LAUSR

For enhancing hydroxide ion conductivity, alkaline stability, and fuel cell performance of quaternaized aromatic/perfluoroaklyl copolymer (QPAF) membranes, ammonium groups attached to the polymer backbone have been investigated. The ammonium groups included dimethylbutylamine (DMBA), dimethylhexylamine (DMHA), and 1,2-dimethylimidazole (DMIm) groups in comparison to the trimethylammonium (TMA) group. DMBA turned to be the optimum ammonium group for QPAF membranes in terms of its high hydroxide ion conductivity based on well-connected and larger phase-separated morphology than that of QPAF-TMA with similar ion exchange capacity (IEC) value. QPAF-DMBA (IEC = 1.33 mequiv g–1) exhibited the highest hydroxide ion conductivity among the tested membranes up to 152 mS cm–1 in water at 80 °C, which was 1.6 times higher than that of QPAF-TMA (95 mS cm–1). In addition, QPAF-DMBA exhibited reasonable alkaline stability in 1 M KOH at 60 °C for 1000 h. The remaining conductivity was 44 mS cm–1 (58%) for QPAF-DMBA, whil...