Room-temperature self-healing polyurethanes with high mechanical strength and superior toughness for sensor application

It remains enormous challenges to balance the conflict between high strength and toughness mechanical properties and excellent room-temperature self-healing abilities of polyurethane elastomers. In this work, we report a recyclable room-temperature self-healing polyurethane elastomer with excellent mechanical properties. The prepared polyurethane elastomer (PU-DA-Zn 0.50 ) exhibits high tensile strength of 15.33 MPa, high toughness of 76.77 MJ m −3 , and high elongation at break of 1604.46% by introducing isophorone diamine (IPDA), 1-(3-aminopropyl) imidazole (IMZ) and zinc ions into polymer system to form a dynamic double-cross-linked structure (hydrogen bonds and Zn 2+ -imidazole coordination bonds). In addition, the tensile strength of fractured polyurethane can reach more than 80% of the original sample after 48 h of self-healing at room temperature without external stimuli, which is attributed to the kinetics of rapid exchange of Zn 2+ -imidazole coordination bonds at room temperature. It is worth noting that the balance between excellent mechanical properties and outstanding room-temperature self-healing ability can be optimized by adjusting the Zn 2+ -imidazole coordination bond density in the system. Moreover, the dynamic nature of the double-cross-linking network endows polyurethane with favorable recyclability. The above remarkable comprehensive performances reveal a great potential of PU-DA-Zn x elastomer in the fields of wearable flexible electronic devices such as bionic skin, human motion monitoring, and soft robots.