Investigation of wettability and optical properties of superhydrophobic polystyrene-SiO₂ composite surfaces

Polystyrene coatings with varying SiO₂ nanoparticle contents were prepared by spin coating technique and their wettability and optical properties were investigated. Superhydrophobic surfaces were achieved with water contact angle values higher than 168° and optimum nanoparticle content was indicated for the highest light propagation and water repellency. Higher CAH values were calculated for hydrophobic surfaces due to their rough surface morphology, however in the case of superhydrophobic surfaces, CAH values were calculated lower. Herein absorption occurred below 300 nm, beyond that all samples displayed wide range of transparency as their nanoparticle content change. In general, the transmittance and reflectance values of the films increased with the decrease in the silica content for the almost same coating thicknesses. Due to the aggregation of the nanoparticles, spectral transmittance values of films that have silica content larger than 85% SiO₂ are lower than the others.