Microstructure, local dynamics, and flow behavior of colloidal suspensions with weak attractive interactions.

We present a comprehensive micro- and macrorheological study of the effect of weak depletion attraction (Ψ ≈ 1-10 kT) on dense colloidal suspensions stabilized by short-range repulsive interactions. We used aqueous polymer dispersions as model system and demonstrated the unique capabilities of multiple particle tracking (MPT) to disclose structural changes in such technically important systems exhibiting many characteristic features of hard sphere systems. Below the hard sphere freezing point ϕ, viscosity increases monotonically with increasing Ψ due to the transition from a fluid to a fluid/crystalline and finally to a gel state.