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

Abstract

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-Zn0.50) 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 Zn2+-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 Zn2+-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 Zn2+-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-Znx elastomer in the fields of wearable flexible electronic devices such as bionic skin, human motion monitoring, and soft robots.