HiPCO SWCNTs

HiPCO-SWCNTs were oxidized in a UV-03 gas-solid interface reaction and subsequently assembled on a rigid oligo(phenylenethynylene) self-assembled monolayer (SAM). In a chemical assembly , based on condensation between the carboxylic acid functionalities of the 03-oxidized SWNTs and the amine functionalities of the SAMs, SWCNT-amides were formed in ordered arrays [116]. 

Carbon Nanotubes. An FT Raman band at 146 cm-1 was assigned as a radial breathing mode for bundles of SWCNT with a tube diameter of 1.53 nm.215 Oxidation of HipCO SWCNT (diameter 8-10 A) leads to irreversible disappearance of Raman breathing modes below 220 cm-1, in the temperature range 150 400 C.216 The Raman spectra of SWCNT produced by plasma-enhanced CVD gave evidence for the formation of single tubes at quite low temperatures (ca. 550°C).217... 

In the same line, high-Pressure carbon monoxide (HiPco) SWCNTs were functionalized along their sidewalls with hydroxyalkyl groups using a radical addition scheme.These moieties were found to be active in the polymerization of acrylic acid from the surface of the nanotubes by a redox radical mechanism. In Figure 9.4 (left-hand panel) the Raman response of pristine, ethanol-treated and polymer-modified samples is illustrated. Compared with... 

Blocky VA/AA copolymer (Fig. 4.6.5) was sonicated with high-pressure carbon monoxide based single-walled carbon nanombes (HiPco SWCNT) in THF (Caneba... 

Surface resistivity performance tests were done for the HiPco SWCNT that was dispersed with blocky VA/AA material at 1 1 VA/AA/HiPco wt/wt ratio. Results indicate that proper dispersion maintained electrical properties of HiPco, because surface resistivities range from 2.17 to 3.50 k Ohms/sq from HiPco loadings of 0.059-0.557 mg/cm (Caneba and Axland, 2004). Note that electrically conductive surfaces require surface resistivities below 100 k-Ohm/sq. 

Figure 2.12 Aqueous SDS solution of HiPCO SWCNTs after 130 minutes of sonication at 20W, corresponding to a total energy input of ca. 150,000 J. (Mostly individual CNTs are observed. From Ref. 102. Reprinted with permission of the American Chemical Society)...

Figure 3.3 SEM image of an aqueous solution of HiPCO SWCNTs after deposition on a Si wafer of which the surface had been chemically modified (a) after 10 min of sonication at 20 W (b) after 30 min of sonication, and (c) after 100 min of sonication at 20 W, Scale bar 2 qm (same one for the first three photos), (d) Magnified view of one part of Figure 3.3c. Scale bar 1 pm.

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... 

Figure 3.5 Evolution ofthevalueoftheabsorbanceatdifferentwavelengths for an aqueous 0.5 wt% HiPCO SWCNT solution, containing 1 wt% of SDS, diluted 750 times.

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. ... 

Consequently, stopping the sonication when the maximum amount of exfoliable CNTs has been unbundled [e.g., at 100,000 J for HiPCO SWCNTs] should prevent further cutting of the SWCNTs, though SWCNT surface damage may not be particularly minimized. 

Firstly it was found that, contrary to treatments based on nitric acid, this mild HCl-based purification did not seem to significantly oxidize the surface of the CNT walls, as shown by the comparison of the IR spectra of purified and non-purified CNTs. Secondly, the results of TGA measurements clearly pointed out that the efficiency of the purification was batch-dependent in terms of relative percentage of iron particle removal. The HIPCO SWCNTs of a batch containing a... 

The purified CNTs were exfoliated by sonication. Grossiord et al. followed this process by UV-Vis spectroscopy, and compared this individualization with the exfoliation of non-purified CNTs. The results are plotted in Figures 3.13 and 3.14 for two HiPCO SWCNT... 

Noii-purified HiPCO SWCNTs O Purified SWCNTs, exfoliation 1 Purified SWCNTs, exfoliation 2... 

These two experimental observations point out that the purified CNTs are more bundled at the end of the exfoliation than the as-produced CNTs. This was confirmed by SEM images of the purified HiPCO SWCNTs of the high quality batch, which showed that these... 

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