Hydrophobic Aggregation of Nonionic Surfactants in Aqueous Solution: An MD Simulation Study

  • Dietmar Paschek
  • Thomas Engels
  • Wolfgang v. Rybinski
  • Alfons Geiger
Conference paper

Abstract

We have studied dilute aqueous solutions of nonionic surfactants of general structure H(CH2) m (OCH2CH2) n OH (abbreviated as C m E n ) by an extensive series of classical molecular dynamics simulations. The temperature dependent association of surfactant molecules and hydrophobic test—particles has been determined by Widom’s particle insertion method. The simulations were performed at constant ambient pressure conditions and temperatures between 275 K and 450 K. Our simulations suggest an entropy driven association process, which can be described well by temperature independent enthalpy and entropy contributions. These properties can be further reduced to group contributions. The resulting Gibbs free energy of transfer was used as a measure of the hydrophobicity and could be correlated with the experimental cloud point temperatures of binary aqueous mixtures of these surfactants. An empirical entropy correction leads to a quantitative description of the experimental data.

Keywords

Nonionic Surfactant Surfactant Molecule Lower Critical Solution Temperature Test Particle Hydration Shell 
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Copyright information

© Springer-Verlag Berlin Heidelberg 1999

Authors and Affiliations

  • Dietmar Paschek
    • 1
  • Thomas Engels
    • 2
  • Wolfgang v. Rybinski
    • 2
  • Alfons Geiger
    • 1
  1. 1.Universität DortmundPhysikalische ChemieDortmundGermany
  2. 2.Henkel KGaADüsseldorfGermany

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