Nanocontainer-Based Self-healing Coatings: Results of the Neutral and Copper-Accelerated Salt Spray Tests and Improved Coating Performance using Nanocontainer Mixtures

摘要

The main message of the report is the demonstration of the applications of nanocontainers of different types (polymer capsules, mesoporous silica or titania nanoparticles with pH-sensitive stoppers or outer polyelectrolyte shell, halloysite nanotubes) loaded with highly effective inhibitors for the protection of Al and Mg alloys: 8-hydroxyquinoline, mercaptobenzothiazole, etc. The corrosion protection performance was demonstrated employing several commercially available paint formulations as coating matrices for hosting nanocontainers with the use of both laboratory-scale tests (Electrochemical Impedance, SVET) and industrial-scale tests (Neutral and Cu-accelerated salt spray tests, weathering tests). Besides the incorporation of the single nanocontainer-inhibitor combination into the coating host, the efficiency of the use of nanocontainer mixtures was demonstrated, especially for different types of the inhibitors. Despite the progress achieved in the field of nanocontainer-based coatings during the last few years, there still exist some, more fundamental, problems on the mixing nanocontainers with the coating material, effective loading of the nanocontainers with the inhibitor and nanocontainer distribution inside the coating matrix. More detailed, these problems involve the answers for the following questions: (i) How to avoid the agglomeration of the nanocontainers; (ii) What should be the optimal loading capacity and (iii) What should be the optimal container content and distribution inside the coating, which, actually, depends on the coating thickness and barrier properties. The answers to these questions can be found in the presented report, where we apply both theoretical and practical approaches for investigation of the nanocontainer behaviour inside the coatings and elaborate the nanocontainer distribution-coating thickness dependencies in order to achieve the best corrosion protection properties.