Wettability of MgF₂ porous nanoparticle layers covered with fluoroalkylsilane self-assembled monolayer

Abstract

MgF₂ porous nanoparticle coatings with SiO₂ binder were formed on glass substrates by solgel method. The samples were exposed to fluoro-alkyl silane (FAS) vapor and heated at 150°C to give water repellency. We measured surface roughnesses and static contact angles of water of the samples and examined the relation between surface roughnesses and contact angles. Scanning Probe Microscopy (SPM) confirmed that the FAS treatment had no effect on the surface roughness. In the autoclave temperature region of 100–180°C, the higher the autoclave temperature was, the larger the surface roughness was. The sample prepared from the 100°C autoclaved sol had the minimum surface roughness of 4.1 nm and showed the minimum static contact angle of 115°. On the other hand, the sample prepared from the 180°C autoclaved sol had the maximum surface roughness of 9.5 nm and showed the maximum static contact angle of 134°.