Effects of a sulfonated hydrophilic cross-linked network on the microstructure and properties of Nafion matrix

A hydrophilic cross-linked proton exchange membrane was constructed in a Nafion matrix based on azide polysulfone containing sulfonic acid (SPSU-N₃) and alkynyl substituted polyvinyl alcohol (APVA) through azide–alkyne click chemistry reaction. Arising from the increased polarity of the cross-linked network and high cross-linking density, the alcohol barrier performance of the Nafion membrane was greatly improved. The methanol permeability of the Nafion/cross-linked SPSU-N₃ and APVA membrane decreases to 1.86 × 10⁻⁷ cm² s⁻¹, which is about 88% lower than that of the recast Nafion membrane, and the proton selectivity is 18.5 × 10⁴ S s cm⁻³.