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 selfhealing epoxy (EP) coating activated by sunlight with photothermal conversion and UV resistance performances is developed by incorporating benzotriazole (BTA) and polydopamine-modified cerium oxide (mCeO2) loaded poly (epsilon-caprolactone) (PCL) microspheres. BTA@PCL/mCeO2 microspheres can not only endow composite coating with excellent anti-corrosion capability (|Z|0.01Hz value of 1.97 x 109 Omega center dot cm2) but also achieve efficient photothermal self-healing under sunlight irradiation of 200 mW/cm2 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/mCeO2 microspheres, the composite coatings still maintain stabilized impedance modulus values (3.62 x 108 Omega & sdot;cm2) after 120 h of UV exposure. Therefore, this work offers a promising candidate for long-term corrosion protection under harsh application conditions.