 3348-3358, 2015.

  5. Sol-Gel Processing of MgF₂ Antireflective Coatings.

    PubMed

    Löbmann, Peer

    2018-05-02

    There are different approaches for the preparation of porous antireflective λ/4 MgF₂ films from liquid precursors. Among these, the non-aqueous fluorolytic synthesis of precursor solutions offers many advantages in terms of processing simplicity and scalability. In this paper, the structural features and optical performance of the resulting films are highlighted, and their specific interactions with different inorganic substrates are discussed. Due to their excellent abrasion resistance, coatings have a high potential for applications on glass. Using solvothermal treatment of precursor solutions, also the processing of thermally sensitive polymer substrates becomes feasible.

  6. Electrophoretically active sol-gel processes to backfill, seal, and/or densify porous, flawed, and/or cracked coatings on electrically conductive material

    DOEpatents

    Panitz, Janda K.; Reed, Scott T.; Ashley, Carol S.; Neiser, Richard A.; Moffatt, William C.

    1999-01-01

    Electrophoretically active sol-gel processes to fill, seal, and/or density porous, flawed, and/or cracked coatings on electrically conductive substrates. Such coatings may be dielectrics, ceramics, or semiconductors and, by the present invention, may have deposited onto and into them sol-gel ceramic precursor compounds which are subsequently converted to sol-gel ceramics to yield composite materials with various tailored properties.

  7. Porous SiO2 nanofiber grafted novel bioactive glass-ceramic coating: A structural scaffold for uniform apatite precipitation and oriented cell proliferation on inert implant.

    PubMed

    Das, Indranee; De, Goutam; Hupa, Leena; Vallittu, Pekka K

    2016-05-01

    A composite bioactive glass-ceramic coating grafted with porous silica nanofibers was fabricated on inert glass to provide a structural scaffold favoring uniform apatite precipitation and oriented cell proliferation. The coating surfaces were investigated thoroughly before and after immersion in simulated body fluid. In addition, the proliferation behavior of fibroblast cells on the surface was observed for several culture times. The nanofibrous exterior of this composite bioactive coating facilitated homogeneous growth of flake-like carbonated hydroxyapatite layer within a short period of immersion. Moreover, the embedded porous silica nanofibers enhanced hydrophilicity which is required for proper cell adhesion on the surface. The cells proliferated well following a particular orientation on the entire coating by the assistance of nanofibrous scaffold-like structural matrix. This newly engineered composite coating was effective in creating a biological structural matrix favorable for homogeneous precipitation of calcium phosphate, and organized cell growth on the inert glass surface. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. 25th anniversary article: CVD polymers: a new paradigm for surface modification and device fabrication.

    PubMed

    Coclite, Anna Maria; Howden, Rachel M; Borrelli, David C; Petruczok, Christy D; Yang, Rong; Yagüe, Jose Luis; Ugur, Asli; Chen, Nan; Lee, Sunghwan; Jo, Won Jun; Liu, Andong; Wang, Xiaoxue; Gleason, Karen K

    2013-10-11

    Well-adhered, conformal, thin (<100 nm) coatings can easily be obtained by chemical vapor deposition (CVD) for a variety of technological applications. Room temperature modification with functional polymers can be achieved on virtually any substrate: organic, inorganic, rigid, flexible, planar, three-dimensional, dense, or porous. In CVD polymerization, the monomer(s) are delivered to the surface through the vapor phase and then undergo simultaneous polymerization and thin film formation. By eliminating the need to dissolve macromolecules, CVD enables insoluble polymers to be coated and prevents solvent damage to the substrate. CVD film growth proceeds from the substrate up, allowing for interfacial engineering, real-time monitoring, and thickness control. Initiated-CVD shows successful results in terms of rationally designed micro- and nanoengineered materials to control molecular interactions at material surfaces. The success of oxidative-CVD is mainly demonstrated for the deposition of organic conducting and semiconducting polymers. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Polymeric Coatings for Combating Biocorrosion

    NASA Astrophysics Data System (ADS)

    Guo, Jing; Yuan, Shaojun; Jiang, Wei; Lv, Li; Liang, Bin; Pehkonen, Simo O.

    2018-03-01

    Biocorrosion has been considered as big trouble in many industries and marine environments due to causing great economic loss. The main disadvantages of present approaches to prevent corrosion include being limited by environmental factors, being expensive, inapplicable to field, and sometimes inefficient. Studies show that polymer coatings with anti-corrosion and anti-microbial properties have been widely accepted as a novel and effective approach to preventbiocorrosion. The main purpose of this review is to summarize up the progressive status of polymer coatings used for combating microbially-induced corrosion. Polymers used to synthesize protective coatings are generally divided into three categories: i) traditional polymers incorporated with biocides, ii) antibacterial polymers containing quaternary ammonium compounds, and iii) conductive polymers. The strategies to synthesize polymer coatings resort mainly to grafting anti-bacterial polymers from the metal substrate surface using novel surface-functionalization approaches, such as free radical polymerization, chemically oxidative polymerization and surface-initiated atom transfer radical polymerization, as opposed to the traditional approaches of dip coating or spin coating.

  10. A novel approach to a fine particle coating using porous spherical silica as core particles.

    PubMed

    Ishida, Makoto; Uchiyama, Jumpei; Isaji, Keiko; Suzuki, Yuta; Ikematsu, Yasuyuki; Aoki, Shigeru

    2014-08-01

    Abstract The applicability of porous spherical silica (PSS) was evaluated as core particles for pharmaceutical products by comparing it with commercial core particles such as mannitol (NP-108), sucrose and microcrystalline cellulose spheres. We investigated the physical properties of core particles, such as particle size distribution, flow properties, crushing strength, plastic limit, drying rate, hygroscopic property and aggregation degree. It was found that PSS was a core particle of small particle size, low friability, high water adsorption capacity, rapid drying rate and lower occurrence of particle aggregation, although wettability is a factor to be carefully considered. The aggregation and taste-masking ability using PSS and NP-108 as core particles were evaluated at a fluidized-bed coating process. The functional coating under the excess spray rate shows different aggregation trends and dissolution profiles between PSS and NP-108; thereby, exhibiting the formation of uniform coating under the excess spray rate in the case of PSS. This expands the range of the acceptable spray feed rates to coat fine particles, and indicates the possibility of decreasing the coating time. The results obtained in this study suggested that the core particle, which has a property like that of PSS, was useful in overcoming such disadvantages as large particle size, which feels gritty in oral cavity; particle aggregation; and the long coating time of the particle coating process. These results will enable the practical fine particle coating method by increasing the range of optimum coating conditions and decreasing the coating time in fluidized bed technology.

  11. Novel biodegradable calcium phosphate/polymer composite coating with adjustable mechanical properties formed by hydrothermal process for corrosion protection of magnesium substrate.

    PubMed

    Kaabi Falahieh Asl, Sara; Nemeth, Sandor; Tan, Ming Jen

    2016-11-01

    Ceramic type coatings on metallic implants, such as calcium phosphate (Ca-P), are generally stiff and brittle, potentially leading to the early failure of the bone-implant interface. To reduce material brittleness, polyacrylic acid and carboxymethyl cellulose were used in this study to deposit two types of novel Ca-P/polymer composite coatings on AZ31 magnesium alloy using a one-step hydrothermal process. X-ray diffraction and scanning electron microscopy showed that the deposited Ca-P crystal phase and morphology could be controlled by the type and concentration of polymer used. Incorporation of polymer in the Ca-P coatings reduced the coating elastic modulus bringing it close to that of magnesium and that of human bone. Nanoindentation test results revealed significantly decreased cracking tendency with the incorporation of polymer in the Ca-P coating. Apart from mechanical improvements, the protective composite layers had also enhanced the corrosion resistance of the substrate by a factor of 1000 which is sufficient for implant application. Cell proliferation studies indicated that the composite coatings induced better cell attachment compared with the purely inorganic Ca-P coating, confirming that the obtained composite materials could be promising candidates for surface protection of magnesium for implant application with the multiple functions of corrosion protection, interfacial stress reduction, and cell attachment/cell growth promotion. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1643-1657, 2016. © 2015 Wiley Periodicals, Inc.

  12. Manufacture of porous biodegradable polymer conduits by an extrusion process for guided tissue regeneration

    NASA Technical Reports Server (NTRS)

    Widmer, M. S.; Gupta, P. K.; Lu, L.; Meszlenyi, R. K.; Evans, G. R.; Brandt, K.; Savel, T.; Gurlek, A.; Patrick, C. W. Jr; Mikos, A. G.; hide

    1998-01-01

    We have fabricated porous, biodegradable tubular conduits for guided tissue regeneration using a combined solvent casting and extrusion technique. The biodegradable polymers used in this study were poly(DL-lactic-co-glycolic acid) (PLGA) and poly(L-lactic acid) (PLLA). A polymer/salt composite was first prepared by a solvent casting process. After drying, the composite was extruded to form a tubular construct. The salt particles in the construct were then leached out leaving a conduit with an open-pore structure. PLGA was studied as a model polymer to analyze the effects of salt weight fraction, salt particle size, and processing temperature on porosity and pore size of the extruded conduits. The porosity and pore size were found to increase with increasing salt weight fraction. Increasing the salt particle size increased the pore diameter but did not affect the porosity. High extrusion temperatures decreased the pore diameter without altering the porosity. Greater decrease in molecular weight was observed for conduits manufactured at higher temperatures. The mechanical properties of both PLGA and PLLA conduits were tested after degradation in vitro for up to 8 weeks. The modulus and failure strength of PLLA conduits were approximately 10 times higher than those of PLGA conduits. Failure strain was similar for both conduits. After degradation for 8 weeks, the molecular weights of the PLGA and PLLA conduits decreased to 38% and 43% of the initial values, respectively. However, both conduits maintained their shape and did not collapse. The PLGA also remained amorphous throughout the time course, while the crystallinity of PLLA increased from 5.2% to 11.5%. The potential of seeding the conduits with cells for transplantation or with biodegradable polymer microparticles for drug delivery was also tested with dyed microspheres. These porous tubular structures hold great promise for the regeneration of tissues which require tubular scaffolds such as peripheral nerve

  13. Gold-coated silicon nanowire-graphene core-shell composite film as a polymer binder-free anode for rechargeable lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Kim, Han-Jung; Lee, Sang Eon; Lee, Jihye; Jung, Joo-Yun; Lee, Eung-Sug; Choi, Jun-Hyuk; Jung, Jun-Ho; Oh, Minsub; Hyun, Seungmin; Choi, Dae-Geun

    2014-07-01

    We designed and fabricated a gold (Au)-coated silicon nanowires/graphene (Au-SiNWs/G) hybrid composite as a polymer binder-free anode for rechargeable lithium-ion batteries (LIBs). A large amount of SiNWs for LIB anode materials can be prepared by metal-assisted chemical etching (MaCE) process. The Au-SiNWs/G composite film on current collector was obtained by vacuum filtration using an anodic aluminum oxide (AAO) membrane and hot pressing method. Our experimental results show that the Au-SiNWs/G composite has a stable reversible capacity of about 1520 mA h/g which was maintained for 20 cycles. The Au-SiNWs/G composite anode showed much better cycling performance than SiNWs/polyvinylidene fluoride (PVDF)/Super-P, SiNWs/G composite, and pure SiNWs anodes. The improved electrochemical properties of the Au-SiNWs/G composite anode material is mainly ascribed to the composite's porous network structure.

  14. Superiority of Graphene over Polymer Coatings for Prevention of Microbially Induced Corrosion

    PubMed Central

    Krishnamurthy, Ajay; Gadhamshetty, Venkataramana; Mukherjee, Rahul; Natarajan, Bharath; Eksik, Osman; Ali Shojaee, S.; Lucca, Don A.; Ren, Wencai; Cheng, Hui-Ming; Koratkar, Nikhil

    2015-01-01

    Prevention of microbially induced corrosion (MIC) is of great significance in many environmental applications. Here, we report the use of an ultra-thin, graphene skin (Gr) as a superior anti-MIC coating over two commercial polymeric coatings, Parylene-C (PA) and Polyurethane (PU). We find that Nickel (Ni) dissolution in a corrosion cell with Gr-coated Ni is an order of magnitude lower than that of PA and PU coated electrodes. Electrochemical analysis reveals that the Gr coating offers ~10 and ~100 fold improvement in MIC resistance over PU and PA coatings respectively. This finding is remarkable considering that the Gr coating (1–2 nm) is ~25 and ~4000 times thinner than the PA (40–50 nm), and PU coatings (20–80 μm), respectively. Conventional polymer coatings are either non-conformal when deposited or degrade under the action of microbial processes, while the electro-chemically inert graphene coating is both resistant to microbial attack and is extremely conformal and defect-free. Finally, we provide a brief discussion regarding the effectiveness of as-grown vs. transferred graphene films for anti-MIC applications. While the as-grown graphene films are devoid of major defects, wet transfer of graphene is shown to introduce large scale defects that make it less suitable for the current application. PMID:26350049

  15. Superiority of Graphene over Polymer Coatings for Prevention of Microbially Induced Corrosion

    NASA Astrophysics Data System (ADS)

    Krishnamurthy, Ajay; Gadhamshetty, Venkataramana; Mukherjee, Rahul; Natarajan, Bharath; Eksik, Osman; Ali Shojaee, S.; Lucca, Don A.; Ren, Wencai; Cheng, Hui-Ming; Koratkar, Nikhil

    2015-09-01

    Prevention of microbially induced corrosion (MIC) is of great significance in many environmental applications. Here, we report the use of an ultra-thin, graphene skin (Gr) as a superior anti-MIC coating over two commercial polymeric coatings, Parylene-C (PA) and Polyurethane (PU). We find that Nickel (Ni) dissolution in a corrosion cell with Gr-coated Ni is an order of magnitude lower than that of PA and PU coated electrodes. Electrochemical analysis reveals that the Gr coating offers ~10 and ~100 fold improvement in MIC resistance over PU and PA coatings respectively. This finding is remarkable considering that the Gr coating (1-2 nm) is ~25 and ~4000 times thinner than the PA (40-50 nm), and PU coatings (20-80 μm), respectively. Conventional polymer coatings are either non-conformal when deposited or degrade under the action of microbial processes, while the electro-chemically inert graphene coating is both resistant to microbial attack and is extremely conformal and defect-free. Finally, we provide a brief discussion regarding the effectiveness of as-grown vs. transferred graphene films for anti-MIC applications. While the as-grown graphene films are devoid of major defects, wet transfer of graphene is shown to introduce large scale defects that make it less suitable for the current application.

  16. 'Breath figure' PLGA films as implant coatings for controlled drug release

    NASA Astrophysics Data System (ADS)

    Ponnusamy, Thiruselvam

    The breath figure method is a versatile and facile approach of generating ordered micro and nanoporous structures in polymeric materials. When a polymer solution (dissolved in a high vapor pressure organic solvent) is evaporated out in the presence of a moist air stream, the evaporative cooling effect causes the condensation and nucleation of water droplets onto the polymer solution surface. This leads to the formation of an imprinted porous structure upon removal of the residual solvent and water. The facile removal of the water droplet template leaving its structural imprint is a specifically appealing aspect of the breath figure film technology. The first part of the dissertation work involves the fabrication of drug loaded breath figure thin films and its utilization as a controlled drug release carrier and biomaterial scaffold. In a single fabrication step, single layer/multilayer porous thin films were designed and developed by combining the breath figure process and a modified spin or dip coating technique. Using biodegradable polymers such as poly (lactic-co-glycolic acid) (PLGA) and poly (ethylene glycol) (PEG), drug loaded films were fabricated onto FDA approved medical devices (the Glaucoma drainage device and the Surgical hernia mesh). The porosity of the films is in the range of 2-4 microm as characterized by scanning electron microscope. The drug coated medical implants were characterized for their surface and bulk morphology, the degradation rate of the film, drug release rate and cell cytotoxicity. The results suggest that the use of breath figure morphologies in biodegradable polymer films adds an additional level of control to drug release. In comparison to non-porous films, the breath figure films showed an increased degradation and enhanced drug release. Furthermore, the porous nature of the film was investigated as a biomaterial scaffold to construct three dimensional in vitro tissue model systems. The breath figure film with interconnected

  17. In vitro studying corrosion behavior of porous titanium coating in dynamic electrolyte.

    PubMed

    Chen, Xuedan; Fu, Qingshan; Jin, Yongzhong; Li, Mingtian; Yang, Ruisong; Cui, Xuejun; Gong, Min

    2017-01-01

    Porous titanium (PT) is considered as a promising biomaterials for orthopedic implants. Besides biocompatibility and mechanical properties, corrosion resistance in physiological environment is the other important factor affecting the long stability of an implant. In order to investigate the corrosion behavior of porous titanium implants in a dynamic physiological environment, a dynamic circle system was designed in this study. Then a titanium-based implant with PT coating was fabricated by plasma spraying. The corrosion resistance of PT samples in flowing 0.9% NaCl solution was evaluated by electrochemical measurements. Commercial pure solid titanium (ST) disc was used as a control. The studies of potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) show that the pores in the PT play a negetive part in corrosion resistance and the flowing electrolyte can increase the corrosive rate of all titanium samples. The results suggest that pore design of titanium implants should pay attention to the effect of dynamic process of a physiological environment on the corrosion behavior of implants. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Controlling the degradation kinetics of porous iron by poly(lactic-co-glycolic acid) infiltration for use as temporary medical implants

    PubMed Central

    Yusop, Abdul Hakim Md; Daud, Nurizzati Mohd; Nur, Hadi; Kadir, Mohammed Rafiq Abdul; Hermawan, Hendra

    2015-01-01

    Iron and its alloy have been proposed as biodegradable metals for temporary medical implants. However, the formation of iron oxide and iron phosphate on their surface slows down their degradation kinetics in both in vitro and in vivo scenarios. This work presents new approach to tailor degradation behavior of iron by incorporating biodegradable polymers into the metal. Porous pure iron (PPI) was vacuum infiltrated by poly(lactic-co-glycolic acid) (PLGA) to form fully dense PLGA-infiltrated porous iron (PIPI) and dip coated into the PLGA to form partially dense PLGA-coated porous iron (PCPI). Results showed that compressive strength and toughness of the PIPI and PCPI were higher compared to PPI. A strong interfacial interaction was developed between the PLGA layer and the iron surface. Degradation rate of PIPI and PCPI was higher than that of PPI due to the effect of PLGA hydrolysis. The fast degradation of PIPI did not affect the viability of human fibroblast cells. Finally, this work discusses a degradation mechanism for PIPI and the effect of PLGA incorporation in accelerating the degradation of iron. PMID:26057073

  19. Insulation Materials Comprising Fibers Having a Partially Cured Polymer Coating Thereon, Articles Including Such Insulation Materials, and Methods of Forming Such Materials and Articles

    NASA Technical Reports Server (NTRS)

    Morgan, Richard E. (Inventor); Meeks, Craig L. (Inventor)

    2017-01-01

    Insulation materials have a coating of a partially cured polymer on a plurality of fibers, and the plurality of coated fibers in a cross-linked polymeric matrix. Insulation may be formed by applying a preceramic polymer to a plurality of fibers, heating the preceramic polymer to form a partially cured polymer over at least portions of the plurality of fibers, disposing the plurality of fibers in a polymeric material, and curing the polymeric material. A rocket motor may be formed by disposing a plurality of coated fibers in an insulation precursor, curing the insulation precursor to form an insulation material without sintering the partially cured polymer, and providing an energetic material over the polymeric material. An article includes an insulation material over at least one surface.

  20. Stabilization of battery electrodes using polymer coatings

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wessells, Colin Deane; Huggins, Robert Alan

    An electrochemical device (e.g., a battery (cell)) including: an aqueous electrolyte and one or two electrodes (e.g., an anode and/or a cathode), one or both of which is a Prussian Blue analogue material of the general chemical formula A.sub.xP[R(CN).sub.6-jL.sub.j].sub.z.nH.sub.2O, where: A is a cation; P is a metal cation; R is a transition metal cation; L is a ligand that may be substituted in the place of a CN.sup.- ligand; 0.ltoreq.x.ltoreq.2; 0.ltoreq.z.ltoreq.1; and 0.ltoreq.n.ltoreq.5, the electrode including a polymer coating to reduce capacity loss.

  1. A Study on the Deposition of Al2O3 Coatings on Polymer Substrates by a Plasma Spray/Micro-Arc Oxidation Two-Step Method

    NASA Astrophysics Data System (ADS)

    Sun, Guanhong; He, Xiaodong; Jiang, Jiuxing; Sun, Yue; Zhong, Yesheng

    2013-02-01

    To increase the wear resistance of polymer matrix composites, alumina coatings were deposited on polymer substrates by a two-step method combining plasma spraying and micro-arc oxidation. The microstructures and phase compositions of the processed coatings were investigated for different treatment times. Uniformly distributed pores were found in addition to the presence of various coral-like structures and floccules on the surface of the coatings. The presence of α-Al2O3 and γ-Al2O3 phases was identified by XRD. The distribution of alumina was analyzed by EDS and is discussed. The maximum bond strength of the coatings was found to be 5.89 MPa. There was little thermal damage in the polymer substrates after the coatings were produced.

  2. Effects of RTV coating on the electrical performance of polymer insulator under lightning impulse voltage condition.

    PubMed

    Jamaludin, Farah Adilah; Ab-Kadir, Mohd Zainal Abidin; Izadi, Mahdi; Azis, Norhafiz; Jasni, Jasronita; Abd-Rahman, Muhammad Syahmi

    2017-01-01

    Located near the equator, Malaysia is a country with one of the highest lightning densities in the world. Lightning contributes to 70% of the power outages in Malaysia and affects power equipment, automated network systems, causes data losses and monetary losses in the nation. Therefore, consideration of insulator evaluation under lightning impulses can be crucial to evaluate and attempt to overcome this issue. This paper presents a new approach to increase the electrical performance of polymer insulators using a Room Temperature Vulcanisation (RTV) coating. The evaluation involves three different settings of polymer insulator, namely uncoated, RTV type 1, and RTV type 2 upper surface coatings. All the insulators were tested under three different conditions as dry, clean wet and salty under different impulse polarities using the even-rising test method. The voltage breakdown for each test was recorded. From the experiment, it was found that the effectiveness of the RTV coating application became apparent when tested under salty or polluted conditions. It increased the voltage withstand capabilities of the polymer insulator up to 50% from the basic uncoated insulator. Under dry and clean conditions, the RTV coating provided just a slight increase of the breakdown voltage. The increase in voltage breakdown capability decreased the probability of surface discharge and dry band arcing that could cause degradation of the polymeric material housing. The RTV type 1 coating was found to be more effective when performing under a lightning impulse. The findings might help the utility companies improve the performance of their insulators in order to increase power system reliability.

  3. Effects of RTV coating on the electrical performance of polymer insulator under lightning impulse voltage condition

    PubMed Central

    Jamaludin, Farah Adilah; Ab-Kadir, Mohd Zainal Abidin; Izadi, Mahdi; Azis, Norhafiz; Jasni, Jasronita; Abd-Rahman, Muhammad Syahmi

    2017-01-01

    Located near the equator, Malaysia is a country with one of the highest lightning densities in the world. Lightning contributes to 70% of the power outages in Malaysia and affects power equipment, automated network systems, causes data losses and monetary losses in the nation. Therefore, consideration of insulator evaluation under lightning impulses can be crucial to evaluate and attempt to overcome this issue. This paper presents a new approach to increase the electrical performance of polymer insulators using a Room Temperature Vulcanisation (RTV) coating. The evaluation involves three different settings of polymer insulator, namely uncoated, RTV type 1, and RTV type 2 upper surface coatings. All the insulators were tested under three different conditions as dry, clean wet and salty under different impulse polarities using the even-rising test method. The voltage breakdown for each test was recorded. From the experiment, it was found that the effectiveness of the RTV coating application became apparent when tested under salty or polluted conditions. It increased the voltage withstand capabilities of the polymer insulator up to 50% from the basic uncoated insulator. Under dry and clean conditions, the RTV coating provided just a slight increase of the breakdown voltage. The increase in voltage breakdown capability decreased the probability of surface discharge and dry band arcing that could cause degradation of the polymeric material housing. The RTV type 1 coating was found to be more effective when performing under a lightning impulse. The findings might help the utility companies improve the performance of their insulators in order to increase power system reliability. PMID:29136025

  4. Fabrication of a multifunctional nano-in-micro drug delivery platform by microfluidic templated encapsulation of porous silicon in polymer matrix.

    PubMed

    Zhang, Hongbo; Liu, Dongfei; Shahbazi, Mohammad-Ali; Mäkilä, Ermei; Herranz-Blanco, Bárbara; Salonen, Jarno; Hirvonen, Jouni; Santos, Hélder A

    2014-07-09

    A multifunctional nano-in-micro drug delivery platform is developed by conjugating the porous silicon nanoparticles with mucoadhesive polymers and subsequent encapsulation into a pH-responsive polymer using microfluidics. The multistage platform shows monodisperse size distribution and pH-responsive payload release, and the released nanoparticles are mucoadhesive. Moreover, this platform is capable of simultaneously loading and releasing multidrugs with distinct properties. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Electrophoretically active sol-gel processes to backfill, seal, and/or densify porous, flawed, and/or cracked coatings on electrically conductive material

    DOEpatents

    Panitz, J.K.; Reed, S.T.; Ashley, C.S.; Neiser, R.A.; Moffatt, W.C.

    1999-07-20

    Electrophoretically active sol-gel processes to fill, seal, and/or density porous, flawed, and/or cracked coatings on electrically conductive substrates. Such coatings may be dielectrics, ceramics, or semiconductors and, by the present invention, may have deposited onto and into them sol-gel ceramic precursor compounds which are subsequently converted to sol-gel ceramics to yield composite materials with various tailored properties. 6 figs.

  6. A modified dynamical model of drying process of polymer blend solution coated on a flat substrate

    NASA Astrophysics Data System (ADS)

    Kagami, Hiroyuki

    2008-05-01

    We have proposed and modified a model of drying process of polymer solution coated on a flat substrate for flat polymer film fabrication. And for example numerical simulation of the model reproduces a typical thickness profile of the polymer film formed after drying. Then we have clarified dependence of distribution of polymer molecules on a flat substrate on a various parameters based on analysis of numerical simulations. Then we drove nonlinear equations of drying process from the dynamical model and the fruits were reported. The subject of above studies was limited to solution having one kind of solute though the model could essentially deal with solution having some kinds of solutes. But nowadays discussion of drying process of a solution having some kinds of solutes is needed because drying process of solution having some kinds of solutes appears in many industrial scenes. Polymer blend solution is one instance. And typical resist consists of a few kinds of polymers. Then we introduced a dynamical model of drying process of polymer blend solution coated on a flat substrate and results of numerical simulations of the dynamical model. But above model was the simplest one. In this study, we modify above dynamical model of drying process of polymer blend solution adding effects that some parameters change with time as functions of some variables to it. Then we consider essence of drying process of polymer blend solution through comparison between results of numerical simulations of the modified model and those of the former model.

  7. Evaluating the in vivo glial response to miniaturized parylene cortical probes coated with an ultra-fast degrading polymer to aid insertion.

    PubMed

    Lo, Meng-Chen; Wang, Shuwu; Singh, Sagar; Damodaran, Vinod B; Ahmed, Ijaz; Coffey, Kevin; Barker, David; Saste, Kshitij; Kals, Karanvir; Kaplan, Hilton M; Kohn, Joachim; Shreiber, David I; Zahn, Jeffrey D

    2018-06-01

    Despite the feasibility of short-term neural recordings using implantable microelectrodes, attaining reliable, chronic recordings remains a challenge. Most neural recording devices suffer from a long-term tissue response, including gliosis, at the device-tissue interface. It was hypothesized that smaller, more flexible intracortical probes would limit gliosis by providing a better mechanical match with surrounding tissue. This paper describes the in vivo evaluation of flexible parylene microprobes designed to improve the interface with the adjacent neural tissue to limit gliosis and thereby allow for improved recording longevity. The probes were coated with an ultrafast degrading tyrosine-derived polycarbonate (E5005(2K)) polymer that provides temporary mechanical support for device implantation, yet degrades within 2 h post-implantation. A parametric study of probes of varying dimensions and polymer coating thicknesses were implanted in rat brains. The glial tissue response and neuronal loss were assessed from 72 h to 24 weeks post-implantation via immunohistochemistry. Experimental results suggest that both probe and polymer coating sizes affect the extent of gliosis. When an appropriate sized coating dimension (100 µm  ×  100 µm) and small probe (30 µm  ×  5 µm) was implanted, a minimal post-implantation glial response was observed. No discernible gliosis was detected when compared to tissue where a sham control consisting of a solid degradable polymer shuttle of the same dimensions was inserted. A larger polymer coating (200 µm  ×  200 µm) device induced a more severe glial response at later time points, suggesting that the initial insertion trauma can affect gliosis even when the polymer shuttle degrades rapidly. A larger degree of gliosis was also observed when comparing a larger sized probe (80 µm  ×  5 µm) to a smaller probe (30 µm  ×  5 µm) using the same polymer coating size (100 µm

  8. Adjustment of surface chemical and physical properties with functionalized polymers to control cell adhesion

    NASA Astrophysics Data System (ADS)

    Zhou, Zhaoli

    Cell-surface interaction is crucial in many cellular functions such as movement, growth, differentiation, proliferation and survival. In the present work, we have developed several strategies to design and prepare synthetic polymeric materials with selected cues to control cell attachment. To promote neuronal cell adhesion on the surfaces, biocompatible, non-adhesive PEG-based materials were modified with neurotransmitter acetylcholine functionalities to produce hydrogels with a range of porous structures, swollen states, and mechanical strengths. Mice hippocampal cells cultured on the hydrogels showed differences in number, length of processes and exhibited different survival rates, thereby highlighting the importance of chemical composition and structure in biomaterials. Similar strategies were used to prepare polymer brushes to assess how topographical cues influence neuronal cell behaviors. The brushes were prepared using the "grown from" method through surface-initiated atom transfer radical polymerization (SI-ATRP) reactions and further patterned via UV photolithography. Protein absorption tests and hippocampal neuronal cell culture of the brush patterns showed that both protein and neuronal cells can adhere to the patterns and therefore can be guided by the patterns at certain length scales. We also prepared functional polymers to discourage attachment of undesirable cells on the surfaces. For example, we synthesized PEG-perfluorinated alkyl amphiphilic surfactants to modify polystyrene-block-poly(ethylene-ran-butylene)- block-polyisoprene (SEBI or K3) triblock copolymers for marine antifouling/fouling release surface coatings. Initial results showed that the polymer coated surfaces can facilitate removal of Ulva sporelings on the surfaces. In addition, we prepared both bioactive and dual functional biopassive/bioactive antimicrobial coatings based on SEBI polymers. Incubating the polymer coated surfaces with gram-positive bacteria (S. aureus), gram

  9. Porous Silicon as Antireflecting Layer

    NASA Astrophysics Data System (ADS)

    Kosoglu, Gulsen; Yumak, Mehmet; Okmen, Selim; Ozatay, Ozhan; Skarlatos, Yani; Garcia, Carlos

    2013-03-01

    The main aim in photovoltaic industry is to produce efficient and energy competitive solar cell modules at low cost. Efficient AntiReflection Coatings (ARC) improve light collection and thereby increase the current output of solar cells. Broadband ARCs are desirable for efficient application over the entire solar spectrum and porous silicon layers as antireflective coating layers provide successful light collection. In the study the most critical physical parameters of porous silicon are examined, homogeneous and uniform porous layers are produced. The photoluminescence spectrum and optical parameters of porous layers have been investigated, and we are now in the process of improving the efficiency of the device by modulating the structure of the porous silicon layers and studying its photovoltaic characteristics. We would like to thank to Mr. Aziz U. Caliskan and his group for their valuable support from TUBITAK YITAL. This Project is supported by Bogazici University Research Funding: 5782, TUBITAK Grant : 209T099, and Bogazici University Infrared Funding: 6121.

  10. The effect of operative fit and hydroxyapatite coating on the mechanical and biological response to porous implants.

    PubMed

    Dalton, J E; Cook, S D; Thomas, K A; Kay, J F

    1995-01-01

    Femoral intramedullary implants were constructed by threading 4.0-millimeter-thick disks with a titanium-alloy (Ti-6Al-4V) porous bead coating onto a two-millimeter-diameter threaded rod. Each porous-coated disk, which was 6.0, 8.0, 9.0, or 10.0 millimeters in diameter, was separated by a two-millimeter-thick acrylic disk with a diameter of ten millimeters. Implants with and without a hydroxyapatite coating of twenty-five micrometers were inserted into fifteen skeletally mature adult mongrel dogs. The femoral canal was sequentially reamed bilaterally to a ten-millimeter diameter, resulting in uniform initial implant-bone interface gaps of 0.0, 0.5, 1.0, and 2.0 millimeters. Each animal received paired hydroxyapatite-coated and uncoated implants. Three animals each were killed at four, eight, twelve, twenty-four, and fifty-two weeks after the implantation. The harvested femora were sectioned through the acrylic spacers, transverse to the long axis, to produce individual push-out test specimens for mechanical testing. Characteristics of interface attachment were determined with test fixtures that supported the surrounding bone to within 150 micrometers of the interface. Histological sections were prepared, and the amount of bone within the porous structure and the amount of the original gap that was filled with new bone were quantified with a computerized video image-analysis system. Mechanical attachment strength and bone ingrowth were found to increase with the time after implantation and with a decrease in the size of the gap. Placement of the implant in proximal (cancellous) compared with distal (cortical) locations had no significant effect on the strength of attachment, bone ingrowth, or gap-filling. However, implants with a large initial gap (1.0 or 2.0 millimeters) demonstrated greater attachment strength in cancellous bone than in cortical bone. With a few exceptions, hydroxyapatite-coated implants with an initial gap of 1.0 millimeter or less demonstrated

  11. Preparation and Thermal Characterization of Annealed Gold Coated Porous Silicon

    PubMed Central

    Behzad, Kasra; Mat Yunus, Wan Mahmood; Talib, Zainal Abidin; Zakaria, Azmi; Bahrami, Afarin

    2012-01-01

    Porous silicon (PSi) layers were formed on a p-type Si wafer. Six samples were anodised electrically with a 30 mA/cm2 fixed current density for different etching times. The samples were coated with a 50–60 nm gold layer and annealed at different temperatures under Ar flow. The morphology of the layers, before and after annealing, formed by this method was investigated by scanning electron microscopy (SEM). Photoacoustic spectroscopy (PAS) measurements were carried out to measure the thermal diffusivity (TD) of the PSi and Au/PSi samples. For the Au/PSi samples, the thermal diffusivity was measured before and after annealing to study the effect of annealing. Also to study the aging effect, a comparison was made between freshly annealed samples and samples 30 days after annealing. PMID:28817037

  12. Preparation and Thermal Characterization of Annealed Gold Coated Porous Silicon.

    PubMed

    Behzad, Kasra; Mat Yunus, Wan Mahmood; Talib, Zainal Abidin; Zakaria, Azmi; Bahrami, Afarin

    2012-01-16

    Porous silicon (PSi) layers were formed on a p-type Si wafer. Six samples were anodised electrically with a 30 mA/cm² fixed current density for different etching times. The samples were coated with a 50-60 nm gold layer and annealed at different temperatures under Ar flow. The morphology of the layers, before and after annealing, formed by this method was investigated by scanning electron microscopy (SEM). Photoacoustic spectroscopy (PAS) measurements were carried out to measure the thermal diffusivity (TD) of the PSi and Au/PSi samples. For the Au/PSi samples, the thermal diffusivity was measured before and after annealing to study the effect of annealing. Also to study the aging effect, a comparison was made between freshly annealed samples and samples 30 days after annealing.

  13. Polymer coating behavior of Rayleigh-SAW resonators with gold electrode structure for gas sensor applications.

    PubMed

    Avramov, Ivan D; Länge, Kerstin; Rupp, Swen; Rapp, Bastian; Rapp, Michael

    2007-01-01

    Results from systematic polymer coating experiments on surface acoustic wave (SAW) resonators and coupled resonator filters (CRF) on ST-cut quartz with a corrosion-proof electrode structure entirely made of gold (Au) are presented and compared with data from similar SAW devices using aluminium (Al) electrodes. The recently developed Au devices are intended to replace their earlier Al counterparts in sensor systems operating in highly reactive chemical gas environments. Solid parylene C and soft poly[chlorotrifluoroethylene-co-vinylidene fluoride] (PCFV) polymer films are deposited under identical conditions onto the surface of Al and Au devices. The electrical performance of the Parylene C coated devices is monitored online during film deposition. The PCVF coated devices are evaluated after film deposition. The experimental data show that the Au devices can stand up to 40% thicker solid films for the same amount of loss increase than the Al devices and retain better resonance and phase characteristics. The frequency sensitivities of Au and Al devices to parylene C deposition are nearly identical. After coating with soft PCFV sensing film, the Au devices provide up to two times higher gas sensitivity when probed with cooling agent, octane, or tetrachloroethylene.

  14. Infusible silazane polymer and process for producing same. [protective coatings

    NASA Technical Reports Server (NTRS)

    Burks, R. E., Jr.; Lacey, R. E.; Christy, C. L., Jr. (Inventor)

    1967-01-01

    Coatings of high thermal and chemical stability for application to metal, glass, ceramics, and other surfaces are formed by reacting diphenyldichlorosilane in the presence of triethylamine with a nitrogen base selected from the group consisting of ammonia and methylamine. The pl polymeric, noncrystalline reaction product is heated in a reaction zone open to the atmosphere at a temperature ranging from approximately 250 C to 450 C until the infusible polymer is formed.

  15. Antibacterial chitosan coating on nano-hydroxyapatite/polyamide66 porous bone scaffold for drug delivery.

    PubMed

    Huang, Di; Zuo, Yi; Zou, Qin; Zhang, Li; Li, Jidong; Cheng, Lin; Shen, Juan; Li, Yubao

    2011-01-01

    This study describes a new drug-loaded coating scaffold applied in infection therapy during bone regeneration. Chitosan (CS) containing antibacterial berberine was coated on a nano-hydroxyapatite/polyamide66 (n-HA/PA66) scaffold to realize bone regeneration together with antimicrobial properties. The porous scaffold was fabricated using the phase-inversion method with a porosity of about 84% and macropore size of 400-600 μm. The morphology, mechanical properties and drug-release behavior were investigated at different ratios of chitosan to berberine. The results show that the elastic modulus and compressive strength of the coated scaffolds were improved to 35.4 MPa and 1.7 MPa, respectively, about 7 times and 3 times higher than the uncoated scaffolds. After a burst release of berberine within the first 3 h in PBS solution, a continuous berberine release can last 150 h, which is highly dependent on the coating concentration and suitable for antibacterial requirement of orthopaedic surgery. The bactericidal test confirms a strong antibiotic effect of the delivery system and the minimum inhibitory concentration of the drug is 0.02 mg/ml. Moreover, in vitro biological evaluation demonstrates that the coating scaffolds act as a good matrix for MG63 adhesion, crawl, growth and proliferation, suggesting that the antibacterial delivery system has no cytotoxicity. We expect the drug-delivery system to have a potential application in bone regeneration or defect repair.

  16. Novel generation of liquid crystalline photo-actuators based on stretched porous polyethylene films.

    PubMed

    Ryabchun, Alexander; Bobrovsky, Alexey; Stumpe, Joachim; Shibaev, Valery

    2012-06-14

    The preparation of photo-actuators based on stretched porous polyethylene and an azobenzene-containing liquid crystalline polymer network is reported for the first time. It is revealed that this kind of photo-actuator possesses the following advantages: the lack of a need for using aligning coatings and cells preparation, high deformation of the actuator and its complete reversibility, good mechanical properties, and relatively low cost of fabrication. In addition some kinetic and thermodynamic features of the bending and unbending processes have been studied. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Towards seamlessly-integrated textile electronics: methods to coat fabrics and fibers with conducting polymers for electronic applications.

    PubMed

    Allison, Linden; Hoxie, Steven; Andrew, Trisha L

    2017-06-29

    Traditional textile materials can be transformed into functional electronic components upon being dyed or coated with films of intrinsically conducting polymers, such as poly(aniline), poly(pyrrole) and poly(3,4-ethylenedioxythiophene). A variety of textile electronic devices are built from the conductive fibers and fabrics thus obtained, including: physiochemical sensors, thermoelectric fibers/fabrics, heated garments, artificial muscles and textile supercapacitors. In all these cases, electrical performance and device ruggedness is determined by the morphology of the conducting polymer active layer on the fiber or fabric substrate. Tremendous variation in active layer morphology can be observed with different coating or dyeing conditions. Here, we summarize various methods used to create fiber- and fabric-based devices and highlight the influence of the coating method on active layer morphology and device stability.

  18. Highly effective ammonia removal in a series of Brønsted acidic porous polymers: investigation of chemical and structural variations

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Barin, Gokhan; Peterson, Gregory W.; Crocellà, Valentina

    Efficient removal of ammonia from air is demonstrated in a series of Brønsted acidic porous polymers under dry and humid conditions. The impact of acidic group strength and their spatial distribution on the ammonia uptake is investigated systematically.

  19. Highly effective ammonia removal in a series of Brønsted acidic porous polymers: investigation of chemical and structural variations

    DOE PAGES

    Barin, Gokhan; Peterson, Gregory W.; Crocella, Valentina; ...

    2017-04-27

    Efficient removal of ammonia from air is demonstrated in a series of Brønsted acidic porous polymers under dry and humid conditions. The impact of acidic group strength and their spatial distribution on the ammonia uptake is investigated systematically.

  20. Initiated Chemical Vapor Deposition (iCVD) of Highly Cross-Linked Polymer Films for Advanced Lithium-Ion Battery Separators.

    PubMed

    Yoo, Youngmin; Kim, Byung Gon; Pak, Kwanyong; Han, Sung Jae; Song, Heon-Sik; Choi, Jang Wook; Im, Sung Gap

    2015-08-26

    We report an initiated chemical vapor deposition (iCVD) process to coat polyethylene (PE) separators in Li-ion batteries with a highly cross-linked, mechanically strong polymer, namely, polyhexavinyldisiloxane (pHVDS). The highly cross-linked but ultrathin pHVDS films can only be obtained by a vapor-phase process, because the pHVDS is insoluble in most solvents and thus infeasible with conventional solution-based methods. Moreover, even after the pHVDS coating, the initial porous structure of the separator is well preserved owing to the conformal vapor-phase deposition. The coating thickness is delicately controlled by deposition time to the level that the pore size decreases to below 7% compared to the original dimension. The pHVDS-coated PE shows substantially improved thermal stability and electrolyte wettability. After incubation at 140 °C for 30 min, the pHVDS-coated PE causes only a 12% areal shrinkage (versus 90% of the pristine separator). The superior wettability results in increased electrolyte uptake and ionic conductivity, leading to significantly improved rate performance. The current approach is applicable to a wide range of porous polymeric separators that suffer from thermal shrinkage and poor electrolyte wetting.

  1. Hydroxyapatite in total hip arthroplasty. Our experience with a plasma spray porous titanium alloy/hydroxyapatite double-coated cementless stem.

    PubMed

    Castellini, Iacopo; Andreani, Lorenzo; Parchi, Paolo Domenico; Bonicoli, Enrico; Piolanti, Nicola; Risoli, Francesca; Lisanti, Michele

    2016-01-01

    Total hip arthroplasty could fail due to many factors and one of the most common is the aseptic loosening. In order to achieve an effective osseointegration and reduce risk of lossening, the use of cemented implant, contact porous bearing surface and organic coating were developed. Aim of this study was to evaluate clinical and radiological mid-term outcomes of a porous titanium alloy/hydroxyapatite double coating manufactured cementless femoral stem applied with "plasma spray" technique and to demonstrate the possibility to use this stem in different types of femoral canals. Between January 2008 and December 2012, 240 consecutive primary total hip arthroplasties (THAs) were performed using a porous titanium alloy/hydroxyapatite double coating manufactured cementless femoral stem. 182 patients were examined: 136 were females (74.7%) and 46 males (25.2%); average age was 72 years old (ranging from 26 to 92 years old). For each patient, Harris Hip Scores (HHS) and Womac Scores were collected. All X-ray images were analyzed in order to demonstrate stem survival rate and subsidence. Harris Hip Score was good or excellent in 85% of the cases (average 90%) and mean WOMAC score was 97.5 (ranging from 73.4 to 100). No cases of early/late infection or periprosthetic fracture were noticed, with an excellent implant survival rate (100%) in a mean period of 40 months (ranging from 24 and 84 months). 5 cases presented acute implant dislocation, 2 due to wrong cup positioning in a dysplastic acetabulum and 3 after ground level fall. Dorr classification of femoral geometry was uses and the results were: 51 type A bone, 53 type B bone and 78 type C bone. Stem subsidence over 2 mm was considered as a risk factor of future implant loosening and was evidenced in 3 female patients with type C of Dorr classification. No radiolucencies signs around the proximally coated portion of stem or proximal reabsorption were visible during the radiographic follow-up. Concerning the use of porous

  2. Simple and Rapid Immobilization of Coating Polymers on Poly(dimethyl siloxane)-glass Hybrid Microchips by a Vacuum-drying Method.

    PubMed

    Kitagawa, Fumihiko; Nakagawara, Syo; Nukatsuka, Isoshi; Hori, Yusuke; Sueyoshi, Kenji; Otsuka, Koji

    2015-01-01

    A simple and rapid vacuum-drying modification method was applied to several neutral and charged polymers to obtain coating layers for controlling electroosmotic flow (EOF) and suppressing sample adsorption on poly(dimethyl siloxane) (PDMS)-glass hybrid microchips. In the vacuum-dried poly(vinylpyrrolidone) coating, the electroosmotic mobility (μeo) was suppressed from +2.1 to +0.88 × 10(-4) cm(2)/V·s, and the relative standard deviation (RSD) of μeo was improved from 10.2 to 2.5% relative to the bare microchannel. Among several neutral polymers, poly(vinylalcohol) (PVA) and poly(dimethylacrylamide) coatings gave more suppressed and repeatable EOF with RSDs of less than 2.3%. The vacuum-drying method was also applicable to polyanions and polycations to provide accelerated and inversed EOF, respectively, with acceptable RSDs of less than 4.9%. In the microchip electrophoresis (MCE) analysis of bovine serum albumin (BSA) in the vacuum-dried and thermally-treated PVA coating channel, an almost symmetric peak of BSA was obtained, while in the native microchannel a significantly skewed peak was observed. The results demonstrated that the vacuum-dried polymer coatings were effective to control the EOF, and reduced the surface adsorption of proteins in MCE.

  3. Coated particles for lithium battery cathodes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Singh, Mohit; Eitouni, Hany Basam; Pratt, Russell Clayton

    Particles of cathodic materials are coated with polymer to prevent direct contact between the particles and the surrounding electrolyte. The polymers are held in place either by a) growing the polymers from initiators covalently bound to the particle, b) attachment of the already-formed polymers by covalently linking to functional groups attached to the particle, or c) electrostatic interactions resulting from incorporation of cationic or anionic groups in the polymer chain. Carbon or ceramic coatings may first be formed on the surfaces of the particles before the particles are coated with polymer. The polymer coating is both electronically and ionically conductive.

  4. Poly(dopamine) coating to biodegradable polymers for bone tissue engineering.

    PubMed

    Tsai, Wei-Bor; Chen, Wen-Tung; Chien, Hsiu-Wen; Kuo, Wei-Hsuan; Wang, Meng-Jiy

    2014-02-01

    In this study, a technique based on poly(dopamine) deposition to promote cell adhesion was investigated for the application in bone tissue engineering. The adhesion and proliferation of rat osteoblasts were evaluated on poly(dopamine)-coated biodegradable polymer films, such as polycaprolactone, poly(l-lactide) and poly(lactic-co-glycolic acid), which are commonly used biodegradable polymers in tissue engineering. Cell adhesion was significantly increased to a plateau by merely 15 s of dopamine incubation, 2.2-4.0-folds of increase compared to the corresponding untreated substrates. Cell proliferation was also greatly enhanced by poly(dopamine) deposition, indicated by shortened cell doubling time. Mineralization was also increased on the poly(dopamine)-deposited surfaces. The potential of poly(dopamine) deposition in bone tissue engineering is demonstrated in this study.

  5. Zeolitic imidazolate framework-8-derived N-doped porous carbon coated olive-shaped FeOx nanoparticles for lithium storage

    NASA Astrophysics Data System (ADS)

    Gan, Qingmeng; Zhao, Kuangmin; He, Zhen; Liu, Suqin; Li, Aikui

    2018-04-01

    We propose a new strategy to uniformly coat zeolitic imidazolate framework-8 (ZIF-8) on iron oxides containing no Zn to obtain an α-Fe2O3@ZIF-8 composite. After carbonization, the α-Fe2O3@ZIF-8 transforms into iron oxides@N-doped porous carbon (FeOx@NC). The uniform N-doped porous carbon layer gives rise to a superior electrical conductivity, highly-increased specific BET surface area (179.2 m2 g-1), and abundant mesopores for the FeOx@NC composite. When served as the LIB anode, the FeOx@NC shows a high reversible capacity (of 1064 mA h g-1 at 200 mA g-1), excellent rate performance (of 198.1 mA h g-1 at 10000 mA g-1) as well as brilliant long-term cyclability (with a capacity retention of 93.3% after 800 cycles), which are much better than those of the FeOx@C and pristine FeOx anodes. Specifically, the Li-ion intercalation pseudocapacitive behavior of the FeOx@NC anode is improved by this N-doped porous carbon coating, which is beneficial for rapid Li-ion insertion/extraction processes. The excellent electrochemical performance of FeOx@NC should be ascribed to the increased electrolyte penetration areas, improved electrical conductivity, boosted lithium storage kinetics, and shortened Li-ion transport length.

  6. Nitric oxide releasing plasma polymer coating with bacteriostatic properties and no cytotoxic side effects.

    PubMed

    Michl, Thomas D; Coad, Bryan R; Doran, Michael; Osiecki, Michael; Kafshgari, Morteza Hasanzadeh; Voelcker, Nicolas H; Hüsler, Amanda; Vasilev, Krasimir; Griesser, Hans J

    2015-04-25

    We report a stable plasma polymer coating, using isopentyl nitrite as a volatile precursor, which releases nitric oxide at bacteriostatic concentrations when contacted with water, inhibiting bacterial growth without cytotoxic side effects to human mesenchymal stem/stromal cells.

  7. Enteric polymers as acidifiers for the pH-independent sustained delivery of a weakly basic drug salt from coated pellets.

    PubMed

    Körber, Martin; Ciper, Mesut; Hoffart, Valerie; Pearnchob, Nantharat; Walther, Mathias; Macrae, Ross J; Bodmeier, Roland

    2011-08-01

    Weakly basic drugs and their salts exhibit a decrease in aqueous solubility at higher pH, which can result in pH-dependent or even incomplete release of these drugs from extended release formulations. The objective of this study was to evaluate strategies to set-off the very strong pH-dependent solubility (solubility: 80 mg/ml at pH 2 and 0.02 mg/ml at pH 7.5, factor 4000) of a mesylate salt of weakly basic model drug (pK(a) 6.5), in order to obtain pH-independent extended drug release. Three approaches for pH-independent release were investigated: (1) organic acid addition in the core, (2) enteric polymer addition to the extended release coating and (3) an enteric polymer subcoating below the extended release coating. The layering of aspartic acid onto drug cores as well as the coating of drug cores with an ethylcellulose/Eudragit L (enteric polymer) blend were not effective to avoid the formation of the free base at pH 7.5 and thus failed to significantly improve the completeness of the release compared to standard ethylcellulose/hydroxypropyl cellulose (EC/HPC)-coated drug pellets. Interestingly, the incorporation of an enteric polymer layer underneath the EC/HPC coating decreased the free base formation at pH 7.5 and thus resulted in a more complete release of up to 90% of the drug loading over 18 h. The release enhancing effect was attributed to an extended acidification through the enteric polymer layer. Flexible release patterns with approximately pH-independent characteristics were successfully achieved. Copyright © 2011 Elsevier B.V. All rights reserved.

  8. Processing and properties of ceramic matrix-polymer composites for dental applications

    NASA Astrophysics Data System (ADS)

    Huang, Hsuan Yao

    The basic composite structure of natural hard tissue was used to guide the design and processing of dental restorative materials. The design incorporates the methodology of using inorganic minerals as the main structural phase reinforced with a more ductile but tougher organic phase. Ceramic-polymer composites were prepared by slip casting a porous ceramic structure, heating and chemical treating the porous preform, infiltrating with monomer and then curing. The three factors that determined the mechanical properties of alumina-polymer composites were the type of polymer used, the method of silane treatments, and the type of bond between particles in the porous preforms. Without the use of silane coupling agents, the composites were measured to have a lower strength. The composite with a more "flexible" porous alumina network had a greater ability to plastically dissipate the energy of propagating cracks. However, the aggressive nature of the alumina particles on opposing enamel requires that these alumina-polymer composites have a wear compatible coating for practical application. A route to dense bioactive apatite wollastonite glass ceramics (AWGC)-polymer composites was developed. The problems associated with glass dissolution into the aqueous medium for slip casting were overcome with the use of silane. The role of heating rate and development of ceramic compact microstructure on composite properties was explored. In general, if isothermal heating was not applied, decreasing heating rate increased glass crystallinity and particle-particle fusion, but decreased pore volume. Also composite strength and fracture toughness decreased while modulus and hardness increased with decreasing heating rate. If isothermal heating was applied, glass crystallinity, pore content, and composite mechanical properties showed relatively little change regardless of the initial heating rate. The potential of AWGC-polymer composites for dental and implant applications was explored

  9. Coated foams, preparation, uses and articles

    DOEpatents

    Duchane, D.V.; Barthell, B.L.

    1982-10-21

    Hydrophobic cellular material is coated with a thin hydrophilic polymer skin which stretches tightly over the foam but which does not fill the cells of the foam, thus resulting in a polymer-coated foam structure having a smoothness which was not possible in the prior art. In particular, when the hydrophobic cellular material is a specially chosen hydrophobic polymer foam and is formed into arbitrarily chosen shapes prior to the coating with hydrophilic polymer, inertial confinement fusion (ICF) targets of arbitrary shapes can be produced by subsequently coating the shapes with metal or with any other suitable material. New articles of manufacture are produced, including improved ICF targets, improved integrated circuits, and improved solar reflectors and solar collectors. In the coating method, the cell size of the hydrophobic cellular material, the viscosity of the polymer solution used to coat, and the surface tension of the polymer solution used to coat are all very important to the coating.

  10. Silicon-based Porous Ceramics via Freeze Casting of Preceramic Polymers

    NASA Astrophysics Data System (ADS)

    Naviroj, Maninpat

    Freeze casting is a technique for processing porous materials that has drawn significant attention for its effectiveness in producing a variety of tailorable pore structures for ceramics, metals, and polymers. With freeze casting, pores are generated based on a solidification process where ice crystals act as a sacrificial template which can eventually be sublimated to create pores. While the majority of freeze-casting studies have been performed using conventional ceramic suspensions, this work explores an alternative processing route by freeze casting with preceramic polymer solutions. Significant differences exist between freeze casting of a particulate suspension and a polymeric solution. These changes affect the processing method, solidification behavior, and pore structure, thereby introducing new challenges and possibilities for the freeze-casting technique. The first part of this study explored the processing requirements involved with freeze casting of preceramic polymers, along with methods to control the resulting pore structure. Solvent choice, freezing front velocity, and polymer concentration were used as processing variables to manipulate the pore structures. A total of seven organic solvents were freeze cast with a polymethylsiloxane preceramic polymer to produce ceramics with isotropic, dendritic, prismatic, and lamellar pore morphologies. Changes in freezing front velocity and polymer concentration were shown to influence pore size, shape, and connectivity. Differences between suspension- and solution-based samples freeze cast under equivalent conditions were also investigated. Certain solidification microstructures were strongly affected by the presence of suspended particles, creating differences between pore structures generated from the same solvents. Additionally, processing of solution-based samples were found to be the more facile technique. Compressive strength and water permeability of dendritic and lamellar structures were analyzed to

  11. Method for making nanoporous hydrophobic coatings

    DOEpatents

    Fan, Hongyou; Sun, Zaicheng

    2013-04-23

    A simple coating method is used to form nanoporous hydrophobic films that can be used as optical coatings. The method uses evaporation-induced self-assembly of materials. The coating method starts with a homogeneous solution comprising a hydrophobic polymer and a surfactant polymer in a selective solvent. The solution is coated onto a substrate. The surfactant polymer forms micelles with the hydrophobic polymer residing in the particle core when the coating is dried. The surfactant polymer can be dissolved and selectively removed from the separated phases by washing with a polar solvent to form the nanoporous hydrophobic film.

  12. Fabricate Optical Microfiber by Using Flame Brushing Technique and Coated with Polymer Polyaniline for Sensing Application

    NASA Astrophysics Data System (ADS)

    Razak, N. A.; Hamida, B. A.; Irawati, N.; Habaebi, M. H.

    2017-06-01

    Adiabaticity is one of the essential criteria in producing good fabricated tapered fibers. Good tapered fibers can be use in sensor application such as humidity sensor, temperature sensor and refractive index sensor. In this paper, good tapering silica fiber is produced by using flame brushing technique and then, the microfiber is coated with polymer Polyaniline (PAni) to sense different type of alcohols with different concentrations. The outcome of this experiment gives excellent repeatability in the detection of alcohol sensing with a sensitivity of 0.1332 μW/% and a resolution of 3.764%. In conclusion, conducting polymer coated optical microfiber sensor for alcohol detection with low cost, effective and simple set-up was successfully achieved in this study.

  13. Three-phase bone scan and indium white blood cell scintigraphy following porous coated hip arthroplasty: A prospective study of the prosthetic tip

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Oswald, S.G.; Van Nostrand, D.; Savory, C.G.

    1989-08-01

    Although few reports address the use of three-phase bone scanning (TPBS) and {sup 111}In-labeled white blood cell (In-WBC) scintigraphy in hip arthroplasty utilizing a porous coated prosthesis, the literature suggests that scintigraphic patterns in the uncomplicated patient may differ from that seen in the cemented prosthesis. In an attempt to determine the scintigraphic natural history, 25 uncomplicated porous coated hip arthroplasties in 21 patients were prospectively studied with serial TPBS and In-WBC at approximately 7 days, and at 3, 6, 12, 18, and 24 mo postoperatively. This report deals with findings related to the prosthetic tip. Only one of 136more » flow studies were abnormal and only two of 136 blood-pool images demonstrated focally increased activity. All 25 prostheses (120 of 143 scans) demonstrated increased uptake on the bone phase images. The area about the tip was divided into three segments; increased uptake at 24 mo was noted in the medial, distal, and lateral segments in 16%, 72%, and 56% of prostheses, respectively. Twenty of 25 prostheses (82 of 142 scans) showed uptake on In-WBC scintigraphy, being noted in 48% of prostheses at 24 mo. We conclude that scintigraphic patterns in the uncomplicated patient with a porous coated prosthesis appear to differ from patterns described in cemented prostheses.« less

  14. Stainless and Galvanized Steel, Hydrophobic Admixture and Flexible Polymer-Cement Coating Compared in Increasing Durability of Reinforced Concrete Structures

    NASA Astrophysics Data System (ADS)

    Tittarelli, Francesca; Giosuè, Chiara; Mobili, Alessandra

    2017-08-01

    The use of stainless or galvanized steel reinforcements, a hydrophobic admixture or a flexible polymer-cement coating were compared as methods to improve the corrosion resistance of sound or cracked reinforced concrete specimens exposed to chloride rich solutions. The results show that in full immersion condition, negligible corrosion rates were detected in all cracked specimens, except those treated with the flexible polymer-cement mortar as preventive method against corrosion and the hydrophobic concrete specimens. High corrosion rates were measured in all cracked specimens exposed to wet-dry cycles, except for those reinforced with stainless steel, those treated with the flexible polymer-cement coating as restorative method against reinforcement corrosion and for hydrophobic concrete specimens reinforced with galvanized steel reinforcements.

  15. Highly Specific Binding on Antifouling Zwitterionic Polymer-Coated Microbeads as Measured by Flow Cytometry.

    PubMed

    van Andel, Esther; de Bus, Ian; Tijhaar, Edwin J; Smulders, Maarten M J; Savelkoul, Huub F J; Zuilhof, Han

    2017-11-08

    Micron- and nano-sized particles are extensively used in various biomedical applications. However, their performance is often drastically hampered by the nonspecific adsorption of biomolecules, a process called biofouling, which can cause false-positive and false-negative outcomes in diagnostic tests. Although antifouling coatings have been extensively studied on flat surfaces, their use on micro- and nanoparticles remains largely unexplored, despite the widespread experimental (specifically, clinical) uncertainties that arise because of biofouling. Here, we describe the preparation of magnetic micron-sized beads coated with zwitterionic sulfobetaine polymer brushes that display strong antifouling characteristics. These coated beads can then be equipped with recognition elements of choice, to enable the specific binding of target molecules. First, we present a proof of principle with biotin-functionalized beads that are able to specifically bind fluorescently labeled streptavidin from a complex mixture of serum proteins. Moreover, we show the versatility of the method by demonstrating that it is also possible to functionalize the beads with mannose moieties to specifically bind the carbohydrate-binding protein concanavalin A. Flow cytometry was used to show that thus-modified beads only bind specifically targeted proteins, with minimal/near-zero nonspecific protein adsorption from other proteins that are present. These antifouling zwitterionic polymer-coated beads, therefore, provide a significant advancement for the many bead-based diagnostic and other biosensing applications that require stringent antifouling conditions.

  16. Highly Specific Binding on Antifouling Zwitterionic Polymer-Coated Microbeads as Measured by Flow Cytometry

    PubMed Central

    2017-01-01

    Micron- and nano-sized particles are extensively used in various biomedical applications. However, their performance is often drastically hampered by the nonspecific adsorption of biomolecules, a process called biofouling, which can cause false-positive and false-negative outcomes in diagnostic tests. Although antifouling coatings have been extensively studied on flat surfaces, their use on micro- and nanoparticles remains largely unexplored, despite the widespread experimental (specifically, clinical) uncertainties that arise because of biofouling. Here, we describe the preparation of magnetic micron-sized beads coated with zwitterionic sulfobetaine polymer brushes that display strong antifouling characteristics. These coated beads can then be equipped with recognition elements of choice, to enable the specific binding of target molecules. First, we present a proof of principle with biotin-functionalized beads that are able to specifically bind fluorescently labeled streptavidin from a complex mixture of serum proteins. Moreover, we show the versatility of the method by demonstrating that it is also possible to functionalize the beads with mannose moieties to specifically bind the carbohydrate-binding protein concanavalin A. Flow cytometry was used to show that thus-modified beads only bind specifically targeted proteins, with minimal/near-zero nonspecific protein adsorption from other proteins that are present. These antifouling zwitterionic polymer-coated beads, therefore, provide a significant advancement for the many bead-based diagnostic and other biosensing applications that require stringent antifouling conditions. PMID:29064669

  17. Evaluating the in vivo glial response to miniaturized parylene cortical probes coated with an ultra-fast degrading polymer to aid insertion

    NASA Astrophysics Data System (ADS)

    Lo, Meng-chen; Wang, Shuwu; Singh, Sagar; Damodaran, Vinod B.; Ahmed, Ijaz; Coffey, Kevin; Barker, David; Saste, Kshitij; Kals, Karanvir; Kaplan, Hilton M.; Kohn, Joachim; Shreiber, David I.; Zahn, Jeffrey D.

    2018-06-01

    Objective. Despite the feasibility of short-term neural recordings using implantable microelectrodes, attaining reliable, chronic recordings remains a challenge. Most neural recording devices suffer from a long-term tissue response, including gliosis, at the device–tissue interface. It was hypothesized that smaller, more flexible intracortical probes would limit gliosis by providing a better mechanical match with surrounding tissue. Approach. This paper describes the in vivo evaluation of flexible parylene microprobes designed to improve the interface with the adjacent neural tissue to limit gliosis and thereby allow for improved recording longevity. The probes were coated with an ultrafast degrading tyrosine-derived polycarbonate (E5005(2K)) polymer that provides temporary mechanical support for device implantation, yet degrades within 2 h post-implantation. A parametric study of probes of varying dimensions and polymer coating thicknesses were implanted in rat brains. The glial tissue response and neuronal loss were assessed from 72 h to 24 weeks post-implantation via immunohistochemistry. Main results. Experimental results suggest that both probe and polymer coating sizes affect the extent of gliosis. When an appropriate sized coating dimension (100 µm  ×  100 µm) and small probe (30 µm  ×  5 µm) was implanted, a minimal post-implantation glial response was observed. No discernible gliosis was detected when compared to tissue where a sham control consisting of a solid degradable polymer shuttle of the same dimensions was inserted. A larger polymer coating (200 µm  ×  200 µm) device induced a more severe glial response at later time points, suggesting that the initial insertion trauma can affect gliosis even when the polymer shuttle degrades rapidly. A larger degree of gliosis was also observed when comparing a larger sized probe (80 µm  ×  5 µm) to a smaller probe (30 µm  ×  5 µm) using the same

  18. A computational study of bulk porous two-dimensional polymers related to graphyne.

    PubMed

    Sánchez-González, A; Dobado, J A; Torneiro, M

    2016-08-03

    Over the last twelve years there has been an explosion in the area of reticular chemistry with several classes of carbonaceous or carbon-rich reticular compounds coming into the scene and/or suffering an exponential growth in the number of related studies. Examples are MOFs, COFs, graphene and 2D polymers. π-Conjugated reticular compounds in particular are of great interest due to their optoelectronic properties. In this study we use density functional theory methods with periodic boundary conditions to investigate the stacking arrangements of bulk 2D polymer multilayer porous graphyne A, the related carbon allotrope multilayer graphyne B, and the analog bulk 2D polymer C in which the triple bonds of A are substituted by double bonds. The results show that for the three materials the eclipsed stacking arrangements are considerably less stable than staggered and slipped arrangements, with the more stable structures being slipped, staggered and off-centered-staggered arrangements for A, B and C, respectively. To shed light on the π-π interactions responsible for the geometry and relative energies of the different stacking modes we analyze the topology of the electron density using the electron localization function. In addition, simulated patterns for powder X-ray diffraction have been obtained from the optimized systems, which can be used for identification of the bulk 2D reticular compounds in future syntheses.

  19. Antimicrobial activity and cytotoxicity of cotton fabric coated with conducting polymers, polyaniline or polypyrrole, and with deposited silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Maráková, Nela; Humpolíček, Petr; Kašpárková, Věra; Capáková, Zdenka; Martinková, Lenka; Bober, Patrycja; Trchová, Miroslava; Stejskal, Jaroslav

    2017-02-01

    Cotton fabric was coated with conducting polymers, polyaniline or polypyrrole, in situ during the oxidation of respective monomers. Raman and FTIR spectra proved the complete coating of substrates. Polypyrrole content was 19.3 wt.% and that of polyaniline 6.0 wt.%. Silver nanoparticles were deposited from silver nitrate solutions of various concentrations by exploiting the reduction ability of conducting polymers. The content of silver was up to 11 wt.% on polypyrrole and 4 wt.% on polyaniline. The sheet resistivity of fabrics was determined. The conductivity was reduced after deposition of silver. The chemical cleaning reduced the conductivity by less than one order of magnitude for polypyrrole coating, while for polyaniline the decrease was more pronounced. The good antibacterial activity against S. aureus and E. coli and low cytotoxicity of polypyrrole-coated cotton, both with and without deposited silver nanoparticles

  20. Surface dynamics and mechanics in liquid crystal polymer coatings

    NASA Astrophysics Data System (ADS)

    Liu, Danqing; Broer, Dirk J.

    2015-03-01

    Based on liquid crystal networks we developed `smart' coatings with responsive surface topographies. Either by prepatterning or by the formation of self-organized structures they can be switched on and off in a pre-designed manner. Here we provide an overview of our methods to generate coatings that form surface structures upon the actuation by light. The coating oscillates between a flat surface and a surface with pre-designed 3D micro-patterns by modulating a light source. With recent developments in solid state lighting, light is an attractive trigger medium as it can be integrated in a device for local control or can be used remotely for flood or localized exposure. The basic principle of formation of surface topographies is based on the change of molecular organization in ordered liquid crystal polymer networks. The change in order leads to anisotropic dimensional changes with contraction along the director and expansion to the two perpendicular directions and an increase in volume by the formation of free volume. These two effects work in concert to provide local expansion and contraction in the coating steered by the local direction of molecular orientation. The surface deformation, expressed as the height difference between the activated regions and the non-activated regions divided by the initial film thickness, is of the order of 20%. Switching occurs immediately when the light is switched `on' and `off' and takes several tens of seconds.

  1. Investigations on the Mechanical Properties of Conducting Polymer Coating-Substrate Structures and Their Influencing Factors

    PubMed Central

    Wang, Xi-Shu; Tang, Hua-Ping; Li, Xu-Dong; Hua, Xin

    2009-01-01

    This review covers recent advances and work on the microstructure features, mechanical properties and cracking processes of conducting polymer film/coating- substrate structures under different testing conditions. An attempt is made to characterize and quantify the relationships between mechanical properties and microstructure features. In addition, the film cracking mechanism on the micro scale and some influencing factors that play a significant role in the service of the film-substrate structure are presented. These investigations cover the conducting polymer film/coating nucleation process, microstructure-fracture characterization, translation of brittle-ductile fractures, and cracking processes near the largest inherent macromolecule defects under thermal-mechanical loadings, and were carried out using in situ scanning electron microscopy (SEM) observations, as a novel method for evaluation of interface strength and critical failure stress. PMID:20054470

  2. Assessment of Erosion Resistance of Coated Polymer Matrix Composites for Propulsion Applications

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa; Sutter, James K.; Horan, Richard A.; Naik, Subhash K.; Cupp, Randall J.

    2004-01-01

    The erosion behavior of tungsten carbide-cobalt (WC-Co) coated and uncoated polymer matrix composites (PMCs) was examined with solid particle impingement using air jets. Erosion tests were conducted with Arizona road dust impinging at 20 degrees, 60 degrees, and 90 degrees angles at a velocity of 229 meters per second at both 294 and 366 K. Noncontact optical profilometry was used to measure the wear volume loss. Results indicate that the WC-Co coating enhanced erosion resistance and reduced erosion wear volume loss by a factor of nearly 2. This should contribute to longer wear lives, reduced related breakdowns, decreased maintenance costs, and increased product reliability.

  3. Substrate dependent stability of conducting polymer coatings on medical electrodes.

    PubMed

    Green, Rylie A; Hassarati, Rachelle T; Bouchinet, Lucie; Lee, Chaekyung S; Cheong, Gin L M; Yu, Jin F; Dodds, Christopher W; Suaning, Gregg J; Poole-Warren, Laura A; Lovell, Nigel H

    2012-09-01

    Conducting polymer (CP) coatings on medical electrodes have the potential to provide superior performance when compared to conventional metallic electrodes, but their stability is strongly dependant on the substrate properties. The aim of this study was to examine the effect of laser roughening of underlying platinum (Pt) electrode surfaces on the mechanical, electrical and biological performance of CP coatings. In addition, the impact of dopant type on electrical performance and stability was assessed. The CP poly(ethylene dioxythiophene) (PEDOT) was coated on Pt microelectrode arrays, with three conventional dopant ions. The in vitro electrical characteristics were assessed by cyclic voltammetry and biphasic stimulation. Results showed that laser roughening of the underlying substrate did not affect the charge injection limit of the coated material, but significantly improved the passive stability and chronic stimulation lifetime without failure of the coating. Accelerated material ageing and long-term biphasic stimulus studies determined that some PEDOT variants experienced delamination within as little as 10 days when the underlying Pt was smooth, but laser roughening to produce a surface index of 2.5 improved stability, such that more than 1.3 billion stimulation cycles could be applied without evidence of failure. PEDOT doped with paratoluene sulfonate (PEDOT/pTS) was found to be the most stable CP on roughened Pt, and presented a surface topography which encouraged neural cell attachment. Crown Copyright © 2012. Published by Elsevier Ltd. All rights reserved.

  4. Algal antifouling and fouling-release properties of metal surfaces coated with a polymer inspired by marine mussels.

    PubMed

    Statz, Andrea; Finlay, John; Dalsin, Jeffrey; Callow, Maureen; Callow, James A; Messersmith, Phillip B

    2006-01-01

    The marine antifouling and fouling-release performance of titanium surfaces coated with a bio-inspired polymer was investigated. The polymer consisted of methoxy-terminated poly(ethylene glycol) (mPEG) conjugated to the adhesive amino acid l-3,4-dihydroxyphenylalanine (DOPA) and was chosen based on its successful resistance to protein and mammalian cell fouling. Biofouling assays for the settlement and release of the diatom Navicula perminuta and settlement, growth and release of zoospores and sporelings (young plants) of the green alga Ulva linza were carried out. Results were compared to glass, a poly(dimethylsiloxane) elastomer (Silastic T2) and uncoated Ti. The mPEG-DOPA3 modified Ti surfaces exhibited a substantial decrease in attachment of both cells of N. perminuta and zoospores of U. linza as well as the highest detachment of attached cells under flow compared to control surfaces. The superior performance of this polymer over a standard silicone fouling-release coating in diatom assays and approximately equivalent performance in zoospore assays suggests that this bio-inspired polymer may be effective in marine antifouling and fouling-release applications.

  5. Tantalum coating of porous carbon scaffold supplemented with autologous bone marrow stromal stem cells for bone regeneration in vitro and in vivo

    PubMed Central

    Wei, Xiaowei; Wang, Benjie; Wang, Wei; Kang, Kai; Xie, Hui; Liu, Baoyi; Zhang, Xiuzhi; Zhang, Jinsong; Yang, Zhenming

    2016-01-01

    Porous tantalum metal with low elastic modulus is similar to cancellous bone. Reticulated vitreous carbon (RVC) can provide three-dimensional pore structure and serves as the ideal scaffold of tantalum coating. In this study, the biocompatibility of domestic porous tantalum was first successfully tested with bone marrow stromal stem cells (BMSCs) in vitro and for bone tissue repair in vivo. We evaluated cytotoxicity of RVC scaffold and tantalum coating using BMSCs. The morphology, adhesion, and proliferation of BMSCs were observed via laser scanning confocal microscope and scanning electron microscopy. In addition, porous tantalum rods with or without autologous BMSCs were implanted on hind legs in dogs, respectively. The osteogenic potential was observed by hard tissue slice examination. At three weeks and six weeks following implantation, new osteoblasts and new bone were observed at the tantalum–host bone interface and pores. At 12 weeks postporous tantalum with autologous BMSCs implantation, regenerated trabecular equivalent to mature bone was found in the pore of tantalum rods. Our results suggested that domestic porous tantalum had excellent biocompatibility and could promote new bone formation in vivo. Meanwhile, the osteogenesis of porous tantalum associated with autologous BMSCs was more excellent than only tantalum implantation. Future clinical studies are warranted to verify the clinical efficacy of combined implantation of this domestic porous tantalum associated with autologous BMSCs implantation and compare their efficacy with conventional autologous bone grafting carrying blood vessel in patients needing bone repairing. PMID:26843518

  6. Bio-based Interpenetrating Network Polymer Composites from Locust Sawdust as Coating Material for Environmentally Friendly Controlled-Release Urea Fertilizers.

    PubMed

    Zhang, Shugang; Yang, Yuechao; Gao, Bin; Wan, Yongshan; Li, Yuncong C; Zhao, Chenhao

    2016-07-20

    A novel polymer-coated nitrogen (N) fertilizer was developed using bio-based polyurethane (PU) derived from liquefied locust sawdust as the coating material. The bio-based PU was successfully coated on the surface of the urea fertilizer prills to form polymer-coated urea (PCU) fertilizer for controlled N release. Epoxy resin (EP) was also used to further modify the bio-based PU to synthesize the interpenetrating network (IPN), enhancing the slow-release properties of the PCU. The N release characteristics of the EP-modified PCU (EMPCU) in water were determine at 25 °C and compared to that of PCU and EP-coated urea (ECU). The results showed that the EP modification reduced the N release rate and increased the longevity of the fertilizer coated with bio-based PU. A corn growth study was conducted to further evaluate the filed application of the EMPCU. In comparison to commercial PCU and conventional urea fertilizer, EMPCU was more effective and increased the yield and total dry matter accumulation of the corn. Findings from this work indicated that bio-based PU derived from sawdust can be used as coating materials for PCU, particularly after EP modification. The resulting EMPCU was more environmentally friendly and cost-effective than conventional urea fertilizers coated by EP.

  7. Multiscale mechanics of the lateral pressure effect on enhancing the load transfer between polymer coated CNTs.

    PubMed

    Yazdandoost, Fatemeh; Mirzaeifar, Reza; Qin, Zhao; Buehler, Markus J

    2017-05-04

    While individual carbon nanotubes (CNTs) are known as one of the strongest fibers ever known, even the strongest fabricated macroscale CNT yarns and fibers are still significantly weaker than individual nanotubes. The loss in mechanical properties is mainly because the deformation mechanism of CNT fibers is highly governed by the weak shear strength corresponding to sliding of nanotubes on each other. Adding polymer coating to the bundles, and twisting the CNT yarns to enhance the intertube interactions are both efficient methods to improve the mechanical properties of macroscale yarns. Here, we perform molecular dynamics (MD) simulations to unravel the unknown deformation mechanism in the intertube polymer chains and also local deformations of the CNTs at the atomistic scale. Our results show that the lateral pressure can have both beneficial and adverse effects on shear strength of polymer coated CNTs, depending on the local deformations at the atomistic scale. In this paper we also introduce a bottom-up bridging strategy between a full atomistic model and a coarse-grained (CG) model. Our trained CG model is capable of incorporating the atomistic scale local deformations of each CNT to the larger scale collect behavior of bundles, which enables the model to accurately predict the effect of lateral pressure on larger CNT bundles and yarns. The developed multiscale CG model is implemented to study the effect of lateral pressure on the shear strength of straight polymer coated CNT yarns, and also the effect of twisting on the pull-out force of bundles in spun CNT yarns.

  8. Biocompatible polymer coating of titania nanotube arrays for improved drug elution and osteoblast adhesion.

    PubMed

    Gulati, Karan; Ramakrishnan, Saminathan; Aw, Moom Sinn; Atkins, Gerald J; Findlay, David M; Losic, Dusan

    2012-01-01

    Bacterial infection, extensive inflammation and poor osseointegration have been identified as the major reasons for [early] orthopaedic implant failures based on titanium. Creating implants with drug-eluting properties to locally deliver drugs is an appealing way to address some of these problems. To improve properties of titanium for orthopaedic applications, this study explored the modification of titanium surfaces with titaniananotube (TNT) arrays, and approach that combines drug delivery into bone and potentially improved bone integration. A titania layer with an array of nanotube structures (∼120 nm in diameter and 50 μm in length) was synthesized on titanium surfaces by electrochemical anodization and loaded with the water-insoluble anti-inflammatory drug indomethacin. A simple dip-coating process of polymer modification formed thin biocompatible polymer films over the drug-loaded TNTs to create TNTs with predictable drug release characteristics. Two biodegradable and antibacterial polymers, chitosan and poly(lactic-co-glycolic acid), were tested for their ability to extend the drug release time of TNTs and produce favourable bone cell adhesion properties. Dependent on polymer thickness, a significant improvement in the drug release characteristics was demonstrated, with reduced burst release (from 77% to >20%) and extended overall release from 4 days to more than 30 days. Excellent osteoblast adhesion and cell proliferation on polymer-coated TNTs compared with uncoated TNTs were also observed. These results suggest that polymer-modified implants with a TNT layer are capable of delivering a drug to a bone site over an extended period and with predictable kinetics. In addition, favourable bone cell adhesion suggests that such an implant would have good biocompatibility. The described approach is broadly applicable to a wide range of drugs and implants currently used in orthopaedic practice. Crown Copyright © 2011. Published by Elsevier Ltd. All rights

  9. Effects of poly (ε-caprolactone) coating on the properties of three-dimensional printed porous structures.

    PubMed

    Zhou, Zuoxin; Cunningham, Eoin; Lennon, Alex; McCarthy, Helen O; Buchanan, Fraser; Clarke, Susan A; Dunne, Nicholas

    2017-06-01

    Powder-based inkjet three-dimensional printing (3DP) to fabricate pre-designed 3D structures has drawn increasing attention. However there are intrinsic limitations associated with 3DP technology due to the weak bonding within the printed structure, which significantly compromises its mechanical integrity. In this study, calcium sulphate ceramic structures demonstrating a porous architecture were manufactured using 3DP technology and subsequently post-processed with a poly (ε-caprolactone) (PCL) coating. PCL concentration, immersion time, and number of coating layers were the principal parameters investigated and improvement in compressive properties was the measure of success. Interparticle spacing within the 3DP structures were successfully filled with PCL material. Consequently the compressive properties, wettability, morphology, and in vitro resorption behaviour of 3DP components were significantly augmented. The average compressive strength, Young׳s modulus, and toughness increased 217%, 250%, and 315%, following PCL coating. Addition of a PCL surface coating provided long-term structural support to the host ceramic material, extending the resorption period from less than 7 days to a minimum of 56 days. This study has demonstrated that application of a PCL coating onto a ceramic 3DP structure was a highly effective approach to addressing some of the limitations of 3DP manufacturing and allows this advanced technology to be potentially used in a wider range of applications. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Polymer subtrates for dry-coupled ultrasonic transducers

    NASA Astrophysics Data System (ADS)

    Komsky, Igor N.

    2003-07-01

    Dry-coupled inspection techniques are very important for applications on components with non-uniform surfaces and for inspections of advanced materials or coatings that are porous or otherwise sensitive to the application of water, gel, or some other ultrasonic couplants. To overcome the problems associated with the liquid coupling medium, a number of polymer films have been developed to transmit the ultrasound through a dry interface. These materials are very flexible so even low pressure loading is sufficient to adapt the films to the irregular inspection surfaces. Several polymer films have been evaluated to develop dry-coupled substrates for transducer modules. The modules will be utilized to detect and characterize fatigue cracks and corrosion spots in the aircraft structures. Ultrasonic properties of the polymer films were measured and compared with the properties of plastic or rubber-like materials commonly used for ultrasonic applications. Experiments have been carried out to analyze propagation of longitudinal and shear waves in the films. Two different types of the ultrasonic modules with the flexible polymer substrates are being developed. The influence of the surface condition on the module performance was evaluated for both types of the modules.

  11. Enhanced structural color generation in aluminum metamaterials coated with a thin polymer layer

    DOE PAGES

    Cheng, Fei; Yang, Xiaodong; Rosenmann, Daniel; ...

    2015-09-18

    A high-resolution and angle-insensitive structural color generation platform is demonstrated based on triple-layer aluminum-silica-aluminum metamaterials supporting surface plasmon resonances tunable across the entire visible spectrum. The color performances of the fabricated aluminum metamaterials can be strongly enhanced by coating a thin transparent polymer layer on top. The results show that the presence of the polymer layer induces a better impedance matching for the plasmonic resonances to the free space so that strong light absorption can be obtained, leading to the generation of pure colors in cyan, magenta, yellow and black (CMYK) with high color saturation.

  12. A versatile semi-permanent sequential bilayer/diblock polymer coating for capillary isoelectric focusing.

    PubMed

    Bahnasy, Mahmoud F; Lucy, Charles A

    2012-12-07

    A sequential surfactant bilayer/diblock copolymer coating was previously developed for the separation of proteins. The coating is formed by flushing the capillary with the cationic surfactant dioctadecyldimethylammonium bromide (DODAB) followed by the neutral polymer poly-oxyethylene (POE) stearate. Herein we show the method development and optimization for capillary isoelectric focusing (cIEF) separations based on the developed sequential coating. Electroosmotic flow can be tuned by varying the POE chain length which allows optimization of resolution and analysis time. DODAB/POE 40 stearate can be used to perform single-step cIEF, while both DODAB/POE 40 and DODAB/POE 100 stearate allow performing two-step cIEF methodologies. A set of peptide markers is used to assess the coating performance. The sequential coating has been applied successfully to cIEF separations using different capillary lengths and inner diameters. A linear pH gradient is established only in two-step CIEF methodology using 3-10 pH 2.5% (v/v) carrier ampholyte. Hemoglobin A(0) and S variants are successfully resolved on DODAB/POE 40 stearate sequentially coated capillaries. Copyright © 2012 Elsevier B.V. All rights reserved.

  13. Comparative experiments for in vivo fibroplasia and biological stability of four porous polymers intended for use in the Seoul-type keratoprosthesis

    PubMed Central

    Kim, M K; Lee, J L; Wee, W R; Lee, J H

    2002-01-01

    Aims: To evaluate in vivo fibroplasia and biological stability of porous polymers intended for use in the Seoul-type keratoprosthesis (S-KPro). Methods: Four porous polymers (polypropylene, two kinds of polyethylene terephthalate (PE70 and PE50), and polyurethane) were investigated. Discs of polymers were inserted into the corneal stroma of rabbits for a 2 and 5 month period. Corneal oedema and neovascularisation were evaluated. The fibroplasia and collagen deposition were examined under light and transmission electron microscopy. S-KPros, whose skirt was made of four types of polymer, were implanted into the rabbits' eyes. The retention time and complications were evaluated. Results: Neovascularisation and corneal oedema were found in all of the disc inserted eyes, but the corneal oedema subsided within 2 months in most of the eyes. The mean number of fibroblasts increased significantly in polypropylene and PE50 disc inserted eyes compared with polyurethane disc inserted eyes. Plentiful collagen deposition was also found in both polypropylene and PE50 disc inserted eyes. Mean retention time in the polypropylene SK-Pro implanted eyes was longer than that of the other eyes (20.7 weeks). The PE70 skirt induced corneal melting around the prosthesis. Conclusion: Polypropylene encourages fibroblast ingrowth and shows good biological stability when used as a skirt material in S-KPro. PMID:12084755

  14. Facile preparation of polymer microspheres and fibers with a hollow core and porous shell for oil adsorption and oil/water separation

    NASA Astrophysics Data System (ADS)

    Gao, Jiefeng; Song, Xin; Huang, Xuewu; Wang, Ling; Li, Bei; Xue, Huaiguo

    2018-05-01

    Non-solvent assisted electrospinning was proposed for fabricating Polymethylmethacrylate (PMMA) microspheres and fibers with a hollow core and porous shell, which could be used for oil adsorption and oil/water separation. Propanediol was chosen as the non-solvent because of its high surface tension and viscosity as well as large phase separation tendency with polymer, which was beneficial to the formation of both the hollow core and porous shell during the electrospinning. With the increase of the polymer solution concentration, the microsphere gradually evolved to the bead-on-string geometry and finally to a continuous fiber form, indicating the transition from electro-spraying to electrospinning. The hollow core and dense surface pores enhanced the hydrophobicity, oleophilicity, permeability, and specific surface area of the fibers, and hence imparted the fibrous mat a high oil adsorption capacity. When the porous hollow microspheres were electro-sprayed onto the stainless steel mesh followed by the PDMS modification, the modified mesh became super-hydrophobic and super-oleophilic with the contact angle of 153° and sliding angle of 4°. The as-prepared mesh showed rapid oil/water separation with high efficiency and excellent recycling performance. The flux for separation of oil/water mixture could reach as high as 11,000 L m-2 h-1. This facile non-solvent assisted electrospinning method provides a new avenue for preparation of multifunctional porous materials which possess potential applications in large-scale oil/water separation.

  15. Sol-Gel Processing of MgF2 Antireflective Coatings

    PubMed Central

    Löbmann, Peer

    2018-01-01

    There are different approaches for the preparation of porous antireflective λ/4 MgF2 films from liquid precursors. Among these, the non-aqueous fluorolytic synthesis of precursor solutions offers many advantages in terms of processing simplicity and scalability. In this paper, the structural features and optical performance of the resulting films are highlighted, and their specific interactions with different inorganic substrates are discussed. Due to their excellent abrasion resistance, coatings have a high potential for applications on glass. Using solvothermal treatment of precursor solutions, also the processing of thermally sensitive polymer substrates becomes feasible. PMID:29724064

  16. Multiscale Computer Simulation of Tensile and Compressive Strain in Polymer- Coated Silica Aerogels

    NASA Technical Reports Server (NTRS)

    Good, Brian

    2009-01-01

    While the low thermal conductivities of silica aerogels have made them of interest to the aerospace community as lightweight thermal insulation, the application of conformal polymer coatings to these gels increases their strength significantly, making them potentially useful as structural materials as well. In this work we perform multiscale computer simulations to investigate the tensile and compressive strain behavior of silica and polymer-coated silica aerogels. Aerogels are made up of clusters of interconnected particles of amorphous silica of less than bulk density. We simulate gel nanostructure using a Diffusion Limited Cluster Aggregation (DLCA) procedure, which produces aggregates that exhibit fractal dimensions similar to those observed in real aerogels. We have previously found that model gels obtained via DLCA exhibited stress-strain curves characteristic of the experimentally observed brittle failure. However, the strain energetics near the expected point of failure were not consistent with such failure. This shortcoming may be due to the fact that the DLCA process produces model gels that are lacking in closed-loop substructures, compared with real gels. Our model gels therefore contain an excess of dangling strands, which tend to unravel under tensile strain, producing non-brittle failure. To address this problem, we have incorporated a modification to the DLCA algorithm that specifically produces closed loops in the model gels. We obtain the strain energetics of interparticle connections via atomistic molecular statics, and abstract the collective energy of the atomic bonds into a Morse potential scaled to describe gel particle interactions. Polymer coatings are similarly described. We apply repeated small uniaxial strains to DLCA clusters, and allow relaxation of the center eighty percent of the cluster between strains. The simulations produce energetics and stress-strain curves for looped and nonlooped clusters, for a variety of densities and

  17. Hard and flexible nanocomposite coatings using nanoclay-filled hyperbranched polymers.

    PubMed

    Fogelström, Linda; Malmström, Eva; Johansson, Mats; Hult, Anders

    2010-06-01

    The combination of hardness, scratch resistance, and flexibility is a highly desired feature in many coating applications. The aim of this study is to achieve this through the introduction of an unmodified nanoclay, montmorillonite (Na(+)MMT), in a polymer resin based on the hyperbranched polyester Boltorn H30. Smooth and transparent films were prepared from both the neat and the nanoparticle-filled hyperbranched resins. X-ray diffraction (XRD) and transmission electron microscopy (TEM) corroborated a mainly exfoliated structure in the nanocomposite films, which was also supported by results from dynamic mechanical analysis (DMA). Furthermore, DMA measurements showed a 9-16 degrees C increase in Tg and a higher storage modulus-above and below the T(g)-both indications of a more cross-linked network, for the clay-containing film. Thermogravimetric analysis (TGA) demonstrated the influence of the nanofiller on the thermal properties of the nanocomposites, where a shift upward of the decomposition temperature in oxygen atmosphere is attributed to the improved barrier properties of the nanoparticle-filled materials. Conventional coating characterization methods demonstrated an increase in the surface hardness, scratch resistance and flexibility, with the introduction of clay, and all coatings exhibited excellent chemical resistance and adhesion.

  18. Formation of Foam-like Microstructural Carbon Material by Carbonization of Porous Coordination Polymers through a Ligand-Assisted Foaming Process.

    PubMed

    Kongpatpanich, Kanokwan; Horike, Satoshi; Fujiwara, Yu-Ichi; Ogiwara, Naoki; Nishihara, Hirotomo; Kitagawa, Susumu

    2015-09-14

    Porous carbon material with a foam-like microstructure has been synthesized by direct carbonization of porous coordination polymer (PCP). In situ generation of foaming agents by chemical reactions of ligands in PCP during carbonization provides a simple way to create lightweight carbon material with a foam-like microstructure. Among several substituents investigated, the nitro group has been shown to be the key to obtain the unique foam-like microstructure, which is due to the fast kinetics of gas evolution during carbonization. Foam-like microstructural carbon materials showed higher pore volume and specific capacitance compared to a microporous carbon. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Superficially Porous Particles with 1000 Å Pores for Large Biomolecule High Performance Liquid Chromatography and Polymer Size Exclusion Chromatography

    PubMed Central

    Wagner, Brian M.; Schuster, Stephanie A.; Boyes, Barry E.; Shields, Taylor J.; Miles, William L.; Haynes, Mark J.; Moran, Robert E.; Kirkland, Joseph J.; Schure, Mark R.

    2017-01-01

    To facilitate mass transport and column efficiency, solutes must have free access to particle pores to facilitate interactions with the stationary phase. To ensure this feature, particles should be used for HPLC separations which have pores sufficiently large to accommodate the solute without restricted diffusion. This paper describes the design and properties of superficially porous (also called Fused-Core®, core shell or porous shell) particles with very large (1000 Å) pores specifically developed for separating very large biomolecules and polymers. Separations of DNA fragments, monoclonal antibodies, large proteins and large polystyrene standards are used to illustrate the utility of these particles for efficient, high-resolution applications. PMID:28213987

  20. Ultrasonic spray coating polymer and small molecular organic film for organic light-emitting devices.

    PubMed

    Liu, Shihao; Zhang, Xiang; Zhang, Letian; Xie, Wenfa

    2016-11-22

    Ultrasonic spray coating process (USCP) with high material -utilization, low manufacture costs and compatibility to streamline production has been attractive in researches on photoelectric devices. However, surface tension exists in the solvent is still a huge obstacle to realize smooth organic film for organic light emitting devices (OLEDs) by USCP. Here, high quality polymer anode buffer layer and small molecular emitting layer are successfully realized through USCP by introducing extra-low surface tension diluent and surface tension control method. The introduction of low surface tension methyl alcohol is beneficial to the formation of poly (3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) films and brings obvious phase separation and improved conductivity to PEDOT:PSS film. Besides, a surface tension control method, in which new stable tension equilibrium is built at the border of wetting layer, is proposed to eliminate the effect of surface tension during the solvent evaporation stage of ultrasonic spray coating the film consists of 9,9-Spirobifluoren-2-yl-diphenyl-phosphine oxide doped with 10 wt% tris [2-(p -tolyl) pyridine] iridium (III). A smooth and homogenous small molecular emitting layer without wrinkles is successfully realized. The effectiveness of the ultrasonic spray coating polymer anode buffer layer and small molecular emitting layer are also proved by introducing them in OLEDs.

  1. Ultrasonic spray coating polymer and small molecular organic film for organic light-emitting devices

    NASA Astrophysics Data System (ADS)

    Liu, Shihao; Zhang, Xiang; Zhang, Letian; Xie, Wenfa

    2016-11-01

    Ultrasonic spray coating process (USCP) with high material -utilization, low manufacture costs and compatibility to streamline production has been attractive in researches on photoelectric devices. However, surface tension exists in the solvent is still a huge obstacle to realize smooth organic film for organic light emitting devices (OLEDs) by USCP. Here, high quality polymer anode buffer layer and small molecular emitting layer are successfully realized through USCP by introducing extra-low surface tension diluent and surface tension control method. The introduction of low surface tension methyl alcohol is beneficial to the formation of poly (3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) films and brings obvious phase separation and improved conductivity to PEDOT:PSS film. Besides, a surface tension control method, in which new stable tension equilibrium is built at the border of wetting layer, is proposed to eliminate the effect of surface tension during the solvent evaporation stage of ultrasonic spray coating the film consists of 9,9-Spirobifluoren-2-yl-diphenyl-phosphine oxide doped with 10 wt% tris [2-(p -tolyl) pyridine] iridium (III). A smooth and homogenous small molecular emitting layer without wrinkles is successfully realized. The effectiveness of the ultrasonic spray coating polymer anode buffer layer and small molecular emitting layer are also proved by introducing them in OLEDs.

  2. Ultrasonic spray coating polymer and small molecular organic film for organic light-emitting devices

    PubMed Central

    Liu, Shihao; Zhang, Xiang; Zhang, Letian; Xie, Wenfa

    2016-01-01

    Ultrasonic spray coating process (USCP) with high material -utilization, low manufacture costs and compatibility to streamline production has been attractive in researches on photoelectric devices. However, surface tension exists in the solvent is still a huge obstacle to realize smooth organic film for organic light emitting devices (OLEDs) by USCP. Here, high quality polymer anode buffer layer and small molecular emitting layer are successfully realized through USCP by introducing extra-low surface tension diluent and surface tension control method. The introduction of low surface tension methyl alcohol is beneficial to the formation of poly (3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) films and brings obvious phase separation and improved conductivity to PEDOT:PSS film. Besides, a surface tension control method, in which new stable tension equilibrium is built at the border of wetting layer, is proposed to eliminate the effect of surface tension during the solvent evaporation stage of ultrasonic spray coating the film consists of 9,9-Spirobifluoren-2-yl-diphenyl-phosphine oxide doped with 10 wt% tris [2-(p -tolyl) pyridine] iridium (III). A smooth and homogenous small molecular emitting layer without wrinkles is successfully realized. The effectiveness of the ultrasonic spray coating polymer anode buffer layer and small molecular emitting layer are also proved by introducing them in OLEDs. PMID:27874030

  3. Improvement of mechanical robustness of the superhydrophobic wood surface by coating PVA/SiO2 composite polymer

    NASA Astrophysics Data System (ADS)

    Liu, Feng; Wang, Shuliang; Zhang, Ming; Ma, Miaolian; Wang, Chengyu; Li, Jian

    2013-09-01

    Improvement of the robustness of superhydrophobic surfaces is crucial for the purpose of achieving commercial applications of these surfaces in such various areas as self-cleaning, water repellency and corrosion resistance. We have investigated a fabrication of polyvinyl alcohol (PVA)/silica (SiO2) composite polymer coating on wooden substrates with super repellency toward water, low sliding angles, low contact angle hysteresis, and relatively better mechanical robustness. The composite polymer slurry, consisting of well-mixing SiO2 particles and PVA, is prepared simply and subsequently coated over wooden substrates with good adhesion. In this study, the mechanical robustness of superhydrophobic wood surfaces was evaluated. The effect of petaloid structures of the composite polymer on robustness was investigated using an abrasion test and the results were compared with those of superhydrophobic wood surfaces fabricated by other processes. The produced wood surfaces exhibited promising superhydrophobic properties with a contact angle of 159̊ and a sliding angle of 4̊, and the relatively better mechanical robustness.

  4. Tantalum coating of porous carbon scaffold supplemented with autologous bone marrow stromal stem cells for bone regeneration in vitro and in vivo.

    PubMed

    Wei, Xiaowei; Zhao, Dewei; Wang, Benjie; Wang, Wei; Kang, Kai; Xie, Hui; Liu, Baoyi; Zhang, Xiuzhi; Zhang, Jinsong; Yang, Zhenming

    2016-03-01

    Porous tantalum metal with low elastic modulus is similar to cancellous bone. Reticulated vitreous carbon (RVC) can provide three-dimensional pore structure and serves as the ideal scaffold of tantalum coating. In this study, the biocompatibility of domestic porous tantalum was first successfully tested with bone marrow stromal stem cells (BMSCs) in vitro and for bone tissue repair in vivo. We evaluated cytotoxicity of RVC scaffold and tantalum coating using BMSCs. The morphology, adhesion, and proliferation of BMSCs were observed via laser scanning confocal microscope and scanning electron microscopy. In addition, porous tantalum rods with or without autologous BMSCs were implanted on hind legs in dogs, respectively. The osteogenic potential was observed by hard tissue slice examination. At three weeks and six weeks following implantation, new osteoblasts and new bone were observed at the tantalum-host bone interface and pores. At 12 weeks postporous tantalum with autologous BMSCs implantation, regenerated trabecular equivalent to mature bone was found in the pore of tantalum rods. Our results suggested that domestic porous tantalum had excellent biocompatibility and could promote new bone formation in vivo. Meanwhile, the osteogenesis of porous tantalum associated with autologous BMSCs was more excellent than only tantalum implantation. Future clinical studies are warranted to verify the clinical efficacy of combined implantation of this domestic porous tantalum associated with autologous BMSCs implantation and compare their efficacy with conventional autologous bone grafting carrying blood vessel in patients needing bone repairing. © 2016 by the Society for Experimental Biology and Medicine.

  5. Construction of a thermoresponsive magnetic porous polymer membrane enzyme reactor for glutaminase kinetics study.

    PubMed

    Zhao, Liping; Qiao, Juan; Moon, Meyong Hee; Qi, Li

    2018-06-16

    Fabrication of polymer membranes with nanopores and a confinement effect toward enzyme immobilization has been an enabling endeavor. In the work reported here, an enzyme reactor based on a thermoresponsive magnetic porous block copolymer membrane was designed and constructed. Reversible addition-fragmentation chain transfer polymerization was used to synthesize the block copolymer, poly(maleic anhydride-styrene-N-isopropylacrylamide), with poly(N-isopropylacrylamide) as the thermoresponsive moiety. The self-assembly property of the block copolymer was used for preparation of magnetic porous thin film matrices with iron oxide nanoparticles. By covalent bonding of glutaminase onto the surface of the membrane matrices and changing the temperature to tune the nanopore size, we observed enhanced enzymolysis efficiency due to the confinement effect. The apparent Michaelis-Menten constant and the maximum rate of the enzyme reactor were determined (K m = 32.3 mM, V max = 33.3 mM min -1 ) by a chiral ligand exchange capillary electrochromatography protocol with L-glutamine as the substrate. Compared with free glutaminase in solution, the proposed enzyme reactor exhibits higher enzymolysis efficiency, greater stability, and greater reusability. Furthermore, the enzyme reactor was applied for a glutaminase kinetics study. The tailored pore sizes and the thermoresponsive property of the block copolymer result in the designed porous membrane based enzyme reactor having great potential for high enzymolysis performance. Graphical abstract ᅟ.

  6. Selective separation of lambdacyhalothrin by porous/magnetic molecularly imprinted polymers prepared by Pickering emulsion polymerization.

    PubMed

    Hang, Hui; Li, Chunxiang; Pan, Jianming; Li, Linzi; Dai, Jiangdong; Dai, Xiaohui; Yu, Ping; Feng, Yonghai

    2013-10-01

    Porous/magnetic molecularly imprinted polymers (PM-MIPs) were prepared by Pickering emulsion polymerization. The reaction was carried out in an oil/water emulsion using magnetic halloysite nanotubes as the stabilizer instead of a toxic surfactant. In the oil phase, the imprinting process was conducted by radical polymerization of functional and cross-linked monomers, and porogen chloroform generated steam under the high reaction temperature, which resulted in some pores decorated with easily accessible molecular binding sites within the as-made PM-MIPs. The characterization demonstrated that the PM-MIPs were porous and magnetic inorganic-polymer composite microparticles with magnetic sensitivity (M(s) = 0.7448 emu/g), thermal stability (below 473 K) and magnetic stability (over the pH range of 2.0-8.0). The PM-MIPs were used as a sorbent for the selective binding of lambdacyhalothrin (LC) and rapidly separated under an external magnetic field. The Freundlich isotherm model gave a good fit to the experimental data. The adsorption kinetics of the PM-MIPs was well described by pseudo-second-order kinetics, indicating that the chemical process could be the rate-limiting step in the adsorption of LC. The selective recognition experiments exhibited the outstanding selective adsorption effect of the PM-MIPs for target LC. Moreover, the PM-MIPs regeneration without significant loss in adsorption capacity was demonstrated by at least four repeated cycles. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Reactive processing and mechanical properties of polymer derived silicon nitride matrix composites and their use in coating and joining ceramics and ceramic matrix composites

    NASA Astrophysics Data System (ADS)

    Stackpoole, Margaret Mary

    Use of preceramic polymers offers many advantages over conventional ceramic processing routes. Advantages include being able to plastically form the part, form a pyrolized ceramic material at lower temperatures and form high purity microstructures which are tailorable depending on property requirements. To date preceramic polymers are mostly utilized in the production of low dimensional products such as fibers since loss of volatiles during pyrolysis leads to porosity and large shrinkage (in excess of 30%). These problems have been partially solved by use of active fillers (e.g. Ti, Cr, B). The reactive filler converts to a ceramic material with a volume expansion and this increases the density and reduces shrinkage and porosity. The expansion of the reactive filler thus compensates for the polymer shrinkage if the appropriate volume fraction of filler is present in a reactive atmosphere (e.g. N2 or NH3). This approach has resulted in structural composites with limited success. The present research investigates the possibility of using filled preceramic polymers to form net shaped ceramic composite materials and to investigate the use of these unique composite materials to join and coat ceramics and ceramic composites. The initial research focused on phase and microstructural development of bulk composites from the filled polymer/ceramic systems. A processing technique was developed to insure consistency between different samples and the most promising filler/polymer choices for this application have been determined. The processing temperatures and atmospheres have also been optimized. The work covers processing and characterization of bulk composites, joints and coatings. With careful control of processing near net shape bulk composites were fabricated. Both ambient and high temperature strength and fracture toughness was obtained for these composite systems. The potential of using reactively filled preceramic polymers to process joints and coatings was also

  8. High temperature ceramic articles having corrosion resistant coating

    DOEpatents

    Stinton, David P.; Lee, Woo Y.

    1997-01-01

    A ceramic article which includes a porous body of SiC fibers, Si.sub.3 N.sub.4 fibers, SiC coated fibers or Si.sub.3 N.sub.4 coated fibers, having at least one surface, the article having a coating of AlN adherently disposed throughout at least a portion of the porous body.

  9. Polymer-Reinforced, Non-Brittle, Lightweight Cryogenic Insulation

    NASA Technical Reports Server (NTRS)

    Hess, David M.

    2013-01-01

    The primary application for cryogenic insulating foams will be fuel tank applications for fueling systems. It is crucial for this insulation to be incorporated into systems that survive vacuum and terrestrial environments. It is hypothesized that by forming an open-cell silica-reinforced polymer structure, the foam structures will exhibit the necessary strength to maintain shape. This will, in turn, maintain the insulating capabilities of the foam insulation. Besides mechanical stability in the form of crush resistance, it is important for these insulating materials to exhibit water penetration resistance. Hydrocarbon-terminated foam surfaces were implemented to impart hydrophobic functionality that apparently limits moisture penetration through the foam. During the freezing process, water accumulates on the surfaces of the foams. However, when hydrocarbon-terminated surfaces are present, water apparently beads and forms crystals, leading to less apparent accumulation. The object of this work is to develop inexpensive structural cryogenic insulation foam that has increased impact resistance for launch and ground-based cryogenic systems. Two parallel approaches will be pursued: a silica-polymer co-foaming technique and a post foam coating technique. Insulation characteristics, flexibility, and water uptake can be fine-tuned through the manipulation of the polyurethane foam scaffold. Silicate coatings for polyurethane foams and aerogel-impregnated polyurethane foams have been developed and tested. A highly porous aerogel-like material may be fabricated using a co-foam and coated foam techniques, and can insulate at liquid temperatures using the composite foam

  10. Structure, composition and morphology of bioactive titanate layer on porous titanium surfaces

    NASA Astrophysics Data System (ADS)

    Li, Jinshan; Wang, Xiaohua; Hu, Rui; Kou, Hongchao

    2014-07-01

    A bioactive coating was produced on pore surfaces of porous titanium samples by an amendatory alkali-heat treatment method. Porous titanium was prepared by powder metallurgy and its porosity and average size were 45% and 135 μm, respectively. Coating morphology, coating structure and phase constituents were examined by SEM, XPS and XRD. It was found that a micro-network structure with sizes of <200 nm mainly composed of bioactive sodium titanate and rutile phases of TiO2 covered the interior and exterior of porous titanium cells, and redundant Ca ion was detected in the titanate layer. The concentration distribution of Ti, O, Ca and Na in the coating showed a compositional gradient from the intermediate layer toward the outer surface. These compositional gradients indicate that the coating bonded to Ti substrate without a distinct interface. After immersion into the SBF solution for 3 days, a bone-like carbonate-hydroxylapatite showing a good biocompatibility was detected on the coating surface. And the redundant Ca advanced the bioactivity of the coating. Thus, the present modification is expected to allow the use of the bioactive porous titanium as artificial bones even under load-bearing conditions.

  11. Preparation and Performance of Porous Polymer Electrolytes Doped with Nano-Al₂O₃.

    PubMed

    Jiang, Qingbai; Liang, Bo; Tang, Siqi; Chen, Xu

    2018-03-01

    Porous polymer electrolytes (PPEs) doped with nano-Al2O3 were prepared by a joint application of ultrasonic treatment and control evaporation in vacuum oven. The morphology, pore size distribution, thermal, electrochemical and mechanical properties of the PPEs were investigated. The porosity distribution of PPEs was uniform and their pore size was relatively modest. The total resistance (Rt) of PPEs with 10% Al2O3 is only 9 Ω at 80 °C. The maximum tensile strength of the PPEs membranes reached to 24.43 MPa. The results show that nano-Al2O3 can improve the comprehensive performance of PPEs without compromising their conductivity and diplayed the good application prospects of Al2O3-modified PPEs for lithium-ion batteries.

  12. Synthesis and Evaluation of Poly(3,4-ethylenedioxythiophene) (PEDOT) Coated Magnesium for Nerve Regeneration

    NASA Astrophysics Data System (ADS)

    Sebaa, Meriam Amel

    In an attempt to develop conductive, biodegradable, mechanically strong, and biocompatible nerve conduits, pure magnesium (Mg) was used as the biodegradable substrate material to provide strength while the conductive polymer, poly(3,4ethylenedioxythiophene) (PEDOT) was used as a conductive coating material to control Mg degradation and improve cytocompatibility of Mg substrates. A series of electrochemical deposition conditions were explored to produce a uniform, consistent PEDOT coating on Mg substrates. Five cycles of CV with the potential ranging from -0.5V to 2.0V were used to produce consistent coatings for further evaluation. Scanning electron micrographs showed the micro-porous structure of PEDOT coatings. Energy Dispersive X-ray Spectroscopy (EDS) showed the peaks of sulfur, oxygen, and carbon, indicating PEDOT coating. Adhesion strength of the coating was measured using ASTM-D 3359 standard tape test. The adhesion strength of PEDOT coating was within the classifications of 3B to 4B. Tafel tests of the PEDOT coated Mg showed a corrosion current (ICORR) of 6.14e-5A and critical voltage of -1.10V, as compared with ICORR of 9.08e-4A with a critical voltage of -1.35V for non-coated Mg. The calculated corrosion rate for the PEDOT coated Mg was 8.6 mm/year, much slower than 126.9mm/year for the non-coated Mg. H9 human embryonic stem cell (hESC) culture studies were conducted using magnesium (Mg) coated with a conductive polymer poly (3,4-ethylenedioxythiophene) (PEDOT) to study viability for potential neural applications. Stem cells cultured indirectly with the Mg coated with PEDOT for 2 cycles were viable for a about half the amount of time when compared with the stem cells cultured with the 5 cycle PEDOT coated Mg.

  13. Strip Coating Metrology on Large Scale Telescope Optics: Scalable Cost Saving Preventative Maintenance with First Contact Polymer

    NASA Astrophysics Data System (ADS)

    Hamilton, J.

    2012-09-01

    Protection and cleaning of precision optical surfaces on large scale astronomical instruments has entered a new era. First surface mirrors have been restored to "like-new" condition avoiding the expense and downtime of recoating. Nearly 10 years of testing and evaluation at a variety of sites including optics at Vandenberg Air Force Base, the Canada France Hawaii Telescope (CFHT) and the W.M Keck Telescope on Mauna Kea, have yielded impressive results: restored reflectivity, no residue, insitu cleaning and better coating performance when used as a precleaner when coating. Metrology and research in our labs has resulted in these novel, commercially available polymeric stripcoatings that are applied as a liquid and subsequently peeled off the substrate as a solid film. These designer polymer solutions safely clean and protect a wide variety of nanostructured surfaces and leave the surface almost atomically clean. Contaminant removal was monitored by a variety of techniques including Reflectivity, Nomarski, Atomic Force and Scanning Electron Microscopy as well as XPS. In addition, data demonstrates that the material safely removes particulate contamination and finger oils from nanostructures such as the 300nm wide lines on diffraction gratings and similar submicron features on Si wafers. High power laser damage testing found no residue on the optical surfaces following dried film removal and YAG laser damage thresholds after cleaning on coated BK7 of 15J/cm2 at 20ns and 20Hz were unchanged. Additionally to these adhesion tunable polymer systems, nanotube and graphene doped, ESD free polymer strip coatings for surface protection, nanoreplication, cleaning and dust mitigation have also been developed. Our coatings have been successfully used on diverse surfaces like high power laser optics, the Hope Diamond in Washington DC, CCD s for the 520 megapixel Dark Energy Survey Camera being built at Fermilab and lithographically fabbed detector surfaces for the Cryogenic Dark

  14. Biocorrosion and osteoconductivity of PCL/nHAp composite porous film-based coating of magnesium alloy

    NASA Astrophysics Data System (ADS)

    Abdal-hay, Abdalla; Amna, Touseef; Lim, Jae Kyoo

    2013-04-01

    The present study was aimed at designing a novel porous hydroxyapatite/poly(ɛ-caprolactone) (nHAp/PCL) hybrid nanocomposite matrix on a magnesium substrate with high and low porosity. The coated samples were prepared using a dip-coating technique in order to enhance the bioactivity and biocompatibility of the implant and to control the degradation rate of magnesium alloys. The mechanical and biocompatible properties of the coated and uncoated samples were investigated and an in vitro test for corrosion was conducted by electrochemical polarization and measurement of weight loss. The corrosion test results demonstrated that both the pristine PCL and nHAp/PCL composites showed good corrosion resistance in SBF. However, during the extended incubation time, the composite coatings exhibited more uniform and superior resistance to corrosion attack than pristine PCL, and were able to survive severe localized corrosion in physiological solution. Furthermore, the bioactivity of the composite film was determined by the rapid formation of uniform CaP nanoparticles on the sample surfaces during immersion in SBF. The mechanical integrity of the composite coatings displayed better performance (˜34% higher) than the uncoated samples. Finally, our results suggest that the nHAp incorporated with novel PCL composite membranes on magnesium substrates may serve as an excellent 3-D platform for cell attachment, proliferation, migration, and growth in bone tissue. This novel as-synthesized nHAp/PCL membrane on magnesium implants could be used as a potential material for orthopedic applications in the future.

  15. Engineering the bio-nano interface using a multi-functional polymer coating

    NASA Astrophysics Data System (ADS)

    Wang, Wentao

    Interfacing inorganic nanoparticles with biological systems to develop a variety of novel imaging, sensing and diagnostic tools has generated great interest and much activity over the past two decades. However, the effectiveness of this approach hinges on the ability to prepare water dispersible nanoparticles, with compact size and long term colloidal stability in biological environments, and the development of controlled conjugation to various biomolecules. The primary focus of this dissertation is the design and synthesis, characterization and use of a series of new multidentate and multifunctional coordinating polymers as ligands that render various inorganic nanocrystals water soluble, In Chapter 1 we introduce the basic physical properties of quantum dots (QDs), gold nanocrystals and magnetic nanocrystals along with brief description of their syntheses. We then provide an overview of surface functionalization strategies and recent progress in the ligand chemistry, followed by highlights of a few conjugation approaches applied to nanoparticles in biology. We then discuss modulation of the optical and spectroscopic properties of QDs via energy and charge transfer interactions. We conclude by presenting a few related examples on the incorporation of QD-conjugates into sensor design and intracellular imaging. In Chapter 2, we report the design of a series of multifunctional polymers as ligands for surface engineering of QDs and facilitating their use in bioconjugation. First, we introduce a novel PEGylated polymer that combines the synergies of metal-chelation promoted by lipoic acid and imidazole groups, as effective coating for the surface functionalization of QDs; one of the goals was to address the problems associated with thiol oxidation and weak imidazole affinity. Second, to minimize the hydrodynamic radius of the QDs without sacrificing aqueous solubility, a set of polymer ligands appended with zwitterion and imidazole motifs have been synthesized applied

  16. Electrohydrodynamics in nanochannels coated by mixed polymer brushes: effects of electric field strength and solvent quality

    NASA Astrophysics Data System (ADS)

    Cao, Qianqian; Tian, Xiu; You, Hao

    2018-04-01

    We examine the electrohydrodynamics in mixed polymer brush-coated nanochannels and the conformational dynamics of grafted polymers using molecular dynamics simulations. Charged (A) and neutral polymers (B) are alternately grafted on the channel surfaces. The effects of the electric field strength and solvent quality are addressed in detail. The dependence of electroosmotic flow characteristics and polymer conformational behavior on the solvent quality is influenced due to the change of the electric field strength. The enhanced electric field induces a collapse of the neutral polymer chains which adopt a highly extended conformation along the flow direction. However, the thickness of the charged polymer layer is affected weakly by the electric field, and even a slight swelling is identified for the A-B attraction case, implying the conformational coupling between two polymer species. Furthermore, the charged polymer chains incline entirely towards the electric field direction oppositely to the flow direction. More importantly, unlike the neutral polymer chains, the shape factor of the charged polymer chains, which is used to describe the overall shape of polymer chains, is reduced significantly with increasing the electric field strength, corresponding to a more coiled structure.

  17. Porous ionic liquids: synthesis and application.

    PubMed

    Zhang, Shiguo; Dokko, Kaoru; Watanabe, Masayoshi

    2015-07-15

    Solidification of fluidic ionic liquids into porous materials yields porous ionic networks that combine the unique characteristics of ionic liquids with the common features of polymers and porous materials. This minireview reports the most recent advances in the design of porous ionic liquids. A summary of the synthesis of ordered and disordered porous ionic liquid-based nanoparticles or membranes with or without templates is provided, together with the new concept of room temperature porous ionic liquids. As a versatile platform for functional materials, porous ionic liquids have shown widespread applications in catalysis, adsorption, sensing, actuation, etc. This new research direction towards ionic liquids chemistry is still in its early stages but has great potential.

  18. Functionalization of alkyne-terminated thermally hydrocarbonized porous silicon nanoparticles with targeting peptides and antifouling polymers: effect on the human plasma protein adsorption.

    PubMed

    Wang, Chang-Fang; Mäkilä, Ermei M; Bonduelle, Colin; Rytkönen, Jussi; Raula, Janne; Almeida, Sérgio; Närvänen, Ale; Salonen, Jarno J; Lecommandoux, Sebastien; Hirvonen, Jouni T; Santos, Hélder A

    2015-01-28

    Porous silicon (PSi) nanomaterials combine a high drug loading capacity and tunable surface chemistry with various surface modifications to meet the requirements for biomedical applications. In this work, alkyne-terminated thermally hydrocarbonized porous silicon (THCPSi) nanoparticles were fabricated and postmodified using five bioactive molecules (targeting peptides and antifouling polymers) via a single-step click chemistry to modulate the bioactivity of the THCPSi nanoparticles, such as enhancing the cellular uptake and reducing the plasma protein association. The size of the nanoparticles after modification was increased from 176 to 180-220 nm. Dextran 40 kDa modified THCPSi nanoparticles showed the highest stability in aqueous buffer. Both peptide- and polymer-functionalized THCPSi nanoparticles showed an extensive cellular uptake which was dependent on the functionalized moieties presented on the surface of the nanoparticles. The plasma protein adsorption study showed that the surface modification with different peptides or polymers induced different protein association profiles. Dextran 40 kDa functionalized THCPSi nanoparticles presented the least protein association. Overall, these results demonstrate that the "click" conjugation of the biomolecules onto the alkyne-terminated THCPSi nanoparticles is a versatile and simple approach to modulate the surface chemistry, which has high potential for biomedical applications.

  19. Theoretical voltammetric response of electrodes coated by solid polymer electrolyte membranes.

    PubMed

    Gómez-Marín, Ana M; Hernández-Ortíz, Juan P

    2014-09-24

    A model for the differential capacitance of metal electrodes coated by solid polymer electrolyte membranes, with acid/base groups attached to the membrane backbone, and in contact with an electrolyte solution is developed. With proper model parameters, the model is able to predict a limit response, given by Mott-Schottky or Gouy-Chapman-Stern theories depending on the dissociation degree and the density of ionizable acid/base groups. The model is also valid for other ionic membranes with proton donor/acceptor molecules as membrane counterions. Results are discussed in light of the electron transfer rate at membrane-coated electrodes for electrochemical reactions that strongly depend on the double layer structure. In this sense, the model provides a tool towards the understanding of the electro-catalytic activity on modified electrodes. It is shown that local maxima and minima in the differential capacitance as a function of the electrode potential may occur as consequence of the dissociation of acid/base molecular species, in absence of specific adsorption of immobile polymer anions on the electrode surface. Although the model extends the conceptual framework for the interpretation of cyclic voltammograms for these systems and the general theory about electrified interfaces, structural features of real systems are more complex and so, presented results only are qualitatively compared with experiments. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. Development of electroactive polymer nanocomposites with porous structured materials

    NASA Astrophysics Data System (ADS)

    Lopes, Ana Catarina Teixeira Castro

    Electroactive polymer composites are interesting materials for advance technological applications due to the possibility to combine the electroactive properties of the polymer matrix with a large variety of fillers that allow tailored responses for specific applications. The best all-around electroactive polymers are poly(vinylidene fluoride) (PVDF) and its copolymers which allied with the properties of porous zeolite materials, with tailored shape, size and Si/Al ratio, among others, leads to the possibility of development of promising PVDF/zeolite composites. In this way, a study of the structural, thermal and electrical properties of PVDF composites prepared with different framework zeolite types (LTL, LTA, FAU and MFI), different polymer solvents (DMF, DMSO, TEP) and different zeolite (NaY) concentrations (4, 16, 24 and 32 wt %) was performed. Further, the dielectric response, electrical conductivity and electric modulus of the composites were investigated as a function of NaYzeolite content. The zeolite influence on the electroactive gamma-phase crystallization of PVDF was explored, as well as the effect of clay layered structure (Montmorillonite, Kaolinite and Laponite) on the electroactive gamma-phase nucleation and on the optical transparency of the composite. It was found that the obtained composites showed an electrical response dependence on the pore structure and chemical content of the inorganic host. The dielectric response of the composites is directly related to the Si/Al ratio, leading zeolites with lower Si/Al ratios to larger dielectric responses and encapsulation efficiencies in the composites. It was also found that the zeolite content strongly influences the macroscopic response of dielectric response, which increases for increasing filler content. The dielectric constant at room temperature reaches values larger than 1000 for the 32 wt.% composite at 1 kHz what is mainly attributed to restricted ion mobility and interfacial polarization