Optimizing smart self-healing coatings: Investigating the transport of active agents from the coating towards the defect

Highlights: • Dedicated set-up for studying inhibitor transport along coatingmetal interfaces. • Insights on the role of inhibitor transport for designing self-healing coating. • An ICP interlayer is shown to enhance transport of inhibitor to the defect. • Cationic inhibitors show better mobility than anionic in the (partially) reduced ICP. • A synergetic effect of inhibitor and the re-oxidizing ICP was observed. There are many studies on different concepts for so called smart self-healing coatings providing safe storage and corrosion triggered release of inhibitors. However, achieving an efficient transport of the released inhibitor to the defect is so far a widely neglected issue, although it is crucial for the overall performance. Hence, an in-depth investigation was carried out on inhibitor transport through the coating system into the defect, based on dedicated model sample set-ups. The main focus was on the possible beneficial role of an interfacial polypyrrole layer on the overall performance. Especially for some organic inhibitors huge effects were observed.