Structural evolution of silica-gel in the late stages of the gelation process

Infrared spectroscopy has been used to analyze the structural changes in samples prepared by the sol-gel method. Silica gels were prepared from alcoholic solutions of tetraethylorthosilicate (TEOS) keeping the H2O/TEOS and Et-OH/TEOS molars ratios constant and equal to 11.66 and 4, respectively. The IR spectra was carried out in the wet state, before or after gelation while the gel was still impregnated by pore liquor. The IR spectra of these gels, measured as a function of the gelation time, confirm that the final structure of the material is in relationship with the pattern in the late stages of this gelation process. The preliminary results of IR allows some structural considerations to be advanced about the final SiO2 glasses obtained.

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