Reinforcement of Highly Proton Conducting Multi-Block Copolymers by Online Crosslinking

Multi-block copolymers with sulfonated polysulfones as hydrophilic blocks and polyethersulfones as hydrophobic blocks have been modified by two methods: covalent and ionic crosslinking. Both methods can easily be integrated into a membrane casting process and improve the membrane properties considerably: water uptake or swelling is decreased and the mechanical stability of the membranes is strongly increased, not only in terms of higher moduli but especially with respect to much higher fracture toughness. The phase-separated morphology is not severely affected by crosslinking so that the advantageous properties of such membranes are retained. Covalent crosslinking is preferred since it does not sacrifice proton conductivity at all.