Forms Of Single-walled Carbon Nanotubes Research Articles

Binder-free, pre-consolidated single-walled carbon nanotubes for manufacturing thermoset nanocomposites

In this work, we propose a pre-consolidated form of single-walled carbon nanotubes (SWCNT) – SWCNT briquettes – as a binder-free, robust, and safe material for manufacturing electrically and thermally conductive thermoset nanocomposites with universal applicability to all polymer matrices. We prove that the briquettes provide similar performance in nanocomposites compared to reference samples: a pristine powder, a commercial masterbatch and an aerogel based on the same type of SWCNTs. Using comprehensive sets of methods, we observe no significant differences in electrical (∼10−7-1 S/cm depending on SWCNT loading) and thermal (0.210–0.304 W/mK) conductivities for all sample types across a wide range of SWCNT concentrations. Moreover, the percolation thresholds of nanocomposites for SWCNT briquettes were ultra-low and close to that of pre-dispersed masterbatches (0.001–0.003 wt%). Pre-consolidated SWCNT powder is shown to provide the same final functional properties, while being free from common nanotube drawbacks such as the higher price of masterbatch manufacturing or aerosolization and low dispersibility during handling for the SWCNT powder/aerogel. The briquettes not only offer a safe solution for large scale fabrication, cutting away the need for personal and facility level safety measures, but do so at no significant cost increase, can be used with any polymer matrix and associated industrial processing route without any loss of final properties. This makes them universally attractive for all composite industrial production as well as small scale low capital laboratories.

Effect of power law index for vibration of armchair and zigzag single walled carbon nanotubes

This research deals with the study of vibrational behavior of armchair and zigzag single-walled carbon nanotubes invoking extended Love shell theory. The effects of different physical and material parameters on the fundamental frequencies are investigated. By using volume fraction for power law index, the fundamental natural frequency spectra for two forms of single-walled carbon nanotubes are calculated. The influence of frequencies against length-to-diameter ratios with varying power law index are investigated in detail for these tubes. To discretize the governing equation in eigen-value form, wave propagation approach is developed. Complex exponential functions have been used and the axial model depends on boundary condition that has been described at the edges of carbon nanotubes to calculate the axial modal dependence. Computer software MATLAB is utilized for the frequencies of single-walled carbon nanotubes and current results shows a good stability with comparison of other studies.

Application of Kelvin's approach for material structure of CNT: Polynomial volume fraction law

In this piece of work, carbon nanotubes motion equations are framed by Kelvin’s method. Employment of the Kelvin’s method procedure gives birth to the tube frequency equation. It is also exhibited that the effect of frequencies is investigated by varying the different index of polynomial function. By using volume fraction for power law index, the fundamental natural frequency spectra for two forms of single-walled carbon nanotubes are calculated. The influence of frequencies against length-to-diameter ratios with varying power law index are investigated in detail for these tubes. Throughout the computation, it is observed that the frequency behavior for the boundary conditions follow as; clamped-clamped, simply supported-simply supported and these frequency curves are higher than that of clamped-free curves. Computer software MATLAB is utilized for the frequencies of single-walled carbon nanotubes.

Nanomedicine: Going small to beat the high.

Aggregated form of single-walled carbon nanotubes can inhibit the neurochemical and behavioural effects induced by methamphetamine, offering a potential treatment for drug addiction and abuse.

Recent progresses on the new condensed forms of single-walled carbon nanotubes and energy-harvesting devices

We demonstrate an effective method to prepare a new condensed form of single-walled carbon nanotubes (crystal of SWNTs) using a series of diamond wire drawing dies. X-ray diffraction indicates that the SWNTs form a two-dimensional triangular lattice with a lattice constant of 19.62 Å. An intertube spacing of 3.39 Å of between adjacent SWNTs results in a sharp (002) reflection in the X-ray diffraction pattern. Meanwhile, we developed an approach based on the Coulomb explosion to separate SWNTs from their bundle. The separated SWNTs have a typical length of several microns and form a nanotree at one end of the original bundle. The separation is convenient and involves no surfactant. In studying devices comprising SWNTs, we find that a four-probe technique can be employed to study the filling of and flow within the inner channel of an individual SWNT. Current/voltage can drive water molecules to have directional flow along an SWNT, and the flowing of water inside an SWNT can induce a voltage gradient force (an induced electromotive force) along the SWNT. This energy conversion is realized by the mutual coupling of water dipoles and charge carriers present in SWNTs. The results suggest that SWNTs can be exploited as molecular channels for water and may find potential application in nanoscale energy conversion. Moreover, a surface-energy generator comprising SWNTs was demonstrated to harvest the surface energy of ethanol. The performance (the induction rate for V oc, the value of V oc and the output power) can be significantly enhanced by the Marangoni effect.

In vitro cytotoxicity of single‐walled carbon nanotube/biodegradable polymer nanocomposites

Injectable nanocomposites made of biodegradable poly(propylene fumarate) and the crosslinking agent propylene fumarate-diacrylate as well as each of three forms of single-walled carbon nanotubes (SWNTs) were evaluated for their in vitro cytotoxicity. Unreacted components, crosslinked networks, and degradation products of the nanocomposites were investigated for their effects on cell viability using a fibroblast cell line in vitro. The results did not reveal any in vitro cytotoxicity for purified SWNTs, SWNTs functionalized with 4-tert-butylphenylene, and ultra-short SWNTs at 1- 100 microg/mL concentrations. Moreover, nearly 100% cell viability was observed on all crosslinked nanocomposites and cell attachment on their surfaces was comparable with that on tissue culture polystyrene. The degradation products of the nanocomposites displayed a dose-dependent adverse effect on cells, which was partially due to increased osmolarity by the conditions of accelerated degradation and could be overcome at diluted concentrations. These results demonstrate that all three tested nanocomposites have favorable cytocompatibility for potential use as scaffolds for bone tissue engineering applications.

Controlling the growth of vertically oriented single-walled carbon nanotubes by varying the density of Co [sbnd]Mo catalyst particles

A simple method to grow vertically aligned arrays of various forms of single-walled carbon nanotubes (V-SWNT) is reported. CO disproportionation on Co Mo bimetallic catalysts has been used in the synthesis. Resonant Raman and transmission electron microscope (TEM) were employed to characterize the as-produced SWNTs, which display a high purity and very low concentration of other carbon forms. Combination of AFM and SEM gives evidence for the crucial role of the surface distribution of the bimetallic (Co/Mo) catalyst particles on the substrate during the growth of SWNT. A novel growth mechanism is discussed.