Highly sulfonated polymer-grafted graphene oxide composite membranes for proton exchange membrane fuel cells

[Display omitted] •SPAES composite membranes were prepared using highly sulfonated polymer-grafted graphene oxide as a filler.•The filler was synthesized by grafting highly sulfonated polymer on GO surface using a mild reaction condition.•Outstanding compatibility between the filler and matrix polymer.•Physicochemical stability of the composite membranes was highly improved.•Excellent proton conductivity of the composite membranes. Sulfonated poly(arylene ether sulfone) (SPAES) composite membranes were prepared using graphene oxide (GO) and sulfonated poly(arylene thioether sulfone)-grafted graphene oxide (SATS-GO) as fillers for proton exchange membrane fuel cell (PEMFC) applications. When GO and SATS-GO were mixed with SPAES to form the composite membranes, dimensional stability, chemical stability, and mechanical strength were improved. The composite membranes containing SATS-GO especially showed higher proton conductivity than the pristine SPAES and the composite membrane containing GO because of highly sulfonated polymer (SATS) introduced on GO surface. Furthermore, the sulfonic acid groups in SATS-GO can increase the compatibility between the filler and matrix polymer.