Performance of Polyvinyl Ester Coating Based on Bisphenol A Containing Polyaniline Composite with Copper Metal-Organic Framework in ST37 Corrosion

The steel corrosion and the control of the damages caused by it is one of the challenging issues that has attracted the attention of many researchers and industrialists. Among corrosion control methods, protective coatings such as epoxy, vinyl ester, polyurethane, etc. are used more. Despite their wide applications, these coatings absorb water and corrosive species over time and cause the metal substrate to corrode and reduce the adhesion of the coating. Therefore, researchers are trying to find solutions to increase their lifespan and efficiency. In the present study, polyaniline (PANI) and its composite with copper metal-organic framework (Cu-MOF) were synthesized using in situ oxidation polymerization method. The X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and X-ray energy diffraction spectroscopy (EDX) were used for characterization. Then, 0.5 wt. % of PANI and PANI-Cu-MOF were added to vinyl ester (VE) resin based on bisphenol A and coated on mounted ST37 steel with a brush method. The protective performance of the prepared coatings was studied in 3.5 wt. % NaCl solution at ambient temperature using electrochemical impedance spectroscopy (EIS) and Tafel polarization for 240 hours. The EIS results showed that the corrosion resistance (Rcorr) of the VE/PANI-Cu-MOF coating at the end of immersion was 1.04 × 108 Ω cm2 , which compared to VE/PANI (1.31 × 105 Ω cm2 ) and VE (1.08 × 105 Ω cm2 ) is more. The results of Tafel polarization also indicate that the corrosion current density of VE coating is reduced in the presence of PANI-Cu-MOF composite.