Single-walled CNTs dependence

In our calculations we used the values of T0 and po the same as those determined from the experimental dependence for sample II, and a value was selected typical for the single-walled CNT (a 0.44). Sample IV contains the particles of disordered carbon and CNT and, besides, the particles of the ordered... 

The theory of the saturable absorption effect in single-wall CNTs has been developed. The dependence of the CNT surface conductivity on the driving field intensity has been calculated. It has been shown that simple approximation (1) is not valid in the SMT T case. The origin of such behavior is that Eq. (1) is obtained for the case of the two-level system in which the resonant line has the Lorentz form while in the CNT case the resonant line is the superposition of the different Lorentz lines. 

Water inside a carbon nanotube (CNT) shows another set of unusual features which have been the subjects ofgreat interest in recent years and are currently being studied extensively by experiments and simulations. A remarkable aspect unearthed is the ability of a CNT to act as water transporter and filter. The properties of water inside a CNT depend on the diameter d of the CNT, which is analogous to the parameter Wq of reverse micelles discussed in the preceding chapter. However, water within a single-wall CNT shows unusual features, such as single-file diffusion, the theory of which was developed in the past but a proper model system was lacking. The orientational motion of individual water molecules exhibits slow dynamics, quite different from those in the bulk. 

For example, Dillon et al. [154] reported a covalent attachment of branched polyethyleneimine (PEI) to the sidewalls of SWNTs through the use of fluorinated single-wall CNTs as precursors. The structural integrity of the original purified SWNT is maintained upon covalent functionalization with PEI. Solid-state NMR shows the presence of carboxylate substituents due to carbamate formation as a consequence of the reversible CO2 absorption to the primary amine substituents of the PEI. Desorption of CO2 is accomplished by heating under argon at 75 °C, while the dependence of the quantity of CO2 absorbed on temperature and the molecular weight of the PEI is also observed. 

Carbon nanotubes (CNTs) were discovered in 1991 by Iijima [182] and since then they have attracted much attention in many research fields. CNTs can be described as tubular structures rolled up from a graphene sheet. Depending on the number of tubular walls CNTs can be classified as single-walled carbon nanotubes (S WCNTs)... 

CNTs may consist of just one layer (i.e. single-walled carbon nanotubes, SWCNTs), two layers (DWCNTs) or many layers (MWCNTs) and per definition exhibit diameters in the range of 0.7 < d < 2 nm, 1 < d < 3 nm, and 1. 4 < d < 150 nm, respectively. The length of CNTs depends on the synthesis technique used (Section 1.1.4) and can vary from a few microns to a current world record of a few cm [16]. This amounts to aspect ratios (i.e. length/diameter) of up to 107, which are considerably larger than those of high-performance polyethylene (PE, Dyneema). The aspect ratio is a crucial parameter, since it affects, for example, the electrical and mechanical properties of CNT-containing nanocomposites. 

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