Structure and Solubility in Surfactant‐Free Microemulsions

Klossek, Michael L.; Touraud, Didier; Zemb, Thomas; Kunz, Werner

doi:10.1002/cphc.201200667

Cited by 93 publications

(88 citation statements)

References 42 publications

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“…It can also be noted that the phase diagrams have exactly the same topology than those reported in our last studies [19][20][21][22] concerning the pre-ouzo effect as they result from the mixture of two immiscible molecules, being cosolubilized by a third one, which is miscible with both immiscible liquids.…”

Section: Ternary Phase Diagramssupporting

confidence: 51%

“…The wide composition extension of the well-defined correlation functions is a strong hint in favor of nanostructure fluctuations and not of simple molecular fluctuations close to a demixing line or a critical point. It can also be noted that the extent of these well-established correlation functions covers a larger area in the realms of existence of clear and homogeneous solutions than in our previous studies on water-based systems [19][20][21][22]. Remarkably, correlation functions are even measured for the mixtures 1-heptanol/rapeseed oil, which suggests the formation of pseudo-phases even in these binary systems.…”

Section: Dynamic Light Scattering Experimentsmentioning

confidence: 76%

“…Remarkably, correlation functions are even measured for the mixtures 1-heptanol/rapeseed oil, which suggests the formation of pseudo-phases even in these binary systems. Contrary to the mixture of water, ethanol, and 1-octanol, obviously the formation of nanostructures does not require the mixture of three compounds [19,22].…”

Section: Dynamic Light Scattering Experimentsmentioning

confidence: 96%

“…In previous works [19][20][21][22], we have investigated the presence of nanostructures in different water/ethanol/hydrophobic molecule systems. In the present study, the formation of liquid nanostructures is investigated in media with ethanol and rapeseed oil using dynamic and static light scattering, small-angle neutron scattering and conductivity measurements.…”

Section: Introductionmentioning

confidence: 99%

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Nanostructures in clear and homogeneous mixtures of rapeseed oil and ethanol in the presence of green additives

et al. 2015

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Section: Ternary Phase Diagramssupporting

confidence: 51%

Section: Dynamic Light Scattering Experimentsmentioning

confidence: 76%

Section: Dynamic Light Scattering Experimentsmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

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Nanostructures in clear and homogeneous mixtures of rapeseed oil and ethanol in the presence of green additives

et al. 2015

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“…Close to a critical point, diverging intensities of static light scattering at low angles are measured, and this divergence is also the case in this ternary system (26). However, in critical fluctuations of an unstructured ternary fluid, fluctuations are featureless changes in molecular concentrations.…”

mentioning

confidence: 55%

How to explain microemulsions formed by solvent mixtures without conventional surfactants

Zemb

Klossek

Lopian

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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Ternary solutions containing one hydrotrope (such as ethanol) and two immiscible fluids, both being soluble in the hydrotrope at any proportion, show unexpected solubilization power and allow strange but yet unexplained membrane enzyme activity. We study the system ethanol-water-octanol as a simple model of such kinds of ternary solutions. The stability of "detergentless" micelles or microemulsions in such mixtures was proposed in the pioneering works of Barden and coworkers [Smith GD, Donelan CE, Barden RE (1977) J Colloid Interface Sci 60(3):488-496 and Keiser BA, Varie D, Barden RE, Holt SL (1979) J Phys Chem 83(10):1276-1281] in the 1970s and then, neglected, because no general explanation for the observations was available. Recent direct microstructural evidence by light, X-ray, and neutron scattering using contrast variation reopened the debate. We propose here a general principle for solubilization without conventional surfactants: the balance between hydration force and entropy. This balance explains the stability of microemulsions in homogeneous ternary mixtures based on cosolvents.A dding slightly hydrophobic compounds to water can lead to structureless solutions, aggregate formation, or even, formation of defined structures, such as micelles, in the case where the added compound is a surfactant. In ternary or quaternary mixtures containing at least one type of surfactant, the formation of microemulsions usually occurs in specific parts of the phase diagram. These macroscopically homogeneous, transparent liquids are composed of well-defined microstructures with specific signatures in scattering experiments (1). It was only recently that similar structures, designated as "pre-Ouzo," were found and characterized in ternary mixtures of two partly miscible solvents and one hydrotropic cosolvent (2). In this paper, we present a theory that explains and even predicts the existence of such structures in "detergentless" formulations.Ouzo, Limoncello, and Pommeau liquors are popular in several European countries and produced by maceration of plants with a specific amount of ethanolic solutions containing some waterinsoluble compounds (3). Adding water to those solutions leads to spontaneous formation of fine emulsions with a remarkable stability, a phenomenon that is called the "Ouzo effect" (4). Even common mouthwash products show a similar phenomenon. In common, they entirely clear up on addition of ethanol and get milky with the addition of water (5).Ternary surfactant-free model systems, such as decane-waterisobutoxyethanol [as studied by Shinoda and Kunieda (6)], however, show this Ouzo effect only for specific points in the composition diagram. The precondition for such behavior seems to be the mixture of two miscible (either completely or at least to a large degree) solvents 1 and 2 with a solute that can also be a liquid (7) (e.g., anethole in the case of Ouzo; component 3). This component 3 must be highly soluble in one solvent (e.g., ethanol) but poorly soluble in the other one (e.g., water) (8).Where...

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Nano‐droplet formation in fragrance tinctures

Marcus

Klossek

Touraud

et al. 2013

Flavour & Fragrance J

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Recently it was shown that water–ethanol–long‐chain alcohol mixtures can be significantly structured in a wide range of compositions. This work is an extension of these studies and suggests that some formulated products on the market correspond to these mixtures. We consider the domains of existence of the clear and homogeneous phase of four water–ethanol–perfumery molecules systems, the perfumery molecules being citronellol, citral, geranyl acetate and limonene, as they can be found in perfumery formulations. Dynamic and static light scattering experiments reveal also the presence of nano‐droplets in these ternary tincture systems. Based on these results the presence of nano‐droplets can be expected in Eau de Toilette, Eau de Parfum, and possibly in perfumes. Copyright © 2013 John Wiley & Sons, Ltd.

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Structure and Solubility in Surfactant‐Free Microemulsions

Abstract: Cheers! The combination of static and dynamic light scattering is demonstrated to deliver an unambiguous proof that well-defined domains of two fluids of clearly different composition can exist in surfactant-free ternary mixtures (see picture for diagram), such as Ouzo.

Cited by 93 publications

References 42 publications

Nanostructures in clear and homogeneous mixtures of rapeseed oil and ethanol in the presence of green additives

Nanostructures in clear and homogeneous mixtures of rapeseed oil and ethanol in the presence of green additives

How to explain microemulsions formed by solvent mixtures without conventional surfactants

Nano‐droplet formation in fragrance tinctures

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