Rheological model for micelles in solution from molecular dynamics

Castrejón-González, Edgar O.; Márquez-Baños, Valaur E.; Alvarado, Juan; Rico-Ramı́rez, Vicente; Jiménez‐Islas, H.

doi:10.1016/j.molliq.2014.07.016

Cited by 13 publications

(4 citation statements)

References 40 publications

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“…Other authors employed coarse-grained nonequilibrium MD simulations to quantify the rheological behavior of micelles formed from 'generic' (four hydrophobic and one hydrophilic bead) surfactants in solution. 29 They suggested a flow-based rheological model, which reproduced accurately all MD data. The authors explained the observed shear thickening effect with the breaking of a micelle followed by dispersing of the surfactant molecules.…”

Section: ■ Introductionmentioning

confidence: 87%

“…However, molecular dynamics has been proven suitable in general for interpreting surface self-assembly and rheological characteristics of surfactants both in the bulk and at interfaces. − Wang et al studied the self-assembly of mixed dodecylamine (DDA)–dodecanol (DOD) layers at the air/water interface by large-scale atomistic MD simulations. They showed that the self-assembly of pure DDA is not significant due to the strong electrostatic repulsion.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Structure of Dense Adsorption Layers of Escin at the Air–Water Interface Studied by Molecular Dynamics Simulations

2019

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Saponins are natural surfactants with high surface activity and unique surface properties. Escin is a triterpenoid saponin which has unusually high surface viscoelasticity [Golemanov et al. Sof t Matter 2013, 9, 5738] and low permittivity to molecular gas diffusion of its adsorption layers. In our previous study [Tsibranska et al. Langmuir 2017, 33, 8330], we investigated the molecular origin of this unconventional behavior and found that escin molecules rapidly assemble in a compact and stable surface cluster. This behavior was explained with long-range attraction between the hydrophobic aglycones combined with intermediate dipole−dipole attraction and strong short-range hydrogen bonds between the sugar residues in the adsorbed escin molecules. In this study, we performed atomistic molecular simulations of escin molecules in dense adsorption layers with two different areas per molecule. The results show that the surfactant molecules in these systems are much less submerged in water and adopt a more upright position compared to the dilute layers studied previously. A significant number of trapped water molecules are located around the hydrophilic groups placed above the water equimolecular surface to solvate them in the dense layer. To maintain the preferred orientation of the escin molecules with respect to the interface, the most compact adsorption layer acquires a significant spontaneous curvature. The substantial elasticity of the neutral escin layers, as in our previous study, is explained with the presence of a specific interaction, which is intermediate between hydrogen bonding and dipole−dipole attraction (populated lengths in the range 0.16 to >0.35 nm), supplemented by substantial flexibility of the surfactant heads, optimal curvature of the interface, and significant normal displacement of the molecules to allow their tight surface packing. The simulations reveal long-range order within the layers, which signifies the role of the collective behavior of the saponin molecules in such dense adsorption layers.

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Section: ■ Introductionmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 99%

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Structure of Dense Adsorption Layers of Escin at the Air–Water Interface Studied by Molecular Dynamics Simulations

2019

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“…Jamali et al 27 used the DPD method to simulate different surface roughnesses of particle surfaces in non-Newtonian fluid suspensions and found a more pronounced continuous nonlinear shear thickening behavior for rough surface particles compared to smooth surface particles. Castrejon-Gonzalez et al 28 used a non-equilibrium molecular dynamics approach to study the rheological behavior of colloidal solutions with an improved Carreau–Yasuda equation was well fitted to the rheological data of colloidal solutions and the fitted rheological curves were divided into Newtonian, shear-thinning and shear-thickening regions. Despite some progress, less effort has been made to understand the mechanisms of variation in non-Newtonian fluids with nonlinear rheological properties at the microscopic level.…”

Section: Introductionmentioning

confidence: 99%