Multi walled carbon

An exhaustive study has been carried out recently on the synthesis of BN nanotubes and nanowires by various CVD techniques.17 The methods examined include heating boric acid with activated carbon, multi-walled carbon nanotubes, catalytic iron particles or a mixture of activated carbon and iron particles, in the presence of ammonia. With activated carbon, BN nanowires are obtained as the primary product. However, with multi-walled carbon tubes, high yields of pure BN nanotubes are obtained as the major product. BN nanotubes with different structures were obtained on heating boric acid and iron particles in the presence of NH3. Aligned BN nanotubes are obtained when aligned multi-walled nanotubes are used as the templates (Fig. 40). Prior to this report, alignment of BN nanotubes was achieved by the synthesis of the BN nanotubule composites in the pores of the anodic alumina oxide, by the decomposition of 2,4,6-trichloroborazine at 750 °C.116 Attempts had been made earlier to align BN nanotubes by... 

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. 

Hilding J., Grulke E. A., Sinnott S. B., Qian D., Andrews R. and Jagtoyen M., Sorption of butane on carbon multi wall nanotubes at room temperature. Langmuir 17 (2000) pp. 7540-7544. 

Exhaustive studies have been carried out on the synthesis of BN nanotubes and nanowires by various CVD techniques [225]. The methods examined include heating boric acid with activated carbon, multi-walled carbon nanotubes, catalytic iron particles or a mixture of activated carbon and iron particles, in the presence of ammonia. With activated carbon, BN nanowires are obtained as the primary prod-... 

R. Andrews, D. Jacques, M. Minot, and T. RanteU, Fabrication of carbon multi-wall nanotube/ polymer composites by shear mixing, MacromoL Mater. Eng., 1X1, 395-403 (2002). 

Carbon multi-walled nanotubes (MWCNTs or MWNTs) [1333-86-4]. These are produced as a black... 

M. J. Assael, K. D. Antoniadis, and D. Tzetzis, "The use of the transient hot-wire technique for measurement of the thermal conductivity of an epoxy-resin reinforced with glass fibres and/or carbon multi-walled nanotubes," Composites Science and Technology, vol. 68, pp. 3178-3183,2008. 

Potschke P, Bhattacharyya A, Janke A, Goering H (2003), Melt-mixing of poly-carbonate/multi-wall carbon nanotube composites . Comp Interfaces, 10, 389-404. 

Fig. 14. High resolution TEM observations of three multi-wall carbon nanotubes with N concentric carbon nanotubes with various outer diameters do (a) N = 5, do = 6.7 nm, (b) N = 2, do = 5.5 nm, and (c) N = 7, do = 6.5 nm. The inner diameter of (c) is d = 2.3 nm. Each cylindrical shell is described by its own diameter and chiral angle [151].

Whereas multi-wall carbon nanotubes require no catalyst for their growth, either by the laser vaporization or carbon arc methods, catalyst species are necessary for the growth of the single-wall nanotubes [156], while two different catalyst species seem to be needed to efficiently synthesize arrays of single wall carbon nanotubes by either the laser vaporization or arc methods. The detailed mechanisms responsible for the growth of carbon nanotubes are not yet well understood. Variations in the most probable diameter and the width of the diameter distribution is sensitively controlled by the composition of the catalyst, the growth temperature and other growth conditions. 

Because of the speeial atomie arrangement of the earbon atoms in a carbon nanotube, substitutional impurities are inhibited by the small size of the carbon atoms. Furthermore, the serew axis disloeation, the most eommon defeet found in bulk graphite, is inhibited by the monolayer strueture of the Cfj() nanotube. For these reasons, we expeet relatively few substitutional or struetural impurities in single-wall earbon nanotubes. Multi-wall carbon nanotubes frequently show bamboo-like defects associated with the termination of inner shells, and pentagon-heptagon (5 - 7) defects are also found frequently [7]. 

Early transport measurements on individual multi-wall nanotubes [187] were carried out on nanotubes with too large an outer diameter to be sensitive to ID quantum effects. Furthermore, contributions from the inner constituent shells which may not make electrical contact with the current source complicate the interpretation of the transport results, and in some cases the measurements were not made at low enough temperatures to be sensitive to 1D effects. Early transport measurements on multiple ropes (arrays) of single-wall armchair carbon nanotubes [188], addressed general issues such as the temperature dependence of the resistivity of nanotube bundles, each containing many single-wall nanotubes with a distribution of diameters d/ and chiral angles 6. Their results confirmed the theoretical prediction that many of the individual nanotubes are metallic. 

Many research opportunities exist for the controlled manipulation of structures of nm dimensions. Advances made in the characterization and manipulation of carbon nanotubes should therefore have a substantial general impact on the science and technology of nanostructures. The exceptionally high modulus and strength of thin multi-wall carbon nanotubes can be used in the manipulation of carbon nanotubes and other nanostructures [212, 213]. 

Many of the carbon nanotube applications presently under consideration relate to multi-wall carbon nanotubes, partly because of their greater availability, and because the applications do not explicitly depend on the ID quantum effects associated with the small diameter single-wall carbon nanotubes. 

Much of the experimental observations on carbon nanotubes thus far have been made on multi-wall tu-bules[15-19]. This has inspired a number of theoretical calculations to extend the theoretical results initially obtained for single-wall nanotubes to observations in multilayer tubules. These calculations for multi-wall tubules have been informative for the interpretation of experiments, and influential for suggesting new re-... 

The birth of the field of carbon nanotubes is marked by the publication by lijima of the observation of multi-walled nanotubes with outer diameters as small as 55 A, and inner diameters as small as 23 A, and a nanotube consisting of only two coaxial cylinders [2]. This paper was important in making the connection between carbon fullerenes, which are quantum dots, with carbon nanotubes, which are quantum wires. FurtheiTnore this seminal paper [2] has stimulated extensive theoretical and experimental research for the past five years and has led to the creation of a rapidly developing research field. 

Synthesis and Purification of Multi-Walled and Single-Walled Carbon Nanotubes... 

Among the several known types of carbon fibres the discussion in this chapter is limited to the electric arc grown multi-walled carbon nanotubes (MWCNTs) as well as single-walled ones (SWCNTs). For MWCNT we restrict the discussion to the idealised coaxial cylinder model. For other models and other shapes we refer to the literature [1-6],... 

Studies on the electronic structure of carbon nanotube (CNT) is of much importance toward its efficient utilisation in electronic devices. It is well known that the early prediction of its peculiar electronic structure [1-3] right after the lijima s observation of multi-walled CNT (MWCNT) [4] seems to have actually triggered the subsequent and explosive series of experimental researches of CNT. In that prediction, alternative appearance of metallic and semiconductive nature in CNT depending on the combination of diameter and pitch or, more specifically, chiral vector of CNT expressed by two kinds of non-negative integers (a, b) as described later (see Fig. 1). 

---