Pendant-sulfonated poly(arylene ether ketone) (PAEK) membranes cross-linked with a proton conducting reagent for fuel cells

► Pendant sulfonated cross-linked PAEK membranes are prepared for fuel cell application. ► Proton conductivity is comparable to Nafion® 117. ► Methanol permeability is very low - about a half to a fourth of Nafion®. ► Cross-linking reduces water uptake and thus enhances dimensional stability. ► The 20% cross-linked system exhibits the best cell performance.