溶胶-凝胶法改性SiO2膜的润湿性与水汽稳定性

以甲基三乙氧基硅烷(MTES)替代部分正硅酸乙酯(TEOS)作为前驱物,用溶胶-凝胶法制备了MTES改性二氧化硅溶胶和二氧化硅膜,研究了憎水基团的添加量对溶胶体系的稳定性和对二氧化硅膜润湿性以及水汽稳定性的影响.结果表明,随MTES/TEOS摩尔比增大,二氧化硅溶胶的稳定性降低,改性二氧化硅膜的表面自由能显著减小;表面润湿性降低,主要是表面张力中极性力的贡献,FTIR分析表明,这是由于二氧化硅颗粒表面-CH3非极性基团增加所致;在潮湿环境中陈化时,二氧化硅膜接触角的变化及吸水率随MTES/TEOS摩尔比增大而减小,疏水性二氧化硅膜的MTES/TEOS宜为0.8～1.0;AFM形貌分析表明陶瓷支撑体上的二氧化硅薄膜连续,膜表面较光滑、平整.

Surface Wettability and Vapour Stability of Silica Membranes Modified by Sol-Gel Method

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.