Patent ID: 8114157
Filing Date: 2012-02-14
Classification: A61L,A61P

Abstract:
1. A method of making a shear-reversible polyurethane gel suitable for use in treatment of a medical or cosmetic condition, the method comprising the steps of: a) providing a polyisocyanate prepolymer, the prepolymer having a polyalkylene oxide backbone comprising one or more copolymers having on average about 65 to about 95 mole % ethylene oxide monomers and at least about 5 to about 35 mole % propylene oxide monomers, and less than about 5% of any other monomer, having an average functionality of greater than 2 active isocyanate groups per prepolymer molecule; b) providing a reaction-supporting solvent, selected from a solution consisting essentially of water, a solution consisting essentially of a dry non-aqueous water-miscible organic solvent in which the prepolymer will dissolve, and a mixture thereof; c) shearing said reaction-supporting solvent so as to provide a known rate of shear; and d) either e) allowing said prepolymer solution to finish reacting, thereby producing a reversibly gelling polyurethane (RGP) polymer solution; characterized in that the polyurethane solution gels when it is not sheared, and becomes fluid under shear.