Synthesis and characterization of a novel sulfonated poly (aryl ether ketone sulfone) semi-crosslinked membrane with high proton selectivity through click reaction for direct methanol fuel cells

A novel sulfonated polyvinyl alcohol containing alkynyl groups (SPVA-C≡C) and a new sulfonated poly (aryl ether ketone sulfone) (SPAEKS) are synthesized. Semi-crosslinked membrane (semi-crosslink-SPAEKS-x) was prepared by click reaction of mercapto-alkynes between 1, 5-pentanedithiol and SPVA-C≡C. The chemical structures of SPAEKS, SPVA-C≡C and semi-crosslink-SPAEKS-x are confirmed by 1 H-NMR and FTIR spectra. The semi-crosslink-SPAEKS-x membranes show good mechanical properties, excellent dimensional stability and oxidative stability. The proton conductivity of SPAEKS and semi-crosslink-SPAEKS-x membranes is in the range of 25.6–52.5 mS/cm. The methanol permeability of semi-crosslink-SPAEKS-x membranes is in the range of 1.4–1.7 × 10 −7 cm −2 s −1 , which is much lower than that of Nafion 117 membrane (18.3 × 10 −7 cm −2 s −1 ). Especially, the proton selectivity of semi-crosslink-SPAEKS-15 membrane (24.3 × 10 4 S s cm −3 ) is above seven times higher than that of Nafion 117 membrane (3.4 × 10 4 S s cm −3 ).