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Published on: March 21, 2016
Ultrastable Water-in-Water Emulsions by Addition of Polyion Complex Micelles
Léna S Vincent1, Vendini Poopalan1, Mariam Koite1
1Soft Matter Sciences and Engineering, ESPCI, PSL University, Sorbonne Université, Paris, France.
Abstract:
We report the use of polyion complex micelles (PICM) obtained by complexation of poly(sodium acrylate) and poly(N-methyl-2-vinylpyridinium iodide-block-ethylene oxide) as novel stabilizers for water-in-water emulsions consisting in poly(ethylene oxide) (PEO) and dextran mixtures in water. PICM concentrations as low as 1 g/L lead to a strong increase of stability for both PEO-in-dextran and dextran-in-PEO emulsions, as they did not display any macroscopic phase separation after several months. Such long term stability is to our knowledge unprecedented in the literature dedicated to water-in-water emulsions. Moreover, increasing the concentration of PICM further induces a decrease in the droplet size, resulting in a strong reduction of the cream-ing or sedimentation rates, and suppression of the coalescence after a few days. The dissociation of PICM at high salt concentration was taken as an opportunity to trigger the destabilization of the water-in-water emulsions by addition of a concentrated salt solution. PEO-in-dextran emulsions displayed more sensitivity to PICM and salt concentrations than dextran-in-PEO emulsions, in terms of both stability and droplet size, indicating that the underlying stabilization mechanisms are different for the two systems.
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A solution is a homogeneous mixture composed of a solvent, the major component, and a solute, the minor component. The physical state of a solution—solid, liquid, or gas—is typically the same as that of the solvent. Solute concentrations are often described with qualitative terms such as dilute (of relatively low concentration) and concentrated (of relatively high concentration).
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