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 °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 × 10 −8  cm 2  s −1 for PPSF to 0.96 × 10 −8  cm 2  s −1 for P80S20.