Ultra-low-temperature self-healing polyurethane with enhanced strength and elongation based on dual synergetic crosslinking strategy

Ultra-low-temperature self-healing polyurethane is expected to be applied in the fields of protective coatings, electronic equipment, armaments, and biomedical materials owing to its longevity and durability in extreme environments. However, the contradiction between low-temperature self-healing and mechanical properties has not been resolved, and there are still limitations such as the insufficient low-temperature self-healing efficiency or poor strength and elongation. In this work, an ultra-low-temperature self-healing polyurethane with significantly enhanced strength and elongation was successfully prepared. The polyurethane had superior molecular chain mobility, even at −80 °C near the glass-transition temperature, and can achieve partial self-healing. At −40 °C, it had an elongation at break of 1501% and tensile strength of 8.02 MPa, as well as excellent self-healing properties; the self-healing efficiency based on the elongation and strength reached 78% and 81%, respectively. This shows that the contradiction between mechanical properties and low-temperature self-healing of polyurethane was successfully alleviated. The polyurethane material with excellent mechanical properties and ultra-low-temperature self-healing functionality is expected to enable a broad range of applications in extreme conditions.