Bioinspired Time‐Gradient Self‐Healing Polyurethane/Epoxy Covalent Dynamic Networks Enhanced by GO/ZIF‐8@Curcumin for Marine Protection

ABSTRACT Self‐healing anti‐corrosion systems based on either extrinsic or intrinsic triggers typically rely on a single repair mechanism, limiting their long‐term reliability in marine environments. Inspired by the self‐healing process of damaged skin tissue, we report an extrinsic‐intrinsic time‐sequential gradient cooperative self‐healing anti‐corrosion coating, fabricated by embedding curcumin‐loaded graphene oxide/ZIF‐8 (GO/ZIF‐8@CCM) nanosheets into a tough polyurethane/epoxy covalent dynamic network. By precisely regulating the distribution of disulfide and sextuple hydrogen bonds within the copolymer network, as well as the interfacial interactions between GO/ZIF‐8@CCM nanosheets and the resin matrix, multi‐mechanism synergistic toughening is realized. The resulting composite exhibits a high tensile strength of 23.29 MPa, exceptional stretchability of 542.97%, and outstanding self‐healing performance (76.48% at 25°C for 4 h). Notably, pH‐responsive nanosheets mediate the rapid release of curcumin for extrinsic repair, while the reconstruction of multiple dynamic bonds in the covalent network enables intrinsic self‐healing, operating in a time‐sequenced synergistic manner to achieve rapid and durable self‐healing. Even post‐damage and 20 days of immersion, the coating maintains an impedance modulus of 1.09 × 10 ⁷ Ω·cm ² . This work offers an innovative paradigm for designing smart anticorrosion materials with integrated multifunctional protective capabilities.