Catalysis of poly(urethane imidine) copolymer formation from amine-blockedisocyanate and bisphthalide

The catalysis of imidine formation between an amine-blocked polyurethane pr epolymer and bisphthalide was studied with a series of metal alkoxides, phe noxides, and organotin compounds and tertiary amines. The carbon dioxide re leased during the reaction was followed for monitoring of the, reaction. Th e metal alkoxides and phenoxides catalyzed the imidine formation reaction b ut did not catalyze the deblocking reaction, whereas the organotin compound s and tertiary amines showed no catalytic activity in the reaction between isocyanate and phthalide, With tin catalysts, the imidine formation reactio n depended on the deblocking of the blocked prepolymer, but it was independ ent of deblocking with amine catalysts. The resultant poly(urethane imidine ) copolymers were characterized with Fourier transform infrared, H-1 NMR, C -13 NMR, gel permeation chromatography, and thermogravimetric analysis tech niques. The thermal stability of polyurethane increased significantly with the incorporation of imidine groups. (C) 2001 John Wiley & Sons, Inc.