Construction of Silane-Modified Diatomite-Magnetic Nanocomposite Superhydrophobic Coatings Using Multi-Scale Composite Principle

To address the challenges of cotton cellulose materials being susceptible to environmental humidity and pollutant erosion, a strategy for constructing superhydrophobic functional coatings with biomimetic micro–nano composite structures was proposed. Through surface silanization modification, diatomite (DEM) and Fe3O4 nanoparticles were functionalized with octyltriethoxysilane (OTS) to prepare superhydrophobic diatomite flakes (ODEM) and OFe3O4 nanoparticles. Following the multi-scale composite principle, ODEM and OFe3O4 nanoparticles were blended and crosslinked via the hydroxyl-initiated ring-opening polymerization of epoxy resin (EP), resulting in an EP/ODEM@OFe3O4 composite coating with hierarchical roughness. Microstructural characterization revealed that the micrometer-scale porous structure of ODEM and the nanoscale protrusions of OFe3O4 form a hierarchical micro–nano topography. The special topography combined with the low surface energy property leads to a contact angle of 158°. Additionally, the narrow bandgap semiconductor characteristic of OFe3O4 induces the localized surface plasmon resonance effect. This enables the coating to attain 80% light absorption across the 350–2500 nm spectrum, and rapidly heat to 45.8 °C within 60 s under 0.5 sun, thereby demonstrating excellent deicing performance. This work provides a theoretical foundation for developing environmentally tolerant superhydrophobic photothermal coatings, which exhibit significant application potential in the field of anti-icing and anti-fouling.