The phase behaviour of cetyltrimethylammonium chloride surfactant aqueous solutions at high concentrations: an all-atom molecular dynamics simulation study

Tsourtou, Flora D.; Peroukidis, Stavros D.; Peristeras, Loukas D.

doi:10.1039/d1sm01639c

Cited by 6 publications

(4 citation statements)

References 56 publications

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“… 45 , 46 , 52 We observe that the increase in viscosity is likely to be a result of a combination of shape effects, as well as inter-micellar interactions. The gradual transition that we find between the micellar and hexagonal phase is in agreement with what is observed in a recent MD study 53 for cetyltrimethyl ammonium chloride surfactants.…”

Section: Resultssupporting

confidence: 92%

“…Changes to the solution viscosity are primarily influenced by changes in the shape of micellar aggregates, the number of micelles formed, and/or due to micellar interactions. ,,, It is often suggested that strong repulsive inter-micellar interactions play a large role in the measured increase in viscosity. ,, We observe that the increase in viscosity is likely to be a result of a combination of shape effects, as well as inter-micellar interactions. The gradual transition that we find between the micellar and hexagonal phase is in agreement with what is observed in a recent MD study for cetyltrimethyl ammonium chloride surfactants.…”

Section: Resultssupporting

confidence: 88%

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Studying the Structure of Sodium Lauryl Ether Sulfate Solutions Using Dissipative Particle Dynamics

2022

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Sodium lauryl ether sulfate (SLES) is a common anionic surfactant used in a large number of personal care products. Commercial products typically contain a distribution in the number of ethoxy groups; despite this, there is limited existing work studying the effect of the ethoxy groups on the phase formation and structure. This is particularly important for the effect the structure has on the viscosity, an important consideration for commercial products. Dissipative particle dynamics is used to simulate the full phase diagram of SLES in water, including both micellar and lyotropic liquid crystal phases. Phase transitions occur at locations which are in good agreement with experimental data, and we find that these boundaries can shift as a result of varying the number of ethoxy groups. Varying the ethoxy groups has a significant effect on the micellar shape and crystalline spacing, with a reduction leading to more nonspherical micelles and decreased periodic spacing of the hexagonal and lamellar phases. Finally, while typical commercial products contain a distribution of ethoxy groups, computational work tends to focus on simulations containing a single chain length. We show that it is valid to use monodisperse simulations to infer behavior about solutions with a polydisperse chain length, based on its mean molecular length.

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Section: Resultssupporting

confidence: 92%

Section: Resultssupporting

confidence: 88%

Studying the Structure of Sodium Lauryl Ether Sulfate Solutions Using Dissipative Particle Dynamics

2022

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“…Clustering analysis of CG water molecules over the last 50 ns of the trajectories was also carried out. A cluster is defined as an aggregate of two of more water molecules in close contact, and the analysis was performed by means of pysimpp software, an open-source tool freely available at Github . Nevertheless, the maximum size of the clusters was calculated by using the GROMACS 2016.5 − cluster analysis functionality with the distance cutoff criterion set to 0.745 nm, which is the location of the first minimum of the polarizable water–water radial distribution function (RDF) .…”

Section: Resultsmentioning

confidence: 99%

Coarse-Grained Molecular Dynamics Simulation of Cobalt Nanoparticle in the n-Octacosane–Water Mixture: The Effect of Water Concentration and Nanoparticle Size

et al. 2022

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The Fischer–Tropsch synthesis (FTS) is central in the Gas-to-Liquids (GTL) process, which is commercially used in the production of environmentally benign transportation fuels from synthesis gas. However, several factors can impede the performance of FTS reactors and thereby increase the overall GTL cost, among which is water in excess concentrations. Water is a byproduct of the FTS process and is present in varying amounts. In order to gain a better understanding of the behavior of catalyst nanoparticles (NPs) inside the produced wax–water mixtures at reaction conditions and realistic scales and sizes, one needs to incorporate coarse-grained approaches in the context of FTS. The present study focuses on coarse-grained (CG) Molecular Dynamics (MD; CGMD) simulations of n-octacosane (n-C28)–water mixture at low-temperature FTS conditions (473.15 K) and considers various water mole fractions with the inclusion of different-sized Co NPs using the MARTINI force field. The Co NPs are suspended inside these bulk mixtures thereby resembling a slurry phase type of reactor. Water mole fractions below and above the solubility of water in n-C28 as predicted by MARTINI were used so as to better capture the phase behavior of the produced wax–water mixtures. Our results show that, for the NP sizes examined, water in small concentrations does not aggregate on the Co NP surface. For water concentrations above the calculated solubility in n-C28, water forms a cluster that fully encapsulates the NP, and for excess water, the NPs are completely immersed in the aqueous phase. This behavior bears implications in the mobility of the NPs examined, which appears to increase as a function of water concentration. Calculations of Co NPs self-diffusion coefficient show that the smaller nanoparticle moves faster, and that mobility drops as nanoparticle size increases. For high water mole fractions, that is, well-exceeding water solubility in bulk n-C28, an increasing effect in the mobility of the examined Co NPs was observed. The computational approach using the MARTINI force field and the results presented showcase that CGMD simulations can be employed to study the hydrodynamic effects on the NP mobility in FTS-related processes.

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“…The simulation means for modified nanoparticles are still at the stage of exploration and realization [14,15]. This study selected alkyl-modified graphene oxide as the research object and used the all-atom molecular dynamics simulation method [16] to study the diffusion of modified nanoparticles (NGOs) in the aqueous phase and the self-aggregation phenomenon at the oil-water interface. We also established two different models through the visualization software Materials Studio.…”

Section: Introductionmentioning

confidence: 99%

Molecular Dynamics Simulation of the Oil–Water Interface Behavior of Modified Graphene Oxide and Its Effect on Interfacial Phenomena

et al. 2022

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Graphene oxide, as a new two-dimensional material, has a large specific surface area, high thermal stability, excellent mechanical stability and exhibits hydrophilic properties. By combining the carboxyl groups on the surface of graphene oxide with hydrophilic groups, surfactant-like polymers can be obtained. In this paper, based on the molecular dynamics method combined with the first nature principle, we first determine the magnitude of the binding energy of three different coupling agents—alkylamines, silane coupling agents, and haloalkanes—and analytically obtain the characteristics of the soft reaction. The high stability of alkylamines and graphene oxide modified by cetylamine, oil, and water models was also established. Then, three different chain lengths of simulated oil, modified graphene oxide–water solution, and oil-modified graphene oxide–water systems were established, and finally, the self-aggregation phenomenon and molecular morphology changes in modified graphene oxide at the oil–water interface were observed by an all-atom molecular dynamics model. The density profile, interfacial formation energy, diffusion coefficient and oil–water interfacial tension of modified graphene oxide molecules (NGOs) at three different temperatures of 300 K, 330 K, and 360 K were analyzed, as well as the relationship between the reduced interfacial tension and enhanced oil recovery (EOR).

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The phase behaviour of cetyltrimethylammonium chloride surfactant aqueous solutions at high concentrations: an all-atom molecular dynamics simulation study

Abstract: We explore the phase behaviour of aqueous solutions of the cetyltrimethyl ammonium chloride (CTAC) surfactant and in particular the transition from the micellar phase (L1) to the hexagonal columnar phase...

Cited by 6 publications

References 56 publications

Studying the Structure of Sodium Lauryl Ether Sulfate Solutions Using Dissipative Particle Dynamics

Studying the Structure of Sodium Lauryl Ether Sulfate Solutions Using Dissipative Particle Dynamics

Coarse-Grained Molecular Dynamics Simulation of Cobalt Nanoparticle in the n-Octacosane–Water Mixture: The Effect of Water Concentration and Nanoparticle Size

Molecular Dynamics Simulation of the Oil–Water Interface Behavior of Modified Graphene Oxide and Its Effect on Interfacial Phenomena

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