Preparation of dynamic polyurethane networks with UV-triggered photothermal self-healing properties based on hydrogen and ion bonds for antibacterial applications

Abstract

• The building of Zn-dimethylglyoxime-polyurethane coordination complex provides a covalently cross-linked elastomer with triple dynamic bonds. • The self-healing behavior and mechanism of 3D micro-crack is investigated by molecular dynamics simulations. • The doping of copper on double-nut shaped zinc oxide generates more defects, preventing the recombination of photo-induced electron-hole pairs and generating more heat through lattice vibration. • The enhanced self-healing effect of UV-light-responsive polyurethane was due to the hybrid of Cu-doped ZnO, which provides coordination bonds and the photothermal effect. Photo-induced self-healing composites have attracted more and more attention as a kind of materials that can be controlled remotely and accurately in real time. Here, we report a strategy of a photo-responsive system based on hydrogen and ion bonds capable of performing self-healing process by ultraviolet wavelengths, which is covalently cross-linked zinc-dimethylglyoxime-polyurethane coordination network with triple dynamic bonds. The recombination of hydrogen bond and metal coordination bond produces effective healing performance. The self-healing behavior and temperature dependence of 3D micro-crack is investigated by molecular dynamics simulations to reveal the mechanism of self-healing at molecular level. Moreover, the hybrid of copper-doped zinc oxide not only provides metal coordination bonds to enhance the self-healing rate, but also enhances the photothermal effect and anti-bacterial properties of polyurethane. Importantly, doping of copper generates more defects and forms a space charge layer on the surface of zinc oxide. The defects could trap surface electrons and holes, preventing the recombination of photo-induced electron-hole pairs, generating more heat through lattice vibration. Therefore, under ultraviolet light irradiation, the polyurethane can reach 62.7°C for 60 s, and the scratches of the polyurethane can be healed within 30 min and fully healed within 1 h.