A smart anticorrosive coating based on pH-sensitive microspheres fabricated via a facile method for protection of AA2024-T3

Self-healing coating has attracted much attention due to its intelligent response to stimulus and automatically recovery of coating properties. This work introduced a self-healing epoxy coating based on the Eudragit E100 (EE100) pH-sensitive microspheres loaded with 2-mercaptobenzothiazole (2-MBT) inhibitor. As a key component, the microspheres with a mean diameter of 2 μm were fabricated via a facile solvent-spray drying technique, and displayed good pH stimuli-response release behavior in acid (pH < 5) or alkaline (pH > 10) conditions. The self-healing coatings (SC) were prepared by incorporating 3 wt% microspheres in a water-borne epoxy coating. The resistance of coating in SC reached up to >1010 Ω·cm2 after 180 days of immersion in 3.5 wt% NaCl solution, which is 6 orders of magnitude higher than that of epoxy coating (EP). The SC displayed good self-healing effect, as the impedance modular of the SC significantly improved than the EP. The neutral salt spray tests also confirm the good long-term anti-corrosion performance of the SC. This work provides a facile strategy to prepare microspheres and construct self-healing coating, which shows the potential application in substituting the coating with chromate.