Non-fluorinated superhydrophobic spray coatings for oil-water separation applications: An eco-friendly approach

Inspired by nature, we prepared durable superhydrophobic coating materials (SHC) using Hexamethyldisilazane (HMDS) modified silica (SiO2) nanoparticles with acrylic resin, coupled with γ-Aminopropyltriethoxysilane (γ-APS) without the need of the perfluorinated and isocyanate based compounds. As we have prepared the organic acrylic resin by surfactant based emulsion polymerization method the material exhibited good film formation and inorganic silica functionalized with HMDS also exhibited low surface energy and good superhydrophobic property. The hybrid nanocomposites with and without γ-APS were characterized by FT-IR, TGA, particle size analyzer and SEM. The results shows that γ-APS strongly attaches with trimethylsilyl modified SiO2 and acrylic resin and form strong covalent network with excellent superhydrophobic property. The prepared superhydrophobic material was coated on various substrates like glass, wood, filter paper, cotton, plastic, stone, fabric and aluminium foil by spray coating. The SHC coated glass slides which were treated under various chemical and thermal conditions exhibited water contact angle of >150. Similarly, the samples were tested for mechanical durability, sand paper abrasion test shows the contact angle of >150 and sliding angle <10 which does not change up to 30 abrasion cycles. Further, we showed that prepared SHC can be used for oil/water separation study and the material exhibited excellent mechanical durability up to 50 cycles.