General Strategies Toward Mechanically Robust Biobased Polymers and Composites

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NON-TECHNICAL SUMMARYSustainable polymers from renewable natural resources have gained much momentum in recent years given their importance to a sustainable economy and society. Natural polymers, such as cellulose, hemicellulose, lignin, starch, proteins, and chitin, have been utilized in composites, plastics, biofuels and other applications. The development of synthetic polymers from molecular biomass, such as plant oils, rosin acids, terpenes, terpenoids, and furan, is a fast-growing area. However, there are many mounting challenges in increasing the component of biobased polymers in the commercial market, in contrast with dominant petrochemical-derived counterparts. To promote sustainability and national prosperity, this project will develop next-generation renewable polymers by designing general strategies based on wrapping of macromolecules on polymers from natural resources to improve their physical properties, especially addressing critical hurdles on inferior mechanical properties involving a variety of biomass. A central goal is to understand how macromolecular chain wrapping via supramolecular interactions dictates thermal and mechanical properties of these materials and to establish structure-property relationships.TECHNICAL SUMMARYSustainable biobased polymers from natural resources are facing a lot of compelling challenges. Among them, many polymers suffer inferior mechanical properties, largely due to their inherent low chain entanglements (thus, they have very high chain-entanglement molecular weight). Macromolecular architectures and compositions play vital roles in dictating these properties. The planned research is aimed to provide an economical, robust, and general approach to enhance mechanical properties of biobased polymers. The central idea is to wrap bulky biobased polymers with a flexible and highly entangled macromolecule via supramolecular interactions. The overall goal of the proposed research is to simultaneously maximize the use of biomass and enable biobased bulky polymers with high tensile strength and desirable elongation under stress by incorporating minimal levels of macromolecular wrapping. This project includes the development of macromolecular engineering protocols through parallel efforts on: (1) polymers containing bulky biomass such as fatty acid, resin acid, isosorbide, guaiacol, pinene, tulipalin, and glucose; and (2) biocomposites based on lignin and cellulose nanowhiskers. An essential goal is to understand how macromolecular chain wrapping via supramolecular interactions dictates thermal and mechanical properties of these materials and to establish clear structure-property relationships. The planned research program seeks to explore potentially transformative concepts to address sustainability issues by maximizing the use of biobased polymers with enhanced thermomechanical properties.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.