Nonfluorinated Robust Ag@SiO ₂ Core–Shell/Polydimethylsiloxane Transparent Superhydrophobic Coating for Multiple Applications

Transparent coatings with self-cleaning, antifouling, and anticorrosion properties hold significant potential for various outdoor applications such as solar panels, automotive surfaces, and windshields, etc. However, their broader adoption is hindered by challenges, including low optical transmittance and the frequent use of environmentally harmful fluorinated compounds. To address these limitations, in this work, we fabricated a transparent, nonfluorinated, robust superhydrophobic coating synthesized via a simple and eco-friendly process. A suspension of Ag@SiO2 core–shell nanoparticles and polydimethylsiloxane (50–200 mg/0.5 mL) was spin-coated onto glass and mild steel substrates at 1000 rpm for 30 s, followed by calcination at 400 °C. The resulting micro-/nano surface exhibited a water contact angle (WCA) of 156.8° ± 1.3°. The coating achieved an average optical transmittance of 91% in the visible range (400–800 nm) and demonstrated excellent thermal stability between 50 and 200 °C. Moreover, the coating retained its superhydrophobic properties under acidic and alkaline conditions (pH 1–9), prolonged outdoor exposure (30 days), mechanical stress from ultrasonication (40 kHz), cross hatch adhesion test (ASTM D3359), sand flow impact test showcasing durability in self-cleaning and antifouling behavior. High-speed imaging captured droplet impact/bouncing dynamics, while impact pressure and bouncing behavior at varying heights was simulated using COMSOL Multiphysics. Additionally, Ag@SiO2/PDMS coatings applied on mild steel exhibited remarkable anticorrosion performance, with a significantly reduced corrosion rate in a 3.5 wt % NaCl solution, highlighting their potential for sustainable outdoor self-cleaning and anticorrosion applications.