Synthesis,characterization, and in vitro drug‐release properties of 2‐hydroxyethyl methacrylate copolymers

2‐Hydroxyethyl methacrylate was copolymerized with acrylamide, N‐vinyl‐2‐pyrrolidone, and n‐butyl methacrylate by free‐radical solution polymerization with α,α′‐azobisisobutyronitrile as an initiator at 70 ± 1°C. The average molecular weights and molar compositions of the resultant copolymers were determined with gel permeation chromatography and ¹H‐NMR spectroscopy data, respectively. Diclofenac or 2‐[(2,6‐dichlorophenyl)amino]benzene acetic acid, a nonsteroidal anti‐inflammatory drug, was chemically attached to the copolymers by transesterification reaction in the presence of N,N′‐dicyclohexylcarbodiimide to give macromolecular prodrugs. All the synthesized polymers were characterized with Fourier transform infrared, ¹H‐, and ¹³C‐NMR spectroscopy techniques. The polymer–drug conjugates were hydrolyzed in cellophane member dialysis bags containing aqueous buffered solutions (pH 8) at 37°C, and the hydrolysis solutions were detected by UV spectrophotometer at selected intervals. The results showed that the drug could be released by selective hydrolysis of the ester bond from the side chain of the drug moiety. The release profiles of the drug indicated that the hydrolytic behavior of polymeric prodrugs strongly depends on the hydrophilicity of the polymer. The results suggest that the synthesized copolymers could be useful carriers for the release of diclofenac in controlled‐release systems. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2403–2409, 2007     

Antifouling microfiltration membranes prepared from poly(vinylidene fluoride)‐graft‐Poly(N‐ vinyl pyrrolidone) powders synthesized via pre‐irradiation induced graft polymerization

Poly(vinylidene fluoride) (PVDF) powders were grafted with N‐vinyl pyrrolidone using the pre‐irradiation induced graft polymerization technique. The effects of reaction time, absorbed dose, and monomer concentration on the degree of grafting were investigated, and the grafted PVDF powders were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, and differential scanning calorimetry. The grafted PVDF powders were also cast into microfiltration (MF) membranes via the phase‐inversion method. The contact angle and water uptake were measured. The membrane morphology was studied by scanning electron microscopy, and the water filtration properties of the membranes were tested. The antifouling properties were determined through measurements of the recovery percentage of pure water flux after the MF membranes were fouled with bovine serum albumin solution. The results confirmed that the existence of poly(N‐vinyl pyrrolidone) (PVP) graft chains improved the hydrophilicity and antifouling properties of the MF membranes cast from PVDF‐g‐PVP powders. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synthesis and characterization of novel graft copolymers by radiation‐induced grafting

The radiation‐induced graft copolymerization of N‐vinyl‐2‐pyrrolidone (NVP), 4‐vinyl pyridine (4VP), and 2‐vinyl pyridine (2VP) monomers onto poly (ethylene‐alt‐tetrafluoroethylene) (ETFE) was investigated. The influence of synthesis conditions particularly the solvent was studied. Various solvents, such as n‐propanol, isoproponol, benzyl alcohol, methanol, ethanol, cyclohexanone, tetrahydrofuran (THF), nitromethane, 1,4‐dioxane, and n‐heptane were examined for this purpose. Graft copolymers were characterized by Fourier transform infrared (FTIR) spectroscopy, dynamic mechanical analysis (DMA), and scanning electron microscopy‐energy dispersive spectroscopy (SEM‐EDAX). It was found that the nature of the solvent had profound influence over the grafting reaction. Cyclohexanone, n‐propanol, and isoproponol for 4VP/ETFE grafting, THF and 1,4‐dioxane for NVP/ETFE grafting, and benzyl alcohol and methanol for 2VP/ETFE grafting were found to be the suitable solvents yielding highest graft levels. Isoproponol and n‐propanol are promising in terms of both graft level and mechanical properties for 4VP/ETFE. Grafting of NVP, 4VP, and 2VP onto ETFE were verified through FTIR spectroscopy. Storage modulus and glass transition temperature of the copolymers were found to increase as graft level increased. Surface profile of representative films was also investigated by viewing the distribution of elemental nitrogen using SEM‐EDAX. Results indicated that copolymers of 4VP, NVP, and 2VP are considerably different from each other. 4VP‐based copolymers exhibited relatively more homogenous grafting over the surface compared with NVP‐ and 2VP‐based copolymers. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Thermoresponsive and biocompatible poly(vinyl alcohol)‐graft‐poly(N,N‐diethylacrylamide) copolymer: Microwave‐assisted synthesis,characterization, and swelling behavior

Novel thermoresponsive poly(vinyl alcohol)‐graft‐poly(N,N‐diethylacrylamide) (PVA‐g‐PDEAAm) copolymers were prepared by microwave‐assisted graft copolymerization using a potassium persulfate/N,N,N′,N′‐tetramethylethylenediamine (KPS/TEMED) initiator system. The structures of PVA‐g‐PDEAAm copolymers were characterized by ¹H‐NMR, Fourier transform infrared spectroscopy, differential scanning calorimetry/thermogravimetric analysis, gel permeation chromatography, X‐ray diffraction, and scanning electron microscopy. The effects of various process parameters on grafting were systematically studied: microwave power, KPS, monomer and PVA concentrations, and ultraviolet irradiation. Under optimal conditions, the maximum grafting percent and graft efficiency were 101% and 93%, respectively. Furthermore, a lower critical temperature of copolymers was measured in the range 29–31 °C by ultraviolet spectroscopy. The swelling behavior of graft membranes was carried out at various temperatures, and the results showed that the swelling behavior of membranes was dependent on the temperature. In vitro cell culture studies using L929 fibroblast cells confirmed cell compatibility with the PVA‐g‐PDEAAm copolymer and its membrane, making them an attractive candidate for drug delivery systems. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45969.     

Synthesis and characterization of N‐vinyl pyrrolidone and cellulosics based functional graft copolymers for use as metal ions and iodine sorbents

To develop cost effective and eco friendly polymeric materials for enrichment and separation technologies, 1‐vinyl‐2‐pyrrolidone (N‐VP) was graft copolymerized onto cellulose, extracted from pine needles. Optimum conditions have been evaluated for the grafting of N‐VP onto cellulose and at these conditions it was also grafted onto cellulose phosphate, hydroxypropyl cellulose, cyanoethyl cellulose, and deoxyhydrazino cellulose. At the optimum grafting conditions for N‐VP, it was also cografted with maleic anhydride. Kinetics of radiochemical graft copolymerization has been studied and evaluation of the polymerization and grafting parameters as percent grafting, percent grafting efficiency, rate of polymerization, homopolymerization, and graft copolymerization have been evaluated. Graft copolymers have been characterized by elemental analysis, FTIR, and swelling studies. An attempt has been made to study sorption of some metal ions such as Fe²⁺ and Cu²⁺ and iodine on select graft copolymers to investigate selectivity in metal ion sorption and iodine sorption as a function of structural aspects of the functionalized graft copolymers to find their end uses in separation and enrichment technologies. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 373–382, 2005     

Synthesis and characterization of poly(N‐vinyl‐2‐pyrrolidone) grafted sodium alginate hydrogel beads for the controlled release of indomethacin

Graft copolymers of sodium alginate (NaAlg) with N‐vinyl‐2‐pyrrolidone were prepared using azobisisobutyronitrile as initiator. The graft copolymers (NaAlg‐g‐PVP) were characterized with Fourier transform infrared spectroscopy, elemental analysis, and differential scanning calorimetry. Polymeric hydrogel beads of NaAlg and NaAlg‐g‐PVP were prepared by crosslinking method using glutaraldehyde (GA) as a crosslinker in the hydrochloric acid catalyst (HCl) and these beads were used to deliver anti‐inflammatory drug, indomethacin (IM). Chemical stability of the IM after encapsulation into beads was confirmed by FTIR. Preparation conditions of the NaAlg‐g‐PVP beads were optimized by considering the percentage entrapment efficiency, particle size, swelling capacity and their release data. In vitro release studies were performed in simulated gastric fluid (pH 1.2) for the initial 2 h, followed by simulated intestinal fluid (pH 7.4) for 4 h. Effects of GA concentration, exposure time to GA, drug/polymer (d/p) ratio, and concentration of HCl on the release of IM were discussed. It was observed that IM release from the beads decreased with increasing GA concentration and exposure time. IM release also decreases with increasing d/p ratio and HCl concentration. The highest IM release was obtained to be 77% for beads crosslinked with 0.027M GA. Swelling experiments were also performed to compute molecular mass between crosslinks of the beads. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Thiol–ene addition enables tailored synthesis of poly(2‐oxazoline)‐graft‐poly(vinyl pyrrolidone) copolymers for binder jetting 3D printing

The continued interest in graft copolymer architectures arises from their unique solution properties and potential for a myriad of applications ranging from drug delivery to adhesives. Poly(vinyl pyrrolidone) (PVP) represents a popular amorphous, water‐soluble polymer used as a polymeric binder in binder jetting additive manufacturing, as fillers in cosmetic products, and for subcutaneous drug delivery systems. This report describes the synthesis of poly(2‐oxazoline) and PVP graft copolymers using a ‘grafting to’ methodology with an efficient thiol–ene ‘click’ reaction. Copolymerization of 2‐methyl‐2‐oxazoline and 2‐(3‐butenyl)‐2‐oxazoline introduced pendent vinyl grafting sites with a predictable absolute number‐average molecular weight. In parallel, reversible addition‐fragmentation chain‐transfer polymerization and subsequent aminolysis yielded well‐defined, oligomeric, thiol‐terminated PVP. Thiol–ene click chemistry enabled the formation of poly(2‐oxazoline)‐graft‐poly(vinyl pyrrolidone) (PMeOx‐g‐PVP) copolymers with varying mole percent grafting sites and PVP graft length. ¹H NMR spectroscopy, aqueous SEC with multiangle light scattering (SEC‐MALS), and bromine titrations confirmed chemical structure, and DSC with TGA elucidated thermal transitions. Aqueous SEC‐MALS and ¹H NMR spectroscopy also determined absolute number‐ and weight‐average molecular weights and average grafting levels, which revealed optimal reaction conditions. Zero‐shear viscosities of 5 and 10 wt% solutions in deionized water for each graft copolymer compared to their linear analogs demonstrated a significant (ca 31%) decrease in viscosity at the same number‐average molecular weight. This decrease in solution viscosity suggested PMeOx‐g‐PVP copolymers as exceptional alternatives to linear analogs for aqueous‐based, binder jetting additive manufacturing.     

Preparation of monodisperse hydrophilic polymer microspheres with N,N′‐methylenediacrylamide as crosslinker by distillation precipitation polymerization

Highly crosslinked cauliflower‐like poly(N,N′‐methylenebisacrylamide) particles were prepared by distillation precipitation polymerization in neat acetonitrile with 2,2′‐azobisisobutyronitrile as initiator. Monodisperse hydrophilic polymer microspheres with various functional groups, such as amide, pyrrolidone and carboxylic acid, with a spherical shape and smooth surface in the size range 120–600 nm were prepared by distillation precipitation copolymerizations of functional comonomers including N‐isopropylacrylamide, N‐vinylpyrrolidone, methacrylic acid with N,N′‐methylenebisacrylamide as crosslinker. The polymer particles were formed and precipitated out from the reaction medium during the distillation of the solvent from the reaction system through an entropic precipitation manner. The effects of the solvent and the degree of crosslinking on the morphology and the loading capacity of the functional groups of the resultant polymer particles were investigated. The resulting polymer particles were characterized with scanning electron microscopy, transmission electron microscopy, dynamic light scattering and Fourier transform infrared spectroscopy. Copyright © 2007 Society of Chemical Industry     

Synthesis and characterization of graft copolymer (guar gum–g–N‐vinyl‐2‐pyrrolidone) and investigation of metal ion sorption and swelling behavior

Graft copolymer of N‐vinyl‐2‐pyrrolidone with guar gum was synthesized and its reaction conditions were optimized for better yield using potassium peroxymonosulfate (PMS) and glycolic acid (GA) as a redox initiator. The effect of PMS, GA, hydrogen ions, guar gum, and N‐vinyl‐2‐pyrrolidone (NVP) along with reaction time and temperature were studied by determining the grafting parameters: grafting ratio, efficiency, conversion, add‐on, homopolymer, and rate of grafting. It was observed that the maximum yield occurred at with a time of 120 min at a temperature of 45°C and a guar gum concentration of 0.4 g/L concentration. The graft copolymer was characterized by infrared spectroscopy and thermal analysis. The activation energy for the grafted and ungrafted gum was calculated. It was observed that the graft copolymer was thermally more stable than the pure gum. The swelling and metal ion sorption behavior of guar gum and guar gum‐g‐N‐vinyl‐2‐pyrrolidone also were studied. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2480–2489, 2006     

Controlled degradation of polylactic acid grafting N‐vinyl pyrrolidone induced by gamma ray radiation

Polylactic acid (PLA) films were surface modified by gamma ray irradiation‐induced grafting of N‐vinyl pyrrolidone (NVP). The in vitro degradation behavior of polylactic acid grafting N‐vinyl pyrrolidone (PLA‐g‐PVP) copolymer was analyzed in terms of weight loss, molecular weight, and thermal properties. Grafting NVP significantly accelerated the degradation of PLA. The mass losses of the copolymers, which were less than that of pure PLA at the beginning of the degradation period, sharply accelerated with increasing degradation time. Moreover, the crystallization temperature decreased with increasing degradation time in the same graft ratio, and the degree of crystallinity increased. Cytotoxicity experiments and animal experiments in vivo were carried out to evaluate the biocompatibility of PLA‐g‐PVP copolymer. Varying graft ratios of PVP could control the degradation rate of copolymers, and thus broadening the applications of this material, such as in tissue engineering scaffolds, drug delivery, and prevention of postsurgical adhesion. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation and characterization of polyaniline N‐grafted with poly(ethyl acrylate) synthesized via atom transfer radical polymerization

Polyaniline (PANI) N‐grafted with poly(ethyl acrylate) (PEA) was synthesized by the grafting of bromo‐terminated poly (ethyl acrylate) (PEA‐Br) onto the leucoemeraldine form of PANI. PEA‐Br was synthesized by the atom transfer radical polymerization of ethyl acrylate in the presence of methyl‐2‐bromopropionate and copper(I) chloride/bipyridine as the initiator and catalyst systems, respectively. The leucoemeraldine form of PANI was deprotonated by butyl lithium and then reacted with PEA‐Br to prepare PEA‐g‐PANI graft copolymers containing different amounts of PEA via an N‐grafting reaction. The graft copolymers were characterized by Fourier transform infrared spectroscopy, elemental analysis, and thermogravimetric analysis. Solubility testing showed that the solubility of PANI in chloroform was increased by the grafting of PEA onto PANI. The morphology of the PEA‐g‐PANI graft copolymer films was observed by scanning electron microscopy to be homogeneous. The electrical conductivity of the graft copolymers was measured by the four‐probe method. The results show that the conductivity of the PANI decreased significantly with increasing grafting density of PEA onto the PANI backbone up to 7 wt % and then remained almost constant with further increases in the grafting percentage of PEA. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synthesis of poly(epichlorohydrin‐g‐methyl methacrylate) and poly(epichlorohydrin‐g‐styrene) graft copolymers by a combination of cationic and photopolymerization methods

Poly(epichlorohydrin‐g‐styrene) and poly (epichlorohydrin‐g‐methyl methacrylate) graft copolymers were synthesized by a combination of cationic and photoinitiated free‐radical polymerization. For this purpose, first, epichlorohydrin was polymerized with tetrafluoroboric acid (HBF₄) via a cationic ring‐opening mechanism, and, then, polyepichlorohydrin (PECH) was reacted ethyl‐hydroxymethyl dithio sodium carbamate to obtain a macrophotoinitiator. PECH, possessing photolabile thiuram disulfide groups, was used in the photoinduced polymerization of styrene or methyl methacrylate to yield the graft copolymers. The graft copolymers were characterized by ¹H‐NMR spectroscopy, differential scanning calorimetry, and gel permeation chromatography. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and properties of carboxymethyl cellulose‐graft‐poly(acrylic acid‐co‐acrylamide) as a novel cellulose‐based superabsorbent

A new cellulose‐based superabsorbent polymer, carboxymethyl cellulose‐graft‐poly(acrylic acid‐co‐acrylamide), was prepared by the free‐radical grafting solution polymerization of acrylic acid (AA) and acrylamide (AM) monomers onto carboxymethyl cellulose (CMC) in the presence of N,N′‐methylenebisacrylamide as a crosslinker with a redox couple of potassium persulfate and sodium metabisulfite as an initiator. The influences of reaction variables such as the initiator content, crosslinker content, bath temperature, molar ratio of AA to AM, and weight ratio of the monomers to CMC on the water absorbency of the carboxymethylcellulose‐graft‐poly(acrylic acid‐co‐acrylamide) copolymer were investigated. The copolymer's structures were characterized with Fourier transform infrared spectroscopy. The optimum reaction conditions were obtained as follows: the bath temperature was 50°C; the molar ratio of AA to AM was 3 : 1; the mass ratio of the monomers to CMC was 4 : 1; and the weight percentages of the crosslinker and initiator with respect to the monomers were 0.75 and 1%, respectively. The maximum water absorbency of the optimized product was 920 g/g for distilled water and 85 g/g for a 0.9 wt % aqueous NaCl solution. In addition, the superabsorbent possessed good water retention and salt resistance. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1382–1388, 2007     

Polymerizable oil‐in‐oil emulsions: poly(vinyl pyrrolidone) dispersions in reactive PDMS medium

The system N‐vinyl‐2‐pyrrolidone (VP)/polydimethylsiloxane diglycidylether (PDMS‐DGE) is a typical example of an oil‐in‐oil emulsion formed by two non‐miscible liquids, where both phases are polymerizable in a ‘one‐pot’ procedure by two distinct reaction mechanisms. These oil‐in‐oil emulsions were characterized by their stability and by the particle size of the dispersed VP phase. Non‐aqueous dispersions (NADs) are obtained in a first step by free radical polymerization of the dispersed VP phase. The reaction kinetics, studied as a function of the initiator type and concentration, show that the polymerization rate is mainly influenced by the partition coefficient of the initiator between both phases. The NAD particle size could be tailored from a micrometer to a nanometer range by in situ formation of PVP‐PDMS graft copolymer. Hydrophilic–hydrophobic two‐phase materials can be obtained by polycondensation, in the presence of polyamines, of the epoxy‐functionalized PDMS continuous NAD phase. Copyright © 2007 Society of Chemical Industry     

Graft copolymerization of itaconic acid onto sodium alginate using ceric ammonium nitrate as initiator

Graft copolymers of sodium alginate (NaAlg) with itaconic acid (IA) were prepared in aqueous solution using ceric ammonium nitrate (CAN) as the redox initiator under N₂ atmosphere. The carboxylic acid groups of IA were neutralized with sodium hydroxide before grafting process. Grafted copolymers as sodium salts (NaAlg‐g‐PIA) were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, intrinsic viscosity measurement, differential scanning calorimetry, and thermogravimetric analysis. The graft yield (GY %) of the graft copolymer and the grafting efficiency (GE %) of the reaction were evaluated comparatively. The effects of the reaction variables such as the reaction time, temperature, percentage of NaAlg, monomer and initiator concentrations on these parameters were studied. It was observed that GY% and GE% increased and then decreased with increasing concentrations of IA and polymerization temperature. The optimum grafting conditions for maximum GY were obtained with a reaction time of 5 h, reaction temperature of 30°C, IA concentration of 0.23 M, CAN concentration of 9.12 × 10^?2 M and percentage of NaAlg 0.5 g/dL. The overall activation energy for the grafting was also calculated to be 1135 cal/mol. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation and antidehydration of interpenetrating polymer network hydrogels based on 2‐hydroxyethyl methacrylate and N‐vinyl‐2‐pyrrolidone

This work reports the preparation of 2‐hydroxyethyl methacrylate (HEMA)/N‐vinyl‐2‐pyrrolidone (NVP) interpenetrating polymer network (IPN) hydrogels by UV‐initiated polymerization in the presence of free radical photoinitiator Darocur 1173 and cationic photoinitiator 4,4′‐dimethyl diphenyl iodonium hexafluorophosphate. The polymerization mechanism was investigated by the formation of gel network. The structure and morphology of the HEMA/NVP IPN hydrogels were characterized by fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM). The results showed that the IPN gels exhibited homogeneous morphology. The dehydration rates of HEMA/NVP IPN hydrogels were examined by the gravimetric method. The results revealed that the hydrogels had a significant improvement of antidehydration ability in comparison with poly(2‐hydroxyethyl methacrylate)(PHEMA) hydrogel embedded physically with poly(N‐vinyl‐2‐pyrrolidone)(PVP). © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Fabrication of a poly(N‐vinyl‐2‐pyrrolidone) modified macroporous polypropylene membrane via one‐pot reversible‐addition fragmentation chain‐transfer polymerization and click chemistry

In this study, a macroporous polypropylene membrane (MPPM) was grafted with hydrophilic poly(N‐vinyl‐2‐pyrrolidone) (PNVP) based on a one‐pot reversible‐addition fragmentation chain transfer (RAFT) polymerization and click chemistry. First, we prepared the clickable membrane by bromination and following S_N2 nucleophilic substitution reaction; then, click chemistry and RAFT polymerization were performed in one‐pot to graft PNVP to the MPPM surface. The surface characterizations, including attenuated total reflectance/Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy, and field‐emission scanning electron microscopy, illustrated that PNVP was really grafted onto the MPPM surface. The permeation and antifouling characteristics of the MPPMs were measured by the filtration of a bovine serum albumin dispersion; this showed that in contrast to the nascent membrane, the grafted membrane efficiently obstructed protein molecules because of the compactly grafted polymer chains. The hydrophilicity and antifouling properties of MPPM were greatly ameliorated after modification. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42649.     

Forgotten monomers: access to α‐modified N‐vinylpyrrolidone polymers via C‐alkylation

Alkylation of N‐vinylpyrrolidone using lithium diisopropylamide and bis(2‐bromoethyl) ether was carried out to obtain 3‐(2‐(2‐bromoethoxy)ethyl)‐1‐vinyl‐2‐pyrrolidone ( 2 ). The derivative 2 represents a versatile starting molecule for further modification via nucleophilic displacement yielding, for example, the bicyclic 2‐vinyl‐8‐oxa‐2‐azaspiro[4.5]decan‐1‐one ( 4 ) or the ammonium salt 3‐diethoxy‐N,N′‐((dimethylbenzyl)ammonium bromide)‐1‐vinyl‐2‐pyrrolidone ( 10 ). Via free radical polymerization of 4 and 10 , the corresponding homopolymers were obtained. Copolymerization of 4 and 10 with N,N′‐diethylacrylamide yielded water‐soluble materials. The thermosensitive solubility of copolymers poly[(2‐vinyl‐8‐oxa‐2‐azaspiro[4.5]decan‐1‐one)‐co‐(N,N′‐diethylacrylamide)] and poly[(3‐diethoxy‐N,N′‐((dimethylbenzyl)ammonium bromide)‐1‐vinyl‐2‐pyrrolidone)‐co‐(N‐vinylpyrrolidone)] in water was investigated. © 2015 Society of Chemical Industry     

“Smart” membrane materials: Preparation and characterization of PVDF‐g‐PNIPAAm graft copolymer

In this research, a smart membrane material of graft copolymer of poly(vinylidene fluoride) with poly(N‐isopropylacrylamide) (PVDF‐g‐PNIPAAm) was synthesized by atom transfer radical polymerization (ATRP) using poly(vinylidene fluoride) (PVDF) as a macroinitiator and direct initiation of the secondary fluorinated site PVDF facilitates grafting the N‐isopropylacrylamide comonomer. The copolymers were characterized by Fourier transform infrared (FTIR), ¹H NMR, gel‐permeation chromatography (GPC), and X‐ray photoelectron spectroscopy (XPS). The temperature‐sensitive membrane was prepared from the PVDF‐g‐PNIPAAm graft copolymers by the phase inversion method. The effects of temperature on the flux of pure water of membrane was investigated. The results showed that alkyl fluorides were successfully applied as ATRP initiators in the synthetic condition and the flux of pure water through the PVDF‐g‐PNIPAAm membrane depended on the temperature change. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1482–1486, 2007     

Surface grafting polymerization of N‐vinyl‐2‐pyrrolidone onto a poly(ethylene terephthalate) nonwoven by plasma pretreatment and its antibacterial activities

The objective of this research was the surface grafting polymerization of biocompatible monomer N‐vinyl‐2‐pyrrolidone (NVP) onto a plasma‐treated nonwoven poly(ethylene terephthalate) (PET) substrate with ultraviolet (UV)‐induced methods. The effects of various parameters, such as the monomer concentration, reaction time, initiator (ammonium peroxodisulfate) concentration, and crosslinking agent (N,N′‐methylene bisacrylamide) concentration, on the grafting percentage were studied. The grafting efficiency of the modified nonwoven PET surfaces reached a maximum at 50 min of UV irradiation and with a 30 wt % aqueous NVP solution. After the plasma activation and/or grafting, the hydrophobic surface of the nonwoven was modified into a hydrophilic surface. NVP was successfully grafted onto nonwoven PET surfaces. The surface wettability showed that the water absorption of NVP‐grafted nonwoven PET (NVP‐g‐nonwoven PET) increased with increasing grafting time. NVP‐g‐nonwoven PET was verified by Fourier transform infrared spectra and scanning electron microscopy measurements. An antibacterial assessment using an anti‐Staphylococcus aureus test indicated that S. aureus was restrained from growing in NVP‐g‐nonwoven PET. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 803–809, 2006