Enhanced proton conductivity and dimensional stability of proton exchange membrane based on sulfonated poly(arylene ether sulfone) and graphene oxide

Highlights: • Proton conductivity of SPAES-GO-x membranes enhanced with increasing GO content. • Incorporating GO into SPAES matrix restrained SPAES-GO-x membranes swelling. • GO promoted the sulfonic acid groups of SPAES molecular chain aggregation (big ionic clusters) to enhance proton transport. - Abstract: A series composited membranes of sulfonated poly(arylene ether sulfone) and graphene oxide (SPAES-GO-x) have been exploited as proton exchange membrane. The properties of SPAES-GO-x membranes were evaluated including proton conductivity, water uptake, swelling ratio, oxide and thermal stability. Incorporating GO into SPAES matrix restrained the composite membranes swelling and enhanced their proton conductivity. The SPAES-GO-3% membrane showed a conductivity value of 0.183 S cm⁻¹ at 120 °C and relative humidity 100%. Compared with the pristine SPAES membrane, the swelling ratio of SPAES-GO-2% membrane was reduced by 55.7% at 90 °C. Small-Angle X-ray Scattering (SAXS) revealed GO promoted SPAES molecular chain movement to form bigger ionic clusters in favor of enhancing proton transport. X-Ray Diffraction and Field Emission Scanning Electron Microscope (XRD and FE-SEM) analysis further demonstrated GO was exfoliated and distributed throughout the SPAES matrix. These results indicated GO was an effective filler to trade off proton conductivity and swelling of composite membrane.