Polydiallylammonium interpenetrating cationic network ion-solvating membranes for anion exchange membrane water electrolyzers

Abstract

A facile methodology of fabricating alkaline exchange membranes was developed by blending an alkaline stable, ammonium network forming precursor with an ion-solvating polymer, poly(ethylene-co-vinyl alcohol) matrix, followed by thermal curing under mild conditions. The alkaline stable, ammonium network forming precursor was synthesized through the Menshutkin reaction of a multifunctional alkyl halide and methyldiallylamine, yielding an ammonium polymer precursor that under radical initiated thermal cyclo-polymerization forms pyrrolidinium cationic networks. The fabricated membranes exhibited tunable IEC, conductivity, and physical properties through the control of the poly(ethylene-co-vinyl alcohol) ion-solvating polymer content. The alkaline stability of the membranes was examined under 70 °C and 1 M KOH conditions for over 300 h, which showed impeccable retention of ion exchange capacity (IEC) and conductivity. The membrane electrode assembly (MEA) of anion exchange membrane electrolyzers with the fabricated membranes showed excellent performance (1.57 A cm⁻² at 2.0 V) and a short-term durability test showed improved durability over a commercial anion exchange membrane.