Nanotube chirality

The SWNT systems chosen in the present studies include 3 armchair nanotubes and 3 zigzag nanotubes with diameters ranging from 4 A to 12 A, and 1 chiral nanotube with a diameter of 8.28 A. The nanotubes were carefully chosen to address the fundamental issues of curvature and chirality and the effect of each on the adsorption capacity. First, to understand the curvature effect on hydrogen uptake, we selected nanotubes with diameters varying from about 4 A to 12 A. Next, to investigate the effect of nanotube chirality, we intentionally chose the nanotubes of different chiral architectures with similar diameters. Finally, to study the capacity of a given nanotube, we included three different H2 loadings at 0.4 wt. %, 3.0 wt. % and 6.5 wt. %, respectively, in our MD simulations. 

Molecular statics calculations by Buldum and Cfraci [71] support the hypothesis that the observed lock-in orientations are directly related to commensurate registry, and the particular set of commensurate orientations is determined by the CNT chirality (the wrapping orientation of the outer graphene sheet of the CNT). Thus the friction experiments provide a novel method for measuring the nanotube chirality. Large multiwall CNTs of different... 

What is the thermal conductivity of silicon nanowires, n-alkane single molecules, carbon nanotubes, or thin films How does the conductivity depend on the nanowiie dimension, nanotube chirality, molecular length and temperature, or the film thickness and disorder More profoundly, what are the mechanisms of heat transfer at the nanoscale, in constrictions, at low tanperatures Recent experiments and theoretical studies have dononstrated that the thermal conductivity of nanolevel systems significantly differ from their macroscale analogs [1]. In macroscopic-continuum objects, heat flows diffusively, obeying the Fourier s law (1808) of heat conduction, J = -KVT, J is the current, K is the thermal conductivity and VT is the temperature gradient across the structure. It is however obvious that at small scales, when the phonon mean free path is of the order of the device dimension, distinct transport mechanisms dominate the dynamics. In this context, one would like to understand the violation of the Fourier s... 

Table 6.1 Effect of carbon nanotube chirality on the conductivity.

SWCNT bundles containing nanotubes with different diameters are easy to obtain experimentally, but such samples may lead to overlapping RBM modes and complex Raman spectra that are difficult to interpret. In contrast, SWCNTs synthesized via the HiPCO method are favored for spectroelectrochemical studies due to their small diameters, which lead to well-separated RBM peaks, thereby simplifying nanotube chirality assignments significantly [58, 72]. 

Molecular dynamic simulations show that the confined space of SWCNTs may influence both the kinetics and thermodynamics of the Diels-Alder reactions between anthracenes and N-substituted maleimide guests, favoring an unusual regioselectivity. Thus, in the confined space of CNTs, the 1,4-exo adduct of a Diels-Alder cycloaddition may be produced instead of the 9,10-adduct, which is favored in bulk. It is possible that the nanotube chirality could influence the outcome of the reaction, as this could alter the preferred orientation of the reactants inside the SWCNT. However, it was snspected that the diameter of the SWCNT is likely to have by far the largest influence on the reaction outcome, as this will have the biggest influence on how close the reactants can approach each other [195]. 

---