Search

Magnetic soft robots are promising for diverse applications, since they can achieve multimodal locomotion through programming magnetization. However, reprogrammable magnetization of soft robots remains a challenge. Here, we prepare a magnetic elastomer containing both Fe3O4 and CrO2 particles, where Fe3O4 nanoparticles can be heated through the magnetothermal effect. Once the temperature exceeds the Curie point of CrO2 particles, the original magnetization profiles of the elastomer can be erased and re-written. We tune the magnetization profile of a one-dimensional magnetic strip to realize three shape transformation modes, and the reprogrammed magnetization profiles are validated experimentally. The magnetothermal heating process is simulated. We also demonstrate reprogrammable shape transformation of two-dimensional magnetic soft structures. Finally, a reprogrammable hand-shaped soft robot is designed and used as a magnetic switch in a LED circuit. [ABSTRACT FROM AUTHOR]

Shape‐morphing of thermosets is challenging due to their permanently cross‐linked polymer network structure. Here, a magnetothermal shape‐morphing strategy is proposed for complex thermoset structures via reshaping, assembly, and shape memory. The thermoset composite is fabricated by adding magnetic nanoparticles into dynamically cross‐linked thermoset resin, which imparts magnetothermal effect and reprocessability under an alternating magnetic field. Epoxy composites are prepared with various weight fractions of Fe3O4 nanoparticles, and their magnetothermal and thermomechanical properties are studied. For a composite with 15 wt% Fe3O4 nanoparticles, the glass transition temperature Tg is 62 °C, and the topology freezing transition temperature Tv is 175 °C. An alternating magnetic field with a working power of 2000 W can generate a temperature of 156 °C, enabling bond exchange reactions and stress relaxation in the dynamically cross‐linked epoxy resin. Magnetothermal reshaping and bonding facilitate the assembly of complex‐shaped structures from simple units, while magnetothermal shape memory provides rapid actuation deformation responses within 60 s. Various examples of magnetothermal shape‐morphing of complex thermoset structures, including grasper, origami, and octopus‐inspired functional structures, are demonstrated. The results indicate that the present shape‐morphing strategy provides advantages such as remote control, high efficiency, flexible design, and straightforward structural fabrication. [ABSTRACT FROM AUTHOR]