Synthesis and characterization of new ion exchange membranes made from chlorosulfonated polyethersulfone (SO 2 Cl-PES) crosslinked by polyaminated crosslinking reagents have been performed. Two examples are described: one crosslinked by hexane diamine, the other by amino-polyethersulfone (NH 2-PES). Sulfonated polyether sulfone (S-PES) and NH 2-PES have similar chemical structures that allow compatibility. Surprisingly enough, better results were obtained using amino-polyethersulfone. The best results have been obtained using SO 2 Cl-PES with 1.3 SO 2 Cl group per monomer unit crosslinked by 0.2 equivalent of NH 2-PES. The membranes, less brittle than pristine SPES and insoluble in solvents such as DMAc, were characterized by TGA, DMA, DSC, ionic conductivity, transport numbers, and water swelling. The results showed that these membranes presented very promising performances for use in Proton Exchange Membrane Fuel Cells.

Sulfonated poly(arylene ether sulfone) (SPES) has received considerable attention in membrane preparation for proton exchange membrane fuel cell (PEMFC). But such membranes are brittle and difficult to handle in operation. We investigated new membranes using SPES grafted with various degrees of octylamine. Five new materials made from sulfonated polyethersulfone sulfonamide (SPESOS) were synthetized with different grades of grafting. They were made from SPES, with initially an ionic exchange capacity (IEC) of 2.4 meq g −1 (1.3 H + per monomer unit). Pristine SPES with that IEC is water swelling and becomes soluble at 80 • C, its proton conductivity is in the range of 0.1 S cm −1 at room temperature in aqueous H 2 SO 4 1 M, similar to that of Nafion ®. After grafting with various amounts of octylamine, the material is water insoluble; membranes are less brittle and show sufficient ionic conductivity. Proton transport numbers were measured close to 1.