Bio-Based Recyclable Thermosets: From Renewable Sources to Circular Materials

Integrating dynamic covalent networks with bio-based resources offers a powerful strategy to create recyclable thermosets while mitigating environmental and resource-related risks, advancing materials development toward a circular economy. Beyond sustainability, the structural diversity and functionality of renewable feedstock provide unique opportunities to design bio-based thermosets with tailored properties and advanced performance. This review summarizes recent progress in bio-based recyclable thermosetting polymers, with particular emphasis on the rational selection of renewable building blocks and their incorporation into recyclable, reprocessable, and high-performance networks. Key bio-derived functional motifs are discussed in terms of their reactivity, availability, and compatibility with dynamic covalent chemistries. Representative examples demonstrate closed-loop recycling, self-healing, stress relaxation, and shape reconfiguration without sacrificing mechanical integrity. Applications in carbon-fiber-reinforced polymer composites, flame-retardant materials, adhesives, and foams are highlighted to illustrate translational potential. Finally, remaining challenges and future opportunities are discussed, providing design principles for next-generation sustainable thermosets.