Magnetothermal Shape-Morphing of Thermoset Structures

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 T_g is 62 °C, and the topology freezing transition temperature T_v 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.