Extracting Depolymerization Rates of Vinyl Polymers with Thermal Triggers via Analytical Models

Abstract

Several depolymerization strategies have emerged as end-of-life options for polymers, such as poly(methyl methacrylate) (PMMA), reflecting a broad design space that spans chemistries, polymer architectures, stimuli, and reaction conditions. This diversity creates a need for predictive and adaptable models that link depolymerization mechanisms to kinetics across systems. Herein, we report an analytical framework for trigger-activated, radical-unzipping depolymerizations that extracts activation, depropagation, and termination rates from thermogravimetric analysis and predicts molar mass distributions during deconstruction. The model was validated using the thermally induced depolymerization of PMMA derivatives containing either chain-end, central, or distributed trigger groups. Depropagation rates were architecturally independent, and termination behavior exhibited signatures of diffusion-limited kinetics. Furthermore, three kinetic regimes of depolymerization behavior were identified from a dimensionless parameter analysis, which enabled simplified analytical treatment. This framework provides a predictive tool for interpreting depolymerization behavior and guiding the design of circular-by-design polymers, along with scale-up of deconstruction unit operations.