Modeling free radical polymerization using dissipative particle dynamics

Understanding the details of free radical polymerization (FRP) in multi-component mixtures and solutions is of great importance for the synthesis of polymeric functional materials. Using the framework of dissipative particle dynamics (DPD), we develop a new computational approach to model FRP that couples the reaction kinetics for the polymerization processes to the dynamics of the complex fluid. We specifically consider two mechanisms of chain termination: disproportionation and combination. We analyze the effects of initiation, propagation, and termination on the polymerization kinetics in three-dimensional bulk polymerization by varying the corresponding reaction probabilities. Our model not only allows us to capture the interplay between hydrodynamics and reaction kinetics, but also provides an effective means to model polymerization in the presence of solid inclusions. We demonstrate the latter feature by simulating the formation of polymer-clay nanocomposite gels by FRP in solution in the absence of organic cross-linking agents, where the exfoliated clay particles serve as multi-functional cross-linkers for the polymer network. We observe that increasing the volume fraction of clay particles can lead to an increase in the number of inter-particle cross-linking chains, which could improve the mechanical properties of the material. Our findings provide insight into the polymerization kinetics of the FRP, as well as potential guidelines for tailoring experimental conditions to achieve the desired polymerization products. (C) 2015 Elsevier Ltd. All rights reserved.