Development of biomass-derived furanic monomers for biorenewable polyesters and polyurethanes
Date
2019
Authors
Wilson, Jedediah Forrest, author
Chen, Eugene Y.-X., advisor
Reynolds, Melissa M., committee member
Ackerson, Chris J., committee member
Radford, Donald W., committee member
Crans, Debbie C., committee member
Journal Title
Journal ISSN
Volume Title
Abstract
Development of Biomass-Derived Furanic Monomers for Biorenewable Polyesters and Polyurethanes This dissertation describes the development of difuranic diol monomers through the N-heterocyclic carbene (NHC) catalyzed cross-coupling of the biomass-derived platform chemicals, 5-hydroxymethylfurfural (HMF) and furfural (FF), and their subsequent utilization in the synthesis of renewable polyesters and polyurethanes with tunable thermal and mechanical properties through the use of soft and rigid co-monomers. The resulting polymers can undergo reversible cross-linking with bis-maleimide cross-linkers through the thermally reversible Diels-Alder reaction involving both the internal and pendent furan rings. The ability to construct a thermally reversible cross-linked network, coupled with formation of a significant amount (up to 34%) of stable carbonaceous materials when heating the polymers to 700 °C, demonstrates some promising features of this class of new difuranic polymers. To address the need to enhance the molecular weight of the current furan-based polymers produced by the step-growth polycondensation process, alternative monomer structures have been designed to adopt the chain-growth mechanism. The first such alternative monomer belongs to a class of furan-derived lactones as candidates for ring-opening polymerization (ROP), which have been shown to produce high molecular weight polyesters because they follow the chain-growth mechanism. Two synthetic routes have been explored to produce such lactone monomers, and their polymerization behavior has been subsequently examined. The second such alternative is centered on a multifunctional furan acrylate monomer, methacrylate furan aldehyde (MFA). The studies tested a hypothesis that auto-tandem or cascading reaction involving the aldehyde functionality in MFA would undergo a benzoin condensation, then the consequent diacrylate would have the appropriate functionality for NHC catalyzed tail-to-tail coupling resulting in a proton transfer polymerization (HTP). It was found that the benzoin condensation was successful but an oxidation occurred at the α-hydroxy of the furoin diacrylate resulting in a highly electrophilic diketone furil diacrylate. Exploration of the coupling mechanism suggests that the enolate acts as a base catalyzing the oxidation. Through careful analysis of the adducts formed when the NHC was reacted with the furil diacrylate showed that the NHC had strong affinity for the diketone moiety thus blocking the HTP pathway. Overall, this work added significantly to our understanding of furans as monomers, NHC catalysis in furan monomer synthesis as well as polymerizations, and enhanced our ability to control thermal and mechanical properties of furan containing polymers.