Amino-containing oligosilsesquioxanes are synthesized by the hydrolytic polycondensation of 3‑aminopropyltriethoxysilane and its cocondensation with phenyltrimethoxysilane in ethanol. According to 1H and 29Si NMR spectroscopy, the oligomers contain incomplete cyclochain structures along with ladder fragments. It is suggested that the spontaneous gelation of the oligomers during long-term storage is due to the intermolecular interactions of siloxane chains with silanol and aminopropyl groups.

According to 1H, 13C, and 29Si NMR spectroscopy, in the hydrolytic copolycondensation of 3‑aminopropyltriethoxysilane and 3-methacryloxypropyltrimethoxysilane, side reactions of addition of amine groups to methacrylate groups (the Michael reaction), as well as partial hydrolysis and transesterification of ester bonds, occur along with the main process of the formation of oligomeric silsesquioxanes. Depending on the ratio of the starting alkoxysilanes, the oligomers are soluble in water (excess of 3-aminopropyltriethoxysilane) or in organic solvents (excess of 3-methacryloxypropyltrimethoxysilane). Mixed oligomers are capable of gelation at room temperature; the duration of the process increases and the content of the gel fraction decreases with an increase in the proportion of 3-methacryloxypropyltrimethoxysilane units in the oligomer molecules.