Hierarchically self-reporting and self-healing photothermal responsive coatings towards smart corrosion protection

For conventional anticorrosion coatings, it is challenging to simultaneously report and repair two failure stages involving coating damage and interfacial metal corrosion. Thus, it leads to difficulties for continuous detection of coating service status, and may result in premature failure of metal-based equipment. Herein, we present a novel photothermal responsive composite epoxy system with hierarchical damage reporting and healing capabilities, which is enabled by mesoporous polydopamine nano-spheres loaded with crystal violet lactone (CVL) and phenanthroline (Phen). In our design, the coating damage is indicated by the immediately intensified fluorescent and can be rapidly closed in 90 s of NIR irradiation. Furthermore, the on-demand released corrosion probes (Phen) are able to chelate with Fe2+ ions generated from localized corrosion, producing distinct visual red color to report corrosion pits and resisting corrosion developing process. The proposed smart coatings provide a concept for achieving hierarchically self-reporting and self-repairing function of general coating defects and substrate corrosion, thus having certain potential to be applied in smart anticorrosion applications.