Preparation of proton exchange membranes by radiation-induced grafting of alpha methyl styrene–butyl acrylate mixture onto polyetheretherketone (PEEK) films

Radiation-induced graft copolymerization of alpha methyl styrene (AMS)–butyl acrylate (BA) mixture onto poly(etheretherketone) (PEEK) was carried out to produce copolymer films which were subsequently sulfonated to develop proton exchange membranes. The characterization of membranes was carried out with infrared spectroscopy (FTIR), differential scanning calorimetry, thermogravimetric analysis, X-ray diffraction analysis (XRD), contact angle and electron probe microanalysis (EPMA). The presence of sulfonic acid groups within the polymer matrix was confirmed by FTIR. The crystallinity of membranes decreased significantly upon sulfonation process. The melting temperature of the membranes also decreased as compared to the virgin and the grafted films. At the same time, glass transition temperature (T _g) of membranes increased as the grafting increased. Virgin film showed stable thermogram up to ~500 °C while the grafted film had two-step degradation pattern. Sulfonation introduced one additional decomposition range in the membrane. Contact angle images showed the hydrophilic nature of the membrane surface. The EPMA showed the presence of the sulphur across the membrane matrix in a homogenous manner. The membranes showed low resistivity of 62 Ω cm for the graft level of 27 %.     

Radiation‐induced graft copolymerization of α‐methyl styrene and butyl acrylate mixture into polyetheretherketone films

Radiation‐induced graft copolymerization of α‐methyl styrene (AMS), butyl acrylate (BA) monomers, and their mixture was investigated on poly(etheretherketone) films. The graft polymerization was carried out using ethyl methyl ketone as the medium for the copolymerization and the maximum degree of grafting of 27% was achieved. It was observed that the grafting is significantly influenced by the reaction conditions, such as reaction time, preirrradiation dose, monomer concentration, monomer ratio, and the reaction temperature. The degree of grafting increases as the monomer concentration increases up to 30%, beyond which a decrease in the grafting was observed. The degree of grafting showed a maximum at 40% BA content in the monomer mixture. The temperature dependence of the grafting process shows decreasing grafting with the increase in the reaction temperature. The presence of AMS and BA grafts in the film was confirmed by FTIR spectra. The relative change in the PBA/PAMS fraction with respect to the reaction temperature has been found in this study. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Simultaneous graft copolymerization of 2‐hydroxyethyl methacrylate and acrylic acid onto polydimethylsiloxane surfaces using a two‐step plasma treatment

Acrylic acid (AAc) and 2‐hydroxyethyl methacrylate (HEMA) mixtures were simultaneously grafted onto the surfaces of polydimethylsiloxane (PDMS) films using a two‐step oxygen plasma treatment (TSPT). The first step of this method includes: oxygen plasma pretreatment of the PDMS films, immersion in HEMA/AAc mixtures, removal from the mixtures, and drying. The second step was carried out by plasma copolymerization of preadsorbed reactive monomers on the surfaces of dried pretreated films. The effects of pretreatment and polymerization time length, monomer concentration, and ratio on peroxide formation and graft amount were studied. The films were characterized by attenuated total reflection Furrier transformer infrared (ATR‐FTIR) spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), zeta potential, surface tension, and water contact angle measurements. The ATR‐FTIR spectrum of the modified film after alkaline treatment showed the two new characteristic bands of PHEMA and PAAc. Both increase the polar part of surface tension (γ_p) after grafting and the evaluation of surface charge at pH 1.8, 7, and 12 confirmed the presence of polar groups on the surface of grafted films with a mixture of HEMA/AAc. Morphological studies using both AFM and SEM evaluation illustrated various amounts of grafted copolymer on the surface of PDMS films. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Structural investigations of poly(ethylene terephthalate)‐graft‐polystyrene copolymer films

Structural investigations of poly(ethylene terephthalate)‐graft‐polystyrene (PET‐g‐PS) films prepared by radiation‐induced grafting of styrene onto commercial poly(ethylene terephthalate) (PET) films were carried out by FTIR, X‐ray diffraction (XRD), and differential scanning calorimetry (DSC). The variation in the degree of crystallinity and the thermal characteristics of PET films was correlated with the amount of polystyrene grafted therein (i.e., the degree of grafting). The heat of melting was found to be a function of PET crystalline fraction in the grafted films. The grafting is found to take place by incorporation of amorphous polystyrene grafts in the entire noncrystalline (amorphous) region of the PET films and at the surface of the crystallites. This results in a decrease in the degree of crystallinity with the increase in the degree of grafting, attributed to the dilution of PET crystalline structure with the amorphous polystyrene, without almost any disruption in the inherent crystallinity. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1949–1955, 2002; DOI 10.1002/app.10515     

Characterization of radiation-grafted polymer films using CP/MAS NMR spectroscopy and confocal Raman microscopy

Preirradiated poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP) base film were grafted with different amounts of an α-methylstyrene (AMS) and methacrylonitrile (MAN) copolymer. The molar ratio of AMS and MAN in the grafted polymer was determined using ¹³C- CP/MAS NMR spectroscopy and compared with the molar ratio determined with FTIR spectroscopy. The distribution of the components across the thickness of the grafted films was determined using confocal Raman microscopy. The validation of the confocal Raman microscopy was performed with FEP films grafted with MAN only, where pronounced grafting fronts were observed. The local degree of grafting for AMS/MAN co-grafted FEP films was calculated for each sample based on the intensity profiles, taking the mass of the grafted polymer and its molar ratio into account. The grafting of the AMS/MAN co-grafted films was found to be homogeneous over the thickness, even in case of small amounts of the copolymer (15 mass%). The homogeneity of the grafting across the film thickness is a prerequisite to obtain sufficient proton conductivity after sulfonation of the radiation-grafted films. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Melt grafting of maleic anhydride onto polypropylene with assistance of α‐methylstyrene

Melt grafting of maleic anhydride (MA) and α‐methylstyrene (AMS) onto polypropylene (PP) was performed by reactive extrusion. Effects of AMS on the graft degree of MA, crystallization behavior, and thermal properties of the graft copolymer were investigated. Results show that the addition of AMS as a comonomer can efficiently improve the MA graft degree. When the molar ratio of AMS to MA is 0.9:1, the maximum MA graft degree is attained, which increases about 56% compared with that using single monomer of MA. The results of the graft degree of MA obtained by chemical titration (CT) agree well with those obtained by Fourier transform infrared spectroscopy (FTIR). Melt flow rate (MFR) measurements indicate that the addition of AMS effectively reduces the degradation of PP molecules. The wide‐angle X‐ray diffraction (WAXD) results show that in comparison with the PP‐g‐MA sample, the PP‐g‐(MA‐AMS) sample shows no new crystalline form, but has a slight decrease in the average crystalline domain size. According to the results of thermogravimetry (TG) and differential scanning calorimetry (DSC), the graft PP in the presence of AMS exhibits a lower melting point and a higher crystallization temperature and thermal stability in comparison with that without AMS. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

Radiation‐induced graft copolymerization of methylmethacrylate onto poly(tetrafluoroethylene‐co‐ethylene) film

Modification of poly(tetrafluoroethylene‐co‐ethylene), Tefzel (ETFE), film has been carried out by grafting methylmethacrylate (MMA) by radiation method including preirradiation and double‐irradiation methods. Percentage of grafting has been determined as a function of the (i) total dose, (ii) monomer concentration, (iii) amount of liquor ratio, (iv) reaction time, and (v) temperature.The effect of different alcohols such as methanol, ethanol, 2‐propanol, n‐butanol, n‐pentanol, and 2‐ethoxy ethanol on percentage of grafting of MMA was also studied. The graft copolymers were characterized by IR spectroscopy and thermogravimetric analysis (TGA). Methylmethacrylate produces higher percentage of grafting by preirradiaton method than double‐irradiation method. MMA‐grafted ETFE films (S_irr), i.e., prepared by preirradiation involving single irradiation show better thermal stability than MMA‐grafted ETFE films (D_irr), i.e., prepared by double irradiation and unmodified ETFE film. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation and characterization of grafting polyacrylamide from PET films by SI‐ATRP via water‐borne system

The grafted homopolymer and comb‐shaped copolymer of polyacrylamide were prepared by combining the self‐assembly of initiator and water‐borne surface‐initiated atom transfer radical polymerization (SI‐ATRP). The structures, composition, properties, and surface morphology of the modified PET films were characterized by FTIR/ATR, X‐ray photoelectron spectroscopy (XPS), contact angle measurement, and scanning electronic microscopy (SEM). The results show that the surface of PET films was covered by equable grafting polymer layer after grafted polyacrylamide (PAM). The amount of grafting polymer increased linearly with the polymerization time added. The GPC date show that the polymerization in the water‐borne medium at lower temperature (50°C) shows better “living” and control. After modified by comb‐shaped copolymer brushes, the modified PET film was completely covered with the second polymer layer (PAM) and water contact angle decreased to 13.6°. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

HEMA‐grafted chitosan for dialysis membrane applications

Chitosan was graft copolymerized with HEMA (2‐Hydroxyethylmethacrylate) for the development of blood‐compatible dialysis membranes. The permeation characteristics of HEMA‐grafted chitosan films for four different solutes creatinine, urea, glucose, and albumin was studied in vitro at 37°C for assessment of the suitability as dialysis membranes. The grafted film CH‐12.5 composition (425% grafting) showed very high permeation to creatinine by reaching the equilibrium within 45 min. The compositions CH‐7.5 and CH‐12.5 showed excellent permeation to glucose when compared to virgin chitosan films. In the case of urea permeation, all the grafted compositions exhibited higher percent permeation than the virgin chitosan films. The copolymer films CH‐7.5 and CH‐12.5 showed enhanced permeability for the high molecular weight solute, albumin. The other grafted copolymer compositions followed almost the same trend as that of chitosan for the low molecular weight solutes as well as the high molecular weight solute. The copolymer films were also found to be highly blood compatible, noncytotoxic, and biodegradable. Hence, the need for developing blood‐compatible chitosan membranes with desirable permeability properties is achieved by the graft copolymerization of HEMA onto chitosan. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2960–2966, 2006     

The study of melt grafting mechanism of acrylic acid and butyl acrylate onto low density polyethylene and its application as internal plasticizer

Melt grafting of acrylic acid (AA) and butyl acrylate (BA) (equal molar ratios) onto low‐density polyethylene (LDPE) was carried out in Haake internal mixter by free radical grafting copolymerization. The graft degree of AA and BA in the grafted LDPE (LDPE‐g‐(AA+BA)) was determined by FTIR. The influences of initiator on the graft degree of AA and BA, melt flow rate (MFR), and gel content were investigated, and the optimum conditions were obtained. The successive self‐nucleation/annealing (SSA) thermal fraction method was used to characterize the molecular structure and polydispersity of LDPE‐g‐(AA+BA) with various graft degrees. The effects of thermal fraction parameters on fraction of LDPE‐g‐(AA+BA) were investigated. On the basis of the results of SSA, the grafting reaction mechanism of AA and BA onto LDPE was proposed, i.e., grafting reaction preferentially occurred on the tertiary carbons of LDPE. The grafted LDPE possessed suitable reactivity and rheological property. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and evaluation of fluorosilicone‐modified starch for protection of historic stone

Starch is sensitive to moisture and is weak to durability in the protection application to ancient relics. Therefore, two fluorosilicone‐modified starches are firstly prepared and evaluated for the protection of historic stones. The fluoro‐silicone copolymer grafted starch of P(VTMS/12FMA)‐g‐starch is synthesized by grafting copolymer of vinyltrimethoxysilane (VTMS) and dodecafluoroheptyl methacrylate (12FMA) onto starch. While the fluoro‐silicone starch latex of VTMS‐starch@P(MMA/BA/3FMA) is obtained by emulsion polymerization of VTMS primarily grafted‐starch (VTMS‐starch) with methyl methacrylate (MMA), butyl acrylate (BA) and 2,2,2‐trifluoroethyl methacrylate (3FMA). The grafting fluorosilicone copolymer onto starch improves obviously their hydrophobic and thermal properties. Comparatively, VTMS‐starch@P(MMA/BA/3FMA) film performs higher water contact angle (107°) and thermal stability (350–430°C) than p(VTMS/12FMA)‐g‐starch film (72°, 250–420°C) due to the migration of fluorine‐containing group onto the surface of film during the film formation. Therefore, VTMS‐starch@P(MMA/BA/3FMA) shows much better protective performance in water‐resistance, and salt/freeze‐thaw resistance for stone samples. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41650.     

Properties of PHMS‐g‐p [butylacrylate (BA)‐N‐hydroxyl‐methyl acrylamide (NMA)] graft copolymer emulsions

Emulsion graft copolymerization of poly(hydrogenmethylsiloxane) (PHMS) and butyl acrylate (BA) in the presence of functional comonomer N‐hydroxyl‐methyl acrylamide (NMA) was conducted by batch emulsion copolymerization to modify the properties of polysiloxane. Morphology of graft copolymer particles was characterized by transmission electron microscopy. The effect of polymerization method, PHMS content, initiator concentration, and NMA content on stability of emulsion, morphology, size of particle, and rheological properties were investigated. It has been found that stability of emulsion is better by semicontinuous emulsion polymerization than that of batch emulsion polymerization and it increased with increasing PHMS‐NMA concentration. Increasing PHMS concentration and NMA concentration, the particle size and the viscosities increase. The property of resistance to electrolytes of graft copolymer emulsions and swelling property of film were also discussed. Results showed PHMS‐g‐P [butylacrylate (BA)‐N‐hydroxyl‐methyl acrylamide (NMA)] graft copolymer emulsion has good resistance to electrolytes and the water absorption of its film increases with increasing BA‐NMA content grafted onto PHMS. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 2209–2217, 1999     

Control of biodegradability of poly(3‐hydroxybutyric acid) film with grafting acrylic acid and thermal remolding

Radiation‐induced graft polymerization of acrylic acid (AAc) on poly(3‐hydroxybutyric acid) (PHB) film was carried out and the resulting film was thermally‐remolded. The PHB films grafted with AAc (PHB‐g‐AAc) having a degree of grafting higher than 5% completely lost the enzymatic degradability. The enzymatic degradability of the grafted film was recovered by thermal remolding. The highest enzymatic degradation rate was observed at degree of grafting of 10% after thermal remolding. The PHB‐g‐AAc films and thermally‐remolded PHB‐g‐AAc films were characterized by contact angle and differential scanning calorimetry. The enzymatic degradability of PHB‐g‐AAc films was lost by the grafted AAc, which covered the surface of PHB film. The acceleration of enzymatic degradation in the remolded PHB‐g‐AAc films was mainly caused by decrease of crystallinity of PHB by dispread of grafted AAc during thermal remolding. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3856–3861, 2006     

Preparation of ion‐exchange membranes by hydrolysis of radiation‐grafted polyethylene‐g‐polyacrylamide membranes

Polyethylene‐g‐polyacrylamide membranes were prepared by graft polymerization of acrylamide onto polyethylene films using a preirradiation method. The ion‐exchange membranes were obtained by the hydrolysis of grafted films so as to transform amide groups into carboxyl groups. The fraction of amide groups transformed into carboxyl groups was limited to ～0.5. The characterization and thermal behavior of membranes with different degrees of grafting were evaluated by FTIR, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) measurements. The heat of fusion and the crystallinity of polyethylene decreased considerably in the hydrolyzed membranes depending on the degree of grafting. It was found that the grafting of acrylamide led to the reduction in crystallinity due to disruption of the crystallites (crystal defects) and dilution of the inherent crystallinity (dilution effect). The contribution of the hydrolysis step to the crystallinity decrease was negligible. The thermal stability of the membranes as obtained from TGA showed considerable enhancement after hydrolysis. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 149–154, 2003     

Photografting polymerization of polyacrylamide on poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) films. II. Wettability and crystallization behaviors of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate)‐graft‐polyacrylamide films

The wettability and crystallization behaviors of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV)‐graft‐polyacrylamide (PAM) films were studied. X‐ray photoelectron spectroscopy analyses illustrated that about 62 atom % of the total polar functionalities on the grafted film with 17% grafting percentage (GP) was amide groups. Wide‐angle X‐ray diffraction results suggest that grafted PAM induced defects in PHBV crystals and influenced their crystal structure. Differential scanning calorimetry (DSC) spectra showed the two melting regions, 60–90 and 145–170°C, of the imperfect PHBV crystals of the grafted films. Grafted PAM could suppress the recrystallization of PHBV, which was consistent with the polarizing optical microscopy results, in which the maximum PHBV spherulite diameter decreased from 350 μm for the PHBV film to 50 μm for the film with 53% GP. In addition, DSC studies revealed that the crystallinity of the grafted films decreased with increasing GP, which facilitated the diffusion of water into the films. The water contact angle of grafted films decreased and the water‐swelling percentage increased as GP went up. These results demonstrate the potential of PHBV‐g‐PAM for wettable surface constructs in tissue engineering applications. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Phase behavior of binary blends of PP/PP‐g‐AA: limitations of the conventional characterization techniques

In this study, miscibility/immiscibility issues of a binary blend consisting of polypropylene (PP) and acrylic acid grafted polypropylene (PP‐g‐AA) were investigated using rheometry, DSC, dynamic mechanical and thermal analysis (DMTA), AFM and time‐of‐flight secondary‐ion mass spectrometry (ToF‐SIMS). Phase separation analysis of such blend systems is a challenge and complex due to chemically similar components as well as the low value of acrylic acid groups in the graft copolymer. Thus, it is crucial to determine if the present blend shows some degree of miscibility or develops co‐continuous morphology between the components. The analysis of rheometrical, DSC and DMTA results indicated no sensitivity of these classical techniques for detecting the miscibility or immiscibility of such a system. However, AFM data effectively detected dispersed‐phase domains corresponding to the PP‐g‐AA rich phase. The results, for the first time, indicated that the start of phase separation occurs at a critical copolymer concentration between 2 and 5 wt%. Furthermore it was observed that, as the PP‐g‐AA content increases, the size and continuity of the dispersed phase increase and reach a highly continuous morphology. Additionally, ToF‐SIMS chemical imaging was carried out to aid in the interpretation of the AFM data. © 2016 Society of Chemical Industry     

Functionalization of poly(tetrafluoroethylene‐co‐ethylene) film by radiation‐induced graft copolymerization

To introduce functional moieties to Tefzel film, a copolymer of tetrafluoroethylene and ethylene, graft copolymerization of vinyl monomers such as acrylonitrile (AN) and methacrylonitrile (MAN) was attempted by a preirradiation method in aqueous medium. Optimum conditions for obtaining the maximum percentage of grafting have been evaluated for both monomers. Maximum grafting of AN (52.2%) and MAN (77.7%) is obtained at a total dose of 3.14 and 2.69 × 10⁴ Gy, respectively, using [AN] = 3.018 mol/L and [MAN] = 1.177 mol/L in 10 mL of water. The effect of aliphatic alcohols of varying chain length, such as methanol, ethanol, isopropanol, n‐butanol, and cyclohexanol, on percentage add‐on of AN and MAN has also been studied. It has been found that all the alcohols decreased the percentage of grafting. Characterization of Tefzel and grafted Tefzel films has been carried out by IR spectroscopy and thermogravimetric analysis. Grafted Tefzel film has been found to have improved thermal resistance. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1171–1178, 2000     

Fuel Cell Membranes Based on Grafted and Post‐Sulfonated Glycidyl Methacrylate (GMA)

Glycidyl methacrylate (GMA) was pre‐irradiation grafted into ETFE base film of 25 μm thickness up to graft levels of 300%. The grafted films were sulfonated using a mixture of sulfite and bisulfite. FTIR and SEM–EDX analysis of the synthesized films and membranes was performed to confirm the grafting and the sulfonation. A pronounced front mechanism for grafting of GMA into ETFE was found. Regarding ex situ fuel cell relevant properties, conductivities of up to 0.25 S cm^–1 were attained. For the first time, fuel cell testing of this type of membrane is reported. These grafted membranes performed comparable to a commercial benchmark membrane (Nafion® 212) and better than a styrene‐based grafted membrane with similar conductivity. Post‐test FTIR analysis showed that a fraction of the grafted chains was lost during the test under constant current conditions, yet the membrane still exhibited superior durability compared to a styrene‐based grafted membrane. Hydrolysis of the methacrylate groups was shown not to be the principle cause of the loss of sulfonic acid groups.     

Graft copolymerization of oleic acid onto low‐density polyethylene in the molten state

A graft copolymer of oleic acid (OA) onto low‐density polyethylene (LDPE) was prepared using dicumyl peroxide (DCP) as an initiator in the molten state. The grafting was carried out in a Haake rheometer. The effects of the reaction time and the amount of DCP and the monomer on the percentage of grafting were studied. The rheological behavior and the melt‐flow rate of the graft copolymer (LDPE‐g‐OA) were also investigated. FTIR spectroscopy and a mass spectrum were used to characterize the structure of LDPE‐g‐OA. The experimental results showed that when the OA amount was 10 wt % and the DCP amount was 0.4 wt % based on the LDPE the percentage of grafting of LDPE‐g‐OA, prepared by maintaining the temperature at 170°C and the roller speed at 80 rpm, was about 6 wt %. It was found that both LDPE and LDPE‐g‐OA were pseudoplastic fluids. OA was grafted onto LDPE in the form of a monomer and a dimer. The grafted LDPE is expected to act as a compatibilizer between starch and polyethylene. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3299–3304, 2003     

Adsorption of VO2+ by poly[(tetrafluoroethylene)‐co‐(perfluorovinyl ether)] copolymer grafted with acrylic acid using γ‐irradiation

Grafted films were prepared by the reaction of acrylic acid (AAc) onto poly[(tetrafluoroethylene)‐co‐(perfluorovinyl ether)] copolymer (PFA) using γ‐irradiation by the mutual technique. The grafted copolymer was complexed with the vanadyl group, VO²⁺, in aqueous solution. The grafted copolymer–metal complexes were examined by infrared and ultraviolet spectrometry, energy‐dispersive spectroscopy (EDS) and X‐ray diffraction (XRD). The amount of vanadium in the grafted films was estimated using EDS. The thermal stability of the films was investigated through thermogravimetric and differential scanning calorimetry measurements. The degree of crystallinity of the grafted and complexed films decreased by treatment with VO²⁺ ions and also by heating at 300 °C. When heated at a temperature above 300 °C, the grafted chains degraded till they disappeared and the original polymer was almost completely separated. XRD investigation revealed that the metal oxide may be formed as a separate phase with subsequent decrease in the crystallinity of the copolymer. Furthermore, scanning electron microscope (SEM) investigation of the grafted and modified films, both unheated and heated (300 °C), showed changes in the structure and morphology. The tendency of the graft copolymer to adsorb and/or bind to VO²⁺ from aqueous solution is of promising use in the field of waste treatment of rare metals in the environment. Copyright © 2004 Society of Chemical Industry