| Monodisperse, ultrafine, spherical particles of amorphous silica were
produced by the hydrolysis of tetraethyl orthosilicate under a variety
of experimental conditions with methanol, ethanol, 1-propanol and
2-propanol as solvents. 1- and iso-butanol, acetone and 1, 4-dioxan
produced non-spherical agglomerates under equivalent conditions.
The smallest size and narrowest size range of the spherical particles
were observed for the product generated from methanolic solutions.
Attempts were made to correlate solvent characteristics, e.g. polarity
and viscosity with the time lag of precipitation after onset of reaction,
and particle size. It was indicated that under specific conditions, the
nature of the solvent could also determine the nature of the polymeric
aggregation in the precipitated particles. |
