Continuum percolation and depletion flocculation

Using Brownian dynamics simulations, we investigate continuum percolation in a system of colloid particles aggregating due to depletion flocculation. For all values of aggregating potential, there is a lower threshold volume fraction of colloid particles at which a percolating cluster appears. This threshold defines a percolation "phase" boundary that crosses the phase boundary between the colloid fluid phase and colloid fluid+crystal coexistence. In the two-phase coexistence regime, the lifetime of percolated clusters increases dramatically, and therefore the percolation threshold may be related to a transient gel threshold reported from experiment. In the phase coexistence regime, there is, evidence of aging due to the thermal restructuring of clusters, implying a finite lifetime for percolating structures. (C) 1998 American Institute of Physics.