Hexagonally organised mesoporous aluminium-oxo-hydroxide thin films prepared by the template approach.: In situ study of the structural formation

Mesoporous organised aluminium oxide based thin films have been prepared by combining the dip-coating method, the sol-gel chemistry and the template approach. The oxide network is composed of aligned-with-the-surface cylindrical pores compacted in the 2D-hexagonal p6m space group. AlCl3 has been chosen as precursor and Brij 58 was used as structuring agent. Once deposited, films were treated to eliminate the organic surfactant and to stiffen the inorganic oxide structure. The final films are around 100 nm thick, exhibit an overall excellent optical quality, and undergo a contraction that transforms the hexagonal p6m original mesostructure into a centred rectangular c2m one, without significantly altering the degree of pore organisation. The structure was deduced from TEM and XRD in theta-2theta and transmission modes. The time-resolved formation of the film and the structure was simultaneously followed by in situ SAXS (synchrotron radiation) and interferometry. XRD, FTIR, Al-27 NMR and RBS analyses allowed characterisation of the chemical composition of the present system at different stages of its evolution. This work shows that the meso-organisation is highly humidity dependent and that as-prepared hybrid films present a significant flexibility.