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Design and Fabrication of a Novel Stimulus-Feedback Anticorrosion Coating Featured by Rapid Self-Healing Functionality for the Protection of Magnesium Alloy

Ding, ChenDi, Xu, JianHua, Tong, Ling, Gong, GuangCai, Jiang, Wei, Fu, Jiajun
ACS applied materials 2017 v.9 no.24 pp. 21034-21047
8-hydroxyquinoline, alloys, aromatic hydrocarbons, binding capacity, coatings, corrosion, electrochemistry, encapsulation, magnesium, magnetic fields
Corrosion potential stimulus-responsive smart nanocontainers (CP-SNCs) are designed and synthesized based on the installation of the supramolecular assemblies (bipyridinium ⊂ water-soluble pillar[5]arenes) onto the exterior surface of magnetic nanovehicles (Fe₃O₄@mSiO₂), linked by disulfide linkers. The supramolecular assemblies with high binding affinity as gatekeepers effectively block the encapsulated organic corrosion inhibitor, 8-hydroxyquinoline (8-HQ), within the mesopores of Fe₃O₄@mSiO₂. When the corrosion potential of the magnesium alloy (−1.5 V vs SHE) is exerted, 8-HQ is released instantly because of the cleavage of disulfide linkers and the removal of the supramolecular assemblies. CP-SNCs were incorporated into the hybrid organic–inorganic sol–gel coating to construct a corrosion potential stimulus-feedback anticorrosion coating (CP-SFAC) that was then deposited on the magnesium alloy, AZ31B. With the aid of a magnetic field, CP-SNCs were gathered in the proximity of the surface of AZ31B. CP-SFAC showed a satisfactory anticorrosion performance, more importantly, through the evaluation of microzone electrochemical techniques. CP-SFAC presented the rapid self-healing functionality when the localized corrosion occurred. Shortening the distance between CP-SNCs and the surface of AZ31B enhances the availability of the incorporated CP-SNCs and makes most of the CP-SNCs to timely respond to the corrosion potential stimulus and facilitates the formation of a compact molecular protective film before the corrosion products pile up. The characteristics of fast response time and quick self-healing rate meet the requirements of the magnesium alloy for self-healing in local regions.