Alkaline stable imidazolium-based ionomers containing poly(arylene ether sulfone) side chains for alkaline anion exchange membranes

Solvent processable anion exchange membranes (AEMs) containing imidazolium cation and poly(arylene ether sulfone) side chains were prepared via the ionization of poly(4-vinylbenzyl chloride)-graft-poly(arylene ether sulfone) copolymers, and followed by anion exchange with hydroxide ions. The ionized copolymers produced ductile, transparent membranes which possess a relatively high ionic conductivity (up to 1.6 × 10−2 S cm−1 at room temperature). The yielded membranes are soluble in polar aprotic solvents, such as DMSO and DMF, while insoluble in water and methanol. The synthesized AEMs show good alkaline stability in 1 M KOH at 60 °C for 20 days, as well as high dimensional and thermal stability. These results should pave way to the practical application of this kind of AEM in alkaline fuel cells.