CONICET | Buscador de Institutos y Recursos Humanos

Vitrimers are a new class of polymeric materials with very attractive properties since they can be reworked to any shape while being at the same time permanently cross-linked. Inspired by the principle of vinylogy, we explored transamination of vinylogous urethanes as exchange reaction for vitrimers. First, a kinetic study on model compounds revealed the occurrence of transamination of vinylogous urethanes in a good temperature window without side reactions. Next, poly(vinylogous urethane) networks with a storage modulus of ~2.4 GPa and a glass transition temperature above 80°C were prepared by bulk polymerization of cyclohexane dimethanol bisacetoacetate, m-xylylene diamine and tris(2-aminoethyl)amine. The vitrimer nature of these networks was examined by solubility, stress-relaxation and creep experiments. Relaxation times as short as 85 s at 170°C were observed without using any catalyst. In addition, the networks were recyclable up to four times by consecutive grinding/compression molding cycles without significant mechanical or chemical degradation.