Highly microporous polymers and methods for producing and using the same

Abstract

The present invention provides microporous polymers and methods for producing and using the same. In particular, microporous polymers of the present invention are highly porous as indicated by a Gurley air permeability flow rate of about 4 seconds or less per mL of air flow per 25 micron of microporous polymer thickness per square inch.

1 . A microporous polymer comprising:
 (a) a first surface;   (b) a bulk matrix;   (c) a second surface; and   (d) a plurality of micro pores extending from said first surface through said bulk matrix and to said second surface thereby providing a fluid communication between said first and second surfaces,   
       wherein said microporous polymer has a Gurley air permeability flow rate of about 4 seconds or less per mL of air flow per 25 microns of microporous polymer thickness per square inch of surface area. 
     
     
         2 . The microporous polymer of  claim 1 , wherein the composition of said polymer comprises carbon and a group selected from hydrogen, halogen, oxygen, nitrogen, sulfur and a combination thereof. 
     
     
         3 . The microporous polymer of  claim 2 , wherein the composition of said polymer comprises halogen. 
     
     
         4 . The microporous polymer of  claim 3 , wherein the halogen is selected from the group consisting of chloride, fluoride, and a mixture thereof. 
     
     
         5 . The microporous polymer of  claim 2 , wherein said polymer is a semi crystalline polymer. 
     
     
         6 . The microporous polymer of  claim 2 , wherein said polymer is selected from the group consisting of:
 polyvinylidene fluoride, polyethylene, polyvinyl chloride, polyacrylonitrile, polymethyl methacrylate, polyvinylidene fluoride-hexafluoropropylene copolymer, ethylene-acrylic acid copolymer, ethylene-styrene copolymer, styrenebutadiene copolymer, styrene-isoprene copolymer, polydiene, polyalkane, polyacrylic, polyvinyl ether, polyvinyl alcohol, polyacetal, polyvinyl ketone, polyvinyl halide, polyvinyl nitril, polyvinyl ester, polystyrene, polyphenylene; polyoxide, polycarbonate, polyester, polyanhydride, polyurethane, polysulfonate, polysulfide, polysulfone, polyamide, and a mixture of two or more thereof.   
     
     
         7 . The microporous polymer of  claim 1 , wherein said polymer comprises polyvinylidene fluoride, polyvinyl chloride, polylvinylidene fluoridehexafluoropropylene copolymer or a mixture thereof. 
     
     
         8 . The microporous polymer of  claim 7 , wherein said polymer comprises at least about 80% polyvinylidene fluoride. 
     
     
         9 . The microporous polymer of  claim 1 , wherein the thickness of said polymer is about 5 mm or less. 
     
     
         10 . The microporous polymer of  claim 9 , wherein said polymer is a thin film. 
     
     
         11 . The microporous polymer of  claim 10 , wherein the thickness of said thin film is about 100 urn or less. 
     
     
         12 . The microporous polymer of  claim 10 , wherein the tensile strength of said thin film is at least about 100 psi. 
     
     
         13 . The microporous polymer of  claim 1 , wherein the average pore size is about 10 in or less. 
     
     
         14 . A method of producing a microporous polymer comprising:
 forming a layer of a polymer solution on a substrate, wherein the polymer solution comprises a liquid and a polymer material that is dissolved in the liquid, and wherein the liquid comprises a high surface tension liquid;
 producing a film of gelled polymer from the layer of polymer solution under conditions sufficient to provide a non-wetting, high surface tension solution within the layer of polymer solution; and 
   removing the liquid from the film of gelled polymer under conditions sufficient to produce the microporous polymer.   
     
     
         15 . The method of  claim 14 , wherein at least the first 50% of the liquid in the gelled polymer is removed at a temperature near or below the temperature of said gelled polymer forming step. 
     
     
         16 . The method of  claim 14 , wherein the solubility of the polymer material in the solution is about 25% v/v or less relative to the total volume of the liquid in the solution. 
     
     
         17 . The method of  claim 14 , wherein the liquid further comprises a low surface tension liquid, wherein said polymer material has a higher solubility in the low surface tension liquid than in the high surface tension liquid. 
     
     
         18 . The method of  claim 17 , wherein the low surface tension liquid has a higher vapor pressure than the higher surface tension liquid, thereby allowing the low surface tension liquid to evaporate at a faster rate than the high surface tension liquid from the polymer solution. 
     
     
         19 . The method of  claim 17 , wherein the ratio of the low surface tension liquid relative to the high surface tension liquid is about 99:1 v/v or less. 
     
     
         20 . The method of  claim 17 , wherein the void volume of the microporous polymer is substantially similar or higher to the relative volumetric ratio between the high surface tension liquid and the combined volume total of the polymer material and the high surface tension liquid. 
     
     
         21 . The method of  claim 17 , wherein the low surface tension liquid is a ketone, ester, ether, aldehyde, amine, amide, nitrile, cyanate, nitrite, nitrate, nitro- or nitroso-compound, thiol, sulfide, sulfonium, sulfate, sulfonyl compound, sulfinyl compound, thio compounds, or a mixture of two or more thereof. 
     
     
         22 . The method of  claim 21 , wherein the ketone is selected from the group consisting of acetone, methyl ethyl ketone, pentanone, hexanone, cyclic ketone, or a mixture of two or more thereof. 
     
     
         23 . The method of  claim 14 , wherein the high surface tension liquid is selected from the group consisting of:
 acetamide, acetophenone, adiponitrile, aniline, benzaldehyde, benzyl benzoate, benzonitrile, benzophenone, bromine, bromobenzene, tribromomethane, bromophenol, carbon disulfide, chloroacetic acid, chlorobenzene, chlorophenol, diethylaniline, diethylene glycol, dimethyl aniline, dimethyl phenyl pyrazolane, dimethyl sulfoxide, diphenylamine, ethyl aniline, ethylene bromide, ethylene glycol, formamide, formic acid, furfural, y-butyrolactone, glycerin, glycerol, methylaniline, methyl benzoate, methylene iodide, nitric acid, nitrobenzene, nitromethane, phenol, phosphorous tribromide, phosphorous tri-iodide, propylene glycol, pyridine, pyridazine, quinoline, sulfuric acid, tetrabromomethane, toluene, xylene, water, and a mixture of two or more thereof.   
     
     
         24 . The method of  claim 23 , wherein the high surface tension liquid is water. 
     
     
         25 . The method of  claim 14 , wherein the thickness of the polymer solution layer on the substrate is about 500 urn or less. 
     
     
         26 . The method of  claim 14 , wherein the substrate is a high surface free energy substrate. 
     
     
         27 . The method of  claim 26 , wherein the surface free energy of the substrate is at least about 40 dynes/cm at 25° C. 
     
     
         28 . The method of  claim 14 , wherein the film of gelled polymer is formed at a temperature of about 40° C. or less. 
     
     
         29 . The method of  claim 28 , wherein the liquid is removed from the gelled polymer at a temperature of about 30° C. or less. 
     
     
         30 . The method of  claim 14 , wherein the film of gelled polymer is formed at a temperature of about 5° C. or less relative to the dissolution and wetting temperature of the polymer. 
     
     
         31 . The method of  claim 14 , wherein the liquid is removed at a temperature of about 5° C. or less relative to the dissolution and wetting temperature of the polymer material. 
     
     
         32 . The method of  claim 14 , wherein the solubility of the polymer material in the liquid is about 10% v/v or less. 
     
     
         33 . The method of  claim 14  further comprising admixing the liquid and the polymer material to form the polymer solution, wherein the polymer solution is formed by heating the mixture, subjecting the mixture to high shear mixing, or a combination thereof. 
     
     
         34 . The method of  claim 14 , wherein the amount of polymer material dissolved in the polymer solution is at least near its saturation limit.