Light-Fueled In-Operando Shape Reconfiguration, Fixation, and Recovery of Magnetically Actuated Microtextured Covalent Adaptable Networks

초록

Covalent adaptable networks (CANs) enable reprocessability via dynamic bond exchange above their topology freezing transition temperature (Tv) 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 Tv. At room temperature, UV irradiation accelerates stress relaxation, mirroring the effect of high-temperature activation (> Tv = 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.

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