Nano- and Micro-SiO₂ With Integrated Green Chemistry-Based Superhydrophobic Coating for Robust Antifouling and Anticorrosion Properties

With increasing energy demands, the need for coating materials with exceptional superhydrophobic properties has grown substantially. However, the widespread use of fluorinated compounds, solvents, and polymer-based synthetic materials has led to heightened levels of microplastics and pollutants. Here, we used a self-curing, solvent-free, and recyclable polyester polyol polymer material combined with (5 and 6.5 μm) micro- and nanosized SiO₂ (μ-SiO₂ and n-SiO₂) particles to create superhydrophobic coatings with contact angles above 170° and low roll-off angle. They were applied for self-cleaning, antifouling, and anticorrosion purposes and tested for stability in hot water, steam, and ultrasound. Both μ-SiO₂ particles mixed with n-SiO₂ exhibited excellent improvement in antifouling properties. Furthermore, 5 μm SiO₂ incorporated with n-SiO₂ demonstrated significantly higher resistance in a 62-cycle sandpaper abrasion test and maintained a contact angle above 150°, whereas this angle was lower for the 6.5 μm SiO₂ coating after 30 cycles. These results suggest that 6.5 μm SiO₂ offers less resistance to applied force due to its irregular roughness. However, in scenarios with lower forces, such as water drop tests, both coatings easily withstand a drop count of 3000. Additionally, electrochemical polarization curve analysis, AC impedance analysis, and seawater immersion tests confirmed the robust corrosion resistance of the superhydrophobic material.