Double-walled nanotubes

Abstract—The fundamental relations governing the geometry of carbon nanotubes are reviewed, and explicit examples are pre.sented. A framework is given for the symmetry properties of carbon nanotubes for both symmorphic and non-symmorphic tubules which have screw-axis symmetry. The implications of symmetry on the vibrational and electronic structure of ID carbon nanotube systems are considered. The corresponding properties of double-wall nanotubes and arrays of nanotubes are also discussed. 

Fig. 4. Schlegel-type diagram of the hemi-toroidal rim of a double walled nanotube, in which the inner and outer walls are connected by a set of n = 5 pentagon/heptagon pairs.

Finally, Eklund s group has described double-walled nanotubes (DWNT), with ca. 0.7 nm inner diameter and 1.4 nm outer diameter, that can form a three-layer cylindrical capacitor with a shell of bromine anions forming the outer electrode. Holes segregate on the outer nanotube, and saturation bromine doping creates 1 hole per 26 carbon atoms in the DWNT [135]. 

Double-stranded RNA (dsRNA) in yeast, 26 451—452 Double-stranded RNA viruses, 3 135 Double-suction pumps, 21 60, 63 Double tipping pan vacuum filter, 11 352 Double titration method, 15 145 Double vacuum-arc remelting (VAR), in titanium sponge consolidation, 24 854 Double wall nanotubes (DWNT), 26 737 Double-wall tanks, 24 296 Doubly smart block copolymers,... 

Abbreviations PDT, Photodynamic therapy EPR, Enhanced permeability and retention IHF, Tetrahydrofuran UV, Ultraviolet DNA, Deoxyribonucleic acid PL, Photoluminescence SWNT, Single-walled nanotube DWNT, Double-walled nanotube MWNT, Multi-walled nanotube IV, Intravenous HSP, Heat shock protein ... 

Naraghi M, Filleter T, Moravsky A, Locascio M, Loutfy RO, Espinosa HD. A multiscale study of high performance double-walled nanotube-polymer fibers. ACS Nano. 2010 Oct 26 4(ll) 6463-76. 

SWNTs single-walled nanotubes DWNTs double-walled nanotubes MWNTs multi-walled nanotubes CNTs carbon nanotubes not purified... 

KEYWORDS carbon nanotubes doped nanotubes double-walled nanotubes Raman spectroscopy transmission electron microscopy... 

The tube/tube attraction (mainly for single and double-walled nanotubes). 

Figure 11.1. Crystallinity of PVA-nanotubes composites versus carbon nanotube volume fraction, for various types of nanotubes (DWNT= double-walled nanotubes, OHMWNT= hydroxyled MWNTs, NMWNT= catalytic Nanocyl S.A. MWNTs, OMWNT=catalytic MWNTs from Orleans, AMWNT=Arc grown MWNTs produced in the author s laboratory. Reprinted with permission from reference (23)).

MultiwaUed carbon nanotubes (MWNT) consist of a concentric arrangement of single-walled nanotubes with a usually constant distance of layers. There are examples with just two nanotubes fit one into another (somany shells (more than 50). The latter measure many nanometers in diameter and may be so hard to distinguish from classical carbon fibers that only electron microscopy can reveal the difference. Common MWNTs, however, possess a smaller number of concentric tubes. The nomenclature of MWNT indicates the intercalation of the inner tubes by the notation (wi,mi) (n2,m2i (n3,m3) ...,starting from the central tube. 

Besides small carbon clusters generated in the reaction zone anyway, the presence of hydrogen further gives rise to light hydrocarbons that contribute to the deposition of DWNT as well. Hence, in principle, this is a floating catalyst CVD performed in situ. It has indeed been applied in a multitude of experiments for the deliberate production of double-walled nanotubes. Normally, acetylene is employed as carbon source because apparently it suits best to surround an existing nanotube with a second layer of amorphous carbon (refer to Section 3.3.6). 

Figure 3.22 (a) Double-walled nanotubes prepared by chemical vapor deposition, (b) The... 

T. J. Lee, and C.J. Lee, Fabrication and applications of conducting polymer nanotube, nanowire, nanohole, and double wall nanotube, Synth. Met., 153, 313-316 (2005). 

Carbon double-walled nanotubes (DWCNTs or DWNTs). These have been prepared by the Carbon Vapour Deposition (CVD) method with >90% carbon content and 50-80% DWCNT. They can be prepared with approximately the following dimension 5mn OD, 1.3-2.0nm ID and 50pm length and with 0.12-0.14g/ml bulk density and >600m2/g sirrface area. The rest (10-40%) consists of amorphoirs carbon and residtral metal catalysts which are deliberately placed in the original carbon in order to synthesise the carbon tubes. 

Researchers examined the effect of solvent selection on the mechanical properties of CNT/polymer composites fabricated from double-walled nanotubes and polyvinyl alcohol in different solvents. It was shown that solvent selection can have a dramatic effect on the mechanical properties of CNT/polymer composites. Also, a critical... 

Phospholipids have recently been utilised in materials science to produce concentric double-walled nanotubes [21-23]. 

With respect to the types of carbon nanotubes, it was shown that the double-wall nanotubes (DWNTs) give the lowest EQE of 3.9%. SWNTs yielded a significantly higher performance (EQE = 6.9%), while the best results (EQE = 10.7%) were obtained using thin MWCNTs. ... 

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