Stabilization of well-organized transient micellar phases in CTAB-templated silica and organosilica thin films

Abstract

The influence of some previously reported critical parameters (aging of the silica sol, humidity, % of trivalent precursor) controlling the nature and the degree of organization of mesophases is studied in detail for CTAB-templated silica and organosilicate films prepared by rapid evaporation techniques. It is shown that all of these parameters directly influence the silica-condensation kinetics. Concerning films with the 2D-hexagonal structure belonging to the CTAB–water phase diagram, the mesophase is mainly stabilized by interactions between cylindrical micelles, and the reactivity of the silica sol does not drastically modify the extent of the order in films. In contrast, the formation of a rigid silica network just after the micellar organization appears to be crucial to prepare well-organized films with the 3D-hexagonal or the cubic transient structure. In the latter case, the size and reactivity of silica clusters have to be controlled to obtain rapid gelation in the deposited sol.