Magnetic-programmable organohydrogels with reconfigurable network for mechanical homeostasis

Synthetic materials with tunable mechanical properties have great potential in soft robotics and biomedical engineering. However, current materials are limited to the mechanical duality altering their mechanical properties only between soft and hard states and lack of consecutively programmable mechanics. Herein, the magnetic-programmable organohydrogels with heterogeneous dynamic architecture are designed by encasing oleophilic ferrofluid droplets into hydrogel matrix. As magnetic field increases, the mechanical properties of organohydrogels can be consecutively modulated owing to the gradual formation of chain-like assembly structures of nanoparticles. The storage modulus G′ increases by 2.5 times when magnetic field goes up to 0.35 T. Small-Angle X-ray Scattering (SAXS) confirms the reconfigurable orientation of nanoparticles and the organohydrogels show reversible modulus switching. Besides, the materials also exhibit high stretchability, magnetic actuation behavior and effective self-healing capability. Furthermore, the organohydrogels are applied into the design of effectors with mechanical adaptivity. When subjected to serious external perturbations, the effector can maintain mechanical homeostasis by regulating modulus of organohydrogel under applied magnetic field. Such materials are applicable to homeostatic systems with mechanically adaptive behaviors and programmed responses to external force stimuli.