A comprehensive overview of polyphenylene oxide-based anion exchange membranes from the perspective of ionic conductivity and alkaline stability

This comprehensive review discusses the latest advancements in polyphenylene oxide-based (PPO) anion exchange membranes (AEMs), showcasing their development through innovative application. This review extensively covers the synthesis, properties, and strategic enhancements in hydroxide ion conductivity, dimensional stability, and alkaline stability. Central to the discussion are pioneering approaches such as functionalization, crosslinking, and the incorporation of heterocyclic groups, which collectively contribute to the improved performance and durability of these membranes. It highlights the importance of introducing steric hindrance effects through the selection of cations to delay alkaline attack in PPO AEMs. In addition, the integration of cutting-edge materials such as covalent organic frameworks (COFs) and metal–organic frameworks (MOFs) which can potentially enhance the ionic conductivity is reviewed. This review suggests potential areas for further advancement of PPO AEMs to achieve improved ionic conductivity and alkaline stability, enabling more efficient and reliable utilization in fuel cell and water electrolyzer applications.