Hydrazine-Catalyzed Ring-Opening Metathesis Polymerization

With support from the Macromolecular, Supramolecular, and Nanochemistry Program in the Division of Chemistry, Professors Tristan Lambert and Brett Fors of Cornell University will develop a metal-free variant of a powerful polymerization reaction known as ring-opening metathesis polymerization (ROMP). Materials produced by ROMP are critically important for a range of applications; however, current ROMP methods rely exclusively on metal-based catalysts that are often toxic, costly, and limited in availability. As a result, ROMP materials typically contain residual metal impurities, requiring difficult and labor-intensive purification procedures—especially problematic for applications such as medical implants, drug delivery systems, and microelectronics, where metal contamination is unacceptable. The new ROMP methodology developed by Lambert and Fors will employ an organic catalyst composed solely of carbon, nitrogen, and hydrogen, making it inexpensive, non-toxic, and sustainable. The broader impact of this work includes the creation of a metal-free platform for preparing ROMP polymers, thereby enabling their use in sensitive and high-value applications, and training graduate students in the areas of polymer chemistry and catalyst development. More technically, this program aims to develop and apply 1,2-dialkylhydrazines as organocatalysts for the ROMP of a wide range of cyclic olefins. A central goal is to elucidate the structural features of these hydrazine catalysts that govern their reactivity and selectivity, and to use these insights to design more efficient and broadly applicable catalysts. The project will integrate empirical and computational approaches to achieve a detailed fundamental mechanistic understanding of key steps in the catalytic cycle, including cycloaddition, cycloreversion, and chain transfer. Catalysts with enhanced reactivity and control will be exploited to expand the scope of ROMP reactions to a more diverse array of monomers, thereby opening new avenues for the synthesis of functional polymeric materials without metal contamination. 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.