Synthesis and characterization of poly(urethane‐ co ‐imidine)s having pendent phenyl and benzylidene groups using bis phthalides, bis lactones and blocked polyurethane prepolymers

Poly(urethane‐ co ‐imidine)s were prepared using amine blocked polyurethane (PU) prepolymer. The PU prepolymer was prepared by the reaction of poly(propylene glycol) (PPG 2000 ) and 2,4‐tolylene diisocyanate (TDI) and end capped with N ‐methyl aniline. The PU prepolymer was then reacted with bis phthalides and bis lactones, until the evolution of carbon dioxide ceased. Polymerization reactions with bis pthalides and bis lactone took more time than with dianhydrides. Polymers were characterized by FTIR, GPC, TG and DSC analyses. Molecular weights of the poly(urethane‐ co ‐imidine)s were found to be lower than that of poly(urethane‐ co ‐imide)s. Compared to poly(urethane‐ co ‐imide)s all poly(urethane‐ co ‐imidine)s showed high glass transition temperature and crystallization peak in DSC. The thermal stability of the polyurethanes was found to increase with the introduction of imidine component. © 2001 Society of Chemical Industry