Graphene oxide (GO), the oxidized form of graphene, shows unique properties including high mechanical strength, optical transparency, amphiphilicity and surface functionalization capability that make it attractive in fields ranging from medicine to optoelectronic devices and solar cells. However, its insolubility in non-polar and polar aprotic solvents hinders some applications. To solve this issue, novel functionalization strategies are pursued. In this regard, this study deals with the preparation and characterization of hexamethylene diisocyanate (HDI)-functionalized GO. Different reaction conditions were tested to optimize the functionalization degree (FD), and detailed characterizations were conducted via elemental analysis, Fourier-transformed infrared (FT-IR) and Raman spectroscopies to confirm the success of the functionalization reaction. The morphology of HDI-GO was investigated by transmission electron microscopy (TEM), which revealed an increase in the flake thickness with increasing FD. The HDI-GO showed a more hydrophobic nature than pristine GO and could be suspended in polar aprotic solvents such as N,N-dimethylformamide (DMF), N-methylpyrrolidone (NMP) and dimethyl sulfoxide (DMSO) as well as in low polar/non-polar solvents like tetrahydrofuran (THF), chloroform and toluene; further, the dispersibility improved upon increasing FD. Thermogravimetric analysis (TGA) confirmed that the covalent attachment of HDI greatly improves the thermal stability of GO, ascribed to the crosslinking between adjacent sheets, which is interesting for long-term electronics and electrothermal device applications. The HDI-GO samples can further react with organic molecules or polymers via the remaining oxygen groups, hence are ideal candidates as nanofillers for high-performance GO-based polymer nanocomposites.

Graphene oxide (GO), the oxidized form of graphene, shows unique properties, such as strong mechanical strength, high thermal conductivity, amphiphilicity, and surface functionalization capability that make it very attractive in various fields, ranging from medicine to optoelectronic devices and solar cells. However, its insolubility in non-polar and polar aprotic solvents hinders some applications. To solve this issue, novel functionalization strategies are pursued. In this regard, the current study deals with the preparation and characterization of hexamethylene diisocyanate (HDI)-functionalized GO. Different reaction conditions were tested to optimize the functionalization degree (FD), and detailed characterization was conducted via Fourier-transformed infrared (FT-IR) spectroscopy to confirm the success of the functionalization reaction. The HDI-GO could further react with other organic molecules or polymers via the remaining oxygen groups, which makes them ideal candidates as nanofillers for high-performance GO-based polymer nanocomposites.

Liquid phase syntheses mainly yield nanoparticles with compact shapes, such as spheres or cubes. However, controlling not only the size but also the shape of magnetic nanoparticles would enable a fine-tuning of their intrinsic properties, due to the shape anisotropy induced by long-range dipolar interactions. We report here a fairly simple approach based on the reduction of an amidinate complex in the presence of a mixture of long-chains acid and amine to yield ferromagnetic Ni nanoparticles. The formation of stable Ni complexes could be promoted in situ by increasing the acid concentration, thus allowing tuning of the final particle size. While amine could be used as a soft reducing agent, dihydrogen was essential to promote anisotropic shapes. Electron holography combined with micromagnetic simulations showed that the resulting shape anisotropy could impose complex magnetic configurations within planar tetrapods. Regarding the heating efficiency, which directly scales with the magnetic hysteresis loop area, maxima of 100W·g–1 were found for nanoplates and nanorods, opening promising perspectives for magnetically induced catalysis.

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The direct integration of performant permanent magnets (PMs) within miniaturized circuits remains both a scientific and a technological challenge. Magnetophoresis‐driven capillary assembly of hard magnetic nanoparticles is a promising approach to fabricate 3D rare‐earth‐free PMs. However, this process implies the use of soft magnetic blocks to generate the magnetic field gradients required to localize the assembly directly onto silicon substrates. The impact of these soft elements onto the overall magnetic properties is evaluated using Co nanorods as hard material and 150 μm–thick Ni blocks. As expected, the presence of Ni softens the overall properties of the hybrid magnet obtained, but PM properties are preserved for reduced Ni volumes. Magnetic induction as high as 19 mT at a distance of 200 μm is generated by the hybrid Ni–Co–Ni structures, allowing for the electromagnetic actuation of a microelectromechanical resonant sensor.