Patent ID: 7262253
Filing Date: 2007-08-28
Classification: C08F,C08G,C08L

Abstract:
1. A process for preparing diblock and triblock copolymers comprising the steps of: (a) performing radical polymerization of N-vinyl-2-pyrrolidone in the presence of a radical initiator, a chain transfer agent and an alcoholic solvent to form hydroxy-terminated poly (N-vinylpyrrolidone) wherein said hydroxy-terminated poly (N-vinylpyrrolidone) is isolated by dissolution and precipitation; and (b) performing ionic polymerization of monomers or comonomers selected from the group consisting of 3,6-dimethyl-1,4-dioxane-2,5-dione, ε-caprolactone, γ-caprolactone poly(D,L-lactide), poly(D-lactide), poly (L-lactide), poly(ε-caprolactone) and poly (γ-caprolactone) in the presence of a catalyst and a macroinitiator wherein said macroinitiator is the hydroxy-terminated poly (N-vinylpyrrolidone) formed in step (a)thereby preparing said diblock and triblock copolymers, wherein said copolymers self-assemble in polymeric micelles or stabilized nanoparticles in aqueous solution.