Particle self-assembly in oil-in-ionic liquid Pickering emulsions

Elizabeth M. Walker, Denzil S. Frost, Lenore Dai

Research output: Contribution to journalArticle

17 Scopus citations

Abstract

We have studied polydimethylsiloxane (PDMS)-in-1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]) Pickering emulsions stabilized by polystyrene microparticles with different surface chemistry. Surprisingly, in contrast to the consensus originating from oil/water Pickering emulsions in which the solid particles equilibrate at the oil-water droplet interfaces and provide effective stabilization, here the polystyrene microparticles treated with sulfate, aldehyde sulfate, or carboxylate dissociable groups mostly formed monolayer bridges among the oil droplets rather than residing at the oil-ionic liquid interfaces. The bridge formation inhibited individual droplet-droplet coalescence; however, due to low density and large volume (thus the buoyant effect), the aggregated oil droplets actually promoted oil/ionic liquid phase separation and distressed emulsion stability. Systems with binary heterogeneous polystyrene microparticles exhibited similar, even enhanced (in terms of surface chemistry dependence), bridging phenomenon in the PDMS-in-[BMIM][PF6] Pickering emulsions.

Original languageEnglish (US)
Pages (from-to)307-313
Number of pages7
JournalJournal of Colloid and Interface Science
Volume363
Issue number1
DOIs
Publication statusPublished - Nov 1 2011

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Keywords

  • Emulsion stability
  • Ionic liquid
  • Microparticle bridging
  • Particle assembly
  • Pickering emulsions

ASJC Scopus subject areas

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

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