Patent ID: 6268449
Filing Date: 2001-07-31
Classification: C08F

Abstract:
A process for preparing a temperature-responsive, water-soluble polymer by precipitation polymerization, wherein the polymer is soluble in water at a temperature below a specific temperature and is insoluble in water above the specific temperature, the process comprising:forming a reaction mixture comprising water, a chain transfer agent, and a monomer capable of being polymerized to form the temperature-responsive polymer;heating the reaction mixture to a temperature above the specific temperature at which the temperature-responsive, water-soluble polymer to be formed is soluble, wherein the temperature is less than about 100.degree. C.; andadding a reaction catalyst to the reaction mixture to polymerize the monomer and form the temperature-responsive polymer;wherein the polymer precipitates out of the reaction mixture as it is formed;wherein the chain transfer agent is isopropanol, the monomer is N-isopropylacrylamide, and the reaction catalyst is potassium persulfate;wherein the polymer exhibits an intrinsic viscosity that is less than about 50 percent of the intrinsic viscosity exhibited by an otherwise substantially identical temperature-responsive polymer that is prepared without using the chain transfer agent;and wherein the intrinsic viscosities are measured in water at room temperature.