Biobased dynamic polymer networks derived from castor oil and anhydrous piperazine

The development of castor oil-based polyurethanes has been restricted significantly because they have poor mechanical properties and cannot be reprocessed or recycled owing to their soft backbone combined with irreversible crosslinked structures. Herein, we synthesized novel castor oil derived dynamic polymer networks (DPNs) based on reversible piperazine-urea bonds, which were obtained by reacting isocyanate group with inexpensive anhydrous piperazine . The six-membered heterocyclic bifunctional piperazine acted as structural modifier to adjust the network stiffness and crosslink density and thus the mechanical properties of the DPNs. Soft, tough and even hard DPNs could be obtained easily by changing the feed content of piperazine. The reversible piperazine-urea bonds imparted DPNs with excellent malleability, reprocessability, and recyclability. In addition, the DPNs showed excellent solvent resistance, thermal stability, and durability. This study provides an important guidance for the synthesis of vegetable oil derived polymer networks that integrate tunable mechanical properties, reprocessability, and recyclability.