Intrinsic Self-Healable, Corrosion-Resistant Silicone Coating Based on Quadruple Hydrogen-Bonded Supramolecular Polymer

Abstract

Corrosion-resistant coatings with self-healing capabilities are still a great challenge for metal protection. In this study, a corrosion-resistant coating with intrinsic self-healing capabilities was developed by compounding hydroxy-terminated silicone oil (HTSO) with 2-ureido-4[1<i>H</i>]-pyrimidone (UPy) derivatives. The smooth surface of the coating was shown by scanning electron microscopy (SEM), and good smoothness was also exhibited in the cross-section, which indicated that the coating is very homogeneous from the top to the bottom. Thermogravimetric analysis (TG) was employed to illustrate the temperature-resistant characteristics of the coating, revealing its significant chemical stability up to 360 °C. The corrosion resistance of the coating is assessed through electrochemical impedance spectroscopy (EIS), the typical impedance at 0.01 Hz is 1.70 × 10⁹ and 2.44 × 10⁸ Ω·cm² before and after exposure to a 3.5 wt % NaCl solution for 70 days. There was no significant change in the water contact angle of the coatings before and after immersion; however, the adhesion strength was reduced. Notably, the coating demonstrates immediate and multiple self-healing properties. The tensile stress of the associated healing sample experiences an augmentation within the temperature range of 30-120 °C, with the critical fracture strain of the healed sample reaching 235% at 120 °C. The self-healing mechanism of the coating is systematically investigated using in situ Raman spectroscopy.