Simulations of sol-to-gel modeling: Effects of mobility, reversibility, and quality of solvent

Some of our recent work on computer simulation modeling of the sol-to-gel t ransition for the polymerization by step reaction are presented. Depending on the variants of the model, a random distribution of bifunctional and tet rafunctional monomers of concentration C-2 and C-4 respectively, and their chains (bond-fluctuating) are used as primary reacting units on a simple cu bic lattice as the initial sol-phase. Effects of solvent, temperature, mobi lity of monomers, rate of reaction, and reversibility are considered in und erstanding the evolution of microgels, onset of gelation and the nature of sol-to-gel transition, inhomogeneity, etc. Gel point (p(c), gel volume frac tion (P-G), weight average degree of polymerization (M-W), structure factor (S(q, t)) show various interesting variations with the conversion factor ( p). For example, sol-to-gel transition seems nonuniversal with respect to q uality of the solvent, degree of inhomogeneity depends on the quality of so lvent and rate of reaction due to interplay between the phase-separation an d cross-linking.