Mechano-responsive hydrogen-bonding array of thermoplastic polyurethane elastomer captures both strength and self-healing

Self-repairable materials strive to emulate curable and resilient biological tissue; however, their performance is currently insufficient for commercialization purposes because mending and toughening are mutually exclusive. Herein, we report a carbonate-type thermoplastic polyurethane elastomer that self-heals at 35 degrees C and exhibits a tensile strength of 43MPa; this elastomer is as strong as the soles used in footwear. Distinctively, it has abundant carbonyl groups in soft-segments and is fully amorphous with negligible phase separation due to poor hard-segment stacking. It operates in dual mechano-responsive mode through a reversible disorder-to-order transition of its hydrogen-bonding array; it heals when static and toughens when dynamic. In static mode, non-crystalline hard segments promote the dynamic exchange of disordered carbonyl hydrogen-bonds for self-healing. The amorphous phase forms stiff crystals when stretched through a transition that orders inter-chain hydrogen bonding. The phase and strain fully return to the pre-stressed state after release to repeat the healing process. Self-healing materials strive to emulate curable and resilient biological tissue but their performance is often insufficient for commercial applications because self-healing and toughening are mutually exclusive properties. Here, the authors report a tough and strong carbonate-type thermoplastic polyurethane elastomer that self-heals at ambient temperature.

Automated summary

Self-repairable materials aim to replicate the curable and resilient properties of biological tissue, but often face challenges due to the conflicting properties of self-healing and toughening. In this study, authors introduced a tough and strong carbonate-type thermoplastic polyurethane elastomer that self-heals at ambient temperature.