Imidazole-Functionalized Sulfonated Polybenzothiazole/Phosphorylated Graphene Oxide Composite Membranes for Proton Exchange Membranes

A kind of sulfonated polybenzothiazole (imidazole) (sPBT-BI) polymers were synthesized by random copolymerization. The benzimidazole (BI) structural modification of the sulfonated polybenzothiazole (sPBT) backbone facilitated more effective acid-base interactions with acidic components, optimizing the interfacial compatibility between functional materials and the polymer matrix, which collectively boosted the membranes' performance metrics. Phosphonated graphene oxide (PGO) was also doped into the sPBT-BI matrix at varying ratios to get Sulfonated polybenzothiazole/phosphorylated graphene oxide composite membranes. The composite membranes exhibited low water uptake while maintaining impressive dimensional stability even under highly hydrated conditions. Furthermore, the incorporation of PGO provided additional proton transport pathways, offering excellent proton transport enhancement for the composite membranes. Owing to this, one of the composite membrane showed a high proton conductivity (120.59 mS cm ^-1 ), surpassing that of the commercial Nafion117 membrane. Notably, the composite membrane demonstrated exceptional durability, with almost no decline in output voltage after continuous operation for 20 hours, indicating outstanding long-term stability of this novel membrane matrix.