Stabilization of thin liquid films by repulsive van der waals force

Erqiang Li, Ivan Uriev Vakarelski, Derek Y. C. Chan, Sigurdur T Thoroddsen

Research output: Contribution to journalArticlepeer-review

18 Scopus citations

Abstract

Using high-speed video recording of bubble rise experiments, we study the stability of thin liquid films trapped between a rising bubble and a surfactant-free liquid-liquid meniscus interface. Using different combinations of nonpolar oils and water that are all immiscible, we investigate the extent to which film stability can be predicted by attractive and repulsive van der Waals (vdW) interactions that are indicated by the relative magnitude of the refractive indices of the liquid combinations, for example, water (refractive index, n = 1.33), perfluorohexane (n = 1.23), and tetradecane (n = 1.43). We show that, when the film-forming phase was oil (perfluorohexane or tetradecane), the stability of the film could always be predicted from the sign of the vdW interaction, with a repulsive vdW force resulting in a stable film and an attractive vdW force resulting in film rupture. However, if aqueous electrolyte is the film-forming bulk phase between the rising air bubble and the upper oil phase, the film always ruptured, even when a repulsive vdW interaction was predicted. We interpret these results as supporting the hypothesis that a short-ranged hydrophobic attraction determines the stability of the thin water film formed between an air phase and a nonpolar oil phase. © 2014 American Chemical Society.
Original languageEnglish (US)
Pages (from-to)5162-5169
Number of pages8
JournalLangmuir
Volume30
Issue number18
DOIs
StatePublished - May 2 2014

ASJC Scopus subject areas

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

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