Author/Authors :
Rigacci، نويسنده , , Arnaud and Ehrburger-Dolle، نويسنده , , Françoise and Geissler، نويسنده , , Erik and Chevalier، نويسنده , , Bruno and Sallée، نويسنده , , Hébert and Achard، نويسنده , , Patrick and Barbieri، نويسنده , , Olivier and Berthon، نويسنده , , Sandrine and Bley، نويسنده , , Françoise and Livet، نويسنده , , Frédéric and Pajonk، نويسنده , , Gérard Marcel and Pinto، نويسنده , , Nicolas and Rochas، نويسنده , , Cyrille، نويسنده ,
Abstract :
An investigation is described into polyethoxydisiloxane (PEDS-Px) silica precursors of aerogels prepared in ethylacetoacetate (etac) under HF conditions and dried under CO2 supercritical conditions. The influence upon the internal nanostructure of aerogels of the number of water molecules (n*) used to synthesize the precursors is studied, as well as that of their volume fraction (xPrec) in solution during the second catalytic step. Correlation between structure and optical transmission (%TR) is necessary to improve optical behavior of monolithic silica aerogels for double-window applications. For this reason, small angle X-ray scattering (SAXS) was performed to characterize the nanostructural silica skeleton, and especially to investigate particle and cluster properties. Optical transmission was also measured to estimate visible optical quality of the samples (%TR). Among other results, it is shown in this study that increasing n* and xPrec contributes to the decrease of the particle and cluster sizes, which indirectly improves %TR in the visible range. These observations confirm and help to explain previously published results.
