Comb-shaped phenolphthalein-based poly(ether sulfone)s as anion exchange membranes for alkaline fuel cells

Abstract

A series of novel comb-shaped phenolphthalein-based poly(ether sulfone)s was synthesized for preparing anion exchange membranes (AEMs). Hexadecyldimethylamine with a long alkyl chain was used as the quaternization reagent to form a comb-shaped architecture of the copolymers. Due to the presence of a long alkyl side chain with hydrophobicity, the as-synthesized comb-shaped AEMs possess a self-anti-swelling property resulting in a low water uptake and swelling ratio. The PES-B100-C16 membrane exhibits excellent alkaline stability due to the presence of large volumetric β-alkyl chains linking to the cationic group that resist the attack of OH⁻, and retain available ionic conductivity in a 2 M KOH solution at 60 °C for 360 h. An open circuit voltage of the single cell reached 0.67 V, and the maximum power density was 43 mW cm² at a current density of 125 mA cm⁻² without optimization in a single H₂/O₂ alkaline fuel cell at 50 °C.