Shortened SWNT

SWNTs (HiPco, Carbon Nanotechnologies Incorporated) were shortened by ultrasonication with a probe-type sonicator in mixed acids (H2SO4 and HNO3) under ice-cooling. After diluting the mixture with water (MiliQ), the shortened SWNTs were purified by filtration through a PTFE membrane filter (pore size 1 pm or 0.2 pm) or by chromatography (Sepadex G-50). 

The SWNT/MEHPPV composites were prepared by the following procedure. The shortened SWNTs were added to a DMF solution of MEHPPV. The suspension was then sonicated with a bath-type sonicator. Centrifugation (6000 rpm) of the suspension for 15 min gave a DMF solution of the SWNT/MEHPPV composite. 

The formation of SWNT/MEHPPV composites was confirmed by absorption and fluorescence spectra. The DMF solution of SWNT/MEHPPV composites or the aqueous solution of the shortened SWNTs was then dropped onto a mica or glass plate. The magnetic processing of the composites or the SWNTs was carried out by using a superconducting magnet (8T) in the horizontal direction, as described below. 

The above results of polarized absorption spectra on glass plates support the magnetic orientation ofthe SWNT/MEHPPV composites and the shortened SWNTs in the absence and presence of NaHC03, where the composites or the SWNTs were oriented with the tube axis of the composites or the SWNTs parallel to the magnetic field (8T), suggested by the results ofthe AFM images (Figure 15.1). 

To produce soluble SWNTs, an octadecylarmnonium (ODA) and SWNT-car-boxylate zwitter ion was produced by the following proceditre. Shortened SWNTs... 

FIGURE 13.7 Preparation and characterization of single-walled nanotube (SWNT) forest formed by metal-assisted deposition of oxidized, shortened SWNTs. (a) Schematic representation of SWNT forest preparation. Shortened, open-ended SWNTs with carboxyl-functionalized ends are produced by oxidation of SWNTs. A suspension of SWNTs is introduced to a metal surface functionalized with iron hydroxides. An SWNT forest results as SWNTs vertically align via self-assembly. (Part a adapted with permission from Chattopadhyay, D., Galeska, I., and Papadimitrakopoulos, F., Metal-assisted organization of shortened carbon nanotubes in monolayer and multilayer forest assemblies, J. Am. Chem. Soc., 123,9451-9452,2001. Copyright 2001 American Chemical Society.) Cyclic voltammograms (scan rate 300 mV s ) of (b) SWNT forest electrodes in pH 5.5 buffer with and without 0.2 mM HjOj. (Continued)... 

After HiPco SWNTs were ground in the presence of fi-CD 57 or y-CD 58 (Fig. 18), the resulting black powder was found to contain shortened SWNTs and could be dissolved in water [200]. HiPco SWNTs were also dissolved in water by refluxing them in the aqueous y-CD solution [201] in a similar procedure to that for preparing y-CD-Ceo complex [184,187]. The SWNTs non-covalently functionalized with y-CD by means of grinding and refluxing were analyzed with absorption and Raman spectroscopies, and differential scan-... 

Scheme 12.7 Functionalization of shortened SWNTs with ATRP initiators and the ATRP of MMA.

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