21 CFR 175.270 - Poly(vinyl fluoride) resins.

Code of Federal Regulations, 2013 CFR

2013-04-01

... polymerization of vinyl fluoride. (b) The poly(vinyl fluoride) basic resins have an intrinsic viscosity of not... Dilute Solution Viscosity of Vinyl Chloride Polymers,” which is incorporated by reference. Copies may be... Solution Viscosity of Vinyl Chloride Polymers,” which is incorporated by reference; see paragraph (b) of...

21 CFR 175.270 - Poly(vinyl fluoride) resins.

Code of Federal Regulations, 2012 CFR

2012-04-01

... polymerization of vinyl fluoride. (b) The poly(vinyl fluoride) basic resins have an intrinsic viscosity of not... Dilute Solution Viscosity of Vinyl Chloride Polymers,” which is incorporated by reference. Copies may be... Solution Viscosity of Vinyl Chloride Polymers,” which is incorporated by reference; see paragraph (b) of...

Colloidal titration of aqueous zirconium solutions with poly(vinyl sulfate) by potentiometric endpoint detection using a toluidine blue selective electrode.

PubMed

Sakurada, Osamu; Kato, Yasutake; Kito, Noriyoshi; Kameyama, Keiichi; Hattori, Toshiaki; Hashiba, Minoru

2004-02-01

Zirconium oxy-salts were hydrolyzed to form positively charged polymer or cluster species in acidic solutions. The zirconium hydrolyzed polymer was found to react with a negatively charged polyelectrolyte, such as poly(vinyl sulfate), and to form a stoichiometric polyion complex. Thus, colloidal titration with poly(vinyl sulfate) was applied to measure the zirconium concentration in an acidic solution by using a Toluidine Blue selective plasticized poly(vinyl chloride) membrane electrode as a potentiometric end-point detecting device. The determination could be performed with 1% of the relative standard deviation. The colloidal titration stoichiometry at pH < or = 2 was one mol of zirconium per equivalent mol of poly(vinyl sulfate).

Preparation of Syndiotactic Poly(vinyl alcohol)/Poly(vinyl pivalate/vinyl acetate) Microspheres with Radiopacity Using Suspension Copolymerization and Saponification

NASA Astrophysics Data System (ADS)

Seok Lyoo, Won; Wook Cha, Jin; Young Kwak, Kun; Jae Lee, Young; Yong Jeon, Han; Sik Chung, Yong; Kyun Noh, Seok

2010-06-01

To prepare Poly(vinyl pivalate/vinyl acetate) [P(VPi/VAc)] microspheres with radiopacity, the suspension copolymerization approach in the presence of aqueous radiopaque nanoparticles was used. After, The P(VPi/VAc) microspheres with radiopacity were saponified in heterogeneous system, and then P(VPi/VAc) microspheres without aggregates were converted to s-PVA/P(VPi/VAc) microspheres of skin/core structure through the heterogeneous surface saponification. Radiopacity of microspheres was confirmed with Computed tomography (CT).

Nanocomposite materials based on poly(vinyl chloride) and bovine serum albumin modified ZnO through ultrasonic irradiation as a green technique: Optical, thermal, mechanical and morphological properties.

PubMed

Mallakpour, Shadpour; Darvishzadeh, Marzieh

2018-03-01

In this project, physicochemical properties of poly(vinyl chloride) (PVC) reinforced by ZnO nanoparticles (NPs) were studied. Firstly, ZnO NPs were modified with bovine serum albumin (BSA) as an organo-modifier and biocompatible substance through ultrasound irradiation as environmental friendly, low cost and rapid means. Nanocomposite (NC) films were prepared by loadings of various ratios of ZnO/BSA NPs (3, 6 and 9wt%) inside the PVC. Structural morphology and physical properties of the ZnO-BSA NPs and NC films were investigated via Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis (TGA), transmission electron microscopy and field emission scanning electron microscopy. According to the obtained information from the TGA, an increase in the thermal stability can be clearly observed. Also the results of contact angle analysis indicated with increasing percent of ZnO/BSA NPs into PVC the hydrophilic behaviors of NCs were increased. Copyright © 2017 Elsevier B.V. All rights reserved.

Poly(ionic liquids) functionalized polypyrrole/graphene oxide nanosheets for electrochemical sensor to detect dopamine in the presence of ascorbic acid.

PubMed

Mao, Hui; Liang, Jiachen; Zhang, Haifeng; Pei, Qi; Liu, Daliang; Wu, Shuyao; Zhang, Yu; Song, Xi-Ming

2015-08-15

Novel poly(ionic liquids) functionalized polypyrrole/graphene oxide nanosheets (PILs/PPy/GO) were prepared by the polymerization of 1-vinyl-3-ethylimidazole bromide (VEIB) on the surface of N-vinyl imidazolium modified PPy/GO nanosheets. Due to the synergistic effects of GO with well-defined lamellar structures, conductive PPy and biocompatible PILs, PILs/PPy/GO modified glassy carbon electrode (GCE) presented the excellent electrochemical catalytic activity towards dopamine (DA) with good stability, high sensitivity and wide linear range in the present of ascorbic acid (AA) with high concentration. PILs played an essential role for the simultaneous determination of DA and AA in a mixture, whose existence effectively improved the transmission mode of electrons and resulted in the different electrocatalytic performance towards the oxidation of DA and AA. It is indicated that PILs/PPy/GO nanosheets can act as a good steady and sensitive electrode material for the development of improved DA sensors. Copyright © 2015 Elsevier B.V. All rights reserved.

Lipogels: surface-adherent composite hydrogels assembled from poly(vinyl alcohol) and liposomes

NASA Astrophysics Data System (ADS)

Jensen, Bettina E. B.; Hosta-Rigau, Leticia; Spycher, Philipp R.; Reimhult, Erik; Städler, Brigitte; Zelikin, Alexander N.

2013-07-01

Drug-eluting engineered surface coatings are of paramount importance for many biomedical applications from implantable devices to tissue engineering. Herein, we present the assembly of lipogels, composite physical hydrogels assembled from poly(vinyl alcohol) and liposomes using thiol-disulfide exchange between end group modified PVA and thiocholesterol containing liposomes, and the response of adhering cells to these coatings. We demonstrate the controlled loading of liposomes into the polymer matrix and the preserved mechanical properties of the lipogels. Furthermore, the lipogels are successfully rendered cell adhesive by incorporation of poly(l-lysine) into the PVA polymer matrix or by poly(dopamine) coating of the lipogels. The successful lipid uptake from the lipogels by macrophages, hepatocytes, and myoblasts was monitored by flow cytometry. Finally, the delivery of active cargo, paclitaxel, to adherent myoblasts is shown, thus illustrating the potential of the lipogels as a drug eluting interface for biomedical applications.Drug-eluting engineered surface coatings are of paramount importance for many biomedical applications from implantable devices to tissue engineering. Herein, we present the assembly of lipogels, composite physical hydrogels assembled from poly(vinyl alcohol) and liposomes using thiol-disulfide exchange between end group modified PVA and thiocholesterol containing liposomes, and the response of adhering cells to these coatings. We demonstrate the controlled loading of liposomes into the polymer matrix and the preserved mechanical properties of the lipogels. Furthermore, the lipogels are successfully rendered cell adhesive by incorporation of poly(l-lysine) into the PVA polymer matrix or by poly(dopamine) coating of the lipogels. The successful lipid uptake from the lipogels by macrophages, hepatocytes, and myoblasts was monitored by flow cytometry. Finally, the delivery of active cargo, paclitaxel, to adherent myoblasts is shown, thus illustrating the potential of the lipogels as a drug eluting interface for biomedical applications. Electronic supplementary information (ESI) available: Paclitaxel calibration curve and images of DIC of PLL blended PVA physical hydrogels, lipogel FRAP, and different cell lines attached to lipogels are available. See DOI: 10.1039/c3nr01662e

Poly(1-Vinyl-1,2,4-triazolium) Poly(Ionic Liquid)s: Synthesis and the Unique Behavior in Loading Metal Ions.

PubMed

Zhang, Weiyi; Yuan, Jiayin

2016-07-01

Herein, the synthesis of a series of poly(4-alkyl-1-vinyl-1,2,4-triazolium) poly(ionic liquid)s is reported either via straightforward free radical polymerization of their corresponding ionic liquid monomers or via anion metathesis of the polymer precursors bearing halide as counter anion. The ionic liquid monomers are first prepared via N-alkylation reaction of commercially available 1-vinyl-1,2,4-triazole with alkyl iodides, followed by anion metathesis with targeted fluorinated anions. The thermal properties and solubilities of these poly(ionic liquid)s have been systematically investigated. Interestingly, it is found that the poly(4-ethyl-1-vinyl-1,2,4-triazolium) poly(ionic liquid) exhibited an improved loading capacity of transition metal ions in comparison with its imidazolium counterpart. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Complex Coacervate Core Micelles Containing Poly(vinyl alcohol) Inhibit Ice Recrystallization.

PubMed

Sproncken, Christian C M; Surís-Valls, Romà; Cingil, Hande E; Detrembleur, Christophe; Voets, Ilja K

2018-04-10

Complex coacervate core micelles (C3Ms) form upon complexation of oppositely charged copolymers. These co-assembled structures are widely investigated as promising building blocks for encapsulation, nanoparticle synthesis, multimodal imaging, and coating technology. Here, the impact on ice growth is investigated of C3Ms containing poly(vinyl alcohol), PVA, which is well known for its high ice recrystallization inhibition (IRI) activity. The PVA-based C3Ms are prepared upon co-assembly of poly(4-vinyl-N-methyl-pyridinium iodide) and poly(vinyl alcohol)-block-poly(acrylic acid). Their formation conditions, size, and performance as ice recrystallization inhibitors are studied. It is found that the C3Ms exhibit IRI activity at PVA monomer concentrations as low as 1 × 10 -3 m. The IRI efficacy of PVA-C3Ms is similar to that of linear PVA and PVA graft polymers, underlining the influence of vinyl alcohol monomer concentration rather than polymer architecture. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Influence of UV and Gamma radiations on the induced birefringence of stretched poly(vinyl) alcohol foils

NASA Astrophysics Data System (ADS)

Nechifor, Cristina-Delia; Zelinschi, Carmen Beatrice; Dorohoi, Dana-Ortansa

2014-03-01

The aim of our paper is to evidence the influence of Gamma and UV radiations on the induced birefringence of poly(vinyl alcohol) stretched foils. Thin foils of PVA were prepared and dried without modifying their surfaces. The polymeric foils were irradiated from 15 min to 6 h using UV and Gamma radiations. The induced by stretching under heating birefringence of PVA films was measured at λ = 589.3 nm with a Babinet Compensator. Physico-chemical processes (photo stabilization, photo degradation, oxidation) induced by irradiation of polymer matrix influence both the stretching degree and the anisotropy of etired foils. An increase of birefringence versus the stretching ratio of the PVA foils was evidenced for all studied samples. The dependence of the birefringence on the exposure time, stretching ratio and nature of radiation was also confirmed.

Poly(zwitterionic liquids) functionalized polypyrrole/graphene oxide nanosheets for electrochemically detecting dopamine at low concentration.

PubMed

Mao, Hui; Liang, Jiachen; Ji, Chunguang; Zhang, Haifeng; Pei, Qi; Zhang, Yuyang; Zhang, Yu; Hisaeda, Yoshio; Song, Xi-Ming

2016-08-01

Poly(3-(1-vinylimidazolium-3-yl)propane-1-sulfonate) (PVIPS), a novel kind of poly(zwitterionic liquids) (PZILs) containing both imidazolium cation and sulfonate anion, was successfully modified on the surface of polypyrrole/graphene oxide nanosheets (PPy/GO) by covalent bonding. The obtained novel PZILs functionalized PPy/GO nanosheets (PVIPS/PPy/GO) modified glassy carbon electrode (GCE) presented the excellent electrochemical catalytic activity towards dopamine (DA) with high stability, sensitivity, selectivity and wide linear range (40-1220nM), especially having a lower detection limit (17.3nM). The excellent analytical performance is attributed to the strongly negative charges on the surface of modified GCE in aqueous solution, which is different from conventional poly(ionic liquids) modified GCE. DA cations could be quickly enriched on the electrode surface by electrostatic interaction in solution due to the existence of SO3(-) groups with negative charge at the end of pendant groups in zwitterionic PVIPS, resulting in a change of the electrons transmission mode in the oxidation of DA, that is, from a typical diffusion-controlled process at conventional poly(1-vinyl-3-ethylimidazole bromide) (PVEIB)/PPy/GO modified GCE to a typical surface-controlled process. Copyright © 2016 Elsevier B.V. All rights reserved.

Fabrication of thermo-responsive cotton fabrics using poly(vinyl caprolactam-co-hydroxyethyl acrylamide) copolymer.

PubMed

Xiao, Min; González, Edurne; Monterroza, Alexis Martell; Frey, Margaret

2017-10-15

A thermo-responsive polymer with hydrophilic to hydrophobic transition behavior, poly(vinyl caprolactam-co-hydroxyethyl acrylamide) P(VCL-co-HEAA), was prepared by copolymerization of vinyl caprolactam and N-hydroxyethyl acrylamide via free radical solution polymerization. The resulting copolymer was characterized by Fourier transform infrared spectroscopy (FTIR), 1 H nuclear magnetic resonance (NMR), gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The lower critical solution temperature (LCST) of P(VCL-co-HEAA) was determined at 34.5°C. This thermo-responsive polymer was then grafted onto cotton fabrics using 1,2,3,4-butanetetracarboxylic acid (BTCA) as crosslinker and sodium hypophosphite (SHP) as catalyst. FTIR and energy dispersive X-ray spectroscopy (EDS) studies confirmed the successful grafting reaction. The modified cotton fabric exhibited thermo-responsive behavior as evidenced by water vapor permeability measurement confirming decreased permeability at elevated temperature. This is the first demonstration that a PVCL based copolymer is grafted to cotton fabrics. This study provides a new thermo-responsive polymer for fabrication of smart cotton fabrics with thermally switchable hydrophilicity. Copyright © 2017 Elsevier Ltd. All rights reserved.

21 CFR 177.2460 - Poly(2,6-dimethyl-1,4-phenylene) oxide resins.

Code of Federal Regulations, 2014 CFR

2014-04-01

...-phenylene) oxide basic resins meet the following: (1) Specifications. Intrinsic viscosity is not less than 0... Solution Viscosity of Vinyl Chloride Polymers,” which is incorporated by reference, modified as follows... reference in paragraph (c)(1) of this section) with the reduced viscosity determined for three concentration...

Urea photosynthesis inside polyelectrolyte capsules: effect of confined media.

PubMed

Shchukin, Dmitry G; Möhwald, Helmuth

2005-06-07

The influence of the restricted volume of poly(styrene sulfonate)/poly(allylamine hydrochloride) capsules of different size (2.2, 4.2, and 8.1 microm) on the TiO2-assisted photosynthesis of urea from inorganic precursors (CO2 and NO(3-)) in aqueous solution was demonstrated. Poly(vinyl alcohol) was employed as electron donor to facilitate the photosynthetic process. Decreasing the size of the confined microvolume of polyelectrolyte capsules accelerates the NO(3-) photoreduction, which is a limiting stage of the urea photosynthesis and, correspondingly, increases the efficiency of urea production. The highest yield of urea photosynthesis (37%) was achieved for Cu-modified TiO2 nanoparticles encapsulated inside 2.2 microm poly(styrene sulfonate)/poly(allylamine hydrochloride) capsules.

Properties of hot-melt extruded theophylline tablets containing poly(vinyl acetate).

PubMed

Zhang, F; McGinity, J W

2000-09-01

The objectives of this study were to investigate the properties of poly(vinyl acetate) (PVAc) as a retardant polymer and to study the drug release mechanism of theophylline from matrix tablets prepared by hot-melt extrusion. A physical mixture of drug, polymer, and drug release modifiers was fed into the equipment and heated inside the barrel of the extruder. The cylindrical extrudates were either cut into tablets or ground into granules and compressed with other excipients into tablets. Due to the low glass transition temperature of the PVAc, the melt extrusion process was conducted at approximately 70 degrees C. Theophylline was used as the model drug in this study. Theophylline was present in the extrudate in its crystalline form and was released from the tablets by diffusion. The Higuchi diffusion model and percolation theories were applied to the dissolution data to explain the drug release properties of the matrix systems. The release rate was shown to be dependent on the granule size, drug particle size, and drug loading in the tablets. Water-soluble polymers were demonstrated to be efficient release rate modifiers for this system.

Property tuning of poly(lactic acid)/cellulose bio-composites through blending with modified ethylene-vinyl acetate copolymer.

PubMed

Pracella, Mariano; Haque, Md Minhaz-Ul; Paci, Massimo; Alvarez, Vera

2016-02-10

The effect of addition of an ethylene-vinyl acetate copolymer modified with glycidyl methacrylate (EVA-GMA) on the structure and properties of poly(lactic acid) (PLA) composites with cellulose micro fibres (CF) was investigated. Binary (PLA/CF) and ternary (PLA/EVA-GMA/CF) composites obtained by melt mixing in Brabender mixer were analysed by SEM, POM, WAXS, DSC, TGA and tensile tests. The miscibility and morphology of PLA/EVA-GMA blends were first examined as a function of composition: a large rise of PLA spherulite growth rate in the blends was discovered with increasing the EVA-GMA content (0-30 wt%) in the isothermal crystallization both from the melt and the solid state. PLA/EVA-GMA/CF ternary composites displayed improved adhesion and dispersion of fibres into the matrix as compared to PLA/CF system. Marked changes of thermodynamic and tensile parameters, as elastic modulus, strength and elongation at break were observed for the composites, depending on blend composition, polymer miscibility and fibre-matrix chemical interactions at the interface. Copyright © 2015 Elsevier Ltd. All rights reserved.

Properties of electrospun pollock gelatin/poly(vinyl alcohol) and pollock gelatin/poly(lactic acid) fibers

USDA-ARS?s Scientific Manuscript database

Pollock gelatin/poly(vinyl alcohol) (PVA) fibers were electrospun using deionized water as the solvent and pollock gelatin/poly(lactic acid) (PLA) fibers were electrospun using 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) as the solvent. The chemical, thermal, and thermal stability properties were exami...

Influence of acrylonitrile butadiene rubber on recyclability of blends prepared from poly(vinyl chloride) and poly(methyl methacrylate).

PubMed

Suresh, Sunil S; Mohanty, Smita; Nayak, Sanjay K

2018-06-01

The current investigation deals with the recycling possibilities of poly(vinyl chloride) and poly(methyl methacrylate) in the presence of acrylonitrile butadiene rubber. Recycled blends of poly(vinyl chloride)/poly(methyl methacrylate) are successfully formed from the plastic constituents, those are recovered from waste computer products. However, lower impact performance of the blend and lower stability of the poly(vinyl chloride) phase in the recycled blend restricts its further usage in industrial purposes. Therefore, effective utilisation acrylonitrile butadiene rubber in a recycled blend was considered for improving mechanical and thermal performance. Incorporation of acrylonitrile butadiene rubber resulted in the improvement in impact performance as well as elongation-at-break of the recycled blend. The optimum impact performance was found in the blend with 9 wt% acrylonitrile butadiene rubber, which shows 363% of enhancement as compared with its parent blend. Moreover, incorporated acrylonitrile butadiene rubber also stabilises the poly(vinyl chloride) phase present in the recycled blend, similarly Fourier transform infrared spectroscopy studies indicate the interactions of various functionalities present in the recycled blend and acrylonitrile butadiene rubber. In addition to this, thermogravimetric analysis indicates the improvement in the thermal stability of the recycled blend after the addition of acrylonitrile butadiene rubber into it. The existence of partial miscibility in the recycled blend was identified using differential scanning calorimetry and scanning electron microscopy.

Poly(ethylene oxide) surfactant polymers.

PubMed

Vacheethasanee, Katanchalee; Wang, Shuwu; Qiu, Yongxing; Marchant, Roger E

2004-01-01

We report on a series of structurally well-defined surfactant polymers that undergo surface-induced self-assembly on hydrophobic biomaterial surfaces. The surfactant polymers consist of a poly(vinyl amine) backbone with poly(ethylene oxide) and hexanal pendant groups. The poly(vinyl amine) (PVAm) was synthesized by hydrolysis of poly(N-vinyl formamide) following free radical polymerization of N-vinyl formamide. Hexanal and aldehyde-terminated poly(ethylene oxide) (PEO) were simultaneously attached to PVAm via reductive amination. Surfactant polymers with different PEO:hexanal ratios and hydrophilic/hydrophobic balances were prepared, and characterized by FT-IR, 1H-NMR and XPS spectroscopies. Surface active properties at the air/water interface were determined by surface tension measurements. Surface activity at a solid surface/water interface was demonstrated by atomic force microscopy, showing epitaxially molecular alignment for surfactant polymers adsorbed on highly oriented pyrolytic graphite. The surfactant polymers described in this report can be adapted for simple non-covalent surface modification of biomaterials and hydrophobic surfaces to provide highly hydrated interfaces.

Poly(vinyl Chloride) Photostabilization in the Presence of Schiff Bases Containing a Thiadiazole Moiety.

PubMed

Shaalan, Naser; Laftah, Nawres; El-Hiti, Gamal A; Alotaibi, Mohammad Hayal; Muslih, Raad; Ahmed, Dina S; Yousif, Emad

2018-04-15

Five Schiff bases containing a thiadiazole moiety have been used as poly(vinyl chloride) photostabilizers at low concentrations. The efficiency of Schiff bases as photostabilizers was investigated using various techniques, for example, the changes in poly(vinyl chloride) infrared spectra, molecular weight, chain scission quantum yield, and surface morphology were monitored upon irradiation with an ultraviolet light. Evidently, all the additives used inhibited poly(vinyl chloride) photodegradation at a significant level. The most efficient Schiff base exhibited a high level of aromaticity and contained a hydroxyl group. It seems possible that such photostabilization could be due to the direct absorption of ultraviolet radiation by the additives. In addition, Schiff bases could act as radical scavengers and proton transfer facilitators to stabilize the polymeric materials.

Comparison of Chain Conformation of Poly(vinyl alcohol) in Solutions and Melts from Quantum Chemistry Based Molecular Dynamics Simulations

NASA Technical Reports Server (NTRS)

Jaffe, Richard; Han, Jie; Matsuda, Tsunetoshi; Yoon, Do; Langhoff, Stephen R. (Technical Monitor)

1997-01-01

Confirmations of 2,4-dihydroxypentane (DHP), a model molecule for poly(vinyl alcohol), have been studied by quantum chemistry (QC) calculations and molecular dynamics (MD) simulations. QC calculations at the 6-311G MP2 level show the meso tt conformer to be lowest in energy followed by the racemic tg, due to intramolecular hydrogen bond between the hydroxy groups. The Dreiding force field has been modified to reproduce the QC conformer energies for DHP. MD simulations using this force field have been carried out for DHP molecules in the gas phase, melt, and CHCl3 and water solutions. Extensive intramolecular hydrogen bonding is observed for the gas phase and CHCl3 solution, but not for the melt or aqueous solution, Such a condensed phase effect due to intermolecular interactions results in a drastic change in chain conformations, in agreement with experiments.

Selective Permeability of PVA Membranes. I: Radiation-Crosslinked Membranes

NASA Technical Reports Server (NTRS)

Katz, Moshe G.; Wydeven, Theodore, Jr.

1981-01-01

The water and salt transport properties of ionizing radiation crosslinked poly(vinyl alcohol) (PVA) membranes were investigated. The studied membranes showed high permeabilities and low selectivities for both water and salt. The results were found to be in accord with a modified solution-diffusion model for transport across the membranes, in which pressure-dependent permeability coefficients are employed.

Selective permeability of PVA membranes. I - Radiation-crosslinked membranes

NASA Technical Reports Server (NTRS)

Katz, M. G.; Wydeven, T., Jr.

1981-01-01

The water and salt transport properties of ionizing radiation crosslinked poly(vinyl alcohol) (PVA) membranes were investigated. The studied membranes showed high permeabilities and low selectivities for both water and salt. The results were found to be in accord with a modified solution-diffusion model for transport across the membranes, in which pressure-dependent permeability coefficients are employed.

A sustainable slashing industry using biodegradable sizes from modified soy protein to replace petro-based poly(vinyl alcohol).

PubMed

Zhao, Yi; Zhao, Yuzhu; Xu, Helan; Yang, Yiqi

2015-02-17

Biodegradable sizing agents from triethanolamine (TEA) modified soy protein could substitute poly(vinyl alcohol)(PVA) sizes for high-speed weaving of polyester and polyester/cotton yarns to substantially decrease environmental pollution and impel sustainability of textile industry. Nonbiodegradable PVA sizes are widely used and mainly contribute to high chemical oxygen demand (COD) in textile effluents. It has not been possible to effectively degrade, reuse or replace PVA sizes so far. Soy protein with good biodegradability showed potential as warp sizes in our previous studies. However, soy protein sizes lacked film flexibility and adhesion for required high-speed weaving. Additives with multiple hydroxyl groups, nonlinear molecule, and electric charge could physically modify secondary structure of soy protein and lead to about 23.6% and 43.3% improvement in size adhesion and ability of hair coverage comparing to unmodified soy protein. Industrial weaving results showed TEA-soy protein had relative weaving efficiency 3% and 10% higher than PVA and chemically modified starch sizes on polyester/cotton fabrics, and had relative weaving efficiency similar to PVA on polyester fabrics, although with 3- 6% lower add-on. In addition, TEA-soy sizes had a BOD5/COD ratio of 0.44, much higher than 0.03 for PVA, indicating that TEA-soy sizes were easily biodegradable in activated sludge.

Poly(vinyl chloride) catheters modified with pH-responsive poly(methacrylic acid) with affinity for antimicrobial agents

NASA Astrophysics Data System (ADS)

Zuñiga-Zamorano, Ivette; Meléndez-Ortiz, H. Iván; Costoya, Alejandro; Alvarez-Lorenzo, Carmen; Concheiro, Angel; Bucio, Emilio

2018-01-01

Radiation-grafting of pH-responsive methacrylic acid (MAA) onto poly(vinyl chloride) (PVC) was carried out by the pre-irradiation method using gamma rays, which demonstrated to be an efficient and fast procedure for obtaining PVC-g-MAA copolymers. The influence of preparation conditions, such as absorbed dose, monomer concentration, reaction time, and reaction temperature on the grafting yield was studied. The grafting of MAA onto PVC catheters was confirmed by means of Fourier transform infrared spectroscopy (FT-IR), thermogravimetry analysis (TGA), and differential scanning calorimetry (DSC). The pH-responsiveness of the grafted copolymers (critical point 8.5) was measured by swelling under cyclic changes in the pH of the medium. Interestingly, PVC-g-MAA showed enhanced capability to immobilize benzalkonium chloride and, particularly, ciprofloxacin and to sustain the release this antimicrobial agent at both acid and alkaline pH. Tests carried out with Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus point out that the developed functionalized catheters may play a role in the prevention/management of urinary tract infections.

Killing bacteria within biofilms by sustained release of tetracycline from triple-layered electrospun micro/nanofibre matrices of polycaprolactone and poly(ethylene-co-vinyl acetate).

PubMed

Alhusein, Nour; De Bank, Paul A; Blagbrough, Ian S; Bolhuis, Albert

2013-12-01

We report the controlled release of the antibiotic tetracycline (tet) HCl from a triple-layered electrospun matrix consisting of a central layer of poly(ethylene-co-vinyl acetate (PEVA) sandwiched between outer layers of poly-ε-caprolactone (PCL). These micro/nanofibre layers with tet successfully encapsulated (essentially quantitatively at 3 and 5 % w/w) in each layer, efficiently inhibited the growth of a panel of bacteria, including clinical isolates, as shown by a modified Kirby-Bauer disc assay. Furthermore, they demonstrated high biological activity in increasingly complex models of biofilm formation (models that are moving closer to the situation in a wound) by stopping biofilm formation, by killing preformed biofilms and killing mature, dense biofilm colonies of Staphylococcus aureus MRSA252. Tet is clinically useful with potential applications in wound healing and especially in complicated skin and skin-structure infections; electrospinning provides good encapsulation efficiency of tet within PCL/PEVA/PCL polymers in micro/nanofibre layers which display sustained antibiotic release in formulations that are anti-biofilm.

Employment of ultrasonic irradiation for production of poly(vinyl pyrrolidone)/modified alpha manganese dioxide nanocomposites: Morphology, thermal and optical characterization.

PubMed

Mallakpour, Shadpour; Abdolmaleki, Amir; Tabebordbar, Hashem

2018-03-01

This work explains the production, morphology, and features of novel nanocomposite (NC) established on poly(vinyl pyrrolidone) (PVP) as polymer background and modified alpha manganese dioxide (α-MnO 2 ) nanorod (NR) asan efficient filler. At first, one-dimensional α-MnO 2 nanorods (NRs) were produced by a hydrothermal technique and then they were amended with stearic acid (SA) by a solvothermal process. In following, the NCs were made by adding different volumes of α-MnO 2 -SA NR (1, 3 and 5wt%) in the PVP matrix through ultrasonic irradiation as a green, low-cost, fast, and useful technique. Structural and morphological descriptions confirm crystallinity of α-MnO 2 -SA NRs and showed that NRs have been separately dispersed in PVP matrix with rod-like morphology and diameter of about 40-60nm. The use of modifier and ultrasonic waves is accountable for good homogeneities of NRs. Thermogravimetric analysis revealed that thermal permanency of the obtained NCs has grown with increasing the α-MnO 2 -SA content. Also, the UV-vis absorption of NCs was enhanced with the incorporation of the modified α-MnO 2 NR in PVP matrix. The substantial perfections in NCs properties are associated to compatible intermolecular relations between the surface modifying groups of the α-MnO 2 -SA and PVP chain. Copyright © 2017 Elsevier B.V. All rights reserved.

Sonochemical synthesis of PVA/PVP blend nanocomposite containing modified CuO nanoparticles with vitamin B1 and their antibacterial activity against Staphylococcus aureus and Escherichia coli.

PubMed

Mallakpour, Shadpour; Mansourzadeh, Soheila

2018-05-01

The aim of this paper was to blend the polymers, poly(N-vinyl-2-pyrrolidone) (PVP) and poly(vinyl alcohol) (PVA) to produce a novel composite materials possessing the benefits of both. CuO nanoparticles (NPs) were used as a suitable filler to fabricate the blend nanocomposites (NCs) with desired properties. First, the surface of NPs, was modified with vitamin B 1 (VB 1 ) as a bio-safe coupling agent. Then, the blend NCs with various ratios of modified CuO (3, 5, and 7 wt%) were fabricated under ultrasonic irradiations followed by casting/solvent evaporation method. These processes are fast and green way to disperse the NPs sufficiently. Several techniques were applied for the characterization of the obtained NCs. morphology examination demonstrated the morphology of NCs and compatibility of NPs with the blend polymer. EDX results indicated the weight and atomic percentage of the achieved materials. TGA analysis verified that the NCs show higher thermal properties than the neat blend polymer. Also embedding the modified NPs into the blend polymer had effected on optical absorbance of the obtained NCs. The contact angle measurements confirmed that the hydrophilicity decreased for different proportions of the modified NPs loaded in the blend polymer. Finally, NCs show better bactericidal effects against gram-positive than gram-negative bacteria. Copyright © 2018 Elsevier B.V. All rights reserved.

Nanostructural surface engineering of grafted polymers on inorganic oxide substrates for membrane separations

NASA Astrophysics Data System (ADS)

Yoshida, Wayne Hiroshi

Nanostructural engineering of inorganic substrates by free radical graft polymerization was studied with the goal of developing new membrane materials for pervaporation. Graft polymerization consisted of modification of surface hydroxyls with vinyl trimethoxysilane, followed by solution graft polymerization reaction using either vinyl acetate (VAc) or vinyl pyrrolidone (VP). The topology of the modified surfaces was studied by atomic force microscopy (AFM) on both atomically smooth silicon wafer substrates and microporous inorganic membrane supports in order to deduce the effects of modification on the nanostructural properties of the membrane. While unmodified wafers showed a root-mean-square (RMS) surface roughness of 0.21 +/- 0.03 nm, roughness increased to 3.15 +/- 0.23 nm upon silylation. Under poor solvent conditions (i.e., air), surfaces modified with higher poly(vinyl acetate) (PVAc) or poly(vinyl pyrrolidone) (PVP) polymer graft yields displayed lateral inhomogeneities in the polymer layer. Although RMS surface roughness was nearly identical (0.81--0.85 nm) for PVAc-modified surfaces grafted at different monomer concentrations, the skewness of the height distribution decreased from 2.22 to 0.78 as polymer graft yield increased from 0.8 to 3.5 mg/m2. The polymer-modified surfaces were used to create inorganic pervaporation membranes consisting of a single macromolecular separation layer formed by graft polymerization. PVAc grafted silica membranes (500A native pore size) were found selective for MTBE in the separation of 0.1--1% (v/v) MTBE from water, achieving MTBE enrichment factors as high as 371 at a permeate flux of 0.38 l/m2 hr and a Reynolds number of 6390; however, these membranes could not separate anhydrous organic mixtures. Pervaporative separation of methanol/MTBE mixtures was possible with PVAc and PVP-modified alumina supports of 50A native pore size, where the separation layer consisted of grafted polymer chains with estimated radius of gyration 4.5--6.8 times larger than the membrane pore radius. Methanol separation factors for the PVP and PVAc-grafted alumina pervaporation membranes reached values of 26 and 100 (respectively) at total permeate fluxes of 0.055--1.26 kg/m 2 hr and 0.55--6.19 kg/m2 hr. The present study demonstrated that selective pervaporation membranes for separation of both organic/organic and organic/aqueous mixtures can be effectively designed by careful selection of the surface-grafted polymer chain density and the ratio of the polymer chain size to the native support pore size.

pH- and sugar-sensitive multilayer films composed of phenylboronic acid (PBA)-modified poly(allylamine hydrochloride) (PBA-PAH) and poly(vinyl alcohol) (PVA): A significant effect of PBA content on the film stability.

PubMed

Seno, Masaru; Yoshida, Kentaro; Sato, Katsuhiko; Anzai, Jun-ichi

2016-05-01

Multilayer thin films composed of phenylboronic acid (PBA)-modified poly(allylamine hydrochloride) (PAH), PBA-PAH, with different PBA contents were prepared to study the effect of PBA content on the stability of the films. An alternate deposition of PBA-PAH and poly(vinyl alcohol) (PVA) on the surface of a quartz slide afforded multilayer films through forming boronate ester bonds between PBA-PAH and PVA. The 10-layered (PBA-PAH/PVA)10 films constructed using PBA-PAHs containing 16% and 26% PBA residues were stable in aqueous solutions over the range of pH 4.0-10.0, whereas the multilayer films composed of PBA-PAHs with 5.9% and 8.3% PBA decomposed at pH 8.0 or lower. The pH-sensitive decomposition of the films was rationalized based on the destabilization of the boronate ester bonds in neutral and acidic solutions. In addition, the (PBA-PAH/PVA)10 films decomposed in glucose and fructose solutions as a result of competitive binding of sugars to PBA-PAH in the films. The sugar response of the films depended on the PBA content in PBA-PAH. The (PBA-PAH/PVA)10 films consisting of 16% and 26% PBA-substituted PBA-PAHs are sensitive to physiological relevant level of glucose at pH7.4 while stable in glucose-free solution, suggesting a potential use of the films in constructing glucose-induced delivery systems. Copyright © 2016 Elsevier B.V. All rights reserved.

Chemically imaging the effects of the addition of nanofibrillated cellulose on the distribution of poly(acrylic acid) in poly(vinyl alcohol)

Treesearch

Craig Clemons; Julia Sedlmair; Barbara Illman; Rebecca Ibach; Carol Hirschmugl

2013-01-01

The distribution of poly(acrylic acid) (PAA) in model laminates of nanocellulose and poly(vinyl alcohol) (PVOH) was investigated by FTIR chemical imaging. The method was effective in spatially discerning the three components of the composite. PAA can potentially improve the performance of nanocellulose reinforced PVOH by not only crosslinking the PVOH matrix but also...

Functional Degradable Polymers by Radical Ring-Opening Copolymerization of MDO and Vinyl Bromobutanoate: Synthesis, Degradability and Post-Polymerization Modification.

PubMed

Hedir, Guillaume G; Bell, Craig A; O'Reilly, Rachel K; Dove, Andrew P

2015-07-13

The synthesis of vinyl bromobutanoate (VBr), a new vinyl acetate monomer derivative obtained by the palladium-catalyzed vinyl exchange reaction between vinyl acetate (VAc) and 4-bromobutyric acid is reported. The homopolymerization of this new monomer using the RAFT/MADIX polymerization technique leads to the formation of novel well-defined and controlled polymers containing pendent bromine functional groups able to be modified via postpolymerization modification. Furthermore, the copolymerization of vinyl bromobutanoate with 2-methylene-1,3-dioxepane (MDO) was also performed to deliver a range of novel functional degradable copolymers, poly(MDO-co-VBr). The copolymer composition was shown to be able to be tuned to vary the amount of ester repeat units in the polymer backbone, and hence determine the degradability, while maintaining a control of the final copolymers' molar masses. The addition of functionalities via simple postpolymerization modifications such as azidation and the 1,3-dipolar cycloaddition of a PEG alkyne to an azide is also reported and proven by (1)H NMR spectroscopy, FTIR spectroscopy, and SEC analyses. These studies enable the formation of a novel class of hydrophilic functional degradable copolymers using versatile radical polymerization methods.

Improving amphiphilic polypropylenes by grafting poly(vinylpyrrolidone) and poly(ethylene glycol) methacrylate segments on a polypropylene microporous membrane

NASA Astrophysics Data System (ADS)

Chen, Huirong; Ma, Wenzhong; Xia, Yanping; Gu, Yi; Cao, Zheng; Liu, Chunlin; Yang, Haicun; Tao, Shengxi; Geng, Haoran; Tao, Guoliang; Matsuyama, Hideto

2017-10-01

An amphiphilic polypropylene-g-poly[vinylpyrrolidone-co-poly(ethylene glycol) methacrylate] (PP-g-(NVP-co-PEGMA)) modifier was prepared by melt grafting polymerization using N-vinyl pyrrolidone (NVP) as the grafting monomer and poly(ethylene glycol) (PEGMA) as the comonomer. Fourier transform infrared (FTIR) spectroscopy and elemental analysis showed that the hydrophilic branched chains (NVP-g-PEGMA) were successfully grafted to polypropylene (PP) macromolecular chains. The largest NVP grafting degree for PP-g-(NVP-co-PEGMA) (up to 20.4%) was obtained when the mass ratio of PP/NVP/PEGMA was 100/30/15. Hydrophilic PP microporous membranes were prepared by stretching cast films of PP/PP-g-(NVP-co-PEGMA) blends. The membrane thermostability (including the modifier) was better than that of the pure PP membrane with a similar surface pore structure. The porosity of the modified membranes was only slightly lower than that of the pure PP membranes. Contact angle measurements were used to examine the hydrophilicity of the membranes. The water contact angle of the membranes decreased when PP-g-(NVP-co-PEGMA) was added, and the minimum contact angle was 64.5°. Therefore, this work provides a good application for stretched hydrophilic PP membrane fabrication.

Enzymatic modification of natural and synthetic polymers using lipases and proteases

NASA Astrophysics Data System (ADS)

Chakraborty, Soma

Enzymatic modification of natural/synthetic polymers [starch nanoparticles, poly (n-alkyl acrylates) and poly(vinyl formamide)] was studied. Enzymes used for catalysis were lipases and proteases. Starch nanoparticles (40nm diameter) were incorporated into AOT-coated reverse micelles. Reactions performed with the acylating agents vinyl stearate, epsilon-caprolactone and maleic anhydride in toluene in presence of Novozyme-435 at 40°C for 36h gave products with degrees of substitution of 0.8, 0.6 and 0.4 respectively. DEPT-135 NMR spectra revealed that the modification occurred regioselectively at the C-6 position of the glucose units. Infrared microspectroscopy showed that the surfactant coated starch nanoparticles diffuse into pores of Novozyme-435 beads, coming in close proximity with CALB to promote modification. The modified products retained nanoscale dimensions. Catalysis of amide bond formation between a low molar mass amine and ester side groups of poly(n-alkyl acrylates)[poly(ethyl acrylate), poly(methyl acrylate) and poly(butyl acrylate)] was also examined. The nucleophiles were mono and diamines. Among the poly(n-alkyl acrylates) and the lipases studied, poly(ethyl acrylate) was the preferred substrate and Novozyme-435 the most active lipase. Poly(ethyl acrylate) in 80% by-volume toluene was reacted with 1 equivalent per repeat unit of hexyl amine at 70°C in presence of Novozyme-435. The product contained 10.6 mol% amide groups. Attempts to increase the amidation beyond 10--11 mol% by increasing the reaction time or use of fresh enzyme were unsuccessful, showing that poly(ethylacrylate-co-10mol%hexylacrylamide) is a poor substrate for further acylation. When chiral amines ([R,S]-alpha-methyl benzylamine, [R,S]-beta-methyl phenyl amine) were used as nucleophiles, Novozyme-435 enantioselectively catalyzed amidation of poly(ethyl acrylate). Poly(vinyl formamide), P(VfAm) by acid or base-catalyzed hydrolysis leads to poly(vinylamine), P(VAm), and corresponding copolymers. As an alternative to chemical hydrolysis a mild and selective enzymatic method was discovered. Fifteen proteases were evaluated for this transformation. Of these, PROT 7 was the most active. Within 24h PROT 7 gave products with 44% hydrolysis. Further hydrolysis was not observed by extending the reaction time because poly(vinylformamide-co-40%vinylamine) is a poor substrate for further hydrolysis. The sequence distribution of copolymers formed by chemical hydrolysis and enzymatic hydrolysis was compared. Chemical hydrolysis gave random copolymer. In contrast, PROT 7 gave block-like arrangement of VAm units.

Mechanical and interfacial properties of poly(vinyl chloride) based composites reinforced by cassava stillage residue with different surface treatments

NASA Astrophysics Data System (ADS)

Zhang, Yanjuan; Gan, Tao; Li, Qian; Su, Jianmei; Lin, Ye; Wei, Yongzuo; Huang, Zuqiang; Yang, Mei

2014-09-01

Cassava stillage residue (CSR), a kind of agro-industrial plant fiber, was modified by coupling agent (CA), mechanical activation (MA), and MA-assisted CA (MACA) surface treatments, respectively. The untreated and different surface treated CSRs were used to prepare plant fibers/polymer composites (PFPC) with poly(vinyl chloride) (PVC) as polymer matrix, and the properties of these CSR/PVC composites were compared. Surface treated CSR/PVC composites possessed better mechanical properties, water resistance and dimensional stability compared with the untreated CSR/PVC composite, attributing to the improvement of interfacial properties between CSR and PVC matrix. MACA-treated CSR was the best reinforcement among four types of CSRs (untreated, MA-treated, CA-treated, and MACA-treated CSRs) because MACA treatment led to the significant improvement of dispersion, interfacial adhesion and compatibility between CSR and PVC. MACA treatment could be considered as an effective and green method for enhancing reinforcement efficiency of plant fibers and the properties of PFPC.

Poly(methyl vinyl ether-alt-maleic acid)-functionalized porous silicon nanoparticles for enhanced stability and cellular internalization.

PubMed

Shahbazi, Mohammad-Ali; Almeida, Patrick V; Mäkilä, Ermei; Correia, Alexandra; Ferreira, Mónica P A; Kaasalainen, Martti; Salonen, Jarno; Hirvonen, Jouni; Santos, Hélder A

2014-03-01

Currently, developing a stable nanocarrier with high cellular internalization and low toxicity is a key bottleneck in nanomedicine. Here, we have developed a successful method to covalently conjugate poly(methyl vinyl ether-co-maleic acid) (PMVE-MA) copolymer on the surface of (3-aminopropyl)triethoxysilane-functionalized thermally carbonized porous silicon nanoparticles (APSTCPSi NPs), forming a surface negatively charged nanovehicle with unique properties. This polymer conjugated NPs could modify surface smoothness, charge, and hydrophilicity of the developed NPs, leading to considerable improvement in the colloidal and plasma stabilities via enhanced suspensibility and charge repulsion. Furthermore, despite the surface negative charge of the polymer-conjugated NPs, the cellular internalization was increased in both MDA-MB-231 and MCF-7 breast cancer cells. These results provide a proof-of-concept evidence that such polymer-based PSi nanocomposite can be extensively used as a promising candidate for intracellular drug delivery. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nanosized insulin-complexes based on biodegradable amine-modified graft polyesters poly[vinyl-3-(diethylamino)-propylcarbamate-co-(vinyl acetate)-co-(vinyl alcohol)]-graft-poly(L-lactic acid): protection against enzymatic degradation, interaction with Caco-2 cell monolayers, peptide transport and cytotoxicity.

PubMed

Simon, Michael; Behrens, Isabel; Dailey, Lea Anne; Wittmar, Matthias; Kissel, Thomas

2007-05-01

Non-parenteral insulin delivery by the oral route is limited by epithelial barriers and enzymatic degradation. Nanosized insulin-complexes based on amine modified comb-like polyesters were designed to overcome these barriers. Protection of insulin in nanocomplexes (NC) from enzymatic degradation was investigated. The interaction with enterocyte-like Caco-2 cells in terms of cytotoxicity, transport through and uptake in the cell layers was evaluated by measuring transepithelial electrical resistance (TEER), release of lactate dehydrogenase (LDH) and insulin transport. The protection capacity of NC and their interaction with Caco-2 cells varied strongly as a function of lactide-grafting (hydrophobicity). With increasing lactide-grafting (P(26) < or = P(26)-1(LL) < or = P(26)-2(LL)) NC protected up to 95% of the insulin against degradation by trypsin. Transport and uptake into cell monolayers increased with higher l-lactid grafting. About 25% of a 1.25mg/ml TRITC-insulin NC dispersion with P(26)-2(LL) was recovered in Caco-2 cells after 90 min. A concentration dependent cytotoxicity profile was observed showing elevated LDH release and decreased TEER values. The cytotoxicity correlates with the surfactant like character of the polymers, decreasing the surface tension to 46 mN/m for the amphiphilic P(26)-2(LL). The observed TEER decrease was reversible after 20 h, suggesting that the biodegradable comb-polyesters offer a promising approach to overcome mucosal barriers.

ESEM analysis of polymeric film in EVA-modified cement paste

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

Silva, D.A.; Monteiro, P.J.M.

2005-10-01

Portland cement pastes modified by 20% weight (polymer/cement ratio) of poly(ethylene-co-vinyl acetate) (EVA) were prepared, cured, and immersed in water for 11 days. The effects of water saturation and drying on the EVA polymeric film formed in cement pastes were observed using environmental scanning electron microscopy (ESEM). This technique allowed the imaging of the EVA film even in saturated samples. The decrease of the relative humidity inside the ESEM chamber did not cause any visual modification of the polymeric film during its drying.

A reduction of diffusion in PVA Fricke hydrogels

NASA Astrophysics Data System (ADS)

Smith, S. T.; Masters, K. S.; Hosokawa, K.; Blinco, J.; Crowe, S. B.; Kairn, T.; Trapp, J. V.

2015-01-01

A modification to the PVA-FX hydrogel whereby the chelating agent, xylenol orange, was partially bonded to the gelling agent, poly-vinyl alcohol, resulted in an 8% reduction in the post irradiation Fe3+ diffusion, adding approximately 1 hour to the useful timespan between irradiation and readout. This xylenol orange functionalised poly-vinyl alcohol hydrogel had an OD dose sensitivity of 0.014 Gy-1 and a diffusion rate of 0.133 mm2 h-1. As this partial bond yields only incremental improvement, it is proposed that more efficient methods of bonding xylenol orange to poly-vinyl alcohol be investigated to further reduce the diffusion in Fricke gels.

Electrospun nanofibers of poly(vinyl alcohol)reinforced with cellulose nanofibrils

USDA-ARS?s Scientific Manuscript database

In this work, nanofibers of poly(vinyl alcohol) (PVA) reinforced with cellulose nanofibrils (CnF) were produced by electrospinning. The effects of applied voltage, polymer concentration and injection rate, tip-to-collector distance (TCD), rotation speed of the collector, and relative humidity on mor...

Microstructure and molecular interaction in glycerol plasticized chitosan/poly(vinyl alcohol) blending films

USDA-ARS?s Scientific Manuscript database

Poly (vinyl alcohol) (PVA)/chitosan (CS) blended films plasticized by glycerol were investigated using mechanical testing, atomic force microscopy (AFM), differential scanning calorimetry (DSC) and FTIR spectroscopy, with primary emphasis on the effects of the glycerol content and the molecular weig...

Self-Healing Proton-Exchange Membranes Composed of Nafion-Poly(vinyl alcohol) Complexes for Durable Direct Methanol Fuel Cells.

PubMed

Li, Yixuan; Liang, Liang; Liu, Changpeng; Li, Yang; Xing, Wei; Sun, Junqi

2018-04-30

Proton-exchange membranes (PEMs) that can heal mechanical damage to restore original functions are important for the fabrication of durable and reliable direct methanol fuel cells (DMFCs). The fabrication of healable PEMs that exhibit satisfactory mechanical stability, enhanced proton conductivity, and suppressed methanol permeability via hydrogen-bonding complexation between Nafion and poly(vinyl alcohol) (PVA) followed by postmodification with 4-carboxybenzaldehyde (CBA) molecules is presented. Compared with pure Nafion, the CBA/Nafion-PVA membranes exhibit enhanced mechanical properties with an ultimate tensile strength of ≈20.3 MPa and strain of ≈380%. The CBA/Nafion-PVA membrane shows a proton conductivity of 0.11 S cm -1 at 80 °C, which is 1.2-fold higher than that of a Nafion membrane. The incorporated PVA gives the CBA/Nafion-PVA membranes excellent proton conductivity and methanol resistance. The resulting CBA/Nafion-PVA membranes are capable of healing mechanical damage of several tens of micrometers in size and restoring their original proton conductivity and methanol resistance under the working conditions of DMFCs. The healing property originates from the reversibility of hydrogen-bonding interactions between Nafion and CBA-modified PVA and the high chain mobility of Nafion and CBA-modified PVA. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Preparation and characterization of magnetic allylamine modified graphene oxide-poly(vinyl acetate-co-divinylbenzene) nanocomposite for vortex assisted magnetic solid phase extraction of some metal ions.

PubMed

Khan, Mansoor; Yilmaz, Erkan; Sevinc, Basak; Sahmetlioglu, Ertugrul; Shah, Jasmin; Jan, Muhammad Rasul; Soylak, Mustafa

2016-01-01

Magnetic allylamine modified graphene oxide-poly(vinyl acetate-co-divinylbenzene) (MGO-DVB-VA) was synthesized and used for magnetic solid phase extraction of Pb(II), Cd(II), Cu(II), Ni(II) and Co(II) prior to their determination by flame atomic absorption spectroscopy. The adsorbent surface functional group was characterized by using FT-IR and Raman spectroscopy. XRD pattern was used to determine the layers of GO. Surface morphology and elemental composition of the adsorbent were evaluated by using SEM and EDX analysis. Various parameters, effecting adsorption efficiency like initial solution pH, adsorbent dose, type and volume of eluent, volume of sample and diverse ions effects were optimized. The preconcentration factor (PF) is 40 for all the metals and the limits of detection for Pb, Cd, Cu, Ni and Co are in the range of 0.37-2.39 µg L(-1) and relative standard deviation below 3.1%. The method was validated by using the method for certified reference materials (Tobacco Leaves (INCT-OBTL-5), Tomato Leaves (1573a), Certified Water (SPS-ww2) and Certified Water (TMDA 64-2)). The method was successfully applied for natural water and food samples. Copyright © 2015 Elsevier B.V. All rights reserved.

Facile fabrication of gold nanoparticles-poly(vinyl alcohol) electrospun water-stable nanofibrous mats: efficient substrate materials for biosensors.

PubMed

Wang, Juan; Yao, Hong-Bin; He, Dian; Zhang, Chuan-Ling; Yu, Shu-Hong

2012-04-01

Electrospun nanofibrous mats are intensively studied as efficient scaffold materials applied in the fields of tissue engineering, catalysis, and biosensors due to their flexibility and porosity. In this paper, we report a facile route to fabricate gold nanoparticles-poly(vinyl alcohol) (Au NPs-PVA) hybrid water stable nanofibrous mats with tunable densities of Au NPs and further demonstrate the potential application of as-prepared Au NPs-PVA nanofibrous mats as efficient biosensor substrate materials. First, through the designed in situ cross-linkage in coelectrospun PVA-glutaraldehyde nanofibers, water insoluble PVA nanofibrous mats with suitable tensile strength were successfully prepared. Then, 3-mercaptopropyltrimethoxysilane (MPTES) was modified on the surface of obtained PVA nanofibrous films, which triggered successful homogeneous decoration of Au NPs through gold-sulfur bonding interactions. Finally, the Au NPs-PVA nanofibrous mats embedded with horseradish peroxidase (HRP) by electrostatic interactions were used as biosensor substrate materials for H(2)O(2) detection. The fabricated HRP-Au NPs/PVA biosensor showed a highly sensitive detection of H(2)O(2) with a detection limit of 0.5 μM at a signal-to-noise ratio of 3. By modifying other different functional nanaoparticles or enzyme on the PVA nanofibrous film will further expand their potential applications as substrate materials of different biosensors.

Ultrasonic-assisted synthesis of novel nanocomposite of poly(vinyl alcohol) and amino-modified MCM-41: A green adsorbent for Cd(II) removal.

PubMed

Soltani, Roozbeh; Dinari, Mohammad; Mohammadnezhad, Gholamhossein

2018-01-01

Amino-modified MCM-41/poly(vinyl alcohol) nanocomposite (M-MCM-41/PVOH NC) was developed for the adsorption of Cd(II) from aqueous media. M-MCM-41/PVOH NC was prepared through ultrasonic-assisted and simple blending procedure with economical and environmentally friendly polymer. The as-prepared adsorbent was characterized by FT-IR, TEM, FE-SEM and TGA. The contact time, solution pH and initial concentration of Cd(II) were found to affect the adsorption of Cd(II) from aqueous media. Kinetic studies were carried out and pseudo-first-order (PFO), pseudo-second-order (PSO), Elovich, and intra-particle diffusion (IPD) reaction kinetic models were examined. The kinetic results revealed that the adsorption of Cd(II) onto M-MCM-41/PVOH NC followed PSO kinetic model and is a chemical adsorption. The equilibrium adsorption data were evaluated by different isotherms viz. Langmuir, Freundlich, and Dubinin Radushkevich (D-R) equations. The equilibrium data fitted better with the Langmuir isotherm and the maximum adsorption capacity of M-MCM-41/PVOH NC at 298K was calculated to be 46.73mgg -1 for Cd(II) on a typical saturated monomolecular layer with a fixed number of localized adsorption sites. Copyright © 2017 Elsevier B.V. All rights reserved.

Poly(vinyl alcohol) composite films with high percent elongation prepared from amylose-fatty ammonium salt inclusion complexes

USDA-ARS?s Scientific Manuscript database

Amylose inclusion complexes prepared from cationic fatty ammonium salts and jet-cooked high amylose starch were combined with poly(vinyl alcohol) (PVOH) to form glycerol-plasticized films. Their tensile properties were compared with similar films prepared previously with analogous anionic fatty acid...

POLY(VINYL ACETATE) AND POLY(VINYL ACETATE-CO-ETHYLENE) LATEXES VIA DISPERSION POLYMERIZATIONS IN CARBON DIOXIDE. (R826115)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

The Inhibition of Aluminum Corrosion in Sulfuric Acid by Poly(1-vinyl-3-alkyl-imidazolium Hexafluorophosphate).

PubMed

Arellanes-Lozada, Paulina; Olivares-Xometl, Octavio; Guzmán-Lucero, Diego; Likhanova, Natalya V; Domínguez-Aguilar, Marco A; Lijanova, Irina V; Arce-Estrada, Elsa

2014-08-07

Compounds of poly(ionic liquid)s (PILs), derived from imidazole with different alkylic chain lengths located in the third position of the imidazolium ring (poly(1-vinyl-3-dodecyl-imidazolium) (PImC 12 ), poly(1-vinyl-3-octylimidazolium) (PImC₈) and poly(1-vinyl-3-butylimidazolium) (PImC₄) hexafluorophosphate) were synthesized. These compounds were tested as corrosion inhibitors on aluminum alloy AA6061 in diluted sulfuric acid (0.1-1 M H₂SO₄) by weight loss tests, polarization resistance measurements and inductively coupled plasma optical emission spectroscopy. Langmuir's isotherms suggested film formation on bare alloy while standard free energy indicated inhibition by a physisorption process. However, compound efficiencies as inhibitors ranked low (PImC 12 > PImC₈ > PImC₄) to reach 61% for PImC 12 in highly diluted acidic solution. Apparently, the high mobility of sulfates favored their adsorption in comparison to PILs. The surface film displayed general corrosion, and pitting occurred as a consequence of PILs' partial inhibition along with a continuous dissolution of defective patchy film on formation. A slight improvement in efficiency was displayed by compounds having high molecular weight and a long alkyl chain, as a consequence of steric hindrance and PIL interactions.

Influence of Block Copolymerization on the Antifreeze Protein Mimetic Ice Recrystallization Inhibition Activity of Poly(vinyl alcohol).

PubMed

Congdon, Thomas R; Notman, Rebecca; Gibson, Matthew I

2016-09-12

Antifreeze (glyco) proteins are produced by many cold-acclimatized species to enable them to survive subzero temperatures. These proteins have multiple macroscopic effects on ice crystal growth which makes them appealing for low-temperature applications-from cellular cryopreservation to food storage. Poly(vinyl alcohol) has remarkable ice recrystallization inhibition activity, but its mode of action is uncertain as is the extent at which it can be incorporated into other high-order structures. Here the synthesis and characterization of well-defined block copolymers containing poly(vinyl alcohol) and poly(vinylpyrrolidone) by RAFT/MADIX polymerization is reported, as new antifreeze protein mimetics. The effect of adding a large second hydrophilic block is studied across a range of compositions, and it is found to be a passive component in ice recrystallization inhibition assays, enabling retention of all activity. In the extreme case, a block copolymer with only 10% poly(vinyl alcohol) was found to retain all activity, where statistical copolymers of PVA lose all activity with very minor changes to composition. These findings present a new method to increase the complexity of antifreeze protein mimetic materials, while retaining activity, and also to help understand the underlying mechanisms of action.

Influence of Block Copolymerization on the Antifreeze Protein Mimetic Ice Recrystallization Inhibition Activity of Poly(vinyl alcohol)

PubMed Central

2016-01-01

Antifreeze (glyco) proteins are produced by many cold-acclimatized species to enable them to survive subzero temperatures. These proteins have multiple macroscopic effects on ice crystal growth which makes them appealing for low-temperature applications—from cellular cryopreservation to food storage. Poly(vinyl alcohol) has remarkable ice recrystallization inhibition activity, but its mode of action is uncertain as is the extent at which it can be incorporated into other high-order structures. Here the synthesis and characterization of well-defined block copolymers containing poly(vinyl alcohol) and poly(vinylpyrrolidone) by RAFT/MADIX polymerization is reported, as new antifreeze protein mimetics. The effect of adding a large second hydrophilic block is studied across a range of compositions, and it is found to be a passive component in ice recrystallization inhibition assays, enabling retention of all activity. In the extreme case, a block copolymer with only 10% poly(vinyl alcohol) was found to retain all activity, where statistical copolymers of PVA lose all activity with very minor changes to composition. These findings present a new method to increase the complexity of antifreeze protein mimetic materials, while retaining activity, and also to help understand the underlying mechanisms of action. PMID:27476873

Novel "anchor modification" of polymeric biomaterial surfaces by the utilization of cyclodextrin inclusion complex supramolecules.

PubMed

Zhao, Xiaobin; Courtney, James M

2009-07-01

In this article, a novel approach for the surface modification of polymeric biomaterials by the utilization of supramolecules was studied. The supramolecules selected were cyclodextrin inclusion complexes (CICs). The biomaterial selected for surface modification was plasticized poly (vinyl chloride) (PVC-P). Results indicate that when the CICs were blended into PVC-P, they tend to migrate and "anchor" on the surface to achieve a remarkable protein-resistant surface, with improved blood compatibility. In comparison with a physical mixture of cyclodextrins and a "guest" molecule, such as poly(ethylene oxide) (PEO)-poly(propylene oxide) (PPO)-PEO and PPO-PEO-PPO for PVC-P modification, CICs modified PVC-P are more consistent in processing and achieve reproducible surface characteristics. Based on this study, a novel "anchor modification" was proposed regarding CICs modified surface. This "anchor modification" is likely to reduce plasticizer extraction from PVC-P and also can be utilized for the modification of polymers other than PVC-P.

Ion exchange polymers and method for making

NASA Technical Reports Server (NTRS)

Philipp, Warren H. (Inventor); Street, Kenneth W., Jr. (Inventor)

1994-01-01

An ion exchange polymer comprised of an alkali metal or alkaline earth metal salt of a poly(carboxylic acid) in a poly(vinyl acetal) matrix is described. The polymer is made by treating a mixture made of poly(vinyl alcohol) and poly(acrylic acid) with a suitable aldehyde and an acid catalyst to cause acetalization with some cross-linking. The material is then subjected to an alkaline aqueous solution of an alkali metal salt or an alkali earth metal salt. All of the film forming and cross-linking steps can be carried out simultaneously, if desired.

Nanostructured composite layers for electromagnetic shielding in the GHz frequency range

NASA Astrophysics Data System (ADS)

Suchea, M.; Tudose, I. V.; Tzagkarakis, G.; Kenanakis, G.; Katharakis, M.; Drakakis, E.; Koudoumas, E.

2015-10-01

We report on preliminary results regarding the applicability of nanostructured composite layers for electromagnetic shielding in the frequency range of 4-20 GHz. Various combinations of materials were employed including poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS), polyaniline, graphene nanoplatelets, carbon nanotubes, Cu nanoparticles and Poly(vinyl alcohol). As shown, paint-like nanocomposite layers consisting of graphene nanoplatelets, polyaniline PEDOT:PSS and Poly(vinyl alcohol) can offer quite effective electromagnetic shielding, similar or even better than that of commercial products, the response strongly depending on their thickness and resistivity.

Poly(vinyl alcohol)/cellulose nanofibril hybrid aerogels with an aligned microtubular porous structure and their composites with polydimethylsiloxane

Treesearch

Tianliang Zhai; Qifeng Zheng; Zhiyong Cai; Lih-Sheng Turng; Hesheng Xia; Shaoqin Gong

2015-01-01

Superhydrophobic poly(vinyl alcohol) (PVA)/ cellulose nanofibril (CNF) aerogels with a unidirectionally aligned microtubular porous structure were prepared using a unidirectional freeze-drying process, followed by the thermal chemical vapor deposition of methyltrichlorosilane. The silanized aerogels were characterized using various techniques including scanning...

MICROWAVE-ASSISTED SYNTHESIS OF CROSSLINKED POLY(VINYL ALCOHOL) NANOCOMPOSITES COMPRISING SINGLE-WALLED CARBON NANOTUBES, MULTI-WALLED CARBON NANOTUBES AND BUCKMINSTERFULLERENE

EPA Science Inventory

We report a facile method to accomplish cross-linking reaction of poly (vinyl alcohol) (PVA) with single-wall carbon nanotubes (SWNT), multi-wall carbon nanotubes (MWNT), and Buckminsterfullerene (C-60) using microwave (MW) irradiation. Nanocomposites of PVA cross-linked with SW...

NOVEL METALLIC AND BIMETALLIC CROSS-LINKED POLY (VINYL ALCOHOL) NANOCOMPOSITES PREPARED UNDER MICROWAVE IRRADIATION

EPA Science Inventory

A facile microwave irradiation approach that results in a cross-linking reaction of poly (vinyl alcohol) (PVA) with metallic and bimetallic systems is described. Nanocomposites of PVA cross-linked metallic systems such as Pt, Cu, and In and bimetallic systems such as Pt-In, Ag-P...

21 CFR 175.270 - Poly(vinyl fluoride) resins.

Code of Federal Regulations, 2014 CFR

2014-04-01

...(vinyl fluoride) basic resins have an intrinsic viscosity of not less than 0.75 deciliter per gram as determined by ASTM method D1243-79, “Standard Test Method for Dilute Solution Viscosity of Vinyl Chloride... (ASTM method D1243-79, “Standard Test Method for Dilute Solution Viscosity of Vinyl Chloride Polymers...

Improvement of Polylactide Properties through Cellulose Nanocrystals Embedded in Poly(Vinyl Alcohol) Electrospun Nanofibers.

PubMed

López de Dicastillo, Carol; Garrido, Luan; Alvarado, Nancy; Romero, Julio; Palma, Juan Luis; Galotto, Maria Jose

2017-05-11

Electrospun nanofibers of poly (vinyl alcohol) (PV) were obtained to improve dispersion of cellulose nanocrystals (CNC) within hydrophobic biopolymeric matrices, such as poly(lactic acid) (PLA). Electrospun nanofibers (PV/CNC) n were successfully obtained with a final concentration of 23% ( w / w ) of CNC. Morphological, structural and thermal properties of developed CNC and electrospun nanofibers were characterized. X-ray diffraction and thermal analysis revealed that the crystallinity of PV was reduced by the electrospinning process, and the incorporation of CNC increased the thermal stability of biodegradable nanofibers. Interactions between CNC and PV polymer also enhanced the thermal stability of CNC and improved the dispersion of CNC within the PLA matrix. PLA materials with CNC lyophilized were also casted in order to compare the properties with materials based on CNC containing nanofibers. Nanofibers and CNC were incorporated into PLA at three concentrations: 0.5%, 1% and 3% (CNC respect to polymer weight) and nanocomposites were fully characterized. Overall, nanofibers containing CNC positively modified the physical properties of PLA materials, such as the crystallinity degree of PLA which was greatly enhanced. Specifically, materials with 1% nanofiber 1PLA(PV/CNC) n presented highest improvements related to mechanical and barrier properties; elongation at break was enhanced almost four times and the permeation of oxygen was reduced by approximately 30%.

The Inhibition of Aluminum Corrosion in Sulfuric Acid by Poly(1-vinyl-3-alkyl-imidazolium Hexafluorophosphate)

PubMed Central

Arellanes-Lozada, Paulina; Olivares-Xometl, Octavio; Guzmán-Lucero, Diego; Likhanova, Natalya V.; Domínguez-Aguilar, Marco A.; Lijanova, Irina V.; Arce-Estrada, Elsa

2014-01-01

Compounds of poly(ionic liquid)s (PILs), derived from imidazole with different alkylic chain lengths located in the third position of the imidazolium ring (poly(1-vinyl-3-dodecyl-imidazolium) (PImC12), poly(1-vinyl-3-octylimidazolium) (PImC8) and poly(1-vinyl-3-butylimidazolium) (PImC4) hexafluorophosphate) were synthesized. These compounds were tested as corrosion inhibitors on aluminum alloy AA6061 in diluted sulfuric acid (0.1–1 M H2SO4) by weight loss tests, polarization resistance measurements and inductively coupled plasma optical emission spectroscopy. Langmuir’s isotherms suggested film formation on bare alloy while standard free energy indicated inhibition by a physisorption process. However, compound efficiencies as inhibitors ranked low (PImC12 > PImC8 > PImC4) to reach 61% for PImC12 in highly diluted acidic solution. Apparently, the high mobility of sulfates favored their adsorption in comparison to PILs. The surface film displayed general corrosion, and pitting occurred as a consequence of PILs’ partial inhibition along with a continuous dissolution of defective patchy film on formation. A slight improvement in efficiency was displayed by compounds having high molecular weight and a long alkyl chain, as a consequence of steric hindrance and PIL interactions. PMID:28788156

Synthesis and application of a novel environmental C26 diglycidyl ester plasticizer based on castor oil for poly(vinyl chloride)

USDA-ARS?s Scientific Manuscript database

In this work, for the first time, a castor oil derived diglycidyl ester plasticizer (C26-DGE) was prepared and incorporated into poly(vinyl chloride) (PVC). The chemical structure of the product was characterized by Fourier transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance (...

Films prepared from poly(vinyl alcohol) and amylose-fatty acid salt inclusion complexes with increased surface hydrophobicity and high elongation

USDA-ARS?s Scientific Manuscript database

In this study, water-soluble amylose-inclusion complexes were prepared from high amylose corn starch and sodium salts of lauric, palmitic, and stearic acid by steam jet cooking. Cast films were prepared by combining the amylose complexes with poly(vinyl alcohol)(PVOH) solution at ratios varying from...

Disk Refining and Ultrasonication Treated Sugarcane Bagasse Residues for Poly(Vinyl Alcohol) Bio-composites

Treesearch

Qingzheng Cheng; Zhaohui Tong; Luisa Dempere; Lonnie Ingram; Letian Wang; J.Y. Zhu

2013-01-01

Disk refining and ultrasonication treated sugarcane bagasse residues reclaimed from the waste stream of a simplified bioethanol process after fermentation were used to fabricate biobased composites with poly(vinyl alcohol) (PVA) by film casting. The morphologies and the size distributions of residue particles were characterized by scanning electronic microscopy and...

A novel biobased plasticizer of epoxidized cardanol glycidylether: Synthesis and application in soft poly(vinyl chloride) films

USDA-ARS?s Scientific Manuscript database

A novel plasticizer derived from cardanol, epoxied cardanol glycidyl ether (ECGE), was synthesized and characterized by 1H-NMR and 13C-NMR. Effects of the ECGE combined with dioctyl phthalate (DOP), a commercial plasticizer, in soft poly(vinyl chloride) (PVC) films were studied. Dynamic mechanical a...

Effect of Poly(Vinyl Alcohol) Addition on the Properties of Hydrothermal Derived Calcium Phosphate Cement for Bone Filling Materials

NASA Astrophysics Data System (ADS)

Razali, N. N.; Sopyan, I.; Mel, M.; Salleh, H. M.; Rahman, M. M.; Singh, R.

2017-06-01

The effect of addition of poly(vinyl alcohol) on hydrothermal derived calcium phosphate cement has been studied. The precursors used to prepare the cement were calcium oxide (CaO) and ammonium dihydrogen phosphate (NH4H2PO4); the reaction was conducted in water at 80-100°C. To improve properties of CPC, poly(vinyl alcohol) (PVA) of 1wt% and 2wt% was added to the liquid phase of CPC and the results were compared to CPC without PVA addition. The addition of PVA was proved to bring remarkable effects on cohesion, setting time and mechanical strength of CPC which make it suitable physically for injectable bone filler applications.

Biomaterial properties evaluation of poly(vinyl acetate- alt-maleic anhydride)/chitosan nanocapsules

NASA Astrophysics Data System (ADS)

Raţă, Delia Mihaela; Popa, Marcel; Chailan, Jean-François; Zamfir, Carmen Lăcrămioara; Peptu, Cătălina Anişoara

2014-08-01

Nanocapsules with diameter around 100 nm based on a natural polymer (chitosan) and a synthetic polymer poly(vinyl acetate- alt-maleic anhydride) [poly(MAVA)] by interfacial condensation method were prepared. The present study proposes a new type of biocompatible nanocapsules based on poly(vinyl acetate- alt-maleic anhydride-chitosan) (MCS) able to become a reliable support for inclusion and release of drugs. The spherical shape of the nanocapsules was evidenced by scanning electron microscopy. Nanocapsules presented a good Norfloxacin loading and release capacity. Haemocompatibility tests have demonstrated that the nanocapsules present a low toxicity and a good compatibility with sanguine medium. The biocompatibility properties of the nanocapsules after their intraperitoneal administration in rats were evidenced by histopathological examination of different organs (brain, liver, kidney, and lung). The results are encouraging and the nanocapsules can be used as controlled drug delivery systems.

Lipase immobilization on epoxy-activated poly(vinyl acetate-acrylamide) microspheres.

PubMed

Zhang, Dong-Hao; Peng, Li-Juan; Wang, Yun; Li, Ya-Qiong

2015-05-01

Poly(vinyl acetate-acrylamide) microspheres with an average diameter of 2-4μm were successfully prepared and characterized via SEM and FTIR. Then the microspheres were modified with epoxy groups through reacting with epichlorohydrin and used as carriers to covalently immobilize Candida rugosa lipase. The results revealed that agitation played an important role on epoxy activation and the immobilization ratio increased with the increase of the epoxy density. On the other hand, the specific activity of the immobilized lipase as well as the activity recovery declined gradually with the increase in the immobilization ratio from 72% to 93%, which were attributed to the steric hindrance effects caused by enzyme overloading. When epoxy density was 76μmol/g microsphere, the activity recovery reached the maximum at 47.5%, and the activity of the immobilized lipase was 261.3U/g microsphere. Moreover, the thermal stability of the immobilized lipase was much better than that of the free one, which indicated potential applications of the immobilized lipase. Copyright © 2015 Elsevier B.V. All rights reserved.

Thermodynamic and Kinetic Behavior of the Polystyrene/Poly(vinyl methyl ether) Blend as Studied by Excimer Fluorescence.

DTIC Science & Technology

1986-01-02

AD-A±63 895 THERMODYNAMIC AND KINETIC BEHAVIOR OF THE / POLYSTYRENE/POLY(YINYL METHYL E..(U) STANFORD UNIY CALIFDEPT OF CHEMICAL ENGINEERING C N...Polystyrene/Poly(vinyl methyl ether) Blend 7. DEcFRMN 81 toOR 30USptE8 00~ as Studied by Excimer Fluorescence 6 EFRIGOG EOTNME *AUTHOR() a. CONTRACT OR GRANT...werea fondoare ihemoriisof * ~ Ex e sp fluodecositionsdu to deud Gen e and hoog Pinus Florsneis shownhase migrationprocSECURITY CLASIFICTIO OFd

Time-resolved spectroscopy of solid poly/1-vinyl naphthalene/ following electron beam pulse radiolysis - Pulse radiolytic studies on polymers

NASA Technical Reports Server (NTRS)

Coulter, D. R.; Liang, R. H.; Di Stefano, S.; Moacanin, J.; Gupta, A.

1982-01-01

Transient emission studies following pulse radiolysis of solid poly(1-vinyl naphthalene) show existence of excited monomers and two excimers. Quenching experiments indicate that excimers are not formed directly by recombination of ions but probably by trapping of migrating monomeric excitation in preformed traps whose density is approximately one in 1000.

Enhancement of diffraction efficiency and storage life of poly(vinyl chloride)-based optical recording medium with incorporation of an electron donor

NASA Astrophysics Data System (ADS)

John, Beena Mary; Ushamani, M.; Sreekumar, K.; Joseph, Rani; Sudha Kartha, C.

2007-01-01

The diffraction efficiency, sensitivity, and storage life of methylene blue-sensitized poly(vinyl chloride) film was improved by the addition of an electron donor in the matrix. The addition of pyridine enhanced the diffraction efficiency by two times, and storage life of the gratings was increased to 2-3 days.

Determination of glass transition temperature of reduced graphene oxide-poly(vinyl alcohol) composites using temperature dependent Fourier transform infrared spectroscopy

NASA Astrophysics Data System (ADS)

Mahendia, Suman; Heena; Kandhol, Geeta; Deshpande, Uday P.; Kumar, Shyam

2016-05-01

In the present work, structural properties of reduced graphene oxide (RGO) synthesized using modified Hummer's method and its composites with Poly(vinyl alcohol) (PVA) fabricated using solution-cast method have been studied. The structural properties of prepared samples have been systematically studied through UV-Visible absorption, Raman, Fourier Transform Infrared (FTIR) and Differential Scanning Calorimeter (DSC) spectroscopy. Infrared spectroscopy indicates the grafting of PVA chains with graphene layer through the formation of H-bonding linkage in the composites. Temperature-dependent FTIR spectra of PVA-RGO composite films were recorded to obtain the glass transition temperature (Tg) and to study its molecular origin. From these spectra the values of Tg were obtained using two-dimensional (2D) mapping of the first derivative of the absorbance intensity with respect to temperature (dA/dT), over the space of wavenumber and temperature. The value of Tg obtained for pure PVA increases from 78 °C to 92 °C after loading 0.5 wt.% of RGO in PVA and can be attributed to the strong H-bonding interaction between polymer chains and grafted solid surface of RGO. These results are in good agreement with those obtained from DSC analysis. This clearly indicates that the thermal behavior of PVA gets modified with loading of RGO.

Separator Membrane from Crosslinked Poly(Vinyl Alcohol) and Poly(Methyl Vinyl Ether-alt-Maleic Anhydride)

PubMed Central

Rohatgi, Charu Vashisth; Dutta, Naba K.; Choudhury, Namita Roy

2015-01-01

In this work, we report separator membranes from crosslinking of two polymers, such as poly vinyl alcohol (PVA) with an ionic polymer poly(methyl vinyl ether-alt-maleic anhydride) (PMVE-MA). Such interpolymer-networked systems were extensively used for biomedical and desalination applications but they were not examined for their potential use as membranes or separators for batteries. Therefore, the chemical interactions between these two polymers and the influence of such crosslinking on physicochemical properties of the membrane are systematically investigated through rheology and by critical gel point study. The hydrogen bonding and the chemical interaction between PMVE-MA and PVA resulted in highly cross-linked membranes. Effect of the molecular weight of PVA on the membrane properties was also examined. The developed membranes were extensively characterized by studying their physicochemical properties (water uptake, swelling ratio, and conductivity), thermal and electrochemical properties using differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), thermo-gravimetric analysis (TGA) and electrochemical impedance spectroscopy (EIS). The DSC study shows the presence of a single Tg in the membranes indicating compatibility of the two polymers in flexible and transparent films. The membranes show good stability and ion conductivity suitable for separator applications. PMID:28347019

Composite poly(vinyl alcohol)/poly(vinyl acetate) electrospun nanofibrous mats as a novel wound dressing matrix for controlled release of drugs

PubMed Central

Jannesari, Marziyeh; Varshosaz, Jaleh; Morshed, Mohammad; Zamani, Maedeh

2011-01-01

The aim of this study was to develop novel biomedicated nanofiber electrospun mats for controlled drug release, especially drug release directly to an injury site to accelerate wound healing. Nanofibers of poly(vinyl alcohol) (PVA), poly(vinyl acetate) (PVAc), and a 50:50 composite blend, loaded with ciprofloxacin HCl (CipHCl), were successfully prepared by an electrospinning technique for the first time. The morphology and average diameter of the electrospun nanofibers were investigated by scanning electron microscopy. X-ray diffraction studies indicated an amorphous distribution of the drug inside the nanofiber blend. Introducing the drug into polymeric solutions significantly decreased solution viscosities as well as nanofiber diameter. In vitro drug release evaluations showed that both the kind of polymer and the amount of drug loaded greatly affected the degree of swelling, weight loss, and initial burst and rate of drug release. Blending PVA and PVAc exhibited a useful and convenient method for electrospinning in order to control the rate and period of drug release in wound healing applications. Also, the thickness of the blend nanofiber mats strongly influenced the initial release and rate of drug release. PMID:21720511

Cyclodextrin modified hydrogels of PVP/PEG for sustained drug release.

PubMed

Nielsen, Anne Louise; Madsen, Flemming; Larsen, Kim Lambertsen

2009-02-01

Hydrogels are water swollen networks of polymers and especially hydrogels consisting of poly vinylpyrrolidone/poly ethyleneglycol-dimethacrylate (PVP/PEG-DMA) blends show promising wound care properties. Enhanced functionality of the hydrogels can be achieved by incorporating drugs and other substances that may assist wound healing into the gel matrix. Controlling the release of active compounds from the hydrogels may be possible by carefully modifying the polymer matrix. For this purpose, cyclodextrins (CD) were grafted to the polymer matrix in 4-5 w/w% in an attempt to retard the release of water-soluble drugs. Ibuprofenate (IBU) was chosen as model drug and loaded in IBU/CD ratios of 0.6, 1.2, and 2.5. Vinyl derivatives of alpha-, beta- and gamma-CD were produced, added to the prepolymer blend and cured by UV-light. During this curing process the CD derivatives were covalently incorporated into the hydrogel matrix. The modified hydrogels were loaded with ibuprofenate by swelling. The release of the model drug from CD modified hydrogels show that especially covalently bonded beta-cyclodextrin can change both the release rate and the release profile of ibuprofen.

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).

Development of functionalized hydroxyapatite/poly(vinyl alcohol) composites

NASA Astrophysics Data System (ADS)

Stipniece, Liga; Salma-Ancane, Kristine; Rjabovs, Vitalijs; Juhnevica, Inna; Turks, Maris; Narkevica, Inga; Berzina-Cimdina, Liga

2016-06-01

Based on the well-known pharmaceutical excipient potential of poly(vinyl alcohol) (PVA) and clinical success of hydroxyapatite (HAp), the objective of this work was to fabricate functionalized composite microgranules. PVA was modified with succinic anhydride to introduce carboxyl groups (-COOH), respectively, by reaction between the -OH groups of PVA and succinic anhydride, for attachment of drug molecules. For the first time, the functionalized composite microgranules containing HAp/PVA in the ratio of 1:1 were prepared through in situ precipitation of HAp in modified PVA aqueous solutions followed by spray drying of obtained suspensions. The microgranules were characterized by Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and differential scanning calorimetry (DSC). The presence of -COOH groups was verified by FT-IR, and the amount of functional groups added to PVA molecules (averaging 15 mol%) was determined by nuclear magnetic resonance spectroscopy (NMR). DSC results showed that modification with -COOH groups slightly decreased the thermal stability of PVA. FT-IR and XRD analysis confirmed that the resulting composites contain mainly nanocrystalline HAp and PVA. Moreover, the images taken by FE-SEM revealed that the microgranules consisted of nanosized HAp crystallites homogenously embedded in the PVA matrix. DSC measurements indicated that decomposition mechanism of the HAp/PVA differs from that of pure PVA and occurs at lower temperatures. However, the presence of HAp had minor influence on the thermal decomposition of the PVA modified with succinic anhydride. The investigation of composite microgranules confirmed interaction and integration between the HAp and PVA.

Passivation-free solid state battery

DOEpatents

Abraham, Kuzhikalail M.; Peramunage, Dharmasena

1998-01-01

This invention pertains to passivation-free solid-state rechargeable batteries composed of Li.sub.4 Ti.sub.5 O.sub.12 anode, a solid polymer electrolyte and a high voltage cathode. The solid polymer electrolyte comprises a polymer host, such as polyacrylonitrile, poly(vinyl chloride), poly(vinyl sulfone), and poly(vinylidene fluoride), plasticized by a solution of a Li salt in an organic solvent. The high voltage cathode includes LiMn.sub.2 O.sub.4, LiCoO.sub.2, LiNiO.sub.2 and LiV.sub.2 O.sub.5 and their derivatives.

Preparation of novel poly(vinyl alcohol)/SiO(2) composite nanofiber membranes with mesostructure and their application for removal of Cu(2+) from waste water.

PubMed

Wu, Shengju; Li, Fengting; Wu, Yinan; Xu, Ran; Li, Guangtao

2010-03-14

Novel mesoporous poly(vinyl alcohol)/SiO(2) composite nanofiber membranes functionalized with mercapto groups with diameters of 300-500 nm have been fabricated by a sol-gel electrospinning process; they were highly effective at absorbing Cu(ii) ions from waste water. These nanofiber membranes could be regenerated through acidification.

40 CFR 721.8658 - Modified polymer of vinyl acetate and quaternary ammonium compound (generic).

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Modified polymer of vinyl acetate and... Significant New Uses for Specific Chemical Substances § 721.8658 Modified polymer of vinyl acetate and.... (1) The chemical substance identified generically as modified polymer of vinyl acetate and quaternary...

40 CFR 721.8658 - Modified polymer of vinyl acetate and quaternary ammonium compound (generic).

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Modified polymer of vinyl acetate and... Significant New Uses for Specific Chemical Substances § 721.8658 Modified polymer of vinyl acetate and.... (1) The chemical substance identified generically as modified polymer of vinyl acetate and quaternary...

40 CFR 721.8658 - Modified polymer of vinyl acetate and quaternary ammonium compound (generic).

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Modified polymer of vinyl acetate and... Significant New Uses for Specific Chemical Substances § 721.8658 Modified polymer of vinyl acetate and.... (1) The chemical substance identified generically as modified polymer of vinyl acetate and quaternary...

40 CFR 721.8658 - Modified polymer of vinyl acetate and quaternary ammonium compound (generic).

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Modified polymer of vinyl acetate and... Significant New Uses for Specific Chemical Substances § 721.8658 Modified polymer of vinyl acetate and.... (1) The chemical substance identified generically as modified polymer of vinyl acetate and quaternary...

40 CFR 721.8658 - Modified polymer of vinyl acetate and quaternary ammonium compound (generic).

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Modified polymer of vinyl acetate and... Significant New Uses for Specific Chemical Substances § 721.8658 Modified polymer of vinyl acetate and.... (1) The chemical substance identified generically as modified polymer of vinyl acetate and quaternary...

Electrodialytic Transport Properties of Anion-Exchange Membranes Prepared from Poly(vinyl alcohol) and Poly(vinyl alcohol-co-methacryloyl aminopropyl trimethyl ammonium chloride).

PubMed

Jikihara, Atsushi; Ohashi, Reina; Kakihana, Yuriko; Higa, Mitsuru; Kobayashi, Kenichi

2013-01-02

Random-type anion-exchange membranes (AEMs) have been prepared by blending poly(vinyl alcohol) (PVA) and the random copolymer-type polycation, poly(vinyl alcohol-co-methacryloyl aminopropyl trimethyl ammonium chloride) at various molar percentages of anion-exchange groups to vinyl alcohol groups, Cpc, and by cross-linking the PVA chains with glutaraldehyde (GA) solution at various GA concentrations, CGA. The characteristics of the random-type AEMs were compared with blend-type AEMs prepared in our previous study. At equal molar percentages of the anion exchange groups, the water content of the random-type AEMs was lower than that of the blend-type AEMs. The effective charge density of the random-type AEMs increased with increasing Cpc and reached a maximum value. Further, the maximum value of the effective charge density increased with increasing CGA. The maximum value of the effective charge density, 0.42 mol/dm3, was obtained for the random-type AEM with Cpc = 4.2 mol % and CGA = 0.15 vol %. A comparison of the random-type and blend-type AEMs with almost the same Cpc showed that the random-type AEMs had lower membrane resistance than the blend-type ones. The membrane resistance and dynamic transport number of the random-type AEM with Cpc = 6.0 mol % and CGA = 0.15 vol % were 4.8 Ω cm2 and 0.83, respectively.

Electrodialytic Transport Properties of Anion-Exchange Membranes Prepared from Poly(vinyl alcohol) and Poly(vinyl alcohol-co-methacryloyl aminopropyl trimethyl ammonium chloride)

PubMed Central

Jikihara, Atsushi; Ohashi, Reina; Kakihana, Yuriko; Higa, Mitsuru; Kobayashi, Kenichi

2012-01-01

Random-type anion-exchange membranes (AEMs) have been prepared by blending poly(vinyl alcohol) (PVA) and the random copolymer-type polycation, poly(vinyl alcohol-co-methacryloyl aminopropyl trimethyl ammonium chloride) at various molar percentages of anion-exchange groups to vinyl alcohol groups, Cpc, and by cross-linking the PVA chains with glutaraldehyde (GA) solution at various GA concentrations, CGA. The characteristics of the random-type AEMs were compared with blend-type AEMs prepared in our previous study. At equal molar percentages of the anion exchange groups, the water content of the random-type AEMs was lower than that of the blend-type AEMs. The effective charge density of the random-type AEMs increased with increasing Cpc and reached a maximum value. Further, the maximum value of the effective charge density increased with increasing CGA. The maximum value of the effective charge density, 0.42 mol/dm3, was obtained for the random-type AEM with Cpc = 4.2 mol % and CGA = 0.15 vol %. A comparison of the random-type and blend-type AEMs with almost the same Cpc showed that the random-type AEMs had lower membrane resistance than the blend-type ones. The membrane resistance and dynamic transport number of the random-type AEM with Cpc = 6.0 mol % and CGA = 0.15 vol % were 4.8 Ω cm2 and 0.83, respectively. PMID:24958543

Effect of gamma ray on poly(lactic acid)/poly(vinyl acetate-co-vinyl alcohol) blends as biodegradable food packaging films

NASA Astrophysics Data System (ADS)

Razavi, Seyed Mohammad; Dadbin, Susan; Frounchi, Masoud

2014-03-01

Poly(lactic acid) (PLA)/poly(vinyl acetate-co-vinyl alcohol) [P(VAc-co-VA)] blends as new transparent film packaging materials were prepared at various blend compositions and different vinyl alcohol contents. The blends and pure PLA were irradiated by gamma rays to investigate the extent of changes in the packaging material during gamma ray sterilization process. The miscibility of the blends was dependent on the blend composition and vinyl alcohol content; gamma irradiation had little effect on the extent of miscibility. The glass transition temperature of pure PLA and PLA/P(VAc-co-VA) miscible blends reduced after irradiation. On the other hand in PLA/P(VAc-co-VA) immiscible blends, while the glass transition temperature of the PLA phase decreased; that of the copolymer phase slightly increased. The reduction in the glass transition was about 10 percent for samples irradiated with 50 kGy indicating dominance of chain scission of PLA molecules at high irradiation dose. The latter was verified by drop in mechanical properties of pure PLA after exposing to gamma irradiation at 50 kGy. Blending of PLA with the copolymer P(VAc-co-VA) compensated greatly the adverse effects of irradiation on PLA. The oxygen-barrier property of the blend was superior to the neat PLA and remained almost intact with irradiation. The un-irradiated and irradiated blends had excellent transparency. Gamma ray doses used for sterilization purposes are usually less than 20 kGy. It was shown that gamma irradiation at 20 kGy had no or little adverse effects on PLA/P(VAc-co-VA) blends mechanical and gas barrier properties.

Influences of modified bacterial cellulose nanofibers (BCNs) on structural, thermophysical, optical, and barrier properties of poly ethylene-co-vinyl acetate (EVA) nanocomposite.

PubMed

Ghadikolaei, Shila Shirdel; Omrani, Abdollah; Ehsani, Morteza

2018-04-14

The BCNs were chemically modified using acetic anhydride with the aim of improving its dispersion and interfacial adhesion. Acetylation of BCNs was confirmed by FT-IR spectroscopy. Morphology studies using TEM and SEM revealed that a reasonable dispersion of the modified BCNs in the EVA matrix was accomplished. The DSC data displayed a little shift in the T g to higher temperatures with the incorporation of both modified and unmodified BCNs. Increased thermal stability of the nanocomposites consisting acetylated BCNs was confirmed by TGA technique. DMA measurements highlighted that the storage modulus increased and the damping properties decreased for the nanocomposites with regard to the neat EVA. Copyright © 2018 Elsevier B.V. All rights reserved.

Improvement of Polylactide Properties through Cellulose Nanocrystals Embedded in Poly(Vinyl Alcohol) Electrospun Nanofibers

PubMed Central

López de Dicastillo, Carol; Garrido, Luan; Alvarado, Nancy; Romero, Julio; Palma, Juan Luis; Galotto, Maria Jose

2017-01-01

Electrospun nanofibers of poly (vinyl alcohol) (PV) were obtained to improve dispersion of cellulose nanocrystals (CNC) within hydrophobic biopolymeric matrices, such as poly(lactic acid) (PLA). Electrospun nanofibers (PV/CNC)n were successfully obtained with a final concentration of 23% (w/w) of CNC. Morphological, structural and thermal properties of developed CNC and electrospun nanofibers were characterized. X-ray diffraction and thermal analysis revealed that the crystallinity of PV was reduced by the electrospinning process, and the incorporation of CNC increased the thermal stability of biodegradable nanofibers. Interactions between CNC and PV polymer also enhanced the thermal stability of CNC and improved the dispersion of CNC within the PLA matrix. PLA materials with CNC lyophilized were also casted in order to compare the properties with materials based on CNC containing nanofibers. Nanofibers and CNC were incorporated into PLA at three concentrations: 0.5%, 1% and 3% (CNC respect to polymer weight) and nanocomposites were fully characterized. Overall, nanofibers containing CNC positively modified the physical properties of PLA materials, such as the crystallinity degree of PLA which was greatly enhanced. Specifically, materials with 1% nanofiber 1PLA(PV/CNC)n presented highest improvements related to mechanical and barrier properties; elongation at break was enhanced almost four times and the permeation of oxygen was reduced by approximately 30%. PMID:28492470

Ultrasonic-assisted synthesis of phosphorus graphene oxide/poly (vinyl alcohol) polymer and surface resistivity research of phosphorus graphene oxide/poly (vinyl alcohol) film.

PubMed

Li, Jihui; Li, Yongshen; Niu, Shuai; Li, Ning

2017-05-01

In this paper, phosphorus graphene oxide/poly (vinyl alcohol) polymer (PGO/PVA polymer) was synthesized by PGO and PVA via the esterification in the case of faint acidity and the ultrasound irradiation and characterized; moreover, phosphorus graphene oxide/poly (vinyl alcohol) film (PGO/PVA film) was prepared by PGO/PVA polymer and characterized; also, the surface resistivity of PGO/PVA film was investigated in the case of the different amount of PGO. Based on those, it had been found that PGO reacted with PVA to produce PGO/PVA polymer via the esterification under the ultrasonic-assisted condition, and PGO/PVA polymer was structured by 2D lattice of PGO and the chain of PVA connected in the form of six-member lactone ring and phosphonic ester, and PGO/PVA film was constituted by PGO/PVA polymer, and surface resistivity of 0.00, 0.75, 1.50, 2.25 and 3.00wt% of PGO/PVA film were 6.85×10 8 , 2.98×10 8 , 1.42×10 6 , 7.66×10 4 and 1.29×10 5 Ω/sq, respectively. Copyright © 2016 Elsevier B.V. All rights reserved.

Adsorption of poly(vinyl formamide-co-vinyl amine) (PVFA-co-PVAm) polymers on zinc, zinc oxide, iron, and iron oxide surfaces.

PubMed

Seifert, Susan; Simon, Frank; Baumann, Giesela; Hietschold, Michael; Seifert, Andreas; Spange, Stefan

2011-12-06

The adsorption of poly(vinyl formamide) (PVFA) and the statistic copolymers poly(vinyl formamide-co-vinyl amine) (PVFA-co-PVAm) onto zinc and iron metal particles as well as their oxides was investigated. The adsorbates were characterized by means of XPS, DRIFT spectroscopy, wet chemical analysis, and solvatochromic probes. Dicyano-bis-(1,10-phenanthroline)-iron(II) (1), 3-(4-amino-3-methylphenyl)-7-phenyl-benzo-[1,2-b:4,5-b']difuran-2,6-dione (2), and 4-tert-butyl-2-(dicyano-methylene)-5-[4-(diethylamino)-benzylidene]-Δ(3)-thiazoline (3) as solvatochromic probes were coadsorbed onto zinc oxide to measure various effects of surface polarity. The experimental findings showed that the adsorption mechanism of PVFA and PVFA-co-PVAm strongly depends on the degree of hydrolysis of PVFA and pH values and also on the kind of metal or metal oxide surfaces that were employed as adsorbents. The adsorption mechanism of PVFA/PVFA-co-PVAm onto zinc oxide and iron oxide surfaces is mainly affected by electrostatic interactions. Particularly in the region of pH 5, the adsorption of PVFA/PVFA-co-PVAm onto zinc and iron metal particles is additionally influenced by redox processes, dissolution, and complexation reactions. © 2011 American Chemical Society

Passivation-free solid state battery

DOEpatents

Abraham, K.M.; Peramunage, D.

1998-06-16

This invention pertains to passivation-free solid-state rechargeable batteries composed of Li{sub 4}Ti{sub 5}O{sub 12} anode, a solid polymer electrolyte and a high voltage cathode. The solid polymer electrolyte comprises a polymer host, such as polyacrylonitrile, poly(vinyl chloride), poly(vinyl sulfone), and poly(vinylidene fluoride), plasticized by a solution of a Li salt in an organic solvent. The high voltage cathode includes LiMn{sub 2}O{sub 4}, LiCoO{sub 2}, LiNiO{sub 2} and LiV{sub 2}O{sub 5} and their derivatives. 5 figs.

Synthesis of a New Titanate Coupling Agent for the Modification of Calcium Sulfate Whisker in Poly(Vinyl Chloride) Composite

PubMed Central

Yuan, Wenjin; Lu, Yunhua; Xu, Shiai

2016-01-01

A new titanate coupling agent synthesized from polyethylene glycol (PEG), isooctyl alcohol, and phosphorus pentoxide (P2O5) was used for the modification of calcium sulfate whiskers (CSWs) and the preparation of high-performance CSW/poly(vinyl chloride) (PVC) composites. The titanate coupling agent (sTi) and the modified CSWs (sTi–CSW) were characterized by Fourier transform infrared (FTIR) spectroscopy, and the mechanical, dynamic mechanical, and heat resistant properties and thermostability of sTi–CSW/PVC and CSW/PVC composites were compared. The results show that sTi–CSW/PVC composite with 10 wt. % whisker content has the best performance, and its tensile strength, Young’s modulus, elongation at break, break strength, and impact strength are 67.2 MPa, 1926 MPa, 233%, 51.1 MPa, and 12.75 KJ·m−2, with an increase of 20.9%, 11.5%, 145.3%, 24.6%, and 65.4% compared to that of CSW/PVC composite at the same whisker content. As the whisker content increases, the storage modulus increases, the Vicat softening temperature decreases slightly, and the glass transition temperature increases at first and then decreases. PMID:28773748

Control of biofilm formation by poly-ethylene-co-vinyl acetate films incorporating nisin.

PubMed

Nostro, Antonia; Scaffaro, Roberto; Ginestra, Giovanna; D'Arrigo, Manuela; Botta, Luigi; Marino, Andreana; Bisignano, Giuseppe

2010-06-01

The aim of this study was to evaluate the effect of poly-ethylene-co-vinyl acetate (EVA) films incorporating different concentrations (0.1%, 0.5% and 1%) of nisin on the biofilm-forming ability of Listeria monocytogenes ATCC 7644, Staphylococcus aureus 815 and Staphylococcus epidermidis ATCC 35984. Nisin was incorporated into two grades of EVA (EVA14 and EVA28) in the melt during a common film-blowing operation. The efficacy of EVA/nisin films was evaluated by biofilm biomass measurements and Live/Dead staining in combination with fluorescence microscopy. In order to evaluate whether the nisin incorporation could modify the film surface properties, contact angle measurements and scanning electron microscopy were performed. The results revealed the efficacy of EVA14/nisin films in reducing biofilm formation on their surfaces with more evident effect for S. epidermidis than L. monocytogenes and S. aureus strains. In contrast, EVA28/nisin films showed unsatisfactory activity. Fluorescence microscopy confirmed poor biofilm formation on EVA14/nisin films, also characterised by the presence of dead cells. The data presented in this study offer new potential applications for developing strategies aimed to improve the effect of antimicrobial agents.

The role of tortuosity on ion conduction in block copolymer electrolyte thin films

NASA Astrophysics Data System (ADS)

Kambe, Yu; Arges, Christopher G.; Nealey, Paul F.

This talk discusses the role of grain tortuosity on ion conductivity in block copolymer electrolyte (BCE) thin films. In particular, we studied lamellae forming BCEs with both domains oriented perpendicular to the substrate surface and connected directly from one electrode to another - i.e., tortuosity of one. The BCE is composed of ion-conducting, poly(2-vinyl n-methylpyridinium) blocks and non-ionic polystyrene blocks. Prior to creating the BCE, the pristine block copolymer, poly(styrene- b-2-vinyl pyridine), was directly self-assembled (DSA) on topographical or chemical patterns via graphoepitaxy and chemoepitaxy. A chemical vapor infiltration reaction modified the P2VP block into positively charged, fixed quaternary ammonium groups paired with mobile counteranions. The graphoepitaxy process utilized topographical interdigitated gold nanoelectrodes (100s of nanometers spacing between electrodes) created via e-beam lithography. Alternatively, chemical patterns had gold electrodes incorporated into them with 10s to 100s of microns spacing using conventional optical lithography. The interdigitated gold electrodes enabled in-plane ion conductivity measurements of the DSA BCEs to study the role of grain tortuosity on ion conductivity. U.S. Department of Energy Office of Science: Contract No. DE-AC02-06CH11357.

Fractionation of poly(methacrylic acid) and poly(vinyl pyridine) in aqueous and organic mobile phases by multidetector thermal field-flow fractionation.

PubMed

Greyling, Guilaume; Pasch, Harald

2017-08-25

Multidetector thermal field-flow fractionation (ThFFF) is shown to be a versatile characterisation platform that can be used to characterise hydrophilic polymers in a variety of organic and aqueous solutions with various ionic strengths. It is demonstrated that ThFFF fractionates isotactic and syndiotactic poly(methacrylic acid) (PMAA) as well as poly(2-vinyl pyridine) (P2VP) and poly(4-vinyl pyridine) (P4VP) according to microstructure in organic solvents and that the ionic strength of the mobile phase has no influence on the retention behaviour of the polymers. With regard to aqueous solutions, it is shown that, despite the weak retention, isotactic and syndiotactic PMAA show different retention behaviours which can qualitatively be attributed to microstructure. Additionally, it is shown that the ionic strength of the mobile phase has a significant influence on the thermal diffusion of polyelectrolytes in aqueous solutions and that the addition of an electrolyte is essential to achieve a microstructure-based separation of P2VP and P4VP in aqueous solutions. Copyright © 2017 Elsevier B.V. All rights reserved.

Biomedical applications of stereoregular poly(vinyl alcohol) micro- and nanoparticles

NASA Astrophysics Data System (ADS)

Lyoo, Won Seok; Kim, Joon Ho; Kim, Sam Soo; Ghim, Han Do

2002-11-01

Syndiotactic poly(vinyl alcohol) (PVA)/poly(vinyl pivalate/vinyl acetate) (P(VPi/VAc)) and atactic PVA/PVAc micro- and nanoparticles with skin/core structure have been prepared by heterogeneous saponification of P(VPi/VAc) and PVAc micro- and nanoparticles. Especially, to prepare P(VPi/VAc) and PVAc microparticles having various particle sizes and uniform particle size distribution, vinyl pivalate (VPi)/vinyl acetate (VAc) and VAc were suspension-polymerized using a low-temperature initiator, 2,2"-azobis(2,4-dimethylvaleronitrile). P(VPi/VAc) particles are promising precursor of stereoregular PVA embolic materials which can be introduced through catheters in the management of gastrointestinal bleeders, arteriovenous malformations, hemangiomas, and traumatic rupture of blood vessels. Monodisperse and/or nearly monodisperse P(VPi/VAc) and PVAc microparticles with various particle diameters were obtained by controlling suspension polymerization conditions. Monodisperse P(VPi/VAc) and PVAc microparticles having various particle sizes were partially saponified in the heterogeneous system. PVA/P(VPi/VAc) and PVA/PVAc microparticles having various tacticity and degree of saponification were produced by controlling various polymerization and saponification conditions. The coating of stereoregular PVA micro- and nanoparticles for drug release experiments was conducted with the strepo-avidin-alkaline phosphatase conjugate in variable conditions of pH value, coating buffer, and reaction temperature. Protein-coated syndiotactic PVA micro- and nanoparticles, which does not crosslinking, were more superior to controllability of drug release, durability, and dimensional stability to water and blood than atactic one.

A novel route to prepare a multilayer system via the combination of interface-mediated catalytic chain transfer polymerization and thiol-ene click chemistry.

PubMed

Zengin, Adem; Caykara, Tuncer

2017-05-01

Herein, we have designed a novel multilayer system composed of poly(methyl methacrylate) [poly(MMA)] brush, biotin, streptavidin and protein-A on a silicon substrate to attach onanti-immunoglobulin G (anti-IgG). poly(MMA) brush with vinyl end-group was first synthesized by the interface-mediated catalytic chain transfer polymerization. The brush was then modified with cysteamine molecules to generate the polymer chains with amine end-group via a thiol-ene click chemistry. The amine end-groups of poly(MMA) chains were also modified with biotin units to ensure selective connection points for streptavidin molecules. Finally, a multilayer system on the silicon substrate was formed by using streptavidin and protein-A molecules, respectively. This multilayer system was employed to attach anti-IgG molecules in a highly oriented manner and provide anti-IgG molecular functional configuration on the multilayer. High reproducibility of the amount of anti-IgG adsorption and homogeneous anti-IgG adsorption layer on the silicon surface could be provided by this multilayer system. The multilayer system with protein A may be opened the door for designing an efficient immunoassay protein chip. Copyright © 2017. Published by Elsevier B.V.

Electron-beam-initiated polymerization of poly(ethylene glycol)-based wood impregnants.

PubMed

Trey, Stacy M; Netrval, Julia; Berglund, Lars; Johansson, Mats

2010-11-01

The current study demonstrates that methacrylate and acrylate poly(ethylene glycol) (PEG) functional oligomers can be effectively impregnated into wood blocks, and cured efficiently to high conversions without catalyst by e-beam radiation, allowing for less susceptibility to leaching, and favorable properties including higher Brinell hardness values. PEG based monomers were chosen because there is a long history of this water-soluble monomer being able to penetrate the cell wall, thus bulking it and decreasing the uptake of water which further protects the wood from fungal attack. Diacrylate, dimethacrylate, and dihydroxyl functional PEG of M(w) 550-575, of concentrations 0, 30, 60, and 100 wt % in water, were vacuum pressure impregnated into Scots Pine blocks of 15 × 25 × 50 mm in an effort to bulk the cell wall. The samples were then irradiated and compared with nonirradiated samples. It was shown by IR, DSC that the acrylate polymers were fully cured to much higher conversions than can be reached with conventional methods. Leaching studies indicated a much lower amount of oligomer loss from the cured vinyl functional PEG chains in comparison to hydroxyl functional PEG indicating a high degree of fastening of the polymer in the wood. The Brinell hardness indicated a significant increase in hardness to hardwood levels in the modified samples compared to the samples of hydroxyl functional PEG and uncured vinyl PEG samples, which actually became softer than the untreated Scots Pine. By monitoring the dimensions of the sample it was found by weight percent gain calculations (WPG %) that water helps to swell the wood structure and allow better access of the oligomers into the cell wall. Further, the cure shrinkage of the wood samples demonstrated infiltration of the oligomers into the cell wall as this was not observed for methyl methacrylate which is well-documented to remain in the lumen. However, dimensional stability of the vinyl polymer modified blocks when placed in water was not observed to the same extent as PEG.

Preparation of poly(vinyl alcohol)/kaolinite nanocomposites via in situ polymerization

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

Jia Xin; Department of Chemistry, Hexi University, Zhangye 734000; Li Yanfeng

2008-03-04

Poly(vinyl alcohol)/kaolinite intercalated nanocomposites (Kao-PVA) were prepared via in situ intercalation radical polymerization. Vinyl acetate (VAc) was intercalated into kaolinite by a displacement method using dimethyl sulfoxide/kaolinite (Kao-DMSO) as the intermediate. Then, PVAc/kaolinite (Kao-PVAc) was obtained via radical polymerization with benzoyl peroxide (BPO) as initiator. Last, PVAc/kaolinite was saponified via direct-hydrolysis with NaOH solution in order to obtain PVA/kaolinite nanocomposites, which was characterized by Fourier-Transformation spectroscopy (FTIR), wide X-ray diffraction (WXRD) and transmission electron microscopy (TEM). Their differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) results of the obtained PVA/kaolinite suggested that the thermal properties had an obvious improvement.

Anisotropic wetting of microstructured surfaces as a function of surface chemistry.

PubMed

Neuhaus, Sonja; Spencer, Nicholas D; Padeste, Celestino

2012-01-01

In order to study the influence of surface chemistry on the wetting of structured surfaces, microstructures consisting of grooves or squares were produced via hot embossing of poly(ethylene-alt-tetrafluoroethylene) ETFE substrates. The structured substrates were modified with polymer brushes, thereby changing their surface functionality and wettability. Water droplets were most strongly pinned to the structure when the surface was moderately hydrophilic, as in the case of poly(4-vinylpyridine) (P4VP) or poly(vinyl(N-methyl-2-pyridone) (PVMP) brush-modified substrates. As a result, the droplet shape was determined by the features of the microstructure. The water contact angles (CA) were considerably higher than on flat surfaces and differed, in the most extreme case, by 37° when measured on grooved substrates, parallel and perpendicular to the grooves. On hydrophobic substrates (pristine ETFE), the same effects were observed but were much less pronounced. On very hydrophilic sampes (those modified with poly(N-methyl-vinylpyridinium) (QP4VP)), the microstructure had no influence on the drop shape. These findings are explained by significant differences in apparent and real contact angles at the relatively smooth edges of the embossed structures. Finally, the highly anisotropic grooved microstructure was combined with a gradient in polymer brush composition and wettability. In the case of a parallel alignment of the gradient direction to the grooves, the directed spreading of water droplets could be observed. © 2011 American Chemical Society

Synthesis and characterization of Pd-poly(N-vinyl-2-pyrrolidone)/KIT-5 nanocomposite as a polymer-inorganic hybrid catalyst for the Suzuki-Miyaura cross-coupling reaction

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

Kalbasi, Roozbeh Javad, E-mail: rkalbasi@iaush.ac.ir; Mosaddegh, Neda

2011-11-15

Composite poly(N-vinyl-2-pyrrolidone)/KIT-5 (PVP/KIT-5) was prepared by in situ polymerization method and used as a support for palladium nanoparticles obtained through the reduction of Pd(OAc){sub 2} by hydrazine hydrate. The physical and chemical properties of the catalyst were investigated by XRD, FT-IR, UV-vis, TG, BET, SEM, and TEM techniques. The catalytic performance of this novel heterogeneous catalyst was determined for the Suzuki-Miyaura cross-coupling reaction between aryl halides and phenylboronic acid in the presence of water at room temperature. The stability of the nanocomposite catalyst was excellent and could be reused 8 times without much loss of activity in the Suzuki-Miyaura cross-couplingmore » reaction. - Graphical Abstract: Pd-poly(N-vinyl-2-pyrrolidone)/KIT-5 was prepared as an organic-inorganic hybrid catalyst for the Suzuki-Miyaura reaction. The stability of the catalyst was excellent and could be reused 8 times in the Suzuki-Miyaura reaction. Highlights: > Pd-poly(N-vinyl-2-pyrrolidone)/KIT-5 was prepared as a novel nanocomposite. > Nanocomposite was prepared based on a cage-type mesoporous system. > Catalyst showed excellent activity for Suzuki-Miyaura reaction in water. > Stability of the catalyst was excellent and could be reused 8 times.« less

Preparation of robust braid-reinforced poly(vinyl chloride) ultrafiltration hollow fiber membrane with antifouling surface and application to filtration of activated sludge solution.

PubMed

Zhou, Zhuang; Rajabzadeh, Saeid; Fang, Lifeng; Miyoshi, Taro; Kakihana, Yuriko; Matsuyama, Hideto

2017-08-01

Braid-reinforced hollow fiber membranes with high mechanical properties and considerable antifouling surface were prepared by blending poly(vinyl chloride) (PVC) with poly(vinyl chloride-co-poly(ethylene glycol) methyl ether methacrylate) (poly(VC-co-PEGMA)) copolymer via non-solvent induced phase separation (NIPS). The tensile strength of the braid-reinforced PVC hollow fiber membranes were significantly larger than those of previously reported various types of PVC hollow fiber membranes. The high interfacial bonding strength indicated the good compatibility between the coating materials and the surface of polyethylene terephthalate (PET)-braid. Owing to the surface segregation phenomena, the membrane surface PEGMA coverage increased upon increasing the poly(VC-co-PEGMA)/PVC blending ratio, resulting in higher hydrophilicities and bovine serum albumin (BSA) repulsion. To compare the fouling properties, membranes with similar PWPs were prepared by adjusting the dope solution composition to eliminate the effect of hydrodynamic conditions on the membrane fouling performance. The blend membranes surface exhibited considerable fouling resistance to the molecular adsorption from both BSA solution and activated sludge solution. In both cases, the flux recovered to almost 80% of the initial flux using only water backflush. Considering their great mechanical properties and antifouling resistance to activated sludge solution, these novel membranes show good potential for application in wastewater treatment. Copyright © 2017 Elsevier B.V. All rights reserved.

Bimodal porous TiO2 structures templated by graft copolymer/homopolymer blend for dye-sensitized solar cells with polymer electrolyte

NASA Astrophysics Data System (ADS)

Kim, Jin Kyu; Lee, Chang Soo; Lee, Sang-Yup; Cho, Hyung Hee; Kim, Jong Hak

2016-12-01

Bimodal porous TiO2 (BP-TiO2) with large surface area, high porosity, good interconnectivity, and excellent light-scattering ability are synthesized via a facile one-step method using a self-assembled blend template consisting of an amphiphilic poly(vinyl chloride)-g-poly(oxyethylene methacrylate) (PVC-g-POEM) graft copolymer and a hydrophobic poly(vinyl chloride) (PVC) homopolymer. The hydrophilically surface-modified TiO2 nanoparticles selectively interact with the hydrophilic POEM chains, while the addition of the PVC homopolymer increases the hydrophobic domain size, resulting in the formation of dual pores (i.e., macropores and mesopores). The sizes and numbers of macropores can easily be controlled by changing the molecular weight and amount of the PVC homopolymer. The polymer electrolyte dye-sensitized solar cells (DSSCs) fabricated with BP-TiO2 photoanodes exhibited energy conversion efficiencies of up to 7.6% at 100 mW cm-2, which is much higher than those of mesoporous TiO2 (5.8%) with PVC-g-POEM only and conventional nanocrystalline TiO2 (4.9%) with commercial Dyesol paste. The enhanced energy conversion efficiencies mostly resulted from the light-scattering effects of the macropores, which increased the light-harvesting efficiencies. The improved light-harvesting and photovoltaic performances of the DSSCs were characterized by UV-vis spectroscopy, incident photon-to-current conversion efficiency analysis, electrochemical impedance spectroscopy, intensity-modulated photocurrent spectroscopy, and intensity-modulated photovoltage spectroscopy.

Photo-triggered release from liposomes without membrane solubilization, based on binding to poly(vinyl alcohol) carrying a malachite green moiety.

PubMed

Uda, Ryoko M; Kato, Yutaka; Takei, Michiko

2016-10-01

When working with liposomes analogous to cell membranes, it is important to develop substrates that can regulate interactions with the liposome surface in response to light. We achieved a photo-triggered release from liposomes by using a copolymer of poly(vinyl alcohol) carrying a malachite green moiety (PVAMG). Although PVAMG is a neutral polymer under dark conditions, it is photoionized upon exposure to UV light, resulting in the formation of a cationic site for binding to liposomes with a negatively charged surface. Under UV irradiation, PVAMG showed effective interaction with liposomes, releasing the encapsulated compound; however, this release was negligible under dark conditions. The poly(vinyl alcohol) moiety of PVAMG played an important role in the photo-triggered release. This release was caused by membrane destabilization without lipid solubilization. We also investigated different aspects of liposome/PVAMG interactions, including PVAMG-induced fusion between the liposomes and the change in the liposome morphologies. Copyright © 2016 Elsevier B.V. All rights reserved.

Poly(vinyl alcohol) cryogel phantoms for use in ultrasound and MR imaging

NASA Astrophysics Data System (ADS)

Surry, K. J. M.; Austin, H. J. B.; Fenster, A.; Peters, T. M.

2004-12-01

Poly(vinyl alcohol) cryogel, PVA-C, is presented as a tissue-mimicking material, suitable for application in magnetic resonance (MR) imaging and ultrasound imaging. A 10% by weight poly(vinyl alcohol) in water solution was used to form PVA-C, which is solidified through a freeze-thaw process. The number of freeze-thaw cycles affects the properties of the material. The ultrasound and MR imaging characteristics were investigated using cylindrical samples of PVA-C. The speed of sound was found to range from 1520 to 1540 m s-1, and the attenuation coefficients were in the range of 0.075-0.28 dB (cm MHz)-1. T1 and T2 relaxation values were found to be 718-1034 ms and 108-175 ms, respectively. We also present applications of this material in an anthropomorphic brain phantom, a multi-volume stenosed vessel phantom and breast biopsy phantoms. Some suggestions are made for how best to handle this material in the phantom design and development process.

Poly(vinyl methyl ether) hydrogels at temperatures below the freezing point of water-molecular interactions and states of water.

PubMed

Pastorczak, Marcin; Dominguez-Espinosa, Gustavo; Okrasa, Lidia; Pyda, Marek; Kozanecki, Marcin; Kadlubowski, Slawomir; Rosiak, Janusz M; Ulanski, Jacek

2014-01-01

Water interacting with a polymer reveals a number of properties very different to bulk water. These interactions lead to the redistribution of hydrogen bonds in water. It results in modification of thermodynamic properties of water and the molecular dynamics of water. That kind of water is particularly well observable at temperatures below the freezing point of water, when the bulk water crystallizes. In this work, we determine the amount of water bound to the polymer and of the so-called pre-melting water in poly(vinyl methyl ether) hydrogels with the use of Raman spectroscopy, dielectric spectroscopy, and calorimetry. This analysis allows us to compare various physical properties of the bulk and the pre-melting water. We also postulate the molecular mechanism responsible for the pre-melting of part of water in poly(vinyl methyl ether) hydrogels. We suggest that above -60 °C, the first segmental motions of the polymer chain are activated, which trigger the process of the pre-melting.

Preparation and characterization of reactive blends of poly(lactic acid), poly(ethylene-co-vinyl alcohol), and poly(ethylene-co-glycidyl methacrylate)

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

Warangkhana, Phromma; Rathanawan, Magaraphan, E-mail: rathanawan.k@chula.ac.th; Jana Sadhan, C., E-mail: janas@uakron.edu

The ternary blends of poly(lactic acid) (PLA), poly(ethylene-co-vinyl alcohol) (EVOH), and poly(ethylene-co-glycidyl methacrylate) (EGMA) were prepared. The role of EGMA as a compatibilizer was evaluated. The weight ratio of PLA:EVOH was 80:20 and the EGMA loadings were varied from 5-20 phr. The blends were characterized as follows: thermal properties by differential scanning calorimetry, morphology by scanning electron microscopy, and mechanical properties by pendulum impact tester, and universal testing machine. The glass transition temperature of PLA blends did not change much when compared with that of PLA. The blends of PLA/EGMA and EVOH/EGMA showed EGMA dispersed droplets where the latter ledmore » to poor impact properties. However, the tensile elongation at break and tensile toughness substantially increased upon addition of EGMA to blends of PLA and EVOH. It was noted in tensile test samples that both PLA and EVOH domains fibrillated significantly to produce toughness.« less

Poly(vinyl benzoate) nanoparticles for molecular delivery: Studies on their preparation and in vitro properties.

PubMed

Labruère, Raphaël; Sicard, Renaud; Cormier, Ryan; Turos, Edward; West, Leigh

2010-12-01

The preparation and properties of poly(vinyl benzoate) nanoparticle suspensions as molecular carriers are described for the first time. These nanoparticles can be formed by nanoprecipitation of commercial poly(vinyl benzoate) in water using Pluronic F68 as surfactant, to create spherical nanostructures measuring 200-250nm in diameter. These nanoparticles are stable in phosphate buffer and blood serum, and only slowly degrade in the presence of esterases. Pluronic F68 stabilizes the nanoparticle and also protects it from enzymatic degradation. Up to 1.6% by weight of a lipid-soluble molecule such as coumarin-6 can be introduced into the nanoparticle during nanoprecipitation, compared to a water-soluble compound (5(6)-carboxyfluorescein) which gave almost no loading. Kinetics experiments in phosphate buffer indicate that 78% of the coumarin-6 was encapsulated within the polymer matrix of the nanoparticle, and the residual 22% of coumarin-6 was surface-bound and quickly released. The nanoparticles are non-toxic in vitro towards human epithelial cells (IC(50)>1000μg/mL) and primary bovine aortic endothelial cells (IC(50)>500μg/mL), and non-bactericidal against a selection of representative test microbes (MIC >250μg/mL). These properties suggest that the poly(vinyl benzoate) nanoparticles may be suitable carriers for molecular delivery of lipophilic small molecules such as pharmaceutical and imaging agents. Copyright © 2010. Published by Elsevier B.V.

Controlled grafting of comb copolymer brushes on poly(tetrafluoroethylene) films by surface-initiated living radical polymerizations.

PubMed

Yu, W H; Kang, E T; Neoh, K G

2005-01-04

Surface modification of poly(tetrafluoroethylene) (PTFE) films by well-defined comb copolymer brushes was carried out. Peroxide initiators were generated directly on the PTFE film surface via radio frequency Ar plasma pretreatment, followed by air exposure. Poly(glycidyl methacrylate) (PGMA) brushes were first prepared by surface-initiated reversible addition-fragmentation chain transfer polymerization from the peroxide initiators on the PTFE surface in the presence of a chain transfer agent. Kinetics study revealed a linear increase in the graft concentration of PGMA with the reaction time, indicating that the chain growth from the surface was consistent with a "controlled" or "living" process. alpha-Bromoester moieties were attached to the grafted PGMA by reaction of the epoxide groups with 2-bromo-2-methylpropionic acid. The comb copolymer brushes were subsequently prepared via surface-initiated atom transfer radical polymerization of two hydrophilic vinyl monomers, including poly(ethylene glycol) methyl ether methacrylate and sodium salt of 4-styrenesulfonic acid. The chemical composition of the modified PTFE surfaces was characterized by X-ray photoelectron spectroscopy.

Amidine-Functionalized Poly(2-vinyl-4,4-dimethylazlactone) for Selective and Efficient CO 2 Fixing

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

Barkakaty, Balaka; Browning, Katie L.; Sumpter, Bobby

Development of novel polymeric materials capable of efficient CO 2 capture and separation under ambient conditions is crucial for cost-effective and practical industrial applications. Here we report the facile synthesis of a new CO 2-responsive polymer through post-polymerization modification of poly(2 vinyl-4,4-dimethylazlactone) (PVDMA). The reactive pendant azlactone groups of PVDMA are easily modified with 4-(N-methyltetrahydropyrimidine) benzyl alcohol (PBA) without any by-product formation. FTIR and TGA experiments show the new PBA functionalized polymer powder can reversibly capture CO 2 at room temperature and under atmospheric pressure. CO2 capture was selective, showing a high fixing efficiency even with a mixed gas systemmore » (20% CO 2, 80% N 2) similar to flue gas. CO 2 release occurred at room temperature and release profiles were investigated as a function of temperature. Density Functional Theory (DFT) calculations coupled with modeling and simulation reveal the presence of two CO 2 binding sites in the PBA functionalized polymer resulting in a two-step CO 2 release at room temperature. Finally, we find that the ease of material preparation, high fixing efficiency, and robust release characteristics suggest that post-polymerization modification may be a useful route to designing new materials for CO 2 capture.« less

Amidine-Functionalized Poly(2-vinyl-4,4-dimethylazlactone) for Selective and Efficient CO 2 Fixing

DOE PAGES

Barkakaty, Balaka; Browning, Katie L.; Sumpter, Bobby; ...

2016-02-12

Development of novel polymeric materials capable of efficient CO 2 capture and separation under ambient conditions is crucial for cost-effective and practical industrial applications. Here we report the facile synthesis of a new CO 2-responsive polymer through post-polymerization modification of poly(2 vinyl-4,4-dimethylazlactone) (PVDMA). The reactive pendant azlactone groups of PVDMA are easily modified with 4-(N-methyltetrahydropyrimidine) benzyl alcohol (PBA) without any by-product formation. FTIR and TGA experiments show the new PBA functionalized polymer powder can reversibly capture CO 2 at room temperature and under atmospheric pressure. CO2 capture was selective, showing a high fixing efficiency even with a mixed gas systemmore » (20% CO 2, 80% N 2) similar to flue gas. CO 2 release occurred at room temperature and release profiles were investigated as a function of temperature. Density Functional Theory (DFT) calculations coupled with modeling and simulation reveal the presence of two CO 2 binding sites in the PBA functionalized polymer resulting in a two-step CO 2 release at room temperature. Finally, we find that the ease of material preparation, high fixing efficiency, and robust release characteristics suggest that post-polymerization modification may be a useful route to designing new materials for CO 2 capture.« less

New high-frequency weldable polyolefin films.

PubMed

Kelch, R

2000-05-01

There is an increasing desire for plastic films that can be sealed using high-frequency energy. Tests on new high-frequency polyolefin film structures are reported, which compare them with the characteristics and performance of poly(vinyl chloride), ethylene-vinyl acetate and thermoplastic polyurethane films.

Multi-stage Mass Spectrometry of Poly(vinyl pyrrolidone) and Its Vinyl Succinimide Copolymer Formed upon Exposure to Sodium Hypochlorite

PubMed Central

Fouquet, Thierry; Torimura, Masaki; Sato, Hiroaki

2016-01-01

The degradation routes of poly(vinyl pyrrolidone) (PVP) exposed to sodium hypochlorite (bleach) have been previously investigated using chemical analyses such as infrared spectroscopy. So far, no reports have proposed mass spectrometry (MS) as an alternative tool despite its capability to provide molecular and structural information using its single stage electrospray (ESI) or matrix assisted laser desorption ionization (MALDI) and multi stage (MSn) configurations, respectively. The present study thus reports on the characterization of PVP after its exposure to bleach by high resolution MALDI spiralTOF-MS and Kendrick mass defect analysis providing clues as to the formation of a vinyl pyrrolidone/vinyl succinimide copolymeric degradation product. A thorough investigation of the fragmentation pathways of PVP adducted with sodium and proton allows one main route to be described—namely the release of the pyrrolidone pendant group in a charge remote and charge driven mechanism, respectively. Extrapolating this fragmentation pathway, the oxidation of vinyl pyrrolidone into vinyl succinimide hypothesized from the single stage MS is validated by the detection of an alternative succinimide neutral loss in lieu of the pyrrolidone release in the ESI-MSn spectra of the aged PVP sample. It constitutes an example of application of multi-stage mass spectrometry for the characterization of the degradation of polymeric samples at a molecular level. PMID:27800293

Performances of a portable electrospinning apparatus.

PubMed

Mouthuy, Pierre-Alexis; Groszkowski, Lukasz; Ye, Hua

2015-05-01

To demonstrate that portable electrospinning devices can spin a wide range of polymers into submicron fibres and provide a mesh quality comparable to those produced with benchtop machines. We have designed a small, battery-operated electrospinning apparatus which enables control over the voltage and the flow rate of the polymer solution via a microcontroller. It can be used to electrospin a range of commonly used polymers including poly(ε-caprolactone), poly(p-dioxanone), poly(lactic-co-glycolic acid), poly(3-hydroxybutyrate), poly(ethylene oxide), poly(vinyl acohol) and poly(vinyl butyral). Moreover, electrospun meshes are produced with a quality comparable to a benchtop machine. We also show that the portable apparatus is able to electrospray beads and microparticles. Finally, we highlight the potential of the device for wound healing applications by demonstrating the possibility of electrospinning onto pig and human skins. Portable electrospinning devices are still at an early stage of development but they could soon become an attractive alternative to benchtop machines, in particular for uses that require mobility and a higher degree of flexibility, such as for wound healing applications.

A Ballistic Material Model for Cross-Plied Unidirectional Ultra-High Molecular-Weight Polyethylene Fiber-Reinforced Armor-Grade Composites

DTIC Science & Technology

2008-01-01

strength polymeric fibers such as aramid (e.g. Kevlar ®, Twaron®, etc.) or oriented polyethy- lene fibers (e.g. Spectra®, Dyneema®, etc.) with an... phenolic -poly-vinyl-butyral resin and on 0◦/90◦ cross- plied oriented polyethylene fiber-reinforced vinyl-ester resin are widely used in hard personnel...are: (a) poly-aramids (e.g. Kevlar ®, Twaron®, Technora®); (b) highly oriented ultra-highmolecular-weight polyethylene, UHMWPE (e.g. Spectra®, Dyneema

Effect of borax concentration on the structure of Poly(Vinyl Alcohol) gels

NASA Astrophysics Data System (ADS)

Lawrence, Mathias B.; Desa, J. A. E.; Aswal, V. K.

2012-06-01

Poly(Vinyl Alcohol) hydrogels cross-linked with varying concentrations of borax have been studied using Small-Angle Neutron Scattering and X-Ray Diffraction. The intensity of scattering increases with borax concentration from 1 mg/ml up to 2 mg/ml and falls thereafter for 4 mg/ml, increasing again for a concentration of 10 mg/ml. The mesoscopic structural changes that cause these trends in the SANS data are in keeping with the variations in the X-ray diffraction patterns pertaining to structures within the PVA chains.

Diffraction efficiency study of holographic gratings in dichromated poly(vinyl alcohol) NiCl II•6H IIO doped

NASA Astrophysics Data System (ADS)

Fontanilla-Urdaneta, R. C.; Hernández-Garay, M. P.; Olivares-Pérez, A.; Páez-Trujillo, G.; Fuentes-Tapia, I.

2008-02-01

Experimental results to the saturation and diffraction efficiency from holographic gratings are presented in this investigation. The experiments were carried out during real time holographic gratings formation. Dichromated poly(vinyl alcohol) was doped with nickel(II) chloride hexahydrate and it is used like optical material. The influence of the hologram parameters to get the maximum diffraction efficiency is studied at room conditions. This study contributes to get more information about the behavior of this material for holographic gratings recording.

Volatile out gassing characteristics of highly filled ethylene vinyl acetate binder materials: Gas phase infra-red spectroscopy

DOE PAGES

Patel, Mogon; Bowditch, Martin; Jones, Ben; ...

2012-12-08

Gas phase Infra-red (IR) spectroscopy has been used to investigate volatile out gassing properties of highly filled poly (ethylene-co-vinyl acetate) materials. In these studies, a Scout-EN TM heated gas cell was interfaced to a vacuum FTIR spectrometer, and the quantification of evolved species was achieved through calibration of the gas cell with certified gas standards. The volatile out gassing properties were monitored as a function of time during storage at 75°C under vacuum conditions (< 1mbar). Acetic acid, carbon dioxide and water were identified as the major out gassing products through IR absorption peaks at 1797, 2354 and 3853 cmmore » -1, respectively. We present a comparison of three highly filled poly (ethyleneco- vinyl acetate) resins.« less

Health hazards in the production and processing of some fibers, resins, and plastics in Bulgaria.

PubMed Central

Spassovski, M

1976-01-01

Results of the toxicological studies of working conditions, general and professional morbidity, and complex examinations carried out on workers engaged in the production of polyamides, polyacrylonitrile fibers, polyester fibers and poly (vinyl chloride) resin, urea-formaldehyde glue, glass fibre materials and polyurethane resins are given. An extremely high occupational hazard for workers in the production of poly (vinyl chloride) resin and porous materials from polyurethane resins and urea-formaldehyde glue has been established. Cases of vinyl chloride disease, poisoning from formaldehyde, isocyanates, and styrene were noted. Prophylactic measures were taken in Bulgaria to lessen the occupational hazard in the productions as set forth included limitation of the work day to 6 hr, free food, additional bonus and leave, and annual physical examinations of workers. PMID:1026405

Effects of Prenatal Exposure to Phthalates

ERIC Educational Resources Information Center

Johnson, Laurie A.

2012-01-01

The purpose of this review of literature is to examine the association of phthalate exposure with development. Phthalates are chemical compounds used in poly-vinyl chloride, PVC; vinyl flooring, cosmetics, shampoo, air fresheners, soft plastic items, intravenous tubing, food packaging and wraps, textiles, paints, cleaning products and detergents.…

The development and characterization of degradable poly(vinyl ester) and poly(vinyl ester)/PEO block copolymers

NASA Astrophysics Data System (ADS)

Lipscomb, Corinne Elizabeth

The development of biodegradable materials is a challenging and important problem in polymer science. A review of the state of the art in degradable materials is presented, which reveals that current biodegradable materials do not exhibit the thermal or mechanical properties necessary for widespread applications. One strategy for toughening polymeric materials, which has previously been applied to non-degradable thermoplastics and thermoplastic elastomers, is the formation of block copolymers. Poly(vinyl esters) (PVE) homopolymers are known to have a wide range of properties, but PVE block copolymers comprise a class of inexpensive and (bio)degradable materials that were previously unknown. Therefore, the synthesis and properties of these block copolymers were explored in an effort to develop robust degradable materials. This thesis research probes the reaction conditions necessary for the reversible-addition fragmentation chain transfer (RAFT) polymerization and chain extension reactions of vinyl ester monomers. PVE di- and triblock copolymers are synthesized and studied, and the triblock copolymers display extremely poor toughness due to their relatively low molecular weights in light of the high entanglement molecular weight of the poly(vinyl acetate) center block. Attempts to improve the mechanical properties of these materials focus on the incorporation of poly(ethylene oxide) (PEO) as a low entanglement molecular weight and biocompatible center block in PVE-containing triblock copolymers. Depending on the choice of PVE endblocks and the overall polymer composition, crystallization of the PEO block can be controlled, confined, or inhibited. Polymers in which PEO crystallization is completely inhibited exhibit enhanced mechanical properties and behave as weak thermoplastics. In order to understand the relationship between the inhibition of PEO crystallization and the mechanical properties of PVE/PEO materials, these polymers were studied using dynamic mechanical spectroscopy, wide angle X-ray scattering, small angle X-ray scattering, differential scanning calorimetry, and uniaxial tensile tests. By combining insights gained from these techniques, a complex picture emerges that explains the enhanced mechanical properties of these materials based on the type and location of thermal transitions, amorphous PEO entanglements, and the strain-induced crystallization of PEO. This work represents an important step toward developing robust materials with tunable properties containing (bio)degradable components.

Glucose biosensor based on the immobilization of glucose oxidase on electrochemically synthesized polypyrrole-poly(vinyl sulphonate) composite film by cross-linking with glutaraldehyde.

PubMed

Colak, Ozlem; Yaşar, Ahmet; Cete, Servet; Arslan, Fatma

2012-10-01

In this study, a novel amperometric glucose biosensor was developed by immobilizing glucose oxidase (GOX) by cross-linking via glutaraldehyde on electrochemically polymerized polypyrrole-poly(vinyl sulphonate) (PPy-PVS) films on the surface of a platinum (Pt) electrode. Electropolymerization of pyrrole and poly(vinyl sulphonate) on the Pt surface was carried out with an electrochemical cell containing pyrrole and poly(vinyl sulphonate) by cyclic voltammetry between -1.0 and + 2.0 V (vs.Ag/AgCl) at a scan rate of 50 mV/s upon the Pt electrode. The amperometric determination was based on the electrochemical detection of H(2)O(2) generated in enzymatic reaction of glucose. Determination of glucose was carried out by the oxidation of enzymatically produced H(2)O(2) at 0.4 V vs. Ag/AgCl. The effects of pH and temperature were investigated and optimum parameters were found to be 7.5 and 65°C, respectively. The effect of working potential was investigated and optimum potential was determined to be 0.4 V. The operational stability of the enzyme electrode was also studied. The response of the PPy/PVS-GOX glucose biosensor exhibited good reproducibility with a relative standard deviation (RSD) of 2.48%. The glucose biosensor retained 63% of initial activity after 93 days when stored in 0.1 M phosphate buffer solution of pH 7.5 at 4°C. With the low operating potential, the biosensor demonstrated little interference from the possible interferants.

Uranium Adsorbent Fibers Prepared by Atom-Transfer Radical Polymerization (ATRP) from Poly(vinyl chloride)- co -chlorinated Poly(vinyl chloride) (PVC- co -CPVC) Fiber

DOE PAGES

Brown, Suree; Yue, Yanfeng; Kuo, Li-Jung; ...

2016-03-11

The need to secure future supplies of energy attracts researchers in several countries to a vast resource of nuclear energy fuel: uranium in seawater (estimated at 4.5 billion tons in seawater). In this study, we developed effective adsorbent fibers for the recovery of uranium from seawater via atom-transfer radical polymerization (ATRP) from a poly-(vinyl chloride)-co-chlorinated poly(vinyl chloride) (PVC-co-CPVC) fiber. ATRP was employed in the surface graft polymerization of acrylonitrile (AN) and tert-butyl acrylate (tBA), precursors for uranium-interacting functional groups, from PVC-co-CPVC fiber. The [tBA]/[AN] was systematically varied to identify the optimal ratio between hydrophilic groups (from tBA) and uranyl-binding ligandsmore » (from AN). The best performing adsorbent fiber, the one with the optimal [tBA]/[AN] ratio and a high degree of grafting (1390%), demonstrated uranium adsorption capacities that are significantly greater than those of the Japan Atomic Energy Agency (JAEA) reference fiber in natural seawater tests (2.42 3.24 g/kg in 42 days of seawater exposure and 5.22 g/kg in 49 days of seawater exposure, versus 1.66 g/kg in 42 days of seawater exposure and 1.71 g/kg in 49 days of seawater exposure for JAEA). Lastly, adsorption of other metal ions from seawater and their corresponding kinetics were also studied. The grafting of alternative monomers for the recovery of uranium from seawater is now under development by this versatile technique of ATRP.« less

Adsorption of poly(vinyl alcohol) from water to a hydrophobic surface: effects of molecular weight, degree of hydrolysis, salt, and temperature.

PubMed

Kozlov, Mikhail; McCarthy, Thomas J

2004-10-12

The adsorption of poly(vinyl alcohol) (PVOH) from aqueous solutions to a silicon-supported fluoroalkyl monolayer is described. Thickness, wettability, and roughness of adsorbed films are studied as a function of polymer molecular weight, degree of hydrolysis (from the precursor, poly(vinyl acetate)), polymer concentration, salt type and concentration, and temperature. The data suggest a two-stage process for adsorption of the polymer: physisorption due to a hydrophobic effect (decrease in interfacial free energy) and subsequent stabilization of the adsorbed layer due to crystallization of the polymer. Adsorption of lower-molecular-weight polymers results in thicker films than those prepared with a higher molecular weight; this is ascribed to better crystallization of more mobile short chains. Higher contents of unhydrolyzed acetate groups on the poly(vinyl alcohol) chain lead to thicker adsorbed films. Residual acetate groups partition to the outermost surface of the films and determine wettability. Salts, including sodium chloride and sodium sulfate, promote adsorption, which results in thicker films; at the same time, their presence over a wide concentration range leads to formation of rough coatings. Sodium thiocyanate has little effect on PVOH adsorption, only slightly reducing the thickness in a 2 M salt solution. Increased temperature promotes adsorption in the presence of salt, but has little effect on salt-free solutions. Evidently, higher temperatures favor adsorption but cause crystallization to be less thermodynamically favorable. These competing effects result in the smoothest coatings being formed in an intermediate temperature range. Copyright 2004 American Chemical Society

Uranium Adsorbent Fibers Prepared by Atom-Transfer Radical Polymerization (ATRP) from Poly(vinyl chloride)- co -chlorinated Poly(vinyl chloride) (PVC- co -CPVC) Fiber

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

Brown, Suree; Yue, Yanfeng; Kuo, Li-Jung

The need to secure future supplies of energy attracts researchers in several countries to a vast resource of nuclear energy fuel: uranium in seawater (estimated at 4.5 billion tons in seawater). In this study, we developed effective adsorbent fibers for the recovery of uranium from seawater via atom-transfer radical polymerization (ATRP) from a poly-(vinyl chloride)-co-chlorinated poly(vinyl chloride) (PVC-co-CPVC) fiber. ATRP was employed in the surface graft polymerization of acrylonitrile (AN) and tert-butyl acrylate (tBA), precursors for uranium-interacting functional groups, from PVC-co-CPVC fiber. The [tBA]/[AN] was systematically varied to identify the optimal ratio between hydrophilic groups (from tBA) and uranyl-binding ligandsmore » (from AN). The best performing adsorbent fiber, the one with the optimal [tBA]/[AN] ratio and a high degree of grafting (1390%), demonstrated uranium adsorption capacities that are significantly greater than those of the Japan Atomic Energy Agency (JAEA) reference fiber in natural seawater tests (2.42 3.24 g/kg in 42 days of seawater exposure and 5.22 g/kg in 49 days of seawater exposure, versus 1.66 g/kg in 42 days of seawater exposure and 1.71 g/kg in 49 days of seawater exposure for JAEA). Lastly, adsorption of other metal ions from seawater and their corresponding kinetics were also studied. The grafting of alternative monomers for the recovery of uranium from seawater is now under development by this versatile technique of ATRP.« less

Uranium Adsorbent Fibers Prepared by Atom-Transfer Radical Polymerization (ATRP) from Poly(vinyl chloride)- co -chlorinated Poly(vinyl chloride) (PVC- co -CPVC) Fiber

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

Brown, Suree; Yue, Yanfeng; Kuo, Li-Jung

The need to secure future supplies of energy attracts researchers in several countries to a vast resource of nuclear energy fuel: uranium in seawater (estimated at 4.5 billion tons in seawater). In this study, we developed effective adsorbent fibers for the recovery of uranium from seawater via atom-transfer radical polymerization (ATRP) from a poly- (vinyl chloride)-co-chlorinated poly(vinyl chloride) (PVC-co-CPVC) fiber. ATRP was employed in the surface graft polymerization of acrylonitrile (AN) and tert-butyl acrylate (tBA), precursors for uranium-interacting functional groups, from PVC-co-CPVC fiber. The [tBA]/[AN] was systematically varied to identify the optimal ratio between hydrophilic groups (from tBA) and uranyl-bindingmore » ligands (from AN). The best performing adsorbent fiber, the one with the optimal [tBA]/[AN] ratio and a high degree of grafting (1390%), demonstrated uranium adsorption capacities that are significantly greater than those of the Japan Atomic Energy Agency (JAEA) reference fiber in natural seawater tests (2.42-3.24 g/kg in 42 days of seawater exposure and 5.22 g/kg in 49 days of seawater exposure, versus 1.66 g/kg in 42 days of seawater exposure and 1.71 g/kg in 49 days of seawater exposure for JAEA). Adsorption of other metal ions from seawater and their corresponding kinetics were also studied. The grafting of alternative monomers for the recovery of uranium from seawater is now under development by this versatile technique of ATRP.« less

Enhanced Stability and Bioconjugation of Photo-cross-linked Polystyrene-Shell, Au-Core Nanoparticles

PubMed Central

Chen, Ying; Cho, Juhee; Young, Alexi; Taton, T. Andrew

2008-01-01

Encapsulating Au nanoparticles within a shell of photo-cross-linked block copolymer surfactant dramatically improves the physical and chemical stability of the nanoparticles, particularly when they are applied as bioconjugates. Photo-cross-linkable block copolymer amphiphiles [polystyrene-co-poly(4-vinyl benzophenone)]-block-poly(acrylic acid) [(PS-co-PVBP)-b-PAA] and [poly(styrene)-co-poly(4-vinyl benzophenone)]-block-poly(ethylene oxide) [(PS-co-PVBP)-b-PEO] were assembled around Au nanoparticles ranging from 12 nm to 108 nm in diameter. UV irradiation cross-linked the PVBP groups on the polymer to yield particles that withstood extremes of temperature, ionic strength, and chemical etching. Streptavidin was attached to [PS-co-PVBP]-b-PAA coated particles using the same noncovalent and covalent conjugation protocols used to bind biomolecules to divinylbenzene-crosslinked polystyrene microspheres. We expect that these particles will be useful as plasmonic, highly light-scattering and light-absorbing analogs to fluorescently labeled polystyrene nanospheres. PMID:17530871

Polyazulene based materials for heavy metal ions detection

NASA Astrophysics Data System (ADS)

Oprisanu, A.; Ungureanu, E. M.; Isopescu, R.; Birzan, L.; Mihai, M.; Vasiliu, C.

2017-06-01

Azulene is a special monomer used to functionalize electrodes, due to its spontaneous electron drift from the seven-membered ring to the five-membered ring. The seven-membered ring of the molecule may act as electron acceptor, while the five-membered ring - as electron donor. This leads to very attractive properties for the synthesis of functional advanced materials like: materials with nonlinear optical and photorefractive properties, cathode materials for lithium batteries, or light emitting diodes based on organic materials. Azulene derivatives have been used rarely to the metal ions electroanalysis. Our study concerns the synthesis and electrochemical characterization of a new azulene based monomer 4-(azulen-1-yl)-2,6-bis((E)-2-(thiophen-3-yl)vinyl)pyridine (L). L has been used to obtain modified electrodes by electrochemical polymerization. PolyL films modified electrodes have been characterized by cyclic voltammetry in ferrocene solutions. The complexing properties of polyL based functional materials have been investigated towards heavy metals (Pb, Cd Hg, Cu) by preconcentration - anodic stripping technique in order to analyze the content of these cations from water samples.

Effects of cyclic structure inhibitors on the morphology and growth of tetrahydrofuran hydrate crystals

NASA Astrophysics Data System (ADS)

Li, Sijia; Wang, Yanhong; Lang, Xuemei; Fan, Shuanshi

2013-08-01

Morphology and growth of hydrate crystals with cyclic structure inhibitors at a hydrate-liquid interface were directly observed through a microscopic manipulating apparatus. Tetrahydrofuran (THF) hydrate was employed as an objective. The effects of four kind of cyclic structure inhibitors, polyvinylpyrrolidone (PVP), poly(N-vinyl-2-pyrrolidone-co-2-vinyl pyridine) (PVPP), poly(2-vinyl pyridine-co-N-vinylcaprolactam) (PVPC) and poly(N-vinylcaprolactam) (PVCap), were investigated. Morphological patterns between each hydrate crystal growth from hydrate-liquid interface into droplet were found differ significantly. Lamellar structure growth of hydrate crystal was observed without inhibitor, while with PVP was featheriness-like, PVPP was like long dendritic crystal, PVPC was Mimosa pudica leaf-like and PVCap was like weeds. The growth rate of hydrate crystal without inhibitor was 0.00498 mm3/s, while with PVPP, PVPC and PVCap, were 0.00339 mm3/s, 0.00350 mm3/s, 0.00386 mm3/s and 0.00426 mm3/s, respectively. Cyclic structure inhibitors can decrease the growth rate, degree of reduction in growth rate of hydrate crystals decrease with the increase of cylinder number.

Rise and Fall: Poly(phenyl vinyl ketone) Photopolymerization and Photodegradation under Visible and UV Radiation.

PubMed

Reeves, Jennifer A; Allegrezza, Michael L; Konkolewicz, Dominik

2017-07-01

Vinyl ketone polymers, including phenyl vinyl ketone (PVK), are an important class of polymers due to their ability to degrade upon irradiation with ultraviolet light which makes them useful for a variety of applications. However, traditional radical methods for synthesizing PVK polymers give rise to poor control or are unable to produce block copolymers. This work uses reversible addition-fragmentation chain transfer polymerization (RAFT) and photochemistry to polymerize PVK. When visible blue radiation of 440 ± 10 nm is used as the light source for the photopolymerization, rapid polymerization and well-defined polymers are created. This RAFT method uses PVK as both monomer and radical initiator, exciting the PVK mono-mer by 440 ± 10 nm irradiation to avoid the use of an additional radical initiator. Once the poly-mer is synthesized, it is stable against degradation by blue light (440 ± 10 nm), but upon exposure to ultraviolet (UV) radiation (310 ± 20 nm) significant decrease in molecular weight is observed. The degradation is observed for all poly(PVK) materials synthesized. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Analysis of friction between articular cartilage and polyvinyl alcohol hydrogel artificial cartilage.

PubMed

Li, Feng; Wang, Anmin; Wang, Chengtao

2016-05-01

Many biomaterials are being used to repair damaged articular cartilage. In particular, poly vinyl alcohol hydrogel has similar mechanical properties to natural cartilage under compressive and shearing loading. Here, three-factor and two-level friction experiments and long-term tests were conducted to better evaluate its tribological properties. The friction coefficient between articular cartilage and the poly vinyl alcohol hydrogel depended primarily on the three factors of load, speed, and lubrication. When the speed increased from 10 to 20 mm/s under a load of 10 N, the friction coefficient increased from 0.12 to 0.147. When the lubricant was changed from Ringer's solution to a hyaluronic acid solution, the friction coefficient decreased to 0.084 with loads as high as 22 N. The poly vinyl alcohol hydrogel was severely damaged and lost its top surface layers, which were transferred to the articular cartilage surface. Wear was observed in the surface morphologies, which indicated the occurrence of surface adhesion of bovine cartilage. Surface fatigue and adhesive wear was the dominant wear mechanism.

Structural analysis, and antioxidant and antibacterial properties of chitosan-poly (vinyl alcohol) biodegradable films.

PubMed

Hajji, Sawssen; Chaker, Achraf; Jridi, Mourad; Maalej, Hana; Jellouli, Kemel; Boufi, Sami; Nasri, Moncef

2016-08-01

The development and characterization of biodegradable blend films based on chitosan and poly (vinyl alcohol) for possible use in a variety of biological activities are reported. Fourier transform infrared spectroscopy (FTIR) spectra of chitosan-poly (vinyl alcohol) (Ch/PVA) films showed characteristics peaks shifting to a lower frequency range due to hydrogen bonding between -OH of PVA and -NH2 of chitosan. The chitosan and PVA polymers presented good compatibility. The morphology study of chitosan and composite films showed a compact and homogenous structure. The tensile strength and elongation at break increased with PVA content. In fact, the highest tensile strength and elongation at break (53.58 MPa and 454 %) occurs with pure PVA film. The results showed that PVA incorporation in the blends contributes to increase the intermolecular interactions, thus improving the mechanical properties. In addition, the prepared films demonstrated high antioxidant activities monitored by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging, reducing power, and β-carotene bleaching activity. Nevertheless, PVA addition reduced antioxidant and antibacterial activities against Gram-positive and Gram-negative bacteria tested.

Silk fibroin/poly (vinyl alcohol) blend scaffolds for controlled delivery of curcumin

PubMed Central

Li, Xiaomeng; Qin, Jinli; Ma, Jun

2015-01-01

A silk fibroin/poly (vinyl alcohol) porous scaffold with a water vapor transmission rate of 2125 ± 464 g/m2/day has been developed via thermally induced phase separation (gelation) and freeze-drying process. A hierarchical architecture of micropores and nanofibers was observed inside the scaffolds, and the related structures were analyzed. The viability and proliferation of 3T3 fibroblasts were examined, which indicated that the scaffolds exerted low cytotoxicity. After loading curcumin, the scaffolds can suppress the growth of 3T3 fibroblasts. The release behavior of curcumin from the scaffolds was investigated. At pH = 7.2, the release profiles showed no significant difference for the loading amounts of 0.5 mg and 0.25 mg per sample. Meanwhile, the cumulative amount of released drug at pH = 5.7 was significantly more than that in neutral solution due to more degradation of the scaffolds. It was suggested that the silk fibroin/poly (vinyl alcohol) blend scaffolds could be potentially used as wound dressing materials. PMID:26816634

In vitro mechanical fatigue behavior of poly-ɛ-caprolactone macroporous scaffolds for cartilage tissue engineering: Influence of pore filling by a poly(vinyl alcohol) gel.

PubMed

Panadero, J A; Vikingsson, L; Gomez Ribelles, J L; Lanceros-Mendez, S; Sencadas, V

2015-07-01

Polymeric scaffolds used in regenerative therapies are implanted in the damaged tissue and submitted to repeated loading cycles. In the case of articular cartilage engineering, an implanted scaffold is typically subjected to long-term dynamic compression. The evolution of the mechanical properties of the scaffold during bioresorption has been deeply studied in the past, but the possibility of failure due to mechanical fatigue has not been properly addressed. Nevertheless, the macroporous scaffold is susceptible to failure after repeated loading-unloading cycles. In this work fatigue studies of polycaprolactone scaffolds were carried by subjecting the scaffold to repeated compression cycles in conditions simulating the scaffold implanted in the articular cartilage. The behavior of the polycaprolactone sponge with the pores filled with a poly(vinyl alcohol) gel simulating the new formed tissue within the pores was compared with that of the material immersed in water. Results were analyzed with Morrow's criteria for failure and accurate fittings are obtained just up to 200 loading cycles. It is also shown that the presence of poly(vinyl alcohol) increases the elastic modulus of the scaffolds, the effect being more pronounced with increasing the number of freeze/thawing cycles. © 2014 Wiley Periodicals, Inc.

Poly(vinyl acetate)/clay nanocomposite materials for organic thin film transistor application.

PubMed

Park, B J; Sung, J H; Park, J H; Choi, J S; Choi, H J

2008-05-01

Nanocomposite materials of poly(vinyl acetate) (PVAc) and organoclay were fabricated, in order to be utilized as dielectric materials of the organic thin film transistor (OTFT). Spin coating condition of the nanocomposite solution was examined considering shear viscosity of the composite materials dissolved in chloroform. Intercalated structure of the PVAc/clay nanocomposites was characterized using both wide-angle X-ray diffraction and TEM. Fracture morphology of the composite film on silicon wafer was also observed by SEM. Dielectric constant (4.15) of the nanocomposite materials shows that the PVAc/clay nanocomposites are applicable for the gate dielectric materials.

A Study of Cross-linked Regions of Poly(Vinyl Alcohol) Gels by Small-Angle Neutron Scattering

NASA Astrophysics Data System (ADS)

Lawrence, Mathias B.; Desa, J. A. E.; Aswal, V. K.

2011-07-01

A poly(vinyl alcohol)-borax cross-linked hydrogel has been studied by Small Angle Neutron Scattering as a function of borax concentration in the wave-vector transfer (Q) range of 0.017 Å-1 to 0.36 Å-1. It is found that as the concentration of borax increases, so does the intensity of scattering in this range. Beyond a borax concentration of 2 mg/ml, the increase in cross-linked PVA chains leads to cross-linked units larger than 150 Å as evidenced by a reduction in intensity in the lower Q region.

Copper Doped Methylene Blue Sensitized Poly(vinyl alcohol)-Acrylamide Films for Stable Diffraction Efficiency

NASA Astrophysics Data System (ADS)

John, Beena Mary; Joseph, Rani; Sreekumar, K.; Sudha Kartha, C.

2006-11-01

Copper doped methylene blue sensitized poly(vinyl alcohol) (MBPVA)-acrylamide films were fabricated to improve the storage life of recorded gratings. The films were fabricated using gravity settling method and the copper chloride concentration was optimized as 3.18× 10-3 mol/l for a dye concentration of 6.2× 10-4 mol/l. The gratings recorded on the optimized film constitution could be stored for months with stable diffraction efficiency (24%) without any chemical or thermal fixing techniques. The resolution of the material is found to be unaffected with the addition of copper chloride.

Novel Biocompatible Thermoresponsive Poly(N-vinyl Caprolactam)/Clay Nanocomposite Hydrogels with Macroporous Structure and Improved Mechanical Characteristics.

PubMed

Shi, Kun; Liu, Zhuang; Yang, Chao; Li, Xiao-Ying; Sun, Yi-Min; Deng, Yi; Wang, Wei; Ju, Xiao-Jie; Xie, Rui; Chu, Liang-Yin

2017-07-05

Poly(N-vinyl caprolactam) (PVCL) hydrogels usually suffer from the imporous structure and poor mechanical characteristics as well as the toxicity of cross-linkers, although PVCL itself is biocompatible. In this paper, novel biocompatible thermoresponsive poly(N-vinyl caprolactam)/clay nanocomposite (PVCL-Clay) hydrogels with macroporous structure and improved mechanical characteristics are developed for the first time. The macroporosity in the hydrogel is introduced by using Pickering emulsions as templates, which contain N-vinyl caprolactam (VCL) monomer as dispersed phase and clay sheets as stabilizers at the interface. After polymerization, macropores are formed inside the hydrogels with the residual unreacted VCL droplets as templates. The three-dimensional PVCL polymer networks are cross-linked by the clay nanosheets. Due to the nanocomposite structure, the hydrogel exhibits better mechanical characteristics in comparison to the conventional PVCL hydrogels cross-linked by N,N'-methylene diacrylamide (BIS). The prepared PVCL-Clay hydrogel possesses remarkable temperature-responsive characteristics with a volume phase transition temperature (VPTT) around 35 °C, and provides a feasible platform for cell culture. With macroporous structure and good mechanical characteristics as well as flexible assembly performance, the proposed biocompatible thermoresponsive PVCL-Clay nanocomposite hydrogels are ideal material candidates for biomedical, analytical, and other applications such as entrapment of enzymes, cell culture, tissue engineering, and affinity and displacement chromatography.

Ferrocene bound poly(vinyl chloride) as ion to electron transducer in electrochemical ion sensors.

PubMed

Pawlak, Marcin; Grygolowicz-Pawlak, Ewa; Bakker, Eric

2010-08-15

We report here on the synthesis of poly(vinyl chloride) (PVC) covalently modified with ferrocene groups (FcPVC) and the electrochemical behavior of the resulting polymeric membranes in view of designing all solid state voltammetric ion sensors. The Huisgen cycloaddition ("click chemistry") was found to be a simple and efficient method for ferrocene attachment. A degree of PVC modification with ferrocene groups between 1.9 and 6.1 mol % was achieved. The chemical modification of the PVC backbone does not significantly affect the ion-selective properties (selectivity, mobility, and solvent casting ability) of potentiometric sensing membranes applying this polymer. Importantly, the presence of such ferrocene groups may eliminate the need for an additional redox-active layer between the membrane and the inner electric contact in all solid state sensor designs. Electrochemical doping of this system was studied in a symmetrical sandwich configuration: glassy carbon electrode |FcPVC| glassy carbon electrode. Prior electrochemical doping from aqueous solution, resulting in a partial oxidation of the ferrocene groups, was confirmed to be necessary for the sandwich configuration to pass current effectively. The results suggest that only approximately 2.3 mol % of the ferrocene groups are electrochemically accessible, likely due to surface confined electrochemical behavior in the polymer. Indeed, cyclic voltammetry of aqueous hexacyanoferrate (III) remains featureless at cathodic potentials (down to -0.5 V). This indicates that the modified membrane is not responsive to redox-active species in the sample solution, making it possible to apply this polymer as a traditional, single membrane. Yet, the redox capacity of the electrode modified with this type of membrane was more than 520 microC considering a 20 mm(2) active electrode area, which appears to be sufficient for numerous practical ion voltammetric applications. The electrode was observed to operate reproducibly, with 1% standard deviation, when applying pulsed amperometric techniques.

Novel conjugates of peptides and conjugated polymers for optoelectronics and neural interfaces

NASA Astrophysics Data System (ADS)

Bhagwat, Nandita

Peptide-polymer conjugates are a novel class of hybrid materials that take advantage of each individual component giving the opportunity to generate materials with unique physical, chemical, mechanical, optical, and electronic properties. In this dissertation peptide-polymer conjugates for two different applications are discussed. The first set of peptide-polymer conjugates were developed as templates to study the intermolecular interactions between electroactive molecules by manipulating the intermolecular distances at nano-scale level. A PEGylated, alpha-helical peptide template was employed to effectively display an array of organic chromophores (oxadiazole containing phenylenevinylene oligomers, Oxa-PPV). Three Oxa-PPV chromophores were strategically positioned on each template, at distances ranging from 6 to 17 A from each other, as dictated by the chemical and structural properties of the peptide. The Oxa-PPV modified PEGylated helical peptides (produced via Heck coupling strategies) were characterized by a variety of spectroscopic methods. Electronic contributions from multiple pairs of chromophores on a scaffold were detectable; the number and relative positioning of the chromophores dictated the absorbance and emission maxima, thus confirming the utility of these polymer--peptide templates for complex presentation of organic chromophores. The rest of the thesis is focused on using poly(3,4-alkylenedioxythiophene) based conjugated polymers as coatings for neural electrodes. This thiophene derivative is of considerable current interest for functionalizing the surfaces of a wide variety of devices including implantable biomedical electronics, specifically neural bio-electrodes. Toward these ends, copolymer films of 3,4-ethylenedioxythiophene (EDOT) with a carboxylic acid functional EDOT (EDOTacid) were electrochemically deposited and characterized as a systematic function of the EDOTacid content (0, 25, 50, 75, and 100%). The chemical surface characterization of the films confirmed the presence of both EODT and EDOTacid units. Cyclic voltammetry showed that the films had comparable charge storage capacities regardless of their composition. The morphology of the films varied depending on the monomer feed ratio. Thus we were able to develop a method for synthesizing electrically active carboxylic acid functional poly(3,4-ethylenedioxythiophene) copolymer films with tunable hydrophilicities and surface morphologies. For longer lifetime devices incorporating a biomolecule via covalent immobilization techniques are preferred over physical adsorption or entrapment. We took advantage of the carboxylic acid group on the PEDOTacid copolymer films to modify the surface of these films with a laminin based peptide, the nonapeptide sequence CDPGYIGSR. XPS and toluidine blue O assay proved the presence of the peptide on the surface and electrochemical analysis demonstrated unaltered properties of the peptide modified films. The bioactivity of the peptide along with the need of a spacer molecule for cell adhesion and differentiation was tested using the rat pheochromocytoma (PC12) cells. Films modified with the longest poly(ethylene glycol) spacer used in this study, a 3 nm long molecule, demonstrated the best attachment and neurite outgrowth compared to films with peptides with no spacer and a 1 nm spacer, PEG3. The films with PEG10-CDPGYISGR covalently modified to the surface demonstrated 11.5% neurite expression with the mean neurite length of 90 microm. Along with the acid functionalized PEDOT films, vinyl terminated ProDOT films were also investigated as coatings for neural electrodes. The vinyl group was successfully modified with a RGD peptide via thiol-ene click chemistry. Both the acid and vinyl functional conducting polymer films provide an effective approach to biofunctionalize conducting polymer films.

Polyethylene Glycol-Poly(2-Methyl-5-Vinyl Tetrazole) Polymer Blend (A desensitizing Binder for Propellants and Explosives)

DTIC Science & Technology

1989-03-01

PVA, CTBN , PBAA, PMMA, etc. As a test of this predictability, we dissolved a vinyl acetate polymer in THF, and then added PMVT, and did succeed in...Polyvinyl acetate CTBN Carboxy terminated butadiene acrylonitrile PBAA Polybutadiene acrylic acid PMMA Polymethyl. methacrylate THF Tetrahydrofuran NMR

Characterisation and in vitro stability of low-dose, lidocaine-loaded poly(vinyl alcohol)-tetrahydroxyborate hydrogels.

PubMed

Abdelkader, D H; Osman, M A; El-Gizawy, S A; Faheem, A M; McCarron, P A

2016-03-16

Poly(vinyl alcohol) hydrogels cross-linked with the tetrahydroxyborate anion possess textural and rheological properties that can be used as novel drug-loaded vehicles for application to traumatic wounds. However, addition of soluble drug substances causes concentration-dependent phase separation and rheological changes. The aim of this work was to investigate the effect of adding a local anaesthetic, but keeping the concentration low in an attempt to prevent these changes. Cross-linked hydrogels prepared from three grades of poly(vinyl alcohol) were characterised rheologically. Temperature sweep studies showed an elevated complex viscosity upon moving from 25°C to 80°C, which remained high for 48 h following completion of the cycle. Adhesion to model dermal surfaces achieved a maximum of 2.62 N cm(-2) and were greater than that observed to epidermal substrates, with a strong dependence on the rate of detachment used during testing. An optimised formulation (6% w/w PVA (31-50; 99) and 2% w/w THB) containing lidocaine hydrochloride loaded to an upper maximum concentration of 1.5% w/w was assessed for phase separation and drug crystallisation. After six months, crystallisation was present in formulations containing 0.7% and 1.5% lidocaine HCl. Changes in pH in response to increases in lidocaine loading were low. Drug release was shown to operate via a non-Fickian process for all three concentrations, with 60% occurring after approximately 24h. It can be concluded that using a low concentration of lidocaine hydrochloride in hydrogels based on poly(vinyl alcohol) will result in crystallisation. Furthermore, these hydrogels are unlikely to induce rapid anaesthesia due to the low loading and slow release kinetics. Copyright © 2016 Elsevier B.V. All rights reserved.

Nanocomposites of phosphonic-acid-functionalized polyethylenes with inorganic quantum dots.

PubMed

Rünzi, Thomas; Baier, Moritz C; Negele, Carla; Krumova, Marina; Mecking, Stefan

2015-01-01

Insertion of diethyl vinyl phosphonates and free vinyl phosphonic acid, respectively, into [(P^O)Pd(Me)(dmso)] ((P^O) = κ(2)-P,O-Ar2PC6H4SO2O with Ar = 2-MeOC6H4) (1-dmso) occurs in a 2,1- as well as 1,2-fashion, to form a four-and a five-membered chelate [(P^O)Pd{κ(2)-C,O-CH(P(O)(OR)2)CH2CH3}] and [(P^O)Pd{κ(2)-C,O-CH2CH(P(O)(OR)2)CH3}] (R = H, Et). No decomposition or other reactions of 1 by free phosphonic acid moieties occur. Copolymerization in a pressure reactor by 1-dmso yields linear random poly(ethylene-co-diethyl vinyl phosphonate) and poly(ethylene-co-vinyl phosphonic acid). In these copolymerizations, reversible coordination of the phosphonate moieties of free monomer as well as chelate formation by incorporated monomer retards chain growth as also evidenced by relative binding studies of diethyl phosphonate towards 1. Post-polymerization emulsification of poly(ethylene-co-vinyl phosphonic acid) together with CdSe/CdS quantum dots (QDs) yields submicron (ca. 50 nm from dynamic light scattering (DLS) and transmission electron microscopy (TEM)) polymer particles with the QDs embedded in the functionalized polyethylene in a nonaggregated fashion. This embedding benefits the fluorescence behavior in terms of continuous emission and life-time as revealed by wide-field fluorescence measurements. These composite particle dispersions are employed as a ″masterbatch" together with an aqueous high density polyethylene (HDPE) dispersion to generate thin films (by spin-coating) and bulk materials (from the melt), respectively, in which the inorganic nanoparticles remain highly disperse. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A novel process for separation of hazardous poly(vinyl chloride) from mixed plastic wastes by froth flotation.

PubMed

Wang, Jianchao; Wang, Hui; Wang, Chongqing; Zhang, Lingling; Wang, Tao; Zheng, Long

2017-11-01

A novel method, calcium hypochlorite (CHC) treatment, was proposed for separation of hazardous poly(vinyl chloride) (PVC) plastic from mixed plastic wastes (MPWs) by froth flotation. Flotation behavior of single plastic indicates that PVC can be separated from poly(ethylene terephthalate) (PET), poly(acrylonitrile-co-butadiene-co-styrene) (ABS), polystyrene (PS), polycarbonate (PC) and poly(methyl methacrylate) (PMMA) by froth flotation combined with CHC treatment. Mechanism of CHC treatment was examined by contact angle measurement, scanning electron microscopy, Fourier transform infrared and X-ray photoelectron spectroscopy. Under the optimum conditions, separation of PVC from binary plastics with different particle sizes is achieved efficiently. The purity of PC, ABS, PMMA, PS and PET is greater than 96.8%, 98.5%, 98.8%, 97.4% and 96.3%, respectively. Separation of PVC from multi-plastics was further conducted by two-stage flotation. PVC can be separated efficiently from MPWs with residue content of 0.37%. Additionally, reusing CHC solution is practical. This work indicates that separation of hazardous PVC from MPWs is effective by froth flotation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Recyclable magnetic nanocluster crosslinked with poly(ethylene oxide)-block-poly(2-vinyl-4,4-dimethylazlactone) copolymer for adsorption with antibody.

PubMed

Prai-In, Yingrak; Boonthip, Chatchai; Rutnakornpituk, Boonjira; Wichai, Uthai; Montembault, Véronique; Pascual, Sagrario; Fontaine, Laurent; Rutnakornpituk, Metha

2016-10-01

Surface modification of magnetic nanoparticle (MNP) with poly(ethylene oxide)-block-poly(2-vinyl-4,4-dimethylazlactone) (PEO-b-PVDM) diblock copolymers and its application as recyclable magnetic nano-support for adsorption with antibody were reported herein. PEO-b-PVDM copolymers were first synthesized via a reversible addition-fragmentation chain-transfer (RAFT) polymerization using poly(ethylene oxide) chain-transfer agent as a macromolecular chain transfer agent to mediate the RAFT polymerization of VDM. They were then grafted on amino-functionalized MNP by coupling with some azlactone rings of the PVDM block to form magnetic nanoclusters with tunable cluster size. The nanocluster size could be tuned by adjusting the chain length of the PVDM block. The nanoclusters were successfully used as efficient and recyclable nano-supports for adsorption with anti-rabbit IgG antibody. They retained higher than 95% adsorption of the antibody during eight adsorption-separation-desorption cycles, indicating the potential feasibility in using this novel hybrid nanocluster as recyclable support in cell separation applications. Copyright © 2016 Elsevier B.V. All rights reserved.

Preparation, characterization and properties of polymer-layered silicate nanocomposites

NASA Astrophysics Data System (ADS)

Fonseca, Claudia Alencar

Nanocomposites are a relatively new class of composites, that in the polymer area typically consist of particle-filled polymers where at least one dimension of the dispersed particles is in the nanometer range. Amongst all potential nanocomposite precursors, those based on clay and layered silicates have been more widely investigated. These nanocomposites exhibit markedly improved mechanical, thermal, optical and physico-chemical properties when compared to conventional (microscale) composites. In the present work, properties of nanocomposites of Ethylene Methacrylic Acid copolymers and organically modified Montmorillonite formed from the melt was investigated. Nanocomposites of Poly(vinyl alcohol) and Montmorillonite formed from solution was also studied.

Fabrication of poly(vinyl carbazole) waveguides by oxygen ion implantation

NASA Astrophysics Data System (ADS)

Ghailane, Fatima; Manivannan, Gurusamy; Knystautas, Émile J.; Lessard, Roger A.

1995-08-01

Polymer waveguides were fabricated by ion implantation involving poly(vinyl carbazole) films. This material was implanted by oxygen ions (O ++ ) of energies ranging from 50 to 250 keV. The ion doses varied from 1010 to 1015 ions / cm2. The conventional prism-film coupler method was used to determine the waveguiding nature of the implanted and unimplanted films. The increase of the surface refractive index in the implanted layer has been studied by measuring the effective refractive index (neff) for different optical modes. Electron spectroscopy chemical analysis measurements were also performed to assess the effect of ion implantation on the polymer matrix.

Effects of Saponification Rate on Electrooptical Properties and Morphology of Poly(vinyl alcohol)/Liquid Crystal Composite Films

NASA Astrophysics Data System (ADS)

Ono, Hiroshi; Kawatsuki, Nobuhiro

1995-03-01

The relationship between the saponification rate of poly(vinyl alcohol) (PVA), and the electrooptical properties and morphology of the PVA/liquid crystal (LC) composite films was investigated. Light transmission clazing and the LC droplet size were varied by changing the saponification rate or the blend ratio of two kinds of PVA with different saponification rates because the refractive index and surface tension could be controlled by the saponification rate of PVA. The threshold voltage decreased with increasing saponification rate though the extrapolation length was decreased. It was suggested that the electrooptical properties were strongly dependent on the droplet size.

Biodegradability of poly(3-hydroxybutyrate) film grafted with vinyl acetate: Effect of grafting and saponification

NASA Astrophysics Data System (ADS)

Wada, Yuki; Seko, Noriaki; Nagasawa, Naotsugu; Tamada, Masao; Kasuya, Ken-ichi; Mitomo, Hiroshi

2007-06-01

Radiation-induced graft polymerization of vinyl acetate (VAc) onto poly(3-hydroxybutyrate) (PHB) film was carried out. At a degree of grafting higher than 5%, the grafted films (PHB-g-VAc) completely lost the enzymatic degradability that is characteristic of PHB due to the grafted VAc covering the surface of the PHB film. However, the biodegradability of the PHB-g-VAc films was recovered when the films were saponified in alkali solution under optimum conditions. Graft chains of the PHB-g-VAc film reacted selectively to become biodegradable polyvinyl alcohol (PVA). The biodegradability of the saponified PHB-g-VAc film increased rapidly with time.

Molecular Engineering of Liquid Crystalline Polymers by Living Polymerization. 8. Influence of Molecular Weight on the Phase Behavior pf Poly(Omega-((4-cyano-4’Biphenyl)oxy)alkyl Vinyl Ether)s with Ethyl, Propyl and Butyl Alkyl Groups

DTIC Science & Technology

1990-10-16

methanol (15 ml). The mixture was refluxed for 12 hr. After cooling and filtration (to remove the catalyst ) the solvent was distilled in a rotavapor and...was controlled by the monomer/initiator ([M]/[I]0 ) ratio. After quenching the polymerization with ammoniacal methanol , the reaction mixture was...The Phase Behavior of Poly(co-[(4-cyano-4’- biphenyl)oxy] alkyl Vinyl Ether]s with Ethyl, Propyl and Butyl Alkyl Groups Acc,--.o ,; ., x .... V

Morphological and Mechanical Properties of Polypropylene[PP]/Poly(Ethylene Vinyl Acetate)[EVA] Blends. I. Homopolymer PP/Eva Systems

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

Ramirez-Vargas, E.

2000-10-01

Morphological and mechanical properties of polypropylene [PP]/poly(ethylene vinyl acetate) [EVA] blends have been studied. Infrared results using thin films first indicated a transition toward compatibility between both components at concentrations above 40% EVA. The transition was verified with different experimental techniques and it was associated to morphological changes and mechanical properties. The PP/EVA blends were mechanically evaluated in terms of impact and tensile strength to determine the influence of blending on the performance properties of these materials. Agreement was found between the transition and the enhancement of both elongation at break and impact strength.

Mucoadhesive hydrogel microparticles based on poly (methacrylic acid-vinyl pyrrolidone)-chitosan for oral drug delivery.

PubMed

Sajeesh, S; Sharma, Chandra P

2011-05-01

The study was aimed at the evaluation of N-vinyl pyrrolidone (NVP) incorporated polymethacrylic acid-chitosan microparticles for oral drug delivery applications. Poly (methacrylic acid)-chitosan (PMC) and poly(methacrylic acid-vinyl pyrrolidone)-chitosan (PMVC) microparticles were prepared by an ionic-gelation method. Mucoadhesion behaviour of these particles was evaluated by ex-vivo adhesion method using freshly excised rat intestinal tissue. Cytotoxicity and absorption enhancing property of PMC and PMVC particles were evaluated on Caco 2 cell monolayers. Protease enzyme inhibition capability and insulin loading/release properties of these hydrogel particles was evaluated under in vitro experimental conditions. Addition of NVP units enhanced the mucoadhesion behavior of PMC particles on isolated rat intestinal tissue. Both PMC and PMVC particles were found non-toxic on Caco 2 cell monolayers and PMC particles was more effective in improving paracellular transport of fluorescent dextran across Caco 2 cell monolayers as compared to PMVC particles. However, protease inhibition efficacy of PMC particles was not significantly affected with NVP addition. NVP incorporation improved the insulin release properties of PMC microparticles at acidic pH. Hydrophilic modification seems to be an interesting approach in improving mucoadhesion capability of PMC microparticles.

Cobalt/copper-decorated carbon nanofibers as novel non-precious electrocatalyst for methanol electrooxidation

PubMed Central

2014-01-01

In this study, Co/Cu-decorated carbon nanofibers are introduced as novel electrocatalyst for methanol oxidation. The introduced nanofibers have been prepared based on graphitization of poly(vinyl alcohol) which has high carbon content compared to many polymer precursors for carbon nanofiber synthesis. Typically, calcination in argon atmosphere of electrospun nanofibers composed of cobalt acetate tetrahydrate, copper acetate monohydrate, and poly(vinyl alcohol) leads to form carbon nanofibers decorated by CoCu nanoparticles. The graphitization of the poly(vinyl alcohol) has been enhanced due to presence of cobalt which acts as effective catalyst. The physicochemical characterization affirmed that the metallic nanoparticles are sheathed by thin crystalline graphite layer. Investigation of the electrocatalytic activity of the introduced nanofibers toward methanol oxidation indicates good performance, as the corresponding onset potential was small compared to many reported materials; 310 mV (vs. Ag/AgCl electrode) and a current density of 12 mA/cm2 was obtained. Moreover, due to the graphite shield, good stability was observed. Overall, the introduced study opens new avenue for cheap and stable transition metals-based nanostructures as non-precious catalysts for fuel cell applications. PMID:24387682

Coating gigaporous polystyrene microspheres with cross-linked poly(vinyl alcohol) hydrogel as a rapid protein chromatography matrix.

PubMed

Qu, Jian-Bo; Huan, Guan-Sheng; Chen, Yan-Li; Zhou, Wei-Qing; Liu, Jian-Guo; Huang, Fang

2014-08-13

Gigaporous polystyrene (PS) microspheres were hydrophilized by in situ polymerization to give a stable cross-linked poly(vinyl alcohol) (PVA) hydrogel coating, which can shield proteins from the hydrophobic PS surface underneath. The amination of microspheres (PS-NH2) was first carried out through acetylization, oximation and reduction, and then 4,4'-azobis (4-cyanovaleric acid) (ACV), a polymerization initiator, was covalently immobilized on PS-NH2 through amide bond formation, and the cross-linked poly(vinyl acetate) (PVAc) was prepared by radical polymerization at the surfaces of ACV-immobilized PS microspheres (PS-ACV). Finally, the cross-linked PVA hydrogel coated gigaporous PS microspheres (PS-PVA) was easily achieved through alcoholysis of PVAc. Results suggested that the PS microspheres were effectively coated with cross-linked PVA hydrogel, where the gigaporrous structure remained under optimal conditions. After hydrophilic modification (PS-PVA), the protein-resistant ability of microspheres was greatly improved. The hydroxyl-rich PS-PVA surface can be easily derivatized by classical chemical methods. Performance advantages of the PS-PVA column in flow experiment include good permeability, low backpressure, and mechanical stability. These results indicated that PS-PVA should be promising in rapid protein chromatography.

Simple, rapid and, cost-effective fabrication of PDMS electrophoresis microchips using poly(vinyl acetate) as photoresist master.

PubMed

Lobo-Júnior, Eulício O; Gabriel, Ellen F M; Dos Santos, Rodrigo A; de Souza, Fabrício R; Lopes, Wanderson D; Lima, Renato S; Gobbi, Angelo L; Coltro, Wendell K T

2017-01-01

This study describes a simple, rapid, and cost-effective fabrication of PDMS electrophoresis microchips using poly(vinyl acetate) (PVAc) emulsion as photoresist master. High-relief microfluidic structures were defined on poly(vinyl acetate) previously deposited on printed circuit boards surfaces without cleanroom facilities and sophisticated instrumentation. After a UV exposure, channels with heights ranging from 30 to 140 μm were obtained by controlling the emulsion mass deposited on the master surface. The developing stage was performed using water rather than the organic solvents that are applied for conventional masks. The surface morphology was characterized by optical imaging, profilometry, and SEM. Based on the achieved results, the proposed method offers suitable reproducibility for the prototyping of electrophoresis microchips in PDMS. The feasibility of the resulting PDMS electrophoresis chips was successfully demonstrated with the separation of major inorganic cations within 100 s using a contactless conductivity detection system. The separation efficiencies ranged from ca. 67 900 to 125 600 plates/m. Due to the satisfactory performance and simplified instrumentation, we believe this fabrication protocol presents potential to be implemented in any chemical, biochemical, or biological laboratory. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electrospun matrices for localised controlled drug delivery: release of tetracycline hydrochloride from layers of polycaprolactone and poly(ethylene-co-vinyl acetate).

PubMed

Alhusein, Nour; Blagbrough, Ian S; De Bank, Paul A

2012-12-01

We report the controlled release of tetracycline (Tet) HCl from a three-layered electrospun matrix for the first time. Five formulations of electrospun poly-ε-caprolactone (PCL) and poly(ethylene-co-vinyl acetate) (PEVA) have been designed, prepared as micro/nanofibre layers, and assayed for the controlled release of the clinically useful antibiotic Tet HCl with potential applications in wound healing and especially in complicated skin and skin-structure infections. Tet HCl was also chosen as a model drug possessing a good ultraviolet (UV) chromophore and capable of fluorescence together with limited stability. Tet HCl was successfully incorporated (essentially quantitatively at 3 %, w/w) and provided controlled release from multilayered electrospun matrices. The Tet HCl release test was carried out by a total immersion method on 2 × 2 cm(2) electrospun fibrous mats in Tris or phosphate-buffered saline heated to 37 °C. The formulation PCL/PEVA/PCL with Tet HCl in each layer gave a large initial (burst) release followed by a sustained release. Adding a third layer to the two-layered formulations led to release being sustained from 6 days to more than 15 days. There was no detectable loss of Tet chemical stability (as shown by UV and NMR) or bioactivity (as shown by a modified Kirby-Bauer disc assay). Using Tet HCl-sensitive bacteria, Staphylococcus aureus (ATCC 25923), the Tet HCl-loaded three-layered matrix formulations were still showing significantly higher antibacterial effects on days 4 and 5 than commercially available Antimicrobial Susceptibility Test Discs of Tet HCl. Electrospinning provides good encapsulation efficiency of Tet HCl within PCL/PEVA/PCL polymers in micro/nanofibre layers which display sustained antibiotic release.

The actuation of a biomimetic poly(vinyl alcohol)poly(acrylic acid) gel.

PubMed

Marra, S P; Ramesh, K T; Douglas, A S

2002-02-15

Active polymer gels expand and contract in response to certain environmental stimuli, such as the application of an electric field or a change in the pH level of the surroundings. This ability to achieve large, reversible deformations with no external mechanical loading has generated much interest in the use of these gels as biomimetic actuators and "artificial muscles". In previous work, a thermodynamically consistent finite-elastic constitutive model has been developed to describe the mechanical and actuation behaviours of active polymer gels. The mechanical properties were characterized by a free-energy function, and the model uses an evolving internal variable to describe the actuation state. In this work, an evolution law for the internal variable is determined from free actuation experiments on a poly(vinyl alcohol)poly(acrylic acid) (PVAPAA) gel. The complete finite-elastic/evolution law constitutive model is then used to predict the response of the PVA-PAA gel to isotonic and isometric loading and actuation. The model is shown to give relatively good agreement with experimental results.

Poly High Internal Phase Emulsion for the Immobilization of Chemical Warfare Agents.

PubMed

Wright, Alexander J; Main, Marcus J; Cooper, Nicholas J; Blight, Barry A; Holder, Simon J

2017-09-20

We report a facile method for the absorption (characterized by the weight/weight swelling degree, Q) of a variety of chemical warfare agents (CWAs); including sulfur mustard (HD) (Q = 40) and V-series (VM, VX, i-Bu-VX, n-Bu-VX) of nerve agents (Q ≥ 45) and a simulant, methyl benzoate (Q = 55), through the use of a poly(styrene-co-vinyl benzyl chloride-co-divinylbenzene) lightly cross-linked poly high internal phase emulsion (polyHIPE). By varying the vinyl benzyl chloride (VBC) content and the volume of the internal phase of the precursor emulsion it is demonstrated that absorption is facilitated both by the swelling of the polymer and the uptake of liquid in the pores. In particular the sample prepared from a 95% internal emulsion water content showed rapid swelling (<5 min to total absorption) and the ability to swell both from a monolithic state and from a compressed state, making these systems ideal practical candidates for the rapid immobilization of CWAs.

Controlled Growth of CdS Quantum Dot in an Amphiphilic Diblock Copolymer Poly(2-Vinyl Pyridine)-b-Poly(n-Hexyl Isocyanate) Reversed Micelle Nanoreactor.

PubMed

Samal, Monica; Mohapatra, Priya Ranjan; Yun, Kyu Sik

2015-09-01

A diblock copolymer poly(2-vinyl pyridine)-b-poly(n-hexyl isocyanate) (P2VP-b-PHIC) is used for the present study. It has two blocks; a rod-shaped PHIC block that adopts a helical conformation, and a coil shaped P2VP block. In a polar solvent such as THF both PHIC and P2VP blocks are soluble. In mixtures of two solvents, such as THF and methanol, while the solubility of P2VP component is augmented that of PHIC is decreased leading to formation of reversed micelles. The pyridine nitrogen in P2VP block is a reactive site. It forms complexes with a suitable metal ion, such as Cd2+. The micelle is employed as a nanoreactor for synthesis of CdS quantum dot (QD). In this paper, the micellization behaviour of the copolymer and the use of the micelles for synthesis and controlled growth of CdS nanocrystals are demonstrated.

Reusable recording medium based on MBPVA and vinyl acetate

NASA Astrophysics Data System (ADS)

John, Beena Mary; Ushamani, M.; Joseph, Rani; Sreekumar, K.; Sudha Kartha, C.

2006-03-01

A new photopolymerizable recording media is introduced based on poly (vinyl alcohol) and vinyl acetate sensitized with methylene blue. It is observed that this MBPVA/VAc system can be reused a number of times without significant decrease in diffraction efficiency. The PVA-VAc ratio was optimized at 2:1. Diffraction efficiency of 6.3% was obtained without any fixing at a dye concentration of 9.3?×?10-4?mol/l at an exposure of 750?mJ/cm2. The material is attractive on account of its reusability.

Thermo- and electro-dual responsive poly(ionic liquid) electrolyte based smart windows.

PubMed

Chen, Fei; Ren, Yongyuan; Guo, Jiangna; Yan, Feng

2017-01-31

Thermo- and electro-dual responsive poly(ionic liquid) (PIL) based electrolytes were synthesized by co-polymerization of N-isopropylacrylamide (NIPAM) with (or without) 3-butyl-1-vinyl-imidazolium bromide ([BVIm][Br]) using diallyl-viologen (DAV) as both the cross-linking agent and electrochromic material.

Self-assembly behavior of poly(fluorenyl styrene)-block-poly(2-vinyl pyridine) and their blends with single wall carbon nanotubes (SWCNT)

NASA Astrophysics Data System (ADS)

Mezzenga, Raffaele; Li, Chaoxu; Hsu, Jung-Ching; Chen, Wen-Chang; Sugiyama, Kenji; Hirao, Akira

2010-03-01

We describe a supramolecular strategy to disperse carbon nanotubes in block copolymer matrices. To achieve the desired functions and morphologies, comb-type architectures in which one and two fluorene units attached on the styrene ring of polystyrene-block-poly(2-vinyl pyridine) were studied. Depending on the pendant fluorene units, the block ratio, the casting solvent and thermal annealing history, multiple morphologies were found. The phase diagram, compared to PS-b-P2VP, was interpreted in terms of the conformational asymmetry arising from grafting of fluorene units of variable lengths. Hydrogen bonds between COOH-SWCNT and P2VP favor miscibility of SWCNT within P2VP domains and the blending of these two components is reflected both on the final morphologies and on the electron conductivity of the blends.

Interfacial Properties of Thin Films of Poly(vinyl ether)s with Architectural Design in Water

NASA Astrophysics Data System (ADS)

Oda, Yukari; Itagaki, Nozomi; Sugimoto, Sin; Kawaguchi, Daisuke; Matsuno, Hisao; Tanaka, Keiji

Precise design of primary structure and architecture of polymers leads to the well-defined structure, unique physical properties, and excellent functions not only in the bulk but also at the interfaces. We here constructed functional polymer interfaces in water based on the architectural design of poly(vinyl ether)s with oxyethylene side-chains (POEVE). A branched polymer with POEVE parts was preferentially segregated at the air interface in the matrix of poly(methyl methacrylate). As an alternative way to prepare the POEVE surface, the cross-linked hydrogel thin films were prepared. The moduli of the hydrogel films near the water interfaces, which were examined by force-distance curve measurements using atomic force microscopy, were greatly sensitive to the cross-linking density of the polymers. Diffuse interfaces of POEVE chains at the water interface make it possible to prevent the platelet adhesion on the films.

Thermal degradation of ternary blend films containing PVA/chitosan/vanillin

NASA Astrophysics Data System (ADS)

Kasai, Deepak; Chougale, Ravindra; Masti, Saraswati; Narasgoudar, Shivayogi

2018-05-01

The ternary chitosan/poly (vinyl alcohol)/vanillin blend films were prepared by solution casting method. The influence of equal weight percent of poly (vinyl alcohol) and vanillin on thermal stability of the chitosan blend films were investigated by using thermogravimetric analysis (TGA). The kinetic parameters such as enthalpy (ΔH*), entropy (ΔS*), and Gibbs free energy (ΔG*) in the first and second decomposition steps based on the thermogravimetric data were calculated. The thermal stabilities of the blend films were confirmed by thermodynamic parameters obtained in the activation energies, which indicated that increase in the equal weight percent of PVA/vanillin decreased the thermal stability of the chitosan film.

Impact behaviour of an innovative plasticized poly(vinyl chloride) for the automotive industry

NASA Astrophysics Data System (ADS)

Bernard, C. A.; Bahlouli, N.; Wagner-Kocher, C.; Ahzi, S.; Rémond, Y.

2015-09-01

Plasticized poly(vinyl chloride) (PPVC) is widely used in the automotive industry in the design of structural parts for crashworthiness applications. Thus, it is necessary to study and understand the influence of the mechanical response and mechanical properties of PPVC over a wide range of strain rate, from quasi-static to dynamic loadings. The process is also investigated using different sample thicknesses. In this work, the strain rate effect of a new PPVC is investigated over a wide range of strain rates at three temperatures and for three thicknesses. A modelling of the yield stress is also proposed. The numerical prediction is in good agreement with the experimental results.

Study on dehydrochlorination of waste poly (vinyl chloride) resins by microwave irradiation

NASA Astrophysics Data System (ADS)

Moriwaki, Saburo; Qian, Qingrong; Sunohara, Satoshi; Machida, Motoi; Tatsumoto, Hideki

Waste poly (vinyl chloride: PVC) resins are experimentally dehydrochlorinated by microwave irradiation. The following unique results are obtained: (1) plasticizer in PVC resin absorbs microwave power more effectively than PVC polymer. The higher the plasticizer content in PVC resin, the higher is the dehydrochlorination reaction (2) low PVC polymer content materials such as cushion floor require high microwave irradiation power to secure a high dehydrochlorination yield, (3) calcium carbonate in PVC resin reacts with released hydrochloric acid gas and results calcium chloride during microwave irradiation, (4) additives in PVC resin strongly influence dehydrochlorination yield, (5) it is evidenced that the PVC copolymer is also dehydrochlorinated by microwave irradiation.

Photoinduced charge-carrier modulation of inkjet-printed carbon nanotubes via poly(vinyl acetate) doping and dedoping for thermoelectric generators

NASA Astrophysics Data System (ADS)

Horike, Shohei; Fukushima, Tatsuya; Saito, Takeshi; Koshiba, Yasuko; Ishida, Kenji

2018-01-01

Here, we studied the charge-carrier modulation of single-walled carbon nanotubes (SWCNTs) via poly(vinyl acetate) (PVAc) doping and dedoping under ultraviolet (UV) light irradiation with the aim of pairing several p- and n-type SWCNTs as thermoelectric (TE) elements. The Seebeck coefficient of the SWCNTs was first made negative by doping with PVAc and then made positive again through UV-induced PVAc dedoping. A possible TE module configuration and the process for its fabrication are proposed, wherein prints and photopatterns can be obtained without the use of additional electrodes. Our findings enable the fabrication of fine TE modules using simple materials and techniques.

Role of metal oxides in the thermal degradation of poly(vinyl chloride)

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

Gupta, M.C.; Viswanath, S.G.

Thermal degradation of poly(vinyl chloride) has been studied in the presence of metal oxides by a thermogravimetric method. It follows a two-step mechanism. In the first step chlorine free radical is formed as in the case of pure PVC, and in the second step chlorine free radical replaces oxygen from metal oxide to form metal chloride and oxygen free radical. Subsequently, the oxygen free radical abstracts hydrogen from PVC. Formation of metal chloride is the rate-controlling step. The metal chlorides formed during the thermal degradation either volatilize or decompose simultaneously to lower metallic chlorides depending on the boiling point ormore » the volatilization temperature.« less

pH responsiveness of dendrimer-like poly(ethylene oxide)s.

PubMed

Feng, Xiaoshuang; Taton, Daniel; Borsali, Redouane; Chaikof, Elliot L; Gnanou, Yves

2006-09-06

Poly(ethylene oxide) (PEO) and poly(acrylic acid) (PAA), two polymers known to form pH-sensitive aggregates through noncovalent interactions, were assembled in purposely designed architecture -a dendrimer-like PEO scaffold carrying short inner PAA chains-to produce unimolecular systems that exhibit pH responsiveness. Because of the particular placement of the PAA chains within the dendrimer-like structure, intermolecular complexation between acrylic acid (AA) and ethylene oxide (EO) units-and thus macroscopic aggregation or even mesoscopic micellization-could be avoided in favor of the sole intramolecular complexation. The sensitivity of such interactions to pH was exploited to generate dendrimer-like PEOs that reversibly shrink and expand with the pH. Such PAA-carrying dendrimer-like PEOs were synthesized in two main steps. First, a fifth-generation dendrimer-like PEO was obtained by combining anionic ring-opening polymerization (AROP) of ethylene oxide from a tris-hydroxylated core and selective branching reactions of PEO chain ends. To this end, an AB(2)C-type branching agent was designed: the latter includes a chloromethyl (A) group for its covalent attachment to the arm ends, two geminal hydroxyls (B(2)) protected in the form of a ketal ring for the growth of subsequent PEO generations by AROP, and a vinylic (C) double bonds for further functionalization of the interior of dendrimer-like PEOs. Reiteration of AROP and derivatization of PEO branches allowed us to prepare a dendrimer-like PEO of fourth generation with a total molar mass of 52,000 g x mol(-1), containing 24 external hydroxyl functions and 21 inner vinylic groups in the interior. A fifth generation of PEO chains was generated from this parent dendrimer-like PEO of fourth generation using a "conventional" AB(2)-type branching agent, and 48 PEO branches could be grown by AROP. The 48 outer hydroxy-end groups of the fifth-generation dendrimer-like PEO obtained were subsequently quantitatively converted into inert benzylic groups using benzyl bromide. The 21 internal vinylic groups carried by the PEO scaffold were then chemically modified in a two-step sequence into bromoester groups. The latter which are atom transfer radical polymerization (ATRP) initiating sites thus served to grow poly(tert-butylacrylate) chains. After a final step of hydrolysis of the tert-butyl ester groups, double, hydrophilic, dendrimer-like PEOs comprising 21 internal junction-attached poly(acrylic acid) (PAA) blocks could be obtained. Dynamic light scattering was used to determine the size of these dendrimer-like species in water and to investigate their response to pH variation: in particular, how the pH-sensitive complexation of EO and AA units affects their overall behavior.

Complementary use of flow and sedimentation field-flow fractionation techniques for size characterizing biodegradable poly(lactic acid) nanospheres

PubMed Central

Contado, Catia; Dalpiaz, Alessandro; Leo, Eliana; Zborowski, Maciej; Williams, P. Stephen

2009-01-01

Poly(lactic acid) nanoparticles were synthesized using a modified evaporation method, testing two different surfactants (sodium cholate and Pluronic F68) for the process. During their formulation the prodrug 5′-octanoyl-CPA (Oct-CPA) of the antiischemic N6-cyclopentyladenosine (CPA) was encapsulated. Three different purification methods were compared with respect to the influence of surfactant on the size characteristics of the final nanoparticle product. Flow and sedimentation field-flow fractionation techniques (FlFFF and SdFFF, respectively) were used to size characterize the five poly(lactic acid) particle samples. Two different combinations of carrier solution (mobile phase) were employed in the FlFFF analyses, while a solution of poly(vinyl alcohol) was used as mobile phase for the SdFFF runs. The separation performances of the two techniques were compared and the particle size distributions, derived from the fractograms, were interpreted with the support of observations by scanning electron microscopy. Some critical aspects, such as the carrier choice and the channel thickness determination for the FlFFF, have been investigated. This is the first comprehensive comparison of the two FFF techniques for characterizing non standard particulate materials. The two FFF techniques proved to be complementary and gave good, congruent and very useful information on the size distributions of the five poly(lactic acid) particle samples. PMID:17482199

Nano-engineered Drug Combinations for Breast Cancer Treatment

DTIC Science & Technology

2013-08-01

dextran),41 or poly(acrylamide-co-acrylic acid ),42 poly(methyl methacrylate),40 poly(styrene),40 and poly(vinyl cinnamate )40, 43, 44 in separate...pH, this polymer is stable and water insoluble, but at acidic pH the polymer becomes de-protected and water-soluble (Figure 6.A). Thus, particles...made of such a polymer will stay intact in the blood stream and will only start to dissolve away and release their cargo in environments with an acidic

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

PubMed

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

2011-01-01

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

An organic dye-polymer (phenol red-poly (vinyl alcohol)) composite architecture towards tunable -optical and -saturable absorption characteristics

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

Sreedhar, Sreeja, E-mail: sreejasreedhar83@gmail.com; Muneera, C. I., E-mail: drcimuneera@hotmail.com; Illyaskutty, Navas

2016-05-21

Herein, we demonstrate that blending an organic dye (guest/filler), with a vinyl polymer (host template), is an inexpensive and simple approach for the fabrication of multifunctional photonic materials which could display an enhancement in the desirable properties of the constituent materials and, at the same time provide novel synergistic properties for the guest-host system. A new guest-host nanocomposite system comprising Phenol Red dye and poly (vinyl alcohol) as guest and host template, respectively, which exhibits tunable optical characteristics and saturable absorption behavior, is introduced. The dependence of local electronic environment provided by the polymer template and the interactions of themore » polymer molecules with the encapsulated guest molecules on the observed optical/nonlinear absorption behavior is discussed. An understanding of the tunability of the optical/ photophysical processes, with respect to the filler content, as discussed herein could help in the design of improved optical materials for several photonic device applications like organic light emitting diodes and saturable absorbers.« less

Synthesis of Degradable Poly(vinyl alcohol) by Radical Ring-Opening Copolymerization and Ice Recrystallization Inhibition Activity.

PubMed

Hedir, Guillaume; Stubbs, Christopher; Aston, Phillip; Dove, Andrew P; Gibson, Matthew I

2017-12-19

Poly(vinyl alcohol) (PVA) is the most active synthetic mimic of antifreeze proteins and has extremely high ice recrystallization inhibition (IRI) activity. Addition of PVA to cellular cryopreservation solutions increases the number of recovered viable cells due to its potent IRI, but it is intrinsically nondegradable in vivo . Here we report the synthesis, characterization, and IRI activity of PVA containing degradable ester linkages. Vinyl chloroacetate (VClAc) was copolymerized with 2-methylene-1,3-dioxepane (MDO) which undergoes radical ring-opening polymerization to install main-chain ester units. The use of the chloroacetate monomer enabled selective deacetylation with retention of esters within the polymer backbone. Quantitative IRI assays revealed that the MDO content had to be finely tuned to retain IRI activity, with higher loadings (24 mol %) resulting in complete loss of IRI activity. These degradable materials will help translate PVA, which is nontoxic and biocompatible, into a range of biomedical applications.

Superstretchable Nacre-Mimetic Graphene/Poly(vinyl alcohol) Composite Film Based on Interfacial Architectural Engineering.

PubMed

Zhao, Nifang; Yang, Miao; Zhao, Qian; Gao, Weiwei; Xie, Tao; Bai, Hao

2017-05-23

Through designing hierarchical structures, particularly optimizing the chemical and architectural interactions at its inorganic/organic interface, nacre has achieved an excellent combination of contradictory mechanical properties such as strength and toughness, which is highly demanded yet difficult to achieve by most synthetic materials. Most techniques applied to develop nacre-mimetic composites have been focused on mimicking the "brick-and-mortar" structure, but the interfacial architectural features, especially the asperities and mineral bridges of "bricks", have been rarely concerned, which are of equal importance for enhancing mechanical properties of nacre. Here, we used a modified bidirectional freezing method followed by uniaxial pressing and chemical reduction to assemble a nacre-mimetic graphene/poly(vinyl alcohol) composite film, with both asperities and bridges introduced in addition to the lamellar layers to mimic the interfacial architectural interactions found in nacre. As such, we have developed a composite film that is not only strong (up to ∼150.9 MPa), but also tough (up to ∼8.50 MJ/m 3 ), and highly stretchable (up to ∼10.44%), difficult to obtain by other methods. This was all achieved by only interfacial architectural engineering within the traditional "brick-and-mortar" structure, without introducing a third component or employing chemical cross-linker as in some other nacre-mimetic systems. More importantly, we believe that the design principles and processing strategies reported here can also be applied to other material systems to develop strong and stretchable materials.

Effect of Microwave Non thermal Plasma Irradiation on the Adsorptive Properties of Active Carbon Preliminarily Impregnated with Poly(vinyl alcohol)

NASA Astrophysics Data System (ADS)

Ueshima, Masato; Toda, Eriko; Nakajima, Yuki; Sugiyama, Kazuo

2010-08-01

Microwave non thermal plasma irradiation was conducted on active carbon (AC) preliminarily impregnated with poly(vinyl alcohol) (PVA) in order to modify the adsorption properties of active carbon, particularly to increase hydrophobicity. The plasma was produced by applying microwave power on the PVA-impregnated active carbon (PVA/AC) placed in a low vacuum chamber (<10 Torr). The surface of the plasma-treated PVA/AC was imaged using scanning electron microscopy and atomic force microscopy (SEM and AFM, respectively), and analyzed using X-ray photoelectron spectroscopy (XPS). Hydrophobicity of the plasma-treated PVA/AC was compared to that of untreated PVA/AC and AC by a sinking test in water/methanol mixed solutions. The hydrophobicity drastically increased for PVA/AC treatment with 1-min plasma irradiation. The AFM results indicated that the surface roughness of the PVA/AC was dependent upon the hydrophobicity, rather than reduction of free energy due to reduction of polarized functional groups. NaOH and HCl adsorption onto the plasma-treated PVA/AC was also measured. Adsorption capacity of plasma-treated PVA/AC increased for NaOH, whereas it decreased for HCl. The plasma treatment not only increased the hydrophobicity of PVA/AC, but also changed its acid-base adsorption properties. We have developed a new material based on active carbon, which is light, hydrophobic and electrically conductive by using a combination of PVA sintering and plasma irradiation.

Facile Synthesis of Thick Films of Poly(methyl methacrylate), Poly(styrene), and Poly(vinyl pyridine) from Au Surfaces

PubMed Central

Saha, Sampa

2011-01-01

Atom transfer radical polymerization (ATRP) is commonly used to grow polymer brushes from Au surfaces, but the resulting film thicknesses are usually significantly less than with ATRP from SiO2 substrates. On Au, growth of poly(methyl methacrylate) (PMMA) blocks from poly(tert-butyl acrylate) brushes occurs more rapidly than growth of PMMA from initiator monolayers, suggesting that the disparity between growth rates from Au and SiO2 stems from the Au surface. Radical quenching by electron transfer from Au is probably not the termination mechanism because polymerization from thin, cross-linked initiators gives film thicknesses that are essentially the same as the thicknesses of films grown from SiO2 under the same polymerization conditions. However, this result is consistent with termination through desorption of thiols from non-cross-linked films, and reaction of these thiols with growing polymer chains. The enhanced stability of cross-linked initiators allows ATRP at temperatures up to ~100 °C and enables the growth of thick films of PMMA (350 nm), polystyrene (120 nm) and poly(vinyl pyridine) (200 nm) from Au surfaces in 1 hour. At temperatures >100 °C, the polymer brush layers delaminate as large area films. PMID:21728374

Novel double-confined polymeric ionic liquids as sorbents for solid-phase microextraction with enhanced stability and durability in high-ionic-strength solution.

PubMed

Feng, Juanjuan; Sun, Min; Xu, Lili; Wang, Shuai; Liu, Xia; Jiang, Shengxiang

2012-12-14

Because of the occurrence of ion exchange between high-ionic-strength solution and anions of polymeric ionic liquids (PILs), PILs based solid-phase microextraction (SPME) fibers were rarely used in direct immersion mode to high-salt-added samples. In this work, a novel double-confined PIL sorbent was prepared by co-polymerization of cation and anion of 1-vinyl-3-octylimidzaolium p-styrenesulfonate (VOIm(+)SS(-)). The poly(VOIm(+)-SS(-)) was chemically bonded onto functionalized stainless steel wire via surface radical chain-transfer reaction. Stability of poly(VOIm(+)-SS(-)) in high-ionic-strength solution was investigated and compared with that of poly(1-vinyl-3-octylimidzaolium benzenesulfonate) (poly(VOIm(+)BS(-))) by elemental analysis of sulfur element, and results turned out that the poly(VOIm(+)-SS(-)) was more stable. Coupled to gas chromatography (GC), the poly(VOIm(+)-SS(-)) fiber was used to extract three sorts of compounds including anilines, phenols and phthalate esters in aqueous solution. The as-established method showed good linearity, low detection limits, and acceptable repeatability. The direct immersion SPME-GC method was applied to determine the model phthalate esters in bottled mineral water. The determination results were satisfactory. Copyright © 2012 Elsevier B.V. All rights reserved.

High performance of poly(dopamine)-functionalized graphene oxide/poly(vinyl alcohol) nanocomposites

NASA Astrophysics Data System (ADS)

Ma, Jiaojiao; Pan, Jingkai; Yue, Jia; Xu, Yu; Bao, Jianjun

2018-01-01

In this paper, poly(vinyl alcohol) (PVA)/poly(dopamine)-functionalized graphene oxide (PGO) nanocomposites with high performance were prepared by an environment-friendly and facile strategy. GO was firstly functionalized and simultaneously reduced by poly(dopamine) to yield PGO. Then it was mixed with PVA in aqueous solution to make PVA/PGO nanocomposites. Transmission electron microscopy revealed that the PGO nanosheets are well dispersed and randomly oriented throughout the PVA matrix. At the same time, the thermal properties and water barrier properties of the PVA/PGO nanocomposites have been strikingly enhanced by the incorporation of PGO. The degradation temperature of the nanocomposites is more than 30 °C higher than that of pure PVA by the addition of 0.7 wt% PGO, which shows good thermal stability. The water vapor permeability of the nanocomposites also decreases to 0.71 × 10-12 g cm/(cm2 s Pa), corresponding to 80% reduction than that of pure PVA. Moreover, the PVA/PGO nanocomposites also present enhanced conductive properties. The PVA/PGO nanocomposites with such outstanding properties show great promising applications in the fields of packaging, electronics, fuel cell industry, fiber, and so on.

Moisture-induced phase separation and recrystallization in amorphous solid dispersions.

PubMed

Luebbert, Christian; Sadowski, Gabriele

2017-10-30

Active Pharmaceutical Ingredients (APIs) are often dissolved in polymeric matrices to control the gastrointestinal dissolution and to stabilize the amorphous state of the API. During the pharmaceutical development of new formulations, stability studies via storage at certain temperature and relative humidity (RH) have to be carried out to verify the long-term thermodynamic stability of these formulations against unwanted recrystallization and moisture-induced amorphous-amorphous phase separation (MIAPS). This study focuses on predicting the MIAPS of API/polymer formulations at elevated RH. In a first step, the phase behavior of water-free formulations of ibuprofen (IBU) and felodipine (FEL) combined with the polymers poly(vinyl pyrrolidone) (PVP), poly(vinyl acetate) (PVAC) and poly (vinyl pyrrolidone-co-vinyl acetate) (PVPVA64) was determined experimentally by differential scanning calorimetry (DSC). The phase behavior of these water-free formulations was modeled using the Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT). Based on this, the API solubility and MIAPS in the above-mentioned formulations at humid conditions was predicted in perfect agreement with the results of two-year lasting stability studies at 25°C/0% RH and 40°C/75% RH. MIAPS was predicted and also experimentally found for the FEL/PVP, FEL/PVPVA64 and IBU/PVP formulations, whereas MIAPS was neither predicted nor measured for the IBU/PVPVA64 system and PVAC-containing formulations. It was thus shown that the results of time-consuming long-term stability tests can be correctly predicted via thermodynamic modeling with PC-SAFT. Copyright © 2017 Elsevier B.V. All rights reserved.

Cell adhesion and guidance by micropost-array chemical sensors

NASA Astrophysics Data System (ADS)

Pantano, Paul; Quah, Soo-Kim; Danowski, Kristine L.

2002-06-01

An array of ~50,000 individual polymeric micropost sensors was patterned across a glass coverslip by a photoimprint lithographic technique. Individual micropost sensors were ~3-micrometers tall and ~8-micrometers wide. The O2-sensitive micropost array sensors (MPASs) comprised a ruthenium complex encapsulated in a gas permeable photopolymerizable siloxane. The pH-sensitive MPASs comprised a fluorescein conjugate encapsulated in a photocrosslinkable poly(vinyl alcohol)-based polymer. PO2 and pH were quantitated by acquiring MPAS luminescence images with an epifluorescence microscope/charge coupled device imaging system. O2-sensitive MPASs displayed linear Stern-Volmer quenching behavior with a maximum Io/I of ~8.6. pH-sensitive MPASs displayed sigmoidal calibration curves with a pKa of ~5.8. The adhesion of undifferentiated rat pheochromocytoma (PC12) cells across these two polymeric surface types was investigated. The greatest PC12 cell proliferation and adhesion occurred across the poly(vinyl alcohol)-based micropost arrays relative to planar poly(vinyl alcohol)-based surfaces and both patterned and planar siloxane surfaces. An additional advantage of the patterned MPAS layers relative to planar sensing layers was the ability to direct the growth of biological cells. Preliminary data is presented whereby nerve growth factor-differentiated PC12 cells grew neurite-like processes that extended along paths defined by the micropost architecture.

High-Tg Polynorbornene-Based Block and Random Copolymers for Butanol Pervaporation Membranes

NASA Astrophysics Data System (ADS)

Register, Richard A.; Kim, Dong-Gyun; Takigawa, Tamami; Kashino, Tomomasa; Burtovyy, Oleksandr; Bell, Andrew

Vinyl addition polymers of substituted norbornene (NB) monomers possess desirably high glass transition temperatures (Tg); however, until very recently, the lack of an applicable living polymerization chemistry has precluded the synthesis of such polymers with controlled architecture, or copolymers with controlled sequence distribution. We have recently synthesized block and random copolymers of NB monomers bearing hydroxyhexafluoroisopropyl and n-butyl substituents (HFANB and BuNB) via living vinyl addition polymerization with Pd-based catalysts. Both series of polymers were cast into the selective skin layers of thin film composite (TFC) membranes, and these organophilic membranes investigated for the isolation of n-butanol from dilute aqueous solution (model fermentation broth) via pervaporation. The block copolymers show well-defined microphase-separated morphologies, both in bulk and as the selective skin layers on TFC membranes, while the random copolymers are homogeneous. Both block and random vinyl addition copolymers are effective as n-butanol pervaporation membranes, with the block copolymers showing a better flux-selectivity balance. While polyHFANB has much higher permeability and n-butanol selectivity than polyBuNB, incorporating BuNB units into the polymer (in either a block or random sequence) limits the swelling of the polyHFANB and thereby improves the n-butanol pervaporation selectivity.

Sol–gel auto-combustion synthesis of PVP/CoFe{sub 2}O{sub 4} nanocomposite and its magnetic characterization

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

Kurtan, U.; Topkaya, R., E-mail: rtopkaya@gyte.edu.tr; Baykal, A.

2013-11-15

Graphical abstract: - Highlights: • The Poly(vinyl pyrrolidone) (PVP) was used as a surface capping agent. • PVP/CoFe{sub 2}O{sub 4} nanocomposite was synthesized by a sol-gel auto-combustion method. • The existence of the spin-disordered surface layer was established. - Abstract: Poly(vinyl pyrrolidone)/CoFe{sub 2}O{sub 4} nanocomposite has been fabricated by a sol–gel auto-combustion method. Poly(vinyl pyrrolidone) was used as a reducing agent as well as a surface capping agent to prevent particle aggregation and stabilize the particles. The average crystallite size estimated from X-ray line profile fitting was found to be 20 ± 7 nm. The high field irreversibility and unsaturatedmore » magnetization behaviours indicate the presence of the core–shell structure in the sample. The exchange bias effect observed at 10 K suggests the existence of the magnetically aligned core surrounded by spin-disordered surface layer. The reduced remanent magnetization value of 0.6 at 10 K (higher than the theoretical value of 0.5) shows the PVP/CoFe{sub 2}O{sub 4} nanocomposite to have cubic magnetocrystalline anisotropy according to the Stoner–Wohlfarth model.« less

Fabrication and characterization of a novel hydrophobic CaCO3 grafted by hydroxylated poly(vinyl chloride) chains

NASA Astrophysics Data System (ADS)

Bao, Lixia; Yang, Simei; Luo, Xin; Lei, Jingxin; Cao, Qiue; Wang, Jiliang

2015-12-01

The hydroxylated PVC (PVC-OH) was successfully synthesized by a suspension polymerization of vinyl chloride (VC), butyl acrylate (BA) and hydroxyethyl acrylate (HEA). Novel hydrophobic CaCO3 was then prepared by a urethane formation reaction between methylene diphenyl diisocyanate (MDI) and the sbnd OH groups both in the PVC-OH chains and on the surface of pristine CaCO3 particles. The effect of the PVC-OH content on the grafting ratio of treated CaCO3 particles was extensively investigated. Combining the result of Fourier transform infrared (FTIR) with that of water contact angle, it can be concluded that the hydrophobicity of CaCO3 had been efficiently improved by the PVC-OH segments grafted on the surface of CaCO3 particles. X-ray diffraction (XRD), thermal gravity analysis (TGA), scanning electron microscope (SEM) and transmission electron microscope (TEM) were also used to study crystalline behaviors, thermal stability and surface morphology of the modified CaCO3 particles, respectively. The change of specific surface area implying surface modification was investigated as well.

Thermodynamic properties (enthalpy, bond energy, entropy, and heat capacity) and internal rotor potentials of vinyl alcohol, methyl vinyl ether, and their corresponding radicals.

PubMed

da Silva, Gabriel; Kim, Chol-Han; Bozzelli, Joseph W

2006-06-29

Vinyl alcohols (enols) have been discovered as important intermediates and products in the oxidation and combustion of hydrocarbons, while methyl vinyl ethers are also thought to occur as important combustion intermediates. Vinyl alcohol has been detected in interstellar media, while poly(vinyl alcohol) and poly(methyl vinyl ether) are common polymers. The thermochemical property data on these vinyl alcohols and methyl vinyl ethers is important for understanding their stability, reaction paths, and kinetics in atmospheric and thermal hydrocarbon-oxygen systems. Enthalpies , entropies , and heat capacities (C(p)()(T)) are determined for CH(2)=CHOH, C(*)H=CHOH, CH(2)=C(*)OH, CH(2)=CHOCH(3), C(*)H=CHOCH(3), CH(2)=C(*)OCH(3), and CH(2)=CHOC(*)H(2). Molecular structures, vibrational frequencies, , and C(p)(T) are calculated at the B3LYP/6-31G(d,p) density functional calculation level. Enthalpies are also determined using the composite CBS-Q, CBS-APNO, and G3 methods using isodesmic work reactions to minimize calculation errors. Potential barriers for internal rotors are calculated at the B3LYP/6-31G(d,p) level and used to determine the hindered internal rotational contributions to entropy and heat capacity. The recommended ideal gas phase values calculated in this study are the following (in kcal mol(-1)): -30.0, -28.9 (syn, anti) for CH(2)=CHOH; -25.6, -23.9 for CH(2)=CHOCH(3); 31.3, 33.5 for C(*)H=CHOH; 27.1 for anti-CH(2)=C(*)OH; 35.6, 39.3 for C(*)H=CHOCH(3); 33.5, 32.2 for CH(2)=C(*)OCH(3); 21.3, 22.0 for CH(2)=CHOC(*)H(2). Bond dissociation energies (BDEs) and group additivity contributions are also determined. The BDEs reveal that the O-H, O-CH(3), C-OH, and C-OCH(3) bonds in vinyl alcohol and methyl vinyl ether are similar in energy to those in the aromatic molecules phenol and methyl phenyl ether, being on average around 3 kcal mol(-1) weaker in the vinyl systems. The keto-enol tautomerization enthalpy for the interconversion of vinyl alcohol to acetaldehyde is determined to be -9.7 kcal mol(-1), while the activation energy for this reaction is calculated as 55.9 kcal mol(-1); this is the simplest keto-enol tautomerization and is thought to be important in the reactions of vinyl alcohol. Formation of the formyl methyl radical (vinoxy radical/vinyloxy radical) from both vinyl alcohol and methyl vinyl ether is also shown to be important, and its reactions are discussed briefly.

Hydrogel Nanoparticles from Supercritical Technology for Pharmaceutical and Seismological Applications

NASA Astrophysics Data System (ADS)

Hemingway, Melinda Graham

This research focuses on hydrogel nanoparticle formation using miniemulsion polymerization and supercritical carbon dioxide. Hydrogel nanopowder is produced by a novel combination of inverse miniemulsion polymerization and supercritical drying (MPSD) methods. Three drying methods of miniemulsions are examined: (1) a conventional freeze drying technique, and (2) two supercritical drying techniques: (2a) supercritical fluid injection into miniemulsions, and (2b) the polymerized miniemulsion injection into supercritical fluid. Method 2b can produce non-agglomerated hydrogel nanoparticles that are free of solvent or surfactant (Chapter 2). The optimized MPSD method was applied for producing an extended release drug formulation with mucoadhesive properties. Drug nanoparticles of mesalamine, were produced using supercritical antisolvent technology and encapsulation within two hydrogels, polyacrylamide and poly(acrylic acid-co-acrylamide). The encapsulation efficiency and release profile of drug nanoparticles is compared with commercial ground mesalamine particles. The loading efficiency is influenced by morphological compatibility (Chapter 3). The MPSD method was extended for encapsulation of zinc oxide nanoparticles for UV protection in sunscreens (Chapter 4). ZnO was incorporated into the inverse miniemulsion during polymerization. The effect of process parameters are examined on absorbency of ultraviolet light and transparency of visible light. For use of hydrogel nanoparticles in a seismological application, delayed hydration is needed. Supercritical methods extend MPSD so that a hydrophobic coating can be applied on the particle surface (Chapter 5). Multiple analysis methods and coating materials were investigated to elucidate compatibility of coating material to polyacrylamide hydrogel. Coating materials of poly(lactide), poly(sulphone), poly(vinyl acetate), poly(hydroxybutyrate), Geluice 50-13, Span 80, octadecyltrichlorosilane, and perfluorobutane sulfate (PFBS) were tested, out of which Gelucire, perfluorobutane sulfate, and poly(vinyl acetate) materials were able to provide some coating and perfluorobutane sulfate, poly(lactide), poly(vinyl acetate) delayed hydration of hydrogel particles, but not to a sufficient extent. The interactions of the different materials with the hydrogel are examined based on phenomena observed during the production processes and characterization of the particles generated. This work provides understanding into the interactions of polyacrylamide hydrogel particles both internally by encapsulation and externally by coating.

Fabrication of antibacterial PVA nanocomposite films containing dendritic polymer functionalized multi-walled carbon nanotubes

NASA Astrophysics Data System (ADS)

Sapalidis, Andreas; Sideratou, Zili; Panagiotaki, Katerina N.; Sakellis, Elias; Kouvelos, Evangelos P.; Papageorgiou, Sergios; Katsaros, Fotios

2018-03-01

A series of Poly(vinyl alcohol) (PVA) nanocomposite films containing quaternized hyperbranched polyethyleneimine (PEI) functionalized multi-walled carbon nanotubes (ox-CNTs@QPEI) are prepared by solvent casting technique. The modified carbon based material exhibits high aqueous solubility, due to the hydrophilic character of the functionalized hyperbranched dendritic polymer. The quaternized PEI successfully wraps around nanotube walls, as polycations provide electrostatic repulsion. Various contents of ox-CNTs@QPEI ranging from 0.05 to 1.0 % w/w were employed to prepare functionalized PVA nanocomposites. The developed films exhibit adequate optical transparency, improved mechanical properties and extremely high antibacterial behavior due to the excellent dispersion of the functionalized carbon nanotubes into the PVA matrix.

Photoinduced Formation and Characterization of Metallic Silver and Gold Particles in VYCOR (trademark) Glass

DTIC Science & Technology

2004-12-01

agent such as citric acid or sodium borohydride. Other systems have been studied in which polymers such as poly vinyl alcohol/poly acrylic acid or...Wu, M. H., Henderson, D. O., Malone, K., Mills, G., Meldrum , A., Proceedings of the Electrochemical Society, 1999, 98-11, 439.

Water-stable diblock polystyrene-block-poly(2-vinyl pyridine) and diblock polystyrene-block-poly(methyl methacrylate) cylindrical patterned surfaces inhibit settlement of zoospores of the green alga Ulva.

PubMed

Grozea, Claudia M; Gunari, Nikhil; Finlay, John A; Grozea, Daniel; Callow, Maureen E; Callow, James A; Lu, Zheng-Hong; Walker, Gilbert C

2009-04-13

Nanopatterned surfaces with hydrophobic and hydrophilic domains were produced using the diblock copolymer polystyrene-block-poly(2-vinyl pyridine) (PS-b-P2VP) and polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA). The PS-b-P2VP diblock copolymer, mixed with the cross-linker benzophenone and spin-coated onto silicon wafers, showed self-assembled cylindrical structures, which were retained after UV treatment for cross-linking. The thin films displayed cylindrical domains after immersion in water. This study shows that pattern retention in water is possible for a long period of time, at least for two weeks in pure water and three weeks in artificial seawater. The PS-b-PMMA diblock showed self-assembled cylindrical structures. PS-b-P2VP and PS-b-PMMA cylindrical patterned surfaces showed reduced settlement of zoospores of the green alga Ulva compared to unpatterned surfaces. The copolymers were investigated using atomic force microscopy and X-ray photoelectron spectroscopy.

Phase Behavior of Pyrene and Vinyl Polymers with Aromatic Side Groups

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

Kangovi, Gagan N.; Lee, Sangwoo

The phase behavior and thermodynamic properties of mixtures of pyrene and model vinyl polymers with and without aromatic side groups are investigated using differential scanning calorimetry (DSC) measurements. The melting temperature and associated heat of melting of the pyrene crystals in the mixtures are utilized to extract the effective interaction parameters χ and the composition of polymer-rich phases, respectively. The χ of pyrene mixed with polymers with aromatic side groups investigated in this study, polystyrene, poly(2-vinylpyridine), and poly(3-vinylanisole), is less than 0.5 at the melting point of the pyrene crystals, suggesting that pyrene and the polymers with aromatic sides groupsmore » are enthalpically compatible, likely due to aromatic π–π interactions. In contrast, the χ of pyrene mixed with poly(1,4-isoprene) or poly(ethylene-alt-propylene) is larger than 0.5. The DSC measurements also enable characterization of the composition of polymer-rich phases. Interestingly, the polymers with aromatic side groups are found to have more pronounced miscibility with pyrene at symmetric compositions.« less

Tissue engineered poly(caprolactone)-chitosan-poly(vinyl alcohol) nanofibrous scaffolds for burn and cutting wound healing.

PubMed

Gholipour-Kanani, Adeleh; Bahrami, S Hajir; Joghataie, Mohammad Taghi; Samadikuchaksaraei, Ali; Ahmadi-Taftie, Hossein; Rabbani, Shahram; Kororian, Alireza; Erfani, Elham

2014-06-01

Natural-synthetic blend nanofibres have recently attracted more interest because of the ability of achieving desirable properties. Poly(ε-caprolactone) (PCL)-chitosan (Cs)-poly(vinyl alcohol) (PVA) blend nanofibrous scaffolds were electrospun in 2:1:1.33 mass ratio of PCL:Cs:PVA. The presence of PCL in the blend leads to improvement in web hydrophobicity and helped the web to retain its integrity in aqueous media. The scaffolds were used in two forms of acellular and with mesenchymal stem cells. They were applied on burn (n = 12) and excisional cutting (n = 12) wounds on dorsum skin of rats. Macroscopic investigations were carried out to measure the wounds areas. It was found that the area of wounds that were treated with cell-seeded nanofibrous scaffolds were smaller compared to other samples. Pathological results showed much better healing performance for cell-seeded scaffolds followed by acellular scaffolds compared with control samples. All these results indicate that PCL:Cs:PVA nanofibrous web would be a proper material for burn and cutting wound healing.

Optimization of Preparation Techniques for Poly(Lactic Acid-Co-Glycolic Acid) Nanoparticles

NASA Astrophysics Data System (ADS)

Birnbaum, Duane T.; Kosmala, Jacqueline D.; Brannon-Peppas, Lisa

2000-06-01

Microparticles and nanoparticles of poly(lactic acid-co-glycolic acid) (PLAGA) are excellent candidates for the controlled release of many pharmaceutical compounds because of their biodegradable nature. The preparation of submicron PLAGA particles poses serious challenges that are not necessarily present when preparing microparticles. We have evaluated several combinations of organic solvents and surfactants used in the formulation of PLAGA nanoparticles. Critical factors such as the ability to separate the nanoparticles from the surfactant, the ability to re-suspend the nanoparticles after freeze-drying, formulation yield and nanoparticle size were studied. The smallest particles were obtained using the surfactant/solvent combination of sodium dodecyl sulfate and ethyl acetate (65 nm) and the largest particles were obtained using poly(vinyl alcohol) and dichloromethane (466 nm). However, the optimal nanoparticles were produced using either acetone or ethyl acetate as the organic solvent and poly(vinyl alcohol) or human serum albumin as the surfactant. This is because the most critical measure of performance of these nanoparticles proved to be their ability to re-suspend after freeze-drying.

Paclitaxel-loaded poly(lactide-co-glycolide)/poly(ethylene vinyl acetate) composite for stent coating by ultrasonic atomizing spray.

PubMed

Yuk, Soon Hong; Oh, Keun Sang; Park, Jinah; Kim, Soon-Joong; Kim, Jung Ho; Kwon, Il Keun

2012-04-01

The mixture of poly(lactide-co-glycolide) (PLGA) and poly(ethylene vinyl acetate) (PEVA) forms a homogeneous liquid in an organic solvent such as tetrahydrofuran, and a phase-separated PLGA/PEVA composite can be prepared from it by evaporating the organic solvent. Exploiting this phenomenon, we designed a novel method of preparing a drug-loaded PLGA/PEVA composite and used it for coating drug-eluting stents (DESs). Paclitaxel (PTX), an anticancer drug, was chosen as a model drug. PLGA acts as a microdepot for PTX, and PEVA provides mechanical strength to the coating material. The presence of PLGA in the PLGA/PEVA composite suppressed PTX crystallization in the coating material, and PTX showed a sustained release rate over more than 30 days. The mechanical strength of the PLGA/PEVA composite was better than that of PEVA used as a control. After coating the stent with a PLGA/PEVA composite using ultrasonic atomizing spray, the morphology of the coated material was observed by scanning electron microscopy, and the release pattern of PTX was measured by high-performance liquid chromatography.

Paclitaxel-loaded poly(lactide-co-glycolide)/poly(ethylene vinyl acetate) composite for stent coating by ultrasonic atomizing spray

PubMed Central

Yuk, Soon Hong; Oh, Keun Sang; Park, Jinah; Kim, Soon-Joong; Kim, Jung Ho; Kwon, Il Keun

2012-01-01

The mixture of poly(lactide-co-glycolide) (PLGA) and poly(ethylene vinyl acetate) (PEVA) forms a homogeneous liquid in an organic solvent such as tetrahydrofuran, and a phase-separated PLGA/PEVA composite can be prepared from it by evaporating the organic solvent. Exploiting this phenomenon, we designed a novel method of preparing a drug-loaded PLGA/PEVA composite and used it for coating drug-eluting stents (DESs). Paclitaxel (PTX), an anticancer drug, was chosen as a model drug. PLGA acts as a microdepot for PTX, and PEVA provides mechanical strength to the coating material. The presence of PLGA in the PLGA/PEVA composite suppressed PTX crystallization in the coating material, and PTX showed a sustained release rate over more than 30 days. The mechanical strength of the PLGA/PEVA composite was better than that of PEVA used as a control. After coating the stent with a PLGA/PEVA composite using ultrasonic atomizing spray, the morphology of the coated material was observed by scanning electron microscopy, and the release pattern of PTX was measured by high-performance liquid chromatography. PMID:27877483

Paclitaxel-loaded poly(lactide-co-glycolide)/poly(ethylene vinyl acetate) composite for stent coating by ultrasonic atomizing spray

NASA Astrophysics Data System (ADS)

Yuk, Soon Hong; Oh, Keun Sang; Park, Jinah; Kim, Soon-Joong; Kim, Jung Ho; Kwon, Il Keun

2012-04-01

The mixture of poly(lactide-co-glycolide) (PLGA) and poly(ethylene vinyl acetate) (PEVA) forms a homogeneous liquid in an organic solvent such as tetrahydrofuran, and a phase-separated PLGA/PEVA composite can be prepared from it by evaporating the organic solvent. Exploiting this phenomenon, we designed a novel method of preparing a drug-loaded PLGA/PEVA composite and used it for coating drug-eluting stents (DESs). Paclitaxel (PTX), an anticancer drug, was chosen as a model drug. PLGA acts as a microdepot for PTX, and PEVA provides mechanical strength to the coating material. The presence of PLGA in the PLGA/PEVA composite suppressed PTX crystallization in the coating material, and PTX showed a sustained release rate over more than 30 days. The mechanical strength of the PLGA/PEVA composite was better than that of PEVA used as a control. After coating the stent with a PLGA/PEVA composite using ultrasonic atomizing spray, the morphology of the coated material was observed by scanning electron microscopy, and the release pattern of PTX was measured by high-performance liquid chromatography.

Anionic polymer, poly(methyl vinyl ether-maleic anhydride)-coated beads-based capture of human influenza A and B virus.

PubMed

Sakudo, Akikazu; Baba, Koichi; Tsukamoto, Megumi; Sugimoto, Atsuko; Okada, Takashi; Kobayashi, Takanori; Kawashita, Norihito; Takagi, Tatsuya; Ikuta, Kazuyoshi

2009-01-15

An anionic magnetic beads-based method was developed for the capture of human influenza A and B viruses from nasal aspirates, allantoic fluid and culture medium. A polymer, poly(methyl vinyl ether-maleic anhydride) [poly(MVE-MA)], was used to endow magnetic beads with a negative charge and bioadhesive properties. After incubation with samples containing human influenza virus, the beads were separated from supernatants by applying a magnetic field. The adsorption [corrected] of the virus by the beads was confirmed by hemagglutinin assay, immunochromatography, Western blotting, egg infection, and cell infection. Successful capture was proved using 5 H1N1 influenza A viruses, 10 H3N2 influenza A viruses, and 6 influenza B viruses. Furthermore, the infectivity in chicken embryonated eggs and Madin-Darby canine kidney (MDCK) cells of the captured human influenza virus was similar to that of the total viral quantity of starting materials. Therefore, this method of capture using magnetic beads coated with poly(MVE-MA) can be broadly used for the recovery of infectious human influenza viruses.

Glycolipid class profiling by packed-column subcritical fluid chromatography.

PubMed

Deschamps, Frantz S; Lesellier, Eric; Bleton, Jean; Baillet, Arlette; Tchapla, Alain; Chaminade, Pierre

2004-06-18

The potential of packed-column subcritical fluid chromatography (SubFC) for the separation of lipid classes has been assessed in this study. Three polar stationary phases were checked: silica, diol, and poly(vinyl alcohol). Carbon dioxide (CO2) with methanol as modifier was used as mobile phase and detection performed by evaporative light scattering detection. The influence of methanol content, temperature, and pressure on the chromatographic behavior of sphingolipids and glycolipids were investigated. A complete separation of lipid classes from a crude wheat lipid extract was achieved using a modifier gradient from 10 to 40% methanol in carbon dioxide. Solute selectivity was improved using coupled silica and diol columns in series. Because the variation of eluotropic strength depending on the fluid density changes, a normalized separation factor product (NSP) was used to select the nature, the number and the order of the columns to reach the optimum glycolipid separation.

Lysozyme immobilization onto PVC catheters grafted with NVCL and HEMA for reduction of bacterial adhesion

NASA Astrophysics Data System (ADS)

Guadarrama-Zempoalteca, Yesica; Díaz-Gómez, Luis; Meléndez-Ortiz, H. Iván; Concheiro, Angel; Alvarez-Lorenzo, Carmen; Bucio, Emilio

2016-09-01

The aim of the present work was to functionalize poly(vinyl chloride) (PVC) urinary catheters with grafted copolymers that can improve the biocompatibility and serve as binding points of lysozyme. PVC catheters were modified by grafting a mixture of N-vinylcaprolactam (NVCL) and 2-hydroxyethylmethacrylate (HEMA) applying a gamma-ray pre-irradiation method. The effect of absorbed dose, monomer concentration, temperature, and reaction time on the grafting percentage was evaluated. The grafted catheters were characterized regarding surface composition (FTIR-ATR spectroscopy), thermal properties (DSC and TGA) and swelling in aqueous medium. Lysozyme was directly coupled onto PVC-g-(NVCL/HEMA) previously activated using carbonyldiimidazole. Antimicrobial lytic activity of the modified catheters over time was tested against Micrococcus lysodeikticus. Lysozyme diminished the adhesion of Staphylococcus aureus onto the functionalized catheters, which may be suitable to prevent biofilm formation.

pH and Glucose Dual-Responsive Injectable Hydrogels with Insulin and Fibroblasts as Bioactive Dressings for Diabetic Wound Healing.

PubMed

Zhao, Lingling; Niu, Lijing; Liang, Hongze; Tan, Hui; Liu, Chaozong; Zhu, Feiyan

2017-11-01

pH and glucose dual-responsive injectable hydrogels were prepared through the cross-linking of Schiff's base and phenylboronate ester using phenylboronic-modified chitosan, poly(vinyl alcohol) and benzaldehyde-capped poly(ethylene glycol). Protein drugs and live cells could be incorporated into the hydrogels during the in situ cross-linking, displaying sustained and pH/glucose-triggered drug release from the hydrogels and cell viability and proliferation in the three-dimensional hydrogel matrix as well. Hence, the hydrogels with insulin and fibroblasts were considered as bioactive dressings for diabetic wound healing. A streptozotocin-induced diabetic rat model was used to evaluate the efficacy of hydrogel dressings in wound repair. The results revealed that the incorporation of insulin and L929 in the hydrogels could promote neovascularization and collagen deposition and enhance the wound-healing process of diabetic wounds. Thus, the drug- and cell-loaded hydrogels have promising potential in wound healing as a medicated system for various therapeutic proteins and live cells.

Versatile wettability gradients prepared by chemical modification of polymer brushes on polymer foils.

PubMed

Neuhaus, Sonja; Padeste, Celestino; Spencer, Nicholas D

2011-06-07

A method to create a wettability gradient by variation of the chemical functionality in a polymer brush is presented. A poly(N-methyl-vinylpyridinium) (QP4VP) brush was created on a poly(ethylene-alt-tetrafluoroethylene) (ETFE) foil by the grafting of 4-vinylpyridine and subsequent quaternization. The instability of QP4VP, a strong polyelectrolyte, in alkaline media was exploited to transform it to the neutral poly(vinyl(N-methyl-2-pyridone)) (PVMP), as confirmed with ATR-IR spectroscopy. The slow transformation resulted in a substantial, time-dependent decrease in wettability. A nearly linear gradient in water contact angle (CA) was created by immersion of a QP4VP brush modified sample into a sodium hydroxide solution, resulting in CAs ranging from 10° to 60°. The concurrent decrease in the number of charged functional groups along the gradient was characterized by loading an anionic dye into the polymer brush and measuring the UV transmittance of the sample. The versatility of the wettability gradient was demonstrated by exchanging the counterions of the N-methyl-vinylpyridinium groups, whereby a reversal of gradient direction was reproducibly achieved.

Synthesis and characterization of poly (benzyl trimethyl ammonium chloride) ionic polymer

NASA Astrophysics Data System (ADS)

Mathew, Manjusha Elizabeth; Ahmad, Ishak; Thomas, Sabu; Daik, Rusli; Kassim, Muhammad

2018-04-01

Poly vinyl benzyl chloride (PVBC) was synthesized by free radical polymerization of 4-vinyl benzyl chloride (VBC) using benzoyl peroxide initiator at 80°C. Amine functionalised polymer prepared by treatment of PVBC with trimethyl amine in different solvents such as water, ethanol, tetra hydro furan(THF) and dimethyl formamide(DMF). The polymers characterized structurally by nuclear magnetic resonance and infrared spectroscopic techniques. The thermal decomposition of the polymer is studied by Thermo Gravimetric Analysis(TGA) and found that the polymer has stability up to 230°C. The nitrogen content of the aminated polymer determined by elemental analysis. The nitrogen content obtained from tetra hydro furan and dimethyl formamide solvents are 20.1% and 19.9% respectively.

Birefringence and dichroism of poly(vinyl-alcohol) foils containing phthalazinium ylids

NASA Astrophysics Data System (ADS)

Rogojanu, Alina; Dascalu, Carmen Felicia; Zelinschi, Beatrice Carmen; Caprosu, Maria; Dorohoi, Dana Ortansa

2011-10-01

Pure and colored with phthalazinium ylids poly(vinyl-alcohol) (PVA) foils were stretched under gentile heating. The birefringence of the thin foils was determined with a Babinet compensator standardized for yellow radiation of a Sodium lamp. The determined birefringence of the colored PVA foils is higher than that of the pure PVA foils. This fact indicates that the phthalazinium ylids facilitate the increase in the anisotropy of the stretched foils. The visible absorption electronic band of phthalazinium ylids was used to estimate the dichroic ratio and the degree of order of the ylid molecules in the stretched PVA foils. An increase in dichroism and birefringence with the degree of stretching has been evidenced for uncolored and colored PVA foils.

Electro–optical properties of poly(vinyl acetate)/polyindole composite film

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

Bhagat, D. J., E-mail: bhagatd@rediffmail.com; Dhokane, G. R.; Bajaj, N. S.

2016-05-06

In present work, electrical and optical properties of poly(vinyl acetate)/polyindole (PVAc/PIN) composite film are reported. The prepared composite was characterized via X–ray diffraction (XRD), UV–Vis spectroscopy and DC conductivity measurements. The polymer chain separation was determined using XRD analysis. An attempt has been made to study the temperature dependence of DC conductivity of PVAc/PIN composite in temperature range 308–373 K. The DC conductivity initially increases and reaches to 2.45×10–7 S/cm. The optical band gap value of composite is determined as 4.77 eV. The semiconducting nature of composite observed from electronic as well as optical band gap and Arrhenius behavior of DCmore » plot.« less

Polyelectrolyte and carbon nanotube multilayers made from ionic liquid solutions

NASA Astrophysics Data System (ADS)

Nakashima, Takuya; Zhu, Jian; Qin, Ming; Ho, Szushen; Kotov, Nicholas A.

2010-10-01

The inevitable contact of substrates with water during the traditional practice of layer-by-layer assembly (LBL) creates problems for multiple potential applications of LBL films in electronics. To resolve this issue, we demonstrate here the possibility of a LBL process using ionic liquids (ILs), which potentially eliminates corrosion and hydration processes related to aqueous media and opens additional possibilities in structural control of LBL films. ILs are also considered to be one of the best ``green'' processing solvents, and hence, are advantageous in respect to traditional organic solvents. Poly(ethyleneimine) (PEI) and poly(sodium styrenesulfonate) (PSS) were dispersed in a hydrophilic IL and successfully deposited in the LBL fashion. To produce electroactive thin films with significance to electronics, a similar process was realized for PSS-modified single-walled carbon nanotubes (SWNT-PSS) and poly(vinyl alcohol) (PVA). Characterization of the coating using standard spectroscopy and microscopy techniques typical of the multilayer field indicated that there are both similarities and differences in the structure and properties of LBL films build from ILs and aqueous solutions. The films exhibited electrical conductivity of 102 S m-1 with transparency as high as 98% for visible light, which is comparable to similar parameters for many carbon nanotube and graphene films prepared by both aqueous LBL and other methods.The inevitable contact of substrates with water during the traditional practice of layer-by-layer assembly (LBL) creates problems for multiple potential applications of LBL films in electronics. To resolve this issue, we demonstrate here the possibility of a LBL process using ionic liquids (ILs), which potentially eliminates corrosion and hydration processes related to aqueous media and opens additional possibilities in structural control of LBL films. ILs are also considered to be one of the best ``green'' processing solvents, and hence, are advantageous in respect to traditional organic solvents. Poly(ethyleneimine) (PEI) and poly(sodium styrenesulfonate) (PSS) were dispersed in a hydrophilic IL and successfully deposited in the LBL fashion. To produce electroactive thin films with significance to electronics, a similar process was realized for PSS-modified single-walled carbon nanotubes (SWNT-PSS) and poly(vinyl alcohol) (PVA). Characterization of the coating using standard spectroscopy and microscopy techniques typical of the multilayer field indicated that there are both similarities and differences in the structure and properties of LBL films build from ILs and aqueous solutions. The films exhibited electrical conductivity of 102 S m-1 with transparency as high as 98% for visible light, which is comparable to similar parameters for many carbon nanotube and graphene films prepared by both aqueous LBL and other methods. Electronic supplementary information (ESI) available: Aggregation of PEI and PSS in [EMIm][EtSO4], detailed FTIR data, water-contact angle for (PEI/PSS)10 multilayers, and XPS survey spectra. See DOI: 10.1039/b9nr00333a

Use of marker ion and cationic surfactant plastic membrane electrode for potentiometric titration of cationic polyelectrolytes.

PubMed

Masadome, Takashi; Imato, Toshihiko

2003-07-04

A plasticized poly (vinyl chloride) (PVC) membrane electrode sensitive to stearyltrimethylammonium (STA) ion is applied to the determination of cationic polyelectrolytes such as poly (diallyldimethylammonium chloride) (Cat-floc) by potentiometric titration, using a potassium poly (vinyl sulfate) (PVSK) solution as a titrant. The end-point of the titration is detected as the potential change of the plasticized PVC membrane electrode caused by decrease in the concentration of STA ion added to the sample solution as a marker ion due to the ion association reaction between the STA ion and PVSK. The effects of the concentration of STA ion, coexisting electrolytes in the sample solution and pH of the sample on the degree of the potential change at the end-point were examined. A linear relationship between the concentration of cationic polyelectrolyte and the end-point volume of the titrant exists in the concentration range from 2x10(-5) to 4x10(-4) N for Cat-floc, glycol chitosan, and methylglycol chitosan.

Potentiometric titration of polyhexamethylene biguanide hydrochloride with potassium poly(vinyl sulfate) solution using a cationic surfactant-selective electrode.

PubMed

Masadome, Takashi; Yamagishi, Yuichi; Takano, Masaki; Hattori, Toshiaki

2008-03-01

A potentiometric titration method using a cationic surfactant as an indicator cation and a plasticized poly(vinyl chloride) membrane electrode sensitive to the cationic surfactant is proposed for the determination of polyhexamethylene biguanide hydrochloride (PHMB-HCl), which is a cationic polyelectrolyte. A sample solution of PHMB-HCl containing an indicator cation (hexadecyltrimethylammonium ion, HTA) was titrated with a standard solution of an anionic polyelectrolyte, potassium poly(vinyl sulfate) (PVSK). The end-point was detected as a sharp potential change due to an abrupt decrease in the concentration of the indicator cation, HTA, which is caused by its association with PVSK. The effects of the concentrations of HTA ion and coexisting electrolytes in the sample solution on the degree of the potential change at the end-point were examined. A linear relationship between the concentration of PHMB-HCl and the end-point volume of the titrant exists in the concentration range from 2.0 x 10(-5) to 4.0 x 10(-4) M in the case that the concentration of HTA is 1.0 x 10(-5) M, and that from 1.0 x 10(-6) to 1.2 x 10(-5) M in the case that the concentration of HTA is 5.0 x 10(-6) M, respectively. The proposed method was applied to the determination of PHMB-HCl in some contact-lens detergents.

New insights on poly(vinyl acetate)-based coated floating tablets: characterisation of hydration and CO2 generation by benchtop MRI and its relation to drug release and floating strength.

PubMed

Strübing, Sandra; Abboud, Tâmara; Contri, Renata Vidor; Metz, Hendrik; Mäder, Karsten

2008-06-01

The purpose of this study was to investigate the mechanism of floating and drug release behaviour of poly(vinyl acetate)-based floating tablets with membrane controlled drug delivery. Propranolol HCl containing tablets with Kollidon SR as an excipient for direct compression and different Kollicoat SR 30 D/Kollicoat IR coats varying from 10 to 20mg polymer/cm2 were investigated regarding drug release in 0.1N HCl. Furthermore, the onset of floating, the floating duration and the floating strength of the device were determined. In addition, benchtop MRI studies of selected samples were performed. Coated tablets with 10mg polymer/cm2 SR/IR, 8.5:1.5 coat exhibited the shortest lag times prior to drug release and floating onset, the fastest increase in and highest maximum values of floating strength. The drug release was delayed efficiently within a time interval of 24 h by showing linear drug release characteristics. Poly(vinyl acetate) proved to be an appropriate excipient to ensure safe and reliable drug release. Floating strength measurements offered the possibility to quantify the floating ability of the developed systems and thus to compare different formulations more efficiently. Benchtop MRI studies allowed a deeper insight into drug release and floating mechanisms noninvasively and continuously.

Antifreeze (glyco)protein mimetic behavior of poly(vinyl alcohol): detailed structure ice recrystallization inhibition activity study.

PubMed

Congdon, Thomas; Notman, Rebecca; Gibson, Matthew I

2013-05-13

This manuscript reports a detailed study on the ability of poly(vinyl alcohol) to act as a biomimetic surrogate for antifreeze(glyco)proteins, with a focus on the specific property of ice-recrystallization inhibition (IRI). Despite over 40 years of study, the underlying mechanisms that govern the action of biological antifreezes are still poorly understood, which is in part due to their limited availability and challenging synthesis. Poly(vinyl alcohol) (PVA) has been shown to display remarkable ice recrystallization inhibition activity despite its major structural differences to native antifreeze proteins. Here, controlled radical polymerization is used to synthesize well-defined PVA, which has enabled us to obtain the first quantitative structure-activity relationships, to probe the role of molecular weight and comonomers on IRI activity. Crucially, it was found that IRI activity is "switched on" when the polymer chain length increases from 10 and 20 repeat units. Substitution of the polymer side chains with hydrophilic or hydrophobic units was found to diminish activity. Hydrophobic modifications to the backbone were slightly more tolerated than side chain modifications, which implies an unbroken sequence of hydroxyl units is necessary for activity. These results highlight that, although hydrophobic domains are key components of IRI activity, the random inclusion of addition hydrophobic units does not guarantee an increase in activity and that the actual polymer conformation is important.

Deproteinised natural rubber latex grafted poly(dimethylaminoethyl methacrylate) - poly(vinyl alcohol) blend membranes: Synthesis, properties and application.

PubMed

Jayadevan, Janisha; Alex, Rosamma; Gopalakrishnapanicker, Unnikrishnan

2018-02-01

Natural rubber latex was initially deproteinised (DNRL) and then subjected to physicochemical modifications to make high functional membranes for drug delivery applications. Initially, DNRL was prepared by incubating with urea, sodiumdodecylsulphate and acetone followed by centrifugation. The deproteinisation was confirmed by CHN analysis. The DNRL was then chemically modified by grafting (dimethylaminoethyl methacrylate) onto NR particles by using a redox initiator system viz; cumene hydroperoxide/tetraethylenepentamine, followed by dialysis for purification. The grafting was confirmed by dynamic light scattering, Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. The grafted system was blended with a hydrophilic adhesive polymer PVA and casted into membranes. The membranes after blending showed enhanced mechanical properties with a threshold concentration of PVA. The moisture uptake, swelling and water contact angle experiments indicated an increased hydrophilicity with an increased PVA content in the blend membranes. The grafted DNRL possessed significant antibacterial property which has been found to be retained in the blended form. A notable decrease in cytotoxicity was observed for the modified DNRL membranes than the bare DNRL membranes. The in-vitro drug release studies using rhodamine B as a model drug, confirmed the utility of the prepared membranes to function as a drug delivery matrix. Copyright © 2017 Elsevier B.V. All rights reserved.

Facile fabrication of mesoporous poly(ethylene-co-vinyl alcohol)/chitosan blend monoliths.

PubMed

Wang, Guowei; Xin, Yuanrong; Uyama, Hiroshi

2015-11-05

Poly(ethylene-co-vinyl alcohol) (EVOH)/chitosan blend monoliths were fabricated by thermally-induced phase separation method. Chitosan was successfully incorporated into the polymeric monolith by selecting EVOH as the main component of the monolith. SEM images exhibit that the chitosan was located on the inner surface of the monolith. Fourier-transform infrared analysis and elemental analysis indicate the successful blend of EVOH and chitosan. BET results show that the blend monoliths had high specific surface area and uniform mesopore structure. Good adsorption ability toward various heavy metal ions was found in the blend monoliths due to the large chelation capacity of chitosan. The blend monoliths have potential application for waste water purification or bio-related applications. Copyright © 2015 Elsevier Ltd. All rights reserved.

Refractive index investigation of poly(vinyl alcohol) films with TiO2 nanoparticle inclusions.

PubMed

Yovcheva, Temenuzhka; Vlaeva, Ivanka; Bodurov, Ivan; Dragostinova, Violeta; Sainov, Simeon

2012-11-10

The refractive index (RI) of polymer nanocomposite of poly(vinyl alcohol) films with TiO(2) nanoparticle inclusions with low concentration up to 1.2 wt. % was investigated. Accurate refractometric measurements, by a specially designed laser microrefractometer, were performed at wavelengths 532 and 632.8 nm. The influence of TiO(2) concentration on the RI dispersion curves was predicted based on the well-known Sellmeier model. The theoretical analysis, in a small filling factor approximation, was performed, and a relation between the effective RI of the nanocomposite and weight concentrations of the TiO(2) nanofiller was derived. The experimental values were approximated by two different functions (linear and a quadratic polynom). The polynomial approximation yields better result, where R(2)=0.90.

Effect of trap states and microstructure on charge carrier conduction mechanism through semicrystalline poly(vinyl alcohol) granular film

NASA Astrophysics Data System (ADS)

Das, A. K.; Bhowmik, R. N.; Meikap, A. K.

2018-05-01

We report a comprehensive study on hysteresis behaviour of current-voltage characteristic and impedance spectroscopy of granular semicrystalline poly(vinyl alcohol) (PVA) film. The charge carrier conduction mechanism and charge traps of granular PVA film by measuring and analyzing the temperature dependent current-voltage characteristic indicate a bi-stable electronic state in the film. A sharp transformation of charge carrier conduction mechanism from Poole-Frenkel emission to space charge limited current mechanism has been observed. An anomalous oscillatory behaviour of current has been observed due to electric pulse effect on the molecular chain of the polymer. Effect of microstructure on charge transport mechanism has been investigated from impedance spectroscopy analysis. An equivalent circuit model has been proposed to explain the result.

Topologically Micropatterned Collagen and Poly(ε-caprolactone) Struts Fabricated Using the Poly(vinyl alcohol) Fibrillation/Leaching Process To Develop Efficiently Engineered Skeletal Muscle Tissue.

PubMed

Kim, Minseong; Kim, WonJin; Kim, GeunHyung

2017-12-20

Optimally designed three-dimensional (3D) biomedical scaffolds for skeletal muscle tissue regeneration pose significant research challenges. Currently, most studies on scaffolds focus on the two-dimensional (2D) surface structures that are patterned in the micro-/nanoscales with various repeating sizes and shapes to induce the alignment of myoblasts and myotube formation. The 2D patterned surface clearly provides effective analytical results of pattern size and shape of the myoblast alignment and differentiation. However, it is inconvenient in terms of the direct application for clinical usage due to the limited thickness and 3D shapeability. Hence, the present study suggests an innovative hydrogel or synthetic structure that consists of uniaxially surface-patterned cylindrical struts for skeleton muscle regeneration. The alignment of the pattern on the hydrogel (collagen) and poly(ε-caprolactone) struts was attained with the fibrillation of poly(vinyl alcohol) and the leaching process. Various cell culture results indicate that the C2C12 cells on the micropatterned collagen structure were fully aligned, and that a significantly high level of myotube formation was achieved when compared to the collagen structures that were not treated with the micropatterning process.

Singlet oxygenation of 1,2-poly/1,4-hexadiene/s

NASA Technical Reports Server (NTRS)

Golub, M. A.; Rosenberg, M. L.; Gemmer, R. V.

1979-01-01

The microstructural changes that occur in cis and trans forms of 1,2-poly(1,4-hexadiene) during methylene blue-photosensitized oxidation were examined by infrared and (C-13)-NMR spectroscopy. The singlet oxygenation of these polymers yielded the expected allylic hydroperoxides accompanied by double bond shifts to new vinyl and trans-vinylene double bonds. The photosensitized oxidation exhibited zero-order kinetics; the relative rates for the cis- and trans-1,2-poly(1,4-hexadiene)s were approximately 3.8:1.0.

Small Angle Neutron Scattering Studies on Blends of Poly (Styrene-ran-Vinyl Phenol) with Liquid Crystalline Polyurethane

NASA Astrophysics Data System (ADS)

Mehta, Rujul

2005-03-01

Molecular composites, composed of uniformly dispersed rigid-rod liquid crystalline polymer (LCP) molecules in a flexible amorphous polymer matrix, have remained hitherto elusive due to a scarcity of miscible systems containing a LCP and an amorphous polymer. The production of such a blend, with an experimentally accessible miscibility window, has become possible by modifying the architecture of the flexible polymer, so as to induce favorable intermolecular hydrogen bonding. Specifically, liquid crystalline polyurethanes (LCPU) are found to be miscible with a copolymer of styrene and vinyl phenol; with optimum hydrogen bonding between the carbonyl groups of the urethane linkages and the hydroxyl groups present in the styrenic matrix. Availability of a truly miscible molecular composite presents a unique opportunity of studying the confirmation of polymer chains containing rigid-rods that are uniformly dispersed in a flexible coil matrix. A system consisting of the LCPU and the deuterated styrenic copolymer containing 20% vinyl phenol is examined by Small Angle Neutron Scattering at the National Center for Neutron Research at Gaithersburg and Technology, and the Institute of Solid State Research (IFF) at Jülich. Scattering curves for neat dPS-VPh did not fit the Debye-Bueche model; indicating complex structure. A two correlation length Debye-Bueche model was considered to accommodate for this nonlinear behavior. This model utilizes four fitting parameters, including two correlation lengths a1 and a2, corresponding to a Debye-Bueche model and Guinier model.

21 CFR 178.3790 - Polymer modifiers in semirigid and rigid vinyl chloride plastics.

Code of Federal Regulations, 2012 CFR

2012-04-01

... chemical reactions, other than addition reactions, occur when they are mixed. (2) Polymers identified in...; provided that no chemical reactions, other than addition reactions, occur when they are combined. Such..., other than addition reactions, occur among the vinyl chloride polymers and the modifying polymers...

21 CFR 178.3790 - Polymer modifiers in semirigid and rigid vinyl chloride plastics.

Code of Federal Regulations, 2013 CFR

2013-04-01

... chemical reactions, other than addition reactions, occur when they are mixed. (2) Polymers identified in...; provided that no chemical reactions, other than addition reactions, occur when they are combined. Such..., other than addition reactions, occur among the vinyl chloride polymers and the modifying polymers...

Physical and chemical basics of modification of poly(vinyl chloride) by means of polyisocyanate

NASA Astrophysics Data System (ADS)

Islamov, Anvar; Fakhrutdinova, Venera; Abdrakhmanova, Lyailya

2016-01-01

This research presents data relating to polyvinyl chloride (PVC) modification by means of reactive oligomer and measures technological, physical and mechanical properties of the modified composites. Polyisocyanate (PIC) has been chosen as the modifying reactive oligomer. It has been shown that insertion of the oligomer has a double effect on PVC. Primarily, PIC produces a plasticizing effect on PVC and in particular leads to an increase in thermal stability and melt flow index at the stage of processing. In addition, the molded PVC composites possess higher strength properties and lower deformability when exposed to temperature because of chemical transformations of PIC in polymer matrix and, as the result, the formation of cross-linked systems takes place. In this case, semi-interpenetrating structures are formed based on cross-linked products of PIC chemical transformations homogeneously distributed in the PVC matrix. It has been determined by means of IR-spectroscopy that the basic products of PIC curing are compounds with urea and biuret groups which leads to modifying effect on PVC especially: increase in strength, thermal and mechanical properties, and chemical resistance.

Ultrasonic-assisted fabrication and characterization of PVC-SiO2 nanocomposites having bovine serum albumin as a bio coupling agent.

PubMed

Mallakpour, Shadpour; Nazari, Hossein Yazdan

2017-11-01

In this work, SiO 2 nanoparticles (NPs) were modified with bovine serum albumin (BSA) under ultrasound irradiations as a green and fast route to achieve their good dispersion. Subsequently, different weight percentages of the modified NPs (3, 6, and 9wt%) were incorporated in poly(vinyl chloride) (PVC) as the matrix. Thermogravimetric analysis of the SiO 2 -BSA NPs indicated that 12wt% of the modifier was loaded on the surface of SiO 2 NPs. Encapsulation of the SiO 2 -BSA resulted in a meaningful improvement in the optical, mechanical and thermal characteristics of the prepared PVC nanocomposites (NCs). X-ray diffraction (XRD) patterns for the PVC/SiO 2 -BSA NCs showed a crystalline behavior for the NC with 6wt% of the SiO 2 -BSA originated from the phosphate buffer on the NPs. Water contact angle of the PVC/SiO 2 -BSA NCs showed that the hydrophilicity enhanced with increasing of the NPs contents. Copyright © 2017 Elsevier B.V. All rights reserved.

Photoinduced crystallization of calcium carbonate from a homogeneous precursor solution in the presence of partially hydrolyzed poly(vinyl alcohol)

NASA Astrophysics Data System (ADS)

Nishio, Takashi; Naka, Kensuke

2015-04-01

Photoinduced crystallization of calcium carbonate (CaCO3) was demonstrated by the photodecarboxylation of ketoprofen (KP, 2-(3-benzoylphenyl)propionic acid) under alkaline conditions (pH 10). In this method, a homogeneous solution comprising KP, calcium chloride, ammonia, and partially hydrolyzed poly(vinyl alcohol) (PVAPS, degree of saponification: 86.5-89.0 mol %) was used as the precursor solution and was exposed to ultraviolet (UV) irradiation for different time periods. Thermogravimetric analysis of the obtained xerogels showed that increasing the UV irradiation time increased the amount of CaCO3 formed and the complete conversion of calcium ions to calcite was achieved after 50 min of UV irradiation. Furthermore, solid phase analyses suggested that nanometer-to-micron-sized calcite crystals were formed and dispersed in the obtained PVAPS matrix.

Activation of Ice Recrystallization Inhibition Activity of Poly(vinyl alcohol) using a Supramolecular Trigger.

PubMed

Phillips, Daniel J; Congdon, Thomas R; Gibson, Matthew I

2016-03-07

Antifreeze (glyco)proteins (AF(G)Ps) have potent ice recrystallisation inhibition (IRI) activity - a desirable phenomenon in applications such as cryopreservation, frozen food and more. In Nature AF(G)P activity is regulated by protein expression levels in response to an environmental stimulus; temperature. However, this level of regulation is not possible in synthetic systems. Here, a synthetic macromolecular mimic is introduced, using supramolecular assembly to regulate activity. Catechol-terminated poly(vinyl alcohol) was synthesised by RAFT polymerization. Upon addition of Fe 3+ , larger supramolecular star polymers form by assembly with two or three catechols. This increase in molecular weight effectively 'switches on' the IRI activity and is the first example of external control over the function of AFP mimetics. This provides a simple but elegant solution to the challenge of external control of AFP-mimetic function.

Effect of γ irradiation on poly(vinyl alcohol) and bacterial cellulose composites used as packaging materials

NASA Astrophysics Data System (ADS)

Stoica-Guzun, Anicuta; Stroescu, Marta; Jipa, Iuliana; Dobre, Loredana; Zaharescu, Traian

2013-03-01

The aim of this paper is to present the influence of bacterial cellulose microfibrils and γ-radiation dose on poly(vinyl alcohol) (PVA)-bacterial cellulose (BC) composites. Two composite materials were obtained: the first one from PVA aqueous solution 4% and 5% wet bacterial cellulose and the second from the same PVA solution and 10% wet bacterial cellulose. In terms of PVA/dry BC ratios (w/w) for these films the ratios are 1/0.025 and 1/0.050. The obtained composite materials were characterized by infrared spectroscopy with Fourier transform (FT-IR) and UV-vis spectroscopy in order to evaluate the irradiation effect on their stability. The swelling behavior of the polymeric composites was also studied. The composite materials were compared with a film of pure PVA and a dry BC membrane.

Microplasma Processed Ultrathin Boron Nitride Nanosheets for Polymer Nanocomposites with Enhanced Thermal Transport Performance.

PubMed

Zhang, Ri-Chao; Sun, Dan; Lu, Ai; Askari, Sadegh; Macias-Montero, Manuel; Joseph, Paul; Dixon, Dorian; Ostrikov, Kostya; Maguire, Paul; Mariotti, Davide

2016-06-01

This Research Article reports on the enhancement of the thermal transport properties of nanocomposite materials containing hexagonal boron nitride in poly(vinyl alcohol) through room-temperature atmospheric pressure direct-current microplasma processing. Results show that the microplasma treatment leads to exfoliation of the hexagonal boron nitride in isopropyl alcohol, reducing the number of stacks from >30 to a few or single layers. The thermal diffusivity of the resulting nanocomposites reaches 8.5 mm(2) s(-1), 50 times greater than blank poly(vinyl alcohol) and twice that of nanocomposites containing nonplasma treated boron nitride nanosheets. From TEM analysis, we observe much less aggregation of the nanosheets after plasma processing along with indications of an amorphous carbon interfacial layer, which may contribute to stable dispersion of boron nitride nanosheets in the resulting plasma treated colloids.

Proton-conducting membrane based on epoxy resin-poly(vinyl alcohol)-sulfosuccinic acid blend and its nanocomposite with sulfonated multiwall carbon nanotubes for fuel-cell application

NASA Astrophysics Data System (ADS)

Kakati, Nitul; Das, Gautam; Yoon, Young Soo

2016-01-01

A blend of poly(vinyl alcohol) (PVA) with diglycidyl ether of bisphenol-A (DGB) in the presence of sulfosuccinic acid (SSA) was investigated as hydrolytically-stable proton-conducting membrane. The PVA modification was carried out by varying the DGB:SSA ratio (20:20, 10:20, and 5:20). A nanocomposite of the blend (20:20) was prepared with sulfonated multiwall carbon nanotubes (viz., 1, 3 and 5 wt%). The water uptake behavior and the proton conductivity of the prepared membranes were evaluated. The ionic conductivity of the membranes and the water uptake behavior depended on the s-MWCNT and the DGB contents. The ionic conductivity showed an enhancement for the blend and for the nanocomposite membrane as compared to the pristine polymer.

Radiation preparation of drug carriers based polyacrylic acid (PAAc) using poly(vinyl pyrrolidone) (PVP) as a template polymer

NASA Astrophysics Data System (ADS)

Abd El-Rehim, H. A.; Hegazy, E. A.; Khalil, F. H.; Hamed, N. A.

2007-01-01

The present study deals with the radiation synthesis of stimuli response hydrophilic polymers from polyacrylic acid (PAAc). To maintain the property of PAAc and control the water swellibility for its application as a drug delivery system, radiation polymerization of AAc in the presence of poly(vinyl pyrrolidone) (PVP) as a template polymer was carried out. Characterization of the prepared PAA/PVP inter-polymer complex was investigated by determining gel content, swelling property, hydrogel microstructure and the release rate of caffeine as a model drug. The release rate of caffeine from the PAA/PVP inter-polymer complexes showed pH-dependency, and seemed to be mainly controlled by the dissolution rate of the complex above a p Ka of PAAc. The prepared inter-polymer complex could be used for application as drug carriers.

Thermal degradation and plasticizing mechanism of poly(vinyl chloride) plasticized with a novel cardanol derived plasticizer

NASA Astrophysics Data System (ADS)

Chen, J.; Nie, X. A.; Jiang, J. C.; Zhou, Y. H.

2018-01-01

A natural plasticizer cardanol derivatives glycidyl ether (CGE) was synthesized and employed as a plasticizer for the poly(vinyl chloride). The effect of CGE on thermal degradation of PVC films and its plasticizing mechanism were firstly reported. The molecular structure of CGE was characterized with Fourier transform infrared spectroscopy (FTIR). Thermal properties, degradation properties and compatibility of the PVC films were investigated by Differential scanning calorimeter analysis (DSC), Thermogravimetric analysis (TGA) and FTIR, respectively. Compared with the commercial plasticizers dioctylphthalate (DOP), CGE can endow PVC film with a decrease of 4.31 °C in glass transition temperature (Tg), an increase of 24.01 °C and 25.53 °C in 10% weight loss (T 10) and 50% weight loss (T 50) respectively, and a higher activetion energy of thermal degradation (Ea ).

Poly(naphthalene diimide) vinylene: solid state red emission and semiconducting properties for transistors

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

Liang, Xianfeng; Tan, Luxi; Liu, Zitong

Here in this work, a conjugated polymer PNV is developed, linking naphthalene diimide with a vinyl linkage. Owing to the C-H ∙∙∙O hydrogen bond between the carbonyl and the vinyl, PNV exhibits a high red emission with a quantum yield of 33.4% in the solid state while it shows n-type properties with an electron mobility up to 1.5 x 10 -3 cm 2 V -1 s -1 in organic field effect transistors, simultaneously.

Tensile Properties of Poly (N-vinyl caprolactam) Gels

NASA Technical Reports Server (NTRS)

Morgret, Leslie D.; Hinkley, Jeffrey A.

2004-01-01

N-vinyl caprolactam was copolymerized with ethylene glycol dimethacrylate using a free-radical initiator in alcohol/water solution. The resulting gels were thermally-responsive in water, undergoing an approximate fivefold reversible volume shrinkage between room temperature and ca. 50 C. Tensile testing showed that the stress-strain behavior was qualitatively different in the collapsed state above the temperature-induced transition. At the higher temperature, gels were stiffer, more ductile, and showed greater time dependence. Implications for the design of gel actuators are briefly discussed.

Poly(naphthalene diimide) vinylene: solid state red emission and semiconducting properties for transistors

DOE PAGES

Liang, Xianfeng; Tan, Luxi; Liu, Zitong; ...

2017-04-06

Here in this work, a conjugated polymer PNV is developed, linking naphthalene diimide with a vinyl linkage. Owing to the C-H ∙∙∙O hydrogen bond between the carbonyl and the vinyl, PNV exhibits a high red emission with a quantum yield of 33.4% in the solid state while it shows n-type properties with an electron mobility up to 1.5 x 10 -3 cm 2 V -1 s -1 in organic field effect transistors, simultaneously.

Miscibility Studies on Polymer Blends Modified with Phytochemicals

NASA Astrophysics Data System (ADS)

Chandrasekaran, Neelakandan; Kyu, Thein

2009-03-01

The miscibility studies related to an amorphous poly(amide)/poly(vinyl pyrrolidone) [PA/PVP] blend with a crystalline phytochemical called ``Mangiferin'' is presented. Phytochemicals are plant derived chemicals which intrinsically possess multiple salubrious properties that are associated with prevention of diseases such as cancer, diabetes, cardiovascular disease, and hypertension. Incorporation of phytochemicals into polymers has shown to have very promising applications in wound healing, drug delivery, etc. The morphology of these materials is crucial to applications like hemodialysis, which is governed by thermodynamics and kinetics of the phase separation process. Hence, miscibility studies of PA/PVP blends with and without mangiferin have been carried out using dimethyl sulfoxide as a common solvent. Differential scanning calorimetry studies revealed that the binary PA/PVP blends were completely miscible at all compositions. However, the addition of mangiferin has led to liquid-liquid phase separation and liquid-solid phase transition in a composition dependent manner. Fourier transformed infrared spectroscopy was undertaken to determine specific interaction between the polymer constituents and the role of possible hydrogen bonding among three constituents will be discussed.

Host polymer influence on dilute polystyrene segmental dynamics

NASA Astrophysics Data System (ADS)

Lutz, T. R.

2005-03-01

We have utilized deuterium NMR to investigate the segmental dynamics of dilute (2%) d3-polystyrene (PS) chains in miscible polymer blends with polybutadiene, poly(vinyl ethylene), polyisoprene, poly(vinyl methylether) and poly(methyl methacrylate). In the dilute limit, we find qualitative differences depending upon whether the host polymer has dynamics that are faster or slower than that of pure PS. In blends where PS is the fast (low Tg) component, segmental dynamics are slowed upon blending and can be fit by the Lodge-McLeish model. When PS is the slow (high Tg) component, PS segmental dynamics speed up upon blending, but cannot be fit by the Lodge-McLeish model unless a temperature dependent self-concentration is employed. These results are qualitatively consistent with a recent suggestion by Kant, Kumar and Colby (Macromolecules, 2003, 10087), based upon data at higher concentrations. Furthermore, as the slow component, we find the segmental dynamics of PS has a temperature dependence similar to that of its host. This suggests viewing the high Tg component dynamics in a miscible blend as similar to a polymer in a low molecular weight solvent.

Anion effects on anti-microbial activity of poly[1-vinyl-3-(2-sulfoethyl imidazolium betaine)].

PubMed

Garg, Godawari; Chauhan, Ghanshyam S; Gupta, Reena; Ahn, J-H

2010-04-01

Recent investigations in the anti-microbial properties of the functional polymers are predominantly focused on the structure of the cationic moieties. In the present study, we investigated that the nature of the anion present in polysulfobetaines affects activity against certain microorganisms and their anti-microbial properties have been rationalized in terms of the structure-activity relationship. Vinyl imidazolium-based polysulfobetaines were prepared by the quaternization of poly(N-vinyl imidazole) with sodium salt of 2-bromo ethanesulfonic acid. The bromide counter anion of the resulting polymer was exchanged with different anions to generate a series of polymers. These were characterized by FTIR, DSC, XRD, SEM, elemental analysis (C, H, N and S) and viscosity measurements. The anti-microbial activity studies were carried against three fungi (Aspergillus niger, Byssochlamys fulva and Mucor circenelliods) and two bacteria (Bacillus coagulans BTS-3 and Pseudomonas aeruginosa BTS-2). The nature of the anion affects the structure of polysulfobetaine by realignment of polymer chains. The anion-dependent anti-microbial properties of polysulfobetaines result from the interaction of the microbes at the polymer interface. Copyright 2009 Elsevier Inc. All rights reserved.

Femtosecond laser microfabrication in polymers towards memory devices and microfluidic applications

NASA Astrophysics Data System (ADS)

Deepak, K. L. N.; Venugopal Rao, S.; Narayana Rao, D.

2011-12-01

We have investigated femtosecond laser induced microstructures, gratings, and craters in four different polymers: poly methyl methacrylate (PMMA), poly dimethyl siloxane (PDMS), polystyrene (PS) and poly vinyl alcohol (PVA) using Ti:sapphire laser delivering 800 nm, 100 femtosecond (fs) pulses at 1 kHz repetition rate with a maximum pulse energy of 1 mJ. Local chemical modifications leading to the formation of optical centers and peroxide radicals which were studied using UV-Visible absorption and emission, confocal micro-Raman and Electron Spin Resonance (ESR) spectroscopic techniques.

Hydrophilic porous magnetic poly(GMA-MBAA-NVP) composite microspheres containing oxirane groups: An efficient carrier for immobilizing penicillin G acylase

NASA Astrophysics Data System (ADS)

Xue, Ping; Su, Weiguang; Gu, Yaohua; Liu, Haifeng; Wang, Julan

2015-03-01

Magnetic hydrophilic polymeric microspheres containing oxirane groups were prepared by inverse suspension polymerization of glycidyl methacrylate (GMA), N, N‧-methylene bisacrylamide (MBAA) and N-vinyl pyrrolidone (NVP) in the existence of formamide, which were denoted as magnetic poly(GMA-MBAA-NVP) microspheres. The magnetic poly(GMA-MBAA-NVP) microspheres were characterized by scanning electron microscopy (SEM), FT-IR spectroscopy, X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and so on. The results showed that poly(GMA-MBAA-NVP) microspheres possessed well spherical shape, narrow size distribution, abundant porous structure, reactive oxirane groups and superparamagnetic properties. Formamide used in the present work served as a modifier, a dispersant and a porogen to form final porous polymer microspheres. The penicillin G acylase (PGA) was covalently immobilized onto the magnetic microspheres through the reaction between the amino groups of enzyme and the oxirane groups on the microspheres for producing 6-aminopenicillanic acid (6-APA). The effects of GMA/NVP ratio and crosslink density on the activity of immobilized PGA were investigated. The highest apparent activity, enzyme loading and coupling yield of immobilized PGA were 821 IU/g, 65.3 mg/g and 42.3% respectively when the mass ratio of GMA/NVP was 1:1 and crosslink density was 60%. Compared with the free PGA, immobilized PGA showed a wider range of pH value and reaction temperature. The relative activity and reaction rate of immobilized PGA remained almost constant after 20 recycles. The magnetic poly(GMA-MBAA-NVP) microspheres would be very promising carriers for immobilizing enzymes in industrial application.

Novel Fabrication of Biodegradable Superabsorbent Microspheres with Diffusion Barrier through Thermo-Chemical Modification and Their Potential Agriculture Applications for Water Holding and Sustained Release of Fertilizer.

PubMed

Feng, Diejing; Bai, Bo; Wang, Honglun; Suo, Yourui

2017-07-26

Synergistic utilization of water and fertilizer has vital contribution to the modern production of agriculture. This work reports on a simple and facile strategy to prepare biodegradable yeast/sodium alginate/poly(vinyl alcohol) superabsorbent microspheres with a diffusion barrier merit by thermo-chemical modification route. The integrated performances, including water absorbency, water retention, water evaporation ratio, leaching loss control, sustained-release behaviors, and degradation in soil, were systematically investigated. The results revealed that the modified microspheres were a triumphant water and fertilizer manager to effectively hold water and control the unexpected leakage of fertilizer for sustained release. Therefore, this work provides a promising approach to ameliorate the utilization efficiency of water and fertilizer in potential agriculture applications.

Organic Materials Chemistry

DTIC Science & Technology

2013-03-07

Carbon nanotubes + Paper ( cellulose fibers) Carbon nanotubes + Poly- ethyleneimeine (PEI) + NaBH4 treatment 21...Double-walled carbon nanotubes (DWNT) are stabilized with two different molecules in poly(vinyl acetate) latex:  PEDOT:PSS (conductive)  TCPP...2.5 3 3.5 0 200 400 600 800 1000 Tensile Modulus (GPa) C o m p re s s iv e S tr e n g th ( G P a ) Pitch Based Carbon Fibers PAN Based

Sulfonated poly(ether ether ketone)/poly(vinyl alcohol) sensitizing system for solution photogeneration of small Ag, Au, and Cu crystallites.

PubMed

Korchev, A S; Shulyak, T S; Slaten, B L; Gale, W F; Mills, G

2005-04-28

Illumination of air-free aqueous solutions containing sulfonated poly(ether ether ketone) and poly(vinyl alcohol) with 350 nm light results in benzophenone ketyl radicals of the polyketone. The polymer radicals form with a quantum yield 0.02 and decay with a second-order rate constant 6 orders of magnitude lower than that of typical alpha-hydroxy radicals. Evidence is presented that the polymeric benzophenone ketyl radicals reduce Ag+, Cu2+, and AuCl4- to metal particles of nanometer dimensions. Decreases in the reduction rates with increasing Ag(I), Cu(II), and Au(III) concentrations are explained using a kinetic model in which the metal ions quench the excited state of the polymeric benzophenone groups, which forms the macromolecular radicals. Quenching is fastest for Ag+, whereas Cu2+ and AuCl4- exhibit similar rate constants. Particle formation becomes more complex as the number of equivalents needed to reduce the metal ions increases; the Au(III) system is an extreme case where the radical reactions operate in parallel with secondary light-initiated and thermal reduction channels. For each metal ion, the polymer-initiated photoreactions produce crystallites possessing distinct properties, such as a very strong plasmon in the Ag case or the narrow size distribution exhibited by Au particles.

Characterization of charged polymer self-assemblies by multidetector thermal field-flow fractionation in aqueous mobile phases.

PubMed

Greyling, Guilaume; Pasch, Harald

2018-01-12

Charged block copolymer self-assemblies, such as charged micelles, have attracted much attention as versatile drug delivery systems due to their readily tunable characteristics such as size and surface charge. However, current column-based analytical techniques are not suitable to fractionate and comprehensively characterize charged micelles in terms of size, molar mass, chemical composition and morphology. Multidetector thermal field-flow fractionation (ThFFF) is shown to be a unique characterization platform that can be used to characterize charged micelles in terms of size, molar mass, chemical composition and morphology in aqueous mobile phases with various ionic strengths and pH. This is demonstrated by the characterization of poly(methacrylic acid)-b-poly(methyl methacrylate) self-assemblies in high pH buffers as well as the characterization of cationic poly(2-vinyl pyridine)-b-polystyrene and poly(4-vinyl pyridine)-b-polystyrene self-assemblies in low pH buffers. Moreover, it is shown that ThFFF is capable of separating charged micelles according to the corona composition. These investigations prove convincingly that ThFFF is broadly applicable to the comprehensive characterization of amphiphilic self-assemblies even when aqueous mobile phases are used. Copyright © 2017 Elsevier B.V. All rights reserved.

Kinetic and theoretical studies of novel biodegradable thermo-sensitive xerogels based on PEG/PVP/silica for sustained release of enrofloxacin

NASA Astrophysics Data System (ADS)

Ebadi, Azra; Rafati, Amir Abbas; Bavafa, Sadeghali; Mohammadi, Masoumah

2017-12-01

This study involves the synthesis of a new silica-based colloidal hybrid system. In this new hybrid system, poly (ethylene glycol) (PEG) and thermo-sensitive amphiphilic biocompatible poly (vinyl pyrrolidone) (PVP) were used to create suitable storage for hydrophobic drugs. The possibility of using variable PVP/PEG molar ratios to modulate drug release rate from silica nanoparticles was a primary goal of the current research. In addition, an investigation of the drug release kinetic was conducted. To achieve this, silica nanoparticles were synthesized in poly (ethylene glycol) (PEG) and poly (vinyl pyrrolidone) (PVP) solution incorporated with enrofloxacin (EFX) (as a model hydrophobic drug), using a simple synthetic strategy of hybrid materials which avoided waste and multi-step processes. The impacts of PVP/PEG molar ratios, temperature, and pH of the release medium on release kinetic were investigated. The physicochemical properties of the drug-loaded composites were studied by Fourier transform infrared (FT-IR) spectra, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). In vitro drug release studies demonstrated that the drug release rate, which was evaluated by analyzing the experimental data with seven kinetic models in a primarily non-Fickian diffusion-controlled process, aligned well with both Ritger-Peppas and Sahlin-Peppas equations.

Microwave irradiation induced modifications on the interfaces in SAN/EVA/PVC and PVAc/BPA/PVP ternary polymer blends: Positron lifetime study

NASA Astrophysics Data System (ADS)

Dinesh, Meghala; Chikkakuntappa, Ranganathaiah

2013-09-01

Ternary polymer blends of poly(styrene-co-acrylonitrile)/poly(ethylene-co-vinylacetate)/poly(vinyl chloride) (SAN/EVA/PVC) and poly(vinyl acetate)/bisphenol A/polyvinylpyrrolidone (PVAc/BPA/PVP) with different compositions have been prepared by solvent casting method and characterized by positron lifetime spectroscopy and differential scanning calorimetry DSC. Phase modifications have been induced by irradiating the blends with microwave radiation. These changes have been monitored by measuring the free-volume content in the blends. The results clearly show improved interactions between the constituent polymers of the blends upon microwave irradiation. However, the free-volume data and DSC measurements are found to be inadequate to reveal the changes at the interfaces and the interfaces determine the final properties of the blend. For this we have used hydrodynamic interaction (αij) approach developed by us to measure strength of hydrodynamic interaction at the interfaces. These results show that microwave irradiation stabilizes the interfaces if the blend contains strong polar groups. SAN/EVA/PVC blend shows an increased effective hydrodynamic interaction from -3.18 to -4.85 at composition 50/35/15 upon microwave irradiation and PVAc/BPA/PVP blend shows an increased effective hydrodynamic interaction from -3.81 to -7.57 at composition 20/50/30 after irradiation.

40 CFR 414.40 - Applicability; description of the thermoplastic resins subcategory.

Code of Federal Regulations, 2010 CFR

2010-07-01

... *Ethylene-Methacrylic Acid Copolymers *Ethylene-Vinyl Acetate Copolymers *Fatty Acid Resins *Fluorocarbon..., Acrylates (Latex) *PVC Copolymers, Ethylene-Vinyl Chloride *Rosin Derivative Resins *Rosin Modified Resins...

Magnetic properties of the Fe{sup II} spin crossover complex in emulsion polymerization of trifluoroethylmethacrylate using poly(vinyl alcohol)

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

Suzuki, Atsushi, E-mail: suzuki@mat.usp.ac.j; Iguchi, Motoi; Oku, Takeo

2010-04-15

Influence of chemical substitution in the Fe{sup II} spin crossover complex on magnetic properties in emulsion polymerization of trifluoroethylmethacrylate using poly(vinyl alcohol) as a protective colloid was investigated near its high spin/low spin (HS/LS) phase transition. The obvious bi-stability of the HS/LS phase transition was considered by the identification of multiple spin states between the quintet (S=2) states to single state (S=0) across the excited triplet state (S=1). Magnetic parameters of gradual shifts of anisotropy g-tensor supported by the molecular distortion of the spin crossover complex would arise from a Jahn-Teller effect regarding ligand field theory on the basis ofmore » a B3LYP density functional theory using electron spin resonance (ESR) spectrum and X-ray powder diffraction. - Graphical abstract: AFM surface image of the emulsion particles with the spin crossover complex.« less

Optical and morphological characterizations of pyronin dye-poly (vinyl alcohol) thin films formed on glass substrates

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

Meral, Kadem, E-mail: kademm@atauni.edu.tr; Arik, Mustafa, E-mail: marik@tatauni.edu.tr; Onganer, Yavuz, E-mail: yonganer@atauni.edu.tr

Thin films of pyronin dye mixed with poly(vinyl alcohol) (PVA) on glass substrate were prepared by using spin-coating technique. The optical and morphological properties of the thin films were studied by UV-Vis., steady-state fluorescence spectroscopies and atomic force microscopy (AFM). The thin films on glass substrate were fabricated at various [PVA]/[dye] (P/D) ratios. Hence, the monomeric and H-aggregates thin films of pyronin dye mixed with PVA were formed as a function of the dye and PVA concentration. It was determined that while the monomeric thin films showed strong fluorescence, the formation of H-aggregates in the thin film caused to decreasingmore » the fluorescence intensity. AFM studies demonstrated that the morphology of the thin film was drastically varied with changing the optical property of the thin film such as monomeric and H-aggregates thin films.« less

Novel alkyd-type coating resins produced using cationic polymerization

DOE PAGES

Chisholm, Bret J.; Kalita, Harjyoti; Alam, Samim; ...

2015-05-06

Novel, partially bio-based poly(vinyl ether) copolymers derived from soybean oil and cyclohexyl vinyl ether (CHVE) were produced by cationic polymerization and investigated for application as alkyd-type surface coatings. Compared to conventional alkyd resins, which are produced by high temperature melt condensation polymerization, the poly(v9nyl ether)s provide several advantages. These advantages include milder, more energy efficient polymer synthesis, elimination of issues associated with gelation during polymer synthesis, production of polymers with well-defined composition and relatively narrow molecular weight distribution, and elimination of film formation and physical property issues associated with entrained monomers, dimers, trimers, etc. The results of the studied showedmore » that the thermal, mechanical, and physical properties of the coatings produced from these novel polymers varied considerably as a function of polymer composition and cure temperature. Overall, the results suggest a good potential for these novel copolymers to be used for coatings cured by autoxidation.« less

Colorful Hydrophobic Poly(Vinyl Butyral)/Cationic Dye Fibrous Membranes via a Colored Solution Electrospinning Process

NASA Astrophysics Data System (ADS)

Yan, Xu; You, Ming-Hao; Lou, Tao; Yu, Miao; Zhang, Jun-Cheng; Gong, Mao-Gang; Lv, Fu-Yan; Huang, Yuan-Yuan; Long, Yun-Ze

2016-12-01

Colorful nanofibrous membranes have attracted much attention for their visual varieties and various functionalities. In this article, a colored solution electrospinning process was used to fabricate colorful hydrophobic poly(vinyl butyral) (PVB)/cationic dye nanofibrous membranes (NFMs) successfully. The color and morphology of these as-spun nanofibrous membranes have been analyzed by colorimetry, spectroscopy, and scanning electron microscopy (SEM). It is shown that the as-spun colorful PVB-based membranes exhibit excellent level-dyeing property and color stability. Furthermore, the doping of cationic dye and the increase of dye concentration can decrease the diameter of the as-spun colored fibers, which results in better level-dyeing property and higher water contact angle more than 140°. The stained PVB fibrous membranes with excellent level-dyeing property and hydrophobicity are promising in some applications such as textiles, wallpapers, and anticorrosive coating/painting.

Dynamics in poly vinyl alcohol (PVA) based hydrogel: Neutron scattering study

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

Prabhudesai, S. A., E-mail: swapnil@barc.gov.in; Mitra, S.; Mukhopadhyay, R.

2015-06-24

Results of quasielastic neutron scattering measurements carried out on Poly Vinyl Alcohol (PVA) based hydrogels are reported here. PVA hydrogels are formed using Borax as a cross-linking agent in D{sub 2}O solvent. This synthetic polymer can be used for obtaining the hydrogels with potential use in the field of biomaterials. The aim of this paper is to study the dynamics of polymer chain in the hydrogel since it is known that polymer mobility influences the kinetics of loading and release of drugs. It is found that the dynamics of hydrogen atoms in the polymer chain could be described by amore » model where the diffusion of hydrogen atoms is limited within a spherical volume of radius 3.3 Å. Average diffusivity estimated from the behavior of quasielastic width is found to be 1.2 × 10{sup −5} cm{sup 2}/sec.« less

Dynamics in poly vinyl alcohol (PVA) based hydrogel: Neutron scattering study

NASA Astrophysics Data System (ADS)

Prabhudesai, S. A.; Lawrence, Mathias B.; Mitra, S.; Desa, J. A. E.; Mukhopadhyay, R.

2015-06-01

Results of quasielastic neutron scattering measurements carried out on Poly Vinyl Alcohol (PVA) based hydrogels are reported here. PVA hydrogels are formed using Borax as a cross-linking agent in D2O solvent. This synthetic polymer can be used for obtaining the hydrogels with potential use in the field of biomaterials. The aim of this paper is to study the dynamics of polymer chain in the hydrogel since it is known that polymer mobility influences the kinetics of loading and release of drugs. It is found that the dynamics of hydrogen atoms in the polymer chain could be described by a model where the diffusion of hydrogen atoms is limited within a spherical volume of radius 3.3 Å. Average diffusivity estimated from the behavior of quasielastic width is found to be 1.2 × 10-5 cm2/sec.

Activation of Ice Recrystallization Inhibition Activity of Poly(vinyl alcohol) using a Supramolecular Trigger†

PubMed Central

Phillips, Daniel J.; Congdon, Thomas R.; Gibson, Matthew I.

2016-01-01

Antifreeze (glyco)proteins (AF(G)Ps) have potent ice recrystallisation inhibition (IRI) activity – a desirable phenomenon in applications such as cryopreservation, frozen food and more. In Nature AF(G)P activity is regulated by protein expression levels in response to an environmental stimulus; temperature. However, this level of regulation is not possible in synthetic systems. Here, a synthetic macromolecular mimic is introduced, using supramolecular assembly to regulate activity. Catechol-terminated poly(vinyl alcohol) was synthesised by RAFT polymerization. Upon addition of Fe3+, larger supramolecular star polymers form by assembly with two or three catechols. This increase in molecular weight effectively ‘switches on’ the IRI activity and is the first example of external control over the function of AFP mimetics. This provides a simple but elegant solution to the challenge of external control of AFP-mimetic function. PMID:28003855

Development and Characterization of Poly(1-vinylpyrrolidone-co-vinyl acetate) Copolymer Based Polymer Electrolytes

PubMed Central

Sa'adun, Nurul Nadiah; Subramaniam, Ramesh; Kasi, Ramesh

2014-01-01

Gel polymer electrolytes (GPEs) are developed using poly(1-vinylpyrrolidone-co-vinyl acetate) [P(VP-co-VAc)] as the host polymer, lithium bis(trifluoromethane) sulfonimide [LiTFSI] as the lithium salt and ionic liquid, and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide [EMImTFSI] by using solution casting technique. The effect of ionic liquid on ionic conductivity is studied and the optimum ionic conductivity at room temperature is found to be 2.14 × 10−6 S cm−1 for sample containing 25 wt% of EMImTFSI. The temperature dependence of ionic conductivity from 303 K to 353 K exhibits Arrhenius plot behaviour. The thermal stability of the polymer electrolyte system is studied by using thermogravimetric analysis (TGA) while the structural and morphological properties of the polymer electrolyte is studied by using Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction analysis (XRD), respectively. PMID:25431781

Preparation and characterization of poly(vinyl alcohol)/sodium alginate hydrogel with high toughness and electric conductivity.

PubMed

Jiang, Xiancai; Xiang, Nanping; Zhang, Hongxiang; Sun, Yujun; Lin, Zhen; Hou, Linxi

2018-04-15

Development of bio-based hydrogels with good mechanical properties and high electrical conductivity is of great importance for their excellent biocompatibility and biodegradability. Novel electrically conducive and tough poly(vinyl alcohol)/sodium alginate (PVA/SA) composite hydrogel was obtained by a simple method in this paper. PVA and SA were firstly dissolved in distilled water to form the composite solution and the pure PVA/SA hydrogel was obtained through the freezing/thawing process. The pure PVA/SA hydrogels were subsequently immersed into the saturated NaCl aqueous solution to increase the gel strength and conductivity. The effect of the immersing time on the thermal and mechanical properties of PVA/SA hydrogel was studied. The swelling properties and the antiseptic properties of the obtained PVA/SA hydrogel were also studied. This paper provided a novel way for the preparation of tough hydrogel electrolyte. Copyright © 2018. Published by Elsevier Ltd.

Study on the performance of eosin-doped poly(vinyl alcohol)/acrylamide photopolymer films for holographic recording using 488-nm wavelength

NASA Astrophysics Data System (ADS)

Rajesh, Chelakkal Sukumaran; Sreeroop, Sasidharan Savithrydevi; Pramitha, Vayalamkuzhi; Joseph, Rani; Sreekumar, Krishnapillai; Kartha, Cheranellore Sudha

2011-12-01

This article reports a study done on eosin-doped poly(vinyl alcohol)/acrylamide films for holographic recording using 488 nm Ar+ laser. Films were fabricated using gravity settling method at room temperature and were stored under normal laboratory conditions. Ar+ laser (488 nm) was used for fringe recording. Characterization was done by real time transmittance measurement, optical absorption studies, and diffraction efficiency measurements. Various holographic parameters such as exposure energy, recording power, spatial frequency, etc., were optimized so as to ensure maximum performance. More than 85% diffraction efficiency was obtained at an exposure energy of 50 mJ/cm2 in the optimized film. Efforts were taken to study the environmental stability of this self-developing polymeric material by looking at its shelf life and storage life. Compatibility for recording transmission hologram was also checked.

Poly(N-vinyl-2-pyrrolidone)-stabilized palladium-platinum nanoparticles-catalyzed hydrolysis of ammonia borane for hydrogen generation

NASA Astrophysics Data System (ADS)

Rakap, Murat

2015-02-01

The catalytic use of highly efficient poly(N-vinyl-2-pyrrolidone)-stabilized palladium-platinum nanoparticles (4.2 ± 1.9 nm) in the hydrolysis of ammonia-borane is reported. The catalyst is prepared by co-reduction of two metal ions in ethanol/water mixture by an alcohol reduction method and characterized by transmission electron microscopy, X-ray photoelectron spectroscopy and UV-Vis spectroscopy. They are recyclable and highly active for hydrogen generation from the hydrolysis of ammonia-borane even at very low concentrations and temperature, providing a record numbers of average turnover frequency value (125 mol H2/mol cat.min-1) and maximum hydrogen generation rate (3468 L H2 min-1 (mol cat)-1). They also provide activation energy of 51.7 ± 2 kJ/mol for the hydrolysis of ammonia borane.

Mercaptoheterocyclic ligands grafted on a poly(ethylene vinyl alcohol) membrane for the purification of immunoglobulin G in a salt independent thiophilic chromatography.

PubMed

Coffinier, Yannick; Vijayalakshmi, Mookambeswaran A

2004-08-25

In this study, we attempted a limited combinatorial approach for designing affinity ligands based on mercaptoheterocyclic components. The template, divinyl sulfone structure (DVS), which was grafted on poly(ethylene vinyl alcohol) (PEVA) hollow fiber membrane, has served for the tethering of different heterocyclic compounds as pyridine, imidazole, purine and pyrimidine rings. Their ability to adsorb specifically IgG in a salt independent manner out of pure IgG solution, mixture of IgG/albumin and human plasma was demonstrated. Mercapto methyl imidazole (MMI) has shown the best adsorption of IgG in terms of binding capacity. No subclass discrimination was observed on all tested ligands except for mercapto methyl pyrimidine where the major IgG subclass adsorbed was IgG3. MMI gave an IgG binding capacity of 100 microg/cm2 of hollow fiber membrane surface area.

Poly (N-vinyl Carbazole) - Polypyrrole/graphene oxide nanocomposite material on tapered fiber for Q-switched pulse generation

NASA Astrophysics Data System (ADS)

Ahmad, H.; Faruki, M. J.; Jasim, A. A.; Ooi, S. I.; Thambiratnam, K.

2018-02-01

A passively Q-switched fiber laser using a Saturable Absorber (SA) fabricated from a new Poly (N-vinyl Carbazole) - Polypyrrole/Graphene Oxide (PNVC-PPy/GO) nanocomposite material deposited on a tapered fiber is proposed and demonstrated. The PNVC-PPy/GO composition is deposited along a 3 mm length of the 6.5 cm tapered fiber which has a tapered waist of 8 μm. Q-switched pulses are obtained with repetition rates of 25.15-42.7 kHz and pulse widths of 5.74-2.48 μs over a pump power range of 12.8-40.0 mW. A maximum average power of 0.19 mW and pulse energy of 4.43 nJ are also observed. The proposed Q-switched maintains advantages of a simple design and low fabrication cost while at the same time generating high quality Q-switched pulses.

Identification of diffusive transport properties of poly(vinyl alcohol) hydrogels from reservoir test.

PubMed

Kazimierska-Drobny, Katarzyna; Kaczmarek, Mariusz

2013-12-01

In this paper the identification of diffusion coefficient, retardation factor and surface distribution coefficient for selected salts in poly(vinyl alcohol) hydrogels is performed. The identification of the transport parameters is based on the previously developed inverse problem technique using experimental data from the reservoir test and the solution of the diffusive transport equation with linear equilibrium sorption. The estimated values of diffusion coefficient are: for physiological fluid (6.30±0.10)×10(-10) m(2)/s, for 1 M NaCl (6.42±0.39)×10(-10) m(2)/s, and for 1 M KCl (7.94±0.38)×10(-10) m(2)/s. The retardation factor for all tested materials and salts is equal or close to one. The average value of the effective surface distribution coefficient is equal to 0.5. © 2013 Elsevier B.V. All rights reserved.

Polyurethane/poly(vinyl alcohol) hydrogel coating improves the cytocompatibility of neural electrodes

PubMed Central

Li, Mei; Zhou, Hai-han; Li, Tao; Li, Cheng-yan; Xia, Zhong-yuan; Duan, Yanwen Y.

2015-01-01

Neural electrodes, the core component of neural prostheses, are usually encapsulated in polydimethylsiloxane (PDMS). However, PDMS can generate a tissue response after implantation. Based on the physicochemical properties and excellent biocompatibility of polyurethane (PU) and poly(vinyl alcohol) (PVA) when used as coating materials, we synthesized PU/PVA hydrogel coatings and coated the surface of PDMS using plasma treatment, and the cytocompatibility to rat pheochromocytoma (PC12) cells was assessed. Protein adsorption tests indicated that the amount of protein adsorption onto the PDMS substrate was reduced by 92% after coating with the hydrogel. Moreover, the PC12 cells on the PU/PVA-coated PDMS showed higher cell density and longer and more numerous neurites than those on the uncoated PDMS. These results indicate that the PU/PVA hydrogel is cytocompatible and a promising coating material for neural electrodes to improve their biocompatibility. PMID:26889197

Anti-cancer, pharmacokinetics and tumor localization studies of pH-, RF- and thermo-responsive nanoparticles.

PubMed

Sanoj Rejinold, N; Thomas, Reju George; Muthiah, Muthunarayanan; Chennazhi, K P; Manzoor, K; Park, In-Kyu; Jeong, Yong Yeon; Jayakumar, R

2015-03-01

The curcumin-encapsulated chitosan-graft-poly(N-vinyl caprolactam) nanoparticles containing gold nanoparticles (Au-CRC-TRC-NPs) were developed by ionic cross-linking method. After "optimum RF exposure" at 40 W for 5 min, Au-CRC-TRC-NPs dissipated heat energy in the range of ∼42°C, the lower critical solution temperature (LCST) of chitosan-graft-poly(N-vinyl caprolactam), causing controlled curcumin release and apoptosis to cancer cells. Further, in vivo PK/PD studies on swiss albino mice revealed that Au-CRC-TRC-NPs could be sustained in circulation for a week with no harm to internal organs. The colon tumor localization studies revealed that Au-CRC-TRC-NPs were retained in tumor for a week. These results throw light on their feasibility as multi-responsive nanomedicine for RF-assisted cancer treatment modalities. Copyright © 2014 Elsevier B.V. All rights reserved.

Preparation and characterization of antibacterial electrospun chitosan/poly (vinyl alcohol)/graphene oxide composite nanofibrous membrane

NASA Astrophysics Data System (ADS)

Yang, Shuai; Lei, Peng; Shan, Yujuan; Zhang, Dawei

2018-03-01

In this paper, chitosan (CS)/poly (vinyl alcohol) (PVA)/graphene oxide (GO) composite nanofibrous membranes were prepared via electrospinning. Such nanofibrous membranes have been characterized and investigated for their morphological, structural, thermal stability, hydrophilic and antibacterial properties. SEM images showed that the uniform and defect-free nanofibers were obtained and GO sheets, shaping spindle and spherical, were partially embedded into nanofibers. FTIR, XRD, DSC and TGA indicated the good compatibility between CS and PVA. There were strong intermolecular hydrogen bonds between the chitosan and PVA molecules. Contact angle measurement indicated that while increasing the content of GO, the distance between fibers increased and water drop showed wetting state on the surface of nanofibrous membranes. As a result, the contact angle decreased significantly. Meanwhile, good antibacterial activity of the prepared nanofibrous membranes were exhibited against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus.

The Effect of Salt on the Complex Coacervation of Vinyl Polyelectrolytes

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

Perry, Sarah; Li, Yue; Priftis, Dimitrios

2014-06-01

Complex coacervation is an electrostatically-driven phase separation phenomenon that is utilized in a wide range of everyday applications and is of great interest for the creation of self-assembled materials. Here, we utilized turbidity to characterize the effect of salt type on coacervate formation using two vinyl polyelectrolytes, poly(acrylic acid sodium salt) (pAA) and poly(allylamine hydrochloride) (pAH), as simple models for industrial and biological coacervates. We confirmed the dominant role of salt valence on the extent of coacervate formation, while demonstrating the presence of significant secondary effects, which can be described by Hofmeister-like behavior. These results revealed the importance of ion-specificmore » interactions, which are crucial for the informed design of coacervate-based materials for use in complex ionic environments, and can enable more detailed theoretical investigations on the role of subtle electrostatic and thermodynamic effects in complex coacervation.« less

Microfluidic solvent extraction of poly(vinyl alcohol) droplets: effect of polymer structure on particle and capsule formation.

PubMed

Sharratt, W N; Brooker, A; Robles, E S J; Cabral, J T

2018-04-26

We investigate the formation of poly(vinyl alcohol) microparticles by the selective extraction of aqueous polymer solution droplets, templated by microfluidics and subsequently immersed in a non-solvent bath. The role of polymer molecular mass (18-105 kg mol-1), degree of hydrolysis (88-99%) and thus solubility, and initial solution concentration (0.01-10% w/w) are quantified. Monodisperse droplets with radii ranging from 50 to 500 μm were produced at a flow-focusing junction with carrier phase hexadecane and extracted into ethyl acetate. Solvent exchange and extraction result in droplet shrinkage, demixing, coarsening and phase-inversion, yielding polymer microparticles with well-defined dimensions and internal microstructure. Polymer concentration, varied from below the overlap concentration c* to above the concentrated crossover c**, as estimated by viscosity measurements, was found to have the largest impact on the final particle size and extraction timescale, while polymer mass and hydrolysis played a secondary role. These results are consistent with the observation that the average polymer concentration upon solidification greatly exceeds c**, and that the internal microparticle porosity is largely unchanged. However, reducing the initial polymer concentration to well below c* (approximately 100×) and increasing droplet size yields thin-walled (100's of nm) capsules which controllably crumple upon extraction. The symmetry of the process can be readily broken by imposing extraction conditions at an impermeable surface, yielding large, buckled, cavity morphologies. Based on these results, we establish robust design criteria for polymer capsules and particles, demonstrated here for poly(vinyl alcohol), with well-defined shape, dimensions and internal microstructure.

High efficiency preparation and characterization of intact poly(vinyl alcohol) dehydrogenase from Sphingopyxis sp.113P3 in Escherichia coli by inclusion bodies renaturation.

PubMed

Jia, Dongxu; Yang, Yu; Peng, Zhengcong; Zhang, Dongxu; Li, Jianghua; Liu, Long; Du, Guocheng; Chen, Jian

2014-03-01

Poly(vinyl alcohol) dehydrogenase (PVADH, EC 1.1.99.23) is an enzyme which has potential application in textile industry to degrade the poly(vinyl alcohol) (PVA) in waste water. Previously, a 1,965-bp fragment encoding a PVADH from Sphingopyxis sp. 113P3 was synthesized based on the replacement of the rare codons in Escherichia coli (E. coli). In this work, the deduced mature PVADH (mPVADH) gene of 1,887 bp was amplified by polymerase chain reaction (PCR) and inserted into the site between NcoI and HindIII in pET-32a(+). The constructed recombinant plasmid was transformed into E. coli Rosetta (DE3). In shake flask, the fusion protein of thioredoxin (Trx)-mPVADH was expressed precisely; however, Trx-mPVADH was found to accumulate mainly as inclusion bodies. After isolating, dissolving in buffer containing urea, purification, dialysis renaturation, and digesting with recombinant enterokinase/His (rEK/His), the bioactive mPVADH fragments were obtained with protein concentration of 0.56 g/L and enzymatic activity of 194 U/mL. The K m and V max values for PVA 1799 were 2.33 mg/mL and 15.7 nmol/(min·mg protein), respectively. (1)H-NMR and infrared (IR) spectrum demonstrated that its biological function was oxidizing hydroxyl groups of PVA 1799 to form diketone, and PVA 1799 could be degraded completely by successive treatment with mPVADH and oxidized PVA hydrolase (OPH).

Measurements of Dynamic Viscoelasticity of Poly (vinyl alcohol) Hydrogel for the Development of Blood Vessel Biomodeling

NASA Astrophysics Data System (ADS)

Kosukegawa, Hiroyuki; Mamada, Keisuke; Kuroki, Kanju; Liu, Lei; Inoue, Kosuke; Hayase, Toshiyuki; Ohta, Makoto

In vitro blood vessel biomodeling with realistic mechanical properties and geometrical structures is helpful for training in surgical procedures, especial those used in endovascular treatment. Poly (vinyl alcohol) hydrogel (PVA-H), which is made of Poly (vinyl alcohol) (PVA) and water, may be useful as a material for blood vessel biomodeling due to its low surface friction resistance and good transparency. In order to simulate the mechanical properties of blood vessels, measurements of mechanical properties of PVA-H were carried out with a dynamic mechanical analyzer, and the storage modulus (G’) and loss modulus (G”) of PVA-H were obtained. PVA-Hs were prepared by the low-temperature crystallization method. They were made of PVA with various concentrations (C) and degrees of polymerization (DP), and made by blending two kinds of PVA having different DP or saponification values (SV). The G’ and G” of PVA-H increased, as the C or DP of PVA increased, or as the proportion of PVA with higher DP or SV increased. These results indicate that it is possible to obtain PVA-H with desirable dynamic viscoelasticity. Furthermore, it is suggested that PVA-H is stable in the temperature range of 0°C to 40°C, indicating that biomodeling made of PVA-H should be available at 37°C, the physiological temperature. The dynamic viscoelasticity of PVA-H obtained was similar to that of the dog blood vessel measured in previous reports. In conclusion, PVA-H is suggested to be useful as a material of blood vessel biomodeling.

Preparation of end-grafted polymer brushes by nitroxide-mediated free radical polymerization of vaporized vinyl monomers.

PubMed

Li, Jun; Chen, Xiaoru; Chang, Ying-Chih

2005-10-11

In this work, we report a gas-phase polymerization approach to create end-grafted vinyl based polymer films on silicon oxide based substrates. The "surface-initiated vapor deposition polymerization" (SI-VDP) of vaporized vinyl monomers, via the nitroxide-mediated free radical polymerization mechanism, was developed to fabricate various homo- and block copolymer brushes from surface-bound initiators, 1-(4'-oxa-2'-phenyl-12'-trimethoxysilyldodecyloxy)-2,2,6,6-tetra-methylpiperidine ("TEMPO"). The resulting polymer thin films were characterized by the Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, ellipsometry, and contact angle goniometry, respectively, to identify the surface composition, film thickness, surface coverage, and water contact angles. Through the SI-VDP, end-grafted polymer films of polystyrene (PSt), poly(acrylic acid) (PAAc), poly(N-(2-hydroxypropyl) methacrylamide) (PHPMA), and poly(N-isopropylacrylamide) (PNIPAAm) with 10-200 nm thicknesses were fabricated. Furthermore, the block copolymer films of PAAc (1st block)-b-PSt (2nd block), PSt (1st block)-b-PAAc (2nd block), and a triblock copolymer film of PAAc (1st)-b-PSt (2nd)-b-PHPMA (3rd), were also fabricated, suggesting the "renewability" of the TEMPO-initiated polymerization in the SI-VDP scheme. It is also noticed that the SI-VDP is more efficient than the conventional solution phase polymerization in producing functional polymer brushes such as PNIPAAm, PAAc, or PAAc-b-PSt end-grafted films. In summary, our studies have shown clear advantages of the SI-VDP setup for the nitroxide-mediated polymerization scheme in controlling synthesis of end-grafted homo- and copolymer thin films.

Antibacterial and wound healing properties of chitosan/poly(vinyl alcohol)/zinc oxide beads (CS/PVA/ZnO).

PubMed

Gutha, Yuvaraja; Pathak, Janak L; Zhang, Weijiang; Zhang, Yaping; Jiao, Xu

2017-10-01

Treatment against bacterial infection is crucial for wound healing. Development of cost-effective antibacterial agent with wound healing properties is still in high demand. In this study we aimed to design chitosan/poly(vinyl alcohol)/zinc oxide (CS/PVA/ZnO) beads as novel antibacterial agent with wound healing properties. CS/PVA/ZnO beads were synthesized, and characterized by using XRD, FTIR, SEM, and TEM analysis. Pure chitosan exhibits two peaks at 2θ=10 and 20 and the CS/PVA polymer matrix exhibit the peaks at 2θ=19.7° and another of low intensity at 2θ=11.5°. Pure ZnO shows the characteristic peaks at (100), (002), (101), (102), (110), (103), (200), and (112) that were in good agreement with wurtzite ore having hexagonal lattice structure. The antibacterial activity of CS/PVA/ZnO against Escherichia coli, and Staphylococcus aureus were evaluated with the zone of inhibition method. Antibacterial activity of CS/PVA/ZnO was higher than that of chitosan (CS) and poly(vinyl alcohol (PVA). Hemocompatibility and biocompatibility of CS/PVA/ZnO were tested in in vitro. Wound healing properties of CS/PVA/ZnO were tested in mice skin wound. CS/PVA/ZnO showed strong antimicrobial, wound healing effect, hemocompatibility and biocompatibility. Hence the results strongly support the possibility of using this novel CS/PVA/ZnO material for the anti bacterial and wound healing application. Copyright © 2017 Elsevier B.V. All rights reserved.

Release of tetracycline hydrochloride from electrospun poly(ethylene-co-vinylacetate), poly(lactic acid), and a blend.

PubMed

Kenawy, El-Refaie; Bowlin, Gary L; Mansfield, Kevin; Layman, John; Simpson, David G; Sanders, Elliot H; Wnek, Gary E

2002-05-17

Electrospun fiber mats are explored as drug delivery vehicles using tetracycline hydrochloride as a model drug. The mats were made either from poly(lactic acid) (PLA), poly(ethylene-co-vinyl acetate) (PEVA), or from a 50:50 blend of the two. The fibers were electrospun from chloroform solutions containing a small amount of methanol to solubilize the drug. The release of the tetracycline hydrochloride from these new drug delivery systems was followed by UV-VIS spectroscopy. Release profiles from the electrospun mats were compared to a commercially available drug delivery system, Actisite (Alza Corporation, Palo Alto, CA), as well as to cast films of the various formulations.

Formation, Structure and Properties of Boron Nitride Fibers from Polymer Precursors

DTIC Science & Technology

1992-02-25

conversion, have been demonstrated in this study. Poly(ethylene oxide) (PEO), poly(N-vinyl-2-pyrrolidinone) ( PVP ), and poly(methyl methacrylate) (PMMA) were...vinylpyrrolidinone ( PVP , Mw = 360,000). A 100 ml reaction flask with teflon boiling chips and a 100 ml receiving flask were used on a high boiling distilling...CH 3 OBO) 3 : B(OH)3 Predicted 2 Experiment Experiment, 1 wt% PVP 2:1 47.8 mole% CH 3 OH 39.6 mole% CH 3OH 35.2 mole% CH3 OH 3:1 47.8 - 35.5 4:1 47.8

Synthesis and characterization of poly-3-((2,5-hydroquinone)vinyl)-1H-pyrrole: investigation on backbone/pendant interactions in a conducting redox polymer.

PubMed

Huang, Hao; Karlsson, Christoffer; Strømme, Maria; Gogoll, Adolf; Sjödin, Martin

2017-04-19

We herein report the synthesis and electrochemical characterization of poly-3-((2,5-hydroquinone)vinyl)-1H-pyrrole, consisting of a polypyrrole backbone derivatized at the beta position by a vinyl-hydroquinone pendant group. The structure of the polymer was characterized by solid state NMR spectroscopy. The interactions between the polypyrrole backbone and the oxidized quinone or reduced hydroquinone pendant groups are probed by several in situ methods. In situ attenuated total reflectance-Fourier transform infrared spectroscopy shows a spectroscopic response from both the doping of the polymer backbone and the redox activity of the pendant groups. Using an in situ Electrochemical Quartz Crystal Microbalance we reveal that the polymer doping is unaffected by the pendant group redox chemistry, as opposed to previous reports. Despite the continuous doping the electrochemical conversion from the hydroquinone state to the quinone state results in a significant conductance drop, as observed by in situ conductivity measurements using an Interdigitated Array electrode set-up. Twisting of the conducting polymer backbone as a result of a decreased separation between pendant groups due to π-π stacking in the oxidized state is suggested as the cause of this conductance drop.

Directed self-assembly of high-chi block copolymer for nano fabrication of bit patterned media via solvent annealing

NASA Astrophysics Data System (ADS)

Xiong, Shisheng; Chapuis, Yves-Andre; Wan, Lei; Gao, He; Li, Xiao; Ruiz, Ricardo; Nealey, Paul F.

2016-10-01

We report the formation of nanoimprint master templates that can be used for the fabrication of bit patterned media (BPM). The template was formed by directed self-assembly, with solvent annealing, of a symmetric ABA triblock copolymer to form perpendicularly oriented lamellae on chemical patterns. We used a high-χ block copolymer, poly(2-vinyl pyridine)-block-polystyrene-block-poly(2-vinyl pyridine) to achieve smaller feature sizes than are possible with polystyrene-block-poly(methyl methacrylate). The work shows that triblock copolymers can provide a large processing window in terms of pitch commensurability. Using block-selective infiltration (atomic layer deposition with sequential long soaking/purge cycles), an alumina composite with high etch resistance was specifically incorporated into the polar and hydrophilic P2VP domains. Subsequently, the surface pattern was successfully transferred into underlying Si substrates by etching with a fluorine-containing plasma to create a nanoimprint master. The line/space pattern of the nanoimprint master met the BPM fabrication requirement of defectivity <10-3. For demonstration purposes, the nanoimprint master was used to imprint a replica pattern of photoresist on a quartz wafer.

The development of an energy-independent personnel neutron dosimeter using CR-39

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

Doremus, S.W.

The addition of specialized (n,{alpha}) radiators to a standard polyethylene/CR-39 (PE/CR-39) neutron dosimetry system was evaluated for improved response to low energy neutrons. Specialized radiators consisting of poly(vinyl alcohol) complexed with boron (natural and enriched boron-10) and poly(acrylic acid) complexed with lithium (enriched lithium-6) were evaluated. The complexion of boron with poly(vinyl alcohol) was accomplished by incorporation or surface coating. The complexion of lithium with poly(acrylic acid) was exclusively performed by incorporation. The dosimeter was designed such that the specialized radiator was in contact with the CR-39 detector (i.e., the specialized radiator was sandwiched between the CR-39 detector and polyethylenemore » radiator). The neutron response of this dosimetry system was investigated using {sup 252}Cf (moderated and bare) spontaneous fission neutrons. Detectors were chemically etched and then read with a Nikon OPTIPHOT microscope. The mean response (tracks {center dot} field{sup {minus}1}) of detectors treated with specialized (n,{alpha}) radiators were evaluated against PE/CR-39 controls. The results of this investigation demonstrate that PE/CR-39 dosimeters equipped with specialized (n,{alpha}) radiators have a noticeable response to low energy neutrons that in many instances is significantly greater than that of the controls. The addition of specialized radiators to this dosimetry system did not effect (diminish) its response to fast neutrons.« less

Preparation, characterization, and application of poly(vinyl alcohol)-graft-poly(ethylene glycol) resins: novel polymer matrices for solid-phase synthesis.

PubMed

Luo, Juntao; Pardin, Christophe; Zhu, X X; Lubell, William D

2007-01-01

Spherical crosslinked poly(vinyl alcohol) (PVA) beads with good mechanical stability were prepared by reverse-suspension polymerization, using dimethyl sulfoxide (DMSO) as a cosolvent in an aqueous phase. Poly(ethylene glycol)s with varying chain lengths were grafted onto the PVA beads by anionic polymerization of ethylene oxide. The thermal behavior, morphology, and swelling were evaluated for each of the new polymer matrices. High loading and good swelling in water and organic solvents were characteristic of the PEG-grafted PVA beads. The polymer beads also exhibited good mechanical and chemical stability and were unaffected by treatment with 6 N HCl and with 6 N NaOH. The hydroxyl groups of the PVA-PEG beads were converted into aldehyde, carboxylic acid, and isocyanate functions to provide scavenger resins and were extended by way of a benzyl alcohol in a Wang linker. The transglutaminase substrates dipeptides (Z-Gln-Gly) and heptapeptides (Pro-Asn-Pro-Gln-Leu-Pro-Phe) were synthesized on PVA-PEG_5, PVA-PEG_20, and the Wang linker-derivatized PVA-PEG resins. The cleavage of the peptides from the resins using MeOH/NH3 mixture at different temperatures (0 degrees C and room temp) and 50% TFA/DCM provided, respectively, peptide methyl esters, amides, and acids in good yields and purity as assessed by LC-MS analysis.

Synthesis of light-selective poly(ethylene-co-vinyl acetate) nanofilms in supercritical carbon dioxide

NASA Astrophysics Data System (ADS)

Xu, William (Zhiming)

Due to the increased requirements of environmental protection, significant effort has been made to develop new "green" chemistry and engineering methods. Two effective approaches for "green" processes are: (1) to employ routes with fewer synthetic and separation steps, and (2) to replace volatile organic solvents with environmentally friendly solvents. Supercritical carbon dioxide (scCO2) has emerged as such a viable "green" alternative to organic solvents for several applications including extraction, polymerization, and nanotechnology, etc. In addition, it is an enabling solvent, allowing new types of chemistry and materials to be formed. In order to effectively utilize scCO2, it is required to study its effect on the relevant chemical process. This thesis focuses on the copolymerization of ethylene and vinyl acetate in scCO2, and the application of scCO2 in the synthesis of novel poly(vinyl acetate) (PVAc) and poly(ethylene-co-vinyl acetate) (PEVA) nanocomposites. Firstly, the kinetics of the process was investigated. The thermal decomposition of the free-radical initiator diethyl peroxydicarbonate (DEPDC) was monitored by in situ attenuate total reflection Fourier transform infrared spectroscopy (ATR-FTIR) in heptane, and in scCO2. The rate constant and activation energy of the thermal decomposition of DEPDC in scCO2 were determined, and a decomposition mechanism was proposed. Further, with a knowledge of the initiator kinetics, in situ ATR-FTIR was employed to monitor the initial formation of copolymers of ethylene and vinyl acetate during polymerization in scCO2. The reactivity ratios for the copolymerization of ethylene and vinyl acetate in scCO2 were determined using both the Kelen-Tudos and the non-linear least-squares methods. The potential of scCO2 was further examined to synthesize advanced and novel nanomaterials based on an understanding of the polymerization mechanism. A novel one-step synthesis route was developed for making silica-PVAc nanocomposites in scCO2, where the parallel reactions of free radical polymerization, hydrolysis/condensation, and linkage of the nanoparticles to the polymer chains, were found to take place simultaneously. This provides a new process featuring significant energy-saving, waste-reduction, and excellent distribution of nanoparticles in the polymer matrix. In addition, the incorporation of quantum dots (QDs) into a transparent polymer matrix was investigated to form light-selective nanofilms. Both CdS and CdS-ZnS core-shell QDs were synthesized, then functionalized with a methoxysilane group, and finally used to synthesize novel QD-PVAc and QD-PEVA nanocomposites in scCO2. The synthesized QD-PEVA nanofilms displayed significant absorption in the ultraviolet and violet regions of the electromagnetic spectrum, while providing a characteristic emission in the region from orange to red light. These materials have significant potential in green houses, and solar absorber films. Key words. supercritical CO2, initiator, thermal decomposition, kinetics, mechanism, ATR-FTIR, reactivity ratios, ethylene, vinyl acetate, silica, nanocomposite, one-pot synthesis, light-selective, nanofilm, quantum dots.

21 CFR 177.1635 - Poly(p-methylstyrene) and rubber-modified poly(p-methyl-styrene).

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Poly(p-methylstyrene) and rubber-modified poly(p... Poly(p-methylstyrene) and rubber-modified poly(p-methyl-styrene). Poly(p-methylstyrene) and rubber-modified poly(p-methylstyrene) identified in this section may be safely used as components of articles...

21 CFR 177.1635 - Poly(p-methylstyrene) and rubber-modified poly(p-methyl-styrene).

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Poly(p-methylstyrene) and rubber-modified poly(p... Components of Single and Repeated Use Food Contact Surfaces § 177.1635 Poly(p-methylstyrene) and rubber-modified poly(p-methyl-styrene). Poly(p-methylstyrene) and rubber-modified poly(p-methylstyrene) identified...

21 CFR 177.1635 - Poly(p-methylstyrene) and rubber-modified poly(p-methyl-styrene).

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Poly(p-methylstyrene) and rubber-modified poly(p... Poly(p-methylstyrene) and rubber-modified poly(p-methyl-styrene). Poly(p-methylstyrene) and rubber-modified poly(p-methylstyrene) identified in this section may be safely used as components of articles...

Poly[(ethylene oxide)-co-(methylene ethylene oxide)]: A hydrolytically-degradable poly(ethylene oxide) platform.

PubMed

Lundberg, Pontus; Lee, Bongjae F; van den Berg, Sebastiaan A; Pressly, Eric D; Lee, Annabelle; Hawker, Craig J; Lynd, Nathaniel A

2012-11-20

A facile method for imparting hydrolytic degradability to poly(ethylene oxide) (PEO), compatible with current PEGylation strategies, is presented. By incorporating methylene ethylene oxide (MEO) units into the parent PEO backbone, complete degradation was defined by the molar incorporation of MEO, and the structure of the degradation byproducts was consistent with an acid-catalyzed vinyl-ether hydrolysis mechanism. The hydrolytic degradation of poly[(ethylene oxide)-co-(methylene ethylene oxide)] was pH-sensitive, with degradation at pH 5 being significantly faster than at pH 7.4 at 37 °C in PBS buffer while long-term stability could be obtained in either the solid-state or at pH 7.4 at 6 °C.

Facile high-yield synthesis of polyaniline nanosticks with intrinsic stability and electrical conductivity.

PubMed

Li, Xin-Gui; Li, Ang; Huang, Mei-Rong

2008-01-01

Chemical oxidative polymerization at 15 degrees C was used for the simple and productive synthesis of polyaniline (PAN) nanosticks. The effect of polymerization media on the yield, size, stability, and electrical conductivity of the PAN nanosticks was studied by changing the concentration and nature of the acid medium and oxidant and by introducing organic solvent. Molecular and supramolecular structure, size, and size distribution of the PAN nanosticks were characterized by UV/Vis and IR spectroscopy, X-ray diffraction, laser particle-size analysis, and transmission electron microscopy. Introduction of organic solvent is advantageous for enhancing the yield of PAN nanosticks but disadvantageous for formation of PAN nanosticks with small size and high conductivity. The concentration and nature of the acid medium have a major influence on the polymerization yield and conductivity of the nanosized PAN. The average diameter and length of PAN nanosticks produced with 2 M HNO(3) and 0.5 M H(2)SO(4) as acid media are about 40 and 300 nm, respectively. The PAN nanosticks obtained in an optimal medium (i.e., 2 M HNO(3)) exhibit the highest conductivity of 2.23 S cm(-1) and the highest yield of 80.7 %. A mechanism of formation of nanosticks instead of nanoparticles is proposed. Nanocomposite films of the PAN nanosticks with poly(vinyl alcohol) show a low percolation threshold of 0.2 wt %, at which the film retains almost the same transparency and strength as pure poly(vinyl alcohol) but 262 000 times the conductivity of pure poly(vinyl alcohol) film. The present synthesis of PAN nanosticks requires no external stabilizer and provides a facile and direct route for fabrication of PAN nanosticks with high yield, controllable size, intrinsic self-stability, strong redispersibility, high purity, and optimizable conductivity.

Preparation of Poly(Dinitropropyl Vinyl Ether) with Crosslinking Sites, for Use as a Castable Binder

DTIC Science & Technology

1978-12-01

acetic acid . 4 Baum, K., Fluorochem, Inc., and Adolph, H., this Center, unpublished results. 11 NSWC/WOL TR 78-120 AFATL TR-78-86 In Table 1 are...for successful hydroxymethyla- tion (Figure 6): The peak for the acidic proton in Figure 5 at 6 4.85 is absent in Figure 6, and the doublet E in Figure...Poly-DNPVE, the work was terminated in favor of screening other cationic initiators. Initiation of DNPVE polymerization with epoxide/Lewis acid

Modulation of polymer refractive indices with diamond nanoparticles for metal-free multilayer film mirrors.

PubMed

Ogata, Tomonari; Yagi, Ryohei; Nakamura, Nozomi; Kuwahara, Yutaka; Kurihara, Seiji

2012-08-01

Modulation of the refractive index of a polymer was achieved by combining it with diamond nanoparticles (NDs). The increase in the refractive index was controlled by the amount of NDs added, according to the Lorentz-Lorenz equation. The refractive index of poly(vinyl alcohol) (PVA), which was used as the base polymer, increased from 1.52 to 1.88. A multilayer film consisting of alternating layers of ND-PVA composite and poly(methyl methacrylate) exhibited ca. 80% reflectance with 10 bilayers.

Versatility of Alkyne-Modified Poly(Glycidyl Methacrylate) Layers for Click Reactions

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

Soto-Cantu, Dr. Erick; Lokitz, Bradley S; Hinestrosa Salazar, Juan Pablo

2011-01-01

Functional soft interfaces are of interest for a variety of technologies. We describe three methods for preparing substrates with alkyne groups, which show versatility for 'click' chemistry reactions. Two of the methods have the same root: formation of thin, covalently attached, reactive interfacial layers of poly(glycidyl methacrylate) (PGMA) via spin coating onto silicon wafers followed by reactive modification with either propargylamine or 5-hexynoic acid. The amine or the carboxylic acid moieties react with the epoxy groups of PGMA, creating interfacial polymer layers decorated with alkyne groups. The third method consists of using copolymers comprising glycidyl methacrylate and propargyl methacrylate (pGP).more » The pGP copolymers are spin coated and covalently attached on silicon wafers. For each method, we investigate the factors that control film thickness and content of alkyne groups using ellipsometry, and study the nanophase structure of the films using neutron reflectometry. Azide-terminated polymers of methacrylic acid and 2-vinyl-4,4-dimethylazlactone synthesized via reversible addition-fragmentation chain transfer polymerization were attached to the alkyne-modified substrates using 'click' chemistry, and grafting densities in the range of 0.007-0.95 chains nm{sup -2} were attained. The maximum density of alkyne groups attained by functionalization of PGMA with propargylamine or 5-hexynoic acid was approximately 2 alkynes nm{sup -3}. The alkyne content obtained by the three decorating approaches was sufficiently high that it was not the limiting factor for the click reaction of azide-capped polymers.« less

Effect of polymer surface modification on polymer-protein interaction via hydrophilic polymer grafting.

PubMed

Liu, S X; Kim, J-T; Kim, S

2008-04-01

Surface modification of flat sheet ultrafiltration membranes, polyethersulfone (PES), was investigated to improve the hydrophilicity of the membrane surface thereby reducing adsorption of the proteins onto the membrane. Grafting of hydrophilic polymers onto UV/ozone-treated PES was used to improve the hydrophilicity of the commercial PES membranes. Hydrophilic polymers, that is, poly(vinyl alcohol) (PVA), polyethylene glycol (PEG), and chitosan, were employed to graft onto PES membrane surfaces because of their excellent hydrophilic property. The surfaces of modified PES membranes were characterized by contact angle measurement, FTIR, and AFM. The FTIR spectra indicated that PES membranes were successfully modified by grafting of the hydrophilic polymers. The modified PES membranes showed 20% to 50% reduction in contact angle measurements in comparison with those of the virgin PES membrane. The tapping mode AFM technique was employed to investigate the changes of surface topography, cross-section, and root mean square roughness of the modified PES membrane surfaces. The modified PES membranes showed elevated roughness (ranging from 7.0 to 25.7 nm) compared with that of the virgin PES membrane (2.1 nm). It is concluded that grafting of PVA, PEG, or chitosan onto UV/ozone-treated PES membranes increases hydrophilicity and lowers protein adsorption by 20% to 60% compared to the virgin PES membrane. Among the 3 hydrophilic polymers studied, PEG showed the most favorable result in terms of contact angle and protein adsorption.

Surface modification of medical implant materials with hydrophilic polymers for enhanced biocompatibility and delivery of therapeutic agents

NASA Astrophysics Data System (ADS)

Urbaniak, Daniel J.

2004-11-01

In the research reported here, the surface modification of medical grade poly(dimethyl siloxane), polyetherurethane, and stainless steel through gamma-radiation grafting of hydrophilic polymers was investigated. Emphasis was placed on developing improved and simplified surface modification methods that produce more stable and more bioacceptible hydrophilic graft surfaces. As a result of this research, new surface modification techniques were developed that yield significantly improved surface stability unachievable using previous surface modification techniques. The surface modification of poly(dimethyl siloxane) with hydrophilic polymers was carried out using gamma radiation initiated graft polymerization. The addition of alkali metal hydroxides afforded a unique way to enhance the grafting of N-vinyl-2 pyrrolidone, dimethylacryamide, 2-methacryloyloxyethyl phosphoryl choline, N,N-dimethyl-N-(methacryloyloxyethyl)-N-(3-sulfopropyl)-ammonium-betaine, N,N-dimethyl-N-(methacrylamidopropyl)-N-(3-sulfopropyl)-ammonium-betaine, and copolymers thereof to silicones. Ethanolamine was found to further enhance the grafting of some hydrophilic polymers to silicone. The resulting hydrophilic surface grafts were resistant to hydrophobic surface rearrangement. This process overcomes previous problems inherent in silicone surface modification. The technique was also found to moderately enhance the grafting of hydrophilic monomers to polyetherurethane and to 316-L stainless steel. The surface modification of 316-L stainless steel was further enhanced by treating the substrates with a chromium III methacrylate bonding agent prior to irradiation. The coatings were evaluated for their potential use as depots for delivering therapeutic agents. The release of ofloxacin from surface-modified poly(dimethyl siloxane) and dexamethasone from surface-modified 316-L stainless steel was evaluated by in-vitro experiments. Therapeutic levels of drugs were released from surface-modified specimens via a burst effect. Improved surface characterization methods were another aspect of this research. New nanomechanical testing techniques were developed and used to evaluate the viscoelastic surface mechanical properties of low modulus surface-modified specimens. Dynamic nanoindentation characterization techniques were designed to measure the storage modulus and loss modulus of compliant viscoelastic substrate surfaces. The results of these experiments were compared with modulus data obtained by conventional dynamic mechanical spectroscopy. Nanoscratch testing methods were also developed that qualitatively compared the abrasion resistance of surface-modified substrates. (Abstract shortened by UMI.)

Quick don-doff electrode pastes

NASA Technical Reports Server (NTRS)

Mosier, B.

1969-01-01

Evaluation of electrode pastes for use in electrocardiographs and electroencephalographs found that the one having the desired don-doff properties had to be water soluble or a water dispersible base. Poly /methyl vinyl ether/maleic anhydride/ or starch gels of the gum drop variety are two such bases.

Novel Thermally Stable Poly (vinyl chloride) Composites for Sulfate Removal

EPA Science Inventory

BaCO₃ dispersed PVC composites were prepared through a polymer re-precipitation method. The composites were tested for sulfate removal using rapid small scale column test (RSSCT) and found to significantly reduce sulfate concentration. The method was extended to synthe...

PREPARATION OF POLY(VINYL ACETATE) LATEXES IN LIQUID AND SUPERCRITICAL CARBON DIOXIDE. (R826115)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

Effect of electron beam irradiation on the structural properties of poly(vinyl alcohol) formulations with triphenyl tetrazolium chloride dye (TTC)

NASA Astrophysics Data System (ADS)

Ali, Z. I.; Said, Hossam M.; Ali, H. E.

2006-01-01

Films of poly(vinyl alcohol) (PVA) composites with triphenyl tetrazolium chloride (TTC) dye were prepared and exposed to various radiation doses delivered by accelerated electrons. The results showed that at a low dose of 50 kGy, the colour difference (Δ E*) of PVA/TTC films was increased by ˜10 times of the initial value. However, the change in colour differences did not go systematically with increasing the TTC content, in which the composite with 1.5 wt% displayed higher value than that with 3.5 wt%. The differential scanning calorimetry (DSC) showed that the presence of the TTC dye caused a depression in the melting point ( Tm) and heat of fusion (Δ Hf) of the PVA bulk polymer. However, the thermogravimetric analysis (TGA) showed that the presence of the TTC dye improved the thermal stability of PVA. Also, the tensile strength at break of PVA/TTC composites was improved after electron beam irradiation.

Surface-coated fly ash reinforced biodegradable poly(vinyl alcohol) composite films: part 2-analysis and characterization

NASA Astrophysics Data System (ADS)

Nath, D. C. D.; Bandyopadhyay, S.; Campbell, J.; Yu, A.; Blackburn, D.; White, C.

2010-12-01

Composite films of poly(vinyl alcohol) (PVA) reinforced with 5, 10, 15, 20 and 25 wt.% surface-coated fly ash by surfactant, sodium lauryl sulphate (SLS-FA) along with 1 wt.% cross-linking agent, glutaraldehyde (GLA) were prepared by aqueous casting method. The tensile strengths of the composite films were increased proportionally with the addition of SLS-FA. The maximum 75% higher strength of the composite with 20 wt.% was achieved compared to that of neat PVA. The modulus of the composites was also increased proportionally with SLS-FA and the maximum 218% reached in composite with 20 wt.%, but the strain at break was decreased with addition of SLS-FA. Changes in FTIR spectra reflect the chemical and/or physical bonding in the ternary PVA, SLS-FA and GLA component systems. In the study of surface morphology, the connectivity was visualized in SEM images along with interstitial voids. The films with SLS-FA show 53% smoother surface calculated with AFM compared to unmodified FA composite films.

Quaternized poly(vinyl alcohol)/alumina composite polymer membranes for alkaline direct methanol fuel cells

NASA Astrophysics Data System (ADS)

Yang, Chun-Chen; Chiu, Shwu-Jer; Chien, Wen-Chen; Chiu, Sheng-Shin

The quaternized poly(vinyl alcohol)/alumina (designated as QPVA/Al 2O 3) nanocomposite polymer membrane was prepared by a solution casting method. The characteristic properties of the QPVA/Al 2O 3 nanocomposite polymer membranes were investigated using thermal gravimetric analysis (TGA), scanning electron microscopy (SEM), dynamic mechanical analysis (DMA), micro-Raman spectroscopy, and AC impedance method. Alkaline direct methanol fuel cell (ADMFC) comprised of the QPVA/Al 2O 3 nanocomposite polymer membrane were assembled and examined. Experimental results indicate that the DMFC employing a cheap non-perfluorinated (QPVA/Al 2O 3) nanocomposite polymer membrane shows excellent electrochemical performances. The peak power densities of the DMFC with 4 M KOH + 1 M CH 3OH, 2 M CH 3OH, and 4 M CH 3OH solutions are 28.33, 32.40, and 36.15 mW cm -2, respectively, at room temperature and in ambient air. The QPVA/Al 2O 3 nanocomposite polymer membranes constitute a viable candidate for applications on alkaline DMFC.

Electrochemical performance of an air-breathing direct methanol fuel cell using poly(vinyl alcohol)/hydroxyapatite composite polymer membrane

NASA Astrophysics Data System (ADS)

Yang, Chun-Chen; Chiu, Shwu-Jer; Lin, Che-Tseng

A novel composite polymer membrane based on poly(vinyl alcohol)/hydroxyapatite (PVA/HAP) was successfully prepared by a solution casting method. The characteristic properties of the PVA/HAP composite polymer membranes were examined by thermal gravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), micro-Raman spectroscopy and AC impedance method. An air-breathing DMFC, comprised of an air cathode electrode with MnO 2/BP2000 carbon inks on Ni-foam, an anode electrode with PtRu black on Ti-mesh, and the PVA/HAP composite polymer membrane, was assembled and studied. It was found that this alkaline DMFC showed an improved electrochemical performance at ambient temperature and pressure; the maximum peak power density of an air-breathing DMFC in 8 M KOH + 2 M CH 3OH solution is about 11.48 mW cm -2. From the application point of view, these composite polymer membranes show a high potential for the DMFC applications.

Nanofibrous nonmulberry silk/PVA scaffold for osteoinduction and osseointegration.

PubMed

Bhattacharjee, Promita; Kundu, Banani; Naskar, Deboki; Maiti, Tapas K; Bhattacharya, Debasis; Kundu, Subhas C

2015-05-01

Poly-vinyl alcohol and nonmulberry tasar silk fibroin of Antheraea mylitta are blended to fabricate nanofibrous scaffolds for bone regeneration. Nanofibrous matrices are prepared by electrospinning the equal volume ratio blends of silk fibroin (2 and 4 wt%) with poly-vinyl alcohol solution (10 wt%) and designated as 2SF/PVA and 4SF/PVA, respectively with average nanofiber diameters of 177 ± 13 nm (2SF/PVA) and 193 ± 17 nm (4SF/PVA). Fourier transform infrared spectroscopy confirms retention of the secondary structure of fibroin in blends indicating the structural stability of neo-matrix. Both thermal stability and contact angle of the blends decrease with increasing fibroin percentage. Conversely, fibroin imparts mechanical stability to the blends; greater tensile strength is observed with increasing fibroin concentration. Blended scaffolds are biodegradable and support well the neo-bone matrix synthesis by human osteoblast like cells. The findings indicate the potentiality of nanofibrous scaffolds of nonmulberry fibroin as bone scaffolding material. © 2014 Wiley Periodicals, Inc.

Ion-selective detection by plasticized poly(vinyl chloride) membrane in glass nanopipette with alternating voltage modulation.

PubMed

Deng, Xiao Long; Takami, Tomohide; Son, Jong Wan; Kang, Eun Ji; Kawai, Tomoji; Park, Bae Ho

2013-08-01

An alternating current (AC) voltage modulation was applied to ion-selective observations with plasticized poly(vinyl chloride) membranes in glass nanopipettes. The liquid confronting the membranes in the nanopipettes, the conditioning process, and AC voltage modulation play important roles in the ion-selective detection. In the AC detection system developed by us, where distilled water was used as the liquid within the nanopipettes, potassium ions were selectively detected in the sample solution of sodium and potassium ions because sodium ions were captured at the membrane containing bis(12-crown-4) ionophores, before the saturation of the ionophores. The membrane lost the selectivity after the saturation. On using sodium chloride as the liquid within the nanopipette, the membrane selectively detected potassium and sodium ions before and after the saturation of ionophores, respectively. The ion-selective detection of our system can be explained by the ion extraction-diffusion-dissolution mechanism through the bis(12-crown-4) ionophores with AC voltage modulation.

Therapeutic-Ultrasound-Triggered Shape Memory of a Melamine-Enhanced Poly(vinyl alcohol) Physical Hydrogel.

PubMed

Li, Guo; Yan, Qiang; Xia, Hesheng; Zhao, Yue

2015-06-10

Therapeutic-ultrasound-triggered shape memory was demonstrated for the first time with a melamine-enhanced poly(vinyl alcohol) (PVA) physical hydrogel. The addition of a small amount of melamine (up to 1.5 wt %) in PVA results in a strong hydrogel due to the multiple H-bonding between the two constituents. A temporary shape of the hydrogel can be obtained by deformation of the hydrogel (∼65 wt % water) at room temperature, followed by fixation of the deformation by freezing/thawing the hydrogel under strain, which induces crystallization of PVA. We show that the ultrasound delivered by a commercially available device designed for the patient's pain relief could trigger the shape recovery process as a result of ultrasound-induced local heating in the hydrogel that melts the crystallized PVA cross-linking. This hydrogel is thus interesting for potential applications because it combines many desirable properties, being mechanically strong, biocompatible, and self-healable and displaying the shape memory capability triggered by a physiological stimulus.

Tensile properties and water absorption assessment of linear low-Density Polyethylene/Poly (Vinyl Alcohol)/Kenaf composites: effect of eco-friendly coupling agent

NASA Astrophysics Data System (ADS)

Pang, A. L.; Ismail, H.; Abu Bakar, A.

2018-02-01

Linear low-density polyethylene (LLDPE)/poly (vinyl alcohol) (PVOH) filled with untreated kenaf (UT-KNF) and eco-friendly coupling agent (ECA)-treated kenaf (ECAT-KNF) were prepared using ThermoHaake internal mixer, respectively. Filler loadings of UT-KNF and ECAT-KNF used in this study are 10 and 40 parts per hundred parts of resin (phr). The effect of ECA on tensile properties and water absorption of LLDPE/PVOH/KNF composites were investigated. Field emission scanning electron microscopy (FESEM) analysis was applied to visualize filler-matrix adhesion. The results indicate LLDPE/PVOH/ECAT-KNF composites possess higher tensile strength and tensile modulus, but lower elongation at break compared to LLDPE/PVOH/UT-KNF composites. The morphological studies of tensile fractured surfaces using FESEM support the increment in tensile properties of LLDPE/PVOH/ECAT-KNF composites. Nevertheless, LLDPE/PVOH/UT-KNF composites reveal higher water absorption compared to LLDPE/PVOH/ECAT-KNF composites.

Starch nanoparticle as a vitamin E-TPGS carrier loaded in silk fibroin-poly(vinyl alcohol)-Aloe vera nanofibrous dressing.

PubMed

Kheradvar, Shadi Alsadat; Nourmohammadi, Jhamak; Tabesh, Hadi; Bagheri, Behnam

2018-06-01

Core-sheath nanofibrous mat as a new vitamin E (VE) delivery system based on silk fibroin (SF)/poly(vinyl alcohol) (PVA)/aloe vera (AV) was successfully prepared by the electrospinning method. Initially, VE-loaded starch nanoparticles were produced and then incorporated into the best beadless SF-PVA-AV nanofibers. The successful loading of VE in starch nanoparticles was proved by Fourier-transform infrared spectroscopy. The scanning electron microscopy and transmission electron microscopy indicated that spherical nanoparticles were successfully embedded within the nanofibers. In vitro release studies demonstrated that the release of VE was controlled by Fickian diffusion and was faster in samples containing more nanoparticles. Fibroblast attachment, proliferation, and collagen secretion were enhanced after adding AV and VE to the SF-PVA nanomatrix. Moreover, the incorporation of VE into the nanocomposite dressing enhanced antioxidant activity, which can have a positive effect on wound healing process by protecting the cells from toxic oxidation products. Copyright © 2018 Elsevier B.V. All rights reserved.

Effects of Molecular Weight upon Irradiation-Cross-Linked Poly(vinyl alcohol)/Clay Aerogel Properties.

PubMed

Chen, Hong-Bing; Zhao, Yan; Shen, Peng; Wang, Jun-Sheng; Huang, Wei; Schiraldi, David A

2015-09-16

Facile fabrication of mechanically strong poly(vinyl alcohol) (PVOH)/clay aerogel composites through a combination of increasing polymer molecular weights and gamma irradiation-cross-linking is reported herein. The aerogels produced from high polymer molecular weights exhibit significantly increased compressive moduli, similar to the effect of irradiation-induced cross-linking. The required irradiation dose for fabricating strong PVOH composite aerogels with dense microstructure decreased with increasing polymer molecular weight. Neither thermal stability nor flammability was significantly changed by altering the polymer molecular weight or by modest gamma irradiation, but they were highly dependent upon the polymer/clay ratio in the aerogel. Optimization of the mechanical, thermal, and flammability properties of these composite aerogels could therefore be obtained by using relatively low levels of polymer, with very high polymer molecular weight, or lower molecular weight coupled with moderate gamma irradiation. The facile preparation of strong, low flammability aerogels is an alternative to traditional polymer foams in applications where fire safety is important.

Fabrication of porous chitosan/poly(vinyl alcohol) reinforced single-walled carbon nanotube nanocomposites for neural tissue engineering.

PubMed

Shokrgozar, Mohammad Ali; Mottaghitalab, Fatemeh; Mottaghitalab, Vahid; Farokhi, Mehdi

2011-04-01

With the ability to form a nano-sized fibrous structure with large pore sizes mimicking the extracellular matrix (ECM), electrospinning was used to fabricate chitosan/poly(vinyl alcohol) nanofibers reinforced by single-walled carbon nanotube (SWNT-CS/PVA) for potential use in neural tissue engineering. Moreover, ultrasonication was performed to fabricate highly dispersed SWNT/CS solution with 7%, 12%, and 17% SWNT content prior to electrospinning process. In the present study, a number of properties of CS/PVA reinforced SWNTs nanocomposites were evaluated. The in vitro biocompatibility of the electrospun fiber mats was also assessed using human brain-derived cells and U373 cell lines. The results have shown that SWNTs as reinforcing phase can augment the morphology, porosity, and structural properties of CS/PVA nanofiber composites and thus benefit the proliferation rate of both cell types. In addition, the cells exhibit their normal morphology while integrating with surrounding fibers. The results confirmed the potential of SWNT-CS/PVA nanocomposites as scaffold for neural tissue engineering.

Self-healing pH-sensitive poly[(methyl vinyl ether)-alt-(maleic acid)]-based supramolecular hydrogels formed by inclusion complexation between cyclodextrin and adamantane.

PubMed

Ma, Xiaoe; Zhou, Naizhen; Zhang, Tianzhu; Hu, Wanjun; Gu, Ning

2017-04-01

Self-healing materials are of interest for drug delivery, cell and gene therapy, tissue engineering, and other biomedical applications. In this work, on the base of biocompatible polymer poly(methyl vinyl ether-alt-maleic acid) (P(MVE-alt-MA)), host polymer β-cyclodextrin-grafted P(MVE-alt-MA) (P(MVE-alt-MA)-g-β-CD) and guest polymer adamantane-grafted P(MVE-alt-MA) (P(MVE-alt-MA)-g-Ad) were first prepared. Then through taking advantage of the traditional host-guest interaction of β-cyclodextrin and adamantane, a novel self-healing pH-sensitive physical P(MVE-alt-MA)-g-β-CD/P(MVE-alt-MA)-g-Ad supramolecular hydrogels were obtained after simply mixing the aqueous solution of host polymer and guest polymer. This kind of supramolecular hydrogels not only possess pH-sensitivity, but also possess the ability to repair themselves after being damaged. Copyright © 2016 Elsevier B.V. All rights reserved.

Optical absorption and thermally stimulated depolarization current studies of nickel chloride-doped poly(vinyl alcohol) irradiated with low-level fast neutron doses

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

Abd El-Kader, F.H.; Ibrahim, S.S.; Attia, G.

1993-11-15

The influence of neutron irradiation on ultraviolet/visible absorption and thermally stimulated depolarization current in nickel chloride-poly(vinyl alcohol) (PVA) cast films has been investigated. The spectral measurements indicate the responsibility of the Ni[sup 2][sup +] ion in its octahedral symmetry. Dopant concentrations higher than 10 wt % NiCl[sub 2] are found to make the samples more resistant to a degradation effect caused by neutron irradiation. The thermally stimulated depolarization currents (TSDC) of pure PVA revealed the existence of the glass transition T[sub g] and space charge relaxation peaks, whereas doped-PVA samples show a new sub-T[sub g] relaxation peak. A proposed mechanismmore » is introduced to account for the neutron effects on both glass transition and space charge relaxation peaks. The peak positions, peak currents, and stored charges of the sub-T[sub g] relaxation peak are strongly affected by both the concentration of the dopant and neutron exposure doses.« less

Fabrication of high quality carbonaceous coating on Cu nanoparticle using poly(vinyl pyrrolidone) and its application for oxidation prevention

NASA Astrophysics Data System (ADS)

Pyo, Youngjun; Choi, Dahyun; Son, Yeon-Ho; Kang, Suhee; Yoon, Eric H.; Jung, Seung-Boo; Kim, Yongil; Sunyong Lee, Caroline

2016-05-01

A novel method of carbonaceous coating on the surface of copper particles was developed through a chemical vapor deposition (CVD) process to prevent the oxidation of copper nanoparticles (CNPs). The types of poly(vinyl pyrrolidone) (PVP) used were K-12 (M W 3,500) and K-30 (M W 45,000). The amounts of PVP used ranged from 10 to 50 wt %. Additionally, processing temperatures of 900 and 875 °C were tested and compared. The optimum CVD process conditions for the carbonaceous coating were as follows: 875 °C processing temperature, 50 wt % K12 PVP solution, and gas conditions of \\text{Ar}:\\text{H}2 = 1:1. The resistivity change in the fabricated copper pattern was confirmed that the initial resistivity value of the ink with a mixing ratio of carbonaceous-coated CNPs to 1-octanethiol-coated CNPs of 4:6 (w/w) maintained its initial resistivity value of 2.93 × 10-7 Ω·m for more than 210 days.

Facile Preparation of Doxorubicin-Loaded and Folic Acid-Conjugated Carbon Nanotubes@Poly(N-vinyl pyrrole) for Targeted Synergistic Chemo-Photothermal Cancer Treatment.

PubMed

Wang, Daquan; Ren, Yibo; Shao, Yongping; Yu, Demei; Meng, Lingjie

2017-11-15

We developed a bifunctional nanoplatform for targeted synergistic chemo-photothermal cancer treatment. The nanoplatform was constructed through a facile method in which poly(N-vinyl pyrrole) (PVPy) was coated on cut multiwalled carbon nanotubes (c-MWNTs); FA-PEG-SH was then linked by thiol-ene click reaction to improve the active targeting ability, water dispersibility, and biocompatibility and to extend the circulation time in blood. The PVPy shell not only enhanced the photothermal effect of c-MWNTs significantly but also provided a surface that could tailor targeting molecules and drugs. The resulting MWNT@PVPy-S-PEG-FA possessed high drug-loading ratio as well as pH-sensitive unloading capacity for a broad-spectrum anticancer agent, doxorubicin. Owing to its outstanding efficiency in photothermal conversion and ability in targeted drug delivery, the material could potentially be used as an efficient chemo-photothermal therapeutic nanoagent to treat cancer.

Neutron spin-echo studies on dynamic and static fluctuations in two types of poly(vinyl alcohol) gels

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

Kanaya, T.; Takahashi, N.; Nishida, K.

2005-01-01

We report neutron spin-echo measurements on two types of poly(vinyl alcohol) (PVA) gels. The first is PVA gel in a mixture of dimethyl sulfoxide (DMSO) and water with volume ratio 60/40, and the second is PVA gel in an aqueous borax solution. The observed normalized intermediate scattering functions I(Q,t)/I(Q,0) are very different between them. The former I(Q,t)/I(Q,0) shows a nondecaying component in addition to a fast decay, but the latter does not have the nondecaying one. This clearly indicates that the fluctuations in the former PVA gel consist of static and dynamic fluctuations whereas the latter PVA gel does includemore » only the dynamic fluctuations. The dynamic fluctuations of the former and latter gels have been analyzed in terms of a restricted motion in the network and Zimm motion, respectively, and the origins of these motions will be discussed.« less

Ultralight super-hydrophobic carbon aerogels based on cellulose nanofibers/poly(vinyl alcohol)/graphene oxide (CNFs/PVA/GO) for highly effective oil-water separation.

PubMed

Xu, Zhaoyang; Zhou, Huan; Tan, Sicong; Jiang, Xiangdong; Wu, Weibing; Shi, Jiangtao; Chen, Peng

2018-01-01

With the worsening of the oil-product pollution problem, oil-water separation has attracted increased attention in recent years. In this study, a porous three-dimensional (3D) carbon aerogel based on cellulose nanofibers (CNFs), poly(vinyl alcohol) (PVA) and graphene oxide (GO) was synthesized by a facile and green approach. The resulting CNF/PVA/GO aerogels were synthesized through an environmentally friendly freeze-drying process and then carbonized to yield CNF/PVA/GO carbon aerogels with low density (18.41 mg cm -3 ), high porosity (98.98%), a water contact angle of 156° (super-hydrophobic) and high oil absorption capacity (97 times its own weight). The carbonization treatment of the CNF/PVA/GO aerogel not only improved the hydrophobic properties but also enhanced the adsorption capacity and specific surface area. Given the many good performance characteristics and the facile preparation process of carbon aerogels, these materials are viable candidates for use in oil-water separation and environmental protection.

Effect of electron beam radiation processing on mechanical and thermal properties of fully biodegradable crops straw/poly (vinyl alcohol) biocomposites

NASA Astrophysics Data System (ADS)

Guo, Dan

2017-01-01

Fully biodegradable biocomposites based on crops straw and poly(vinyl alcohol) was prepared through thermal processing, and the effect of electron beam radiation processing with N,N-methylene double acrylamide as radiation sensitizer on mechanical and thermal properties of the biocomposites were investigated. The results showed that, when the radiation dose were in the range of 0-50 kGy, the mechanical and thermal properties of the biocomposites could be improved significantly through the electron beam radiation processing, and the interface compatibility was also improved because of the formation of stable cross-linked network structure, when the radiation dose were above the optimal value (50 kGy), the comprehensive properties of the biocomposites were gradually destroyed. EB radiation processing could be used as an effective technology to improve the comprehensive performance of the biocomposites, and as a green and efficient processing technology, radiation processing takes place at room temperature, and no contamination and by-product are possible.

Preparation and Properties of Electrospun Poly (Vinyl Pyrrolidone)/Cellulose Nanocrystal/Silver Nanoparticle Composite Fibers

PubMed Central

Huang, Siwei; Zhou, Ling; Li, Mei-Chun; Wu, Qinglin; Kojima, Yoichi; Zhou, Dingguo

2016-01-01

Poly (vinyl pyrrolidone) (PVP)/cellulose nanocrystal (CNC)/silver nanoparticle composite fibers were prepared via electrospinning using N,N′-dimethylformamide (DMF) as a solvent. Rheology, morphology, thermal properties, mechanical properties, and antimicrobial activity of nanocomposites were characterized as a function of material composition. The PVP/CNC/Ag electrospun suspensions exhibited higher conductivity and better rheological properties compared with those of the pure PVP solution. The average diameter of the PVP electrospun fibers decreased with the increase in the amount of CNCs and Ag nanoparticles. Thermal stability of electrospun composite fibers was decreased with the addition of CNCs. The CNCs help increase the composite tensile strength, while the elongation at break decreased. The composite fibers included Ag nanoparticles showed improved antimicrobial activity against both the Gram-negative bacterium Escherichia coli (E. coli) and the Gram-positive bacterium Staphylococcus aureus (S. aureus). The enhanced strength and antimicrobial performances of PVP/CNC/Ag electrospun composite fibers make the mat material an attractive candidate for application in the biomedical field. PMID:28773644

Thermodynamic and spectroscopic analysis of the conformational transition of poly(vinyl alcohol) by temperature-dependent FTIR

NASA Astrophysics Data System (ADS)

Han, Shan; Luan, Ye-Mei; Pang, Shu-Feng; Zhang, Yun-Hong

2015-03-01

The conformational change of poly(vinyl alcohol) has been studied by Fourier transform infrared spectroscopy at various temperatures in the 4000-400 cm-1 region. The molecular motion and the trans/gauche content are sensitive to the Csbnd H, Csbnd C stretching modes. FTIR spectra show that the I2920/I2849 decreases from 1.84 to 1.0 with increasing temperature, companying the decrease in I1047/I1095 from 0.78 to 0.58, implying the conformational transition from trans to gauche in alkyl chain. Based on the van't Hoff relation, the enthalpies and entropies have been calculated in different temperatures, which are 4.61 kJ mol-1 and 15.23 J mol-1 K-1, respectively, in the region of 80-140 °C. From the Cdbnd O stretching mode and Osbnd H band, it can be concluded that the intermolecular hydrogen bonds decrease owing to elevating temperature, which leads to more gauche conformers.

Novel synthesis of cobalt/poly vinyl alcohol/gamma alumina nanocomposite for catalytic application

NASA Astrophysics Data System (ADS)

Hatamie, Shadie; Ahadian, Mohammad Mahdi; Rashidi, Alimoradeh; Karimi, Ali; Akhavan, Omid

2017-05-01

In this manuscript, synthesis of cobalt/poly vinyl alcohol (PVA)/gamma alumina nanocomposite via a simple room temperature, as well as its catalyst performance were explored. Brunauer-Emmett-Teller analysis, X-ray diffraction, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy were conducted. The surface area of the polymeric composite was obtained to be 280 m2/g. The cobalt loading on the nanocomposite was measured using inductivity couple plasma. Transmission electron microscopy analysis showed that the size of cobalt crystalline encapsulate inside the polymer was confined to 5 nm. Magnetic property analysis, using vibrating sample magnetometer, confirmed ferromagnetic nature of the composite. Thermo-gravimetric analyses were employed to explain the degradation process for the polymeric base nanocomposite. Temperature-programmed reduction was used to evaluate the structural form of cobalt oxide in nanocomposite. The catalysis activity was determined by Fischer-Tropsch synthesize, which showed a high catalyst selectivity to C2-C4 hydrocarbons.

Poly (vinyl alcohol) as a capping agent in oven dried cellulose nanofibrils.

PubMed

Velásquez-Cock, J; Gómez H, B E; Posada, P; Serpa G, A; Gómez H, C; Castro, C; Gañán, P; Zuluaga, R

2018-01-01

Commercialization of cellulose nanofibrils (CNFs) involves addressing various challenges. Among them, wet storage and transport of CNFs due to their irreversible agglomeration when dehydrated (i.e., hornification) is a pressing issue, as it increases transportation costs. Various alternatives have been proposed in literature, some of which require the use of high-energy treatments to facilitate their redispersion after drying, while others may be inadequate when applied to food and pharmaceutical applications. The present work examines a new approach that involves using poly (vinyl alcohol) (PVA) as a capping agent to redisperse CNFs. Different CNF to PVA ratios were used, and redispersed samples were analyzed in terms of their morphological, physicochemical and rheological properties to assess changes occurring during processing. Results show that the ratio of CNFs to PVA affects the final properties of the redispersed product, when the ratio 1:2.5 was used, the redispersed product closely resembles the never dried sample. Copyright © 2017 Elsevier Ltd. All rights reserved.

Synthesis and characterization of core-shell gold nanoparticles with poly(vinyl pyrrolidone) from a new precursor salt

NASA Astrophysics Data System (ADS)

Behera, M.; Ram, S.

2013-02-01

In this article, we report a facile one-step chemical synthesis of gold (Au) nanoparticles (GNPs) from a new precursor salt i.e., gold hydroxide in the presence of poly(vinyl pyrrolidone) (PVP) polymer. The non-aqueous dispersion of GNPs was comprehensively characterized by UV-Visible, FTIR, zeta potential, and transmission electron microscope (TEM). A strong surface plasmon resonance band at 529 nm in the UV-Visible spectrum confirms the formation of GNPs in the Au colloid. The FTIR spectroscopic results showed that PVP molecules get chemisorbed onto the surface of GNP via O-atom of carbonyl group. A negative zeta potential of (-)16 mV reveals accumulation of nonbonding electrons of O-atom of carbonyl group of PVP molecules on the nanosurface of GNP. TEM images demonstrate a core-shell nanostructure with an Au-crystalline core covered by a thin amorphous PVP-shell. PVP-capped GNPs could be a potential candidate for bio-sensing, catalysis, and other applications.

Label-free potentiometric biosensor based on solid-contact for determination of total phenols in honey and propolis.

PubMed

Draghi, Patrícia Ferrante; Fernandes, Julio Cesar Bastos

2017-03-01

We developed a label-free potentiometric biosensor using tyrosinase extracted from Musa acuminata and immobilized by covalent bond on a surface of a solid-contact transducer. The transducer was manufactured containing two layers. The first layer contained a blend of poly(vinyl) chloride carboxylated (PVC-COOH), graphite and potassium permanganate. On this layer, we deposited a second layer containing just a mixture of poly(vinyl chloride) carboxylated and graphite. On the last layer of the transducer, we immobilized the tyrosinase enzyme by reaction with N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride. The solid-contact potentiometric biosensor presented at low detection limit of 7.3×10 -7 M and a linear range to catechol concentration between 9.3×10 -7 M and 8.3×10 -2 M. This biosensor was applied to determine the amount of total phenols in different samples of honey and propolis. The results agreed with the Folin-Ciocalteu method. Copyright © 2016 Elsevier B.V. All rights reserved.

Acoustic Behavior of Subfloor Lightweight Mortars Containing Micronized Poly (Ethylene Vinyl Acetate) (EVA).

PubMed

Brancher, Luiza R; Nunes, Maria Fernanda de O; Grisa, Ana Maria C; Pagnussat, Daniel T; Zeni, Mára

2016-01-15

This paper aims to contribute to acoustical comfort in buildings by presenting a study about the polymer waste micronized poly (ethylene vinyl acetate) (EVA) to be used in mortars for impact sound insulation in subfloor systems. The evaluation method included physical, mechanical and morphological properties of the mortar developed with three distinct thicknesses designs (3, 5, and 7 cm) with replacement percentage of the natural aggregate by 10%, 25%, and 50% EVA. Microscopy analysis showed the surface deposition of cement on EVA, with preservation of polymer porosity. The compressive creep test estimated long-term deformation, where the 10% EVA sample with a 7 cm thick mortar showed the lowest percentage deformation of its height. The impact noise test was performed with 50% EVA samples, reaching an impact sound insulation of 23 dB when the uncovered slab was compared with the 7 cm thick subfloor mortar. Polymer waste addition decreased the mortar compressive strength, and EVA displayed characteristics of an influential material to intensify other features of the composite.

The Impact of the Polymer Chain Length on the Catalytic Activity of Poly(N-vinyl-2-pyrrolidone)-supported Gold Nanoclusters.

PubMed

Haesuwannakij, Setsiri; Kimura, Tetsunari; Furutani, Yuji; Okumura, Kazu; Kokubo, Ken; Sakata, Takao; Yasuda, Hidehiro; Yakiyama, Yumi; Sakurai, Hidehiro

2017-08-29

Poly(N-vinyl-2-pyrrolidone) (PVP) of varying molecular weight (M w  = 40-360 kDa) were employed to stabilize gold nanoclusters of varying size. The resulting Au:PVP clusters were subsequently used as catalysts for a kinetic study on the sized-dependent aerobic oxidation of 1-indanol, which was monitored by time-resolved in situ infrared spectroscopy. The obtained results suggest that the catalytic behaviour is intimately correlated to the size of the clusters, which in turn depends on the molecular weight of the PVPs. The highest catalytic activity was observed for clusters with a core size of ~7 nm, and the size of the cluster should increase with the molecular weight of the polymer in order to maintain optimal catalytic activity. Studies on the electronic and colloid structure of these clusters revealed that the negative charge density on the cluster surface also strongly depends on the molecular weight of the stabilizing polymers.

Effect of freeze-thawing conditions for preparation of chitosan-poly (vinyl alcohol) hydrogels and drug release studies.

PubMed

Figueroa-Pizano, M D; Vélaz, I; Peñas, F J; Zavala-Rivera, P; Rosas-Durazo, A J; Maldonado-Arce, A D; Martínez-Barbosa, M E

2018-09-01

The freezing-thawing is an advantageous method to produce hydrogels without crosslinking agents. In this study chitosan-poly(vinyl alcohol) (CS-PVA) hydrogels were prepared by varying the freezing conditions and composition, which affect the final characteristics of the products. The swelling degree, morphology, porosity, and diflunisal drug loading, as well as the drug release profiles were evaluated. The hydrogel swelling ratio was found to be mainly affected by the CS content, the number of freezing cycles and the temperature. SEM micrographs and porosity data confirm that pore size increases with the chitosan content. However, the use of either lower temperatures or longer freezing times, results in higher porosity and smaller pores. The drug release times of the CS-PVA hydrogels were as long as 30 h, and according to the mathematical fitting, a simple diffusion mechanism dominates the process. Moreover, a mathematical model predicting the hydrogels physical and structural behavior is proposed. Copyright © 2018 Elsevier Ltd. All rights reserved.

New multifunctional materials obtained by the intercalation of anionic dyes into layered zinc hydroxide nitrate followed by dispersion into poly(vinyl alcohol) (PVA).

PubMed

Marangoni, Rafael; Ramos, Luiz Pereira; Wypych, Fernando

2009-02-15

Different anionic blue and orange dyes have been immobilized on a zinc hydroxide nitrate (Zn(5)(OH)(8)(NO(3))(2)nH(2)O--Zn-OH-NO(3)) by anion exchange with interlayer and/or outer surface nitrate ions of the layered matrix. Orange G (OG) was totally intercalated, orange II (OII) was partially intercalated, while Niagara blue 3B (NB) and Evans blue (EV) were only adsorbed at the outer surface. Several composite films of poly(vinyl alcohol)--PVA were prepared by casting through the dispersion of the hybrid material (Zn-OH-OG) into a PVA aqueous solution and evaporation of water in a vacuum oven. The obtained composite films were transparent, colored, and capable of absorbing UV radiation. Improved mechanical properties were also obtained in relation to the nonfilled PVA films. These results demonstrate the onset of a new range of potential applications for layered hydroxide salts in the preparation of polymer composite multifunctional materials.

Development of biomimetic nanocomposites as bone extracellular matrix for human osteoblastic cells.

PubMed

Bhowmick, Arundhati; Mitra, Tapas; Gnanamani, Arumugam; Das, Manas; Kundu, Patit Paban

2016-05-05

Here, we have developed biomimetic nanocomposites containing chitosan, poly(vinyl alcohol) and nano-hydroxyapatite-zinc oxide as bone extracellular matrix for human osteoblastic cells and characterized by Fourier transform infrared spectroscopy, powder X-ray diffraction. Scanning electron microscopy images revealed interconnected macroporous structures. Moreover, in this study, the problem related to fabricating a porous composite with good mechanical strength has been resolved by incorporating 5wt% of nano-hydroxyapatite-zinc oxide into chitosan-poly(vinyl alcohol) matrix; the present composite showed high tensile strength (20.25MPa) while maintaining appreciable porosity (65.25%). These values are similar to human cancellous bone. These nanocomposites also showed superior water uptake, antimicrobial and biodegradable properties than the previously reported results. Compatibility with human blood and pH was observed, indicating nontoxicity of these materials to the human body. Moreover, proliferation of osteoblastic MG-63 cells onto the nanocomposites was also observed without having any negative effect. Copyright © 2016 Elsevier Ltd. All rights reserved.

Facile and green fabrication of electrospun poly(vinyl alcohol) nanofibrous mats doped with narrowly dispersed silver nanoparticles.

PubMed

Lin, Song; Wang, Run-Ze; Yi, Ying; Wang, Zheng; Hao, Li-Mei; Wu, Jin-Hui; Hu, Guo-Han; He, Hua

2014-01-01

Submicrometer-scale poly(vinyl alcohol) (PVA) nanofibrous mats loaded with aligned and narrowly dispersed silver nanoparticles (AgNPs) are obtained via the electrospinning process from pure water. This facile and green procedure did not need any other chemicals or organic solvents. The doped AgNPs are narrowly distributed, 4.3±0.7 nm and their contents on the nanofabric mats can be easily tuned via in situ ultraviolet light irradiation or under preheating conditions, but with different particle sizes and size distributions. The morphology, loading concentrations, and dispersities of AgNPs embedded within PVA nanofiber mats are characterized by transmission electron microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, ultraviolet-visible spectra, X-ray photoelectron spectroscopy, and X-ray diffraction, respectively. Moreover, the biocidal activities and cytotoxicity of the electrospun nanofiber mats are determined by zone of inhibition, dynamic shaking method, and cell counting kit (CCK)-8 assay tests.

40 CFR 721.10044 - Metal oxide, modified with alkyl and vinyl terminated polysiloxanes (generic).

Code of Federal Regulations, 2010 CFR

2010-07-01

... and vinyl terminated polysiloxanes (PMN P-02-698) is subject to reporting under this section for the... specified in § 721.125 (a), (b), (c), and (i) are applicable to manufacturers, importers, and processors of...

Organogel polymers from 10-undecenoic acid and poly(vinyl acetate)

USDA-ARS?s Scientific Manuscript database

Organogels are used in a variety of high value applications including the removal of toxic solvents from aqueous environments and the time-controlled release of compounds. One of the most promising gelators is a polyvinyl polymer containing medium chain length carboxylic acids. The existing producti...

Nonaqueous polypyrrole colloids

DOEpatents

Armes, Steven P.; Aldissi, Mahmoud

1991-01-01

Processable conductive polymers including an oxidized, polymerized aromatic heterocyclic monomer, e.g., pyrrole, an stabilizing effective amount of a poly(vinyl acetate) and dopant anions, and a process of preparing said processable conductive polymers directly in a nonaqueous medium such as methyl acetate, methyl formate, ethyl formate, and propyl formate are disclosed.

Polymeric blend nanocomposite membranes for ethanol dehydration-effect of morphology and membrane-solvent interactions

EPA Science Inventory

Nanocomposite membranes (NCMs) of sodium alginate/poly(vinyl pyrrolidone) blend polymers incorporated with varying concentrations of phosphotungstic acid (H3PW12O40) (PWA) nanoparticles have been prepared and used in ethanol dehydration by the pervaporation (PV) technique. Effe...

Synthesis and evaluation of acryloylated starch-g-poly (Acrylamide/Vinylmethacrylate/1-Vinyl-2-pyrrolidone) crosslinked terpolymer functionalized by dimethylphenylvinylsilane derivative as a novel polymer-flooding agent.

PubMed

El-Hoshoudy, A N; Desouky, S M

2018-05-16

Starch is a natural biopolymer that subjected to various chemical modifications through different industrial applications. Molecular structure of starch allow its grafting with different vinyl monomers in the presence of crosslinking agents to synthesize cross-linked hydrogels, which used in enhanced oil recovery (EOR) applications, water shutoff and drag reduction. Application of native starch in the field of petroleum reservoirs as a flooding agent suffer from some limitations concerned with microbial degradation, thermal and salinity resistance under harsh petroleum reservoir conditions. In the current research, we stated the synthesis of acryloylated starch then it's grafting with poly (Acrylamide/Vinylmethacrylate/1-Vinyl-2-pyrrolidone) terpolymer in presence of dimethylphenylvinylsilane through emulsification polymerization. Characterization and structure determination occur by different spectroscopic techniques as stated throughout the manuscript. Rheological and solution properties carried out as a function of shear rate, salinity and temperature at simulated reservoir conditions. Flooding tests carried out through linear-dimensional sandstone model at simulated reservoir conditions, and recovered oil amount calculated on volumetric basis. The obtained results indicate that the prepared starch-g-terpolymer can tolerate to severe flooding conditions of high temperature and salinity, moreover it can increase recovery factor up to 49% of residual oil saturation so considered as a promised EOR candidate. Copyright © 2017 Elsevier B.V. All rights reserved.

Calcium Stearate as an Effective Alternative to Poly(vinyl alcohol) in Poly-Lactic-co-Glycolic Acid Nanoparticles Synthesis.

PubMed

Cella, Claudia; Gerges, Irini; Milani, Paolo; Lenardi, Cristina; Argentiere, Simona

2017-02-13

Poly(d,l-lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) are among the most studied systems for drug and gene targeting. So far, the synthesis of stable and uniform PLGA NPs has involved the use of a large excess of polyvinyl surfactants such as poly(vinyl alcohol) (PVA) and polyvinylpyrrolidone (PVP), whose removal requires multistep purification procedures of high ecological and economic impact. Hence the development of environment-friendly and cost-effective synthetic procedures for the synthesis of PLGA NPs would effectively boost their use in clinics. This work aims to address this issue by investigating more efficacious alternatives to the so far employed polyvinyl surfactants. More specifically, we developed an innovative synthetic process to achieve stable and uniformly distributed PLGA NPs that involves the use of calcium stearate (CSt), gaining benefits of its high biocompatibility and efficacy at low concentrations and avoiding consequently expensive purification steps. With the help of minimum quantities of polysorbate 60 and sorbitane monostearate, CSt-stabilized PLGA NPs with different sizes and structures were synthesized. The influence of CSt on the encapsulation efficiency of bioactive molecules has been also investigated. The effective encapsulation of both hydrophobic (curcumin) and hydrophilic (fibrinogen labeled with Alexa647) biomolecules into NPs was demonstrated by confocal microscopy, and their release quantified by spectrofluorimetric analyses. Finally, degradation and cytotoxicity studies showed that CSt stabilized NPs were stable under physiological conditions and with good biocompatibility, thus looking promising for further investigation as controlled release devices.

Investigation of yeast invertase immobilization onto cupric ion-chelated, porous, and biocompatible poly(hydroxyethyl methacrylate-n-vinyl imidazole) microspheres.

PubMed

Sari, Müfrettin Murat

2011-04-01

Cupric ion-chelated poly(hydroxyethyl methacrylate-n-vinyl imidazole) (poly(HEMA-VIM)) microspheres prepared by suspension polymerization were investigated as a specific adsorbent for immobilization of yeast invertase in a batch system. They were characterized by scanning electron microscopy, surface area, and pore size measurements. They have spherical shape and porous structure. The specific surface area of the p(HEMA-VIM) spheres was found to be 81.2 m²/g with a size range of 70-120 μm in diameter, and the swelling ratio was 86.9%. Then, Cu(II) ion chelated on the microspheres (546 μmol Cu(II)/g), and they were used in the invertase adsorption. Maximum invertase adsorption was 51.2 mg/g at pH 4.5. Cu(II) chelation increases the tendency from Freundlich-type to Langmuir-type adsorption model. The optimum activity for both free and adsorbed invertase was observed at pH 4.5. The optimum temperature for the poly(HEMA-VIM)/Cu(II)-invertase system was found to be at 55 °C, 10 °C higher than that of the free enzyme at 45 °C. V(max) values were determined as 342 and 304 U/mg enzyme, for free and adsorbed invertase, respectively. K(m) values were found to be same for free and adsorbed invertase (20 mM). Thermal and pH stability and reusability of invertase increased with immobilization.

Performance improvement of gel- and solid-state dye-sensitized solar cells by utilization the blending effect of poly (vinylidene fluoride-co-hexafluropropylene) and poly (acrylonitrile-co-vinyl acetate) co-polymers

NASA Astrophysics Data System (ADS)

Venkatesan, Shanmugam; Obadja, Nesia; Chang, Ting-Wei; Chen, Li-Tung; Lee, Yuh-Lang

2014-12-01

Poly (vinylidene fluoride-co-hexafluropropylene) (PVDF-HFP) and poly (acrylonitrile-co-vinyl acetate) (PAN-VA) are used as gelator to prepare gel- and solid-state polymer electrolytes for dye sensitized solar cells (DSSCs) applications. The electrolytes prepared using PVDF-HFP have higher conductivities than those prepared using PAN-VA. In blended polymers, the conductivities of the electrolytes increase with increasing composition of PVDF-HFP; at 75% PVDF-HFP, conductivity of the blended polymer surpassed that of pure polymers. It is also found that the viscosity of the electrolyte prepared by PAN-VA (1.2 kPaS) is much lower than that by PVDF-HFP (11 kPaS). Therefore, increasing PAN-VA composition can decrease the viscosity of the electrolyte, improving the penetration of electrolytes in the TiO2 matrix. By controlling the ratio of PVDF-HFP/PAN-VA, the conductivity and viscosity of the electrolyte can be regulated and an optimal ratio based on the conversion efficiency of the gel- and solid state DSSCs is obtained at the ratio of 3/1. The highest efficiency achieved by the gel- and solid-state cells using the blending polymers are 6.3% and 4.88%, respectively, which are higher than those prepared using pure polymers (5.53% and 4.56%, respectively). The introduction of TiO2 fillers to the solid electrolyte can further increase the cell efficiency to 5.34%.

Protein valves prepared by click reaction grafting of poly(N-isopropylacrylamide) to electrospun poly(vinyl chloride) fibrous membranes

NASA Astrophysics Data System (ADS)

Guo, Jian-Wei; Lin, Zhen-Yu; Chang, Chi-Jung; Lu, Chien-Hsing; Chen, Jem-Kun

2018-05-01

In this study, poly(vinyl chloride) (PVC) was electrospun into fibrous membranes and then reacted with NaN3 to generate azido-terminated PVC fibrous membranes. A propargyl-terminated poly(N-isopropylacrylamide) (PNIPAAm) was also synthesized and then grafted, through click reactions, onto the azido-terminated PVC fiber surface. Protrusion-, scale-, and joint-like structures of the PNIPAAm grafts on the PVC fibers were formed upon increasing the molecular weight of the PNIPAAm grafts. The PNIPAAm-grafted PVC fibrous mats exhibited completely wetted surfaces at 25 °C because of their high roughness. The static water contact angle of the PNIPAAm-grafted PVC fibrous mats reached 140° when the temperature was increased to 45 °C. This thermoresponsive behavior was significantly greater than that of the PNIPAAm grafted on a flat surface. Temperature-responsive membranes were constructed having a pore size of 1.38 μm and applied as protein valves to block and release an antibody (fluorescein-conjugated AffiniPure goat anti-rabbit IgG). At 25 °C, the collection efficiency remained at 94% for antibody concentrations up to 60 ng/L. As the temperature increased to 45 °C, the collection efficiency decreased abruptly, to 4%, when the antibody concentration was greater than 20 ng/L. Accordingly, this system of PNIPAAm-grafted PVC fibers functioned as a protein valve allowing the capture and concentration of proteins.

Covalent attachment of polymeric monolith to polyether ether ketone (PEEK) tubing.

PubMed

Lv, Chunguang; Heiter, Jaana; Haljasorg, Tõiv; Leito, Ivo

2016-08-17

A new method of reproducible preparation of vinylic polymeric monolithic columns with a key step of covalently anchoring the monolith to PEEK surface is described. In order to chemically attach the polymer monolith to the tube wall, methacrylate functional groups were introduced onto PEEK surface by a three-step procedure, including surface etching, surface reduction and surface methacryloylation. The chemical state of the modified tubing surface was characterized by attenuated total reflectance infrared (ATR-IR) spectroscopy. It was found that the etching step is the key to successfully modifying the PEEK tubing surface. Poly(styrene-co-divinylbenzene) monoliths were in situ synthesized by thermally initiated free radical copolymerization within the confines of surface-vinylized PEEK tubings of dimensions close to ones conventionally used in HPLC and UHPLC (1.6 mm internal diameter, 10.0-12.5 cm length). Adhesion test was done by measuring the operating pressure drop, which the prepared stationary phases can withstand. Good pressure resistance, up to 140 bar/10 cm (flow rate 0.5 mL min(-1), acetonitrile as a mobile phase), indicates strong bonding of monolith to the tubing wall. The monolithic material was proven to have a permeability of 1.7 × 10 (-14) m(2), applying acetonitrile-water 70:30 (v/v) as a mobile phase. The column performance was reproducible from column to column and was evaluated via the isocratic separation of a series of alkylbenzenes in the reversed-phase mode (acetonitrile-water 70:30, v/v). The numbers of plates per meter at optimal flow rate were found to be between 26 000 and 32 000 for the different analytes. Copyright © 2016 Elsevier B.V. All rights reserved.

Characterisation of historic plastics using terahertz time-domain spectroscopy and pulsed imaging.

PubMed

Pastorelli, Gianluca; Trafela, Tanja; Taday, Phillip F; Portieri, Alessia; Lowe, David; Fukunaga, Kaori; Strlič, Matija

2012-05-01

Terahertz (THz) time-domain spectroscopy and 3D THz pulsed imaging have been explored with regard to polymer materials, both commodity and historic polymers. A systematic spectroscopic study of a wide range of different polymer materials showed significant differences in their spectra. Polyolefins and polystyrenes generally exhibit lower absorption than other examined polymers, various cellulose derivates, poly(vinyl chloride), poly(methyl methacrylate), polyamide, hard rubber and phenol formaldehyde resin, the last of these exhibiting the most intense absorption over the entire range, 0.15-4.2 THz. It was also examined how the presence of plasticisers in poly(vinyl chloride), the presence of fillers in polypropylene, and the degree of branching in polyethylene and polystyrene affect the spectra; inorganic fillers in polypropylene affected the absorption most. With 3D THz pulsed imaging, features in polymer objects were explored, appearing either as integral parts of the material (coatings and pores in foams) or as a consequence of physical deterioration (cracks, delamination). All of these features of various complexities can be successfully imaged in 3D. Terahertz technology is thus shown to have significant potential for both chemical and structural characterisation of polymers, which will be of interest to heritage science, but also to the polymer industry and development of analytical technologies in general.

In vivo evaluation of the bone integration of coated poly(vinyl-alcohol) hydrogel fiber implants.

PubMed

Moreau, David; Villain, Arthur; Bachy, Manon; Proudhon, Henry; Ku, David N; Hannouche, Didier; Petite, Hervé; Corté, Laurent

2017-08-01

Recently, it has been shown that constructs of poly(vinyl alcohol) (PVA) hydrogel fibers reproduce closely the tensile behavior of ligaments. However, the biological response to these systems has not been explored yet. Here, we report the first in vivo evaluation of these implants and focus on the integration in bone, using a rabbit model of bone tunnel healing. Implants consisted in bundles of PVA hydrogel fibers embedded in a PVA hydrogel matrix. Half of the samples were coated with a composite coating of hydroxyapatite (HA) particles embedded in PVA hydrogel. The biological integration was evaluated at 6 weeks using histology and micro-CT imaging. For all implants, a good biological tolerance and growth of new bone tissue are reported. All the implants were surrounded by a fibrous layer comparable to what was previously observed for poly(ethylene terephthalate) (PET) fibers currently used in humans for ligament reconstruction. An image analysis method is proposed to quantify the thickness of this fibrous capsule. Implants coated with HA were not significantly osteoconductive, which can be attributed to the slow dissolution of the selected hydroxyapatite. Overall, these results confirm the relevance of PVA hydrogel fibers for ligament reconstruction and adjustments are proposed to enhance its osseointegration.

Processable dodecylbenzene sulfonic acid (DBSA) doped poly(N-vinyl carbazole)-poly(pyrrole) for optoelectronic applications

PubMed Central

Hammed, W. A.; Rahman, M. S.; Mahmud, H. N. M. E.; Yahya, R.; Sulaiman, K.

2017-01-01

Abstract A soluble poly (n-vinyl carbazole)–polypyrrole (PNVC–Ppy) copolymer was prepared through oxidative chemical polymerization wherein dodecyl benzene sulfonic acid (DBSA) was used as a dopant to facilitate polymer-organic solvent interaction and ammonium persulfate (APS) was used as an oxidant. Compared with undoped PNVC–Ppy, the DBSA-doped PNVC–Ppy copolymer showed higher solubility in some selected organic solvents. The composition and structural characteristics of the DBSA-doped PNVC–Ppy were determined by Fourier transform infrared, ultraviolet–visible, and X-ray diffraction spectroscopic methods. Field emission scanning electron microscopic method was employed to observe the morphology of the DBSA-doped PNVC–Ppy copolymer. The electrical conductivity of the DBSA-doped PNVC–Ppy copolymer was measured at room temperature. The conductivity increased with increasing concentration of APS oxidant, and the highest conductivity was recorded at 0.004 mol/dm3 APS at a polymerization temperature of −5 °C. The increased conductivity can be explained by the extended half-life of pyrrole free radical at a lower temperature and a gradual increase in chain length over a prolonged time due to the slow addition of APS. Furthermore, the obtained soluble copolymer exhibits unique optical and thermal properties different from those of PNVC and Ppy. PMID:29491808

An Analysis of Shock-Compression in Mo-Si Powder Mixtures Using Recovery and Time-Resolved Measurements

NASA Astrophysics Data System (ADS)

Vandersall, Kevin S.; Thadhani, Naresh N.

1999-06-01

The densification and reaction characteristics in the Mo-Si system were investigated utilizing recovery experiments as well as time resolved measurements with in-situ stress gages. The starting sample in all cases consisted of statically pressed Mo + 2 Si powder mixtures ( ~55% TMD). The recovery experiments were performed using the Sandia Momma Bear and Momma Bear A fixtures with baratol and composition B explosives respectively. The instrumented experiments were performed in a capsule design similar to that of the Momma Bear, but modified to incorporate poly-vinyl di-flouride (PVDF) stress gages at the front and rear surfaces of the powder. These experiments were performed using a single stage gas gun in the velocity range of 500 m/s to 1 km/s. The instrumented experiments allow the crush strength, densification history, and reaction threshold to be mapped at increasing pressure to correlate with reaction observed in the recovery experiments.

A temperature, pH and sugar triple-stimuli-responsive nanofluidic diode.

PubMed

Zheng, Yu-Bin; Zhao, Shuang; Cao, Shuo-Hui; Cai, Sheng-Lin; Cai, Xiu-Hong; Li, Yao-Qun

2017-01-07

In this article, we have demonstrated for the first time a triple stimuli-responsive nanofluidic diode that can rectify ionic current under multiple external stimuli including temperature, pH, and sugar. This diode was fabricated by immobilizing poly[2-(dimethylamino)ethyl methacrylate]-co-[4-vinyl phenylboronic acid] (P(DMAEMA-co-VPBA)) onto the wall of a single glass conical nanopore channel via surface-initiator atom transfer radical polymerization (SI-ATRP). The copolymer brushes contain functional groups sensitive to pH, temperature and sugar that can induce charge and configuration change to affect the status of the pore wall. The experimental results confirmed that the P(DMAEMA-co-VPBA) brush modified nanochannel regulated the ionic current rectification successfully under three different external stimuli. This biomimetically inspired research simulates the complex biological multi-functions of ion channels and promotes the development of "smart" biomimetic nanochannel systems for actuating and sensing applications.

A Strategy for Nonmigrating Plasticized PVC Modified with Mannich base of Waste Cooking Oil Methyl Ester.

PubMed

Jia, Puyou; Zhang, Meng; Hu, Lihong; Song, Fei; Feng, Guodong; Zhou, Yonghong

2018-01-25

The waste cooking oil (WCO) production from the catering industry and food processing industry causes serious environmental, economic and social problems. However, WCO can be used for the preparation of fine chemicals such as internal plasticizer. With this aim, this work is focused on preparing internal plasticizer by using WCO and determining technical viability of non-migration poly (vinyl chloride) (PVC) materials. The mannich base of waste cooking oil methyl ester (WCOME) was synthesized from WCO via esterification, interesterification and mannich reaction, which was used to produce self-plasticization PVC materials as an internal plasticizer. The results showed that the PVC was plasticized effectively. Self-plasticization PVC films showed no migration in n-hexane, but 15.7% of dioctyl phthalate (DOP) leached from DOP/PVC(50/50) system into n-hexane. These findings transformed the traditional plastic processing technology and obtained cleaner production of no migration plasticizer from WCO.

Studies on biodegradable and crosslinkable poly(castor oil fumarate)/poly(propylene fumarate) composite adhesive as a potential injectable biomaterial.

PubMed

Mitha, M K; Jayabalan, M

2009-12-01

Biodegradable hydroxyl terminated-poly(castor oil fumarate) (HT-PCF) and poly(propylene fumarate) (HT-PPF) resins were synthesized as an injectable and in situ-cross linkable polyester resins for orthopedic applications. An injectable adhesive formulation containing this resin blend, N-vinyl pyrrolidone (NVP), hydroxy apatite, free radical initiator and accelerator was developed. The Composite adhesives containing the ratio of resin blend and NVP, 2.1:1.5, 2.1:1.2 and 2.1:1.0 set fast with tolerable exothermic temperature as a three dimensionally cross linked toughened material. Crosslink density and mechanical properties of the crosslinked composite increase with increase of NVP. The present crosslinked composite has hydrophilic character and cytocompatibility with L929 fibroblast cells.

PVC: health implications and production trends.

PubMed Central

Karstadt, M

1976-01-01

Poly(vinyl chloride) (PVC) is a complex plastic system. Individual components of the PVC system, including residual vinyl chloride monomer (RVCM) and certain additives, may pose risks of harm to human health. There have been significant reductions in the RVCM content of PVC resin since 1974, reducing the cancer risk of workers in PVC fabrication plants and consumers of PVC products. A "no-effect" level for vinyl chloride monomer (VCM)-induced carcinogenesis has not been found to date; therefore, the significance of human exposure to low levels of RVCM remains to be determined. Exposure to PVC dust may cause pulmonary dysfunctions. Pulmonary and other possible health effects of PVC dust require further study. The PVC plastics system should be characterized as to interactions among its various components and as to interactions of the components and the PVC system as a whole with biological systems. Images FIGURE 1. FIGURE 2. PMID:799961

Nanocomposites prepared from acrylonitrile butadiene rubber and organically modified montmorillonite with vinyl groups

NASA Astrophysics Data System (ADS)

Han, Mijeong; Kim, Hoonjung; Kim, Eunkyoung

2006-01-01

Nanocomposites were prepared from acrylonitrile-butadiene rubber (NBR), vinyl groups containing organically modified montmorillonite and additives, such as zinc oxide, stearic acid, and sulfur. The organically modified montmorillonites used in these nanocomposites were prepared by ion exchange reactions of N,N'-dimethylalkyl-(p-vinylbenzyl)-ammonium chlorides (DAVBAs, alkyl = octyl, dodecyl, and octadecyl) with sodium montmorillonite (Na+-MMT). NBR nanocomposites were obtained by controlling both the mixing and vulcanization conditions, by using a Brabender mixer and hot-press process. X-ray diffraction (XRD) analysis shows that, depending on the amount of montmorillonite that is added, both exfoliated and intercalated nanocomposite structures are formed. The NBR/DAVBA-MMT nanocomposites exhibit much higher mechanical properties (e.g., tensile strength, Young's modulus, 300% modulus, and hardness) as well as gas barrier properties as compared to NBR Na+-MMT or NBR composites generated from modified montmorillonites without vinyl groups. Consistent with the results of XRD, transmission electron microscopy (TEM) reveals that the intercalation and exfoliation structures of the nanocomposites coexist and that the DAVBA-MMT layers are well dispersed in NBR.

Novel self-assembled amphiphilic poly(epsilon-caprolactone)-grafted-poly(vinyl alcohol) nanoparticles: hydrophobic and hydrophilic drugs carrier nanoparticles.

PubMed

Sheikh, Faheem A; Barakat, Nasser A M; Kanjwal, Muzafar A; Aryal, Santosh; Khil, Myung Seob; Kim, Hak-Yong

2009-03-01

In the present study, we have aimed to produce nanoparticles (NPs) possessing the capability of carrying both of the hydrophobic and hydrophilic drugs and reveal significant release for both drug types. Poly(epsilon-caprolactone) (PCL) grafted poly(vinyl alcohol) (PVA) copolymer (PCL-g-PVA) has been prepared and shaped in nano-particulate form to be adequate for carrying the drugs. Stannous octoate (Sn(II)Oct(2)) was used to catalyze PVA and epsilon-caprolactone monomer to chemically bond. Moreover, this catalyst enhanced side chain polymerization reaction for the utilized epsilon-caprolactone monomer to form poly(epsilon-caprolactone) (PCL). The formed PCL was attached as branches with PVA backbone. (1)H NMR has confirmed formation of PCL and grafting of PVA by this new polymer. Moreover, the vibration modes in the functional groups of PCL-g-PVA have been detected by FT-IR. The thermal alteration in the grafted polymer was checked by TGA analysis. The successfully synthesized grafted copolymer was able to self-aggregate into NPs by direct dialysis method. The size, morphology and charges associated with the obtained NPs were analyzed by DLS, TEM and ELS, respectively. PCL-g-PVA NPs were investigated as drug carrier models for hydrophobic and hydrophilic anti cancer drugs; paclitaxel and doxorubicin. In vitro drug release experiments were conducted; the loaded NPs reveal continuous and sustained release form for both drugs, up to 20 and 15 days for paclitaxel and doxorubicin, respectively. However, in a case of using pure drugs only, both drugs completely released within 1-2 h. The overall obtained results strongly recommend the use these novel NPs in future drug delivery systems.

Hydrogels Prepared from Cross-Linked Nanofibrillated Cellulose

Treesearch

Sandeep S. Nair; J.Y. Zhu; Yulin Deng; Arthur J. Ragauskas

2014-01-01

Nanocomposite hydrogels were developed by cross-linking nanofibrillated cellulose with poly(methyl vinyl ether-co-maleic acid) and polyethylene glycol. The cross-linked hydrogels showed enhanced water absorption and gel content with the addition of nanocellulose. In addition, the thermal stability, mechanical strength, and modulus increased with an increase in the...

ADMINISTRATIVE SETTLEMENT AGREEMENT AND ORDER ON CONSENT FOR REMEDIAL INVESTIGATION/FEASIBILITY STUDY, B.F. GOODRICH. CERCLA DOCKET NO. 04-2010-3761.

EPA Pesticide Factsheets

legal agreement about the B. F. Goodrich Superfund Site Calvert City, Marshall County, Kentucky between EPA and Goodrich Corporation, PolyOne Corporation, and Westlake Vinyls, Inc. Region ID: 04 DocID: 10453129, DocDate: 12-09-2009

Plasticizers derived from cardanol: Synthesis and plasticization properties for poly(vinyl chloride)

USDA-ARS?s Scientific Manuscript database

Two natural plasticizers derived from cardanol, cardanol acetate (CA), and epoxidized cardanol acetate (ECA), were synthesized and characterized by 1H NMR and 13C NMR. The plasticizing effects of the obtained plasticizers on semi-rigid polyvinyl chloride (PVC) formulations were also investigated. Tw...

Synthesis and application of a natural plasticizer based on cardanol for poly(vinyl chloride)

USDA-ARS?s Scientific Manuscript database

A natural plasticizer with multifunctional groups, similar in structure to phthalates, cardanol derivatives glycidyl ether (CGE) was synthesized from cardanol by a two-step modification process and characterized by FT-IR, 1-HNMR, and 13-CNMR. The resulting product was incorporated to PVC (CGE/PVC), ...

Hybrid composite based on poly(vinyl alcohol) and fillers from renewable resources

USDA-ARS?s Scientific Manuscript database

Hybrid composite laminates consisting of polyvinyl alcohol (PVA) as continuous phase (33% by weight) and lignocellulosic fillers, derived from sugarcane bagasse, apple and orange waste (22% by weight) were molded in a carver press in the presence of water and glycerol such as platicizers agents. Cor...

Composite Pyroelectric Materials.

DTIC Science & Technology

1979-06-30

in hydtochloric acid .. The wax negative is reinvested with a PZT slip (43 volume% PZT, 53% 1120, 4% poly (vinyl alcohol)). Ultrasonics PZT-501A with an...Laboratory are also acknowledged with gratitude. This work was sponsored by the Department of Defense through contracts N00014-78-C-0291 and HDA 903-78

Using Greener Gels to Explore Rheology

ERIC Educational Resources Information Center

Garrett, Brendan; Matharu, Avtar S.; Hurst, Glenn A.

2017-01-01

A laboratory experiment was developed to investigate the rheological properties of a green calcium-cross-linked alginate gel as an alternative to the traditional borax-cross-linked poly(vinyl alcohol) gel. As borax is suspected of damaging fertility and the unborn child, a safe, green alternative is necessary. The rheological properties of a…

How to Learn and Have Fun with Poly(Vinyl Alcohol) and White Glue.

ERIC Educational Resources Information Center

de Zea Bermudez, V.; Passos de Almeida, P.; Feria Seita, J.

1998-01-01

Presents a classroom guide for a simple theoretical approach to the study of certain fluids. Discusses background information, followed by experimental procedures for the preparation of two popular viscoelastic materials ("Slime" and "Silly Putty") that exhibit unusual flow properties. Also lists student discussion questions…

Effect of natural and synthetic organics on the processing of ceramics

NASA Astrophysics Data System (ADS)

Schulz, Brett M.

Dry pressing has been shown to be an efficient and cost effective method of manufacturing ceramic ware. Dry pressed parts are typically manufactured with a low moisture content which has the further advantage of eliminating the drying step that is necessary for plastic formed ware, i.e., jiggered or ram pressed. Problems associated with the use of dry pressing in an industrial setting involve the high loss rate during the bisque firing process and the poor surface finish of the green (unfired) ware. It was the goal of this research to improve the surface finish of dry pressed ware to a level that is satisfactory for decorating of the bisque fired ware. The adsorption of organic additives, specifically dispersants, on the surface of particles is an important aspect of ceramic processing. The interactions between organic additives, specifically sodium poly[acrylic acid] and poly[vinyl alcohol], have been demonstrated to result in phase separation into distinct domains during the spray-drying process. This phase separation leads to a poly[vinyl alcohol]-rich film on the surface of the granulate which will increase the P1 value, the pressure at the onset of granule deformation, of the granulate. This negative interaction between the organics increases the surface roughness of the dry pressed ware. The roughness of the industrially prepared ware was determined using an optical interferometer to set a baseline for improvements in the surface finish of the dry pressed ware. Blending of dried granulate was determined to significantly improve the surface finish of the ware. Alternative binders to replace a plasticized poly[vinyl alcohol] were observed to show improvements in the surface finish of the ware dry pressed in a semi-isostatic die. In summary the most important aspect to improving the surface finish of dry pressed ware, i.e. facilitating compaction, is the selection of the organic additives. Additives which are observed to have a negative interaction, i.e. to phase separate into distinct domains, will result in an organic rich film at the surface of the granule thus increasing the P1 value of the granulate.

A composite hydrogels-based photonic crystal multi-sensor

NASA Astrophysics Data System (ADS)

Chen, Cheng; Zhu, Zhigang; Zhu, Xiangrong; Yu, Wei; Liu, Mingju; Ge, Qiaoqiao; Shih, Wei-Heng

2015-04-01

A facile route to prepare stimuli-sensitive poly(vinyl alcohol)/poly(acrylic acid) (PVA/PAA) gelated crystalline colloidal array photonic crystal material was developed. PVA was physically gelated by utilizing an ethanol-assisted method, the resulting hydrogel/crystal composite film was then functionalized with PAA to form an interpenetrating hydrogel film. This sensor film is able to efficiently diffract the visible light and rapidly respond to various environmental stimuli such as solvent, pH and strain, and the accompanying structural color shift can be repeatedly changed and easily distinguished by naked eye.

A novel nonenzymatic amperometric hydrogen peroxide sensor based on CuO@Cu2O nanowires embedded into poly(vinyl alcohol).

PubMed

Chirizzi, Daniela; Guascito, Maria Rachele; Filippo, Emanuela; Tepore, Antonio

2016-01-15

A new, very simple, rapid and inexpensive nonenzymatic amperometric sensor for hydrogen peroxide (H2O2) detection is proposed. It is based on the immobilization of cupric/cuprous oxide core shell nanowires (CuO@Cu2O-NWs) in a poly(vinyl alcohol) (PVA) matrix directly drop casted on a glassy carbon electrode surface to make a CuO@Cu2O core shell like NWs PVA embedded (CuO@Cu2O-NWs/PVA) sensor. CuO nanowires with mean diameters of 120-170nm and length in the range 2-5μm were grown by a simple catalyst-free thermal oxidation process based on resistive heating of pure copper wires at ambient conditions. The oxidation process of the copper wire surface led to the formation of a three layered structure: a thick Cu2O bottom layer, a CuO thin intermediate layer and CuO nanowires. CuO nanowires were carefully scratched from Cu2O layer with a sharp knife, dispersed into ethanol and sonicated. Then, the NWs were embedded in PVA matrix. The morphological and spectroscopic characterization of synthesized CuO-NWs and CuO@Cu2O-NWs/PVA were performed by transmission electron microscopy (TEM), selected area diffraction pattern (SAD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) analysis. Moreover a complete electrochemical characterization of these new CuO@Cu2O-NWs/PVA modified glassy carbon electrodes was performed by Cyclic Voltammetry (CV) and Cronoamperometry (CA) in phosphate buffer (pH=7; I=0.2) to investigate the sensing properties of this material against H2O2. The electrochemical performances of proposed sensors as high sensitivity, fast response, reproducibility and selectivity make them suitable for the quantitative determination of hydrogen peroxide substrate in batch analysis. Copyright © 2015 Elsevier B.V. All rights reserved.

Artificial Polymeric Scaffolds as Extracellular Matrix Substitutes for Autologous Conjunctival Goblet Cell Expansion

PubMed Central

He, Min; Storr-Paulsen, Thomas; Wang, Annie L.; Ghezzi, Chiara E.; Wang, Siran; Fullana, Matthew; Karamichos, Dimitrios; Utheim, Tor P.; Islam, Rakibul; Griffith, May; Islam, M. Mirazul; Hodges, Robin R.; Wnek, Gary E.; Kaplan, David L.; Dartt, Darlene A.

2016-01-01

Purpose We fabricated and investigated polymeric scaffolds that can substitute for the conjunctival extracellular matrix to provide a substrate for autologous expansion of human conjunctival goblet cells in culture. Methods We fabricated two hydrogels and two silk films: (1) recombinant human collagen (RHC) hydrogel, (2) recombinant human collagen 2-methacryloylxyethyl phosphorylcholine (RHC-MPC) hydrogel, (3) arginine-glycine-aspartic acid (RGD) modified silk, and (4) poly-D-lysine (PDL) coated silk, and four electrospun scaffolds: (1) collagen, (2) poly(acrylic acid) (PAA), (3) poly(caprolactone) (PCL), and (4) poly(vinyl alcohol) (PVA). Coverslips and polyethylene terephthalate (PET) were used for comparison. Human conjunctival explants were cultured on scaffolds for 9 to 15 days. Cell viability, outgrowth area, and the percentage of cells expressing markers for stratified squamous epithelial cells (cytokeratin 4) and goblet cells (cytokeratin 7) were determined. Results Most of cells grown on all scaffolds were viable except for PCL in which only 3.6 ± 2.2% of the cells were viable. No cells attached to PVA scaffold. The outgrowth was greatest on PDL-silk and PET. Outgrowth was smallest on PCL. All cells were CK7-positive on RHC-MPC while 84.7 ± 6.9% of cells expressed CK7 on PDL-silk. For PCL, 87.10 ± 3.17% of cells were CK7-positive compared to PET where 67.10 ± 12.08% of cells were CK7-positive cells. Conclusions Biopolymer substrates in the form of hydrogels and silk films provided for better adherence, proliferation, and differentiation than the electrospun scaffolds and could be used for conjunctival goblet cell expansion for eventual transplantation once undifferentiated and stratified squamous cells are included. Useful polymer scaffold design characteristics have emerged from this study. PMID:27832279

Artificial Polymeric Scaffolds as Extracellular Matrix Substitutes for Autologous Conjunctival Goblet Cell Expansion.

PubMed

He, Min; Storr-Paulsen, Thomas; Wang, Annie L; Ghezzi, Chiara E; Wang, Siran; Fullana, Matthew; Karamichos, Dimitrios; Utheim, Tor P; Islam, Rakibul; Griffith, May; Islam, M Mirazul; Hodges, Robin R; Wnek, Gary E; Kaplan, David L; Dartt, Darlene A

2016-11-01

We fabricated and investigated polymeric scaffolds that can substitute for the conjunctival extracellular matrix to provide a substrate for autologous expansion of human conjunctival goblet cells in culture. We fabricated two hydrogels and two silk films: (1) recombinant human collagen (RHC) hydrogel, (2) recombinant human collagen 2-methacryloylxyethyl phosphorylcholine (RHC-MPC) hydrogel, (3) arginine-glycine-aspartic acid (RGD) modified silk, and (4) poly-D-lysine (PDL) coated silk, and four electrospun scaffolds: (1) collagen, (2) poly(acrylic acid) (PAA), (3) poly(caprolactone) (PCL), and (4) poly(vinyl alcohol) (PVA). Coverslips and polyethylene terephthalate (PET) were used for comparison. Human conjunctival explants were cultured on scaffolds for 9 to 15 days. Cell viability, outgrowth area, and the percentage of cells expressing markers for stratified squamous epithelial cells (cytokeratin 4) and goblet cells (cytokeratin 7) were determined. Most of cells grown on all scaffolds were viable except for PCL in which only 3.6 ± 2.2% of the cells were viable. No cells attached to PVA scaffold. The outgrowth was greatest on PDL-silk and PET. Outgrowth was smallest on PCL. All cells were CK7-positive on RHC-MPC while 84.7 ± 6.9% of cells expressed CK7 on PDL-silk. For PCL, 87.10 ± 3.17% of cells were CK7-positive compared to PET where 67.10 ± 12.08% of cells were CK7-positive cells. Biopolymer substrates in the form of hydrogels and silk films provided for better adherence, proliferation, and differentiation than the electrospun scaffolds and could be used for conjunctival goblet cell expansion for eventual transplantation once undifferentiated and stratified squamous cells are included. Useful polymer scaffold design characteristics have emerged from this study.

Polymeric ionic liquid modified graphene oxide-grafted silica for solid-phase extraction to analyze the excretion-dynamics of flavonoids in urine by Box-Behnken statistical design.

PubMed

Hou, Xiudan; Liu, Shujuan; Zhou, Panpan; Li, Jin; Liu, Xia; Wang, Licheng; Guo, Yong

2016-07-22

A solid-phase extraction method for the efficient analysis of the excretion-dynamics of flavonoids in urine was established and described. In this work, in situ surface radical chain-transfer polymerization and in situ anion exchange were utilized to tune the extraction performance of poly(1-vinyl-3-hexylimidazolium bromide)-graphene oxide-grafted silica (poly(VHIm(+)Br(-))@GO@Sil). Graphene oxide (GO) was first coated onto the silica using a layer-by-layer fabrication method, and then the anion of poly(VHIm(+)Br(-))@GO@Sil was changed into hexafluorophosphate (PF6(-)) by in situ anion exchange. The interaction energies between two PILs and four flavonoids were calculated with the Gaussian09 suite of programs. A Box-Behnken design was used for the optimization of four greatly influential parameters after single-factor experiments to obtain more accurate and precise results. Coupled to high performance liquid chromatography, the poly(VHIm(+)PF6(-))@GO@Sil method showed acceptable extraction recoveries for the four flavonoids, with limits of detection in the range of 0.1-0.5μgL(-1), and wide linear ranges with correlation coefficients (R) ranging from 0.9935 to 0.9987. Under the optimum conditions, the proposed method was applied to analyze the urines collected from a healthy volunteer. The excretion amount-time profiles revealed that 4-15h was the main excretion time for the detected flavonoids. The results indicated that the newly developed method offered the advantages of being feasible, green and cost-effective, and could be successfully applied to the extraction and enrichment of flavonoids in human body systems allowing the study of the metabolic kinetics. Copyright © 2016. Published by Elsevier B.V.

Bis(trifluoromethanesulfonyl)imide-based ionic liquids grafted on graphene oxide-coated solid-phase microextraction fiber for extraction and enrichment of polycyclic aromatic hydrocarbons in potatoes and phthalate esters in food-wrap.

PubMed

Hou, Xiudan; Guo, Yong; Liang, Xiaojing; Wang, Xusheng; Wang, Lei; Wang, Licheng; Liu, Xia

2016-06-01

A class of novel, environmental friendly ionic liquids (ILs) were synthesized by on-fiber preparation strategy and modified on graphene oxide (GO)-coated stainless steel wire, which was used as a solid-phase microextraction (SPME) fiber for efficient enrichment of polycyclic aromatic hydrocarbons (PAHs) and phthalate esters (PAEs). Surface characteristic of the ILs and polymeric-ILs (PILs) fibers with the wave-structure were inspected by scanning electron microscope. The successfully synthesis of bis(trifluoromethanesulfonyl)imide (NTf2(-))-based ILs were also characterized by energy dispersive spectrometer analysis. Through the chromatograms of the proposed two ILs (1-aminoethyl-3-methylimidazolium bromide (C2NH2MIm(+)Br(-)), C2NH2MIm(+)NTf2(-)) and two PILs (polymeric 1-vinyl-3-hexylimidazolium bromide (poly(VHIm(+)Br(-))), poly(VHIm(+)NTf2(-)))-GO-coated fibers for the extraction of analytes, NTf2(-)-based PIL demonstrated higher extraction capacity for hydrophobic compounds than other as-prepared ILs. Analytical performances of the proposed fibers were investigated under the optimized extraction and desorption conditions coupled with gas chromatography (GC). Compared with the poly(VHIm(+)Br(-))-GO fiber, the poly(VHIm(+)NTf2(-))-GO SPME fiber brought wider linear ranges for analytes with correlation coefficient in the range of 0.9852-0.9989 and lower limits of detection ranging from 0.015-0.025μgL(-1). The obtained results indicated that the newly prepared PILs-GO coating was a feasible, selective and green microextraction medium, which could be suitable for extraction and determination of PAHs and PAEs in potatoes and food-wrap sample, respectively. Copyright © 2016 Elsevier B.V. All rights reserved.

Bioorthogonal Metabolic DNA Labelling using Vinyl Thioether-Modified Thymidine and o-Quinolinone Quinone Methide.

PubMed

Gubu, Amu; Li, Long; Ning, Yan; Zhang, Xiaoyun; Lee, Seonghyun; Feng, Mengke; Li, Qiang; Lei, Xiaoguang; Jo, Kyubong; Tang, Xinjing

2018-04-17

Bioorthogonal metabolic DNA labeling with fluorochromes is a powerful strategy to visualize DNA molecules and their functions. Here, we report the development of a new DNA metabolic labeling strategy enabled by the catalyst-free bioorthogonal ligation using vinyl thioether modified thymidine and o-quinolinone quinone methide. With the newly designed vinyl thioether-modified thymidine (VTdT), we added labeling tags on cellular DNA, which could further be linked to fluorochromes in cells. Therefore, we successfully visualized the DNA localization within cells as well as single DNA molecules without other staining reagents. In addition, we further characterized this bioorthogonal DNA metabolic labeling using DNase I digestion, MS characterization of VTdT as well as VTdT-oQQF conjugate in cell nuclei or mitochondria. This technique provides a powerful strategy to study DNA in cells, which paves the way to achieve future spatiotemporal deciphering of DNA synthesis and functions. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

An Extraordinary Sulfonated-Graphenal-Polymer-Based Electrolyte Separator for All-Solid-State Supercapacitors.

PubMed

Liu, Xubo; Men, Chuanling; Zhang, Xiaohua; Li, Qingwen

2016-09-01

Sulfonated graphenal polymers can be assembled up by poly(vinyl alcohol) adhesion. The porous assembly structure results in a remarkably improved ionic conductivity and thus enhances electrochemical performances such as specific capacitance, capacitance retention, and cycling stability. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

SPECIATION OF ORGANOTINS IN POLY VINYL CHLORIDE PIPE VIA X-RAY ABSORPTION SPECTROSCOPY AND IN LEACHATES USING GC-PFPD AFTER DERIVATISATION

EPA Science Inventory

Three different polyvinyl chloride (PVC) pipe types were subjected to de–ionized water exposures over the course of at least 180 days. Water exposed to the pipe was analyzed for organotin speciation and concentration. Organotin concentrations were the highest during the fir...

Reversible Addition Fragmentation Chain Transfer (RAFT) Polymerization in Undergraduate Polymer Science Lab

ERIC Educational Resources Information Center

Nguyen, T. L. U.; Bennet, Francesca; Stenzel, Martina H.; Barner-Kowollik, Christopher

2008-01-01

This 8-hour experiment (spread over two 4-hour sessions) is designed to equip students with essential skills in polymer synthesis, particularly in synthesizing polymers of well-defined molecular weight. The experiment involves the synthesis and characterization of poly(vinyl neodecanoate) via living free radical polymerization, specifically the…

Modification of Poly(vinyl butyral) Coatings Using Bis-silanes (Postprint)

DTIC Science & Technology

2010-04-01

parent coating to 2-chloroethyl ethyl sulfide (2-CEES), dimethyl methylphosphonate (DMMP), diisopropyl methylphosphonate, and methyl salicylate ; the...methylphosphonate (DMMP), diisopropyl methylphos- phonate, and methyl salicylate ; the most significant reduction was observed for 2-CEES and DMMP at...dimethyl methylphosphonate (DMMP), diisopropyl methylphosphonate (DIMP), dibutyltin dilaurate (DBTDL), and methyl salicylate (MS)wereobtained

Lignin-Based Electrospun Nanofibers Reinforced with Cellulose Nanocrystals

Treesearch

Mariko Ago; Kunihiko Okajima; Joseph E. Jakes; Park Sunkyu; Orlando J. Rojas

2012-01-01

Lignin-based fibers were produced by electrospinning aqueous dispersions of lignin, poly(vinyl alcohol) (PVA), and cellulose nanocrystals (CNCs). Defect-free nanofibers with up to 90 wt % lignin and 15% CNCs were achieved. The properties of the aqueous dispersions, including viscosity, electrical conductivity, and surface tension, were examined and correlated to the...

Radical graft polymerization of an Allyl Monomer onto Hydrophilic Polymers and their antibacterial nanofibrous membranes

USDA-ARS?s Scientific Manuscript database

Hydrophilic poly (vinyl alcohol-co-ethylene) (PVA-co-PE) copolymers with 27 mol %, 32 mol % and 44 mol % ethylene were functionalized by melt radical graft copolymerization with 2,4-diamino-6-diallylamino-1,3,5-triazine (NDAM) using reactive extrusion. This functionalization imparts antibacterial pr...

Thermal behavior of epoxidized cardanol diethyl phosphate as novel renewable plasticizer for poly(vinyl chloride)

USDA-ARS?s Scientific Manuscript database

A novel plasticizer, epoxidized cardanol diethyl phosphate (ECEP), based on cardanol was synthesized. Chemical structure of ECEP was characterized by fourier transform infrared (FTIR), 1H-nuclear magnetic resonance(1H NMR) and 13C-nuclear magnetic resonance(13C NMR) spectroscopy. Effects of ECEP sub...

Morphological influence of cellulose nanoparticles (CNs) from cottonseed hulls on rheological properties of polyvinyl alcohol/CN suspensions

USDA-ARS?s Scientific Manuscript database

This work aims to extract and characterize fibrous, rod-like and spherical cellulose nanoparticles (CNs) from cottonseed hull and to investigate the structure-morphology-rheology relationships. The rheological behavior of poly(vinyl alcohol) (PVA)/CNs suspensions was also examined to guide the solve...

SPECIATION OF ORGANOTINS IN POLY VINYL PIPE VIA X-RAY ABSORPTION SPECTROSCOPY AND IN LEACHATES BY ELTHYLATION/DERIVITIZATION

EPA Science Inventory

Three different polyvinyl chloride (PVC) pipe types were subjected to de-ionized water exposures over the course of at least 180 days. Water exposed to the pipe was analyzed for organotin speciation and concentration. Organotin concentrations were the highest during the first 1-5...

Visualizing Fluorescence: Using a Homemade Fluorescence "Microscope" to View Latent Fingerprints on Paper

ERIC Educational Resources Information Center

LaFratta, Christopher N.; Huh, Sun Phill; Mallillin, Allistair C.; Riviello, Peter J.; Walt, David R.

2010-01-01

We describe an inexpensive hand-held fluorescence imager (low-magnification microscope), constructed from poly(vinyl chloride) pipe and other inexpensive components for use as a teaching tool to understand the principles of fluorescence detection. Optical filters are used to select the excitation and emission wavelengths and can be easily…

PREPARATION OF NOVEL METALLIC AND BIMETALLIC CROSS-LINKED POLY (VINYL ALCOHOL) NANOCOMPOSITES UNDER MICROWAVE IRRADIATION

EPA Science Inventory

A facile method utilizing microwave irradiation is described that accomplishes the cross-linking reaction of PVA with metallic and bimetallic systems. Nanocomposites of PVA-cross-linked metallic systems such as Pt, Cu, and In and bimetallic systems such as Pt-In, Ag-Pt, Pt-Fe, Cu...

Synthesizing and Playing with Magnetic Nanoparticles: A Comprehensive Approach to Amazing Magnetic Materials

ERIC Educational Resources Information Center

Dalverny, Anne-Laure; Leyral, Géraldine; Rouessac, Florence; Bernaud, Laurent; Filhol, Jean-Sébastien

2018-01-01

Magnetic iron oxide nanoparticles were synthesized and stabilized using ammonium cations or poly(vinyl alcohol) to produce amazing materials such as safer aqueous ferrofluids, ferrogels, ferromagnetic inks, plastics, and nanopowders illustrating how versatile materials can be produced just by simple modifications. The synthesis is fast, reliable,…

Surface restructuring behavior of various types of poly(dimethylsiloxane) in water detected by SFG.

PubMed

Chen, Chunyan; Wang, Jie; Chen, Zhan

2004-11-09

Surface structures of several different poly(dimethylsiloxane) (PDMS) materials, tetraethoxysilane-cured hydroxy-terminated PDMS (TEOS-PDMS), platinum-cured vinyl-terminated PDMS (Pt-PDMS), platinum-cured vinyl-terminated poly(diphenylsiloxane)-co-poly(dimethylsiloxane) (PDPS-co-PDMS), and PDMS-co-polystyrene (PDMS-co-PS) copolymer in air and water have been investigated by sum frequency generation (SFG) vibrational spectroscopy. The SFG spectra collected from all PDMS surfaces in both air and water are dominated by methyl group stretches, indicating that all the surfaces are mainly covered by methyl groups. Other than surface-dominating methyl groups, some -Si-CH2-CH2- moieties on the Pt-PDMS surface have also been detected in air, which are present at cross-linking points. Information about the average orientation angle and angle distribution of the methyl groups on the PDMS surface has been evaluated. Surface restructuring of the methyl groups has been observed for all PDMS surfaces in water. Upon contacting water, the methyl groups on all PDMS surfaces tilt more toward the surface. The detailed restructuring behaviors of several PDMS surfaces in water and the effects of molecular weight on restructuring behaviors have been investigated. For comparison, in addition to air and water, surface structures of PDMS materials mentioned above in a nonpolar solvent, FC-75, have also been studied. By comparing the different response of phenyl groups to water on both PDPS-co-PDMS and PS-co-PDMS surfaces, we have demonstrated how the restructuring behaviors of surface phenyl groups are affected by the structural flexibility of the molecular chains where they are attached.

Definition and validation of operating equations for poly(vinyl alcohol)-poly(lactide-co-glycolide) microfiltration membrane-scaffold bioreactors

PubMed Central

Shipley, RJ; Waters, SL; Ellis, MJ

2010-01-01

The aim of this work is to provide operating data for biodegradable hollow fiber membrane bioreactors. The physicochemical cell culture environment can be controlled with the permeate flowrate, so this aim necessitates the provision of operating equations that enable end-users to set the pressures and feed flowrates to obtain their desired culture environment. In this paper, theoretical expressions for the pure water retentate and permeate flowrates, derived using lubrication theory, are compared against experimental data for a single fiber poly(vinyl alcohol)–poly(lactide-co-glycolide) crossflow module to give values for the membrane permeability and slip. Analysis of the width of the boundary layer region where slip effects are important, together with the sensitivity of the retentate and permeate equations to the slip parameter, show that slip is insignificant for these membranes, which have a mean pore diameter of 1.1 µm. The experimental data is used to determine a membrane permeability, of k = 1.86 × 10−16 m2, and to validate the model. It was concluded that the operating equation that relates the permeate to feed ratio, c, lumen inlet flowrate, Ql,in, lumen outlet pressure, P1, and ECS outlet pressure, P0, is1 where A and B are constants that depend on the membrane permeability and geometry (and are given explicitly). Finally, two worked examples are presented to demonstrate how a tissue engineer can use Equation 1 to specify operating conditions for their bioreactor. PMID:20641054

Effects of poly(2-hydroxyethyl methacrylate) and poly(vinyl-pyrrolidone) hydrogel implants on myopic and normal chick sclera

PubMed Central

Su, James; Iomdina, Elena; Tarutta, Elena; Ward, Brian; Song, Jie; Wildsoet, Christine F.

2008-01-01

There has been generally little attention paid to the utilization of biomaterials as an anti-myopia treatment. The purpose of this study was to investigate whether polymeric hydrogels, either implanted or injected adjacent to the outer scleral surface, slow ocular elongation. White Leghorn (gallus gallus domesticus) chicks were used at 2 weeks of age. Chicks had either (1) strip of poly(2-hydroxyethyl methacrylate) (pHEMA) implanted monocularly against the outer sclera at the posterior pole, or (2) an in situ polymerizing gel [main ingredient: poly(vinyl-pyrrolidone) (PVP)] injected monocularly at the same location. Some of the eyes injected with the polymer were fitted with a diffuser or a −10D lens. In each experiment, ocular lengths were measured at regular intervals by high frequency A-scan ultrasonography, and chicks were sacrificed for histology at staged intervals. No in vivo signs of either orbital or ocular inflammation were observed. The pHEMA implant significantly increased scleral thickness by the third week, and the implant became encapsulated with fibrous tissue. The PVP-injected eyes left otherwise untreated, showed a significant increase in scleral thickness, due to increased chondrocyte proliferation and extracellular matrix deposition. However, there was no effect of the PVP injection on ocular elongation. In eyes wearing optical devices, there was no effect on either scleral thickness or ocular elongation. These results represent “proof of principle” that scleral growth can be manipulated without adverse inflammatory responses. However, since neither approach slowed ocular elongation, additional factors must influence scleral surface area expansion in the avian eye. PMID:19109950

Definition and validation of operating equations for poly(vinyl alcohol)-poly(lactide-co-glycolide) microfiltration membrane-scaffold bioreactors.

PubMed

Shipley, R J; Waters, S L; Ellis, M J

2010-10-01

The aim of this work is to provide operating data for biodegradable hollow fiber membrane bioreactors. The physicochemical cell culture environment can be controlled with the permeate flowrate, so this aim necessitates the provision of operating equations that enable end-users to set the pressures and feed flowrates to obtain their desired culture environment. In this paper, theoretical expressions for the pure water retentate and permeate flowrates, derived using lubrication theory, are compared against experimental data for a single fiber poly(vinyl alcohol)-poly(lactide-co-glycolide) crossflow module to give values for the membrane permeability and slip. Analysis of the width of the boundary layer region where slip effects are important, together with the sensitivity of the retentate and permeate equations to the slip parameter, show that slip is insignificant for these membranes, which have a mean pore diameter of 1.1 microm. The experimental data is used to determine a membrane permeability, of k = 1.86 x 10(-16) m(2), and to validate the model. It was concluded that the operating equation that relates the permeate to feed ratio, c, lumen inlet flowrate, Q (l,in), lumen outlet pressure, P (1), and ECS outlet pressure, P (0), is P(1) - P(0) = Q(l),in (Ac + B) where A and B are constants that depend on the membrane permeability and geometry (and are given explicitly). Finally, two worked examples are presented to demonstrate how a tissue engineer can use Equation (1) to specify operating conditions for their bioreactor.

Carbon nanotube/poly(ethylene-co-vinyl acetate) composite electrode for capillary electrophoretic determination of esculin and esculetin in Cortex Fraxini.

PubMed

Chen, Zhi; Zhang, Luyan; Chen, Gang

2009-10-01

In this report, a novel carbon nanotube/poly(ethylene-co-vinyl acetate) (CNT/EVA) composite electrode was developed for the amperometric detection in CE. The composite electrode was fabricated by packing a mixture of CNTs and melted EVA in a piece of fused-silica capillary under heat. It was coupled with CE for the separation and detection of esculin and esculetin in Cortex Fraxini, a traditional Chinese medicine, to demonstrate its feasibility and performance. Esculin and esculetin have been well separated within 9 min in a 40 cm long capillary at a separation voltage of 12 kV using a 50 mM borate buffer (pH 9.2). The new CNT-based CE detector offered significantly lower detection potentials, yielded enhanced S/N characteristics, and exhibited high resistance to surface fouling and enhanced stability. It showed long-term stability and reproducibility with relative standard deviations of less than 5% for the peak current (n=15) and should also find a wide range of applications in other microfluidic analysis systems.

Water-insoluble sericin/β-cyclodextrin/PVA composite electrospun nanofibers as effective adsorbents towards methylene blue.

PubMed

Zhao, Rui; Wang, Yong; Li, Xiang; Sun, Bolun; Jiang, Ziqiao; Wang, Ce

2015-12-01

A novel water-insoluble sericin/β-cyclodextrin/poly (vinyl alcohol) composite nanofiber adsorbent was prepared by electrospinning and followed by thermal crosslinking for removal of cationic dye methylene blue from aqueous solution. Fourier transform infrared spectroscopy and solubility experiments confirmed that sericin and β-cyclodextrin were incorporated into the nanofibers and the crosslinking reaction occurred successfully. Kinetics, isotherms and thermodynamics analysis were studied for adsorption of methylene blue. The adsorption process is better fitted with the pseudo-second-order model and Langmuir isotherm model. The maximum adsorption capacities are 187.97, 229.89, and 261.10mg/g at the temperatures 293, 313 and 333 K, respectively. Thermodynamic parameters showed that methylene blue adsorption was endothermic and spontaneous. In addition, the fiber membrane adsorbent could be easily separated from dye solution and showed high recyclable removal efficiency. All these results suggest that crosslinked sericin/β-cyclodextrin/poly(vinyl alcohol) composite nanofibers could be potential recyclable adsorbents in dye wastewater treatment. Copyright © 2015 Elsevier B.V. All rights reserved.

Acoustic Behavior of Subfloor Lightweight Mortars Containing Micronized Poly (Ethylene Vinyl Acetate) (EVA)

PubMed Central

Brancher, Luiza R.; Nunes, Maria Fernanda de O.; Grisa, Ana Maria C.; Pagnussat, Daniel T.; Zeni, Mára

2016-01-01

This paper aims to contribute to acoustical comfort in buildings by presenting a study about the polymer waste micronized poly (ethylene vinyl acetate) (EVA) to be used in mortars for impact sound insulation in subfloor systems. The evaluation method included physical, mechanical and morphological properties of the mortar developed with three distinct thicknesses designs (3, 5, and 7 cm) with replacement percentage of the natural aggregate by 10%, 25%, and 50% EVA. Microscopy analysis showed the surface deposition of cement on EVA, with preservation of polymer porosity. The compressive creep test estimated long-term deformation, where the 10% EVA sample with a 7 cm thick mortar showed the lowest percentage deformation of its height. The impact noise test was performed with 50% EVA samples, reaching an impact sound insulation of 23 dB when the uncovered slab was compared with the 7 cm thick subfloor mortar. Polymer waste addition decreased the mortar compressive strength, and EVA displayed characteristics of an influential material to intensify other features of the composite. PMID:28787851

Aluminum–phthalocyanine chloride associated to poly(methyl vinyl ether-co-maleic anhydride) nanoparticles as a new third-generation photosensitizer for anticancer photodynamic therapy

PubMed Central

Muehlmann, Luis Alexandre; Ma, Beatriz Chiyin; Longo, João Paulo Figueiró; Almeida Santos, Maria de Fátima Menezes; Azevedo, Ricardo Bentes

2014-01-01

Photodynamic therapy is generally considered to be safer than conventional anticancer therapies, and it is effective against different kinds of cancer. However, its clinical application has been significantly limited by the hydrophobicity of photosensitizers. In this work, a system composed of the hydrophobic photosensitizer aluminum–phthalocyanine chloride (AlPc) associated with water dispersible poly(methyl vinyl ether-co-maleic anhydride) nanoparticles is described. AlPc was associated with nanoparticles produced by a method of solvent displacement. This system was analyzed for its physicochemical characteristics, and for its photodynamic activity in vitro in cancerous (murine mammary carcinoma cell lineage 4T1, and human mammary adenocarcinoma cells MCF-7) and noncancerous (murine fibroblast cell lineage NIH/3T3, and human mammary epithelial cell lineage MCF-10A) cell lines. Cell viability and the elicited mechanisms of cell death were evaluated after the application of photodynamic therapy. This system showed improved photophysical and photochemical properties in aqueous media in comparison to the free photosensitizer, and it was effective against cancerous cells in vitro. PMID:24634582

Preparation and electrical-property characterization of poly(vinyl chloride)-derived carbon nanosheet by ion beam irradiation-induced carbon clustering and carbonization

NASA Astrophysics Data System (ADS)

Jung, Chan-Hee; Sohn, Joon-Yong; Kim, Hyo-Sub; Hwang, In-Tae; Lee, Hong-Joon; Shin, Junhwa; Choi, Jae-Hak

2018-05-01

In this work, we demonstrated that carbon nanosheet (CNS) can easily be produced by a room-temperature, solid-state proton irradiation-induced clustering of poly(vinyl chloride) (PVC) films followed by carbonization. The results of the optical, chemical, and structural analyses revealed that oxidized and sp2-hybridized carbon clusters were effectively created in the PVC thin film by combined dehydrochlorination and inter-coupling reactions during proton irradiation. This was further converted to pseudo-hexagonally-structured nano-crystalline CNS with 2-D symmetry and metallic transporting character by high-temperature treatment. As a result, the CNS exhibited a very high electrical conductivity (587 S/cm) without a significant change in their thickness, a low surface roughness (0.36 nm), and a high work function (5.11 eV). These findings demonstrate that the radiation-based approach opens new avenues for the design and development of 2-D CNS as a graphene allotrope for the application of electronic devices, including field-effect transistors, electric heating devices, biosensors, supercapacitors, and fuel cells.

A poly(vinyl alcohol)/sodium alginate blend monolith with nanoscale porous structure

PubMed Central

2013-01-01

A stimuli-responsive poly(vinyl alcohol) (PVA)/sodium alginate (SA) blend monolith with nanoscale porous (mesoporous) structure is successfully fabricated by thermally impacted non-solvent induced phase separation (TINIPS) method. The PVA/SA blend monolith with different SA contents is conveniently fabricated in an aqueous methanol without any templates. The solvent suitable for the fabrication of the present blend monolith by TINIPS is different with that of the PVA monolith. The nanostructural control of the blend monolith is readily achieved by optimizing the fabrication conditions. Brunauer Emmett Teller measurement shows that the obtained blend monolith has a large surface area. Pore size distribution plot for the blend monolith obtained by the non-local density functional theory method reveals the existence of the nanoscale porous structure. Fourier transform infrared analysis reveals the strong interactions between PVA and SA. The pH-responsive property of the blend monolith is investigated on the basis of swelling ratio in different pH solutions. The present blend monolith of biocompatible and biodegradable PVA and SA with nanoscale porous structure has large potential for applications in biomedical and environmental fields. PMID:24093494

Poly(vinyl alcohol) films reinforced with nanofibrillated cellulose (NFC) isolated from corn husk by high intensity ultrasonication.

PubMed

Xiao, Shaoliang; Gao, Runan; Gao, LiKun; Li, Jian

2016-01-20

This work was aimed at fabricating and characterizing poly(vinyl alcohol) films that were reinforced by nanofibrillated corn husk celluloses using a combination of chemical pretreatments and ultrasonication. The obtained nanofibrillated celluloses (NFCs) possessed a narrow width ranging from 50 to 250 nm and a high aspect ratio (394). The crystalline type of NFC was cellulose I type. Compared with the original corn husks, the NCF crystallinity and thermal stability increased due to the removal of the hemicelluloses and lignin. PVA films containing different NFC concentrations (0.5%, 1%, 3%, 5%, 7% and 9%, w/w, dry basis) were examined. The 1% PVA/NFC reinforced films exhibited a highly visible light transmittance of 80%, and its tensile strength and the tensile strain at break were increased by 1.47 and 1.80 times compared to that of the pure PVA film, respectively. The NFC with high aspect ratio and high crystallinity is beneficial to the improvement of the mechanical strength and thermal stability. Copyright © 2015 Elsevier Ltd. All rights reserved.

Influence of natural and synthetic crosslinking reagents on the structural and mechanical properties of chitosan-based hybrid hydrogels.

PubMed

Garnica-Palafox, I M; Sánchez-Arévalo, F M

2016-10-20

The objective of this work was to correlate the physical and chemical properties of chitosan/poly(vinyl alcohol)/genipin (CS/PVA/GEN) and chitosan/poly(vinyl alcohol)/glutaraldehyde (CS/PVA/GA) hydrogels with their structural and mechanical responses. In addition, their molecular structures were determined and confirmed using FTIR spectroscopy. The results indicated that the hybrid hydrogels crosslinked with genipin showed similar crystallinity, thermal properties, elongation ratio and structural parameters as those crosslinked with glutaraldehyde. However, it was found that the elastic moduli of the two hybrid hydrogels were slightly different: 2.82±0.33MPa and 2.08±0.11MPa for GA and GEN, respectively. Although the hybrid hydrogels crosslinked with GEN presented a lower elastic modulus, the main advantage is that GEN is five to ten thousand times less cytotoxic than GA. This means that the structural and mechanical properties of hybrid hydrogels crosslinked with GEN can easily be tuned and could have potential applications in the tissue engineering, regenerative medicine, food, agriculture and environmental industries. Copyright © 2016 Elsevier Ltd. All rights reserved.

Photoemission and energy gap of MgWO4 particles connecting as nanofibers synthesized by electrospinning-calcination combinations

NASA Astrophysics Data System (ADS)

Wannapop, Surangkana; Thongtem, Titipun; Thongtem, Somchai

2012-03-01

Mixtures of magnesium acetate tetrahydrate ((CH3COO)2Mg·4H2O), ammonium tungstate tetrahydrate ((NH4)6W7O24·4H2O), and poly(vinyl alcohol) with the molecular weight of 72,000 were electrospun through a +15 kV direct voltage to form fibers on ground flat aluminum foils. The electrospun fibers of 1.5, 3.0, and 4.5 mmol of each starting material containing 1.3 g poly(vinyl alcohol) were further calcined at 500-700 °C for 3 h constant length of time. At 500 and 600 °C calcination, both monoclinic and anorthic phases of MgWO4 particles with different sizes connecting as fibrous assemblies were detected. Upon increasing the calcination temperature to 700 °C, only monoclinic phase of facet nanoparticles interconnecting along the fibrous axes with 4.19 eV indirect band gap and 461 nm photoemission was synthesized. In the present research, formation of MgWO4 molecules as well as nucleation and growth of nanoparticles was also proposed.

Selol nanocapsules with a poly(methyl vinyl ether-co-maleic anhydride) shell conjugated to doxorubicin for combinatorial chemotherapy against murine breast adenocarcinoma in vivo.

PubMed

Ganassin, Rayane; Horst, Frederico Hillesheim; Camargo, Nichollas Serafim; Chaves, Sacha Braun; Morais, Paulo César; Mosiniewicz-Szablewska, Ewa; Suchocki, Piotr; Figueiró Longo, João Paulo; Azevedo, Ricardo Bentes; Muehlmann, Luis Alexandre

2018-05-29

Nanocapsules containing selol and doxorubicin (NCS-DOX) with an oily core of selol and a shell of poly(methyl vinyl ether-co-maleic anhydride) covalently conjugated to doxorubicin were developed in a previous work. In this study, these nanocapsules showed a similar antitumour effect in comparison to the free doxorubicin (DOX) treatment, but showed no evident DOX-related cardiotoxicity, as evidenced by serum creatine kinase-MB (CK-MB) activity. The histopathological analysis showed that the free DOX treatment induced more intense morphological damage to myocardial tissues in comparison to NCS-DOX treatment. Animals treated with free DOX presented important muscle fibre degradation and animals treated with NCS-DOX, heart tissue did not present signals of muscle fibre degeneration. These results indicate that the cardiotoxicity related to DOX is reduced when this drug is carried by the NCS-DOX. Noteworthy, biodistribution analyses showed that NCS-DOX accumulated more intensely in tumours than the free DOX. Thus, this study reinforces the importance of the development of nanocapsules as drug carriers for the treatment of cancer.

Topological and morphological analysis of gamma rays irradiated chitosan-poly (vinyl alcohol) blends using atomic force microscopy

NASA Astrophysics Data System (ADS)

Bhatt, Rinkesh; Bisen, D. S.; Bajpai, R.; Bajpai, A. K.

2017-04-01

In the present communication, binary blends of poly (vinyl alcohol) (PVA) and chitosan (CS) were prepared by solution cast method and the roughness parameters of PVA, native CS and CS-PVA blend films were determined using atomic force microscopy (AFM). Moreover, the changes in the morphology of the samples were also investigated after irradiation of gamma rays at absorbed dose of 1 Mrad and 10 Mrad for the scanning areas of 5×5 μm2, 10×10 μm2 and 20×20 μm2. Amplitude, statistical and spatial parameters, including line, 3D and 2D image profiles of the experimental surfaces were examined and compared to un-irradiated samples. For gamma irradiated CS-PVA blends the larger waviness over the surface was found as compared to un-irradiated CS-PVA blends but the values of average roughness for both the films were found almost same. The coefficient of skewness was positive for gamma irradiated CS-PVA blends which revealed the presence of more peaks than valleys on the blend surfaces.

Structure and physical properties of starch/poly vinyl alcohol/sodium montmorillonite nanocomposite films.

PubMed

Ali, Samer S; Tang, Xiaozhi; Alavi, Sajid; Faubion, Jon

2011-12-14

Nanocomposites of starch, poly vinyl alcohol (PVOH), and sodium montmorillonite (Na(+)MMT) were produced by solution mixing and cast into films. Tensile strength (TS) and elongation at the break (E%) of the films ranged from 11.60 to 22.35 MPa and 28.93-211.40%, respectively, while water vapor permeability (WVP) ranged from 0.718 to 1.430 g·mm/kPa·h·m(2). In general, an increase in Na(+)MMT content (0-20%) enhanced TS and decreased E% and WVP. Use of higher molecular weight PVOH increased both TS and E% and also decreased WVP. Mechanical properties were negatively affected, but water vapor barrier properties improved with increasing starch content (0-80%). X-ray diffraction and transmission electron microscopy were used to analyze the nanostructure, and molecular conformations and interactions in the multicomponent nanocomposites were inferred from glass transition behavior. Interactions between starch and PVOH were strongest, followed by polymer/clay interactions. On the basis of this insight, a conceptual model was presented to explain the phenomena of intercalation and exfoliation in the starch/PVOH/Na(+)MMT nanocomposites.

Luminescence study of ZnSe/PVA (polyvinyl alcohol) composite film

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

Lahariya, Vikas

The ZnSe nanocrystals have been prepared into poly vinyl alcohol(PVA) polymer matrix on glass using ZnCl2 and Na2SeSO3 as zinc and selenium source respectively. Poly vinyl Alcohol (PVA) used as polymer matrix cum capping agent due to their high viscosity and water solubility. It is transparent for visible region and prevents Se- ions to photo oxidation. The ZnSe/PVA composite film was deposited on glass substrate. The film was characterized by X Ray Diffraction (XRD) and UV-Visible absorption Spectroscopy and Photoluminescence. The X Ray Diffraction (XRD) study confirms the nanometer size (10 nm) particle formation within PVA matrix with cubic zinc blendmore » crystal structure. The UV-Visible Absorption spectrum of ZnSe/PVA composite film shown blue shift in absorption edge indicating increased band gap due to quantum confinement. The calculated energy band gap from the absorption edge using Tauc relation is 3.4 eV. From the Photoluminescence study a broad peak at 435 nm has been observed in violet blue region due to recombination of surface states.« less

Study of Dielectric Behavior and Charge Conduction Mechanism of Poly(Vinyl Alcohol) (PVA)-Copper (Cu) and Gold (Au) Nanocomposites as a Bio-resorbable Material for Organic Electronics

NASA Astrophysics Data System (ADS)

Mahendia, Suman; Goyal, Parveen Kumar; Tomar, Anil Kumar; Chahal, Rishi Pal; Kumar, Shyam

2016-10-01

Poly(vinyl alcohol) (PVA) embedded with varying concentrations of chemically synthesized copper (Cu) and gold (Au) nanoparticles (NPs) were prepared using ex situ sol-gel casting method. The addition of almost the same concentration of CuNPs in PVA improves the conducting properties, while that of AuNPs improves the dielectric nature of composite films. It has been found that addition of AuNPs up to ˜0.4 wt.% concentration enhaneces the capacitive nature due to the formation of small Coulomb tunneling knots as internal capacitors. The dielectric studies suggest the Maxwell-Wagner interfacial polarization as the dominant dielectric relaxation process, whereas the I- V characteristics indicate bulk limited Poole-Frenkel emission at high voltages as the dominant charge transport mechanism operating at room temperature in all specimens. These novel features lead to the conclusion that addition of a small quantity of metal nanoparticles can help tune the properties of PVA for desired applications in bio-compatible polymer-based organic electronic devices.

Intelligent poly (vinyl alcohol)-chitosan nanoparticles-mulberry extracts films capable of monitoring pH variations.

PubMed

Ma, Qianyun; Liang, Tieqiang; Cao, Lele; Wang, Lijuan

2018-03-01

The aim of this study was to prepare a visually responsive intelligent film based on poly (vinyl alcohol) (PVA), chitosan nanoparticles (CHNPs) and mulberry extracts (MBE). CHNPs were first prepared by using ionotropic gelation method to enhance the mechanical properties of PVA based films. The morphology, particle size, zeta potential and crystallinity of CHNPs were measured. The resultant CHNPs were spherical with a diameter of 381.2nm, with high stability and a zeta potential of 49.1±1.33mV. The film with 6% CHNPs (P-C6) had the highest tensile strength (∼73.43MPa). MBE was incorporated into the P-C6 film. The film containing 20% MBE had the highest tensile strength and showed visible color responses to variations across pH 1-13. The film was tested by monitoring the spoilage of fish. The color of the film changed from red to green as the fish spoiled. Therefore, the pH responsive intelligent film developed here can be used as a package label to detect food spoilage. Copyright © 2017 Elsevier B.V. All rights reserved.

New Tetra-Schiff Bases as Efficient Photostabilizers for Poly(vinyl chloride).

PubMed

Ahmed, Dina S; El-Hiti, Gamal A; Hameed, Ayad S; Yousif, Emad; Ahmed, Ahmed

2017-09-09

Three new tetra-Schiff bases were synthesized and characterized to be used as photostabilizers for poly(vinyl chloride) (PVC) films. The photostability of PVC films (40 μm thickness) in the presence of Schiff bases (0.5 wt %) upon irradiation (300 h) with a UV light (λ max = 365 nm and light intensity = 6.43 × 10 -9 ein∙dm -3 ∙s -1 ) was examined using various spectroscopic measurements and surface morphology analysis. The changes in various functional groups' indices, weight and viscosity average molecular weight of PVC films were monitored against irradiation time. The additives used showed photostability for PVC films, with Schiff base 1 being the most effective additive upon irradiation, followed by 2 and 3 . The atomic force microscopy (AFM) images for the PVC surface containing Schiff base 1 after irradiation were found to be smooth, with a roughness factor ( R q) of 36.8, compared to 132.2 for the PVC (blank). Several possible mechanisms that explain PVC photostabilization upon irradiation in the presence of tetra-Schiff bases were proposed.

Using carboxylated nanocrystalline cellulose as an additive in cellulosic paper and poly (vinyl alcohol) fiber paper.

PubMed

Cha, Ruitao; Wang, Chengyu; Cheng, Shaoling; He, Zhibin; Jiang, Xingyu

2014-09-22

Specialty paper (e.g. cigarette paper and battery diaphragm paper) requires extremely high strength properties. The addition of strength agents plays an important role in increasing strength properties of paper. Nanocrystalline cellulose (NCC), or cellulose whiskers, has the potential to enhance the strength properties of paper via improving inter-fibers bonding. This paper was to determine the potential of using carboxylated nanocrystalline cellulose (CNCC) to improve the strength properties of paper made of cellulosic fiber or poly (vinyl alcohol) (PVA) fiber. The results indicated that the addition of CNCC can effectively improve the strength properties. At a CNCC dosage of 0.7%, the tear index and tensile index of the cellulosic paper reached the maximum of 12.8 mN m2/g and 100.7 Nm/g, respectively. More importantly, when increasing the CNCC dosage from 0.1 to 1.0%, the tear index and tensile index of PVA fiber paper were increased by 67.29%, 22.55%, respectively. Copyright © 2014 Elsevier Ltd. All rights reserved.

Development, characterization and biocompatibility of chondroitin sulfate/poly(vinyl alcohol)/bovine bone powder porous biocomposite.

PubMed

da Silva, Gabriela T; Voss, Guilherme T; Kaplum, Vanessa; Nakamura, Celso V; Wilhelm, Ethel A; Luchese, Cristiane; Fajardo, André R

2017-03-01

Chondroitin sulfate (ChS), a sulfated glycosaminoglycan, poly(vinyl alcohol) (PVA) and bovine bone powder (BBP) were blended to form a novel eco-friendly biocomposite through cyclic freeze-thawing under mild conditions. The systematic investigation reveals that the content of BBP has a remarkable effect on the pore size, porosity, mechanical and liquid uptake properties and biodegradability. At 10wt.% BBP the biocomposite exhibited enhanced mechanical properties and biodegradability rate as compared to the pristine sample. Further, different properties of the biocomposite can be tailored according to the content of BBP. In vitro assays showed that ChS/PVA-BBP does not exert cytotoxicity against healthy cells. In vivo and ex vivo experiments revealed that ChS/PVA-BBP biocomposites are biocompatibility materials without exert pro-inflammatory responses. The biocomposite was completely biodegraded and bioresorbed after 15days of treatment. Taken together, BBP is a low-cost source of hydroxyapatite and collagen, which are insurance. All these results suggest that the biocomposite designed in this study is a promising biomaterial for potential skin tissue engineering. Copyright © 2016 Elsevier B.V. All rights reserved.

Enhanced mechanical, thermal and antimicrobial properties of poly(vinyl alcohol)/graphene oxide/starch/silver nanocomposites films.

PubMed

Usman, Adil; Hussain, Zakir; Riaz, Asim; Khan, Ahmad Nawaz

2016-11-20

In the present work, synthesis of poly(vinyl alcohol)/graphene oxide/starch/silver (PVA/GO/Starch/Ag) nanocomposites films is reported. Such films have been characterized and investigated for their mechanical, thermal and antimicrobial properties. The exfoliation of GO in the PVA matrix occurs owing to the non-covalent interactions of the polymer chains of PVA and hydrophilic surface of the GO layers. Presence of GO in PVA and PVA/starch blends were found to enhance the tensile strength of the nanocomposites system. It was found that the thermal stability of PVA as well as PVA/starch blend systems increased by the incorporation of GO where strong physical bonding between GO layers and PVA/starch blends is assumed to cause thermal barrier effects. Antimicrobial properties of the prepared films were investigated against Escherichia coli and Staphylococcus aureus. Our results show enhanced antimicrobial properties of the prepared films where PVA-GO, PVA-Ag, PVA-GO-Ag and PVA-GO-Ag-Starch showed antimicrobial activity in ascending order. Copyright © 2016 Elsevier Ltd. All rights reserved.

Chromaticity and color saturation of ultraviolet irradiated poly(vinyl alcohol)-anthocyanin coatings

NASA Astrophysics Data System (ADS)

Mat Nor, N. A.; Aziz, N.; Mohd-Adnan, A. F.; Taha, R. M.; Arof, A. K.

2016-06-01

The purpose of this paper is to evaluate the chromaticity and color saturation of anthocyanin extraction from fruit pericarps of Ixora siamensis in a poly(vinyl alcohol) (PVA) matrix. The colored PVA matrix was exposed to UV-B irradiation for 93 days at UV intensity of 17.55 lux. Anthocyanin colorant has been extracted using methanol acidified with 0.5% trifluoroacetic acid (TFA). Different concentrations of ferulic acid (FA) (0, 1, 2, 3, 4 and 5 wt.%) have been added to the anthocyanin extractions before mixing with PVA to form a coating system. The PVA-anthocyanin-FA mixtures have been coated on glass slides and kept overnight in the dark for curing before exposure to UV-B irradiation. The FA-free sample undergoes more color degradation compared to samples containing FA. The coating with 2% FA has the most stable color with chromaticity of 41% and color saturation of 0.88 compared to other FA containing coats. The FA-free coat exhibits 29% chromaticity and color saturation of 0.38 at the end of the experiment.

Catalytic Effect of Pd Clusters in the Poly( N-vinyl-2-pyrrolidone) Combustion

NASA Astrophysics Data System (ADS)

Schiavo, L.; De Nicola, S.; Carotenuto, G.

2018-01-01

Pd(0) is able to catalyze oxygen-involving reactions because of its capability to convert molecular oxygen to the very reactive atomic form. Consequently, the embedding of a little amount of Pd(0) clusters in polymeric phases can be technologically exploited to enhance the incineration kinetic of these polymers. The effect of nanostructuration on the Pd(0) catalytic activity in the polymer incineration reaction has been studied using poly( N-vinyl-2-pyrrolidone) ( \\overline{Mw} = 10,000 gmol-1) as polymeric model system. A change in the PVP incineration kinetic mechanism with significant increase in the reaction rate was experimentally found. The kinetic of the Pd(0)-catalyzed combustion has been studied by isothermal thermogravimetric analysis. After a short induction time, the combustion in presence of Pd(0) clusters shifted to a zero-order kinetic from a second-order kinetic control, which is operative in pure PVP combustion reaction. In addition, the activation energy resulted much lowered compared to the pure PVP incineration case (from 300 to 260 kJ/mol).

A poly(vinyl alcohol)/sodium alginate blend monolith with nanoscale porous structure.

PubMed

Sun, Xiaoxia; Uyama, Hiroshi

2013-10-04

A stimuli-responsive poly(vinyl alcohol) (PVA)/sodium alginate (SA) blend monolith with nanoscale porous (mesoporous) structure is successfully fabricated by thermally impacted non-solvent induced phase separation (TINIPS) method. The PVA/SA blend monolith with different SA contents is conveniently fabricated in an aqueous methanol without any templates. The solvent suitable for the fabrication of the present blend monolith by TINIPS is different with that of the PVA monolith. The nanostructural control of the blend monolith is readily achieved by optimizing the fabrication conditions. Brunauer Emmett Teller measurement shows that the obtained blend monolith has a large surface area. Pore size distribution plot for the blend monolith obtained by the non-local density functional theory method reveals the existence of the nanoscale porous structure. Fourier transform infrared analysis reveals the strong interactions between PVA and SA. The pH-responsive property of the blend monolith is investigated on the basis of swelling ratio in different pH solutions. The present blend monolith of biocompatible and biodegradable PVA and SA with nanoscale porous structure has large potential for applications in biomedical and environmental fields.

In situ synthesis of bilayered gradient poly(vinyl alcohol)/hydroxyapatite composite hydrogel by directional freezing-thawing and electrophoresis method.

PubMed

Su, Cui; Su, Yunlan; Li, Zhiyong; Haq, Muhammad Abdul; Zhou, Yong; Wang, Dujin

2017-08-01

Bilayered poly(vinyl alcohol) (PVA)/hydroxyapatite (HA) composite hydrogels with anisotropic and gradient mechanical properties were prepared by the combination of directional freezing-thawing (DFT) and electrophoresis method. Firstly, PVA hydrogels with aligned channel structure were prepared by the DFT method. Then, HA nanoparticles were in situ synthesized within the PVA hydrogels via electrophoresis. By controlling the time of the electrophoresis process, a bilayered gradient hydrogel containing HA particles in only half of the gel region was obtained. The PVA/HA composite hydrogel exhibited gradient mechanical strength depending on the distance to the cathode. The gradient initial tensile modulus ranging from 0.18MPa to 0.27MPa and the gradient initial compressive modulus from 0.33MPa to 0.51MPa were achieved. The binding strength of the two regions was relatively high and no apparent internal stress or defect was observed at the boundary. The two regions of the bilayered hydrogel also showed different osteoblast cell adhesion properties. Copyright © 2017 Elsevier B.V. All rights reserved.

[The effect of long-term preservation of microbial cells immobilized in poly(vinyl alcohol) cryogel on their viability and biosynthesis of target metabolites].

PubMed

Efremenko, E N; Tatarinova, N Iu

2007-01-01

The effect of cell storage at -18 degrees C for 18-24 months on reproductive capacity was investigated for various microorganisms (gram-positive and gram-negative bacteria, yeasts, and filamentous fungi) immobilized in poly(vinyl alcohol) cryogel. To examine the viability of immobilized cells after defrosting, the bioluminescent method of intracellular ATP determination was used. A high level of metabolic activity of immobilized cells after various periods of storage was recorded for Streptomyces anulatus, Rhizopus orvzae, and Escherichia coli, which are producers of the antibiotic aurantin, L(+)-lactic acid, and the recombinant enzyme organophosphate hydrolase, respectively. It was shown that the initial concentration of immobilized cells in cryogel granules plays an important role in the survival of Str. anulatus and Pseudomonas putida after 1.5 years of storage. It was found that, after slow defrosting in the storage medium at 50C for 18 h of immobilized cells of the yeast Saccharomvces cerevisiae that had been stored for nine months, the number of reproductive cells increased due to the formation of ascospores.

Biological and physicochemical properties of carbon-graphite fibre-reinforced polymers intended for implant suprastructures.

PubMed

Segerström, Susanna; Sandborgh-Englund, Gunilla; Ruyter, Eystein I

2011-06-01

The aim of this study was to determine water sorption, water solubility, dimensional change caused by water storage, residual monomers, and possible cytotoxic effects of heat-polymerized carbon-graphite fibre-reinforced composites with different fibre loadings based on methyl methacrylate/poly(methyl methacrylate) (MMA/PMMA) and the copolymer poly (vinyl chloride-co-vinyl acetate). Two different resin systems were used. Resin A contained ethylene glycol dimethacrylate (EGDMA) and 1,4-butanediol dimethacrylate (1,4-BDMA); the cross-linker in Resin B was diethylene glycol dimethacrylate (DEGDMA). The resin mixtures were reinforced with 24, 36 and 47 wt% surface-treated carbon-graphite fibres. In addition, polymer B was reinforced with 58 wt% fibres. Water sorption was equal to or below 3.34±1.18 wt%, except for the 58 wt% fibre loading of polymer B (5.27±1.22 wt%). Water solubility was below 0.36±0.015 wt%, except for polymer B with 47 and 58 wt% fibres. For all composites, the volumetric increase was below 0.01±0.005 vol%. Residual MMA monomer was equal to or below 0.68±0.05 wt% for the fibre composites. The filter diffusion test and the (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) (MTT) assay demonstrated no cytotoxicity for the carbon-graphite fibre-reinforced composites, and residual cross-linking agents and vinyl chloride were not detectable by high-performance liquid chromatography (HPLC) analysis. © 2011 Eur J Oral Sci.

Influence of humidity on the phase behavior of API/polymer formulations.

PubMed

Prudic, Anke; Ji, Yuanhui; Luebbert, Christian; Sadowski, Gabriele

2015-08-01

Amorphous formulations of APIs in polymers tend to absorb water from the atmosphere. This absorption of water can induce API recrystallization, leading to reduced long-term stability during storage. In this work, the phase behavior of different formulations was investigated as a function of relative humidity. Indomethacin and naproxen were chosen as model APIs and poly(vinyl pyrrolidone) (PVP) and poly(vinyl pyrrolidone-co-vinyl acetate) (PVPVA64) as excipients. The formulations were prepared by spray drying. The water sorption in pure polymers and in formulations was measured at 25°C and at different values of relative humidity (RH=25%, 50% and 75%). Most water was absorbed in PVP-containing systems, and water sorption was decreasing with increasing API content. These trends could also be predicted in good agreement with the experimental data using the thermodynamic model PC-SAFT. Furthermore, the effect of absorbed water on API solubility in the polymer and on the glass-transition temperature of the formulations was predicted with PC-SAFT and the Gordon-Taylor equation, respectively. The absorbed water was found to significantly decrease the API solubility in the polymer as well as the glass-transition temperature of the formulation. Based on a quantitative modeling of the API/polymer phase diagrams as a function of relative humidity, appropriate API/polymer compositions can now be selected to ensure long-term stable amorphous formulations at given storage conditions. Copyright © 2015 Elsevier B.V. All rights reserved.

Effects of pore forming agents on chitosan-graft-poly(N-vinylpyrrolidone) hydrogel properties for use as a matrix for floating drug delivery

NASA Astrophysics Data System (ADS)

Budianto, E.; Al-Shidqi, M. F.; Cahyana, A. H.

2017-07-01

Eradicating H. pylori-based infection by using conventional oral dosage form of amoxicillin trihydrate finds difficulties to overcome rapid gastric retention time. Encapsulating amoxicillin trihydrate in floating drug delivery system may solve the problem. In this research, the floating drug delivery system of amoxicillin trihydrate encapsulated in floating chitosan-graft-poly(N-vinyl pyrrolidone) hydrogels containing CaCO3 and NaHCO3 as pore forming agents has been successfully prepared. Pore forming agents used was varied with the ratio of 10 to 25% pore forming agents to total mass of the used materials. The hydrogel were characterizedusing FTIR spectrophotometer and stereo microscope. As pore forming agents compositions increased, the porosity (%) and floating properties increased but followed by decrease in drug entrapment efficiency. Most of the floating hydrogels possessed floating ability longer than 180 min and the highest porosity was found in hydrogel containing 25% NaHCO3. Hydrogel containing CaCO3 showed sustained drug release profile than hydrogel containing NaHCO3. However, the optimum formulation was achieved at composition of 10% NaHCO3 with 57% of drug entrapped within the hydrogel and 43% drug released. The results of these studies show that NaHCO3 is an effective pore forming agents for chitosan-graft-poly(N-vinyl pyrrolidone) hydrogel preparation as compare to CaCO3.

[Preparation and catalytic activity of surface-modification CNTs/TiO2 composite photocatalysts].

PubMed

Wang, Huan-Ying; Li, Wen-Jun; Chang, Zhi-Dong; Zhou, Hua-Lei; Guo, Hui-Chao

2011-09-01

A novel kind of carbon nanotubes/titanium dioxide (CNTs/TiO2) composite photocatalyst was prepared by a modified sol-gel method in which the nanoscaled TiO2 particles were uniformly deposited on the CNTs modified with poly(vinyl pyrrolidone) (PVP). The composites were characterized by a range of analytical techniques including high resolution transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The results show the successful covering of the CNTs with PVP, forming core-shell structure. The nanoscaled TiO2 particles were uniformly deposited on the surface of CNTs reducing the bare CNTs which avoid losing the absorption and scattering of photons. The combination of CNTs and TiO2 particles imply the enhanced interactions between the CNTs and TiO2 interface which possibly becomes heterojunction. The composites become mesoporous crystalline TiO2 (anatase) clusters after annealing at 500 degrees C, and the surface area increases obviously. The photocatalytic activities of surface modification CNTs/TiO2 (smCNTs/TiO2) composites are extremely enhanced from the results of the photodegradation of methylene blue (MB).

Solid electrolytes

DOEpatents

Abraham, Kuzhikalail M.; Alamgir, Mohamed

1993-06-15

This invention pertains to Li ion (Li.sup.+) conductive solid polymer electrolytes composed of solvates of Li salts immobilized (encapsulated) in a solid organic polymer matrix. In particular, this invention relates to solid polymer electrolytes derived by immobilizing complexes (solvates) formed between a Li salt such as LiAsF.sub.6, LiCF.sub.3 SO.sub.3 or LiClO.sub.4 and a mixture of aprotic organic solvents having high dielectric constants such as ethylene carbonate (EC) (dielectric constant=89.6) and propylene carbonate (PC) (dielectric constant=64.4) in a polymer matrix such as polyacrylonitrile, poly(tetraethylene glycol diacrylate), or poly(vinyl pyrrolidinone).

The effect of polymers onto the size of zinc layered hydroxide salt and its calcined product

NASA Astrophysics Data System (ADS)

Hussein, Mohd Zobir bin; Ghotbi, Mohammad Yeganeh; Yahaya, Asmah Hj; Abd Rahman, Mohd Zaki

2009-02-01

Zinc hydroxide nitrate, a brucite-like layered material was synthesized using pH control method. Poly(vinyl alcohol) and poly(ethylene glycol) were used at various percentages as size decreasing agents during the synthesis of zinc hydroxide nitrate. SEM and PXRD showed the decrease of size and thickness of the resultant zinc hydroxide nitrates. TG and surface area data confirmed the decrease of the particle sizes, too. When zinc hydroxide nitrates were heat treated at 500 °C, the physical properties of nano zinc oxides obtained depended on the parent material, zinc hydroxide nitrate.

Rheological behavior of highly loaded cellulose nanocrystal/poly(vinyl alcohol) composite suspensions

Treesearch

Caitlin E. Meree; Gregory T. Schueneman; J. Carson Meredith; Meisha L. Shofner

2016-01-01

Recent emphasis on the pilot scale production of cellulosic nanomaterials has increased interest in the effective use of these materials as reinforcements for polymer composites. An important, enabling step to realizing the potential of cellulosic nanomaterials in their applications is the materials processing of CNC/polymer composites through multiple routes, i.e....

Solid polymer electrolytes

DOEpatents

Abraham, Kuzhikalail M.; Alamgir, Mohamed; Choe, Hyoun S.

1995-01-01

This invention relates to Li ion (Li.sup.+) conductive solid polymer electrolytes composed of poly(vinyl sulfone) and lithium salts, and their use in all-solid-state rechargeable lithium ion batteries. The lithium salts comprise low lattice energy lithium salts such as LiN(CF.sub.3 SO.sub.2).sub.2, LiAsF.sub.6, and LiClO.sub.4.

Magnetically recoverable magnetite/gold catalyst stabilized by poly(N-vinyl-2-pyrrolidone) for aerobic oxidation of alcohols.

PubMed

Chen, Hsiao Wei; Murugadoss, Arumugam; Hor, T S Andy; Sakurai, Hidehiro

2010-12-29

Fe(3)O(4):PVP/Au nanocomposite synthesized via a two-step procedure was tested as a quasi-homogenous alcohol oxidation catalyst. It was found that the nanocomposite was able to carry out aerobic oxidation of alcohols in water at room temperature. Studies show rapid magnetic recoverability and reusability characteristics.

Higher value films prepared from poly(vinyl alcohol) and amylose-fatty acid derivatives inclusion complexes

USDA-ARS?s Scientific Manuscript database

Water soluble amylose fatty acid and fatty ammonium salt inclusion complexes (AIC) were prepared by jet cooked high amylose corn starch with water soluble salts of long chain fatty acids or fatty amines. The formation of AIC was confirmed by X-ray diffraction of freeze-dried samples. After dissoluti...

Continuous Hypergolic Monitor Network for Shipboard Applications

DTIC Science & Technology

2005-08-30

PEI Oxidizers MON-25 Polyamines and Polycarbonyls Ethanol SXFA Acetone PEO Octane Poly(ethylene-co-vinyl acetate) ( PEVA ), Polyisobutylene...polyvinylacetate ( PEVA ). These tests were performed under variable humidity and temperature (Figure 13) and under low humidity at ambient temperature...Test of Chemoselective Polymers Against Interferents with Variable Temperature and Humidity. Key: PEVA black; PEI red; SXFA blue; NmA yellow

Preparation and properties of films cast from mixtures of poly(vinyl alcohol) and submicron particles prepared from amylose-palmitic acid inclusion complexes

USDA-ARS?s Scientific Manuscript database

The use of starch in polymer composites for film production has been studied extensively for increasing biodegradability, improving film properties and reducing cost. Starch nanoparticles have received much attention, primarily those obtained by acid hydrolysis of starch granules. In this study, nan...

The Rheological Properties of Poly(Vinyl Alcohol) Gels from Rotational Viscometry

ERIC Educational Resources Information Center

Hurst, Glenn A.; Bella, Malika; Salzmann, Christoph G.

2015-01-01

A laboratory experiment was developed to follow the gelation of a polyvinyl alcohol (PVA) solution upon addition of borax by using rotational viscometry. The rheological properties of the gel were examined, measuring the dependence of viscosity and shear stress on the shear rate. Time-dependent studies were also conducted in which the viscosity of…

Advanced functionalization of polyhydroxyalkanoate via the UV-initiated thiol-ene click reaction.

PubMed

Tajima, Kenji; Iwamoto, Kosuke; Satoh, Yasuharu; Sakai, Ryosuke; Satoh, Toshifumi; Dairi, Tohru

2016-05-01

Polyhydroxyalkanoates (PHAs) incorporating vinyl-bearing 3-hydroxyalkanoates were prepared in 8.5-12.9 g L(-1) yield. The molar ratios (0-16 mol%) of the vinyl-bearing 3-hydroxyalkanoate derivatives were controlled by the continuous feeding of undecylenate at various concentrations. Subsequently, the PHAs were functionalized by UV-initiated thiol-ene click reaction and chemical modification. (1)H NMR spectra suggested that 3-mercaptopropionic acid and 2-aminoethanethiol were successfully introduced into the vinyl-bearing PHA. Subsequently, chemical modification using fluorescein or a fibronectin active fragment (GRGDS) was attempted. The former yielded a PHA derivative capable of emitting fluorescence under UV irradiation, which was useful for determining the miscibility of PHA in a composite film comprising poly-ʟ-lactic acid (PLLA) and PHA. In the latter case, PHA bearing GRGDS peptides exhibited cell adhesiveness, suggesting that its biocompatibility was improved upon peptide introduction. Taken together, the UV-initiated thiol-ene click reaction was demonstrated to be useful in PHA modification.

Complex coacervate core micelles with a lysozyme-modified corona.

PubMed

Danial, Maarten; Klok, Harm-Anton; Norde, Willem; Stuart, Martien A Cohen

2007-07-17

This paper describes the preparation, characterization, and enzymatic activity of complex coacervate core micelles (C3Ms) composed of poly(acrylic acid) (PAA) and poly(N-methyl-2-vinyl pyridinium iodide)-b-poly(ethylene oxide) (PQ2VP-PEO) to which the antibacterial enzyme lysozyme is end-attached. C3Ms were prepared by polyelectrolyte complex formation between PAA and mixtures containing different ratios of aldehyde and hydroxyl end-functionalized PQ2VP-PEO. This resulted in the formation of C3Ms containing 0-40% (w/w) of the aldehyde end-functionalized PQ2VP-PEO block copolymer (PQ2VP-PEO-CHO). Chemical conjugation of lysozyme was achieved via reductive amination of the aldehyde groups, which are exposed at the surface of the C3M, with the amine groups present in the side chains of the lysine residues of the protein. Dynamic and static light scattering indicated that the conjugation of lysozyme to C3Ms prepared using 10 and 20% (w/w) PQ2VP-PEO-CHO resulted in the formation of unimicellar particles. Multimicellar aggregates, in contrast, were obtained when lysozyme was conjugated to C3Ms prepared using 30 or 40% (w/w) PQ2VP-PEO-CHO. The enzymatic activity of the unimicellar lysozyme-C3M conjugates toward the hydrolysis of the bacterial substrate Micrococcus lysodeikticus was comparable to that of free lysozyme. For the multimicellar particles, in contrast, significantly reduced enzymatic rates of hydrolysis, altered circular dichroism, and red-shifted tryptophan fluorescence spectra were measured. These results are attributed to the occlusion of lysozyme in the interior of the multimicellar conjugates.

Fluorescent porous film modified polymer optical fiber via "click" chemistry: stable dye dispersion and trace explosive detection.

PubMed

Ma, Jiajun; Lv, Ling; Zou, Gang; Zhang, Qijin

2015-01-14

In this paper, we report a facile strategy to fabricate fluorescent porous thin film on the surface of U-bent poly(methyl methacrylate) optical fiber (U-bent POF) in situ via "click" polymerization for vapor phase sensing of explosives. Upon irradiation of evanescent UV light transmitting within the fiber under ambient condition, a porous film (POSS-thiol cross-linking film, PTCF) is synthesized on the side surface of the fiber by a thiol-ene "click" reaction of vinyl-functionalized polyhedral oligomeric silsesquioxanes (POSS-V8) and alkane dithiols. When vinyl-functionalized porphyrin, containing four allyl substituents at the periphery, is added into precursors for the polymerization, fluorescence porphyrin can be covalently bonded into the cross-linked network of PTCF. This "fastened" way reduces the aggregation-induced fluorescence self-quenching of porphyrin and enhances the physicochemical stability of the porous film on the surface of U-bent POF. Fluorescent signals of the PTCF/U-bent POF probe made by this method exhibit high fluorescence quenching toward trace TNT and DNT vapor and the highest fluorescence quenching efficiency is observed for 1, 6-hexanedimercaptan-based film. In addition, because of the presence of POSS-V8 with multi cross-linkable groups, PTCF exhibits well-organized pore network and stable dye dispersion, which not only causes fast and sensitive fluorescence quenching against vapors of nitroaromatic compounds, but also provides a repeatability of the probing performance.

A Highly Hydroxide Conductive, Chemically Stable Anion Exchange Membrane, Poly(2,6 dimethyl 1,4 phenylene oxide)- b -Poly(vinyl benzyl trimethyl ammonium), for Electrochemical Applications

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

Pandey, Tara P.; Sarode, Himanshu N.; Yang, Yating

A chemically stable copolymer [poly(2,6 dimethyl 1,4 phenylene oxide)-b-poly(vinyl benzyl trimethyl ammonium)] with two ion exchange capacities, 3.2 and 2.9 meq g-1, was prepared as anion exchange membranes (AEM-3.2 and AEM-2.9). These materials showed high OH- conductivities of 138 mS.cm-1 and 106 mS.cm-1, for AEM-3.2 and AEM-2.9 respectively, at 60°C, and 95% RH. The OH- conductivity = 45 mS.cm-1 for AEM-3.2 at 60% RH and 60°C in the absence of CO2. Amongst the ions studied, only OH- is fully dissociated at high RH. The lower Ea = 10–13 kJ.mol-1 for OH- compared to F- ~ 20 kJ.mol-1 in conductivity measurements,more » and of H2O from self-diffusion coefficients suggests the presence of a Grotthuss hopping transport mechanism in OH- transport. PGSE-NMR of H2O and F- show that the membranes have low tortuosity, 1.8 and 1.2, and high water self-diffusion coefficients, 0.66 and 0.26 × 10-5 cm2.s-1, for AEM-3.2 and AEM-2.9 respectively. SAXS and TEM show that the membrane has several different sized water environments, ca. 62 nm, 20 nm, and 3.5 nm. The low water uptake, λ = 9–12, reduced swelling, and high OH- conductivity, with no chemical degradation over two weeks, suggests that the membrane is a strong candidate for electrochemical applications.« less

Fabrication of novel high performance ductile poly(lactic acid) nanofiber scaffold coated with poly(vinyl alcohol) for tissue engineering applications.

PubMed

Abdal-Hay, Abdalla; Hussein, Kamal Hany; Casettari, Luca; Khalil, Khalil Abdelrazek; Hamdy, Abdel Salam

2016-03-01

Poly(lactic acid) (PLA) nanofiber scaffold has received increasing interest as a promising material for potential application in the field of regenerative medicine. However, the low hydrophilicity and poor ductility restrict its practical application. Integration of hydrophilic elastic polymer onto the surface of the nanofiber scaffold may help to overcome the drawbacks of PLA material. Herein, we successfully optimized the parameters for in situ deposition of poly(vinyl alcohol), (PVA) onto post-electrospun PLA nanofibers using a simple hydrothermal approach. Our results showed that the average fiber diameter of coated nanofiber mat is about 1265±222 nm, which is remarkably higher than its pristine counterpart (650±180 nm). The hydrophilicity of PLA nanofiber scaffold coated with a PVA thin layer improved dramatically (36.11±1.5°) compared to that of pristine PLA (119.7±1.5°) scaffold. The mechanical testing showed that the PLA nanofiber scaffold could be converted from rigid to ductile with enhanced tensile strength, due to maximizing the hydrogen bond interaction during the heat treatment and in the presence of PVA. Cytocompatibility performance of the pristine and coated PLA fibers with PVA was observed through an in vitro experiment based on cell attachment and the MTT assay by EA.hy926 human endothelial cells. The cytocompatibility results showed that human cells induced more favorable attachment and proliferation behavior on hydrophilic PLA composite scaffold than that of pristine PLA. Hence, PVA coating resulted in an increase in initial human cell attachment and proliferation. We believe that the novel PVA-coated PLA nanofiber scaffold developed in this study, could be a promising high performance biomaterial in regeneration medicine. Copyright © 2015. Published by Elsevier B.V.

Influence of gamma irradiation on polymerization of pyrrole and glucose oxidase immobilization onto poly (pyrrole)/poly (vinyl alcohol) matrix

NASA Astrophysics Data System (ADS)

Idris, Sarada; A. Bakar, Ahmad Ashrif; Thevy Ratnam, Chantara; Kamaruddin, Nur Hasiba; Shaari, Sahbudin

2017-04-01

This paper describes the immobilization of glucose oxidase, GOx onto polymer matrix comprising of poly(pyrrole), PPy and poly(vinyl alcohol), PVA using gamma irradiation technique. Py/PVA-GOx film was prepared by spreading PVA:GOx, 1:1 solution onto dried pyrrole film and exposed to gamma irradiation from cobalt 60 source at doses ranging from 0 to 60 kGy. The films were subjected to structural and morphological analyses by using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Scanning electron microscope (SEM), Field emission scanning electron microscope (FESEM) and Atomic-force microscopy (AFM) techniques. Similar studies were also made on pristine pyrrole film which served as control. The SEM and FTIR spectra of Py/PVA-GOx film revealed that pyrrole has been successfully polymerized through irradiation-induced reactions. The results on the morphological properties of the samples characterize using FESEM, SEM and AFM further confirmed the occurrence of radiation-induced modification of Py/PVA-GOx film. The FTIR spectra showed the existence of intermolecular interaction between polymer matrix and GOx indicating that GOx had been successfully immobilized onto Ppy/PVA matrix by radiation-induced reactions. Results revealed that radiation induced reactions such as polymerization of pyrrole, crosslinking of PVA, grafting between the adjacent PVA and pyrrole molecules as well as immobilization of GOx onto Ppy/PVA matrix occurred simultaneously upon gamma irradiation. The optimum dose for GOx immobilization in the polymer matrix found to be 40 kGy. Therefore it is clear that this irradiation technique offered a simple single process to produce Py/PVA-GOx film without additional crosslinking and polymerization agents.

In vitro and in vivo study of sustained nitric oxide release coating using diazeniumdiolate-oped poly(vinyl chloride) matrix with poly(lactide-co-glycolide) additive

PubMed Central

Handa, Hitesh; Brisbois, Elizabeth J.; Major, Terry C.; Refahiyat, Lahdan; Amoako, Kagya A.; Annich, Gail M.; Bartlett, Robert H.; Meyerhoff, Mark E.

2013-01-01

Nitric oxide (NO) is an endogenous vasodilator as well as natural inhibitor of platelet adhesion and activation that can be released from a NO donor species, such as diazeniumdiolated dibutylhexanediamine (DBHD/N2O2) within a polymer coating. In this study, various Food and Drug Administration approved poly(lactic-co-glycolic acid) (PLGA) species were evaluated as additives to promote a prolonged NO release from DBHD/N2O2 within a plasticized poly(vinyl chloride) (PVC) matrix. When using an ester-capped PLGA additive with a slow hydrolysis time, the resulting coatings continuously release between 7–18×10-10 mol cm-2 min-1 NO for 14 d at 37°C in PBS buffer. The corresponding pH changes within the polymer films were visualized using pH sensitive indicators and are shown to correlate with the extended NO release pattern. The optimal combined diazeniumdiolate/PLGA-doped NO release (NOrel) PVC coating was evaluated in vitro and its effect on the hemodynamics was also studied within a 4 h in vivo extracorporeal circulation (ECC) rabbit model of thrombogenicity. Four out of 7 control circuits clotted within 3 h, whereas all the NOrel coated circuits were patent after 4 h. Platelet counts on the NOrel ECC were preserved (79 ± 11% compared to 54 ± 6% controls). The NOrel coatings showed a significant decrease in the thrombus area as compared to the controls. Results suggest that by using ester-capped PLGAs as additives to a conventional plasticized PVC material containing a lipophilic diazeniumdiolates, the NO release can be prolonged for up to 2 weeks by controlling the pH within the organic phase of the coating. PMID:23914297

Poly(N-vinylpyrrolidone)-block-poly(vinyl acetate) as a drug delivery vehicle for hydrophobic drugs.

PubMed

Bailly, Nathalie; Thomas, Mark; Klumperman, Bert

2012-12-10

Poly((N-vinylpyrrolidone)-block-poly(vinyl acetate)) (PVP-b-PVAc) block copolymers of varying molecular weight and hydrophobic block lengths were synthesized via controlled radical polymerization and investigated as carriers for the solubilization of highly hydrophobic riminophenazine compounds. These compounds have recently been shown to exhibit a strong activity against a variety of cancer types. PVP-b-PVAc self-assembles into polymer vesicles in aqueous media, and the dialysis method was used to load the water-insoluble drug (clofazimine) into these polymer vesicles. The polymer vesicles were characterized by 1H NMR spectroscopy to confirm vesicle formation and the incorporation of the anticancer drugs into the polymer vesicles. Dynamic light scattering was used to determine the particle size and particle size distribution of the drug-loaded vesicles as well as the stability of the vesicles under physiological conditions. The size of the polymer vesicles did not increase upon loading with clofazimine, and the particle size of 180-200 nm and the narrow particle size distribution were maintained. The morphology of the vesicles was examined by transmission electron microscopy. The polymer vesicles had a relatively high drug loading capacity of 20 wt %. In vitro cytotoxicity studies of PVP-b-PVAc and drug-loaded PVP-b-PVAc were performed against MDA-MB-231 multidrug-resistant breast epithelial cancer cells and MCF12A nontumorigenic breast epithelial cells. In vitro experiments demonstrated that the PVP-b-PVAc drug carrier showed no cytotoxicity, which confirms the biocompatibility of the PVP-b-PVAc drug carrier. The results indicate that the present PVP-b-PVAc block copolymer could be a potential candidate as a drug carrier for hydrophobic drugs.

Dielectric relaxation and ac conductivity behavior of carboxyl functionalized multiwalled carbon nanotubes/poly (vinyl alcohol) composites

NASA Astrophysics Data System (ADS)

Amrin, Sayed; Deshpande, V. D.

2017-03-01

We study the dielectric relaxation and ac conductivity behavior of MWCNT-COOH/Polyvinyl alcohol nanocomposite films in the temperature (T) range 303-423 K and in the frequency (f) range 0.1 Hz-1 MHz. The dielectric constant increases with an increase in temperature and also with an increase in MWCNT-COOH loading into the polymer matrix, as a result of interfacial polarization. The permittivity data were found to fit well with the modified Cole-Cole equation. Temperature dependent values of the relaxation times, free charge carrier conductivity and space charge carrier conductivity were extracted from the equation. An observed increment in the ac conductivity for the nanocomposites was analysed by a Jonscher power law which suggests that the correlated barrier hopping is the dominant charge transport mechanism for the nanocomposite films. The electric modulus study revealed deviations from ideal Debye-type behavior which are explained by considering a generalized susceptibility function. XRD and DSC results show an increase in the degree of crystallinity.

Novel reverse osmosis membranes composed of modified PVA/Gum Arabic conjugates: Biofouling mitigation and chlorine resistance enhancement.

PubMed

Falath, Wail; Sabir, Aneela; Jacob, Karl I

2017-01-02

A novel crosslinked Poly (vinyl alcohol) (PVA) reverse osmosis (RO) thin film membrane conjugated with Gum Arabic (GA) with superb performance and features was synthesized for water desalination. RO membrane desalination parameters, such as hydrophilicity, surface roughness, water permeability, salt rejection, Chlorine resistance and biofouling resistance were evaluated using a dead end RO filtration unit. The incorporation of Pluronic F127 and the conjugation of Gum Arabic improved the overall RO performance of the membranes. This study has shown that the membrane PVA-GA-5 that contains 0.9wt% Gum Arabic provided excellent permeation, salt rejection, Chlorine and biofouling resistance and mechanical strength. The most remarkable result to arise from this research is that the overall RO performance enhancement has been achieved while utilizing PVA/Gum Arabic as a separation layer without the use of a substrate, which eliminates negative effects associated with the use of a substrate like internal concentration polarization. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of silver-doping on the crystal structure, morphology and photocatalytic activity of TiO2 nanofibers

NASA Astrophysics Data System (ADS)

Barakat, N. A. M.; Kim, H. Y.

2012-09-01

In this study, effect of sliver-doping on the crystal structure, the nanofibrous morphology and the photocatalytic activity of titanium oxide nanofibers have been investigated. Silver-doped TiO2 nanofibers having different silver contents were prepared by calcination of electrospun nanofiber mats consisting of silver nitrate, titanium isopropoxide and poly(vinyl acetate) at 600 °C. The results affirmed formation of silver-doped TiO2 nanofibers composed of anatase and rutile when the silver nitrate content in the original electrospun solution was more than 3 wt%. The rutile phase content was directly proportional with the AgNO3 concentration in the electrospun solution. Negative impact of the silver-doping on the nanofibrous morphology was observed as increase the silver content caused to decrease the aspect ratio, i.e. producing nanorods rather nanofibers. However, silver-doping leads to modify the surface roughness. Study of the photocatalytic degradation of methylene blue dye clarified that increase the silver content strongly enhances the dye oxidation process.

Polysiloxane-based luminescent elastomers prepared by thiol-ene "click" chemistry.

PubMed

Zuo, Yujing; Lu, Haifeng; Xue, Lei; Wang, Xianming; Wu, Lianfeng; Feng, Shengyu

2014-09-26

Side-chain vinyl poly(dimethylsiloxane) has been modified with mercaptopropionic acid, methyl 3-mercaptopropionate, and mercaptosuccinic acid. Coordinative bonding of Eu(III) to the functionalized polysiloxanes was then carried out and crosslinked silicone elastomers were prepared by thiol-ene curing reactions of these composites. All these europium complexes could be cast to form transparent, uniform, thin elastomers with good flexibility and thermal stability. The networks were characterized by FTIR, NMR, UV/Vis, and luminescence spectroscopy as well as by scanning electron microscopy, thermogravimetric analysis, and X-ray photoelectron spectroscopy. The europium elastomer luminophores exhibited intense red light at 617 nm under UV excitation at room temperature due to the (5)D0 →(7)F2 transition in Eu(III) ions. The newly synthesized luminescent materials offer many advantages, including the desired mechanical flexibility. They cannot be dissolved or fused, and so they have potential for use in optical and electronic applications. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Surface-coated fly ash used as filler in biodegradable poly(vinyl alcohol) composite films: Part 1—The modification process

NASA Astrophysics Data System (ADS)

Nath, D. C. D.; Bandyopadhyay, S.; Gupta, S.; Yu, A.; Blackburn, D.; White, C.

2010-02-01

The surfaces of fly ash (FA) particles were modified by surfactant, sodium lauryl sulphate (SLS) and used in fabrication of composite films with polyvinyl alcohol (PVA). Both unmodified fly ash (FA) and modified fly ash (SLS-FA) samples were examined using a range of analytical tools including X-ray fluorescence spectroscopy (XRF), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS). The distribution patterns of SLS-FA particles were shifted to the higher regions compared to FA by adding 1.2-4.2 μm in the ranges between 2 and 25 μm, whereas the modification process reduced the size of the particles over 25 μm due to grinding during the activation process. The increased 1.2-4.2 μm in average can be considered the thickness of the surfactant on the SLS-FA surface. On the oxides based chemical analysis by XRF, the compositions were almost unchanged. SEM and TEM were visualised the irregular sizes morphology mostly spherical of the particles, although it is impossible to capture the images of exactly same particles in modified and unmodified forms. The composite films reinforced with SLS-FA showed 33% higher strength than those of FA filled films. The enhancement of tensile strength attributed from the level of physical bonding between SLS-FA and PVA surfaces.

40 CFR 721.10044 - Metal oxide, modified with alkyl and vinyl terminated polysiloxanes (generic).

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Metal oxide, modified with alkyl and... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10044 Metal oxide, modified with alkyl... to reporting. (1) The chemical substance identified generically as metal oxide, modified with alkyl...

Studies on polyurethane adhesives and surface modification of hydrophobic substrates

NASA Astrophysics Data System (ADS)

Krishnamoorthy, Jayaraman

This thesis work deals with (a) Curing of reactive, hot-melt polyurethane adhesives and (b) Adsorption studies using different interactions. Research on polyurethanes involves characterization of polyurethane prepolymers and a novel mechanism to cure isocyanate-terminated polyurethane prepolymer by a "trigger" mechanism. Curing of isocyanate-terminated polyurethane prepolymers has been shown to be influenced by morphology and environmental conditions such as temperature and relative humidity. Although the initial composition, final morphology and curing kinetics are known, information regarding the intermediate prepolymer mixture is yet to be established. Polyurethane prepolymers prepared by the reaction of diisocyanates with the primary hydroxyls of polyester diol (PHMA) and secondary hydroxyls of polyether diol (PPG) were characterized. The morphology and crystallization kinetics of a polyurethane prepolymer was compared with a blend of PPG prepolymer (the product obtained by the reaction of PPG with diisocyanate) and a PHMA prepolymer (the product obtained by the reaction of PHMA with diisocyanate) to study the effect of copolymer formed in the polyurethane prepolymer on the above-mentioned properties. Although the morphology of the polyurethane prepolymer is determined in the first few minutes of application, the chemical curing of isocyanate-terminated prepolymer occurs over hours to days. In the literature, different techniques are described to follow the curing kinetics. But there is no established technique to control the curing of polyurethane prepolymer. To make the curing process independent of environmental factors, a novel approach using a trigger mechanism was designed and implemented by using ammonium salts as curing agents. Ammonium salts that are stable at room temperature but decompose on heating to yield active hydrogen-containing compounds, NH3 and H2O, were used as 'Trojan horses' to cure the prepolymer chemically. Research on adsorption studies involved making functionalized, thickness-controlled, wettability-controlled multilayers on hydrophobic substrates and the adsorption of carboxylic acid-terminated poly(styrene-b-isoprene) on alumina/silica substrates. Poly(vinyl alcohol) has been shown to adsorb onto hydrophobic surfaces irreversibly due to hydrophobic interactions. This thin semicrystalline coating is chemically modified using acid chlorides, butyl isocyanate and butanal to form thicker and hydrophobic coatings. The products of the modification reactions allow adsorption of a subsequent layer of poly(vinyl alcohol) that could subsequently be hydrophobized. This 2-step (adsorption/chemical modification) allows layer-by-layer deposition to prepare coatings with thickness, chemical structure and wettability control on any hydrophobic surface. Research on adsorption characteristics of carboxylic acid-terminated poly(styrene-b-isoprene) involved syntheses of block copolymers with the functional group present at specific ends. Comparative adsorption studies for carboxylic acid-terminated and hydrogen-terminated block copolymers was carried out on alumina and silica substrates.

Poly(vinyl alcohol)-based film potentially suitable for antimicrobial packaging applications.

PubMed

Musetti, Alessandro; Paderni, Katia; Fabbri, Paola; Pulvirenti, Andrea; Al-Moghazy, Marwa; Fava, Patrizia

2014-04-01

This work aimed at developing a thin and water-resistant food-grade poly(vinyl alcohol) (PVOH)-based matrix able to swell when in contact with high moisture content food products without rupturing to release antimicrobial agents onto the food surface. This film was prepared by blending PVOH and 7.20% (wt/wt of PVOH) of poly(ethylene glycol) (PEG) with citric acid as crosslinking agent. The film-forming solution was then casted onto a flat surface and the obtained film was 60 μm in thickness and showed a good transparency (close to T = 100%) in the visible region (400 to 700 nm). After immersion in water for 72 h at room temperature, the crosslinked matrix loses only 19.2% of its original weight (the percentage includes the amount of unreacted crosslinking agent, antimicrobial in itself). Water content, degree of swelling, and crosslinking density of the film prove that the presence of PEG diminishes the hydrophilic behavior of the material. Also the mechanical properties of the wet and dry film were assessed. Alongside this, 2.5% (wt/wt of dry film) of grapefruit seed extract (GSE), an antimicrobial agent, was added to the film-forming solution just before casting and the ability of the plastic matrix to release the additive was then evaluated in vitro against 2 GSE-susceptible microorganisms, Salmonella enteritidis and Listeria innocua. The results indicate that the developed matrix may be a promising food-grade material for the incorporation of active substances. © 2014 Institute of Food Technologists®

Synthesis and properties of hemicelluloses-based semi-IPN hydrogels.

PubMed

Peng, Feng; Guan, Ying; Zhang, Bing; Bian, Jing; Ren, Jun-Li; Yao, Chun-Li; Sun, Run-Cang

2014-04-01

Hemicelluloses were extracted from holocellulose of bamboo by alkaline treatment. The phosphorylated poly(vinyl alcohol) (P-PVA) samples with various substitution degrees were prepared through the esterification of PVA and phosphoric acid. A series of hydrogels of semi-interpenetrating polymeric networks (semi-IPN) composed of hemicelluloses-g-poly(acrylic acid) (HM-g-PAA) and the phosphorylated poly(vinyl alcohol) (P-PVA) were prepared by radical polymerization using potassium persulphate (KPS) as initiator. The HM-g-PAA networks were crosslinked by N,N-methylenebisacrylamide (MBA) as a crosslinking agent in the presence of linear P-PVA. FT-IR results confirmed that the hydrogels comprised a porous crosslink structure of P-PVA and HM with side chains that carried carboxylate and phosphorylate groups. SEM observations indicated that the incorporation of P-PVA induced highly porous structure, and P-PVA was uniformly dispersed in the polymeric network. The interior network structures of the semi-IPN matrix became more porous with increasing P-PVA. The TGA results showed that the thermo-decomposing temperature and thermal stability were increased effectively for intruding the chain of P-PVA. The maximum equilibrium swelling ratio of hydrogels in distilled water and 0.9 wt% sodium chloride solutions was up to 1085 g g(-1) and 87 g g(-1), respectively. The compressive strength increased with increasing the MBA/HM and P-PVA/HM ratios, and decreased with the increment of AA/HM ratio. Copyright © 2014 Elsevier B.V. All rights reserved.

Design of poly(acrylonitrile)-based gel electrolytes for high-performance lithium ion batteries.

PubMed

Wang, Shih-Hong; Kuo, Ping-Lin; Hsieh, Chien-Te; Teng, Hsisheng

2014-11-12

The use of polyacrylonitrile (PAN) as a host for gel polymer electrolytes (GPEs) commonly produces a strong dipole-dipole interaction with the polymer. This study presents a strategy for the application of PAN in GPEs for the production of high performance lithium ion batteries. The resulting gel electrolyte GPE-AVM comprises a poly(acrylonitrile-co-vinyl acetate) copolymer blending poly(methyl methacrylate) as a host, which is swelled using a liquid electrolyte (LE) of 1 M LiPF6 in carbonate solvent. Vinyl acetate and methacrylate groups segregate the PAN chains in the GPE, which produces high ionic conductivity (3.5 × 10 (-3) S cm(-1) at 30 °C) and a wide electrochemical voltage range (>6.5 V) as well as an excellent Li(+) transference number of 0.6. This study includes GPE-AVM in a full-cell battery comprising a LiFePO4 cathode and graphite anode to promote ion motion, which reduced resistance in the battery by 39% and increased the specific power by 110%, relative to the performance of batteries based on LE. The proposed GPE-based battery has a capacity of 140 mAh g(-1) at a discharge rate of 0.1 C and is able to deliver 67 mAh g(-1) of electricity at 17 C. The proposed GPE-AVM provides a robust interface with the electrodes in full-cell batteries, resulting in 93% capacity retention after 100 charge-discharge cycles at 17 C and 63% retention after 1000 cycles.

Polymer-based materials to be used as the active element in microsensors: a scanning force microscopy study

PubMed

Porter; Eastman; Pace; Bradley

2000-09-01

Polymer-based materials can be incorporated as the active sensing elements in chemiresistor devices. Most of these devices take advantage of the fact that certain polymers will swell when exposed to gaseous analytes. To measure this response, a conducting material such as carbon black is incorporated within the nonconducting polymer matrix. In response to analytes, polymer swelling results in a measurable change in the conductivity of the polymer/carbon composite material. Arrays of these sensors may be used in conjunction with pattern recognition techniques for purposes of analyte recognition and quantification. We have used the technique of scanning force microscopy (SFM) to investigate microstructural changes in carbon-polymer composites formed from the polymers poly (isobutylene) (PIB), poly (vinyl alcohol) (PVA), and poly (ethylene-vinyl acetate) (PEVA) when exposed to the analytes hexane, toluene, water, ethanol, and acetone. Using phase-contrast imaging (PI), changes in the carbon nanoparticle distribution on the surface of the polymer matrix are measured as the polymers are exposed to the analytes in vapor phase. In some but not all cases, the changes were reversible (at the scale of the SFM measurements) upon removal of the analyte vapor. In this paper, we also describe a new type of microsensor based on piezoresistive microcantilever technology. With these new devices, polymeric volume changes accompanying exposure to analyte vapor are measured directly by a piezoresistive microcantilever in direct contact with the polymer. These devices may offer a number of advantages over standard chemiresistor-based sensors.

Ethanol-assisted multi-sensitive poly(vinyl alcohol) photonic crystal sensor.

PubMed

Chen, Cheng; Zhu, Yihua; Bao, Hua; Shen, Jianhua; Jiang, Hongliang; Peng, Liming; Yang, Xiaoling; Li, Chunzhong; Chen, Guorong

2011-05-21

An ethanol-assisted method is utilized to generate a robust gelated crystalline colloidal array (GCCA) photonic crystal sensor. The functionalized sensor efficiently diffracts the visible light and responds to various stimuli involving solvent, pH, cation, and compressive strain; the related color change can be easily distinguished by the naked eye. © The Royal Society of Chemistry 2011

Solid polymer electrolyte lithium batteries

DOEpatents

Alamgir, M.; Abraham, K.M.

1993-10-12

This invention pertains to Lithium batteries using Li ion (Li[sup +]) conductive solid polymer electrolytes composed of solvates of Li salts immobilized in a solid organic polymer matrix. In particular, this invention relates to Li batteries using solid polymer electrolytes derived by immobilizing solvates formed between a Li salt and an aprotic organic solvent (or mixture of such solvents) in poly(vinyl chloride). 3 figures.

Solid polymer electrolyte lithium batteries

DOEpatents

Alamgir, Mohamed; Abraham, Kuzhikalail M.

1993-01-01

This invention pertains to Lithium batteries using Li ion (Li.sup.+) conductive solid polymer electrolytes composed of solvates of Li salts immobilized in a solid organic polymer matrix. In particular, this invention relates to Li batteries using solid polymer electrolytes derived by immobilizing solvates formed between a Li salt and an aprotic organic solvent (or mixture of such solvents) in poly(vinyl chloride).

Cellulose nanofibril/reduced graphene oxide/carbon nanotube hybrid aerogels for highly flexible and all-solid-state supercapacitors

Treesearch

Qifeng Zheng; Zhiyong Cai; Zhenqiang Ma; Shaoqin Gong

2015-01-01

A novel type of highly flexible and all-solid-state supercapacitor that uses cellulose nanofibril (CNF)/reduced graphene oxide (RGO)/carbon nanotube (CNT) hybrid aerogels as electrodes and H2SO4 poly (vinyl alcohol) PVA gel as the electrolyte was developed and is reported here. These flexible solid-state supercapacitors...

Solid polymer electrolytes

DOEpatents

Abraham, K.M.; Alamgir, M.; Choe, H.S.

1995-12-12

This invention relates to Li ion (Li{sup +}) conductive solid polymer electrolytes composed of poly(vinyl sulfone) and lithium salts, and their use in all-solid-state rechargeable lithium ion batteries. The lithium salts comprise low lattice energy lithium salts such as LiN(CF{sub 3}SO{sub 2}){sub 2}, LiAsF{sub 6}, and LiClO{sub 4}. 2 figs.

HBCU Future Engineering Faculty Fellowship Program

DTIC Science & Technology

2009-03-31

North Carolina Agricultural and Technical State University in Greensboro, North Carolina. He received both his Master of Science and Doctor of...Department of Industrial and Systems Engineering at North Carolina Agricultural and Technical State University since January 2002, Christopher’s...Polyvinyl alcohol Membranes. The overall objective of Felecia Nave’s research is to synthesize and characterize poly vinyl alcohol hydrogels that

CuC1 thermochemical cycle for hydrogen production

DOEpatents

Fan, Qinbai [Chicago, IL; Liu, Renxuan [Chicago, IL

2012-01-03

An electrochemical cell for producing copper having a dense graphite anode electrode and a dense graphite cathode electrode disposed in a CuCl solution. An anion exchange membrane made of poly(ethylene vinyl alcohol) and polyethylenimine cross-linked with a cross-linking agent selected from the group consisting of acetone, formaldehyde, glyoxal, glutaraldehyde, and mixtures thereof is disposed between the two electrodes.

Thermomechanical Properties of Lignin-Based Electrospun Nanofibers and Films Reinforced with Cellulose Nanocrystals: A Dynamic Mechanical and Nanoindentation Study

Treesearch

Mariko Ago; Joseph E. Jakes; Orlando J. Rojas

2013-01-01

We produced defect-free electrospun fibers from aqueous dispersions of lignin, poly(vinyl alcohol) (PVA), and cellulose nanocrystals (CNCs), which were used as reinforcing nanoparticles. The thermomechanical performance of the lignin-based electrospun fibers and the spin-coated thin films was improved when they were embedded with CNCs. Isochronal dynamic mechanical...

Polymer/boron nitride nanocomposite materials for superior thermal transport performance.

PubMed

Song, Wei-Li; Wang, Ping; Cao, Li; Anderson, Ankoma; Meziani, Mohammed J; Farr, Andrew J; Sun, Ya-Ping

2012-06-25

Boron nitride nanosheets were dispersed in polymers to give composite films with excellent thermal transport performances approaching the record values found in polymer/graphene nanocomposites. Similarly high performance at lower BN loadings was achieved by aligning the nanosheets in poly(vinyl alcohol) matrix by simple mechanical stretching (see picture). Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Demonstration of the Coagulation and Diffusion of Homemade Slime Prepared under Acidic Conditions without Borate

ERIC Educational Resources Information Center

Isokawa, Naho; Fueda, Kazuki; Miyagawa, Korin; Kanno, Kenichi

2015-01-01

Poly(vinyl alcohol) (PVA) precipitates in many kinds of aqueous salt solutions. While sodium sulfate, a coagulant for PVA fiber, precipitates PVA to yield a white rigid gel, coagulation of PVA with aluminum sulfate, a coagulant for water treatment, yields a slime-like viscoelastic fluid. One type of homemade slime is prepared under basic…

Photothermoplastic films for holographic recording

NASA Technical Reports Server (NTRS)

Neduzhiy, S. A.; Pavlov, A. V.; Tabatadze, D. G.; Cheltsova, T. V.

1987-01-01

The electrophotographic and sensitometric characteristics of poly-N-vinyl carbazole photothermoplastic films, sensitized by an amorphous-Se sublayer are examined. It is shown that the photosensitivity of the material can be improved and its spectral range can be expanded by sensitization of amorphous Se with additions of Te, As, and Sb; this can be accomplished without a significant reduction in diffraction efficiency and resolving power.

Effect of cellulose nanocrystals (CNCs) on crystallinity, mechanical and rheological properties of polypropylene/CNCs nanocomposites

NASA Astrophysics Data System (ADS)

Bagheriasl, D.; Carreau, P. J.; Dubois, C.; Riedl, B.

2015-05-01

Rheological and mechanical properties of polypropylene (PP)/CNCs nanocomposites were compared with those of nanocomposites containing poly(ethylene-co-vinyl alcohol) as a compatibilizer. The nanocomposites were prepared by a Brabender internal mixer at CNC contents of 5 wt%. The compression molded nanocomposite dog-bones and disks were characterized regarding their tensile and dynamic rheological behavior, respectively. The complex viscosity of the nanocomposites samples containing the compatibilizer were increased, slightly, compared to the non-compatibilized nanocomposite samples. Moreover, an overshoot in the transient start-up viscosity of the compatibilized nanocomposite was observed. The Young modulus of the nanocomposite samples containing the compatibilizer were increased up to ca. 37% compared to the neat PP. The elongation at break was decreased in all PP/CNC nanocomposite samples, but less for the nanocomposite samples containing the compatibilizer. The crystalline content of the PP in the nanocomposites and also the crystallization temperature were increased after compatibilization. These results could be ascribed to the efficiency of the poly(ethylene-co-vinyl alcohol) as a compatibilizer that favors a better dispersion and wetting of the hydrophilic CNCs within the hydrophobic PP.

Design and fabrication of optical chemical sensor for detection of nitroaromatic explosives based on fluorescence quenching of phenol red immobilized poly(vinyl alcohol) membrane.

PubMed

Zarei, Ali Reza; Ghazanchayi, Behnam

2016-04-01

The present study developed a new optical chemical sensor for detection of nitroaromatic explosives in liquid phase. The method is based on the fluorescence quenching of phenol red as fluorophore in a poly(vinyl alcohol) (PVA) membrane in the presence of nitroaromatic explosives as quenchers, e.g., 2,4,6-trinitrotoluene (TNT), 2,4-dinitrotoluene (2,4-DNT), 4-nitrotoluene (4-NT), 2,4,6-trinitrobenzene (TNB), and nitrobenzene (NB). For chemical immobilization of phenol red in PVA, phenol red reacted with formaldehyde to produce hydroxymethyl groups and then attached to PVA membrane through the hydroxymethyl groups. The optical sensor showed strong quenching of nitroaromatic explosives. A Stern-Volmer graph for each explosive was constructed and showed that the range of concentration from 5.0 × 10(-6) to 2.5 × 10(-4) mol L(-1) was linear for each explosive and sensitivity varied as TNB >TNT>2,4-DNT>NB>4-NT. The response time of the sensor was within 1 min. The proposed sensor showed good reversibility and reproducibility. Copyright © 2015 Elsevier B.V. All rights reserved.

Three-Dimensional Printed Poly(vinyl alcohol) Substrate with Controlled On-Demand Degradation for Transient Electronics.

PubMed

Yoon, Jinsu; Han, Jungmin; Choi, Bongsik; Lee, Yongwoo; Kim, Yeamin; Park, Jinhee; Lim, Meehyun; Kang, Min-Ho; Kim, Dae Hwan; Kim, Dong Myong; Kim, Sungho; Choi, Sung-Jin

2018-05-25

Electronics that degrade after stable operation for a desired operating time, called transient electronics, are of great interest in many fields, including biomedical implants, secure memory devices, and environmental sensors. Thus, the development of transient materials is critical for the advancement of transient electronics and their applications. However, previous reports have mostly relied on achieving transience in aqueous solutions, where the transience time is largely predetermined based on the materials initially selected at the beginning of the fabrication. Therefore, accurate control of the transience time is difficult, thereby limiting their application. In this work, we demonstrate transient electronics based on a water-soluble poly(vinyl alcohol) (PVA) substrate on which carbon nanotube (CNT)-based field-effect transistors were fabricated. We regulated the structural parameters of the PVA substrate using a three-dimensional (3D) printer to accurately control and program the transience time of the PVA substrate in water. The 3D printing technology can produce complex objects directly, thus enabling the efficient fabrication of a transient substrate with a prescribed and controlled transience time. In addition, the 3D printer was used to develop a facile method for the selective and partial destruction of electronics.

Development of swellable local implants of a polyethyleneimine-poly(vinyl pyrrolidone) (PEI-PVP) hydrogel as a socket filler.

PubMed

Chang, Ching-Wen; Ho, Hsiu-O; Lo, Yi-June; Lee, Sheng-Yang; Yang, You-Ren; Sheu, Ming-Thau

2012-01-01

In this study, hydrogels composed of polyethyleneimine (PEI) and poly(vinyl pyrrolidone) K90 (PVP) cross-linked with various concentrations (0, 0.125, 0.25 and 0.5%) of glutaraldehyde were evaluated as a hydrogel filler for the local delivery of lidocaine after tooth extraction. The drug-release kinetics, swellability, cytotoxicity and wound healing after tooth extraction of these non-cross-linked and cross-linked PEI-PVP hydrogels were examined in male beagles and compared to values using Spongostan(®). Results demonstrated that the extent of cross-linking influenced the swelling of the resulting hydrogel, but the drug-release rates were similar. No significant changes were observed in gingival fibroblasts in contact with the PEI- PVP hydrogels or Spongostan(®). In the in vivo study, PEI-PVP hydrogels showed good retention in the socket for 2 days and showed comparable wound-healing rates within 2 weeks with those of Spongostan(®). In conclusion, PEI-PVP hydrogels are suitable for use as socket-dressing materials, and the release of local anaesthesia from PEI-PVP hydrogels can be sustained for a desirable period of time to prevent pain after a tooth extraction.

Evaluation of physicochemical and biological properties of chitosan/poly (vinyl alcohol) polymer blend membranes and their correlation for Vero cell growth.

PubMed

Sharma, Parul; Mathur, Garima; Dhakate, Sanjay R; Chand, Subhash; Goswami, Navendu; Sharma, Sanjeev K; Mathur, Ashwani

2016-02-10

The blend membranes with varying weight ratios of chitosan/poly (vinyl alcohol) (CS/PVA) (1:0, 1:1, 1:2.5, 1.5:1, 1.5: 2.5) were prepared using solvent casting method and were evaluated for their potential application in single-use membrane bioreactors (MBRs). The physicochemical properties of the prepared membranes were investigated for chemical interactions (FTIR), surface morphology (SEM), water uptake, protein sorption (qe), ammonia sorption and growth kinetics of Vero cells. CS/PVA blend membrane having weight ratio of 1.5:1 had shown enhanced membrane flexibility, reduced water uptake, less protein sorption and no ammonium sorption compared to CS membrane. This blend membrane also showed comparatively enhanced higher specific growth rate (0.82/day) of Vero cells. Improved physicochemical properties and growth kinetics obtrude CS/PVA (1.5:1) as a potential surface for adhesion and proliferation with possible application in single use membrane bioreactors. Additionally, new insight explaining correlation between water holding (%) of CS/PVA (1.5:1) blend membrane and doubling time (td) of Vero cells is proposed. Copyright © 2015 Elsevier Ltd. All rights reserved.

Improvement in Wood Bonding Strength of Poly (Vinyl Acetate-Butyl Acrylate) Emulsion by Controlling the Amount of Redox Initiator

PubMed Central

Zhang, Yun; Pang, Bo; Yang, Sen; Fang, Wei; Yang, Sheng; Yuan, Tong-Qi; Sun, Run-Cang

2018-01-01

Polyvinyl acetate emulsion adhesive has been widely used due to its good bonding performance and environmentally friendly properties. Indeed, the bonding performance can be further improved by copolymerizing with other monomers. In this study, the effect of the adjunction of redox initiator (hydrogen peroxide–tartaric acid, H2O2–TA) on the properties of the poly (vinyl acetate-butyl acrylate) (P (VAc–BA)) emulsion adhesive was investigated. With increasing dosage, the reaction became more complete and the obtained film was more compact, as identified via SEM. The core-shell structure of the emulsion particles was confirmed via TEM. Results indicate that while the initiator content increased from 0.5 to 1.0%, a clearer core-shell structure was obtained and the bonding strength of the plywood improved from 2.34 to 2.97 MPa. With the further incorporation of H2O2–TA (i.e., 1.5%), the bonding performance deteriorated. The optimum wood bonding strength (2.97 MPa) of the prepared P (VAc-BA) emulsion adhesive was even better than that (2.55 MPa) of a commercial PVAc emulsion adhesive, suggesting its potential application for the wood industry. PMID:29316725

Synthesis and characterization of poly(vinyl alcohol) membranes with quaternary ammonium groups for wound dressing.

PubMed

Chen, Kuo-Yu; Lin, Yu-Sheng; Yao, Chun-Hsu; Li, Ming-Hsien; Lin, Jui-Che

2010-01-01

2-[(acryloyloxy)ethyl]Trimethylammonium chloride (AETMAC) was grafted onto poly(vinyl alcohol) (PVA) using ceric ammonium nitrate (CAN) as a redox initiator. A series of graft co-polymer (PVA-g-PAETMAC) membranes with different contents of AETMAC were prepared with a casting method. The incorporation of AETMAC into PVA chains was confirmed by element analysis and Fourier transform infrared spectroscopy. The effects of grafting on the thermal properties, water take, water vapor transmission rate (WVTR), contact angle, antibacterial activity and cytotoxicity of PVA-g-PAETMAC membranes were investigated. The experiment results showed that PVA-g-PAETMAC membrane has a higher equilibrium swelling ratio, surface hydrophilicity and WVTR than pure PVA membrane. Moreover, the higher the content of AETMAC, the higher were equilibrium swelling ratio, surface hydrophilicity and WVTR. In vitro bacterial adhesion study demonstrated a significantly reduced number of Staphylococcus aureus and Escherichia coli on PVA-g-PAETMAC surfaces when compared to PVA surface. In addition, no significant difference in the in vitro cytotoxicity was observed between PVA and PVA-g-PAETMAC membranes. The presence of quaternary ammonium groups did not reduce L929 cell growth. Therefore, the PVA-g-PAETMAC membranes have the potential for wound-dressing application.

Flexible all-solid-state supercapacitors based on graphene/carbon black nanoparticle film electrodes and cross-linked poly(vinyl alcohol)-H2SO4 porous gel electrolytes

NASA Astrophysics Data System (ADS)

Fei, Haojie; Yang, Chongyang; Bao, Hua; Wang, Gengchao

2014-11-01

Flexible all-solid-state supercapacitors (SCs) are fabricated using graphene/carbon black nanoparticle (GCB) film electrodes and cross-linked poly(vinyl alcohol)-H2SO4 porous gel electrolytes (gPVAP-H2SO4). The GCB composite films, with carbon black (CB) nanoparticles uniformly distributed in the graphene nanosheets, greatly improve the active surface areas and ion transportation of pristine graphene film. The porous structure of as-prepared gPVAP-H2SO4 membrane improves the equilibrium swelling ratio in electrolyte and provides interconnected ion transport channels. The chemical crosslinking solves the fluidity problem of PVA-H2SO4 gel electrolyte at high temperature. As-fabricated GCB//gPVAP(20)-H2SO4//GCB flexible SC displays an increased specific capacitance (144.5 F g-1 at 0.5 A g-1) and a higher specific capacitance retention (67.9% from 0.2 to 4 A g-1). More importantly, the flexible SC possesses good electrochemical performance at high temperature (capacitance retention of 78.3% after 1000 cycles at 70 °C).

Tunable Mechanics in Electrospun Composites via Hierarchical Organization.

PubMed

Wanasekara, Nandula D; Matolyak, Lindsay E; Korley, LaShanda T J

2015-10-21

Design strategies from nature provide vital clues for the development of synthetic materials with tunable mechanical properties. Employing the concept of hierarchy and controlled percolation, a new class of polymer nanocomposites containing a montmorillonite (MMT)-reinforced electrospun poly(vinyl alcohol) (PVA) filler embedded within a polymeric matrix of either poly(vinyl acetate) (PVAc) or ethylene oxide-epichlorohydrin copolymer (EO-EPI) were developed to achieve a tunable mechanical response upon exposure to specific stimuli. Mechanical response and switching times upon hydration were shown to be dependent on the weight-fraction of MMT in the PVA electrospun fibers and type of composite matrix. PVA/MMT.PVAc composite films retained excellent two-way switchability for all MMT fractions; however, the switching time upon hydration was decreased dramatically as the MMT content was increased due to the highly hydrophilic nature of MMT. Additionally, for the first time, significant two-way switchability of PVA/MMT.EO-EPI composites was achieved for higher weight fractions (12 wt %) of MMT. An extensive investigation into the effects of fiber diameter, crystallinity, and MMT content revealed that inherent rigidity of MMT platelets plays an important role in controlling the mechanical response of these hierarchical electrospun composites.

Inorganic-organic hybrid coatings on stainless steel by layer-by-layer deposition and surface-initiated atom-transfer-radical polymerization for combating biocorrosion.

PubMed

Yuan, S J; Pehkonen, S O; Ting, Y P; Neoh, K G; Kang, E T

2009-03-01

To improve the biocorrosion resistance of stainless steel (SS) and to confer the bactericidal function on its surface for inhibiting bacterial adhesion and biofilm formation, well-defined inorganic-organic hybrid coatings, consisting of the inner compact titanium oxide multilayers and outer dense poly(vinyl-N-hexylpyridinium) brushes, were successfully developed. Nanostructured titanium oxide multilayer coatings were first built up on the SS substrates via the layer-by-layer sol-gel deposition process. The trichlorosilane coupling agent, containing the alkyl halide atom-transfer-radical polymerization (ATRP) initiator, was subsequently immobilized on the titanium oxide coatings for surface-initiated ATRP of 4-vinylpyridine (4VP). The pyridium nitrogen moieties of the covalently immobilized 4VP polymer, or P(4VP), brushes were quaternized with hexyl bromide to produce a high concentration of quaternary ammonium salt on the SS surfaces. The excellent antibacterial efficiency of the grafted polycations, poly(vinyl-N-pyridinium bromide), was revealed by viable cell counts and atomic force microscopy images of the surface. The effectiveness of the hybrid coatings in corrosion protection was verified by the Tafel plot and electrochemical impedance spectroscopy measurements.

Preparation and characterization of novel biocompatible cryogels of poly (vinyl alcohol) and egg-albumin and their water sorption study.

PubMed

Bajpai, A K; Saini, Rajesh

2006-01-01

Polyvinyl alcohol (PVA) and egg albumin are water-soluble, biocompatible and biodegradable polymers and have been widely employed in biomedical fields. In this paper, novel physically cross-linked hydrogels composed of poly (vinyl alcohol) and egg albumin were prepared by cyclic freezing/thawing processes of aqueous solutions containing PVA and egg albumin. The FTIR analysis of prepared cryogels indicated that egg albumin was successfully introduced into the formed hydrogel possibly via hydrogen bonds among hydroxyl groups, amide groups and amino groups present in PVA and egg albumin. The gels were also characterized thermally and morphologically by DSC and SEM-techniques, respectively. The prepared so called 'cryogels' were evaluated for their water uptake potential and influence of various factors such as chemical architecture of the spongy hydrogels, pH and temperature of the swelling bath were investigated on the degree of water sorption by the cryogels. The effect of salt solution and various simulated biological fluids on the swelling of cryogel was also studied. The in vitro biocompatibility of the prepared cryogel was also judged by methods such as protein (BSA) adsorption, blood clot formation and percentage hemolysis measurements.

Solution spinning of a high-? oxide superconductor: the effect of poly(vinyl alcohol) spinning medium on the critical current density of melt-processed ? superconducting filaments

NASA Astrophysics Data System (ADS)

Tomita, Hisayo; Sunohara, Makoto; Goto, Tomoko; Takahashi, Kiyohisa

1996-12-01

The precursor 0953-2048/9/12/014/img9 filament was prepared by solution spinning through a homogeneous aqueous poly(vinyl alcohol) (PVA) solution of Y, Ba and Cu acetates. The solution spinning was successfully performed using PVA with degrees of polymerization (DP) of 1700 and 2450 and a degree of saponification of 85 mol%. The as-drawn filament was heated to remove volatile components and partially melted to generate a superconducting phase. The effects of the DP of PVA and a content of mixed acetates in the precursor filament on the critical current density 0953-2048/9/12/014/img10 of the melt-processed filament were examined. The higher 0953-2048/9/12/014/img11 was obtained for the filament spun from PVA solution of higher DP and lower acetate content. The highest 0953-2048/9/12/014/img11 value of 0953-2048/9/12/014/img13 at 77 K and 0 T was achieved for the filament spun from the DP 2450 PVA with an acetate to PVA ratio of two.

In situ fabricated platinum—poly(vinyl alcohol) nanocomposite thin film: a highly reusable ‘dip catalyst’ for hydrogenation

NASA Astrophysics Data System (ADS)

Divya Madhuri, U.; Kesava Rao, V.; Hariprasad, E.; Radhakrishnan, T. P.

2016-04-01

A simple protocol for the in situ generation of platinum nanoparticles in a poly(vinyl alcohol) (PVA) thin film is developed. Chloroplatinic acid as well as potassium platinum(II) chloride are used as precursors and the film is fabricated by spin coating followed by mild thermal annealing. The chemical process occurring inside the film, wherein the polymer itself acts as the reducing agent, is explored through different spectroscopy and microscopy techniques. The Pt-PVA film, <100 nm thick and containing ˜1 nm size Pt nanoparticles, is shown to be a highly efficient catalyst for the reduction of methylene blue using sodium borohydride. The ease of retrieval and reuse of the thin film is highlighted by the term ‘dip catalyst’. The reaction yield, kinetics and rate are reproducible through several reuses of the same catalyst film. Turnover number (TON = number of mols of product/number of mols of catalyst) and turnover frequency (TOF = TON/reaction time) are significantly higher than those reported earlier for this reaction using metal nanocatalysts. Utility of Pt-PVA film as an efficient catalyst for other hydrogenation reactions is demonstrated.

Probing the Biomimetic Ice Nucleation Inhibition Activity of Poly(vinyl alcohol) and Comparison to Synthetic and Biological Polymers.

PubMed

Congdon, Thomas; Dean, Bethany T; Kasperczak-Wright, James; Biggs, Caroline I; Notman, Rebecca; Gibson, Matthew I

2015-09-14

Nature has evolved many elegant solutions to enable life to flourish at low temperatures by either allowing (tolerance) or preventing (avoidance) ice formation. These processes are typically controlled by ice nucleating proteins or antifreeze proteins, which act to either promote nucleation, prevent nucleation or inhibit ice growth depending on the specific need, respectively. These proteins can be expensive and their mechanisms of action are not understood, limiting their translation, especially into biomedical cryopreservation applications. Here well-defined poly(vinyl alcohol), synthesized by RAFT/MADIX polymerization, is investigated for its ice nucleation inhibition (INI) activity, in contrast to its established ice growth inhibitory properties and compared to other synthetic polymers. It is shown that ice nucleation inhibition activity of PVA has a strong molecular weight dependence; polymers with a degree of polymerization below 200 being an effective inhibitor at just 1 mg.mL(-1). Other synthetic and natural polymers, both with and without hydroxyl-functional side chains, showed negligible activity, highlighting the unique ice/water interacting properties of PVA. These findings both aid our understanding of ice nucleation but demonstrate the potential of engineering synthetic polymers as new biomimetics to control ice formation/growth processes.

Probing the Biomimetic Ice Nucleation Inhibition Activity of Poly(vinyl alcohol) and Comparison to Synthetic and Biological Polymers

PubMed Central

2015-01-01

Nature has evolved many elegant solutions to enable life to flourish at low temperatures by either allowing (tolerance) or preventing (avoidance) ice formation. These processes are typically controlled by ice nucleating proteins or antifreeze proteins, which act to either promote nucleation, prevent nucleation or inhibit ice growth depending on the specific need, respectively. These proteins can be expensive and their mechanisms of action are not understood, limiting their translation, especially into biomedical cryopreservation applications. Here well-defined poly(vinyl alcohol), synthesized by RAFT/MADIX polymerization, is investigated for its ice nucleation inhibition (INI) activity, in contrast to its established ice growth inhibitory properties and compared to other synthetic polymers. It is shown that ice nucleation inhibition activity of PVA has a strong molecular weight dependence; polymers with a degree of polymerization below 200 being an effective inhibitor at just 1 mg.mL–1. Other synthetic and natural polymers, both with and without hydroxyl-functional side chains, showed negligible activity, highlighting the unique ice/water interacting properties of PVA. These findings both aid our understanding of ice nucleation but demonstrate the potential of engineering synthetic polymers as new biomimetics to control ice formation/growth processes PMID:26258729

Fabrication of biomimetic superhydrophobic surface using hierarchical polyaniline spheres.

PubMed

Dong, Xiaofei; Wang, Jixiao; Zhao, Yanchai; Wang, Zhi; Wang, Shichang

2011-06-01

Wettability and water-adhesion behavior are the most important properties of solid surfaces from both fundamental and practical aspects. Here, the biomimetic superhydrophobic surface was fabricated via a simple coating process using polyaniline (PANI) microspheres which is covered with PANI nanowires as functional component, and poly-vinyl butyral (PVB, poly-vinyl alcohol crosslinked with n-butylaldehyde) as PANI microsphere adhering improvement agent to the substrate. The obtained surface displays superhydrophobic behavior without any modification with low-surface-energy materials such as thiol- or fluoroalkylsilane. The effects of coating process and the content of PANI microspheres on superhydropbobic behavior were discussed. Combine contact angle, water-adhesion measurements, scanning electronic microscopy (SEM) observations with selected areas energy dispersion spectrometer (EDS), the hydrophobic mechanism was proposed. The superhydrophobicity is attributed to a hierarchical morphology of PANI microspheres and the nature of the material itself. In addition, induced by van der Waals forces, the created superhydrophobic surface here shows the strong water-adhesion behavior. The surface has the combination performance of Lotus leaf and gecko's pad. The special wettability would be of great significance to the liquid microtransport in microfluid devices. The experimental results show that the ordinary coating process is a facile approach for fabrication of superhydrophobic surfaces.

Preparation and characterization of oriented poly(vinyl alcohol)/carbon nanotube composite nanofibers

NASA Astrophysics Data System (ADS)

Shimizu, Akikazu; Kato, Hayato; Sato, Taiga; Kushida, Masahito

2017-07-01

Oriented nanofiber mats blended with carbon nanotubes (CNTs) are expected to be applied as cell seeding scaffolds. Biomaterials that are often used for cell seeding scaffolds generally have low mechanical strength and low electrical conductivity; thus, it has been difficult to apply them to tissues such as heart and nerve. In this study, we prepared oriented poly(vinyl alcohol) (PVA) nanofiber mats blended with various CNT concentrations (up to 10 wt %) by electrospinning using the parallel plate electrodes as collectors with applied voltage. The morphology, mechanical properties, and electrical properties of the prepared oriented nanofiber mats were measured by using various techniques such as scanning electron microscopy (SEM). The tensile strength of the oriented nanofiber mats in the applied voltage direction increased from 2.5 to 9.7 MPa with CNT concentration. Furthermore, the electrical conductivity of the oriented nanofiber mats in the applied voltage direction increased from 0.67 × 10-7 to 4.3 × 10-7 S·m-1. Also, the mechanical strength and electrical conductivity of the oriented nanofiber mats in the applied voltage direction were 3-4 and 2-3 times higher than those in the perpendicular direction, respectively.

Superabsorbent hydrogel composite based on copolymer cellulose/poly (vinyl alcohol)/CNT

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

Khoerunnisa, Fitri, E-mail: fitri.khoerunnisa@gmail.com; Hendrawan,; Sonjaya, Yaya

2016-04-19

Superabsorbent hydrogels are cross-linked hydrophilic polymers that can absorb and retain a large volume of water, saline solution, or physiological fluids. A distinctive superabsorbent hydrogel composite based on cellulose/ poly (vinyl alcohol)/ carbon nanotubes was successfully synthesized via the graft bio-copolymerization in an aqueous medium with glutaraldehide as a crosslinking agent. The effect of carbon nanotubes (CNT) on water absorption capacity and mechanical properties of superabsorbent composite were particularly investigated. The Fourier transform infrared spectra showed the evidence of copolymerization of hydrogel precursors as well as the interaction of CNT filler with the hydrogel matrices, as indicated by the shiftingmore » of peak intensity and position of several functional groups (O-H, C-H sp{sup 3}, C=O, C-N, C-O). The modification of hydrogel surface morphology and porosity owing to CNT insertion was also confirmed by scanning electron microscopy images. The CNT insertion improved the mechanical strength of superabsorbent hydrogel composites. Moreover, insertion of CNT into hydrogel matrix remarkably increased the swelling capacity of superabsorbent composites up to 840%. This huge water absorption capacity of hydrogel composites offers promising applications in development of superabsorbent polymers.« less

A comparative study of nano-SiO2 and nano-TiO2 fillers on proton conductivity and dielectric response of a silicotungstic acid-H3PO4-poly(vinyl alcohol) polymer electrolyte.

PubMed

Gao, Han; Lian, Keryn

2014-01-08

The effects of nano-SiO2 and nano-TiO2 fillers on a thin film silicotungstic acid (SiWA)-H3PO4-poly(vinyl alcohol) (PVA) proton conducting polymer electrolyte were studied and compared with respect to their proton conductivity, environmental stability, and dielectric properties, across a temperature range from 243 to 323 K. Three major effects of these fillers have been identified: (a) barrier effect; (b) intrinsic dielectric constant effect; and (c) water retention effect. Dielectric analyses were used to differentiate these effects on polymer electrolyte-enabled capacitors. Capacitor performance was correlated to electrolyte properties through dielectric constant and dielectric loss spectra. Using a single-ion approach, proton density and proton mobility of each polymer electrolyte were derived as a function of temperature. The results allow us to deconvolute the different contributions to proton conductivity in SiWA-H3PO4-PVA-based electrolytes, especially in terms of the effects of fillers on the dynamic equilibrium of free protons and protonated water in the electrolytes.

Nanostructured starch combined with hydroxytyrosol in poly(vinyl alcohol) based ternary films as active packaging system.

PubMed

Luzi, Francesca; Fortunati, Elena; Di Michele, Alessandro; Pannucci, Elisa; Botticella, Ermelinda; Santi, Luca; Kenny, José Maria; Torre, Luigi; Bernini, Roberta

2018-08-01

Novel ternary films have been realized by using poly(vinyl alcohol) (PVA) as polymeric matrix, nanostructured starch as reinforcement phase and hydroxytyrosol (HTyr), a low-molecular phenolic compound present in olive oil, as antioxidant agent. Nanostructured starch, in the form of starch nanocrystals (NC) and nanoparticles (NP) obtained by acid hydrolysis and ultrasound irradiation of starch derived from the bread wheat variety Cadenza (WT, amylose content 33%) and a derived-high amylose line (HA, amylose content 75%), was considered. The developed multifunctional films were characterized in terms of morphological, thermal and optical properties, water absorption capacity, overall and specific migration into a food simulant and antioxidant properties. Experimental data showed a prolonged release of HTyr from all ternary films and the released HTyr retained a strong antioxidant activity. The data, compared to those of PVA/HTyr binary films, demonstrated the key role of nanostructured starch in the ternary formulations in promoting a gradual release of HTyr. Overall, PVA fillm combined with nanoparticles from low amylose starch and hydroxytyrosol resulted as the most promising ternary formulation for food packaging applications. Copyright © 2018 Elsevier Ltd. All rights reserved.

Poly(vinyl alcohol) gels as photoacoustic breast phantoms revisited.

PubMed

Xia, Wenfeng; Piras, Daniele; Heijblom, Michelle; Steenbergen, Wiendelt; van Leeuwen, Ton G; Manohar, Srirang

2011-07-01

A popular phantom in photoacoustic imaging is poly(vinyl alcohol) (PVA) hydrogel fabricated by freezing and thawing (F-T) aqueous solutions of PVA. The material possesses acoustic and optical properties similar to those of tissue. Earlier work characterized PVA gels in small test specimens where temperature distributions during F-T are relatively homogeneous. In this work, in breast-sized samples we observed substantial temperature differences between the shallow regions and the interior during the F-T procedure. We investigated whether spatial variations were also present in the acoustic and optical properties. The speed of sound, acoustic attenuation, and optical reduced scattering coefficients were measured on specimens sampled at various locations in a large phantom. In general, the properties matched values quoted for breast tissue. But while acoustic properties were relatively homogeneous, the reduced scattering was substantially different at the surface compared with the interior. We correlated these variations with gel microstructure inspected using scanning electron microscopy. Interestingly, the phantom's reduced scattering spatial distribution matches the optical properties of the standard two-layer breast model used in x ray dosimetry. We conclude that large PVA samples prepared using the standard recipe make excellent breast tissue phantoms.

Preparation and characterization of a magneto-polymeric nanocomposite: Fe 3O 4 nanoparticles in a grafted, cross-linked and plasticized poly(vinyl chloride) matrix

NASA Astrophysics Data System (ADS)

Rodríguez-Fernández, Oliverio S.; Rodríguez-Calzadíaz, C. A.; Yáñez-Flores, Isaura G.; Montemayor, Sagrario M.

In this work two kind of materials: (1) grafted, cross-linked and plasticized poly(vinyl chloride) (PVC) "plastic films" and (2) magnetic plastic films "magneto-polymeric nanocomposites" were prepared. Precursor solutions or "plastisols" used to obtain the plastic films were obtained by mixing PVC (emulsion grade) as polymeric matrix, di(2-ethylhexyl)phthalate (DOP) as plasticizer, a thermal stabilizer based in Ca/Zn salts, and a cross-linking agent, 3-mercaptopropyltrimethoxysilane (MTMS) or 3-aminopropyltriethoxysilane (ATES), at several concentrations. Flexible films were obtained from the plastisols using static casting. The stress-strain behavior and the gel content (determined by Soxhlet extraction with boiling THF) of the flexible films were measured in order to evaluate the effect of the cross-linking agent and their content on the degree of cross-linking. The magneto-polymeric nanocomposites were obtained by mixing the optimum composition of the plastisols (analyzed previously) with magnetite (Fe 3O 4)-based ferrofluid and DOP. Later, flexible films were obtained by static casting of the plastisol/ferrofluid systems. The magnetic films were characterized by the above-mentioned techniques and X-ray diffraction, vibrating sample magnetometry and thermogravimetrical analysis.

Shape Memory Composites Based on Electrospun Poly(vinyl alcohol) Fibers and a Thermoplastic Polyether Block Amide Elastomer.

PubMed

Shirole, Anuja; Sapkota, Janak; Foster, E Johan; Weder, Christoph

2016-03-01

The present study aimed at developing new thermally responsive shape-memory composites, that were fabricated by compacting mats of electrospun poly(vinyl alcohol) (PVA) fibers and sheets of a thermoplastic polyether block amide elastomer (PEBA). This design was based on the expectation that the combination of the rubber elasticity of the PEBA matrix and the mechanical switching exploitable through the reversible glass transition temperature (Tg) of the PVA filler could be combined to create materials that display shape memory characteristics as an emergent effect. Dynamic mechanical analyses (DMA) show that, upon introduction of 10-20% w/w PVA fibers, the room-temperature storage modulus (E') increased by a factor of 4-5 in comparison to the neat PEBA, and they reveal a stepwise reduction of E' around the Tg of PVA (85 °C). This transition could indeed be utilized to fix a temporary shape and recover the permanent shape. At low strain, the fixity was 66 ± 14% and the recovery was 98 ± 2%. Overall, the data validate a simple and practical strategy for the fabrication of shape memory composites that involves a melt compaction process and employs two commercially available polymers.

Graphene-poly(vinyl alcohol) composites: Fabrication, adsorption and electrochemical properties

NASA Astrophysics Data System (ADS)

Wang, Ning; Chang, Peter R.; Zheng, Pengwu; Ma, Xiaofei

2014-09-01

Porous composites of graphene oxide (GO)-poly(vinyl alcohol) (PVA) were fabricated using a process of aqueous suspension precursor freezing, solvent exchange, and ethanol drying. When frozen, ice crystals formed leaving a porous structure, composed of randomly oriented GO sheets consolidated by PVA. The yellow GO-PVA composite could be reduced with glucose to obtain a black porous RGO (PRGO). XRD revealed that PVA enlarged the GO interlay spacing in the GO-PVA composite, and that RGO sheets were highly disordered in single or several layers in PRGO. GO-PVA and PRGO exhibited ultralight densities of 10.52 and 11.42 mg/cm3, respectively. GO-PVA adsorbed greater quantities of water, ethanol, and soybean oil than PRGO. The methylene blue (MB) adsorption pattern for both materials was also investigated. The kinetic adsorption and isotherm data fit the pseudo second-order and the Langmuir models, respectively. The maximum adsorption capacity according to the Langmuir isotherm model was 571.4 mg/g for GO-PVA. The electrochemical properties of PRGO were estimated using cyclic voltammetry, electrochemical impedance spectrometry, and chronopotentiometry. The PRGO electrode exhibited large capacitance (82.8 F/g) and small internal resistance (0.52 Ω).

Negligible seeding source effect on the final ANAMMOX community under steady and high nitrogen loading rate after enrichment using poly(vinyl alcohol) gel carriers.

PubMed

Cho, Kyungjin; Choi, Minkyu; Lee, Seockheon; Bae, Hyokwan

2018-05-26

This study investigated the effect of seeding source on the mature anaerobic ammonia oxidation (ANAMMOX) bacterial community niche in continuous poly(vinyl alcohol) (PVA) gel systems operated under high nitrogen loading rate (NLR) condition. Four identical column reactors packed with PVA gels were operated for 182 d using different seeding sources which had distinct community structures. The ANAMMOX reaction was achieved in all the bioreactors with comparable total and ANAMMOX bacterial 16S rRNA gene quantities. The bacterial community structure of the bioreactors became similar during operation; some major bacteria were commonly found. Interestingly, one ANAMMOX species, "Candidatus Brocadia sinica", was conclusively predominant in all the bioreactors, even though different seeding sludges were used as inoculum source, possibly due to the unique physiological characteristics of "Ca. Brocadia sinica" and the operating conditions (i.e., PVA gel-based continuous system and 1.0 kg-N/(m 3 ·d) of NLR). The results clearly suggest that high NLR condition is a more significant factor determining the final ANAMMOX community niche than is the type of seeding source. Copyright © 2018 Elsevier Ltd. All rights reserved.

Investigation of Zinc Oxide-Loaded Poly(Vinyl Alcohol) Nanocomposite Films in Tailoring Their Structural, Optical and Mechanical Properties

NASA Astrophysics Data System (ADS)

Aslam, Muhammad; Kalyar, Mazhar Ali; Raza, Zulfiqar Ali

2018-04-01

Wurtzite ZnO nanoparticles, as a nanofiller, were incorporated in a poly(vinyl alcohol) (PVA) matrix to prepare multipurpose nanocomposite films using a solution casting approach. Some advanced analytical techniques were used to investigate the properties of prepared nanocomposite films. The mediation of ZnO nanofillers resulted in modification of structural, optical and mechanical properties of nanocomposite films. A comprehensive band structure investigation might be useful for designing technological applications like in optoelectronic devices. The experimental results were found to be closely dependent on the nanofiller contents. Some theoretical models like Tauc's and Wemple-DiDomenico, were employed to investigate the band structure parameters. The imaginary part of the dielectric constant was used to investigate the band gap. Then, the Helpin-Tsai model was employed to predict Young's moduli of the prepared nanocomposite films. On 3 wt.% ZnO nanofiller loading, the optical band gap of the PVA-based nanocomposite film was decreased from 5.26 eV to 3 eV, the tensile strength increased from 25.3 MPa to 48 MPa and Young's modulus increased from 144 MPa to 544 MPa.

Cold Spray Coating of Submicronic Ceramic Particles on Poly(vinyl alcohol) in Dry and Hydrogel States

NASA Astrophysics Data System (ADS)

Moreau, David; Borit, François; Corté, Laurent; Guipont, Vincent

2017-06-01

We report an approach using cold spray technology to coat poly(vinyl alcohol) (PVA) in polymer and hydrogel states with hydroxyapatite (HA). Using porous aggregated HA powder, we hypothesized that fragmentation of the powder upon cold spray could lead to formation of a ceramic coating on the surface of the PVA substrate. However, direct spraying of this powder led to complete destruction of the swollen PVA hydrogel substrate. As an alternative, HA coatings were successfully produced by spraying onto dry PVA substrates prior to swelling in water. Dense homogeneous HA coatings composed of submicron particles were obtained using rather low-energy spraying parameters (temperature 200-250 °C, pressure 1-3 MPa). Coated PVA substrates could swell in water without removal of the ceramic layer to form HA-coated hydrogels. Microscopic observations and in situ measurements were used to explain how local heating and impact of sprayed aggregates induced surface roughening and strong binding of HA particles to the molten PVA substrate. Such an approach could lead to design of ceramic coatings whose roughness and crystallinity can be finely adjusted to improve interfacing with biological tissues.

Investigation of Zinc Oxide-Loaded Poly(Vinyl Alcohol) Nanocomposite Films in Tailoring Their Structural, Optical and Mechanical Properties

NASA Astrophysics Data System (ADS)

Aslam, Muhammad; Kalyar, Mazhar Ali; Raza, Zulfiqar Ali

2018-07-01

Wurtzite ZnO nanoparticles, as a nanofiller, were incorporated in a poly(vinyl alcohol) (PVA) matrix to prepare multipurpose nanocomposite films using a solution casting approach. Some advanced analytical techniques were used to investigate the properties of prepared nanocomposite films. The mediation of ZnO nanofillers resulted in modification of structural, optical and mechanical properties of nanocomposite films. A comprehensive band structure investigation might be useful for designing technological applications like in optoelectronic devices. The experimental results were found to be closely dependent on the nanofiller contents. Some theoretical models like Tauc's and Wemple-DiDomenico, were employed to investigate the band structure parameters. The imaginary part of the dielectric constant was used to investigate the band gap. Then, the Helpin-Tsai model was employed to predict Young's moduli of the prepared nanocomposite films. On 3 wt.% ZnO nanofiller loading, the optical band gap of the PVA-based nanocomposite film was decreased from 5.26 eV to 3 eV, the tensile strength increased from 25.3 MPa to 48 MPa and Young's modulus increased from 144 MPa to 544 MPa.

Di-(2-ethylhexyl)-phthalate migration from irradiated poly(vinyl chloride) blood bags for graft-vs-host disease prevention.

PubMed

Ferri, Marcella; Marcella, Ferri; Chiellini, Federica; Federica, Chiellini; Pili, Giorgio; Giorgio, Pili; Grimaldi, Luca; Luca, Grimaldi; Florio, Elena Tiziana; Pili, Stefania; Stefania, Pili; Cucci, Francesco; Francesco, Cucci; Latini, Giuseppe; Giuseppe, Latini

2012-07-01

Irradiation with 20-25 kGy is a process commonly used for sterilizing poly(vinyl chloride) (PVC) medical devices. Moreover, whole blood and blood components undergo additional irradiation with 25-50 Gy to inhibit the proliferative capacity of lymphocytes and reduce the risk of transfusion-associated graft-vs-host disease (GVHD). Di-(2-ethylhexyl)-phthalate (DEHP) plasticized PVC is extensively used for the production of flexible medical devices including blood bags, but since DEHP is not covalently bound to PVC, it tends to migrate and leach out of the medical device, with harmful consequences for the patients. In this study, the effects of different doses of gamma irradiation on DEHP migration from PVC blood bags was investigated using differential scanning calorimetry (DSC) analysis. Our findings indicate that irradiation with 25-100 Gy reduces the ability of DEHP to migrate from the blood bags, and in the case of a primary container a correlation between the doses of gamma ray irradiation was also observed. In particular, a decrease in DEHP leachability was obtained by increasing the dose of gamma ray irradiation. Copyright © 2012 Elsevier B.V. All rights reserved.

Sugar-Responsive Layer-by-Layer Film Composed of Phenylboronic Acid-Appended Insulin and Poly(vinyl alcohol).

PubMed

Takei, Chihiro; Ohno, Yui; Seki, Tomohiro; Miki, Ryotaro; Seki, Toshinobu; Egawa, Yuya

2018-01-01

Previous studies have shown that reversible chemical bond formation between phenylboronic acid (PBA) and 1,3-diol can be utilized as the driving force for the preparation of layer-by-layer (LbL) films. The LbL films composed of a PBA-appended polymer and poly(vinyl alcohol) (PVA) disintegrated in the presence of sugar. This type of LbL films has been recognized as a promising approach for sugar-responsive drug release systems, but an issue preventing the practical application of LbL films is combining them with insulin. In this report, we have proposed a solution for this issue by using PBA-appended insulin as a component of the LbL film. We prepared two kinds of PBA-appended insulin derivatives and confirmed that they retained their hypoglycemic activity. The LbL films composed of PBA-appended insulin and PVA were successfully prepared through reversible chemical bond formation between the boronic acid moiety and the 1,3-diol of PVA. The LbL film disintegrated upon treatment with sugars. Based on the results presented herein, we discuss the suitability of the PBA moiety with respect to hypoglycemic activity, binding ability, and selectivity for D-glucose.

Evaluation of the density of the charge trapped in organic ferroelectric capacitors based on the Mott-Schottky model

NASA Astrophysics Data System (ADS)

Kim, Won-Ho; Kwon, Jin-Hyuk; Park, Gyeong-Tae; Kim, Jae-Hyun; Bae, Jin-Hyuk; Zhang, Xue; Park, Jaehoon

2014-09-01

Organic ferroelectric capacitors were fabricated using pentacene and poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE) as an organic semiconductor and a ferroelectric material, respectively. A paraelectric poly(vinyl cinnamate) layer was adopted as an interlayer between the PVDF-TrFE layer and the bottom electrode. The paraelectric interlayer induced a depolarization field opposite to the direction of the polarization formed in the ferroelectric PVDF-TrFE insulator, thereby suppressing spontaneous polarization. As a result, the Mott-Schottky model could be used to evaluate, from the extracted flat-band voltages, the density of the charge trapped in the organic ferroelectric capacitors.

The chemistry of dimethacrylate-styrene networks, and, Development of flame retardant, halogen-free fiber reinforced vinyl ester composites

NASA Astrophysics Data System (ADS)

Rosario, Astrid Christa

One of the major classes of polymer matrix resins under consideration for structural composite applications in the infrastructure and construction industries is vinyl ester resin. Vinyl ester resin is comprised of low molecular weight poly(hydroxyether) oligomers with methacrylate endgroups diluted with styrene monomer. The methacrylate endgroups cure with styrene via free radical copolymerization to yield thermoset networks. The copolymerization behavior of these networks was monitored by Fourier Transform Infrared Spectroscopy (FTIR) at various cure conditions. Reactions of the carbon-carbon double bonds of the methacrylate (943 cm-1) and styrene (910 cm-1 ) were followed independently. Oligomers possessing number average molecular weights of 700 g/mole were studied with systematically increasing levels of styrene. The Mortimer-Tidwell reactivity ratios indicated that at low conversion more styrene was incorporated into the network at lower cure temperatures. The experimental vinyl ester-styrene network compositions deviated significantly from those predicted by the Meyer-Lowry integrated copolymer equation at higher conversion, implying that the reactivity ratios for these networks may change with conversion. The kinetic data were used to provide additional insight into the physical and mechanical properties of these materials. In addition to establishing the copolymerization kinetics of these materials, the development of halogen free fiber reinforced vinyl ester composites exhibiting good flame properties was of interest. Flame retardant vinyl ester resins are used by many industries for applications requiring good thermal resistance. The current flame-retardant technology is dependent on brominated vinyl esters, which generate high levels of smoke and carbon monoxide. A series of halogen free binder systems has been developed and dispersed in the vinyl ester to improve flame retardance. The binder approach enables the vinyl ester resin to maintain its low temperature viscosity so that fabrication of composites via Vacuum Assisted Resin Transfer Molding (VARTM) is possible. The first binder system investigated was a polycaprolactone layered silicate nanocomposite, which was prepared via intercalative polymerization. Transmission Electron Microscopy (TEM) and X-ray Diffraction (XRD) data indicated a mixed morphology of exfoliated and intercalated structures. The mechanical properties and the normalized peak heat release rates were comparable to the neat vinyl ester resin. Alternative binder systems possessing inherent flame retardance were also investigated. A series of binders comprised of novolac, bisphenol A diphosphate, and montmorillonite clay were developed and dispersed into the vinyl ester matrix. Cone calorimetry showed reductions in the peak heat release rate comparable to the brominated resin. Keywords: dimethacrylate; vinyl ester; network; reactivity ratios; nanocomposites; layered silicates; exfoliated; thermoset matrix resin; flame retardant

Poly(4-vinylphenylboronic acid) functionalized polypyrrole/graphene oxide nanosheets for simultaneous electrochemical determination of catechol and hydroquinone

NASA Astrophysics Data System (ADS)

Mao, Hui; Liu, Meihong; Cao, Zhenqian; Ji, Chunguang; Sun, Ying; Liu, Daliang; Wu, Shuyao; Zhang, Yu; Song, Xi-Ming

2017-10-01

Novel poly(4-vinylphenylboronic acid) (P4VPBA) functionalized polypyrrole/graphene oxide (PPy/GO) nanosheets, which combined the advantages of GO, PPy and PBA groups, were successfully prepared by a simple polymerization of 4-vinylphenylboronic acid (4VPBA) on the surface of pre-treated PPy/GO containing vinyl groups. Because of the synergistic effects of GO with excellent 2D structures and large surface area, PPy with good electronic conductivity and PBA with high recognition capability, P4VPBA/PPy/GO modified glassy carbon electrode presented excellent electrochemical sensing capabilities toward catechol (CC) and hydroquinone (HQ) with good stability, high sensitivity and selectivity, especially giving a large anodic peak potential difference between CC and HQ enough to well distinguish and simultaneously determine the two dihydroxybenzene isomers in their mixture. It is found that PBA groups on the surface of P4VPBA/PPy/GO nanosheets played an essential role for the discrimination and simultaneous electrochemical determination of CC and HQ, which may be due to the selective formation of stable cyclic esters by the covalent interaction between PBA groups and related molecules with a cis-diol in an alkaline aqueous solution. Therefore, P4VPBA/PPy/GO nanosheets can act as a good electrode material for building a steady electrochemical sensor for detecting the two dihydroxybenzene isomers with high sensitivity and selectivity.

21 CFR 177.1635 - Poly(p-methylstyrene) and rubber-modified poly(p-methyl-styrene).

Code of Federal Regulations, 2011 CFR

2011-04-01

... polymerization of p-methylstyrene. (2) Rubber-modified poly(p-methylstyrene) (CAS Reg. No. 33520-88-6) polymer... during or after polymerization of the poly(p-methylstyrene), such that the finished polymers contain not...

Grafting of styrene into pre-irradiated fluoropolymer films: Influence of base material and irradiation temperature

NASA Astrophysics Data System (ADS)

Lappan, Uwe; Geißler, Uwe; Gohs, Uwe; Uhlmann, Steffi

2010-10-01

In this study, the influence of irradiation temperature on mechanical properties of three fluoropolymers and on grafting of styrene into the polymers by the pre-irradiation method was investigated. Electron paramagnetic resonance spectroscopy and infrared spectroscopy were used to characterize the irradiated polymers regarding trapped radical species and changes in the chemical structure, respectively. For poly(tetrafluoroethylene-co-perfluoropropyl vinyl ether) (PFA) the irradiation temperature was found to be an important factor for tensile strength and elongation at break of the pre-irradiated film. No strong effect of irradiation temperature on the mechanical properties was noticed for poly(tetrafluoroethylene-co-ethylene) (ETFE); however the yield of grafting drops at high irradiation temperatures. Finally, mechanical properties of poly(tetrafluoroethylene) (PTFE) were found to be dramatically altered, even if the film was irradiated at elevated temperature.

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

Peterson, R.C.; Garard, R.J.; Lokhandwala, K.K.

The crush behavior (specific energy absorption and crush load stability) of unidirectional fiber composite rods having tougher matrices than vinyl ester were investigated and compared with the crush behavior of similar specimens having a vinyl ester matrix. The matrices were a cyclic polyester and two rubber-toughened vinyl esters. The specific energy absorption with the cyclic polyester matrix, 180 MJ/m{sup 3}, was slightly lower than that with the vinyl ester matrix, 230 MJ/m{sup 3}. On the other hand, the crush stability was markedly better. The average deviation of the crush load about the mean was as small as 3.5% with themore » cyclic polyester matrix, in contrast to about 12% with the vinyl ester matrix. The higher ductility of the cyclic polyester and the good fiber-matrix bond strength together resulted in less fracturing of the matrix and more uniform kink-band formation across the composite cross section than occurred with the vinyl ester matrix. There was also a reduction in the tendency for fibers at the periphery of the rod to splay outward rather than being crushed. Of the two rubber-toughened vinyl ester matrices, a 30% reduction was found in the average deviation of the crush load about the mean with the matrix toughened with a core-shell material, although no improvement was found with the CTBN rubber-modified vinyl ester resin.« less

Synthesis of PVP-stabilized ruthenium colloids with low boiling point alcohols.

PubMed

Zhang, Yuqing; Yu, Jiulong; Niu, Haijun; Liu, Hanfan

2007-09-15

A route to the preparation of poly(N-vinyl-2-pyrrolidone) (PVP)-stabilized ruthenium colloids by refluxing ruthenium(III) chloride in low boiling point alcohols was developed. Deep purple colloids with shuttle-like ruthenium particles were also synthesized. XPS measurement verified the nanoparticles were in the metallic state. The morphology of metal nanoparticles was characterized by UV-visible absorption spectrophotometry, TEM and XRD.

Graphitic carbon stabilized silver nanoparticles synthesized by a simple chemical precursor method

NASA Astrophysics Data System (ADS)

Soni, Bhasker; Biswas, Somnath

2018-04-01

Monodispersed graphitic carbon stabilized silver nanoparticles (AgNPs) were synthesized following a simple chemical precursor method. The precursor was obtained by a controlled reduction of Ag+ in aqueous solution of poly-vinyl alcohol (PVA) and sucrose. The process allows precise control over the morphology of the AgNPs along with in situ formation of a surface stabilization layer of graphitic carbon.

Dual UV/thermally curable plastisols

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

Morgan, C.R.

1983-10-01

Photoactive, thermally curable plastisol compositions are made by mixing a thermoplastic (preferably poly(vinyl chloride)), a (meth)acrylate, a thermal initiator, a photoinitiator, and a conventional plasticizer. A short exposure of these compositions to UV results in a tack-free skin cure. Heating after UV irradiation gives simultaneous crosslinking and fusion. These dual UV/thermally curable plastisols are useful as adhesives, sealants, encapsulants, and in many other applications.

Development of structure in natural silk spinning and poly(vinyl alcohol) hydrogel formation

NASA Astrophysics Data System (ADS)

Willcox, Patricia Jeanene

This research involves the characterization of structure and structure formation in aqueous systems. Particularly, these studies investigate the effect of various processing variables on the structure formation that occurs upon conversion from aqueous solution to fiber or hydrogel. The two processes studied include natural silk fiber spinning and physical gelation of poly(vinyl alcohol), PVOH, in water. The techniques employed combine cryogenic technology for sample preparation and direct observation by transmission electron microscopy with electron diffraction, atomic force microscopy, optical rheometry, X-ray scattering and optical microscopy. In order to explore the full range of structure formation in natural silk spinning, studies are conducted in vivo and in vitro. In vivo structural investigations are accomplished through the cryogenic quenching and subsequent microtoming of live silk-spinning animals, Nephila clavipes (spider) and Bombyx mori (silkworm). Observations made using transmission electron microscopy, electron diffraction and atomic force microscopy indicate a cholesteric liquid crystalline mesophase of aqueous silk fibroin in both species. The mechanism of structure formation in solution is studied in vitro using optical rheometry on aqueous solutions made from regenerated Bombyx mori cocoon silk. Concentrated solutions exhibit birefringence under flow, with a wormlike conformation of the silk molecules in concentrated salt solution. Changes in salt concentration and pH of the aqueous silk solutions result in differing degrees of alignment and aggregation. These results suggest that structural control in the natural silk spinning process is accomplished by chemical manipulation of the electrostatic interactions and hydrogen bonding between chains. Application of cryogenic methods in transmission electron microscopy also provides a unique look at hydration-dependent structures in gels of poly(vinyl alcohol) produced by freeze-thaw processing. Morphologies ranging from circular pores to fibrillar networks are observed in gels formed from aqueous PVOH solutions subjected to cycles of freezing and thawing. These morphologies can be directly associated with the progressive nature of the mechanism of gelation as it proceeds from liquid-liquid phase separation to crystallization with increased cycling. A comparison of the structures produced by cycling and by aging suggests that there is a similarity in structural changes, but a superposition of the effects of cycling and aging is not possible.

Multiscale Modeling of Thermal Conductivity of Polymer/Carbon Nanocomposites

NASA Technical Reports Server (NTRS)

Clancy, Thomas C.; Frankland, Sarah-Jane V.; Hinkley, Jeffrey A.; Gates, Thomas S.

2010-01-01

Molecular dynamics simulation was used to estimate the interfacial thermal (Kapitza) resistance between nanoparticles and amorphous and crystalline polymer matrices. Bulk thermal conductivities of the nanocomposites were then estimated using an established effective medium approach. To study functionalization, oligomeric ethylene-vinyl alcohol copolymers were chemically bonded to a single wall carbon nanotube. The results, in a poly(ethylene-vinyl acetate) matrix, are similar to those obtained previously for grafted linear hydrocarbon chains. To study the effect of noncovalent functionalization, two types of polyethylene matrices. -- aligned (extended-chain crystalline) vs. amorphous (random coils) were modeled. Both matrices produced the same interfacial thermal resistance values. Finally, functionalization of edges and faces of plate-like graphite nanoparticles was found to be only modestly effective in reducing the interfacial thermal resistance and improving the composite thermal conductivity

Green-Yellow Electroluminescence from a host-dopant blended system as the active layer in a bilayer polymer light emitting diode: Poly(n-vinyl carbazole) as the host and a new soluble thiophene based copolymer [poly(2,2‧-BT)-co-(3-DDT)] as the dopant

NASA Astrophysics Data System (ADS)

Shahalizad, Afshin; Ahmadi-Kandjani, Sohrab; Movla, Hossein; Omidi, Hafez; Massoumi, Bakhshali; Zakerhamidi, Mohammad Sadegh; Entezami, Ali Akbar

2014-11-01

A new type of bilayer Polymer Light Emitting Diode (PLED) which emits green-yellow light is reported. In this PLED, a novel thiophene-based copolymer [poly(2,2‧-BT)-co-(3-DDT)] with an excellent electron transporting property has been doped in hole transporting and electron blocking poly(n-vinylcarbazole) (PVK). Formation of type-II heterojunctions among nm-size features in PVK:poly(2,2‧-BT)-co-(3-DDT) blended system makes exciplex and electroplex emissions would be dominant in the Electroluminescence (EL) spectrum of the device. These cross recombinations between electrons in the LUMO of poly(2,2‧-BT)-co-(3-DDT) and holes in the HOMO of PVK is a reason for the low driving voltage of the PLED because there is no need for the charge carriers to hop or tunnel to the adjacent polymer. Morphological investigations demonstrate that the mixing degree between the components is high, favoring formation of exciplexes and electroplexes at the interface of the components.

Development of polyether urethane intravaginal rings for the sustained delivery of hydroxychloroquine

PubMed Central

Chen, Yufei; Traore, Yannick Leandre; Li, Amanda; Fowke, Keith R; Ho, Emmanuel A

2014-01-01

Hydroxychloroquine (HCQ) has been shown to demonstrate anti-inflammatory properties and direct anti-HIV activity. In this study, we describe for the first time the fabrication and in vitro evaluation of two types of intravaginal ring (IVR) devices (a surfaced-modified matrix IVR and a reservoir segmental IVR) for achieving sustained delivery (>14 days) of HCQ as a strategy for preventing male-to-female transmission of HIV. Both IVRs were fabricated by hot-melt injection molding. Surface-modified matrix IVRs with polyvinylpyrrolidone or poly(vinyl alcohol) coatings exhibited significantly reduced burst release on the first day (6.45% and 15.72% reduction, respectively). Reservoir IVR segments designed to release lower amounts of HCQ displayed near-zero-order release kinetics with an average release rate of 28.38 μg/mL per day for IVRs loaded with aqueous HCQ and 32.23 μg/mL per day for IVRs loaded with HCQ mixed with a rate-controlling excipient. Stability studies demonstrated that HCQ was stable in coated or noncoated IVRs for 30 days. The IVR segments had no significant effect on cell viability, pro-inflammatory cytokine production, or colony formation of vaginal and ectocervical epithelial cells. Both IVR systems may be suitable for the prevention of HIV transmission and other sexually transmitted infections. PMID:25336923

Synthesis, characterisation and phase transition behaviour of temperature-responsive physically crosslinked poly (N-vinylcaprolactam) based polymers for biomedical applications.

PubMed

Halligan, Shane C; Dalton, Maurice B; Murray, Kieran A; Dong, Yixiao; Wang, Wenxin; Lyons, John G; Geever, Luke M

2017-10-01

Poly (N-vinylcaprolactam) (PNVCL) is a polymer which offers superior characteristics for various potential medical device applications. In particular it offers unique thermoresponsive capabilities, which fulfils the material technology constraints required in targeted drug delivery applications. PNVCL phase transitions can be tailored in order to suit the requirements of current and next generation devices, by modifying the contents with regard to the material composition and aqueous polymer concentration. In this study, physically crosslinked Poly (N-vinylcaprolactam)-Vinyl acetate (PNVCL-VAc) copolymers were prepared by photopolymerisation. The structure of the polymers was established by Fourier transform infrared spectroscopy, nuclear magnetic resonance and gel permeation chromatography. The polymers were further characterised using differential scanning calorimetry and swelling studies. Determination of the LCST of the polymers in aqueous solution was achieved by employing four techniques; cloud point, UV-spectrometry, differential scanning calorimetry and rheometry. Sol-gel transition was established using tube inversion method and rheological analysis. This study was conducted to determine the characteristics of PNVCL with the addition of VAc, and to establish the effects on the phase transition. The PNVCL based polymers exhibited a decrease in the LCST as the composition of VAc increased. Sol-gel transition could be controlled by altering the monomeric feed ratio and polymer concentration in aqueous milieu. Importantly all copolymers (10wt% in solution) underwent gelation between 33.6 and 35.9°C, and based on this and the other materials properties recorded in this study, these novel copolymers have potential for use as injectable in situ forming drug delivery systems for targeted drug delivery. Copyright © 2017 Elsevier B.V. All rights reserved.

Solvent Stability Study with Thermodynamic Analysis and Superior Biocatalytic Activity of Burkholderia cepacia Lipase Immobilized on Biocompatible Hybrid Matrix of Poly(vinyl alcohol) and Hypromellose.

PubMed

Badgujar, Kirtikumar C; Bhanage, Bhalchandra M

2014-12-26

In the present study, we have synthesized a biocompatible hybrid carrier of hypromellose (HY) and poly(vinyl alcohol) (PVA) for immobilization of Burkholderia cepacia lipase (BCL). The immobilized biocatalyst HY:PVA:BCL was subjected to determination of half-life time (τ) and deactivation rate constant (K(D)) in various organic solvents. Biocatalyst showed higher τ-value in a nonpolar solvent like cyclohexane (822 h) as compared to that of a polar solvent such as acetone (347 h), which signifies better compatibility of biocatalyst in the nonpolar solvents. Furthermore, the K(D)-value was found to be less in cyclohexane (0.843 × 10(-3)) as compared to acetone (1.997 × 10(-3)), indicating better stability in the nonpolar solvents. Immobilized-BCL (35 mg) was sufficient to achieve 99% conversion of phenethyl butyrate (natural constituent of essential oils and has wide industrial applications) using phenethyl alcohol (2 mmol) and vinyl butyrate (6 mmol) at 44 °C in 3 h. The activation energy (E(a)) was found to be lower for immobilized-BCL than crude-BCL, indicating better catalytic efficiency of immobilized lipase BCL. The immobilized-BCL reported 6-fold superior biocatalytic activity and 8 times recyclability as compared to crude-BCL. Improved catalytic activity of immobilized enzyme in nonpolar media was also supported by thermodynamic activation parameters such as enthalpy (ΔH(⧧)), entropy (ΔS(⧧)) and Gibb's free energy (ΔG(⧧)) study, which showed that phenethyl butyrate synthesis catalyzed by immobilized-BCL was feasible as compared to crude-BCL. The present work explains a thermodynamic investigation and superior biocatalytic activity for phenethyl butyrate synthesis using biocompatible immobilized HY:PVA:BCL in nonaqueous media for the first time.

Effect of the Z- and Macro-R-Group on the Thermal Desulfurization of Polymers Synthesized with Acid/Base "Switchable" Dithiocarbamate RAFT Agents.

PubMed

Stace, Sarah J; Fellows, Christopher M; Moad, Graeme; Keddie, Daniel J

2018-05-11

Thermolysis is examined as a method for complete desulfurization of reversible addition-fragmentation chain transfer (RAFT)-synthesized polymers prepared with acid/base "switchable" N-methyl-N-pyridyldithiocarbamates [RS 2 CZ or RS 2 CZH + ]. Macro-RAFT agents from more activated monomers (MAMs) (i.e., styrene (St), N-isopropylacrylamide (NIPAm), and methyl methacrylate (MMA)) with RS 2 CZH + and less activated monomers (LAMs) (i.e., vinyl acetate (VAc) and N-vinylpyrolidone (NVP)) with RS 2 CZ are prepared by RAFT polymerization and analyzed by thermogravimetric analysis. In all cases, a mass loss consistent with loss of the end group (ZCS 2 H) is observed at temperatures lower than, and largely discrete from, that required for further degradation of the polymer. The temperatures for end group loss and the new end groups formed are strongly dependent on the identity of the R(P) n and the state of the pyridyl Z group; increasing in the series poly(MMA) < poly(St) ∼ poly(NIPAm) < poly(VAc) ∼ poly(NVP) for S 2 CZ and poly(MMA) < poly(St) ∼ poly(NIPAm) for S 2 CZH + . Clean end group removal is possible for poly(St) and poly(NVP). For poly(NIPAm), the thiocarbonyl chain end is removed, but the end group identity is less certain. For poly(MMA) and poly(VAc), some degradation of the polymer accompanies end group loss under the conditions used and further refinement of the process is required. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Development of a novel anisotropic self-inflating tissue expander: in vivo submucoperiosteal performance in the porcine hard palate.

PubMed

Swan, Marc C; Bucknall, David G; Czernuszka, Jan T; Pigott, David W; Goodacre, Timothy E E

2012-01-01

The advent of self-inflating hydrogel tissue expanders heralded a significant advance in the reconstructive potential of this technique. Their use, however, is limited by their uncontrolled isotropic (i.e., uniform in all directions) expansion. Anisotropy (i.e., directional dependence) was achieved by annealing a hydrogel copolymer of poly(methyl methacrylate-co-vinyl pyrrolidone) under a compressive load for a specified time period. The expansion ratio is dictated by the percentage of vinyl pyrrolidone content and the degree of compression. The expansion rate is modified by incorporating the polymer within a silicone membrane. The in vivo efficacy of differing prototype devices was investigated in juvenile pigs under United Kingdom Home Office Licence. The devices were implanted within a submucoperiosteal pocket in a total of six porcine palates; all were euthanized by 6 weeks after implantation. A longitudinal volumetric assessment of the expanded tissue was conducted, in addition to postmortem analysis of the bony and mucoperiosteal palatal elements. Uncoated devices caused excessive soft-tissue expansion that resulted in mucoperiosteal ulceration, thus necessitating animal euthanasia. The silicone-coated devices produced controlled soft-tissue expansion over the 6-week study period. There was a statistically significant increase in the volume of expanded soft tissue with no evidence of a significant acute inflammatory response to the implant, although peri-implant capsule formation was observed. Attenuation of the bony palatal shelf was noted. A unique anisotropic hydrogel device capable of controlled expansion has been developed that addresses a number of the shortcomings of the technology hitherto available.

Mechanism of the formation and growth of fine particles clustered polymer microspheres by simple one-step polymerization in aqueous alcohol system

NASA Astrophysics Data System (ADS)

Mao, Hui; Wen, Chao; Wu, Shuyao; Liu, Daliang; Zhang, Yu; Song, Xi-Ming

2016-02-01

By using the one-step copolymerization of styrene (St) and 1-vinyl-3-ethylimidazolium bromide (VEIB), fine particles clustered (FPC) poly(St-co-VEIB) microspheres have been successfully prepared in the present of sodium dodecylsulfonate (SDS) in aqueous alcohol system. The FPC poly(St-co-VEIB) microspheres are composed of small poly(St-co-VEIB) nanospheres with the average diameter of 40 nm. The formation mechanism of FPC poly(St-co-VEIB) microspheres is proposed by investigating the influence of reaction conditions on their morphologies and observing their growth process. It can be well convinced that VEIB not only acted as a kind of monomers, which participated in the polymerization and provided electropositivity for FPC poly(St-co-VEIB) microspheres, but also acted as emulsifier and reactive stabilizer. The FPC poly(St-co-VEI[SO3CF3]) microspheres, which were obtained by anion-exchange between -SO3CF3 of HSO3CF3 and Br- in FPC poly(St-co-VEIB) microspheres due to the existence of imidazolium groups with electropositivity, showed higher catalytic efficiency for hydration of 1,2-epoxypropane with H2O and esterification between acetic acid and ethanol than that of H2SO4.