Ionic liquid-assisted production of hydrophobic nanocomposite coating for mild steel corrosion prevention in saline medium

A dicationic ionic liquid, [BisOct (MIM)2][2Br], was successfully synthesized and used for the hydrothermal preparation of rod-shaped nanostructured ZnO with a basic hexagonal wurtzite growth unit. A hydrophobic nanocomposite coating of ZnO with polystyrene (ZnO/PS) was fabricated and characterized using Fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis. The effect of nanocomposite coatings with different percentages of ZnO (1, 3, and 5 wt.%) was explored for mild steel corrosion protection in NaCl (3.5 wt.%) saline solution using electrochemical impedance spectroscopy (EIS), atomic force microscopy (AFM), and FE-SEM. The EIS results showed a significant increase in the charge transfer resistance, with the highest value of 4.83 × 105 Ω cm2 in the presence of PS/ZnO-5, which acted as an efficient passivating barrier for the diffusion of corrosive ions. The results revealed that embedding ZnO nanorods significantly enhanced the corrosion-protection properties of the PS coating. The results of this study may contribute to the design of anticorrosive coatings for industrial applications.