Interfacial films and wetting behavior of hexadecane on aqueous solutions of dodecyltrimethylammonium bromide

Hiroki Matsubara, Norihiro Ikeda, Takanori Takiue, Makoto Aratono, Colin D. Bain

Research output: Contribution to journalArticlepeer-review

28 Citations (Scopus)

Abstract

The interfacial tensions and dihedral angles of hexadecane lenses on aqueous solutions of dodecyltrimethylammonium bromide (DTAB) were measured in air as a function of the molality of DTAB at 298.15 K and atmospheric pressure. The air/water interfacial tension of DTAB solution shows a break point that shifts to a lower concentration in the presence of a hexadecane lens. Ellipsometric measurements showed a continuous variation in ellipticity with concentration for pure DTAB solutions, but a discontinuous change in the ellipticity of the air/water interface in the presence of a hexadecane lens. This behavior can be viewed either as a first-order wetting transition driven by the adsorbed surfactant, or as a gaseous-expanded phase transition in the surfactant adsorbed film induced by the hexadecane. The formation of a microscopic oil film in equilibrium with a lens is rationalized by an attractive long-range potential across the thin film. From the measurement of dihedral angles, it was found that there was a concentration region where a lens exists stably even when complete wetting was expected from measured values of interfacial tensions.

Original languageEnglish
Pages (from-to)2249-2253
Number of pages5
JournalLangmuir
Volume19
Issue number6
DOIs
Publication statusPublished - Mar 18 2003

All Science Journal Classification (ASJC) codes

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

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