Dynamic and static aspects of bimodal colloidal suspension

by Marcin Sikorski, APS, Argonne National Laboratory

Friday 4 Jun 2010, 10:00 → 11:00 Europe/Berlin

Bldg. 25b, room 109

Structure and dynamics of bimodal suspensions of latex spheres in supercooled glycerol were investigated using coherent synchrotron radiation using small angle x-ray scattering and x-ray photon correlation spectroscopy. Measurements were performed on a series of samples spanning the full range of relative concentration of large to small species. The arrangement of large particles was found to be well-described within the framework of the sticky hard sphere model. Outcome of the structural analysis is in good agreement with XPCS results, showing dramatic slowing down of dynamics within suspensions with the smallest content of large spheres. Excluding the largest length scales at the highest temperatures, the intermediate scattering function was found to have a stretched exponential form. Both dynamical parameters, namely the characteristic time scale for particle motion and the exponent ? show non-trivial length-scale dependence. A model based on depletion effect driven phase separation and formation of monomodal domains has been proposed to explain the results.