Smart self-healing coating with multiple synergistic effects based on ZIF-11 for corrosion protection of carbon steel

Adding fillers with corrosion inhibitors to organic coatings is an effective and common strategy for enhancing active and passive corrosion protection of coatings. However, most of the self-healing coatings only can offer limited corrosion protection because of a single corrosion inhibitor loaded in fillers. Herein, a smart self-healing coating system (ZIF-11-PAACe-EP) consisting of epoxy coating containing ZIF-11 encapsulated by cerium polyacrylate (PAACe) polymer (ZIF-11-PAACe) was designed. The anti-corrosion and self-healing properties of ZIF-11-PAACe-EP were evaluated by electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The EIS results show that the impedance modulus at the low frequency (|Z|0.01 Hz) of ZIF-11-PAACe-EP can continuously increase with time and reach 4.01 × 1010 Ω·cm2 after 60 days of immersion. ZIF-11-PAACe-EP can provide long-term corrosion protection for steel, which is attributed to its excellent self-healing abilities conferred by multiple synergistic effects of benzimidazole (BIM), Zn2+ and Ce3+ ions released from ZIF-11-PAACe based on pH-stimuli response. The design of the pH-responsive self-healing coating system with multiple synergistic effects will provide a new strategy for the fabrication of highly efficient anti-corrosion coating.