Preparation of Fluoroalkylsilane/Urea Formaldehyde/Polyurethane Modified SiO2@TiO2 Self-Healing Superhydrophobic Composite Coating

Superhydrophobic materials have attracted widespread attention due to their unique surface structures and properties. However, in practical applications, superhydrophobic surfaces are often affected by external environmental factors, such as chemical corrosion and organic contamination, which can lead to structural damage and the loss of superhydrophobicity. In this work, SiO 2 @TiO 2 composite micro/nano particles were prepared by coating photocatalytically active TiO 2 nanoparticles onto the surface of SiO 2 . After modification with fluoroalkylsilane (FAS) and blending with urea formaldehyde and polyurethane, a SiO 2 @TiO 2 –FUP superhydrophobic coating with self-healing capability was fabricated. Specifically, the resulting SiO 2 @TiO 2 micro/nanostructure exhibits excellent photocatalytic performance for the degradation of organic pollutants. As a surface modifier, 1H,1H,2H,2H-perfluorooctyltriethoxysilane (FAS-13) provides low surface energy, which is essential for achieving superhydrophobicity. Urea–formaldehyde acts as a microcapsule shell that encapsulates the low-surface-energy compound FAS-13, enabling the coating to exhibit self-healing behaviour. Polyurethane serves as a binder that firmly anchors the hydrophobic particles and self-healing microcapsules to the substrate, thereby enhancing the mechanical durability and stability of the coating. After spray deposition, a stable superhydrophobic coating forms on the substrate surface. Even after immersion in acidic or alkaline solutions or exposure to water-flow impact, no solid particles detach from the surface, and the coating maintains its superhydrophobic properties. More importantly, the coating can restore its superhydrophobicity under UV irradiation after mechanical damage or organic contamination.