Dynamicity-Tunable Covalent Adaptable Networks Mediated by Catalysts

Covalent adaptable networks (CANs), crosslinked by dynamic covalent bonds (DCBs), possess reprocessability and recyclability like thermoplastics, offering a promising sustainable alternative to conventional thermosets. However, CANs face a significant trade-off between dynamicity and thermal stability, since heat-induced dynamic network reorganization enables reprocessing but inevitably compromises both mechanical performance and dimensional stability. Recent advances have sought to address such a dynamicity-stability trade-off through tuning the dynamicity of CANs, achieved by incorporating switchable and latent catalysts as well as exploiting the "quenching-activating" catalytic strategy. First, CANs incorporating switchable catalysts enable reversible tuning of their dynamicity based on stimuli-responsive regulation of the catalyst activity. Second, CANs incorporating latent catalysts allow off-to-on switching of their dynamicity based on stimuli-responsive release of catalytically active species from the latent catalysts, enabling a one-way transformation from thermosets to CANs. Moreover, CANs based on the "quenching-activating" catalytic strategy enable reversible "on-off" tuning of their dynamicity by quenching and activating the dynamic exchange reaction, allowing reversible switching between CANs and thermosets. Looking ahead, a promising direction is to develop dynamicity-tunable CANs via straightforward and simple "quenching-activating" strategies that allow rapid and on-demand transitions between CANs and thermosets, ultimately resolving the trade-off between dynamicity and thermal stability.