Effects of heat treatment of silica-based glasses on their static and dynamic wettability

Abstract

Heat treatment of silica-based glasses affects their wettability. In this study, the static and dynamic wettabilities of glass before and after heat treatment were investigated using different probe solutions to evaluate the effect of heat treatment on wettability. Commercially available silica-based glasses were subjected to heat treatment at various temperatures for 1 h. Heat treatment affected the surface roughness of the glass, which depended on the treatment temperature. The treated glass exhibited a higher surface free energy compared to the untreated glass, independent of the treatment temperature. Compared to the untreated glass, the static contact angles for water, ethylene glycol, and diiodomethane of the treated glasses decreased, and those of hexadecane increased. These results suggest the different interface formation, such as Wenzel or Cassie states, by the probe solutions. The dynamic behavior of water and ethylene glycol in the treated sample resulted in the spreading of droplets on the surface. The nanoscale surface roughness of the glass plays an important role in the spreading of water droplets on silica-based glasses. The change in the surface roughness of the silica-based glass and the selection of the probe solution affected the static and dynamic wettabilities after heat treatment.