The Sulfonated Poly(ether sulfone ketone) Ionomers Containing Partial Graphene of Mesonaphthobifluorene for PEMFC

Novel sulfonated poly(ether sulfone ketone)s containing mesonaphthobifluorene (MNF) moiety were synthesized and their properties characterized. The prepared polymers had a partial graphene structure due to the MNF group. Poly(ether sulfone ketone)s bearing tetraphenylethylene (TPE) on the polymer backbone were synthesized by polycondensation, after which MNF was formed by the intra-cyclization of TPE by Friedel-Crafts reaction with Lewis acid (FeCl3). The sulfonation was performed selectively on MNF units with concentrated sulfuric acid. The synthesized polymer electrolyte membranes showed better thermal and dimensional stabilities owing to the MNF-induced graphene structure in the polymer backbone. The water uptake of the synthesized membranes ranged from 30% - 55%, compared with 32.13% for Nafion 211 (R) at 80 degrees C. The proton conductivity (80 degrees C, RH 90%) ranged from 74.6 - 101.2 mS/cm, compared with 102.7 mS/cm for Nafion 211 (R).