Equilibrium cluster formation and gelation

We study the formation and growth of equilibrium clusters in a suspension of weakly charged colloidal particles and small non-adsorbing, polymers. The effective potential is characterized by a short-range attraction and a long-range repulsion. The size, shape and local structure of the clusters are studied using three-dimensional particle microscopy. We observe a rapid growth in the mean cluster size and the average number of nearest neighbours approaching the gel boundary.