Modelling of intramolecular reactions in the step-growth polymerization of multifunctional monomers

Abstract

A general kinetic model for the polymerization of multifunctional monomers RY_f valid up to the gel point has been presented, which accounts for the intramolecular reactions. In this model, various molecular species have been distinguished on the basis of the total number of intramolecular bonds existing on them. Various reactions leading to formation and depletion of a molecular species of given degree of polymerization are identified and the differential mole balance equations for these have been written down. The intramolecular rate constant has been assumed to be that proposed by Plate and Noah (based on their Monte Carlo studies of intramolecular reactions) and the various mole balances have been solved numerically. Numerical computations confirm that, as the gel point is approached, larger polymer chains are formed and these have a higher tendency to react intramolecularly. However, even at high conversions, the average number of rings per polymer chain remains small, which is consistent with experimentally observed results.