Mussel‐Inspired Self‐Healing Waterborne Polyurethanes With Catechol–Fe 3+ Coordination and Dynamic Disulfide Bonds

ABSTRACT Conventional self‐healing waterborne polyurethanes (WPUs) often suffer from an intrinsic trade‐off between mechanical robustness and healing efficiency. To address this limitation, inspired by the hierarchical structure and dynamic interactions found in marine mussel byssus, a dual dynamic network WPU was synthesized via step‐growth polymerization by integrating dopamine‐derived catechol groups and aromatic disulfide bonds. Subsequently, was introduced to provide Fe 3+ species capable of forming additional reversible coordination interactions with oxygen‐containing groups in the polyurethane network, including catechol groups and potentially DMPA‐derived carboxylates. The combined presence of these reversible interactions may contribute to network rearrangement and energy dissipation during deformation, thereby improving mechanical performance while retaining self‐healing capability. Experimental results demonstrate that at an optimal content of 0.1 wt%, the DWPU‐‐0.1% film exhibited a tensile strength of 29.8 MPa, an elongation at break of 553.2%, and a toughness of 83.3 MJ m −3 . Furthermore, the damaged film recovered 98.2% of its original tensile strength after thermal healing at 60°C for 2 h. These results demonstrate that the combined incorporation of multiple reversible interactions provides a feasible strategy for achieving a favorable balance between mechanical performance and self‐healing capability under the investigated conditions.