Tannic complexes coated nanocontainers for controlled release of corrosion inhibitors in self-healing coatings

Abstract Nanocontainers with controlled release properties have been used in self-healing coatings for many years. However, the spontaneous leakage of the small molecular weight inhibitors from the nanocontainers promoted the development of nanovalves or gatekeepers to control inhibitor release. Herein, we demonstrate a facile method to encapsulate corrosion inhibitor in mesoporous silica nanoparticles (MSNs) with the help of tannic acid complexes, which endow the inhibitor loaded MSNs with pH-controlled release function. Commercial water-borne alkyd coating impregnated with 2 wt% of benzotriazole-loaded nanocontainers presented significant self-healing effect after 20 days of immersion in 0.1 M NaCl solution from both released benzotriazole and tannic acid as confirmed by electrochemical impedance spectroscopy and microscopy. The impedance modulus of coating with nanocontainers increased from 4.7 × 104 Ω cm2 to 1.8 × 105 Ω cm2 after 15 days of immersion.