A Tough Metal‐Coordinated Elastomer: A Fatigue‐Resistant, Notch‐Insensitive Material with an Excellent Self‐Healing Capacity

Abstract Self‐healing materials can prolong device life, but their relatively weak mechanical strength limits their applications. Introducing tunable metal‐ligand interactions into self‐healing systems can improve their mechanical strength. However, applying this concept to solid elastomers is a challenge. To address this need, polyurethane‐containing metal complexes were fabricated by introduction of a pyridine‐containing ligand into polyurethane, and subsequent coordination with Fe 2+ . The strong reversible coordination bond provides mechanical strength and self‐healing ability. By optimizing the monomer ratio and Fe 2+ content, the resulting complex possesses a very high tensile strength of 4.6 MPa at strain of around 498 % and a high Young's modulus (3.2 MPa). Importantly, the metal complex exhibits an extremely high self‐healing efficiency of approximately 96 % of tensile strength at room temperature and around 30 % at 5 °C. The complex is notch‐insensitive and the fracture energy is 76186 J/m 2 , which is among the highest reported values for self‐healing systems.