Novel intramolecular blocked isocyanates as stable one-component systems for poly(urea urethane)s

Several poly(urea urethane) oligomers 14a-e were prepared by polycondensation of N-(hydroxyalkyl)-2-oxo-1,3-diazepane-1-carboxamides 11a-e in bulk. The latter compounds were obtained under mild reaction conditions from a novel type of activated urethane/intramolecular blocked isocyanate 8 and a homologous series of amino alcohols. The influence of several catalysts (DABCO, Sn(octoate)2, and Bu2Mg) and reaction temperatures (100-150 °C) on molecular weight and microstructure of the polymers obtained was studied. The poly(urea urethane)s are semicrystalline materials and their melting points show the odd/even effect observed earlier for [n]-polyamides, [n]-polyurethanes, poly(ester amide)s, and poly(amide urethane)s. TGA analysis showed that the polymers are stable up to approximately 205-230 °C, the polymers with lower number of methylene groups in the amino alcohol decomposing at the lowest temperature.