Adaptable Strategy to Fabricate Self-Healable and Reprocessable Poly(thiourethane-urethane) Elastomers via Reversible Thiol- Isocyanate Click Chemistry

Currently, a variety of elastomers with a self-healing capacity and reprocessability have been developed by dynamic chemistry to extend the service life, increase the reliability of polymeric materials, and reduce the waste. However, it is still a large challenge to seek an appropriate dynamic interaction that may perfectly match the general performance of the target polymeric materials such as polyurethane. Herein, we report a poly(thiourethane-urethane) (PTUU-N-x) elastomer containing dynamic thiourethane bonds prepared via a thiol-isocyanate click reaction, which is stable at room temperature, healable at moderate temperature, and reprocessable at high temperature. Importantly, it exhibits a mechanical strength similar to the polyurethane because of a very similar structure. The dynamic feature of PTUU-N-x is demonstrated theoretically and experimentally to originate from the exchange of thiourethane bonds via the reversible generation of isocyanates and thiols. Most importantly, the thiourethane bond possesses a much lower bond dissociation energy than the urethane bond, which not only makes PTUU-N-x elastomers easier to be reprocessed but also endows them with a desirable self-healing ability under moderate conditions. In addition, the optimized sample PTUU-N-2 is utilized to fabricate a conductive device by coating Ag glue on the elastomer surface and inserting the coated elastomer into a circuit, which displays a high self-healing efficiency, as the material recovers to its original mechanical property and conductivity. Therefore, these results not only indicate that the PTUU-N-x elastomers have considerable potential for applications in intelligent electronic devices but also provide new ideas for developing new self-healing materials by applying the adaptable dynamic bond to the target polymers.