Short-time dynamics in dispersions with competing short-range attraction and long-range repulsion

The dynamic clustering of globular particles in suspensions exhibiting competing short-range attraction and long-range repulsion such as in protein solutions has gained a lot of interest over the past years. We investigate theoretically the influence of clustering on the dynamics of globular particle dispersions [1]. To this end, we systematically explore various pair potential models by a combination of state-of-the-art analytic methods in conjunction with computer simulations where the solvent-mediated hydrodynamic interactions are likewise included. Our theoretical results show that the cluster peak (intermediate-range-order peak) is present also in the hydrodynamic function characterizing the short-time dynamics, in accord with new experimental data [2]. Enhanced short-range attraction leads to a smaller self-diffusion coefficient and a larger dispersion viscosity. The behavior of the (generalized) sedimentation coefficient is more intricate, e.g. showing a non-monotonic interaction strength dependence. \begin{itemize} \item [{[1]}] J. Riest \& G. N\"agele, \textit{Soft Matter} (2015). doi:10.1039/C5SM02099A \item [{[2]}] Collaboration with D. Godfrin (NIST \& MIT), Y. Liu (NIST) and N. Wagner (UDEL), work in progress \end{itemize}