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.

非技术摘要是良好的塑料降解为微塑料和纳米塑料的。这些环境污染物已在海面（例如大西洋垃圾斑块）和现在的深海发现。尽管通常认为这些材料会对海洋生物产生有害影响，但对它们的形成，最终命运以及最重要的是如何减轻其发生的方式几乎没有理解。这项研究的重点是该主题，尤其是半晶体聚合物，该聚合物占目前使用的所有塑料的70％以上。这项工作将结合实验和理论工具，以阐明其在机械力，水，空气和/或紫外线的降解机制时阐明其降解机制。因此，该研究将带来良好的聚合物表征工具，以描述纳米塑料形成的关键机制。超越了这些方面，这项工作预测了减轻这些环境污染物的创建的机制 - 寻找和优化它们是该项目的第二个插脚。从更广泛的影响观点来看，受这项研究启发的设计问题将在跨学科计划（例如工程设计课程）中展示。该项目还将促进本科研究机会，并培训哥伦比亚大学的大三和高年级学生。了解纳米塑性创造的减少的途径，并将这些知识传达给外界，是拟议工作的最终焦点，因此，这深深植根于为全球可持续性做出贡献。技术总结现在已经良好地塑造了塑料中的微型和纳米塑料。这些环境污染物已在海面和深海中发现。这项研究特别关注的是半晶聚合物，该聚合物占目前使用的所有塑料的70％以上。当这些聚合物在水环（即在海洋中）中环境降解时，实验始终表明，无定形相中的链节段首先，而晶体种群实际上会增长。这项工作提出，由于优先片段化的非物相扎带链，半晶体聚合物形成纳米塑料（100 nm及较小），该链的优先碎片，最初提供了相邻晶体层之间的连通性。通过类似于环境应力破裂的现象，这些分子连接器的破坏会导致局部材料衰竭和纳米塑料的形成。提出的工作将结合实验和理论工具，以阐明在暴露于机械应力，水，O2和/或紫外光时，不同化学分子的半晶体聚合物提出的降解机制。在实验上，它应将纳米颗粒的产生与初始聚合物化学和形态相关。这些变量如何影响所得环境污染物的大小，结构和特性是本研究应批判性解决的空旷问题。平行的理论研究将预测相邻晶体之间的连通性的时间演化，降解塑料的机械性能，以及从散装聚合物时间产生的纳米塑性对象的大小和数量。因此，这项工作将带来良好的聚合物表征工具，以描述纳米塑料形成的关键物理学。超越了这些方面，建议使用共聚物或挤出材料可以增加晶体之间的连通性，从而作为减轻其创造的有效策略。受这项研究启发的设计问题将在跨学科计划（例如工程设计课程）中展示。该项目还将促进本科研究机会，并培训哥伦比亚大学的大三和高年级学生。 PI将开发与本科和K-12学生的建议主题相关的在线学习模块。该PI已经在哥伦比亚大学举办了为期三天的虚拟研讨会，旨在将机器学习应用于材料科学。实现减少纳米塑性创造的目标是拟议工作的最终重点，因此，该工作集中于全球可持续性。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识分子优点和更广泛影响的审查标准来评估的支持。