The reaction locus in supercritical carbon dioxide dispersion polymerization. The case of poly(methyl methacrylate)

Dispersion Polymerization of Methyl Methacrylate in Supercritical Carbon Dioxide: Control of Molecular Weight Distribution by Adjusting Particle Surface Area

“…On the other hand, a generally good agreement is apparent in terms of conversion and/or MWD for all the other experiments (C to H) when adjusting the particle specific surface. It is then confirmed that the interplay between particle size and polymerization rate is a key peculiarity of the dispersion polymerization in supercritical media: as shown previously, [1,24,25] depending on the extent of interphase surface area, the predominant locus of polymerization reaction shifts from the continuous to the dispersed phase. Such shift is clearly shown by the conversion curves for polymerization runs A through H in Figure 3.…”

“…[27][28][29] More details about the derivation of the equations and the numerical solution can be found elsewhere. [1,24,25] All model parameters have been taken from reference [25] without any further adjustment except for the particle surface area A p . In fact, in polymerization run A, where a stable dispersion of spherical particles with narrow size distribution has been obtained, it is possible to estimate the final particle radius r f p from the scanned electron microscopy (SEM) photographs shown in Figure 1.…”

“…The first comprehensive model of dispersion polymerization in scCO 2 has been reported by Chatzidoukas et al [22] This model is conceptually identical to that proposed by the same group for the suspension polymerization of poly(vinyl chloride) whereas the growing radical chains remain segregated in the phase where they were formed. [23] In a previous contribution [24] we showed that the latter model is unlikely to be applicable for the polymerization system under consideration when using reasonable parameter values and thus prompting us to develop a new model accounting for the detailed description of the radical interphase transport. [25] The so-called V-analysis introduced in the same work was focused on the comparison of the characteristic times of termination and interphase mass transport.…”

Dispersion copolymerization of acrylonitrile‐vinyl acetate in supercritical carbon dioxide

“…This is because the polymerization takes place in two loci, the supercritical continuous phase and the polymer-rich phase. 38,40 When the stabilizer concentration is above 5 w/w%, the stabilizer reaches saturation in the supercritical continuous phase. So further increasing the stabilizer content has negligible effect on yield and M v .…”

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

“…[30] Comprehensive models allow computation of the full molar mass distribution (for linear cases) by using phase equilibrium, a kinetic description of the reaction and mass transport calculations. [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.…”