Alkyl bisimidazolium-mediated crosslinked comb-shaped polymers as highly conductive and stable anion exchange membranes

Abstract

Crosslinked poly(arylene ether sulfone)s (PES) with pendant alkyl bisimidazolium units, which act as both crosslinkage sites and hydroxide conductors, were developed as anion exchange membranes (AEMs). These bisimidazolium-mediated crosslinked membranes (BI-cPESs) display a high hydroxide conductivity exceeding 0.012 S cm⁻¹ at 20 °C and 0.061 S cm⁻¹ at 80 °C, together with good chemical, thermal, mechanical, oxidative and dimensional stabilities. The BI-cPES membrane, which includes a long alkyl chain (C₁₀, BI-cPES-10), form self-aggregated structures due to the long pendant hydrophobic side chain that forms a comb shape. The benefit of this crosslinked comb-shaped system is its high conductivity of 0.027 S cm⁻¹ at 20 °C, even at an IEC as low as 1.13 meq. g⁻¹ and a low water uptake of 8.70%.