Accelerated Oxidative Degradation of Polystyrene: Correlating UV Aging with Reactive Molecular Dynamics.

This study investigates the oxidative degradation of polystyrene (PS) through a synergistic framework integrating UV-C-accelerated aging with Reactive Molecular Dynamics (ReaxFF) simulations. To bridge the gap between experimental and computational timescales, shock compression was employed in the simulations as an accelerator of degradation reactions. ATR-FTIR spectroscopy revealed the emergence of carbonyl (1717 cm-1) and peroxyester (1760 cm-1) bands, alongside dominant ether-type oxygen bridges (1260, 1209 cm-1). These experimental data, particularly the depletion of native aromatic bands (1492, 1451 cm-1), provide direct empirical validation of the ring-ring cross-linking and radical-mediated oxidation pathways predicted by the ReaxFF model. The results demonstrate that theory-guided diagnostics offer a robust mechanism for understanding the atomic-level restructuring of the polymer matrix. Significantly, the formation of hydrophilic oxygenated groups increases the bioavailability and environmental hazard potential of fragmented PS microplastics, providing critical insights into their long-term ecological fate.