Self‐Healing and Recyclable Waterborne Polyurethane With Ultra‐High Toughness Based on Dynamic Covalent and Hydrogen Bonds

ABSTRACT The implementation of self‐healing properties in waterborne polyurethane (WPU) materials plays a pivotal role in resource conservation and pollution mitigation. In this work, a strategy was devised to balance the self‐healing and mechanical properties of WPU by incorporating bis(hydroxyethyl) disulfide (HEDS), an aliphatic disulfide, as a chain extender. The synthesized WPU constructed a dynamic molecular network through dynamic disulfide bonds (SS). Meanwhile, a physical cross‐linked network was formed by dynamic hydrogen bonds from carbamate groups. The synergistic effect of the dual dynamic bonds significantly contributed to the remarkable self‐healing capability of WPU. Specifically, the optimal sample (SWPU‐15) not only exhibited a tensile strength of 33.42 MPa and toughness of 162.19 MJ/m 3 but also achieved a healing efficiency of 81.9% when heated at 80°C for 4 h. Profiting from the abundant dynamic bonds, the SWPU‐15 sample could be recycled through hot pressing or solvent treatment, with its tensile strength remaining above 20 MPa after recycling. This study provided a feasible approach for preparing environmentally friendly WPU with excellent performance and demonstrates promising prospects for potential applications.