Study of new phosphorus-sulfur epoxy polymer for CS anticorrosion in HCl solution: Experimental and theoretical investigations

In this study, we synthesized a novel difunctional phosphorus-sulfur polymer, DGMEPE, and explored its anti-corrosive properties on carbon steel (CS) in a 1 M HCl medium. Structural characterization was conducted using FTIR, 1H, and 13C NMR. An integrated experiment-computation approach was employed. Polarization curves and electrochemical impedance spectroscopy were used to assess DGMEPE's inhibition efficiency and mechanism. Quantum chemical calculations and molecular dynamics simulation were employed to provide further insights into the anticorrosive ability of DGMEPE. Scanning electron microscopy and energy-dispersive X-ray spectroscopy characterized surface morphology. The maximum protection of DGMEPE was 94-96 % at 10-3 M. The polarization curves demonstrated the mixed-type inhibition behavior of DGMEPE. Surface analysis revealed effective chemical adsorption of DGMEPE on the CS surface, significantly reducing acid-induced damage, which was further supported by DFT calculations and MC and MD simulations. These simulations provided a detailed picture of the adsorption of DGMEPE and its protonated form on the CS surface, offering insights into the mechanism of corrosion inhibition.