| Our lab studies how confinement modifies the structure and dynamics of densely packed colloidal suspensions. Colloidal suspensions are composed of micron-sized particles in a liquid, and the particles diffuse due to Brownian motion. The diffusion constant decreases rapidly as the volume fraction phi is increased toward phi = 0.58, which has been identified as the colloidal glass transition point. When a colloidal suspension is confined to a small region we find the sample behaves glassier: diffusion is slower for a given phi than in an unconfined sample. We observe this motion using confocal microscopy in samples confined in one, two, or three directions. We have also conducted simulations of random-close-packing in 2D and 3D confined geometries, to give us intuition about how confinement, close-packing, and dimensionality relate to the colloidal glass transition. |
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