Urethanes as reversible covalent moieties in self-healing polymers

For the first time, reversible covalent urethane units are used for the design of new self-healing polymers. For this purpose, an electron-poor diol was synthesized and utilized as crosslinker to create a dynamic polymer network. Therefore, the diol, butyl methacrylate as well as 2-isocyanato ethyl methacrylate are intermixed and photo-polymerized in a bone-shaped PTFE mold. The resulting test specimens are characterized by DSC, TGA and DMTA and the self-healing behavior is studied using tensile tests. Thereby, healing efficiencies of up to 85% could be reached while the material exhibits good mechanical properties with high E-moduli. Additionally, the self-healing mechanism, which is based on exchange reactions of the reversible urethane moieties, is investigated by Raman as well as temperature dependent IR measurements.