Phase Diagrams for Microemulsions

Safran, S. A.; Turkevich, Leonid A.

doi:10.1103/physrevlett.50.1930

Cited by 199 publications

(100 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Doing this we make use of the fact that away from the 3Φ-region the microstructure of the mixture conforms to droplets close to the emulsification boundary [12,16,44]. At the emulsification boundary the dependence of the size of droplets changes from being determined by composition towards being determined by temperature [26,38,45].…”

Section: The Preferred Curvaturementioning

confidence: 99%

How to calculate phase diagrams for microemulsions — a simple rule

Vollmer¹

1999

Fett/Lipid

View full text Add to dashboard Cite

Section: The Preferred Curvaturementioning

confidence: 99%

How to calculate phase diagrams for microemulsions — a simple rule

Vollmer¹

1999

Fett/Lipid

View full text Add to dashboard Cite

“…[3] for a review) concentrated on a qualitative understanding of the organization of the mixtures into mesoscopic water and oil domains of various topology, into typical sequences of structural transitions upon changing thermodynamic control parameters, and into the mutual wetting properties of the phases. Among other complementary approaches, Landau theories [3,[22][23][24][25] and interfacial descriptions [6][7][8]12,14,17,26] turned out to be particularly successful to address these questions. The latter comprise a phenomenological description based on the bending rigidities (κ, κ) and spontaneous curvature (c 0 ) of the interface ("Helfrich energy") [6,7,18,27], complemented by estimates [12,28,29] of entropic contributions to the free energy and/or terms taking into account long-range (e.g., van-der-Waals) interactions across the mesoscopic domains.…”

Section: Introductionmentioning

confidence: 98%

“…One of the important achievements was the modeling of static and dynamic properties of membrane and vesicle configurations [2], and of structural phase transitions in amphiphilic mixtures [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]. Early work (cf.…”

Section: Introductionmentioning

confidence: 99%

Bending free energy and spontaneous curvature for micelles and microemulsions with weak and strong surfactants

Vollmer

2001

The European Physical Journal E

View full text Add to dashboard Cite

For mixtures of water, oil and non-ionic surfactant the temperature-induced phase separation of a droplet-phase microemulsion into a phase of smaller sized droplets coexisting with a water-or oilrich phase is studied by differential-scanning microcalorimetry. A comparison of theoretical estimates and experimental findings for specific-heat measurements on mixtures containing different types of surfactants (weak and strong) support a broad range of applicability of an interfacial modeling ("Helfrich free energy"), provided a more general expression for the spontaneous curvature of the interface is considered than suggested so far. The model provides then a quantitative interfacial description even for the strongly curved diffuse interface of micelles of weak surfactants.

show abstract

“…When the concentration goes down further the interfacial tension goes up to positive, but low, values and its positive contribution to the free energy of the system can be offset by the entropy of mixing of the many small droplets formed with the continuous medium. This mechanism, however, would allow the droplets to take up an infinite amount of liquid, whereas in practice they show only limited swelling, the remainder of the liquid staying behind as a separate phase, (emulsification failure [25]), thus giving rise to the Winsor I and II equilibria, 0/W + 0 and W/O + W. To explain this limited swelling, we need to take into account the influence of curvature of the interface on y, which becomes an important effect at the low interfacial tensions and the strong curvatures of the interfaces of the nanodroplets.…”

Section: Elementary Theory Of the Stability And Phase Behavior Of Ionmentioning

confidence: 99%

Phase Behavior of Ionic Microemulsions

Lekkerkerker

Kegel

Overbeek

1996

Ber Bunsenges Phys Chem

View full text Add to dashboard Cite

Non-polar oils and water can form thermodynamically stable quasi-homogeneous (colloidal) mixtures (called microemulsions) in the presence of relatively large amounts (several %) of ionic surfactants. If the surfactant contains a single hydrocarbon chain (e.g. Sodium Dodecyl Sulphate) the presence of a non-ionic cosurfactant (e.g. hexanol) and electrolyte (concentration of the order 0.1 M) is essential. With a double chain surfactant (e.g. Aerosol OT) the cosurfactant can be missed. At increasing concentrations of electrolyte and/or cosurfactant the nature of the microemulsion changes from droplets of oil in water via a presumably bicontinuous pattern to droplets of water in oil. It should be obvious that thermodynamic stability requires the interfacial tension between water and oil to be low (order of 0.01 0.1 mN m -1) so that the dispersion entropy can offset the interfacial free energy. At these low interfacial tensions the influence of curvature on the interfacial tensions becomes important. It turns out that a given amount of surfactant (and co-surfactant) can only disperse a limited amount of oil in water or of water in oil or of water and oil into one another and therefore a microemulsion may be in equilibrium with non colloidal oil and/or water phases. In the bicontinuous microemulsion oil and water may have a geometrically irregular interface or they may form lamellae of more or less constant thickness or other structures, such as a "molten cubic phase". These equilibria lead to very interesting, but rather complicated phase diagrams. It will be discussed by what mechanisms the various components of the mixture influence the interfacial tension and promote the stability of the microemulsion and how this depends on the chemical nature of the components.

show abstract

Phase Diagrams for Microemulsions

Cited by 199 publications

References 12 publications

How to calculate phase diagrams for microemulsions — a simple rule

How to calculate phase diagrams for microemulsions — a simple rule

Bending free energy and spontaneous curvature for micelles and microemulsions with weak and strong surfactants

Phase Behavior of Ionic Microemulsions

Contact Info

Product

Resources

About