Rational design of photothermally activated self-healing coating with UV resistance towards smart corrosion protection

The self-healing coating loaded with corrosion inhibitors has been proven to protect metals against harsh corrosive environments . However, the complex stimulation methods and inability to resist ultraviolet (UV) radiation greatly limit the further application of these coatings in intelligent corrosion protection . In this work, a self-healing epoxy (EP) coating activated by sunlight with photothermal conversion and UV resistance performances is developed by incorporating benzotriazole (BTA) and polydopamine-modified cerium oxide (mCeO 2 ) loaded poly (ε-caprolactone) (PCL) microspheres . BTA@PCL/mCeO 2 microspheres can not only endow composite coating with excellent anti-corrosion capability (|Z| 0.01Hz value of 1.97 × 10 9  Ω∙cm 2 ) but also achieve efficient photothermal self-healing under sunlight irradiation of 200 mW/cm 2 for 10 min. Based on the results of scanning electrochemical microscopy , the healing efficiency of composite coatings on scratched areas reaches 92.13 % after immersion for 24 h, which is much higher than 5.27 % of pure EP coatings. Profited from the UV absorption and free radical scavenging ability of BTA@PCL/mCeO 2 microspheres, the composite coatings still maintain stabilized impedance modulus values (3.62 × 10 8  Ω·cm 2 ) after 120 h of UV exposure. Therefore, this work offers a promising candidate for long-term corrosion protection under harsh application conditions.