Preparation of methylacridinium iodides self-assembled monolayers and its anti-corrosion properties for mild steel in seawater: Experimental and computational studies

Two kinds of environmentally stable acridinium-based self-assembled monolayer materials, namely 9,10-dimethylacridinium iodide (DMAI) and 9-phenyl-10-methylacridinium iodide (PMAI), were produced on the surface of mild steel by a dip-coating strategy. The resultant self-assembled monolayers have been characterized by ATR-FTIR, XPS, and contact angle measurements. The anti-corrosion performances of the self-assembled monolayers were evaluated by weight-loss tests and electrochemical techniques. The experimental results indicated that the properties of self-assembled monolayers are mixed-type inhibitor, and the η_max of PMAI and DMAI reached up to 92.27% and 89.47% respectively at 300 mg/L based on polarization studies. The surface morphology of corroded/inhibited mild steel has been studied by atomic force microscope (AFM), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDX). Quantum chemical calculations provided insightful quantitative information for revealing the relationship between the molecular structures and inhibition performance. Molecular dynamics (MD) simulations were carried out to explore the configurationally adsorption behavior of DMAI and PMAI on Fe (110) surface.