Monte Carlo Simulations of Free Radical Polymerizations with Divinyl Cross-Linker: Pre- and Postgel Simulations of Reaction Kinetics and Molecular Structure

Abstract

A computationally efficient Monte Carlo method was used to simulate the reaction kinetics and molecular structure development during free-radical copolymerizations with divinyl monomers. A single parameter was used to describe the reduced reactivity of the pendent vinyl groups incorporated within the polymer backbone. The simulation results were compared with published experimental data for the bulk copolymerization of methyl methacrylate with different levels of ethylene glycol dimethacrylate. The model was able to effectively predict the reaction kinetics, the gel point, and sol−gel fractions in both the pre-and postgel regimes, including the swelling index of the gel. In the postgel regime the cross-linked molecule becomes the primary locus of reactions, and all chains eventually become part of this massive cross-linked polymer network. The Monte Carlo method allows the determination of the complete molecular structure as it evolves with time, including properties like cross-linking density, number of free chain ends, primary cycles and loops, and the fraction of unreacted pendent vinyl groups.

Cross‐linking photopolymerization of monoacrylate initiated by benzophenone

“…This suggests that the cross‐linking reaction proceeds with the formation of another polymer chain during polymerization as previously reported . This happens more quickly, when the amount of cross‐linkers is larger . In this study, the final gel conversion in the polymerization without PP cover film was higher than that with PP cover film (Fig.…”

“…Once the total conversion reached to the gel point, the gel fraction of the resultant polymer increased rapidly. This suggests that the cross‐linking reaction proceeds with the formation of another polymer chain during polymerization as previously reported . This happens more quickly, when the amount of cross‐linkers is larger .…”

Acceleration of kinetic monte carlo simulations of free radical copolymerization: A hybrid approach with scaling

“…The second reason KMC methods are attractive is that polymer molecules with different microstructures, including sequence distribution, branching and crosslinking, are described explicitly. In KMC simulations, it is relatively straightforward to construct and record the microstructure for each polymer chain …”

“…In KMC simulations, it is relatively straightforward to construct and record the microstructure for each polymer chain. 9,12,21,24 Due to these advantages, applications of KMC to polymerization have been rapidly growing in recent years. For example, Tripathi et al applied kinetic Monte Carlo methods to simulate free radical polymerization with a divinyl crosslinker, revealing features related to reaction kinetics and molecular structure.…”

“…For example, Tripathi et al applied kinetic Monte Carlo methods to simulate free radical polymerization with a divinyl crosslinker, revealing features related to reaction kinetics and molecular structure. 12 Al-Harthi et al modeled atom transfer radical polymerization of polystyrene and obtained accurate molecular weight distributions at any instant of the reaction time. 18 Mohammadi et al used a KMC model to study the effect of reactivity ratios and initial feed composition on the properties of copolymers produced by free radical polymerization, with detailed prediction of copolymer composition and sequence distribution as a function of monomer conversion.…”