Mussel-Inspired Self-Healing Waterborne Polyurethanes With Catechol–Fe3+ Coordination and Dynamic Disulfide Bonds

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, F e C l 3 FeCl 3 $$ {\mathrm{FeCl}}_3 $$ 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 F e C l 3 FeCl 3 $$ {\mathrm{FeCl}}_3 $$ content of 0.1 wt%, the DWPU- F e C l 3 FeCl 3 $$ {\mathrm{FeCl}}_3 $$ -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. Graphical A mussel-inspired waterborne polyurethane incorporating aromatic disulfide bonds and Fe 3+ –catechol coordination is developed to balance mechanical performance and self-healing capability. An optimal Fe 3+ content enhances strength, toughness, and energy dissipation while maintaining high healing efficiency, demonstrating the effectiveness of combining multiple reversible interactions within a dynamic polyurethane network.