Imparting anisotropic performance to soft materials via a magnetically-driven programmable templating-deposition strategy

Creating biomimetic aligned structures in soft materials with fast stimuli-responsive ability and tunable performance is of great interest to intelligent material science. However, there is still a technical challenge to balance the relative velocities of polymeric gelation and nano-alignment/accumulation processes in a controllable manner. Herein, a magnetically-driven programmable templating-deposition strategy coupled with an oscillating electrical signal has been developed to impart tunable anisotropic performance to the soft hydrogels. Specifically, the programmable electrophoretic deposition was initiated from a typical self-aggregated chitosan/ Fe3O4 nanoclusters in the presence of an external magnetic field, in which case allows magnetically-driven fast templating of chitosan chains to the electrode surface, oriented/enriched nanoclusters into a compact "fiber-like" aligned structure, and then locked by the electric-field induced localized neutralization processes. An oscillating electrical signal has been used for the first time to manipulate the fiber thickness by varying the ON-OFF electrical signal sequences (e.g., each interruption provides extratimes/chances for nano-assembly), resulting in a higher concentration of magnetic particles and tunable aligned structure to the hydrogels with improved multifunctionalities (e.g., mechanical strength, conductivity, magnetic responsiveness, and photothermal activity). The proof-of-concept for potential applications in the controlled drug delivery system and smart magnetic catheter have also been demonstrated. Consequently, this versatile magnetically-driven programmable templating-deposition approach expands the range of stimuli-responsive materials beyond magnetic hydrogels, inspiring the creation of advanced functional soft materials and devices for wide-broad applications.