A multifunctional zwitterionic-catechol polymer with dynamic Fe³⁺ coordination for self-healing and...

The long-term degradation of metallic structures in marine environments is mainly driven by chloride-induced corrosion and mechanical damage, which severely limits the durability of conventional polymer coatings. Herein, we report a multifunctional zwitterionic-catechol polymer coating (DZCP-Fe) that integrates hydration-mediated ion regulation, catechol interfacial adhesion, fluorinated barrier contribution, and dynamic Fe³⁺-catechol coordination. The coating exhibits a dense morphology, enhanced hydrophobicity, and strong adhesion. Electrochemical measurements show an impedance modulus up to ∼10⁹ Ω·cm² and a reduced corrosion current density in the 10^-8-10^-9 A·cm^-2 range. After scratching, DZCP-Fe achieves ∼90% crack closure within 24 h and ∼95% after 48 h, accompanied by substantial electrochemical recovery. Chloride-transport analysis shows a strongly suppressed effective diffusion coefficient (∼1.8 × 10^-15 m²·s^-1) and delayed ion penetration. These results demonstrate that the integrated hydration-adhesion-coordination strategy provides a robust route toward intrinsic self-healing and chloride-resistant marine anticorrosion coatings.