Synthesis and Characterization of Novel Sulfonated Aromatic Polyamides for Proton Exchange Membranes

Abstract

Sulfonated polymer membranes play an important role in PEMFC (proton exchange membrane fuel cell). Series of sulfonated polyamides were prepared by polycondensation of a CF3-containing diamine with various ratios of terephthalic acid and 5-Sodiosulfoisophthalic acid. Sulfonated polyamides were characterized by 1H-NMR, FTIR and intrinsic viscosity. The resulting polyamides exhibited outstanding thermal stability. Membranes were prepared by solution casting, then characterized by determining ion-exchange capacity (IEC), water uptake, swelling ratio, proton conductivity and mechanical properties. With the gradual growth of sulfonic acid groups from 70% to 100% (molar ratio), IEC increased to 1.0223meq/g, and proton conducticity reached up to 3.82×10-2S/cm, while water uptake and swelling ratio remained in proper values. And the tensile strength of membranes was beyond 46.63MPa, which showed very good perspectives in PEMFC applications.