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Micelle Formation in Alkyl Sulfate Surfactants Using Dissipative Particle Dynamics
journal contribution
posted on 2018-03-23, 00:00 authored by Richard L. Anderson, David J. Bray, Annalaura Del Regno, Michael A. Seaton, Andrea S. Ferrante, Patrick B. WarrenWe
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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study micelle formationuse dissipative particle dynamicsMicelle Formationsubmicellar aggregatesalkyl chain lengthssurfactant concentrationsodium dodecyl sulfatesodium ionsalkyl sulfate surfactantsmicelle concentrationsaggregation numberspseudophase modelDissipative Particle Dynamicsalkyl chain lengthAlkyl Sulfate Surfactantssulfate chemical groupCMC12 carbon atomshalfSDS concentrationsDPD force field
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