Silanes such as dichlorosilane, tetraethyl orthosilicate (TEOS) could be used to generate free radical intermediates at high temperatures (> 400 oC). The mechanism of radical formation upon the breakdown of Silane at high temperatures is less understood as of yet. In this study, quantum chemical calculations are carried out to determine breakdown reaction mechanisms, reacting species and kinetics of five types of Silane's with varying ligand functionality. In addition, physical properties at different temperatures and pressures of the Silane are predicted. All calculations are performed with density functional theory using GAMESS and COSMOtherm.  We found that the energy required for release of ethoxy radicals from TEOS is higher than that of ethoxy radicals from 2 chloroethyltriethoxysilane and butoxy radicals from dibutoxyacetoxysilane. We observed that the aspect ratio and heat of vaporization of the TEOS, 2 chloroethyltriethoxysilane, dibutoxyacetoxysilane, nbutyl silane and tetramethyldisiloxane  had little influence on the breakdown mechanism and formation of radicals. The calculated boiling point of the Silane's is found to be comparable to experiments. Vapor pressure curves of the Silane's at different temperatures is computed to show the phase behavior of the system.

Quantum chemical modeling: Silane reactions at high temperatures

248th National Meeting (2014)

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