XPS and FT-IR investigation of silicate polymers

This article presents the results of an investigation of the compositional and structural features of an inorganic polymer synthesized from amorphous silica and KOH. The inorganic polymers were characterized using Fourier transformation infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and X-ray diffraction (XRD). FT-IR investigation of the inorganic polymers showed that an increase in the hydroxide concentration used in the synthesis shifts the position of the maximum absorbance of Si–O bands toward lower wave numbers, indicating the transformation of Q⁴ units to Q³ and Q² units. XPS investigation of the inorganic polymers showed that the total amount of oxygen and potassium present in the sample increased when higher concentrations of hydroxide were used in the synthesis. The O/Si ratio of the inorganic polymers changed from 2 to 2.6 when the KOH concentration was increased from 0.75 to 4 M. The increase in the O/Si ratio can be explained by the greater dissolution of SiO₂ particles leading to the formation of branched polymers and gelation.