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