Ionic Liquid-Modified Hydrophobic Layers for Enhanced Corrosion Inhibition

The aim of this study was to investigate the potential of the ionic liquid 1-methyl-3-n-octylimidazolium bis(trifluoromethanesulfonyl)imide (M3OITF), in combination with stearic acid (SA), to form self-assembled hydrophobic protective layers SAHL on AISI 316L stainless steel. The corrosion resistance of the resulting layers were evaluated in 1.0 M and 0.5 M HCl solutions using potentiodynamic polarisation measurements. Results show that immersing steel samples in ethanolic solutions of SA containing various concentrations of M3OITF leads to the formation of a hydrophobic layer that effectively suppresses anodic dissolution. Increasing the M3OITF concentration significantly decreased the anodic current density and enhanced inhibition efficiency. In 1.0 M HCl, inhibition efficiencies above 85% were achieved for all concentrations tested, while in 0.5 M HCl, efficiencies close to 99.9% were obtained. Contact angle measurements confirmed the hydrophobic nature of the modified surfaces, remaining above 105° even after five days of immersion in 0.5 M HCl. These findings demonstrate that M3OITF, when combined with stearic acid, can effectively form durable and highly efficient self-assembled anticorrosive coatings.