Stereocontrolled cationic polymerization of vinyl ethers through asymmetric ion-pairing catalysis
Abstract
Next-generation technologies in adhesives, membranes, additive manufacturing, and biotechnology demand soft materials with a greatly expanded property space. Control of polymer stereochemistry is well known to improve the properties of otherwise chemically identical atactic materials. Despite its dramatic influence, difficulty controlling the chain-end stereochemical environment in ionic- and /or radical-based polymerization mechanisms has hindered progress in realizing general synthetic methods for control of polymer tacticity. Isotactic poly(vinyl ethers) (PVEs) are a class of polymers with untapped potential due to challenges controlling stereochemistry during their cationic polymerization. We propose to leverage advances in asymmetric ion-pairing catalysis to realize the first highly stereocontrolled synthesis of PVEs, thus creating a new class of thermoplastic elastomers. Recent developments in the field of chiral Bronsted acid catalysis for small-molecule transformations provide a plethora of structurally diverse catalysts that enable optimization of the catalyst- substrate interactions to facilitate high stereoselectivity. We will translate these advances to macromolecular systems and discover catalysts that can initiate polymerization and control tacticity during propagation. These studies will be integrated with our expertise in controlled polymerization methods to develop a cationic RAFT polymerization that will simultaneously control polymer stereochemistry and molecular weight (i.e. living, stereocontrolled polymerization). Realization of the proposed work will lead to a new class of semicrystalline, isotactic poly(vinyl ethers) and greatly expand the accessible property space and utility of these materials. Long term, we will seek to leverage the mechanistic insights of this work to develop general methods for tacticity control in ionic polymerizations using the tools of asymmetric ion pairing catalysis.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Feb 14, 2019
- Source ID
- W911NF1810084
Entities
People
- Frank Leibfarth
Organizations
- Army Contracting Command
- United States Army
- University of North Carolina at Chapel Hill