Hydrothermal stability of mesostructured silica prepared using a nonionic fluorinated surfactant

In this study, we have investigated the influence of the temperature during the synthesis on the hydrothermal stability of mesostructured silica prepared from a system based on nonionic fluorinated surfactant. Results obtained by SAXS, nitrogen adsorption–desorption analysis and infrared spectroscopy show that when the temperature is increased the hydrothermal stability of the recovered material is enhanced. Indeed, as soon as the treatment into boiling water begins, the structure of the sample synthesized at 80 °C is altered, while the material synthesized at 100 °C is very stable up to 24 h. This behavior has been attributed to a higher degree of silica condensation and to a decrease of both the number of silanol groups and the microporosity.A comparison of the characteristics of the materials obtained with both hydrogenated and fluorinated surfactants also evidences that the lather are more stable when treated with boiling water.