Piperidinium-Functionalized Poly(Vinylbenzyl Chloride) Cross-linked by Polybenzimidazole as an Anion Exchange Membrane with a Continuous Ionic Transport Pathway

Abstract

A bicomponent anion exchange membrane (AEM) in the form of poly(vinylbenzyl chloride) (PVBC) cross-linked by polybenzimidazole (PBI) and quaternized by N-methylpiperidine (NMPD) is provided. On the one hand, the cross-linking between the benzimidazole moiety of PBI and chloromethyl group of PVBC increases the compatibility of two components without macroscopic phase separation. On the other hand, the difference between hydrophilic NMPD-functionalized PVBC and hydrophobic PBI leads to microphase separation and results in the construction of continuous ion transport channels in the membrane. The AEM with a PBI/PVBC weight ratio of 1/1 (PBI1-PVBC1-NMPD/OH) presents a hydroxide conductivity >80 mS cm–1 at 80 °C. Moreover, the supporting effect of PBI as well as the cross-linking structure gives the membrane good mechanical properties and nearly temperature-independent water uptake (<50%) and swelling ratio (∼10%). After soaking in 1 M KOH at 60 °C for 336 h, ∼80% of hydroxide conductivity of PBI1-PVBC1-NMPD/OH is maintained. In addition, the feasibility of PBI1-PVBC1-NMPD/OH used in the AEM-based water electrolyzer is demonstrated.