Fluorine-free superhydrophobic and water-repellent polymer nanocomposite coatings are developed on different substrates, like stainless steel, glass and polypropylene, utilizing a fluorine-free, silicone-based aqueous polymer emulsion (Protectosil® WS 610), to provide the appropriate hydrophobicity, and silica nanoparticles, to introduce the appropriate roughness; the coatings are prepared by a straightforward dip-coating process. The surface structure and topography of the resulting coatings were investigated using appropriate characterization techniques, while their wettability was evaluated with contact angle measurements. After thermal annealing of the polymer / silica nanocomposite films, the treated surfaces exhibited water contact angles exceeding 150° and very low contact angle hysteresis and roll-off angles, confirming their superhydrophobicity and water-repellence, respectively. Furthermore, the mechanical and chemical durability of the coatings was evaluated, revealing excellent stability under both highly acidic and highly alkaline conditions, as well as sustained performance during abrasion testing, while, more importantly, cytotoxicity testing confirmed the cytocompatibility of the coatings5 with the human skin. These findings demonstrate that Protectosil® WS 610 / silica nanocomposites provide an effective and environmentally friendly route for developing fluorine-free superhydrophobic surfaces. • Successful development of environmentally friendly superhydrophobic and water-repellent nanocomposite coatings based on a new non-fluorinated silicone-based polymer and SiO 2 nanoparticles. • The proposed strategy includes a single-step method for the preparation of the coating formulation, followed by a simple spray deposition process • The nanocomposite coatings exhibited superhydrophobic and water-repellent properties for nanoparticle concentrations in the range 30 – 50 wt% following annealing at 65 °C for 24 h • The polymeric and the annealed nanocomposite coatings remain stable even under extreme acidic or basic pH conditions. • The pure polymer coatings can withstand several abrasion cycles, whereas the nanocomposite coatings lose their superhydrophobic and water-repellent properties under mechanical stress. • Cytocompatibility assessment confirmed that all coatings were safe and suitable for applications with human involvement.
Petsi et al. (Sun,) studied this question.