(649e) An Integrated Off-Lattice Kinetic Monte Carlo-Molecular Dynamics (KMC-MD) Framework for Modeling Polyvinyl Chloride Dehydrochlorination

Many plastic wastes, including polyvinyl chloride (PVC), contain considerable repositories of molecular value. These resources can potentially be accessed via depolymerization mechanisms; we aspire to perform these transformations using scalable techniques at mild conditions. In this study, a three-dimensional off-lattice kinetic Monte Carlo-molecular dynamics (KMC-MD) framework [Comp. Mat. Sci. 229, 112421 (2023)] is developed to investigate the dehydrochlorination/conjugation transformation of PVC in sodium hydroxide (NaOH) with atomistic resolutions at experimental timescales (10³ – 10⁶ s). Our framework enables a comprehensive examination of the competing reaction pathways and molecular-scale changes influenced by various solvents (acetone, ethylene glycol, triethylene glycol, tetrahydrofuran, and bio-derived solvents), as well as the influence of varying molecular weight distributions, concentrations, and temperatures. The algorithm simulates bond cleavage and formation during the KMC stage, whereas the MD stage is dedicated to the relaxation and thermalization of the PVC-NaOH-solvent system. The framework allows us to capture important configurational aspects (mixing, correlations, clustering, etc.) that are not accessible with a traditional microkinetic model. Our KMC-MD approach provides an exceptionally powerful tool for elucidating the complex reaction pathways, while simultaneously gaining insights into the molecular changes inherent to the depolymerization processes. Our technique allows us to perform direct experimental benchmarking at experimental timescales, paving the way for more effective upcycling of polymer wastes into valuable chemicals under mild conditions.