Understanding PET Hydrolysis via Reactive Molecular Dynamics Simulation and Experimental Investigation.

Abstract

Polyethylene terephthalate (PET), a widely used polymer in packaging applications, has posed significant environmental challenges due to its resistance to environmental degradation. Chemical recycling via hydrolysis offers a circular solution by breaking PET down into its monomers, terephthalic acid and ethylene glycol, which can then be repolymerized into new PET. Despite its promise, the detailed pathways of PET hydrolysis─particularly the interplay between hydrolysis and thermal degradation─remain a topic of scientific debate. We combine reactive molecular dynamics (MD) simulations with experimental studies to elucidate key reaction pathways, intermediate species, and the temperature-dependent evolution of degradation products. Molecular dynamics simulations offer detailed insights into molecular motions and interactions that are often elusive in experimental setups, thus enhancing our understanding of the complex dynamics at play during PET decomposition. By systematically examining bond dissociation, intermediate species, and product formation at various temperatures, this study elucidates how hydrolysis and thermal degradation pathways evolve and interact. Furthermore, a severity index approach is employed to directly compare TPA yields from simulations with corresponding experimental data.