Polysiloxanes aryl groups

The technique of potassium hydroxide fusion-reaction gas chromatography has been applied to the determination of alkyl and aryl groups in polysiloxanes. The method involves the quantitative cleavage of all organic substituents bonded to silicon, producing the corresponding hydrocarbons ... 

The TT-electron system-substituted organodisilanes such as aryl-, alkenyl-, and alkynyldisilanes are photoactive under ultraviolet irradiation, and their photochemical behavior has been extensively studied (1). However, much less interest has been shown in the photochemistry of polymers bearing TT-electron substituted disilanyl units (2-4). In this paper, we report the synthesis and photochemical behavior of polysiloxanes involving phenyl(trimethylsilyl)-siloxy units and silicon polymers in which the alternate arrangement of a disilanylene unit and a phenylene group is found regularly in the polymer backbone. We also describe lithographic applications of a double-layer system of the latter polymers. 

Spherical siloxanes (RSiOi 5), with polyhedral frameworks, also called silsesquioxanes, can be used as defined oligomeric models for surface-modified silica gels or polysiloxanes. Whereas silsesquioxanes with alkyl-, aryl-, hydrido-, and trimethylsiloxy groups are known for a long time [1], functionalized octa-[propyl-silsesquioxanes], [X-(CH2)3]g(SiOi.5)g, were synthesized for the first time in 1990 by Weidner, Zeller, Deubzer, and Frey [2]. Octa[(3-chloropropyl)-silsesquioxane], [Cl-(CH2)3]g(SiO, 5)g, could be obtained by hydrolysis of (3-chloropropyl)-trichlorosilane. 

In a modem variant of this vulcanization reaction, polysiloxanes containing a small amount, <1%, of methylvinylsiloxane groups are the starting materials. Aryl or alkyl peroxides are again used to initiate cross-linking, but the chemistry now involves radical addition to vinyl groups on neighboring siloxane chains, depicted in Scheme 1. 

General Electric s Patent EP862185 concerns flame retardant based on an aryl-containing silicone, which may contain triphenyl or diphenyl groups, together with a diorganic polysiloxane compound. It is claimed to improve the flame retardancy of polycarbonate without losing the transparency. 

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