GOALI: Single droplet level understanding of phase inversion emulsification to enable continuous processing

University Of Pennsylvania, Philadelphia PA

Investigators

Abstract

CBET - 1604536 PI: Lee, Daeyeon Emulsions are composed of liquid drops that are suspended in an immiscible liquid, such as oil drops in water. The drops are the dispersed phase, and the immiscible liquid is the continuous phase. Emulsions are used in the manufacture of many products, including foodstuffs, nutrients, drugs, and pesticides. Phase inversion emulsification (PIE) is a process for generating a new emulsion by inverting the phases of an existing emulsion. PIE is especially useful when it is difficult to generate the desired emulsion by other methods. For example, Xerox uses PIE to manufacture latex particles, which are used to produce toners for printing and photocopying. This GOALI project, which is a collaborative effort between the University of Pennsylvania and Xerox, will explore a variation on PIE called flow-induced PIE. In flow-induced PIE, phase inversion takes place by flowing an existing emulsion through microchannels that contain abrupt variations in their cross-sections, such as constrictions or expansions. Under proper conditions, an emulsion of oil drops in water flowing through the channel is inverted into an emulsion of water drops in oil. Experiments will be designed to explore effects of channel geometry, flow rates, wettability of the channel surface, and composition of the liquid phases on the phase inversion process. The flow-induced PIE process will allow products to be manufactured in a continuous process with reduced energy consumption, higher efficiency, and reduced environmental impact. The project will provide opportunities for students at various academic levels to participate in research. Students from underrepresented groups will be encouraged to participate through several programs at Penn, including the Louis Stokes Alliance for Minority Participation. A series of experiments will be conducted to determine effects of initial emulsion morphology and chemistry as well as channel geometry on the mechanism and efficiency of flow-induced PIE. The effect of surface wettability of the channels on the phase inversion process will be determined. Hydrodynamic parameters such as shear and extensional deformation in the microchannels will also be examined. The use of a microfluidic platform will enable the formation of model emulsions with controlled properties and the direct observation of PIE during flow. Emulsion droplets with precisely controlled size, size distribution and interfacial chemistry will be used to understand effects of emulsion morphology and chemistry on flow-induced PIE. Alternative arrangements that can promote flow-induced PIE will also be explored, including flow through a microfluidic device containing pillar arrays, which serves as a model porous medium.