Synthesis and characterization of sulfonated polymers containing triazoles as low-humidity proton exchange membranes

A series of copolymers, sulfonated poly (aryl ether ketone sulfones) containing triazoles (SPAEKST), were synthesized by direct polycondensation reactions. The content of sulfonic acid and triazole groups was controlled by adjusting the molar ratio of feeding. The structures of triazole monomer and SPAEKST copolymers were confirmed by their 1H NMR and FTIR spectral analyses. The performance of membranes such as thermal and oxidative stabilities was clearly improved with increasing content of triazole groups. The morphology of SPAEKST membranes was investigated by TEM analyses, and the results indicate that the sulfonic acid groups were dispersed evenly. No clear phase separation was observed. The contact angle tests showed that the presence of triazoles clearly improved the hydrophilicity of membranes. The water desorption curves showed that the water retention of membranes increased with increasing content of triazole groups. The proton conduction of membranes exhibited a low dependence on relative humidity. At 80 °C, the proton conductivity of SPAEKST-30 % reached to 1.1 mScm−1 under 20 % RH.