Abstract

Objectives of this study focused is understanding the mechanisms involved in the stabilization of water / oil interfaces by solid nanoparticles (NPs). Magnesium hydroxide of different sizes and in different electrolyte concentrations were studied and compared, at a model water / cyclohexane interface, in a drop tensiometer. Gradual interfacial adsorption of NPs, initially dispersed in water, were followed by tensiometry and the interfacial behavior of NPs layers were characterized by two-dimensional rheology. Owing to the direct relationship between emulsion stability and the interfacial properties of these layers, different nanoparticulate systems were compared, magnesium hydroxide (Mg(OH)₂) NPs, with different size. In addition, the concentration of electrolytes (NaCl) in the bulk phase was shown to induce a partial NPs aggregation (so-called NPs flocs), with an important incidence on the interfacial layer stability. Theoretical phase shift was calculated from Winter and Chambon models corresponding to a two-dimensional gel behavior at the gel-point. This interfacial gelation results in strengthening the interfacial layer, and is actually a considerable advantage in the stabilization of Pickering emulsions.

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