Corn Oil-Derived Poly (Urethane-Glutaric-Esteramide)/Fumed Silica Nanocomposite Coatings for Anticorrosive Applications

Poly (urethane-glutaric-esteramide) (PUGEA) was synthesized using corn oil and glutaric acid and further treated with toluene-2, 4-diisocyanate. Fumed silica with 1, 2, and 3 weight percentage was included in the synthesized PUGEA resin to obtain PUGEA-1, PUGEA-2 and PUGEA-3 nanocomposite resins, respectively. The chemical structure of glutaric polyesteramide and PUGEA was characterized by Fourier-transform infrared spectroscopy and nuclear magnetic resonance (H-1 and C-13 NMR). The morphology, hydrophobicity and thermal stability of the PUGEA nanocomposites were investigated by using scanning electron microscopy and energy-dispersive X-ray spectroscopy, by measuring contact angle and by thermogravimetric analysis (TGA). Afterward, the PUGEA/fumed silica nanocomposite coatings were applied on mild steel and dried at room temperature, and they were physico-mechanically characterized by measuring their scratch and pencil hardness, bending, impact resistance and cross-hatch adhesion. The anti-corrosion effectiveness of PUGEA-2 was investigated by electrochemical impedance spectroscopy immersing it for 42 days in a 3.5 wt% NaCl aqueous solution. Finally, TGA reveals that the PUGEA-3 nanocomposite coating can be safely used up to 275 degrees C.