Modelling of ring‐free crosslinking chain (co)polymerization

Modelling of copolymerization of a monounsaturated monomer and a bisunsaturated monomer with equal and independent reactivities of double bonds is described. No rings are assumed to be formed before the gel point, and uncorrelated circuit closing beyond the gel point is allowed. These assumptions are approximately met in the case of copolymerization of α, ω-unsaturated telechelic polymers. Modelling is based on a combination of kinetic and statistical polymer formation and crosslinking theories. The bisunsaturated monomer is split into two monounsaturated fragments and these fragments are copolymerized with the monounsaturated monomer to form ‘primary’ chains. The elementary reactions of initiator dissociation, initiation, propagation, chain transfer, and termination by recombination and disproportionation are considered. The primary chains are then recombined by joining fragments of the bisunsaturated monomers into branched molecules (sol) and gel. This step is performed by the formalism of the theory of branching processes (cascade theory) employing the generating functions transform. Examples of variations of molecular-weight averages of primary chains and branched molecules, gel fraction and concentration of elastically active network chains as a function of polymerization conversion for several sets of rate constants of elementary reactions are given. ©1997 SCI