Increasing Control Over Photoredox-Mediated Ring-Opening Metathesis Polymerization through Improved Mechanistic Understanding and Chain Transfer

凭借这一奖项，化学系的大分子、超分子和纳米化学项目资助了威斯康星大学麦迪逊分校化学系的Andrew J. Boydston教授研究无金属开环复分解聚合。这项研究能够合成用于车辆轻量化的精密塑料，以提高能源效率，抗弹道冲击成分，甚至3D打印。在这项研究中，进行了系统的研究，以了解这种反应是如何起作用的。还研究了优化聚合条件以制备具有补充或超过规格性能的塑料所需的因素。这项研究为本科生和研究生提供了合成聚合物化学方面的培训和教育，并提供了与陆军研究实验室合作研究的机会。外展活动的重点是在威斯康星大学麦迪逊分校为中学访客举办的讲习班，以及在教育者开放日（Educators Open House）上增加当地高中对STEM的兴趣。本文主要研究了乙烯醚引发的光氧化还原介导开环复分解聚合的机理。该技术为使用金属基引发剂生产具有挑战性的聚合物提供了途径。本文系统地研究了引发剂和光氧化还原催化剂之间的动态氧化还原偶联、可逆链端（去）活化的动力学和热力学、提高引发剂效率的方法、溶剂效应以及通过设计链转移剂控制分子量的实用方法。机理的见解是不同于任何其他目前报道的聚合过程，但从光氧化还原催化过程跨越小分子和聚合物合成。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。

With this award, the Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry is funding Professor Andrew J. Boydston of the Department of Chemistry at University of Wisconsin-Madison to investigate metal-free ring opening metathesis polymerization. This research enables the synthesis of precision plastics that are used in light-weighting of vehicles to improve energy efficiency, ballistic impact resistant compositions, and even 3D printing. In this research, systematic studies are performed to gain understanding of how this reaction works. Factors needed to optimize polymerization conditions to prepare plastics with properties that complement or exceed specifications are also investigated. This research provides training and education to undergraduate and graduate students in synthetic polymer chemistry as well collaborative research opportunities with the Army Research Laboratory. Outreach activities focus on workshops for middle school visitors at the University of Wisconsin-Madison, and at the Educators Open House to increase interest in STEM at local high schools. This research is focused on the mechanistic understanding of photoredox-mediated ring opening metathesis polymerization initiated by vinyl ethers. The technique provides access to classes of polymers that are challenging to produce using metal-based initiators. Key aspects of the envisioned mechanism, such as the dynamic redox couple between the initiator and photoredox catalyst, kinetics and thermodynamics of reversible chain end (de)activation, methods to improve initiator efficiency, solvent effects, and practical methods for molecular weight control via designer chain transfer agents are systematically investigated. Mechanistic insights are distinct from any other currently reported polymerization process, yet draw from photoredox catalyzed processes across small molecule and polymer synthesis.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.