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Single-walled Carbon Nanotubes (single-walled + carbon_nanotube)
Selected AbstractsPreparation and properties of the single-walled carbon nanotube/cellulose nanocomposites using N -methylmorpholine- N -oxide monohydrateJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010Dong-Hun Kim Abstract Single-walled carbon nanotube (SWNT)/cellulose nanocomposite films were prepared using N -methylmorpholine- N -oxide (NMMO) monohydrate as a dispersing agent for the acid-treated SWNTs (A-SWNTs) as well as a cellulose solvent. The A-SWNTs were dispersed in both NMMO monohydrate and the nanocomposite film (as confirmed by scanning electron microscopy) because of the strong hydrogen bonds of the A-SWNTs with NMMO and cellulose. The mechanical properties, thermal properties, and electric conductivity of the nanocomposite films were improved by adding a small amount of the A-SWNTs to the cellulose. For example, by adding 1 wt % of the A-SWNTs to the cellulose, tensile strain at break point, Young's modulus, and toughness increased , 5.4, , 2.2, and , 6 times, respectively, the degradation temperature increased to 9°C as compared with those of the pure cellulose film, and the electric conductivities at , (the wt % of A-SWNTs in the composite) = 1 and 9 were 4.97 × 10,4 and 3.74 × 10,2 S/cm, respectively. Thus, the A-SWNT/cellulose nanocomposites are a promising material and can be used for many applications, such as toughened Lyocell fibers, transparent electrodes, and soforth. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Pseudo 3D Single-Walled Carbon Nanotube Film for BSA-Free Protein ChipsCHEMBIOCHEM, Issue 8 2005Hye Ryung Byon Sweet home for proteins. Single-walled carbon nanotube (SWNT) film treated with CDI,Tween20 (CT) has been used as a substrate for a BSA-free protein chip. In the absence of BSA, which is conventionally applied as a nonspecific binding inhibitor, protein A, biotinylated BSA, and even small peptide such as 3×FLAG immobilized on the CT-functionalized SWNT film substrates recognize their respective counterparts, streptavidin, immunoglobulin G, and antiFLAG. with high specificity. [source] Effects of functionalized and nonfunctionalized single-walled carbon nanotubes on root elongation of select crop species,,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2008Jaclyn E. Cañas Abstract Single-walled carbon nanotubes have many potential beneficial uses, with additional applications constantly being investigated. Their unique properties, however, create a potential concern regarding toxicity, not only in humans and animals but also in plants. To help develop protocols to determine the effects of nanotubes on plants, we conducted a pilot study on the effects of functionalized and nonfunctionalized single-walled carbon nanotubes on root elongation of six crop species (cabbage, carrot, cucumber, lettuce, onion, and tomato) routinely used in phytotoxicity testing. Nanotubes were functionalized with poly-3-aminoben-zenesulfonic acid. Root growth was measured at 0, 24, and 48 h following exposure. Scanning-electron microscopy was used to evaluate potential uptake of carbon nanotubes and to observe the interaction of nanotubes with the root surface. In general, nonfunctionalized carbon nanotubes affected root length more than functionalized nanotubes. Nonfunctionalized nanotubes inhibited root elongation in tomato and enhanced root elongation in onion and cucumber. Functionalized nanotubes inhibited root elongation in lettuce. Cabbage and carrots were not affected by either form of nanotubes. Effects observed following exposure to carbon nanotubes tended to be more pronounced at 24 h than at 48 h. Microscopy images showed the presence of nanotube sheets on the root surfaces, but no visible uptake of nanotubes was observed. [source] Selective Electrochemical Etching of Single-Walled Carbon NanotubesADVANCED FUNCTIONAL MATERIALS, Issue 22 2009Dacheng Wei Abstract Single-walled carbon nanotubes (SWNTs) are a promising material for future nanotechnology. However, their applications are still limited in success because of the co-existence of metallic SWNTs and semiconducting SWNTs produced samples. Here, electrochemical etching, which shows both diameter and electrical selectivity, is demonstrated to remove SWNTs. With the aid of a back-gate electric field, selective removal of metallic SWNTs is realized, resulting in high-performance SWNT field-effect transistors with pure semiconducting SWNT channels. Moreover, electrochemical etching is realized on a selective area. These findings would be valuable for research and the application of SWNTs in electrochemistry and in electronic devices. [source] A Versatile, Molecular Engineering Approach to Simultaneously Enhanced, Multifunctional Carbon-Nanotube, Polymer Composites,ADVANCED FUNCTIONAL MATERIALS, Issue 1 2006J. Chen Abstract Single-walled carbon nanotubes (SWNTs) are recognized as the ultimate carbon fibers for high-performance, multifunctional composites. The remarkable multifunctional properties of pristine SWNTs have proven, however, difficult to harness simultaneously in polymer composites, a problem that arises largely because of the smooth surface of the carbon nanotubes (i.e., sidewalls), which is incompatible with most solvents and polymers, and leads to a poor dispersion of SWNTs in polymer matrices, and weak SWNT,polymer adhesion. Although covalently functionalized carbon nanotubes are excellent reinforcements for mechanically strong composites, they are usually less attractive fillers for multifunctional composites, because the covalent functionalization of nanotube sidewalls can considerably alter, or even destroy, the nanotubes' desirable intrinsic properties. We report for the first time that the molecular engineering of the interface between non-covalently functionalized SWNTs and the surrounding polymer matrix is crucial for achieving the dramatic and simultaneous enhancement in mechanical and electrical properties of SWNT,polymer composites. We demonstrate that the molecularly designed interface of SWNT,matrix polymer leads to multifunctional SWNT,polymer composite films stronger than pure aluminum, but with only half the density of aluminum, while concurrently providing electroconductivity and room-temperature solution processability. [source] Vertically Aligned Single-Walled Carbon Nanotubes by Chemical Assembly , Methodology, Properties, and ApplicationsADVANCED MATERIALS, Issue 13 2010Peng Diao Abstract Single-walled carbon nanotubes (SWNTs), as one of the most promising one-dimension nanomaterials due to its unique structure, peculiar chemical, mechanical, thermal, and electronic properties, have long been considered as an important building block to construct ordered alignments. Vertically aligned SWNTs (v-SWNTs) have been successfully prepared by using direct growth and chemical assembly strategies. In this review, we focus explicitly on the v-SWNTs fabricated via chemical assembly strategy. We provide the readers with a full and systematic summary covering the advances in all aspects of this area, including various approaches for the preparation of v-SWNTs using chemical assembly techniques, characterization, assembly kinetics, and electrochemical properties of v-SWNTs. We also review the applications of v-SWNTs in electrochemical and bioelectrochemical sensors, photoelectric conversion, and scanning probe microscopy. [source] Specific thermal ablation of tumor cells using single-walled carbon nanotubes targeted by covalently-coupled monoclonal antibodiesINTERNATIONAL JOURNAL OF CANCER, Issue 12 2009Radu Marches Abstract CD22 is broadly expressed on human B cell lymphomas. Monoclonal anti-CD22 antibodies alone, or coupled to toxins, have been used to selectively target these tumors both in SCID mice with xenografted human lymphoma cell lines and in patients with B cell lymphomas. Single-walled carbon nanotubes (CNTs) attached to antibodies or peptides represent another approach to targeting cancer cells. CNTs convert absorbed near-infrared (NIR) light to heat, which can thermally ablate cells that have bound the CNTs. We have previously demonstrated that monoclonal antibodies (MAbs) noncovalently coupled to CNTs can specifically target and kill cells in vitro. Here, we describe the preparation of conjugates in which the MAbs are covalently conjugated to the CNTs. The specificity of both the binding and NIR-mediated killing of the tumor cells by the MAb-CNTs is demonstrated by using CD22+CD25, Daudi cells, CD22,CD25+ phytohemagglutinin-activated normal human peripheral blood mononuclear cells, and CNTs covalently modified with either anti-CD22 or anti-CD25. We further demonstrate that the stability and specificity of the MAb-CNT conjugates are preserved following incubation in either sodium dodecyl sulfate or mouse serum, indicating that they should be stable for in vivo use. © 2009 UICC [source] Fault-Tolerant Dielectric Elastomer Actuators using Single-Walled Carbon Nanotube Electrodes,ADVANCED MATERIALS, Issue 3 2008W. Yuan Fault-tolerant actuators. Single-walled carbon nanotubes were studied as new compliant electrodes for dielectric elastomers. The spray-coated SWNT electrodes drive electromechanical strains greater than 200,%. When a fault is present due to pin puncture or internal defect in the elastomer films, dielectric breakdown causes localized self-clearing of the SWNT electrodes and isolation of the fault. The increased fault tolerance may enhance the actuation reliability of dielectric elastomers actuators. [source] Growth of Cement Hydration Products on Single-Walled Carbon NanotubesJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 6 2009Jonathan M. Makar Single-walled carbon nanotubes (SWCNT) were distributed on the surface of ordinary Portland cement (OPC) grains. The OPC/SWCNT composite was then hydrated at a 0.5 w/c ratio. The effects of the SWCNT on the early hydration process were studied using isothermal conduction calorimetry, high-resolution scanning electron microscopy and thermogravimetric analysis. The observed behavior of the composite samples was compared with both OPC sonicated without SWCNT and previously published data on as-delivered OPC. The SWCNT were found to accelerate the hydration reaction of the C3S in the OPC. The morphology of both the initial C3A and the C3S hydration products were found to be affected by the presence of the SWCNT. In particular, the nanotubes appeared to act as nucleating sites for the C3S hydration products, with the nanotubes becoming rapidly coated with C,S,H. The resulting structures remained on the surface of the cement grains while those in the sonicated and as-delivered OPC samples grew out from the grain surfaces to form typical C,S,H clusters. Classical evidence of reinforcing behavior, in the form of fiber pullout of the SWCNT bundles, was observed by 24 h of hydration. [source] Photothermal antimicrobial nanotherapy and nanodiagnostics with self-assembling carbon nanotube clustersLASERS IN SURGERY AND MEDICINE, Issue 7 2007Jin-Woo Kim PhD Abstract Background and Objectives Unique properties of carbon nanotubes (CNTs) would open new avenues for addressing challenges to realize rapid and sensitive antimicrobial diagnostics and therapy for human pathogens. In this study, new CNTs' capabilities for photothermal (PT) antimicrobial nanotherapy were explored in vitro using Escherichia coli as a model bacterium. Study Design/Materials and Methods Single-walled carbon nanotubes (SWNTs) and multi-walled carbon nanotubes (MWNTs) were incubated with E. coli K12 strain. CNTs' locations in bacteria and laser-induced thermal and accompanied effects around CNTs were estimated with TEM and PT microscopy, respectively. Multi-pulse lasers at 532 and 1064 nm with 12-ns pulse duration were used for irradiating sample mixtures at different laser fluences. Cell viability was evaluated using a bacterial viability test kit and epi-fluorescence microscopy. Results This study revealed CNTs' high binding affinity to bacteria, their capability to self-assemble as clusters at bacteria surfaces, and their inherent near-infrared (NIR) laser responsiveness. Cell viability was affected neither by CNTs alone nor by NIR irradiations alone. Notable changes in bacteria viability, caused by local thermal and accompanied bubble-formation phenomena, were observed starting at laser fluences of 0.1,0.5 J/cm2 with complete bacteria disintegration at 2,3 J/cm2 at both wavelengths. Furthermore, ethanol in reaction mixtures significantly (more than one order) enhanced bubble formation phenomena. Conclusion This first application of laser-activated CNTs as PT contrast antimicrobial agents demonstrated its great potential to cause irreparable damages to disease-causing pathogens as well as to detect the pathogens at single bacterium level. This unique integration of laser and nanotechnology may also be used for drinking water treatment, food processing, disinfection of medical instrumentation, and purification of grafts and implants. Furthermore, the significant ethanol-induced enhancement of bubble formation provides another unique possibility to improve the efficiency of selective nanophotothermolysis for treating cancers, wounds, and vascular legions. Lesers Surg. Med. 39:622,634, 2007. © 2007 Wiley-Liss, Inc. [source] pH Tailoring Electrical and Mechanical Behavior of Polymer,Clay,Nanotube AerogelsMACROMOLECULAR RAPID COMMUNICATIONS, Issue 19 2009Matthew D. Gawryla Abstract Aerogels are low density (<0.1,g,·,cm,3), highly porous materials that are especially interesting for insulating applications. Combinations of clay and water-soluble polymers are commonly used to produce aerogels, but these materials are often mechanically weak. Single-walled carbon nanotubes (SWNT) were combined with clay and found to significantly improve mechanical behavior and impart electrical conductivity to these aerogels. Poly(acrylic acid) (PAA) as the matrix polymer provides a means of tailoring the electrical conductivity and mechanical behavior by altering the pH of the aqueous aerogel precursor suspensions prior to freeze drying. An aerogel, made from a pH 9 aqueous suspension containing 0.5,wt.-% PAA, 5,wt.-% clay, and 0.05,wt.-% SWNT, has a compressive modulus of 373,kPa. In the absence of nanotubes, this modulus is reduced to 43,kPa. Reducing suspension pH to 3, prior to freeze drying, also reduces modulus for these aerogels, but electrical conductivity is increased when nanotubes are present. It was found that bundled nanotubes provide better reinforcement for these low-density composites, which may provide some new insight into the use of nanotubes in materials that will be exposed to compressive loading. [source] Photonic bandgap modification in hollow optical fibers integrated with single walled carbon nanotubesMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 11 2009Marco Pisco Abstract Single-walled carbon nanotubes (SWCNTs) have been infiltrated within the holes of hollow-core optical fibers (HOFs) by Langmuir-Blodgett method in order to develop new in-fiber active and passive optoelectronic devices. Far field transmission characterizations demonstrated HOF's holes successful filling and the SWCNTs' capability to modify the guiding properties of HOFs. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2729,2732, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24725 [source] Single-walled carbon nanotubes modified by PFO: An optical absorption and Raman spectroscopic investigationPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 11-12 2009P. Lukaszczuk Abstract In this contribution, we present preliminary results from an optical absorption and resonance Raman spectroscopic investigation on single-walled carbon nanotubes (SWCNT) functionalized by poly(9,9-dioctylfluorenyl-2,7-diyl)- co -bithiophene (PFO-BTP). A route for a stable suspension of SWCNT in a solution of fluorine-base copolymer is shown. Additionally, the detailed analysis of the supernatant and sediment after centrifugation of the functionalized sample is given. The resonance Raman and optical absorption spectroscopic data suggest that selective wrapping of the carbon nanotubes by PFO occurs. Additionally, one can see that the abundance of SWCNT in the supernatant in a bulk sample increased by a factor of 2. [source] Single-walled carbon nanotubes as nanotest tubesPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 11 2007E. Borowiak-Palen Abstract In this study a wet-chemistry procedure to perform a metathesis reaction in the interior of single-walled carbon nanotube (SWCNT) is shown. Initially, AgNO3 was placed into the tube interior. The AgNO3 filling was then transformed into AgCl through a metathesis reaction involving a treatment step with HCl. The reaction highlights the potential application of SWCNT as nanotest tubes. This was further demonstrated by the successful development of a facile and efficient wet-chemistry route to purge the AgCl filling from the interior of the SWCNT. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Carbon Nanotube,Acridine Nanohybrids: Spectroscopic Characterization of Photoinduced Electron TransferCHEMISTRY - A EUROPEAN JOURNAL, Issue 15 2009Nicolas Mackiewicz Dr. Abstract Change happens: Acridine,carbon nanotube nanohybrids were built (see figure) and their photoinduced electron-transfer properties investigated, showing variable behaviour depending on the acridine partner. Single-walled carbon nanotubes (NT) were covalently functionalized with either 9-phenyl acridine (PhA) or 10-methyl-9-phenyl acridinium (PhMeA+). Absorption and fluorescence properties of acridine derivatives tethered to the nanotubes were studied in homogeneous dispersions. Exciplex emission was observed for NT functionalized with 9-phenylacridine. This phenomenon was attributed to an "intramolecular" interaction between excited phenyl acridine and carbon nanotubes. Interestingly, reverse photoinduced electron transfer from the nanotube to 10-methyl-9-phenylacridinium was detected for the NT-PhMeA+ nanohybrid. This electron transfer led to a strong quenching of the acridinium fluorescence and to the formation of a metastable acridine radical. Evidence for the formation of this radical was obtained by ESR studies. [source] Spectroscopic Characteristics of Differently Produced Single-Walled Carbon NanotubesCHEMPHYSCHEM, Issue 13 2009Zhongrui Li Prof. Dr. Abstract Single-walled carbon nanotubes (SWNTs) synthesized with different methods are investigated by using multiple characterization techniques, including Raman scattering, optical absorption, and X-ray absorption near edge structure, along with X-ray photoemission by following the total valence bands and C 1s core-level spectra. Four different SWNT materials (produced by arc discharge, HiPco, laser ablation, and CoMoCat methods) contain nanotubes with diameters ranging from 0.7 to 2.8 nm. The diameter distribution and the composition of metallic and semiconducting tubes of the SWNT materials are strongly affected by the synthesis method. Similar sp2 hybridization of carbon in the oxygenated SWNT structure can be found, but different surface functionalities are introduced while the tubes are processed. All the SWNTs demonstrate stronger plasmon resonance excitations and lower electron binding energy than graphite and multiwalled carbon nanotubes. These SWNT materials also exhibit different valence-band X-ray photoemission features, which are considerably affected by the nanotube diameter distribution and metallic/semiconducting composition. [source] Characterisation of Nanohybrids of Porphyrins with Metallic and Semiconducting Carbon Nanotubes by EPR and Optical SpectroscopyCHEMPHYSCHEM, Issue 13 2008Sofie Cambré Abstract Single-walled carbon nanotubes (SWCNTs) are noncovalently functionalised with octaethylporphyrins (OEPs) and the resulting nanohybrids are isolated from the free OEPs. Electron paramagnetic resonance (EPR) spectroscopy of cobalt(II)OEP, adsorbed on the nanotube walls by ,,,-stacking, demonstrates that the CNTs act as electron acceptors. EPR is shown to be very effective in resolving the different interactions for metallic and semiconducting tubes. Moreover, molecular oxygen is shown to bind selectively to nanohybrids with semiconducting tubes. Water solubilisation of the porphyrin/CNT nanohybrids using bile salts, after applying a thorough washing procedure, yields solutions in which at least 99,% of the porphyrins are interacting with the CNTs. Due to this purification, we observe, for the first time, the isolated absorption spectrum of the interacting porphyrins, which is strongly red-shifted compared to the free porphyrin absorption. In addition a quasi-complete quenching of the porphyrin fluorescence is also observed. [source] Molecular dynamics of the generation process of double-walled carbon nanotubes from peapodsHEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 4 2006Yasushi Shibuta Abstract The generation process of a double-walled carbon nanotube (DWNT) from a "peapod" was studied by classical molecular dynamics simulation. Starting from a peapod structure, defined by five C60 molecules inside a (10,10) single-walled carbon nanotube (SWNT), polymerized fullerenes, a peanut-like structure and an almost nanotube-like structure were obtained under suitable conditions of temperature control. The mean distance between the two layers of the DWNT agreed with an experimental report that it is larger than the interlayer spacing found in multi-walled carbon nanotubes (MWNTs). In addition, the chirality dependence of the potential energy of a DWNT on the relative chirality of its constituent tubes was examined using a 6-12 Lennard-Jones potential. It was found that the potential energy depends only on the distance between the two layers, not on the relative chiralities. © 2006 Wiley Periodicals, Inc. Heat Trans Asian Res, 35(4): 254,264, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20115 [source] Nanotube Surfactant Design: The Versatility of Water-Soluble Perylene BisimidesADVANCED MATERIALS, Issue 7 2010Claudia Backes Abstract The synthesis of perylene-based single-walled carbon nanotube (SWCNT) surfactants and the dispersion and exfoliation of SWCNTs in water by a variety of designed surfactants is investigated. The quality of the nanotube dispersions is evaluated by optical absorption and emission spectroscopy, zeta-potential measurements and statistical atomic force microscopy (AFM). Significantly the dispersion efficiency can be increased at higher pH, as water solubility of the surfactants is ensured by peripheral derivatization with carboxyl-functionalized first- and second-order Newkome dendrimers. Even at very low perylene concentrations of 0.1,g L,1 and a nanotube-to-surfactant ratio of 1:1, the nanotube supernatant after centrifugation contains up to 73% of the pristine material with exfoliation degrees (the number of fractions of individualized nanotubes NI/NT) of up to 76%. The adsorption of the perylene core to the nanotube scaffold is indicated by red-shifted perylene-absorption and SWCNT-emission features except for the smallest perylene amphiphile, where solubilization is presumably based on a micellar arrangement. The nanotube fluorescence is significantly altered and reduced in intensity compared to nanotubes dispersed in sodium dodecylbenzene sulfonate (SDBS) being strongly dependent on the structure of the perylene surfactant. We attribute this observation to the homogeneity of the surfactant coverage, e.g., the supramolecular arrangement onto the nanotube backbone. This study represents a step forward in understanding the structure,property relationship of nanotube surfactants. Furthermore high-quality nanotube dispersions with increased degrees of exfoliation are highly desirable, as the efficiency of nanotube separation techniques relies on highly individualized samples. [source] Functional Covalent Chemistry of Carbon Nanotube SurfacesADVANCED MATERIALS, Issue 6 2009Xiaohui Peng Abstract In this Progress Report, we update covalent chemical strategies commonly used for the focused functionalization of single-walled carbon nanotube (SWNT) surfaces. In recent years, SWNTs have been treated as legitimate nanoscale chemical reagents. Hence, herein we seek to understand, from a structural and mechanistic perspective, the breadth and types of controlled covalent reactions SWNTs can undergo in solution phase, not only at ends and defect sites but also along sidewalls. We explore advances in the formation of nanotube derivatives that essentially maintain and even enhance their performance metrics after precise chemical modification. We especially highlight molecular insights (and corresponding correlation with properties) into the binding of functional moieties onto carbon nanotube surfaces. Controllable chemical functionalization suggests that the unique optical, electronic, and mechanical properties of SWNTs can be much more readily tuned than ever before, with key implications for the generation of truly functional nanoscale working devices. [source] Fully Transparent Thin-Film Transistors Based on Aligned Carbon Nanotube Arrays and Indium Tin Oxide Electrodes,ADVANCED MATERIALS, Issue 5 2009Sunkook Kim Fully transparent thin-film transistors (TFTs) based on well-aligned single-walled carbon nanotube (SWCNT) arrays with indium tin oxide (ITO) electrodes are achieved. The fully transparent SWCNT-TFTs could be attractive candidates for future flexible or transparent electronics. [source] A Catalytic Reaction Inside a Single-Walled Carbon Nanotube,ADVANCED MATERIALS, Issue 8 2008Hidetsugu Shiozawa A catalytic reaction inside a single-walled carbon nanotube is demonstrated by using encapsulated ferrocene molecules as precursors. A combined spectroscopic and microscopic study unravels the mechanism of catalytic inner tube growth. This confined process provides for the controlled iron growing of double-walled carbon nanotubes and represents a new route for materials design. [source] High-frequency transmission through metallic single-walled carbon nanotube interconnectsINTERNATIONAL JOURNAL OF NUMERICAL MODELLING: ELECTRONIC NETWORKS, DEVICES AND FIELDS, Issue 5 2009M. S. Tahvili Abstract In this paper, high-frequency transmission behavior of metallic single-walled carbon nanotube (SWCNT) interconnects is investigated. The SWCNT is assumed to be lying over a doped Si substrate, in a transmission line configuration. A hybrid approach, combining quantum theory with classical distributed-element model is utilized to predict dynamical performance of the metallic SWCNT as a nano transmission line. Several aspects of high-frequency performance of such interconnect, including the effect of SWCNT length and substrate doping level, is studied. A novel modification is proposed to take damping mechanisms effect caused by the imperfect conductance of substrate into account. The results show that the impact of limited conductivity of the substrate determines the dynamical behavior of short SWCNTs; whereas in case of long nanotubes, damping effects that arise from scattering mechanisms are dominant. Copyright © 2009 John Wiley & Sons, Ltd. [source] Cumulative ,-, interaction triggers unusually high stabilization of linear hydrocarbons inside the single-walled carbon nanotubeINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 12 2007T. C. Dinadayalane Abstract The interactions of linear hydrocarbons C2nH4 and C2nH2 (n = 1,4) with a finite-length armchair (5,5) single-walled carbon nanotube have been investigated using HF and MP2 methods in conjunction with 6-31G(d) basis set, and molecular mechanics (MM) with MM2 force field. In all cases, the results obtained at MP2/6-31G(d) level show stabilization of these supramolecular systems, contrary to the repulsive interactions obtained with the HF method. The interaction energies computed using MM with MM2 force field are in close agreement with the results obtained using the MP2/6-31G(d) level. They increase gradually as the length of linear hydrocarbon chain increases. The present study indicates that cumulative ,-, interaction is the origin for the exceptionally high stabilization of the long nanotube-hydrocarbon complexes. Mulliken population analysis reveals a very small charge transfer between the nanotube and the guest. Essentially there is no change in HOMO-LUMO energy gap by the insertion of linear hydrocarbons. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007 [source] Interaction Between Polymer Chains Covalently Fixed to Single-Walled Carbon NanotubesMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 9 2006Hiromi Kitano Abstract Summary: A single-walled carbon nanotube (SWNT), which had been oxidized with a mixture of nitric acid and sulfuric acid to afford polar groups at its ends, was incubated with an azo-type macroinitiator carrying dextran (DEX), poly(ethylene glycol) (PEG) or poly(N -vinylpyrrolidone) (PVPy) chains at 70,°C. Similarly, the oxidized SWNT was incubated with 2,2,-azoisobutyronitrile and acrylic acid (HAA) or N -vinylpyrrolidone at 70,°C. Due to the large radical trapping ability of SWNT, the polymer chains corresponding to the cloven macroinitiator (PEG, DEX or PVPy) and the propagating polymer chains (poly(acrylic acid) (HPAA) or PVPy) were covalently fixed to the surface of the SWNTs. The hydrophilic polymer-modified SWNTs could be stably dispersed in water. Furthermore, the SWNTs modified with PEG and DEX sedimented in the presence of free DEX and PEG, respectively, whereas there was no precipitation of the PEG- and DEX-modified SWNTs in the presence of the same kind of free polymer. This seemed to be related to the phase separation phenomena in water soluble DEX and PEG systems induced by the repulsive interaction between PEG and DEX molecules. However, the mixture of two kinds of polymer-modified SWNTs (PEG-SWNT and DEX-SWNT) did not show noticeable phase separation, probably due to steric hindrance for the efficient repulsive polymer-polymer interaction by fixation to the gigantic SWNTs. Furthermore, upon mixing the dispersions of HPAA-SWNT and PEG-SWNT or PVPy-SWNT, the turbidity of the dispersions gradually increased, while no increase in turbidity of the dispersion mixture was observed in the presence of dimethyl sulfoxide, indicating hydrogen bonding between the HPAA and PEG or PVPy chains on the surface of the SWNTs. The modification methods examined in this work would be promising to give various functions to SWNT. Susceptible processes of radical trap on SWNT surface. [source] Single-walled carbon nanotubes as nanotest tubesPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 11 2007E. Borowiak-Palen Abstract In this study a wet-chemistry procedure to perform a metathesis reaction in the interior of single-walled carbon nanotube (SWCNT) is shown. Initially, AgNO3 was placed into the tube interior. The AgNO3 filling was then transformed into AgCl through a metathesis reaction involving a treatment step with HCl. The reaction highlights the potential application of SWCNT as nanotest tubes. This was further demonstrated by the successful development of a facile and efficient wet-chemistry route to purge the AgCl filling from the interior of the SWCNT. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Progress in single-walled carbon nanotube based nanoelectromechanical systemsPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 13 2006Jannik C. Meyer Abstract We present torsional pendulums based on small bundles of single-walled carbon nanotubes and ultimately on individual single-walled carbon nanotubes. The nanotubes serve as mechanical support and torsional spring for a lithographically defined metal plate. The plate can be actuated in an electric field and the device is operated inside the transmission electron microscope. In comparison with previous works we have built mechanically much more fragile devices, i.e. almost three orders of magnitude heavier suspended metal structures, and metal blocks suspended on smaller diameter nanotubes. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Radiation force mediated by exciton of a carbon nanotubePHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 1 2009Hiroshi Ajiki Abstract Resonant radiation force exerted on a single-walled carbon nanotube is theoretically studied. Even under weak laser irradiation at room temperature, the acceleration of a nanotube caused by a radiation force becomes significantly large in the resonant excitation conditions of an exciton. The spectral peak frequencies of the acceleration are sensitive to the diameter of nanotubes and to the light polarization. These features are quite useful for nondestructive remote sorting and collection of nanotubes with desired structure and alignment. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Influence of initial mixing methods on melt-extruded single-walled carbon nanotube,polypropylene nanocompositesPOLYMER ENGINEERING & SCIENCE, Issue 9 2010Vinod K. Radhakrishnan We report the first direct comparison of melt-extruded polypropylene,single-walled carbon nanotube (PP/SWNT) nanocomposites prepared by three different initial mixing methods. The standard deviation of the G-band intensity obtained using Raman mapping was found to be the best measure of dispersion uniformity in the extruded composites, and dispersion uniformity was found to generally correlate with rheological and thermal properties. For all three initial mixing methods, both unmodified and sidewall-functionalized purified SWNTs were evaluated. Surprisingly, in all cases, dodecylated SWNTs prepared using the reductive alkylation method were less uniformly dispersed in the final composite than the unmodified SWNTs. The simplest process, dry blending, resulted in poor nanotube dispersion and only polymer crystallization was significantly affected by the presence of the nanotubes. A slightly more complex rotary evaporation process resulted in significantly more uniform dispersion and significant changes in rheological properties, polymer crystallization, and thermal stability. The most elaborate process tested, hot coagulation, enabled the most uniform dispersion and the greatest change in properties but also resulted in some polymer degradation. POLYM. ENG. SCI., 50:1831,1842, 2010. © 2010 Society of Plastics Engineers [source] Light-Driven Thermoelectric Conversion Based on a Carbon Nanotube,Ionic Liquid Gel CompositeCHEMSUSCHEM CHEMISTRY AND SUSTAINABILITY, ENERGY & MATERIALS, Issue 8 2009Eijiro Miyako Dr. A photoinduced thermoelectric conversion system based on single-walled carbon nanotube,room temperature ionic liquid composite gels is reported. These new types of gel-based near-infrared laser-driven thermoelectric convertors generate high electrical energy. [source] | |||||||||||||||||||||||||||||||||||||