N,N-bis(sulfopropyl)aminyl-4-phenyl polysulfone and O,O′-bis(sulfopropyl)resorcinol-5-yl-4-phenyl polysulfone composite membrane for proton exchange membrane fuel cells

Novel functionalized polysulfone with high local density of sulfonic acid groups, N , N -bis(sulfopropyl)aminyl-4-phenyl polysulfone or O , O′ -bis(sulfopropyl)resorcinol-5-yl-4-phenyl polysulfone (PSF-X-C 3 H 6 SO 3 H, X = N or O) are synthesized. These polymers are synthesized by bromination of polysulfone followed by Suzuki cross-coupling reaction to graft the aminophenyl groups and the dimethoxyphenyl groups onto the polymeric backbone, followed by introduction of the sulfopropyl groups via sultone ring-opening reaction. In addition, the composite membrane of PSF-O-C 3 H 6 SO 3 H and PSF-N-C 3 H 6 SO 3 H is also synthesized for comparison. The maximum proton conductivity of composite PSF-O-C 3 H 6 SO 3 H and PSF-N-C 3 H 6 SO 3 H reaches 46.66 mS cm −1 at 95 °C and 90% RH, higher than PSF-O-C 3 H 6 SO 3 H (42.06 mS cm −1 ) and PSF-N-C 3 H 6 SO 3 H (38.76 mS cm −1 ). Meanwhile, the composite exhibits compromised water uptake and swelling ratio, and low methanol permeability . The excellent overall performance of the composite is attributed to phase-separation between the hydrophilic and the hydrophobic subphases, and the hydrogen-bonding network developed in the hydrophilic subphases.