Carbon nanotubes surface treatment

Chirila V, Marginean G, Brandi W (2005) Effect of the oxygen plasma treatment parameters on the carbon nanotube surface properties Sur Coat Techn 200 548-551... 

An important route to solubilization of carbon nanotubes is to functionalize their surface to form groups that are more soluble in the desired solvent environment. It has been shown that acid treatment of nanotube bundles, particularly with HC1 or HNO3 at elevated temperatures, opens up the aggregate structure, reduces nanotube length, and facilitates dispersion (An et al., 2004 Kordas et al., 2006). Nitric acid treatment oxidizes the nanotubes at the defect sites of the outer graphene sheet, especially at the open ends (Hirsch, 2002 Alvaro et al., 2004), and creates carbonyl, carboxyl, and hydroxyl groups, which aid in their solubility in polar solvents. 

Carbon nanotubes inevitably contain defects, whose extent depends on the fabrication method but also on the CNT post-treatments. As already seen, oxidizing treatments, such as acid, plasma or electrochemical, can introduce defects that play an important role in the electrochemical performance of CNT electrodes. For instance, Collins and coworkers have published an interesting way to introduce very controlled functionalization points or defects on individual SWNTs by electrochemical means [96]. Other methodologies to introduce artificial defects comprise argon, hydrogen and electron irradiation. Under this context, a number of recent works have appeared with the goal of tailoring the electrochemical behavior of CNT surfaces by the controlled introduction of defects [97, 98]. 

Liu, Y. and Gao, L., A study of the electrical properties of carbon nanotube-NiFe204 composites effect of the surface treatment of the carbon nanotubes , Carbon, 2005, 43, 47-52. 

Surface Treatment of Carbon Nanotube and Other Nanoadditives.272... 

Provided in this chapter is an overview on the fundamentals of polymer nanocomposites, including structure, properties, and surface treatment of the nanoadditives, design of the modifiers, modification of the nanoadditives and structure of modified nanoadditives, synthesis and struc-ture/morphology of the polymer nanocomposites, and the effect of nanoadditives on thermal and fire performance of the matrix polymers and mechanism. Trends for the study of polymer nanocomposites are also provided. This covers all kinds of inorganic nanoadditives, but the primary focus is on clays (particularly on the silicate clays and the layered double hydroxides) and carbon nanotubes. The reader who needs to have more detailed information and/or a better picture about nanoadditives and their influence on the matrix polymers, particularly on the thermal and fire performance, may peruse some key reviews, books, and papers in this area, which are listed at the end of the chapter. 

Surface area of as-obtained CNF is nearly 300-500 m2/g. One of the effective methods of activation of different carbon materials is treatment with melted KOH at 400-900°C. High surface area (up to nearly 3000 m2/g) carbon materials were obtained [16, 17]. This method was also applied to carbon nanotubes. Significant development of surface was observed, from 465 m2/g for starting MWNT to 1184 m2/g after activation [18], Also, KOH activation of carbon nanofibers resulted in increase of surface area from initial 174 m2/g up to 1212 m2/g [19]. When activated our nanofibers, we obtained for some samples very high effective surface area, nearly 2000-4000 m2/g and in some experiments even 6000 m2/g (measured by argon desorption method). In electron image of activated material (Fig. 7) fiber-like structure is observed. 

P2VP macroradicals were added to multi-walled carbon nanotubes (CNTs), which was proved to be an effective grafting to method [26], In contrast to other methods of CNTs modification, the macroradical addition does not require any hard oxidative pre-treatment of the CNTs, which preserves their original size. Deposition of an amorphous shell at the surface of CNTs was confirmed by TEM observations. Figure 4a shows modified nanotubes with closed... 

Behler K, Osswald S, Ye H, Dimovski S et al (2006) Effect of thermal treatment on the structure of multi-walled carbon nanotubes. J Nanopart Res 8 615-625 Fanning PE, Vannice MA (1993) A drifts study of the formation of surface groups on carbon by oxidation. Carbon 31(5) 721-730... 

FIGURE 2.21 Aligned carbon nanotubes with a bioactive conducting polymer (a) Pure CNT array before treatment, (b) aligned CEP-CNT coaxial nanowires inset shows clear image of single tube coated with PPy, (c) PPy only deposited on the top of CNT surface because of high density of tubes, and (d) polymer formed on both outside of walls and the top of the surface of the CNT array. (With permission from Electroanalysis, 15, 1089 (2003). 2003, Wiley-VCH.)... 

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