NSF Award
2305058
With the support of the Macromolecular, Supramolecular and Nanochemistry program in the Division of Chemistry, Professor Eugene Y. Chen of Colorado State University is developing new synthetic routes for the construction of technologically important cyclic polymers and copolymers from bio-based renewable monomers. Cyclic polymers are an intriguing class of macromolecules that lack chain ends. When compared to linear counterparts, these polymers typically have lower viscosity, faster crystallization kinetics, and sometimes higher resistance to chemical and thermal degradation. These properties make cyclic polymers ideally suited for a variety of industrially important applications. The project will utilize synthetic, catalytic, and mechanistic approaches to prepare a variety of cyclic polymers and copolymers with the aim of precisely controlling the structures and sequences of monomer units. Computational methods through established international collaborations will further guide experimental design. The synthetic work has the potential to help provide precision regular and block cyclic polymers at a scale large enough for structure/property relationship studies to be conducted by the broader polymer community. From the point of view of sustainability, the design principles associated with this project have the potential to help nucleate a sea change, whereby recyclable and upcyclable polymers are more widely produced and used as commodity plastics. The activities associated with this project are intended to broaden participation and enable the training of undergraduate and graduate students in polymer chemistry, with a distinct effort to develop and promote more sustainable approaches than are typically practiced today.<br/><br/>In this work, Lewis pair polymerization (LPP) will be used for tailored synthesis of cyclic polymers and copolymers. LPP exploits the synergy and cooperativity between an acid and a base of a Lewis pair (LP) to effect monomer activation, chain initiation, propagation, termination, and transfer events. This cooperative two-component catalytic mechanism provides several advantageous features when compared to other polymerization methods, particularly with respect to compounded sequence control and spatiotemporal control in one-step precision synthesis. Cyclic polymers (CPs) have historically been less studied than their linear counterparts, which is mainly due to limited synthetic access to this interesting class of polymers. Specific objectives of the project include: (1) developing a better fundamental understanding of the factors that determine spatial and temporal control in the synthesis of precision CPs and cyclic block copolymers (cBCPs), (2) synthesizing higher-order multi-BCPs by LPP of bio-based acrylic monomers in one pot and one step, and (3) constructing stereoregular and recyclable CPs derived from renewable vinyl lactones utilizing chiral dinuclear LPs as promoters.<br/><br/>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.
