Abstract: Hyperbranched polymer with alternating ureido and urethano units was prepared by direct polymerizarion of isophorone diisocyanate(IPDI, A₂) with diethanolamine(DEOA, CB₂) in the absence of catalyst. In the reaction, one isocyanato group of IPDI reacts fast with amino group of DEOA, generating an intermediate with one isocyanato group and two hydroxyl groups. Now the intermediate formed is a new kind of AB₂ type monomer. Further self-condensation of this AB₂ species leads to hyperbranched poly(urea-urethane). The reaction mechanism was characterized with in situ FTIR. Temperature and concentration have great influence on the polymerization process. When the feed ratio of IPDI to DEOA is equal to 1∶1, no gelation is observed if the reaction temperature within initial several hours is lower than 20 ℃. Cross-linking would occur if the reaction temperature during initial period is high. The degree of branching(DB) of the resulting hyperbranched poly(urea-urethane) is 46.5%-48.5%.

Key words: Hyperbranched poly(urea-urethane), Diisocyanate, Diethanolamine