(501k) Feedstock Design for High-Quality Biomaterial Manufacturing

Traditional lignocellulosic feedstock design has focused on saccharification efficiency, which does not inform the material development. We have advanced fundamental understanding on how biomass structure characteristics impacts carbon material properties, which empowered the feedstock design toward high-quality materials. First, modeling of NIR data from over 2000 sorghum lines have identified 8 sorghum lines with diverse biomass structures. Carbon fibers were manufactured from these lines and underlying biopolymer characteristics defining crystalline structure and properties were identified. The study highlighted that lignin uniformity from the biomass defines the mechanical properties of carbon materials, which is very different from the traditional factors like lignin content and composition. Second, we further carried out cross-species studies with more diverse lignin structures from a broad range of biomass feedstock. Specifically, lignin extracted from hardwood (sugar maple), softwood (loblolly pine and red cedar), and herbaceous plant (corn stover and switchgrass) were used for carbon fiber manufacturing. Linear regression models were established to define the relationship among carbon fiber properties, microstructures, and properties. The results again highlighted that traditional biomass characteristics don’t impact lignin carbon material properties. Instead, the content of β-O-4 linkage correlates significantly with tensile strength and elastic modulus of lignin carbon fiber, indicating that the more linear β-O-4 linkage would promote carbon fiber performance. We further demonstrated that a higher β-O-4 content also promotes electroconductive performance of carbon fiber and improves the crystalline content and size, which could be due to the better miscibility with the guest polymer. Thirdly, based on these fundamental understanding, we have engineered lignin biosynthesis in sorghum to achieve improvement of lignin molecular weight and linearity, which increased carbon fiber properties significantly. The fundamental understanding has paved path to use synthetic biology to design feedstock for various high-quality carbon and polymer materials. The value-added products will in turn empower cost-effective and sustainable lignocellulosic biorefinery.