Multifunctional Epoxy Coatings with GA-Functionalized MWCNTs: Corrosion Resistance and Thermo-Mechanical Performance for Steel Protection

Document Type : Original Article

Authors

1 Department of Nanomaterials and Nanocoatings, Institute for Color Science and Technology, P.O. Box 16765-654, Tehran, Iran

2 Department of Surface Coatings and Corrosion, Institute for Color Science and Technology, P.O. Box 16765-654, Tehran, Iran

Abstract

Amine-functionalized multi-wall carbon nanotubes (MWCNTs-NH₂) were employed as nanocarriers for gallic acid (GA), a green corrosion inhibitor, to develop multifunctional epoxy nanocomposites for steel protection in saline environments. GA was effectively immobilized onto MWCNTs-NH₂ to attain both active corrosion inhibition and enhanced barrier performance. Electrochemical impedance spectroscopy and polarization performed after 72 hours of immersion in saline solution indicated a ~91 % increase in total resistance and a ~ 47 % decrease in corrosion current density for the optimized MWCNT-NH₂/GA system compared to uninhibited samples. Epoxy coatings containing 0.15 wt. % of the synthesized nanocomposites demonstrated active protection in damaged regions, as confirmed by EIS and salt-spray testing. Following 24 hours of exposure to saline solution, the total resistance of the epoxy coating with 50 % GA loading increased by ~560% relative to the bare samples. Furthermore, the log|Z|10 mHz value, which serves as a suitable measure of self-healing ability in the scratched region, increased to ~4.8 kΩ.cm2. While it showed a notable decrease for uncoated epoxy, falling below 0.4 kΩ.cm2.These coatings also exhibited significantly improved adhesion under both dry and wet conditions. Adhesion loss for the epoxy coating containing the optimal 50 % GA loading was ~6 %. Notably, cathodic disbondment was reduced by 50 % and 42 % relative to neat epoxy and MWCNTs-NH₂-containing epoxy coatings, respectively, in the 50 % GA-loaded formulation. Furthermore, Thermo-mechanical analysis confirmed enhanced toughness reinforcement. Overall, the synergistic barrier effect of MWCNTs-NH₂ and the controlled release of gallate ions provide a promising strategy for durable, self-healing corrosion protection in harsh environments.

Keywords

Main Subjects

References

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Progress in Color, Colorants and Coatings
Volume 19, Issue 4 - Serial Number 63
October 2026
Pages 435-455

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