In this project funded by the Macromolecular, Supramolecular, and Nanochemistry Program in the Division of Chemistry, Professor Andrea M. Kasko of the Department of Bioengineering at University of California-Los Angeles is preparing polymers from biomass using starting materials (monomers) derived from lignin. Lignin is one of the most important structural polymers in nature. As the second most abundant natural polymer after cellulose, lignin is an inexpensive and widely available source of carbon. In this research, monomers or polymer building blocks based on lignin are first chemically functionalized to enhance their solubility in common organic solvents. These monomers are then polymerized by themselves or in the presence of other synthetic monomers to yield high molecular weight polymers and copolymers. The physical properties of the generated polymers are then systematically evaluated and compared to other high performance, commodity plastics. The properties that are being investigated include mechanical properties, thermal stability, solvent resistance and degradability or recyclability. The broader impacts of this work involve potentially substantial societal benefits by transforming natural resources into polymers, thereby decreasing society's dependence on petroleum resources for raw materials. This project also broadens participation in a number of ways. The multi-disciplinary nature of the research provides training to graduate and undergraduate students in organic, polymer and physical chemistry. Undergraduate students are involved in the project throughout the school year and during the summer through undergraduate research programs at University of California-Los Angeles. A strong emphasis is placed on recruiting and retaining under-represented populations in research, and promoting research to non-STEM undergraduates. A summer internship module on biopolymers is developed for veterans who have re-entered civilian life and are pursuing STEM degrees at local community colleges through the Project SERVES program.
The overall objective of this research is to synthesize polymers and copolymers incorporating hydroxycinnamate monomers derived from lignin. The team evaluates the properties of the generated polymers and copolymers as plant-derived alternatives to commodity and high performance polymeric materials. A series of substituted monomers and dimers based on hydroxycinnamic acids (monolignol biosynthetic precursors) and monolignols are first prepared, and then copolymerized via condensation polymerizations to produce poly(ester amide)s, poly(ester)s, poly(ether amide)s and poly(amide)s. Small molecules and polymers are also grafted to/from the double bond in the backbone of these poly(ester amide)s, poly(ester)s, poly(ether amide)s, and poly(amide)s. Flexible blocks (siloxane and poly(ethylene oxide)) are additionally incorporated into the polymers to broaden the range of achievable properties. The research team is also synthesizing benzoxazine-based polymers. Lastly, the material properties of the polymers, copolymers, and their blends and composites (mechanical properties, thermal stability, solvent resistance, and degradability/recyclability) are characterized. This research could have a positive impact on the environmental and economic sustainability because it focuses on the synthesis of polymers from abundant renewable feed stock.
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.