Modelling the interfacial behaviour of dilute light-switching surfactant solutions

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

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

The direct molecular modelling of an aqueous surfactant system at concentrations below the critical micelle concentration (pre-cmc) conditions is unviable in terms of the presently available computational power. Here, we present an alternative that combines experimental information with tractable simulations to interrogate the surface tension changes with composition and the structural behaviour of surfactants at the water-air interface. The methodology is based on the expression of the surface tension as a function of the surfactant surface excess, both in the experiments and in the simulations, allowing direct comparisons to be made. As a proof-of-concept a coarse-grained model of a light switching non-ionic surfactant bearing a photosensitive azobenzene group is considered at the air-water interface at 298. K. Coarse-grained molecular dynamic simulations are detailed based on the use of the SAFT force field with parameters tuned specifically for this purpose. An excellent agreement is obtained between the simulation predictions and experimental observations; furthermore, the molecular model allows the rationalization of the macroscopic behaviour in terms of the different conformations of the cis and trans surfactants at the surface.

Original languageEnglish
Pages (from-to)16-23
Number of pages8
JournalJournal of Colloid and Interface Science
Volume445
DOIs
Publication statusPublished - 1 May 2015

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Surface-Active Agents
Surface active agents
Surface tension
Bearings (structural)
Molecular modeling
Azobenzene
Water
Critical micelle concentration
Nonionic surfactants
Air
Conformations
Molecular dynamics
Computer simulation
Chemical analysis
Experiments

Keywords

  • Amphiphiles
  • CMC
  • Coarse graining
  • Complex fluids
  • Molecular dynamics
  • Molecular simulation
  • SAFT
  • Surface tension

Cite this

Modelling the interfacial behaviour of dilute light-switching surfactant solutions. / Herdes, Carmelo; Santiso, Erik E.; James, Craig; Eastoe, Julian; Müller, Erich A.

In: Journal of Colloid and Interface Science, Vol. 445, 01.05.2015, p. 16-23.

Research output: Contribution to journalArticle

Herdes, Carmelo ; Santiso, Erik E. ; James, Craig ; Eastoe, Julian ; Müller, Erich A. / Modelling the interfacial behaviour of dilute light-switching surfactant solutions. In: Journal of Colloid and Interface Science. 2015 ; Vol. 445. pp. 16-23.
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