Carbolex CNTs

Nevertheless, these features could not be observed in the UV-Vis spectra of Carbolex CNTs, not even at the end of the debundling, whereas these van Hove singularities could be observed for the debundling of the same type of CNTs in sulfuric acid. Vaccarini et al. showed that the absorption peak width does not necessarily exclusively correlate with the level of debundling, and the interaction between the CNT and the dispersion medium can have a noticeable effect on the peak width. It can thus be conjectured that Carbolex and H iPCO CNTs might not have the same interaction with SDS molecules adsorbed on their walls. 

The same Carbolex and HiPCO SWCNT dispersions as those previously studied in Section 3.1.2 were examined with UV-Vis spectroscopy. Samples were taken regularly during the sonicating process, diluted and UV-Vis spectra were recorded. Since desorption processes are typically quite slow, it was assumed that the amount of SDS molecules adsorbed on the CNT walls was not significantly influenced by dilution, and UV-Vis spectra were typically immediately recorded after dilution. " Please note that the dilution factor — in other words, the CNT concentration after dilution [i.e., 6.7 x 10 wt% for the standard SWCNT dispersions) — was chosen in such a way that all the UV-Vis absorbance values remained below 1 so that the error inherently present in the measurement itself is reduced. At this dilution, the contribution of scattering can be ignored. " ... 

The UV-Vis spectra recorded for aqueous HiPCO SWCNT dispersions, obtained after different energy-inputs and sonication times, are given in Figure 3.4. The corresponding spectra for Carbolex SWCNTs show a similar development, but exhibit one maximum instead of two around 250-300 nm. This difference indicates that the UV-Vis spectra obtained are specific for the CNT type studied. This is not surprising since the Carbolex and HiPCO CNTs studied... 

It appears that all the CNT dispersions [of SDS-HiPCO SWCNTs, SDS-Carbolex SWCNTs, and SDS-MWCNTs (thin MWCNTs of the batches MWA P041206 and 060213 provided by Nanocyl SA]] presented in this chapter are stable for at least several months, if not years, since the value of the UV-Vis absorbance of these dispersions remained virtually constant during this period. ... 

For the range of SWCNT concentrations studied by Grossiord et al. (below 0.5 wt% for HiPCO CNTs and below 1 wt% for Carbolex... 

The nature and the quantity of impurities removed are strongly connected to the surfactant type, as well as to the CNT type and batch (notably their density and the homogeneity of the batch). In order to Illustrate this last point, SDS-Carbolex SWCNT and SDS-HiPCO SWCNT dispersions were exfoliated and subsequently centrifuged at... 

Raman spectroscopy is often used to assess the quality of CNTs. -A typical Raman spectrum of a CNT mat or dispersion shows a few characteristic bands. These include the "graphene-like or G-band observed between 1,500 and 1,600 cm , the "disorder-induced or D-band observed at 1,300 cm , and the radial breathing mode [RBM] observed between 100 and 500 cm . A comparison between the G-and D-bands from two samples has been reported to indicate their relative purity.Raman spectra taken for SDS-stabilized dispersions of HiPCO and Carbolex SWCNTs are given in Figure 6.13. 

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