Patent ID: 6841646

Claim:
A process for preparing a polydimethyl siloxane-containing poly(urea-urethane) comprising the following steps: a) reacting polydimethyl siloxane having two terminal amine groups with an excessive amount of polyisocyanate in an organic solvent to form a solution containing poly(urea-urethane) prepolymer; and b) reacting the poly(urea-urethane) prepolymer from step a) with a chain extender in the presence of a catalyst to obtain a solution containing poly(urea-urethane); introducing the poly(urea-urethane)-containing solution into an open mold, and evaporating the organic solvent contained therein to form a poly(urea-urethane) film, wherein said mold is made of aluminum enabling a water contact angle of an air-contact face of the poly(urea-urethane) film being 20-30 degrees smaller than that of a mold-contact face of the poly(urea-urethane) film.