Incorporation of n-alkanols in reverse micelles in the AOT/n-heptane/water system

Lissi, E. A.; Engel, D.C.

doi:10.1021/la00038a023

Cited by 50 publications

(71 citation statements)

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“…As can be observed, for molecule 1 the value of K b diminishes when water is added (higher W 0 ). The same trend has been found for saturated alcohols (40), where the association constants decrease as the water content increases, the largest changes being observed when W 0 changes from 4 to 8-the water content range in which the micellar interface hydration is changing. We found similar behavior when o-nitroanilines (17) and N -[2-(trifluoromethyl)-4-nitrophenyl]-4-nitroaniline (18) were used as probes.…”

Section: Calculation Of the Binding Constantsupporting

confidence: 76%

“…Thus, the binding for the carotenoid alcohol 1 behaves as due mainly to hydrogen bond complexes with the AOT polar heads at the micelle interface. Moreover, the value of K b for 1 is quite reasonable compared with that obtained for other longchain alcohols (35,40) and follows the trend that the longer the chain of the alcohol the smaller the association constant. This trend can be understood in terms of the location of the polyene chain in a hydrocarbon-like environment.…”

Section: Calculation Of the Binding Constantsupporting

confidence: 75%

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Substituent Effects on Binding Constants of Carotenoids to n-Heptane/AOT Reverse Micelles

Correa

Durantini

Silber

2001

Journal of Colloid and Interface Science

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Section: Calculation Of the Binding Constantsupporting

confidence: 76%

Section: Calculation Of the Binding Constantsupporting

confidence: 75%

Substituent Effects on Binding Constants of Carotenoids to n-Heptane/AOT Reverse Micelles

Correa

Durantini

Silber

2001

Journal of Colloid and Interface Science

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“…This trend was just opposite that observed for K p with increasing oil fractions in the case of the partition of phenol red in o/w benzene/water/sodium dodecyl sulfate/cosurfactant microemulsions (18,19). The observation is, however, similar to the decrease in incorporation of alkanols into reverse micelles of water/AOT/n-heptane with an increase in the water/AOT ratio (23). The decrease in K p with an increase in the water fraction in the present case can be attributed to the water/AOT ratio or an increase in the volume of water compared with the area of the oil-water interface.…”

Section: Which Increases Linearly With [S I ] and Is Given Bycontrasting

confidence: 70%

Partition of bromophenol blue in toluene/water/sodium bis(2‐ethylhexyl)‐sulfosuccinate water‐in‐oil microemulsions

Sarma

Dutta

2005

J Surfact & Detergents

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The partition of bromophenol blue between oil-water interfaces and water droplets in water-in-oil microemulsions of toluene/water/sodium bis(2-ethylhexyl)sulfosuccinate was studied by a spectroscopic method at different water fractions and pH. The partition equilibrium constant, K p , between the two domains decreased considerably with an increase in the water fraction and pH. The decrease in K p with an increase in the water fraction suggests the retention of more dye molecules in water. The decrease in K p with an increase in pH has been attributed to a lower tendency of the base form to associate with the anionic oil-water interface compared with that of the acid form and to an increase in the negative charge density at the oil-water interface at a higher pH.Paper no. S1484 in JSD 8, 277-281 (July 2005). KEY WORDS:Aerosol OT, AOT, bromophenol blue, partition equilibrium, sulfonephthalein dye, toluene, W/O microemulsion.Knowledge of the microstructure of microemulsions is important for their applications in physicochemical and technological processes (1,2). The partition of solutes between the polar droplet core, the apolar bulk solvent, and the interface may affect the microstructure and determine the physicochemical properties of microemulsions. It is also important for determining the possible localization/distribution of reagents and the reaction positions in microemulsions (3). The pseudophase ion-exchange model has been widely used for describing the partition behavior and reaction rates in micellar solutions (4). The method also has been applied to study partition equilibria of solutes between different pseudophases of microemulsions (5-8). Although several reports can be found in the literature on partition equilibria and the acid-base behavior of solutes or indicator dyes in microemulsion systems, most of them involve the partition between all three pseudophases, viz., oil, water, and the oil-water interface (3,9-13).We have developed an equilibrium method that allows us to determine equilibrium constants of the partition of dyes between aqueous and micellar pseudophases. The method has been applied to predict apparent pK a of the dyes in micellar solutions of surfactants of different charge types, where the dye is partially incorporated into the micelles (14-16). Recently, this partition equilibrium approach has been extended to o/w (oil-in-water) microemulsions to gain information on microemulsion microstructure and behavior (17). We have also applied the partition equilibrium approach to study the effects of alcohols as cosurfactants and the change in pH on partition equilibrium of a dye, viz., phenol red in o/w microemulsions (18,19). The partition equilibrium approach is a simple and time-saving approach, and the studies add to the lack of direct information on microemulsion microstructure, with some assumptions widely present in the literature. The studies carried out so far have involved only o/w microemulsions stabilized by anionic surfactants, viz., sodium dodecyl sulfate and sodium dodecyl be...

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“…This medium was choosen in order to match the ogy between water and n-octanol (1), their solubility in conditions employed in the studies of DPPC vesicles (6,7). water (1), and their solubilization in micelles (1)(2)(3)(4), LUVs The alkanols were incorporated up to the desired concentra-(5-7), and reverse micelles (8). From these studies it is tion from a concentrated solution in methanol.…”

Section: Introductionmentioning

confidence: 99%

Interfacial Free Energy of Alkanols in Aqueous Solutions: Dependence with Hydrophobicity and Topology of the Solute

Aspée

Lissi

1996

Journal of Colloid and Interface Science

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Incorporation of n-alkanols in reverse micelles in the AOT/n-heptane/water system

Cited by 50 publications

References 0 publications

Substituent Effects on Binding Constants of Carotenoids to n-Heptane/AOT Reverse Micelles

Substituent Effects on Binding Constants of Carotenoids to n-Heptane/AOT Reverse Micelles

Partition of bromophenol blue in toluene/water/sodium bis(2‐ethylhexyl)‐sulfosuccinate water‐in‐oil microemulsions

Interfacial Free Energy of Alkanols in Aqueous Solutions: Dependence with Hydrophobicity and Topology of the Solute

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