Investigation of the Silanols Groups of Mesostructured Silica Prepared Using a Fluorinated Surfactant:  Influence of the Hydrothermal Temperature

• Published in: Journal of physical chemistry. C Vol. 111; no. 39; pp. 14380 - 14388
• Main Authors: Blin, J. L, Carteret, C
• Format: Journal Article
• Language: English
• Published: American Chemical Society 04.10.2007
• Subjects: Chemical Sciences; Material chemistry
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/jp072369h

In this study, we have investigated the influence of the hydrothermal temperature on the properties of mesoporous silica materials. Mesostructures with a well-hexagonal array of their channel are prepared if the temperature is lower than 140 °C. Increasing the hydrothermal temperature leads to the formation of wormhole like structures. An increase of the mean pore diameter with heating temperature is also noted. Then we have characterized the silica surface. Results obtained by infrared, Raman, or 29Si NMR spectroscopies provided evidence for a decrease in the amount of silanol groups when the temperature of the hydrothermal treatment is increased. Moreover, the variation of the Q 4/Q 3 ratio shows that silica exhibits a higher degree of condensation when the hydrothermal treatment is performed at higher temperature. However, a thermogravimetric analysis reveals that this enhancement of silica condensation is followed by an increase of the hydroxyl concentration (OH in nanometers squared), which is due to the loss of pore ordering when the hydrothermal temperature reaches 140 °C.