Evolution of non-ionic surfactant-templated silicate films at the air-liquid interface

Spontaneous growth of non-ionic surfactant-templated thin films at the air-water interface was investigated using three techniques: Brewster angle microscopy (BAM), time-resolved off-specular X-ray reflectivity and grazing incidence X-ray diffraction (GIXD). Experiments were also carried out to study the evolution of micelles in the subphase solution using small-angle neutron scattering (SANS). Films were prepared in acidic conditions using octaethylene glycol mono-n-hexadecyl ether (C₁₆EO₈) as the surfactant and tetramethyloxysilane (TMOS) as the silica precursor. Three different TMOS-C₁₆EO₈ molar ratios (3.5, 7.1 and 10.8) were studied. Variation of the silica-precursor concentration causes a significant effect on the film-formation time, the solution and film-growth mechanisms and the final film structure.