Preparation and characterization of UV‐grafted ion‐exchange textiles in continuous electrodeionization

Ion‐exchange textiles (IETs) suitable for use in continuous electrodeionization (CEDI) stacks were prepared using the ultraviolet (UV)‐induced grafting of acrylic acid and sodium styrene sulfonate for cation‐exchange textiles, or 2‐hydroxyethyl methacrylate and vinylbenzyl trimethyl ammonium chloride for anion‐exchange textiles, onto nonwoven polypropylene fabric using benzophenone as photoinitiator. Although the ion‐exchange capacity (2.2 meq g^?1) of the prepared strong acid cation‐exchange textile was lower than that of IRN77 strong acid cation‐exchange resin (4.2 meq g^?1), the overall rate constant of IET was very high due to its low crosslinking and high specific surface area. There was no significant difference between the two different media in terms of the Co(II) removal rate. Furthermore, the current efficiency for IETs was higher than that of IRN77 cation‐exchange resin during a CEDI operation, with efficiencies of 60% and 20%, respectively. The IET also showed the faster exchange kinetics. Therefore, IETs prepared in this study proved to have desirable ion‐conducting characteristics within the CEDI systems. Also this study revealed that the primary removal mechanism in CEDI is the transport of ions through a medium and not the ionic capacity of a medium. Copyright © 2004 Society of Chemical Industry     

Lysine Adsorption on Cation Exchange Resin. IV. Temperature Effects on Equilibrium and Kinetics in Batch and Column Systems

Abstract

Ion exchange equilibria and kinetics are determined for lysine adsorption on the strong acid cation exchanger DIAION SK‐1B at temperatures of 25, 40, and 60°C. The ion exchange equilibrium is found to be independent of temperature. Conversely, the kinetics of ion exchange increases dramatically as the temperature is increased. Average ion exchange selectivity coefficients of 6.0 g/cm³ and 0.52 are obtained for the ion exchange of divalent and monovalent cationic lysine with hydrogen ion, respectively. Resin phase diffusivities are determined by fitting batch binary ion‐exchange data with a mass transfer model based on the Nernst‐Planck equations. As the temperature is increased from 25 to 60°C, the resin phase diffusivity increases from 0.04×10^?6 to 0.14×10^?6 cm²/s for divalent lysine and from 0.16×10^?6 to 0.55×10^?6 cm²/s for monovalent lysine. The combination of temperature‐independent ion exchange equilibria and faster mass transfer at higher temperatures results in higher dynamic binding capacity and more efficient desorption of lysine when ion exchange is operated at an elevated temperature. This behavior is confirmed by means of column adsorption/desorption experiments whose results are found to be in agreement with a model incorporating the equilibrium and mass transfer data obtained in this work.     

Durability and performance of polystyrene‐b‐poly(vinylbenzyl trimethylammonium) diblock copolymer and equivalent blend anion exchange membranes

Anion exchange membranes (AEM) are solid polymer electrolytes that facilitate ion transport in fuel cells. In this study, a polystyrene‐b‐poly(vinylbenzyl trimethylammonium) diblock copolymer was evaluated as potential AEM and compared with the equivalent homopolymer blend. The diblock had a 92% conversion of reactive sites with an IEC of 1.72 ± 0.05 mmol g^?1, while the blend had a 43% conversion for an IEC of 0.80 ± 0.03 mmol g^?1. At 50°C and 95% relative humidity, the chloride conductivity of the diblock was higher, 24–33 mS cm^?1, compared with the blend, 1–6 mS cm^?1. The diblock displayed phase separation on the length scale of 100 nm, while the blend displayed microphase separation (～10 μm). Mechanical characterization of films from 40 to 90 microns thick found that elasticity and elongation decreased with the addition of cations to the films. At humidified conditions, water acted as a plasticizer to increase film elasticity and elongation. While the polystyrene‐based diblock displayed sufficient ionic conductivity, the films' mechanical properties require improvement, i.e., greater elasticity and strength, before use in fuel cells. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41596.     

Polybenzimidazolium‐Based Solid Electrolytes

A series of methyl, benzyl, and mixed polybenzimidazolium halides was synthesised and characterised by NMR spectroscopy. Membranes were formed and ion exchanged with hydroxides. These membranes are of interest for use in potentially platinum‐free anionic exchange membrane fuel cells. Crosslinked membranes were obtained by the addition of α,α′‐dibromo‐p‐xylene to the casting solution. The ion conductivity of membranes was determined by impedance spectroscopy. A hydroxide conductivity of 29 mS · cm^?1 at 26 °C and 58 mS · cm^?1 at 60 °C was obtained. The thermal and hydrolytic stability was investigated and a pathway for hydrolytic degradation proposed. Hydroxide ions react at the 2 position, the intermediate carbinol opens to the amine–amide, and further degrades under chain scission to diamine and carboxylic acid.

     

Polystyrene‐based anion exchange membranes via click chemistry: improved properties and AEM performance

Polystyrene‐based anion exchange membranes (AEMs) have been fabricated using in situ click chemistry between azide and alkyne moieties introduced as side groups on functionalized polymers. The membrane properties such as water uptake, swelling ratio and conductivity were affected by the number of cations and the degree of crosslinking. The membranes containing a larger amount of trimethylammonium cationic groups (i.e. higher ion exchange capacity) showed high hydroxide conductivity when immersed in KOH solution, exhibiting a peak in conductivity (156 mS cm^?1) in 3 mol L^–1 KOH solution. A higher degree of crosslinking tended to decrease conductivity. These membranes demonstrated relatively good stability in 8 mol L^–1 KOH at 60 °C and maintained 33%–62% of initial conductivity after 49 days with most of the loss in conductivity occurring in early stages of the test. In an alkaline fuel cell, the areal specific resistance was constant indicating good stability of the membranes. The observed peak power density (157 mW cm^?2) was comparable to that of other AEM‐based fuel cells reported. © 2018 Society of Chemical Industry     

Preparation and properties of alkaline anion exchange membrane with semi‐interpenetrating polymer networks based on poly(vinylidene fluoride‐co‐hexafluoropropylene)

Alkaline anion exchange membrane with semi‐interpenetrating polymer network (s‐IPN) was constituted based upon quaternized poly(butyl acrylate‐co‐vinylbenzyl chloride) (QPBV) and poly(vinylidene fluoride‐co‐hexafluoropropylene) [P(VDF‐HFP)]. The QPBV was synthesized via the free radical copolymerization, followed by quaternization with N‐methylimidazole. The s‐IPN system was constituted by melting blend of QPBV and P(VDF‐HFP), and then crosslinking of P(VDF‐HFP). Ion exchange capacity, water uptake, mechanical performance, and thermal stability of these membranes were characterized. TEM showed that alkaline anion exchange membrane exhibited s‐IPN morphology with microphase separation. The fabricated s‐IPN membrane exhibited hydroxide ion conductivity up to 15 mS cm^?1 at 25 °C and a maximum DMFC power density of 46.55 mW cm^?2 at a load current density of 98 mA cm^?2 at 30 °C. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45775.     

Fluorenyl‐containing Quaternary Ammonium Poly(arylene ether sulfone)s for Anion Exchange Membrane Applications

A series of anion exchange membranes (AEM) based on block quaternary ammonium poly(arylene ether sulfone) (QA‐bPAES) were successfully synthesized from 9,9′‐bis(4‐hydroxyphenyl) fluorene, 4,4′‐(hexafluoroisopropylidene) diphenol and 4,4′‐difluorodiphenyl sulfone via block polymerization, chloromethylation, quaternization, alkalization and solution casting. Properties of the obtained QA‐bPAES membranes, including ion exchange capacity (IEC), water uptake, swelling ratios, methanol permeability and ion conductivity were investigated. The obtained QA‐bPAES membranes showed low water uptakes, high ion conductivities and good physical and chemical stability. For example, the membrane of QA‐bPAES(20/10)‐1.34 with IEC of 1.34 mmol g⁻¹ exhibited swelling ratios of 5.0% and 5.1% in in‐plane and through‐plane direction, respectively, and ion conductivity of 15.6 mS cm⁻¹ in water at 60 °C with low methanol permeability of 1.06 × 10⁻⁷ cm² s⁻¹ (25 °C). All the results indicated that this type of block membranes had good potentials for alkaline anion exchange membrane fuel cell applications.     

Treatment of wastewater containing Pb and Fe using ion‐exchange techniques

Treatment of wastewater containing lead and iron was examined using two different ion‐exchange resins namely Duolite ES 467 (containing amino‐phosphonic functional groups) and a chelating ion‐exchange resin (containing hydroxamic acid functional groups). Initially different sorption parameters such as contact time, pH, concentrations of sorbent, sorbate and chloride ion were studied. The sorption kinetics was observed to be fast and equilibrium could be reached within 30 min. Lead sorption efficiency increased with increase in pH whereas the opposite trend was observed with iron. The presence of chloride ions greatly reduced the Pb sorption efficiency in the case of Duolite ES 467. Column studies were carried out to recover Pb and Fe individually using Duolite ES 467 resin. The maximum uptake of Pb at pH 2 and 3 was observed to be 11.63 and 33.96 g dm^?3 of resin respectively. Similarly, for Fe at pH 2 and 3 the uptake was observed to be 10.07 and 6.96 g dm^?3 of resin respectively. In the presence of chloride ions, column studies were carried out using Duolite ES 467 for iron and chelating ion‐exchange resin containing hydroxamic acid functional groups for lead sorption. Hydroxamic acid resin's loading capacity remains constant for at least up to 20 cycles. Copyright © 2005 Society of Chemical Industry     

Investigation on structure and properties of anion exchange membranes based on tetramethylbiphenol moieties containing copoly(arylene ether)s

Quaternary ammonium functionalized poly(arylene ether)s (QPAEs) containing 2,2′,6,6′‐tetramethylbiphenol moieties were designed and successfully synthesized via nucleophilic substitution polycondensation, bromination, quaternization and alkalization. The structure, water uptake, ion exchange capacities (IECs), hydroxide ion conductivities, and mechanical properties, as well as thermal and chemical stabilities of obtained QPAEs membranes were investigated. The QPAE‐a membrane with IEC value of 0.98 meq g^?1 demonstrated the highest ion conductivity (47.4 mS cm^?1) at 80°C. The ion transport activation energy (E_a) of QPAEs membranes varied from 8.57 to 19.95 kJ mol^?1. After chemical stability test conditioned in 1M NaOH at 60°C for 7 days, the QPAEs membranes except QPAE‐c (IEC = 0.88 meq g^?1) still exhibited high hydroxide ion conductivities (over 15 mS cm^?1) and acceptable tensile strength (～10 MPa). These properties indicate that the ionomers membranes are potential candidates for anion exchange membranes in anion exchange membrane fuel cells. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41525.     

Hydroquinone Based Sulfonated Copolytriazoles with Enhanced Proton Conductivity

A series of new fluorinated sulfonated copolytriazoles (PTHQSH‐XX) with ion exchange capacity (IEC_w) values ranging from 1.66 to 2.82 meq g⁻¹ are prepared via cuprous ion catalyzed azide‐alkyne click polymerization reaction between 1,4‐bis(prop‐2‐ynyloxy)benzene, 4,4′‐diazido‐2,2′‐stilbene disulfonic acid disodium salt (SA), and 4,4‐bis[3′‐trifluoromethyl‐4′(4‐azidobenzoxy) benzyl] biphenyl (QAZ). The degree of sulfonation of the copolytriazoles is adjusted between 60% and 90% by varying the molar ratio of sulfonated monomer (SA) to the nonsulfonated monomer (QAZ). The structure of the copolytriazoles is characterized by Fourier transform infrared and NMR spectroscopy. The solution‐cast membranes of these copolymers exhibit high thermal, mechanical, oxidative and hydrolytic stability, and high proton conductivity (19–142 mS cm⁻¹ at 80 °C and 22–157 mS cm⁻¹ at 90 °C). Transmission electron microscopy confirms the formation of good phase separated morphology with ionic clusters in the range of 15–145 nm.     

Cryostructuration of polymer systems. XXIV. Poly(vinyl alcohol) cryogels filled with particles of a strong anion exchanger: Properties of the composite materials and potential applications

A composite material produced from a poly(vinyl alcohol) cryogel with entrapped particles of the strong anion‐exchange resin Amberlite is presented. The properties of the composite material depended strongly on whether the resin was used in OH^? form or Cl^? form. The ion‐exchange filler in OH^? form caused both a significant reinforcement of the composite material and an increase in the gel fusion temperature. These effects were thought to be associated with the additional ionic bonding between the continuous and disperse phases. Beads 200–600 μm in size were prepared from the composite material and used in expanded‐bed ion‐exchange chromatography for the capture of the negatively charged solutes benzoate and lactate from the suspension of negatively charged cells. The plausibility of the approach has been demonstrated on model systems composed of yeast cells and benzoate and with a real fermentation broth produced after lactic acid fermentation. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 529–538, 2005     

Application of azodiisobutyronitrile and azobisisoheptonitrile in low‐density unsaturated polyester resin manufacturing

Low‐density unsaturated polyester resin (LDUPR) is an extended application of unsaturated polyester resin (UPR) material. In this study, azodiisobutyronitrile (AIBN) and azobisisoheptonitrile (ABVN) were presented as composite foaming agents and as initiators in LDUPR manufacturing. On the basis of the kinetics of AIBN and ABVN, their optimum half‐lives (t_1/2's) for LDUPR were both 1.0 h. In this study, the mass ratio of AIBN and ABVN was chosen at 7:3, and the preferred amount of the composite foaming agent was 2 wt % resin. They were treated at a molding temperature of 78.7 ± 1.0°C. The obtained LDUPR had an apparent density of 0.37 ± 0.01 g/cm³ and a specific compression strength of 35.58 ± 1.50 MPa·g^?1·cm^?3; it approached the highest specific compression strength value of rigid polyurethane foam (28–35 MPa g^?1 cm^?3). A dual‐initiation and dual‐foaming mechanism based on the dual‐exothermic decomposition properties of the composite foaming agent was proposed with the support of the differential scanning calorimetry and scanning electron microscopy results. In the first stage, ABVN decomposed, released bubble nuclei, and initiated UPR cross‐polymerization. The bubble nuclei spread in the resin glue and grew. In the second stage, the gas in resin glue was enriched by the AIBN decomposition. The gelation time of the resin glue was influenced by AIBN and delayed. With the curing of resin, more bubbles grew up, took shape, and were retained in the UPR matrix. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40238.     

Microporous gel electrolyte for quasi‐solid‐state dye‐sensitized solar cell

The extension of electrocatalytic reaction of I^?/I₃^? from counter electrode/gel electrolyte interface to gel electrolyte can significantly enhance the redox kinetics and therefore conversion efficiency of dye‐sensitized solar cells. Microporous gel electrolyte from polypyrrole integrated poly(hydroxyethyl methacrylate/cetytrimethylammonium bromide) [PPy‐integrated poly (HEMA/CTAB)] is successfully synthesized by in‐situ polymerization of pyrrole monomers in three‐dimensional framework of porous poly(HEMA/CTAB) matrix. An ionic conductivity of 12.72 mS cm^?1 and activation energy of 8.65 kJ mol^?1 are obtained from PPy‐integrated poly(HEMA/CTAB) gel electrolyte. Tafel polarization and electrochemical impedance spectroscopy are employed to characterize the electrocatalytic behaviors of the gel electrolytes. The resultant quasi‐solid‐state dye‐sensitized solar cell shows a light‐to‐electrical conversion efficiency of 6.68%. POLYM. ENG. SCI., 54:2531–2535, 2014. © 2013 Society of Plastics Engineers     

Controllable Cross‐Linking Anion Exchange Membranes with Excellent Mechanical and Thermal Properties

A new monomer called 2,2′‐(4,4′‐oxydiphenol‐4,4′‐diyl)bis(2‐methyl‐2,3,3a,4,7,7a‐hexahydro‐1H‐4,7‐methanoisoindol‐2‐ium) iodide (d₃) is synthesized possessing both cross‐linker and functional groups. The membranes are formed by copolymerizing d₃ with norbornene and (3aR,4S,7R,7aS)‐2‐methyl‐2‐(3‐(trimethylammonio)propyl)‐2,3,3a,4,7,7a‐hexahydro‐1H‐4,7‐methanoisoindol‐2‐ium iodide (a₃) at varying ratios. The water uptake is 41.35% at 60 °C, and ion exchange capacity is 2.35 mequiv g^?1 for a mole ratio of a₃, norbornene, and d₃ (1:6:3). The conductivity is 12, 37, and 40 mS cm^?1 when d₃ is decreased. Meanwhile, the conductivity increases quickly with increasing the temperature. Furthermore, the mechanical properties and thermal properties are improved, attributed to the increased cross‐linker. The membrane has a tensile strength of 41.3 MPa and the elongation at break of 38.0 %, and the 5 wt% loss temperature for membrane is ≈159 °C. The H₂/O₂ single fuel cells with this membrane show a maximum power density of 124 mW cm^?2 at 50 °C. The cross‐linked membranes demonstrate high‐dimensional stability in alkaline solution.     

Modification of sulfonated poly(ether ether ketone) membranes by impregnation with the ionic liquid 1‐butyl‐3‐methylimidazolium tetrafluoroborate for proton exchange membrane fuel cell applications

Sulfonated poly(ether ether ketone) (SPEEK) membranes were modified by impregnation with the ionic liquid (IL) 1‐butyl‐3‐methylimidazolium tetrafluoroborate (BMI.BF₄) by immersion into an IL aqueous solution for different periods of time. The modified membranes were investigated by thermogravimetric analyses (TGA), differential scanning calorimetry (DSC), ion exchange capacity (IEC), and conductivity. The SPEEK membrane immersed into the IL aqueous solution for 2 min showed greater dimensional and thermal stability than the pristine SPEEK membrane, and achieved higher decomposition temperatures. It also presented a higher conductivity value (1.0 mS cm^?1), indicating that BMI.BF₄ is a promoter of proton conductivity. The membrane electrode assembly (MEA) produced reached maximum values of power density of 0.13 W cm^?2 and current density of 0.54 A cm^?2 during fuel cell operation. The results indicate that the SPEEK membrane modified by immersion for 2 min is promising for use in a proton exchange membrane fuel cell. Its performance yielded values very close to those obtained with Nafion, which reaches maximum values of power density of 0.19 W cm^?2 and current density of 0.77 A cm^?2. POLYM. ENG. SCI. 56:1037–1044, 2016. © 2016 Society of Plastics Engineers     

Poly(arylene ether)s carrying pendant (3‐sulfonated) phenylsulfonyl groups

A series of poly(arylene ether)s with biphenyl units and pendant sulfonated phenylsulfonyl groups was prepared via nucleophilic aromatic substitution reactions of varying ratios of 3,5‐difluoro‐3′‐sulfonated diphenylsulfone and 4,4′‐difluorodiphenylsulfone with 4,4′‐biphenol. As such, the sulfonic acid moieties reside in the meta position of a pendant, electron‐poor phenylsulfonyl group. Mechanically robust proton‐exchange membranes with ion‐exchange capacities (IEC) ranging from 0.91 to 2.05 meq g^?1 were cast from dimethylacetamide. The thermal stability of the membranes was evaluated via thermogravimetric analysis and the 5% weight losses were found to be in excess of 330 °C in air. The glass transition temperatures were determined, via differential scanning calorimetry, to range from a low of 148 to a high of 209 °C at IEC values of 0.91 and 1.79 meq g^?1, respectively. The copolymer membranes reached proton conductivities as high as 142 mS cm^?1 under 100% relative humidity, with relatively low water uptake values (8–32 wt%). Copyright © 2012 Society of Chemical Industry     

Cr(VI)‐containing wastewater treatment by means of ion exchange on weak‐ and strong‐base anion exchangers

The aim of this research work was a thermodynamic and kinetic study of the retention of Cr(VI) ions from a K₂CrO₄ solution on macroporous weak‐ and strong‐base anion exchangers, Lewatit M 64 A and Lewatit MP 500 A, respectively. Also, the correlations among the ion‐exchange rate, the retention capacity of Cr(VI), and some process parameters were established. The parameters studied mainly were the concentration of Cr(VI) ions and the type of the counterions coupled with active groups from the anion exchangers. The results led to the conclusion that, for the Lewatit M 64 A resin, there is the following order of the Cr(VI) retention capacity: RCl > R₂SO₄ > ROH, while for the strong‐base anion exchanger, the retention capacity for the Cr(VI) ions is different: ROH > RCl > R₂SO₄. In the Cl^? form, both anion exchangers have the same retention‐capacity values. On the other side, the weak‐base anion exchanger in SO and OH^? forms presents the lowest retention‐capacity values. The process kinetics also presents some differences: for the Lewatit M 64 A resin, the ion‐exchange rate has lower values, especially in the OH^? form. This result is attributed to the increase of the OH^? ion concentration in the solution and its presence hinders the dissociation of the active groups of a weak‐base anion exchanger. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2093–2098, 2002     

Main‐chain poly(1,2,3‐triazolium hydroxide)s obtained through AA+BB click polyaddition as anion exchange membranes

A series of aromatic poly(1,2,3‐triazolium iodide)s were synthesized by step growth polymerization of dipropargyl bisphenol A with aliphatic and aromatic diazides followed by quantitative or partial N‐alkylation of the main‐chain 1,2,3‐triazole groups using iodomethane. After characterization by ¹H NMR spectroscopy, SEC and DSC the corresponding self‐standing membranes were obtained by hot pressing. Poly(1,2,3‐triazolium iodide) membranes were converted to the corresponding hydroxide‐containing membranes by anion exchange. Structure–property correlations are discussed based on the evolution of water uptake and ionic conductivity with respect to the ionic exchange capacities of the different materials having distinct chemical structure, quaternization degree and counter‐anion structure. Poly(1,2,3‐triazolium hydroxide) anion exchange membranes exhibit water uptakes below 150% and ionic conductivity in the hydrated state up to 4 mS cm^?1 for ionic exchange capacities up to 3.2 meq g^?1. © 2019 Society of Chemical Industry     

Water Free Operated Phosphoric Acid Doped Radiation‐Grafted Proton Conducting Membranes for High Temperature Polymer Electrolyte Membrane Fuel Cells

The present study uses the radiation‐induced grafting method and applies it onto poly(ethylene‐alt‐tetrafluoroethylene) (ETFE) for the synthesis of proton‐exchange membranes by using monomers 4‐vinyl pyridine (4VP), 2‐vinyl pyridine (2VP), N‐vinyl‐2‐pyrrolidone (NVP) followed by phosphoric acid doping. Phosphoric acid that provides Grotthuss mechanism in proton mobilization is used to transform the graft copolymers to a high temperature membrane state. Resultant proton‐exchange membranes are verified with their proton conductivity, water uptake, mechanical and thermal properties, and phosphorous distribution as ex situ characterization. Our most important finding as a novelty in literature is that ETFE‐g‐P4VP phosphoric acid doped proton‐exchange membranes exhibit proton conductivities as 66 mS cm^–1 at 130 °C, 53 mS cm^–1 at 120 °C, 45 mS cm^–1 at 80 °C at RH 100% and 55 mS cm^–1 at 130 °C, 40 mS cm^–1 at 120 °C, 35 mS cm^–1 at 80 °C at dry conditions. Moreover, ETFE‐g‐P4VP membranes still conserves the mechanical properties, i.e., tensile strength up to 48 MPa. ETFE‐g‐P4VP membranes were tested in PEMFC at 80, 100, and 120 °C and RH <2% and exhibit promising performance as an alternative to commercial Nafion® membranes. The single cell testing performance of ETFE‐g‐P4VP membranes is presented for the first time in literature in our study.     

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