Preparation And Properties Of Sulfonated Poly(Arylene Ether Sulfone)s For Proton Exchange Membrane Applications

This thesis focused on the preparation and characteiztion of proton exchange membrane based on sulfonated poly(arylene ether sulfone)s (SPAES) for fuel cell applications by modification methods as crosslinking, blending and grafting. The properties such as solubility, water uptake(WU), dimensional change, water stability, mechanical property as well as proton conductivity were investigated in detail.Based on the multiblock copolymers of sulfonated poly (arylene ether sulfone)(bSPAES), a series of crosslinked membranes (cbSPAES) were obtained by introducing P2O5as the crosslinking reagent during the membrane casting, where the crosslinking occurred as the dehydration reaction of sulfonic acid groups and active hydrogens in the polymer backbone. The results indicated that the WU and proton conductivity of the cbSPAES membranes increased with the increasing in the block length of hydrophilic moiety at the same crosslinking ratio, and exhibited better comprehensive performance than the random ones at the same ion exchange capacity (IEC). Comparing with those non-crosslinked membranes, they showed significant improvements in water uptake capacity, dimensional stability and water stability. All the crosslinked membranes exhibited comparable or larger proton conductivity than Nafion112at30-90℃in water. The membrane of cbSPAES(30/10)-10exhibited water uptake of65%, dimensional change in the in-plane (△l) and through-plane direction(△t) of0.16and0.18, proton conductivity of163mS/cm in water at60℃, showed the best comprehensive performance.Based on the random copolymers of sulfonated poly (arylene ether sulfone)(RSPAES), a series of RSPAES/TiO2composite membranes were obtained by introducing nano-sized TiO2(1-10wt%) during the membrane casting by ball milling. The results indicated that the water uptake and dimensional change of the composite membranes increased first and then decreased with the increase in the TiO2content. Comparing with pristine membrane, slight improvements were achieved in dimensional stability and water stability. Among them, the membrane of RSPAES-2showed the best comprehensive performance.A series of novel side-chain-type sulfonated poly(ether sulfone)s (SPES) copolymers were successfully synthesized from4,4’-sulfonyldiphenol (SDP), DFBP, and2-naphthol-6,8-disulfonic acid dipotassium (NDS-K) via nucleophilic copolymerization at low temperature. The membranes IEC of0.91-1.77mmol/g were obtained through solution casting. The results indicated that the SPES membranes displayed water uptakes33-76%at 60℃, and proton conductivity achieved228mS/cm for the membrane with IEC of1.77mmol/g).