VP Monomer Research Articles

Crosslinking ABA-type elastomers with polyoxometalate: A convenient molecular design of double network

In this study, we reported a convenient pathway toward the molecular design of double network materials. First, we prepared an ABA-type copolymer composed of a central poly (n-butyl acrylate) block and two 4-vinylpyridine end moieties, i.e., 4VP-PnBA-4VP. Since the central PnBA block was much larger than the two end 4VP blocks, sphere 4VP domains were formed in the PnBA matrix after the phase segregation. Second, we introduced a small number of polyoxometalate (POM) molecules that preferentially locate in the 4VP domain to cross-link only a fraction of the end moieties selectively. Since the cross-linked ends have an additional association energy, the sample exhibits two-step relaxation behavior. The amplitude and relaxation time of the slower process, owing to those chains end-cross-linked by POM, can be well explained by assuming (1) the reactivity is the same for all chain ends during the synthesize of the the end moiety, and (2) the probability for crosslinking by POM is the same for all 4VP monomers in their domain.

Grafting of Poly(4-vinylpyridine) onto a Macroporous Resin for Sorption of 2-Naphthalenesulfonic Acid in Batch Experiments

In the current work, poly(4-vinylpyridine) (P4VP) was grafted on a macroporous polystyrene resin via free-radical polymerization by using the pendent vinyl group. The grafting conditions such as swelling agent, initiator concentration, reaction temperature, and amount of 4-vinylpyridine (4VP) monomer were optimized, and three resins with different 4VP monomer amounts (SC-1, SC-2, and SC-3) were chosen as adsorbents. P4VP-grafted resins were characterized by scanning electron microscopy, N2 sorption/desorption isotherms, Fourier transform infrared, and X-ray photoelectron spectroscopy. The sorption properties of 2-naphthalenesulfonic acid (NSA) on three resins were comparatively investigated. The experimental data revealed that the sorption process on three resins fitted well with the pseudo-second-order kinetics equation, and the equilibrium isotherms were in good agreement with the Langmuir model. The NSA sorption onto resins was an endothermic and spontaneous process, and SC-3 loaded with NSA can be eff...

Processing Hundreds of Nanometres Thick Electrografted P4VP for High Aspect Ratio TSV Insulation

In 3D integration of microsystems, electrical insulation of High Aspect Ratio Through Silicon Via (HAR TSV) is a major challenge. This insulation is traditionally realized through the deposition of a thin SiO2 layer. Electrografted poly-4-vinylpyridine (P4VP) has been demonstrated to be considered as an alternative to SiO2 dielectric, traditionally used, for HAR TSVs insulation1. Electrografted P4VP has comparable electrical performances than SiO2 based dielectric and is capable to smoothly cover the scalloped side walls of the TSV with better coverage uniformity than most dielectrics considered for Via-Middle or Via-Last processes2. Electrografting methods are electro-initiated processes. The commercial electrografting solution contains organic reactants in an aqueous acidic media: 4-nitrobezen diazonium (NBD) and monomers of 4 vinylpyridine (4VP). The electrografting mechanism of P4VP onto Si in aqueous media through reduction of diazonium salts is complex. However, a mechanism based on electrochemical initiation followed by a purely chemical polymerization has been proposed. In a first electro-initiated step, aryl radicals must be generated by the electrochemical reduction of NBD on the Si electrode. This can be achieved using different technics such as electrochemical reduction. The generated aryl radicals can covalently bond to the silicon surface through an electron transfer or can initiate radical polymerization of 4VP monomers into P4VP. Most of the published work about electrografting on silicon substrate is realized on oxide free Si-H functionalized surface. Such experimental condition do not usually permit an electrografted polymer to grow up to hundreds of nanometres, which is not suitable to meet electrical requirement for TSV insulation. Experimentally, reverse potential pulse conditions applied on p-type Si-OH functionalized sample allow the electrografting process of P4VP to grow faster and the grafted layer to be thicker. This phenomenon is enhanced if the process is realized under illumination (with the proper wavelength source with the respects of the silicon band gap). One of the hypotheses to explain this increase of kinetic and thickness could be the rapid inversion of the surface charge during the reverse pulse: the polymer structure would stay open by the creation of channels in the film, through desorption of physisorbed species, allowing the reactive species to diffuse more easily from the electrografting solution to the silicon surface. This phenomenon could facilitate the generation of aryl radicals for the 4VP polymerization process to be maintained. And thus, for the P4VP electrografting technic to be a versatile method for HAR TSV electrical insulation. We will present and discuss the electrografting experimental conditions and the impact of the surface preparation on the P4VP to understand their role on the kinetic and the thickness of the grafted P4VP. Acknowledgement Université de Sherbrooke, Natural Sciences and Engeeniring Research Council of Canada (NSERC), Institut National de la Recherche Scientifique (INRS), Teledyne Dalsa and aveni are gratefully acknowledged for their help and their financial support.

Morphological Control over ZnO Nanostructures from Self-Emulsion Polymerization

Three different morphologies of ZnO nanostructures, such as nanospheres, nanorods, and nanoribbons, were controlled by tuning the ratio of the Zn2+ precursor to the 4VP monomer when polymerized in aqueous medium utilizing self-emulsion polymerization. The amphiphilic homopolymer (P4VP) acts as a template to form the ZnO/P4VP nanocomposite. The aspect ratio of the nanostructures is strongly dependent on the molar concentration of the Zn2+ precursor and becomes higher as its concentration increases. This results in different morphologies that are consistently repeatable. Pure ZnO was obtained from the ZnO/P4VP nanocomposites by calcination at 400 °C or by solvent washing. The calcination of the nanocomposties resulted in different morphologies, such as spherical, corolla shaped, and nanosheets. In addition, hexagonal nanoblocks, nanorods, and nanoribbons were observed when the polymer was removed from the nanocomposites by washing with chloroform. Removing polymer by solvent washing is a very easy, cost-eff...

Radiation induced emulsion graft polymerization of 4-vinylpyridine onto PE/PP nonwoven fabric for As(V) adsorption

A novel nonwoven fabric adsorbent having 4-vinylpyridine functional groups was prepared by using radiation-induced emulsion graft polymerization method and grafting 4-vinylpyridine monomer onto a polyethylene-coated polypropylene nonwoven fabric (NWF) in aqueous emulsion solution. The grafting conditions of the 4-vinylpyridine monomer onto the NWF were optimised and 150% Dg VP-g-NWF was prepared using 30 kGy pre-irradiation dose, 5% VP monomer concentration and 0.5% (w/w) Tween 20 in aqueous emulsion. Grafted 4-vinylpyridine chains on the NWF were then quaternized for the preparation of QVP-g-NWF adsorbent. All fabric structures were characterized by using Fourier-transform infrared spectrometer, x-ray photoelectron spectrometer and scanning electron microscope. QVP-g-NWF adsorbent was used in batch adsorption experiments for As(V) ions by studying the pH, contact time, and initial As(V) ion concentration parameters. Results showed that QVP-g-NWF adsorbent has significant As(V) adsorption and experimental As(V) adsorption capacity was 98.04mg As(V)/g polymer from 500mg/L initial As(V) concentration at pH 7.00.

Synthesis and Thermal Stability of Glyoxalated Alkali Lignin-Polyvinylpyrrolidone Resins

Natural, renewable, and non-toxic lignin-based resin was synthesized through copolymerization with monomeric N-vinyl-2-pyrrolidone (VP) in the presence of benzoyl peroxide (BPO) as the free radical initiator. Glyoxalated lignin was used as the feedstock. The mechanism of copolymerization between the glyoxalated alkali lignin and VP monomer was determined through Fourier-transform infrared spectroscopy (FT-IR). The optimum amount of VP monomer used and the reflux time required in the synthesis process were determined through thermogravimetric analysis (TGA). In the presence of BPO, copolymerization between glyoxalated alkali lignin and VP monomer was accomplished via the formation of ether linkages in a condensation reaction at pH 7.0. More ether linkages were formed with higher amounts of VP monomer and longer reflux times. The addition of VP monomer into glyoxalated alkali lignin increased its thermal stability. FT-IR and TGA indicated that 0.012 moles of VP monomer and an 8-h reflux time were optimum conditions for the synthesis of glyoxalated alkali lignin-polyvinylpyrrolidone resins.

Dissolution and Solubility Enhancement of the Highly Lipophilic Drug Phenytoin via Interaction with Poly(N-isopropylacrylamide-co-vinylpyrrolidone) Excipients.

Excipients of natural or synthetic origin play an important role in pharmaceutical performance to enhance the solubility, bioavailability, release, and stability of insoluble drugs. Herein, a series of seven excipient models was prepared by both homopolymerization and copolymerization of 1-vinyl-2-pyrrolidone (VP) and N-isopropylacrylamide (NIPAAm) by free radical polymerization yielding two homopolymers poly(VP) and poly(NIPAAm) and five copolymers of poly(NIPAAm-co-VP) at difference compositions. While the VP monomer provided aqueous solubility at a variety of conditions to the excipient, the incorporation of NIPAAm into the copolymer offered additional hydrogen bond donating sites to optimize the drug-polymer interactions in the system. Due to the presence of NIPAAm, the copolymers were sensitive to temperature as well. It was found that as the proportion of VP was increased (from 0 to 100%), the lower critical solution temperature (LCST) and the water solubility of the polymer models increased. To examine the role of specific drug-polymer interactions during dissolution on drug solubility and bioavailability, the polymers were formulated with the anticonvulsant drug phenytoin, which is a poorly water-soluble BCS class II drug where oral absorption is limited by the drug solubility. Amorphous solid dispersions (ASD) were prepared via spray drying of phenytoin with the polymer excipient models to contain 10% and 25% by weight drug loading. Physical characterization of the ASDs by powder X-ray diffraction (PXRD) and differential scanning calorimetry (DSC) revealed that the polymers held the drug in a high-energy amorphous phase in all the formulations prepared. All ASDs exhibited improved in vitro dissolution rates compared to drug only and physical mixtures of the polymers and the drug. Drug solubility was the highest with the ASDs containing poly(NIPAAm-co-VP) 60:40 and 50:50, which showed a solubility enhancement of near 14-fold increase compared to pure drug, indicating the significance of copolymer composition to improve drug-polymer interactions toward increasing bioavailability.

Modification of PTFE latex with P4VP/Surfactant complexes at nanoscale

Polytetrafluoroethylene (PTFE) latex nanoparticles were subjected to modification with Poly (4-vinylpyridine) (P4VP) by in situ seeded emulsion polymerization technique using regular [sodium dodecyl sulfate (SDS)] and fluorinated [Potassium heptadecafluoro-1-octanesulfonate (PFS)]surfactants. The as prepared PTFE- (P4VP/surfactant complex) composite latex nanoparticles were characterized for structure, morphology, and thermal properties and a comparison of particles obtained by PFS and SDS was done with different W/W ratios of PTFE and 4VP monomer. The composites have shown a multistep degradation pattern that may be attributed to the P4VP, surfactant and PTFE backbone degradation. Lowering of crystal–crystal transition temperature of PTFE and increase in the glass transition temperature of the P4VP/PFS or SDS complexes was noticed in all the composites suggesting a homogeneous modification. Thus, a simple and easy way to modify PTFE has been reported which could be subsequently complexed with metal salts such that stringent high energy pretreatment methods like plasma, ozone, or irradiation techniques could be avoided. POLYM. ENG. SCI., 55:499–505, 2015. © 2014 Society of Plastics Engineers

In situ polymerization of 4-vinylpyridine/bentonite composites and their application for toluene removal

A new composite material, able to remove organic molecules from aqueous solutions, is obtained by in situ polymerization of 4-vinylpyridine (4VP) in bleaching clay (BC, bentonite) as support. The 4VP monomer is inserted into the interlayer space of the BC using N-dodecylpyridinium chloride (DPC) as tensioactive intercalating reagent. Thus, three composite samples (BCP-1, BCP-2, and BCP-3) were prepared by varying the initial amount of DPC. Thermogravimetric analysis reveals good stability of the new materials at high temperatures. Fourier-transform infrared (FTIR) analysis clearly shows that 4VP is effectively polymerized and adsorbed onto bentonite. Good efficiency in removing toluene from aqueous solution is demonstrated by adsorption kinetics. Batch adsorption studies are conducted to evaluate the effects of the initial DPC amount. We show in this work that an increase of the amount of DPC increases the introduction of 4VP monomer onto the bentonite. Consequently, the amount of coated poly(4-vinylpyridine) P4VP rises. Organic modification leads to an increase in the amount of toluene adsorbed. The obtained results clearly show that the composite samples BCP-X (X = 1, 2, 3) are efficient in toluene removal from aqueous solution, showing thus the hydrophobic character of these materials.

Studies of the effect of surface modification of carbon sorbents by poly-N-vinylpyrrolidone using a complex of physicochemical and microbiological methods

The surface of the VNIITU-1 carbon mesoporous sorbent was modified with poly-N-vinylpyrrolidone characterized by antibacterial activity. Synthesis was carried out in two stages: (1) impregnation of the carbon sorbent by an aqueous solution of poly-N-vinylpyrrolidone with the molecular mass of 10000 g/mol; and (2) impregnation of the carbon sorbent by an aqueous solution of the (N-vinylpyrrolidone) monomer and initiator with their further polymerization in an inert atmosphere. Carbon sorbent samples were studied using a complex of physicochemical methods: scanning electron microscopy, infrared spectroscopy, low-temperature nitrogen adsorption, nuclear magnetic resonance, and thermogravimetry. It was found that the polymer obtained on the carbon surface is free of the initial toxic VP monomer. Microbiological tests of modified sorbents with respect to pathogenic and opportunistic microflora were carried out.

Fabrication and properties of ultrafiltration membranes composed of polysulfone and poly(1-vinylpyrrolidone) grafted silica nanoparticles

Membranes for ultrafiltration were prepared from polysulfone (PSf) composites with poly(1-vinylpyrrolidone) grafted silica nanoparticles (PVP-g-silica). For the synthesis of PVP-g-silica, hydroxyl terminated silica nanoparticles were reacted with (3-methacryloxypropyl)trimethoxysilane (γ-MPS) to form γ-MPS terminated silica nanoparticles (silica-MPS), which were further reacted with VP monomer. Formation of PVP-g-silica was confirmed by FT-IR, XPS, TGA, FE-SEM, and HR-TEM. PSf/PVP-g-silica membranes exhibited higher water flux than PSf membranes without any loss in solute rejection for membranes containing less than or equal to 5wt% of PVP-g-silica. The water flux of a membrane containing 1wt% PVP-g-silica was 2.3 times higher than that of PSf membrane. The hydrophilicity of the PSf/PVP-g-silica membrane also increased with increasing PVP-g-silica content. The hydrophilicity of the PSf/PVP membrane decreased with increasing retention time in a water bath, while the hydrophilicity of the PSf/PVP-g-silica membrane did not change with retention time. PSf/PVP-g-silica membranes exhibited enhanced fouling resistance in fouling experiments using nonionic surfactants.

Synthesis and swelling behavior of thermosensitive IPN hydrogels based on sodium acrylate and N‐isopropyl acrylamide by a two‐step method

AbstractA series of interpenetrating polymer network (IPN) hydrogels having higher swelling ratio (SR) and thermosensitivity were synthesized from sodium acrylate (SA) and N‐isopropyl acrylamide (NIPAAm) by a two‐step method. A series of the porous poly(sodium acrylate ‐co‐1‐vinyl–2‐pyrrolidone) [poly(SA‐co‐VP)], (SV), hydrogels were prepared from acrylic acid having 90% degree of neutralization and VP monomer in the first step. The second step is to immerse the SV dried gels into the NIPAAm solution containing initiator, accelerator, and crosslinker to absorb NIPAAm solution and then polymerized to form the poly(SA‐co‐VP)/poly(NIPAAm) IPN hydrogels (SVN). The effect of the different molar ratios of SA/VP and the content of NIPAAm on the swelling behavior and physical properties of the SVN hydrogels was investigated. Results showed that the SVN hydrogels displayed an obviously thermoreversible behavior when the temperature turns across the critical gel transition temperature (CGTT) of poly(NIPAAm) hydrogel. The pore diameter distributions inside the hydrogel also indicated that the pore sizes inside the SVN hydrogels were smaller than those inside the SV hydrogels. At the same time, the more proportion of SA was added into the hydrogel, the larger pore diameter of the SV hydrogel was formed. The results also showed that the SR decreased with an increase of the VP content in the SV hydrogel and more obviously decreased in the SVN hydrogels. The SVN networks also showed stronger shear moduli than SV hydrogels. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Microphase separation in thin films of supramolecular assemblies composed of a triblock copolymer and low‐molecular‐weight additive

AbstractThe phase behavior of supramolecular assemblies (SMAs) formed by poly(4‐vinylpyridine)‐block‐polystyrene‐block‐poly(4‐vinylpyridine) (P4VP‐b‐PS‐b‐P4VP) triblock copolymer with 2‐(4′‐hydroxybenzeneazo)benzoic acid (HABA) was investigated with respect to the molar ratio (X) between HABA and 4VP monomer unit in bulk as well as in thin films. The results were compared with SMAs formed by a PS‐b‐P4VP diblock copolymer of similar composition as the triblock but half the molecular weight to ascertain the effect of molecular architecture on microphase separation. In bulk, both the di‐ and triblock SMAs showed composition‐dependent morphological transitions, which could be tuned by HABA/4VP molar ratio. The domain spacing of the SMA was not significantly affected by the molecular architecture of the constituting block copolymers. In thin films also, both the di‐ and triblock SMAs showed more or less similar morphological transitions depending on X. Interestingly, the domain orientation of the cylindrical or lamellar microdomains in the SMAs was influenced by the molecular architecture of the block copolymer. After chloroform annealing, although the diblock SMAs showed in‐plane orientation of the domains, triblock SMAs showed perpendicular domain orientation. The perpendicular orientation of the microdomains in triblock was favored because it allowed the mid‐PS blocks to acquire normal distribution of loop and bridged conformations. Furthermore, the orientation of the lamellar and cylindrical microdomains of the diblock SMAs was found to switch to perpendicular orientation after annealing in 1,4‐dioxane vapors. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1594–1605, 2010

Grafting CVD of Poly(vinyl pyrrolidone) for Durable Scleral Lens Coatings

AbstractGrafting (g)CVD from the monomer 1‐vinyl‐2‐pyrrolidone (VP) and the Type II initiator benzophenone (BP) under 254 nm UV irradiation yields durable hydrophilic coatings on substrates of poly(methacrylic acid) (PMA) derivatives, desirable for scleral lens applications. The gCVD polymerization of the VP monomer is essentially complete, and little excess BP remains in the film. Process optimization, through single variable and two fractional factorial experiments, result in retention of >90% of the as‐deposited film thickness after rinsing. Increasing the initiator dosing time beyond 10 min, or the UV exposure time beyond 5 min, has little effect on the as‐deposited thickness, or percentage of film retained after rinsing. This suggests that UV irradiation rapidly transforms most of the BP absorbed on the surface to initiating radicals. Once sufficient initiator dosage and UV exposure have been achieved, the initial deposition thickness is controlled primarily by the total flux of monomer to the surface, which is consistent with previous studies. For all samples, thickness loss occurs primarily during the first 30 days of saline soak‐testing with no statistically significant loss (p > 0.25) during the next 90 days of soak testing. While the additional UV exposure time has a limited effect on initial film thickness, it does increase long term thickness retention, most likely by forming crosslinked and branched structures within the film. All samples tested retain sufficient gCVD coating thickness to impart improved hydrophilicity at the surface throughout the entire 120 day saline soak‐testing period. The fractional factorial experiments correlate improved hydrophilicity with an interaction between initiator dosage time and UV exposure time. Indeed, decreasing these two process variables in tandem provides the greatest reduction in contact angle. While the uncoated PMA displayed 92.3° ± 2.1° advancing and 86.7° ± 3.0° receding contact angles with water, the most hydrophilic gCVD coating lowers the advancing and receding contact angles to 39.5° ± 2.6° and 36.2° ± 1.6°, respectively.

Composition-Dependent Morphological Transitions and Pathways in Switching of Fine Structure in Thin Films of Block Copolymer Supramolecular Assemblies

The phase behavior of supramolecular assemblies (SMA) formed by polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) with 2-(4′-hydroxybenzeneazo)benzoic acid (HABA) was investigated with respect to the molar ratio (X) between HABA and 4VP monomer unit in bulk as well as in thin films coated on a silicon substrate. In bulk, the SMA showed bcc packed spherical or hexagonally packed cylindrical microdomains composed of P4VP(HABA) blocks in PS matrix depending on the composition which varied with the HABA weight fraction. However, at a molar ratio of 2 where HABA was in excess, the cylindrical microdomains of P4VP(HABA) blocks were found to pack in a tetragonal lattice. The SMA in thin film also showed spherical or cylindrical morphology depending on the composition. Interestingly, the orientation of cylindrical microdomains of P4VP(HABA) depended on the selectivity of the solvent as well as on the degree of swelling. Hence, in a nonselective solvent like chloroform, the cylinders were found to lie parallel t...

A New Approach for the Electrochemical Detection of Phenolic Compounds. Part I: Modification of Graphite Surface by Plasma Polymerization Technique and Characterization by Raman Spectroscopy

This paper describes the early stages of preparation of an electrochemical sensor for the detection of phenolic compounds. For this aim, graphite leads were modified by plasma polymerization (PlzP) technique utilizing the monomer N-vinylpyrrolidone (VP) with its conductive property as precursor. The influence of different experimental parameters such as plasma discharge power and exposure time was investigated to optimize the proposed electrode. After the modification process, graphite leads (electrodes) were investigated by differential pulse voltammetry. The voltammograms were recorded between 0 and +1.0 V at 16 mVs−1. The surface characteristics of the PlzP-VP modified carbon lead surfaces were determined by Raman spectroscopy. It was clearly observed that VP monomer was polymerized to form polyvinylpyrrolidone that is a very well-known adsorbant for phenolics. As expected, it was clearly pointed out that the electrochemical conductivity of the modified carbon leads were varied due to adsorption of a model phenolic compound “gallic acid” at a certain concentration.

Complex-radical copolymerization of N-vinyl pyrrolidone with isostructural analogs of maleic anhydride

Radical copolymerizations of N-vinyl-2-pyrrolidone (VP) with isostructural analogs of maleic anhydride (MA), such as citraconic anhydride (CA) and N-substituted maleimides [maleimide (MI), N-ethylmaleimide (EMI) and N-phenylmaleimide (PhMI)] were studied. Compositions of copolymers synthesized in a wide range of monomer feed ratios were determined by alkali titration (for anhydride copolymers), FTIR and 1H NMR spectroscopy using 1495 and 630 cm-1 (for VP-MI), 1289 and 1225 cm-1 (for VP-EMI) and 1050 and 3067 cm-1 (for VP-PhMI) analytical bands and integral areas of CH2 (pyrrolidone ring) and CH (MI), CH3 (EMI) and CH= (benzene ring in PhMI) groups, respectively. Electron-donor VP monomer was found to have substantially different reactivities in the radical copolymerization with MA, CA and N-substituted (H, C2H5 and phenyl) malemides as electron-acceptor comonomers. Effects of H-bonding and N→O=C coordination on the monomer reactivity ratios were evaluated. Tendency to alternation of the monomer pairs increases in the order of VP–MA > VP–CA > VP-MI > VP-PhMI > VP-EMI. Structure-thermal property-relationship for the synthesized copolymers was also studied.

Adsorption Properties of Poly(N‐vinylpyrrolidone‐co‐methacrylic acid) Hydrogels

In this study, N‐vinylpyrrolidone (VP)/methacrylic acid (MAA) copolymers have been prepared at three different mole percents for which the methacrylic acid composition is around 5, 10, and 15%. MAA and VP monomer mixtures have been irradiated in a 60Co‐γ source at different irradiation doses and percent conversions have been determined gravimetrically. ∼80% conversion of monomers into hydrogels were performed at 3.4 kGy irradiation dose. Poly(N‐vinylpyrrolidone‐co‐methacrylic acid) P(VP/MAA) hydrogels have been used for the adsorption of some dyes such as Safranine‐O, Methylene Blue from aqueous solutions. These hydrogels were swollen in distilled water and in aqueous solutions of dyes at pH 4.0, 7.0, and 9.0. P(VP/MAA)1 hydrogel which contains the higher methacrylic acid content showed the maximum % swelling at pH 9.0 in water and swelling increased in the order of Safranine‐O>Methylene Blue. Diffusion of water and aqueous solution of dyes within hydrogels was found to be of non‐Fickian character. Diffus...

Preparation and Characterization of Poly(N‐Vinylpyrrolidone‐co‐Methacrylic Acid) Hydrogels

In this study, N‐vinylpyrrolidone (VP)/methacrylic acid (MAA) copolymers have been prepared at three different mole percents, the methacrylic acid composition being around 5, 10, 15%. MAA and VP monomer mixtures have been irradiated in 60Co‐γ source at different irradiation doses and percent conversions have been determined gravimetrically. ∼80% conversion of monomers into hydrogels were performed at 3.4 kGy irradiation dose. These hydrogels were swollen in distilled water at pH 4.0, 7.0, and 9.0. P(VP/MAA) hydrogel which contains 5% methacrylic acid showed the maximum % swelling at pH 9.0 in water. Diffusion of water was found to be of non‐Fickian character. Diffusion coefficients of water in P(VP/MAA) hydrogels were calculated. Initial swelling rates of P(VP/MAA) hydrogels increased with increasing pH and MAA content in hydrogels. Swelling kinetics of P(VP/MAA) hydrogels was found to be of second order. Thermal behavior of PMAA, PVP and P(VP/MAA) hydrogel were investigated by thermal analysis. P(VP/MAA) hydrogel gained new thermal properties and the temperature for maximum weight loss and temperature for half‐life of P(VP/MAA) hydrogel were determined.

Surface Functionalization Technique for Conferring Antibacterial Properties to Polymeric and Cellulosic Surfaces

A simple surface modification technique was developed to functionalize polymeric and cellulosic materials with bactericidal polycationic groups. The poly(ethylene terephthalate) (PET) film was first graft copolymerized with 4-vinylpyridine (4VP) and subsequently derivatized with hexyl bromide via the quaternization of the grafted pyridine groups into pyridinium groups. The amount of pyridinium groups on the film surface could be controlled by varying the 4VP monomer concentrations used for grafting. The pyridinium groups introduced on the surface of the substrate possess antibacterial properties, as shown by their effect on Escherichia coli (E. coli). The bacteria killing efficiency is very high when the concentration of pyridinium groups on surfaces is 15 nmol/cm2 or higher. E. coli adhered on the functionalized surfaces are no longer viable when released into an aqueous culture medium. Filter paper, as a typical cellulosic material, was also functionalized in the same manner to introduce the pyridinium ...