Gel to Glass Transformation of Methyltriethoxysilane: A Silicon Oxycarbide Glass Precursor Investigated Using Vibrational Spectroscopy

Gel to glass transformation of methyltriethoxysilane was investigated using infrared and Raman spectroscopies. The vibrational frequencies of the Si−O network are found to be a sensitive probe of the gel to glass transformation, which is measured to be at ca. 950 °C for this system, under the experimental conditions used for the synthesis. Vibrational data are also compatible with an earlier suggestion of the presence of polyhedral silsesquioxanes type structures embedded in a 3-D network. Further evidence is presented for the formation of Si−CH 2 −Si and Si−C 2 H 4 −Si units during the pyrolysis process.