Hydrolysis of tetraethoxysilane in various associated media of diols

Objectives. To investigate the specific features of tetraethoxysilane (TEOS) hydrolysis in associated media of saturated diols and their esters in acidic media. Propylene- and butylene glycols and ethylcarbitol were selected as associated systems. Methods. Association, hydrolysis, and condensation processes in the TEOS–diol system were studied by potentiometry, infrared spectroscopy, and dynamic light scattering in liquid media. The acidic environment was created by adding HCl in the amount not exceeding 0.3 wt %. Results. The hydrolysis of TEOS in associated alcohol media is limited by the reaction that yields silanol (RO) 3 SiOН, which further interacts with the associated diol. This results in the incorporation of (RO) 3 SiO groups into the hydrogen bond network of diols. This is confirmed by a decrease in the self-association of diols with a decrease in size in the diol–(RO) 3 SiO domains of up to 1–7 μm. Conclusions. The use of diols as a reaction medium for TEOS with a low content of H 2 O in acidic media limits the depth of hydrolysis and condensation, which increases the possibility of esterification reactions of diol with alkoxy derivatives of silanols. The decreased number of hydroxyl groups during the transition from diols to their esters has a significant effect on the degree of association.