Simulation model for the molecular weight distribution in emulsion polymerization

Abstract

A Monte Carlo simulation model for the kinetics of emulsion polymerization is proposed. In the present model, the formation of each polymer molecule is simulated by the use of only a couple of probability functions; therefore, the calculation can be handled well even on personal computers. It is straightforward to account for virtually any kinetic event, such as the desorption of oligomeric radicals and chain length dependence of kinetic parameters, and as a consequence very detailed information such as the full distributions of the dead polymer molecular weights and the macroradicals among various polymer particles can be obtained. When bimolecular terminations are the dominant chain stoppage mechanism, the instantaneous molecular weight distribution (produced in a very small time interval) becomes broader than that for homogeneous polymerizations due to a higher possibility that short and long polymer radicals react with each other if bimolecular reactions are fast enough. The increase in the polydispersity of the MWD is fairly large, especially when bimolecular termination by disproportionation is significant; however, the gel permeation chromatography (GPC) may not be a suitable analytical technique to detect such broadening since oligomeric peaks may not be observed in the elution curve. The present simulation method provides greater insight into the complicated phenomena of emulsion polymerizations. © 1995 John Wiley & Sons, Inc.

Effect of Small Reaction Locus in Free-Radical Polymerization: Conventional and Reversible-Deactivation Radical Polymerization

“…Because the exit of trapping agent is expected to be more significant for smaller particles, the polymerization rate may not decrease with the third power of dp. Experimentally, the decrease in polymerization rate by decreasing the particle size is reported [17], but not with dp 3 .…”

“…In this case, Equation (5) leads to the threshold diameter, d p1q p,R = 252 nm. Figure 2 shows the calculated results based on the Monte Carlo (MC) simulation method proposed in [3,12], with k p = 500 L¨mol´1¨s´1. It is clearly shown that the polymerization rate increases significantly for d p < 250 nm, which shows excellent agreement with Equation (5).…”

“…This is the case for suspension polymerization. In general, when the average number of radicals in a particle is larger than 2, the pseudo-bulk polymerization kinetics can be applied [3], at least approximately. On the other hand, when the particle diameter is smaller than ca.…”

Monte Carlo Simulation of Emulsion Polymerization Kinetics and the Evolution of Latex Particle Morphology and Polymer Chain Architecture

“…About 20 years ago Chern and Poehlein [22,23,27] looked at non-uniform radical distributions in latex particles and went on to apply the MC method to phase separated particles and also to grafting reactions. Asua [24] soon followed with another treatment of chain end anchoring, and then Tobita [28][29][30][31][32][33] followed with a series of papers utilizing MC techniques with particular emphasis on molecular weight distributions, chain transfer and cross-linking. Jabbari [34,35] applied similar techniques to the emulsion polymerization of butadiene and copolymers.…”

Bayesian Modeling and Markov Chain Monte Carlo Simulations for a Kinetic Study of Homo‐ and Co‐ Polymerization Systems

“…This versatility enables us to handle complicated kinetic processes in a straightforward manner, provided each kinetic process, or the transition probabilities, can be defined explicitly. [2,3] Specifically, in the case of complex reaction schemes where deterministic methods require a high level…”