Colloidal aggregation induced by attractive interactions

Colloidal aggregation induced by attractive interactions is tackled experim entally and by Brownian dynamics simulations using a mixture of positive an d negative particles. The structure of the aggregates and the aggregation k inetics are used to characterize the aggregation behavior. The clusters sho w uniform internal structures, with a fractal dimension lower than that of clusters formed in diffusion, indicating a more branched architecture. The aggregation kinetics also differs from the diffusive one, slowing down as t ime proceeds. Both results are totally confirmed by simulation. The transit ion from the attractive driven to the diffusion controlled regimes is studi ed varying the range of interaction. Continuous transitions are observed bo th for the aggregation kinetics and cluster structure. (C) 2001 American In stitute of Physics.