Development of novel superhydrophobic coatings using siloxane-modified epoxy nanocomposites

The extensive research and interest in superhydrophobic surfaces have not yet resulted in their widespread utilization. Limitations include high cost, complex fabrication techniques, and poor durability. Herein, we report a facile, economic, and scalable spray-coating fabrication technique that utilizes an epoxy-silica nanocomposite to create robust and durable superhydrophobic coatings. To overcome its inherent high surface energy, the epoxy was modified using an amino-functionalized polysiloxane. The newly developed nanocomposite coating demonstrated excellent water repellency with contact angles of ~165° and sliding angles of ~3° for different substrate materials such as metals, wood, glass, and textile. Our results revealed that a nanocomposite coating with a silica concentration of ~28 wt% provides an optimum balance between superhydrophobicity and durability. We also investigated the effect of solvent volatility on the hierarchical structure and superhydrophobicity of the coated samples, which is rarely considered in the literature. It was found that a spray emulsion with lower solvent volatility results in an enhanced surface microstructure that improves water repellency. Moreover, the coated samples demonstrated excellent robustness and durability against peeling, abrasion, corrosion (pH 1 to 13), and high temperature (up to 150 °C) environments exposure tests. The outcome of our efforts confirms that the epoxy modification process leads to enhanced superhydrophobicity without compromising the robustness and durability of the coating. This remarkable performance offers a great potential for large-scale production of superhydrophobic surfaces operating in harsh working conditions.