Preparation and properties of bisphenol A‐based sulfonated poly(arylene ether sulfone) proton exchange membranes for direct methanol fuel cell

Novel bisphenol A‐based sulfonated poly(arylene ether sulfone) (bi A‐SPAES) copolymers were successfully synthesized via direct copolymerization of disodium 3,3′‐disulfonate‐4,4′‐dichlorodiphenylsulfone, 4,4′‐dichlorodiphenylsulfone, and bisphenol A. The copolymer structure was confirmed by Fourier transform infrared spectra and ¹H NMR analysis. The series of sulfonated copolymers based membranes were prepared and evaluated for proton exchange membranes (PEM). The membranes showed good thermal stability and mechanical property. Transmission electron microscopy was used to obtain the microstructures of the synthesized polymers. The membranes exhibit increased water uptake from 8% to 66%, ion exchange capacities from 0.41 to 2.18 meq/g and proton conductivities (25°C) from 0.012 to 0.102 S/cm with the degree of sulfonation increasing. The proton conductivities of bi A‐SPAES‐6 membrane (0.10–0.15 S/cm) with high‐sulfonated degree are higher than that of Nafion 117 membrane (0.095–0.117 S/cm) at all temperatures (20–100°C). Especially, the methanol diffusion coefficients of membranes (1.7 × 10^?8 cm²/s–8.5 × 10^?7 cm²/s) are much lower than that of Nafion 117 membrane (2.1 × 10^?6 cm²/s). The new synthesized copolymer was therefore proposed as a candidate of material for PEM in direct methanol fuel cell. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Sulfonated poly(styrene)s‐PBIOO® blend membranes: Thermo‐oxidative stability and conductivity

Low‐cost polymers poly(styrene) and poly(α‐methylstyrene) have been sulfonated followed by blending with PBIOO® (30 wt % sulfonated ionomer, 70 wt % PBIOO). At this polymer ratio the sulfonated ionomer served as the macromolecular acidic cross‐linker which led to enhancement of the PBIOO stability. Both membrane types were treated with Fenton's Reagent to investigate their resistance to oxidation and radical attack. Indeed, the blend membranes showed enhanced stability in oxidative conditions compared to the pure PBIOO membranes. Furthermore, the sulfonated poly(α‐methylstyrene)‐PBIOO blend membrane showed less weight loss during and after Fenton's Test than the corresponding poly(styrene sulfonic acid)‐PBIOO membrane. Assuming all the characteristics of the blend membrane before and after the Fenton's Test, we concluded for a partial degradation of both sulfonated poly(styrene)s, whereas they remain in the blend membrane matrix due to the acid‐base crosslinking. Thus, since the sulfonated poly((α‐methyl)styrene)‐PBIOO blend membranes conserved their integrity even after Fenton's Test they can be regarded as potential low‐cost high‐T fuel cell membranes. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39889.     

Imidazolium ionic liquid incorporation on sulfonated poly(styrene‐isobutylene‐styrene) proton exchange membranes

Ionic liquids (ILs) with different anions and cations were incorporated in sulfonated poly(styrene‐isobutylene‐styrene) (SIBS) to modify its chemical, morphological, and transport properties for direct methanol fuel cell (DMFC) applications. Different loadings of IL and different solvents were studied to have a better understanding of the incorporation process and the ability of the solvent to affect the interaction of the IL with the sulfonated polymer. Morphological characterization with SAXS and AFM suggested changes caused by the incorporation of the IL and by the solvent used. FT‐IR spectra showed small variations in energy related to interactions of the IL with the sulfonic groups which caused thermogravimetric stabilization of the ionic domains. Other results suggest that water has a very significant effect on the morphology, interaction with the IL, and transport properties of the membranes. Optimal concentration of IL (～10 mol %) provides enough water to produce efficient proton conductivity (0.15 S/cm) and minimal methanol permeability (0.8 × 10^?6 cm²/s). © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44900.     

Novel Proton Conducting Membranes from the Combination of Sulfonated Polymers of Polyetheretherketones and Polyphosphazenes Doped with Sulfonated Single‐Walled Carbon Nanotubes

Intent on developing efficient proton exchange membranes used for direct methanol fuel cells as well as hydrogen fuel cells, a series of membranes based on sulfonated polyetheretherketone and sulfonated polyphosphazene‐graft copolymers is prepared by cross‐linking reaction because the former material has good enough mechanical property, while the latter is excellent in the proton transfer. The cross‐linked membranes combine the advantages of the two kinds of polymers. Among them, the membrane poly[(4‐trifluoromethylphenoxy)(4‐methylphenoxy)phosphazene]‐g‐poly {(styrene)₁₁‐r‐[4‐(4‐sulfobutyloxy)styrene]₃₃‐sulfonated poly(ether ether ketone)75 (CF₃‐PS₁₁‐PSBOS₃₃‐SPEEK75) shows a proton conductivity at 0.143 S cm⁻¹ under fully hydrated conditions at 80 °C and performs tensile strength about five times as much as did the sulfonated polyphosphazene membrane CF₃‐PS₁₁‐PSBOS₃₃. Further doping of sulfonated single‐walled carbon nanotubes (S‐SWCNTs) into the cross‐linked membranes on the screening of additives gives composite membrane CF₃‐PS₁₁‐PSBOS₃₃‐SPEEK75‐SWCNT possessing proton conductivity of 0.196 S cm⁻¹, even higher than that of Nafion 117 and a tensile strength comparable to that of Nafion 117. However, this significance of the composite membrane in the proton conduction is not observed in the test with a H₂/air fuel cell when it shows a maximal power density of 280 mW cm⁻² at 80 °C, whereas 294 mW cm⁻² is observed for CF₃‐PS₁₁‐PSBOS₃₃‐SPEEK75.

     

Pendant crosslinked poly(aryl ether sulfone) copolymers sulfonated on backbone for proton exchange membranes

A series of sulfonated poly(aryl ether sulfone) copolymers containing phenyl pendant groups with sulfonic acid groups on the backbone were synthesized through condensation polymerization. The degree of sulfonation (DS) of the copolymers was controlled by changing the feed ratios of sulfonated to unsulfonated monomers. Post‐crosslink reactions are carried out with 4,4′‐thiodibenzoic acid (TDA) as a crosslinker and the carboxylic acid groups in TDA can undergo Friedel–Craft acylation with the phenyls pendent rings in sulfonated poly(arylene ether sulfone)s copolymers to prepare polymer electrolyte membranes for fuel cell applications. The chemical structures of crosslinked and uncrosslinked sulfonated poly(arylene ether sulfone)s copolymers (SPSFs and CSPSFs) were characterized by FTIR, ¹H NMR spectra. The thermal and mechanical properties of the membranes were characterized by thermogravimetric analysis and stress–strain test. The dependence of water uptake, methanol permeability, proton conductivity, and selectivity on DS was studied. Transmission electron microscopic observations revealed that SPSFs and CSPSFs membranes form well‐defined microphase separated structures. POLYM. ENG. SCI., 54:2013–2022, 2014. © 2013 Society of Plastics Engineers     

Preparation and application of sulfonated poly(1‐octene‐co‐styrene)

In this article, 1‐octene and styrene was copolymerized by the supported catalyst (TiCl₄/ID/MgCl₂). Subsequently, by sulfonation reaction, sulfonated poly(1‐octene‐co‐styrene)s which were amphiphilic copolymers were prepared. The copolymerization behavior between 1‐octene and styrene is moderate ideal behavior. Copolymers prepared by this catalyst contain appreciable amounts of both 1‐octene and styrene. Increase in the feed ratio of styrene/1‐octene leads to increase in styrene content in copolymer and decrease in molecular weight. As the polymerization temperature increases, the styrene content in the copolymers increases, however, the molecular weight decreases. Hydrogen is an efficient regulator to lower the molecular weights of poly(1‐octene‐co‐styrene)s. The sulfonation degree of the sulfonated poly(1‐octene‐co‐styrene)s increased as the styrene content in copolymer increased or the molecular weight decreased. Thirty‐six hour is long enough for sulfonation reaction. The sulfonated poly(1‐octene‐co‐styrene)s can be used as effective and durable modifying agent to improve the wettability of polyethylene film and have potential application in emulsified fuels and for the stabilization of dispersions. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis of microphase‐separated poly(styrene‐co‐sodium styrene sulfonate) membranes using amphiphilic urethane acrylate nonionomers as an reactive compatibilizer

Microphase‐separated poly(styrene‐co‐sodium styrene sulfonate) random copolymer (PSSU) membranes were fabricated through a new copolymerization process. Two immiscible monomers, styrene and sodium styrene sulfonate were dissolved in a single solvent and formed homogeneous solutions, which were directly converted to wall‐to‐wall membranes via radical copolymerization process with microphase separation. Since urethane acrylate nonionomer (UAN) chain has amphiphilicity as well as reactivity with vinyl monomers, UAN chain could act not only as compatibilizer for polystyrene and poly(sodium styrene sulfonate), but also as macrocrosslinker, which makes it possible for the formation of crosslinked copolymer of two immiscible polymers without macrophase separation. TEM image of the PSSU membranes showed that nanosized hydrophilic domains formed by hydrophilic/hydrophobic microphase separation were dispersed at hydrophobic matrix phase. PSSU membranes fabricated using UAN chain having longer chain length of polyethylene oxide showed bigger size of hydrophilic domains, which was also confirmed by TEM images. Fabricated PSSU membranes showed proton conductivity higher than 10^?2 S/cm and methanol permeability lower than 10^?7 cm²/s of Nafion® 117 membranes. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Synthesis and phase separation of poly(N‐isopropyl acrylamide‐co‐methoxy polyethyleneglycol monomethacrylate)

The poly(N‐isopropyl acrylamide‐co‐methoxy polyethyleneglycol monomethacrylate, NIPAM‐co‐MPEG) with different length of ethylene oxide (EO) were synthesized from their monomers, NIPAM and MPEGs. The numbers of repeating units of EO were 6, 10, 24, and 46. The chemical structure and mole ratio of the monomers was determined by Fourier transform infrared (FTIR), ¹H‐NMR, and ¹³C‐NMR spectroscopy. The d‐spacing increased with the number of EO and the values of the copolymers were in the range of 0.437–0.452 nm. The lower critical solution temperature of the poly(NIPAM‐co‐MPEG) shifted to higher temperature as the number of EO and the amount of MPEG increased. The change of chemical shift for methoxy proton in MPEG exhibited a larger than those of the other protons of the poly(NIPAM‐co10?2MPEG). Activation energy (E_a) for methoxy proton in MPEG showed a larger value than that of the methyl proton in NIPAM. These NMR results indicate the fact that more significant conformational transformations occur in the methoxy group through the phase separation than in the methyl group in NIPAM. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1833–1841, 2006     

Highly methanol resistant and selective ternary blend membrane composed of sulfonated PVdF‐co‐HFP,sulfonated polyaniline and nafion

Partially sulfonated poly(vinylidene fluoride‐co‐hexafluoro propylene)/partially sulfonated polyaniline (SPVdF‐co‐HFP/SPAni) binary blend membranes have shown promising results in terms of low methanol permeability and high membrane selectivity compared to Nafion‐117 membrane. However, the proton conductivity and IEC of this binary blend membrane was much lower than Nafion‐117. It was found that incorporation of minimal quantity of Nafion within SPVdF‐co‐HFP/SPAni blend membrane at a constituent weight % ratio of SPVdF‐co‐HFP:SPAni:Nafion = 50:40:10 induced significant improvements in ion‐exchange capacity (IEC), proton conductivity and tensile strength over that of the binary blend membrane. In addition, the SPVdF‐co‐HFP/SPAni/Nafion ternary blend membrane exhibited much lower methanol permeability, higher membrane and relative selectivities and comparable IEC to Nafion‐117. In effect, presence of minimal quantity of Nafion induced significant positive attributes to the ternary blend membrane; and assisted in reaching a balance between material cost and properties. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43294.     

Poly(styrene‐co‐N‐butylmaleimide) macroinitiators by controlled autopolymerization and related block copolymers

Autopolymerization of styrene‐N‐butylmaleimide mixtures at 125 or 140°C in the presence of a stable nitroxyl radical [2,2,6,6‐tetramethylpiperidin‐1‐yloxyl (TEMPO)] was found to proceed in a pseudoliving manner. Unimolecular initiators, which were originated by trapping self‐generated radical species with TEMPO, took part in the process. Under the studied experimental conditions, the TEMPO‐controlled autopolymerization with a varying comonomer ratio provided virtually alternating copolymers of narrow molecular weight distributions. The molecular weights of the copolymers increased with conversions. The obtained styrene‐N‐butylmaleimide copolymers containing TEMPO end groups were used to initiate the polymerization of styrene. The polymerization yielded poly(styrene‐co‐N‐butylmaleimide)‐polystyrene block copolymers with various polystyrene chain lengths and narrow molecular weight distributions. The compositions, molecular weights, and molecular weight distributions of the synthesized block copolymers and the initial poly(styrene‐co‐N‐butylmaleimide) precursors were evaluated using nitrogen analysis, gel permeation chromatography, and ¹H‐ and ¹³C‐NMR spectroscopy. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2378–2385, 1999     

Proton exchange membrane based on crosslinked sulfonated polyphosphazene containing pendent perfluorosulfonic acid groups with sulfonated poly(ether ether ketone)

A series of crosslinked membranes based on new sulfonated polyphosphazene bearing pendent perfluorosulfonic acid groups (PMFP‐g‐PS) and sulfonated poly (ether ether ketone) were prepared and evaluated as proton exchange membranes for direct methanol fuel cells (DMFCs). The structure of PMFP‐g‐PS was characterized by Fourier transform infrared spectroscopy, ¹H and ¹⁹F NMR spectra. In comparison with the pristine PMFP‐g‐PS membrane, the crosslinked membranes showed improved water uptakes and proton conductivities. The methanol permeability values of the membranes were in the range of 1.32 × 10^?7 to 3.85 × 10^?7 cm²/s, which were lower than Nafion 117 (12.1 × 10^?7 cm²/s). The selectivity of all the membranes was much higher compared with Nafion 117. Furthermore, transmission electron microscopy observation revealed that clear phase‐separated structures were well dispersed and connected to each other in the membranes. These membranes displayed high water uptakes and low swelling ratios, high proton conductivities, low methanol permeability values, good thermal, and oxidative stabilities. The results indicate that these membranes are potential candidate proton exchange membrane materials for DMFCs. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43492.     

Novel membranes based on poly(5‐(methacrylamido)tetrazole) and sulfonated polysulfone for proton exchange membrane fuel cells

Proton‐exchange membrane fuel cells (PEMFC)s are increasingly regarded as promising environmentally benign power sources. Heterocyclic molecules are commonly used in the proton conducting membranes as dopant or polymer side group due to their high proton transfer ability. In this study, 5‐(methacrylamido)tetrazole monomer, prepared by the reaction of methacryloyl chloride with 5‐aminotetrazole, was polymerized via conventional free radical mechanism to achieve poly(5‐(methacrylamido)tetrazole) homopolymer. Novel composite membranes, SPSU‐PMTetX, were successfully produced by incorporating sulfonated polysulfone (SPSU) into poly(5‐(methacrylamido)tetrazole) (PMTet). The sulfonation of polysulfone was performed with trimethylsilyl chlorosulfonate and high degree of sulfonation (140%) was obtained. The homopolymers and composite membranes have been characterized by NMR, FTIR, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). ¹H‐NMR and FTIR confirmed the sulfonation of PSU and the ionic interaction between sulfonic acid and poly(5‐(methacrylamido)tetrazole) units. TGA showed that the polymer electrolyte membranes are thermally stable up to ～190°C. Scanning electron microscopy analysis indicated the homogeneity of the membranes. This result was also supported by the appearance of a single T_g in the DSC curves of the blends. Water uptake and proton conductivity measurements were, as well, carried out. Methanol permeability measurements showed that the composite membranes have similar methanol permeability values with Nafion 112. The maximum proton conductivity of anhydrous SPSU‐PMTet0.5 at 150°C was determined as 2.2 × 10^?6 S cm^?1 while in humidified conditions at 20°C a value of 6 × 10^?3 S cm^?1 was found for SPSU‐PMTet2. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40107.     

Sulfonated graphene oxide‐doped proton conductive membranes based on polymer blends of highly sulfonated poly(ether ether ketone) and sulfonated polybenzimidazole

Simultaneously improving the proton conductivity and mechanical properties of a polymer electrolyte membrane is a considerable challenge in commercializing proton exchange membrane fuel cells. In response, we prepared a new series of miscible polymer blends and thus the corresponding crosslinked membranes based on highly sulfonated poly(ether ether ketone) and sulfonated polybenzimidazole. The blended membranes showed more compact structures, due to the acid‐base interactions between the two constituents, and improved mechanical and morphological properties. Further efforts by doping sulfonated graphene oxide (s‐GO) forming composite membranes led to not only significantly elevated proton conductivity and electrochemical performance, but also better mechanical properties. Notably, the composite membrane with the filler content of 15 wt % exhibited a proton conductivity of 0.217 S cm^?1 at 80 °C, and its maximum power density tested by the H₂/air single PEMFC cell at room temperature reached 171 mW cm^?2, almost two and half folds compared with that of the native membrane. As a result, these polymeric membranes provided new options as proton exchange membranes for fuel‐cell applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46547.     

Synthesis and properties of sulfonated poly(arylene ether nitrile) copolymers containing carboxyl groups for proton‐exchange membrane materials

A series of sulfonated poly(arylene ether nitrile) copolymers containing carboxyl groups were synthesized via a nucleophilic aromatic substitution reaction from phenolphthalein, hydroquinone sulfonic acid potassium salt, and 2,6‐difluorobenzonitrile in N‐methyl pyrrolidone (NMP) with K₂CO₃ as a catalyst. The synthesized copolymers had good solubility in common polar organic solvents and could be easily processed into membranes from solutions of dimethyl sulfoxide, NMP, N,N′‐dimethyl acetylamide, and dimethylformamide. Typical membranes in acid form were gained, and the chemical structures of these membranes were characterized by Fourier transform infrared analysis. The thermal properties, fluorescence properties, water uptake, ion‐exchange capacity, and proton conductivities of these copolymers were also investigated. The results indicate that they had high glass‐transition temperatures in the range 151–187°C and good thermal stability, with the 10 wt% loss temperatures ranging from 330 to 351°C under nitrogen. The copolymers showed characteristic unimodal ultraviolet–visible (UV–vis) absorption and fluorescence emission, and the UV–vis absorption, fluorescence excitation, and emission peaks of the copolymers were obvious. Moreover, the copolymer membranes showed good water uptake and proton conductivities at room temperature and 55% relative humidity because of the introduction of both sulfonic acid groups and carboxyl groups into the copolymers, whose contents were in ranges 18.45–67.86 and 3.4 × 10^?4 to 3.0 × 10^?3 s/cm, respectively. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40213.     

Polymer electrolyte membranes prepared by EB‐crosslinking of sulfonated poly(ether ether ketone) with 1,4‐butanediol

Crosslinked sulfonated poly(ether ether ketone) (SPEEK) membranes were prepared through the electron beam (EB)‐irradiation crosslinking of SPEEK/1,4‐butanediol under various irradiation conditions and used as a proton exchange membrane (PEM) for fuel cell applications. The crosslinked membranes were characterized by gel fraction, a universal testing machine (UTM), dynamic mechanical analysis (DMA), and small‐angle X‐ray scattering (SAXS). The gel fraction of the crosslinked membranes was used to estimate the degree of crosslinking, and the gel fraction was found to be increased with an increase of the crosslinker content and EB‐absorbed dose. The UTM results indicate that a brittle EB‐crosslinked membrane becomes more flexible with an increase in the crosslinker content. The DMA results show that the EB‐crosslinked membranes have well‐developed ionic aggregation regions and the cluster T_g of membranes decrease with an increase in the 1,4‐butanediol crosslinker content. The SAXS results show that the Bragg and persistence distance of crosslinked membranes increase with an increase in the crosslinker content. The proton conductivities of the EB‐crosslinked membranes were more than 9 × 10^?2 S/cm. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41760.     

Synthesis and characterization of sulfonated fluorinated block copolymer membranes with different esterified initiators for DMFC applications

This investigation studied the synthesis of ionic membranes composed of a sulfonated poly(styrene‐isobutylene‐styrene) with novel fluoroblock copolymers. These fluoroblock copolymers were synthesized using three different initiators by Atom Transfer Radical Polymerization (ATRP); two fluoroinitiators were obtained from the esterification of 2‐(perfluoroalkyl) ethanol or octafluoro 4‐4′‐biphenol. The third initiator evaluated was 1‐bromoethyl benzene. The resulting block copolymers were characterized using several techniques: Gel Permeation Chromatography, Nuclear Magnetic Resonance, Fourier Transform Infrared Spectroscopy, Ultraviolet Spectroscopy, Thermogravimetric Analysis, and Differential Scanning Calorimetry. Transport properties (e.g., proton conductivity and methanol permeability) were measured to evaluate their performance for direct methanol fuel cell (DMFC). The choice of ATRP initiator was found to have a profound impact on the thermal stability of the different homopolymers and block copolymers studied. In addition, the chemical nature and symmetry of the initiators can lead to different chemical and electronic transitions, which influence the performance of these ionic membranes in applications such as proton exchange membranes for DMFC applications. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42046.     

Synthesis of water‐soluble and conducting polyaniline by growing of poly (N‐isopropylacrylamide) brushes via atom transfer radical polymerization method

Polyaniline‐graft‐Poly(N‐isopropylacrylamide) copolymers were synthesized by atom‐transfer radical polymerization (ATRP) of N‐isopropylacrylamide using polyaniline macro‐initiators. Polyaniline‐chloroacetylchloride and polyaniline‐chloropropionylchloride macroinitiators were obtained by the reaction of amine nitrogens of polyaniline with chloroacetyl chloride and 2‐choloropropionyl choloride, respectively. Both macroinitiators and graft copolymers were characterized by FT‐IR and ¹H‐NMR spectroscopy. The cyclic voltammetry (CV) and UV‐Vis spectroscopy studies showed that these copolymers are electroactive. The solubility test revealed that the polyaniline‐graft‐poly (N‐isopropylacrylamide) copolymers are water soluble or water/methanol soluble. The Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM) images showed the growing of poly (N‐isopropylacrylamide) chains on polyaniline backbone. Investigation of thermal behavior of graft copolymers by thermal gravimetry analysis (TGA) confirmed the results obtained from AFM and SEM images. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Highly selective sulfonated poly(vinylidene fluoride‐co‐hexafluoropropylene)/poly(ether sulfone) blend proton exchange membranes for direct methanol fuel cells

Proton exchange membranes (PEMs) based on blends of poly(ether sulfone) (PES) and sulfonated poly(vinylidene fluoride‐co‐hexafluoropropylene) (sPVdF‐co‐HFP) were prepared successfully. Fabricated blend membranes showed favorable PEM characteristics such as reduced methanol permeability, high selectivity, and improved mechanical integrity. Additionally, these membranes afford comparable proton conductivity, good oxidative stability, moderate ion exchange capacity, and reasonable water uptake. To appraise PEM performance, blend membranes were characterized using techniques such as Fourier transform infrared spectroscopy, AC impedance spectroscopy; atomic force microscopy, and thermogravimetry. Addition of hydrophobic PES confines the swelling of the PEM and increases the ultimate tensile strength of the membrane. Proton conductivities of the blend membranes are about 10^?3 S cm^?1. Methanol permeability of 1.22 × 10^?7cm² s^?1 exhibited by the sPVdF‐co‐HFP/PES10 blend membrane is much lower than that of Nafion‐117. AFM studies divulged that the sPVdF‐co‐HFP/PES blend membranes have nodule like structure, which confirms the presence of hydrophilic domain. The observed results demonstrated that the sPVdF‐co‐HFP/PES blend membranes have promise for possible usage as a PEM in direct methanol fuel cells. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43907.     

pH and thermo‐responsive poly(N‐isopropylacrylamide) copolymer grafted to poly(ethylene glycol)

pH and thermo‐responsive graft copolymers are reported where thermo‐responsive poly(N‐isopropylacrylamide) [poly(NIPAAm), poly A ], poly(N‐isopropylacrylamide‐co‐2‐(diethylamino) ethyl methacrylate) [poly(NIPAAm‐co‐DEA), poly B ], and poly(N‐isopropylacrylamide‐co‐methacrylic acid) [poly(NIPAAm‐co‐MAA), poly C ] have been installed to benzaldehyde grafted polyethylene glycol (PEG) back bone following introducing a pH responsive benzoic‐imine bond. All the prepared graft copolymers for PEG‐g‐poly(NIPAAm) [ P‐N1 ], PEG‐g‐poly(NIPAAm‐co‐DEA) [ P‐N2 ], and PEG‐g‐poly(NIPAAm‐co‐MAA) [ P‐N3 ] were characterized by ¹H‐NMR to assure the successful synthesis of the expected polymers. Molecular weight of all synthesized polymers was evaluated following gel permeation chromatography. The lower critical solution temperature of graft copolymers varied significantly when grafted to benzaldehyde containing PEG and after further functionalization of copolymer based poly(NIPAAm). The contact angle experiment showed the changes in hydrophilic/hydrophobic behavior when the polymers were exposed to different pH and temperature. Particle size measurement investigation by dynamic light scattering was performed to rectify thermo and pH responsiveness of all prepared polymers. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Palladium and platinum sorption on a thiocarbamoyl‐derivative of chitosan

Novel proton exchange membranes are solvent‐cast from N,N‐dimethylacetamide (DMAc) solutions of the crosslinked poly(arylene ether ketone) copolymer with pendant carboxylic acid group (C‐SPAEK) via poly(ethylene glycol) (PEG) with different amounts. These membranes are formed as a result of physical and chemical crosslinking. In this study, ¹H‐NMR and FTIR have been used to confirm the chemical structures of the copolymers. Mechanical and thermal properties, swelling and proton conductivity are affected by the crosslinker (PEG) content in the copolymers. Compared to the noncrosslinked C‐SPAEK membrane, the crosslinked membranes become more flexible and greatly reduced water uptake and swelling ratio with only slight sacrifice in proton conductivities. And the crosslinked membranes keep higher proton conductivities without a sharply decrease at higher temperature. These results show that the crosslinked membranes have potential applications as proton exchange membranes for fuel cell. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010