Novel Biodegradable Polyesters based on Lignin-derived 3-Carboxymuconolactone

• (4 S )-3-Carboxymuconolactone (3CML) was polycondensed with various α,ω-alkylene diols via dehydration polymerization to afford a series of 3CML polyesters, P(3CMLm). • DFT calculations revealed that 3CML adopts a nonplanar structure due to the presence of a stereogenic center, leading to flexible polymer chains. • The thermal decomposition temperature (T d,5% ) of P(3CMLm) increased with increasing alkylene spacer length. • In BOD tests using surface and deep seawater, P(3CMLm) showed over 40% biodegradation after 54 days, attributable to hydrolysis under mildly alkaline conditions. Lignin has attracted considerable attention as an abundant natural carbon feedstock capable of replacing petroleum-based resources. Recent development in microbial funneling techniques has enabled the stable production of dibasic compounds as biometabolic intermediates such as 2-pyron-4,6-dicarboxylic acid ( PDC ) and (4 S )-3-carboxymuconolactone ( 3CML ) from lignin-derived aromatic molecules under controlled metabolic processes. Our group has demonstrated that PDC -incorporated polymers exhibit excellent heat resistance, mechanical performance, adhesive nature to metal and wood substrates, and biodegradability in simulated natural environments. In this study, a series of 3CML -based polyesters was synthesized by dehydrated polycondensation with diol compounds containing various alkyl spacer lengths. The resulting polyesters displayed distinct macroscopic behavior and thermal properties compared with PDC -based analogues due to the nonplanar molecular structure arising from the asymmetric center in 3CML . Biodegradation tests of 3CML -based polyesters in both surface and deep seawater revealed biodegradation rates exceeding ca. 40% after 54 days, comparable to those of polyhydroxyalkanoates and polycaprolactone.