Exploring Some Kinetic Aspects of the Free Radical Polymerization of PDMS-MA

Abstract

This study conducts a theoretical exploration of the free radical polymerization of polydimethylsiloxane homopolymers with a methyl methacrylate end group (PDMS-MA). To achieve this, a methodology is developed to model and simulate experimental data previously reported by one of the authors. The model incorporates a typical chain reaction mechanism, encompassing initiation, propagation, chain transfer, and termination stages. The resulting ordinary differential equations from this mechanistic approach are numerically integrated over time. Employing a semi-heuristic procedure, the study derives estimated values for the diffusive steps of termination (ktd) and propagation (kpd). Methodological accuracy is assessed through a comparison of the mathematical model results and experimental data. This evaluation includes the estimation of conversion and the average molecular weight (both number (Mn) and weight (Mw)) at three distinct monomer concentrations, considering a 4.78% mol initiator-to-monomer ratio. The theoretical results obtained from this study contribute to a better understanding of the evolution of diffusion coefficients. These coefficients play a crucial role in influencing the behavior of the studied reactions, particularly in relation to the absence of the autoacceleration effect in these reactions.