Ultrasonics Sonochemistry (Dec 2021)

Turbulence-induced formation of emulsion gels

  • Wu Li,
  • Gregory J.O. Martin,
  • Muthupandian Ashokkumar

Journal volume & issue
Vol. 81
p. 105847

Abstract

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Emulsion gels have a wide range of applications. We report on a facile and versatile method to produce stable emulsion gels with tunable rheological properties. Gel formation is triggered by subjecting a mixture containing aqueous colloidal particle (CP) suspensions and water-immiscible liquids to intense turbulence, generated by low frequency (20 kHz) ultrasound or high-pressure homogenization. Through systematic investigations, requisite gel formation criteria are established with respect to both formulation and processing, including ratio/type of liquid pairs, CP properties, and turbulence conditions. Based on the emulsion microstructure and rheological properties, inter-droplet bridging and CP void-filling are proposed as universal stabilization mechanisms. These mechanisms are further linked to droplet-size scaling and sphere close-packing theory, distinctive from existing gel-conferring models. The study thereby provides the foundation for advancing the production of emulsion gels that can be tailored to a wide range of current and emerging applications in the formulation and processing of food, cosmetics or pharmaceutical gels, and in material science.

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