EVOLUTION OF THE CLUSTER SIZE DISTRIBUTION DURING SLOW COLLOID AGGREGATION

We have made in situ dynamic light-scattering measurements to observe the real-time evolution to scaling of the light-scattering moments of a gold colloid cluster size distribution during aggregation in a slow aggregation regime. Quasi-monodisperse sols with significantly different aggregation rates evolved quickly to the same polydispersity in approximately equivalent reduced time units. This behavior and the experimental values of the asymptotic polydispersity agreed with numerical solutions to the coagulation equation and theoretical forms for the large-size part of the distribution. Numerical solutions showed, however, that the small-size part of the distribution does not reach its asymptotic scaling form in the time scales of our experiments. © 1990.