International Research Fellowship Program: Surface Forces Between Two Oil Drops in Aqueous Solutions: Measurements and Interpretation Using Atomic Force Microscopy

Dagastine Raymond R, Pittsburgh PA

Investigators

Abstract

0202675 Dagastine The International Research Fellowship Program enables U.S. scientists and engineers to conduct three to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad. This award will support a twenty-four month research fellowship by Dr. Raymond R. Dagastine to work with Dr. Franz Grieser at the Particulate Fluids Processing Center at the University of Melbourne in Parkville, Victoria, Australia. The goal of this project is to quantitatively study forces between two oil drops in the presence of a variety of different types of emulsifiers and surface-active additives. The PI will develop an experimental approach to measure these forces directly using atomic force microscopy (AFM) and a theoretical framework for interpretation of these measurements. The approach builds on his work on the interpretation of measurements between a single oil drop interacting with a rigid probe. The additives and emulsifiers that are common in industrial processes are commonly amphiphilic molecules, which partition themselves in the oil-water interface. Adsorption to the interface can be competitive or cooperative and the increased mobility of these absorbed species can provide different force behavior than that of the same species absorbed at solid-liquid interfaces. This work will provide correlation between additives and emulsifiers in oil-water emulsions and the interparticle between drops, leading to insight in formulation, emulsion stability, and processing. Understanding of the interaction forces between liquid-liquid interfaces, where attraction between droplets can lead to coalesce and phase separation in emulsions, is vital to predict and model emulsion stability in processing and storage situations. The Particulate Fluids Processing Center is part of the world-leading program in colloidal and interfacial science research that has been established at the University of Melbourne for more than twenty years. Dr. Grieser is a leader in making AFM measurements at liquid-liquid interfaces.