Abstract
Silica gels with well-defined pores both in micrometer and nanometer ranges were obtained by acid-catalyzed hydrolysis and polymerization of tetramethoxysilane in the presence of formamide. The micrometer-range structures of these gels are studied in terms of the phase diagram of the quasi two-component system, namely solvent-rich and silica-rich end compositions. The resulting interconnected structures and aggregates of particles are related to the occurrence of spinodal phase separation. The composition region that gave interconnected structures for the present system was much more limited and their characteristic sizes were much smaller than those for the previously reported systems containing an organic polymer. These results could be explained qualitatively by the effect of the degree of polymerization on the Flory-Huggins' type free energy change of mixing.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
J.D. Gunton, M. San Miguel, and P. Sahni in Phase Transition and Critical Phenomena, edited by C. Domb and J.H. Lebowitz (Academic, London, 1983), vol. 8.
S. Komura and H. Furukawa, eds., Dynamics of Ordering Processes in Condensed Matter (Plenum, New York, 1987).
H. Tanaka and T. Nishi, Phys. Rev. Lett. 59, 692 (1987).
H. Tanaka, Phys. Rev. Lett. 65, 3136 (1990).
H. Tanaka and T. Nishi, J. Appl. Phys. 60, 1306 (1986).
T. Izumitani and T. Hashimoto, J. Chem, Phys. 83, 3694 (1985).
T. Izumitani, M. Takenaka, and T. Hashimoto, J. Chem. Phys. 92, 3213 (1990)
K. Yamanaka and T. Inoue, Polymer 30, 662 (1989).
K. Yamanaka, Y. Takagi, and T. Inoue, Polymer 30, 1839 (1989).
K. Yamanaka and T. Inoue, J. Mater. Sci. 25, 241 (1990).
For example, T. Nishi and T.K. Kwei, Polymer, 16, 285 (1975) for LCST system and S. Saeki, N. Kuwahara, S. Konno, and M. Kaneko, Macromolecules, 6, 589 (1973) for UCST-LCST coexisting system.
K. Nakanishi and N. Soga, J. Am. Ceram. Soc. 74, 2518 (1991).
K. Nakanishi, N. Soga, H. Matsuoka, and N. Ise, J. Am. Ceram. Soc. 75, 971 (1992).
K. Nakanishi and N. Soga, J. Non-Cryst. Solids 139, 1 (1992).
K. Nakanishi and N. Soga, J. Non-Cryst. Solids 139, 14 (1992).
C.J. Brinker, G.W. Scherer, and E.P. Roth, J. Non-Cryst. Solids 72, 345 (1985).
H. Kaji, K. Nakanishi, N. Soga, and F. Horii, J. Non-Cryst. Solids 145, 80 (1992).
J.C. Pouxviel, J.P. Boilot, J.C. Beloeil, and J.Y. Lallemand, J. Non-Cryst. Solids 89, 345 (1987).
R.K. Iler, The Chemistry of Silica (Wiley, New York, 1979).
C.J. Brinker, J. Non-Cryst. Solids 100, 30 (1988).
P.J. Flory, Principles of Polymer Chemistry (Cornell University Press, Ithaca, New York, 1971).
K. Nakanishi, H. Kaji, and N. Soga, in Ceramic Transactions, Vol. 31, Porous Materials, edited by K. Ishizaki et al. (American Ceramics Society, Ohio, 1993).
M. Takenaka, K. Tanaka, and T. Hashimoto in Contemporary Topics in Polymer Science, Vol. 6, Multiphase Macromolecular Systems Symposium, edited by W.M. Culberston (Plenum, New York, 1989).
T. Hashimoto, M. Takenaka, and T. Izumitani, J. Chem. Phys. 97, 679 (1992).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Kaji, H., Nakanishi, K. & Soga, N. Polymerization-induced phase separation in silica sol-gel systems containing formamide. J Sol-Gel Sci Technol 1, 35–46 (1993). https://doi.org/10.1007/BF00486427
Issue Date:
DOI: https://doi.org/10.1007/BF00486427