Nanotube functionalization

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. 

Such carbonyls may be further oxidized using potassium permanganate (KMnO and perchloric acid (HCIO4) to convert all of these groups into carboxylic acids. Once functionalized in this manner, the nanotubes can be fully dispersed in aqueous systems. Kordas et al. (2006) used these derivatives to print nanotube patterns on paper or polymer surfaces to create conductive patterns for potential use in electronic circuitry. The carboxylates also may be used as conjugation sites to link other ligands or proteins to the nanotube surface using a carbodiimide reaction as previously discussed (Section 1, this chapter Chapter 2, Section 1.11 Chapter 3, Section 1). 

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D. Pantarotto, C.D. Partidos, R. Graff, J. Hoebeke, J.P. Briand, M. Prato, and A. Bianco, Synthesis, structural characterization, and immunological properties of carbon nanotubes functionalized with peptides. J. Am. Chem. Soc. 125, 6160-6164 (2003). 

M.S. Strano, C.A. Dyke, M.L. Usrey, P.W. Barone, MJ. Allen, H. Shan, C. Kittrell, R.H. Hauge, J.M. Tour, R.E. Smalley, Electronic structure control of single-walled carbon nanotube functionalization. Science 301, 1519-1522 (2003). 

Covalent sidewall nanotube functionalization, 17 55 Cover crops, allelopathic, 13 352-353 Covering power, 9 773 Coverstock, use of nonwoven goods in, 17 517... 

Direct consumption sugar, 23 450-451 Direct contact heat exchangers, 13 268 Direct cooler evaporators, 21 537 Direct-coupled plasma (DCF), 25 370 Direct covalent carbon nanotube functionalization, 17 54-55 Direct current (dc) diode sputtering, 24 730-731. See also dc sensing current... 

Noncontact printing, in microarray fabrication, 16 386 Noncoordinating anions, 16 95 Noncovalent carbon nanotube functionalization, 17 53 Noncovalent fluorescence labeling, 20 519... 

Keywords Carbon nanotubes, Functionalization, Drag Delivery, Gene transfer, Health, Biodistribution... 

Menna E, Scorrano G, Maggini M, Cavallaro M, Della Negra F, Battagliarin M, Bozio R, Fantinel F, Meneghetti M (2003) Shortened single-walled nanotubes functionalized with polyethylene glycol) preparation and properties. Arkivoc 64-73. 

This is mainly due to their laborious purification procedures and their required chemical modification for solubilization. Only recently, Prato et al. reported the electrochemistry of carbon nanotubes functionalized using the 1,3-dipolar cycloaddition reaction.120 The cyclic voltammogram obtained is shown in Fig. 8.9. 

Keywords Single-wall carbon nanotube, noncovalent nanotube functionalization, Raman... 

Fig. 2 (a) Raman spectrum of BN nanotubes, (b) Raman spectra of the dispersions of BN nanotubes functionalized with tributylamine (1), trioctylamine (2) and trioctylphosphine (3). 

Nanotube functionalization is performed in other examples listed in Table 11.1. In 1999, Shaffer et al. used carboxylated MWNTs. By contrast to studies described in the followings, this allows to the achievement of homogeneous composites with a large nanotube fraction of about 50 wt%. However, the improvement of the Young s modulus is still weak, particularly if we consider the large amount of CNTs included in the matrix. Liu et al. (47) reported an improvement of mechanical properties with SWNTs which are covalently functionalized by OH groups, compared to the same neat nanotubes simply dispersed with SDS. 

A limitation of AFM approaches in the study of porous materials is the limited ability of the scanned probe tip to penetrate and probe into smaller pores. This is illustrated in Chap. 2 (Fig. 2.23). Clearly, ultrasharp, high aspect ratio probe tips comprise an improvement in this respect. While carbon nanotube functionalized tips are not yet of widespread availability, conventional TM probes are preferred over CM probes because of the different opening angles (compare Chap. 2). In addition,... 

Yang YK, Xie XL, Wu JG et al (2006) Multiwalled carbon nanotubes functionalized by hyperbranched poly (urea-urethtme)s by a one-pot polycondensation. Macromol Rapid... 

Ahmad S, Singh S (2008) Electrochromic device based on carbon nanotubes functionalized poly(methyl pyrrole) synthesized in hydrophobic ionic liquid medium. Electrochem Commun 10 895-898... 

Figure 3.62 Possible ways of carbon nanotube functionalization.

As for the fullerenes, the development of methods for nanotube functionalization began very soon after their discovery. After first successes in opening the tubes and attaching functional groups to their ends, the nejct attempts were made in applying the common reactions of fullerene modification to the side-waU functionalization of the structurally related carbon nanotubes. Many reactions performed on fullerenes can indeed be applied to nanotubes as expected. However, the latter are generally observed to be less reactive, which has already been discussed in Section 3.5.1. 

Polystyrene For polystyrene, both covalently and noncovalently bound composite materials with carbon nanotubes are known. Polystyrene, like the methacrylates, can be generated by surface-initiated radical polymerization on nanotubes functionalized with initiator molecules (in analogy to Figure 3.86). Suitable substances then actually include analogous compounds like in the case of polymethacrylates. 

Carbon nanotubes functionalized with organic residues can act as sensors, too. For example, the limit of detection of NO2 drops below 100 ppt using nanotubes modified with polyethylene imine. Strongly electron-withdrawing molecules as well can be detected this way. Sensors consisting of nanotubes may further... 

Biomedical applications of carbon nanotubes functionalized by heteryl groups 05CC571. 

Rojas, J., Castano, C. H. 2011. Production and characterization of supported transition metal nano-particles on multi-walled carbon nanotubes functionalized by gamma irradiation and chemical processes. In Supplemental Proceedings Volume I Materials Processing and Energy Materials TMS (The Minerals, Metals Materials Society). John Wiley Sons, Inc., New York. 

Fig. 27 (a) Ti02 nanotubes functionalized with group VI semiconductors (b) generation and... 

Fig. 43 Schematic procedure of nanotube functionalization with CdTe (a) conventional...

Ambrogi V, Gentile G, Ducati C, Oliva MC, Carfagna C. MultiwaUed carbon nanotubes functionalized with maleated poly(propylene) by a dry mechano-chemical process. Polymer 2012 53 291-9. 

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