Infrared and Raman spectra of (3,3,3-trifluoropropyl)trimethoxysilane, its sol and xerogel

Organic modified silica sol was prepared by using (3,3,3-trifluoropropyl)trimethoxysilane (TFPTMS) as a precursor in ethanol solution under acidic condition. Infrared and Raman spectra were recorded for the silane coupling agent (SCA), TFPTMS sol and xerogel. Vibrational assignments have been suggested based on the spectral relative intensity, results from the vibrational study of trimethoxypropylsilane (TMPS), similar trifluorocompounds and group frequencies. Low temperature IR spectra revealed the presence of two conformers in TFPTMS. Only one conformer could be identified in the TFPTMS sol and xerogel. Thermal investigation of TFPTMS xerogel with infrared spectroscopic method indicated that the organic part remained essentially unchanged at or below 350 °C but decomposed at or around 450 °C, in agreement with the result from thermal gravimetric analysis (TGA). After the decomposition of the organic branch, the remaining part of the xerogel was composed of silica.

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► TFPTMS sol and gel have been prepared.
► Two conformers were identified in TFPTMS but not in sol and xerogel.
► The progression of TFPTMS sol–gel process could be monitored with IR spectroscopic method.
► TFPTMS xerogel decomposed around 450 °C.