3D Monte Carlo Simulations of Diffusion Limited Cluster Aggregation up to the Sol-Gel Transition: Structure and Kinetics

Three-dimensional (3D) Monte Carlo simulations of diffusion limited cluster aggregation at different concentrations () show a crossover from a flocculation regime at short times to a percolation regime close to the gel time (t_g). Contrary to suggestions in the literature t_g is independent of the system size (L) for large L. The structural and temporal crossovers between flocculation and percolation take place at characteristic values of the cluster mass (m_c) and the time (t_c) which depend on . After normalisation by these characteristic values the crossovers are independent of except for very small clusters and at short times. The concentration dependence of m_c and t_c indicates that the crossover takes place at a given cumulated volume fraction of the clusters independent of . At low concentrations the -dependence of t_g is determined by the cluster growth in the flocculation regime.