Influence of PEG Content on FT-IR Absorption Signals in Silica-Based Materials Synthesized via Sol–Gel Method

The sol–gel route is a chemical technique useful for synthesizing hybrid materials applicable to several fields such as biomedical. Through the sol–gel method, it is possible to tailor the size and control the porosity, as well as, to obtain pure hybrid materials. In this study, several inorganic–organic silica/PEG (polyethylene glycol) hybrids have been synthesized through the sol–gel method, by using tetraethylortosilicate (TEOS) as the SiO₂ precursor. The PEG amount was 6, 12, 24, and 50 wt.% to SiO₂ stoichiometrically calculated. The inorganic phase is well-known in literature as bioactive, while the organic phase improves mechanical performance. The influence of the organic phase has been investigated through the Fourier-transform infrared spectroscopy (FT-IR) in the range of 4000–400 cm⁻¹. A deconvolution study of the main Si─O─Si stretching vibration in the range 1600–800 cm⁻¹ has also been carried out. According to the observation of FT-IR spectra, the changes in the shape of O─H stretching and banding, as well as the presence of CH₂ and CH₃ vibrations in silica/PEG spectra revealed the co-presence of both phases. This finding is strengthened by the presence of C─O bending found in the deconvoluted spectra affecting the intensity and the shape of the Si─O─Si vibration band.