Mixed aqueous-and-oil foams in bulk

Yuchen Si, John R. Royer, Tao Li, Paul S. Clegg*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

Hypothesis: Because particle-stabilised foams are extremely stable and have a yield stress, a particle-stabilised aqueous foam and a particle-stabilised oil foam can be mixed together to give a stable composite foam which
brings together two immiscible liquids.
Experiments: We have developed a mixed foam system comprised of an olive oil foam with bubbles stabilised using partially fluorinated particles and an aqueous foam with bubbles stabilised using hydrophobic silica particles. The aqueous phase is a mixture of water and propylene glycol. We have studied this system using bulk observations, confocal microscopy and rheology as we vary the proportions of the two foams, the silica particles and the propylene glycol, and the sample age.
Findings: The composite foam resembles an emulsion of one foam within another and is stable for a week or more. The structure and flow properties depend on the proportions of the two phases and the quantities of both
silica particles and propylene glycol. Inversion between water-in-oil and oil-in-water is observed, where both phases are foams, driven both by silica wettability and by adding increasing quantities of the dispersed foam.
Composites formed at the inversion point are the least stable, showing significant phase separation in less than
one week.
Original languageEnglish
Pages (from-to)671-678
Number of pages8
JournalJournal of Colloid and Interface Science
Early online date18 May 2023
Publication statusPublished - 15 Sept 2023

Keywords / Materials (for Non-textual outputs)

  • Emulsions
  • Foams
  • Bubbles
  • Transitional phase inversion
  • Catastrophic phase inversion


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