Abstract
Novel sulfonated diamine isomers, 2,2'-bis(4-sulfophenoxy)benzidine (2,2'-BSPOB) and 3,3'-bis(4-sulfophenoxy)benzidine (3,3'-BSPOB), were prepared by direct sulfonation with fuming sulfuric acid from corresponding diamines of 2,2'(or 3,3')-bisphenoxybenzidine. Sulfonated polyimides (SPIs) were synthesized from these sulfonated diamines of BSPOB and 1,4,5,8-naphthlene tetracarboxylic dianhydride (NTDA) via polycondensation. Tough and ductile membranes were obtained by solution casting method. The SPI membranes with reasonable ion exchange capacities (IECs) displayed high proton conductivity and excellent water stability.
