Layered organosiloxanes

Fig. 2.15 Organosiloxane-based layered structure containing high-hyperpolarizable chromophore arrays (A) without inserted layer of refractive index modifying Ga and In oxide layers (B) with inserted layer of refractive index modifying Ga and In oxide layers.

The surface of silica turns hydrophobic on treatment with organo-silicon chlorides. Water vapor adsorption isotherms measured by Stober (219) showed a very marked decrease in reversible adsorption. Less than 0.3 primary adsorption centers per 100 A remained in the surface after covering with the organosiloxane layer. Similar effects were observed in the adsorption of ammonia. About 2.2 silanol groups per 100 A had not reacted with the trimethylsilyl chloride. Nevertheless, the greater part of these had become unaccessible for water vapor. Apparently, they were hidden underneath a trimethylsilyl umbrella. ... 

From the above-stated it follows that synthesis of poly-organosiloxane xerogels with a bifunctional surface layer is possible when a use is made of functional groups of various nature. In this case the composition of a surface layer can be varied over a wide range (in our experiments the SH/NH2 ratio was equal to 4 0, 3 1, 2 2, or 1 3). 

E. Hanelt, F. Sandmeyer, and N. Haberle, Liquid-crystalline nematic organosiloxanes which can be crosslinked to form optically anisotropic polymer layers, US Patent 6 300 454, assigned to Wacker-Chemie GmbH (Munich, DE), October 9, 2001. 

In this section the attention of the reader is called to some particular problems the surface analyst may encounter in analyzing thin surface films treated by various particle beams, essentially in the sputtering regime (from I to 5 keV). In the following subsections some representative studies will be presented in which it is demonstrated how the effects of particle bombardment on surface chemistry can be evaluated, mainly by XPS, for various inorganic compounds (e.g., TiN layers, metal oxides, Cr-O-Si cermet films) and polymeric materials (e.g., polysulfone, polyimide and poly(organosiloxanes)). 

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