HiPCO SWCNTs purified

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... 

Du ct al. 2003 SWCNT HiPco Purified SWCNT Coagulation Unaligned Elastic Percolation Increased ther- Increased... 

PAne (PANi, SFST, 280 000 g/mol), DCAd (DCAA, Merck, 9 %) and 2-acrylamido-2-methyl-l-propane sulfonic acid (AMPSA, Aldrich, 9 %) were all used without arty further purification. Purified SWCNT (SWNTs, Hipco CNI) were used as pirrchased and contained 5 w % iron residue as determined by elemental analysis. 

Purified HiPCO Rice University, SWCNT as-received... 

FIGURE 16.2 (a) Optical absorption spectrum of an SWCNT sample with an average diameter of 1.3 run. The inset shows the same spectrnm after subtraction of the surface Jt-plasmon. (Adapted from Liu, X. et al., Phys. Rev. B Condens. Matter, 66,045411, 2002.) (b) Absorption spectra of films of pnrified HiPCO, purified laser, and soluble Arc produced SWCNTs after baseline correction. The inset shows the corresponding interband transitions in the DOS diagram showing van Hove singularities and the levels/bands involved. (Adapted from Hamon, M.A. et al., J. Am. Chem. Soc., 123, 11292, 2001.)... 

A variant, the so-called "coagulation method," is based on the difference in swellability of polymers in a good and in a poor solvent. In a sonication bath, purified SWCNTs, produced by a HiPCO process, were first purified by an acidic HCl treatment, which led to the obtaining of a CNT sample containing less than 8 wt% of metal residue, and subsequently mixed with the polymer (poly(methyl... 

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