Although it is well known that photochemical processing of plastics in the environment occurs, the environmental fate and impact of the plastics remain poorly understood. The reason for the lack of knowledge lies in the complexity of the sample environments and the limited number of techniques that are capable of measuring the molecular level details of the plastic materials at environmentally relevant interfaces, namely aqueous surfaces. The chemical moieties and structure of the plastic materials play a direct role in the adsorption of the molecules, such as organic pollutants, onto water surfaces and lead to different sunlight-driven mechanisms and photodegradation products. Without a clear understanding of the micro- and nanoplastics on aqueous environments, we risk increasing the burden of adverse health effects for animals and humans. Gaining molecular-level insights on the plastic polymers in-situ, i.e. on water, is crucial in understanding their behavior in the environment and in designing robust devices to remove or eliminate micro- and nanoplastics from water systems. In this work, advanced nonlinear spectroscopic techniques, such as vibrational sum frequency generation (SFG) spectroscopy, will be employed to determine the direct, molecular-level details of micro- and nanoplastics on environmentally relevant water surfaces. In this study we obtain molecular-level details of the photochemical processing of plastic micro- and nanoparticles in environmentally relevant conditions, i.e. on water, utilizing SFG spectroscopy and TEM. From these results, we determined if the plastic particles are clustering on aqueous interfaces, which can potentially change their behavior and absorption of sunlight.

Characterization of microplastics at the air/water interface with sum frequency generation spectroscopy

ACS Spring 2022

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