Colloidal systems used as a template in sol- gel synthesis are of great interest owing to their structural diversity, however, they are very sensitive to the experimental conditions. The introduction of a precursor, the release of an organic solvent during hydrolysis, the addition of catalytic additives - acid or alkali, heating lead to rearrangement and phase transformations. As a result, the final state turns out to be significantly changed compared to the initial one, which is not determined a priori. The review is devoted to precursors with ethylene glycol residues, which, unlike tetraethoxysilane used in traditional sol- gel synthesis, are hydrophilic, completely soluble in water, hydrolyzes in neutral aqueous solutions, do not require the addition of a catalyst and heating. Furthermore, unlike ethanol, ethylene glycol, in the quantities in which it is released during hydrolysis, does not lead to the transformation of colloidal systems. The review covers the preparation of the precursors, the issues of sol- gel chemistry and examples of the formation of various functional materials that are synthesized using a simpler protocol in one step under conditions determined by the mineralized template, rather than the sol- gel process. Many of the mentioned silica materials can be synthesized only using ethylene glycol- containing silane.
Yu. A. Shchipunov (Wed,) studied this question.