Superhydrophobic nanocomposite coating with functionalized SiO₂ nanoparticles embedded in a hybrid matrix of ZnO

There has been an exponential growth in the development of superhydrophobic coatings over the last few decades. Superhydrophobic surfaces developed worldwide consist of complex structures with adequate surface roughness depicting contact angles (>150⁰) at the glass-water interface. Such surfaces are fragile having poor abrasion resistance. In this work, superhydrophobic surfaces were prepared by coating a layer of functionalized SiO₂ nanoparticles embedded in a hybrid inorganic matrix of ZnO nanocrystallites on a glass surface. Specific silanes were used as functionalizing agents instead of fluorine thereby making the coating environment-friendly. The nanocomposite coating consists of a complex solution of (zinc acetate dihydrate) mixed with SiO₂ nanoparticle dispersion. Hydrophilic sites attached with ZnO nanocrystallites helped the coating in adhering to the hydroxyl groups present on the glass surface which improved its abrasion resistance. Functionalized SiO₂ nanoparticles formed a composite network with the ZnO nanocrystallites on the glass surface which roughened the surface to give the desired superhydrophobicity. This route allowed development of a superhydrophobic surface exhibiting contact angles (>150⁰) along with increased resistance to mechanical abrasion.