Synthetic polymers protect people from extreme weather, enable prolonged food storage, and help cure disease. While these versatile materials have enabled population expansion and globalization, a new need has arisen: the capability to make high-volume plastics with the functional properties needed for next-generation challenges while simultaneously incorporating sustainability into the material design. To tackle this challenge, the research team of Professor Leibfarth of the University of North Carolina at Chapel Hill develops synthetic methods to enable the precise control of the polymer structure and the use of building blocks from biorenewable resources. Accomplishing the goals enumerated in this project will make significant contributions to the scientific community and the broader population, both in contributing new fundamental knowledge and in introducing novel material solutions for contemporary societal challenges. This fundamental research in polymer chemistry couples with an education program that develops inquiry-guided scientific activities to educate and bring the joy of discovery to children undergoing long-term hospitalization. This underserved group ranges in age from K-12. These patients/students not get the same interactive scientific experiences as their peers. Professor Leibfarth and his group create structured modules that introduce inpatients to contemporary aspects of polymer science through an interactive mix of hands-on and multimedia activities. Six scalable modules that can be implemented across a range of hospital settings are available at UNC Children's Hospital and will impact 50+ patients per year. Detailed instructions and multimedia resources are publicly available online. In addition, graduate students receive formal training in interacting with diverse patient populations and communicating science with the public, building a sustainable group culture that values the importance of diversity and outreach.
The tacticity (stereochemistry) of vinyl polymers is intimately linked to their resultant material properties. Despite the well-developed stereoselective methods for the polymerization of propylene and other nonpolar alpha-olefins, stereoselective polymerization of polar vinyl monomers has proven more challenging. The Leibfarth group has recently developed catalysts that systematically bias the chain-end stereochemical environment during cationic polymerization and enable the synthesis of isotactic poly(vinylether)s with unprecedented isotacticities. With the support from the Macromolecular, Supramolecular, and Nanochemistry Program of the NSF Division of Chemistry, the Leibfarth group seeks to gain a deeper fundamental understanding of this polymerization method. The first objective of this project is to examine the influence of monomer sterics and chirality on reaction performance in order to understand the interactions that enable the catalyst to direct stereoselective polymerization of these monomers. The second objective seeks to expand the diversity of chemical functionality amenable to stereoselective polymerization and explore strategies (e.g., continuous flow methods) to control the molecular weight and molecular weight distribution of the polymers. The third objective leverages the fundamental understanding gained throughout the project to develop a new class of biorenewable vinyl ether monomers that are amenable to stereoselective polymerization.
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.
