Preparation of water-soluble carbon nanotubes using a pulsed streamer discharge in water

Abstract

A novel technique for the preparation of water-soluble carbon nanotubes was demonstrated using a pulsed streamer discharge generated in water. The technique involved chemical reactions between radicals generated by the pulsed streamer discharge and carbon nanotubes. The pulsed streamer-treated carbon nanotubes were homogeneously dispersed and well solubilized in water for a month or longer. The mechanism of solubilization of carbon nanotubes by the pulsed streamer discharge is discussed based on FTIR spectroscopy and optical emission spectra measurements. FTIR spectroscopy revealed that -OH groups, which are known to impart a hydrophilic nature to carbon material, were introduced on the carbon nanotube surface. Optical emission spectra from the pulsed streamer plasma showed that highly oxidative O(*) and H(*) radicals were generated in water. These results suggest that the functionalization of the carbon nanotube surface by -OH group can be attributed to the O(*) and H(*) radicals. An advantage of the proposed method is that there is no need for any chemical agents or additives for solubilization. Chemical agents for solubilization are generated from the water itself by the electrochemical reactions induced by the pulsed streamer discharge.

Fabrication of bio/nano interfaces between biological cells and carbon nanotubes using dielectrophoresis

“…In order to make CNTs well dispersed in water, pristine CNTs should be chemically functionalized so that their solubility can be greatly improved. In this study, microplasma-based solubilization technique, which has been proposed and developed by the present authors (Imasaka et al 2006 was employed to prepare water soluble CNTs. This solubilization method enables to mix and disperse cells and CNTs together in water without The formation of micro/nano interfaces causing fatal damages to biological cells, which may be induced using surfactants such as SDS.…”

“…The MWCNTs had a diameter of 60-100 nm, a length of 5-15 lm and 95 % purity. The MWCNTs were solubilized in water by the microplasma treatment technique, which was developed by the present authors (Imasaka et al 2006. In brief, radical species, such as H * or O * , are produced by the microplasma in water and functionalize the CNT surface with hydrophilic group including -OH or -COOH.…”

“…Thus far, several approaches have been attempted to solubilize CNTs, such as covalent or noncovalent functionalization (Luong et al 2004), chemical oxidation (Nakajima and Matsuo 1994), addition of surfactants (Islam et al 2003), polymer wrapping (Chen et al 2002) and use of DNA (deoxyribonucleic acid) as a solubilizer (Zheng et al 2003). The authors have previously proposed a novel technique for the preparation of watersoluble carbon nanotubes (CNTs) using microplasma generated by a pulsed streamer discharge in water (Imasaka et al 2006. It was revealed that O* and H* radicals produced by the microplasma in water played an important role in the water-solubilization of CNTs.…”

Investigation of Cytotoxicity of Phosphoryl Choline Modified Single-Walled Carbon Nanotubes under a Live Cell Station

“…In order to deal with these problems, various physical and chemical modifications [13] on CNTs have been carried out for the purpose of improving their solubility in water, which will in turn partially resolve toxicity issue. For example, hydroxyl group [14], carboxyl group [15], polyethylene glycol [16–22], amino group [23], poly(allylamine) [24], DNA or RNA [25, 26], and many others [13, 27] have been used to functionalize CNTs. Meanwhile, the studies on the toxicities, bioeffects, and environment health risks about CNTs have also made great progresses in the past few years; the studies themselves have moved from in vitro model and statistical assay to in vivo animal studies and mechanisms investigations [11, 28–31].…”

Microwave‐based treatments for multi‐walled carbon nanotubes

“…Since carbon nanotubes are chemically inert, many different wet and dry methods based on different oxidizing agents have been developed, but most of them are time consuming, expensive and require accurate control of temperature, atmosphere and reaction time. The other problem with these techniques is the lack of control on formation of the wide variety of oxygenated functional groups such as hydroxyl, epoxy, carbonyl and carboxylic acid moieties on CNTs [3][4][5][6][7][8].…”