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

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 wave-lengths,which is covalently cross-linked zinc-dimethylglyoxime-polyurethane coordination network with triple dynamic bonds.The recombination of hydrogen bond and metal coordination bond produces ef-fective 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 molecu-lar 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 recom-bination 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.

High efficiency photothermal cyclic self-healing antibacterial coating based on in-situ dual-functional BiOI@Bi_(2)S_(3)

Although extremely challenging,it is highly desirable to develop self-healing materials that exhibit high efficiency under environmental conditions for marine protection applications.In this work,polyurethane elastomers with hydrogen bond and dimethylglyoxime-urethane(DOU)coordination complex were combined with in-situ dual-functional BiOI@Bi_(2)S_(3) to synthesize high-efficiency photothermal cyclic self-healing antibacterial coating.The photothermal efficiency of BiOI@Bi_(2)S_(3) is improved by 38% through interfacial regulation.BiOI@Bi_(2)S_(3)/PU rapidly rises by 50.2℃ within 300 s under near-infrared(NIR)light,which can trigger the hydrogen bond of polyurethane coating and recover the barrier properties of the coating through self-healing.Density functional theory was used to simulate and analyze the generation of multiple electron transfer paths after the vulcanization of BiOI,which improves the interfacial mobility of photogenerated carriers and generates more heat.Importantly,molecular dynamics verified the self-healing mechanism of hydrogen bond and the photothermal lifting mechanism of the coating.After 5th scratches and self-healing cycle tests,the coating has a self-healing efficiency of more than 80%,which can ensure the self-healing and anticorrosion protection performance of the coating for multiple cycles.The photocatalytic and photothermal properties of BiOI@Bi_(2)S_(3) enhance the antibacterial rate of the coating up to 99%.This work provides heuristic perspectives for the design of coatings with anti-corrosion,antibacterial and self-healing properties.