Molecular Dynamics Simulations of Film Rupture in Water/Surfactant Systems

Yang, Wenhong; Wu, Rongliang; Kong, Bin; Zhang, Xiongfei; Yang, Xiaozhen

doi:10.1021/jp9010108

Cited by 34 publications

(50 citation statements)

References 52 publications

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“…Most computer simulations of SDS-NBFs have focused so far on the investigation of the structure of foam films. 10,11,[21][22][23][24][25][26] The simulated structures, with thicknesses similar to those inferred from x-ray experimental data, 17 indicate that the film contains between two and four water molecules per surfactant. Part of this water accumulates around the head groups as solvation water, the remaining distributing in the film's core.…”

Section: Introductionsupporting

confidence: 58%

Adhesive transitions in Newton black films: A computer simulation study

Bresme

Chacón

Martínez

et al. 2011

The Journal of Chemical Physics

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We report molecular dynamics simulations of Newton black films (NBFs), ultra thin films of aqueous solutions stabilized with two monolayers of ionic surfactants, sodium dodecyl sulfate. We show that at low water content conditions and areas per surfactant corresponding to experimental estimates in NBFs, homogeneous films undergo an adhesion "transition," which results in a very thin adhesive film coexisting with a thicker film. We identify the adhesive film with the equilibrium structure of the Newton black film. We provide here a direct microscopic view of the formation of these important structures, which have been observed in experimental studies of emulsions and foams. We also report a detailed investigation of the structural properties and interfacial fluctuation spectrum of the adhesive film. Our analysis relies on the definition of an "intrinsic surface," which is used to remove the averaging effect that the capillary waves have on the film properties.

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Section: Introductionsupporting

confidence: 58%

Adhesive transitions in Newton black films: A computer simulation study

Bresme

Chacón

Martínez

et al. 2011

The Journal of Chemical Physics

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“…Gamba and coworkers [25] made an attempt to use MD to simulate the air/liquid interface with the same composition as that in the experiments of Benattar et al [26]. Yang et al [27] used MD simulation to investigate water/surfactant film rupture to predict the stability of films. The increment of both the lateral dimension and the duration of the film will lead to increases in the critical thickness of the film; these investigators found that the former plays a more significant role in film rupture.…”

Section: Introductionmentioning

confidence: 99%

Surface behavior of a model surfactant: A theoretical simulation study

Yuan¹,

Yan²,

Lv³

et al. 2010

Journal of Colloid and Interface Science

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“…Several works have reported classical computer simulation investigations of SDS black film foams 10,18,[21][22][23][24][25] . Simulation studies indicate that the equilibrium film contains between two and four water molecules per surfactant, and between two and three of these molecules are part of a solvation layer.…”

Section: Introductionmentioning

confidence: 99%

Electronic structure computations of Newton Black Films

Bresme

Artacho

2010

J. Mater. Chem.

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We investigate using quantum density functional theory (DFT) the electronic structure of sodium dodecyl sulfate Newton Black Films (NBF), consisting of water sandwiched between surfactants surrounded by vacuum. We generate a classical trajectory of the film using full-atom empirical potentials. DFT theory is employed to investigate the electron density and electrostatic properties of the film. The electrostatic potential derived directly from the electron and nuclear densities shows an important drop towards the vacuum side, similar to recent findings for the water-vacuum interface. We discuss the physical significance of this potential drop. We also consider as an alternative definition of the electrostatic potential, the deformation charge potential (DCP), to quantify the electrostatic properties of the interfaces. The analysis of the DCP potential indicates there is charge separation at the surfactant alkyl tails, showing that the surfactant-vacuum surface has an excess of positive charge. This result is consistent with molecular dynamics simulations employing classical force-fields, which incorporate partial charges to model the surfactant alkyl chain. The DCP potential also gives evidence for the existence of electronic polarization in the hydrophobic region of the NBF, whose origin is connected to charge transfer between the surfactant tails and the head group. We suggest that the deformation charge potential provides a route to compare the electrostatic potentials obtained from DFT and emprirical computations. This idea is illustrated by computing the electrostatic potential of the water-vapor interface. We discuss the relevance of these results in the context of DFT computations of soft interfaces.

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Molecular Dynamics Simulations of Film Rupture in Water/Surfactant Systems

Cited by 34 publications

References 52 publications

Adhesive transitions in Newton black films: A computer simulation study

Adhesive transitions in Newton black films: A computer simulation study

Surface behavior of a model surfactant: A theoretical simulation study

Electronic structure computations of Newton Black Films

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