Effect of stiffness on the micellization behavior of model H4T4 surfactant chains

Vanessa Firetto, Michele A. Floriane, Athanassios Z. Panagiotopoulos

Research output: Contribution to journalArticle

18 Scopus citations

Abstract

The micellization behavior of a series of model surfactants, all with four head and tail groups (H 4T 4) but with different degrees of chain stiffness, was studied using grand canonical Monte Carlo simulations on a cubic lattice. The critical micelle concentration, micellar size, and thermodynamics of micellization were examined. In all cases investigated, the critical micelle concentration was found to increase with increasing temperature as observed for nonionic surfactants in apolar or slightly polar solvents. At a fixed reduced temperature and increasing chain stiffness, in agreement with previous observations, it was found that the critical micelle concentration decreased and the average micelle size increased. This behavior is qualitatively consistent with that experimentally observed when comparing hydrogenated and homologous fluorinated surfactants. Thermodynamic considerations based on the analysis of the temperature dependence of the critical micelle concentration indicated that both effects could be interpreted as arising from an increased number of heterocontacts between hydrophobic portions of stiff surfactants and a lower entropic cost on packing rigid chains. Structural analysis that was also based on considering the inner micellar radial dependence of the surfactant head and tail site fraction distributions suggested that, on stiffening the molecular backbone, the resulting micellar aggregates grew, without appreciable deviations from spherical symmetry. Suffer surfactants led to a slightly denser micellar core because of better packing.

Original languageEnglish (US)
Pages (from-to)6514-6522
Number of pages9
JournalLangmuir
Volume22
Issue number15
DOIs
StatePublished - Jul 18 2006

All Science Journal Classification (ASJC) codes

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

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