[en] Single-layer graphene oxide (SLGO) possesses carboxylic and hydroxyl groups suitable for reactions with aliphatic or aromatic diisocyanate molecules. TEM analysis reveals that aliphatic diisocyanate molecules caused SLGO to scroll into star-like formations, whereas aromatic diisocyanate molecules retained SGLO in a flat-sheet morphology. TGA confirms the stabilisation of the formed urea and urethane groups on SLGO, but the onset of sheet pyrolysis occurs at a lower temperature due to isocyanate reactions with anhydride and epoxide groups embedded in the sheet. Pendant isocyanate groups act as bridging units to facilitate the attachment of pyrrole molecules, which are then used as anchor sites for the covalent polymerisation of pyrrole to polypyrrole (PPy). The use of FeCl₃ as the polymerisation catalyst generated both covalent and free PPy, but also iron hydroxide nanoparticles were observed decorating the SLGO surface. When using ammonium persulfate as a catalyst and dodecylbenzenesulfonate as a dopant, free PPy could be removed under treatment with solvents to leave a purely covalent system. Discrete regions of SLGO were observed decorated with nanoparticles of PPy along the edge or across the surface of individual sheets. It was found that the flexibility of the SLGO sheet and the type of diisocyanate used directly affected the electrical resistance of the final composite.

[en] We develop a low temperature, organic solvent-free method of producing iron containing carbon (Fe-C) nanoparticles. We show that Fe-C nanoparticles are self-assembled by mixing ferrocene with sub-critical (25.0 °C), near-critical (31.0 °C) and super-critical (41.0 °C) carbon dioxide and irradiating the solutions with UV laser of 266-nm wavelength. The diameter of the iron particles varies from 1 to 100 nm, whereas that of Fe-C particles ranges from 200 nm to 1 μm. Bamboo-shaped structures are also formed by iron particles and carbon layers. There is no appreciable effect of the temperature on the quantity and diameter distributions of the particles produced. The Fe-C nanoparticles show soft ferromagnetic characteristics. Iron particles are crystallised, composed of bcc and fcc lattice structures, and the carbon shells are graphitised after irradiation of electron beams.

[en] A facile and rapid assembly of powdered carbon nanotubes (CNTs) into compressible, porous, macroscale monoliths is reported. Despite a Poisson's ratio just above zero, we found that the sample under compression inside a scanning electron microscope (SEM) revealed CNT regions behaving in auxetic and vortex-like rotational modes as well as standard collapse responses. This method is crucial in understanding the macroscale behaviour based on the accumulation of nanoscale responses to an applied force.