Durable asymmetric composite membranes and modified substrates used in their preparation
Durable asymmetric composite membranes consisting essentially of a film of cross-linked sulfonated poly(ether ether ketone) adhered to a sheet of hydrophilicitized microporous poly(ethylene) are disclosed. The membranes have application in the recovery of water from feed streams where 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 the rejection layer and hydrophilicitized sheets of microporous poly(ethylene) suitable for use as the support layer of such membranes are also disclosed.
1. An asymmetric composite membrane comprising a film of crosslinked sulfonated poly(ether ether ketone) adhered to one side of a hydrophilicitized sheet of microporous polyolefin where the hydrophilicitized sheet of microporous polyolefin consists of polyolefin grafted with 4-ethenyl-benzenesulfonic acid.
2. The membrane of claim 1 where the crosslinked sulfonated poly(ether ether ketone) incorporates a crosslinking agent selected from the group consisting of: divinylbenzene; ethylene glycol dimethacrylate; and glyoxal bis(diallyl acetal).
3. The membrane of claim 2 where the crosslinked sulfonated poly(ether ether ketone) incorporates divinylbenzene as the crosslinking agent.
4. The membrane of claim 1 where the polyolefin is poly(ethylene).
5. An asymmetric composite membrane consisting of a film of crosslinked sulfonated poly(ether ether ketone) incorporating divinylbenzene as the crosslinking agent adhered to one side of a sheet of microporous poly(ethylene) grafted with 4-ethenyl-benzenesulfonic acid.