Nanocomposites and nanomaterials

Influence of solvent thermodynamical property on Stober process product
Myronyuk O.V., Kharchenko A.V.,
Chemical Technology of Composite Materials Department,
National Technical University of Ukraine
Igor Sikorsky Kyiv Polytechnic Institute
Peremohy Avenue, 37, Kyiv-03056, Ukraine.
E-mail: whizershines@gmail.com

The Stober method is one of the rational methods for synthesizing silicon dioxide nanoparticles, since simple components are used in the synthesis process and the resulting particle size can be controlled in a wide range by changing the synthesis parameters. The polarity of the solvent is one of the factors affecting the size of the nanoparticles produced [1,2]. In particular, it was shown that as the dielectric constant of the solvent is increased, the particle size decreases.
However, this statement is based on the studies of one homologous series of saturated monohydric alcohols [3]. In addition, the question of the influence of the thermodynamic quality of the solvent received insufficient coverage in previous studies. In this paper, we considered the question from the standpoint of Hansen's approach. 
A study of the morphology of the reaction products showed that an increase in the particle size is observed upon transition from a more polar solvent (isopropanol) to less polar (tetrahydrofuran, xylene). In the region of 10-40% (polar - nonpolar solvent, respectively), the size increases gradually while the shape remains spherical. When this ratio is exceeded, the form changes to a quasispherical and aggregation of particles is observed. At higher levels of non-polar solvent content, the structure becomes irregular and aggregated to a continuous media.

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