Polyethylene plastic degradation: The dual pathways from macroplastics to nanoplastics

Plastics degrade in the environment through complex physical and chemical processes. Here, we demonstrate that nanoplastics (NPs) can be directly released from macroplastics, and not solely generated via intermediate microplastic (MP) fragmentation, thereby challenging the conventional stepwise degradation paradigm. Using a multi-technique approach combining scanning electron microscopy (SEM), µ-Raman spectroscopy, Chemical mapping (sSNOM), and optical infrared spectroscopy (OPTIR), we show that chain scission and oxidation drive structural embrittlement, promoting direct NP detachment from macroplastic surfaces. These findings emphasize the urgent need to reconsider plastic pollution mitigation strategies, moving beyond a sole focus on MPs and NPs to include macroplastics as a primary and active source of nanoscale pollutants. Expanding regulatory frameworks to address plastic degradation across all size scales, from macro to nano, is essential to limit long-term environmental and ecological risks.