Some observations on binary and ternary aerosol OT systems

Ekwall, Per; Mandell, Leo; Fontell, Krister

doi:10.1016/0021-9797(70)90024-x

Cited by 311 publications

(160 citation statements)

References 34 publications

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“…Moreover, the diameter increased with an increase in W 0 value , even though it remained almost constant when W 0 value was fixed (n-decane to MEL-A molar ratio was increased) as shown in . This corresponds well to the typical features of W/O microemulsions formed by other surfactants such as AOT 1 [17][18][19] . The type of microemulsion was then checked as follows: 1) Small drops of the microemulsion were put into a test tube containing pure water or pure n-decane and observed.…”

Section: Glycolipid Biosurfactant-based W/o Microemulsionsupporting

confidence: 83%

Formation of W/O Microemulsion Based on Natural Glycolipid Biosurfactant, Mannosylerythritol Lipid-A

Worakitkanchanakul

Imura²,

Morita³

et al. 2008

J. Oleo Sci.

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Mannosylerythritol lipid-A (MEL-A) is a glycolipid biosurfactant abundantly produced from soybean oil by microorganisms at a yield of up to 100 g/L. In this study, the formation of water-in-oil (W/O) microemulsion based on the single component of MEL-A was confirmed using dynamic light scattering (DLS) and freeze fracture electron microscopy (FF-EM). DLS and FF-EM measurements revealed that the diameter of the microemulsion increases with an increase in water-to-surfactant mole ratio (W 0 ) ranging from 20 to 60 nm, and the maximum W 0 value was found to be 20, which is as high as that of soybean lecithin. Glycolipid biosurfactant has a great potential for the formation of W/O microemulsion without using any cosurfactants.

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Section: Glycolipid Biosurfactant-based W/o Microemulsionsupporting

confidence: 83%

Formation of W/O Microemulsion Based on Natural Glycolipid Biosurfactant, Mannosylerythritol Lipid-A

Worakitkanchanakul

Imura²,

Morita³

et al. 2008

J. Oleo Sci.

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“…Since these peaks occur at q1!3 and q1!4 where q1 corresponds to the interplanar distance of 1.54 nm 21 observed in the SAXS spectrum, it can be concluded that this sample forms a reverse hexagonal bidimensional structure, an arrangement frequently observed in pure dichained surfactants. [16][17][18][19] Taking into account this geometry, the lattice parameter (a) through the relation q(10) = 4p/3a turns out to be a = 1.78 nm, so that a schematic representation of the building block of the local structures of the X NOA = 0.5 sample can be sketched (see Fig. 8).…”

Section: Waxs Datamentioning

confidence: 99%

Self-assembly in surfactant-based mixtures driven by acid–base reactions: bis(2-ethylhexyl) phosphoric acid–n-octylamine systems

2013

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Structural and dynamic features of bis(2-ethylhexyl) phosphoric acid (HDEHP)-n-octylamine (NOA) mixtures as a function of the NOA mole fraction (X NOA ) have been investigated by SAXS, WAXS, IR, dielectric spectroscopy and polarized optical microscopy. In the 0 ¡ X NOA , 0.5 range, mixtures are transparent liquids, while the abrupt formation of a waxy solid characterized by an hexagonal bidimensional structure occurs at X NOA = 0.5. Such a composition-induced phase transition results from the synergetic effect of the progressive increase in number density of ordered HDEHP-NOA nanodomains with X NOA . Mainly driven by an HDEHP to NOA proton transfer, the increase of structural order with X NOA arises from the progressive substitution of loosely hydrogen bonded HDEHP-HDEHP aggregates with strongly bonded NOA-HDEHP ones. Analysis of SAXS patterns at temperatures in the 10-70 uC range emphasized that these local structures are scarcely impacted by an increase of thermal fluctuations. Effects due to the steric compatibility between HDEHP and NOA apolar moieties have been highlighted. Overall, the results allow us to emphasize the role of specific polar and apolar interactions joined to steric effects in regulating the molecular organization in surfactant mixtures and can be used to design novel materials with planned physico-chemical properties.

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“…Using a photon correlation experiment, Zulauf and Eicke 29,30,29,30 have studied the aggregation number of AOT micelles over a wide range of concentrations and in different solvents. 27,28 Kotlarchyk et al have used small-angle neutron scattering (SANS) and found an aggregation number of 22 ± 2 monomers per micelle. 31 Conductivity measurements of AOT solutions show that the conductivity scales linearly with the concentration of AOT in the range between 0.1 and 3 wt %.…”

Section: Introductionmentioning

confidence: 99%

Charging Dynamics of Aerosol OT Inverse Micelles

et al. 2015

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Aerosol OT (AOT) is a commonly used surfactant and charging agent in nonpolar liquids. Properties such as the conductivity of AOT suspensions in nonpolar liquids and the behavior of charged AOT inverse micelles at interfaces have been studied recently, but still little is known about the generation dynamics of charged AOT inverse micelles. In this article, the generation dynamics of charged AOT inverse micelles in dodecane are investigated with transient current measurements. At low applied voltages, the generation rate is sufficiently fast to maintain the equilibrium concentration of charged inverse micelles, such that the current scales proportionally with the applied voltage. However, above a threshold voltage the current becomes limited by the generation of charged inverse micelles. Al 2 O 3-coated electrodes are used to achieve these high-voltage current measurements while reducing surface generation currents. The dependency of the resulting generation-limited currents with the micelle concentration and the liquid volume is compatible with a bulk disproportionation mechanism. The measured currents are analyzed using a model based on drift, generation, and recombination of charged inverse micelles and the corresponding generation and recombination rates of charged AOT inverse micelles have been determined. INTRODUCTIONSurfactants are widely used for charging colloidal particles in reflective displays, 1−8 inkjet printing, 9 electrorheological fluids, 10 emulsion polymerization, 11,12 and dry cleaning. 13Over recent years, Anionic sodium bis (2-ethylhexyl) sulfosuccinate (Aerosol OT, AOT) with its double-tail and polar headgroup has attracted increasing attention in aqueous, 14,15 nonaqueous 16−19 and water-in-oil (w/o) microemulsions. 20−26 During the last decades, different methods have been used to investigate the properties of AOT inverse micelles in nonpolar solvents. Peri has combined ultracentrifugation, light scattering, and viscometric measurements of AOT in various solvents, and he has suggested that AOT inverse micelles are monodisperse and spherical.27 Ekwall et al. have found similar results by using light and X-ray scattering. 28 Their studies indicate that the aggregation number N g , the number of monomers per inverse micelle, for AOT is about 20−30. Using a photon correlation experiment, Zulauf and Eicke 29,30,29,30 have studied the aggregation number of AOT micelles over a wide range of concentrations and in different solvents.27,28 Kotlarchyk et al. have used small-angle neutron scattering (SANS) and found an aggregation number of 22 ± 2 monomers per micelle. This difference can be explained by the hygroscopic properties of AOT, which makes the micelles absorb ambient moisture, and increases the conductivity of the AOT solution. 34 The charge-bearing entities are either trace ions such as formed from the dissociation of water into H + and OH − , or even charged AOT molecules that have released a H + . When two micelles collide there is a chance that these charged entities are e...

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Some observations on binary and ternary aerosol OT systems

Cited by 311 publications

References 34 publications

Formation of W/O Microemulsion Based on Natural Glycolipid Biosurfactant, Mannosylerythritol Lipid-A

Formation of W/O Microemulsion Based on Natural Glycolipid Biosurfactant, Mannosylerythritol Lipid-A

Self-assembly in surfactant-based mixtures driven by acid–base reactions: bis(2-ethylhexyl) phosphoric acid–n-octylamine systems

Charging Dynamics of Aerosol OT Inverse Micelles

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