Novel cross-linked membranes based on polybenzoxazine and polybenzimidazole containing 4-phenyl phthalazinone moiety for high-temperature proton exchange membrane

Here, we report a series of novel PA-doped cross-linked benzoxazine-polybenzimidazole copolymer membranes. These membranes were obtained by mixing PBI containing 4-phenyl phthalazinone moieties (PPBI) and 4-phenyl phthalazinone-based benzoxazine (Bp) in N-methyl pyrrolidone (NMP), followed by heating to 260 A degrees C. The cross-linking reaction was determined by DSC and gel fraction tests. These copolymer membranes showed excellent comprehensive properties, with high proton conductivity up to 14.7 mS/cm at 160 A degrees C under anhydrous conditions. Besides, the P(PBp-co-PPBI)-30 membrane exhibited excellent mechanical property (approximately 50% improvement in tensile modules and strength compared to the pristine PPBI) and oxidative stability in Fenton's test (remaining intact after 226 h). This study proved that using benzoxazine as a cross-linking agent is a promising method for improving the properties of proton exchange membranes (PEMs).