Elucidating Ring Opening Metathesis Copolymerization Thermodynamics of Monomers with Dissimilar Ring Strain Energies

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With the support of the Macromolecular, Supramolecular and Nanochemistry program in the Division of Chemistry, Professor Justin G. Kennemur of Florida State University is studying copolymerization thermodynamics of cyclic monomers in ring opening metathesis polymerization (ROMP). Copolymerization of two or more individual monomers into one macromolecule or polymer offers a divergent means of producing societal plastics that contain distributed functionality for a myriad of applications. Specifically, ROMP affords a variety of industrially relevant polyolefin-based materials through chain growth of strained cycloolefin monomers using well-established catalysts. This Kennemur team will perform systematic synthetic, kinetic and mechanistic studies to gain understanding of how basic thermodynamic principles along with key conditions, such as catalyst and solvent, ultimately dictate the reactivity ratios of various cycloolefin comonomers and their sequencing within the macromolecular chains that are grown. The project will also introduce new biomass-based terpene cycloolefins to provide a thermodynamic spectrum of medium ring-strain not afforded by the commonly employed cycloolefin monomers in ROMP. The research team will continue engagement with the first ever American Chemical Society Division of Polymer Chemistry and Division of Polymer Materials Science and Engineering student chapter that is co-established between a historically black college/university of Florida Agricultural and Mechanical University (FAMU) and an R1 research university in Florida State University. This student chapter will bring together a highly diverse body of students and faculty aimed at polymer science research. This unique platform will additionally be utilized to promote the growth of graduate and undergraduate students towards the development of leadership, both governed by outreach and the development of a new Florida-based conference, centered on polymer science.This project will focus on elucidating ring opening metathesis copolymerization thermodynamics of monomers with dissimilar ring strain energies. In the first aim, reactivity ratios of low-strain cyclopentene monomers that are highly sensitive to slight variations in their ring strain energy (RSE) will be determined using modern integrated approaches. Determined parameters will then be correlated to monomer sequencing within the polymer microstructure as a function of thermodynamic principles (monomer concentration, stoichiometry, and temperature). The second aim will examine, delta-pinene, and its variant, apopinene , which have RSEs that are in-between the high strain and low strain monomers typically employed in ROMP. Fundamental thermodynamic investigations and copolymerizations of these terpene-based monomers with each other and with low/ high RSE monomers will also be explored. Finally, the last specific aim will push the limits of disparity between RSEs by investigating high strain and low strain monomers in combination. Such investigations have potential for both alternating and blocky sequencing strategies. Taken together, these studies have the potential to provide guiding principles for the rational design of copolymers from readily available cycloolefin monomers; there is the potential to uncover basic principles that will apply to ring-opening polymerization (ROMP), in general, and thereby have a significant long-term scientific impact on polymer chemistry.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.