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.

Magneto-responsive nanocomposites are prepared by mixing 1−5 vol % of Fe nanoparticles (NPs) in a metallo-supramolecular network made of poly(n-butyl acrylate) (PnBA) bearing terpyridine side groups and cross-linked by the addition of different amounts of Zn 2+ ions. To have a clear understanding of the stepwise increase of complexity, the thermomechanical behavior of these materials was characterized through shear linear rheology at each step of their preparation. The metallo-supramolecular networks reveal a clear transition from polymer-to network-driven dynamics when passing progressively from low (<0 °C) to high temperature. While terpyridine (TPy)−Zn 2+ complexes are usually treated as independent "stickers", the analysis of our master curves strongly suggests their aggregation. After the addition of 1−5 vol % of Fe nanoparticles within the supramolecular networks, we evidence the presence of TPy−NP bonds, resulting in a hybrid network of much longer relaxation time. Lastly, we combine thermal imaging and induction heating to emphasize the signature of sticker dissociation, offering new technical solutions to deepen our fundamental understanding of supramolecular networks.

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