Surface Wettability and Vapour Stability of Silica Membranes Modified by Sol-Gel Method
溶胶-凝胶法改性SiO2膜的润湿性与水汽稳定性

Silica sols and silica membranes modified by methyltriethoxysilane(MTES) were prepared by acid catalysed co-hydrolysis and condensation reaction of tetraethylorthosilicate(TEOS) and MTES. The influences of hydrophobic group content on the stability of the silica sols and the surface wettability and vapour stability of the silica membranes were investigated. The results show that the stability of silica sols decreases with MTES/TEOS molar ratio increasing. As MTES/TEOS molar ratio increasing, the surface free energy and surface wettability of the silica membranes decrease greatly. It is mainly because the polar force in surface tension decreases which results from the increase of CH3 nonpolar group on the surface of silica particles shown from FTIR analysis. When the silica membranes age in moist condition, the changes of contact angles and water shoulcl be decrease with MTES/TEOS molar ratio increasing. For hydrophobic silica membranes, MTES/TEOS molar ratio should be controlled between 0.8 and 1.0. AFM image shows that the silica membrane on the ceramic support is continuous and the surface is relatively even and smooth.