Light-Fueled In-Operando Shape Reconfiguration, Fixation, and Recovery of Magnetically Actuated Microtextured...

Covalent adaptable networks (CANs) enable reprocessability via dynamic bond exchange above their topology freezing transition temperature (T_v) despite chemical crosslinks. However, conventional CANs often exhibit insufficient viscosity reduction upon heating, necessitating extensive application of heat and pressure through direct contact for processing. In this study, a disulfide-bonded CAN is introduced to facilitate UV-assisted processing at room temperature, in addition to conventional thermal processing above T_v. At room temperature, UV irradiation accelerates stress relaxation, mirroring the effect of high-temperature activation (> T_v = 86 °C) without UV. Molecular dynamics (MD) simulation also reveals the underlying mechanism of UV- and heat-induced dynamic bond exchange. By incorporating magnetic NdFeB particles, magnetomechanical actuation of CAN/NdFeB microarrays is achieved. Unlike conventional approaches which rely on binders to maintain actuated shapes after removal of magnetic field, this system enables in-operando UV-fueled shape reconfiguration and fixation through dynamic bond exchange at room temperature, with reversible recovery of the original architectures on-demand. Furthermore, photoresponsivity allows for contactless spatiotemporal control over dynamic bond exchanges and resultant microarchitectures via a masking technique. This strategy offers facile, patternable 3D microfabrication and binder-free homologous shape-fixation in dry conditions without external pressure.