Computer simulation of irreversible gelation of polymers with stickers

The ''bond fluctuation model'' is used for Monte Carlo simulations of irreversible aggregation in solutions of associating macromolecules with regularly spaced stickers. The irreversible aggregation process follows the kinetically-limited-aggregation model first proposed by Eden. The fractal structures produced in the course of the aggregation are analyzed depending on the number of chains involved in the final cluster, n, chain length, N, and the number of stickers per chain, n(s). It is shown that the chains with n(s) greater than or equal to 2 form aggregates crosslinking the chains in a network-like structure. The mesh size of this network mainly depends on the chain length between two stickers; there is also a weaker dependence on the number of associating groups per chain, n(s). The chains connecting two aggregates turn out to be strongly extended. It is shown that the aggregates have a rather broad size distribution and that there is always a significant fraction of free single stickers. The inter- and intrachain screening effects control the local morphology of the aggregates.