Structural Modification of Poly(p-phenylene) Ionomers for Alcohol-Processable and Tough Hydrocarbon Membranes

Fluorine-free hydrocarbon proton exchange membranes (PEMs) are attracting increasing attention as alternatives to perfluorosulfonic acid (PFSA)-based materials. However, the limited processability of many hydrocarbon ionomers, particularly their poor compatibility with alcohol-based solvent systems, remains a major barrier to scalable membrane and membrane–electrode assembly (MEA) manufacturing. In this presentation, a benzoyl-substituted poly(p-phenylene) ionomer incorporating meta-linked phenylene units is explored as an approach to improve alcohol processability and mechanical toughness. The introduction of nonlinear backbone segments disrupts aromatic chain packing and reduces conformational rigidity, leading to enhanced compatibility with alcohol-based green solvents and improved tensile toughness and puncture resistance. The modified ionomers also enable all-hydrocarbon MEA fabrication using hydrocarbon binders. Electrochemical evaluation in proton exchange membrane water electrolysis demonstrates competitive performance together with stable operation under differential pressure conditions. These findings highlight backbone structural modification as an effective strategy for developing green-processable and mechanically durable fluorine-free PEMs.