Viscosity silicon alkoxides

The Stober route (8) is a well-known method for providing submicro-meter- or micrometer-sized silica particles by hydrolysis and condensation of silicon alkoxide an excess of base and water is used in the reaction. Compared with this method, ours has quite different reaction conditions, namely, the use of a limited amount of water and a large amount of acid. In contrast to the reaction of silicon alkoxide with a large amount of water in basic conditions, Sakka and Kamiya (9) noticed from the measurement of the intrinsic viscosity of silica sols that linear particles or polymers, not round particles, are formed with acidic conditions and the addition of a small amount of water. Therefore, the reaction conditions for this method for producing round micrometer-sized particles is new, and the mechanism of formation of round particles is of interest. 

Figure 12-18. Viscosity vs. shear-rate relation for a silicon alkoxide solution reacted in open state (OP). From Kozuka, (1988), with permission of Elsevier.

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