Copolymerization of partly incompatible monomers: an insight from computer simulations

TL;DR

This study uses dissipative particle dynamics simulations to explore how spatial heterogeneities and incompatibility between monomers influence copolymerization, sequence structure, and phase segregation, validated against experimental data.

Contribution

It introduces a simulation approach to predict copolymer sequences and phase behavior considering monomer incompatibility and heterogeneities, extending understanding of copolymerization dynamics.

Findings

Simulation accurately predicts copolymer composition and triad fractions.

Copolymer sequence is affected by density fluctuations, not just feed composition.

Gradient copolymers can form under highly asymmetric feed conditions.

Abstract

In this work we used dissipative particle dynamics simulations to study the copolymerization process in the presence of spatial heterogeneities caused by incompatibility between polymerizing monomers. The polymer sequence details as well as the resulting system spatial structure in the case if phase segregation occurs during the chain growth can be predicted using the method. We performed the model verification with the available literature data on styrene-acrylic acid copolymerization in the bulk and a very good agreement between experimental and simulated data for both chain average composition and triad fractions was observed. Next, we studied the system properties for a model symmetric reaction process with the reactivity ratios r1 = r2 = 0.5 at different compositions and Flory-Huggins parameters \c{hi}. We found that the system average copolymer "composition-feed" curve does not depend on the \c{hi}-value, but there are significant changes in the copolymer sequences caused by the density fluctuations. Finally, we investigated the formation of gradient copolymers during living styrene-acrylic acid copolymerization at a highly asymmetrical feed composition.