Kinetics of structuring in the sol-gel systems based on tetraethoxysilane with organic additives: I. Sols

This paper reports on the results of theological investigations into the kinetics of gelation of the sol-gel systems based on a water-alcohol solution of tetraethoxysilane (TEOS) modified by a number of metal salts and organic polyhydroxyl compounds, such as glycerol, poly(ethylene glycol) (PEG-300), and hyperbranched aliphatic complex polyol polyethers (HBP-49, HBP-64). It is demonstrated that, at a dispersed phase concentration of approximately 10 wt %, water-ethanol sol-gel systems containing 2-4 g/l of high-molecular additives possess a shear strength and are characterized by anomalous properties in their flow. The gelation time of sols in the presence of organic additives is affected by the ratio between the numbers of OH- hydrophilic and CH3 hydrophobic groups in the polymer molecule, the concentration of the introduced additive, and the electrolyte multivalence. The presence of metal salts enhances the structuring effect of polymers.