Design of Lewis Acid Tethered Chain-End Capping Agents for Stereocontrolled Radical Polymerization

Yale University, New Haven CT

Investigators

Abstract

With the support of the Macromolecular, Supramolecular, and Nanochemistry (MSN) Program in the Division of Chemistry, Dr. Mingjiang Zhong of Yale University aims to develop synthetic approaches to the production of stereoregular polymers from a broader scope of monomers compared to traditional polymerization methods. These methods are expected to demonstrate high compatibility with a variety of functionalities and environmentally friendly reaction conditions. This project strives to develop a versatile platform for the preparation of polymeric materials with readily diversified properties without altering their chemical composition. Educational activities associated with this project will include participation in an undergraduate research program aimed at promoting the involvement of students from underrepresented groups (URGs) in the field of chemistry, outreach to local high school students from URGs, and hosting high school research interns from URGs. The stereochemical regularity of carbons along polymer backbones plays a significant role in determining the physical properties of polymers, including their mechanical strength, dielectric constant, thermal behaviors, and optical transparency. This project aims to develop innovative catalytic systems to achieve stereocontrolled radical polymerization. By designing reversible radical deactivators covalently linked with metallic Lewis acids, the study seeks to precisely control interactions between tethered Lewis acids and polymeric radical chain ends, enabling a stereocontrolled radical propagation process. The primary focus will be on systems utilizing cobalt–porphyrin complexes as deactivators. Guided by mechanistic and kinetic insights, modifications to the porphyrin ligands, linkers between the two metallic centers, and the ligands that chelate rare earth metals are expected to facilitate the development of stereocontrolled radical polymerization with expanded substrate scope, reduced catalyst loading, improved control and livingness, and compatibility with aqueous reaction media. The knowledge gained is expected to further contribute to the development of metal-free stereocontrolled systems employing chiral Lewis acids and organocatalytic reversible-deactivation chemistry. This work not only aims to address the inherent challenges associated with radical polymerizations but also to shed light on small-molecule reactions involving sp2-hybridized, non-interactive radical species. 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.