Nondestructive and High-Recovery-Yield Purification of Single-Walled Carbon Nanotubes by Chemical Functionalization

Abstract

Raw single-walled carbon nanotubes produced by arc discharge were first treated with K 2 S 2 O 8 in dilute H 2 -SO 4 solution to generate oxygenated functional groups such as carboxyl, hydroxyl, and carbonyl on varying carbon components. Further functionalization with octadecylamine was carried out via a condensation reaction between an amine group and a carboxyl group with the assistance of dicyclohexylcarbodiimide. The attachment of long alkyl chains leads the sample to be soluble in tetrahydrofuran and other organic solvents. The thus obtained stable dispersion was subjected to dispersion-centrifugation recycles, and then the metal catalysts and varying carbon impurities were separated with carbon nanotubes. The advantage of this procedure lies in high-yield and nondestructive recovery of the target material. Optical absorption spectroscopic and thermogravimetric analyses show that about 60% of the nanotubes in the starting material is extracted with a purity more than 90 wt %.

Mild hydrothermal treatment to prepare highly dispersed multi-walled carbon nanotubes

“…5-7 and Nos. [8][9][10][11] with different KPS concentration, KOH concentration and reaction time, respectively).…”

“…The poor chemical compatibility greatly hinders their solution phase manipulation and processability. Extensive researches have thus focused on the MWCNT modification to provide homogeneous dispersion of MWCNTs in various solutions [7][8][9][10][11][12][13], mainly in term of severe oxidation treatments (H 2 SO 4 [10], HNO 3 [11,12] or KMnO 4 [13]) that allow the introduction of carboxyl and hydroxyl groups to MWCNT surface. In general, these approaches unavoidably break carbon nanotubes into short fragments and even change their inherent morphology owing to oxidative conditions.…”

One-step preparation of water-soluble single-walled carbon nanotubes

“…KPS is previously used as a common initiator for emulsion polymerization [21,22], and also an important role as oxidant in organic chemistry [23,24]. This one-step method without the need for organic solvents and acids may be considered as a low-cost, eco-friendly and convenient method to prepare water-soluble nanotubes.…”

Centrifugal purification of chemically modified single-walled carbon nanotubes

“…The reactants were ground and evenly mixed in a mortar, then were heated to 140 8C and stirred by a magnetic stirrer under Ar atmosphere for a week. After a proper amount of DCC was added, the reaction mixture was further heated at the temperature of w130 8C [26].…”

“…A graphite rod, drilled and filled with powder of graphite and catalyst particles (Ni:Y:C/2:1:10 atomic ratio), is vaporized by an 80 A current under a helium atmosphere of 650 Torr. The sticky cotton-like To account for the difference in tube concentration, the plots were normalized at 1010 nm [26].…”