Analysis of the products of copolymerization with chain branching in the pregelation stage

The copolymerization of methyl methacrylate with small amounts (0.25‐1 mol %) of bis (4‐methacryloxybenzilidene)‐1,2‐diaminoethane in the pregelation stage was investigated. The mole fractions in the copolymers of the divinyl monomer, of the reacted vinyl groups of divinyl monomer, and of the totally reacted divinyl monomer units forming intermolecular crosslinks were determined experimentally and some other parameters were calculated from these quantities. The amount of intramolecular crosslinks, forming closed rings, has been shown to predominate over the amount of intermolecular crosslinks. The comparison of the experimental data with values calculated from Wesslau's theory, based on the classical concepts of copolymerization, reveals differences increasing up to an order of magnitude with rising content of the divinyl monomer. A major reason for this divergence appears to be the intramolecular crosslinking.