Self-assembly cell structure superhydrophobic coatings for high efficient oil-water separation and anti-icing

The existing superhydrophobic materials applied in anti-icing and water-in-oil emulsion separation have some limitations, such as environmental concerns, poor coating durability and non-biodegradability. In this work, a robust, fluorine-free and versatile self-assembly cell structure superhydrophobic cotton fabric is presented. Modified nano-SiO₂ was embedded into the voids and pores of diatomite, forming a unique cell structure. Subsequently, polydimethylsiloxane (PDMS) was used to hydrophobically treat the cotton fabric impregnated with the diatomite/SiO₂ mixture, resulting in the preparation of superhydrophobic cotton fabric composed of diatomite/SiO₂/PDMS. The resulting superhydrophobic cotton fabric demonstrates the water contact angle (WCA) of 163.6° and sliding angle (SA) of 4.7°, with an ice-delay time of 615 s. Moreover, the superhydrophobic cotton fabric demonstrates excellent separation performance for oil-water and water-in-oil emulsions. The unique dual-hydrophobic structure of the fabric surface allows for the release of modified nano-silica particles from within when the diatomite and PDMS are worn down or damaged, thereby reintroducing new roughness and low-energy surface materials to the fabric. Consequently, the prepared superhydrophobic cotton fabric exhibits outstanding durability and stability, enduring 40 cycles of abrasion, 35 cycles of washing and 60 cycles of freeze-thaw.