Novel Coated Membranes and Other Articles

Abstract

The present invention provides porous media or membranes having a surface coating that includes a cross-linked terpolymer which has a superior combination of properties, including heat stable biomolecule resistant adsorptive properties, resistance to strong alkaline solutions, and low levels of extractable matter. In some preferred embodiments, the porous media is a porous membrane.

1 - 66 . (canceled) 
     
     
         67 . A method for the preparation of a clean, caustic resistant porous membrane, said membrane comprising a porous membrane substrate and a heat stable biomolecule resistant surface coating, said method comprising the steps of:
 a. providing a porous membrane substrate;   b. optionally washing said porous membrane substrate with a wetting liquid to wet the surfaces thereof;   c. optionally washing said wet porous membrane substrate with a second wetting liquid to replace said first wetting liquid, leaving said porous membrane substrate wetted with said second liquid;   d. contacting the surfaces of said porous membrane substrate with a solution containing polyfunctional monomer that is methylene-bis-acrylamide, and at least two monofunctional monomers, wherein at least one of said monofunctional monomers is dimethylacrylamide or diacetone acrylamide; and   e. polymerizing said monomers to form said heat stable biomolecular resistant surface.   
     
     
         68 . The method of  claim 67  wherein said porous membrane substrate is a polyvinylidene difluoride microporous membrane. 
     
     
         69 . The method of  claim 67  wherein the solution further comprises a supplemental property modifying monomer. 
     
     
         70 . The method of  claim 69  wherein said supplemental property modifying monomer is selected from the group consisting of (3-(methacryloylamino)propyl)trimethylammonium chloride, (3-acrylamidopropyl)trimethylammonium chloride, 2-acrylamido-2-methyl-1-propanesulfonic acid and aminopropylmethacrylamide. 
     
     
         71 . The method of  claim 69  wherein two of said monofunctional monomers are present in the ratio of about 1 to about 5 by weight. 
     
     
         72 . The method of  claim 69  wherein two of said monofunctional monomers are present in the ratio of about 1 to about 2 by weight. 
     
     
         73 . The method of  claim 69  wherein the total amount of said monofunctional monomers present is from about 0.5% to about 20% by weight. 
     
     
         74 . The method of  claim 69  wherein the total amount of said monofunctional monomers present is from about 2% to about 10% by weight. 
     
     
         75 . The method of  claim 69  wherein the total amount of said monofunctional monomers present is from about 4% to about 8% by weight. 
     
     
         76 . The method of  claim 69  wherein the ratio of the total amount of monofunctional monomers to polyfunctional monomer is about 2 to about 10 by weight. 
     
     
         77 . The method of  claim 69  wherein the ratio of the total amount of monofunctional monomers to polyfunctional monomer is about 2 to about 6 by weight. 
     
     
         78 . The method of  claim 69  wherein the heat stable biomolecule resistant surface is hydrophilic. 
     
     
         79 . The membrane of  claim 69 , wherein said membrane has a biomolecule binding of less than about 30 microgram per square centimeter measured by the IgG binding test. 
     
     
         80 . The membrane of  claim 69 , wherein the membrane has TOC extractables of less than about 1 microgram of extractable matter per square centimeter of membrane as measured by the TOC Extractables test. 
     
     
         81 . The membrane of  claim 69 , wherein the membrane has TOC extractables of less than about 2 micrograms of extractable matter per square centimeter of membrane as measured by the NVR Extractables test. 
     
     
         82 . The membrane of  claim 69 , wherein the membrane has caustic resistance of less than about 1.3 as measured by the Flow Time Measurement test. 
     
     
         83 . The method of  claim 69  wherein the sizes of the pores of the porous membrane substrate prior to performing steps (a) through (e) are substantially equivalent to the sizes of said pores after performing steps (a) through (e). 
     
     
         84 . The method of  claim 69  wherein said porous membrane substrate is a microporous membrane. 
     
     
         85 . The method of  claim 84  wherein said microporous membrane is formed from one or more of the group consisting of aromatic sulfone polymers, polytetrafluoroethylene, perfluorinated thermoplastic polymers, polyolefin polymers, ultrahigh molecular weight polyethylene, and polyvinylidene difluoride. 
     
     
         86 . The method of  claim 69 , wherein one of said at least two monofunctional monomers is dimethylacrylamide. 
     
     
         87 . The method of  claim 69 , wherein one of said at least two monofunctional monomers is diacetone acrylamide.