A Comparison of Modeling Approaches for Dispersion Homopolymerization of MMA and Styrene in Supercritical CO₂

Abstract

A comparison of kinetic models for dispersion polymerization of MMA and styrene in supercritical CO2 is presented. The limiting case of solution polymerization, as a simplified case, was also addressed. Calculation of the partition of components between the continuous and dispersed phases was emphasized. Experimental data for the solution and dispersion polymerizations of styrene and MMA, using different types of stabilizers, were used to guide the study. Although all the models analyzed can be considered as “adequate” in representing the behavior of the system, some of their strengths and drawbacks have been highlighted.

Modeling of RAFT Copolymerization with Crosslinking of Styrene/Divinylbenzene in Supercritical Carbon Dioxide

“…Kiparissides et al [47] and Quintero-Ortega et al [35,36] used a simple model for the partition of monomer and initiator between continuous and dispersed phases in the modeling of dispersion polymerization of vinyl and vinyl/divinyl monomers in scCO 2 . Likewise, in our model it is assumed that the polymerization occurs in three stages.…”

“…[35,36] If the aforementioned ratio is not constant, a correction factor, F I , can be used, as shown in Equation ( The ratio of amount of RAFT agent in the continuous to that in the dispersed phase is defined in Equation (55). The initial amount of crosslinker in each phase was assumed to be the same, as shown in Equation (56)…”

“…[31][32][33][34] On the other hand, simplified models, such as the method of moments, and simple equilibrium calculations have been also used to describe the behavior of these simpler systems. [35][36][37] To the best of our knowledge, the modeling of copolymerization kinetics, molar mass development, and gel fraction evolution for vinyl/divinyl monomers in the presence of RDRP controllers, in scCO 2 , has not been addressed or has been addressed assuming a single phase situation. [38] In this contribution, we use a multifunctional polymer molecule approach developed in our group, [39] along with a simple partition of the main components in the scCO 2 -rich and polymer-rich phases, to model the RAFT copolymerization with crosslinking of vinyl/divinyl monomers in scCO 2 .…”

Graft Copolymerization of Styrene and Acrylonitrile in the Presence of Poly(propylene glycol): Kinetics and Modeling

“…In general, partition coefficients of small molecular weight species between a dispersed phase and a continuous phase are determined by phase equilibria 9, 10. Some phase equilibrium models have been developed to estimate partition coefficients of small molecular weight species in heterogeneous polymerization systems, such as dispersion polymerization of St in alcohol and/or water,11–13 dispersion polymerization of methyl methacrylate (or vinylidene fluoride) in supercritical carbon dioxide,14–16 two‐phase polymerization of acrylamide in aqueous poly(ethylene glycol) solution,17 and emulsion polymerization of St and AN 18. In our previous work,19 we studied the phase equilibria of the quaternary St‐AN‐SAN‐PPG system, which can provide reasonable partition coefficients of St and AN in polymerization.…”

Copolymerization of VDF and HFP in Supercritical Carbon Dioxide: A Robust Approach for Modeling Precipitation and Dispersion Kinetics

“…Nevertheless, such drawback is somehow counterbalanced by the easy recovery of very pure polymer by simple depressurization at the end of the reaction, without any need of polymer purification steps. Many papers and reviews have been published addressing the main features of the polymer/scCO 2 thermodynamics,2, 3 as well as those of polymer synthesis, modeling of polymerization kinetics, and polymer processing in scCO 2 4–11…”