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

点击翻译按钮获取中文摘要

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.