Calorimetric studies on the state of water in reversed micelles of sodium bis(2-ethylhexyl)sulfosuccinate in various solvents

Goto, Ayako; Yoshioka, Hisashi; Kishimoto, Hiroshi; Fujita, Teruyuki

doi:10.1021/la00038a021

Cited by 54 publications

(34 citation statements)

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“…Microemulsion properties have been widely studied in relation to various surfactant types; [6][7][8][9][10][11] however, the influence of the nonpolar continuous medium has scarcely been examined, and the few studies on it have led to contradictory conclusions. [12][13][14][15][16][17][18][19] Temperature-induced dynamic percolation of water-in-oil microemulsions is known to depend on the properties of the bulk solvent. [20] By using n-heptane, n-octane, and ndecane as continuous media, Moulik and co-workers found the percolation temperature to decrease with increasing length of the alkyl chain in the hydrocarbon.…”

Section: Introductionmentioning

confidence: 99%

“…Similar conclusions were drawn regarding the solution enthalpies of water. [19] A variety of experimental techniques have confirmed that the bulk solvent influences the size and structure of microemulsions. [34,35] In this work, we conducted a systematic study of the influence of the continuous medium on the properties of AOT-based microemulsions involving various solvents, including alkanes (n-heptane, isooctane, and n-dodecane), cycloalkanes (cyclopentane, cyclohexane, and cycloheptane), aromatic hydrocarbons (toluene as well as o-, m-and p-xylene), trichloromethane and tetrachloromethane.…”

Section: Introductionmentioning

confidence: 99%

“…1 H NMR and 13 C NMR spectroscopy allowed us to elucidate the properties of water [36] and the AOT molecule, [19,37] respectively, in the microemulsions. The latter technique provided information about the local environment of each individual nucleus.…”

Section: Introductionmentioning

confidence: 99%

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Influence of the Oil on the Properties of Microemulsions as Reaction Media

2006

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The influence of the nature of the continuous medium on various properties of a wide range of water‐in‐oil (w/o) microemulsions was examined. 1H NMR spectroscopy allowed to determine the properties of water in the studied systems and the way they are affected by the solvent to be elucidated. Changes in interfacial polarity were examined from the 13C NMR signals of the surfactant molecule sodium bis(2‐ethylhexyl)sulfosuccinate (AOT). Chemical shifts were found to vary with the water content of the microemulsion. The variation of the carbon chemical shift as a function of the water‐to‐surfactant concentration ratio (W) was used as an indirect measure of polarity changes at the microemulsion interface. The kinetic effects of the microemulsion composition on the solvolysis of anisoyl chloride were studied, and the reagent was found to react with water at the microemulsion interface alone. Based on both kinetic and NMR results, the solvolysis rate constants of anisoyl chloride decrease with increasing penetration of the oil into the interface. Also, the resonance signals for the water H atoms were found to change in parallel with the solvolysis rate constant for anisoyl chloride. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Influence of the Oil on the Properties of Microemulsions as Reaction Media

2006

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“…For the classical microemulsions FT-IR studies suggest that the reverse water interior has a multilayered structure, consisting of interfacial, intermediate, and core water. 19,20,21 Diferent spectra displayed in Figure 6 show the absorption bands characheristic for fuctional groups in molecular stucture of present compounds of ternary system citronellol, ethanol, and water. The stretching refering to an OH-group is in the range 3000-3700 cm -1 represent the stretching of an OH-group in molecules of citronelol, ethanol, and water.…”

Section: Characteristic Ft-ir Spectra Of Microemulsionsmentioning

confidence: 99%

The Nanostructure Studies of Surfactant-Free-Microemulsions in Fragrance Tinctures

Bošković

Sokol

Touraud

et al. 2016

ACSi

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As it was shown recently that nanostructures can exist in water-ethanol-citronellol tinctures, a deeper investigation of these media was performed using conductivity, UV-Vis and FT-IR spectroscopy techniques. Different regimes of conductivity, depending on the water content, an increase of the polarity of the polar pseudo-phase with increasing water content, and even the presence of free water molecules at higher water content are observed, just as in classical surfactant-based microemulsions. The percolation model, generally used to fit conductivity data in surfactant based microemulsion having a weak interfacial film, can be used to fit our conductivity data below a critical water content (φ w p ) with a critical exponent typical of dynamic percolation. In presence of higher water contents, superior to φ w p , obtained conductivity data cannot be fitted neither with a static nor a dynamic percolation model. As in surfactant-based microemulsions, an increase of polarity of the microenvironment with increasing water content can be postulated using respectively the UV-Vis wavelength absorption band (λ max ) of methyl orange and performing FT-IR spectra.

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“…Reversed micelles are very dynamic in contrast with the liposome system and the enzyme kinetics are not affected by the exchange processes between reversed micelles. The physical properties and sizes of water pools can be controlled by changing W 0 (=[water]/[surfactant] molar ratio) [4][5][6][7]. As W 0 increases, not only do sizes of the reversed micelles and the water pools increase, but also the micropolarity increases and the microviscosity decreases with the appearance of free water in the center of water pool [8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%