Cluster-size distribution in colloidal aggregation monitored by single-cluster light scattering

The aggregation of polymer colloids is studied in processes induced at high ionic concentration. Cluster-size distributions are measured with a single-cluster light scattering instrument constructed by our team. A brief description of the instrument is given and its proper performance is checked. The results are interpreted with the framework of Smoluchowski's equation. The rate constant for dimer formation is measured and compared with the theoretical prediction. Viscous interaction is taken into account to explain the differences. The temporal evolution of the number-average mean cluster size and the time-independent scaling function are determined from the cluster-size distributions. Dynamic scaling is observed even for small clusters and short aggregation times. Parameters λ and μ from Van Dongen and Ernst's classification scheme for homogeneous kernels are estimated and the aggregation mechanism is identified.