An ultrafast and highly efficient self-healing coating with dynamic-covalent boroxine bonds for corrosion protection

 

Abstract:

This study developed an ultrafast self-healing epoxy coating based on dynamic covalent boroxine bonds for metal corrosion protection. By incorporating polydimethylsiloxane with dynamic boroxine bonds (PDMS-Boro) and flexible chain segment crosslinker D400 into the epoxy network, an intelligent coating system with room-temperature chain segment mobility and water molecule-triggered self-healing properties was constructed. The results showed that the coating could autonomously close micrometer-level scratches within 40 s, and its repair mechanism originated from the reversible dissociation and reconstruction process of the boroxine structure mediated by water molecules.

Electrochemical impedance spectroscopy (EIS) indicated that the low-frequency impedance modulus of the repaired coating remained at the 108 Ω·cm2 level throughout a 30 days immersion period, and the charge transfer resistance was nearly five orders of magnitude higher than that of the pure epoxy coating, demonstrating excellent corrosion resistance. Salt spray corrosion tests combined with scanning vibrating electrode technique (SVET) further confirmed that the coating could rapidly suppress local anodic current density after damage, effectively restoring its barrier protection function. 

This study provides a new material design strategy for developing intelligent protective coatings with both efficient self-healing ability and long-term anti-corrosion performance.

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