RAFT Step-Growth Polymerization

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With the support of the Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry, Dr. Wei You of the University of North Carolina at Chapel Hill will explore a new polymerization method that will allow the facile construction of polymers with embedded functionality in their backbone through a generally applicable process. The success of this project will lead to a simple and facile methodology of designing functional macromolecules with precisely defined architectures, unlocking new opportunities for broad applications. Education, collaboration, and outreach are integral aspects of this project. All trainees involved in this project will become proficient in organic and polymer syntheses, and a variety of characterizations. For the past fifteen years, the You research group has successfully recruited students of underrepresented groups into research, and has developed and supervised laboratory exercises for middle and high-school students through various educational programs at UNC. In polymer chemistry, free radical-centered polymerizations are almost synonymous to the chain-growth mechanism. As one of the most important controlled free-radical polymerizations, Reversible-Addition Fragmentation chain Transfer (RAFT) polymerization has been widely adopted due to its simplicity and versatility of controlling the degree of polymerization (DP) of free radical polymers, enabled by the addition of chain transfer agents (CTAs) known as the RAFT agents. However, inherent to the chain-growth nature of conventional RAFT, the backbone of such polymers usually consists of only inert carbon atoms, while desired functionality is introduced through the pendent groups. This contrasts to step-growth polymerization that typically offers multifunctional heteroatom backbones, which can easily allow the introduction of functionalities into the backbone. The You group recently discovered a unique approach to achieve RAFT step-growth polymerization. Building upon significant results, this project aims to further explore this exciting new polymerization, with two objectives: (1) to establish the general principle and mechanism of RAFT step-growth polymerization and expand the expand the chemistry with other RAFT agents and monomer family; and (2) to understand the impact of reaction conditions on the RAFT step-growth polymerization. If successful, this project will construct important steps to achieve the long-term goal of establishing a new polymerization methodology, RAFT step-growth polymerization, for broader use to enable synthesis of new materials that were previously unachievable.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.