engleski

Longterm protective properties of polymer nano- coatings of fatty acids for protection of copper based cultural heritage

Copper and its alloys are among the most common metals that have been used in art throughout history. They have been used for sculptures and building structures like roofs, facades, and gutters. Because of the increased air pollution, all these artefacts are endangered and need additional protection. Fatty acids have self-assembling properties and an affinity for metals. They form self-assembled molecular layers (SAMs) with protective properties on the surface of metals. SAMs have good potential in replacing traditional corrosion inhibitors because of their numerous advantages: they are easy to prepare, safe, small amounts of chemicals are needed to cover large surfaces, resulting in less environmental impact and a lower price compared to traditional inhibitors. A disadvantage of this method is SAMs easy removal from the metal surface. Crosslinking of the molecules that form the SAM would result in a nano-thick polymer coating which is more durable, stronger, and resistant to penetration of molecules from the atmosphere. If the SAMs are crosslinked using ionizing radiation the procedure is fast, effective, and still environment friendly. In this work, the long-time behavior of SAMs formed on copper, uncrosslinked and crosslinked, in simulated atmospheric conditions were examined to evaluate their long-lasting protective properties. Elaidic acid, C₁₈H₃₄O₂, an unsaturated trans fatty acid was used to form SAMs on the surface of copper. The SAMs were then crosslinked using gamma irradiation into protective polymer coatings. Electrochemical impedance spectroscopy (EIS) and linear polarization resistance were used to evaluate the protective properties of the coatings against corrosion in atmospheric conditions. Goniometry and Raman spectroscopy were used to additionally characterize the hydrophobic properties of the coated surfaces. Results have shown that the crosslinked coatings on the surface of copper offer greater and longer protection compared to the unirradiated SAMs.

Copper ; self-assembling monolayers ; polymer coatings ; ionizing radiation ; corrosion protection

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