Synthesis and properties of ABPPQ for high-temperature proton exchange membrane fuel cells

In this study, the one-pot synthesis of self-polymerizable quinoxaline monomer was developed. 3-(4-hydroxyphenyl)-2-phenyl-6-fluoroquinoxaline and 2-(4-hydroxyphenyl)-3-phenyl-6-fluoroquinoxaline mixture (M1a,b) was synthesized from benzyl 4-hydroxyphenyl ketone and 1,2-diamino-4-fluorobenzene, catalyzed by 1,4-diazabicyclo[2.2.2]octane. Then, an ether-containing AB type polyphenylquinoxaline (ABPPQ) was synthesized successfully from the monomer M1a,b. The ether-containing ABPPQ is organosoluble, and has good proton conductivity at high temperatures after doping with phosphoric acid. It is suitable for use in high-temperature proton exchange membrane fuel cells. Compared to polybenzimidazole (PBI), ABPPQ has higher acid doping level at the same doping time, because it has more sites that can be doped with phosphoric acid in the PPQ's molecular structure than PBI.