Dynamic Light Scattering for the Characterization of Polydisperse Fractal Systems: II. Relation between Structure and DLS Results

Abstract Dynamic light scattering (DLS) is frequently used to characterize suspensions of pyrogenic silica which consists of polydisperse fractal aggregates of sintered spherical primary particles. As the method primarily measures temporal fluctuations of scattered light caused by the translational and rotational diffusive motion of the aggregates it is an important prerequisite to identify those structural properties that are measurable with DLS and to quantify the method's sensitivity to changes in these properties. In a recent paper [1] we have investigated the structure‐hydrodynamics relationship via simulations. Here, the validation of the simulation results by experimental data is presented. Therefore, the structure of different pyrogenic silica grades has been characterized by static light and X‐ray scattering and the diffusional properties were obtained by multi‐angle DLS measurements. It is shown that the hydrodynamic radii determined with DLS scale well with the mean aggregate radius of gyration but that the influence of rotational diffusion has to be accounted for in the measurements.