Bending of ionic surfactant monolayers

Daicic, John; Fogden, Andrew; Carlsson, Ingemar; Wennerström, Håkan; Jönsson, Bengt

doi:10.1103/physreve.54.3984

Cited by 47 publications

(56 citation statements)

References 53 publications

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“…The undulating motion is also important in systems of ionic surfactant monolayers, such as microemulsions. However, previous studies on such systems (27)(28)(29) analyzed the electrostatic contributions without corrugation. The effects of slight deformation can be examined by the perturbation about the spherical shape and are currently under investigation.…”

Section: Fig 4 the Dimensionless Interaction Energy For Variousmentioning

confidence: 97%

The Electrostatic Interactions between Two Corrugated Charged Planes

Tsao

1999

Journal of Colloid and Interface Science

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Section: Fig 4 the Dimensionless Interaction Energy For Variousmentioning

confidence: 97%

The Electrostatic Interactions between Two Corrugated Charged Planes

Tsao

1999

Journal of Colloid and Interface Science

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“…[17][18][19][20] Moreover, we will assume that both lipid and surfactant are nonionic so that we will not consider any possible effects of electric charges of polar heads. 21 To characterize the composition of the system, we use the area fraction occupied by surfactant:…”

Section: The Modelmentioning

confidence: 99%

Shape of Phospholipid/Surfactant Mixed Micelles: Cylinders or Disks? Theoretical Analysis

1997

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We develop a theoretical model for the solubilization of phospholipid bilayers by micelle-forming surfactants. Cylindrical micelles, disklike micelles, and spherical micelles are considered as alternative resultant structures. The main question addressed is, what kind of micelles can be expected under various thermodynamical conditions? Our analysis is based on a theoretical model that accounts for Helfrich energy of curvature of amphiphile monolayers and for the entropy of mixing of lipids and surfactants in mixed aggregates. We conclude that for usual values of the elastic parameters of amphiphile monolayers cylindrical micelles are the most probable aggregates resulting from micellization of phospholipid by surfactants. This conclusion is consistent with available experimental data. Conditions of formation of disklike and spherical micelles are also determined. IntroductionAmphiphiles tend to self-assemble in aqueous solutions, mostly due to the hydrophobic effect. 1 In the resultant aggregates, the amphiphilic molecules are packed as monolayers, where their hydrophobic moieties are shielded from contact with the external aqueous medium by the polar head groups. Depending on their molecular structure and interactions, the amphiphiles form aggregates of different shapes. [2][3][4] Most of the biological amphiphiles (phospholipids) self-assemble in nearly flat bilayer membranes, forming closed vesicles (liposomes). By contrast, most of the commonly used surfactants form micelles whose radii of curvature are close to the length of hydrocarbon chains. 5 While each of the pure compounds form in dilute solution aggregates of a particular type, mixtures of lipids and surfactants self-assemble in either mixed liposomes or mixed micelles, depending on the composition. [5][6][7] Transition from mixed bilayers to mixed micelles upon addition of surfactant to phospholipid vesicles is commonly denoted as solubilization of the liposomes. The resultant micelles were previously described as having either disklike (oblate ellipsoidal 8 ) or cylindrical shapes, 5 in apparent agreement with dynamic light scattering data.More recently, however, cryotransmition electron microscopy, 9,10 size-exclusion high-performance liquid chromatography, 11 small angle neutron scattering, 12 and re-evaluation of dynamic light scattering data 13 indicated that in most cases solubilization of liposomes results in formation of threadlike rather than disklike micelles.The model of disklike micelles was supported by the idea that the surfactant molecules form the rims of the micelles where the amphiphile monolayers are strongly curved, while the lipid molecules remain in flat parts of the disks. However, this qualitative consideration did not account for the entropy of mixing of the two components in the micelle, which tends to distribute uniformly the molecules of the two components over the whole surface of each micelle. The result of competition of these two tendencies is not obvious and requires a detailed theoretical analysis.Based on the more...

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“…A second class of systems, for which the Helfrich free energy has been used, are those in contact with a solid curved wall. Several authors [12][13][14][15] have calculated the electrostatic contribution to the curvature coefficients using double layer theory for a charged solid wall, 16 while recently Clement and Joanny 17 calculated the curvature energy associated with polymer adsorption onto a curved substrate. In these systems the curvature of the interface is varied simply by changing the radius of the solid wall.…”

Section: ͑11͒mentioning

confidence: 99%

“…18 Also, these expressions can be derived from the virial expressions for the curvature coefficients 6 by making a mean-field approximation to the pair density. 19,20 On the other hand, it is well established by various authors [12][13][14][15] that the expressions for the electrostatic contribution to the curvature coefficients in double layer theory calculated directly via the free energy are the same as when the pressure expressions are used. This was shown by Winterhalter and Helfrich 12 using the Debye-Hückel theory, by Lekkerkerker 13 and by Mitchell and Ninham 14 using Poisson-Boltzmann theory in excess salt, and by Fogden, Daicic, and coworkers 15 using Poisson-Boltzmann theory with an arbitrary amount of added salt.…”

Section: ͑11͒mentioning

confidence: 99%

Correspondence between the pressure expressions and van der Waals theory for a curved surface

Blokhuis

Lekkerkerker²,

Szleifer

2000

The Journal of Chemical Physics

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We investigate the apparent contradiction between the pressure expressions, or ''mechanical expressions,'' and the van der Waals squared-gradient expressions for the curvature coefficients k/R 0 , k, and k . We show that, in the context of the mean-field theory discussed, both types of expression are indeed equivalent, with the differences only being caused by the thermodynamic conditions used to vary the curvature.

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Bending of ionic surfactant monolayers

Cited by 47 publications

References 53 publications

The Electrostatic Interactions between Two Corrugated Charged Planes

The Electrostatic Interactions between Two Corrugated Charged Planes

Shape of Phospholipid/Surfactant Mixed Micelles: Cylinders or Disks? Theoretical Analysis

Correspondence between the pressure expressions and van der Waals theory for a curved surface

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