Ultrafast Remote Healing of Magneto-Responsive Thermoplastic Elastomer-Based Nanocomposites

We describe herein, a general, efficient, and scalable process to design magneto-responsive thermoplastic elastomer-based (nano)composites that can be repeatedly healed in a few tens of seconds by triggering polymer melting upon exposure to a high-frequency magnetic field. Three series of composites loaded with 1-15 vol % of Fe3O4 nanoparticles, Fe nanoparticles, or Fe microparticles were produced and characterized in depth with the aim to identify the physical properties required for two applications: (1) material healing, which we evaluate through the rewelding of precut samples and subsequent tensile tests, and (2) surface smoothening of 3D-printed objects, serving to remove superficial defects and improve their appearance. The optimal formulation consisting of a composite reinforced with 5 vol % of Fe nanoparticles ensures a high ability to heat while keeping a low viscosity in the molten state being ideal for polymer processing.