CAS: Development of a General System for Upcycling Polyolefins through C-H Diversification

CAS：开发通过 C-H 多样化升级循环聚烯烃的通用系统

• 批准号: 2304548
• 负责人: Erik Alexanian
• 金额: $ 65.28万
• 依托单位: University of North Carolina at Chapel Hill
• 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: 2023-07-01 至 2027-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2304548&HistoricalAwards=false
• 关键词: CAS; Development; General; System; Upcycling

With the support of the Macromolecular, Supramolecular and Nanochemistry program in the Division of Chemistry, Professor Erik J. Alexanian of the University of North Carolina at Chapel Hill is developing chemical reagents for upcycling polyolefins through C-H bond diversification. Polyolefins are a family of polyethylene and polypropylene thermoplastics that are non-toxic, durable, heat resistant, and capable of withstanding most kinds of chemical corrosion. They are produced mainly from oil and natural gas by polymerization of ethylene and propylene, respectively. They are the most widely utilized plastics in the world, with variations of each used in numerous products, ranging from drinking straws to sophisticated laboratory instruments. By chemical structure, they are long chain hydrocarbon macromolecules consisting exclusively of C-C and C-H bonds. This project will address sustainability and recyclability of polyolefins by developing reagents that enable the selective C–H diversification of polyolefin mixtures. Essentially, through such diversification, C-H groups along the main polymer backbone will be replaced with other valuable and diverse chemical functional groups. In the long run, the approaches associated with this research have the potential to provide valuable methods for polyolefin upcycling, where post-consumer plastic waste will serve as an abundant feedstock for the synthesis of plastics with a greater economic value and a smaller environmental footprint. The UNC Chemical Education Outreach group, established by Prof. Alexanian, will involve graduate students teaching at a range of local schools, especially those with high ethnic and socioeconomic diversity. The topics will aim to draw important connections between chemistry and its impact on our lives. Additionally, “Polymer Upcycling” outreach activities through the UNC Morehead Planetarium and Science Center’s Launch Lab Makerspace will engage local K-12 learners and the public on the challenges and opportunities for building more sustainable polymer lifecycles.This project will focus on the development of novel classes of N-functionalized amides and radical traps that enable the selective C–H diversification of polyolefin mixtures and impart a range of new polymer properties. In the first objective, new classes of O-alkenylhydroxamate and N-dithiocarbonyl reagents will be developed to increase the practicality of the platform and enable scalable, site-selective polyolefin C–H diversification. The second objective will focus on utilizing these structurally optimized reagents for the selective functionalization of polyethylene/polypropylene mixtures, and mixtures with other polymers commonly found in plastic waste streams. Finally, the last objective will identify a diverse set of thiosulfonates as radical trapping reagents to introduce a range of functionality onto polyolefins in a selective manner. Direct polyolefin C–H heteroarylation will also be pursued. The tools developed with this research have the potential to enable the upcycling of polyolefins to a range of new polymers under conditions relevant to the processing of mixed plastic waste.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.

在化学系大分子、超分子和纳米化学项目的支持下，北卡罗来纳大学教堂山分校的埃里克·J·亚历克萨尼安教授正在开发通过C-H键多样化使聚烯烃循环升级的化学试剂。聚烯烃是一系列聚乙烯和聚丙烯热塑性塑料，无毒、耐用、耐热，能够承受大多数类型的化学腐蚀。它们主要由石油和天然气分别通过乙烯和丙烯聚合生产。它们是世界上使用最广泛的塑料，每种塑料的变体都用于许多产品，从吸管到复杂的实验室仪器。从化学结构上看，它们是完全由C-C键和C-H键组成的长链烃大分子。该项目将通过开发能够选择性地使聚烯烃混合物的C-H多样化的试剂来解决聚烯烃的可持续性和可回收性。基本上，通过这种多样化，沿着主要聚合物主干的C-H基团将被其他有价值的和多样化的化学官能团所取代。从长远来看，与这项研究相关的方法有可能为聚烯烃的循环利用提供有价值的方法，消费后的塑料废物将作为合成塑料的丰富原料，具有更大的经济价值和更小的环境足迹。北卡罗来纳大学化学教育外展小组由阿列克桑尼亚教授建立，将有研究生在当地一系列学校任教，特别是那些种族和社会经济多样性较高的学校。这些主题将旨在找出化学及其对我们生活的影响之间的重要联系。此外，通过北卡罗来纳大学莫尔黑德天文馆和科学中心的启动实验室Makerspace开展的“聚合物升级”推广活动将使当地的K-12学习者和公众了解建立更可持续的聚合物生命周期的挑战和机会。该项目将专注于开发新型的N-官能化酰胺和自由基陷阱，使聚烯烃混合物能够选择性地实现C-H多样化，并传授一系列新的聚合物性质。在第一个目标中，将开发新类别的O-烯基羟基甲酸酯和N-二硫代羰基试剂，以增加平台的实用性，并使可扩展的、位置选择性的聚烯烃C-H多样化。第二个目标将侧重于利用这些结构优化的试剂对聚乙烯/聚丙烯混合物以及与塑料废料中常见的其他聚合物的混合物进行选择性官能化。最后，最后一个目标将确定一组不同的硫代磺酸盐作为自由基捕捉剂，以选择性的方式在聚烯烃上引入一系列官能团。还将进行直接聚烯烃C-H异芳基化反应。通过这项研究开发的工具具有在与处理混合塑料废物相关的条件下将聚烯烃升级为一系列新聚合物的潜力。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。