Comparison of structural properties of different polymer network types as obtained by computer simulation

摘要

Using large-scale Monte Carlo simulations we study the properties of randomly cross-linked ordered AB diblock copolymer melts as a function of the A-B repulsion parameter. We compare the results to those for cross-linked homopolymer melts and for disordered diamondlike networks. We analyze the structure of the resulting networks using measures we borrowed from the theory of fractals. These are the chemical dimension obtained by counting the number of neighbors in a shell for a prescribed chemical distance (counted along the bounds) and a dimension which characterizes the relation between the masses of network clusters and their radius of gyration in 3D. Modified diamondlike topologies can only partly reproduce the structural properties of randomly cross-linked chains, which show a large crossover region with dimensions smaller than 3. A decrease in the A-B repulsion leads to the loss of order. Cross linking can only partly stabilize the ordered structures; in a large region of cross-link densities above the gel point the removal of the interaction still leads to structural disorder.