Preparation of AB2 Monomers and the Corresponding Hyperbranched Polyureas in a One-Pot Procedure

Novel AB2 monomers and corresponding hyperbranched polyureas are prepared in a one-pot process. AB2 monomers are synthesized by a highly selective reaction of carbonyl biscaprolactam (CBC) with triamines comprising one secondary and two primary amino groups. Only the primary amines react with CBC, yielding blocked isocyanates. On heating, self-condensation of the obtained monomer solution takes place, yielding polymers with Mn up to 11 000 Da. Mark-Houwink exponents of 0.3 and branching frequencies of 0.3 demonstrate the hyperbranched topology. Each polymer molecule comprises one secondary amino group in the focal point and numerous active blocked isocyanates located at the end of the polymer branches. The polymers are fully characterized by means of 1H NMR, 13C NMR, MALDI-TOF, SEC, and DSC