Functionalized coatings based on organic polymer matrix against the process of corrosion of mild steel in neutral medium

Abstract

To obtain a protective system against corrosion process of carbon steel in a near neutral electrolytic solution prepared with 26.5 g NaCl and 3.5 g of (NH4)2SO2, a series of coatings were formulated. They were based on a nitrocellulose resin in which 3% w/w of a composite material (PANIB-F or PANIS-F) prepared with either base polyaniline (PANIB) and its salt (PANIS) were formed as a matrix, in which 10% w/w of fluconazole (F) as a corrosion inhibitor was dispersed. The synthesized materials were characterized by techniques such as: FTIR, DRX, and SEM. The protective behavior of the synthesized coatings was evaluated by electrochemical impedance spectroscopy (EIS). The results of the electrochemical tests indicated that the formulated films with the PANIB-F composite, provide highest protection to the metal substrate than the one formulated with PANIS-F. For the understanding of the protection mechanism and the molecular interactions of the composite materials (PANIB-F and PANIS-F respectively), a molecular coupling simulation was performed considering the experimental conditions. Calculation of binding energies was performed and obtained using the Adaptive Poisson-Bolztmann (APBS) software. The results of the simulation suggest that PANIB has less affinity for F than PANIS, which favors the F dissolution when the electrolyte penetrates the pores of the coating.