Synergistic cross-linking strategy with oxime-carbamate and hydrogen bonding arrays for excellent damage self-healing and reprocess ability of thermoset polyurethanes

Thermoset polyurethanes face significant deterioration of physical properties after damage self-healing or reprocessing. It is still a great challenge to design the structure of polyurethanes to realize damage self-healing and reprocess ability under mild conditions. In this work, a series of double-crosslinked networked polyurethanes with different crosslinking densities were synthesized by designing a synergistic crosslinking strategy of oxime-carbamate bonding and hydrogen bonding arrays. By regulating the density of the crosslinked network and the content of strong and weak hydrogen bonds, the tensile strength of the polyurethanes was increased from 13.1 to 24.3 MPa, and the toughness was increased from 66.5 to 129.2 MJ/m 3 . Meanwhile, the synergistic effect of the oxime-carbamate with low activation energy and hydrogen bonding arrays enabled the polyurethanes to have an excellent self-healing (97 %) and reprocessing. The polyurethanes could be rapidly reprocessed after only 5 min of hot pressing at 120 °C by virtue of the thermal response of the dual network. More importantly, the tensile strength retention rate can still maintain more than 96 % after reprocessing. Finally, we propose the concept of a wearable device that can intelligently detect changes in resistance values during human movement. Therefore, this work provides a new idea for the preparation of polyurethanes with excellent damage self-healing and reprocessing, which is expected to expand its application.