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Abstract
As the global use of plastics continues to expand, the need to investigate alternate feedstocks for high-performance polymers is increasing. Lignin is a promising feedstock due to its widespread abundance and significant structural variety. In this work, a number of novel, lignin-derived monomers are synthesized, and resultant polymers are fully characterized for thermal, mechanical, and processing properties. First, a suite of nine polyester elastomers were synthesized. Iterative structural permutations provided a significant array of tensile properties, from brittle to exceptionally ductile thermoplastics. The effects of various structural features were investigated using melt rheology to correlate to properties. It was also demonstrated that these materials are easily chemically-recyclable in rapid timeframes. Building on this foundation, two novel, biobased crosslinkers were polymerized with a ductile thermoplastic elastomer at loadings between 0.25% and 5.0%. Significant improvement to tensile and cyclic tensile properties were achieved, and comprehensive rheological analysis was conducted to analyze the efficiency of crosslinking between the two additives. Two chemical-recycling experiments were conducted, and it was found that the crosslinked elastomers degraded extremely rapidly under basic conditions with excellent retention of monomer feed ratio. Finally, a novel, biobased monomer was synthesized, and the polyester was fully characterized. Including two other previously reported ester-based monomers, three polyesters and six poly(ester amide)s were synthesized. The polymers were found to be remarkably thermally stable and exhibited a wide array of mechanical properties, including one example that exhibited excellent elastomeric recovery. This work ultimately describes the synthesis of many polyesters that encompass a very wide array of thermal, mechanical, and rheological properties and offers significant contributions toward characterization and applications of materials in this class.