Poly(arylene ether sulfone)s ionomers containing quaternized triptycene groups for alkaline fuel cell

Abstract

A series of poly(arylene ether sulfone)s containing quaternized triptycene groups are synthesized through a chloromethylation reaction following a quaternization process. The resulting ionomers are soluble in polar aprotic solvents; thus, flexible, tough membranes could be prepared by solution casting. Novel anion exchange membranes based on these ionomers are obtained by anion exchange with hydroxide ions. All anion exchange membranes show conductivities above 10−2 S cm−1 at room temperature. The highest hydroxide conductivity is 7.2 × 10−2 S cm−1, which is achieved by the anion exchange membrane with ion exchange capacity (IEC) = 2.61 mmol g−1. Meanwhile, these anion exchange membranes have low water uptake and good dimensional stability even at high IEC values. For example, the membrane water uptake (IEC = 1.97 mmol g−1) is only 21% at room temperature, and the swelling ratio is 11%. The anion exchange membranes are stable in alkaline conditions. All the membranes have no significant change in 4 M NaOH solution at 25 °C after 30 days. All results suggest that these anion exchange membranes have potential application in alkaline fuel cells.