Proton conducting composite membranes based on sulfonated polysulfone and polysulfone-g-(phosphonated polystyrene) via controlled atom-transfer radical polymerization for fuel cell applications

Polysulfone-g-(phosphonated polystyrene) (PPSF) is synthesized by grafting of poly(phosphonated polystyrene) to polysulfone (PSF) backbone via controlled atom-transfer radical polymerization (ATRP). And its comprehensive performances are improved by compositing with sulfonated polysulfone (SPSF). The best comprehensive performances are achieved in the composite membrane consisting of 80 wt% PPSF and 20 wt% SPSF (P80S20). The maximum proton conductivity reaches 17.23 mS cm(-1) at 95 degrees C and 90% RH, which is 3.3 times as high as the pristine PPSF at 5.22 mS cm(-1). In addition, the composite membrane exhibits favorable thermal stability, compromised water uptake and swelling ratio, significantly improved mechanical strength. Moreover, the methanol permeability is reduced from 5.74 x 10(-8) cm(2) s(-1) for PPSF to 0.96 x 10(-8) cm(2) s(-1) for P80S20.