Role of Surface Roughness in Colloidal Dynamics of Dense Suspensions

Topographical characteristics of colloidal particles can drastically alter the particles' thermal (or Brownian) motions in concentrated suspensions. While particle surface roughness has been shown to influence various macroscopic behaviors strongly, microscopic understanding of particle dynamics at high concentrations is lacking. One of the main reasons for this is that surface rough colloidal particles with explicit roughness characteristics are not easily accessible. In addition, resolving the rotational motion of particles with spherical symmetry is not trivial due to the lack of natural optical anisotropy. Disentangling the topography's role from the other colloidal properties, such as shape anisotropy and directionality of the interactions, starts with a model system with well-characterized properties and accessing colloidal dynamics on a single particle level in terms of rotations and translations. To disentangle the specific role of topography from other shape and geometry-dependent particle features, this thesis focuses exclusively on hard, globally spherical colloidal particles with well-defined roughness geometry. In this thesis, two different methods to obtain surface rough particles are provided to address the absence of model systems. Then, one model system with well-defined topography characteristics and optical anisotropy is used to reveal the effect of roughness on colloidal dynamics near the glass transition.