Dianiline-epoxy modification as effective defender agent in metal corrosion: a combined experimental and computational approach
This study explores the efficacy of bisphenol A tetraglycidyl ether dianiline dipropoxy epoxy polymer (TGEDADPBA) as a safeguarding agent, using both experimental and computational approaches. The study found that 97.4% defensive level was achieved at 10−3 M. The corrosion current density (icorr) exhibited a substantial decline, from 982 μA/cm² in the 1.0 M HCl solution to 25 μA/cm² at 10−3 M. Polarisation studies indicated mixed-type inhibition, affecting both anodic and cathodic reactions, as evidenced by changes in Tafel slopes (βa and βc). The charge transfer resistance (Rct) reached 938.7 Ω cm² at 10−3 M, enhancing the steel's protective capability. Scanning electron microscopy (SEM) analysis revealed a smoother and less corroded surface in the presence of TGEDADPBA, while energy-dispersive spectroscopy (EDS) analysis indicated a reduction in oxygen concentration and an increase in carbon content, confirming the establishment of a defender layer. Density functional theory (DFT) calculations further revealed that the protonated form of TGEDADPBA exhibited higher EHOMO (−3.913 eV) and lower ELUMO (−0.543 eV) energy values, suggesting enhanced adsorption and inhibition capabilities. Furthermore, molecular dynamics (MD) simulations revealed robust adsorption interactions with Fe(110) surfaces, with adsorption energies of −238.05 kcal/mol and −215.35 kcal/mol for the protonated and neutral forms, respectively.
