Nanostructures fullerenes

After different allotropic modifications of carbon nanostructures (fullerenes, tubules) have been discovered, a lot of papers dedicated to the investigations of such materials, for instance [9-15] were published, determined by the perspectives of their vast application in different fields of material science. 

Because of the great expectations that these carbon nanostructures—fullerenes, carbon nanotubes, graphene, and related species20—have for potential applications in... 

Highly Organized Carbon Nanostructures Fullerenes and Carbon Nanotubes... 

The nanostructures formed in nanoreactors of polymeric matrixes can be presented as oscillators with rather high oscillation frequency. It should be pointed out that according to references [1] for nanostructures (fullerenes and nanotubes) the absorption in the range of wave numbers 1300-1450 cm is indicative. These values of wave numbers correspond to the frequencies in the range 3.9-4.35x10 Hz, that is, in the range of ultrasound frequencies. 

In addition to diamond and amorphous films, nanostructural forms of carbon may also be formed from the vapour phase. Here, stabilisation is achieved by the formation of closed shell structures that obviate the need for surface heteroatoms to stabilise danghng bonds, as is the case for bulk crystals of diamond and graphite. The now-classical example of closed-shell stabilisation of carbon nanostructures is the formation of C o molecules and other Fullerenes by electric arc evaporation of graphite [38] (Section 2.4). 

Key Words—Carbon nanotubes, fullerenes, STM, fibers, nanostructures, vapor growth. 

Key Words—Graphite, fullerenes, HREM, nanostructures, electron irradiation. 

In addition to chemical or physical properties, a fascinating aspect of fullerene related materials is their central empty space, where atoms, molecules or particles can be enclosed. The enclosed particles are then protected by the robust graphitic layers from chemical or mechanical effects. The very long cavities of CNTs have a special potential due to their high aspect ratio and they can be used as templates to fabricate elongated nanostructures. 

Huczko, A. et al. (2005) Pulmonary toxicity of 1-D nanocarbon materials. Fullerenes, Nanotubes, and Carbon Nanostructures, 13 (2), 141—145. Grubek-Jaworska, H. et al. (2006) Preliminary results on the pathogenic effects of intratracheal exposure to onedimensional nanocarbons. Carbon,... 

Buckminsterfullerene, the most representative example among the fullerenes, have been extensively explored. Their intrinsic properties such as their size, hydrophobicity, three-dimensionality, and electronic properties have made them extremely promising nanostructures, offering interesting features at the interface of various scientific disciplines, ranging from material sciences207 to biological and medicinal chemistry.208-210... 

In conclusion, such three-dimensional carbon-based nanostructures as fullerenes and nanotubes constitute scaffolds whose efficient functionalization and derivatization... 

Measurements of the optical properties in this range of wavelengths can probe the fundamental electronic transitions in these nanostructures. Some of the aforementioned effects have in fact been experimentally revealed in this series of experiments (90). As mentioned above, the IF nanoparticles in this study were prepared by a careful sulfidization of oxide nanoparticles. Briefly, the reaction starts on the surface of the oxide nanoparticle and proceeds inward, and hence the number of closed (fullerene-like) sulfide layers can be controlled quite accurately during the reaction. Also, the deeper the sulfide layer in the nanoparticle, the smaller is its radius and the larger is the strain in the nanostructure. Once available in sufficient quantities, the absorption spectra of thin films of the fullerene-like particles and nanotubes were measured at various temperatures (4-300 K). The excitonic nature of the absorption of the nanoparticles was established, which is a manifestation of the semiconducting nature of the material. Furthermore, a clear red shift in the ex-citon energy, which increased with the number of sulfide layers of the nanoparticles, was also observed (see Fig. 21). The temperature dependence of the exciton... 

Georgakilas V, Pellarini F, Prato M, Guldi DM, Melle-Franco M, Zerbetto F (2002). Supramolecular self-assembled fullerene nanostructures. Proc. Natl. Acad. Sci. USA. 99 5075-5080. 

Foley S, Curtis ADM, Hirsch A, Brettreich M, Pelegrin A, Seta P, Larroque C (2002b) Interaction of a water soluble fullerene derivative with reactive oxygen species and model enzymatic systems. Fullerenes Nanotubes and Carbon Nanostructures 10 49-67. 

Scharff P, Siegmund C, Risch K, Lysko I, Lysko O, Zherebetskyy A, Ivanisik A, Gorchinskiy A, Buzaneva E (2005) Characterization of water-soluble fullerene C-60 oxygen and hydroxyl group derivatives for photosensitizers. Fullerenes Nanotubes and Carbon Nanostructures 13 497-509. 

Carbon nanotubes (CNTs) constitute a nanostructured carbon material that consists of rolled up layers of sp2 hybridized carbon atoms forming a honeycomb lattice. After diamond, graphite and fullerenes, the one-dimensional tubular structure of CNTs is considered the 4th allotrope of carbon (graphene is the 5th). 

The field of carbon nanostructure research is vast and novel, and it experienced a major breakthrough after the discovery of fullerenes in 1985 [1], and their subsequent bulk synthesis in 1990 [2]. This event opened the minds of various scientists towards discovering novel carbon allotropes. Promptly, yet another allotrop of carbon was observed by Iijima [3], although it had previously been produced by M. Endo et al. in the 1970s by chemical vapor deposition (CVD) [4]. The most recent important advance in the quest for novel forms of carbon constitutes the isolation of graphene layers [5], which exhibit unique and exceptional electrical properties [6]. In addition, graphene nanoribbons have recently been synthesized and produced using diverse methods [7]. 

Nanocarbon structures such as fullerenes, carbon nanotubes and graphene, are characterized by their weak interphase interaction with host matrices (polymer, ceramic, metals) when fabricating composites [99,100]. In addition to their characteristic high surface area and high chemical inertness, this fact turns these carbon nanostructures into materials that are very difficult to disperse in a given matrix. However, uniform dispersion and improved nanotube/matrix interactions are necessary to increase the mechanical, physical and chemical properties as well as biocompatibility of the composites [101,102]. 

In the beginning, functionalization reactions were applied to fullerenes [1], later to CNTs [4,3], and recently to graphene [5]. Although both functionalization approaches have clear differences, they share the same intrinsic objective the creation of defects or doping within the surface of the carbon nanostructures in order to facilitate the interactions between the matrix and the filler. 

The first carbon nanostructure that was covalently modified to alter surface properties was the C60 fullerene. After its discovery in the mid-1980s, numerous functionalization methods were developed for obtaining two important classes of derivatives, methanofullerenes and fullerene Diels-Alder adducts. 

Although there have been great advances in covalent functionalization of fullerenes to obtain surface-modified fullerene derivatives or fullerene polymers, the application of these compounds in composites still remains unexplored, basically because of the low availability of these compounds [132]. However, until now, modified fullerene derivatives have been used to prepare composites with different polymers, including acrylic [133,134] or vinyl polymers [135], polystyrene [136], polyethylene [137], and polyimide [138,139], amongst others. These composite materials have found applications especially in the field of optoelectronics [140] in which the most important applications of the fullerene-polymer composites have been in the field of photovoltaic and optical-limiting materials [141]. The methods to covalently functionalize fullerenes and their application for composites or hybrid materials are very well established and they have set the foundations that later were applied to the covalent functionalization of other carbon nanostructures including CNTs and graphene. 

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