Triblock copolymer anion exchange membranes bearing alkyl-tethered cycloaliphatic quaternary ammonium-head-groups for fuel cells

To explore highly conductive and alkaline stable anion exchange membrane (AEM) materials, triblock copolymers bearing alkyl-tethered cycloaliphatic quaternary ammonium-head-groups are prepared via nucleophilic substitution , Friedel-Crafts acylation, ketone reduction and Menshutkin reaction . The designed triblock copolymers composed of quaternized poly(phenylene oxide) segments and poly(ether sulfone) segments are responsible for the microphase separated morphology and well-connected ion domains, as confirmed by transmission electron microscopy . The highest conductivity, up to 105.1 mS cm −1 at 80 °C is achieved for the AEM with ionic exchange capacity (IEC) of 1.81 meq g −1 . Furthermore, the AEMs show robust alkaline stability due to the alkyl-tethered cation-head-groups structure. High retention of hydroxide conductivity (88.9%) and IEC (91.2%) is observed for the AEMs via degradation test in a 1 M aqueous KOH solution at 80 °C for 480 h. Based on the AEM with high conductivity, a H 2 /O 2 fuel cell achieves a peak power density of 176.5 mW cm −2 (80 °C) at a current density of 500 mA cm −2 .