Modeling of the Methyl Methacrylate Atom Transfer Radical Suspension Polymerization Process: Polymerization and Particle Kinetics

Abstract

increase in viscosity), [15] suspension polymerization is one of the most important technologies applied in the poly merization industry. A key consideration in designing a suspension polymerization is to achieve such that desired molecular microstructure and droplet/particle size dis tribution (PSD) of polymers are satisfied. The number average molecular weight (M n ) and polydispersity index (PDI), as the most basic performance indices of polymer affecting the polymer enduse properties, are mainly determined by polymerization kinetics, and the PSD can control some key aspects of operation including suspen sion stability and productivity. Hence, there is a growing demand for studying suspension polymerization kinetics and its droplet/particle kinetics.For a suspension polymerization, two characteristic phases, i.e., the aqueous phase and the dispersed phase, are present. If the dissolved monomer in the aqueous phase is ignored, the polymerization process occurring at the suspension droplets will be considered as a bulk one.In this work, a mathematical model is developed to characterize the batch atom transfer rad ical suspension polymerization (batch suspension ATRP). For the first time, the morphological and molecular properties of particles, as well as their dynamics in methyl methacrylate ATRP can be simultaneously simulated by solving the model that consists of ATRP kinetic equations, moment equations, a phase equilibrium equation for calculating equilibrium monomer dis tributions in various phases, and a particle population balance model. The proposed model is verified using the open experimental data. Based on the verified model, two key operating factors including the ratios of monomer to initiator and water to monomer are studied in order to investigate the batch suspension ATRP kinetics. In addition, the model is also used to predict the droplet/par ticle size distribution. The effects of breakage rate, coales cence rate, and agitation speed on the droplet volume density distribution and the Sauter mean diameter are discussed in details. The simulated results demonstrate that the coupled model can describe the batch suspension ATRP kinetics and its droplet kinetics.

Conformational Distributions near and on the Substrate during Surface-Initiated Living Polymerization: A Lattice-Based Kinetic Monte Carlo Approach

“…Notably, computer simulations represent a powerful strategy to deal with limitations of the experimental characterization of polymer layers and polymers in general, including the quantification of the temporal evolution of average chain-length characteristics, monomer sequences, and the composition of polymer chains. − Several modeling techniques have been developed to study the kinetics of homogeneous polymerizations in general, distinguishing between deterministic and stochastic approaches. − In SIP, one typically focuses on only two of them, namely, the deterministic method of moments (MoM), which relies on solving a set of ordinary differential equations to calculate the change of the monomer conversion and average polymerization characteristics, − and the Monte Carlo (MC) method, as based on the consecutive sampling of reaction events or mass transfers (species movements) according to discrete reaction probabilities. , For example, Zhu et al − used MoM to study SI-CRP from flat solid surfaces and focused on the simulation of the temporal variation of monomer conversion, polymer-layer thickness, number-average molar mass, and dispersity in both phases. Assuming ballpark values for the rate coefficients involved, these authors found that the surface-tethered polymer chains displayed less controlled average molecular characteristics compared to those formed in the solution.…”

Multiscale Computational Fluid Dynamics–Population Balance Model Coupled System of Atom Transfer Radical Suspension Polymerization in Stirred Tank Reactors

“…However, given that the effect of polymerization was ignored, the complete flow fields in suspension polymerization reactors remained unclear. Recently, our group numerically simulated the multiphase flow characteristics and multiscale properties in various polymerization reactors. − Specifically, we built a coupled model comprising the CFD model, PBM, and polymerization moment equations. , However, we mostly focused on the macroscale gas–solid flow field instead of the liquid–liquid system. Wang et al , conducted several simulations to study the dynamic behavior of the atom transfer radical copolymerization (ATRcoP) in a continuous stirred-tank reactor (CSTR).…”

“…However, they only considered ideal reactors. Although previous studies have proposed a comprehensive model to simulate the batch suspension ATRP of MMA while considering the polymerization and particle dynamics, this model ignores the flow fields …”