Compared organization of the molecules of NaDEHP and AOT: Determination of the microscopic organization of the sodium bis(2-ethylhexyl)phosphate molecule in the solid state in the reversed hexagonal liquid crystal state

Lovera, J.; Lovera, Patrick; Gregoire, P.

doi:10.1016/0022-4596(88)90087-4

Cited by 10 publications

(9 citation statements)

References 6 publications

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“…Accordingly, the percentage correlation error was found to be 16, 23, and 29%, respectively, for the three equations assuming that a dimeric structure was formed. At low concentrations (0.11 M ∼ φ = 0.027) all equations are in excellent accord with reported data from the literature. , It is not by accident that eqs 6 and 7 show a good matching trend. This fact can be attributed to the relatively small φ 2,3 values.…”

Section: Resultssupporting

confidence: 89%

“…The aggregation number of the associates estimated according to the proposed model, eq 16, using φ 1,3 values obtained from eqs 5, 6, and 7 versus D2EHPA concentrations are shown in Figure . The hydrocarbon tail, l c , of D2EHPA molecule was taken as 0.59 nm . From this figure it can be seen that the model predicts the molecular structure of D2EHPA in n -dodecane solutions with varied accuracy depending on the φ 1,3 values obtained from the corresponding eqs 5, 6, and 7.…”

Section: Resultsmentioning

confidence: 99%

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Microstructures in the System Water/D2EHPA/Span-80/n-Dodecane

Abou‐Nemeh

Bart

1998

Langmuir

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The solubilization of water by the single ionic amphiphile bis(2-ethyhexyl)phosphoric acid (D2EHPA) and the single nonionic surfactant Span 80 in a nonpolar medium has been investigated. The hydrodynamic, optical, and other various analytical techniques were extensively employed to study the physicochemical nature of the microstructures formed in D2EHPA/n-dodecane/water and Span 80/n-dodecane/water solutions. An analytical model based on geometrical assumptions of the spherical shape of the reversed micelles has been developed. The proposed model correlates, among several others, the aggregation number, and, thus, the size of microstructures with parameters such as the hydrocarbon chain length of the surfactant molecule, its concentration and volume fraction occupied by the reversed micelles, etc., the latter is being estimated from the Einstein viscosity equation and its two modified versions reported by Guth and Simha and Vand. Assuming the spherical shape of the aggregates, the Einstein equation was found to fit the experimental data of the D2EHPA solutions very well; however, Vand's equation was found to be more suitable to fit those of Span 80 solutions. The molecular associates formed by D2EHPA were mostly dimers; however, relatively larger microstructures were formed by Span 80, the higher the concentration the smaller the size with a tendency to leveling off and the shape is nonspherical. The basic structural parameters, that is, the aggregation number, reversed micelle, and water pool radii were derived, and a good agreement between the experimental and the predicted data from the model was found.

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Section: Resultssupporting

confidence: 89%

Section: Resultsmentioning

confidence: 99%

Microstructures in the System Water/D2EHPA/Span-80/n-Dodecane

Abou‐Nemeh

Bart

1998

Langmuir

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“…The reported AOT chain length is 18 Å; hence, there is significant interdigitation of the tails. The headgroup layer has been estimated as approximately 7.1 Å . We therefore conclude that some of the tails may overlap the opposite headgroup regions.…”

Section: Resultsmentioning

confidence: 67%

“…The headgroup layer has been estimated as approximately 7.1 Å. 31 We therefore conclude that some of the tails may overlap the opposite headgroup regions. An illustration is given below.…”

Section: ■ Resultsmentioning

confidence: 73%

An Anionic Surfactant on an Anionic Substrate: Monovalent Cation Binding

et al. 2017

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Neutron reflectometry has been used to study the adsorption of the anionic surfactant bis(2-ethylhexyl) sulfosuccinate cesium salt on the anionic surface of mica. Evidence of significant adsorption is reported. The adsorption is reversible and changes little with pH. This unexpected adsorption behavior of an anionic molecule on an anionic surface is discussed in terms of recent models for surfactant adsorption such as cation bridging, where adsorption has been reported with the divalent ion calcium but not previously observed with monovalent ions.

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“…In addition, the conductivity (in homogeneous electric field) increases nonmonotonically with wo and displays a plateau region in the neighborhood of W O ,~ (1.5 I wo 5 4.0). Furthermore, conductance measurements in inhomogeneous electric field indicated that the aggregates present at w o < 3.0 have a permanent dipole moment which diminishes with increasing water content.…”

Section: Introductionmentioning

confidence: 95%

Electric Birefringence Dynamics of Crystallites and Reverse Micelles of Sodium Bis(2-ethylhexyl)phosphate in Benzene

Feng

Schelly²

1995

J. Phys. Chem.

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Results of single square pulse and reversing pulse electric birefringence experiments on the ternary system of the surfactant sodium bis(2-ethylhexy1)phosphate (or NaDEHP) in benzeneM20 are in agreement with the existence of ca. up to 307 nm long, rod-shaped, dipolar crystallites in solutions below the critical water content (~0 ,~ e 3.0) and with the formation of nondipolar and nonspherical reverse micelles above the WQ. In the range of water content (WO = 0.75-4.5), [NaDEHP] (0.08-0.35 M), and temperature (15-37 "C) investigated, the homogeneous, isotropic solutions exhibit negative birefringence, with the Kerr constants (B) of the order of 1 x V2 m. It is concluded that the plane of the terminal 0-P-0-of the phosphate is perpendicular to the crystallite's major axis. In the range 1.5 < wo 4.5 (where dissolution of the crystallites and the nucleation of the micelles overlap), the relaxations times and amplitudes are too small to be evaluated. Outside that range, the rise and decay signals (in the 0.2-28 ,us range) are double exponential; they are asymmetric for the crystallites but symmetric for the reverse micelles. The magnitudes of the rotational relaxation times indicate that the crystallites break into shorter segments in the initial phase of their forced reorientation by the applied field. Mechanisms are proposed involving polarization, structural changes, and linear clustering (not for the micelles) for the relaxations observed.

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Compared organization of the molecules of NaDEHP and AOT: Determination of the microscopic organization of the sodium bis(2-ethylhexyl)phosphate molecule in the solid state in the reversed hexagonal liquid crystal state

Cited by 10 publications

References 6 publications

Microstructures in the System Water/D2EHPA/Span-80/n-Dodecane

Microstructures in the System Water/D2EHPA/Span-80/n-Dodecane

An Anionic Surfactant on an Anionic Substrate: Monovalent Cation Binding

Electric Birefringence Dynamics of Crystallites and Reverse Micelles of Sodium Bis(2-ethylhexyl)phosphate in Benzene

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