Dynamic properties of liquid states in systems with a short-range attraction and long-range respulsion

Colloidal systems with a short-range attraction and long-range repulsion have been intensively studied in the past decade. A generalized phase diagram has been proposed with multiple liquid states. Using lysozyme as a model system, we have identified different liquid states of previous experimentally studied lysozyme samples within this generalized state diagram and explore the dynamic properties of each liquid state. Most lysozyme samples studied previously at low and intermediate concentrations are dispersed fluid states while a few high concentration samples are randomly percolated liquid states. In the dispersed fluid state, the short-time diffusion coefficient measured is found insensitive to the attraction strength, while it is very sensitive to the attraction strength in random percolated fluids. At high enough concentrations, the mean square displacement can be as slow as those of many glassy colloidal systems at time scales near the characteristic diffusion time even though these lysozyme samples remain in liquid states at the long-time limit. A localized glassy state is further identified by the mean square displacement.