In Situ Luminescence Probing of the Chemical and Structural Changes during Formation of Dip-Coated Lamellar Phase Sodium Dodecyl Sulfate Sol−Gel Thin Films

Sodium dodecyl sulfate (SDS)-templated sol−gel films formed by the rapid dip-coating method possess highly ordered lamellar phase structure. Thin film morphology allows both the chemistry and the dynamics of the assembly process to be traced in real time because the steps involved in the formation of the mesostructured material are separated both spatially and temporally. The dynamic processes that occur during film formation can be conveniently monitored by the combination of interferometry and luminescence spectroscopy of the incorporated molecular probes. The luminescence of the probe molecule is measured with a spatial resolution of 100 μm. The selected probes respond to changes in the surrounding solvent composition and polarity, and report these changes by changes in their luminescence characteristics. In situ luminescence spectra taken at various stages during the film formation process monitor changes in the solvent composition, onset of micelle formation, and its transformation to the final mesophase structure. Local molecular motion in the dried films is also examined.