Dynamics of Spontaneous Emulsification in Microchannels

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This award will investigate the basic multiphase flow properties of mixtures made of oil, water, and organic solvents at small scales. The phenomenon of spontaneous emulsification refers to the natural formation of droplets due to the presence of a miscible solvent in oil-water systems and offers great opportunities for tailoring the properties of soft materials and developing innovative methods for the treatment of oil and aqueous products in a range of industries, including pharmaceutical, personal care, food, energy, and in the environment. While the multiphase flow behavior of pure substances is relatively well understood, less is known about the influence of fluid additives, which significantly alter material properties and flow arrangements. Here, an integrated suite of teaching and research activities is designed to unravel the physics of multiphase flows in the presence of miscible solvents and develop new predictive knowledge into an array of captivating fluid phenomena of fundamental and practical interests. This award will provide a wide range of educational opportunities for a diversity of students in an inclusive and well-structured environment and original outreach activities will stimulate the curiosity of the public at large.This award will formulate the relationships between material properties and liquid-liquid multiphase flows using advanced microfluidic protocols. A series of hypothesis-driven inquiries will quantitatively elucidate various microscale transport phenomena resulting from the addition of miscible solvents, such as alcohols, in immiscible liquid-liquid multiphase flows. Alcohols compose an important class of simple organic compounds with a myriad of practical uses as extractants, antiseptics, detergents, biofuels, wetting agents, viscosity modifiers, or emulsifiers. The proposed research will lay the scientific foundations for improved manipulations of aqueous-oil multiphase flows with alcohol solvents and characterize out-of-equilibrium fluid interactions resulting from the interplay of interfacial tension and diffusion phenomena in microflow geometries. Functional relationship of flow pattern characteristics will be established across a broad range of solvent concentration for both ‘water-in-oil’ and ‘oil-in-water’ multiphase flows. Interfacial phenomena leading to the generation of colloidal dispersions at ultralow interfacial tension will be methodically accessed over vast ranges of length-scales and timescales using well-characterized microgeometries and leading-edge imaging and diagnostic techniques. Broad variations of flow velocity and fluid properties will delineate significant regions of uncharted flow regimes and enable opportunities for scientific discoveries. Ultimately, a general, unifying theoretical framework will be developed to characterize the role of liquid solubility on the fundamentals of multiphase flows.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.