Real time GISAXS study of micelle hydration in CTAB templated silica thin films

We have used grazing incidence small angle X-ray scattering (GISAXS) experiments to probe the mesoscopic organization of cetyltrimethyl ammonium bromide (CTAB) templated silica thin films combined to optical interferometry to monitor the macroscopic evolution of these films as a function of relative humidity (RH). The combination of these two experiments permits to address how water can penetrate or quit the silica network during cycling the RH. We report both the fast and the long time responses of these hybrid materials upon cycling the RH. We show that at high RH a hydration layer of one water molecule covers the micelles. Long time response evidences that the silica network remains flexible along the normal to the films for several hours.