Intrinsically self-healing and stretchy poly(urethane-urea) elastomer based on dynamic urea bonds and thiol-ene click reaction

The development of self-healing elastomers with superior physical properties is a challenging task. Herein, we present a design concept for a self-healing, highly stretchable, and robust poly(urethane–urea) elastomer prepared via a thiol-ene click reaction by a facile one-pot in situ photopolymerization method. The objective of the utilized approach is to incorporate weak noncovalent H-bonds, dynamic covalent urea bonds, and products of a thiol-ene click reaction into a polymeric backbone. This study also applies polytetramethylene ether glycol domains as soft segments to facilitate the polymeric chain diffusion and dynamic exchange reaction. Owing to these unique molecular characteristics, the resultant elastomer possesses a uniform structure and versatile properties, such as high stretchability corresponding to a maximum strain of 464%, ultimate tensile strength of 10.9 MPa, self-recoverability, high self-healing efficiency of 99%, high recyclability, and good weldability. Upon rupture, the as-prepared elastomer completely restores its original mechanical properties after heating to 80 °C for 5 h. The dynamic reversibility of the elastomer is evidenced by stress relaxation analysis and rheological testing. In addition, it can be effectively encapsulated and potentially used for fabricating self-healing stretchable conductive devices.