Novel self-healing protective coatings with nanocontainers of corrosion inhibitors open new opportunities for long-term anticorrosion protection of different metallic materials. In this paper a new type of functional nanoreservoir based on silica nanocapsules (SiNC) synthesized and loaded with corrosion inhibitor 2-mercaptobenzothiazole (MBT) in a one-stage process is reported for the first time. Unlike conventional mesoporous silica nanoparticles, SiNC possess an empty core and shell with gradual mesoporosity, arising from the particular conditions of the synthetic route adopted, which confers significant loading capacity and allows prolonged and stimuli-triggered release of the inhibiting species. The kinetics of inhibitor release was studied at different pH values and concentrations of NaCl. The results show a clear dependence of the release profiles on corrosion relevant triggers such as pH and Cl⁻ concentration. When SiNC loaded with MBT are dispersed in NaCl solution, there is a significant decrease of the corrosion activity on aluminium alloy 2024. More importantly, when SiNC–MBT is added to a conventional water-based coating formulation, the modified coating hampers corrosion activity at the metal interface, better than in the case of direct addition of corrosion inhibitor. Furthermore, self-healing is observed before and after artificially inflicting defects in the modified coatings. As a result, the developed nanocontainers show high potential to be used in new generation of active protective coatings.

Self-healing protective coatings based on different types of nanocontainers of corrosion inhibitors have been recently developed and reported as promising solutions for many industrial applications. Layered double hydroxide (LDH) nanocontainers are among the most interesting systems since they confer the delivery of inhibitors on demand under action of corrosion-relevant triggers such as the presence of corrosive anions or local change of pH. In this paper, we report for the first time a new approach based on formation of a nanostructured LDH-container layer directly on the metal surface as a result of conversion reaction with a metal (aluminium alloy 2024) surface. The methodology allows the formation of a spatially differentiated LDH structure preferentially on surface sites located at active intermetallics. The LDH container layer loaded with vanadate ions provides an efficient active corrosion protection and can be used as a functional layer in self-healing coating systems.