Porous membrane formed from interpenetrating polymer network having hydrophilic surface
First Claim
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1. The process for forming a porous membrane having a water wettable surface formed of an interpenetrating polymer network of a semi-crystalline hydrophobic polymer, and a cross-linked hydrophilic second polymer which comprises:
- (a) forming a solution of said hydrophobic polymer, a monomeric composition precursor of said hydrophilic polymer, a crosslinking agent for said monomeric composition and a photoinitiator for said monomer composition,(b) casting said solution on a substrate,(c) exposing said cast solution to ultraviolet radiation to polymerize and cross-link said monomeric composition,(d) coagulating said cast solution,(e) removing solvent from said coagulated solution to form a dried porous membrane, and(f) annealing said dried porous membrane to render the surface of said membrane water wettable.
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Abstract
A porous membrane is formed from an interpenetrating polymer network of a hydrophobic polymer and a polymerized and crosslinked hydrophilic monomeric composition. A solution of the polymer and monomeric composition is cast, exposed to ultraviolet radiation, coagulated and dried. The resulting dried membrane is annealed in order to render its surface hydrophilic.
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Citations
7 Claims
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1. The process for forming a porous membrane having a water wettable surface formed of an interpenetrating polymer network of a semi-crystalline hydrophobic polymer, and a cross-linked hydrophilic second polymer which comprises:
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(a) forming a solution of said hydrophobic polymer, a monomeric composition precursor of said hydrophilic polymer, a crosslinking agent for said monomeric composition and a photoinitiator for said monomer composition, (b) casting said solution on a substrate, (c) exposing said cast solution to ultraviolet radiation to polymerize and cross-link said monomeric composition, (d) coagulating said cast solution, (e) removing solvent from said coagulated solution to form a dried porous membrane, and (f) annealing said dried porous membrane to render the surface of said membrane water wettable.
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2. The process of claim 1 wherein said dried porous membrane is restrained to prevent shrinkage during annealing.
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3. The process of any one of claims 1 or 2 wherein said annealing step is conducted at a temperature between about 130°
- C. and about 160°
C. for a time between about 30 minutes and 60 minutes.
- C. and about 160°
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4. The process of any one of claims 1 or 2 wherein said hydrophobic polymer is a fluorinated hydrocarbon polymer.
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5. The process of any one of claims 1 or 2 wherein said hydrophobic polymer is a polyvinylidene fluoride.
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6. The process of any one of claims 1 or 2 wherein said monomeric composition is an hydroxyalkyl acrylate.
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7. The process of any one of claims 1 or 2 wherein said porous membrane has a maximum pore size between about 0.01 and 0.1 micron and has an isopropyl alcohol bubble point of between about 40 psi and 140 psi, a water flux of above about 3500 gallons per foot per day at 25 psi for a membrane having a bubble point of about 40 psi, a water flux of above about 1000 gallons per foot per day at 25 psi for a membrane having a bubble point of about 80 psi and a water flux of above about 1000 gallons per foot per day at 25 psi for a membrane having a bubble point of about 140 psi.
Specification