Preparation, Characterization and Corrosion Evaluation of Poly(o-toluidine), Poly(m-Toluidine), and Poly(p-Toluidine) Blended with Waterborne Polyurethane

In this study, poly-toluene isomers, such as poly(o-toluidine), poly(m-toluidine), and poly(p-toluidine), (abbreviated as POT, PMT, and PPT, respectively), were investigated for the corrosion protection of mild steel in 3.5% NaCl. The polymers were prepared by chemical oxidation and characterized by Fourier-transform infrared spectroscopy, UV–visible spectroscopy, x-ray diffraction, cyclic voltammetry, and scanning electron microscopy. The corrosion inhibition abilities of these coatings were evaluated by polarization and electrochemical impedance spectroscopy in aqueous NaCl solution. The results of this study showed that the inhibition efficiency of PMT reached 82.1%, which was greater than those of POT and PPT with 74.5% and 69.2%, respectively. In addition, the corresponding corrosion rates of PMT, POT, and PPT are 1.3 × 10−4 mm/year, 1.0 × 10−3 mm/year, and 4.1 × 10−2 mm/year, respectively. All these data reveal excellent properties of PMT in terms of corrosion protection.