Adsorption of alkyl trimethylammonium bromides at the air/water interface

Tibor Gilányi, Imre Varga, Cosima Stubenrauch, Róbert Mészáros

Research output: Contribution to journalArticle

22 Citations (Scopus)


A number of features of the adsorption of alkyl trimethylammonium bromides with nc = 10, 12, 14, and 16 at the air/water interface were studied. First, the adsorption isotherms were calculated from experimental surface tension vs concentration curves by means of the Gibbs equation. Second, a novel method was used to estimate the adsorption free energy change. From the analysis of these data it was concluded that the hydrophobic driving force for the adsorption first increases with increasing adsorbed amount and then levels off in a plateau, which holds true for all four homologues. This peculiar behavior was interpreted by the formation of a thin liquid-like alkane film at the air/water interface once a certain adsorbed amount is exceeded. The hydrophobic contribution to the standard free energy change of adsorption was compared with those values previously determined for alkyl sulfate homologues. This comparison suggests that the alkyl trimethylammonium type surfactants behave as if their alkyl chain was approximately one methylene group shorter than those of the corresponding alkyl sulfates.

Original languageEnglish
Pages (from-to)395-401
Number of pages7
JournalJournal of colloid and interface science
Issue number2
Publication statusPublished - Jan 15 2008


  • Adsorption
  • Adsorption free energy
  • Alkyl trimethylammonium bromides
  • Surfactants

ASJC Scopus subject areas

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

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