Self-Healing and Antifouling Multifunctional Coatings Based on pH and Sulfide Ion Sensitive Nanocontainers

Application of mesoporous silica nanoparticles (MSNs) as delivery tools for self-healing coatings is limited by spontaneous leakage and specifically responsive release of small molecular inhibitors. In this work, a pH/sulfide ion responsive release system based on MSNs using a Cu-BTA complex forms at the openings of the mesopores into which BTA (corrosion inhibitor) and benzalkonium chloride (biocide) are loaded. The spontaneous leakage of active species is completely avoided and premature release of the loaded composition was lowered to 0.02. The responsive release begins when the pH is lower than 5 or [S2-] is higher than 0.02 mM (about 0.6 ppm). The hybrid coating containing the responsive release system exhibits feedback self-healing property sensitive to lowering of pH and sulfide ion concentration and, at the same time, provides a high barrier level for a long time. Due to incorporation of biocide in the release system, the coating is also provided with antifouling properties.