Reactivity and gelation. I. Intrinsic reactivity

The method of Case is used with the Flory-Stockmayer gelation criterion to derive a critical transition equation for polycondensation of multifunctional reactants bearing coreactive functional groups of two species A and B, where the B groups may be of unequal intrinsic reactivity. Systems of the types R(A)2/R′(B)4 and R(A)2/R′(B)4/R′′(B)2 are considered with the B groups divided into two classes characterized by a reactivity ratio in the range 0.1 to 10. If the reactivities are sufficiently different the polymerization can be regarded as a multistage process. Intramolecular reactions are not considered.