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Method for making a porous polymeric material

  • US 8,697,108 B2
  • Filed: 09/23/2004
  • Issued: 04/15/2014
  • Est. Priority Date: 05/13/1994
  • Status: Expired due to Fees
First Claim
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1. A process for making a porous polymeric material, comprising the steps of:

  • (a) providing a polymer consisting essentially of polyurethane comprising a siloxane moiety or a carbonate moiety;

    (b) identifying a liquid swelling agent that does not dissolve the polymer in solid form, but instead merely swells the solid polymer, said liquid swelling agent being selected from the group consisting of p-dioxane and dimethyl sulfoxide;

    (c) providing at least sufficient tetrahydrofuran to said polymer as to dissolve the polymer in the tetrahydrofuran to form a solution;

    (d) adding a quantity of the liquid swelling agent to the solution, whereupon the entire volume of solution begins to increase its viscosity without forming a separation of solid and liquid phases;

    (e) continuing to add the liquid swelling agent to the solution until the entire volume of solution transforms to gel, the gelation being without visible separation of a solid phase and a liquid phase;

    (f) shape-forming the gel; and

    (g) removing the tetrahydrofuran and liquid swelling agent from the gel.

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