Abstract
For precursor mixtures containing tetraethoxysilane (TEOS) and phenyltriethoxysilane (PhTREOS), time of gelation can be reduced by up to two orders of magnitude depending on reaction conditions employed when reacting the silicon alkoxide mixture with formic acid instead of water. Results indicate that time of gelation depends on the amount of PhTREOS in the precursor mixture. Within the range of concentrations investigated, an exponential law describes best the dependence of reduced time of gelation on the molar fraction of PhTREOS. Therefore, we conclude that the phenyl ring acts as a steric hindrance to network formation. Raman spectroscopy is used to characterize the reaction between the alkoxide mixture and formic acid. During the acidolysis reaction, ethanol is formed as an intermediate. A preliminary reaction scheme is proposed to account for the time dependence of species involved. Furthermore, Raman spectroscopy is successfully employed to monitor the effects of post-gelation thermal treatment of the gel samples. The effects observed are interpreted with a model of a phenyl ring trapped in a siloxane cage.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
C.J. Brinker and G.W. Scherer, Sol-Gel Science: The Physics and Chemistry of Sol-Gel Processing (Academic Press, San Diego, 1990).
L.L. Hench and J.K. West, Chemical Processing of Advanced Materials (Wiley, New York, 1992).
Y. Abe, T. Namiki, K. Tuchida, Y. Nagao, and T. Misono, J. Non-Cryst. Solids 147&148, 47 (1992).
H.R. Allcock, Adv. Mater. 6, 106 (1994).
J.-C. Panitz, Ph.D. Thesis, Universität Bayreuth, 1994.
K.G. Sharp, Patent WO 9323333, 25.11.1993.
L.N. Zorya, V.A. Onaiko, G.P. Panasyuk, and V.B. Lazarev, Zh. Neorg. Khim. 34, 1953 (1989).
K. Saita and K. Saegusa, Patent EP 273089, 06.07.1988
I. Artaki, M. Bradley, T.W. Zerda, and J. Jonas, J. Phys.Chem. 89, 4399 (1985).
C.A.M. Mulder and A.A.J.M. Damen, J. Non-Cryst. Solids 93, 169 (1987).
M.C. Matos, L.M. Ilharco, and R.M. Almeida, J. Non-Cryst. Solids 147&148, 232 (1992).
T.M. Che, J.J. Rafalko, and P.B. Dorain, Raman and FT-IR Spectroscopy of Rapid Sol-Gel Processes, Ch. 64 in Ultrastructure Processing of Advanced Ceramics, edited by J.D. Mackenzie and D.R. Ulrich (Wiley, New York, 1988), p. 827.
D. Avnir, D. Levy, and R. Reisfeld, J. Phys. Chem. 88, 5956 (1984).
R. Reisfeld and C.K. Jorgensen, Structure and Bonding (Springer, Berlin, 1992), Vol. 77, p. 207.
J.M. McKiernan, S.Y. Yamanaka, E. Knobbe, J.-C. Pouxviel, S. Parvaneh, B. Dunn, and J.I. Zink, J. Inorg. Organomet. Polym. 1, 87 (1991).
C. Rottman, M. Ottolenghi, R. Zusman, O. Lev, M. Smith, G. Gong, M.L. Kagan, and D. Avnir, Mater. Lett. 13, 293 (1992).
U. Narang, R. Wang, P.N. Prasad, and F.V. Bright, J. Phys. Chem. 98, 17 (1994).
T. Fujii and K. Toriumi, J. Chem. Soc. Faraday Trans. 89, 3437 (1993).
J. McKiernan, E. Simoni, B. Dunn, and J.I. Zink, J. Phys. Chem. 98, 1006 (1994).
S. Reul, W. Richter, and D. Haarer, J. Non-Cryst. Solids 145, 149 (1992).
J.-C. Panitz, F. Zimmermann, W. Häfner, F. Fischer, and A. Wokaun, Appl. Spectrosc. 48, 454 (1994).
H. Kriegsmann, K. Licht, and Z. Elektrochem. Ber. Bunsenges. Physik. Chem. 62, 1163 (1962).
J.J.P. Stewart, J. Comput, Chem. 10, 209, 221 (1989). J.J.P. Stewart, J. Comp. Aid. Mol. Design 4, 1 (1990).
T. Clark, VAMP4.4, Universität Erlangen, 1992.
J.-C. Panitz, T. Lipert, and A. Wokaun, J. Phys. Chem. 98, 8817 (1994).
F. Devreux, J.P. Boilot, F. Chaput, and A. Leconte, in Better Ceramics Through Chemistry, edited by B.J.J. Zelinski, C.J. Brinker, D.E. Clark, and D.R. Ulrich (Materials Research Society, Pittsburgh, 1990), Vol. IV, p. 211.
M. Sahimi, Applications of Percolation Theory (Taylor and Francis, London, 1994), p. 11.
B. Schrader, Raman/Infrared Atlas of Organic Compounds, 2nd edition, (Verlag Chemie, Weinheim, 1989).
F.R. Dollish, W.G. Fateley, and F.F. Bentley, Characteristic Raman Frequencies of Organic Compounds (Wiley, New York, 1974).
W. Müller-Warmuth, K.-H. Duprée, and M. Prager, Z. Naturforschung A 39, 66 (1984).
Xmol, Version 1.3.1, Minnesota Supercomputer Center, Inc., Minneapolis, MN, 1993.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Panitz, JC., Wokaun, A. Characterization of the Sol-Gel Process Using Raman Spectroscopy Organically Modified Silica Gels Prepared Via the Formic Acid-Alkoxide Route. Journal of Sol-Gel Science and Technology 9, 251–263 (1997). https://doi.org/10.1023/A:1018355210753
Issue Date:
DOI: https://doi.org/10.1023/A:1018355210753