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“A2 + CBn” Approach to Hyperbranched Polymers with Alternating Ureido and Urethano Units

Various hyperbranched polymers with alternating ureido and urethano units in their backbones were synthesized by direct polycondensation of diisocyanates (A 2 -type monomers) with compounds containing one amino group and multihydroxyl groups (CB n -type monomers). Because of the commercial availability of the monomers and the simplicity of the synthesis process, hyperbranched poly(urea-urethane) materials can be large scale accessed. The reaction between an A group and a C group is much faster than that between an A group and a B group, resulting in the formation of AB n -type intermediates in the initial stage of the reaction. Further self-polycondensation of the intermediates gives hyperbranched macromolecules. The influence of reaction conditions such as temperature and concentration on the polymerization was discussed in detail.