Wetting and freezing of hexadecane on an aqueous surfactant solution: Triple point in a 2-D film

Hiroki Matsubara, E. Ohtomi, Makoto Aratono, Colin D. Bain

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

Wetting of water by hexadecane has been investigated by ellipsometry as a function of the concentration of the cationic surfactant dodecyltrimethylammonium bromide (DTAB) in the aqueous phase and temperature. Three phases are identified: a 2-D gas of hexadecane molecules and DTAB molecules, a 2-D liquid comprising a mixed monolayer of hexadecane and DTAB, and a 2-D 'solid' phase. Evidence is presented to support the hypothesis that the liquid-solid phase transition is actually a wetting transition in which a surface-frozen layer of pure hexadecane wets the liquid-like mixed monolayer of hexadecane and DTAB. The triple point, at which the three phases coexist, is located at a temperature of 17.3°C and DTAB concentration of 0.75 mmol kg-1. The slopes of the three phase boundaries are analyzed thermodynamically.

Original languageEnglish
Pages (from-to)11664-11668
Number of pages5
JournalJournal of Physical Chemistry B
Volume112
Issue number37
DOIs
Publication statusPublished - Sep 18 2008

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

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