Nanotube scroll

Carbon tubules (or nanotubes) are a new form of elemental carbon recently isolated from the soot obtained during the arc-discharge synthesis of fuller-enes[I]. High-resolution electron micrographs do not favor a scroll-like heUcal structure, but rather concentric tubular shells of 2 to 50 layers, with tips closed by curved, cone-shaped, or even polygonal caps. Later work[2] has shown the possibility of obtaining singleshell seamless nanotubes. 

The yield strengths of defect-free SWNTs may be higher than that measured for Bacon s scroll structures, and measurements on defect-free carbon nanotubes may allow the prediction of the yield strength of a single, defect-free graphene sheet. Also, the yield strengths of MWNTs are subject to the same limitations discussed above with respect to tube slippage. All the discussion here relates to ideal nanotubes real carbon nanotubes may contain faults of various types that will influence their properties and require experimental measurements of their mechanical constants. 

Zhang W, Wen X, Yang S, Yolande B, Wang ZL (2003) Single-crystalline scroll-type nanotube arrays of copper hydroxide synthesized at room temperature. Adv Mater 15(10) 822-825... 

Lavin, J.G., S. Subramoney, R.S. Ruoff, S. Berber, D. Tomanek, Scrolls and nested tubes in multiwall carbon nanotubes. Carbon 40, 1123-1130, 2002. 

As mentioned above, electronic properties of CNTs depend on the chirality and presence of defects in the scrolled graphene layer. Metallic nanotubes can have an electric current density more than 1,000 times greater than metals such as silver and copper. All nanotubes are expected to be very good thermal conductors along the tube, but good insulators laterally to the tube axis.8... 

Fig. 28 Cross-sectional TEM images of monoamine-intercalated VO, nanotubes showing serpentine-like scrolls.

It must be pointed out that tile VO, scroll-like structures are not genuine nanotubes of the type formed by carbon or metal dichalcogenides. 

Fig. 8.27. TEM images of VO, nanotubes with intercalated amine having varying chain lengths (a) C4VO,-NT (b) C,6-VO,-NT. The length of the bar is 50 nm. (c) Cross-sectional TEM images of monoamine-intercalated VO, nanotubes showing serpentine-like scrolls.

Figure 2. SEM and HRTEM images of InGaAs/GaAs nanotubes rolled-up from bi-layered films, (a) Two scrolls after their collision at the end of their formation process (b) Initial-bifilm thickness 4ML GaAs +4ML lnxGai.xAs(x = 0.6) (c) 2ML GaAs + IML InAs.

Figure 8-59. Idealized models of multi-wall nanotubes (a) Russian doll (b) hexagonal prism (e) scroll.

The synthesis of V2 02,45(alkylamine) nanotubes, by a sol-gel reaction using vanadium oxide triisopropoxide in the presence of hexadecyl amine template and hydrothermal treatment was descrihed [6, 31]. These nanotuhes consist of concentric shells with alternating V202.45(alkylamine) layers. Most of them are obtained as scrolls. Further studies [61] showed that the nanotuhe material could he used as a li insertion electrode. To obtain the electrode material, the nanotubes were refluxed, first, for 24 hours in ethanolic solution of NaCl, in order to remove the hexadecylamine template. Sodium ions were intercalated between... 

The common featnres of carbon whiskers, cones, scrolls, and GPCs, besides their chanistry and the graphitic natnre of their bonds, are their morphology and the high length-to-diameter aspect ratio, which places them between graphite and carbon nanotube materials. In the foUowing sections, we examine the varions types of these materials, show the effect of structural conformation, as well as describe its properties and potential applications. 

Caron phase shape (shell) Nanofibers asso-eiated with metal phase forming nanoeoatings Nanofilms scrolled in nanotubes Nanofilms associated with nanocrystals of metal containing phase Nanofilms forming nanobeads with metal containing phase... 

Carbon nanotubes (CNTs) discovered by lijima (1991), are seamless cylinders made of rolled up hexagonal network of carbon atoms. Single-wall nanotubes (SWNTs) consist of a single cylindrical layer of carbon atoms. The details of the structure of multi-wall carbon nanotubes (MWNTs) are still being resolved, but can be envisioned as a tubular structure consisting of multiple walls with an inter-layer separation of 0.34 nm. The diameter for inner most tube is on the scale of nanometer. In one model, the MWNTs are considered as a single sheet of graphene that is rolled up like a scroll to form multiple walls [33]. 

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