Smart Coatings for Corrosion Protection: On the Need for New Coating Concepts

Ideally smart coatings for corrosion protection have to be able to protect the underlying metal from corrosion by providing excellent barrier properties, at the same time showing a fast and efficient self-healing in case a defect down to the metal is inflicted into them, while being as delamination resistant as possible. These seem to be basically incompatible properties, as either mobility of species is high or the coating is highly impermeable, i.e. it is difficult to envisage a coating that can be both at the same time. In fact, in recent works we have shown that for excellent self-healing performance especially the resistance against cathodic delamination of a coating should be significantly weakened [1, 2]. Using conductive polymer additions to non-conductive coatings, both high self-healing activity [1-3] as well as high resistance against cathodic delamination [4, 5] can be controlled in a wide range. Based on an in-depth understanding of the underlying mechanisms we are currently working on strategies for developing coatings that show excellent active as well as passive protection properties. Latest progress of the research on this topic well be presented and the implication will be discussed. [1] M. Uebel, L. Exbrayat, M. rabe, T.H. Tran, D. Crespy, M. Rohwerder, On the Role of Trigger Signal Spreading Velocity for Efficient Self-Healing Coatings for Corrosion Protection, Electrochem. Soc. 165 (2018) C1017-C1027 [2] H. Tran , A. Vimalanandan , G.Genchev , J. Fickert , K. Landfester, D. Crespy , M.Rohwerder, R egenerative Nano-Hybrid Coating Tailored for Autonomous Corrosion Protection, Advanced Materials 27 (25) (2015) 3825-3830 [3] A. Vimalanandan, L.P. Lv, T.H. Tran, K. Landfester, D. Crespy, M. Rohwerder, Redox-Responsive Self-Healing for Corrosion Protection, Advanced Materials 25 (48) (2013) 6980-6984 [4] Anna Merz, Matthias Uebel, Michael Rohwerder, The Protection Zone: A Long-Range Corrosion Protection Mechanism around Conducting Polymer Particles in Composite Coatings: Part I. Polyaniline and Polypyrrole, Electrochem. Soc. 166 (2019) C304-C313 [5] Anna Merz, Michael Rohwerder, The Protection Zone: A Long-Range Corrosion Protection Mechanism around Conducting Polymer Particles in Composite Coatings: Part II. PEDOT:PSS, Electrochem. Soc. 166 (2019) C314-C320