Shielding effects in polymer-polymer reactions. IV. Intermolecular contact formation between star-branched molecules.

Pairs of star-branched molecules--taken from ensembles of athermal five-way cubic lattice chains prepared by Monte Carlo simulation--are analyzed for the relative probability of mutual contact formation between particularly specified segments i and j belonging to different chains within these pairs. These contact probabilities--termed shielding factors K(ij)--are calculated by means of exact enumeration as a function of chain length ranging from n = 8 to 256 bonds per arm, as a function of functionality (i.e., the number of arms) ranging from F = 2 to 6 arms, and as a function of segment position within the arms ranging from central to terminal segments. In addition, changes of properties that characterize the size and shape of the involved molecules while approaching and penetration are evaluated as a function of chain separation.