engleski

Application of self-assembled films of long chain organic acids in corrosion protection

Self-assembled monolayers (SAMs) of long-chain organic compounds have found their application in many fields [1], such as sensors, electronic devices, lubrication as well as in corrosion protection [2]. Long-chain organic acids, such as carboxylic, hydroxamic or phosphonic acids can bind to oxidized surfaces of metals and alloys which is an advantage for their practical application as most of the commercially important metals and alloys readily get covered by thin oxide layers when exposed to air. The other advantage of long- chain organic acids, especially carboxylic acids is that they are non-toxic. Most of the studies on longchain organic acids SAMs are focusing on characterization of SAM structure and binding of head group to metal surface but there are far less studies that focus on efficiency and durability of corrosion protection provided by SAMs, especially on alloys. In order to achieve efficient corrosion protection, self-assembled monolayer should be dense, ordered and defect free to act as a barrier against aggressive ions diffusion towards the metal surface. In principle, SAMs are easily prepared by adsorption, either from the solution or vapor phase, but in practice many factors determine whether the well ordered and compact monolayer will be formed. Film formation is affected by temperature, solution exposure time, environmental conditions, solvent, etc. The task of forming well ordered organic monolayer is especially complicated when alloys are used as a substrate. In this work the possibility of corrosion protection of copper-nickel alloy by self- assembled films of long chain carboxylic and phosphonic acids is examined. The influence of various factors, such as molecule chain length, acid group, surface roughness, adsorption conditions on the corrosion protection are examined. By changing the experimental conditions both mono- and multilayer films are formed and their protective effect is evaluated. References [1] A.R. Bishop, R.G. Nuzzo, Curr. Opin. Colloid Interface Sci., 1 (1996) 127-136. [2] M. Rohwerder, M. Stratmann, G. Grundmeier, Corrosion Prevention by Adsorbed Organic Monolayers and Ultrathin Plasma Polymer Films in P. Marcus Corrosion Mechanisms in Theory and Practice, CRC Press, Francis Taylor Group, 2012, USA, pp: 617-668. Acknowledgments: The research leading to these results has received funding from Croatian Science Foundation under grant agreement 9.01/253.

corrosion protection ; copper-nickel alloy ; self-assembled layers ; long chain organic acids

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