Dynamics in colloid and protein systems: hydrodynamically structured particles, and dispersions with competing attractive and repulsive interactions

In this thesis, we develop and apply a toolbox of versatile theoretical methods of calculating structural, and short-time and long-time dynamic properties of three classes of industrially important dispersions. The rst one are suspensions of hydrodynamically structured colloidal particles, and here most notably non-ionic microgels. The second class are dispersions of submicron sized charge-stabilized colloidal globules, and the third one are globular protein solutions with competing short-range attraction (SA) and long-range repulsion (LR). The results for the transport, structure, and thermodynamic properties of charge-stabilized colloids are used as input in our realistic macroscopic diusion-advection modeling of the membrane cross- ow ultraltration of silica particles dispersions. The thesis bridges thus the gap from the theoretical exploration of intra-particle properties such as solvent permeability, particle softness, and surface charge, to the calculation of transport, structural, and thermodynamic properties of concentrated dispersions, and to the modeling of a technologically important ltration process. The accuracy of our toolbox methods is assessed by the comprehensive comparison with experimental measurements of, and simulation results for static and dynamic properties. The considered dynamic properties include short- and long-time self-diusion and sedimentation coecients, the wavenumber-dependent diusion function determined routinely in dynamic scattering experiments, and the zero- and high-frequency shear viscosities. In particular, we provide various analytic transport coecient expressions for rigid permeable particles that can be readily used for the analysis of dynamic scattering and rheology data. The toolbox methods for the calculation of transport properties of concentrated dispersions of globular colloidal particles with internal hydrodynamic structure are based on the hydrodynamic radius model (HRM) wherein the internal particle structure is mapped on an eective hydrodynamic radius for unchanged direct interactions. The good performance of the HRM is demonstrated by comparison with dynamic light scattering experiments on concentrated suspensions of solvent permeable non-ionic microgels. Furthermore, we quantify the eect of particle softness and permeability on the dynamics of ionic microgel suspensions, and we characterize the particle interactions and microstructure in polydisperse amphoteric microgel systems in the zwitterionic regime.