Durable asymmetric composite membranes consisting of a film of cross-linked sulfonated poly(ether ether ketone) adhered to a sheet of sulfonated microporous poly(ethylene) are disclosed. The membranes have application in the recovery of water from feed streams were the ability to clean in situ is desirable, for example in dairy processing. Methods of preparing cross-linked sulfonated poly(ether ether ketone) suitable for use as a rejection layer in such membranes are also disclosed.
