Association Equilibrium and Gelation in Solutions of Cross-Associating Chains Containing Inactive Fragments

Solutions of two cross-associating chain molecular species ( n -chains and p -chains) containing both associative (“sticky”) and non-associative monomer links have been simulated by molecular dynamics. The inactive monomers increase the stickers’ association equilibrium constant due to the excluded volume effect. In a wide concentration range, the equilibrium constant can be approximated as a simple function of the total volume concentration of the inert monomers, the volume effectively excluded by one inert monomer being about the same at different mixture compositions. Characteristics of molecular aggregates formed at pre-gelation and gelation conditions are examined, including effects of local cyclization.