DIRECT SYNTHESIS AND PROPRTIES OF SULFONATED POLY(ARYLENE ETHER SULFONE) COPOLYMERS FOR PROTON EXCHANGE MEMBRANES IN FUELCELLS

A series of sulfonated poly (arylene ether sulfone) (SPAES) copolymers with different degree of sulfonation (D-s) were synthesized by aromatic nucleophilic polycondensation of 3,3'-disulfonate-4,4'-dichlorodiphenylsulfone (SDCDPS) 4,4'-dichlorodiphenylsulfone (DCDPS) and 4,4'-biphenol (BP) Synthesized sulfonated copolymers were characterized by FT-IR, TGA and DSC. Moreover, the microstructure of membranes was investigated by TEM, and the relationship between structure and performance was established. The influence of different D-s on the properties of SPAES membranes was studied, and it showed that the increase of sulfonated groups in the polymers led to the increase of water uptake, ion exchange capacity (IEC) methanol diffusion coefficient and proton conductivitie of the membranes. Physical and electrochemical performances of all membranes were studied thoroughly. The results showed that the proton conductivity of SPAES-2 membrane was 0.116 S/cm at 80 degrees C and 0.126 S/cm at 100 degrees C, which were higher than those of Nafion 117 membrane (0.114 S/cm and 0.117 S/cm) 2 However, the methanol diffusion coefficient of SPAES-2 membrane only reached 8.4 x 10(-7) cm(2)/s and was much lower than that of Nafion 117 membrane (2.1 x 10(-6) cm(2)/s). The new synthesized membranes displayed good potential in application as proton exchange membranes (PEM) in proton exchange membrane fuel cells (PEMFC) and direct methanol fuel cells (DMFC).