Transparent porous membrane having hydrophilic surface and process
AssigneeMillipore Corporation
InventorsAldo M. Pitt, Michael J. Steuck
Life of this patent
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Abstract
A composite, microscopically transparent, porous membrane is formed from a porous polytetrafluoroethylene membrane having desired bulk properties on which is directly coated a cross-linked polymer having desired surface properties. The composite membrane retains the porosity of the porous polymeric membrane.
Claims32
The process for forming a composite porous membrane which is microscopically transparent in aqueous solution and which is formed from a porous polytetrafluoroethylene substrate having an average pore size between about 0.001 and 10 microns, said substrate being directly coated over its entire surface with a crosslinked second polymer, said composite porous membrane having essentially the same porous configuration as said porous membrane substrate which comprises:
- contacting said porous membrane with a solution of a monomer of said second polymer, a cross-linking agent for said monomer and a polymerization initiator for said monomer under conditions to polymerize said monomer and to cross-link said second polymer over the entire surface of said porous polytetrafluoroethylene substrate, under conditions to avoid plugging of said pores and to form a coating between about 10 and 200 Angstroms thick, said solution comprising between about 10 and 90 weight percent water and between 80 and 10 weight percent of a water miscible organic solvent.
The process for forming a composite hydrophilic porous membrane which is microscopically transparent in aqueous solution and which is formed from a porous polytetrafluoroethylene substrate having an average pore size between about 0.001 and 10 microns said substrate being directly coated over its entire surface with a crosslinked second polymer, said composite porous membrane having essentially the same porous configuration as said porous membrane substrate which comprises:
- (a) washing said porous membrane substrate to wet the surfaces of the pores in said porous membrane;
- and
- (b) contacting said porous membrane with a solution of a monomer of said second polymer, a cross-linking agent for said monomer and a polymerization initiator for said monomer under conditions to polymerize said monomer and to cross-link said second polymer over the entire surface of said porous polytetrafluoroethylene substrate, and to form a coating between about 10 and 200 Angstroms thick, said solution comprising between about 10 and 90 weight percent water and between about 10 and 80 weight percent of a water miscible organic solvent.
Dependencies are inferred from the claim text.