Enhancing proton conduction of sulfonated poly (phenylene ether ether sulfone) membrane by charged surface modifying macromolecules for H2/O2 fuel cells

Abstract

Blend membranes comprising sulfonated poly (phenylene ether ether sulfone) (SPEES) - charged surface modifying macromolecules (cSMMs) were fabricated as an alternative proton exchange membrane (PEM) for H2/O2 fuel cell applications. Prepared membranes were characterized by determining the ion exchange capacity, water uptake, proton conductivity, oxidative stability and dimensional stability. The water uptake of SPEES/cSMM blended membrane was found to be higher than that of the pristine SPEES and the Nafion 117 membranes. Proton conductivity of the blend membranes is in the range of 10−3 to 10−2 S/cm. The conductivity of the prepared membranes increases with temperature, in particular, the poly (propylene glycol) – hydroxy benzene sulfonate (PPG-HBS) blended SPEES membrane shows rise in conductivities from 1.61 × 10−2 S/cm (25 °C) to 5.22 × 10−2 S/cm (80 °C). Surface morphology of the membranes was investigated by tapping mode atomic force microscopy (AFM), which indicates that the nodule size and surface roughness are increased by the incorporation of cSMM into the SPEES matrix. Surface modified blended membranes exhibited excellent thermal stability and acceptable dimension stability in 80 °C, which implies that the SPEES/cSMM blended membranes are promising materials for PEMFC application.