Membrane obtained from the sulfonated polysulfone (SPSU) is a potential substitute for perfiuorosulfonic acid membrane used now in proton exchange membranes fuel cells (PEMFC). In this report, SPSU was prepared by direct solution sulfonation of bisphenol-A-polysulfone (PSU) using chlorosulfonic acid (HSO3C1) as sulfonating agent. Fourier transform infrared spectra (FTIR) and thermogravimetric analysis (TGA) were used to characterize the structure and thermal properties of obtained membranes. The results indicated that SPSU was successfully synthesized due to the presence of sulfonate groups in the samples. The prepared SPSU samples were of lower decomposition temperatures compared with PSU. The analyses of ion-exchange capacity (IEC), proton conductivity and mechanical properties of SPSU membranes revealed that sulfonation levels from 30 to 50% were easily achieved by varying the content of the sulfonating agent. IEC could be controlled by changing the amount of HSO3CI. The proton conductivities increased with increasing of sulfonation. Compared with Nafion(r) 117, SPSU membranes were of higher tensile strength and lower tensile elongation, comparable or higher proton conductivities and comparable water uptake value.
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