Electrochemical assessment of crosslinked self-assembled monolayers of behenic acid for enhanced corrosion protection of bronze and patinated surfaces

Biljanić, Helena; Markulić, Barbara; Kosec, Tadeja; Mirosavljević, Marija; Desnica, Vladan; Šatović, Domagoj; Kralj, Damir; Marušić, Katarina (2025) Electrochemical assessment of crosslinked self-assembled monolayers of behenic acid for enhanced corrosion protection of bronze and patinated surfaces. Progress in Organic Coatings, 211 . ISSN 0300-9440

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Official URL: http://doi.org/10.1016/j.porgcoat.2025.109750

Abstract

Bronze sculptures and historical artifacts typically develop natural or artificially induced patinas that enhance aesthetic value and confer some degree of corrosion protection. However, patinated surfaces are vulnerable to environmental degradation, especially due to acid rain, resulting in material loss and impaired visual integrity. Current protective coatings are limited by either environmental or performance constraints. While self-assembled monolayers (SAMs) based on fatty acids such as behenic acid offer potential corrosion protection by forming ultrathin layers on metal surfaces, their long-term effectiveness is compromised by limited chemical stability. This study addresses this critical gap by evaluating the protective effectiveness and durability of SAMs and polymer nanocoatings (PNCs) derived by crosslinking SAMs from behenic acid using gamma irradiation on bare bronze (BB), black sulfide-patinated bronze (BP), and green chloride-patinated bronze (GP) surfaces. The assessment focused primarily on electrochemical performance, using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (Tafel) measurements to evaluate coating stability and corrosion resistance before and after artificial aging. Initial surface characterization employed spectroscopic (FTIR-ATR, Raman spectroscopy), microscopic (SEMEDS, metallography), elemental (X-ray fluorescence), wettability (contact angle goniometry), and visual analyses (colorimetry) to characterize the composition and morphology of the substrates. Distinct structural and chemical differences were identified, with BP characterized primarily by anilite (Cu₇S₄) and GP consisting predominantly of basic copper chlorides (Cu₂(OH)₃Cl), such as atacamite and its isomorphs. Electrochemical analyses demonstrated that while SAM coatings initially reduced corrosion current densities significantly, their protective capability diminished over time due to progressive removal of loosely bound molecules. Conversely, radiation-crosslinked PNC coatings maintained stable corrosion protection over UV-Wet- Dry artificial aging. Minor capacitance increases indicated slight enhancement in surface activity, yet no significant degradation of the crosslinked polymer coating was observed.

Item Type:

Article

Uncontrolled Keywords:

Bronze patina; Self-assembled monolayer; Radiation crosslinking; Polymer nanocoating; Corrosion protection

Subjects:

NATURAL SCIENCES
NATURAL SCIENCES > Chemistry
NATURAL SCIENCES > Chemistry > Applied Chemistry

Divisions:

Division of Materials Chemistry

Projects:

Project title	Project leader	Project code	Project type
Primjena ionizirajućeg zračenja za dobivanje polimernih nano prevlaka na metalima-RadMeNano	Katarina Marušić	IP-2020-02-4344	HRZZ
Višenamjenska primjena radijacijske tehnologije za zaštitu i očuvanje kulturne baštine	Katarina Marušić	IAEA CRP 26656	UNSPECIFIED
Development and Implementation of Cultural Heritage Preservation using Ionizing Radiation Technology" project entitled "The Multipurpose Application of Radiation Technology for the Protection and Preservation of Cultural Heritage	Katarina Marušić	CRP F22082	UNSPECIFIED
Studija trajnosti prevlaka na bronci za vanjsku primjenu	Katarina Marušić	UNSPECIFIED	MZOS