Mechanically robust and rapid room temperature self-healing waterborne polyurethane with three cross-linking networks based on triple dynamic bonds

Abstract

Although the research on self-healing waterborne polyurethane has been relatively in-depth, accomplishing rapid self-healing at room temperature along with superior mechanical properties remains a substantial challenge. Herein, a three cross-linking waterborne polyurethane (TeWPU-Zn-x) with triple dynamic bonds was prepared by adding ditellurium glycol, isophorone diamine, and trimethylolpropane to the backbone of the waterborne polyurethane, forming coordination bonds between carboxyl groups on the backbone of the waterborne polyurethane and zinc ions. Owing to the cooperative action of three distinct types of cross-linking and triple dynamic bonds, the film of TeWPU-Zn-3 exhibits outstanding mechanical features (the tensile strength, 40.58 MPa; the fracture toughness, 20.75 MJ m²; the elongation at break, 629.15%) and a remarkable self-healing efficiency (89.43% under a trace amount of ethanol induction and visible light irradiation at room temperature for a duration of 2 hours) simultaneously, demonstrating an exceptional balance between mechanical robustness and rapid room temperature self-healing, whose two characteristics outperforms those of the self-healing waterborne polyurethane reported so far. After reprocessing, the TeWPU-Zn-3 film cut into particles is basically restored to its original state and the reprocessing film can easily weigh 5 kg dumbbells. Moreover, due to the incorporation of zinc ions and ditellurium bonds, TeWPU-Zn-3 film is endowed with good antibacterial properties (S. aureus, 99.3%; E. coli, 97.5%). Importantly, when used as leather coating, TeWPU-Zn-3 also shows a protective self-healing ability on the leather. In summary, this work provides a promising avenue for the creation of waterborne polyurethane distinguished by their superior mechanical attributes, rapid room temperature self-healing, reprocess ability, and antibacterial properties.