Journal of Sol-Gel Science and Technology

, Volume 1, Issue 1, pp 35–46 | Cite as

Polymerization-induced phase separation in silica sol-gel systems containing formamide

  • Hironori Kaji
  • Kazuki Nakanishi
  • Naohiro Soga


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.

Key words

Flory-Huggins' theory phase separation spinodal decomposition sol-gel method porous silica gel 


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  1. 1.
    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.Google Scholar
  2. 2.
    S. Komura and H. Furukawa, eds., Dynamics of Ordering Processes in Condensed Matter (Plenum, New York, 1987).Google Scholar
  3. 3.
    H. Tanaka and T. Nishi, Phys. Rev. Lett. 59, 692 (1987).Google Scholar
  4. 4.
    H. Tanaka, Phys. Rev. Lett. 65, 3136 (1990).Google Scholar
  5. 5.
    H. Tanaka and T. Nishi, J. Appl. Phys. 60, 1306 (1986).Google Scholar
  6. 6.
    T. Izumitani and T. Hashimoto, J. Chem, Phys. 83, 3694 (1985).Google Scholar
  7. 7.
    T. Izumitani, M. Takenaka, and T. Hashimoto, J. Chem. Phys. 92, 3213 (1990)Google Scholar
  8. 8.
    K. Yamanaka and T. Inoue, Polymer 30, 662 (1989).Google Scholar
  9. 9.
    K. Yamanaka, Y. Takagi, and T. Inoue, Polymer 30, 1839 (1989).Google Scholar
  10. 10.
    K. Yamanaka and T. Inoue, J. Mater. Sci. 25, 241 (1990).Google Scholar
  11. 11.
    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.Google Scholar
  12. 12.
    K. Nakanishi and N. Soga, J. Am. Ceram. Soc. 74, 2518 (1991).Google Scholar
  13. 13.
    K. Nakanishi, N. Soga, H. Matsuoka, and N. Ise, J. Am. Ceram. Soc. 75, 971 (1992).Google Scholar
  14. 14.
    K. Nakanishi and N. Soga, J. Non-Cryst. Solids 139, 1 (1992).Google Scholar
  15. 15.
    K. Nakanishi and N. Soga, J. Non-Cryst. Solids 139, 14 (1992).Google Scholar
  16. 16.
    C.J. Brinker, G.W. Scherer, and E.P. Roth, J. Non-Cryst. Solids 72, 345 (1985).Google Scholar
  17. 17.
    H. Kaji, K. Nakanishi, N. Soga, and F. Horii, J. Non-Cryst. Solids 145, 80 (1992).Google Scholar
  18. 18.
    J.C. Pouxviel, J.P. Boilot, J.C. Beloeil, and J.Y. Lallemand, J. Non-Cryst. Solids 89, 345 (1987).Google Scholar
  19. 19.
    R.K. Iler, The Chemistry of Silica (Wiley, New York, 1979).Google Scholar
  20. 20.
    C.J. Brinker, J. Non-Cryst. Solids 100, 30 (1988).Google Scholar
  21. 21.
    P.J. Flory, Principles of Polymer Chemistry (Cornell University Press, Ithaca, New York, 1971).Google Scholar
  22. 22.
    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).Google Scholar
  23. 23.
    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).Google Scholar
  24. 24.
    T. Hashimoto, M. Takenaka, and T. Izumitani, J. Chem. Phys. 97, 679 (1992).Google Scholar

Copyright information

© Kluwer Academic Publishers 1993

Authors and Affiliations

  • Hironori Kaji
    • 1
  • Kazuki Nakanishi
    • 1
  • Naohiro Soga
    • 1
  1. 1.Department of Industrial Chemistry, Faculty of EngineeringKyoto UniversityKyotoJapan

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