Effects of solvent in a kinetic gelation model

An irreversible, kinetic gelation model is used to study the effects of nondiffusive, solvent molecules on the universal behavior of the sol-gel transition. This model includes molecules on a simple cubic lattice with fixed concentrations of bifunctional and tetrafunctional monomers and zero-functional solvent. Bond formation is accomplished through the random motion of active centers (radicals). The effects of varying lattice size, active-center concentration, and solvent concentration on the trapping of active centers are determined. Finite-size scaling analyses of this growth process give estimates for the average-molecular-weight exponent $\gamma$, the gel fraction exponent $\beta$, the correlation exponent $\nu$, and the ratio of critical amplitudes $R$ of the average molecular weight in the vicinity of the gel point. Evidence indicates that there is no change in the universal behavior of this model when solvent molecules are added.