(Digital Presentation) Improved Properties of Polyurethane Coatings Using Mesoporous Silica Nanoparticles Loaded with Imidazole

Corrosion causes damage to the steel infrastructure, and polyurethane coatings were developed to overcome this issue. Three types of samples were evaluated in the study: the first consisted of pure polyurethane (PU), serving as the reference for comparison; the second incorporated Mesoporous Silica (MSN) within the polyurethane matrix; and the third involved polyurethane mixed with Imidazole-loaded MSN, which was then applied to the carbon steel substrate. Thermogravimetric analysis (TGA) and Fourier Transform Infrared Spectroscopy (FTIR) affirmed the effective encapsulation of the corrosion inhibitor Imidazole in MSN, achieving a loading capacity of 37 wt.%. The electrochemical technique was employed to assess the corrosion resistance, where results obtained from Electrochemical Impedance Spectroscopy (EIS) over a period of 168 hours indicated that the Imidazole-loaded coatings provided more robust and consistent corrosion protection compared to both the MSN-enhanced and the pure PU samples by maintaining the impedance above 1 GΩ by the end of the test period while the other two sample types went below 1 MΩ. This enhanced protective performance is credited to the inhibitor's role in passivating the steel surfaces against saltwater exposure. Additionally, Potentiodynamic testing (Tafel) on scratched samples over 144 hours period showing a change in the corrosion current from 1.07 μA to 20.4 μA then back to 10.8 μA for the MSN, and from 1.39 μA to 7.54 μA and finally back to 2.07 μA for the Imidazole loaded MSN-PU coating demonstrating the corrosion protection benefits of both coating with better performance when using the Imidazole loaded MSNand better the an the steadily decreasing performance in the pure PU samples going from 3.43 μA to 40.2 μA over the same timeframe.