Sol–gel synthesis of siloxane–oxide hybrid coatings [Si(CH3)2O·MOx: M = Si, Ti, Zr, Al] with luminescent properties

Abstract

Siloxane–oxide hybrid coatings have been prepared via the hydrolysis–condensation of diethoxydimethylsilane and various metallic alkoxides, M(OR)_n with M = Si, Ti, Zr and Al. The rheological behaviour of the precursor sols and their hydrophobic character due to the presence of methyl groups, allows the formation of films several tens of micrometres thick, with no cracks. Preliminary structural characterizations are presented on the Ti-containing system using MAS NMR and X-ray absorption techniques. Rhodamine 6G and coumarin 4 have been embedded in these films. Some preliminary optical properties (absorption and emission) are presented. Most of the systems exhibit strong fluorescence, even for high dye concentration. This effect seems to be related to the particular structural nature of these matrices.