Cryogenic milling of consumer plastics for high-throughput characterization of polydisperse, amorphous microplastics

Microplastics - defined as tiny polymer fragments less than 5 mm in size - pose a clear threat to a wide range of small organisms through ingestion, leading to starvation. In addition, there are many reports of their occurrence both in remote geographical areas and in the human body. Small and made of mostly inert materials, they pose a significant analytical challenge. While primary microplastics i.e., those manufactured intentionally, have defined characteristics, secondary microplastics resulting from the degradation of larger plastic debris are much less understood. Cryogenic milling has emerged as one of the best ways to generate realistic samples with potential for use as references in studies. Here, we use this technique to generate and study the shapes and properties of a wide range of consumer plastics, providing an overview of optical and analytical properties.