Bioinspired Time-Gradient Self-Healing Polyurethane/Epoxy Covalent Dynamic Networks Enhanced by GO/ZIF-8@Curcumin for...

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 × 10⁷ Ω·cm². This work offers an innovative paradigm for designing smart anticorrosion materials with integrated multifunctional protective capabilities.