Preparation and wettability examinations of transparent SiO₂ binder-added MgF₂ nanoparticle coatings covered with fluoro-alkyl silane self-assembled monolayer

SiO₂-added MgF₂ nanoparticle coatings with various surface roughness properties were formed on fused silica-glass substrates from autoclaved sols prepared at 100-180 °C. To give it hydrophobicity, we treated the samples with fluoro-alkyl silane (FAS) vapor to form self-assembled monolayers on the nanoparticle coating and we examined the wettability of the samples. The samples preserved good transparency even after the FAS treatment. The wettability examination revealed that higher autoclave temperatures produced a larger average MgF₂ nanoparticle particle size, a larger surface roughness, and a higher contact angle and the roll-off angle.