Phase transition and miscibility of binary surfactant mixtures in adsorbed film at the air/water surface

Akio Ohta, Hiroki Matsubara, Tatsuya Matsukubo, Takanori Takiue, Norihiro Ikeda, Makoto Aratono

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)

Abstract

The surface tension γ of aqueous solutions of tetraethyleneglycol monomethyl ether (C1E4) and dodecylammonium chloride (DAC) mixture was measured as a function of the total molality m̂ and the composition X̂2 of the mixture at 298.15 K under atmospheric pressure. It was found that the two break points exist on the γ vs - curves in the very low concentration region and at the critical micelle concentration except for the low composition region. It was concluded that the former break point corresponds to the phase transition of the adsorbed film from the gaseous to the expanded state. The excess Gibbs energy and the activity coefficient of adsorption were calculated to examine the interaction between C1E4 and DAC molecules in the adsorbed film quantitatively. The results showed that the interaction between C1E4 and DAC molecules is favorable in the gaseous state and unfavorable in the expanded state. This finding shows that the drastic change of the miscibility in the adsorbed film is induced by the phase transition. Furthermore it was seen that the C1E4 molecules are miscible with DAC molecules in the micelle rather than in the adsorbed film. This may be due to differences in geometry between the micelle and the adsorbed film.

Original languageEnglish
Pages (from-to)411-417
Number of pages7
JournalJournal of Colloid And Interface Science
Volume256
Issue number2
DOIs
Publication statusPublished - Dec 15 2002

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Surfaces, Coatings and Films
  • Colloid and Surface Chemistry

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