4th International Symposium on Slow Dynamics in Complex Systems
DEC 02-07, 2012
Glass formers constitute of anisotropic particles was mainly studied by simulations in three dimensions with incomplete phase diagrams. Here we studied the structures and the glassy dynamics for translational and rotational motions in quasi-two dimensional (2D) suspensions of colloidal ellipsoids at the single-particle level. At high densities, ellipsoids with large aspect ratio formed psuedo-nematic domains. Video microscopy revealed a two-step glass transition: rotational motion first becomes glassy due to the inter-domain freezing, then translational motion become glassy at a higher density due to inner-domain freezing. Between the two transitions, ellipsoids formed an "orientational glass". Below and near the respective glass transition densities, the rotational and translational fastest-moving particles moved cooperatively and formed clusters with power-law size distributions. The mean cluster sizes diverge in power law as approaching the glass transitions. The fast translational particles concentrated in pseudonematic domains and form band-like clusters while the fast rotational particles mainly located around domain boundaries and form branch-like clusters.