Effect of Hydrophobic Side Chain Length on Poly(carbazolyl terphenyl piperidinium) Anion Exchange Membranes

In recent years, with the continuous application of superacid-catalyzed condensation reaction in the preparation of anion exchange membranes (AEMs), a number of AEMs with excellent performance have been designed. Among them, the method to copolymerize two aromatic compounds with piperidone via a superacid-catalyzed reaction to synthesize anionic conducting copolymers has been widely discussed by researchers. Here, we focus on the introduction of poly(N-alkylcarbazole-co-terphenyl N,N′-dimethylpiperidinium) (PCTP-n), which is formed by copolymerizing different chain lengths of N-alkylcarbazole (AHC, n = 2, 4, and 6) and p-terphenyl with 1-methyl-4-piperidone (1M4P). As a result of the high-curvature backbone and hydrophobic flexible side chains, the PCTP-n AEMs show comprehensive performance advantage. Among them, the PCTP-6 membrane, with an ultralow swelling (7.9%) and an excellent OH– conductivity retention (91.9% in 2 M NaOH at 80 °C after 1080 h), highlights high dimensional stability and alkaline resistance. Then, the PCTP-2 membrane displays excellent mechanical robustness (EB: 40%, TS: 20 MPa) and a decent OH– conductivity (134 mS cm–1 at 80 °C). Furthermore, the PCTP-2-based single cell exhibits a decent power density of 542 mW cm–2 under H2–O2 condition.