(646a) Mechanism-Based Lignin Bioprocess and Biomaterial Design

Lignin is one of the most abundant biopolymers on earth. Despite the abundance, lignin remains primarily a waste stream from paper, pulping, and biorefining industries. The utilization of lignin as a fungible product is fundamental to the sustainable development of our society. Nevertheless, efficient and cost-effective lignin processing and material heavily depend on the structure-functional relationship between lignin chemistry and bioprocess or biomaterial features. In the past decades, we have substantially advanced understanding of how lignin chemistry could impact bioprocessing efficiency and biomaterial quality. First, we have revealed that lignin fractionation into smaller molecular weight, monomer-containing, and hydroxyl group-enriched fractions will significantly improve lignin dissolution and bioprocessibility. Based on the fundamental understanding, we have substantially improved lignin conversion efficiency, titer, and economics to PHA and lipid, along with achieving efficient co-utilization of carbohydrates and lignin. Second, we discovered that the higher molecular weight, better uniformity, and more ether linkages could improve carbon material properties. The fundamental understanding has guided the lignin process and feedstock design to substantially improve lignin carbon fiber property and achieve co-improvement of feedstock stress tolerance. Third, we found that lignin with a more condensed structure improves the stability and size selection for nanoparticles. We subsequently designed biomass processing to derive the structure to produce stable lignin nanoparticles. Fourth, we found that lignin functional groups and molecular weight also impact the interaction with asphaltene in a way that lignin can be tailored to derive asphalt binder modifiers with higher PG grades. We have integrated the discovery with biorefinery design to derive lignin as an effective asphalt binder modifier. Overall, based on the fundamental understanding, we have developed various process and feedstock designs to transform lignin into a precursor for broader biomaterial applications. The fundamental understanding will guide the advancement of a broader spectrum of functional materials from lignin.