Robust damage warning and healing tracing strategy for anticorrosion coatings on magnesium alloy AZ31enabled by polydopamine fluorophores

Polymeric coatings are susceptible to microdefects that are difficult to detect thus leading to premature failure of metallic components or even catastrophic accidents. Although obtaining considerable progress in damage healing and detecting, it is still challenging for anticorrosion coating to realize warning the damage generation and tracing the healing process simultaneously. This article validates a robust strategy based on damage-induced fluorescence enhancement effect to visualize dynamic damage-healing processes in anticorrosion coatings on magnesium alloy AZ31. Through embedding fluorescent polydopamine nanoparticles into thermo-responsive epoxy resin, immediate fluorescence was intensified at coating damages. Localized electrochemical impedance and salt spray results proved that the prepared coating possessed pronounced healing and corrosion protection capability with near-infrared irradiation. Notably, the healing behavior can be traced and visualized based on the decrease in fluorescence intensity. This work opens a new avenue to monitor the failure and self-healing mechanism of anticorrosion coatings, providing guideline for engineering of next generation smart protection materials.