Shape of Long Chain Alkyl Sulfonate Micelle upon Salt Addition: a Molecular Dynamics Study

Poghosyan, Armen H.; Arsenyan, Levon H.; Shahinyan, Aram A.

doi:10.1007/s11743-015-1701-y

Cited by 10 publications

(4 citation statements)

References 22 publications

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“…Cylindrical micelles present as semiflexible rods with spherical end-caps that are larger in diameter than the main cylinder body. This dumbbell shape for rod micelles has been predicted by theory and observed in molecular dynamics simulations . In this work, we also observe the formation of these dumbbell-type structures at concentrations around and above the sphere-to-rod transition (see the structures in Figure a).…”

Section: Resultssupporting

confidence: 85%

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Micelle Formation in Alkyl Sulfate Surfactants Using Dissipative Particle Dynamics

Anderson

Bray

Regno

et al. 2018

J. Chem. Theory Comput.

159

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We use dissipative particle dynamics (DPD) to study micelle formation in alkyl sulfate surfactants, with alkyl chain lengths ranging from 6 to 12 carbon atoms. We extend our recent DPD force field [ J. Chem. Phys. 2017 , 147 , 094503 ] to include a charged sulfate chemical group and aqueous sodium ions. With this model, we achieve good agreement with the experimentally reported critical micelle concentrations (CMCs) and can match the trend in mean aggregation numbers versus alkyl chain length. We determine the CMC by fitting a charged pseudophase model to the dependence of the free surfactant on the total surfactant concentration above the CMC and compare it with a direct operational definition of the CMC as the point at which half of the surfactant is classed as micellar and half as monomers and submicellar aggregates. We find that the latter provides the best agreement with experimental results. Finally, with the same model, we are able to observe the sphere-to-rod morphological transition for sodium dodecyl sulfate (SDS) micelles and determine that it corresponds to SDS concentrations in the region of 300-500 mM.

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Section: Resultssupporting

confidence: 85%

“…This dumbbell shape for rod micelles has been predicted by theory 75 and observed in molecular dynamics simulations. 76 In this work, we also observe the formation of these dumbbell-type structures at concentrations around and above the sphere-torod transition (see the structures in Figure 5a).…”

Section: Journal Of Chemical Theory and Computationsupporting

confidence: 61%

Micelle Formation in Alkyl Sulfate Surfactants Using Dissipative Particle Dynamics

Anderson

Bray

Regno

et al. 2018

J. Chem. Theory Comput.

159

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“…Systematic research effort over the years has resulted in a considerable amount of computational work on model SDS aqueous solutions employing either coarse-grained − (CG) or united-atom − (UA) or even all-atom − (AA) force fields. For example, using the MARTINI Force Field (FF) ,, or other CG models, good estimates of the first CMC , and of the mean aggregation number of micelles have been obtained for certain SDS concentrations. , Dissipative particle dynamics (DPD) simulations − have also offered a qualitative description of the morphological properties of aqueous SDS solutions.…”

Section: Introductionmentioning

confidence: 99%

Quantitative Prediction of the Structure and Viscosity of Aqueous Micellar Solutions of Ionic Surfactants: A Combined Approach Based on Coarse-Grained MARTINI Simulations Followed by Reverse-Mapped All-Atom Molecular Dynamics Simulations

Peroukidis

Tsalikis

Noro

et al. 2020

J. Chem. Theory Comput.

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We address the problem of the quantitative prediction of micelle formation in dilute aqueous solutions of ionic surfactants using sodium dodecyl sulfate (SDS) as a model system through a computational approach that involves three steps: (a) execution of coarse-grained simulations based on the MARTINI force field (with slightly modified parameters to afford the formation of large micelles); (b) reverse mapping of the final self-assembled coarse-grained configuration into an all-atom configuration; and (c) final relaxation of this all-atom configuration through short-time (on the order of a few tens of nanoseconds), detailed isothermal–isobaric molecular dynamics simulations using the CHARMM36 force field. For a given concentration of the solution in SDS molecules, the modified MARTINI-based coarse-grained simulations lead to the formation of large micelles characterized by mean aggregation numbers above the experimentally observed ones. However, by reintroducing the detailed chemical structure through a strategy that solves a well-defined geometric problem and re-equilibrating, these large micellar aggregates quickly dissolve to smaller ones and equilibrate to sizes that perfectly match the average micelle size measured experimentally at the given surfactant concentration. From the all-atom molecular dynamics simulations, we also deduce the surfactant diffusivity D SDS and the zero-shear rate viscosity, η0, of the solution, which are observed to compare very favorably with the few experimental values that we were able to find in the literature.

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“…9 The effect of the interaction parameters between the surfactant and the counter-ion over micelle structure, which to some extent presents similar effects of possible counterions exchanges, was studied by de Moura and Freitas 10 and by Tang et al 11 The salt concentration was also showed to have significant effects over the shape and dynamics of aggregates in self-assembled systems. 12,13,14,15 Here, we will compare the widely used surfactant sodium dodecyl-sulfate (SDS) with the choline dodecyl-sulfate (ChDS). The micelles formed by dodecyl-sulfate are well-behaved and stable.…”

Section: Introductionmentioning

confidence: 99%

Counter-ion adsorption and electrostatic potential in sodium and choline dodecyl sulfate micelles — a molecular dynamics simulation study

Eliasquevici,

Bernardino

2024

J Mol Model

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Choline-based surfactants are interesting both from the practical point of view to obtaining environmental-friendly surfactants as well as from the theoretical side since the interactions between the choline and surfactants can help to understand self-assembly phenomena in deep eutectic solvents. Although no significant change was noticed in the micelle size and shape due to the exchange of the sodium counterion by choline in our simulations, the adsorption of the choline cation over the micelle surface is stronger than the adsorption of the sodium, which leads to a reduction of the exposed surface area of the micelle and remarkable effects over the electrostatic potential. The choline neutralizes the surface charge of the surfactant better than sodium, however, this is partially compensated by a stronger water orientation around SDS micelle. The balance between the contributions from the surfactant, the counterion and water to the electrostatic potential leads to a complex pattern with alternate regions of positive and negative potential at the micelle/water interface which can be important to the incorporation of other charged species at the micelle surface as well as for the interaction between micelles in solution. MethodsTo evaluate the effects of the counterion substitution, micelles of sodium dodecyl sulfate (SDS) and choline dodecyl sulfate (ChDS) were studied and compared by means of 2 molecular dynamics simulations in aqueous solution. In both cases, the simulations started from pre-assembled micelles with 60 dodecyl sulfate ions and 240 ns simulations were performed at NPT ensemble at T = 323.15 K and P = 1 bar using the Gromacs software with the OPLS-AA force field to describe dodecyl-sulfate and choline, Åqvist parameters for sodium and SPC model for water molecules.

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Shape of Long Chain Alkyl Sulfonate Micelle upon Salt Addition: a Molecular Dynamics Study

Cited by 10 publications

References 22 publications

Micelle Formation in Alkyl Sulfate Surfactants Using Dissipative Particle Dynamics

Micelle Formation in Alkyl Sulfate Surfactants Using Dissipative Particle Dynamics

Quantitative Prediction of the Structure and Viscosity of Aqueous Micellar Solutions of Ionic Surfactants: A Combined Approach Based on Coarse-Grained MARTINI Simulations Followed by Reverse-Mapped All-Atom Molecular Dynamics Simulations

Counter-ion adsorption and electrostatic potential in sodium and choline dodecyl sulfate micelles — a molecular dynamics simulation study

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