Membrane properties of trisulfonated hydrophilic and partially fluorinated hydrophobic multiblock copolymer

Abstract A multiblock copolymer with increased charge density in the hydrophilic phase was synthesized by utilizing a trisulfonated poly(arylene ether sulfone) backbone (SHQS100). To achieve a balance of membrane properties a partially fluorinated poly(arylene ether benzonitrile) hydrophobic phase (6FPAEB) was used in uneven block lengths to form the hydrophilic-hydrophobic multiblock copolymer. Multiblock copolymers were synthesized via nucleophilic aromatic substitution to achieve high molecular weight copolymers and corresponding ductile membranes. Combination of the shorter increased charge density hydrophilic phase and longer partially fluorinated hydrophobic phase resulted in superior proton conductivity and mechanical properties while limiting water uptake and swelling, despite high ion-exchange capacity. The trifunctional SHQSH hydrophilic phase is proposed to produce a more concentrated charge region in the hydrophilic phase, while swelling of the membrane was limited by a longer partially fluorinated hydrophobic phase.