Quantitative Insights into Poly(acrylate) Synthesis: Comparing Model Predictions with Experimental Data for High-Temperature Semi-Batch Solution Radical Polymerization

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Esmaeilzadeh, Mahsa
Radical polymerization , Poly(acrylate) synthesis , Modeling, parameter estimation
Acrylic resins are essential components in many automotive coatings and adhesives, valued for their superior chemical and mechanical properties. Understanding the kinetics of radical polymerization, especially under commercial high-temperature semi-batch starved feed conditions, is a challenging task. This complexity is particularly pronounced for acrylate monomers like butyl acrylate (BA), where the impact of secondary reactions on polymer properties and the polymerization rate becomes crucial. By selecting appropriate operating conditions to maximize macromonomer content, it is possible to chemically modify these resins to produce specialized graft or comb copolymer architectures, thereby enhancing the value of acrylate resins. This study aims to refine the kinetic parameters for modeling acrylate homopolymerization, with a particular focus on the reaction network essential for predicting macromonomer content. Using PREDICI software, we have estimated a comprehensive set of kinetic parameters, including backbiting, scission, termination, and transfer to solvent. Significantly, we incorporated chain length-dependent termination kinetics into the model, enhancing its predictive accuracy. This refined model shows substantial improvements in predictions for not only macromonomer content but also for critical variables such as weight-average molar masses, free monomer concentrations, and molar mass distributions. The modified model was further validated by testing predictions for BA/butyl methacrylate (BMA) and hydroxyethyl acrylate (HEA)/BMA copolymerization systems, demonstrating a good correlation with experimental data. The final application of the model is to the polymerization of isobornyl acrylate (iBoA), an acrylate of current interest due to a significantly higher macromonomer content compared to BA. The estimated kinetic parameters for iBoA homopolymerization, in particular the reduced rate coefficients for termination and for monomer addition to the mid-chain 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.
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