Abstract

TIRADO, D.F; ACEVEDO, D  and  HERRERA, A.P. Modeling the interaction energy of silica nanoparticles prepared in microemulsions. Entre Ciencia e Ingenieria [online]. 2015, vol.9, n.18, pp.95-101. ISSN 1909-8367.

Abstract The interaction energy of silica nanoparticles prepared in microemulsions of organic phase was modeled, using the DLVO theory for spherical particles of equal size. For this purpose, the effect of the organic solvent and the surface active agent (surfactant) used for the coating of the nanomaterials was evaluated. The selected commercial surfactants were the sodium bis-(2-ethylhexyl) sulfosuccinate (AOT) and the p-(1, 1, 3, 3-tetramethylbutyl) phenyl (TX-100). The colloidal systems studied were cyclohexane/AOT, cyclohexane/TX-100, isooctane/AOT, and isooctane/TX-100. Curves of total energy contribution were analyzed considering the interaction energy of van der Waals attraction and repulsion energy due to osmotic layer covering surfactant molecules to the nanoparticles. From these analyzes the curves of total energy for several diameters of nanoparticles as a function of their separation distance were built. These results were compared with the thermal energy of the system, indicating greater stability for the colloidal silica nanoparticles model covered with the TX-100 surfactant and suspended in the organic medium cyclohexane. Thus, it could be expected that the combination of the chemical compounds cyclohexane/TX-100 allow the formation of reverse micelles, which serve for the synthesis of silica nanoparticle providing control size, as well as a system with a good colloidal stability.

Keywords : colloidal stability; nanoparticles; silica; microemulsions; DLVO theory.

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