Nanotubes backbone

The N-doped carbons with a nanotube backbone combine a moderate presence of micropores with the extraordinary effect of nitrogen that gives pseudocapacitance phenomena. The capacitance of the PAN/CNts composite (ca. 100 F/g) definitively exceeds the capacitance of the single components (5-20 F/g). The nitrogen functionalities, with electron donor properties, incorporated into the graphene rings have a great importance in the exceptional capacitance behavior. 

For nanofibers and nanotubes, backbone modification refers to selective chemical transformation of one or more of the core blocks. In our preparation of nanotubes from the PI-PCEMA-PtBA and PS-PCEMA-PtBA triblock nanofibers, the core PI and PtBA blocks were sculpted away either fully or partially. These reactions are examples of nanofiber backbone modification. One can also consider inorganic reactions carried out inside one of the block copolymer phases to be a kind of backbone modification. These reactions lead to the formation of interesting polymer-inorganic hybrid nanostructures. This topic will be reviewed in the following paragraphs. 

Another interesting type of novel carbons applicable for supercapacitors, consists of a carbon/carbon composite using nanotubes as a perfect backbone for carbonized polyacrylonitrile. Multiwalled carbon nanotubes (MWNTs), due to their entanglement form an interconnected network of open mesopores, which makes them optimal for assuring good mechanical properties of the electrodes while allowing an easy diffusion of ions. 

The rational synthesis of peptide-based nanotubes by self-assembling of polypeptides into a supramolecular structure was demonstrated. This self-organization leads to peptide nanotubes, having channels of 0.8 nm in diameter and a few hundred nanometer long (68). The connectivity of the proteins in these nanotubes is provided by weak bonds, like hydrogen bonds. These structures benefit from the relative flexibility of the protein backbone, which does not exist in nanotubes of covalently bonded inorganic compounds. 

The DNA-carbon nanotube interaction is a complicated and dynamic process. Many studies on this subject have been pursued through a series of techniques, including molecular dynamic simulation, microscopy, circular dichroism, and optical spectroscopy.57,58 Although the detailed mechanism is not fully understood at present, several physical factors have been proposed to be driving DNA-carbon nanotube interactions,46,59-61 such as entropy loss due to confinement of the DNA backbone, van der Waals and hydrophobic (rr-stacking) interactions, electronic interactions between DNA and carbon nanotubes, and nanotube deformation. A recent UV optical spectroscopy study of the ssDNA-SWNT system demonstrated experimentally that... 

A functionalized carbon multi-walled nanotube, MWNT, was prepared in 2 steps by initially oxidizing the unfunctionalized nanotube with mixed acids followed by amida-tion with guanidine. When reacted with polystyrene-g-dibenzo-18-crown-6-ether, the polymer, polystyrene-g-dibenzo-18-crown-6-ether-g-(nanotube-g-guanidine), was formed having the nanotube component aligned perpendicular to the polystyrene backbone. 

Carbon nanotubes have limited solubility in most organic solvents. Phenylene-ethynylene derivatives have been prepared and used to noncovalently functionalize and solubilize these materials by means of the electron donor/electron acceptor characteristics of the polymer backbone. 

As revealed by FTIR and UV-Vis spectra in other studies, all PANI nanotubes, nanofibers, nanowires, nanorods, as well as microtubes, have backbone structures similar to that of the conventionally prepared granular PANI. In some cases, the Einstein shifts observed in the FTIR and UV-Vis spectra were ascribed to the interaction between the PANI chains and some small molecules, such as ethanol rather than to the chemical structures. 

As mentioned in the introduction, the tubular materials are fascinating new structures with a considerable potential for various applications. Most of the nanotubes investigated to date have been carbon-based nanotubes. In this chapter, we have discussed the properties of various nanotubes with a silicon or germanium backbone structure. Most of these nanotubes are still hypothetical, "made" only in the computer. We proposed the stability of phosphorus nanotubes, and about a year later Li et al. reported the successful synthesis of nanotubes from bismuth, which is isoelectronic with phosphorus. The stability of NbS2 nanotubes was also proposed in 2000, and these were synthesized by Nath and Rao in 2001... 

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