Aging of As-Prepared Gels Based on Tetraethoxysilane
in the Presence of Boric Acid

V. I. Rakhimov^a, O. V. Rakhimova^b,*, and M. P. Syomov^a

^aFaculty of Chemistry, St. Petersburg State University, Universitetskii pr. 26, Petrodvorets, St. Petersburg, 198504 Russia

^bSt. Petersburg State Electrotechnical University “LETI”
ul. Professora Popova 5, St. Petersburg, 197376 Russia

*e-mail: olga-18061963@yandex.ru

Received April 24, 2010

Abstract—The influence of additions of boric acid on the aging of as-prepared gels from water–alcohol solu-
tions of tetraethoxysilane has been investigated by the kinetic spectrophotometric method using the reaction
between silica and ammonium molybdate with the formation of a colored -silicomolybdate heteropolyanion
as the reaction product. The distribution of silica over different molecular species at different instants of time
after the gel formation point has been determined within the framework of the kinetic model.

Keywords: hydrolysis and polycondensation, gel formation, chemical kinetics, alkoxysilanes, molecular spe-
cies of silica

DOI: 10.1134/S1087659611020131

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