Coiled carbon nanotubes

MODEL STRUCTURE OF PERFECTLY GRAPHITIZABLE COILED CARBON NANOTUBES... 

Graphitizable coiled carbon nanotubes Table 1, Characteristics of some knees with minimal diameter difference... 

Zhong, D.Y., Liu, S., Wang, E.G., 2003. Patterned growth of coiled carbon nanotubes by a template-assisted technique. Appl. Phys. Lett. 83, 4423—4425. 

Figure 13.11 Electrothermal (a) and chemical (b) actuation in coiled carbon nanotube yarns infused with silicone rubber.

Lu M, Liu W-M, Guo X-Y, Li H-L. Coiled carbon nanotubes growth via reduced-pressure catalytic chemical vapour deposition. Carbon 2004a 42(4) 805-811. 

Popovic ZP, Damnjanovic M, Milosevic I (2013) Anisotropy of thermal expansion of helically coiled carbon nanotubes. Phys Status Solid B 250 2535-2538... 

Dmitrovic S, Popovic ZP, Damnjanovic M et al (2013) Strain engineering of electronic band structure and optical absorption spectra of helically coiled carbon nanotubes. J Nanoelect Optoe-lektr 8 160-164... 

Lau, K.T., Lu, M., Hui, D., 2006. Coiled carbon nanotubes synthesis and their potential application in advanced composite stmctures. Composites Part B Engineering 37 (6), 437-448. 

Xie, J., Mukhopadyay, K., Yadev, J., Varadan, V. K., Catalytic Chemical Vapor Deposition Synthesis and Electron Microscopy Observation of Coiled Carbon Nanotubes, Smart Mater. Struct., 12,744-748 (2003). 

The nanowires in Fig. 10.5, straight and coiled, are believed to be SiNW. Experiments were performed to verify that they were not carbon nanotubes or metal nanorods. One method to prove this was by using a substrate other than Si. In this case, AI2O3 wafers replaced Si as the substrate to avoid interference from the Si substrate for characterization. The SiNW grown on Si are shown in Fig. 10.11, and those grown on the AI2O3 wafer are shown in Fig. 10.12. Characterization of these nanowires yielded that they were SiNW. 

The naming of specific carbon nanotubes is based on using a pair of numbers that indicate the coiling direction and the perimeter of the tube. This pair of descriptors (n,m) results from geometrical considerations that are presented in the following section. 

Therefore, multiwalled carbon nanotubes may henceforward be assumed normally to consist of concentric single-walled tubes. These are largely independent of one another and may belong to different structural types even within an individual MWNT. However, this does not mean that alternative structures do not exist. At least partially coiled species have been observed in some cases, and rolled up graphene layers play an important role in some hypotheses on the mechanism of nanotube formation. 

It was not long after the discovery of carbon nanotubes before specimens with coiled or helical shapes were observed. These helical nanotubes (hMWNT) are often found as by-product in the synthesis of multiwalled nanotubes, yet by now a directed preparation has succeeded as well. Their extraordinary shape turns the helical nanotubes into an interesting subject of research as the expected electronic properties like inductive effect under electrical current should enable an application, for example, as nanocoils. ... 

Interesting supramolecular structures can furthermore be obtained by the controlled crystallization of polymers hke polyethylene or nylon-6,6 on carbon nanotubes. The latter serve both as template and as nucleus of crystallization. There are in principle three modes of how a polymer crystal might grow on a nanotube surface (a) Phase separation may occur in the course of the crystallization so the initially dispersed carbon nanotubes rea omerate and precipitate, (b) The polymer coils around the individual tubes whose solubility increases in the sequel,... 

The carbonization of pure organic compounds such as carbazole, phenazine, acridine (for formulas, see Figure 7.2) has also been studied under 7.5 Mbar argon pressure [23], Volatile compounds such as benzene, pyridine, pyrazine, quinoline, and phenazine have been calcined at 1073 K in sealed quartz glass tubes [24], Bent carbon nanotubes and coils with a nitrogen content of about 1% were formed when pyridine, 5-methylpyrimidine, or i-triazine (see Figure 7.2) were decomposed on small catalytic cobalt particles at 1123 or 1373 K [25], Carbon nanotubes with about 2% N were produced in excellent yield and free of other carbon materials by pyrolysis of pyridine vapor at 1373 K in an argon stream with admixed iron pentacarbonyl, [Fe(CO)s] [26], In another study, pyrrole vapor has been catalytically decomposed on nickel sheets at 1073 K [27],... 

Figure 2. TEM micrograph showing (a) straight carbon nanotubes grown at the nickel wire (b) coiled nanotubes grown at the surface of stainless steel.

In conclusion, carbon nanotubes were successfully synthesized at low temperature (500-700 °C) under assistance of plasma generated at atmospheric pressure by pulsed barrier discharge. Both highly ordered arrays and individual straight and coiled nanotubes can be grown depending on the catalyst used. 

Kerman, K., Morita, Y., Takamura, Y., Tamiya, E. (2005). Escherichia coil single-strand binding protein-DNA interactions on carbon nanotube-modified electrodes from a label-free electrochemical hybridization sensor. Anal Bioanal Chem 381, 1114-1121. 

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