Beyond the Bulk: Mechanistic Insights into Nanoplastic Release and the Environmental Fate of Polymers

Abstract: 
The linear economy of synthetic polymers systematically results in the vast majority of the materials being relegated to landfill accumulation and environmental leakages. With global plastic production projected to triple by mid-century, understanding their environmental fate is paramount. While bulk plastics are visibly persistent, their environmental degradation generates a complex spectrum of highly mobile products, including micro- and nanoplastics (MP/NPs), dissolved carbon, and CO2. Among these, NPs are of particular concern because they readily infiltrate biological tissues and yet remain notoriously difficult to quantify and characterize. Furthermore, because accurate lifetime estimations rely on tracking the mass of full spectrum products, the current scarcity of data across all degradation pathways severely limits these calculations. Such foundational estimations are essential for conducting robust risk and life cycle assessments, ultimately informing science-based policymaking on how we should produce, use, and discard plastics. 
In this talk, I will highlight our recent efforts to bridge these knowledge gaps by harmonizing plastic degradation data and advancing the mechanistic understanding of NP release. First, utilizing our comprehensive degradation database harmonized from 300 peer-review articles, I will present our population balance modeling of polystyrene degradation to predict its product mass distribution and MP/NP persistence across extended timescales. Second, I will explore mechanical degradation—a dominant yet understudied mechanism for NP release in terrestrial and coastal environments. Using novel lateral force microscopy-based nanoscratch methods and macroscopic abrasion experiments, I will discuss new release behavior of polyethylene at the single-asperity and sand grain level. I will reveal how factors such as photo-oxidation, normal force, and additive formulation could govern NP release. Finally, our quantitative nanomechanical mapping demonstrates that NPs possess distinct material properties from bulk plastics, challenging the current toxicity studies that largely rely on ideal model nanoplastics. Ultimately, this work advances our understanding and prediction for MP/NP exposure and effects, enabling the early design, selection, and management of polymer materials for responsible environmental outcomes.