Preparation and properties of sulfonated polybenzimidazole/phosphonic acid modified graphene oxide proton exchange composite membrane

Phosphonic acid modified graphene oxide (MGO) grafted with phosphonic acid groups and sulfonic acid groups was synthesized by phosphorylation of the aminated graphene oxide (GO). Thermogravimetric analysis indicated that MGO had good thermal stability. The sulfonated polybenzimidazole (SPBI)/MGO composite membrane was successfully prepared by doping MGO into SPBI by in-situ polymerization. SEM showed that the membrane surface was dense and the addition of MGO presented a flake structure in the cross section. The SPBI/MGO-1% composite membrane had the highest acid doping rate of 248.8%. The addition of MGO improved the thermal stability of the composite membrane. The tensile strength of the dry composite membrane increased by 36% compared to the Nafion117 membrane (26.65MPa) and the tensile strength of the SPBI/MGO-1% wet membrane reached 69.46MPa, which was 41.2% higher than that of the SPBI membrane. The composite membrane had high mechanical properties. The proton conductivity of SPBI/MGO composite membranes increased with the increase of MGO content. The proton conductivity of SPBI/MGO-1% composite membrane reached 0.193S/cm at 160℃ and 10% RH, indicating its high application prospect in high temperature and low humidity proton exchange membrane fuel cells. © 2020, Chemical Industry Press. All right reserved.