Sol-gel synthesis and characterization of lamellar mesostructured titania films

This work reports the sol-gel synthesis and characterisation of inorganic/organic mesostructured titania-based layers obtained by the self-assembly of inorganic species and surfactants. Films have been prepared by dip-coating from solutions of prehydrolysed titanium isobutoxide (Ti(i-OC4H9)4) in presence of hexadecyltrimethylammonium bromide (CTAB). The influence of different solvents (2-Butanol, 2-BuOH and tetrahydrofuran, THF) and the effect of hydrolysis ratio (H2O / Ti) on the film structure have been investigated. The structural characterisation of the films was obtained by X-ray Reflectivity (XRR) and 2D X-ray microDiffraction (micro-XRD2). The more relevant result is the formation of lamellar mesostructured titania films. In particular, in the case of the sample prepared from THF sols with the lower hydrolysis ratio, the XRR analysis has evidenced three order of reflections. This finding suggests the formation of a highly ordered lamellar film with 45 Å layer periodicity (d spacing). By means of micro-XRD2 the most intense reflection of crystalline CTAB phase has been detected in all the samples, showing the presence of traces of this phase.