Preparation and characterization of side-chain poly(aryl ether ketone) anion exchange membranes by superacid-catalyzed reaction

The poly(aryl ether ketone) with spatial cardo structure is prepared from 4,4′-bis(phenoxy)benzophenone and 1-(4-bromobutyl)indoline-2,3-dione through a facile polyhydroxyalkylation reaction catalyzed by superacid. The number average molecular weight of the resultant polymer is achieved as high as 105.6 kg mmol−1. Three anion exchange membranes were prepared by reacting the polymer with trimethylamine, N-methyl-piperidine, and N,N,N′,N′,N″-pentaethylguanidine, respectively. Among the prepared membranes, N-methyl-piperidine based anion exchange membrane exhibited the highest OH− conductivity of 99.8 mS cm−1 at corresponding IEC of 1.54 meq g−1. In addition, the prepared membranes also exhibit excellent mechanical properties, in which the tensile strength and elongation at break can reach up to 50 MPa and 35%, respectively. Moreover, the anion exchange membranes exhibited good alkaline stability. When they were treated with 1 M KOH at 60 °C for 600 h, their conductivity decreased by less than 5%.