Fast-Reprocessing, Postadjustable, Self-Healing Covalent Adaptable Networks with Schiff Base and Diels-Alder Adduct

Covalent adaptable networks (CANs) are a new type of polymers, which possess excellent performance of thermosets and reprocessability of thermoplastics. Nevertheless, it is still a challenge to realize rapid reprocessing and postadjusting (adjust properties after preparation). Herein, for the first time, a method of combining Schiff base and Diels-Alder adduct in one network is developed to achieve rapid reprocessing and postadjusting. Through the dissociation of the Diels-Alder adduct at high temperatures, the cross-link densities of the networks are reduced, thereby accelerating the rearrangement of the networks and realizing the rapid reprocessing and self-healing. Moreover, the reconnecting degree of network after dissociation of Diels-Alder adduct can be easily controlled by annealing; as a result, the properties of the obtained CANs are postadjustable. This work provides a simple and promising approach of achieving excellent reprocessing and postadjusting for CANs via the synergism of an associative dynamic chemistry with a dissociative dynamic chemistry.