Constructing active/passive binary self-healing mesoporous SiO2/PDMS coating with superior anti-corrosion performance

• Mesoporous SiO 2 loading corrosion inhibitor was incorporated into PDMS resin. • Self-healing and anti-corrosion performance were affected by the structural size of mesoporous SiO 2 . • The active/passive binary self-healing function was constructed for PSB-PDMS coatings. • Mechanisms for self-healing and corrosion resistance of PSB-PDMS coatings were elucidated. Organic coatings are prone to damage during service life in severe marine environments, thereby reducing or even losing their corrosion protection performance. The development of self-healing capability is crucial for extending the service life of organic coatings and ensuring long-lasting anti-corrosion performance. However, an individual passive or active self-healing strategy is insufficient to meet practical application demands. Herein, high-efficiency self-healing organic coatings were developed by integrating polydopamine (PDA) modified mesoporous SiO 2 loaded with benzotriazole (BTA) into polydimethylsiloxane (PDMS) resin (PSB-PDMS). Especially, the structural sizes of mesoporous SiO 2 were regulated to increase the loading capacity of corrosion inhibitors, optimizing extrinsic self-healing capability. For PSB-PDMS coating with mesoporous SiO 2 diameter of 80 nm (80PSB-PDMS), intrinsic self-healing efficiency reached as high as 96.81% for 12 h at room temperature. Besides, 80PSB-PDMS coating showed remarkable extrinsic self-healing performance, with impedance value at the center point increasing from 6.46 × 10 6 to 1.29 × 10 7 Ω cm 2 after 48 h in local electrochemical impedance spectroscopy (LEIS) test. In addition, after 60 d of immersion in 3.5 wt.% NaCl solution, 80PSB-PDMS coating maintained impedance modulus (| Z | 0.01 Hz ) value of 1.40 × 10 10 Ω cm 2 and open circuit potential value of 79.76 mV, exhibiting excellent corrosion resistance. The significant improvement of anti-corrosion ability was attributed to PSB nanoparticles, which promoted the recombination of dynamic reversible imine bond for intrinsic self-healing, and the release of BTA inhibited corrosion activity on Q235 to achieve extrinsic self-healing.