Hybrid systems of a semiconjugated organic polymer and single-wall nanotubes have been characterized by optical absorption spectroscopy, electron microscopy, and Raman spectroscopy. It is demonstrated that solutions of the polymer are capable of suspending nanotubes indefinitely while the majority of the accompanying amorphous graphite precipitates out of solution. Electron microscopy and Raman scattering indicate that through an intercalation process, the ropes of nanotubes are destroyed, resulting in individual nanotubes being well dispersed within the polymer matrix. Moreover, Raman and absorption studies suggest that the polymer interacts preferentially with nanotubes of specific diameters or a range of diameters.

International audienceThe large-scale production of single-wall carbon nanotubes (SWNTs) is reported. Large quantities of SWNTs can be synthesised by catalytic decomposition of methane over well-dispersed metal particles supported on MgO at 1000°C. The thus produced SWNTs can be separated easily from the support by a simple acidic treatment to obtain a product with high yields (70-80%) of SWNTs. Because the typical synthesis time is 10 min, 1 g of SWNTs can be synthesised per day by this method. The SWNTs are characterized by high-resolution transmission electron microscopy and by Raman spectroscopy, showing the quality and the quantity of products

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Thin films of poly(methyl methacrylate)–multiwalled nanotubes composites were produced by spin coating using different nanotube concentrations. The materials were characterized by scanning electron microscopy, energy-dispersive x-ray analysis, and Raman spectroscopy to obtain information on the possible interactions between the constituents and to control the homogeneity of the films. Electrical conductivity measurements of the composites, as a function of the nanotube concentration, show a percolation threshold at very low concentration. Also, the J–E characteristics exhibits a nonlinear behavior at low concentration, becoming linear far above the threshold.

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The low frequency RBM observed in SWNTs has been proved to probe efficiently their diameter distribution. We have built a model to estimate the interactions between individual nanotubes when arranged in bundles which leads to a RBM upshift of 10 to 20 cm−1. In a PMMA-SWNTs composite, our model shows that an upshift can be also predicted as due to the stress applied by the polymer on the bundles upon breathing. Finally, the interaction between concentric layers in MWNTs can lead to low frequency modes originating from the RBM of individual tubes as observed experimentally.