Synthesis and characterization of sulfonated poly(ether imide) membranes using thermo-analysis and dialysis process

Polyimides have been investigated as alternative materials to commercial membranes, once these polymers present high thermal, chemical, and mechanical performances. This work has modified poly(ether imide), PEI, by sulfonation reaction using acetyl sulfate as sulfonating agent. Sulfonated PEI (SPEI) films were characterized by infrared spectroscopy, ion exchange capacity (IEC), glass transition temperature (Tg), and proton diffusivity. The influence of degree of sulfonation on IEC, Tg, and proton diffusivity can be observed. SPEI membranes have presented proton diffusivity lower than that obtained with a commercial sulfonated membrane (Nafion). This result was related to low degree of sulfonation and low chain mobility of the obtained SPEI.