Effects of Alkyl Amide Solvents on the Dispersion of Single-Wall Carbon Nanotubes

Landi, Brian J.; Ruf, Herbert J.; Worman, James J.; Raffaelle, Ryne P.

doi:10.1021/jp047521j

Cited by 188 publications

(258 citation statements)

References 33 publications

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“…To correct for this, we use the ratio of the resonant extinction coefficients measured below (soluble) and above (aggregated) the intrinsic solubility limit for comparable metallic and semiconducting SWCNTs in alkyl-amide solvents. 39, 43 We are specifically interested in intimate nanotube contact, which is most relevant from the perspective of transparent conductive coatings. In the near-field limit within the Derjaguin approximation, 27 the non-retarded contact potential for two SWCNTs of identical type and diameter 2a depends on surface separation, ℓ, and orientation angle, θ, as…”

Section: Methodsmentioning

confidence: 99%

Empirical evaluation of attractive van der Waals potentials for type-purified single-walled carbon nanotubes

et al. 2012

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Van der Waals forces play a critical role in the structure and stability of single-wall carbon nanotube (SWCNT) materials. Thin films assembled from SWCNTs purified by electronic type show particular promise for flexible electronics applications, but mechanical durability remains an unresolved issue. Using transition resonances determined from spectroscopic measurements of typepurified SWCNTs deposited on quartz, coupled with analogous spectroscopic characterization of polydimethylsiloxane (PDMS) substrates, we use the Lifshitz theory of van der Waals dispersion interactions developed by Rajter and co-workers [R. F. Rajter et. al., Phys. Rev. B 76, 045417 (2007)] to examine the influence of electronic type on van der Waals contact potentials in polymer supported nanotube networks. Our results suggest a significantly stronger nanotube-nanotube and nanotube-polymer attraction for the semiconducting SWCNT fractions, consistent with recent measurements of the electronic durability of flexible transparent SWCNT coatings.PACS numbers: 61.48. De, 78.67.Ch, 82.35.Np, 78.20.Bh 2 I. INTRODUCTIONVan der Waals (vdW) forces play a significant role in the structural stability of matter across a broad range of chemistry, physics, and biology. 1-6 They also play a particularly important role in nanotechnology, where they dominate the short-range attraction between nanoparticles and can hinder their dispersion and manipulation. [7][8][9][10][11] For particles lacking a permanent dipole moment, vdW dispersion forces arise solely from small fluctuations in the electromagnetic field -or more precisely, the dielectric permittivity -across the space between the particles, 12,13 which is dominated by the zero-point energy of quantum vacuum fluctuations. The quantum-field nature of such a mundane, ubiquitous and sometimes macroscopic force is quite remarkable, if on occasion not fully appreciated.Single-wall carbon nanotubes (SWCNTs) are nanometer thick tubes of graphene 100 nm to 100 µm in length. They can be either metallic or semiconducting, depending on the chiral vector (n, m) that characterizes the symmetry of rolling a 2D graphene sheet into a hollow tube. 14 They are one of the most studied materials within the realm of modern nanotechnology, with exceptional physical properties that herald the possibility of significant technological potential. 15 The importance of vdW forces in SWCNT materials cannot be overstated. The high aspect ratio and strong anisotropy create potential wells thousands of k B T in depth, but SWCNTs have yet to realize their full potential as mechanical reinforcing agents. This is primarily due to the mechanical failure of interfacial contacts, which are largely governed by vdW forces. Although chemical crosslinking can help mitigate such effects, this often occurs at the expense of the intrinsic SWCNT properties of interest, 16 which can limit the potential impact of applications.Raw nanotube materials typically contain a broad distribution of lengths and a mixture of the two distinct electronic species...

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Section: Methodsmentioning

confidence: 99%

Empirical evaluation of attractive van der Waals potentials for type-purified single-walled carbon nanotubes

et al. 2012

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“…In recent years a number of papers have appeared describing the preparation of stable suspensions of single walled nanotubes (SWNTs) in a range of common solvents [16,17,[21][22][23][53][54][55] . In 1999 Liu et al showed that individual SWNT could be deposited from N,N-dimethylformamide (DMF) dispersions [54] .…”

Section: Dispersion and Exfoliation Of Nanotubes In Solventsmentioning

confidence: 99%

“…Various methods to provide this repulsive potential have been explored. Nanotubes have been dispersed and stabilised with the aid of specific solvents [16][17][18][19][20][21][22][23][24] , acids [25,26] , macromolecules [27][28][29][30] and surfactants [31][32][33][34] as well as through covalent functionalisation strategies [35,36] . Such systems have been characterised by a range of techniques such as atomic force microscopy [37] , infra-red photoluminescence and absorbance spectroscopy [34] , viscometry [25] , small angle neutron scattering [32] to name but a few.…”

Section: Introductionmentioning

confidence: 99%

Liquid‐Phase Exfoliation of Nanotubes and Graphene

Coleman

2009

Adv Funct Materials

592

536

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Many applications of carbon nanotubes require the exfoliation of the nanotubes to give individual tubes in the liquid phase. This requires the dispersion, exfoliation and stabilisation of nanotubes in a variety of liquids. In this paper we review recent work in this area, focusing on results from the author's group. We begin by reviewing stabilisation mechanisms before exploring research into the exfoliation of nanotubes in solvents, by using surfactants or biomolecules and by covalent attachment of molecules.The concentration dependence of the degree of exfoliation in each case will be highlighted. In addition we will discuss research into the dispersion mechanism for each dispersant type. Most importantly we have compared dispersion quality metrics for all dispersants. From this analysis, we conclude that functionalised nanotubes can be exfoliated to the greatest degree. Finally, we review the extension of this work to the liquid phase exfoliation of graphite to give graphene.

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“…We show that the process can be improved to give yields of 12% with sediment recycling of the starting graphite mass. As a solution phase method, it is versatile and up-scalable and can be used to deposit graphene in a variety of environments and substrates not available using cleavage or growth methods.Furthermore, it can be used to produce graphene based composites or films, a key requirement for many applications, such as thin film transistors, conductive transparent electrodes for Indium Tin Oxide (ITO) replacement or for photovoltaics.Recently, carbon nanotubes have been successfully exfoliated in a small number of solvents such N-methylpyrrolidone (NMP) [21][22][23] . Such exfoliation occurs because the strong interaction between solvent and nanotube sidewall means that the energetic penalty for exfoliation and subsequent solvation becomes small [22][23][24] .…”

mentioning

confidence: 99%

“…Such exfoliation occurs because the strong interaction between solvent and nanotube sidewall means that the energetic penalty for exfoliation and subsequent solvation becomes small [22][23][24] . We suggest that similar effects may occur between these solvents and graphene.…”

mentioning

confidence: 99%

High-yield production of graphene by liquid-phase exfoliation of graphite

et al. 2008

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Graphene is at the centre of nanotechnology research. In order to fully exploit its outstanding properties, a mass production method is necessary. Two main routes are possible: large-scale growth or large-scale exfoliation. Here, we demonstrate graphene dispersions with concentrations up to ~0.01 mg/ml by dispersion and exfoliation of graphite in organic solvents such as N-methylpyrrolidone. This occurs because the energy required to exfoliate graphene is balanced by the solvent-graphene interaction for solvents whose surface energy matches that of graphene. We confirm the presence of individual graphene sheets with yields of up to 12% by mass, using absorption spectroscopy, transmission electron microscopy and electron diffraction. The absence of defects or oxides is confirmed by X-ray photoelectron, infra-red and Raman spectroscopies. We can produce conductive, semi-transparent films and conductive composites. Solution processing of graphene opens up a whole range of potential large-scale applications from device or sensor fabrication to liquid phase chemistry. Hernandez et al 2Graphene is one of the most exciting nano-materials due to the cascade of unique physical properties that have recently been demonstrated. For example, due to the details of its electronic structure, charge carriers in graphene behave as massless Dirac fermions 1 . Furthermore, novel effects such as an ambipolar field effect 2 , room temperature quantum Hall effect 3 , breakdown of the Born-Oppenheimer approximation 4 are observed. However, as was the case in the early days of nanotube and nanowire research, graphene at present still suffers from one problem, critical for its mass-scale exploitation: it cannot yet be made with high yield. The standard procedure used to make graphene is micromechanical cleavage 5 . This yields the best samples to date, with mobilities up to 200,000 cm 2 /Vs. 6 However, single layers are a negligible fraction amongst large quantities of thin graphite flakes. Furthermore, it is difficult to see how to scale up this process to mass production. Alternatively, growth of graphene is also commonly achieved by annealing SiC substrates, but these samples are in fact composed of a multitude of domains, most of them sub-micrometer, and not spatially uniform in number, or in size over larger length scales 7 . A number of works have also reported graphene growth on metal substrates 8,9 , but this would require the sample transfer to insulating substrates in order to make useful devices, either via mechanical transfer or, via solution processing.Recently, a large number of papers have described the dispersion and exfoliation of graphene oxide (GO) [10][11][12][13] . This material consists of graphene-like sheets, chemically functionalised with compounds such as hydroxyls and epoxides, which stabilise the sheets in water 14 . However, this functionalisation results in considerable disruption of the electronic structure of the graphene. In fact GO is an insulator 15 rather than a semi-metal and is conceptually differen...

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Effects of Alkyl Amide Solvents on the Dispersion of Single-Wall Carbon Nanotubes

Cited by 188 publications

References 33 publications

Empirical evaluation of attractive van der Waals potentials for type-purified single-walled carbon nanotubes

Empirical evaluation of attractive van der Waals potentials for type-purified single-walled carbon nanotubes

Liquid‐Phase Exfoliation of Nanotubes and Graphene

High-yield production of graphene by liquid-phase exfoliation of graphite

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