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M. Lomoschitz, U. Schubert:
"Highly Porous Hybrid Sol-Gel Thin Films";
Poster: Einsteins in the City 2, New York, USA; 30.10.2007 - 31.10.2007.

The application of sol-gel films in gas sensing and adsorption processes is very important due to the environmentally friendly processing, simple deposition techniques and very good adhesion properties to substrate. The most important feature of the sol-gel process in adsorption process is that a variety of functional organic groups can be incorporated into the inorganic matrix and enhance the adsorption of volatile compounds. For the manufacture of hybrid sol-gel thin films different silicon and zirconium precursors are chosen. These precursors are hydrolyzed and condensed in the presence of a non-ionic surfactant which is used to induce porosity into the system during evaporation induced self-assambly (EISA). The determination of optimal conditions is achieved by varying the initial sol conditions as well as external conditions during film formation. The incorporation of different organic functionalities into the inorganic framework is obtained by a two step synthesis procedure. The organic functionality is introduced by using organically modified silicon precursors. This allows the organic group to be incorporated into the inorganic network by co-condensation during sol-gel processing. After film formation and template removal, incorporation of a second organic functionality can take place by selective modification of zirconium sites. Organic functionalities are characterized by spectroscopic methods, such as NMR and IR spectroscopy. Nitrogen adsorption / desorption measurements at 77K are used for determination of surface area and pore shape. The interactions between template and different organic functionalities as well as influence of the template concentration on the film structure are investigated by SAXS. The surface properties are investigated by scanning electron microscopy SEM.