Effect of silica and heat treatment on PS-SiO₂ wetting behavior

The wetting behavior of solid surfaces by a liquid is a very important aspect of surface chemistry and surface geometrical structure. In the present study, polystyrene-silica (PS-SiO₂) nanocomposite coatings with varying degrees of wettability are prepared by a simple and cheap spraying process without the use of sophisticated equipments. Both PS and SiO₂ are cheaper and readily available chemicals. Silica source, silica content and heat-treatment temperatures are varied to modulate the surface wettability of the composite coatings. These variations resulted in surfaces with hydrophilic, hydrophobic, superhydrophobic and sticky hydrophobic properties. The coatings are characterized for contact angle, sliding angle, surface roughness, hardness and adhesion. The microstructure of the coatings was studied by using field emission scanning electron microscopy. The results indicate that the surface prepared by 1:2 (PS:SiO₂) composition and dried at room temperature exhibited hydrophilic properties. The same surfaces on heat treatment exhibited superhydrophobic property, and with time, one of the silica surfaces became sticky hydrophobic. Furthermore, supplementary information is available at http://www.icevirtuallibrary.com/upload/10.1680si.12.00011_SupplementaryInformation.pdf