A recently developed method of synthesizing organic-inorganic hybrid (nano)particles using a nonhydrolytic sol-gel route is reported. A range of silsesquioxane particles with diameters in the range ca. 0.1-2.0 µm has been prepared by reacting organotrichlorosilane precursors with dimethyl sulfoxide, used both as an oxygen donor and as a solvent, in the absence of a catalyst under nonaqueous conditions. Pure silica particles with diameters in the range ca. 100-400 nm have been produced by the same method using silicon tetrachloride as a precursor. Ethoxysilane, silanol, and, sometimes, paraformaldehyde groups are present in incompletely condensed species. The formation of silanol groups is insignificant in silsesquioxanes, but not in "unmodified" silicas. A major advantage of this approach is the absence of catalyst residues and, hence, color in the final product in comparison to the normal Lewis acid-catalyzed route.
The adsorption of polyester onto organically modified silicas (ormosils) and (commercial) fumed silica has been compared utilising ToF-SIMS. The thermodynamics of each system was examined by constructing adsorption isotherm plots which indicated that the adsorption of polyester onto one of the modified silicas used may be a two stage process. Adsorption onto the fumed silica is in accord with the Langmuir model.
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