Modeling and Parameter Estimation of Acrylate Radical Solution Polymerization under High-Temperature Semibatch Operating Conditions

Understanding the kinetics of radical polymerization, especially under commercial high-temperature semibatch starved feed conditions, is a challenging task. This complexity is particularly pronounced for acrylate monomers, where the impact of secondary reactions on polymer properties and the polymerization rate becomes crucial. This study estimates kinetic coefficients for butyl acrylate (BA) homopolymerization, with a particular focus on the reaction network essential for predicting the macromonomer content. Incorporating chain-length-dependent termination kinetics into the model, the kinetic coefficients for backbiting, scission, termination, and transfer to solvent are estimated from available data. This refined model shows substantial improvements in predictions for not only macromonomer content but also critical variables such as weight-averaged molar masses, free monomer concentrations, and molar mass distributions. The same model and parameter estimation strategy is applied to better understand the significantly higher macromonomer and lower branched polymer content obtained when polymerizing isobornyl acrylate (iBoA) compared to BA. The estimated kinetic parameters, in particular the reduced rate coefficients for iBoA termination and for monomer addition to the midchain radical compared to those for BA, align with our understanding of these systems. This insight not only underscores the utility of precise parameter estimation in representing complex systems but also opens avenues for modeling a broader range of acrylate polymerization systems.