Synthesis and Properties of Symmetric Side-Chain Quaternized Poly(Arylene Ether Sulfone)s for Anion Exchange Membrane Fuel Cells

Poly(arylene ether sulfone)s containing symmetric side-chain benzyltrimethyl ammonium groups are synthesized via Suzuki reaction, copolycondensation, and functionalization. Two series of anion exchange membranes, 4C-y-Q and 8C-y-Q, containing four or eight pendent benzyl or cationic groups are synthesized to clarify the steric effect of the benzyl groups on the water channels. H-1 NMR and transmission electron microscopy are used to study the chemical structure and morphology, respectively. These two series of membranes are assessed in terms of ion exchange capacity (IEC), water uptake, swelling ratio, , hydroxide ion conductivity (sigma), mechanical properties, thermal stability, and alkaline stability. The 4C-y-Q membranes show better-defined microphase separation morphology and higher ion conductivity (206.2 mS cm(-1) at 80 degrees C) than most of the reported membranes. Ionic conduction efficiency (sigma/IEC) can be improved and made higher than that of Nafion with lower ion transport activation energy. The obtained membranes with superior properties reveal their prospective application in anion exchange membrane fuel cells.