Synthesis and characterization of a novel locally high dense sulfonated poly (aryl ether ketone sulfone) for DMFCs applications

A new sulfonated poly (aryl ether ketone sulfone) (SPAEKS-x) with locally dense sulfonic acid groups is synthesized by post-sulfonation. The SPAEKS-x membranes have a number average molecular weight of 45,000-58,000 g/mol and exhibit excellent mechanical properties. In addition, SPAEKS-x membranes have moderate water absorption, swelling rate, excellent thermal stability and good oxidative stability. The proton conductivity of SPAEKS-x membranes ranges from 35.6 to 52.4 mS/cm. All membranes show much lower methanol permeability than Nafion 117 membrane. Therefore, all membranes show higher proton selectivity than Nafion 117 membrane. In particularly, proton selectivity of SPAEKS-40 (15.8 x 10(4)S s cm(-3)) is about 5 times higher than that of Nafion 117 membrane (3.5 x 10(4)S s cm(-3)). Overall, SPAEKS-x membranes as a proton exchange membrane have shown very great application prospects in direct methanol fuel cells.