AGGREGATION PHENOMENA

We report on low-angle static light scattering measurements on colloidal aggregation of polystyrene latex particles. Measurements have been performed both at low and high monomer concentrations. Pure diffusion limited cluster aggregation (DLCA) have been investigated in the dilute regime. The predicted power-law growth of the radius has been observed. Spurious effects due to the presence of gravity are reported. Measurements on the high concentration samples show an unexpected and quite novel phenomenon. A peak in the scattering pattern whose position q(m) moves towards smaller q-values and whose height grows in time has been observed. We have found that the scattering distributions can be scaled onto the same master curve with a scaling law strongly reminiscent of that working in the completely different case of spinodal decomposition.