Poly(arylene ether sulfone)s ionomers with pendant quaternary ammonium groups for alkaline anion exchange membranes: Preparation and stability issues

A series of quaternized poly(arylene ether sulfone)s containing up to two pendant quaternary ammonium groups per repeat unit was prepared by cesium carbonate mediated direct aromatic nucleophilic substitution polycondensation of 2,2′-dimethylaminemethylene-4,4′-biphenol (DABP), 4,4′-biphenol (BP) and 4,4′-difluorodiphenylsulfone (DFDPS), followed by reaction with iodomethane. The anion exchange membranes formed from these polymers showed conductivities above 10−2 S cm−1 at room temperature with a hydroxide conductivity of 6.5 × 10−2 S cm−1 for QNPS-OH-80. At the test of alkaline stability, these poly(arylene ether sulfone) ionomers were more stable than our previous reported partially fluorinated poly(arylene ether sulfone) ionomers under highly basic conditions.