Closed-Loop Recyclable Vinylogous Carbamothioate-Based Covalent Adaptable Networks

Synthesis of covalent adaptable networks (CANs) has been considered a promising strategy to address the challenge of recycling thermosets. However, there is still huge room for improvement, such as diversity of polymer networks, closed-loop recycling processes, and individual monomer recovery. Herein, we designed and synthesized a closed-loop recyclable high refractive index CAN based on vinylogous carbamothioate dynamic chemistry. Both static and dynamic properties of the as-fabricated CAN were investigated in detail, showing improved properties compared to its counterpart. Critically, the relationship between the exchange kinetics of the model reaction, apparent exchange kinetics, bond exchange kinetics, and segmental relaxation in CANs was clarified. Moreover, the resulting CANs were closed-loop recycled through acidolysis and remanufactured based on the recovered pure monomers. The remanufactured CANs possess almost the same original performance. This study offers opportunities for the design of sustainable and closed-loop recyclable CANs with sophisticated dynamic properties.