While it can be confirmed that the used nature inspired design allows to obtain macroscale, robust materials, the 3-point-bending fracture surfaces of xSP-NH 2 composites reveal that the majority of exposed supraparticles still do not show any significant polymer residues on their surface (Fig. ), indicating that the SP-epoxy interface still remains the weakest point of the hierarchical composites even after amine functionalization. We relate this to a possible partial decomposition of the amine moieties during the crosslinking at 325 °C. In fact, other amine-bearing ligands with different polar head groups -such as oleyl phosphate and silane ligands, able to provide other strong coordinative and covalent bonds to the magnetite surface, respectively -lead to similar mechanical responses (Fig. ). If an optimal anchoring to the polymer would be provided by the functionalization, it would be expected to observe significant differences when using other ligand head groups. Furthermore, the mesostructure of the composite materials was improved by optimizing the fabrication protocol for the packing of supraparticles before infiltration. Yet, overview microscopy images (Fig. ) reveal that still areas of loosely packed SPs can be found, which lead to regions with increased polymer accumulation that could act as weak spots within the material. Overall, the hereinreported values suppose a step-forward in achieving material cohesion, damage tolerance, and allowing to controllably grow from the nano-to the macroscale. There is though still room for further improvement in the overall mechanical behavior, e.g. by improving the SPs compaction and by fine tuning the 1st HL crosslinking strategy to avoid amine-ligand degradation.