Materials with Carbon Nanotubes

Due to their fibrous stracture and remarkable properties, carbon nanotubes are suitable to the production of polymer composites. Their extreme tensile strength 

A variety of substances fits a use as polymer components in these materials. Examples described in the Hterature include polystyrene, polypropylene, PMMA, polyanihne, PmPV, epoxy resins etc. (Section 3.5.5). Polymers with conjugated it-bonds suit best to the incorporabon of carbon nano tubes because the addibonal it-it-interacbon sbengthens the bonding and leads to a wrapping of the (single or bundled) nanotubes in polymer molecules. 

In any case, the mechanical loading capacity of the material increases upon the addibon of carbon nanotubes. The composite s properbes are considerably enhanced, especially with regard to tensile or bending sbess. In workpieces charged with pressure, on the other hand, nanotubes do not convey much benefit as their resistance to compression along the axis is limited. 

In a similar approach, it is not the monomer, but a solution of the prefabricated polymer (polyacrylonibile in this case) in DMF that is being used. Herein the SWNTs are very finely dispersed. The product then also contains nano tubes aligned in the fiber s longitudinal direction. Another procedure resembles the method of producing carbon fibers from PAN (Section 1.2.3). Here the composite fibers are carbonized to yield a material of nanotube-reinforced carbon fibers. At a nanotube portion of as little as 3%, it already exhibits markedly improved mechanical properties. 

The direct production of fibers exclusively consisting of carbon nanotubes succeeded as well. The method makes use of the deposibon from the gas phase on a finely subdivided iron catalyst that is generated in situ. Ethanol added with 2% 

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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. 

Fukushima, T, and Aida, T. (2007], Ionic liquids for soft functional materials with carbon nanotubes. Chem. Eur.]., 13, pp. 5048-5058. 

Conzuelo LV, Arias-Pardilla J, Caitich-Rodriguez JV, Smit MA, Otero TF (2010) Sensing and tactile artificial muscles from reactive materials. Sensors (Basel) 10 2638-2674 Foroughi J, et al (2011) Torsional carbon nanotube artificial muscles. Science 334 494-497 Fukushima T, Aida T (2007) Ionic liquids for soft functional materials with carbon nanotubes. 

Chapter 1 contains a review of carbon materials, and emphasizes the stmeture and chemical bonding in the various forms of carbon, including the foui" allotropes diamond, graphite, carbynes, and the fullerenes. In addition, amorphous carbon and diamond fihns, carbon nanoparticles, and engineered carbons are discussed. The most recently discovered allotrope of carbon, i.e., the fullerenes, along with carbon nanotubes, are more fully discussed in Chapter 2, where their structure-property relations are reviewed in the context of advanced technologies for carbon based materials. The synthesis, structure, and properties of the fullerenes and... 

There is currently considerable interest in processing polymeric composite materials filled with nanosized rigid particles. This class of material called "nanocomposites" describes two-phase materials where one of the phases has at least one dimension lower than 100 nm [13]. Because the building blocks of nanocomposites are of nanoscale, they have an enormous interface area. Due to this there are a lot of interfaces between two intermixed phases compared to usual microcomposites. In addition to this, the mean distance between the particles is also smaller due to their small size which favors filler-filler interactions [14]. Nanomaterials not only include metallic, bimetallic and metal oxide but also polymeric nanoparticles as well as advanced materials like carbon nanotubes and dendrimers. However considering environmetal hazards, research has been focused on various means which form the basis of green nanotechnology. 

Nonconjugated hydrocarbon polymers could also be combined with carbon nanotubes, with polystyrene being the most studied example. The composites are generally prepared by solution or shear mixing techniques, resulting in materials with improved mechanical properties [60]. 

Encapsulation of other material into carbon nanotubes would also open up a possibility for the applications to electrodevices. By applying the template method, perfect encapsulation of other material into carbon nanotubes became possible. No foreign material was observed on the outer surface of carbon nanotubes. The metal-filled uniform carbon nanotubes thus prepared can be regarded as a novel onedimensional composite, which could have a variety of potential applications (e.g novel catalyst for Pt metal-filled nanotubes, and magnetic nanodevice for Fe304-filled nanotubes). Furthermore, the template method enables selective chemical modification of the inner surface of carbon nanotubes. With this technique, carbon... 

The unique two-phase structures of polyurethane that offers the elasticity of rubber combined with the toughness and durability of metal make them one of the most extensively studied and frequently used materials in carbon nanotube related nanocomposites. The main difficulty in developing CNT based polyurethane nanocomposites was how to achieve uniform and homogeneous CNT dispersion. Further investigations on the interactions between carbon nanotubes and two-phase structures are critical for the wider applications of carbon nanotube/polyurethane composites. 

Nanometer-Sized Electronic Devices The possible use of carbon nanotubes in nanoelectronics has aroused considerable interest. Dramatic recent advances have fueled speculation that nanotubes (SWNTs) will be useful for downsizing circuit dimensions. Because of their unique electronic properties, SWNTs can be interfaced with other materials to form novel heterostructures [156]. The simplest device one can imagine with carbon nanotubes is that involving a bend or a kink, arising from the presence of a diametrically opposite pentagon-heptagon pair. The resultant junction connects two nanotubes of different chirality and hence of different electronic structure, leading to the realization of an intramolecular device. Such a device in SWNTs is found to behave like a diode rectifier [157]. Silicon nanowire-carbon nanotube heterojunctions do indeed exhibit a rectification behavior [158]. 

In contrast with carbon nanotubes, mesoporous materials composed of silica and nonsilica species exhibit rich surface chemical activity. The ordered channels in mesoporous materials may act as micro-reactors to assemble nanometer-sized homogeneous guest... 

More recently, Hayashi et al. [50] found that toluene can be retained by adsorption on C oPd, a polymer-like material, at room temperature and at low toluene concentrations. Toluene seems to absorb through its ir-electrons on partially positive Pd atoms of C5oPd . Theoretical studies have suggested that TT-electrons of and toluene overlap through the d-electron orbitals of a Pd atom (thus, not only physical adsorption takes place). This may open a route to fuUerene-based materials as adsorbents for harmful volatile organic compounds (VOCs). Other recent studies on organic vapor adsorption on re connected with either applications in chromatography [51], or as a reference for comparison with carbon nanotubes [52]. 

There have been a number of INS studies of dihydrogen sorbed by microporous oxidic materials, including zeolites. As with carbon nanotubes, there is some interest in the use of these materials for dihydrogen storage. A number are also used as catalysts where the... 

Composites with Other Polymers Besides the composite materials presented so far, a multitude of further polymer composites with carbon nanotubes has been prepared and studied regarding their properties. After all, any given polymer is suitable to some extent to interact with different carbon nanotubes (pristine or functionalized). The number and range of possible combinations surpass the scope of this text, so the examples mentioned below inevitably have to remain incomplete. 

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