Sustainable Polyaddition Path to Polyesters via Catalytic Homocoupling of Renewable Dicrotonate Monomers

The development of biorenewable polyhydroxyalkanoate (PHA) chemistry has generated interest in crotonate-based monomers as versatile building blocks. Crotonates can be obtained through the pyrolysis of PHAs, offering both a sustainable end-of-life pathway for PHAs and a renewable route to crotonate monomers. This study presents a new polyaddition-type step-growth polymerization of dicrotonates in which alkene-functionalized polyesters are synthesized using potassium tert-butoxide as a simple base catalyst. The reaction proceeds rapidly at room temperature, achieving >99% conversion within seconds and requiring no byproduct removal. The properties of the resulting polyesters can be tuned via the choice of bridging diol, and the materials are degradable by hydrolysis. The polymers reported herein are soft, amorphous solids with predominantly cyclic architectures under standard conditions, while linear analogs can be accessed through a chain-end-capping strategy. The work presented herein bridges key principles of polymer sustainabilityincluding biorenewability of feedstocks, energy-efficient synthesis, and degradable end-of-life pathwayswith practical considerations essential for real-world application, such as operational simplicity, scalability, cost-effectiveness, and supply chain accessibility.