Modelling the interfacial behaviour of dilute light-switching surfactant solutions

Herdes, Carmelo; Santiso, Erik E.; James, Craig; Eastoe, Julian; Müller, Erich A.

doi:10.1016/j.jcis.2014.12.040

Cited by 37 publications

(31 citation statements)

References 51 publications

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“…The SAFT force field does not suffer from the aforementioned limitations and has been shown to reproduce in a quantitative manner the behavior of complex fluids and, of particular interest to this case, ethoxylated surfactants and photosensitive surfactants in water. 31 In our study, the surfaces correspond to unstructured walls with an integrated potential that depends only on the energy potential parameters and the distance to the surface. 32 The baseline surface is paraffinic in nature, parametrized so that a pure water droplet has an average contact angle of 60°, corresponding to the conditions for which the optimum superspreading behavior is observed experimentally.…”

Section: ■ Methodologymentioning

confidence: 99%

Superspreading: Mechanisms and Molecular Design

et al. 2015

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The intriguing ability of certain surfactant molecules to drive the superspreading of liquids to complete wetting on hydrophobic substrates is central to numerous applications that range from coating flow technology to enhanced oil recovery. Despite significant experimental efforts, the precise mechanisms underlying superspreading remain unknown to date. Here, we isolate these mechanisms by analyzing coarse-grained molecular dynamics simulations of surfactant molecules of varying molecular architecture and substrate affinity. We observe that for superspreading to occur, two key conditions must be simultaneously satisfied: the adsorption of surfactants from the liquid-vapor surface onto the three-phase contact line augmented by local bilayer formation. Crucially, this must be coordinated with the rapid replenishment of liquid-vapor and solid-liquid interfaces with surfactants from the interior of the droplet. This article also highlights and explores the differences between superspreading and conventional surfactants, paving the way for the design of molecular architectures tailored specifically for applications that rely on the control of wetting.

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Section: ■ Methodologymentioning

confidence: 99%

Superspreading: Mechanisms and Molecular Design

et al. 2015

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“…Finally, following the general methodology proposed by Segura et al, 43,44 the molecular parameters of pure fluids can be calculated by forcing the EoS to exactly reproduce the experimental vapor pressure, the local slope of the vapor pressure curve, and the density and compressibility of the liquid phase at one single reference temperature in terms of the theory of displacements. 45,46 In this work we modeled THF as a single-and double-segment pearl-necklace model, without any additional electrostatic interactions, estimated from the corresponding states principle (or critical data) proposed by Mejía et al 41 This methodology has shown great flexibility to characterize vapor-liquid interfacial properties of pure fluids 47 and complex mixtures of dilute surfactant solutions 48 and natural gases and condensates. 47,[49][50][51] Table I summarizes the SAFT parameters for THF as used in molecular simulations in this work.…”

Section: A Saft-coarse Grained Mie Force Fieldmentioning

confidence: 99%

On interfacial properties of tetrahydrofuran: Atomistic and coarse-grained models from molecular dynamics simulation

Garrido

Algaba

Mı́guez

et al. 2016

The Journal of Chemical Physics

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We have determined the interfacial properties of tetrahydrofuran (THF) from direct simulation of the vapor-liquid interface. The molecules are modeled using six di↵erent molecular models, three of them based on the united-atom approach and the other three based on a coarse-grained (CG) approach. In the first case, THF is modeled using the transferable parameters potential functions approach proposed by Chandrasekhar and Jorgensen [J. Chem. Phys. 77, 5073 (1982) (2014)]. Simulations were performed in the molecular dynamics canonical ensemble and the vapor-liquid surface tension is evaluated from the normal and tangential components of the pressure tensor along the simulation box. In addition to the surface tension, we have also obtained density profiles, coexistence densities, critical temperature, density, and pressure, and interfacial thickness as functions of temperature, paying special attention to the comparison between the estimations obtained from di↵erent models and literature experimental data. The simulation results obtained from the three CG models as described by the SAFTMie approach are able to predict accurately the vapor-liquid phase envelope of THF, in excellent agreement with estimations obtained from TraPPE model and experimental data in the whole range of coexistence. However, Chandrasekhar and Jorgensen model presents significant deviations from experimental results. We also compare the predictions for surface tension as obtained from simulation results for all the models with experimental data. The three CG models predict reasonably well (but only qualitatively) the surface tension of THF, as a function of temperature, from the triple point to the critical temperature. On the other hand, only the TraPPE united-atoms models are able to predict accurately the experimental surface tension of the system in the whole temperature range. C 2016 AIP Publishing LLC. [http://dx

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“…The SAFT-γ Mie EoS is used here to inform CG force-field parameters representing the interactions between the chemical groups characteristic of PFAA molecules that can then be used as input in direct molecular simulation. The SAFT-γ Mie methodology has already been applied to develop an efficient parametrization of CG force fields over a broad range of conditions for a variety of molecular fluids, including carbon dioxide [45][46][47], other greenhouse gases and refrigerants [48], aromatic compounds [49], water and aqueous mixtures [50][51][52][53], n-alkanes [48,54], and amphiphilic systems comprising nonionic [55], light-switching [56], and super spreading surfactants [57]. The procedure for the determination of the molecular parameters can be further simplified with a corresponding states treatment [58].…”

Section: Introductionmentioning

confidence: 99%

SAFT-γ force field for the simulation of molecular fluids: 8. Hetero-segmented coarse-grained models of perfluoroalkylalkanes assessed with new vapour–liquid interfacial tension data

et al. 2016

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The air-liquid interfacial behaviour of linear perfluoroalkylalkanes (PFAAs) is reported through a combined experimental and computer simulation study. The surface tensions of seven liquid PFAAs (perfluorobutylethane, F 4 H 2 ; perfluorobutylpentane, F 4 H 5 ; perfluorobutylhexane, F 4 H 6 , perfluorobutyloctane, F 4 H 8 ; perfluorohexylethane, F 6 H 2 ; perfluorohexylhexane, F 6 H 6 ; and perfluorohexyloctane, F 6 H 8 ) are experimentally determined over a wide temperature range (276-350 K). The corresponding surface thermodynamic properties and the critical temperatures of the studied compounds are estimated from the temperature dependence of the surface tension. Experimental density and vapour pressure data are employed to parameterize a generic heteronuclear coarse-grained intermolecular potential of the SAFT-γ family for PFAAs. The resulting force field is used in direct molecular-dynamics simulations to predict the experimental tensions with quantitative agreement and to explore the conformations of the molecules in the interfacial region revealing a preferential alignment of the PFAA molecules towards the interface and an enrichment of the perfluoro groups at the outer interface region.

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Modelling the interfacial behaviour of dilute light-switching surfactant solutions

Cited by 37 publications

References 51 publications

Superspreading: Mechanisms and Molecular Design

Superspreading: Mechanisms and Molecular Design

On interfacial properties of tetrahydrofuran: Atomistic and coarse-grained models from molecular dynamics simulation

SAFT-γ force field for the simulation of molecular fluids: 8. Hetero-segmented coarse-grained models of perfluoroalkylalkanes assessed with new vapour–liquid interfacial tension data

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