Sulfonated phenolphthalein poly(ether sulfone) (SPES C) with various sulfonation degree were synthesized by reaction of PES C with sulfonic acid as sulfonating agent and solvent.Their proton conductivity and methanol permeability as a function of the degree of sulfonation were investigated.For 70 21% degree of sulfonation,proton conductivity was 3 45×10 -2 S/cm at 100℃,which is closed to or superior to that of Nafion 115 membrane at the same conditions (4 19×10 -2 S/cm).Methanol permeability of SPES C was considerable smaller than that of Nafion 115 membrane.Because of their high conductivity and low methanol permeability,SPES C membranes appear to be excellent candidate for use in DMFC applications.
