Synergistic Dual Dynamic Bonds in Covalent Adaptable Networks

Covalent adaptable networks (CANs), comprising polymer networks crosslinked by dynamic covalent bonds (DCBs), have garnered considerable attention as sustainable materials. Mastering the stress relaxation of CANs is essential for controlling their viscoelastic properties. An unexpected acceleration of stress relaxation has been observed in CANs containing dual dynamic bonds. The dynamic behavior of the second dynamic bonds can accelerate stress relaxation and lower the relaxation activation energy of dual dynamic CANs compared to analogous CANs that rely on only one type of DCB. These findings complement current approaches that utilize catalysts or adjust network parameters. In this minireview, we summarize the synergistic acceleration effects in various CANs containing dual dynamic bonds. We classify these effects based on the second dynamic bonds, including noncovalent bonds, me- chanical bonds, and the second DCBs. We also dis- cuss the mechanisms behind this synergy. Finally, we highlight the challenges and offer perspectives on harnessing the synergistic effects of these dual dy- namic systems to expand the chemistry and applica- tions of CANs.