Orientational Co Nanorod-Enabled Ferromagnetic Hydrogel Actuators with Diverse Hosts

Abstract

Magnetic hydrogel actuators have promising applications in soft robots, wastewater treatment, and underwater detection due to the advantages of their remote control and high magnetic penetration. However, their controllability is limited by the general fabrication methods of doping paramagnetic nanoparticles and nonuniform ferromagnetic nanoparticles with a weak or nonconfigurable magnetic distribution. Herein, we report a kind of ferromagnetic hydrogel actuator comprising oriented ferromagnetic Co nanorods with high magnetic anisotropy, and the magnetic domains can be flexibly programmed by external fields. To demonstrate the generality of the approach and to research how the flexibility of the hydrogel hosts influences the behavior of the actuators, three kinds of hydrogel hosts have been used, including silica hydrogel, cellulose hydrogel, and clay hydrogel. The silica hydrogel actuators provide a holistic response. The cellulose hydrogel actuator can achieve a certain degree of deformation. The clay hydrogel actuators are capable of achieving large deformations such as the knot and the bow-knot. Furthermore, biomimetic actuators with the capacities for wriggling, paddling, and climbing simple obstacles are designed by utilizing the bending deformations of the clay hydrogel. In conclusion, this work provides an alternative strategy for designing and fabricating magnetically actuated hydrogel actuators for imitating biological units or constructing soft robots by regulating the orientation and distribution of ferromagnetic nanoparticles.

Flexible and Transparent Bagasse Aerogels for Thermal Regulation Glazing

“…The mixture was stirred for 2 days and dialyzed for another 2 days, after which the well-dispersed sugarcane cellulose solution was produced. Bagasse hydrogels were further fabricated by cross-linking the above surface-modified cellulose with polysiloxane using procedures described in the literature. , Typically, 0.4 g of CTAB and 3.0 g of urea were dissolved in 12 mL of functionalized sugarcane cellulose solution via sonication until the sol became homogeneous. Then, 2 mL of MTMS and 0.01 mmol of acetic acid were added to the above mixture under vigorous stirring and reacted for 30 min at room temperature.…”

Jamming of Miscible Liquids via Electrostatic Repulsion Between Polystyrene‐Modified Gold Nanorods and Toluene

“…They were prepared following a polyol method. [ 38 ] Specifically, cobalt laureate (2.73 g), RuCl 3 (0.039 g), and NaOH (0.225 g) were added to 75 mL of butanediol. The mixture solution was heated from room temperature to 170 °C and maintained at a target temperature for 12 min with mechanical stirring.…”

Nanocomposite Hydrogel Actuators with Ordered Structures: From Nanoscale Control to Macroscale Deformations

“…Analogously, several studies have proposed the preparation of ordered nanocomposites based on 1D nano-objects using the magnetic field-induced assembly. [93] For instance, Li et al exploited anisotropic hydrogel-metal hybrid materials that incorporated high-aspect ratio Ni nanowires aligned by magnetic field into a hydrogel matrix, which could implement deformation autonomously in response to light, as demonstrated in Figure 4e. [31] The inherent mechanism of photoresponsive deformation in the as-obtained hydrogel was stemmed from generation of spatial gradients of hydrophilic and hydrophobic group populations in the crosslinked network.…”

“…Oriented structure Magnetic field [ 31,35,37,50,[92][93][94][95] Nanomaterials High aspect to diameter ratio; Magnetic nanomaterials…”

“…Elaborate and programmable structure, complex and programmable deformation Require high-intensity magnetic field (Continued) Co nanorods [93] Bending and twisting, etc.…”