Chemically Modified Carbon Nanotubes

Jiang, M.-J. Dang, Z.-M. Xu, H.-P., Enhanced Electrical Conductivity in Chemically Modified Carbon Nanotube/Methylvinyl Silicone Rubber Nanocomposite. Ear. Polym. J. 2007, 43, 4924-4930. 

Figure 4 (A) AFM images (a) MWNTs/CoTMPyP/RCI film assembled on GC electrode (before electrochemical reduction) (b) MWNTs/CoTMPyP/R hybrid film (after electrochemical reduction at - 0.7 V in N2-saturated 0.1 mol I KCI solution). (B) XPS data of MWNTs/CoTMPyP film on GC surface (cun/es (a) and (b)) and MWNTs/CoTMPyP/RCii" film in the R (4f) region before (cun/e (c)) and after (cun/e (d)) electrochemical reduction. (Qu JY, Shen Y, Qu XH, and Dong SJ (2004) Preparation of hybrid thin film modified carbon nanotubes on glassy carbon electrode and its electrocatalysis for oxygen reduction. Chemical Communications 2004 34-35 reproduced by permission of The Royal Society of Chemistry.)...

Arguably, the first commercial analytical chemical instrument" was the glass electrode poten-tiometric pH meter, invented and marketed by Arnold Beckman in the 1930s. In 2004, a group at Oxford University published a means of measuring pH with special modified carbon nanotube... 

J J. Davis, K.S. Coleman, B.R. Azamian, C.B. Bagshaw, and M.L.H. Green, Chemical and biochemical sensing with modified single walled carbon nanotubes. Chem. Eur. J. 9, 3732—3739 (2003). 

In recent years, CNTs have been receiving considerable attention because of their potential use in biomedical applications. Solubility of CNTs in aqueous media is a fundamental prerequisite to increase their biocompatibility. For this purpose several methods of dispersion and solubilisation have been developed leading to chemically modified CNTs (see Paragraph 2). The modification of carbon nanotubes also provides multiple sites for the attachment of several kinds of molecules, making functionalised CNTs a promising alternative for the delivery of therapeutic compounds. 

Section I reviews the new concepts and applications of nanotechnology for catalysis. Chapter 1 provides an overview on how nanotechnology impacts catalyst preparation with more control of active sites, phases, and environment of actives sites. The values of catalysis in advancing development of nanotechnology where catalysts are used to facilitate the production of carbon nanotubes, and catalytic reactions to provide the driving force for motions in nano-machines are also reviewed. Chapter 2 investigates the role of oxide support materials in modifying the electronic stmcture at the surface of a metal, and discusses how metal surface structure and properties influence the reactivity at molecular level. Chapter 3 describes a nanomotor driven by catalysis of chemical reactions. 

CNT randomly dispersed composites Many soft and rigid composites of carbon nanotubes have been reported [17]. The first carbon-nanotube-modified electrode was made from a carbon-nanotube paste using bromoform as an organic binder (though other binders are currently used for the paste formation, i.e. mineral oil) [105]. In this first application, the electrochemistry of dopamine was proved and a reversible behavior was found to occur at low potentials with rates of electron transfer much faster than those observed for graphite electrodes. Carbon-nanotube paste electrodes share the advantages of the classical carbon paste electrode (CPE) such as the feasibility to incorporate different substances, low background current, chemical inertness and an easy renewal nature [106,107]. The added value with CNTs comes from the enhancement of the electron-transfer reactions due to the already discussed mechanisms. 

Taking into consideration that only the inner wall surface of carbon nanotubes is exposed to atmosphere in the stage of carbon-deposited alumina film, it would be possible to modify only the inner surface if the carbon-deposited alumina film is chemically treated. On the basis of this concept, Hattori et al. tried to fluorinate only the inner surface of carbon nanotubes (42). It is well known that fluorination is quite an effective way to introduce strong hydrophobicity to carbonaceous materials, and it perturbs the carbon it electron system (43,44). Thus, by the selective fluorination of nanotube s inner surface, it would be possible to produce carbon nanotubes whose inner surface is highly hydrophobic and electrically insulating while their outer... 

Attaching chemical functionalities to CNTs can improve their solubility and allow for their manipulation and processability [24]. The chemical functionalization can tailor the interactions of nanotubes with solvents, polymers and biopolymer matrices. Modified tubes may have physical or mechanical properties different from those of the original nanotubes and thus allow tuning of the chemistry and physics of carbon nanotubes. Chemical functionalization can be performed selectively, the metallic SWCNTs reacting faster than semiconducting tubes [25]. 

Double-walled carbon nanotubes (DWNTs), first observed in 1996, constitute a unique family of carbon nanotubes (CNTs). -2 DWNTs occupy a position between the single-walled carbon nanotubes (SWNTs) and the multiwalled carbon nanotubes (MWNTs), as they consist of two concentric cylinders of rolled graphene. DWNTs possess useful electrical and mechanical properties with potential applications. Thus, DWNTs and SWNTs have similar threshold voltages in field electron emission, but the DWNTs exhibit longer lifetimes.3 Unlike SWNTs, which get modified structurally and electronically upon functionalization, chemical functionalization of DWNTs surfaces would lead to novel carbon nanotube materials where the inner tubes are intact. The stability of DWNTs is controlled by the spacing of the inner and outer layers but not by the chirality of the tubes 4 therefore, one obtains a mixture of DWNTs with varying diameters and chirality indices of the inner and outer tubes. DWNTs have been prepared by several techniques, such as arc discharge5 and chemical vapor depo-... 

Single-walled carbon nanotubes, SWNT, having a diameter of 0.7 nm were electro-chemically derivatized on the sides and ends with diazonium tetrafluoroborate derivatives. In this process the estimated degree of functionality was about 1 out of every 20 to 30 carbons in the nanotube. These chemically modified nanotubes have applications in polymer composite materials, molecular electronic applications, and sensor devices. 

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