Cross-linked multiblock copoly(arylene ether sulfone) ionomer/nano-ZrO2 composite anion exchange membranes for alkaline fuel cells

Abstract

A series of cross-linked multiblock copoly(arylene ether sulfone) ionomer/nano-ZrO₂ (CLQCPAES/nano-ZrO₂) composite anion exchange membranes were prepared via block copolymerization, bromomethylation, ultrasonication blending, self-crosslinking, quaternization and alkalization. The structure, and the surface and cross section morphology of the CLQCPAES/nano-ZrO₂ composite membranes were characterized by solubility tests, FT-IR, XRD and SEM analyses. The combination of the determined results revealed that the CLQCPAES/nano-ZrO₂ composite membranes are a complex cross-linking networks of hydrophobic domains/hydrophilic domains/nano-ZrO₂ with a clear zonal distribution of uniform nano-sized particles in the hydrophilic domains, when the nano-filler loading was below 7.5%. Basic performances of the CLQCPAES/nano-ZrO₂ composite membranes were assessed to investigate their application in fuel cells in terms of the water uptake, swelling ratio, ion exchange capacity (IEC), hydroxide conductivity, thermal and mechanical properties, and alkaline stability. The modification of anion exchange membranes with multiblock ionomer structures, the use of a cross-linking technique and the introduction of nano-ZrO₂ particles greatly enhanced the water uptake, hydroxide conductivity, mechanical properties and alkaline stability of the composite membranes. In particular, the CLQCPAES/7.5%ZrO₂ membrane with an IEC value of 1.23 mmol g⁻¹ exhibited the best comprehensive properties and constitutes a good potential candidate for an anion exchange membrane to be used in AEMFCs.