EAGER: CAS-MNP: Mapping the structure–property relationships of micro- and nanoplastics by in-situ nanoscopic imaging and simulation

非技术总结：这个合作项目结合了实验和模拟，以了解微塑料和纳米塑料，这些塑料是人眼不可见的微小塑料，已被证明普遍存在于食物链和环境中。因此，微米和纳米塑料对人类健康，生态系统和食品的不可预测的影响引起了人们的关注。例如，在淡水、咸水鱼和空气中发现了大量的微塑料，其浓度很高，形状各异，如碎片、泡沫和颗粒。 纳米塑料（小于100纳米）存在于水中，可能对人类健康特别令人担忧，因为它们的尺寸属于活细胞可以吸收的小颗粒。 使用基于统计平均值的传统工具包无法彻底检查微米和纳米塑料。 正是由于这些原因，本提案的研究目标是引入和使用液相透射电子显微镜（TEM）。 这将包含一个含有微塑料和纳米塑料的水的纳米水族馆，以记录它们在飞行中的运动，相互作用和聚集的电影，然后与理论相关联，为预测建模提供信息。要获得的基本理解与可持续性有关（例如，通过分离、收获和回收微塑料和纳米塑料来升级回收塑料），并且可以应用于其他系统，例如地质颗粒（砂、粘土）。除了跨学科的学生培训外，该项目的教育目标是为科学界提供以前无法获得的实验和建模数据，这些数据可能适用于其他地理区域的不同微塑料和纳米塑料。“水中的塑料”示范和讲座将为K-12学生和公众提供服务。 由三名共同PI组成的多元化团队还将积极鼓励女性和少数民族从事科学事业。技术摘要：这项实验性的模拟合作的研究目标是了解结构之间的基本关系（例如，该研究以前所未有的纳米分辨率对水中或分离膜存在下的微米和纳米塑料的组成、大小、形状（如纳米级、纳米级、纳米级）、胶体相互作用和聚集动力学进行了研究，从而实现了有效的策略，以最大限度地减少微米和纳米塑料在生态系统中的足迹。 这种塑料颗粒的一般不规则性和高分散性导致了在理解结构如何编码其性质和相行为（例如絮凝成大的聚集体或重的沉积物）的原理方面的知识缺口，这需要被弥合以促进其去除。该研究项目旨在通过聚合物合成和表征，纳米成像和胶体模拟的综合努力来填补这一空白。 通过使用低剂量液相透射电子显微镜（TEM）和扫描透射电子显微镜（STEM）的特殊显微镜套件，以真实的时间以纳米和毫秒分辨率对液体中的微米和纳米塑料进行成像，将获得新的理解。从（i）绘制模型和现实生活中的微米和纳米塑料的纳米级结构以及结构如何与单颗粒和成对水平上的胶体间相互作用势相关开始，该项目将继续（ii）阐明相互作用势如何影响微米和纳米塑料的聚集动力学。 它将最终遵循（iii）调查的实际相关的结构和相行为的环境变化的影响，特别是在分离膜的存在下，以了解基本的吸附和渗透动力学。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。

NON-TECHNICAL SUMMARY:This collaborative project combines experiments and simulation to understand micro- and nanoplastics, which are tiny pieces of plastics invisible to human eyes that have been shown to be ubiquitously present in the food chain and the environment. Micro- and nanoplatics thus pose major concerns on their unpredictable impact on human health, ecosystem, and food. For example, micro-plastics, the larger-sized population of the plastic pieces, are found in freshwaters, saltwater fish, and air, at high concentrations and in various shapes such as fragments, foam, and pellets. Nanoplastics (smaller than 100 nanometers are found in water and could be particularly worrisome for human health because their sizes fall into a regime of small grains that living cells could incorporate. Micro- and nanoplastics cannot be thoroughly examined using the conventional toolkits based on statistical averaging. It is for these reasons that the research goal of this proposal is to introduce and use liquid-phase transmission electron microscopy (TEM). This will enclose a nano-aquarium with water containing micro- and nanoplastics to record movies of their motion, interactions, and aggregation on the fly, and then be correlated with theory to inform predictive modeling. The fundamental understanding to be obtained is relevant to sustainability (e.g., upcycling of plastics by separating, harvesting, and recycling of micro- and nanoplastics) and may apply to other systems such as geological grains (sands, clays). In addition to interdisciplinary student training, the educational goal of this project is to provide previously inaccessible experimental and modeling data to the scientific community that could potentially be applied to different micro- and nanoplastics in other geographic regions. "Plastics in water" demonstrations and lectures will be developed for outreach to K-12 students and the general public. The diverse team of three co-PIs will also actively encourage women and minorities to pursue scientific careers.TECHNICAL SUMMARY:The research goal of this experimental‒simulation collaboration is to understand the fundamental relationships among the structure (e.g., composition, size, shape), colloidal interactions, and aggregation dynamics of micro- and nanoplastics in water or in the presence of separation membranes at unprecedented nanometer resolution, thereby enabling efficient strategies to minimize the footprint of micro- and nanoplastics in the ecosystem. The generic irregularity and high dispersity of such plastic particles has resulted in a knowledge gap in understanding the principles of how structure encodes their properties and phase behaviors (such as flocculation into large aggregates or heavy sediments) which needs to be bridged in order to facilitate their removal. This research project aims to fill this gap through an integrated effort of polymer synthesis and characterization, nanoimaging and colloid simulation. New understanding will be obtained by using the special microscopy suite of low-dose liquid-phase transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) to image the micro- and nanoplastics in liquids at nanometer and millisecond resolutions in real time. Starting with (i) mapping the nanoscale structures of model and real-life micro- and nanoplastics and how the structures relate with the intercolloidal interaction potential on the single particle and pairwise level, this project will continue with (ii) elucidating how the interaction potential affects the aggregation dynamics of micro- and nanoplastics. It will ultimately be followed by (iii) investigating the effects of environmental variations of practical relevance on structure and phase behaviors, especially in the presence of separation membranes so as to understand the fundamental adsorption and penetration dynamics..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.