This paper surveys a few of the current issues in sol-gel reaction kinetics. Many times seemingly modest changes in reactants or reaction conditions can lead to substantial differences in the overall reaction rates and pathways. For example, qualitative features of the reaction kinetics can depend on catalyst concentration. At very high acid-catalyst concentrations, reverse reactions are significant for TMOS solgels, while for moderate acid-catalyst concentrations, reverse reactions are substantially reduced. The reaction kinetics of two similar tetraalkoxysilanes: tetramethoxysilane (TMOS) and tetraethoxysilane (TEOS), can be markedly different under identical reaction conditions. Under acid-catalyzed reaction conditions, a TMOS sol-gel undergoes both water- and alcoholproducing condensation reactions while a TEOS sol-gel undergoes only water-producing condensation. The early time hydrolysis and condensation reactions of a TMOS sol-gel are statistical in nature and can be quantitatively described by a few simple reaction rate constants while the reaction behavior of a TEOS sol-gel is markedly nonstatistical. A comprehensive theory of sol-gel kinetics must address these diverse experimental findings.
This is a preview of subscription content, access via your institution.
Buy single article
Instant access to the full article PDF.
Tax calculation will be finalised during checkout.
R. A. Assink and B. D. Kay in Better Ceramics through Chemistry, edited by C. J. Brinker, D. E. Clark, and D. R. Ulrich (Mater. Res. Soc. Proc. 32, Elsevier Science, NY, 1984) p. 301.
L. W. Kelts, N. J. Effinger, and S. M. Melpolder, J. Non-Cryst. Solids 83, 353 (1986).
W. G. Klemperer and S. D. Ramamurthi in Better Ceramics through Chemistry III, edited by C. J. Brinker, D. E. Clark, and D. R. Ulrich (Mater. Res. Soc. Proc. 121, Mater. Res. Soc, Pittsburgh, Pennsylvania, 1988) p. 1.
C. A. Balfe, K. J. Ward, D. R. Tallant and S. L. Martinez in Better Ceramics through Chemistry II, edited by C. J. Brinker, D. E. Clark, and D. R. Ulrich (Mater. Res. Soc. Proc. 73, Mater. Res. Soc, Pittsburgh, Pennsylvania, 1988) p. 619.
R. A. Assink and B. D. Kay, J. Non-Cryst. Solids 107, 35 (1988).
R. A. Assink and C. J. Brinker, unpublished results.
R. A. Assink and B. D. Kay, J. Non-Cryst. Solids 99, 359 (1988).
J. C. Pouxviel and J. P. Boilot, J. Non-Cryst. Solids 94, 374 (1987).
B. D. Kay and R. A. Assink, J. Non-Cryst. Solids 104, 112 (1988).
About this article
Cite this article
Assink, R.A., Kay, B.D. Current Issues in Sol-Gel Reaction Kinetics. MRS Online Proceedings Library 180, 21 (1990). https://doi.org/10.1557/PROC-180-21