CAREER: Microstructure of Jammed Particulate Matter

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****NON-TECHNICAL ABSTRACT****This Faculty Early Career Award supports a project with a goal of understanding the structure and dynamics of randomly packed particles. At a given density, particulate systems pack into a mechanically stable and amorphous jammed state whose geometry is hidden from view. This project will therefore employ transparent, fluorescent emulsions (a suspension of droplets of one liquid in another) to look through the packing of the droplets in 3D using a special type of microscope called a confocal microscope. The resulting geometry of the packing will then test the principles of the random organization of the particles as a function of parameters, such as the pressure, the protocol by which the packing is created, the distribution of sizes of the particles and the interaction between the particles. This study aims to lead the way to a novel theoretical understanding of packing inspired by experimental data. This problem is of relevance to fundamental research and to many industries, ranging from oil extraction through porous rocks, to grain storage in silos and the compaction of pharmaceutical powders into tablets. The integration of the research in the laboratory and the science education in the New York area and beyond will take place on a new mobile facility called the Biobus. Since its start in 2007, the BioBus has reached over 10,000 students at more than 30 different minority-serving institutions and has received an extremely positive response from students, teachers, and the media alike.****TECHNICAL ABSTRACT****This Faculty Early Career Award funds a project with a goal of developing an understanding of random packing on the microscopic scale. A confocal microscope will be employed to study jammed particulate matter, using an emulsion system. The study of jammed materials will then be extended to their dynamic rheological and micromechanical properties. Having experimental access to the forces between individual particles and their rearrangement, the microscopic mechanisms of stress relaxation and energy dissipation in these systems will be assessed. Understanding packed particulate materials with statistical models, would not only impact industrial processes, such as oil drilling or grain storage, but also provide broad insight into the behavior of complex systems experiencing structural arrest. Along with training high-school, undergraduate and graduate students who participate in the research in the area of soft-condensed matter physics, the educational plan involves K-12 outreach through a novel science education facility called the Biobus. The mobile lab provides school students with a dynamic, hands-on science curriculum: one that fosters exploration of the natural world, which will help develop the next generation of scientists.