Lateral dynamics of surfactants at the free water surface: A computer simulation study

Nóra A. Rideg, Mária Darvas, Imre Varga, P. Jedlovszky

Research output: Contribution to journalArticle

20 Citations (Scopus)

Abstract

Molecular dynamics simulations of the adsorption layer of five different surfactant molecules, i.e., pentyl alcohol, octyl alcohol, dodecyl alcohol, sodium dodecyl sulfate, and dodecyl trimethyl ammonium chloride are performed at the free surface of their aqueous solution at two surface densities, namely 1 and 4 μmol/m2 at 298 K. The results are analyzed in terms of the two-dimensional single molecule dynamics, in particlular, lateral diffusion of the surfactants at the liquid surface, in order to distinguish between two possible adsorption scenarios, namely the assumptions of localized and mobile surfactants. The obtained results, in accordance with the dynamical nature of the liquid phase and liquid surface, clearly support the latter scenario, as the time scale of lateral diffusion of the surfactant molecules is found to be comparable with that of the three-dimensional diffusion of water in the bulk liquid phase. The mechanism of this lateral diffusion is also investigated in detail by calculating binding energy distribution of the water molecules in the first hydration shell of the surfactant headgroups and that of the nonfirst shell surface waters, and by calculating the mean residence time of the water molecules in the first hydration shell of the surfactant headgroups. This time is found to be at least an order of magnitude smaller than the characteristic time of the lateral diffusion of the surfactants, revealing that surfactant molecules move without their first shell hydration water neighbors at the surface.

Original languageEnglish
Pages (from-to)14944-14953
Number of pages10
JournalLangmuir
Volume28
Issue number42
DOIs
Publication statusPublished - Oct 23 2012

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surface water
Surface-Active Agents
Surface active agents
computerized simulation
surfactants
Water
Computer simulation
Molecules
Hydration
hydration
molecules
alcohols
Alcohols
liquid surfaces
Liquids
water
liquid phases
Dodecanol
Pentanols
Adsorption

ASJC Scopus subject areas

  • Electrochemistry
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Materials Science(all)
  • Spectroscopy

Cite this

Lateral dynamics of surfactants at the free water surface : A computer simulation study. / Rideg, Nóra A.; Darvas, Mária; Varga, Imre; Jedlovszky, P.

In: Langmuir, Vol. 28, No. 42, 23.10.2012, p. 14944-14953.

Research output: Contribution to journalArticle

Rideg, Nóra A. ; Darvas, Mária ; Varga, Imre ; Jedlovszky, P. / Lateral dynamics of surfactants at the free water surface : A computer simulation study. In: Langmuir. 2012 ; Vol. 28, No. 42. pp. 14944-14953.
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