CAS-MNP: Origins of Secondary Nanoplastics and Mitigating Their Creation

CAS-MNP：二次纳米塑料的起源以及减少其产生

• 批准号: 2301348
• 负责人: Sanat Kumar
• 金额: $ 45.9万
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-06-01 至 2026-05-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2301348&HistoricalAwards=false
• 关键词: CAS; MNP; Origins; Secondary; Nanoplastics

NON-TECHNICAL SUMMARYIt is well-established that plastics degrade into micro and nanoplastics. These environmental pollutants have been found at the ocean surface (e.g., the Atlantic garbage patch) and now in the deep(est) ocean. While it is commonly believed that these materials can have deleterious effects on marine life, there is little understanding of how they form, their ultimate fate and most importantly how their occurrence can be mitigated. This research focuses on exactly this topic, in particular on semicrystalline polymers, which constitute over 70% of all plastics used currently. The work will combine experimental and theoretical tools to elucidate their degradation mechanisms when exposed to mechanical forces, water, air and/or UV light. The research will thus bring the well-established tools of polymer characterization towards delineating the critical mechanisms underpinning the formation of nanoplastics. Going beyond these aspects, this work anticipates mechanisms to mitigate the creation of these environmental pollutants -- finding and optimizing them is the second prong of the project. From a broader impacts viewpoint, design problems inspired by this research will be showcased in interdisciplinary programs such as the Engineering Design curriculum. The project will also facilitate undergraduate research opportunities and the training of a diverse cohort of junior and senior students at Columbia University. Understanding the routes to achieving decreased nanoplastic creation, and communicating this knowledge to the outside world, are the ultimate foci of the proposed work, which is thus deeply rooted in contributing to global sustainability.TECHNICAL SUMMARYIt is now well-established that plastics degrade into micro and nanoplastics. These environmental pollutants have been found on the ocean surface and in the deep ocean. This research focuses in particular on semicrystalline polymers, which constitute over 70% of all plastics used currently. When these polymers environmentally degrade in the aqueous milieu (i.e., in oceans) experiments consistently show that the chain segments in the amorphous phase break first, while the crystalline population actually grows. This work proposes that semicrystalline polymers form nanoplastics (100 nm and smaller) due to the preferential fragmentation of amorphous-phase tie chains which originally provided the connectivity between adjacent crystalline lamellae. By analogy to the phenomenon of environmental stress cracking, breaking of these molecular connectors leads to local material failure and the formation of nanoplastics. The proposed work will combine experimental and theoretical tools to elucidate the proposed degradation mechanisms of semicrystalline polymers of varying chemistries when exposed to mechanical stresses, water, O2 and/or UV light. Experimentally, it shall correlate nanoparticle creation with the initial polymer chemistry and morphology. How these variables affect the size, structure and properties of the resulting environmental pollutants are open questions that this research shall critically address. Parallel theoretical studies will predict the temporal evolution of the connectivity between adjacent crystals, the mechanical properties of the degrading plastics, and hence the size and number of nanoplastic objects that are temporally generated from a bulk polymer. The work will thus bring the well-established tools of polymer characterization towards delineating the critical physics underpinning the formation of nanoplastics. Going beyond these aspects, it is proposed that the use of copolymers or extruding the material can increase connectivity between crystals and thus serve as an efficient strategy to mitigate their creation. Design problems inspired by this research will be showcased in interdisciplinary programs such as the Engineering Design curriculum. The project will also facilitate undergraduate research opportunities and the training of a diverse cohort of junior and senior students at Columbia University. The PI will develop online learning modules related to the theme of this proposal for undergraduate and K-12 students. This PI has already run a three-day virtual workshop at Columbia University on the application of Machine Learning to materials science. Achieving the goal of decreasing nanoplastic creation is the ultimate focus of the proposed work, which is thus centrally focused on global sustainability..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.

非技术总结众所周知，塑料会降解成微米和纳米塑料。这些环境污染物已经在海洋表面发现（例如，大西洋垃圾带），现在在深海（东部）。虽然人们普遍认为，这些物质可能对海洋生物产生有害影响，但人们对它们如何形成、最终命运以及最重要的是如何减轻其发生的了解甚少。这项研究的重点正是这一主题，特别是半结晶聚合物，它占目前使用的所有塑料的70%以上。这项工作将结合联合收割机的实验和理论工具，以阐明其降解机制时，暴露于机械力，水，空气和/或紫外线。因此，这项研究将带来完善的聚合物表征工具，以描绘支撑纳米塑料形成的关键机制。超越这些方面，这项工作预计机制，以减轻这些环境污染物的创造-找到和优化它们是该项目的第二个方面。从更广泛的影响角度来看，本研究启发的设计问题将在工程设计课程等跨学科课程中展示。该项目还将促进本科生的研究机会，并在哥伦比亚大学培训一批不同的大三和大四学生。了解实现减少纳米塑料产生的途径，并将此知识传达给外界，是拟议工作的最终焦点，因此，这深深植根于为全球可持续发展做出贡献。技术总结现在已经确定，塑料降解为微米和纳米塑料。这些环境污染物存在于海洋表面和深海中。这项研究特别关注半结晶聚合物，它占目前使用的所有塑料的70%以上。当这些聚合物在水性环境中环境降解时（即，在海洋中）实验一致表明，非晶相中的链段首先断裂，而晶体群实际上在增长。这项工作提出，半结晶聚合物形成纳米塑料（100 nm及以下），由于优先破碎的非晶相连接链，最初提供相邻的结晶层之间的连接。通过类比环境应力开裂现象，这些分子连接器的断裂导致局部材料失效和纳米塑料的形成。拟议的工作将联合收割机实验和理论工具，以阐明不同的化学半结晶聚合物暴露于机械应力，水，O2和/或UV光时，提出的降解机制。在实验上，它将纳米粒子的产生与初始聚合物化学和形态相关联。这些变量如何影响所产生的环境污染物的大小，结构和性质是开放的问题，这项研究应严格解决。平行的理论研究将预测相邻晶体之间的连接性的时间演变，降解塑料的机械性能，以及从本体聚合物中暂时产生的纳米塑料物体的大小和数量。因此，这项工作将带来完善的聚合物表征工具，以描绘支撑纳米塑料形成的关键物理学。超越这些方面，提出使用共聚物或挤出材料可以增加晶体之间的连接性，从而作为减轻其产生的有效策略。受本研究启发的设计问题将在工程设计课程等跨学科课程中展示。该项目还将促进本科生的研究机会，并在哥伦比亚大学培训一批不同的大三和大四学生。PI将为本科生和K-12学生开发与本提案主题相关的在线学习模块。这个PI已经在哥伦比亚大学举办了一个为期三天的虚拟研讨会，主题是机器学习在材料科学中的应用。实现减少纳米塑料产生的目标是拟议工作的最终重点，因此重点关注全球可持续性。该奖项反映了NSF的法定使命，并被认为是值得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的支持。