Microporous silica gels have been synthesized through a nano-particulate sol-gel route. These gels have uniformly distributed and extremely small pores(< 15Â in diameter). Hydrolysis and condensation reactions leading to these gels were carried out in an alkyl silicate-water (ammonia) two phase system. These reactions took place at the alkyl silicate droplet-water interfacial boundary. No alcohol was added. A clear, stable and uniformly distributed colloidal silica suspension having an average particle size less than 6 nm was prepared by this method. Fast hydrolysis, slow condensation and low solubility all contribute to a high supersaturation level and result in the formation of small particles. This process is consistent with classic nucleation theory. When the particles are produced under acidic rather than under basic reaction conditions, smaller particles are formed due to the slower condensation rate and lower solubility of these silica particles in acidic conditions. At the same pH, alkylsilicates having smaller alkyl groups react faster with water leading to smaller primary particles. Homogeneous nucleation conditions are achieved when the water/alkylsilicate ratio is high.
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M.K. Titulaer, J.B.H. Jansen and J.W. Geus, J. Non-Cryst. Solids, 168, 1–13 (1994).
M.A. Anderson and L. Chu, U. S. Patent No. 5 194 200 (16 Mar. 1993).
Q. Xu and M.A. Anderson; J. mater. Reseach. 6, 1073–1081 (1991).
L.C. Klein and N. Giszpenc, American Ceramic Soc. Bull., 69, 1821–1825 (1990).
R.J. Uhlhorn, K. Keizer and A.J. Burggraaf, J. Membr. Sci., 66, 271 (1992).
A. Julbe, C. Guizard, A. Larbot, L. Cot and, A. Giroir-Fendier, J. Membr. Sci. 77, 2–3, 137-153 (1993).
B.E. Yoldas, J. Non-Cryst. Solids, 51, 105 (1982).
P.K. Her. The Chemistry Of Silica. (Wiley Interscience, New York, 1979).
C.J. Brinker and G.W. Scherer, Sol-Gel Science. (Academic Press, Boston, 1990).
W. Stöber, E. Fink and E. Bohn, J.Colloid And Interface Sci. 26, 62 (1968).
C.J. Brinker, K.D. Keefer, D.W. Schaefer and C.S. Ashley, J. Non-Cryst, Solids, 48, 47 (1982).
S. Sakka, K. Aoki, RKozoka and J. Yamaguchi, J. Mater. Sci., 28, 4607–4614 (1993).
A.K. Van Helden, J.W. Jansen and A. Vrij, J.Colloid and Interface Sci., 81 (1980).
A. van Blaaderen and A.P.M. Kentgens, J.Non-Cryst, Solids, 149, 161 (1992).
A. Kaiser and H. Schmidt, J.Non-Cryst, Solids, 63, 261(1984).
D. Avnir and V.R. Kaufman, J.Non-Cryst, Solids, 192, 180(1987).
F.F. Abraham, Homogeneous Nucleation theory: (New York, Academic Press, 1974).
A.G. Walton, The Formation and Properties of Precipitation: (New York, Interscince Publishers,1967).
A.E. Nielsen, Kinetics of Precipitation. (The macmillan company, 1964).
G.H. Bogush, C.J. Brinker, P.D. Majors and D.M. Smith, (Mater. Res. Soc. Symp. Proc. Vol. 180, Materials research society,1990), p.491
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Chu, L., Tejedor-Tejedor, M.I. & Anderson, M.A. Micrqporous Silica Gels from Alkylsilicate-Water Two Phase Hydrolysis. MRS Online Proceedings Library 346, 855–860 (1994). https://doi.org/10.1557/PROC-346-855