scholarly journals Mesoscale modeling of mechanics of carbon nanotubes: Self-assembly, self-folding, and fracture

2006 ◽  
Vol 21 (11) ◽  
pp. 2855-2869 ◽  
Author(s):  
Markus J. Buehler

Using concepts of hierarchical multiscale modeling, we report development of a mesoscopic model for single-wall carbon nanotubes with parameters completely derived from full atomistic simulations. The parameters in the mesoscopic model are fit to reproduce elastic, fracture, and adhesion properties of carbon nanotubes, in this article demonstrated for (5,5) carbon nanotubes. The mesoscale model enables modeling of the dynamics of systems with hundreds of ultralong carbon nanotubes over time scales approaching microseconds. We apply our mesoscopic model to study self-assembly processes, including self-folding, bundle formation, as well as the response of bundles of carbon nanotubes to severe mechanical stimulation under compression, bending, and tension. Our results with mesoscale modeling corroborate earlier results, suggesting a novel self-folding mechanism, leading to creation of racket-shaped carbon nanotube structures, provided that the aspect ratio of the carbon nanotube is sufficiently large. We find that the persistence length of the (5,5) carbon nanotube is on the order of a few micrometers in the temperature regime from 300 to 1000 K.

2003 ◽  
Vol 772 ◽  
Author(s):  
Emmanuel Valentin ◽  
Stephane Auvray ◽  
Arianna Filoramo ◽  
Aline Ribayrol ◽  
Marcelo Goffman ◽  
...  

AbstractWe describe the realization of high quality self-assembled single wall carbon nanotube field effect transistors (CNTFET). A method using self-assembled monolayers (SAMs) is used to obtain high yield selective deposition placement of single wall carbon nanotubes (SWNTs) on predefined regions of a substrate. This is achieved with individual or small bundles of SWNTs and with high densities suitable for fabrication of integrated devices. We show that such positioned SWNTs can be electrically contacted to realize high performance transistors, which very well compare with state-of-the-art CNTFETs. We therefore validate the self-assembly approach to reliably fabricate efficient carbon nanotube based devices.


2018 ◽  
Vol 13 (7-8) ◽  
pp. 349-355 ◽  
Author(s):  
D. K. Shishkova ◽  
Yu. I. Khodyrevskaya ◽  
A. G. Kutikhin ◽  
M. S. Rybakov ◽  
R. A. Mukhamadiyarov ◽  
...  

Author(s):  
Francisco Torrens ◽  
Gloria Castellano

This paper discusses the existence of single-wall carbon nanocones (SWNCs), especially nanohorns (SWNHs), in organic solvents in the form of clusters. A theory is developed based on a bundlet model describing their distribution function by size. Phenomena have a unified explanation in bundlet model in which free energy of an SWNC, involved in a cluster, is combined from two components: a volume one, proportional to number of molecules n in a cluster, and a surface one proportional to n1/2. Bundlet model enables describing distribution function of SWNC clusters by size. From purely geometrical differences, bundlet (SWNCs) and droplet (fullerene) models predict different behaviours. The SWNCs of various disclinations are investigated via energetic–structural analyses. Several SWNC’s terminations are studied, which are different among one another because of type of closing structure and arrangement. The packing efficiencies and interaction-energy parameters of SWNCs/SWNHs are intermediate between fullerene and single-wall carbon nanotube (SWNT) clusters; an in-between behaviour is expected. However, the properties of SWNCs, especially SWNHs, are calculated close to SWNTs. The structural asymmetry in the different SWNCs, entirely characterized by their cone angle, distinguishes the properties of some, such as P2.


RSC Advances ◽  
2015 ◽  
Vol 5 (125) ◽  
pp. 103365-103372 ◽  
Author(s):  
Lei Liu ◽  
Dong Wang ◽  
Yuan Hu

Negative graphene oxide was combined with positive chitosan-modified multi-walled carbon nanotubes in aqueous solution and then thermally reduced to fabricate a multi-walled carbon nanotube/graphene (MWCNT/G) hybrid material.


2004 ◽  
Vol 855 ◽  
Author(s):  
S. Gupta ◽  
M. Hughes ◽  
J. Robertson

ABSTRACTElectrochemical tuning of single-wall carbon nanotubes has been investigated using in situ Raman spectroscopy. We built a linear actuator from single-wall carbon nanotube mat and studied in several alkali metal (Li, Na, and K) and alkaline earth (Ca) halide solutions. The variation of bonding with electrochemical biasing was monitored using in situ Raman. This is since Raman can detect changes in C-C bond length: the radial breathing mode (RBM) at ∼190 cm−1 varies inversely with the nanotube diameter and the G band at ∼1590 cm−1 varies with the axial bond length. In addition, the intensities of both the modes vary significantly in a nonmonotonic manner pointing at the emptying/depleting or filling of the bonding and anti-bonding states - electrochemical charge injection. We discuss the variation of spectroscopic observables (intensity/frequency) of these modes providing valuable information on the charge transfer dynamics on the single-wall carbon nanotubes mat surface. We found the in-plane compressive strain (∼ -0.25%) and the charge transfer per carbon atom (fc ∼ -0.005) as an upper bound for the electrolytes used i.e. CaCl2. These results can be quantitatively understood in terms of the changes in the energy gaps between the one-dimensional van Hove singularities in the electron density of states arising possibly due to the alterations in the overlap integral of π bonds between the p orbitals of the adjacent carbon atoms. Moreover, the extent of variation of the absolute potential of the Fermi level or alternatively modification of band gap is estimated from modeling Raman intensity to be around 0.1 eV as an upper bound for CaCl2.


2015 ◽  
Vol 3 (10) ◽  
pp. 2319-2325 ◽  
Author(s):  
Sehee Ahn ◽  
Ayoung Choe ◽  
Jonghwa Park ◽  
Heesuk Kim ◽  
Jeong Gon Son ◽  
...  

Directed self-assembly of carbon nanotubes into 2D rhombic nanomesh films results in greatly lower sheet resistance, higher stretchability, and better mechanical durability than those of random carbon nanotube films.


2012 ◽  
Vol 7 (1) ◽  
pp. 29-34
Author(s):  
N. R. Arutyunyan ◽  
A. I. Chernov ◽  
K. M. Kuznetsov ◽  
E. D. Obraztsova

2009 ◽  
Vol 1204 ◽  
Author(s):  
Letian Lin ◽  
Lu-Chang Qin ◽  
Sean Washburn ◽  
Scott Paulson

AbstractThe properties of a carbon nanotube (CNT), in particular a single-wall carbon nanotube (SWNT), are highly sensitive to the atomic structure of the nanotube described by its chirality (chiral indices). We have grown isolated SWNTs on a silicon substrate using chemical vapor deposition (CVD) and patterned sub-micron probes using electron beam lithography. The SWNT was exposed by etching the underlying substrate for transmission electron microscope (TEM) imaging and diffraction studies. For each individual SWNT, its electrical resistance was measured by the four-probe method at room temperature and the chiral indices of the same SWNT were determined by nano-beam electron diffraction. The contact resistances were reduced by annealing to typically 3-5 kΩ. We have measured the I-V curve and determined the chiral indices of each nanotube individually from four SWNTs selected randomly – two are metallic and two are semiconducting. We will present the electrical resistances in correlation with the carbon nanotube diameter as well as the band gap calculated from the determined chiral indices for the semiconducting carbon nanotubes. These experimental results are also discussed in connection with theoretical estimations.


2007 ◽  
Vol 121-123 ◽  
pp. 631-636
Author(s):  
T. Li ◽  
X.B. Zhang ◽  
Y. Li ◽  
W.Z. Huang ◽  
X.Y. Tao ◽  
...  

Single-wall Carbon nanotubes (SWNTs) bonded with dodecylamine groups were obtained by chemical modification. The modified SWNTs showed improved solubility in organic solvents. Both its chemical and aggregated structure was characterized by means of FTIR and TEM. The photoconductivity of oxotitanium phthalocyanine (TiOPc) doped with the modified SWNTs was investigated by xerographic photoinduced discharge method. The results showed that the photosensitivity of the double-layered photoreceptor composed of the SWNTs/TiOPc composite as charge generation material was higher than that of pristine TiOPc, and the sensitivity increased with the content of modified SWNTs in the composites. It is the photoinduced charge transfer between TiOPc and SWNTs that contributes to the improved photosensitivity of the modified SWNTs/TiOPc composites.


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