Brown University School of Engineering

Fluids Seminar: Magnetic Nanorods for Probing Rheology of Nanoliter Droplets, Making Reconfigurable Lattices, and Sharpening Liquid Surfaces on Demand

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Tuesday, March 11, 2014 3:00pm - 4:00pm

Konstantin G. Kornev, Departments of Materials Science & Engineering Clemson University Clemson, SC http://www.clemson.edu/ces/kornevlab/ Magnetic Nanorods for Probing Rheology of Nanoliter Droplets, Making Reconfigurable Lattices, and Sharpening Liquid Surfaces on Demand Magnetic nanorods are attractive materials enabling assembly, ordering, control, and reconfiguration of different magnetic lattices within milliseconds. MilliTesla magnetic fields are sufficient to manipulate with these nanorods. In this talk, a few examples of applications of magnetic nanorods will be shown. First we will discuss the remote controlled rotation of magnetic nanorods providing a new nanoscale tool to probe different properties of liquids and solids at the micrometer scale. In particular, we will show that with magnetic nanorods one can address the current challenge of the in situ characterization of minute amounts of fluids rapidly changing their rheological properties. Basic theory of Magnetic Rotational Spectroscopy for rotation of a magnetic nanorod in non-Newtonian fluids will be introduced and specific features of rotating nanorods will be explained. Then we will experimentally demonstrate that magnetic rotational spectroscopy provides rich physicochemical information about the gelation processes of polymers and sols. Then we introduce a new physical principle of self-assembly of magnetic nanorods into droplets of different sizes without using any nozzle. These droplets can be formed on demand by taking advantage of the specific magneto-static interactions between nanorods. Using X-ray phase contrast imaging and scaling analysis we will explain the behavior of magnetic paranematics and their interactions with the droplet surface.