A multifunctional zwitterionic–catechol polymer with dynamic Fe3+ coordination for self-healing and chloride-resistant marine anticorrosion coatings

A multifunctional zwitterionic–catechol polymer with dynamic Fe 3+ coordination is developed. • The coating achieves ultrahigh impedance (∼10 9  Ω·cm 2 ) and low corrosion current (∼10 −9 A·cm −2 ). • Rapid intrinsic self-healing enables ∼90% recovery at 24 h and ∼95% at 48 h. • Chloride diffusion is strongly suppressed (D ≈ 1.8 × 10 −15  m 2 ·s −1 ) with delayed penetration. • Synergistic mechanism integrates hydration layer, coordination bonding, and dynamic repair. 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 Fe 3+ -catechol coordination. The coating exhibits a dense morphology, enhanced hydrophobicity, and strong adhesion. Electrochemical measurements show an impedance modulus up to ∼10 9  Ω·cm 2 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  m 2 ·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. Download: Download high-res image (716KB) Download: Download full-size image