We show that the thermal and electrical properties of single wall carbon nanotube (CNT)-polymer composites are significantly enhanced by magnetic alignment during processing. The electrical transport properties of the composites are mainly governed by the hopping conduction with localization lengths comparable to bundle diameters. The bundling of nanotubes during the composite processing is an important factor for electrical, and in particular, for thermal transport properties. Better CNT isolation will be needed to reach the theoretical thermal conductivity limit for CNT composites.

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Carbon nanotubes possess exceptional mechanical properties and superior thermal and electric properties.[1±4] Hence, nanotubes can be ideal reinforcement fibers for structural composites. For example, a cast composite film consisting of polystyrene and carbon nanotubes (5 % volume fraction) has increased the modulus by 100 % and the strength of the polystyrene by 25 %.[5] Moreover, the carbon nanotubes reinforcement increased the toughness of the composite by absorbing energy because of their high elastic behavior during loading.

We demonstrate that dispersion of single walled carbon nanotubes (SWNTs) by ultrasonication with phospholipid-polyethylene glycol (PL-PEG) fragments it, thus interfering with its ability to block nonspecific uptake by cells. However, unfragmented PL-PEG promoted specific cellular uptake of targeted SWNTs to two distinct classes of receptors expressed by cancer cells. Since fragmentation is a likely consequence of ultrasonication, a technique commonly used to disperse SWNTs, this maybe a concern for certain applications such as drug delivery.