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To effectively utilize the anisotropic characteristics of hexagonal boron nitride (h-BN), we have developed magnetic h-BN hybrid platelets decorated with iron oxide (Fe 3 O 4 ) nanoparticles, which are used as magnetic carriers for tailoring the anisotropy of h-BN. The as-synthesized Fe 3 O 4 -coated h-BN powders can easily move under a relatively low magnetic field. With the aid of iron oxide nanoparticles, h-BN platelets randomly dispersed in an epoxy matrix are successfully reoriented in a direction vertical to the film plane. Moreover, by utilizing the anisotropic characteristics of h-BN platelets, Fe 3 O 4 -coated h-BN/ epoxy composites exhibit exceptional performance in terms of in-plane thermal conductivity. This result is attributed to an improvement in the heat-transport pathways in composite films due to the anisotropic ordering of thermally conductive h-BN sheets. The Fe 3 O 4 -decorated h-BN platelets will be promising candidates for significantly improving the performances of advanced electronic devices that require excellent thermal conductivity and electrical insulation.

To realize a wide range of applications using three-dimensional (3D) printing, it is urgent to develop 3D printing resins with exceptional features such as enhanced mechanical properties. Herein, we developed a series of photocurable elastomers incorporating a cross-linkable SiO 2 nanofiller for digital light processing (DLP) 3D printing. Methacrylate-functionalized polyether polyol was synthesized for the photocurable elastomers. To enhance the mechanical properties, surface-modified SiO 2 nanoparticles (NPs) were incorporated into photocurable elastomers; this led to the generation of interfacial cross-links between the polymer matrix and the NPs surface. The effect of SiO 2 NPs on the photocuring behavior of the elastomers was monitored using a photocuring depth test. Due to the small size and exceptional dispersibility of surface-modified SiO 2 NPs, suppressed severe light scattering, photocuring process, and 3D printing with a large amount of SiO 2 NPs (up to 20 wt %) were evenly conducted. Furthermore, tensile testing and hardness measurements were performed to reveal the effect of SiO 2 NPs on the mechanical properties of 3D-printed structures. The elastomer containing 20 wt % of cross-linkable SiO 2 NPs was observed to enhance the tensile strength and hardness by 87 and 52%, respectively, overcoming the limitation of conventional composites. To evaluate the resilience of the various photocurable elastomers containing SiO 2 NPs, continuous tensile loading−unloading tests were conducted. Furthermore, 3D printing of various structures was carried out using a DLP printer, and their compression and bending deformation was monitored in terms of the amount of SiO 2 NPs. Under high pressure, 3D-printed structures containing cross-linkable SiO 2 NPs were observed to exhibit mechanical durability without defects. Therefore, this study proposes a promising method for the development of photocurable elastomers, which can be utilized in practical 3D printing applications.

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