PRODUCTION, CHARACTERIZATION, AND UTILIZATION OF AEROSOL-DEPOSITED SOL-GEL-DERIVED FILMS

A new aerosol-based deposition method, for the production of sol-gel-d erived films under ambient conditions, has been developed. Tetraethyl orthosilicate (TEOS) and N-octyltriethoxysilane (TrEOS-C-8)-derived so l-gel-processed films were produced using the new technique and compar ed to films produced by a conventional spin-casting approach. All film s were characterized using scanning electron microscopy, profilometry, electron spectroscopy for chemical analysis (ESCA), diffuse-reflectan ce infrared Fourier transform spectroscopy, and steady-state fluoresce nce spectroscopy. Sol-gel-derived films produced using the aerosol-bas ed method were uniform, and their 'ihickness could be controlled betwe en 0.6 and at least 3.0 mu m. Spin casting of the neat sol-gel-process ed solutions generally yielded more thick (2.0 +/- 0.10 mu m) films, b ut these thicker films were of poorer optical quality and very often m ore highly cracked. ESCA data demonstrate surface segregation of the C -8 moiety within the TrEOS-C-8-derived films. This segregation phenome non is much more pronounced in the aerosol-generated films. A scenario is proposed where the distribution of and/or the dynamics/solvation o f the C-8 residue within the aerosol droplet vs the bulk cast film are very different and lead to the segregation. Static fluorescence exper iments demonstrate that several dopant classes can be incorporated dir ectly into the sol-gel-processed solution and aerosol deposited. All r esults are also consistent with films that are heterogeneous on a mole cular level. The utility of aerosol-deposited, sol-gel-derived films a s a chemical sensing platform is demonstrated using fluorescence quenc hing of entrapped pyrene by O-2.