An integrated off-lattice kinetic Monte Carlo (KMC)-molecular dynamics (MD) framework for modeling polyvinyl chloride dehydrochlorination

Abstract

In this study, a three-dimensional off-lattice kinetic Monte Carlo-Molecular Dynamics (KMC-MD) simulation framework [Comp. Mat. Sci. 229, 112421 (2023)] is used to investigate the dehydrochlorination/conjugation transformation of polyvinyl chloride (PVC) in sodium hydroxide (NaOH) with atomistic resolutions at experimental timescales (10³ – 10⁶ s). Our framework enables an 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, NaOH concentrations, and temperatures. The algorithm simulates bond cleavage and formation during the KMC stages, 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, and it potentially allows us to perform benchmarking at experimental timescales