CAS-MNP: Molecular Probing Surface Reactivity Dynamics of Native versus Photo-Oxidized Microplastics and Nanoplastics in Environmental Aqueous Media

该奖项由化学学部的环境化学科学项目和化学、生物、环境和运输系统学部的环境工程项目颁发，旨在支持西北大学的Ludmilla Aristilde博士对微塑料和纳米塑料的研究，这些塑料是海洋、湖泊和河流中塑料环境命运的重要最终产品。据报道，这些残留的塑料材料可以在不同的环境水介质中捕获各种有机污染物。通过光氧化，由于暴露在阳光下的活性颗粒的存在，碎片塑料表面可以发展不同的化学特性。这个项目的重点是揭示这些不同的化学特性及其在促进污染物吸附在聚乙烯、聚丙烯和聚苯乙烯塑料类型中的作用。外联和教育的广泛影响旨在将本科生纳入研究活动，促进高中生的参与，提高公众对塑料废物环境命运的认识。本项目应用了几项光谱研究，结合分子模拟，揭示了微塑料和纳米塑料的天然与光氧化结构的表面化学和化学动力学，以及它们与特定污染物类别的选择性相互作用。塑料的吸附剂作用依赖于水-塑料界面上有利的纳米级到分子级的相互作用。然而，对这些相互作用的机理理解，特别是在天然塑料和光氧化塑料不同表面化学的背景下，仍然是一个关键的知识空白。在水-塑性界面环境中进行原子尺度的实验探测，以阐明不同介质组成中分子反应性的变化，代表淡水与不同化学成分的海水。这些实验结果与溶剂化系统的分子建模模拟相结合，以确定控制污染物对天然纳米塑料表面和光老化纳米塑料表面有利或不利亲和力的结构因素。该研究有望为微塑料和纳米塑料表面的结构和化学变化如何影响水-塑料界面上不同类别有机污染物的捕获动力学提供新的机制见解。这些发现对于开发微塑料和纳米塑料在淡水和海水中有机污染物命运中的作用的预测模型将是重要的。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This award from the Environmental Chemical Sciences Program in the Division of Chemistry and the Environmental Engineering Program in the Division of Chemical, Biological, Environmental, and Transport Systems is supporting Dr. Ludmilla Aristilde at Northwestern University for research on microplastics and nanoplastics, which are important end-products in the environmental fate of plastics in oceans, lakes, and rivers. These remnant plastic materials are reported to trap various organic contaminants in different environmental aqueous media. Through photo-oxidation due to exposure to sunlight in the presence of reactive particles, the fragmented plastic surfaces can develop different chemical characteristics. This project focuses on unraveling these different chemical characteristics and their role in facilitating contaminant adsorption on the polyethylene, polypropylene, and polystyrene plastic types. The outreach and educational broader impacts aim to implement undergraduate students into the research activities, foster the engagement of high school students, and increase public literacy regarding the environmental fates of plastic wastes.This project applies several spectroscopic investigations coupled with molecular simulations to unravel the surface chemistry and chemical dynamics at native versus photo-oxidized structures of microplastics and nanoplastics in relation to their selective interactions with specific contaminant classes. The adsorbent role of plastics relies on favorable nanoscale to molecular-scale interactions at the water-plastic interfaces. However, a mechanistic understanding of these interactions, especially within the context of the different surface chemistries of native versus photo-oxidized plastics, remains a critical knowledge gap. Atomistic-scale experimental probing at the water-plastic interfacial environments is performed to elucidate changes in molecular reactivity in different media composition representing freshwater versus seawater of varying chemistries. These experimental results are coupled with molecular modeling simulations of solvated systems to determine the structural factors that control favorable versus unfavorable contaminant affinity to native versus photo-aged nanoplastic surfaces. The research is expected to provide new mechanistic insights on how structural and chemical changes at the microplastic and nanoplastic surfaces influence the trapping dynamics of organic contaminants of different classes at the water-plastic interface. These findings will be important in the quest to develop predictive models for the role of microplastics and nanoplastics in the fate of organic contaminants in freshwater and marine waters.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.