In‐situ Crosslinked Polymer Electrolyte Membranes from Thermally Reactive Oligomers for Direct Methanol Fuel Cells

Thermally reactive ally‐terminated sulfonated oligosulfone was easily synthesized and made it possible to fabricate crosslinked membrane with high ionic group contents for direct methanol fuel cells. The crosslinked network structures of rigid rod sulfonated polyarylene sulfone showed high suppression of swelling with high sulfonation degree of 70%, which gave excellent properties for direct methanol fuel cell applications. The proposed membranes gave unprecedented reduction in methanol cross‐over (less than 3% of Nafion 112) and high ionic conductivity (∼80% of Nafion 112).