MWN for the Study of Macromolecular Ferrofluids Judy S. Riffle, Virginia Polytechnic Institute and State University, DMR 0602932.
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PDMS-Magnetite nanostructures have been rationally designed to form neat ferrofluids that can be remotely manipulated with magnetic fields. We have a modeling tool for calculating the sizes of sterically-stabilized single-particle complexes to an accuracy within 10%. Using a modified DLVO theory for particle interactions, this tool also predicts the onset of colloidal instability in these magnetic suspensions.
Top figure: A representative TEM image shows a well-defined magnetite core. Bottom figure: Particle histograms of repeated magnetite syntheses show a high degree of reproducibility.
Table: Comparison of number average diameters Dn from dynamic light scattering (DLS) with those predicted by the model, with no adjustable parameters, show excellent agreement.
Remote Shape Control of Macromolecular Ferrofluid DropletsJudy S. Riffle, Virginia Polytechnic Institute and State University, DMR 0602932
The Materials World Network for the Study of Macromolecular Ferrofluids addresses the chemistry, engineering and physics that govern remote control over the shapes and locations of magnetic droplets suspended in immiscible media. Top: Raquel Mejia-Ariza (left, VT student) and Annette Tyler (right, UWA student) collaborate at VT to understand the influence of interfacial tension on the shapes of magnetic PDMS droplets in uniform magnetic fields. Bottom: Droplet shape in uniform fields results from a balance between particle alignment induced by the field and interfacial energy.
1. S. Afkhami, Y. Renardy, M. Renardy, J.S. Riffle, T.G. St. Pierre, J. Fluid Mechanics, 610, 363-80 (2008).
2. O.T. Mefford, M.L. Vadala, M.R.J. Carroll, R. Mejia-Ariza, B.L. Caba, T.G. St. Pierre, R.C. Woodward, R.M. Davis, J.S. Riffle, Langmuir, 24(9), 5060-69 (2008).