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

Abstract

Monte Carlo methods were applied to the reaction kinetics and polymer diffusion at play during the dynamics of creating structured latex particles. Reaction kinetic events in both the water phase and the particles are combined with diffusion of polymer radicals in the particles to allow the prediction of the overall polymerization kinetics, including the Trommsdorf gel effect, chain transfer reactions to monomer, chain transfer agents (e.g., thiols) and polymer chains, and chain length dependent termination reactions. This allowed the calculation of latex particle morphology, as well as the polymer molecular weight, gel content and graft level, when applicable. A number of examples are used to provide experimental data with which to compare the Monte Carlo predictions.magnified image

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

“…It should be pointed out that eq 28 is expanded from Karlsson et al 22 to incorporate the difference in radius of interaction between polymer chains "i" and "j". The radius of interaction for a reaction is given in terms of the average number of repeat units between entanglements (j c ) as 22 (29) where a is the root mean squared end-to-end distance per square root of the number of monomer units in a chain. The value for j c can be obtained for a chain end radical as 23…”

Композиционные Полимерные Суспензии Со Сложной Морфологией Частиц

“…Существуют полимерные частицы несферической формы [29], частицы типа «конфетти» (малинообразные) [30], частицы с внутренними пустотами [31], звездообразные частицы [32]. В литературе описано большое количество методов синтеза композиционных полимерных частиц [49].…”

The Structural Evolution of Composite Latex Particles During Starve‐Fed Emulsion Polymerization: Modeling and Experiments for Kinetically Frozen Morphologies

“…The mathematical model, in great detail, has been presented in previous publications27, 28 and will not be presented again here for the sake of brevity. Suffice it to say that the termination and propagation reactions are treated as diffusion controlled events and that their rate coefficients are written in terms of the diffusion coefficients of the radical species involved in the reactions.…”

“…The latter two are dynamic variables, in that the chain length for each oligomeric radical increases by one unit each time it propagates and the monomer concentration may (and usually does) change with time during the polymerization process; this is fully described in a previous publication 27. The solution to the set of rate equations was at first carried out by standard numerical methods,27 but now done by the Monte Carlo technique 28…”