Fluorine-Free Superhydrophobic Petal-like SiO2 Nanostructure Supported on Cotton for Oil–Water Separation

The practical applications of superhydrophobic fabrics face challenges such as inadequate durability and dependence on toxic fluorine-containing reagents. In this work, a robust, multipurpose, and fluoride-free superhydrophobic fabric is engineered. The fabrication process involves the preparation of a petal-like nano-SiO2 (PNS) using a two-phase layering approach. The pleated structure of PNS contributes to excellent roughness on the fabric surface, while the strong adhesion of polydopamine (PDA) serves as an intermediate layer, enhancing the durability and stability of the hydrophobic fabric. Additionally, the surface energy of cotton is reduced by polydimethylsiloxane (PDMS) coating. The resulting fabric coated with PDMS/PNS–PDA exhibits an exceptional water contact angle of 166.3°, a remarkably low sliding angle of only 3.6°, and excellent mechanical stability that can withstand 50 washing cycles and 30 Martindale abrasion cycles. Moreover, the superhydrophobic fabric demonstrates prominent antifouling and self-cleaning properties along with oil–water separation efficiency (>98%), water-in-oil emulsion (96%), and reusability for oil–water separation. Overall, the engineered superhydrophobic fabric shows promising potential in oil–water separation and the development of functional textiles.