Probing Primary and Mechanically Degraded Nanoplastic Particles via Atomic Force Microscopy

The presence of Nanoplastic particles (NPs) is very common in the environment and the effect of such NPs on ecological systems is still far from being clearly understood. The identification of NPs both in terms of size, shape, and its adhesion property is still challenging due to its minute dimension. In this paper, the commercially available NPs are probed by conventional atomic force microscopy (AFM). The commercially available pyramidal tips are used to assess the size and shape of NPs and its adhesion property. In addition to this, the primary NPs are mechanically treated with silica particles to study the size, shape and adhesion of degraded secondary NPs. Three different NPs namely melamine formaldehyde resin (MF), polystyrene (PS), poly methyl methacrylate (PMMA) are considered for the study. We observe the change of size, shape, and roughness of the NPs after mechanical treatment. The adhesion energy is calculated from the pull-off force mapping on each NPs. The Tabor's parameter is estimated to explain and select the suitable contact mechanical model for adhesion energy measurement. The Young's moduli of primary and secondary NPs are also measured from the force-distance curve.