Patent ID: 7073671

Claim:
A porous membrane comprising a polymeric microporous substrate membrane and a separately formed heat stable, biomolecule resistant surface having a biomolecule binding of less than about 30 micrograms per square centimeter as measured by the lgG binding test and a heat resistance of less than about twice the lgG adsorption of the same surface prior to heat exposure as measured by exposing the membrane to a method selected from the group consisting of heating to 135Â° C. for two hours in an oven and heating to 121Â° C. in a steam autoclave for one hour wherein said surface is comprised of a first polymeric coating and a second polymeric coating, the first coating being a crosslinked hydrophilic terpolymer and a second coating applied to the first coating, the second coating being a second polymer modified with functional groups and wherein the sizes of the pores of the porous membrane after applying the first and second coatings are not significantly different from the sizes of pores of the microporous substrate membrane before application of the first and second coatings.