Title: User-Friendly Ionic Polymerizations
Abstract:
Ionic polymerizations are a powerful platform for the synthesis of well-defined polymeric materials; however, their widespread adoption is limited by stringent reaction conditions, including sensitivity to air and moisture, the use of highly reactive reagents, and the need for low-temperature operation. Developing more practical, user-friendly approaches to ionic polymerizations remains a significant challenge. In this presentation, we present two complementary strategies that expand the operational scope, safety, and accessibility of ionic polymerizations. First, we developed a reversible deactivation cationic polymerization of vinyl ethers that can be run open to the air without monomer purification. This new method enables the synthesis of new sustainable thermoplastics and thermosets from renewable resources. Second, we demonstrate a CO₂-mediated anionic polymerization in which reversible addition of CO₂ to the enolate chain end tempers its reactivity, enabling controlled polymerization at elevated temperatures using an easily handled solid initiator. This approach provides excellent molecular weight control and narrow molar mass distributions while improving scalability and operational simplicity. Additionally, we introduce an anionic reversible addition–fragmentation chain-transfer (RAFT) polymerization that reduces the required loading of an organolithium initiator. Using a chain-transfer agent, reversible aldol reactions with propagating enolate chain ends enable dynamic chain transfer and control over polymer growth. This method affords well-defined polymers with isolable aldehyde chain ends that can be reinitiated to form block copolymers.
Bio:
Brett P. Fors was born in Montana and carried out his undergraduate studies in chemistry at Montana State University (2006). He went on to do his Ph.D. (2011) at the Massachusetts Institute of Technology with Professor Stephen L. Buchwald. After his doctoral studies, he became an Elings Fellow at the University of California, Santa Barbara working with Professor Craig J. Hawker. In of 2014 he joined the faculty at Cornell University and is currently the Frank and Robert Laughlin Professor in the Department of Chemistry and Chemical Biology. His group’s research focuses on the development and application of new synthetic methods for polymer science.