Abstract
Nanoplastics are ubiquitously present in the aqueous medium carrying an increased risk due to their size and extended lifetime. Behaviour of environmentally relevant nanoplastics in the aqueous medium differs from engineered nanoplastics because of alterations in physicochemical properties through natural aging. Examination of these alterations and their implications for environmental behaviour need to be studied urgently. This study aims to partially fill the gap by conceptual analysis of changes in environmental stability of five types of environmentally relevant nanoplastic models upon aging. Aged samples were taken from aged surfaces of plastics collected from nature that were altered naturally whereas young samples are from their original commercial counterparts. Five types of plastics were selected within the scope including the most widely used PVC (Polyvinyl chloride), PP (PolyPropylene), PS (Polystyrene) and Nylon66, and PET (PolyEthylene Terephthalate) plastics. Characterization techniques for identification of changes physicochemical properties at nanoscopic and molecular scales included Small-Angle X-ray Scattering (SAXS), Wide-Angle X-ray Scattering (WAXS) and Fourier-Transform Infrared Spectroscopy (FT-IR). The analysis revealed several notable differences between original and aged samples in terms of structural arrangement, size, shape, crystallinity, chemical structure, and surface functionalization. The effect of aging was the most pronounced for PP polymer. PVC polymer, on the other hand, stayed structurally the most similar to its original form whilst fragmentated to a signifant degree. Conceptual examination of implications for environmental stability revealed that aged nanoplastics could be less mobile in the aquatic medium than their original counterparts. Similar studies need to be vigoruously pursued to further address relevant physicochemical changes to formulate eco-design decisions for plastics production.