A polymeric structural approach to improving proton-blocking performance in anion exchange membranes for electrochemical systems

Anion exchange membranes are crucial in processes involving acids and bases, yet they often suffer from proton leakage, which diminishes system efficiency and membrane durability. To tackle this challenge, a novel polymeric structural approach was assessed to enhance proton-blocking performance. This approach scrutinized the interaction between protons and proton-attracting chemical species in the presence or absence of dimethyl (DM) groups within the poly(phenylene oxide) structure, and compared with the commercially available poly(aryl piperidinium) (PiperION) membrane containing strongly hydrophobic -CF3 groups. The findings revealed proton-blocking efficiencies of 60 % for PiperION, 62 % for PPO, and 72 % for DMPPO, with corresponding proton permeabilities of 36.71 × 10−6 cm2·s−1, 17.30 × 10−6 cm2·s−1, and 7.58 × 10−6 cm2·s−1, respectively. These results suggest enhanced proton-blocking performance with DM groups, while -CF3 groups do not provide a substantial improvement. Moreover, PPO-based membranes, when reinforced as composites, demonstrated superior proton-blocking capabilities compared to non-reinforced counterparts. These findings underscore the significance of designing anion exchange membranes with reduced proton interactions to achieve optimal proton-blocking performance in electrochemical systems.