Irradiation‐induced grafting of poly(vinylidene fluoride)‐graft‐poly(styrene sulfonic acid) for the preparation of planar and tube‐shaped air‐drying membranes

A novel air‐drying membrane was developed and investigated as an alternative for planar and tube‐shaped drying membranes composed of Nafion^®. The new membrane is based on poly(vinylidene fluoride) (PVDF) polymer types grafted with polystyrene sulfonic acid. Modification of the PVDF membrane by chemical grafting was initiated via γ‐irradiation of pre‐made film and tube‐shaped samples. The grafting was conducted while the pre‐irradiated PVDF samples were immersed in styrene monomer solution. Three unique characterization methods were introduced to evaluate the ion exchange and barrier functions of the membrane. This investigation focuses on optimizing the degree of grafting yield, and subsequently the control of the membrane's overall functional performances, through (1) monitoring the PVDF's degree of crystallinity and (2) monitoring the styrene monomer solution temperature, respectively. Different levels of crystallinity were achieved by melt blending the PVDF‐copolymer with PVDF‐homopolymer, in various mixing ratios. Another variable examined in this investigation was the introduction of an ionic complex on the sulfonic acid end groups, and its effect on the membrane functional performance was studied. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis and characterization of a poly(acrylic acid)‐graft‐methoxy poly(ethylene oxide) comblike copolymer

A methoxy poly(ethylene oxide) (MPEO) grafted poly(acrylic acid) (PAA) comblike copolymer was synthesized by the direct condensation of MPEO onto the PAA backbone in the presence of dicyclohexyl dimethylcarbodiimide (DCC) and 4‐dimethylaminopyridine (DMAP). Its chemical structure was characterized by Fourier transform infrared and ¹H‐NMR spectroscopies. The effects of different catalysts, solvents, reaction temperatures, and reaction times on the grafting degree of the PAA‐g‐MPEO comblike copolymer were investigated. Compared to p‐toluene sulfonic acid, DMAP/DCC as a catalyst markedly increased the grafting degree. The optimum reaction conditions were a tetrahydrofuran/water mixture solvent, a reaction temperature of 50°C, and a reaction time of 168 h. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Characterization of acrylic acid‐grafted PP membranes prepared by plasma‐induced graft polymerization

Acrylic acid (AA)‐g‐polypropylene (PP) membranes were prepared by grafting AA on to a microporous PP membrane via plasma‐induced graft polymerization. The grafting of AA to the PP membrane was investigated using Fourier transform infrared spectroscopy (FTIR). Pore‐filling of the membranes was confirmed by field emission‐scanning electron microscopy (FESEM) and energy dispersing X‐ray (EDX). Ion exchange capacity (IEC), membrane electric resistance, transport number and water content were measured and analyzed as a function of grafting reaction time. The prepared AA‐g‐PP membranes showed moderate electrochemical properties as a cation‐exchange membrane. In particular, membranes with a degree of grafting of 155% showed good electrical properties, with an IEC of 2.77 mmol/g dry membrane, an electric resistance of 0.4 Ω cm² and a transport number of 0.96. Chronopotentiometric measurements indicated that AA‐g‐PP membranes, with a high IEC had a sufficient conducting region in the membrane. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Study on the Graft Reaction of Poly(propylene) Fiber with Acrylic Acid

Summary: In this paper, the graft of poly(propylene) fiber with acrylic acid is investigated. The effects of grafting temperature, monomer concentration, and grafting time on the grafting degree of acrylic acid onto poly(propylene) fiber are discussed. In contrast to the conventional method of determining the grafting degree gravimetrically, the acid‐base titration method used in this paper was more efficient, even at low grafting degree. High‐performance liquid chromatography (HPLC) was used to estimate the averaged length of the grafted poly(acrylic acid) chains on each grafted site of poly(propylene) backbone. And also a mechanism for the grafting polymerization is proposed.

Possible microstructures of two PP‐g‐AA samples at the same grafting degree.     

Synthesis and characteristics of radiation‐grafted membranes for fuel cell electrolytes

Proton exchange membranes were prepared by simultaneous radiation grafting of styrene onto polytetrafluoroethylene (PTFE) films at room temperature and subsequent sulfonation by chlorosulfonic acid. A series of grafted films with degree of grafting ranging from 0.947% to 35.4% were obtained. The effect of styrene concentration on the grafting yield was investigated and the maximum value was obtained at a monomer concentration of 70‐vol%. The structure of PTFE‐graft‐polystyrene sulfonic acid membranes was studied by infrared spectroscopy. The membrane properties, such as water uptake, ion exchange capacity, swelling performance and ionic resistance, were studied as functions of the degree of grafting. The thermal and chemical stability of the sulfonic acid membranes was also investigated. The membrane properties were found to depend on the degree of grafting and the amorphous character of the membrane structure, and the better membrane properties were obtained at a degree of grafting in the range 12–21%. Copyright © 2003 Society of Chemical Industry     

Surface initiated ATRP of acrylic acid on dopamine‐functionalized AAO membranes

A facile method for surface‐initiated atom transfer radical polymerization (ATRP) on the anodic aluminum oxide (AAO) membranes has been developed. The AAO membrane was firstly functionalized by poly(dopamine), the bromoalkyl initiator was then immobilized on the poly(dopamine) functionalized AAO membrane surface in a two‐step solid‐phase reaction, followed by ATRP of acrylic acid in a aqueous solution. The poly(acrylic acid) (PAAc)‐grafted AAO membranes were characterized by X‐ray photoelectron spectroscopy, fourier transform infrared spectroscopy and scanning electron microscopy. The XPS and FTIR results indicated that PAAc was successfully grafted on the AAO membrane surface. The degree of grafting increases linearly with the increase of monomer concentration, and it reaches a plateau when the reaction time up to 4 h. The results indicate that the thickness of the grafted polymer inside the isocylindrical pores of AAO membranes could be well controlled by changing the reaction time and monomer concentration. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Kinetics study of radiation‐grafting of acrylic acid,acrylonitrile, and their mixture onto wool fabric

The effect of monomer concentration, exposure time, irradiation temperature, and weaving direction on the kinetics of grafting acrylic acid (AA), acrylonitrile (AN), and their mixture onto wool fabric has been studied at the dose rate of 1.38 Gy/s. The degree of grafting is found to depend on the methanol‐to‐water solvent ratio and fabric‐to‐liquor ratio. The grafting rate and rate constant are dependent on irradiation temperature, type of grafted monomer, and weaving direction. The grafting rates increase with the increase in irradiation temperature (276–308 K). The calculated activation energy is nearly the same (16.4–17.2 kJ mol^?1) and the preexponential rate constant is dependent on the type of grafted monomer. The grafting of AA, AN, and their mixture are confirmed from the dyeing affinity of grafted fabrics towards Sandocryl Blue (SB), a basic dye. The formation of wool grafts and structural changes resulting from grafting were verified by using FTIR spectrometry and X‐ray diffraction analysis. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4328–4340, 2006     

UV‐radiation–induced preirradiation grafting of methyl methacrylate onto lignocellulose fiber in an aqueous medium and characterization

The preirradiation method of grafting has been established by ultraviolet radiation. Methyl methacrylate (MMA) was grafted onto jute fiber in an aqueous medium. The variation of graft weight with UV‐radiation time, monomer concentration, and reaction time was investigated. The conversion of monomer into homopolymer and graft copolymer was evaluated. The graft weight passes through a maximum value (～ 122%) with UV‐radiation time. The optimum value of the monomer concentration was evaluated for maximum degree of grafting. Graft copolymerization of MMA onto lignocellulose fiber significantly increases the elongation at break (～ 65%) compared to that of the “as‐received” sample. However, a linear decrease on breaking load was observed with the increase of graft weight. The estimation of degree of grafting was achieved using an IR technique by correlating band intensities with the degree of grafting. Considering the water‐absorption property, the grafted sample showed a maximum up to 61% decrease in hydrophilicity compared to that of the as‐received sample. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1667–1675, 2004     

Improving the hydrophilicity of polyethersulfone membrane by the combination of grafting technology and reverse thermally induced phase separation method

In this work, surface grafting modification technology was combined with reverse thermally induced phase separation (RTIPS) method in order to improve the structure and permanent hydrophilicity of polyethersulfone (PES) membranes. Acrylic solution with different concentrations was grafted on the surface of PES membranes while grafting temperature and grafting time were also varied. The modified PES membranes were characterized in all aspects. Attenuated total reflectance Fourier transform-infrared confirmed successful modification of the PES membrane by grafting acrylic acid. Scanning electron microscopy revealed that homogeneous porous top surface as well as spongy-like cross-section structure appeared in the membrane by RTIPS procedure. Moreover, porosity was affected by changes of acrylic acid concentration, grafting temperature, and grafting time. Atomic force microscopy showed that grafting acrylic acid gave a reduction in roughness of PES membrane. Combined with the decreased values of contact angle, the hydrophilicity and antifouling performance of the PES membrane were improved. The pure water flux and BSA rejection rate of the grafted PES membranes were remarkably improved for pure PES membrane and attained a maximum, which was 1,646.24 L/(m²h) and 94.5%, respectively. The long-term test demonstrated that grafting membranes exhibited outstanding elevated water flux recovery ratio (>85%).     

Plasma‐induced graft polymerization of acrylic acid onto poly(ethylene terephthalate) films

The graft polymerization of acrylic acid was carried out onto poly(ethylene terephthalate) films that had been pretreated with argon plasma and subsequently exposed to oxygen to create peroxides. The influence of synthesis conditions, such as plasma treatment time, plasma power, monomer concentration, temperature, and the presence of Mohr's salt, on the degree of grafting was investigated. The observed initial increase in grafting with monomer concentration accelerated at about 20% monomer. The grafting reached a maximum at 40% monomer and subsequently decreased with further increases in monomer concentration. The reaction temperature had a pronounced effect on the degree of grafting. The initial rate of grafting increased with increasing temperature, but the degree of grafting showed a maximum at 50°C. The activation energy of the grafting obtained from an Arrhenius plot was 29.1 kJ/mol. The addition of Mohr's salt to the reaction medium not only led to a homopolymer‐free grafting reaction but also diminished the degree of grafting. The degree of grafting increased with increasing plasma power and plasma treatment time. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2993–3001, 2001     

Properties of grafted polymer metal complexes as ion exchangers and its electrical conductivity

A polyelectrolyte has been prepared, as a potential proton exchange polymer, by grafting acrylic acid/acrylamide (AAc/AAm) and acrylic acid/acrylonitrile (AAc/AN) comonomers onto a low‐density polyethylene film via gamma irradiation. The developed polymers were characterized by evaluating their physico‐chemical properties such as ion exchange capacity (IEC) and electrical conductivity as functions of grafting yield. The grafted film at different compositions was characterized by Fourier transform infrared, thermogravimetric analysis, and scanning electron microscopy. IEC of the grafted film at grafting % 191 and monomer concentration ratio 50:50 for (LDPE‐g‐AAc/AAm) was found to be more than that for (LDPE‐g‐AAc/AN). The electrical conductivity was found to be greatly affected by the comonomer composition, were it increased as the degree of grafting increased for all grafted films. After alkaline treatment with 3% KOH (3% potassium hydroxide), the electrical conductivity of the grafted films found to be increased. The presence of potassium as counter ion maximized the electrical conductivity of the grafted films. The electrical conductivity of Cu‐membrane complexes was higher than that of both Co (cobalt) and Ni (Nickel) complexes. It has been indicated that, the electrical conductivity increased by increasing both Cu ion content and temperature. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers.     

Plasma‐induced grafting of hydroxyethyl methacrylate (HEMA) onto chitosan membranes by a swelling method

Hydroxyethyl methacrylate (HEMA) was grafted onto chitosan membranes by plasma‐graft polymerization. Effects of monomer concentration, plasma power and plasma time on the amount of grafting were investigated. The results showed that there were two processes: grafting polymerization and etching of the membrane. The surface of the grafted membrane was evaluated by FTIR. Scanning electron microscopy indicated that the surface morphology of the grafted membrane could be adjusted through plasma power. Water contact angles of the chitosan surface decreased from 78.2° to 45.4° while the amount of grafting increased from 0 to 12.2%, indicating improved hydrophilicity of the membrane surface. Permeation coefficients through the original membrane, the membrane treated at 55 W for 15 min, and the membrane treated at 55 W for 30 min for creatinine were 9.12 × 10^?7, 10.6 × 10^?7 and 8.57 × 10^?7 cm² s^?1, respectively. Thermogravimetry and mechanical testing showed that there were no significant changes on the bulk property of chitosan membrane after modification. © 2003 Society of Chemical Industry     

UV‐radiation‐induced preirradiation graft copolymerization of methacrylic acid and acrylic acid onto jute fibre

UV‐radiation‐induced graft copolymerization of methacrylic acid and acrylic acid onto jute fibre was carried out using a preirradiation method with 1‐hydroxycyclohexyl‐phenylketone as a photoinitiator. 2‐methyl‐2‐propene 1‐sulfonic acid, sodium salt was incorporated into the grafting solution in suppressing the homopolymer/gel formation and facilitating graft copolymerization. In comparison, results showed that the type of monomer significantly influence on grafting. The results of the characterisation showed that the graft weight and the type of monomer have significant influence on the mechanical and water absorption properties in the case of grafted samples. Copyright © 2004 Society of Chemical Industry     

Electrokinetic properties of polypropylene‐layered silicate nanocomposite fibers

Nanocomposite fibers based on polypropylene (PP) polymer were prepared with different content of nanofiller. Filaments were spun from an isotactic iPP homopolymer. Montmorillonite modified by N,N‐dimethyl‐N,N dioctadecylammonium cations was used for preparation of PP nanocomposite fibers. A PP grafted with acrylic acid was added as a coupling agent. Nanocomposite fibers were characterized, i.e., the surface morphology of PP nanocomposite fibers was observed and surface properties were defined by electrokinetic properties determination by zeta potential measurements. For particle distribution observation the plasma etching was involved as a method for sample preparation. The addition of nanoparticles has an impact on ZP value of nanofilled fibers, however, isoelectric point IEP is not significantly influenced by different concentrations of nanofiller. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Proton exchange membranes by grafting of styrene–acrylic acid onto FEP by preirradiation technique. II. Physicochemical properties of the membrane and its sulfonated derivatives

Poly(tetrafluoroethylene‐co‐haxafluoropropylene) (FEP)‐g‐styrene–acrylic acid and its sulfonated derivative membranes were prepared by graft copolymerization of styrene–acrylic acid onto FEP by using preirradiation of γ‐ray technique followed by sulfonation. The physiochemical properties such as ion exchange capacity, water uptake, ionic resistance of the grafted membranes, and their sulfonated derivatives were studied as a function of degree of grafting. These membranes on sulfonation gave acid base, indicating property. The membranes gave yellow color in acidic medium and purple color in alkali medium. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2318–2325, 2004     

Zwitterionic sulfobetaine‐modified non‐woven fabric for blood filtration

Blood filtration requires a high removal ratio of leukocytes and with simultaneous high recovery ratio of platelets and other beneficial components. Problems are often encountered with blood filter materials in terms of high platelet loss. Zwitterions such as phosphorylcholine, sulfobetaine and carboxybetaine show effective resistance against protein adsorption and platelet adhesion. The study reported was aimed at achieving surface modification of poly(butylene terephthalate) non‐woven fabric (PBTNF) using UV radiation‐induced graft copolymerization of a zwitterionic sulfobetaine, N‐(3‐sulfopropyl)‐N‐methacroyloxyethyl‐N,N‐dimethylammonium betaine (SMDB), in order to improve the wettability and platelet recovery ratio of the PBTNF. Attenuated total reflection Fourier transform infrared and X‐ray photoelectron spectroscopy results showed that SMDB was successfully grafted onto the PBTNF. Photoinitiator concentration, monomer concentration and UV irradiation time affected markedly the degree of grafting. Critical wetting surface tension, water wetting time and hemolysis tests showed an improvement in wettability and blood compatibility as a result of graft copolymerization of SMDB. A blood filter material composed of SMDB‐modified PBTNF reduced platelet adhesion and had higher platelet recovery compared to poly(acrylic acid)‐modified PBTNF. It was found that SMDB monomer was successfully grafted onto PBTNF using UV radiation. The degree of grafting of SMDB could be controlled by varying the photoinitiator concentration, monomer concentration and UV irradiation time. SMDB‐modified PBTNF showed significant improvement in wettability and blood compatibility. The zwitterionic structure of SMDB is resistant to platelet adhesion. The SMDB‐modified PBTNF could be a candidate for a blood filter material and in other medical applications. Copyright © 2010 Society of Chemical Industry     

Gentamicin‐loaded poly(acrylic acid)‐grafted cotton fibers,part 1: Synthesis,characterization, and preliminary drug release study

This study describes preparation of poly (acrylic acid)‐grafted cotton fibers and release of antibiotic drug gentamicin sulfate from them under physiological conditions. Poly(acrylic acid) has been grafted onto cellulose backbone of cotton fibers via Ce(IV)‐initiated polymerization in aqueous medium. The conditions obtained for optimum grafting were as follows: initiation time 30 min; initiation temperature 37°C; monomer concentration 27.8 mM; grafting temperature 30°C; nitric acid (catalyst) concentration 0.1M. The grafted fibers were characterized by FTIR, TGA, and SEM analysis. The antibiotic drug gentamicin sulfate (GS) was loaded into the grafted fibers by equilibration method and release was studied under physiological conditions. The kinetic release data was interpreted by first‐order kinetic model. Finally, drug‐loaded fibers showed fair antibacterial action against Escherichia coli. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis of polymer‐grafted natural rubbers by radical photopolymerization of vinyl monomers initiated from the rubber chains

The synthesis of polymer‐grafted natural rubbers (NRs) was considered through photopolymerization of vinyl monomers initiated from N,N‐diethyldithiocarbamate groups previously introduced onto cis 1,4‐polyisoprene units of NR chains. The development of the procedure was made with methyl methacrylate (MMA) as monomer. First, initiation of MMA photopolymerization was tested using a model molecule of the N,N‐diethyldithiocarbamate‐functionalized 1,4‐polyisoprene unit to verify the feasibility of the procedure considered. Then, MMA polymerization was successfully initiated from N,N‐diethyldithiocarbamate‐functionalized NR backbone used as macroinitiator, and the conditions of grafting were optimized. It was shown that MMA grafting could occur either in monomer medium, in solution in toluene, and in latex medium, and that the quantities of homopolymer formed were still low. Thereafter, grafting studies were performed with other vinyl monomers (styrene, methacrylonitrile, acrylamide, acrylic acid) showing that grafting efficiency depends essentially on the nature of the monomer. The method developed here was shown particularly well adapted for the synthesis of polymer‐grafted NR with monomers of low polarity. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation and characterization of acrylic acid‐treated bacterial cellulose cation‐exchange membrane

The feasibility of using bacterial cellulose as a source for environmentally compatible ion‐exchange membranes (IEM) was studied. Bacterial cellulose was modified with cation‐exchangeable acrylic acid (AAc) by UV‐graft polymerization to prepare membranes having ion‐exchange capacity (IEC) and greater structural density. Fourier transform infrared (FTIR) spectra showed that acrylic acids were successfully bound to bacterial cellulose. Morphological changes of acrylic acid‐treated bacterial cellulose were examined through scanning electron microscopy. A dense structure of the membrane increased with increasing UV‐irradiation time. Acrylic‐modified bacterial cellulose membrane showed reasonable mechanical properties, such as tensile strength of 12 MPa and elongation of 6.0%. Also the prepared membranes were comparable to the commercial membrane CMX in terms of the electrochemical properties, ie IEC of 2.5 meq g^?1‐dry mem, membrane electric resistance of 3 ohm cm², and transport number of 0.89. Copyright © 2003 Society of Chemical Industry     

A pH‐sensitive porous chitosan membrane prepared via surface grafting copolymerization in supercritical carbon dioxide

We report the successful grafting copolymerization of acrylic acid (AA) on a crosslinked porous chitosan membrane in supercritical carbon dioxide at pressures ranging from 13 to 25 MPa with the use of benzyl peroxide (BPO) as the reduction–oxidation free radical initiator. The effects of reaction pressure, initiator concentration, monomer concentration, reaction temperature and reaction time on grafting yield (GY) were investigated. GY initially increases and then decreases with increasing polymerization temperature and AA and BPO concentrations. The optimum grafting conditions to obtain maximum GY are as follows: 8 h reaction time, 80 °C reaction temperature, 3.05 × 10^?2 g mL^?1 AA concentration, 3 × 10^?3 g mL^?1 BPO concentration and 16 MPa reaction pressure. The water flux of the grafted chitosan membranes decreases with pH from 2 to 7, even at considerably low GY (0.95 wt%). A novel and green modification method has been developed for the preparation of biopolymer‐based membranes. © 2014 Society of Chemical Industry