Redox-Active Polymerization Catalysts and Their Applications

Traditional catalyst systems are reliable means to produce polymers with well-defined architectures and thermomechanical properties; however, they are often limited by a narrow monomer scope and their ability access few, if any, advanced polymer architectures. To address this limitation, a new class of catalysts have recently emerged that feature redox-active moieties that may access advanced architectures through catalyst electronic modulation that arises from redox events occurring on the ligand scaffold or at the active metal center itself. For example, researchers have explored the ability of redox-active catalysts to impart “on-off” kinetic control during ring-opening polymerizations and their ability to access block copolymers via redox-switching for a host of monomers.

This thesis provides a historical perspective of, and introduction to, redox-active (or in some cases redox-switchable) catalysis for ring-opening polymerization (ROP), including both its advantages and its limitations. I will then describe our attempts to expand the field of redox-active catalysis to include olefin polymerizations using tetradentate [ONNO], zirconium-centered precatalysts. These precatalysts, which bear ferrocenyl units symmetrically appended to the ligand are used to polymerize 1-hexene, a model α-olefin monomer. Lastly, I will provide a brief perspective as to remaining challenges that are of interest to the field of redox-active olefin polymerization catalysis. Specifically, it is interesting to note that no example of polymer tacticity modulation via redox-activity has heretofore been reported in the literature.