The D IP is a crucial parameter for coupling phenomena in functional NCs. By means of the used crosslinking strategy, this parameter can be further adjusted by changing the process temperature, time, and atmosphere without the necessity of sophisticated synthetic adjustments of the ligands. The NC surface functionalization with OA (and thus of the SPs) only allows weak interactions between the OA aliphatic chain and the epoxy polymer phase. Hence, aiming to tune these interactions in the second hierarchical level, the un-crosslinked SPs were surface modified with amine moieties that can serve as chemical anchoring points for the epoxy groups of the organic matrix of the 2nd HL, as depicted in Fig. . This modification proceeds via ligand exchange of the OA surface ligands with 4-Aminobutylphosphonic acid as indicated in Fig. . The phosphonic acid head group of the amino-ligand ensures a successful ligand exchange, since phosphate-derived acids are known to have a strong affinity to the Fe 3 O 4 NC surface, rapidly exchanging the surface-coordinated oleate molecules. It has to be noted that this step was applied before the crosslinking reaction, since after the crosslinking step, a dense polymeric derived network is formed, passivating the outer surface of the xSPs, and consequently preventing any subsequent SPs surface ligand-exchange. To ensure that only the outer surface of the SPs is modified during the ligand-exchange and, thus, still be able to crosslink the inner NC-NC, the concentration of amine ligands has to be carefully adjusted.