Morphology of dispersed carbon single-walled nanotubes

Schaefer, Dale W.; Zhao, Jian; Brown, Janis M.; Anderson, David P.; Tomlin, D. W.

doi:10.1016/s0009-2614(03)00867-4

Cited by 130 publications

(114 citation statements)

References 19 publications

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“…In attempts to achieve well-dispersed CNTs in a polymer, functionalization of the CNT walls [9,10], use of surfactants [11], controlled duration of sonication of mixtures of CNTs in various solvents [12,13,14,15,16], in situ polymerization under sonication [17], in situ bulk polymerization [18], high speed mechanical stirring [19,20], and compounding using a twin screw extruder [21,22] have been used. The dispersion of the CNTs in the polymer was mainly determined by taking images using transmission electron microscopy (TEM), scanning electron microscopy (SEM), or optical microscopy.…”

Section: Introductionmentioning

confidence: 99%

“…Four different methods using small-angle neutron scattering, near-infrared fluorescence measurement, optical absorption spectroscopy, and resonant Raman scattering were applied to determine the dispersion of DNA-wrapped single-walled carbon nanotubes (SWNT) in poly(acrylic acid) [25]. The morphology of dispersed SWNT was determined by light scattering [12] and the length and the diameter of multi-walled carbon nanotubes (MWNT) suspended in an aqueous solution were determined by analysis of the images taken by field emission gun scanning microscope [15]. The dispersion level of SWNTs in poly(methyl methacrylate) (PMMA) was characterized by producing a Raman map over a 40 μm by 40 μm domain by measuring Raman scattering intensity [13].…”

Section: Introductionmentioning

confidence: 99%

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Relationship between dispersion metric and properties of PMMA/SWNT nanocomposites

Kashiwagi

Fagan

Douglas

et al. 2007

Polymer

169

113

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Particle spatial dispersion is a crucial characteristic of polymer composite materials and this property is recognized as especially important in nanocomposite materials due to the general tendency of nanoparticles to aggregate under processing conditions. We introduce dispersion metrics along with a specified dispersion scale over which material homogeneity is measured and consider how the dispersion metrics correlate quantitatively with the variation of basic nanocomposite properties. We then address the general problem of quantifying nanoparticle spatial dispersion in model nanocomposites of single wall carbon nanotubes (SWNT) dispersed in poly(methyl methacrylate) (PMMA) at a fixed SWNT concentration of 0.5 % using a 'coagulation' fabrication method. Two methods are utilized to measure dispersion, UV-Vis spectroscopy and optical confocal microscopy. Quantitative spatial dispersion levels were obtained through image analysis to obtain a 'relative dispersion index' (RDI) representing the uniformity of the dispersion of SWNTs in the samples and through absorbance. We find that the storage modulus, electrical conductivity, and flammability containing the same amount of SWNTs, the relationships between the quantified dispersion levels and physical properties show about four orders of magnitude variation in storage modulus, almost eight orders of magnitude variation in electric conductivity, and about 70 % reduction in peak mass loss rate at the highest dispersion level used in this study. The observation of such a profound effect of SWNT dispersion indicates the need for objective dispersion metrics for correlating and understanding how the properties of nanocomposites are determined by the concentration, shape and size of the nanotubes. conditions. We introduce dispersion metrics along with a specified dispersion scale over which material homogeneity is measured and consider how the dispersion metrics correlate quantitatively with the variation of basic nanocomposite properties. We then address the general problem of quantifying nanoparticle spatial dispersion in model nanocomposites of single wall carbon nanotubes (SWNT) dispersed in poly(methyl methacrylate) (PMMA) at a fixed SWNT concentration of 0.5 % using a 'coagulation' fabrication method. Two methods are utilized to measure dispersion, UV-Vis spectroscopy and optical confocal microscopy. Quantitative spatial dispersion levels were obtained through image analysis to obtain a 'relative dispersion index ' (RDI) representing the uniformity of the dispersion of SWNTs in the samples and through absorbance. We find that the storage modulus, electrical conductivity, and flammability † This was carried out by the National Institute of Standards and Technology (NIST), an agency of the US Government and is not subject to copyright in the US. ‡ Correspondence to: T. Kashiwagi (E-mail: takashi.kashiwagi@nist.gov) 1 property of the nanocomposites correlates well with the RDI. For the nanocomposites containing the same amount of SWNTs, the relationships betw...

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Relationship between dispersion metric and properties of PMMA/SWNT nanocomposites

Kashiwagi

Fagan

Douglas

et al. 2007

Polymer

169

113

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“…Although various methods have been used to infer or measure these persistence lengths, there is still controversy about whether, in the absence of flow, individual SWCNTs in liquids should be considered rigid (L Ͻ Ͻ L p ) or semiflexible (L Ϸ L p ). A study based on the size of closed SWCNT rings estimated a persistence length of 800 nm (8); experimental data from neutron scattering indicated that SWCNTs behave as rigid rods on length scales of at least Ϸ150 nm (9), and X-ray scattering data suggested that SWCNTs do not display rod-like behavior at any length (10). Fluorescence video microscopy studies of fluorescently labeled SWCNTs deduced persistence lengths ranging between 32 and 174 m (11), although this method could not distinguish between individual SWCNTs and small bundles.…”

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confidence: 99%

Diameter-dependent bending dynamics of single-walled carbon nanotubes in liquids

Fakhri¹,

Tsyboulski

Cognet

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

143

132

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By relating nanotechnology to soft condensed matter, understanding the mechanics and dynamics of single-walled carbon nanotubes (SWCNTs) in fluids is crucial for both fundamental and applied science. Here, we study the Brownian bending dynamics of individual chirality-assigned SWCNTs in water by fluorescence microscopy. The bending stiffness scales as the cube of the nanotube diameter and the shape relaxation times agree with the semiflexible chain model. This suggests that SWCNTs may be the archetypal semiflexible filaments, highly suited to act as nanoprobes in complex fluids or biological systems.actin ͉ microrheology ͉ semiflexible filaments and polymers ͉ stochastic dynamics ͉ nanomechanics

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“…D = 1 implies a linear objects and D > 1 indicates more branched or flexible structures. (Schaefer, Brown et al 2003;Schaefer, Zhao et al 2003) For our data, however, the scattering entities are polydisperse and the power-law regions extend over a very limited q range, so this approach is unworkable. An alternative is to use the relationship…”

Section: Light Scattering Investigationmentioning

confidence: 97%

“…Such a slope, however, can also arise from more complex aggregated structures. (Schaefer, Brown et al 2003;Schaefer, Zhao et al 2003) The crossover length scale (q -1 ≅ 1 μm) between the two power-law regimes corresponds to the largest radius of the tube aggregates. Minimal change in Rg and P is observed for q > 10 -4 Å -1 , indicating minimal change in morphology with time on length scales below ~1 μm.…”

Section: Light Scattering Investigationmentioning

confidence: 99%