Poly(arylene ether) electrolyte membranes bearing aliphatic-chain-linked sulfophenyl pendant groups

Two series of novel side-chain-acid poly(arylene ether)s bearing aliphatic-chain-linked sulfophenyl pendants are synthesized by direct polycondensation reactions derived from a new sulfonated difluoro-monomer, sodium 4-(3-(4-(2,6-difluorobenzoyl)phenoxy)propoxy)benzenesulfonate. The sulfonation content is readily controlled by adjusting the feed ratios of sulfonated and unsulfonated monomers. The obtained polymers exhibit considerably reduced dimensional swelling and good proton conductivities. It is found that the cyano-functionalized poly(arylene ether)s exhibit lower water uptake and dimensional swelling in comparison with the corresponding SPAE series. SPAEK-3 with an ion exchange capacity of 1.5 mequiv g−1 has proton conductivity of 0.12 S cm−1 and water swelling ratio of only 26% at 100 °C. Importantly, obvious hydrophobic/hydrophilic phase separation morphology is observed, which may be highly related with their good proton transport ability.