Mechanically robust and fast room-temperature self-healing waterborne polyurethane constructed by coordination bond and hydrogen bond with antibacterial and photoluminescence functions

It is still a great challenge to synthesize waterborne polyurethane (WPU) with excellent mechanical performance and fast room-temperature self-healing ability because of the mutually exclusive nature of these properties. Herein, a room-temperature self-healing waterborne polyurethane based on Zn2+-carboxyl coordination bond and hydrogen bond was prepared by adding zinc ion buffer solution to WPU emulsion. Due to the synergistic effect of dynamic coordination bonds and hydrogen bonds, the optimized sample (WPU-Zn-3) exhibited excellent mechanical properties (a tensile strength of 7.26 MPa, a elongation at break of 855 % and an exceptional toughness of 26.76 MJ/m3) and fast room-temperature self-healing capacity under ethanol induction (a high healing efficiency of 88 % within 4 h), showing a good balance between fast room temperature healing ability and excellent mechanical properties. Interestingly, this method also works for nickel ions but not for iron and aluminum ions. Furthermore, compared with zinc chloride and zinc nitrate, the waterborne polyurethane containing zinc acetate showed the best comprehensive performance. Due to the presence of zinc ions, the sterilization rates of WPU-Zn-3 film samples against Escherichia coli and Staphylococcus were 97.1 % and 97.8 %, respectively. Specially, we introduced graphene quantum dots into the waterborne polyurethanes to construct photoluminescence films and demonstrated their potential applications prospect in the fields of information encryption and anti-counterfeiting. This work broadens the avenue for fabricating room-temperature self-healing and multifunctional waterborne polyurethanes.