SYNTHESIS AND CHARACTERIZATION OF SILOXANE TITANIA MATERIALS

Diethoxydimethylsilane and titanium isopropoxide have been used for preparation, via the sol-gel process, of mixed siloxane-titania materials. Depending on the Ti/Si molar ratio, flexible to brittle gels can be obtained. The rheological properties of the sols can be adjusted in order to obtain films and transparent monoliths. Due to the high amount of hydrophobic methyl groups in these materials, thick films with an average thickness of 20 mum can be obtained. These films have been used for laser dye matrices. A characterization of the various steps of the hydrolysis-condensation process as well as of the structure of the final solid gel determined by liquid and solid state NMR and TiK edge X-ray absorption spectroscopy are presented. A structural model for the gel is proposed mainly based on siloxane chains and TiO2 based particles. Optical properties of Coumarin 4 and Rhodamin 6G incorporated in such films are discussed.