A rapid room-temperature self-healing, antibacterial, photoluminescent waterborne polyurethane coating with excellent mechanical properties based on double dynamic cross-linked network used for leather finishing

Waterborne polyurethane that integrates fast room-temperature self-healable ability, high mechanical properties, antibacterial activity, and photoluminescence features is highly desirable but challenging. Herein, a novel waterborne polyurethane (ZIWPU) is synthesized with the double dynamic cross-linked networks of multiple hydrogen bonds formed by asymmetric polyurea structure and Zn2+-carboxylate coordination bonds. Profiting from the synergistic effects of double dynamic cross-linked networks, the optimized ZIWPU2 film exhibits excellent mechanical properties (tensile strength of 34.36 MPa and toughness of 107.21 MJ/m3) and rapid room-temperature self-healing ability (healing efficiency > 85 % within 10 h) with the assistant of trace alcohol, which is superior to those of the most of currently reported room-temperature self-healing waterborne polyurethane. In addition, owing to the existence of Zn2+, ZIWPU2 is simultaneously integrated with the outstanding antibacterial ability (antibacterial rate>96 %). Especially, the carbon dots (CDs) are introduced into ZIWPU2 to give it an excellent photoluminescence function that can be used for anti-counterfeiting and crack diagnosis. Finally, this versatile WPU material is successfully applied to leather finishing.