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Sample records for nanotubes baytubes approach

  1. Pulmonary toxicity of multi-walled carbon nanotubes (Baytubes) relative to alpha-quartz following a single 6h inhalation exposure of rats and a 3 months post-exposure period.

    PubMed

    Ellinger-Ziegelbauer, Heidrun; Pauluhn, Jürgen

    2009-12-21

    Manufactured multi-walled carbon nanotubes (MWCNT) have attracted a great deal of attention due to their unique structural, chemical, and physical characteristics. This study utilized a 1x 6h inhalation exposure protocol followed by a 3 months post-exposure period. Wistar rats were nose-only exposed to 11 and 241 mg/m(3) MWCNT (Baytubes) of respirable, solid aerosol. MWCNT depleted of residual metals (depletion from 0.53% to 0.12% Co) were compared at 11 mg/m(3). Rats similarly exposed to air and alpha-quartz (248 mg/m(3)) served as negative and positive controls, respectively. Pulmonary response was characterized by bronchoalveolar lavage (BAL), lung histopathology, organ burden determinations, and gene expression analyses of lung homogenates with emphasis on extracellular matrix components. This acute inhalation exposure protocol was suitable to characterize and distinguish acute deposition-related effects from the long-term sequelae of retained MWCNT. Subtle differences in acute pulmonary toxic potency due to differences in metal contaminations could be revealed by this protocol. Consistent with the long retention halftime of poorly soluble particles, even short-term inhalation studies may require post-exposure periods of at least 3 months to reveal MWCNT-specific dispositional and toxicological characteristics relative to alpha-quartz. Distinct differences in the time course of pulmonary inflammation of MWCNT and alpha-quartz could be demonstrated. Transcriptomics proved to be a useful tool to analyze the etiopathology of collagen detected by BAL and histopathology. In summary, the pulmonary inflammogenicity following exposure to MWCNT was concentration-dependent with evidence of regression over time. Conversely, alpha-quartz resulted in progressive changes over time. The time course of pulmonary inflammation associated with retained MWCNT was independent on the concentration of residual cobalt. This supports the conclusion that the predominant response to

  2. Epitaxial Approaches to Carbon Nanotube Organization

    NASA Astrophysics Data System (ADS)

    Ismach, Ariel

    Carbon nanotubes have unique electronic, mechanical, optical and thermal properties, which make them ideal candidates as building blocks in nano-electronic and electromechanical systems. However, their organization into well-defined geometries and arrays on surfaces remains a critical challenge for their integration into functional nanosystems. In my PhD, we developed a new approach for the organization of carbon nanotubes directed by crystal surfaces. The principle relies on the guided growth of single-wall carbon nanotubes (SWNTs) by atomic features presented on anisotropic substrates. We identified three different modes of surface-directed growth (or 'nanotube epitaxy'), in which the growth of carbon nanotubes is directed by crystal substrates: We first observed the nanotube unidirectional growth along atomic steps ('ledge-directed epitaxy') and nanofacets ('graphoepitaxy') on the surface of miscut C-plane sapphire and quartz. The orientation along crystallographic directions ('lattice-directed epitaxy') was subsequently observed by other groups on different crystals. We have proposed a "wake growth" mechanism for the nanotube alignment along atomic steps and nanofacets. In this mechanism, the catalyst nanoparticle slides along the step or facet, leaving the nanotube behind as a wake. In addition, we showed that the combination of surface-directed growth with external forces, such as electric-field and gas flow, can lead to the simultaneous formation of complex nanotube structures, such as grids and serpentines. The "wake growth" model, which explained the growth of aligned nanotubes, could not explain the formation of nanotube serpentines. For the latter, we proposed a "falling spaghetti" mechanism, in which the nanotube first grows by a free-standing process, aligned in the direction of the gas flow, then followed by absorption on the stepped surface in an oscillatory manner, due to the competition between the drag force caused by the gas flow on the suspended

  3. Structure of ordered coaxial and scroll nanotubes: general approach.

    PubMed

    Khalitov, Zufar; Khadiev, Azat; Valeeva, Diana; Pashin, Dmitry

    2016-01-01

    The explicit formulas for atomic coordinates of multiwalled coaxial and cylindrical scroll nanotubes with ordered structure are developed on the basis of a common oblique lattice. According to this approach, a nanotube is formed by transfer of its bulk analogue structure onto a cylindrical surface (with a circular or spiral cross section) and the chirality indexes of the tube are expressed in the number of unit cells. The monoclinic polytypic modifications of ordered coaxial and scroll nanotubes are also discussed and geometrical conditions of their formation are analysed. It is shown that tube radii of ordered multiwalled coaxial nanotubes are multiples of the layer thickness, and the initial turn radius of the orthogonal scroll nanotube is a multiple of the same parameter or its half. PMID:26697865

  4. Synthetic approach from polypyrrole nanotubes to nitrogen doped pyrolyzed carbon nanotubes for asymmetric supercapacitors

    NASA Astrophysics Data System (ADS)

    Dubal, Deepak P.; Chodankar, Nilesh R.; Caban-Huertas, Zahilia; Wolfart, Franciele; Vidotti, Marcio; Holze, Rudolf; Lokhande, Chandrakant D.; Gomez-Romero, Pedro

    2016-03-01

    Pseudocapacitive materials are highly capable to achieve high energy density integrated with high power electrostatic capacitive materials. However, finding a suitable electrostatic capacitive material to integrate with pseudocapacitive material in order to achieve high energy density with good rate capability is still a challenge. Herein, we are providing a novel synthetic approach starting from the synthesis of polypyrrole nanotubes (PPy-NTs) and ending up at the carbonization of PPy-NTs to obtain N-doped carbon nanotubes (N-CNTs). With highly porous nature of PPy-NTs and great graphitic texture with copious heteroatom functionalities, N-CNTs significantly promoted the faradic pseudo-capacitors, demonstrating high single-electrode capacitance over 332 F/g(PPy-NTs) and 228 F/g(N-CNTs) in 1 M H2SO4 aqueous solution. Further, a novel asymmetric supercapacitor with PPy-NTs as positive and N-CNTs as negative electrode has been fabricated. This PPy-NTs//N-CNTs cell effectively provides high operation voltage (1.4 V) and hence high energy density over 28.95 W h/kg (0.41 mW h/cm3) with a high power density of 7.75 kW/kg (113 mW/cm3) and cyclic stability of 89.98% after 2000 cycles.

  5. Nanotube

    Energy Science and Technology Software Center (ESTSC)

    2007-09-13

    This is a source code to calculate the current-voltage characteristics, the charge distribution and the electrostatic potential in carbon nanotube devices. The code utilizes the non-equilibrium Green's function method, implemented in a tight-binding scheme, to calculate the charge distribution and the energy-dependent transmission function, from which the current or the conductance are obtained. The electrostatic potential is obtained by solving Poisson's equation on a grid with boundary conditions on the electrodes, and at other interfaces.more » Self-consistency between the charge and the electrostatic potential is achieved using a linear mixing method. Different versions of the code allow the modeling of different types of nanotube devices: Version 1.0: Modeling of carbon nanotube electronic devices with cylindrical symmetry Version 1.1: Modeling of planar carbon nanotube electronic devices Version 1.2: Modeling of photocurrent in carbon nanotube devices« less

  6. Thermodynamic approach to boron nitride nanotube solubility and dispersion

    NASA Astrophysics Data System (ADS)

    Tiano, A. L.; Gibbons, L.; Tsui, M.; Applin, S. I.; Silva, R.; Park, C.; Fay, C. C.

    2016-02-01

    Inadequate dispersion of nanomaterials is a critical issue that significantly limits the potential properties of nanocomposites and when overcome, will enable further enhancement of material properties. The most common methods used to improve dispersion include surface functionalization, surfactants, polymer wrapping, and sonication. Although these approaches have proven effective, they often achieve dispersion by altering the surface or structure of the nanomaterial and ultimately, their intrinsic properties. Co-solvents are commonly utilized in the polymer, paint, and art conservation industries to selectively dissolve materials. These co-solvents are utilized based on thermodynamic interaction parameters and are chosen so that the original materials are not affected. The same concept was applied to enhance the dispersion of boron nitride nanotubes (BNNTs) to facilitate the fabrication of BNNT nanocomposites. Of the solvents tested, dimethylacetamide (DMAc) exhibited the most stable, uniform dispersion of BNNTs, followed by N,N-dimethylformamide (DMF), acetone, and N-methyl-2-pyrrolidone (NMP). Utilizing the known Hansen solubility parameters of these solvents in comparison to the BNNT dispersion state, a region of good solubility was proposed. This solubility region was used to identify co-solvent systems that led to improved BNNT dispersion in poor solvents such as toluene, hexane, and ethanol. Incorporating the data from the co-solvent studies further refined the proposed solubility region. From this region, the Hansen solubility parameters for BNNTs are thought to lie at the midpoint of the solubility sphere: 16.8, 10.7, and 9.0 MPa1/2 for δd, δp, and δh, respectively, with a calculated Hildebrand parameter of 21.8 MPa1/2.Inadequate dispersion of nanomaterials is a critical issue that significantly limits the potential properties of nanocomposites and when overcome, will enable further enhancement of material properties. The most common methods used to

  7. Thermodynamic approach to boron nitride nanotube solubility and dispersion.

    PubMed

    Tiano, A L; Gibbons, L; Tsui, M; Applin, S I; Silva, R; Park, C; Fay, C C

    2016-02-21

    Inadequate dispersion of nanomaterials is a critical issue that significantly limits the potential properties of nanocomposites and when overcome, will enable further enhancement of material properties. The most common methods used to improve dispersion include surface functionalization, surfactants, polymer wrapping, and sonication. Although these approaches have proven effective, they often achieve dispersion by altering the surface or structure of the nanomaterial and ultimately, their intrinsic properties. Co-solvents are commonly utilized in the polymer, paint, and art conservation industries to selectively dissolve materials. These co-solvents are utilized based on thermodynamic interaction parameters and are chosen so that the original materials are not affected. The same concept was applied to enhance the dispersion of boron nitride nanotubes (BNNTs) to facilitate the fabrication of BNNT nanocomposites. Of the solvents tested, dimethylacetamide (DMAc) exhibited the most stable, uniform dispersion of BNNTs, followed by N,N-dimethylformamide (DMF), acetone, and N-methyl-2-pyrrolidone (NMP). Utilizing the known Hansen solubility parameters of these solvents in comparison to the BNNT dispersion state, a region of good solubility was proposed. This solubility region was used to identify co-solvent systems that led to improved BNNT dispersion in poor solvents such as toluene, hexane, and ethanol. Incorporating the data from the co-solvent studies further refined the proposed solubility region. From this region, the Hansen solubility parameters for BNNTs are thought to lie at the midpoint of the solubility sphere: 16.8, 10.7, and 9.0 MPa(1/2) for δd, δp, and δh, respectively, with a calculated Hildebrand parameter of 21.8 MPa(1/2). PMID:26839175

  8. A multiscale approach for estimating the chirality effects in carbon nanotube reinforced composites

    NASA Astrophysics Data System (ADS)

    Joshi, Unnati A.; Sharma, Satish C.; Harsha, S. P.

    2012-08-01

    In this paper, the multiscale representative volume element approach is proposed for modeling the elastic behavior of carbon nanotubes reinforced composites. The representative volume element incorporates the continuum approach, while carbon nanotube characterizes the atomistic approach. Space frame structure similar to three dimensional beams and point masses are employed to simulate the discrete geometrical constitution of the single walled carbon nanotube. The covalent bonds between carbon atoms found in the hexagonal lattices are assigned elastic properties using beam elements. The point masses applied on each node are coinciding with the carbon atoms work as mass of beam elements. The matrix phase is modeled as a continuum medium using solid elements. These two regions are interconnected by interfacial zone using beam elements. Analysis of nanocomposites having single walled carbon nanotube with different chiralities is performed, using an atomistic finite element model based on a molecular structural mechanics approach. Using the proposed multi scale model, the deformations obtained from the simulations are used to predict the elastic and shear moduli of the nanocomposites. A significant enhancement in the stiffness of the nanocomposites is observed. The effects of interfacial shear strength, stiffness, tensile strength, chirality, length of carbon nanotube, material of matrix, types of representative volume elements and types of loading conditions on the mechanical behavior of the nanocomposites are estimated. The finite element results are compared with the rule of mixtures using formulae. It is found that the results offered by proposed model, are in close proximity with those obtained by the rule of mixtures.

  9. A room temperature approach for the fabrication of aligned TiO₂ nanotube arrays on transparent conductive substrates.

    PubMed

    Zeng, Ruosha; Li, Ke; Sheng, Xia; Chen, Liping; Zhang, Haijiao; Feng, Xinjian

    2016-03-14

    A novel solution approach is reported for the fabrication of TiO₂ nanotube arrays on transparent conductive substrates via in situ conversion from nanowires. The as-prepared nanotube arrays not only demonstrate a larger surface area in comparison with the primary NWs, but also longer charge carrier lifetime than that of randomly packed nanoparticle films. PMID:26892268

  10. A general approach towards carbon nanotube and iron oxide coaxial architecture and its lithium storage capability

    NASA Astrophysics Data System (ADS)

    Zhang, Ling; Ni, Jiangfeng; Wang, Wencong; Li, Liang

    2015-12-01

    Coaxial architectures consisting of metal oxide and carbon nanotube are promising for many energy applications due to their synergetic interaction. The engineering and development of coaxial structures through a simple approach are highly desirable but remain a challenge. Herein, we present a general and facile ethylene glycol bath approach to fabricate coaxial architectures in which the metal oxide component is sandwiched by carbon nanotube and amorphous carbon. These unique architectures can serve as efficient electrode for lithium storage. The internal carbon nanotube allows rapid electron transport, while the external amorphous carbon acts as flexible buffer to accommodate volume variation upon lithium uptake. When evaluated in lithium cells, the carbon nanotube and iron oxide coaxial material exhibits a remarkable electrochemical lithium storage. It affords a capacity of 1083 mAh g-1 over 60 cycles, and retains 529 mAh g-1 at a high rate of 5 A g-1, drastically outperforming the pure iron oxide counterpart. This facile approach is in principle applicable to constructing other coaxial electrodes, and thus holds great potential in the manipulation of battery materials for lithium storage application.

  11. DNA Linked To Single Wall Carbon Nanotubes: Covalent Versus Non-Covalent Approach

    NASA Astrophysics Data System (ADS)

    Chung, C.-L.; Nguyen, K.; Lyonnais, S.; Streiff, S.; Campidelli, S.; Goux-Capes, L.; Bourgoin, J.-P.; Filoramo, A.

    2008-10-01

    Nanometer-scale structures represent a novel and intriguing field, where scientists and engineers manipulate materials at the atomic and molecular scale levels to produce innovative materials. Carbon nanotubes constitute a relatively new class of materials exhibiting exceptional mechanical and electronic properties and were found to be promising candidates for molecular electronics, sensing or biomedical applications. Considering the bottom-up strategy in nanotechnology, the combination of the recognition properties of DNA with the electronic properties of single walled carbon nanotubes (SWNTs) seems to be a promising approach for the future of electronics. With the aim to assemble DNA with SWNTs, two complementary strategies have been envisioned: the covalent linkage of DNA on carboxylic groups of SWNTs under classical coupling condition and the non-covalent approach based on biotin-streptavidin molecular recognition properties. Here, we present and compare the results that we obtained with these two different methods; we want to objectively show the advantages and disadvantages of each approach.

  12. A single-molecule approach to explore binding, uptake and transport of cancer cell targeting nanotubes

    NASA Astrophysics Data System (ADS)

    Lamprecht, C.; Plochberger, B.; Ruprecht, V.; Wieser, S.; Rankl, C.; Heister, E.; Unterauer, B.; Brameshuber, M.; Danzberger, J.; Lukanov, P.; Flahaut, E.; Schütz, G.; Hinterdorfer, P.; Ebner, A.

    2014-03-01

    In the past decade carbon nanotubes (CNTs) have been widely studied as a potential drug-delivery system, especially with functionality for cellular targeting. Yet, little is known about the actual process of docking to cell receptors and transport dynamics after internalization. Here we performed single-particle studies of folic acid (FA) mediated CNT binding to human carcinoma cells and their transport inside the cytosol. In particular, we employed molecular recognition force spectroscopy, an atomic force microscopy based method, to visualize and quantify docking of FA functionalized CNTs to FA binding receptors in terms of binding probability and binding force. We then traced individual fluorescently labeled, FA functionalized CNTs after specific uptake, and created a dynamic ‘roadmap’ that clearly showed trajectories of directed diffusion and areas of nanotube confinement in the cytosol. Our results demonstrate the potential of a single-molecule approach for investigation of drug-delivery vehicles and their targeting capacity.

  13. Modeling of Carbon Nanotube Composites Based on Nonlocal Elasticity Approach

    NASA Astrophysics Data System (ADS)

    Alavinasab, Ali; Jha, Ratneshwar; Ahmadi, G.

    2014-01-01

    Nonlocal continuum theory is studied for modeling stress distributions in nanocomposites. The second-order approximation in nonlocal theory is considered since the first-order approximation leads to an unacceptable solution. A representative volume element (RVE) of CNT composite is utilized to derive unknown constants in the nonlocal theory model. Stress distributions in RVE using nonlocal theory, classical elasticity, and finite element method are obtained. All three approaches yield the same force, but classical elasticity gives an incorrect value of first moment. Wave propagation studies show that the dispersion curve obtained by nonlocal theory is quite close to the atomic Born-von Karman model.

  14. Temperature dependence of strain energy and thermodynamic properties of V2 O5 -based single-walled nanotubes: Zone-folding approach.

    PubMed

    Porsev, Vitaly V; Bandura, Andrei V; Evarestov, Robert A

    2016-06-15

    A zone-folding approach is applied to estimate the thermodynamic properties of V2 O5 -based nanotubes. The results obtained are compared with those from the direct calculations. It is shown that the zone-folding approximation allows an accurate estimation of nanotube thermodynamic properties and gives a gain in computation time compared to their direct calculations. Both approaches show that temperature effects do not change the relative stability of V2 O5 free layers and nanotubes derived from the α- and γ-phase. The internal energy thermal contributions into the strain energy of nanotubes are small and can be ignored. © 2016 Wiley Periodicals, Inc. PMID:26990664

  15. A doping-free approach to carbon nanotube electronics and optoelectronics

    NASA Astrophysics Data System (ADS)

    Peng, Lian-Mao; Zhang, Zhiyong; Wang, Sheng; Liang, Xuelei

    2012-12-01

    The electronic properties of conventional semiconductor are usually controlled by doping, which introduces carriers into the semiconductor but also distortion and scattering centers to the otherwise perfect lattice, leading to increased scattering and power consumption that becomes the limiting factors for the ultimate performance of the next generation electronic devices. Among new materials that have been considered as potential replacing channel materials for silicon, carbon nanotubes (CNTs) have been extensively studied and shown to have all the remarkable electronic properties that an ideal electronic material should have, but controlled doping in CNTs has been proved to be challenging. In this article we will review a doping-free approach for constructing nanoelectronic and optoelectronic devices and integrated circuits. This technique relies on a unique property of CNTs, i.e. high quality ohmic contacts can be made to both the conduction band and valence band of a semiconducting CNT. High performance nanoelectronic and optoelectronic devices have been fabricated using CNTs with this method and performance approach to that of quantum limit. In principle high performance electronic devices and optoelectronic devices can be integrated on the same carbon nanotube with the same footing, and this opens new possibilities for electronics beyond the Moore law in the future.

  16. On the continuum mechanics approach for the analysis of single walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Chaudhry, M. S.; Czekanski, A.

    2016-04-01

    Today carbon nanotubes have found various applications in structural, thermal and almost every field of engineering. Carbon nanotubes provide great strength, stiffness resilience properties. Evaluating the structural behavior of nanoscale materials is an important task. In order to understand the materialistic behavior of nanotubes, atomistic models provide a basis for continuum mechanics modelling. Although the properties of bulk materials are consistent with the size and depends mainly on the material but the properties when we are in Nano-range, continuously change with the size. Such models start from the modelling of interatomic interaction. Modelling and simulation has advantage of cost saving when compared with the experiments. So in this project our aim is to use a continuum mechanics model of carbon nanotubes from atomistic perspective and analyses some structural behaviors of nanotubes. It is generally recognized that mechanical properties of nanotubes are dependent upon their structural details. The properties of nanotubes vary with the varying with the interatomic distance, angular orientation, radius of the tube and many such parameters. Based on such models one can analyses the variation of young's modulus, strength, deformation behavior, vibration behavior and thermal behavior. In this study some of the structural behaviors of the nanotubes are analyzed with the help of continuum mechanics models. Using the properties derived from the molecular mechanics model a Finite Element Analysis of carbon nanotubes is performed and results are verified. This study provides the insight on continuum mechanics modelling of nanotubes and hence the scope to study the effect of various parameters on some structural behavior of nanotubes.

  17. A substrate-integrated and scalable templated approach based on rusted steel for the fabrication of polypyrrole nanotube arrays.

    PubMed

    Velazquez, Jesus M; Gaikwad, Anil V; Rout, Tapan K; Rzayev, Javid; Banerjee, Sarbajit

    2011-04-01

    We report here a facile, generalizable, and entirely scalable approach for the fabrication of vertically aligned arrays of Fe(2)O(3)/polypyrrole core-shell nanostructures and polypyrrole nanotubes. Our "all electrochemical" approach is based on the fabrication of α-Fe(2)O(3) nanowire arrays by the simple heat treatment of commodity low carbon steel substrates, followed by electropolymerization of conformal polypyrrole sheaths around the nanowires. Subsequently, electrochemical etching of the nanowires yields large-area vertically aligned polypyrrole nanotube arrays on the steel substrate. The developed methodology is generalizable to functionalized pyrrole monomers and represents a significant practical advance of relevance to the technological implementation of conjugated polymer nanostructures in electrochromics, electrochemical energy storage, and sensing. PMID:21425803

  18. A Substrate-Integrated and Scalable Templated Approach Based on Rusted Steel for the Fabrication of Polypyrrole Nanotube Arrays

    SciTech Connect

    J Velazquez; A Gaikwad; T Rout; J Rzayev; S Banerjee

    2011-12-31

    We report here a facile, generalizable, and entirely scalable approach for the fabrication of vertically aligned arrays of Fe{sub 2}O{sub 3}/polypyrrole core-shell nanostructures and polypyrrole nanotubes. Our 'all electrochemical' approach is based on the fabrication of {alpha}-Fe{sub 2}O{sub 3} nanowire arrays by the simple heat treatment of commodity low carbon steel substrates, followed by electropolymerization of conformal polypyrrole sheaths around the nanowires. Subsequently, electrochemical etching of the nanowires yields large-area vertically aligned polypyrrole nanotube arrays on the steel substrate. The developed methodology is generalizable to functionalized pyrrole monomers and represents a significant practical advance of relevance to the technological implementation of conjugated polymer nanostructures in electrochromics, electrochemical energy storage, and sensing.

  19. Plumbing carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Jin, Chuanhong; Suenaga, Kazu; Iijima, Sumio

    2008-01-01

    Since their discovery, the possibility of connecting carbon nanotubes together like water pipes has been an intriguing prospect for these hollow nanostructures. The serial joining of carbon nanotubes in a controlled manner offers a promising approach for the bottom-up engineering of nanotube structures-from simply increasing their aspect ratio to making integrated carbon nanotube devices. To date, however, there have been few reports of the joining of two different carbon nanotubes. Here we demonstrate that a Joule heating process, and associated electro-migration effects, can be used to connect two carbon nanotubes that have the same (or similar) diameters. More generally, with the assistance of a tungsten metal particle, this technique can be used to seamlessly join any two carbon nanotubes-regardless of their diameters-to form new nanotube structures.

  20. Effects of interfacial bonding in the Si-carbon nanotube nanocomposite: A molecular dynamics approach

    NASA Astrophysics Data System (ADS)

    Kim, Byung-Hyun; Lee, Kwang-Ryeol; Chung, Yong-Chae; Gunn Lee, June

    2012-08-01

    We investigated the effects of interfacial bonding on the mechanical properties in the Si-carbon nanotube (CNT) nanocomposite by a molecular dynamics approach. To describe the system appropriately, we used a hybrid potential that includes Tersoff, AIREBO (adaptive intermolecular reactive empirical bond order), and Lennard-Jones potentials. With increasing bonding strength at the interface of Si matrix and CNT, toughness as well as Young's modulus and maximum strength increased steadily. CNT pull-out and load transfer on the strong CNT were identified as the main mechanisms for the enhanced properties. At optimum bonding, crack tip was deflected around CNT and the fracture proceeded in plastic mode through Si matrix owing to the strong reinforcement of CNT, and resulted in a further enhancement of toughness. At maximum bonding, however, only load transfer is operative and the fracture returned to brittle mode. We concluded that a strong interface as long as the CNT maintains its structural integrity is desirable to realize the optimum result.

  1. Lagrangian Approach to Jet Mixing and Optimization of the Reactor for Production of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Povitsky, Alex; Salas, Manuel D.

    2001-01-01

    This study was motivated by an attempt to optimize the High Pressure carbon oxide (HiPco) process for the production of carbon nanotubes from gaseous carbon oxide, The goal is to achieve rapid and uniform heating of catalyst particles by an optimal arrangement of jets. A mixed Eulerian and Lagrangian approach is implemented to track the temperature of catalyst particles along their trajectories as a function of time. The FLUENT CFD software with second-order upwind approximation of convective terms and an algebraic multigrid-based solver is used. The poor performance of the original reactor configuration is explained in terms of features of particle trajectories. The trajectories most exposed to the hot jets appear to be the most problematic for heating because they either bend towards the cold jet interior or rotate upwind of the mixing zone. To reduce undesirable slow and/or oscillatory heating of catalyst particles, a reactor configuration with three central jets is proposed and the optimal location of the central and peripheral nozzles is determined.

  2. New approaches for carbon nanotubes-based biosensors and their application to cell culture monitoring.

    PubMed

    Boero, Cristina; Olivo, Jacopo; De Micheli, Giovanni; Carrara, Sandro

    2012-10-01

    Amperometric biosensors are complex systems and they require a combination of technologies for their development. The aim of the present work is to propose a new approach in order to develop nanostructured biosensors for the real-time detection of multiple metabolites in cell culture flasks. The fabrication of five Au working electrodes onto silicon substrate is achieved with CMOS compatible microtechnology. Each working electrode presents an area of 0.25 mm², so structuration with carbon nanotubes and specific functionalization are carried out by using spotting technology, originally developed for microarrays and DNA printing. The electrodes are characterized by cyclic voltammetry and compared with commercially available screen-printed electrodes. Measurements are carried out under flow conditions, so a simple fluidic system is developed to guarantee a continuous flow next to the electrodes. The working electrodes are functionalized with different enzymes and calibrated for the real-time detection of glucose, lactate, and glutamate. Finally, some tests are performed on surnatant conditioned medium sampled from neuroblastoma cells (NG-108 cell line) to detect glucose and lactate concentration after 72 hours of cultivation. The developed biosensor for real-time and online detection of multiple metabolites shows very promising results towards circuits and systems for cell culture monitoring. PMID:23853234

  3. a Diffusive-Transport Approach to Determine the Electrical Conductance of AN Imperfect Multiwalled Carbon Nanotube

    NASA Astrophysics Data System (ADS)

    Grado-Caffaro, Maria Angeles; Grado-Caffaro, Martin

    2014-05-01

    In this paper, we propose a diffusive-transport-based analytical formulation to calculate the linear electrical conductance through a multiwalled carbon nanotube with defects. In fact, on the one hand, by considerations on diffusive transport and, on the other hand, using the Drude model, we find out that the conductance (at Fermi energy) of an imperfect multiwalled carbon nanotube is approximately equal to the fundamental conductance quantum multiplied by the number of layers (or shells) of the tube. Our result agrees with experimental data.

  4. Covalent sidewall functionalization of single-walled carbon nanotubes: a photoreduction approach.

    PubMed

    Wei, Liangming; Zhang, Yafei

    2007-12-12

    Covalent sidewall functionalization of single-walled carbon nanotubes (SWNTs) via photoreduction of aromatic ketones by alcohols is reported for the first time. Irradiation of benzophenone, benzhydrol and SWNTs in benzene resulted in covalent attachment of benzhydrol to the sidewalls of the SWNTs. A variety of tools were used to characterize the functionalized SWNTs. Raman scattering, UV-visible and near-IR spectroscopy confirm the covalent nature of the sidewall functionalization. Attenuated total reflection (ATR) FTIR and NMR provided evidence for attachment of benzhydrol onto the sidewalls of nanotubes. Thermogravimetric analysis (TGA) showed that the degree of functionalization was about one benzhydrol in 52 sidewall carbons. A long-chain hydrocarbon marker (n-C(18)H(35)) was also grafted onto the functional groups by esterification reaction for high-resolution TEM (HRTEM) visualization. PMID:20442484

  5. Theoretical study of electronic transport through quasicrystalline nanotubes using mesh inflation approach

    NASA Astrophysics Data System (ADS)

    Ho, I.-Lin; Chou, Chung-Hsien; Chang, Yia-Chung

    2014-05-01

    This work introduces the mesh inflation method to construct (dodecagonal) quasicrystalline shell structures, and investigates the properties and functions of quantum transport through quasiperiodic components, e.g. the nanotube device. We model the quantum dynamics of a system described by a nearest neighbor tight-binding formulism, and apply the non-equilibrium Green’s function technique to calculate the electronic transport properties, in which the non-equilibrium (transmitted) electronic density is self-consistently determined by solving Poisson’s equation in capacitive network modeling. Numerical results find that the transmission spectrum of the quasicrystalline nanotube illustrates crossover characteristics from local order (like in periodic lattices) to global disorder (like in amorphous solids) with varying energy. Moreover, the electronic transport properties of nanoprobes through multiple atomic channels follow the rule of Landauer’s formula.

  6. Thermodynamic Approach to Enhanced Dispersion and Physical Properties in a Carbon Nanotube/Polypeptide Nanocomposite

    NASA Technical Reports Server (NTRS)

    Lovell, Conrad S.; Wise, Kristopher E.; Kim, Jae-Woo; Lillehei, Peter T.; Harrison, Joycelyn S.; Park, Cheol

    2009-01-01

    A high molecular weight synthetic polypeptide has been designed which exhibits favorable interactions with single wall carbon nanotubes (SWCNTs). The enthalpic and entropic penalties of mixing between these two molecules are reduced due to the polypeptide's aromatic sidechains and helical secondary structure, respectively. These enhanced interactions result in a well dispersed SWCNT/Poly (L-Leucine-ran-L-Phenylalanine) nanocomposite with enhanced mechanical and electrical properties using only shear mixing and sonication. At 0.5 wt% loading of SWCNT filler, the nanocomposite exhibits simultaneous increases in the Young's modulus, failure strain, and toughness of 8%, 120%, and 144%, respectively. At one kHz, the same nanotube loading level also enhances the dielectric constant from 2.95 to 22.81, while increasing the conductivity by four orders of magnitude.

  7. Biocompatibility of Carbon Nanotubes in Mammalian Cells: An Imaging Based Approach

    NASA Astrophysics Data System (ADS)

    Chen, Howard; Lucas, Jessica; Ponek, Hannah; Evans, Christopher; Baer, Bradly; Choung, Sara; Chen, Michelle

    2012-02-01

    Carbon nanotubes have been widely researched for ultrasensitive biomolecule detection and drug delivery. However, its impact on cells is yet to be fully characterized, mainly due to the complex biological in vivo environment. We report here a mammalian cell-imaging paradigm to study the cellular response to single-walled carbon nanotubes (SWNTs) at the single-cell level. Chinese Hamster Ovarian cells were exposed to SWNTs resuspended in phosphate buffered saline (PBS) at various concentrations. Upon exposure, we optically imaged the cells (1) to visually quantify the SWNTs' crossing of the cell membrane in real-time; (2) to both qualitatively and quantitatively assess the morphological changes associated with cellular stress in the presence of SWNTs; and (3) to serially quantify cell survival with highly sensitive bioluminescence-based imaging. Consistent with literature reports, high concentration of SWNTs acutely compromised cell division and decreased cell survival. Low concentrations were well tolerated by the cells initially but had similar effects after prolonged exposure. We discuss the inter-relationships among the cell morphology, viability, and intracellular SWNT uptake parameters, as a function of nanotube concentration and exposure time.

  8. Safety Evaluation of Engineered Nanomaterials for Health Risk Assessment: An Experimental Tiered Testing Approach Using Pristine and Functionalized Carbon Nanotubes

    PubMed Central

    Coccini, Teresa; Manzo, Luigi; Roda, Elisa

    2013-01-01

    Increasing application of engineered nanomaterials within occupational, environmental, and consumer settings has raised the levels of public concern regarding possible adverse effects on human health. We applied a tiered testing strategy including (i) a first in vitro stage to investigate general toxicity endpoints, followed by (ii) a focused in vivo experiment. Cytotoxicity of laboratory-made functionalized multiwalled carbon nanotubes (CNTs) (i.e., MW-COOH and MW-NH2), compared to pristine MWCNTs, carbon black, and silica, has been assessed in human A549 pneumocytes by MTT assay and calcein/propidium iodide (PI) staining. Purity and physicochemical properties of the test nanomaterials were also determined. Subsequently, pulmonary toxic effects were assessed in rats, 16 days after MWCNTs i.t. administration (1 mg/kg b.w.), investigating lung histopathology and monitoring several markers of lung toxicity, inflammation, and fibrosis. In vitro data: calcein/PI test indicated no cell viability loss after all CNTs treatment; MTT assay showed false positive cytotoxic response, occurring not dose dependently at exceedingly low CNT concentrations (1 μg/mL). In vivo results demonstrated a general pulmonary toxicity coupled with inflammatory response, without overt signs of fibrosis and granuloma formation, irrespective of nanotube functionalization. This multitiered approach contributed to clarifying the CNT toxicity mechanisms improving the overall understanding of the possible adverse outcomes resulting from CNT exposure. PMID:23724301

  9. Carbon Nanotube Purification and Functionalization

    NASA Technical Reports Server (NTRS)

    Lebron, Marisabel; Mintz, Eric; Smalley, Richard E.; Meador, Michael A.

    2003-01-01

    Carbon nanotubes have the potential to significantly enhance the mechanical, thermal, and electrical properties of polymers. However, dispersion of carbon nanotubes in a polymer matrix is hindered by the electrostatic forces that cause them to agglomerate. Chemical modification of the nanotubes is necessary to minimize these electrostatic forces and promote adhesion between the nanotubes and the polymer matrix. In a collaborative research program between Clark Atlanta University, Rice University, and NASA Glenn Research Center several approaches are being explored to chemically modify carbon nanotubes. The results of this research will be presented.

  10. Magnetic nanotubes

    DOEpatents

    Matsui, Hiroshi; Matsunaga, Tadashi

    2010-11-16

    A magnetic nanotube includes bacterial magnetic nanocrystals contacted onto a nanotube which absorbs the nanocrystals. The nanocrystals are contacted on at least one surface of the nanotube. A method of fabricating a magnetic nanotube includes synthesizing the bacterial magnetic nanocrystals, which have an outer layer of proteins. A nanotube provided is capable of absorbing the nanocrystals and contacting the nanotube with the nanocrystals. The nanotube is preferably a peptide bolaamphiphile. A nanotube solution and a nanocrystal solution including a buffer and a concentration of nanocrystals are mixed. The concentration of nanocrystals is optimized, resulting in a nanocrystal to nanotube ratio for which bacterial magnetic nanocrystals are immobilized on at least one surface of the nanotubes. The ratio controls whether the nanocrystals bind only to the interior or to the exterior surfaces of the nanotubes. Uses include cell manipulation and separation, biological assay, enzyme recovery, and biosensors.

  11. Effective approach to strengthening TiO2 nanotube arrays by using double or triple reinforcements

    NASA Astrophysics Data System (ADS)

    Sun, Mengwei; Yu, Dongliang; Lu, Linfeng; Ma, Weihua; Song, Ye; Zhu, Xufei

    2015-08-01

    Porous anodic TiO2 nanotube arrays (TNTAs) are fragile and also susceptible to be damaged during physical manipulation. Few studies have involved the improvement of the poor interfacial adhesion of TNTAs to the Ti substrate. Here, the poor adhesion of TNTAs was dramatically improved by appending an additional compact layer (ACL) formed at the interface between TNTAs and the Ti substrate. The adhesion of TNTAs with single-ACL increased with the increase of the ACL thickness. Furthermore, the reinforced TNTAs with double-ACL and triple-ACL have been successfully developed for the first time. The experimental results indicated that the critical load of the TNTAs with triple-ACL is roughly 5.8 times higher than that of the untreated TNTAs. The present results may be helpful to assemble less brittle and large area TNTAs for extensive applications.

  12. Photovoltaics based on nanotubes filled with nanoparticles: generalized Mie theory approach

    NASA Astrophysics Data System (ADS)

    Dhayal, Suman; Sapkota, Gopal; Philipose, Usha; Rostovtsev, Yuri

    2013-01-01

    Gold nanoparticles have interesting properties of nano-antennas that focus the radiation field into relatively small, much smaller than the wavelength of radiation, regions. Optical and electronic properties of nano-wires experiencing huge field enhancement can be modified due to these plasmonic interactions. We have developed a generalized Mie theory to demonstrate the effect of enhancement of the electric field near gold nanoparticles and study novel optical and electronic properties of these new structures: nanotubes filled with metal nanoparticles and nano-wires with metal nanoparticles as inclusions on their surface. In the paper, we discuss the applications of such novel nanoscale hybrid metal/semiconductor composites to sensitive sensors and efficient photovoltaics.

  13. Magnon specific heat and free energy of Heisenberg ferromagnetic single-walled nanotubes: Green's function approach

    NASA Astrophysics Data System (ADS)

    Mi, Bin-Zhou; Zhai, Liang-Jun; Hua, Ling-Ling

    2016-01-01

    The effect of magnetic spin correlation on the thermodynamic properties of Heisenberg ferromagnetic single-walled nanotubes are comprehensively investigated by use of the double-time Green's function method. The influence of temperature, spin quantum number, diameter of the tube, anisotropy strength and external magnetic field to internal energy, free energy, and magnon specific heat are carefully calculated. Compared to the mean field approximation, the consideration of the magnetic correlation effect significantly improves the internal energy values at finite temperature, while it does not so near zero temperature, and this effect is related to the diameter of the tube, anisotropy strength, and spin quantum number. The magnetic correlation effect lowers the internal energy at finite temperature. As a natural consequence of the reduction of the internal energy, the specific heat is reduced, and the free energy is elevated.

  14. Boron nitride nanotube-based biosensing of various bacterium/viruses: continuum modelling-based simulation approach.

    PubMed

    Panchal, Mitesh B; Upadhyay, Sanjay H

    2014-09-01

    In this study, the feasibility of single walled boron nitride nanotube (SWBNNT)-based biosensors has been ensured considering the continuum modelling-based simulation approach, for mass-based detection of various bacterium/viruses. Various types of bacterium or viruses have been taken into consideration at the free-end of the cantilevered configuration of the SWBNNT, as a biosensor. Resonant frequency shift-based analysis has been performed with the adsorption of various bacterium/viruses considered as additional mass to the SWBNNT-based sensor system. The continuum mechanics-based analytical approach, considering effective wall thickness has been considered to validate the finite element method (FEM)-based simulation results, based on continuum volume-based modelling of the SWBNNT. As a systematic analysis approach, the FEM-based simulation results are found in excellent agreement with the analytical results, to analyse the SWBNNTs for their wide range of applications such as nanoresonators, biosensors, gas-sensors, transducers and so on. The obtained results suggest that by using the SWBNNT of smaller size the sensitivity of the sensor system can be enhanced and detection of the bacterium/virus having mass of 4.28 × 10⁻²⁴ kg can be effectively performed. PMID:25082222

  15. Carbon nanotube macroelectronics

    NASA Astrophysics Data System (ADS)

    Zhang, Jialu

    In this dissertation, I discuss the application of carbon nanotubes in macroelectronis. Due to the extraordinary electrical properties such as high intrinsic carrier mobility and current-carrying capacity, single wall carbon nanotubes are very desirable for thin-film transistor (TFT) applications such as flat panel display, transparent electronics, as well as flexible and stretchable electronics. Compared with other popular channel material for TFTs, namely amorphous silicon, polycrystalline silicon and organic materials, nanotube thin-films have the advantages of low-temperature processing compatibility, transparency, and flexibility, as well as high device performance. In order to demonstrate scalable, practical carbon nanotube macroelectroncis, I have developed a platform to fabricate high-density, uniform separated nanotube based thin-film transistors. In addition, many other essential analysis as well as technology components, such as nanotube film density control, purity and diameter dependent semiconducting nanotube electrical performance study, air-stable n-type transistor fabrication, and CMOS integration platform have also been demonstrated. On the basis of the above achievement, I have further demonstrated various kinds of applications including AMOLED display electronics, PMOS and CMOS logic circuits, flexible and transparent electronics. The dissertation is structured as follows. First, chapter 1 gives a brief introduction to the electronic properties of carbon nanotubes, which serves as the background knowledge for the following chapters. In chapter 2, I will present our approach of fabricating wafer-scale uniform semiconducting carbon nanotube thin-film transistors and demonstrate their application in display electronics and logic circuits. Following that, more detailed information about carbon nanotube thin-film transistor based active matrix organic light-emitting diode (AMOLED) displays is discussed in chapter 3. And in chapter 4, a technology to

  16. Artificial neural network approach for atomic coordinate prediction of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Acı, Mehmet; Avcı, Mutlu

    2016-07-01

    In this paper, four artificial neural network (ANN) models [i.e., feed-forward neural network (FFNN), function fitting neural network (FITNET), cascade-forward neural network (CFNN) and generalized regression neural network] have been developed for atomic coordinate prediction of carbon nanotubes (CNTs). The research reported in this study has two primary objectives: (1) to develop ANN prediction models that calculate atomic coordinates of CNTs instead of using any simulation software and (2) to use results of the ANN models as an initial value of atomic coordinates for reducing number of iterations in calculation process. The dataset consisting of 10,721 data samples was created by combining the atomic coordinates of elements and chiral vectors using BIOVIA Materials Studio CASTEP (CASTEP) software. All prediction models yield very low mean squared normalized error and mean absolute error rates. Multiple correlation coefficient (R) results of FITNET, FFNN and CFNN models are close to 1. Compared with CASTEP, calculation times decrease from days to minutes. It would seem possible to predict CNTs' atomic coordinates using ANN models can be successfully used instead of mathematical calculations.

  17. Large-Scale Processing of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Finn, John; Sridhar, K. R.; Meyyappan, M.; Arnold, James O. (Technical Monitor)

    1998-01-01

    Scale-up difficulties and high energy costs are two of the more important factors that limit the availability of various types of nanotube carbon. While several approaches are known for producing nanotube carbon, the high-powered reactors typically produce nanotubes at rates measured in only grams per hour and operate at temperatures in excess of 1000 C. These scale-up and energy challenges must be overcome before nanotube carbon can become practical for high-consumption structural and mechanical applications. This presentation examines the issues associated with using various nanotube production methods at larger scales, and discusses research being performed at NASA Ames Research Center on carbon nanotube reactor technology.

  18. Exploring the sensitivity of ZnO nanotubes to tyrosine nitration: A DFT approach

    NASA Astrophysics Data System (ADS)

    Maddahi, Pari Sadat; Shahtahmassebi, Nasser; Rezaee Roknabadi, Mahmood; Moosavi, Fatemeh

    2016-05-01

    Due to association of protein tyrosine nitration (PTN) with development of some serious human disorders and diseases, in this paper, the possible applications of ZnO-based nanobiosensors in nitrated tyrosine (nTyr) detection were explored within the density functional framework. With this motivation, the interaction of nTyr with ZnO single walled nanotubes via all possible active sites of nTyr was investigated. The results show the tendency of nTyr to interact through its nitro site (forming nitro-site configuration) with ZnO SWNTs as it has the highest binding energy; while, the charge-solvent configuration involving the interaction of nTyr's phenolic ring has the second place in terms of binding energy magnitude. Regardless of which active site contributes in interaction, the binding energies exhibit an ascending trend with decrease of SWNTs' curvature. Electronic properties analysis indicates that nTyr interaction via its nitro group results in formation of some flat bands inside the band gap region leading to significant reduction of overall band gap energy. Similar behavior is also observed in charge-solvent configuration but the band gap energy is larger. These red shifts are mainly attributed to contribution of 2p orbitals of species present in nTyr. Also, the hybridization of 3d orbital of Zn atom with 2p orbitals of nitro group atomic species is found responsible for bonding formation in bioconjugated system possessing the highest binding energy. Comparison of the electronic band structure of ZnO SWNT-Tyr with that of ZnO SWNT-nTyr indicates the sensitivity of ZnO SWNTs toward tyrosine nitration hence, a considerable change in its optical spectra is expectable. This introduces ZnO SWNTs as a promising candidate for PTN detection.

  19. Nano LC-MS Based Proteomic Analysis as a Predicting Approach to Study Cellular Responses of Carbon Nanotubes.

    PubMed

    Li, Ruibin; Wang, Fangjun; Liu, Hongwei; Wu, Ren'an; Zou, Hanfa

    2016-03-01

    Nano-bio interface has been paid much attention recently, though with the lack of methodology to predict the potential responses in biological systems such as cells induced by nanomaterials. In this study, we described a proteomic approach to investigate the proteome change in K562 cells exposed to oxidized single-walled carbon nanotubes (o-SWCNTs). 605 proteins were identified by semi-quantitative proteomic analysis (SQPA), including 29 significantly changed proteins with spectra count (SpC) ratios lager than 2 or less than 0.5. Three of them including HBA, CFL1 and LMAN2 were further validated by western blotting. The differential proteins were further classified by Ingenuity Pathways Analysis (IPA) to integrate them into a signaling network. Based on the information by this network, we predict that o-SWCNT treatment activated cell aggregation, decreased cell migration, but had no effect on cell death. And these cellular responses were further experimentally demonstrated. The protein signaling network established in this study would greatly benefit the studies on the bio-applications of o-SWCNTs and their toxicity studies. Our study demonstrated that proteomics could be used as a predicting tool to study nano-bio interface at cellular level. PMID:27455640

  20. Effect of multiwalled carbon nanotubes on the kinetics of the aniline polymerization: the semi-quantitative OCP approach.

    PubMed

    Ogurtsov, Nikolay A; Noskov, Yuriy V; Pud, Alexander A

    2015-04-16

    We demonstrate applicability of the open-circuit potential (OCP) method for kinetic analysis of the oxidative chemical polymerization of aniline both in clear solution and in dispersions of multiwalled carbon nanotubes (MWCNT). The characteristic points and the shape of the OCP profile are used to estimate the kinetic parameters of the main stages of the known two-step polymerization mechanism of aniline. We have found that the reciprocal values of the duration of the main polymerization stages namely the induction period, pernigraniline (PN) accumulation and reduction of PN with residual aniline are the linear functions of the weight fraction of MWCNT. To compare the kinetic data of the proposed OCP and known approaches the last two stages have been considered as a single heterogeneous stage of emeraldine (EM) formation. The kEM rate constant calculated by the OCP profiles for this EM stage in the solution and dispersion media is in a very good agreement with the known k2 values. PMID:25825795

  1. Multilayer Film Assembly of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Cassell, Alan M.; Meyyappan, M.; Han, Jie; Arnold, J. (Technical Monitor)

    2000-01-01

    An approach to assemble multilayers of carbon nanotubes on a substrate is presented. Chemical vapor deposition using a transition metal catalyst formulation is used to grow the nanotubes. Results show a bilayer assembly of nanotubes each with a different density of tubes.

  2. A soft approach to encapsulate sulfur: polyaniline nanotubes for lithium-sulfur batteries with long cycle life.

    PubMed

    Xiao, Lifen; Cao, Yuliang; Xiao, Jie; Schwenzer, Birgit; Engelhard, Mark H; Saraf, Laxmikant V; Nie, Zimin; Exarhos, Gregory J; Liu, Jun

    2012-03-01

    A novel vulcanized polyaniline nanotube/sulfur composite was prepared successfully via an in situ vulcanization process by heating a mixture of polyaniline nanotube and sulfur at 280 °C. The electrode could retain a discharge capacity of 837 mAh g(-1) after 100 cycles at a 0.1 C rate and manifested 76% capacity retention up to 500 cycles at a 1 C rate. PMID:22278978

  3. Nanotube junctions

    DOEpatents

    Crespi, Vincent Henry; Cohen, Marvin Lou; Louie, Steven Gwon; Zettl, Alexander Karlwalte

    2004-12-28

    The present invention comprises a new nanoscale metal-semiconductor, semiconductor-semiconductor, or metal-metal junction, designed by introducing topological or chemical defects in the atomic structure of the nanotube. Nanotubes comprising adjacent sections having differing electrical properties are described. These nanotubes can be constructed from combinations of carbon, boron, nitrogen and other elements. The nanotube can be designed having different indices on either side of a junction point in a continuous tube so that the electrical properties on either side of the junction vary in a useful fashion. For example, the inventive nanotube may be electrically conducting on one side of a junction and semiconducting on the other side. An example of a semiconductor-metal junction is a Schottky barrier. Alternatively, the nanotube may exhibit different semiconductor properties on either side of the junction. Nanotubes containing heterojunctions, Schottky barriers, and metal-metal junctions are useful for microcircuitry.

  4. Nanotube junctions

    DOEpatents

    Crespi, Vincent Henry; Cohen, Marvin Lou; Louie, Steven Gwon Sheng; Zettl, Alexander Karlwalter

    2003-01-01

    The present invention comprises a new nanoscale metal-semiconductor, semiconductor-semiconductor, or metal-metal junction, designed by introducing topological or chemical defects in the atomic structure of the nanotube. Nanotubes comprising adjacent sections having differing electrical properties are described. These nanotubes can be constructed from combinations of carbon, boron, nitrogen and other elements. The nanotube can be designed having different indices on either side of a junction point in a continuous tube so that the electrical properties on either side of the junction vary in a useful fashion. For example, the inventive nanotube may be electrically conducting on one side of a junction and semiconducting on the other side. An example of a semiconductor-metal junction is a Schottky barrier. Alternatively, the nanotube may exhibit different semiconductor properties on either side of the junction. Nanotubes containing heterojunctions, Schottky barriers, and metal-metal junctions are useful for microcircuitry.

  5. Electronic interaction in composites of a conjugated polymer and carbon nanotubes: first-principles calculation and photophysical approaches

    PubMed Central

    Wéry, Jany; Duvail, Jean-Luc; Lefrant, Serge; Yaya, Abu; Ewels, Chris

    2015-01-01

    Summary The mechanisms that control the photophysics of composite films made of a semiconducting conjugated polymer (poly(paraphenylene vinylene), PPV) mixed with single-walled carbon nanotubes (SWNT) up to a concentration of 64 wt % are determined by using photoexcitation techniques and density functional theory. Charge separation is confirmed experimentally by rapid quenching of PPV photoluminescence and changes in photocurrent starting at relatively low concentrations of SWNT. Calculations predict strong electronic interaction between the polymer and the SWNT network when nanotubes are semiconducting. PMID:26171290

  6. Processable Cyclic Peptide Nanotubes with Tunable Interiors

    SciTech Connect

    Hourani, Rami; Zhang, Chen; van der Weegen, Rob; Ruiz, Luis; Li, Changyi; Keten, Sinan; Helms, Brett A.; Xu, Ting

    2011-09-06

    A facile route to generate cyclic peptide nanotubes with tunable interiors is presented. By incorporating 3-amino-2-methylbenzoic acid in the d,l-alternating primary sequence of a cyclic peptide, a functional group can be presented in the interior of the nanotubes without compromising the formation of high aspect ratio nanotubes. The new design of such a cyclic peptide also enables one to modulate the nanotube growth process to be compatible with the polymer processing window without compromising the formation of high aspect ratio nanotubes, thus opening a viable approach toward molecularly defined porous membranes.

  7. Improved Process for Fabricating Carbon Nanotube Probes

    NASA Technical Reports Server (NTRS)

    Stevens, R.; Nguyen, C.; Cassell, A.; Delzeit, L.; Meyyappan, M.; Han, Jie

    2003-01-01

    An improved process has been developed for the efficient fabrication of carbon nanotube probes for use in atomic-force microscopes (AFMs) and nanomanipulators. Relative to prior nanotube tip production processes, this process offers advantages in alignment of the nanotube on the cantilever and stability of the nanotube's attachment. A procedure has also been developed at Ames that effectively sharpens the multiwalled nanotube, which improves the resolution of the multiwalled nanotube probes and, combined with the greater stability of multiwalled nanotube probes, increases the effective resolution of these probes, making them comparable in resolution to single-walled carbon nanotube probes. The robust attachment derived from this improved fabrication method and the natural strength and resiliency of the nanotube itself produces an AFM probe with an extremely long imaging lifetime. In a longevity test, a nanotube tip imaged a silicon nitride surface for 15 hours without measurable loss of resolution. In contrast, the resolution of conventional silicon probes noticeably begins to degrade within minutes. These carbon nanotube probes have many possible applications in the semiconductor industry, particularly as devices are approaching the nanometer scale and new atomic layer deposition techniques necessitate a higher resolution characterization technique. Previously at Ames, the use of nanotube probes has been demonstrated for imaging photoresist patterns with high aspect ratio. In addition, these tips have been used to analyze Mars simulant dust grains, extremophile protein crystals, and DNA structure.

  8. Horizontal carbon nanotube alignment.

    PubMed

    Cole, Matthew T; Cientanni, Vito; Milne, William I

    2016-09-21

    The production of horizontally aligned carbon nanotubes offers a rapid means of realizing a myriad of self-assembled near-atom-scale technologies - from novel photonic crystals to nanoscale transistors. The ability to reproducibly align anisotropic nanostructures has huge technological value. Here we review the present state-of-the-art in horizontal carbon nanotube alignment. For both in and ex situ approaches, we quantitatively assess the reported linear packing densities alongside the degree of alignment possible for each of these core methodologies. PMID:27546174

  9. Constitutive Modeling of Crosslinked Nanotube Materials

    NASA Technical Reports Server (NTRS)

    Odegard, G. M.; Frankland, S. J. V.; Herzog, M. N.; Gates, T. S.; Fay, C. C.

    2004-01-01

    A non-linear, continuum-based constitutive model is developed for carbon nanotube materials in which bundles of aligned carbon nanotubes have varying amounts of crosslinks between the nanotubes. The model accounts for the non-linear elastic constitutive behavior of the material in terms of strain, and is developed using a thermodynamic energy approach. The model is used to examine the effect of the crosslinking on the overall mechanical properties of variations of the crosslinked carbon nanotube material with varying degrees of crosslinking. It is shown that the presence of the crosslinks has significant effects on the mechanical properties of the carbon nanotube materials. An increase in the transverse shear properties is observed when the nanotubes are crosslinked. However, this increase is accompanied by a decrease in axial mechanical properties of the nanotube material upon crosslinking.

  10. Heteroporphyrin nanotubes and composites

    DOEpatents

    Shelnutt, John A.; Medforth, Craig J.; Wang, Zhongchun

    2007-05-29

    Heteroporphyrin nanotubes, metal nanostructures, and metal/porphyrin-nanotube composite nanostructures formed using the nanotubes as photocatalysts and structural templates, and the methods for forming the nanotubes and composites.

  11. Heteroporphyrin nanotubes and composites

    DOEpatents

    Shelnutt, John A.; Medforth, Craig J.; Wang, Zhongchun

    2006-11-07

    Heteroporphyrin nanotubes, metal nanostructures, and metal/porphyrin-nanotube composite nanostructures formed using the nanotubes as photocatalysts and structural templates, and the methods for forming the nanotubes and composites.

  12. Application of zone-folding approach to the first-principles estimation of thermodynamic properties of carbon and ZrS2 -based nanotubes.

    PubMed

    Bandura, Andrei V; Porsev, Vitaly V; Evarestov, Robert A

    2016-03-15

    A zone-folding (ZF) approach is applied for the estimation of the phonon contributions to thermodynamic properties of carbon-and ZrS2 -based nanotubes (NTs) of hexagonal morphology with different chiralities. The results obtained are compared with those from the direct calculation of the thermodynamic properties of NTs using PBE0 hybrid exchange-correlation functional. The phonon contribution to the stability of NTs proved to be negligible for the internal energy and small for the Helmholtz free energy. It is found that the ZF approach allows us an accurate estimation of phonon contributions to internal energy, but slightly overestimates the phonon contributions to entropy. © 2015 Wiley Periodicals, Inc. PMID:26519863

  13. Segmentation and additive approach: A reliable technique to study noncovalent interactions of large molecules at the surface of single-wall carbon nanotubes.

    PubMed

    Torres, Ana M; Scheiner, Steve; Roy, Ajit K; Garay-Tapia, Andrés M; Bustamante, John; Kar, Tapas

    2016-08-01

    This investigation explores a new protocol, named Segmentation and Additive approach (SAA), to study exohedral noncovalent functionalization of single-walled carbon nanotubes with large molecules, such as polymers and biomolecules, by segmenting the entire system into smaller units to reduce computational cost. A key criterion of the segmentation process is the preservation of the molecular structure responsible for stabilization of the entire system in smaller segments. Noncovalent interaction of linoleic acid (LA, C18 H32 O2 ), a fatty acid, at the surface of a (10,0) zigzag nanotube is considered for test purposes. Three smaller segmented models have been created from the full (10,0)-LA system and interaction energies were calculated for these models and compared with the full system at different levels of theory, namely ωB97XD, LDA. The success of this SAA is confirmed as the sum of the interaction energies is in very good agreement with the total interaction energy. Besides reducing computational cost, another merit of SAA is an estimation of the contributions from different sections of the large system to the total interaction energy which can be studied in-depth using a higher level of theory to estimate several properties of each segment. On the negative side, bulk properties, such as HOMO-LUMO (highest occupied molecular orbital - lowest occupied molecular orbital) gap, of the entire system cannot be estimated by adding results from segment models. © 2016 Wiley Periodicals, Inc. PMID:27241227

  14. Effects of high energy electrons on the properties of polyethylene / multiwalled carbon nanotubes composites: Comparison of as-grown and oxygen-functionalised MWCNT

    NASA Astrophysics Data System (ADS)

    Krause, B.; Pötschke, P.; Gohs, U.

    2014-05-01

    Polymer modification with high energy electrons (EB) is well established in different applications for many years. It is used for crosslinking, curing, degrading, grafting of polymeric materials and polymerisation of monomers. In contrast to this traditional method, electron induced reactive processing (EIReP) combines the polymer modification with high energy electrons and the melt mixing process. This novel reactive method was used to prepare polymer blends and composites. In this study, both methods were used for the preparation of polyethylene (PE)/ multiwalled carbon nanotubes (MWCNT) composites in the presence of a coupling agent. The influence of MWCNT and type of electron treatment on the gel content, the thermal conductivity, rheological, and electrical properties was investigated whereby as-grown and oxidised MWCNT were used. In the presence of a coupling agent and at an absorbed dose of 40 kGy, the gel content increased from 57 % for the pure PE to 74 % or 88 % by the addition of as-grown (Baytubes® C150P) or oxidised MWCNT, respectively. In comparison to the composites containing the as-grown MWCNTs, the use of the oxidised MWCNTs led to higher melt viscosity and higher storage modulus due to higher yield of filler polymer couplings. The melt viscosity increased due to the addition of MWCNT and crosslinking of PE. The thermal conductivity increased to about 150 % and showed no dependence on the kind of MWCNT and the type of electron treatment. In contrast, the lowest value of electrical volume resistivity was found for the non-irradiated samples and after state of the art electron treatment without any influence of the type of MWCNT. In the case of EIReP, the volume resistivity increased by 2 (as-grown MWCNT) or 3 decades (oxidised MWCNT) depending on the process parameters.

  15. Effects of high energy electrons on the properties of polyethylene / multiwalled carbon nanotubes composites: Comparison of as-grown and oxygen-functionalised MWCNT

    SciTech Connect

    Krause, B. E-mail: poe@ipfdd.de Pötschke, P. E-mail: poe@ipfdd.de Gohs, U. E-mail: poe@ipfdd.de

    2014-05-15

    Polymer modification with high energy electrons (EB) is well established in different applications for many years. It is used for crosslinking, curing, degrading, grafting of polymeric materials and polymerisation of monomers. In contrast to this traditional method, electron induced reactive processing (EIReP) combines the polymer modification with high energy electrons and the melt mixing process. This novel reactive method was used to prepare polymer blends and composites. In this study, both methods were used for the preparation of polyethylene (PE)/ multiwalled carbon nanotubes (MWCNT) composites in the presence of a coupling agent. The influence of MWCNT and type of electron treatment on the gel content, the thermal conductivity, rheological, and electrical properties was investigated whereby as-grown and oxidised MWCNT were used. In the presence of a coupling agent and at an absorbed dose of 40 kGy, the gel content increased from 57 % for the pure PE to 74 % or 88 % by the addition of as-grown (Baytubes® C150P) or oxidised MWCNT, respectively. In comparison to the composites containing the as-grown MWCNTs, the use of the oxidised MWCNTs led to higher melt viscosity and higher storage modulus due to higher yield of filler polymer couplings. The melt viscosity increased due to the addition of MWCNT and crosslinking of PE. The thermal conductivity increased to about 150 % and showed no dependence on the kind of MWCNT and the type of electron treatment. In contrast, the lowest value of electrical volume resistivity was found for the non-irradiated samples and after state of the art electron treatment without any influence of the type of MWCNT. In the case of EIReP, the volume resistivity increased by 2 (as-grown MWCNT) or 3 decades (oxidised MWCNT) depending on the process parameters.

  16. The self-assembly of anticancer camptothecin-dipeptide nanotubes: a minimalistic and high drug loading approach to increased efficacy.

    PubMed

    Kim, Se Hye; Kaplan, Jonah A; Sun, Yuan; Shieh, Aileen; Sun, Hui-Lung; Croce, Carlo M; Grinstaff, Mark W; Parquette, Jon R

    2015-01-01

    20-(S)-Camptothecin (CPT)-conjugated dipeptides are reported that preassemble into nanotubes with diameters ranging from 80-120 nm. These nanoassemblies maintain a high (∼47 %) drug loading and exhibit greater drug stability (i.e., resistance to lactone hydrolysis), and consequently greater efficacy against several human cancer cells (HT-29, A549, H460, and H23) in vitro compared with the clinically used prodrug irinotecan. A key and defining feature of this system is the use of the CPT-conjugated dipeptide as both the drug and precursor to the nanostructured carrier, which simplifies the overall fabrication process. PMID:25384556

  17. Tunneling Nanotubes

    PubMed Central

    Lou, Emil; Fujisawa, Sho; Barlas, Afsar; Romin, Yevgeniy; Manova-Todorova, Katia; Moore, Malcolm A.S.; Subramanian, Subbaya

    2012-01-01

    Tunneling nanotubes are actin-based cytoplasmic extensions that function as intercellular channels in a wide variety of cell types.There is a renewed and keen interest in the examination of modes of intercellular communication in cells of all types, especially in the field of cancer biology. Tunneling nanotubes –which in the literature have also been referred to as “membrane nanotubes,” “’intercellular’ or ‘epithelial’ bridges,” or “cytoplasmic extensions” – are under active investigation for their role in facilitating direct intercellular communication. These structures have not, until recently, been scrutinized as a unique and previously unrecognized form of direct cell-to-cell transmission of cellular cargo in the context of human cancer. Our recent study of tunneling nanotubes in human malignant pleural mesothelioma and lung adenocarcinomas demonstrated efficient transfer of cellular contents, including proteins, Golgi vesicles, and mitochondria, between cells derived from several well-established cancer cell lines. Further, we provided effective demonstration that such nanotubes can form between primary malignant cells from human patients. For the first time, we also demonstrated the in vivo relevance of these structures in humans, having effectively imaged nanotubes in intact solid tumors from patients. Here we provide further analysis and discussion on our findings, and offer a prospective ‘road map’ for studying tunneling nanotubes in the context of human cancer. We hope that further understanding of the mechanisms, methods of transfer, and particularly the role of nanotubes in tumor-stromal cross-talk will lead to identification of new selective targets for cancer therapeutics. PMID:23060969

  18. Constitutive Modeling of Nanotube/Polymer Composites with Various Nanotube Orientations

    NASA Technical Reports Server (NTRS)

    Odegard, Gregory M.; Gates, Thomas S.

    2002-01-01

    In this study, a technique has been proposed for developing constitutive models for polymer composite systems reinforced with single-walled carbon nanotubes (SWNT) with various orientations with respect to the bulk material coordinates. A nanotube, the local polymer adjacent to the nanotube, and the nanotube/polymer interface have been modeled as an equivalent-continuum fiber by using an equivalent-continuum modeling method. The equivalent-continuum fiber accounts for the local molecular structure and bonding information and serves as a means for incorporating micromechanical analyses for the prediction of bulk mechanical properties of SWNT/polymer composite. As an example, the proposed approach is used for the constitutive modeling of a SWNT/LaRC-SI (with a PmPV interface) composite system, with aligned nanotubes, three-dimensionally randomly oriented nanotubes, and nanotubes oriented with varying degrees of axisymmetry. It is shown that the Young s modulus is highly dependent on the SWNT orientation distribution.

  19. An analytical approach to evaluate the performance of graphene and carbon nanotubes for NH3 gas sensor applications.

    PubMed

    Akbari, Elnaz; Arora, Vijay Kumar; Enzevaee, Aria; Ahmadi, Mohamad T; Saeidmanesh, Mehdi; Khaledian, Mohsen; Karimi, Hediyeh; Yusof, Rubiyah

    2014-01-01

    Carbon, in its variety of allotropes, especially graphene and carbon nanotubes (CNTs), holds great potential for applications in variety of sensors because of dangling π-bonds that can react with chemical elements. In spite of their excellent features, carbon nanotubes (CNTs) and graphene have not been fully exploited in the development of the nanoelectronic industry mainly because of poor understanding of the band structure of these allotropes. A mathematical model is proposed with a clear purpose to acquire an analytical understanding of the field-effect-transistor (FET) based gas detection mechanism. The conductance change in the CNT/graphene channel resulting from the chemical reaction between the gas and channel surface molecules is emphasized. NH3 has been used as the prototype gas to be detected by the nanosensor and the corresponding current-voltage (I-V) characteristics of the FET-based sensor are studied. A graphene-based gas sensor model is also developed. The results from graphene and CNT models are compared with the experimental data. A satisfactory agreement, within the uncertainties of the experiments, is obtained. Graphene-based gas sensor exhibits higher conductivity compared to that of CNT-based counterpart for similar ambient conditions. PMID:24991510

  20. Superhydrophobic amorphous carbon/carbon nanotube nanocomposites

    NASA Astrophysics Data System (ADS)

    Han, Z. J.; Tay, B. K.; Shakerzadeh, M.; Ostrikov, K.

    2009-06-01

    Superhydrophobic amorphous carbon/carbon nanotube nanocomposites are fabricated by plasma immersion ion implantation with carbon nanotube forests as a template. The microstructure of the fabricated nanocomposites shows arrays of carbon nanotubes capped with amorphous carbon nanoparticles. Contact angle measurements show that both advancing and receding angles close to 180° can be achieved on the nanocomposites. The fabrication here does not require patterning of carbon nanotubes or deposition of conformal coatings with low surface energy, which are usually involved in conventional approaches for superhydrophobic surfaces. The relationship between the observed superhydrophobicity and the unique microstructure of the nanocomposites is discussed.

  1. Nanotube cathodes.

    SciTech Connect

    Overmyer, Donald L.; Lockner, Thomas Ramsbeck; Siegal, Michael P.; Miller, Paul Albert

    2006-11-01

    Carbon nanotubes have shown promise for applications in many diverse areas of technology. In this report we describe our efforts to develop high-current cathodes from a variety of nanotubes deposited under a variety of conditions. Our goal was to develop a one-inch-diameter cathode capable of emitting 10 amperes of electron current for one second with an applied potential of 50 kV. This combination of current and pulse duration significantly exceeds previously reported nanotube-cathode performance. This project was planned for two years duration. In the first year, we tested the electron-emission characteristics of nanotube arrays fabricated under a variety of conditions. In the second year, we planned to select the best processing conditions, to fabricate larger cathode samples, and to test them on a high-power relativistic electron beam generator. In the first year, much effort was made to control nanotube arrays in terms of nanotube diameter and average spacing apart. When the project began, we believed that nanotubes approximately 10 nm in diameter would yield sufficient electron emission properties, based on the work of others in the field. Therefore, much of our focus was placed on measured field emission from such nanotubes grown on a variety of metallized surfaces and with varying average spacing between individual nanotubes. We easily reproduced the field emission properties typically measured by others from multi-wall carbon nanotube arrays. Interestingly, we did this without having the helpful vertical alignment to enhance emission; our nanotubes were randomly oriented. The good emission was most likely possible due to the improved crystallinity, and therefore, electrical conductivity, of our nanotubes compared to those in the literature. However, toward the end of the project, we learned that while these 10-nm-diameter CNTs had superior crystalline structure to the work of others studying field emission from multi-wall CNT arrays, these nanotubes still

  2. Nanotube phonon waveguide

    DOEpatents

    Chang, Chih-Wei; Zettl, Alexander K.

    2013-10-29

    Disclosed are methods and devices in which certain types of nanotubes (e.g., carbon nanotubes and boron nitride nanotubes conduct heat with high efficiency and are therefore useful in electronic-type devices.

  3. Modelling water molecules inside cyclic peptide nanotubes

    NASA Astrophysics Data System (ADS)

    Tiangtrong, Prangsai; Thamwattana, Ngamta; Baowan, Duangkamon

    2016-03-01

    Cyclic peptide nanotubes occur during the self-assembly process of cyclic peptides. Due to the ease of synthesis and ability to control the properties of outer surface and inner diameter by manipulating the functional side chains and the number of amino acids, cyclic peptide nanotubes have attracted much interest from many research areas. A potential application of peptide nanotubes is their use as artificial transmembrane channels for transporting ions, biomolecules and waters into cells. Here, we use the Lennard-Jones potential and a continuum approach to study the interaction of a water molecule in a cyclo[(- D-Ala- L-Ala)_4-] peptide nanotube. Assuming that each unit of a nanotube comprises an inner and an outer tube and that a water molecule is made up of a sphere of two hydrogen atoms uniformly distributed over its surface and a single oxygen atom at the centre, we determine analytically the interaction energy of the water molecule and the peptide nanotube. Using this energy, we find that, independent of the number of peptide units, the water molecule will be accepted inside the nanotube. Once inside the nanotube, we show that a water molecule prefers to be off-axis, closer to the surface of the inner nanotube. Furthermore, our study of two water molecules inside the peptide nanotube supports the finding that water molecules form an array of a 1-2-1-2 file inside peptide nanotubes. The theoretical study presented here can facilitate thorough understanding of the behaviour of water molecules inside peptide nanotubes for applications, such as artificial transmembrane channels.

  4. SnO2-decorated multiwalled carbon nanotubes and Vulcan carbon through a sonochemical approach for supercapacitor applications.

    PubMed

    Vinoth, Victor; Wu, Jerry J; Asiri, Abdullah M; Lana-Villarreal, Teresa; Bonete, Pedro; Anandan, Sambandam

    2016-03-01

    Multiwalled carbon nanotubes (MWCNTs) and Vulcan carbon (VC) decorated with SnO2 nanoparticles were synthesized using a facile and versatile sonochemical procedure. The as-prepared nanocomposites were characterized by means of transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and Fourier transform infra red spectroscopy. It was evidenced that SnO2 nanoparticles were uniformly distributed on both carbon surfaces, tightly decorating the MWCNTs and VC. The electrochemical performance of the nanocomposites was evaluated by cyclic voltammetry and galvanostatic charge/discharge cycling. The as-synthesized SnO2/MWCNTs nanocomposites show a higher capacity than the SnO2/VC nanocomposites. Concretely, the SnO2/MWCNTs electrodes exhibit a specific capacitance of 133.33 F g(-1), whereas SnO2/VC electrodes exhibit a specific capacitance of 112.14 F g(-1) measured at 0.5 mA cm(-2) in 1 M Na2SO4. PMID:26585000

  5. Nanotube News

    ERIC Educational Resources Information Center

    Journal of College Science Teaching, 2005

    2005-01-01

    Smaller, faster computers, bullet-proof t-shirts, and itty-bitty robots--such are the promises of nanotechnology and the cylinder-shaped collection of carbon molecules known as nanotubes. But for these exciting ideas to become realities, scientists must understand how these miracle molecules perform under all sorts of conditions. This brief…

  6. Carbon Nanotubes for Human Space Flight

    NASA Technical Reports Server (NTRS)

    Scott, Carl D.; Files, Brad; Yowell, Leonard

    2003-01-01

    Single-wall carbon nanotubes offer the promise of a new class of revolutionary materials for space applications. The Carbon Nanotube Project at NASA Johnson Space Center has been actively researching this new technology by investigating nanotube production methods (arc, laser, and HiPCO) and gaining a comprehensive understanding of raw and purified material using a wide range of characterization techniques. After production and purification, single wall carbon nanotubes are processed into composites for the enhancement of mechanical, electrical, and thermal properties. This "cradle-to-grave" approach to nanotube composites has given our team unique insights into the impact of post-production processing and dispersion on the resulting material properties. We are applying our experience and lessons-learned to developing new approaches toward nanotube material characterization, structural composite fabrication, and are also making advances in developing thermal management materials and electrically conductive materials in various polymer-nanotube systems. Some initial work has also been conducted with the goal of using carbon nanotubes in the creation of new ceramic materials for high temperature applications in thermal protection systems. Human space flight applications such as advanced life support and fuel cell technologies are also being investigated. This discussion will focus on the variety of applications under investigation.

  7. A facile approach towards increasing the nitrogen-content in nitrogen-doped carbon nanotubes via halogenated catalysts

    NASA Astrophysics Data System (ADS)

    Ombaka, L. M.; Ndungu, P. G.; Omondi, B.; McGettrick, J. D.; Davies, M. L.; Nyamori, V. O.

    2016-03-01

    Nitrogen-doped carbon nanotubes (N-CNTs) have been synthesized at 850 °C via a CVD deposition technique by use of three ferrocenyl derivative catalysts, i.e. para-CN, -CF3 and -Cl substituted-phenyl rings. The synthesized catalysts have been characterized by NMR, IR, HR-MS and XRD. The XRD analysis of the para-CF3 catalyst indicates that steric factors influence the X-ray structure of 1,1‧-ferrocenylphenyldiacrylonitriles. Acetonitrile or pyridine was used as carbon and nitrogen sources to yield mixtures of N-CNTs and carbon spheres (CS). The N-CNTs obtained from the para-CF3 catalysts, in pyridine, have the highest nitrogen-doping level, show a helical morphology and are less thermally stable compared with those synthesized by use of the para-CN and -Cl as catalyst. This suggests that fluorine heteroatoms enhance nitrogen-doping in N-CNTs and formation of helical-N-CNTs (H-N-CNTs). The para-CF3 and para-Cl catalysts in acetonitrile yielded iron-filled N-CNTs, indicating that halogens promote encapsulation of iron into the cavity of N-CNT. The use of acetonitrile, as carbon and nitrogen source, with the para-CN and -Cl as catalysts also yielded a mixture of N-CNTs and carbon nanofibres (CNFs), with less abundance of CNFs in the products obtained using para-Cl catalysts. However, para-CF3 catalyst in acetonitrile gave N-CNTs as the only shaped carbon nanomaterials.

  8. Preparation of High-Efficiency Cytochrome c-Imprinted Polymer on the Surface of Magnetic Carbon Nanotubes by Epitope Approach via Metal Chelation and Six-Membered Ring.

    PubMed

    Qin, Ya-Ping; Li, Dong-Yan; He, Xi-Wen; Li, Wen-You; Zhang, Yu-Kui

    2016-04-27

    A novel epitope molecularly imprinted polymer on the surface of magnetic carbon nanotubes (MCNTs@EMIP) was successfully fabricated to specifically recognize target protein cytochrome c (Cyt C) with high performance. The peptides sequences corresponding to the surface-exposed C-terminus domains of Cyt C was selected as epitope template molecule, and commercially available zinc acrylate and ethylene glycol dimethacrylate (EGDMA) were employed as functional monomer and cross-linker, respectively, to synthesize MIP via free radical polymerization. The epitope was immobilized via metal chelation and six-membered ring formed between the functional monomer and the hydroxyl and amino groups of the epitope. The resulting MCNTs@EMIP exhibited specific recognition ability toward target Cyt C including more satisfactory imprinting factor (about 11.7) than that of other reported imprinting methods. In addition, the MCNTs@EMIP demonstrated a high adsorption amount (about 780.0 mg g(-1)) and excellent selectivity. Besides, the magnetic property of the support material made the processes easy and highly efficient by assistance of an external magnetic field. High-performance liquid chromatography analysis of Cyt C in bovine blood real sample and protein mixture indicated that the specificity was not affected by other competitive proteins, which forcefully stated that the MCNTs@EMIP had potential to be applied in bioseparation area. In brief, this study provided a new protocol to detect target protein in complex sample via epitope imprinting approach and surface imprinting strategy. PMID:27049646

  9. New Approach to Create TiO2(B)/Carbon Core/Shell Nanotubes: Ideal Structure for Enhanced Lithium Ion Storage.

    PubMed

    Zhu, Xiaoyi; Yang, Xianfeng; Lv, Chunxiao; Guo, Shaojun; Li, Jianjiang; Zheng, Zhanfeng; Zhu, Huaiyong; Yang, Dongjiang

    2016-07-27

    To achieve uniform carbon coating on TiO2 nanomaterials, high temperature (>500 °C) annealing treatment is a necessity. However, the annealing treatment inevitably leads to the strong phase transformation from TiO2(B) with high lithium ion storage (LIS) capacity to anatase with low LIS one as well as the damage of nanostructures. Herein, we demonstrate a new approach to create TiO2(B)/carbon core/shell nanotubes (C@TBNTs) using a long-chain silane polymethylhydrosiloxane (PMHS) to bind the TBNTs by forming Si-O-Ti bonds. The key feature of this work is that the introduction of PMHS onto TBNTs can afford TBNTs with very high thermal stability at higher than 700 °C and inhibit the phase transformation from TiO2(B) to anatase. Such a high thermal property of PMHS-TBNTs makes them easily coated with highly graphitic carbon shell via CVD process at 700 °C. The as-prepared C@TBNTs deliver outstanding rate capability and electrochemical stability, i.e., reversible capacity above 250 mAh g(-1) at 10 C and a high specific capacity of 479.2 mAh g(-1) after 1000 cycles at 1 C. As far as we know, the LIS performance of our sample is the highest among the previously reported TiO2(B) anode materials. PMID:27383450

  10. Carbon nanotube composite materials

    DOEpatents

    O'Bryan, Gregory; Skinner, Jack L; Vance, Andrew; Yang, Elaine Lai; Zifer, Thomas

    2015-03-24

    A material consisting essentially of a vinyl thermoplastic polymer, un-functionalized carbon nanotubes and hydroxylated carbon nanotubes dissolved in a solvent. Un-functionalized carbon nanotube concentrations up to 30 wt % and hydroxylated carbon nanotube concentrations up to 40 wt % can be used with even small concentrations of each (less than 2 wt %) useful in producing enhanced conductivity properties of formed thin films.

  11. Sacrificial template method of fabricating a nanotube

    DOEpatents

    Yang, Peidong; He, Rongrui; Goldberger, Joshua; Fan, Rong; Wu, Yi-Ying; Li, Deyu; Majumdar, Arun

    2007-05-01

    Methods of fabricating uniform nanotubes are described in which nanotubes were synthesized as sheaths over nanowire templates, such as using a chemical vapor deposition process. For example, single-crystalline zinc oxide (ZnO) nanowires are utilized as templates over which gallium nitride (GaN) is epitaxially grown. The ZnO templates are then removed, such as by thermal reduction and evaporation. The completed single-crystalline GaN nanotubes preferably have inner diameters ranging from 30 nm to 200 nm, and wall thicknesses between 5 and 50 nm. Transmission electron microscopy studies show that the resultant nanotubes are single-crystalline with a wurtzite structure, and are oriented along the <001> direction. The present invention exemplifies single-crystalline nanotubes of materials with a non-layered crystal structure. Similar "epitaxial-casting" approaches could be used to produce arrays and single-crystalline nanotubes of other solid materials and semiconductors. Furthermore, the fabrication of multi-sheath nanotubes are described as well as nanotubes having multiple longitudinal segments.

  12. Functionalized boron nitride nanotubes

    DOEpatents

    Sainsbury, Toby; Ikuno, Takashi; Zettl, Alexander K

    2014-04-22

    A plasma treatment has been used to modify the surface of BNNTs. In one example, the surface of the BNNT has been modified using ammonia plasma to include amine functional groups. Amine functionalization allows BNNTs to be soluble in chloroform, which had not been possible previously. Further functionalization of amine-functionalized BNNTs with thiol-terminated organic molecules has also been demonstrated. Gold nanoparticles have been self-assembled at the surface of both amine- and thiol-functionalized boron nitride Nanotubes (BNNTs) in solution. This approach constitutes a basis for the preparation of highly functionalized BNNTs and for their utilization as nanoscale templates for assembly and integration with other nanoscale materials.

  13. Binding energy of the trion complex in carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Meliksetyan, Areg; Bondarev, Igor

    2014-03-01

    We derive an analytical expression for the binding energy of the trion complex (charged exciton) in small diameter (~1nm) carbon nanotubes. We use the (asymptotically exact) Landau-Herring approach that was previously implemented by one of us (Ref.) to evaluate the biexciton binding energy in carbon nanotubes. Within this approach, we find the universal asymptotic relationship between the trion, biexciton and exciton binding energies in the same carbon nanotube. Particularly, the trion binding energy we obtained is estimated to be greater than the corresponding biexciton binding energy by a factor ~1.5 for carbon nanotubes with diameters ~1nm, which reasonably agrees with the latest non-linear optical spectroscopy measurements reported in Refs. and (1.46 for the (6,5) nanotube and 1.42 for the (9,7) nanotube, respectively). ARO-W911NF-11-1-0189 (A.M.), DOE-DE-SC0007117 (I.B.).

  14. Twisting Graphene into Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Kit, Oleg O.; Tallinen, Tuomas; Mahadevan, L.; Timonen, Jussi; Koskinen, Pekka

    2012-02-01

    Carbon nanotubes are usually described as being rolled up from graphene sheets; this process, however, have never been realized experimentally. We showed that graphene can indeed be transformed into nanotube by twisting [1]. Further, we showed that tube formation can be well-explained within classical theory of elasticity---in fact the very mechanism of tube formation can be observed by twisting a strap from one's backpack (try now!). Furthermore, we showed that nanotube chirality may not only be predicted, but can also be controlled externally. The quantum molecular dynamic simulations at T=300K were achieved thanks to the revised periodic boundary conditions (RPBC) approach [2-3]. The structures similar to simulated have been recently observed experimentally [4]. This novel rote for nanotube formation opens new opportunities in nanomaterial manipulation not restricted to carbon alone. In the presentation, I will describe tube formation, as well as outline the easy and efficient technique for distorted nanostructures simulation, the RPBC approach. [4pt] [1] O. O. Kit et al. arXiv:1108.0048[0pt] [2] P. Koskinen & O. O. Kit PRL 105, 106401 (2010)[0pt] [3] O. O. Kit, L. Pastewka, P. Koskinen PRB 84, 155431 (2011)[0pt] [4] A. Chuvilin et al. Nature Materials 10, 687 (2011)

  15. Single-crystal gallium nitride nanotubes

    NASA Astrophysics Data System (ADS)

    Goldberger, Joshua; He, Rongrui; Zhang, Yanfeng; Lee, Sangkwon; Yan, Haoquan; Choi, Heon-Jin; Yang, Peidong

    2003-04-01

    Since the discovery of carbon nanotubes in 1991 (ref. 1), there have been significant research efforts to synthesize nanometre-scale tubular forms of various solids. The formation of tubular nanostructure generally requires a layered or anisotropic crystal structure. There are reports of nanotubes made from silica, alumina, silicon and metals that do not have a layered crystal structure; they are synthesized by using carbon nanotubes and porous membranes as templates, or by thin-film rolling. These nanotubes, however, are either amorphous, polycrystalline or exist only in ultrahigh vacuum. The growth of single-crystal semiconductor hollow nanotubes would be advantageous in potential nanoscale electronics, optoelectronics and biochemical-sensing applications. Here we report an `epitaxial casting' approach for the synthesis of single-crystal GaN nanotubes with inner diameters of 30-200nm and wall thicknesses of 5-50nm. Hexagonal ZnO nanowires were used as templates for the epitaxial overgrowth of thin GaN layers in a chemical vapour deposition system. The ZnO nanowire templates were subsequently removed by thermal reduction and evaporation, resulting in ordered arrays of GaN nanotubes on the substrates. This templating process should be applicable to many other semiconductor systems.

  16. Stability of diphenylalanine peptide nanotubes in solution

    NASA Astrophysics Data System (ADS)

    Andersen, Karsten Brandt; Castillo-Leon, Jaime; Hedström, Martin; Svendsen, Winnie Edith

    2011-03-01

    Over the last couple of years, self-organizing nanotubes based on the dipeptide diphenylalanine have received much attention, mainly as possible building blocks for the next generation of biosensors and as drug delivery systems. One of the main reasons for this large interest is that these peptide nanotubes are believed to be very stable both thermally and chemically. Previously, the chemical and thermal stability of self-organizing structures has been investigated after the evaporation of the solvent. However, it was recently discovered that the stability of the structures differed significantly when the tubes were in solution. It has been shown that, in solution, the peptide nanotubes can easily be dissolved in several solvents including water. It is therefore of critical importance that the stability of the nanotubes in solution and not after solvent evaporation be investigated prior to applications in which the nanotube will be submerged in liquid. The present article reports results demonstrating the instability and suggests a possible approach to a stabilization procedure, which drastically improves the stability of the formed structures. The results presented herein provide new information regarding the stability of self-organizing diphenylalanine nanotubes in solution.Over the last couple of years, self-organizing nanotubes based on the dipeptide diphenylalanine have received much attention, mainly as possible building blocks for the next generation of biosensors and as drug delivery systems. One of the main reasons for this large interest is that these peptide nanotubes are believed to be very stable both thermally and chemically. Previously, the chemical and thermal stability of self-organizing structures has been investigated after the evaporation of the solvent. However, it was recently discovered that the stability of the structures differed significantly when the tubes were in solution. It has been shown that, in solution, the peptide nanotubes can

  17. Janus Composite Nanotubes.

    PubMed

    Chen, Ying; Liu, Zhen; Qu, Xiaozhong; Liang, Fuxin; Yang, Zhenzhong

    2016-06-21

    We propose a facile method to achieve paramagnetic Janus nanotubes with two compositions compartmentalized onto the interior and exterior surfaces, respectively. A sulfonated polydivinylbenzene (PDVB) nanotube is prepared by simple sulfonation of the exterior surface of a PDVB nanotube. Silica@FeOOH dual layers are sequentially grown onto the sulfonated PDVB nanotube surface. The composite nanotubes become paramagnetic after calcination and can be broken into shorter pieces under vigorous ultrasonication. After selective modification of the interior and exterior surfaces of the paramagnetic nanotubes, the nanotube shell becomes Janus in wettability. Desired hydrophobic species can be selectively captured inside the cavity. The paramagnetic Janus composite nanotubes can align into parallel chains under a magnetic field, which is self-disassembled upon removal of the magnetic field. PMID:27124877

  18. Carbon nanotube nanoelectrode arrays

    DOEpatents

    Ren, Zhifeng; Lin, Yuehe; Yantasee, Wassana; Liu, Guodong; Lu, Fang; Tu, Yi

    2008-11-18

    The present invention relates to microelectode arrays (MEAs), and more particularly to carbon nanotube nanoelectrode arrays (CNT-NEAs) for chemical and biological sensing, and methods of use. A nanoelectrode array includes a carbon nanotube material comprising an array of substantially linear carbon nanotubes each having a proximal end and a distal end, the proximal end of the carbon nanotubes are attached to a catalyst substrate material so as to form the array with a pre-determined site density, wherein the carbon nanotubes are aligned with respect to one another within the array; an electrically insulating layer on the surface of the carbon nanotube material, whereby the distal end of the carbon nanotubes extend beyond the electrically insulating layer; a second adhesive electrically insulating layer on the surface of the electrically insulating layer, whereby the distal end of the carbon nanotubes extend beyond the second adhesive electrically insulating layer; and a metal wire attached to the catalyst substrate material.

  19. Engineered Carbon Nanotube Materials for High-Q Nanomechanical Resonators

    NASA Technical Reports Server (NTRS)

    Choi, Daniel S.; Hunt, Brian; Bronikowski, Mike; Epp, Larry; Hoenk, Michael; Hoppe, Dan; Kowalczyk, Bob; Wong, Eric; Xu, Jimmy; Adam, Douglas; Young, Rob

    2003-01-01

    This document represents a presentation offered by the Jet Propulsion Laboratory, with assistance from researchers from Brown University and Northrop Grumman. The presentation took place in Seoul, Korea in July 2003 and attempted to demonstrate the fabrication approach regarding the development of high quality factor (high-Q) mechanical oscillators (in the forms of a tunable nanotube resonator and a nanotube array radio frequency [RF] filter) aimed at signal processing and based on carbon nanotubes. The presentation also addressed parallel efforts to develop both in-plane single nanotube resonators as well as vertical array power devices.

  20. Ambipolar transistors based on random networks of WS2 nanotubes

    NASA Astrophysics Data System (ADS)

    Sugahara, Mitsunari; Kawai, Hideki; Yomogida, Yohei; Maniwa, Yutaka; Okada, Susumu; Yanagi, Kazuhiro

    2016-07-01

    WS2 nanotubes are rolled multiwalled nanotubes made of a layered material, tungsten disulfide. Their fibril structures enable the fabrication of random network films; however, these films are nonconducting, and thus have not been used for electronic applications. Here, we demonstrate that carrier injection into WS2 networks using an electrolyte gating approach could cause these networks to act as semiconducting channels. We clarify the Raman characteristics of WS2 nanotubes under electrolyte gating and confirm the feasibility of the injection of electrons and holes. We reveal ambipolar behaviors of the WS2 nanotube networks in field-effect transistor setups with electrolyte gating.

  1. Automated manipulation of carbon nanotubes using atomic force microscopy.

    PubMed

    Zhang, Chao; Wu, Sen; Fu, Xing

    2013-01-01

    The manipulation of carbon nanotubes is an important and essential step for carbon-based nanodevice or nanocircuit assembly. However, the conventional push-and-image approach of manipulating carbon nanotubes using atomic force microscopy has low efficiency on account of the reduplicated scanning process during manipulation. In this article, an automated manipulation system is designed and tested. This automated manipulation system, which includes an atomic force microscope platform and a self-developed computer program for one-dimensional manipulation, is capable of automatically moving any assigned individual carbon nanotube to a defined target location without any intermediate scanning procedure. To demonstrate the high-efficiency of this automated manipulation system and its potential applications in nanoassembly, two experiments were conducted. The first experiment used this system to manipulate a carbon nanotube to a defined target location. In the second experiment, this system was used to automatically manipulate several carbon nanotubes for generating and translating a defined pattern of nanotubes. PMID:23646781

  2. Carbon nanotube catalysts: recent advances in synthesis, characterization and applications.

    PubMed

    Yan, Yibo; Miao, Jianwei; Yang, Zhihong; Xiao, Fang-Xing; Yang, Hong Bin; Liu, Bin; Yang, Yanhui

    2015-05-21

    Carbon nanotubes are promising materials for various applications. In recent years, progress in manufacturing and functionalizing carbon nanotubes has been made to achieve the control of bulk and surface properties including the wettability, acid-base properties, adsorption, electric conductivity and capacitance. In order to gain the optimal benefit of carbon nanotubes, comprehensive understanding on manufacturing and functionalizing carbon nanotubes ought to be systematically developed. This review summarizes methodologies of manufacturing carbon nanotubes via arc discharge, laser ablation and chemical vapor deposition and functionalizing carbon nanotubes through surface oxidation and activation, doping of heteroatoms, halogenation, sulfonation, grafting, polymer coating, noncovalent functionalization and nanoparticle attachment. The characterization techniques detecting the bulk nature and surface properties as well as the effects of various functionalization approaches on modifying the surface properties for specific applications in catalysis including heterogeneous catalysis, photocatalysis, photoelectrocatalysis and electrocatalysis are highlighted. PMID:25855947

  3. Constitutive Modeling of Nanotube-Reinforced Polymer Composites

    NASA Technical Reports Server (NTRS)

    Odegard, G. M.; Gates, T. S.; Wise, K. E.

    2002-01-01

    In this study, a technique is presented for developing constitutive models for polymer composite systems reinforced with single-walled carbon nanotubes (SWNT). Because the polymer molecules are on the same size scale as the nanotubes, the interaction at the polymer/nanotube interface is highly dependent on the local molecular structure and bonding. At these small length scales, the lattice structures of the nanotube and polymer chains cannot be considered continuous, and the bulk mechanical properties can no longer be determined through traditional micromechanical approaches that are formulated by using continuum mechanics. It is proposed herein that the nanotube, the local polymer near the nanotube, and the nanotube/polymer interface can be modeled as an effective continuum fiber using an equivalent-continuum modeling method. The effective fiber serves as a means for incorporating micromechanical analyses for the prediction of bulk mechanical properties of SWNT/polymer composites with various nanotube shapes, sizes, concentrations, and orientations. As an example, the proposed approach is used for the constitutive modeling of two SWNT/LaRC-SI (with a PmPV interface) composite systems, one with aligned SWNTs and the other with three-dimensionally randomly oriented SWNTs. The Young's modulus and shear modulus have been calculated for the two systems for various nanotube lengths and volume fractions.

  4. Constitutive Modeling of Nanotube-Reinforced Polymer Composite Systems

    NASA Technical Reports Server (NTRS)

    Odegard, Gregory M.; Harik, Vasyl M.; Wise, Kristopher E.; Gates, Thomas S.

    2001-01-01

    In this study, a technique has been proposed for developing constitutive models for polymer composite systems reinforced with single-walled carbon nanotubes (SWNT). Since the polymer molecules are on the same size scale as the nanotubes, the interaction at the polymer/nanotube interface is highly dependent on the local molecular structure and bonding. At these small length scales, the lattice structures of the nanotube and polymer chains cannot be considered continuous, and the bulk mechanical properties of the SWNT/polymer composites can no longer be determined through traditional micromechanical approaches that are formulated using continuum mechanics. It is proposed herein that the nanotube, the local polymer near the nanotube, and the nanotube/polymer interface can be modeled as an effective continuum fiber using an equivalent-continuum modeling method. The effective fiber retains the local molecular structure and bonding information and serves as a means for incorporating micromechanical analyses for the prediction of bulk mechanical properties of SWNT/polymer composites with various nanotube sizes and orientations. As an example, the proposed approach is used for the constitutive modeling of two SWNT/polyethylene composite systems, one with continuous and aligned SWNT and the other with discontinuous and randomly aligned nanotubes.

  5. Constitutive Modeling of Nanotube-Reinforced Polymer Composite Systems

    NASA Technical Reports Server (NTRS)

    Odegard, Gregory M.; Harik, Vasyl M.; Wise, Kristopher E.; Gates, Thomas S.

    2004-01-01

    In this study, a technique has been proposed for developing constitutive models for polymer composite systems reinforced with single-walled carbon nanotubes (SWNT). Since the polymer molecules are on the same size scale as the nanotubes, the interaction at the polymer/nanotube interface is highly dependent on the local molecular structure and bonding. At these small length scales, the lattice structures of the nanotube and polymer chains cannot be considered continuous, and the bulk mechanical properties of the SWNT/polymer composites can no longer be determined through traditional micromechanical approaches that are formulated using continuum mechanics. It is proposed herein that the nanotube, the local polymer near the nanotube, and the nanotube/polymer interface can be modeled as an effective continuum fiber using an equivalent-continuum modeling method. The effective fiber retains the local molecular structure and bonding information and serves as a means for incorporating micromechanical analyses for the prediction of bulk mechanical properties of SWNT/polymer composites with various nanotube sizes and orientations. As an example, the proposed approach is used for the constitutive modeling of two SWNT/polyethylene composite systems, one with continuous and aligned SWNT and the other with discontinuous and randomly aligned nanotubes.

  6. Structure of boron nitride nanotubes

    SciTech Connect

    Buranova, Yu. S. Kulnitskiy, B. A.; Perezhogin, I. A.; Blank, V. D.

    2015-01-15

    The crystallographic structure of boron nitride nanotubes has been investigated. Various defects that may arise during nanotube synthesis are revealed by electron microscopy. Nanotubes with different numbers of walls and different diameters are modeled by molecular dynamics methods. Structural features of single-wall nanotubes are demonstrated. The causes of certain defects in multiwall nanotubes are indicated.

  7. High frequency nanotube oscillator

    DOEpatents

    Peng, Haibing; Zettl, Alexander K.

    2012-02-21

    A tunable nanostructure such as a nanotube is used to make an electromechanical oscillator. The mechanically oscillating nanotube can be provided with inertial clamps in the form of metal beads. The metal beads serve to clamp the nanotube so that the fundamental resonance frequency is in the microwave range, i.e., greater than at least 1 GHz, and up to 4 GHz and beyond. An electric current can be run through the nanotube to cause the metal beads to move along the nanotube and changing the length of the intervening nanotube segments. The oscillator can operate at ambient temperature and in air without significant loss of resonance quality. The nanotube is can be fabricated in a semiconductor style process and the device can be provided with source, drain, and gate electrodes, which may be connected to appropriate circuitry for driving and measuring the oscillation. Novel driving and measuring circuits are also disclosed.

  8. Triplex inducer-directed self-assembly of single-walled carbon nanotubes: a triplex DNA-based approach for controlled manipulation of nanostructures

    PubMed Central

    Zhao, Chao; Qu, Konggang; Xu, Can; Ren, Jinsong; Qu, Xiaogang

    2011-01-01

    As a promising strategy for artificially control of gene expression, reversible assembly of nanomaterials and DNA nanomachine, DNA triplex formation has received much attention. Carbon nanotubes as gene and drug delivery vector or as ‘building blocks’ in nano/microelectronic devices have been successfully explored. Therefore, studies on triplex DNA-based carbon nanotube hybrid materials are important for development of smart nanomaterials and for gene therapy. In this report, a small molecule directed single-walled carbon nanotubes (SWNTs) self-assembly assay has been developed by disproportionation of SWNTs–dT22·dA22 duplex into triplex dT22·dA22·dT22 and dA22 by a triplex formation inducer, coralyne. This has been studied by circular dichroism, light scattering (LS) spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), electrophoretic mobility shift assay and supported by using DNA random sequence. In contrast, SWNTs do not aggregate under the same experimental conditions when the small molecules used can not induce dT22·dA22·dT22 triplex formation. Therefore, this novel small molecule-directed SWNTs self-assembly assay has also been used for screening of triplex inducers in our studies. PMID:21227925

  9. Atomistic Modeling of Thermal Conductivity of Epoxy Nanotube Composites

    NASA Astrophysics Data System (ADS)

    Fasanella, Nicholas A.; Sundararaghavan, Veera

    2016-05-01

    The Green-Kubo method was used to investigate the thermal conductivity as a function of temperature for epoxy/single wall carbon nanotube (SWNT) nanocomposites. An epoxy network of DGEBA-DDS was built using the `dendrimer' growth approach, and conductivity was computed by taking into account long-range Coulombic forces via a k-space approach. Thermal conductivity was calculated in the direction perpendicular to, and along the SWNT axis for functionalized and pristine SWNT/epoxy nanocomposites. Inefficient phonon transport at the ends of nanotubes is an important factor in the thermal conductivity of the nanocomposites, and for this reason discontinuous nanotubes were modeled in addition to long nanotubes. The thermal conductivity of the long, pristine SWNT/epoxy system is equivalent to that of an isolated SWNT along its axis, but there was a 27% reduction perpendicular to the nanotube axis. The functionalized, long SWNT/epoxy system had a very large increase in thermal conductivity along the nanotube axis (~700%), as well as the directions perpendicular to the nanotube (64%). The discontinuous nanotubes displayed an increased thermal conductivity along the SWNT axis compared to neat epoxy (103-115% for the pristine SWNT/epoxy, and 91-103% for functionalized SWNT/epoxy system). The functionalized system also showed a 42% improvement perpendicular to the nanotube, while the pristine SWNT/epoxy system had no improvement over epoxy. The thermal conductivity tensor is averaged over all possible orientations to see the effects of randomly orientated nanotubes, and allow for experimental comparison. Excellent agreement is seen for the discontinuous, pristine SWNT/epoxy nanocomposite. These simulations demonstrate there exists a threshold of the SWNT length where the best improvement for a composite system with randomly oriented nanotubes would transition from pristine SWNTs to functionalized SWNTs.

  10. Working Toward Nanotube Composites

    NASA Technical Reports Server (NTRS)

    Arepalli, Sivaram; Nikolaev, Pavel; Gorelik, Olga; Hadjiev, Victor G.; Scott, Carl D.; Files, Bradley S.

    2001-01-01

    One of the most attractive applications of single-wall carbon nanotubes (SWNT) is found in the area of structural materials. Nanotubes have a unique combination of high strength, modulus, and elongation to failure, and therefore have potential to significantly enhance the mechanical properties of today's composites. This is especially attractive for the aerospace industry looking for any chance to save weight. This is why NASA has chosen to tackle this difficult application of SWNT. Nanotube properties differ significantly from that of conventional carbon fibers, and a whole new set of problems, including adhesion and dispersion in the adhesive polymer matrix, must be resolved in order to engineer superior composite materials. From recent work on a variety of applications it is obvious that the wide range of research in nanotubes will lead to advances in physics, chemistry, and engineering. However, the possibility of ultralightweight structures is what causes dreamers to really get excited. One of the important issues in composite engineering is aspect ratio of the fibers, since it affects load transfer in composites. Nanotube length was a gray area for years, since they are formed in bundles, making it impossible to monitor individual nanotube length. Even though bundles are observed to be tens and hundreds of microns long, they can be built of relatively short tubes weakly bound by Van der Waals forces. Nanotube length can be affected by subsequent purification and ultrasound processing, which has been necessary in order to disperse nanotubes and introduce them into a polymer matrix. Some calculations show that nanotubes with 10(exp 5) aspect ratio may be necessary to achieve good load transfer. We show here that nanotubes produced in our laser system are as much as tens of microns long and get cut into lengths of hundreds of nanometers during ultrasound processing. Nanotube length was measured by AFM on pristine nanotube specimens as well, as after sonication

  11. Constitutive Modeling of Nanotube-Reinforced Polymer Composites

    NASA Technical Reports Server (NTRS)

    Odegard, G. M.; Gates, T. S.; Wise, K. E.; Park, C.; Siochi, E. J.; Bushnell, Dennis M. (Technical Monitor)

    2002-01-01

    In this study, a technique is presented for developing constitutive models for polymer composite systems reinforced with single-walled carbon nanotubes (SWNT). Because the polymer molecules are on the same size scale as the nanotubes, the interaction at the polymer/nanotube interface is highly dependent on the local molecular structure and bonding. At these small length scales, the lattice structures of the nanotube and polymer chains cannot be considered continuous, and the bulk mechanical properties can no longer be determined through traditional micromechanical approaches that are formulated by using continuum mechanics. It is proposed herein that the nanotube, the local polymer near the nanotube, and the nanotube/polymer interface can be modeled as an effective continuum fiber using an equivalent-continuum modeling method. The effective fiber serves as a means for incorporating micromechanical analyses for the prediction of bulk mechanical properties of SWNT/polymer composites with various nanotube lengths, concentrations, and orientations. As an example, the proposed approach is used for the constitutive modeling of two SWNT/polyimide composite systems.

  12. Applications of Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Ajayan, Pulickel M.; Zhou, Otto Z.

    Carbon nanotubes have attracted the fancy of many scientists worldwide. The small dimensions, strength and the remarkable physical properties of these structures make them a very unique material with a whole range of promising applications. In this review we describe some of the important materials science applications of carbon nanotubes. Specifically we discuss the electronic and electrochemical applications of nanotubes, nanotubes as mechanical reinforcements in high performance composites, nanotube-based field emitters, and their use as nanoprobes in metrology and biological and chemical investigations, and as templates for the creation of other nanostructures. Electronic properties and device applications of nanotubes are treated elsewhere in the book. The challenges that ensue in realizing some of these applications are also discussed from the point of view of manufacturing, processing, and cost considerations.

  13. Multiscale simulation of carbon nanotube devices

    NASA Astrophysics Data System (ADS)

    Adessi, C.; Avriller, R.; Blase, X.; Bournel, A.; Cazin d'Honincthun, H.; Dollfus, P.; Frégonèse, S.; Galdin-Retailleau, S.; López-Bezanilla, A.; Maneux, C.; Nha Nguyen, H.; Querlioz, D.; Roche, S.; Triozon, F.; Zimmer, T.

    2009-05-01

    In recent years, the understanding and accurate simulation of carbon nanotube-based devices has become very challenging. Conventional simulation tools of microelectronics are necessary to envision the performance and use of nanotube transistors and circuits, but the models need to be refined to properly describe the full complexity of such novel type of devices at the nanoscale. Indeed, many issues such as contact resistance, low dimensional electrostatics and screening effects, as well as nanotube doping or functionalization, demand for more accurate quantum approaches. In this article, we review our recent progress on multiscale simulations which aim at bridging first principles calculations with compact modelling, including the comparison between semi-classical Monte Carlo and quantum transport approaches. To cite this article: C. Adessi et al., C. R. Physique 10 (2009).

  14. Water-assisted chemical vapor deposition synthesis of boron nitride nanotubes and their photoluminescence property

    NASA Astrophysics Data System (ADS)

    Li, Juan; Li, Jianbao; Yin, Yanchun; Chen, Yongjun; Bi, Xiaofan

    2013-09-01

    A novel water-assisted chemical vapor deposition (CVD) method for the efficient synthesis of boron nitride (BN) nanotubes is demonstrated. The replacement of metal oxide by water vapor could continuously generate intermediate boron oxide vapor and enhance the production of BN nanotubes. The nanotubes synthesized when an appropriate amount of water vapor was introduced had an average diameter of about 80 nm and lengths of several hundred μm. The diameter and yield of nanotubes could be controlled by tuning the amount of water vapor. This simple water-assisted CVD approach paves a new path to the fabrication of BN nanotubes in large quantities.

  15. Reinforced Carbon Nanotubes.

    DOEpatents

    Ren, Zhifen; Wen, Jian Guo; Lao, Jing Y.; Li, Wenzhi

    2005-06-28

    The present invention relates generally to reinforced carbon nanotubes, and more particularly to reinforced carbon nanotubes having a plurality of microparticulate carbide or oxide materials formed substantially on the surface of such reinforced carbon nanotubes composite materials. In particular, the present invention provides reinforced carbon nanotubes (CNTs) having a plurality of boron carbide nanolumps formed substantially on a surface of the reinforced CNTs that provide a reinforcing effect on CNTs, enabling their use as effective reinforcing fillers for matrix materials to give high-strength composites. The present invention also provides methods for producing such carbide reinforced CNTs.

  16. Gallium nitride nanotube lasers

    SciTech Connect

    Li, Changyi; Liu, Sheng; Hurtado, Antonio; Wright, Jeremy Benjamin; Xu, Huiwen; Luk, Ting Shan; Figiel, Jeffrey J.; Brener, Igal; Brueck, Steven R. J.; Wang, George T.

    2015-01-01

    Lasing is demonstrated from gallium nitride nanotubes fabricated using a two-step top-down technique. By optically pumping, we observed characteristics of lasing: a clear threshold, a narrow spectral, and guided emission from the nanotubes. In addition, annular lasing emission from the GaN nanotube is also observed, indicating that cross-sectional shape control can be employed to manipulate the properties of nanolasers. The nanotube lasers could be of interest for optical nanofluidic applications or application benefitting from a hollow beam shape.

  17. Enhanced Hole Extraction in Perovskite Solar Cells Through Carbon Nanotubes.

    PubMed

    Habisreutinger, Severin N; Leijtens, Tomas; Eperon, Giles E; Stranks, Samuel D; Nicholas, Robin J; Snaith, Henry J

    2014-12-01

    Here, we report the use of polymer-wrapped carbon nanotubes as a means to enhance charge extraction through undoped spiro-OMeTAD. With this approach a good solar cell performance is achieved without the implementation of conventional doping methods. We demonstrate that a stratified two-layer architecture of sequentially deposited layers of carbon nanotubes and spiro-OMeTAD, outperforms a conventional blend of the hole-conductor and the carbon nanotubes. We also provide insights into the mechanism of the rapid hole extraction observed in the two-layer approach. PMID:26278955

  18. Single-walled metal oxide nanotubes and nanotube membranes for molecular separations

    NASA Astrophysics Data System (ADS)

    Kang, Dun-Yen

    Single-walled nanotubes have been considered essential “building-blocks” in nanotechnology and emerging materials for molecular recognition-based applications, such as molecular sensing, catalysis, and separations. Two critical obstacles in the development of functional nanotube-based devices are: (a) the difficulty of creating diverse functionality at the interior surfaces of single-walled nanotubes, and (b) the lack of effective approaches for fabricating scalable technological platforms with nanotube materials. This thesis describes my work addressing key fundamental issues in nanotube science and technology; particularly regarding the synthesis, characterization, and functionalization of single-walled metal oxide nanotubes (SWNTs) (Chapters 2, 3, 4),and approaches for applying SWNTs in scalable separation platforms for potentially achieving high performance (Chapters 5, 6, 7). The above, rather ambitious, objectives were addressed in a step-wise manner in this work. First, I acquired a detailed fundamental understanding of the inner surface properties of aluminosilicate SWNTs (Chapter 2). The investigations included elucidating molecular level details of dehydration and dehydroxylation phenomena in aluminosilicate single-walled nanotubes with a combination of several temperature-dependent solid-state characterization techniques. Critical information from this study enables a number of subsequent processes such as interior modification, molecular transport, and controlled delivery of molecules. In Chapter 3, a successful post-synthesis interior functionalization methodology is discussed, with the appropriately dehydrated or dehydroxylated nanotubes as the starting materials. Through surface reactions involving organosilane precursors and the inner wall of the nanotube, diverse organic entities can be immobilized at the inner surface of aluminosilicate nanotubes and thereby the hydrophilicity and interior surface properties can be tailored. This study was the

  19. Filling of carbon nanotubes and nanofibres

    PubMed Central

    Gately, Reece D

    2015-01-01

    Summary The reliable production of carbon nanotubes and nanofibres is a relatively new development, and due to their unique structure, there has been much interest in filling their hollow interiors. In this review, we provide an overview of the most common approaches for filling these carbon nanostructures. We highlight that filled carbon nanostructures are an emerging material for biomedical applications. PMID:25821693

  20. Flexible high-performance carbon nanotube integrated circuits.

    PubMed

    Sun, Dong-ming; Timmermans, Marina Y; Tian, Ying; Nasibulin, Albert G; Kauppinen, Esko I; Kishimoto, Shigeru; Mizutani, Takashi; Ohno, Yutaka

    2011-03-01

    Carbon nanotube thin-film transistors are expected to enable the fabrication of high-performance, flexible and transparent devices using relatively simple techniques. However, as-grown nanotube networks usually contain both metallic and semiconducting nanotubes, which leads to a trade-off between charge-carrier mobility (which increases with greater metallic tube content) and on/off ratio (which decreases). Many approaches to separating metallic nanotubes from semiconducting nanotubes have been investigated, but most lead to contamination and shortening of the nanotubes, thus reducing performance. Here, we report the fabrication of high-performance thin-film transistors and integrated circuits on flexible and transparent substrates using floating-catalyst chemical vapour deposition followed by a simple gas-phase filtration and transfer process. The resulting nanotube network has a well-controlled density and a unique morphology, consisting of long (~10 µm) nanotubes connected by low-resistance Y-shaped junctions. The transistors simultaneously demonstrate a mobility of 35 cm(2) V(-1) s(-1) and an on/off ratio of 6 × 10(6). We also demonstrate flexible integrated circuits, including a 21-stage ring oscillator and master-slave delay flip-flops that are capable of sequential logic. Our fabrication procedure should prove to be scalable, for example, by using high-throughput printing techniques. PMID:21297625

  1. Fluidic nanotubes and devices

    DOEpatents

    Yang, Peidong; He, Rongrui; Goldberger, Joshua; Fan, Rong; Wu, Yiying; Li, Deyu; Majumdar, Arun

    2008-04-08

    Fluidic nanotube devices are described in which a hydrophilic, non-carbon nanotube, has its ends fluidly coupled to reservoirs. Source and drain contacts are connected to opposing ends of the nanotube, or within each reservoir near the opening of the nanotube. The passage of molecular species can be sensed by measuring current flow (source-drain, ionic, or combination). The tube interior can be functionalized by joining binding molecules so that different molecular species can be sensed by detecting current changes. The nanotube may be a semiconductor, wherein a tubular transistor is formed. A gate electrode can be attached between source and drain to control current flow and ionic flow. By way of example an electrophoretic array embodiment is described, integrating MEMs switches. A variety of applications are described, such as: nanopores, nanocapillary devices, nanoelectrophoretic, DNA sequence detectors, immunosensors, thermoelectric devices, photonic devices, nanoscale fluidic bioseparators, imaging devices, and so forth.

  2. Fluidic nanotubes and devices

    DOEpatents

    Yang, Peidong; He, Rongrui; Goldberger, Joshua; Fan, Rong; Wu, Yiying; Li, Deyu; Majumdar, Arun

    2010-01-10

    Fluidic nanotube devices are described in which a hydrophilic, non-carbon nanotube, has its ends fluidly coupled to reservoirs. Source and drain contacts are connected to opposing ends of the nanotube, or within each reservoir near the opening of the nanotube. The passage of molecular species can be sensed by measuring current flow (source-drain, ionic, or combination). The tube interior can be functionalized by joining binding molecules so that different molecular species can be sensed by detecting current changes. The nanotube may be a semiconductor, wherein a tubular transistor is formed. A gate electrode can be attached between source and drain to control current flow and ionic flow. By way of example an electrophoretic array embodiment is described, integrating MEMs switches. A variety of applications are described, such as: nanopores, nanocapillary devices, nanoelectrophoretic, DNA sequence detectors, immunosensors, thermoelectric devices, photonic devices, nanoscale fluidic bioseparators, imaging devices, and so forth.

  3. Quantum Monte Carlo calculations for carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Luu, Thomas; Lähde, Timo A.

    2016-04-01

    We show how lattice quantum Monte Carlo can be applied to the electronic properties of carbon nanotubes in the presence of strong electron-electron correlations. We employ the path-integral formalism and use methods developed within the lattice QCD community for our numerical work. Our lattice Hamiltonian is closely related to the hexagonal Hubbard model augmented by a long-range electron-electron interaction. We apply our method to the single-quasiparticle spectrum of the (3,3) armchair nanotube configuration, and consider the effects of strong electron-electron correlations. Our approach is equally applicable to other nanotubes, as well as to other carbon nanostructures. We benchmark our Monte Carlo calculations against the two- and four-site Hubbard models, where a direct numerical solution is feasible.

  4. Mesoscopic modeling of cancer photothermal therapy using single-walled carbon nanotubes and near infrared radiation: insights through an off-lattice Monte Carlo approach

    NASA Astrophysics Data System (ADS)

    Gong, Feng; Hongyan, Zhang; Papavassiliou, Dimitrios V.; Bui, Khoa; Lim, Christina; Duong, Hai M.

    2014-05-01

    Single-walled carbon nanotubes (SWNTs) are promising heating agents in cancer photothermal therapy when under near infrared radiation, yet few efforts have been focused on the quantitative understanding of the photothermal energy conversion in biological systems. In this article, a mesoscopic study that takes into account SWNT morphologies (diameter and aspect ratio) and dispersions (orientation and concentration), as well as thermal boundary resistance, is performed by means of an off-lattice Monte Carlo simulation. Results indicate that SWNTs with orientation perpendicular to the laser, smaller diameter and better dispersion have higher heating efficiency in cancer photothermal therapy. Thermal boundary resistances greatly inhibit thermal energy transfer away from SWNTs, thereby affecting their heating efficiency. Through appropriate interfacial modification around SWNTs, compared to the surrounding healthy tissue, a higher temperature of the cancer cell can be achieved, resulting in more effective cancer photothermal therapy. These findings promise to bridge the gap between macroscopic and microscopic computational studies of cancer photothermal therapy.

  5. Buckling of Carbon Nanotube-Reinforced Polymer Laminated Composite Materials Subjected to Axial Compression and Shear Loadings

    NASA Technical Reports Server (NTRS)

    Riddick, J. C.; Gates, T. S.; Frankland, S.-J. V.

    2005-01-01

    A multi-scale method to predict the stiffness and stability properties of carbon nanotube-reinforced laminates has been developed. This method is used in the prediction of the buckling behavior of laminated carbon nanotube-polyethylene composites formed by stacking layers of carbon nanotube-reinforced polymer with the nanotube alignment axes of each layer oriented in different directions. Linking of intrinsic, nanoscale-material definitions to finite scale-structural properties is achieved via a hierarchical approach in which the elastic properties of the reinforced layers are predicted by an equivalent continuum modeling technique. Solutions for infinitely long symmetrically laminated nanotube-reinforced laminates with simply-supported or clamped edges subjected to axial compression and shear loadings are presented. The study focuses on the influence of nanotube volume fraction, length, orientation, and functionalization on finite-scale laminate response. Results indicate that for the selected laminate configurations considered in this study, angle-ply laminates composed of aligned, non-functionalized carbon nanotube-reinforced lamina exhibit the greatest buckling resistance with 1% nanotube volume fraction of 450 nm uniformly-distributed carbon nanotubes. In addition, hybrid laminates were considered by varying either the volume fraction or nanotube length through-the-thickness of a quasi-isotropic laminate. The ratio of buckling load-to-nanotube weight percent for the hybrid laminates considered indicate the potential for increasing the buckling efficiency of nanotube-reinforced laminates by optimizing nanotube size and proportion with respect to laminate configuration.

  6. Capture and manipulation of hybrid DNAs by carbon nanotube bundles

    NASA Astrophysics Data System (ADS)

    Li, Zhenhai; Yang, Wei

    2010-05-01

    When approached from both sides, a piece of single-duplex-single DNA may be drawn into the inlets of two bundles of carbon nanotubes. This provides opportunities to manipulate the DNA by two bundles of nanotubes. The capture and manipulation processes envisaged above are simulated by molecular dynamics in this work. The radius of the carbon nanotube and the ambient temperature show the effects on the spontaneous insertion of DNA strands. This procedure, if successful, could be used for capturing expectant sdsDNAs, with subsequent manipulation to pull or to unzip the captured DNA.

  7. Carbon Nanotube Solar Cells

    PubMed Central

    Klinger, Colin; Patel, Yogeshwari; Postma, Henk W. Ch.

    2012-01-01

    We present proof-of-concept all-carbon solar cells. They are made of a photoactive side of predominantly semiconducting nanotubes for photoconversion and a counter electrode made of a natural mixture of carbon nanotubes or graphite, connected by a liquid electrolyte through a redox reaction. The cells do not require rare source materials such as In or Pt, nor high-grade semiconductor processing equipment, do not rely on dye for photoconversion and therefore do not bleach, and are easy to fabricate using a spray-paint technique. We observe that cells with a lower concentration of carbon nanotubes on the active semiconducting electrode perform better than cells with a higher concentration of nanotubes. This effect is contrary to the expectation that a larger number of nanotubes would lead to more photoconversion and therefore more power generation. We attribute this to the presence of metallic nanotubes that provide a short for photo-excited electrons, bypassing the load. We demonstrate optimization strategies that improve cell efficiency by orders of magnitude. Once it is possible to make semiconducting-only carbon nanotube films, that may provide the greatest efficiency improvement. PMID:22655070

  8. Nanotube composite carbon fibers

    NASA Astrophysics Data System (ADS)

    Andrews, R.; Jacques, D.; Rao, A. M.; Rantell, T.; Derbyshire, F.; Chen, Y.; Chen, J.; Haddon, R. C.

    1999-08-01

    Single walled carbon nanotubes (SWNTs) were dispersed in isotropic petroleum pitch matrices to form nanotube composite carbon fibers with enhanced mechanical and electrical properties. We find that the tensile strength, modulus, and electrical conductivity of a pitch composite fiber with 5 wt % loading of purified SWNTs are enhanced by ˜90%, ˜150%, and 340% respectively, as compared to the corresponding values in unmodified isotropic pitch fibers. These results serve to highlight the potential that exits for developing a spectrum of material properties through the selection of the matrix, nanotube dispersion, alignment, and interfacial bonding.

  9. Nanotube resonator devices

    SciTech Connect

    Jensen, Kenneth J; Zettl, Alexander K; Weldon, Jeffrey A

    2014-05-06

    A fully-functional radio receiver fabricated from a single nanotube is being disclosed. Simultaneously, a single nanotube can perform the functions of all major components of a radio: antenna, tunable band-pass filter, amplifier, and demodulator. A DC voltage source, as supplied by a battery, can power the radio. Using carrier waves in the commercially relevant 40-400 MHz range and both frequency and amplitude modulation techniques, successful music and voice reception has been demonstrated. Also disclosed are a radio transmitter and a mass sensor using a nanotube resonator device.

  10. Tunable multiwalled nanotube resonator

    DOEpatents

    Zettl, Alex K.; Jensen, Kenneth J.; Girit, Caglar; Mickelson, William E.; Grossman, Jeffrey C.

    2011-03-29

    A tunable nanoscale resonator has potential applications in precise mass, force, position, and frequency measurement. One embodiment of this device consists of a specially prepared multiwalled carbon nanotube (MWNT) suspended between a metal electrode and a mobile, piezoelectrically controlled contact. By harnessing a unique telescoping ability of MWNTs, one may controllably slide an inner nanotube core from its outer nanotube casing, effectively changing its length and thereby changing the tuning of its resonance frequency. Resonant energy transfer may be used with a nanoresonator to detect molecules at a specific target oscillation frequency, without the use of a chemical label, to provide label-free chemical species detection.

  11. Tunable multiwalled nanotube resonator

    DOEpatents

    Jensen, Kenneth J; Girit, Caglar O; Mickelson, William E; Zettl, Alexander K; Grossman, Jeffrey C

    2013-11-05

    A tunable nanoscale resonator has potential applications in precise mass, force, position, and frequency measurement. One embodiment of this device consists of a specially prepared multiwalled carbon nanotube (MWNT) suspended between a metal electrode and a mobile, piezoelectrically controlled contact. By harnessing a unique telescoping ability of MWNTs, one may controllably slide an inner nanotube core from its outer nanotube casing, effectively changing its length and thereby changing the tuning of its resonance frequency. Resonant energy transfer may be used with a nanoresonator to detect molecules at a specific target oscillation frequency, without the use of a chemical label, to provide label-free chemical species detection.

  12. Optimizing the Electronic Properties of Carbon Nanotubes using Amphoteric Doping

    SciTech Connect

    Sumpter, Bobby G; Meunier, Vincent

    2008-01-01

    Present day semiconductor devices are rapidly approaching their physical limits, prompting an increasing number of researchers across multiple disciplines to attempt devising innovative ways for decreasing the size and increasing the performance of critical features in microelectronic circuits. One possible route is based on the idea of using molecules and molecular structures as functional electronic devices. Carbon nanotubes may provide one of the best materials for molecular electronic devices as they present a flexible and well structured architecture. However, practical realizations of new nanotube-based electronic devices hinge on a number of outstanding problems, such as the capability of achieving large-scale air-stable and controlled doping. Amphoteric doping by encapsulating suitable organic molecules inside of nanotubes may hold tremendous promise in this respect. In order to investigate and optimize the electronic transport properties in carbon nanotubes doped with organic molecules we have performed large-scale quantum electronic structure calculations coupled with a Green's function formulation for determining the conductance. By implementing this hybrid computational approach for examination of the electronic properties of molecular-based structures, an efficient and accurate procedure has been demonstrated for studying the effects of amphoteric doping of carbon nanotubes. With this method, a computational framework for the optimal design of nanotube based electronic devices is becoming routinely accessible. Results from our calculations suggest that the electronic structure of a carbon nanotube can be easily manipulated by encapsulating appropriate organic molecules leading to charge transfer processes that induce efficient n- and p-type doping of the carbon nanotube. Even though a molecule may cause n- or p-doping, we have found it to generally have minor effects on the transport properties of the nanotube as compared to a pristine tube.

  13. Dispersionless propagation of electron wavepackets in single-walled carbon nanotubes

    SciTech Connect

    Rosati, Roberto; Rossi, Fausto; Dolcini, Fabrizio

    2015-06-15

    We investigate the propagation of electron wavepackets in single-walled carbon nanotubes via a Lindblad-based density-matrix approach that enables us to account for both dissipation and decoherence effects induced by various phonon modes. We show that, while in semiconducting nanotubes the wavepacket experiences the typical dispersion of conventional materials, in metallic nanotubes its shape remains essentially unaltered, even in the presence of the electron-phonon coupling, up to micron distances at room temperature.

  14. Carbon Nanotube and Graphene Nanoelectromechanical Systems

    NASA Astrophysics Data System (ADS)

    Aleman, Benjamin Jose

    One-dimensional and two-dimensional forms of carbon are composed of sp 2-hybridized carbon atoms arranged in a regular hexagonal, honeycomb lattice. The two-dimensional form, called graphene, is a single atomic layer of hexagonally-bonded carbon atoms. The one-dimensional form, known as a carbon nanotube, can be conceptualized as a rectangular piece of graphene wrapped into a seamless, high-aspect-ratio cylinder or tube. This dissertation addresses the physics and applied physics of these one and two-dimensional carbon allotropes in nanoelectromechanical systems (NEMS). First, we give a theoretical background on the electrodynamics and mechanics of carbon nanotube NEMS. We then describe basic experimental techniques, such as electron and scanning probe microscopy, that we then use to probe static and dynamic mechanical and electronic behavior of the carbon nanotube NEMS. For example, we observe and control non-linear beam bending and single-electron quantum tunneling effects in carbon nanotube resonators. We then describe parametric amplification, self-oscillation behavior, and dynamic, non-linear effects in carbon nanotube mechanical resonators. We also report a novel approach to fabricate carbon nanotube atomic force microscopy (AFM) probes, and show that they can lead to exceptional lateral resolution enhancement in AFM when imaging both hard and soft (biological) materials. Finally, we describe novel fabrication techniques for large-area, suspended graphene membranes, and utilize these membranes as TEM-transparent, AFM-compatible, NEMS resonators. Laser-driven mechanical vibrations of the graphene resonators are detected by optical interferometry and several vibration harmonics are observed. A degeneracy splitting is observed in the vibrational modes of square-geometry resonators. We then attribute the observed degeneracy splitting to local mass inhomogeneities and membrane defects, and find good overall agreement with the developed theoretical model.

  15. Theoretical design of the cyclic lipopeptide nanotube as a molecular channel in the lipid bilayer, molecular dynamics and quantum mechanics approach.

    PubMed

    Khavani, Mohammad; Izadyar, Mohammad; Housaindokht, Mohammad Reza

    2015-10-14

    In this article, cyclic peptides (CP) with lipid substituents were theoretically designed. The dynamical behavior of the CP dimers and the cyclic peptide nanotube (CPNT) without lipid substituents in the solution (water and chloroform) during the 50 ns molecular dynamic (MD) simulations has been investigated. As a result, the CP dimers and CPNT in a non-polar solvent are more stable than in a polar solvent and CPNT is a good container for non-polar small molecules such as chloroform. The effect of the lipid substituents on the CP dimers and CPNT has been investigated in the next stage of our studies. Accordingly, these substituents increase the stability of the CP dimers and CPNT, significantly, in polar solvents. MM-PBSA and MM-GBSA calculations confirm that substitution has an important effect on the stability of the CP dimers and CPNT. Finally, the dynamical behavior of CPNT with lipid substituents in a fully hydrated DMPC bilayer shows the high ability of this structure for molecule transmission across the lipid membrane. This structure is stable enough to be used as a molecular channel. DFT calculations on the CP dimers in the gas phase, water and chloroform, indicate that H-bond formation is the driving force for dimerization. CP dimers are more stable in the gas phase in comparison to in solution. HOMO-LUMO orbital analysis indicates that the interaction of the CP units in the dimer structures is due to the molecular orbital interactions between the NH and CO groups. PMID:26366633

  16. Mechanical integrity of a carbon nanotube/copper-based through-silicon via for 3D integrated circuits: a multi-scale modeling approach.

    PubMed

    Awad, Ibrahim; Ladani, Leila

    2015-12-01

    Carbon nanotube (CNT)/copper (Cu) composite material is proposed to replace Cu-based through-silicon vias (TSVs) in micro-electronic packages. The proposed material is believed to offer extraordinary mechanical and electrical properties and the presence of CNTs in Cu is believed to overcome issues associated with miniaturization of Cu interconnects, such as electromigration. This study introduces a multi-scale modeling of the proposed TSV in order to evaluate its mechanical integrity under mechanical and thermo-mechanical loading conditions. Molecular dynamics (MD) simulation was used to determine CNT/Cu interface adhesion properties. A cohesive zone model (CZM) was found to be most appropriate to model the interface adhesion, and CZM parameters at the nanoscale were determined using MD simulation. CZM parameters were then used in the finite element analysis in order to understand the mechanical and thermo-mechanical behavior of composite TSV at micro-scale. From the results, CNT/Cu separation does not take place prior to plastic deformation of Cu in bending, and separation does not take place when standard thermal cycling is applied. Further investigation is recommended in order to alleviate the increased plastic deformation in Cu at the CNT/Cu interface in both loading conditions. PMID:26559788

  17. Mechanical integrity of a carbon nanotube/copper-based through-silicon via for 3D integrated circuits: a multi-scale modeling approach

    NASA Astrophysics Data System (ADS)

    Awad, Ibrahim; Ladani, Leila

    2015-12-01

    Carbon nanotube (CNT)/copper (Cu) composite material is proposed to replace Cu-based through-silicon vias (TSVs) in micro-electronic packages. The proposed material is believed to offer extraordinary mechanical and electrical properties and the presence of CNTs in Cu is believed to overcome issues associated with miniaturization of Cu interconnects, such as electromigration. This study introduces a multi-scale modeling of the proposed TSV in order to evaluate its mechanical integrity under mechanical and thermo-mechanical loading conditions. Molecular dynamics (MD) simulation was used to determine CNT/Cu interface adhesion properties. A cohesive zone model (CZM) was found to be most appropriate to model the interface adhesion, and CZM parameters at the nanoscale were determined using MD simulation. CZM parameters were then used in the finite element analysis in order to understand the mechanical and thermo-mechanical behavior of composite TSV at micro-scale. From the results, CNT/Cu separation does not take place prior to plastic deformation of Cu in bending, and separation does not take place when standard thermal cycling is applied. Further investigation is recommended in order to alleviate the increased plastic deformation in Cu at the CNT/Cu interface in both loading conditions.

  18. Supercritical-assistant liquid crystal template approach to synthesize mesoporous titania/multiwalled carbon nanotube composites with high visible-light driven photocatalytic performance

    SciTech Connect

    Liu, Chen; Li, Youji Xu, Peng; Li, Ming; Huo, Pingxiang

    2014-12-15

    Graphical abstract: We investigate the influence of mesoporous titania content upon the visible-light driven photocatalytic performance of MPT/MWCNTs in phenol degradation. - Highlights: • MPT/MWCNTs were fabricated by liquid-crystal template in supercritical CO{sub 2}. • MPT/MWCNTs show high visible-light driven photoactivity for phenol degradation. • MPT/MWCNTs also show high reusable photoactivity under visible irradiation. • MPT content can control visible-light driven photoactivity of MPT/MWCNTs. • MPT is not easily broken away from from MPT/MWCNT composites. - Abstract: Mesoporous titania (MPT) was deposited onto multiwalled carbon nanotubes (MWCNTs) by deposition of titanium sol containing liquid-crystal template with assistant of supercritical CO{sub 2}. The products were characterized with various analytical techniques to determine their structural, morphological, optical absorption and photocatalytic properties. The results indicate that in photocatalytic degradation of phenol under visible light, the mixtures or composites of MPT and MWCNT show the high efficiency because of synergies between absorbing visible light, releasing electrons and facilitating transfer of charge carriers of MWCNTs and providing activated centers of MPT. Because of the mutual constraint between MPT and MWCNTs on the photocatalytic efficiency, the optimal loading of MPT in MPT/MWCNT-3 for phenol degradation is 48%. Because the intimate contact between MWCNTs and MPT is more beneficial to electron transformation, photoactivity of mixture is lower than that of composites with high reusable performance. The optimum conditions of phenol degradation were obtained.

  19. Self-Volatilization Approach to Mesoporous Carbon Nanotube/Silver Nanoparticle Hybrids: The Role of Silver in Boosting Li Ion Storage.

    PubMed

    Jiang, Hao; Zhang, Haoxuan; Fu, Yao; Guo, Shaojun; Hu, Yanjie; Zhang, Ling; Liu, Yu; Liu, Honglai; Li, Chunzhong

    2016-01-26

    One of the biggest challenging issues of carbon nanomaterials for Li ion batteries (LIBs) is that they show low initial Coulombic efficiency (CE), leading to a limited specific capacity. Herein, we demonstrate a simple template self-volatilization strategy for in situ synthesis of mesoporous carbon nanotube/Ag nanoparticle (NP) hybrids (Ag-MCNTs) to boost the LIBs' performance. The key concept of Ag-MCNTs for enhancing LIBs is that a small trace of Ag NPs on MCNTS can greatly restrict the formation of a thicker solid electrolyte interphase film, which has been well verified by both transmission electron microscopy results and quantum density functional theory calculations, leading to the highest initial CE in all the reported carbon nanomaterials. This uncovered property of Ag NPs from Ag-MCNTs makes them exhibit a very high reversible capacity of 1637 mAh g(-1) after 400 discharge/charge cycles at 100 mA g(-1), approximately 5 times higher than the theoretical value of a graphite anode (372 mAh g(-1)), excellent rate capability, and long cycle life. PMID:26691283

  20. Transport in Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Datta, S.; Xue, Yong-Qinag; Anantram, M. P.; Saini, Subhash (Technical Monitor)

    1999-01-01

    This presentation discusses coupling between carbon nanotubes (CNT), simple metals (FEG) and a graphene sheet. The graphene sheet did not couple well with FEG, but the combination of a graphene strip and CNT did couple well with most simple metals.

  1. Polymer composites containing nanotubes

    NASA Technical Reports Server (NTRS)

    Bley, Richard A. (Inventor)

    2008-01-01

    The present invention relates to polymer composite materials containing carbon nanotubes, particularly to those containing singled-walled nanotubes. The invention provides a polymer composite comprising one or more base polymers, one or more functionalized m-phenylenevinylene-2,5-disubstituted-p-phenylenevinylene polymers and carbon nanotubes. The invention also relates to functionalized m-phenylenevinylene-2,5-disubstituted-p-phenylenevinylene polymers, particularly to m-phenylenevinylene-2,5-disubstituted-p-phenylenevinylene polymers having side chain functionalization, and more particularly to m-phenylenevinylene-2,5-disubstituted-p-phenylenevinylene polymers having olefin side chains and alkyl epoxy side chains. The invention further relates to methods of making polymer composites comprising carbon nanotubes.

  2. Carbon nanotubes: Fibrillar pharmacology

    NASA Astrophysics Data System (ADS)

    Kostarelos, Kostas

    2010-10-01

    The mechanisms by which chemically functionalized carbon nanotubes flow in blood and are excreted through the kidneys illustrate the unconventional behaviour of these fibrillar nanostructures, and the opportunities they offer as components for the design of advanced delivery vehicles.

  3. Chalcogenide Cobalt telluride nanotubes

    NASA Astrophysics Data System (ADS)

    Dahal, Bishnu; Dulal, Rajendra; Pegg, Ian L.; Philip, John

    Cobalt telluride nanotubes are grown using wet chemical and hydrothermal syntheses. Wet chemical synthesized nanotubes display nearly 1: 1 Co to Te ratio. On the other hand, CoTe nanotubes synthesized using hydrothermal method show excess Co content leading to the compound Co58Te42. Both CoTe and Co58Te42 display magnetic properties, but with totally different characteristics. The Curie temperature of CoTe is higher than 400 K. However, the Tc of Co58Te42 is below 50 K. Transport properties of cobalt telluride (CoTe) nanotube devices show that they exhibit p-type semiconducting behavior. The magnetoresistance measured at 10 K show a magnetoresistance of 54%. . National Science Foundation under ECCS-0845501 and NSF-MRI, DMR-0922997.

  4. Surface functionalization of aluminosilicate nanotubes with organic molecules

    PubMed Central

    Ma, Wei; Yah, Weng On; Otsuka, Hideyuki

    2012-01-01

    Summary The surface functionalization of inorganic nanostructures is an effective approach for enriching the potential applications of existing nanomaterials. Inorganic nanotubes attract great research interest due to their one-dimensional structure and reactive surfaces. In this review paper, recent developments in surface functionalization of an aluminosilicate nanotube, “imogolite”, are introduced. The functionalization processes are based on the robust affinity between phosphate groups of organic molecules and the aluminol (AlOH) surface of imogolite nanotubes. An aqueous modification process employing a water soluble ammonium salt of alkyl phosphate led to chemisorption of molecules on imogolite at the nanotube level. Polymer-chain-grafted imogolite nanotubes were prepared through surface-initiated polymerization. In addition, the assembly of conjugated molecules, 2-(5’’-hexyl-2,2’:5’,2’’-terthiophen-5-yl)ethylphosphonic acid (HT3P) and 2-(5’’-hexyl-2,2’:5’,2’’-terthiophen-5-yl)ethylphosphonic acid 1,1-dioxide (HT3OP), on the imogolite nanotube surface was achieved by introducing a phosphonic acid group to the corresponding molecules. The optical and photophysical properties of these conjugated-molecule-decorated imogolite nanotubes were characterized. Moreover, poly(3-hexylthiophene) (P3HT) chains were further hybridized with HT3P modified imogolite to form a nanofiber hybrid. PMID:22428100

  5. Boron nitride nanotubes

    DOEpatents

    Smith, Michael W.; Jordan, Kevin; Park, Cheol

    2012-06-06

    Boron nitride nanotubes are prepared by a process which includes: (a) creating a source of boron vapor; (b) mixing the boron vapor with nitrogen gas so that a mixture of boron vapor and nitrogen gas is present at a nucleation site, which is a surface, the nitrogen gas being provided at a pressure elevated above atmospheric, e.g., from greater than about 2 atmospheres up to about 250 atmospheres; and (c) harvesting boron nitride nanotubes, which are formed at the nucleation site.

  6. Functionalization of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Webber, Stephen E.

    2003-01-01

    These project will explore the functionalization of carbon nanotubes via the formation of molecular complexes with perylene diimide based systems. It is anticipated that these complexes would be soluble in organic solvent and enable the homogenous dispersion of carbon nanotubes in polymer films. Molecular complexes will be prepared and characterized using standard spectroscopic and thermal analytical techniques. Polymer films will be prepared with these complexes and their properties (electrical and thermal conductivity, mechanical properties, stability) evaluated.

  7. Boron Nitride Nanotubes

    NASA Technical Reports Server (NTRS)

    Smith, Michael W. (Inventor); Jordan, Kevin (Inventor); Park, Cheol (Inventor)

    2012-01-01

    Boron nitride nanotubes are prepared by a process which includes: (a) creating a source of boron vapor; (b) mixing the boron vapor with nitrogen gas so that a mixture of boron vapor and nitrogen gas is present at a nucleation site, which is a surface, the nitrogen gas being provided at a pressure elevated above atmospheric, e.g., from greater than about 2 atmospheres up to about 250 atmospheres; and (c) harvesting boron nitride nanotubes, which are formed at the nucleation site.

  8. Formation of ice nanotube with hydrophobic guests inside carbon nanotube.

    PubMed

    Tanaka, Hideki; Koga, Kenichiro

    2005-09-01

    A composite ice nanotube inside a carbon nanotube has been explored by molecular-dynamics and grand canonical Monte Carlo simulations. It is made from an octagonal ice nanotube whose hollow space contains hydrophobic guest molecules such as neon, argon, and methane. It is shown that the attractive interaction of the guest molecules stabilizes the ice nanotube. The guest occupancy of the hollow space is calculated by the same method as applied to clathrate hydrates. PMID:16164361

  9. Conducting carbonized polyaniline nanotubes

    NASA Astrophysics Data System (ADS)

    Mentus, Slavko; Ćirić-Marjanović, Gordana; Trchová, Miroslava; Stejskal, Jaroslav

    2009-06-01

    Conducting nitrogen-containing carbon nanotubes were synthesized by the carbonization of self-assembled polyaniline nanotubes protonated with sulfuric acid. Carbonization was carried out in a nitrogen atmosphere at a heating rate of 10 °C min-1 up to a maximum temperature of 800 °C. The carbonized polyaniline nanotubes which have a typical outer diameter of 100-260 nm, with an inner diameter of 20-170 nm and a length extending from 0.5 to 0.8 µm, accompanied with very thin nanotubes with outer diameters of 8-14 nm, inner diameters 3.0-4.5 nm and length extending from 0.3 to 1.0 µm, were observed by scanning and transmission electron microscopies. Elemental analysis showed 9 wt% of nitrogen in the carbonized product. Conductivity of the nanotubular PANI precursor, amounting to 0.04 S cm-1, increased to 0.7 S cm-1 upon carbonization. Molecular structure of carbonized polyaniline nanotubes has been analyzed by FTIR and Raman spectroscopies, and their paramagnetic characteristics were compared with the starting PANI nanotubes by EPR spectroscopy.

  10. Transparent conducting oxide nanotubes

    NASA Astrophysics Data System (ADS)

    Alivov, Yahya; Singh, Vivek; Ding, Yuchen; Nagpal, Prashant

    2014-09-01

    Thin film or porous membranes made of hollow, transparent, conducting oxide (TCO) nanotubes, with high chemical stability, functionalized surfaces and large surface areas, can provide an excellent platform for a wide variety of nanostructured photovoltaic, photodetector, photoelectrochemical and photocatalytic devices. While large-bandgap oxide semiconductors offer transparency for incident light (below their nominal bandgap), their low carrier concentration and poor conductivity makes them unsuitable for charge conduction. Moreover, materials with high conductivity have nominally low bandgaps and hence poor light transmittance. Here, we demonstrate thin films and membranes made from TiO2 nanotubes heavily-doped with shallow Niobium (Nb) donors (up to 10%, without phase segregation), using a modified electrochemical anodization process, to fabricate transparent conducting hollow nanotubes. Temperature dependent current-voltage characteristics revealed that TiO2 TCO nanotubes, doped with 10% Nb, show metal-like behavior with resistivity decreasing from 6.5 × 10-4 Ωcm at T = 300 K (compared to 6.5 × 10-1 Ωcm for nominally undoped nanotubes) to 2.2 × 10-4 Ωcm at T = 20 K. Optical properties, studied by reflectance measurements, showed light transmittance up to 90%, within wavelength range 400 nm-1000 nm. Nb doping also improves the field emission properties of TCO nanotubes demonstrating an order of magnitude increase in field-emitter current, compared to undoped samples.

  11. Transparent conducting oxide nanotubes.

    PubMed

    Alivov, Yahya; Singh, Vivek; Ding, Yuchen; Nagpal, Prashant

    2014-09-26

    Thin film or porous membranes made of hollow, transparent, conducting oxide (TCO) nanotubes, with high chemical stability, functionalized surfaces and large surface areas, can provide an excellent platform for a wide variety of nanostructured photovoltaic, photodetector, photoelectrochemical and photocatalytic devices. While large-bandgap oxide semiconductors offer transparency for incident light (below their nominal bandgap), their low carrier concentration and poor conductivity makes them unsuitable for charge conduction. Moreover, materials with high conductivity have nominally low bandgaps and hence poor light transmittance. Here, we demonstrate thin films and membranes made from TiO2 nanotubes heavily-doped with shallow Niobium (Nb) donors (up to 10%, without phase segregation), using a modified electrochemical anodization process, to fabricate transparent conducting hollow nanotubes. Temperature dependent current-voltage characteristics revealed that TiO2 TCO nanotubes, doped with 10% Nb, show metal-like behavior with resistivity decreasing from 6.5 × 10(-4) Ωcm at T = 300 K (compared to 6.5 × 10(-1) Ωcm for nominally undoped nanotubes) to 2.2 × 10(-4) Ωcm at T = 20 K. Optical properties, studied by reflectance measurements, showed light transmittance up to 90%, within wavelength range 400 nm-1000 nm. Nb doping also improves the field emission properties of TCO nanotubes demonstrating an order of magnitude increase in field-emitter current, compared to undoped samples. PMID:25180635

  12. Conducting carbonized polyaniline nanotubes.

    PubMed

    Mentus, Slavko; Cirić-Marjanović, Gordana; Trchová, Miroslava; Stejskal, Jaroslav

    2009-06-17

    Conducting nitrogen-containing carbon nanotubes were synthesized by the carbonization of self-assembled polyaniline nanotubes protonated with sulfuric acid. Carbonization was carried out in a nitrogen atmosphere at a heating rate of 10 degrees C min(-1) up to a maximum temperature of 800 degrees C. The carbonized polyaniline nanotubes which have a typical outer diameter of 100-260 nm, with an inner diameter of 20-170 nm and a length extending from 0.5 to 0.8 microm, accompanied with very thin nanotubes with outer diameters of 8-14 nm, inner diameters 3.0-4.5 nm and length extending from 0.3 to 1.0 microm, were observed by scanning and transmission electron microscopies. Elemental analysis showed 9 wt% of nitrogen in the carbonized product. Conductivity of the nanotubular PANI precursor, amounting to 0.04 S cm(-1), increased to 0.7 S cm(-1) upon carbonization. Molecular structure of carbonized polyaniline nanotubes has been analyzed by FTIR and Raman spectroscopies, and their paramagnetic characteristics were compared with the starting PANI nanotubes by EPR spectroscopy. PMID:19471087

  13. Efficient suppression of nanograss during porous anodic TiO2 nanotubes growth

    NASA Astrophysics Data System (ADS)

    Gui, Qunfang; Yu, Dongliang; Li, Dongdong; Song, Ye; Zhu, Xufei; Cao, Liu; Zhang, Shaoyu; Ma, Weihua; You, Shiyu

    2014-09-01

    When Ti foil was anodized in fluoride-containing electrolyte for a long time, undesired etching-induced “nanograss” would inevitably generate on the top of porous anodic TiO2 nanotubes (PATNTs). The nanograss will hinder the ions transport and in turn yield depressed (photo) electrochemical performance. In order to obtain nanograss-free nanotubes, a modified three-step anodization and two-layer nanostructure of PATNTs were designed to avoid the nanograss. The first layer (L1) nanotubes were obtained by the conventional two-step anodization. After washing and drying processes, the third-step anodization was carried out with the presence of L1 nanotubes. The L1 nanotubes, serving as a sacrificed layer, was etched and transformed into nanograss, while the ultralong nanotubes (L2) were maintained underneath the L1. The bi-layer nanostructure of the nanograss/nanotubes (L1/L2) was then ultrasonically rinsed in deionized water to remove the nanograss (L1 layer). Then much longer nanotubes (L2 layer) with intact nanotube mouths could be obtained. Using this novel approach, the ultralong nanotubes without nanograss can be rationally controlled by adjusting the anodizing times of two layers.

  14. Exploring growth kinetics of carbon nanotube arrays by in situ optical diagnostics and modeling

    SciTech Connect

    Puretzky, Alexander A; Geohegan, David B; Pannala, Sreekanth; Rouleau, Christopher

    2014-01-01

    Simple kinetic models of carbon nanotube growth have been able to successfully link together many experimental parameters involved in the growth of carbon nanotubes for practical applications including the prediction of growth rates, terminal lengths, number of walls, activation energies, and their dependences on the growth environment. The implications of recent experiments utilizing in situ monitoring of carbon nanotube growth on our past kinetic model are first reviewed. Then, sub-second pulsed feedstock gas introduction is discussed to explore the nucleation and initial growth of carbon nanotubes in the context of the kinetic model. Moreover, kinetic effects in "pulsed CVD" - using repeated pulsed gas introduction to stop and restart nanotube growth - are explored to understand renucleation, the origin of alignment in nanotube arrays, and incremental growth. Time-resolved reflectivity of the surface is used to remotely understand the kinetics of nucleation and the coordinated growth of arrays. This approach demonstrates that continuous vertically aligned single wall carbon nanotubes can be grown incrementally by pulsed CVD, and that the first exposure of fresh catalyst to feedstock gas is critical to nanotubes site density required for coordinated growth. Aligned nanotube arrays (as short as 60 nm) are shown to nucleate and grow within single, sub-second gas pulses. The multiple-pulse growth experiments (> 100 pulses) show that a high fraction of nanotubes renucleate on subsequent gas pulses.

  15. Templated Growth of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Siochik Emilie J. (Inventor)

    2007-01-01

    A method of growing carbon nanotubes uses a synthesized mesoporous si lica template with approximately cylindrical pores being formed there in. The surfaces of the pores are coated with a carbon nanotube precu rsor, and the template with the surfaces of the pores so-coated is th en heated until the carbon nanotube precursor in each pore is convert ed to a carbon nanotube.

  16. Carbon nanotube array based sensor

    DOEpatents

    Lee, Christopher L.; Noy, Aleksandr; Swierkowski, Stephan P.; Fisher, Karl A.; Woods, Bruce W.

    2005-09-20

    A sensor system comprising a first electrode with an array of carbon nanotubes and a second electrode. The first electrode with an array of carbon nanotubes and the second electrode are positioned to produce an air gap between the first electrode with an array of carbon nanotubes and the second electrode. A measuring device is provided for sensing changes in electrical capacitance between the first electrode with an array of carbon nanotubes and the second electrode.

  17. Lipid nanotube or nanowire sensor

    DOEpatents

    Noy, Aleksandr; Bakajin, Olgica; Letant, Sonia; Stadermann, Michael; Artyukhin, Alexander B.

    2010-06-29

    A sensor apparatus comprising a nanotube or nanowire, a lipid bilayer around the nanotube or nanowire, and a sensing element connected to the lipid bilayer. Also a biosensor apparatus comprising a gate electrode; a source electrode; a drain electrode; a nanotube or nanowire operatively connected to the gate electrode, the source electrode, and the drain electrode; a lipid bilayer around the nanotube or nanowire, and a sensing element connected to the lipid bilayer.

  18. Lipid nanotube or nanowire sensor

    DOEpatents

    Noy, Aleksandr; Bakajin, Olgica; Letant, Sonia; Stadermann, Michael; Artyukhin, Alexander B.

    2009-06-09

    A sensor apparatus comprising a nanotube or nanowire, a lipid bilayer around the nanotube or nanowire, and a sensing element connected to the lipid bilayer. Also a biosensor apparatus comprising a gate electrode; a source electrode; a drain electrode; a nanotube or nanowire operatively connected to the gate electrode, the source electrode, and the drain electrode; a lipid bilayer around the nanotube or nanowire, and a sensing element connected to the lipid bilayer.

  19. Transport Through Carbon Nanotube Wires

    NASA Technical Reports Server (NTRS)

    Anantram, M. P.; Kwak, Dochan (Technical Monitor)

    2001-01-01

    This viewgraph presentation deals with the use of carbon nanotubes as a transport system. Contact, defects, tubular bend, phonons, and mechanical deformations all contribute to reflection within the nanotube wire. Bragg reflection, however, is native to an ideal energy transport system. Transmission resistance depends primarily on the level of energy present. Finally, the details regarding coupling between carbon nanotubes and simple metals are presented.

  20. Weaving Nanotechnology Dreams with Nanotubes

    SciTech Connect

    Tomanek, David

    2003-01-15

    The continuous reduction of device sizes, which is rapidly approaching the atomic level, calls for new approaches to design and test future building blocks of nanotechnology. Computers will become the most powerful tools to interpret what happens on the nanometer scale, where as I will illustrate, structures of carbon may become stronger than steel, yet turn into quantum conductors or even efficient heat conductors. In nanostructures that form during a hierarchical self-assembly process, even defects may play a different, often helpful role. An efficient self-healing process may convert less stable atomic assemblies into other, more perfect structures, thus answering an important concern in molecular electronics. Defects may even be used in nano-scale engineering to form complex systems such as carbon foam or nanotube peapods. I will show how some of these challenging problems can be most efficiently addressed in simulations on recently available massively parallel supercomputers.

  1. Doping of single-walled carbon nanotubes controlled via chemical transformation of encapsulated nickelocene.

    PubMed

    Kharlamova, Marianna V; Sauer, Markus; Saito, Takeshi; Sato, Yuta; Suenaga, Kazu; Pichler, Thomas; Shiozawa, Hidetsugu

    2015-01-28

    Controlled doping of carbon nanotubes is elemental for their electronic applications. Here we report an approach to tune the polarity and degree of doping of single-walled carbon nanotubes via filling with nickelocene followed by encapsulated reactions. Using Raman, photoemission spectroscopy and transmission electron microscopy, we show that nickelocene molecules transform into nickel carbides, nickel and inner carbon nanotubes with reaction temperatures as low as 250 °C. The doping efficiency is determined for each chemical component. Synchronous charge transfer among the molecular components allows bipolar doping of the carbon nanotubes to be achieved in a broad range of ±0.0012 e(-) per carbon. PMID:25503929

  2. Near-ideal strength in metal nanotubes revealed by atomistic simulations

    SciTech Connect

    Sun, Mingfei; Xiao, Fei; Deng, Chuang

    2013-12-02

    Here we report extraordinary mechanical properties revealed by atomistic simulations in metal nanotubes with hollow interior that have been long overlooked. Particularly, the yield strength in [1 1 1] Au nanotubes is found to be up to 60% higher than the corresponding solid Au nanowire, which approaches the theoretical ideal strength in Au. Furthermore, a remarkable transition from sharp to smooth yielding is observed in Au nanotubes with decreasing wall thickness. The ultrahigh tensile strength in [1 1 1] Au nanotube might originate from the repulsive image force exerted by the interior surface against dislocation nucleation from the outer surface.

  3. Theoretical calculation of magneto-optical properties in cobalt nanotube array with hexagonal symmetry

    NASA Astrophysics Data System (ADS)

    Zhang, Shaoyin; Tang, Shaolong; Gao, Jinlong; Luo, Xiaojing; Xia, Wenbin; Du, Youwei

    2013-09-01

    The extended Fourier components and effective electric dipole model allowing for the proper treatment of magneto-optical (MO) activity are presented. The scattering-matrix approach is employed to analyze the MO properties of hexagonal array of magnetic metallic nanotubes embedded in a dielectric medium in the presence of magnetic field. It is found the MO properties of the nanotube array are more prominent than those of the nanodisk array for the same value of the cobalt filling ratio in specific wavelength range. The spectral position of the Kerr maxima can be tuned by the nanotube's length, wall thickness, separation of the neighboring nanotubes and the filling medium.

  4. Practical considerations for the demonstration of a single walled carbon nanotube actuator

    NASA Astrophysics Data System (ADS)

    Minett, A. I.; Fraysse, J.; Gu, G.; Roth, S.

    2001-11-01

    The conversion of electrical energy into mechanical energy using macro scale sheets of carbon nanotubes (bucky paper) has been shown to exhibit comparable or superior performance to that of human skeletal muscle. This level of performance was not as high as predicted by theoretical calculations. Therefore, working from a bottom-up principle, it is of paramount interest to not only demonstrate a single carbon nanotube actuator, but to gain a better understanding of the process of nanotube actuation. In this paper, practical considerations and approaches to the preparation of suspended single walled carbon nanotube (SWNT) structures and the measurement of actuation force are discussed.

  5. Magnetism in zigzag and armchair CuO nanotubes: Ab-initio study

    NASA Astrophysics Data System (ADS)

    Paudel, Samir; Dandeliya, Sushmita; Chaurasiya, Rajneesh; Srivastava, Anurag; Kaphle, Gopi Chandra

    2016-05-01

    The structural stability, electronic band structure and magnetic properties of zigzag (4≤n≤12) and armchair (3≤n≤8) copper oxide nanotubes have been analyzed by employing a standard Density Functional Theory based ab-intio approach using spin polarized generalized gradient approximation with revised Perdew Burke Ernzerhoff type parameterization. The binding energy of both zigzag as well as armchair CuO nanotubes increases with increasing diameter. Whereas, calculated total magnetic moment decreases with increasing diameter. Among the considered chiralities, (5, 5) armchair (diameter 9.08 Å) and (9, 0) zigzag (diameter 9.47 Å) CuO nanotubes show highest degree of spin polarization, however total magnetic moment is found to be highest for (4, 0) zigzag and (3, 3) armchair CuO nanotubes. The computed electronic properties of considered CuO Nanotube, confirms the metallic nature of these nanotubes.

  6. Comparative study on different carbon nanotube materials in terms of transparent conductive coatings.

    PubMed

    Li, Zhongrui; Kandel, Hom R; Dervishi, Enkeleda; Saini, Viney; Xu, Yang; Biris, Alexandru R; Lupu, Dan; Salamo, Gregory J; Biris, Alexandru S

    2008-03-18

    We compared conductive transparent carbon nanotube coatings on glass substrates made of differently produced single-wall (SWNT), double-wall, and multiwall carbon nanotubes. The airbrushing approach and the vacuum filtration method were utilized for the fabrication of carbon nanotube films. The optoelectronic performance of the carbon nanotube film was found to strongly depend on many effects including the ratio of metallic-to-semiconducting tubes, dispersion, length, diameter, chirality, wall number, structural defects, and the properties of substrates. The electronic transportability and optical properties of the SWNT network can be significantly altered by chemical doping with thionyl chloride. Hall effect measurements revealed that all of these thin carbon nanotube films are of p-type probably due to the acid reflux-based purification and atmospheric impurities. The competition between variable-range hoping and fluctuation-assisted tunneling in the functionized carbon nanotube system could lead to a crossover behavior in the temperature dependence of the network resistance. PMID:18251555

  7. Noncovalent functionalization of carbon nanotubes for highly specific electronic biosensors

    NASA Astrophysics Data System (ADS)

    Chen, Robert J.; Bangsaruntip, Sarunya; Drouvalakis, Katerina A.; Wong Shi Kam, Nadine; Shim, Moonsub; Li, Yiming; Kim, Woong; Utz, Paul J.; Dai, Hongjie

    2003-04-01

    Novel nanomaterials for bioassay applications represent a rapidly progressing field of nanotechnology and nanobiotechnology. Here, we present an exploration of single-walled carbon nanotubes as a platform for investigating surface-protein and protein-protein binding and developing highly specific electronic biomolecule detectors. Nonspecific binding on nanotubes, a phenomenon found with a wide range of proteins, is overcome by immobilization of polyethylene oxide chains. A general approach is then advanced to enable the selective recognition and binding of target proteins by conjugation of their specific receptors to polyethylene oxide-functionalized nanotubes. This scheme, combined with the sensitivity of nanotube electronic devices, enables highly specific electronic sensors for detecting clinically important biomolecules such as antibodies associated with human autoimmune diseases.

  8. Generalizing thermodynamic properties of bulk single-walled carbon nanotubes

    PubMed Central

    Rodriguez, Kenneth R.; Nanney, Warren A.; A. Maddux, Cassandra J.; Martínez, Hernán L.

    2014-01-01

    The enthalpy and Gibbs free energy thermodynamical potentials of single walled carbon nanotubes were studied of all types (armchairs, zig-zags, chirals (n>m), and chiral (napproach. Those values were used to study the relationship between the thermodynamic potentials and the diameter of the nanotube. Results of this study led to the proposal of a single equation for the thermodynamical potential of ΔHAB298 K or ΔGAB298 K (assembly of nanotubes from atoms) versus the chiral vector indexes n and m for any given nanotube. The equations show a good level of accuracy in predicting thermodynamic potentials for practical applications. PMID:25874156

  9. Generalizing thermodynamic properties of bulk single-walled carbon nanotubes

    SciTech Connect

    Rodriguez, Kenneth R. Nanney, Warren A.; Maddux, Cassandra J.A.; Martínez, Hernán L.; Malone, Marvin A.; Coe, James V.

    2014-12-15

    The enthalpy and Gibbs free energy thermodynamical potentials of single walled carbon nanotubes were studied of all types (armchairs, zig-zags, chirals (n>m), and chiral (napproach. Those values were used to study the relationship between the thermodynamic potentials and the diameter of the nanotube. Results of this study led to the proposal of a single equation for the thermodynamical potential of ΔH{sub AB}{sup 298 K} or ΔG{sub AB}{sup 298 K} (assembly of nanotubes from atoms) versus the chiral vector indexes n and m for any given nanotube. The equations show a good level of accuracy in predicting thermodynamic potentials for practical applications.

  10. Generalizing thermodynamic properties of bulk single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Rodriguez, Kenneth R.; Malone, Marvin A.; Nanney, Warren A.; A. Maddux, Cassandra J.; Coe, James V.; Martínez, Hernán L.

    2014-12-01

    The enthalpy and Gibbs free energy thermodynamical potentials of single walled carbon nanotubes were studied of all types (armchairs, zig-zags, chirals (n>m), and chiral (napproach. Those values were used to study the relationship between the thermodynamic potentials and the diameter of the nanotube. Results of this study led to the proposal of a single equation for the thermodynamical potential of Δ HAB 298 K or Δ GAB 298 K (assembly of nanotubes from atoms) versus the chiral vector indexes n and m for any given nanotube. The equations show a good level of accuracy in predicting thermodynamic potentials for practical applications.

  11. Facile synthesis of boron nitride nanotubes and improved electrical conductivity.

    PubMed

    Chen, Yongjun; Luo, Lijie; Zhou, Longchang; Mo, Libin; Tong, Zhangfa

    2010-02-01

    A layer of catalyst film on substrate is usually required during the vapor-liquid-solid (VLS) growth of one-dimensional (1D) nanomaterials. In this work, however, a novel approach for synthesizing high-purity bamboo-like boron nitride (BN) nanotubes directly on commercial stainless steel foils was demonstrated. Synthesis was realized by heating boron and zinc oxide (ZnO) powders at 1200 degrees C under a mixture gas flow of nitrogen and hydrogen. The stainless steel foils played an additional role of catalyst besides the substrate during the VLS growth of the nanotubes. In addition, the electrical conductivity of the BN nanotubes was efficiently improved in a simple way by coating with Au and Pd nanoparticles. The decorated BN nanotubes may find potential applications in catalysts, sensors and nanoelectronics. PMID:20352730

  12. An application of carbon nanotubes for integrated circuit interconnects

    NASA Astrophysics Data System (ADS)

    Coiffic, J. C.; Foa Torres, L. E.; Le Poche, H.; Fayolle, M.; Roche, S.; Maitrejean, S.; Roualdes, S.; Ayral, A.

    2008-08-01

    Integrated circuits fabrication is soon reaching strong limitations. Help could come from using carbon nanotubes as conducting wires for interconnects. Although this solution was proposed six years ago, researchers still come up with many obstacles such as localization, low temperature growth on copper, contacting and reproducibility. The integration processes exposed here intend to meet the industrial requirements. Two approaches are then possibly followed. Either using densely packed single wall (SWCNT) (or very tiny multiwall) nanotubes, or filling up the whole interconnect diameter with a single large multiwall (MWCNT) nanotube. In this work, we focus on the integration of multiwall vertical interconnects. Densely packed MWCNTs are grown in via holes by CVD. Alternatively, we have developed a method to obtain a single large nanofibre grown by PECVD (MWCNF) in each via hole. Electrical measurements are performed on CVD and PECVD grown carbon nanotubes. The role of electron-phonon interaction in these devices is also briefly discussed.

  13. Reinforcement of Epoxies Using Single Walled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Krishnamoorti, Ramanan; Sharma, Jitendra; Chatterjee, Tirtha

    2008-03-01

    The reinforcement of bisphenol-A and bisphenol-F epoxies using single walled carbon nanotubes has been approached experimentally by understanding the nature of interactions between the matrices and nanotubes. Unassisted dispersions of single walled carbon nanotubes in epoxies were studied by a combination of radiation scattering (elastic small angle scattering and inelastic scattering), DSC based glass transition determination, melt rheology and solid-state mechanical testing in order to understand and correlate changes in local and global dynamics to the tailoring of composite mechanical properties. Significant changes in the glass transition temperature of the matrix can successfully account for changes in the viscoelastic properties of the epoxy dispersions for concentrations below the percolation threshold, while above the percolation threshold the network superstructure formed by the nanotubes controls the viscoelastic properties.

  14. Synthesis of carbon nanotubes and nanotube forests on copper catalyst

    NASA Astrophysics Data System (ADS)

    Kruszka, Bartosz; Terzyk, Artur P.; Wiśniewski, Marek; Gauden, Piotr A.; Szybowicz, Mirosław

    2014-09-01

    The growth of carbon nanotubes on bulk copper is studied. We show for the first time, that super growth chemical vapor deposition method can be successfully applied for preparation of nanotubes on copper catalyst, and the presence of hydrogen is necessary. Next, different methods of copper surface activation are studied, to improve catalyst efficiency. Among them, applied for the first time for copper catalyst in nanotubes synthesis, sulfuric acid activation is the most promising. Among tested samples the surface modified for 10 min is the most active, causing the growth of vertically aligned carbon nanotube forests. Obtained results have potential importance in application of nanotubes and copper in electronic chips and nanodevices.

  15. Pathogen identification using peptide nanotube biosensors and impedance AFM

    NASA Astrophysics Data System (ADS)

    Maccuspie, Robert I.

    Pathogen identification at highly sensitive levels is crucial to meet urgent needs in fighting the spread of disease or detecting bioterrorism events. Toward that end, a new method for biosensing utilizing fluorescent antibody nanotubes is proposed. Fundamental studies on the self-assembly of these peptide nanotubes are performed, as are applications of aligning these nanotubes on surfaces. As biosensors, these nanotubes incorporate recognition units with antibodies at their ends and fluorescent signaling units at their sidewalls. When viral pathogens were mixed with these antibody nanotubes in solution, the nanotubes rapidly aggregated around the viruses. The size of the aggregates increased as the concentration of viruses increased, as detected by flow cytometry on the order of attomolar concentrations by changes in fluorescence and light scattering intensities. This enabled determination of the concentrations of viruses at trace levels (102 to 106 pfu/mL) within 30 minutes from the receipt of samples to the final quantitative data analysis, as demonstrated on Adenovirus, Herpes Simplex Virus, Influenza, and Vaccinia virus. As another separate approach, impedance AFM is used to study the electrical properties of individual viruses and nanoparticles used as model systems. The design, development, and implementation of the impedance AFM for an Asylum Research platform is described, as well as its application towards studying the impedance of individual nanoparticles as a model system for understanding the fundamental science of how the life cycle of a virus affects its electrical properties. In combination, these approaches fill a pressing need to quantify viruses both rapidly and sensitively.

  16. Functionalization of vertically aligned carbon nanotubes

    PubMed Central

    Snyders, Rony; Colomer, Jean-François

    2013-01-01

    Summary This review focuses and summarizes recent studies on the functionalization of carbon nanotubes oriented perpendicularly to their substrate, so-called vertically aligned carbon nanotubes (VA-CNTs). The intrinsic properties of individual nanotubes make the VA-CNTs ideal candidates for integration in a wide range of devices, and many potential applications have been envisaged. These applications can benefit from the unidirectional alignment of the nanotubes, the large surface area, the high carbon purity, the outstanding electrical conductivity, and the uniformly long length. However, practical uses of VA-CNTs are limited by their surface characteristics, which must be often modified in order to meet the specificity of each particular application. The proposed approaches are based on the chemical modifications of the surface by functionalization (grafting of functional chemical groups, decoration with metal particles or wrapping of polymers) to bring new properties or to improve the interactions between the VA-CNTs and their environment while maintaining the alignment of CNTs. PMID:23504581

  17. Hyperspectral Microscopy of Near-Infrared Fluorescence Enables 17-Chirality Carbon Nanotube Imaging.

    PubMed

    Roxbury, Daniel; Jena, Prakrit V; Williams, Ryan M; Enyedi, Balázs; Niethammer, Philipp; Marcet, Stéphane; Verhaegen, Marc; Blais-Ouellette, Sébastien; Heller, Daniel A

    2015-01-01

    The intrinsic near-infrared photoluminescence (fluorescence) of single-walled carbon nanotubes exhibits unique photostability, narrow bandwidth, penetration through biological media, environmental sensitivity, and both chromatic variety and range. Biomedical applications exploiting this large family of fluorophores will require the spectral and spatial resolution of individual (n,m) nanotube species' fluorescence and its modulation within live cells and tissues, which is not possible with current microscopy methods. We present a wide-field hyperspectral approach to spatially delineate and spectroscopically measure single nanotube fluorescence in living systems. This approach resolved up to 17 distinct (n,m) species (chiralities) with single nanotube spatial resolution in live mammalian cells, murine tissues ex vivo, and zebrafish endothelium in vivo. We anticipate that this approach will facilitate multiplexed nanotube imaging in biomedical applications while enabling deep-tissue optical penetration, and single-molecule resolution in vivo. PMID:26387482

  18. Hyperspectral Microscopy of Near-Infrared Fluorescence Enables 17-Chirality Carbon Nanotube Imaging

    PubMed Central

    Roxbury, Daniel; Jena, Prakrit V.; Williams, Ryan M.; Enyedi, Balázs; Niethammer, Philipp; Marcet, Stéphane; Verhaegen, Marc; Blais-Ouellette, Sébastien; Heller, Daniel A.

    2015-01-01

    The intrinsic near-infrared photoluminescence (fluorescence) of single-walled carbon nanotubes exhibits unique photostability, narrow bandwidth, penetration through biological media, environmental sensitivity, and both chromatic variety and range. Biomedical applications exploiting this large family of fluorophores will require the spectral and spatial resolution of individual (n,m) nanotube species’ fluorescence and its modulation within live cells and tissues, which is not possible with current microscopy methods. We present a wide-field hyperspectral approach to spatially delineate and spectroscopically measure single nanotube fluorescence in living systems. This approach resolved up to 17 distinct (n,m) species (chiralities) with single nanotube spatial resolution in live mammalian cells, murine tissues ex vivo, and zebrafish endothelium in vivo. We anticipate that this approach will facilitate multiplexed nanotube imaging in biomedical applications while enabling deep-tissue optical penetration, and single-molecule resolution in vivo. PMID:26387482

  19. Carbon nanotubes on a substrate

    DOEpatents

    Gao, Yufei [Kennewick, WA; Liu, Jun [West Richland, WA

    2002-03-26

    The present invention includes carbon nanotubes whose hollow cores are 100% filled with conductive filler. The carbon nanotubes are in uniform arrays on a conductive substrate and are well-aligned and can be densely packed. The uniformity of the carbon nanotube arrays is indicated by the uniform length and diameter of the carbon nanotubes, both which vary from nanotube to nanotube on a given array by no more than about 5%. The alignment of the carbon nanotubes is indicated by the perpendicular growth of the nanotubes from the substrates which is achieved in part by the simultaneous growth of the conductive filler within the hollow core of the nanotube and the densely packed growth of the nanotubes. The present invention provides a densely packed carbon nanotube growth where each nanotube is in contact with at least one nearest-neighbor nanotube. The substrate is a conductive substrate coated with a growth catalyst, and the conductive filler can be single crystals of carbide formed by a solid state reaction between the substrate material and the growth catalyst. The present invention further provides a method for making the filled carbon nanotubes on the conductive substrates. The method includes the steps of depositing a growth catalyst onto the conductive substrate as a prepared substrate, creating a vacuum within a vessel which contains the prepared substrate, flowing H2/inert (e.g. Ar) gas within the vessel to increase and maintain the pressure within the vessel, increasing the temperature of the prepared substrate, and changing the H2/Ar gas to ethylene gas such that the ethylene gas flows within the vessel. Additionally, varying the density and separation of the catalyst particles on the conductive substrate can be used to control the diameter of the nanotubes.

  20. Specific features of low-frequency vibrational dynamics and low-temperature heat capacity of double-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Avramenko, M. V.; Roshal, S. B.

    2016-05-01

    A continuous model has been constructed for low-frequency dynamics of a double-walled carbon nanotube. The formation of the low-frequency part of the phonon spectrum of a double-walled nanotube from phonon spectra of its constituent single-walled nanotubes has been considered in the framework of the proposed approach. The influence of the environment on the phonon spectrum of a single double-walled carbon nanotube has been analyzed. A combined method has been proposed for estimating the coefficients of the van der Waals interaction between the walls of the nanotube from the spectroscopic data and the known values of the elastic moduli of graphite. The low-temperature specific heat has been calculated for doublewalled carbon nanotubes, which in the field of applicability of the model ( T < 35 K) is substantially less than the sum of specific heats of two individual single-walled nanotubes forming it.

  1. Carbon Nanotubes Based Quantum Devices

    NASA Technical Reports Server (NTRS)

    Lu, Jian-Ping

    1999-01-01

    This document represents the final report for the NASA cooperative agreement which studied the application of carbon nanotubes. The accomplishments are reviewed: (1) Wrote a review article on carbon nanotubes and its potentials for applications in nanoscale quantum devices. (2) Extensive studies on the effects of structure deformation on nanotube electronic structure and energy band gaps. (3) Calculated the vibrational spectrum of nanotube rope and the effect of pressure. and (4) Investigate the properties of Li intercalated nanotube ropes and explore their potential for energy storage materials and battery applications. These studies have lead to four publications and seven abstracts in international conferences.

  2. Controlled carbon nanotube synthesis for quantification of polymer-nanotube composite micromechanics

    NASA Astrophysics Data System (ADS)

    Bult, Justin Bernard

    Conventional experimental approaches to the understanding of nanotube-polymer micro-mechanics have struggled to produce reproducible data due to the inherent difficulty in physically manipulating the nanotube in-situ. To avoid the problems scale represents in nanotube-polymer composites a novel approach of using Polarized Raman spectroscopy was developed. The Raman spectroscopic technique has the advantage of using non-invasive analysis to compute the composite micro mechanical properties of interfacial shear stress and critical length. Composites with nanotubes of defined length were needed in order to use the Raman technique. To satisfy this requirement a new thermal Chemical Vapor Deposition (CVD) tool capable of reproducibly growing aligned length uniformity with large mass yield was designed and built. The course of developing these furnace capabilities led to the investigation of nanotube growth mechanics. It is shown herein that a stable passivation barrier is required for nanotube growth. Using X-Ray Photoelectron Spectroscopy (XPS) depth profiling of metal substrate growth conclusively shows the presence of a stable catalyst layer on the outer surface of stable oxides of greater than 100 nm. By analyzing the diffusion profile represented in the XPS data it is shown that a critical thickness for the passivation oxide can be calculated as a function of time and temperature. For the growth parameters used in this study the critical thickness was found to be between 10 nm and 30 nm depending on the diffusivity value used for iron in chromia. This value agrees well with experimental observation. Uniformly grown carbon nanotubes with lengths of 4, 14, 17, 22, 43, 74, and 116 mum were incorporated into a polycarbonate matrix polymer via solvent-antisolvent processing. The nanotube composites of varied length were tested in tensile strain while Raman spectra were taken concurrently to deduce the load transfer to the nanotube due to composite strain. It is found

  3. Copper-philic carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Belgamwar, Sachin U.; Sharma, Niti Nipun

    2016-04-01

    Carbon nanotube is having poor wet-ability with copper metal. Wet-ability of carbon nanotube was improved by exposing and creating more active sites on the surface of carbon nanotube. Carbon nanotubes were subjected to the prolong ultrasonication treatment of 20×103 Hz and 500W, which helped in disentanglement of carbon nanotube agglomerates and in breaking the weak bonds like pentagonal or heptagonal structure on the surface and on the CNT cap. Disentanglement of the carbon nanotube, resulted in exposing the defective sites on the surface and breaking of weak bonds, which assisted in creating the new defects on the surface. This process results in generates more active sites on the surface and it helps in improving the wet-ability of the carbon nanotube in copper.

  4. Transport in Carbon Nanotube Junctions

    NASA Astrophysics Data System (ADS)

    Khoo, K. H.; Chelikowsky, James R.

    2008-03-01

    There is growing interest in the use of carbon nanotube thin films as transparent electrical conductors and thin-film transistors owing to their high optical transmittance, low sheet resistivity, and ease of fabrication. [1,2] A major contribution to the sheet resistivity originates at nanotube junctions, as electrical contact is typically poor between adjacent nanotubes. It is thus important to characterize carbon nanotube junctions in order to understand the conduction properties of nanotube thin films. To this end, we have performed ab initio density functional theory calculations to investigate the structural, electronic and transport properties of carbon nanotube junctions as a function of nanotube chirality and contact geometry [1] Z. Wu et al., Science 305, 1273 (2004) [2] E. S. Snow, J. P. Novak, P. M. Campbell, and D. Park, Appl. Phys. Lett. 82, 2145 (2003).

  5. Nanotechnology with Carbon Nanotubes: Mechanics, Chemistry, and Electronics

    NASA Technical Reports Server (NTRS)

    Srivastava, Deepak

    2003-01-01

    This viewgraph presentation reviews the Nanotechnology of carbon nanotubes. The contents include: 1) Nanomechanics examples; 2) Experimental validation of nanotubes in composites; 3) Anisotropic plastic collapse; 4) Spatio-temporal scales, yielding single-wall nanotubes; 5) Side-wall functionalization of nanotubes; 6) multi-wall Y junction carbon nanotubes; 7) Molecular electronics with Nanotube junctions; 8) Single-wall carbon nanotube junctions; welding; 9) biomimetic dendritic neurons: Carbon nanotube, nanotube electronics (basics), and nanotube junctions for Devices,

  6. Carbon Nanotubes for Supercapacitor

    PubMed Central

    2010-01-01

    As an electrical energy storage device, supercapacitor finds attractive applications in consumer electronic products and alternative power source due to its higher energy density, fast discharge/charge time, low level of heating, safety, long-term operation stability, and no disposable parts. This work reviews the recent development of supercapacitor based on carbon nanotubes (CNTs) and their composites. The purpose is to give a comprehensive understanding of the advantages and disadvantages of carbon nanotubes-related supercapacitor materials and to find ways for the improvement in the performance of supercapacitor. We first discussed the effects of physical and chemical properties of pure carbon nanotubes, including size, purity, defect, shape, functionalization, and annealing, on the supercapacitance. The composites, including CNTs/oxide and CNTs/polymer, were further discussed to enhance the supercapacitance and keep the stability of the supercapacitor by optimally engineering the composition, particle size, and coverage. PMID:20672061

  7. Conductance of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Datta, Supriyo; Anatram, M. P.

    1998-01-01

    The recent report of quantized conductance in a 4 m long multiwalled nanotube (MWNT) raises the exciting possibility of ballistic transport at room temperature over relatively long distances. We argue that this is made possible by the special symmetry of the eigenstates of the lowest propagating modes in metallic nanotubes which suppresses backscattering. This unusual effect is absent for the higher propagating modes so that transport is not ballistic once the bias exceeds the cut-off energy for the higher modes, which is estimated to be approximately 75 meV for nanotubes of diameter approximately 15 nm. Also, we show that the symmetry of the eigenstates can significantly affect their coupling to the reservoir and hence the contact resistance. A simple model is presented that can be used to understand the observed conductance-voltage characteristics.

  8. Single crystalline magnetite nanotubes.

    PubMed

    Liu, Zuqin; Zhang, Daihua; Han, Song; Li, Chao; Lei, Bo; Lu, Weigang; Fang, Jiye; Zhou, Chongwu

    2005-01-12

    We descried a method to synthesize single crystalline Fe3O4 nanotubes by wet-etching the MgO inner cores of MgO/Fe3O4 core-shell nanowires. Homogeneous Fe3O4 nanotubes with controllable length, diameter, and wall thickness have been obtained. Resistivity of the Fe3O4 nanotubes was estimated to be approximately 4 x 10-2 Omega cm at room temperature. Magnetoresistance of approximately 1% was observed at T = 77 K when a magnetic field of B = 0.7 T was applied. The synthetic strategy presented here may be extended to a variety of materials such as YBCO, PZT, and LCMO which should provide ideal candidates for fundamental studies of superconductivity, piezoelectricity, and ferromagnetism in nanoscale structures. PMID:15631421

  9. Non-equilibrium Dynamics of DNA Nanotubes

    NASA Astrophysics Data System (ADS)

    Hariadi, Rizal Fajar

    nanotubes with an irreversible energy consumption reaction, analogous to nucleotide hydrolysis in actin and microtubule polymerization. Finally, we integrated the DNA strand displacement circuits with DNA nanotube polymerization to achieve programmable kinetic control of behavior within artificial cytoskeleton. Our synthetic approach may provide insights into natural cytoskeleton dynamics, such as minimal architectural or reaction mechanism requirements for non-equilibrium behaviors including treadmilling and dynamic instability. The outgrowth of DNA nanotechnology beyond its own boundaries, serving as a general model system for biomolecular dynamics, can lead to an understanding of molecular processes that advances both basic and applied sciences.

  10. Facile Preparation of Octadecyl Monoliths with Incorporated Carbon Nanotubes and Neutral Monoliths with Coated Carbon Nanotubes Stationary Phases for HPLC of Small and Large Molecules by Hydrophobic and π-π Interactions

    PubMed Central

    Mayadunne, Erandi; Rassi, Ziad El

    2014-01-01

    Two approaches for incorporating carbon nanotubes into monolithic columns for HPLC are described in this report. They pertain to the investigation of carbon nanotubes either (i) as entities to modulate solute retention on monolithic columns bearing well defined retentive ligands or (ii) as entities that constitute the stationary phase responsible for solute retention and separation. Approach (i) involved the incorporation of carbon nanotubes into octadecyl monolithic columns while approach (ii) concerns the preparation and evaluation of an ideal monolithic support and coating it with carbon nanotubes to yield a real “carbon nanotube stationary phase” for the HPLC separation of a wide range of solutes. First, an octadecyl monolithic column based on the in situ polymerization of octadecyl acrylate and trimethylolpropane trimethacrylate was optimized for use in HPLC separations of small and large solutes (e.g., proteins). To further modulate the retention and separation of proteins, small amounts of carbon nanotubes were incorporated into the octadecyl monolith column. In approach (ii), an inert, relatively polar monolith based on the in situ polymerization of glyceryl monomethacrylate (GMM) and ethylene glycol dimethacrylate (EDMA) proved to be the most suitable support for the preparation of “carbon nanotube stationary phase”. This carbon nanotube “coated” monolith proved useful in the HPLC separation of a wide range of small solutes including enantiomers. In approach (ii), a more homogeneous incorporation of carbon nanotubes into the diol monolithic columns (i.e., GMM/EDMA) was achieved when hydroxyl functionalized carbon nanotubes were incorporated into the GMM/EDMA monolithic support. In addition, high power sonication for a short time enhanced further the homogeneity of the monolith incorporated with nanotubes. In all cases, nonpolar and π interactions were responsible for solute retention on the monolith incorporated carbon nanotubes. PMID:25127634

  11. Facile preparation of octadecyl monoliths with incorporated carbon nanotubes and neutral monoliths with coated carbon nanotubes stationary phases for HPLC of small and large molecules by hydrophobic and π-π interactions.

    PubMed

    Mayadunne, Erandi; El Rassi, Ziad

    2014-11-01

    Two approaches for incorporating carbon nanotubes into monolithic columns for HPLC are described in this report. They pertain to the investigation of carbon nanotubes either (i) as entities to modulate solute retention on monolithic columns bearing well defined retentive ligands or (ii) as entities that constitute the stationary phase responsible for solute retention and separation. Approach (i) involved the incorporation of carbon nanotubes into octadecyl monolithic columns while approach (ii) concerns the preparation and evaluation of an ideal monolithic support and coating it with carbon nanotubes to yield a real "carbon nanotube stationary phase" for the HPLC separation of a wide range of solutes. First, an octadecyl monolithic column based on the in situ polymerization of octadecyl acrylate and trimethylolpropane trimethacrylate was optimized for use in HPLC separations of small and large solutes (e.g., proteins). To further modulate the retention and separation of proteins, small amounts of carbon nanotubes were incorporated into the octadecyl monolith column. In approach (ii), an inert, relatively polar monolith based on the in situ polymerization of glyceryl monomethacrylate (GMM) and ethylene glycol dimethacrylate (EDMA) proved to be the most suitable support for the preparation of "carbon nanotube stationary phase". This carbon nanotube "coated" monolith proved useful in the HPLC separation of a wide range of small solutes including enantiomers. In approach (ii), a more homogeneous incorporation of carbon nanotubes into the diol monolithic columns (i.e., GMM/EDMA) was achieved when hydroxyl functionalized carbon nanotubes were incorporated into the GMM/EDMA monolithic support. In addition, high power sonication for a short time enhanced further the homogeneity of the monolith incorporated with nanotubes. In all cases, nonpolar and π interactions were responsible for solute retention on the monolith incorporated carbon nanotubes. PMID:25127634

  12. Indium telluride nanotubes: Solvothermal synthesis, growth mechanism, and properties

    SciTech Connect

    Zhou, Liyan; Yan, Shancheng; Lu, Tao; Shi, Yi; Wang, Jianyu; Yang, Fan

    2014-03-15

    A convenient solvothermal approach was applied for the first time to synthesize In{sub 2}Te{sub 3} nanotubes. The morphology of the resultant nanotubes was studied by scanning electron microscopy and transmission electron microscopy. Nanotubes with a relatively uniform diameter of around 500 nm, tube wall thickness of 50–100 nm, and average length of tens of microns were obtained. X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy were used to study the crystal structures, composition, and optical properties of the products. To understand the growth mechanism of the In{sub 2}Te{sub 3} nanotubes, we studied the influences of temperature, reaction time, and polyvinylpyrrolidone (PVP) and ethylene diamine (EDA) dosages on the final products. Based on the experimental results, a possible growth mechanism of In{sub 2}Te{sub 3} nanotubes was proposed. In this mechanism, TeO{sub 3}{sup −2} is first reduced to allow nucleation. Circumferential edges of these nucleated molecules attract further deposition, and nanotubes finally grow rapidly along the c-axis and relatively slowly along the circumferential direction. The surface area of the products was determined by BET and found to be 137.85 m{sup 2} g{sup −1}. This large surface area indicates that the nanotubes may be suitable for gas sensing and hydrogen storage applications. The nanotubes also showed broad light detection ranging from 300 nm to 1100 nm, which covers the UV–visible–NIR regions. Such excellent optical properties indicate that In{sub 2}Te{sub 3} nanotubes may enable significant advancements in new photodetection and photosensing applications. -- Graphical abstract: A convenient solvothermal approach was applied to synthesize In{sub 2}Te{sub 3} nanotubes, which has not been reported in the literature for our knowledge. Surface area of this material is 137.85 m{sup 2} g{sup −1} from the BET testing, and such a high value makes it probably suitable for gas sensing and

  13. Homochiral metal phosphonate nanotubes.

    PubMed

    Liu, Xun-Gao; Bao, Song-Song; Huang, Jian; Otsubo, Kazuya; Feng, Jian-Shen; Ren, Min; Hu, Feng-Chun; Sun, Zhihu; Zheng, Li-Min; Wei, Shiqiang; Kitagawa, Hiroshi

    2015-10-21

    A new type of homochiral metal-organic nanotubular structures based on metal phosphonates are reported, namely, (R)- or (S)-[M(pemp)(H2O)2][M = Co(II) (1), Ni(II) (2)] [pemp(2-) = (R)- or (S)-(1-phenylethylamino)methylphosphonate]. In these compounds, the tube-walls are purely inorganic, composed of metal ions and O-P-O bridges. The cavity of the nanotube is hydrophilic with one coordination water pointing towards the center, while the outer periphery of the nanotube is hydrophobic, decorated by the phenylethyl groups of pemp(2-). The thermal stabilities, adsorption and proton conductivity properties are investigated. PMID:26324662

  14. Applications of Quantum Chemistry to the Study of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Jaffe, Richard L.

    2005-01-01

    For several years, scientists at NASA Ames have been studying the properties of carbon nanotubes using various experimental and computational methods. In this talk, I will compare different strategies for using quantum chemistry calculations to describe the electronic structure, deformation and chemical functionalization of single wall carbon nanotubes (SWNT) and the physisorption of small molecules on nanotube surfaces. The SWNT can be treated as an infinite (periodic) or finite length carbon cylinder or as a polycyclic aromatic hydrocarbon (PAH) molecule with an imposed curvature maintained by external constraints (as if it were cut out of the SWNT surface). Calculations are carried out using DFT and MP2 methods and a variety of atomic orbital basis sets from minimal (STO-3G) to valence triple zeta. The optimal approach is based on the particular SWNT property of interest. Examples to be discussed include: nanotube fluorination and other functionalization reactions; coating of nanotubes by water vapor and low-molecular weight organic molecules; and the nature of the interface between SWNT and liquids such as water and amines. In many cases, the quantum chemistry calculations are used to parameterize or validate force fields for molecular dynamics simulations. The results of these calculations have helped explain experimental data and contributed to the design of novel materials and sensors based on carbon nanotubes. Some of this research is described in the following papers:

  15. Multiwalled Carbon Nanotubes at the Interface of Pickering Emulsions.

    PubMed

    Briggs, Nicholas M; Weston, Javen S; Li, Brian; Venkataramani, Deepika; Aichele, Clint P; Harwell, Jeffrey H; Crossley, Steven P

    2015-12-01

    Carbon nanotubes exhibit very unique properties in biphasic systems. Their interparticle attraction leads to reduced droplet coalescence rates and corresponding improvements in emulsion stability. Here we use covalent and noncovalent techniques to modify the hydrophilicity of multiwalled carbon nanotubes (MWCNTs) and study their resulting behavior at an oil-water interface. By using both paraffin wax/water and dodecane/water systems, the thickness of the layer of MWNTs at the interface and resulting emulsion stability are shown to vary significantly with the approach used to modify the MWNTs. Increased hydrophilicity of the MWNTs shifts the emulsions from water-in-oil to oil-in-water. The stability of the emulsion is found to correlate with the thickness of nanotubes populating the oil-water interface and relative strength of the carbon nanotube network. The addition of a surfactant decreases the thickness of nanotubes at the interface and enhances the overall interfacial area stabilized at the expense of increased droplet coalescence rates. To the best of our knowledge, this is the first time the interfacial thickness of modified carbon nanotubes has been quantified and correlated to emulsion stability. PMID:26549532

  16. Switching and Rectification in Carbon-Nanotube Junctions

    NASA Technical Reports Server (NTRS)

    Srivastava, Deepak; Andriotis, Antonis N.; Menon, Madhu; Chernozatonskii, Leonid

    2003-01-01

    Multi-terminal carbon-nanotube junctions are under investigation as candidate components of nanoscale electronic devices and circuits. Three-terminal "Y" junctions of carbon nanotubes (see Figure 1) have proven to be especially interesting because (1) it is now possible to synthesize them in high yield in a controlled manner and (2) results of preliminary experimental and theoretical studies suggest that such junctions could exhibit switching and rectification properties. Following the preliminary studies, current-versus-voltage characteristics of a number of different "Y" junctions of single-wall carbon nanotubes connected to metal wires were computed. Both semiconducting and metallic nanotubes of various chiralities were considered. Most of the junctions considered were symmetric. These computations involved modeling of the quantum electrical conductivity of the carbon nanotubes and junctions, taking account of such complicating factors as the topological defects (pentagons, heptagons, and octagons) present in the hexagonal molecular structures at the junctions, and the effects of the nanotube/wire interfaces. A major component of the computational approach was the use of an efficient Green s function embedding scheme. The results of these computations showed that symmetric junctions could be expected to support both rectification and switching. The results also showed that rectification and switching properties of a junction could be expected to depend strongly on its symmetry and, to a lesser degree, on the chirality of the nanotubes. In particular, it was found that a zigzag nanotube branching at a symmetric "Y" junction could exhibit either perfect rectification or partial rectification (asymmetric current-versus-voltage characteristic, as in the example of Figure 2). It was also found that an asymmetric "Y" junction would not exhibit rectification.

  17. Patterned growth of carbon nanotubes obtained by high density plasma chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Mousinho, A. P.; Mansano, R. D.

    2015-03-01

    Patterned growth of carbon nanotubes by chemical vapor deposition represents an assembly approach to place and orient nanotubes at a stage as early as when they are synthesized. In this work, the carbon nanotubes were obtained at room temperature by High Density Plasmas Chemical Vapor Deposition (HDPCVD) system. This CVD system uses a new concept of plasma generation, where a planar coil coupled to an RF system for plasma generation was used with an electrostatic shield for plasma densification. In this mode, high density plasmas are obtained. We also report the patterned growth of carbon nanotubes on full 4-in Si wafers, using pure methane plasmas and iron as precursor material (seed). Photolithography processes were used to pattern the regions on the silicon wafers. The carbon nanotubes were characterized by micro-Raman spectroscopy, the spectra showed very single-walled carbon nanotubes axial vibration modes around 1590 cm-1 and radial breathing modes (RBM) around 120-400 cm-1, confirming that high quality of the carbon nanotubes obtained in this work. The carbon nanotubes were analyzed by atomic force microscopy and scanning electron microscopy too. The results showed that is possible obtain high-aligned carbon nanotubes with patterned growth on a silicon wafer with high reproducibility and control.

  18. Non-covalent interactions between carbon nanotubes and conjugated polymers

    NASA Astrophysics Data System (ADS)

    Tuncel, Dönüs

    2011-09-01

    Carbon nanotubes (CNTs) are interest to many different disciplines including chemistry, physics, biology, material science and engineering because of their unique properties and potential applications in various areas spanning from optoelectronics to biotechnology. However, one of the drawbacks associated with these materials is their insolubility which limits their wide accessibility for many applications. Various approaches have been adopted to circumvent this problem including modification of carbon nanotube surfaces by non-covalent and covalent attachments of solubilizing groups. Covalent approach modification may alter the intrinsic properties of carbon nanotubes and, in turn make them undesirable for many applications. On the other hand, a non-covalent approach helps to improve the solubility of CNTs while preserving their intrinsic properties. Among many non-covalent modifiers of CNTs, conjugated polymers are receiving increasing attention and highly appealing because of a number of reasons. To this end, the aim of this feature article is to review the recent results on the conjugated polymer-based non-covalent functionalization of CNTs with an emphasis on the effect of conjugated polymers in the dispersibility/solubility, optical, thermal and mechanical properties of carbon nanotubes as well as their usage in the purification and isolation of a specific single-walled nanotube from the mixture of the various tubes.

  19. Modeling of carbon nanotubes and carbon nanotube-polymer composites

    NASA Astrophysics Data System (ADS)

    Pal, G.; Kumar, S.

    2016-01-01

    In order to meet stringent environmental, safety and performance requirements from respective regulatory bodies, various technology-based industries are promoting the use of advanced carbon nanotube (CNT) reinforced lightweight and high strength polymer nanocomposites (PNCs) as a substitute to conventional materials both in structural and non-structural applications. The superior mechanical properties of PNCs made up of CNTs or bundles of CNTs can be attributed to the interfacial interaction between the CNTs and matrix, CNT's morphologies and to their uniform dispersion in the matrix. In PNCs, CNTs physically bond with polymeric matrix at a level where the assumption of continuum level interactions is not applicable. Modeling and prediction of mechanical response and failure behavior of CNTs and their composites becomes a complex task and is dealt with the help of up-scale modeling strategies involving multiple spatial and temporal scales in hierarchical or concurrent manner. Firstly, the article offers an insight into various modeling techniques in studying the mechanical response of CNTs; namely, equivalent continuum approach, quasi-continuum approach and molecular dynamics (MD) simulation. In the subsequent steps, these approaches are combined with analytical and numerical micromechanics models in a multiscale framework to predict the average macroscopic response of PNCs. The review also discusses the implementation aspects of these computational approaches, their current status and associated challenges with a future outlook.

  20. The Toxicology of Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Donaldson, Ken; Poland, Craig; Duffin, Rodger; Bonner, James

    2012-06-01

    1. Carbon nanotube structure, synthesis and applications C. Singh and W. Song; 2. The aerodynamic behaviour and pulmonary deposition of carbon nanotubes A. Buckley, R. Smith and R Maynard; 3. Utilising the concept of the biologically effective dose to define the particle and fibre hazards of carbon nanotubes K. Donaldson, R. Duffin, F. Murphy and C. Poland; 4. CNT, biopersistence and the fibre paradigm D. Warheit and M. DeLorme; 5. Length-dependent retention of fibres in the pleural space C. Poland, F. Murphy and K. Donaldson; 6. Experimental carcinogenicity of carbon nanotubes in the context of other fibres K. Unfried; 7. Fate and effects of carbon nanotubes following inhalation J. Ryman-Rasmussen, M. Andersen and J. Bonner; 8. Responses to pulmonary exposure to carbon nanotubes V. Castranova and R. Mercer; 9. Genotoxicity of carbon nanotubes R. Schins, C. Albrecht, K. Gerloff and D. van Berlo; 10. Carbon nanotube-cellular interactions; macrophages, epithelial and mesothelial cells V. Stone, M. Boyles, A. Kermanizadeh, J. Varet and H. Johnston; 11. Systemic health effects of carbon nanotubes following inhalation J. McDonald; 12. Dosimetry and metrology of carbon nanotubes L. Tran, L. MacCalman and R. Aitken; Index.

  1. Carbon nanotube intramolecular junctions

    NASA Astrophysics Data System (ADS)

    Yao, Zhen; Postma, Henk W. Ch.; Balents, Leon; Dekker, Cees

    1999-11-01

    The ultimate device miniaturization would be to use individual molecules as functional devices. Single-wall carbon nanotubes (SWNTs) are promising candidates for achieving this: depending on their diameter and chirality, they are either one-dimensional metals or semiconductors. Single-electron transistors employing metallic nanotubes and field-effect transistors employing semiconducting nanotubes have been demonstrated. Intramolecular devices have also been proposed which should display a range of other device functions. For example, by introducing a pentagon and a heptagon into the hexagonal carbon lattice, two tube segments with different atomic and electronic structures can be seamlessly fused together to create intramolecular metal-metal, metal-semiconductor, or semiconductor-semiconductor junctions. Here we report electrical transport measurements on SWNTs with intramolecular junctions. We find that a metal-semiconductor junction behaves like a rectifying diode with nonlinear transport characteristics that are strongly asymmetric with respect to bias polarity. In the case of a metal-metal junction, the conductance appears to be strongly suppressed and it displays a power-law dependence on temperatures and applied voltage, consistent with tunnelling between the ends of two Luttinger liquids. Our results emphasize the need to consider screening and electron interactions when designing and modelling molecular devices. Realization of carbon-based molecular electronics will require future efforts in the controlled production of these intramolecular nanotube junctions.

  2. Vibrations of carbon nanotube-reinforced composites

    NASA Astrophysics Data System (ADS)

    Formica, Giovanni; Lacarbonara, Walter; Alessi, Roberto

    2010-05-01

    This work deals with a study of the vibrational properties of carbon nanotube-reinforced composites by employing an equivalent continuum model based on the Eshelby-Mori-Tanaka approach. The theory allows the calculation of the effective constitutive law of the elastic isotropic medium (matrix) with dispersed elastic inhomogeneities (carbon nanotubes). The devised computational approach is shown to yield predictions in good agreement with the experimentally obtained elastic moduli of composites reinforced with uniformly aligned single-walled carbon nanotubes (CNTs). The primary contribution of the present work deals with the global elastic modal properties of nano-structured composite plates. The investigated composite plates are made of a purely isotropic elastic hosting matrix of three different types (epoxy, rubber, and concrete) with embedded single-walled CNTs. The computations are carried out via a finite element (FE) discretization of the composite plates. The effects of the CNT alignment and volume fraction are studied in depth to assess how the modal properties are influenced both globally and locally. As a major outcome, the lowest natural frequencies of CNT-reinforced rubber composites are shown to increase up to 500 percent.

  3. Nonlinear optical transmission in VOx nanotubes and VOx nanotube composites

    NASA Astrophysics Data System (ADS)

    Xu, J.-F.; Czerw, R.; Webster, S.; Carroll, D. L.; Ballato, J.; Nesper, R.

    2002-08-01

    Optical-limiting behavior of vanadium oxide nanotubes is characterized for the visible and infrared spectral ranges using 8 ns pulses from a Nd:YAG laser with an f/40 optical system. Vanadium oxide nanotube dispersions were investigated in both water suspensions and embedded in solid polymethyl methacrylate films. In each case, these nanotubes exhibit strong optical-limiting at 532 nm (in comparison to carbon nanotubes); however, no nonlinear behavior is observed for 1064 nm. This suggests that a two photon or excited state absorption mechanism is responsible for the observed nonlinearity.

  4. Carbon Nanotubes - Polymer Composites with Enhanced Conductivity using Functionalized Nanotubes

    NASA Astrophysics Data System (ADS)

    Ramasubramaniam, Rajagopal; Chen, Jian; Gupta, Rishi

    2003-03-01

    Individual carbon nanotubes show superior electrical, mechanical and thermal properties [1]. Composite materials using carbon nanotubes as fillers are predicted to show similar superior properties. However, realization of such composites has been plagued by poor dispersion of carbon nanotubes in solvents and in polymer matrices. We have developed a method to homogenously disperse carbon nanotubes in polymer matrices using functionalized nanotubes [2]. Thin films of functionalized single walled nanotubes (SWNT) - polystyrene composites and functionalized SWNT - polycarbonate composites were prepared using solution evaporation and spin coating. Both of the composites show several orders of magnitude increase in conductivity for less than 1 wt thresholds of the composites are less than 0.2 wt nanotubes. We attribute the enhanced conduction to the superior dispersion of the functionalized nanotubes in the polymer matrix and to the reduced nanotube waviness resulting from the rigid backbone of the conjugated polymer. References: [1]. R. H. Baughman, A. A. Zakhidov and W. A. de Heer, Science v297, p787 (2002); [2]. J. Chen, H. Liu, W. A. Weimer, M. D. Halls, D. H. Waldeck and G. C. Walker, J. Am. Chem. Soc. v124, p9034 (2002).

  5. Superconducting Nanotube Dots

    NASA Astrophysics Data System (ADS)

    Schönenberger, Christian

    2007-03-01

    In this talk, I will focus on charge transport in carbon nanotube devices with superconducting source and drain contacts in the finite-bias non-equilibrium transport regime. As contact material, bi-layers of Au and Al were used and transport has been studied at temperatures in the 0.1 K range. Because carbon nanotubes are quantum dots (qdots), we in fact explore the physics of qdots with superconducting contacts, something which only recently became possible thanks to carbon nanotubes and most recently to semiconducting nanowires. In my talk, I will first summarize our pioneering work on multiwalled carbon nanotubes in which we could demonstrate proximity induced effects both in the weak and the strong coupling regime. In the latter an intriguing interplay between superconductivity and Kondo physics appears. Then, I will discuss the physics of multiple Andreev reflection in a situation when only one resonant state is present and compare this with experimental results. Finally, I will compare our early results with our recent measurements on single-wall carbon nanotubes. This work has been supported by the Swiss Institute on Nanoscience, the Swiss National Science Foundation, EU projects DIENOW and HYSWITCH. I gratefully acknowledge contribution of the following persons to this work (in alphabetic order): B. Babic, W. Belzig, C. Bruder, M. R. Buitelaar, J.-C. Cuevas, A. Eichler, L. Forro, J. Gobrecht, M. Gr"aber, M. Iqbal, T. Kontos, A. Levy Yeyati, A. Martin-Rodero, T. Nussbaumer, S. Oberholzer, C. Strunk, H. Scharf, J. Trbovic, E. Vecino, M. Weiss

  6. Connecting carbon nanotubes using Sn.

    PubMed

    Mittal, Jagjiwan; Lin, Kwang Lung

    2013-08-01

    Process of Sn coating on mutiwalled carbon nanotubes (MWCNT) and formation of interconnections among nanotubes are studied using high resolution transmission electron microscopy (HRTEM) and energy dispersive X-ray spectroscopy (EDX). Surface oxidation of nanotubes during heating with HNO3 prior to the SnCl2 treatment and the bonding between functional groups and Sn are found to be responsible for the coating and its stability. Open nanotubes are filled as well as coated during tin chloride treatment. Coating and filling are converted into the coatings on the inner as well as outer walls of the nanotubes during reduction with H2/N2. EDX studies show the formation of intermetallic compounds e.g., Cu6Sn5 and Cu3Sn at the joints between nanotubes. Formation of intermetallic compounds is supposed to be responsible for providing the required strength for bending and twisting of nanotubes joining of nanotubes. Paper presents a detailed mechanism of coating and filling processes, and interconnections among nanotubes. PMID:23882800

  7. Fabricating Copper Nanotubes by Electrodeposition

    NASA Technical Reports Server (NTRS)

    Yang, E. H.; Ramsey, Christopher; Bae, Youngsam; Choi, Daniel

    2009-01-01

    Copper tubes having diameters between about 100 and about 200 nm have been fabricated by electrodeposition of copper into the pores of alumina nanopore membranes. Copper nanotubes are under consideration as alternatives to copper nanorods and nanowires for applications involving thermal and/or electrical contacts, wherein the greater specific areas of nanotubes could afford lower effective thermal and/or electrical resistivities. Heretofore, copper nanorods and nanowires have been fabricated by a combination of electrodeposition and a conventional expensive lithographic process. The present electrodeposition-based process for fabricating copper nanotubes costs less and enables production of copper nanotubes at greater rate.

  8. Accelerated dynamics simulations of nanotubes.

    SciTech Connect

    Uberuaga, B. P.; Stuart, S. J.; Voter, A. F.

    2002-01-01

    We report on the application of accelerated dynamics techniques to the study of carbon nanotubes. We have used the parallel replica method and temperature accelerated dynamics simulations are currently in progress. In the parallel replica study, we have stretched tubes at a rate significantly lower than that used in previous studies. In these preliminary results, we find that there are qualitative differences in the rupture of the nanotubes at different temperatures. We plan on extending this investigation to include nanotubes of various chiralities. We also plan on exploring unique geometries of nanotubes.

  9. Carbon nanotube IR detectors (SV)

    SciTech Connect

    Leonard, F. L.

    2012-03-01

    Sandia National Laboratories (Sandia) and Lockheed Martin Corporation (LMC) collaborated to (1) evaluate the potential of carbon nanotubes as channels in infrared (IR) photodetectors; (2) assemble and characterize carbon nanotube electronic devices and measure the photocurrent generated when exposed to infrared light;(3) compare the performance of the carbon nanotube devices with that of traditional devices; and (4) develop and numerically implement models of electronic transport and opto-electronic behavior of carbon nanotube infrared detectors. This work established a new paradigm for photodetectors.

  10. Nanotube-assisted protein deactivation

    NASA Astrophysics Data System (ADS)

    Joshi, Amit; Punyani, Supriya; Bale, Shyam Sundhar; Yang, Hoichang; Borca-Tasciuc, Theodorian; Kane, Ravi S.

    2008-01-01

    Conjugating proteins onto carbon nanotubes has numerous applications in biosensing, imaging and cellular delivery. However, remotely controlling the activity of proteins in these conjugates has never been demonstrated. Here we show that upon near-infrared irradiation, carbon nanotubes mediate the selective deactivation of proteins in situ by photochemical effects. We designed nanotube-peptide conjugates to selectively destroy the anthrax toxin, and also optically transparent coatings that can self-clean following either visible or near-infrared irradiation. Nanotube-assisted protein deactivation may be broadly applicable to the selective destruction of pathogens and cells, and will have applications ranging from antifouling coatings to functional proteomics.

  11. Carbon Nanotubes for Space Applications

    NASA Technical Reports Server (NTRS)

    Meyyappan, Meyya

    2000-01-01

    The potential of nanotube technology for NASA missions is significant and is properly recognized by NASA management. Ames has done much pioneering research in the last five years on carbon nanotube growth, characterization, atomic force microscopy, sensor development and computational nanotechnology. NASA Johnson Space Center has focused on laser ablation production of nanotubes and composites development. These in-house efforts, along with strategic collaboration with academia and industry, are geared towards meeting the agency's mission requirements. This viewgraph presentation (including an explanation for each slide) outlines the research focus for Ames nanotechnology, including details on carbon nanotubes' properties, applications, and synthesis.

  12. Thermoelectric power in carbon nanotubes

    SciTech Connect

    Mavrinskiy, A. V. Baitinger, E. M.

    2009-04-15

    The theoretical results for the temperature dependence of the thermoelectric power of graphite and semimetal carbon nanotubes are reported. In the calculations, the cylindrical superatomic range structure of nanotubes is taken into account. The Boltzmann equation and the {pi}-electron model of semimetal carbon nanotubes are used. The basic parameters of the calculation are the concentration of electrons, the Fermi energy, and the energy of the local level associated with the cylindrical structure of carbon nanotubes. The theoretical results are compared with the available experimental data.

  13. Carbon Nanotube Membranes: Carbon Nanotube Membranes for Energy-Efficient Carbon Sequestration

    SciTech Connect

    2010-03-01

    Broad Funding Opportunity Announcement Project: Porifera is developing carbon nanotube membranes that allow more efficient removal of CO2 from coal plant exhaust. Most of today’s carbon capture methods use chemical solvents, but capture methods that use membranes to draw CO2 out of exhaust gas are potentially more efficient and cost effective. Traditionally, membranes are limited by the rate at which they allow gas to flow through them and the amount of CO2 they can attract from the gas. Smooth support pores and the unique structure of Porifera’s carbon nanotube membranes allows them to be more permeable than other polymeric membranes, yet still selective enough for CO2 removal. This approach could overcome the barriers facing membrane-based approaches for capturing CO2 from coal plant exhausts.

  14. Controlled synthesis and tunable properties of ultrathin silica nanotubes through spontaneous polycondensation on polyamine fibrils

    PubMed Central

    Yuan, Jian-Jun; Zhu, Pei-Xin; Noda, Daisuke

    2013-01-01

    Summary This paper describes a facile approach to a biomimetic rapid fabrication of ultrathin silica nanotubes with a highly uniform diameter of 10 nm and inner hollow of around 3 nm. The synthesis is carried out through a spontaneous polycondensation of alkoxysilane on polyamine crystalline fibrils that were conveniently produced from the neutralization of a solution of protonated linear polyethyleneimine (LPEI–H+) by alkali compounds. A simple mixing the fibrils with alkoxysilane in aqueous solution allowed for the rapid formation of silica to produce LPEI@silica hybrid nanotubes. These 10-nm nanotubes were hierarchically organized in a mat-like morphology with a typical size of 1–2 micrometers. The subsequent removal of organic LPEI via calcination resulted in silica nanotubes that keep this morphology. The morphology, the structure, the pore properties and the formation mechanism of the silica nanotubes were carefully investigated with scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller measurements (BET), and X-ray diffraction (XRD). Detailed studies demonstrated that the formation of the nanotubes depends on the molar ratio of [OH]/[CH2CH2NH] during the neutralization as well as on the basicity of the alkali compound and on the concentration of the silica source. The synthesis of silica nanotubes established here could be easily applied to a fabrication on the kilogram scale. Silica nanotubes that were obtained from the calcination of hybrid nanotubes of LPEI@silica in an N2 atmosphere showed a distinct photoluminescence centered at 540 nm with a maximum excitation wavelength of 320 nm. Furthermore, LPEI@silica hybrid nanotubes were applied to create silica–carbon composite nanotubes by alternative adsorption of ionic polymers and subsequent carbonization. PMID:24367748

  15. Carbon Nanotubes in Biology and Medicine: In vitro and in vivo Detection, Imaging and Drug Delivery

    PubMed Central

    Liu, Zhuang; Tabakman, Scott; Welsher, Kevin; Dai, Hongjie

    2010-01-01

    Carbon nanotubes exhibit many unique intrinsic physical and chemical properties and have been intensively explored for biological and biomedical applications in the past few years. In this comprehensive review, we summarize the main results from our and other groups in this field and clarify that surface functionalization is critical to the behavior of carbon nanotubes in biological systems. Ultrasensitive detection of biological species with carbon nanotubes can be realized after surface passivation to inhibit the non-specific binding of biomolecules on the hydrophobic nanotube surface. Electrical nanosensors based on nanotubes provide a label-free approach to biological detection. Surface-enhanced Raman spectroscopy of carbon nanotubes opens up a method of protein microarray with detection sensitivity down to 1 fmol/L. In vitro and in vivo toxicity studies reveal that highly water soluble and serum stable nanotubes are biocompatible, nontoxic, and potentially useful for biomedical applications. In vivo biodistributions vary with the functionalization and possibly also size of nanotubes, with a tendency to accumulate in the reticuloendothelial system (RES), including the liver and spleen, after intravenous administration. If well functionalized, nanotubes may be excreted mainly through the biliary pathway in feces. Carbon nanotube-based drug delivery has shown promise in various In vitro and in vivo experiments including delivery of small interfering RNA (siRNA), paclitaxel and doxorubicin. Moreover, single-walled carbon nanotubes with various interesting intrinsic optical properties have been used as novel photoluminescence, Raman, and photoacoustic contrast agents for imaging of cells and animals. Further multidisciplinary explorations in this field may bring new opportunities in the realm of biomedicine. PMID:20174481

  16. Synthesis of Platinum Nanotubes and Nanorings via Simultaneous Metal Alloying and Etching.

    PubMed

    Huang, Zhiqi; Raciti, David; Yu, Shengnan; Zhang, Lei; Deng, Lin; He, Jie; Liu, Yijing; Khashab, Niveeen M; Wang, Chao; Gong, Jinlong; Nie, Zhihong

    2016-05-25

    Metallic nanotubes represent a class of hollow nanostructures with unique catalytic properties. However, the wet-chemical synthesis of metallic nanotubes remains a substantial challenge, especially for those with dimensions below 50 nm. This communication describes a simultaneous alloying-etching strategy for the synthesis of Pt nanotubes with open ends by selective etching Au core from coaxial Au/Pt nanorods. This approach can be extended for the preparation of Pt nanorings when Saturn-like Au core/Pt shell nanoparticles are used. The diameter and wall thickness of both nanotubes and nanorings can be readily controlled in the range of 14-37 nm and 2-32 nm, respectively. We further demonstrated that the nanotubes with ultrathin side walls showed superior catalytic performance in oxygen reduction reaction. PMID:27090384

  17. TRANSPORT SPECTROSCOPY OF CHEMICAL NANOSTRUCTURES: The Case of Metallic Single-Walled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Liang, Wenjie; Bockrath, Marc; Park, Hongkun

    2005-05-01

    Transport spectroscopy, a technique based on current-voltage measurements of individual nanostructures in a three-terminal transistor geometry, has emerged as a powerful new tool to investigate the electronic properties of chemically derived nanostructures. In this review, we discuss the utility of this approach using the recent studies of single-nanotube transistors as an example. Specifically, we discuss how transport measurements can be used to gain detailed insight into the electronic motion in metallic single-walled carbon nanotubes in several distinct regimes, depending on the coupling strength of the contacts to the nanotubes. Measurements of nanotube devices in these different conductance regimes have enabled a detailed analysis of the transport properties, including the experimental determination of all Hartree-Fock parameters that govern the electronic structure of metallic nanotubes and the demonstration of Fabry-Perot resonators based on the interference of electron waves.

  18. Facile Synthesis of Highly Aligned Multiwalled Carbon Nanotubes from Polymer Precursors

    DOE PAGESBeta

    Han, Catherine Y.; Xiao, Zhi-Li; Wang, H. Hau; Lin, Xiao-Min; Trasobares, Susana; Cook, Russell E.

    2009-01-01

    We report a facile one-step approach which involves no flammable gas, no catalyst, and no in situ polymerization for the preparation of well-aligned carbon nanotube array. A polymer precursor is placed on top of an anodized aluminum oxide (AAO) membrane containing regular nanopore arrays, and slow heating under Ar flow allows the molten polymer to wet the template through adhesive force. The polymer spread into the nanopores of the template to form polymer nanotubes. Upon carbonization the resulting multi-walled carbon nanotubes duplicate the nanopores morphology precisely. The process is demonstrated for 230, 50, and 20 nm pore membranes. The synthesized carbonmore » nanotubes are characterized with scanning/transmission electron microscopies, Raman spectroscopy, and resistive measurements. Convenient functionalization of the nanotubes with this method is demonstrated through premixing CoPt nanoparticles in the polymer precursors.« less

  19. Selective adsorption of proteins on single-wall carbon nanotubes by using a protective surfactant.

    PubMed

    Knyazev, Anton; Louise, Loïc; Veber, Michèle; Langevin, Dominique; Filoramo, Arianna; Prina-Mello, Adriele; Campidelli, Stéphane

    2011-12-16

    The dispersion of highly hydrophobic carbon materials such as carbon nanotubes in biological media is a challenging issue. Indeed, the nonspecific adsorption of proteins occurs readily when the nanotubes are introduced in biological media; therefore, a methodology to control adsorption is in high demand. To address this issue, we developed a bifunctional linker derived from pyrene that selectively enables or prevents the adsorption of proteins on single-wall carbon nanotubes (SWNTs). We demonstrated that it is possible to decrease or completely suppress the adsorption of proteins on the nanotube sidewall by using proper functionalization (either covalent or noncovalent). By subsequently activating the functional groups on the nanotube derivatives, protein adsorption can be recovered and, therefore, controlled. Our approach is simple, straightforward, and potentially suitable for other biomolecules that contain thio or amino groups available for coupling. PMID:22095560

  20. Lipid nanotube formation using space-regulated electric field above interdigitated electrodes.

    PubMed

    Bi, Hongmei; Fu, Dingguo; Wang, Lei; Han, Xiaojun

    2014-04-22

    Lipid nanotubes have great potential in biology and nanotechnology. Here we demonstrate a method to form lipid nanotubes using space-regulated AC electric fields above coplanar interdigitated electrodes. The AC electric field distribution can be regulated by solution height above the electrodes. The ratio of field component in x axis (Ex) to field component in z axis (Ez) increases dramatically at solution height below 50 μm; therefore, at lower solution height, the force from Ex predominantly drives lipids to form lipid nanotubes along with the electric field direction. The forces exerted on the lipid nanotube during its formation were analyzed in detail, and an equation was obtained to describe the relationship among nanotube length and field frequency, amplitude, and time. We believe that the presented approach opens a way to design and prepare nanoscale materials with unique structural and functional properties using space-regulated electric fields. PMID:24669822

  1. Relationships among the structural topology, bond strength, and mechanical properties of single-walled aluminosilicate nanotubes

    NASA Astrophysics Data System (ADS)

    Liou, Kai-Hsin; Tsou, Nien-Ti; Kang, Dun-Yen

    2015-10-01

    Carbon nanotubes (CNTs) are regarded as small but strong due to their nanoscale microstructure and high mechanical strength (Young's modulus exceeds 1000 GPa). A longstanding question has been whether there exist other nanotube materials with mechanical properties as good as those of CNTs. In this study, we investigated the mechanical properties of single-walled aluminosilicate nanotubes (AlSiNTs) using a multiscale computational method and then conducted a comparison with single-walled carbon nanotubes (SWCNTs). By comparing the potential energy estimated from molecular and macroscopic material mechanics, we were able to model the chemical bonds as beam elements for the nanoscale continuum modeling. This method allowed for simulated mechanical tests (tensile, bending, and torsion) with minimum computational resources for deducing their Young's modulus and shear modulus. The proposed approach also enabled the creation of hypothetical nanotubes to elucidate the relative contributions of bond strength and nanotube structural topology to overall nanotube mechanical strength. Our results indicated that it is the structural topology rather than bond strength that dominates the mechanical properties of the nanotubes. Finally, we investigated the relationship between the structural topology and the mechanical properties by analyzing the von Mises stress distribution in the nanotubes. The proposed methodology proved effective in rationalizing differences in the mechanical properties of AlSiNTs and SWCNTs. Furthermore, this approach could be applied to the exploration of new high-strength nanotube materials.Carbon nanotubes (CNTs) are regarded as small but strong due to their nanoscale microstructure and high mechanical strength (Young's modulus exceeds 1000 GPa). A longstanding question has been whether there exist other nanotube materials with mechanical properties as good as those of CNTs. In this study, we investigated the mechanical properties of single

  2. Nanotube attachment for prevention of interfacial delamination

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, Sharmila M.; Karumuri, Anil K.

    2010-09-01

    A new approach to suppressing interfacial delamination in composites has been investigated. It involves growing strongly attached nanotubes on the surface of the core phase prior to matrix infiltration. Unusually durable interfaces between epoxy and graphite have been demonstrated using this technique. Two types of graphitic core materials have been studied: complex cellular foams having open-interconnected porosity and highly oriented pyrolitic graphite (HOPG) providing a model flat interface. When untreated foam is infiltrated with epoxy, the resulting composite is brittle, and shatters before 10% compression. However, when carbon nanotubes (CNTs) are grown on the foam prior to epoxy infiltration, the specimen becomes pliable, and visibly flattens out rather than fracturing. Model studies on a flat graphite-epoxy interface were performed by joining two HOPG specimens with a thin layer of epoxy, and testing the flexural response of the 'seam' using the three-point bend test. The untreated HOPG sandwich fails easily, whereas nanotube-attached HOPG sandwich shows an over three times increase in flexural load-carrying capacity, close to that of seamless monolithic graphite having identical dimensions. Microscopic evaluations of fractured interfaces indicate that, in all geometries, CNT grafting prevents delamination at the graphite-epoxy interface, and forces any crack(s) to propagate through the graphitic phase. This added inter-laminar strength and toughness can be related to the hierarchical morphology of the interface created by CNT attachment, and unprecedented composite structures can be envisioned.

  3. Virus-templated self-assembled single-walled carbon nanotubes for highly efficient electron collection in photovoltaic devices

    NASA Astrophysics Data System (ADS)

    Dang, Xiangnan; Yi, Hyunjung; Ham, Moon-Ho; Qi, Jifa; Yun, Dong Soo; Ladewski, Rebecca; Strano, Michael S.; Hammond, Paula T.; Belcher, Angela M.

    2011-06-01

    The performance of photovoltaic devices could be improved by using rationally designed nanocomposites with high electron mobility to efficiently collect photo-generated electrons. Single-walled carbon nanotubes exhibit very high electron mobility, but the incorporation of such nanotubes into nanocomposites to create efficient photovoltaic devices is challenging. Here, we report the synthesis of single-walled carbon nanotube-TiO2 nanocrystal core-shell nanocomposites using a genetically engineered M13 virus as a template. By using the nanocomposites as photoanodes in dye-sensitized solar cells, we demonstrate that even small fractions of nanotubes improve the power conversion efficiency by increasing the electron collection efficiency. We also show that both the electronic type and degree of bundling of the nanotubes in the nanotube/TiO2 complex are critical factors in determining device performance. With our approach, we achieve a power conversion efficiency in the dye-sensitized solar cells of 10.6%.

  4. Virus-templated self-assembled single-walled carbon nanotubes for highly efficient electron collection in photovoltaic devices.

    PubMed

    Dang, Xiangnan; Yi, Hyunjung; Ham, Moon-Ho; Qi, Jifa; Yun, Dong Soo; Ladewski, Rebecca; Strano, Michael S; Hammond, Paula T; Belcher, Angela M

    2011-06-01

    The performance of photovoltaic devices could be improved by using rationally designed nanocomposites with high electron mobility to efficiently collect photo-generated electrons. Single-walled carbon nanotubes exhibit very high electron mobility, but the incorporation of such nanotubes into nanocomposites to create efficient photovoltaic devices is challenging. Here, we report the synthesis of single-walled carbon nanotube-TiO(2) nanocrystal core-shell nanocomposites using a genetically engineered M13 virus as a template. By using the nanocomposites as photoanodes in dye-sensitized solar cells, we demonstrate that even small fractions of nanotubes improve the power conversion efficiency by increasing the electron collection efficiency. We also show that both the electronic type and degree of bundling of the nanotubes in the nanotube/TiO(2) complex are critical factors in determining device performance. With our approach, we achieve a power conversion efficiency in the dye-sensitized solar cells of 10.6%. PMID:21516089

  5. Electron transport properties of a single-walled carbon nanotube in the presence of hydrogen cyanide: first-principles analysis.

    PubMed

    Srivastava, Anurag; Sharma, Vikash; Kaur, Kamalpreet; Khan, Md Shahzad; Ahuja, Rajeev; Rao, V K

    2015-07-01

    First-principles analysis based on density functional theory was performed to compute the electronic and transport properties of a single-walled carbon nanotube in the presence of hydrogen cyanide. A chiral (4,1) carbon nanotube was found to become less metallic as the number of hydrogen cyanide molecules nearby increased. When there were a sufficient number of hydrogen cyanide molecules close to the nanotube, it became semiconducting. This metallic to semiconducting transformation of the nanotube was verified by analyzing its conductance and current as a function of the number of molecules of hydrogen cyanide present. The conductivity of the carbon nanotube was very high when no hydrogen cyanide molecules were present, but decreased considerably when even just a single hydrogen cyanide molecule approached the surface of the nanotube. PMID:26072123

  6. Carbon nanotube-polymer composite actuators

    DOEpatents

    Gennett, Thomas; Raffaelle, Ryne P.; Landi, Brian J.; Heben, Michael J.

    2008-04-22

    The present invention discloses a carbon nanotube (SWNT)-polymer composite actuator and method to make such actuator. A series of uniform composites was prepared by dispersing purified single wall nanotubes with varying weight percents into a polymer matrix, followed by solution casting. The resulting nanotube-polymer composite was then successfully used to form a nanotube polymer actuator.

  7. Electrical and optical characterization of carbon nanotube diodes

    NASA Astrophysics Data System (ADS)

    Malapanis, Argyrios

    Carbon nanotubes are good candidates for future applications, including nanoelectronic and nanophotonic devices. Their quasi-one dimensional (1D) character offers appealing device properties. These include reduced carrier scattering, carrier mobility up to two orders of magnitude higher than that of materials used in state-of-the-art computer chips today, current densities rivaling those of the best semiconductors, enhanced optical absorption, and band gaps tunable with tube diameter and doping. Recent breakthroughs in research point to the possibility of placing nanotubes precisely on substrates with densities approaching that of transistors on today's computer chips in a way that's integratable with existing Si-based technology. Such advances may accelerate the day when high-speed and power-efficient applications using carbon nanotubes as the transistor channel can become a reality. Thus the need to explore the fundamental properties of carbon nanotubes becomes more pressing. Using single-walled carbon nanotube (SWNT) p-n diodes as the medium, the purpose of this work is to examine SWNT fundamental properties that little experimental work has dealt with measuring. These properties include the band-gap of a SWNT, band-gap renormalization (shrinkage) as a function of doping, and optical absorption in the infrared region of the spectrum. This dissertation also shows the extreme sensitivity of carbon nanotubes to their environment (i.e. exposure to air). In addition, it demonstrates a new technique---current annealing---that can reverse the degradation of the electrical and optical properties of carbon nanotube diodes due to ambient exposure

  8. Combining Portable Raman Probes with Nanotubes for Theranostic Applications

    PubMed Central

    Bhirde, Ashwinkumar A.; Liu, Gang; Jin, Albert; Iglesias-Bartolome, Ramiro; Sousa, Alioscka A.; Leapman, Richard D.; Gutkind, J. Silvio; Lee, Seulki; Chen, Xiaoyuan

    2011-01-01

    Recently portable Raman probes have emerged along with a variety of applications, including carbon nanotube (CNT) characterization. Aqueous dispersed CNTs have shown promise for biomedical applications such as drug/gene delivery vectors, photo-thermal therapy, and photoacoustic imaging. In this study we report the simultaneous detection and irradiation of carbon nanotubes in 2D monolayers of cancer cells and in 3D spheroids using a portable Raman probe. A portable handheld Raman instrument was utilized for dual purposes: as a CNT detector and as an irradiating laser source. Single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) were dispersed aqueously using a lipid-polymer (LP) coating, which formed highly stable dispersions both in buffer and cell media. The LP coated SWCNT and MWCNT aqueous dispersions were characterized by atomic force microscopy, transmission electron microscopy, dynamic light scattering, Fourier transform infrared spectroscopy and Raman spectroscopy. The cellular uptake of the LP-dispersed SWCNTs and MWCNTs was observed using confocal microscopy, and fluorescein isothiocyanate (FITC)-nanotube conjugates were found to be internalized by ovarian cancer cells by using Z-stack fluorescence confocal imaging. Biocompatibility of SWCNTs and MWCNTs was assessed using a cell viability MTT assay, which showed that the nanotube dispersions did not hinder the proliferation of ovarian cancer cells at the dosage tested. Ovarian cancer cells treated with SWCNTs and MWCNTs were simultaneously detected and irradiated live in 2D layers of cancer cells and in 3D environments using the portable Raman probe. An apoptotic terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay carried out after laser irradiation confirmed that cell death occurred only in the presence of nanotube dispersions. We show for the first time that both SWCNTs and MWCNTs can be selectively irradiated and detected in cancer cells using a simple

  9. Silicon Carbide Nanotube Synthesized

    NASA Technical Reports Server (NTRS)

    Lienhard, Michael A.; Larkin, David J.

    2003-01-01

    Carbon nanotubes (CNTs) have generated a great deal of scientific and commercial interest because of the countless envisioned applications that stem from their extraordinary materials properties. Included among these properties are high mechanical strength (tensile and modulus), high thermal conductivity, and electrical properties that make different forms of single-walled CNTs either conducting or semiconducting, and therefore, suitable for making ultraminiature, high-performance CNT-based electronics, sensors, and actuators. Among the limitations for CNTs is their inability to survive in high-temperature, harsh-environment applications. Silicon carbon nanotubes (SiCNTs) are being developed for their superior material properties under such conditions. For example, SiC is stable in regards to oxidation in air to temperatures exceeding 1000 C, whereas carbon-based materials are limited to 600 C. The high-temperature stability of SiCNTs is envisioned to enable high-temperature, harsh-environment nanofiber- and nanotube-reinforced ceramics. In addition, single-crystal SiC-based semiconductors are being developed for hightemperature, high-power electronics, and by analogy to CNTs with silicon semiconductors, SiCNTs with single-crystal SiC-based semiconductors may allow high-temperature harsh-environment nanoelectronics, nanosensors, and nanoactuators to be realized. Another challenge in CNT development is the difficulty of chemically modifying the tube walls, which are composed of chemically stable graphene sheets. The chemical substitution of the CNTs walls will be necessary for nanotube self-assembly and biological- and chemical-sensing applications. SiCNTs are expected to have a different multiple-bilayer wall structure, allowing the surface Si atoms to be functionalized readily with molecules that will allow SiCNTs to undergo self-assembly and be compatible with a variety of materials (for biotechnology applications and high-performance fiber-reinforced ceramics).

  10. Carbon nanotube network varactor.

    PubMed

    Generalov, A A; Anoshkin, I V; Erdmanis, M; Lioubtchenko, D V; Ovchinnikov, V; Nasibulin, A G; Räisänen, A V

    2015-01-30

    Microelectromechanical system (MEMS) varactors based on a freestanding layer of single-walled carbon nanotube (SWCNT) films were designed, fabricated and tested. The freestanding SWCNT film was employed as a movable upper patch in the parallel plate capacitor of the MEMS. The measurements of the SWCNT varactors show very high tunability, nearly 100%, of the capacitance with a low actuation voltage of 10 V. The functionality of the varactor is improved by implementing a flexible nanocellulose aerogel filling. PMID:25556375

  11. Carbon nanotube network varactor

    NASA Astrophysics Data System (ADS)

    Generalov, A. A.; Anoshkin, I. V.; Erdmanis, M.; Lioubtchenko, D. V.; Ovchinnikov, V.; Nasibulin, A. G.; Räisänen, A. V.

    2015-01-01

    Microelectromechanical system (MEMS) varactors based on a freestanding layer of single-walled carbon nanotube (SWCNT) films were designed, fabricated and tested. The freestanding SWCNT film was employed as a movable upper patch in the parallel plate capacitor of the MEMS. The measurements of the SWCNT varactors show very high tunability, nearly 100%, of the capacitance with a low actuation voltage of 10 V. The functionality of the varactor is improved by implementing a flexible nanocellulose aerogel filling.

  12. Carbon nanotube materials for hydrogen storage

    SciTech Connect

    Dillon, A.C.; Jones, K.M.; Heben, M.J.

    1996-10-01

    Hydrogen burns pollution-free and may be produced from renewable energy resources. It is therefore an ideal candidate to replace fossil fuels as an energy carrier. However, the lack of a convenient and cost-effective hydrogen storage system greatly impedes the wide-scale use of hydrogen in both domestic and international markets. Although several hydrogen storage options exist, no approach satisfies all of the efficiency, size, weight, cost and safety requirements for transportation or utility use. A material consisting exclusively of micropores with molecular dimensions could simultaneously meet all of the requirements for transportation use if the interaction energy for hydrogen was sufficiently strong to cause hydrogen adsorption at ambient temperatures. Small diameter ({approx}1 mm) carbon single-wall nanotubes (SWNTs) are elongated micropores of molecular dimensions, and materials composed predominantly of SWNTs may prove to be the ideal adsorbent for ambient temperature storage of hydrogen. Last year the authors reported that hydrogen could be adsorbed on arc-generated soots containing 12{Angstrom} diameter nanotubes at temperatures in excess of 285K. In this past year they have learned that such adsorption does not occur on activated carbon materials, and that the cobalt nanoparticles present in their arc-generated soots are not responsible for the hydrogen which is stable at 285 K. These results indicate that enhanced adsorption forces within the internal cavities of the SWNTs are active in stabilizing hydrogen at elevated temperatures. This enhanced stability could lead to effective hydrogen storage under ambient temperature conditions. In the past year the authors have also demonstrated that single-wall carbon nanotubes in arc-generated soots may be selectively opened by oxidation in H{sub 2}O resulting in improved hydrogen adsorption, and they have estimated experimentally that the amount of hydrogen stored is {approximately}10% of the nanotube weight.

  13. Chemical Sensing with Polyaniline Coated Single-Walled Carbon Nanotubes

    SciTech Connect

    Ding, Mengning; Tang, Yifan; Gou, Pingping; Reber, Michael J; Star, Alexander

    2011-01-25

    Single-walled carbon nanotube/polyaniline (SWNT/PAni) nanocomposite with controlled core/shell morphology was synthesized by a noncovalent functionalization approach. Unique electron interactions between the SWNT core and the PAni shell were studied electrochemically and spectroscopically, and superior sensor performance to chemical gases and vapors was demonstrated.

  14. Teslaphoresis of Carbon Nanotubes.

    PubMed

    Bornhoeft, Lindsey R; Castillo, Aida C; Smalley, Preston R; Kittrell, Carter; James, Dustin K; Brinson, Bruce E; Rybolt, Thomas R; Johnson, Bruce R; Cherukuri, Tonya K; Cherukuri, Paul

    2016-04-26

    This paper introduces Teslaphoresis, the directed motion and self-assembly of matter by a Tesla coil, and studies this electrokinetic phenomenon using single-walled carbon nanotubes (CNTs). Conventional directed self-assembly of matter using electric fields has been restricted to small scale structures, but with Teslaphoresis, we exceed this limitation by using the Tesla coil's antenna to create a gradient high-voltage force field that projects into free space. CNTs placed within the Teslaphoretic (TEP) field polarize and self-assemble into wires that span from the nanoscale to the macroscale, the longest thus far being 15 cm. We show that the TEP field not only directs the self-assembly of long nanotube wires at remote distances (>30 cm) but can also wirelessly power nanotube-based LED circuits. Furthermore, individualized CNTs self-organize to form long parallel arrays with high fidelity alignment to the TEP field. Thus, Teslaphoresis is effective for directed self-assembly from the bottom-up to the macroscale. PMID:27074626

  15. Nanotube Nano-actuators

    NASA Astrophysics Data System (ADS)

    Jennifer, Sippel; Arnason, Steve; Baughman, Ray; Rinzler, Andrew

    2002-03-01

    In 1999 it was found that a thin sheet of single wall carbon nanotubes (buckypaper) can act as an electromechanical transducer (an actuator), converting an applied voltage into a dimensional change, with the potential to do work.[1] The mechanism proposed for the effect is quite fundamental, relying on modification of the nearest neighbor carbon-carbon distance due to charge injected into the nanotube pi-orbital system. Because the experiment relied on buckypaper, which possesses nanoscale pores (where gas generation might also account for dimensional changes), as well as creep (where ropes sliding against one another make it difficult to determine the magnitude of the effect in the fundamental unit), the demonstration was less than ideal. Using an atomic force microscope for detection, we have now performed corresponding measurements on individual ropes of nanotubes tethered across micromachined trenches in silicon substrates. The experiment and results will be described. 1. R. H. Baughman, C. X. Cui, A. A. Zakhidov, Z. Iqbal, J. N. Barisci, G. M. Spinks, G. G. Wallace, A. Mazzoldi, D DeRossi, A. G. Rinzler, O. Jaschinski, S. Roth, M. Kertesz, Science, 284, 1340 (1999).

  16. Molecular mechanics methods for individual carbon nanotubes and nanotube assemblies

    NASA Astrophysics Data System (ADS)

    Eberhardt, Oliver; Wallmersperger, Thomas

    2015-04-01

    Since many years, carbon nanotubes (CNTs) have been considered for a wide range of applications due to their outstanding mechanical properties. CNTs are tubular structures, showing a graphene like hexagonal lattice. Our interest in the calculation of the mechanical properties is motivated by several applications which demand the knowledge of the material behavior. One application in which the knowledge of the material behavior is vital is the CNT based fiber. Due to the excellent stiffness and strength of the individual CNTs, these fibers are expected to be a promising successor for state of the art carbon fibers. However, the mechanical properties of the fibers fall back behind the properties of individual CNTs. It is assumed that this gap in the properties is a result of the van-der-Waals interactions of the individual CNTs within the fiber. In order to understand the mechanical behavior of the fibers we apply a molecular mechanics approach. The mechanical properties of the individual CNTs are investigated by using a modified structural molecular mechanics approach. This is done by calculating the properties of a truss-beam element framework representing the CNT with the help of a chemical force field. Furthermore, we also investigate the interactions of CNTs arranged in basic CNT assemblies, mimicking the ones in a simple CNT fiber. We consider the van-der-Waals interactions in the structure and calculate the potential surface of the CNT assemblies.

  17. CARBON NANOTUBES AS MULTIPOLLUTANT SORBENTS

    EPA Science Inventory

    Exploratory Research Program Project - Carbon nanotubes (CNTs) are formed from graphite (or graphene) sheets rolled into tubes, typically with diameters of 1 - 10 nm and lengths of 200 - 500 nm. Carbon nanotubes have unique electrical properties that have led to interest in thei...

  18. Conduction in Carbon Nanotube Networks

    NASA Astrophysics Data System (ADS)

    Kaiser, A. B.; Rogers, S. A.

    2003-10-01

    Recent measurements of the resistivity of single-wall carbon nanotube (SWNT) networks are consistent with our model of metallic conduction interrupted by barriers. We extend our model of thermopower nonlinearities due to peaks in the density of electronic states and apply it to recent thermopower data for carbon nanotube networks.

  19. Progress Toward Sequestering Carbon Nanotubes in PmPV

    NASA Technical Reports Server (NTRS)

    Bley, Richard A.

    2009-01-01

    Sequestration of single-walled carbon nanotubes (SWNTs) in molecules of poly(m-phenylenevinylene-co-2,5-diocty-loxy-p-phenylenevinylene) [PmPV] is a candidate means of promoting dissolution of single-walled carbon nanotubes (SWNTs) into epoxies for making strong, lightweight epoxy-matrix/carbon-fiber composite materials. Bare SWNTs cannot be incorporated because they are not soluble in epoxies. In the present approach, one exploits the tendency of PmPV molecules to wrap themselves around SWNTs without chemically bonding to them.

  20. CVD Growth of Carbon Nanotubes: Structure, Catalyst, and Growth

    NASA Technical Reports Server (NTRS)

    Delzeit, Lance

    2003-01-01

    Carbon nanotubes (CNTs) exhibit extraordinary mechanical and unique electronic properties and hence have been receiving much attention in recent years for their potential in nanoelectronics, field emission devices, scanning probes, high strength composites and many more applications. Catalytic decomposition of hydrocarbon feedstock with the aid of supported transition metal catalysts - also known as chemical vapor deposition (CVD) - has become popular to produce single-walled and multi-walled nanotubes (SWNTs, MWNTs) and multiwalled nanofibers (MWNFs). The ability to grow CNTs on patterned substrates and in vertically aligned arrays, and the simplicity of the process, has made CVD growth of CNTs an attractive approach.

  1. Nanotubes for noisy signal processing

    NASA Astrophysics Data System (ADS)

    Lee, Ian Yenyin

    Nanotubes can process noisy signals. We present two central results in support of this general thesis and make an informed extrapolation that uses nanotubes to improve body armor. The first result is that noise can help nanotubes detect weak signals. The finding confirmed a stochastic-resonance theoretical prediction that noise can enhance detection at the nano-level. Laboratory experiments with nanotubes showed that three types of noise improved three measures of detection. Small amounts of Gaussian, uniform, and Cauchy additive white noise increased mutual-information, cross-correlation, and bit-error-rate measures before degrading them with further increases in noise. Nanotubes can apply this noise-enhancement and nanotube electrical and mechanical properties to improve signal processing. Similar noise enhancement may benefit a proposed nanotube-array cochlear-model spectral processing. The second result is that nanotube antennas can directly detect narrowband electromagnetic (EM) signals. The finding showed that nanotube and thin-wire dipoles are similar: They are resonant and narrowband and can implement linear-array designs if the EM waves in the nanotubes propagate at or near the free-space velocity of light. The nanotube-antenna prediction is based on a Fresnel-zone or near-zone analysis of antenna impedance using a quantum-conductor model. The analysis also predicts a failure to resonate if the nanotube EM-wave propagation is much slower than free-space light propagation. We extrapolate based on applied and theoretical analysis of body armor. Field experiments used a baseball comparison and statistical and other techniques to model body-armor bruising effects. A baseball comparison showed that a large caliber handgun bullet can hit an armored chest as hard as a fast baseball can hit a bare chest. Adaptive fuzzy systems learned to predict a bruise profile directly from the experimental data and also from statistical analysis of the data. Nanotube signal

  2. Optoelectronics with Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Kinoshita, Megumi

    2011-12-01

    The carbon nanotube is a promising material for future micro- and nano-scale electronics because of its unique electronic properties, high carrier mobility and extraordinary capacity for high current density. In particular, semiconducting carbon nanotubes are direct bandgap materials with a typical energy gap in the order of 1 eV, which means they emit light in the near-infrared range, making them an attractive option in telecommunications applications. However, there have been few systematic investigations of electrically-induced light emission (i.e. electroluminescence) from carbon nanotubes, and their emission properties are not well understood. In this dissertation, we explore the characteristics of electroluminescence in three different types of carbon-nanotube devices. The first is a single-tube field-effect transistor (CNTFET), whose emission has previously been found to have a very broad spectral shape and low emission efficiency. We analyze the spectral shape in detail, which reveals that a high electric field near metal contacts contributes most to the bias-dependent component of broadening, in addition to smaller contributions from tube nonuniformity, inelastic scattering of phonons, high temperature, etc. In the second part of the study, single-tube light-emitting diodes are constructed by employing a split top-gate scheme. The split gate creates p- and n-doped regions electrostatically, so that electrons and holes combine between the two sections and can decay radiatively. This configuration creates electron-hole pairs under much lower electric fields and gives us a greater control over carrier distribution in the device channel, resulting in much narrower spectral linewidths and an emission intensity several orders of magnitude larger than that of CNTFETs. The much better signal-to-noise also leads to the observation of emission from defect-induced states. Finally, we extend the idea of the single-tube p-n diode and fabricate CNT film diodes from many

  3. Building Organized Structures using Nanotubes

    NASA Astrophysics Data System (ADS)

    Ajayan, Pulickel M.

    This talk will focus on the directed assembly of multiwalled carbon nanotubes on planar substrates into highly organized structures that include vertically and horizontally oriented arrays, ordered fibers and porous membranes. The concept of growing such architectures is based on growth selectivity on certain surfaces compared to others. Selective placement of ordered nanotube arrays is achieved on patterned templates prepared by lithography or oxide templates with well-defined pores. Growth of nanotubes is achieved by chemical vapor deposition (CVD) using hydrocarbon precursors and vapor phase catalyst delivery. The new technique developed in our laboratory allows enormous flexibility in building a large number of complex structures based on nanotube building units. We will also discuss some of our recent efforts in creating nanotube junctions selectively and controllably.

  4. Superhydrogels of nanotubes capable of capturing heavy-metal ions.

    PubMed

    Song, Shasha; Wang, Haiqiao; Song, Aixin; Hao, Jingcheng

    2014-01-01

    Self-assembly regulated by hydrogen bonds was successfully achieved in the system of lithocholic acid (LCA) mixed with three organic amines, ethanolamine (EA), diethanolamine (DEA), and triethanolamine (TEA), in aqueous solutions. The mixtures of DEA/LCA exhibit supergelation capability and the hydrogels consist of plenty of network nanotubes with uniform diameters of about 60 nm determined by cryogenic TEM. Interestingly, the sample with the same concentration in a system of EA and LCA is a birefringent solution, in which spherical vesicles and can be transformed into nanotubes as the amount of LCA increases. The formation of hydrogels could be driven by the delicate balance of diverse noncovalent interactions, including electrostatic interactions, hydrophobic interactions, steric effects, van der Waals forces, and mainly hydrogen bonds. The mechanism of self-assembly from spherical bilayer vesicles into nanotubes was proposed. The dried hydrogels with nanotubes were explored to exhibit the excellent capability for capturing heavy-metal ions, for example, Cu(2+), Co(2+), Ni(2+), Pb(2+), and Hg(2+). The superhydrogels of nanotubes from the self-assembly of low-molecular-weight gelators mainly regulated by hydrogen bonds used for the removal of heavy-metal ions is simple, green, and high efficiency, and provide a strategic approach to removing heavy-metal ions from industrial sewage. PMID:24136830

  5. Synthesis and Characterization of Polydiacetylene Films and Nanotubes

    PubMed Central

    Gatebe, Erastus; Herron, Hayley; Zakeri, Rashid; Rajasekaran, Pradeep Ramiah; Aouadi, Samir; Kohli, Punit

    2009-01-01

    We report here the synthesis and characterization of polydiacetylene (PDA) films and nanotubes using layer-by-layer (LBL) chemistry. 10,12-Docosadiyndioic acid (DCDA) monomer was self-assembled on flat surfaces and inside of nanoporous alumina templates. UV irradiation of DCDA provided polymerized-DCDA (PDCDA) films and nanotubes. We have used zirconium-carboxylate interlayer chemistry to synthesize PDCDA multilayers on flat surfaces and in nanoporous template. PDCDA multilayers were characterized using optical (UV–vis, fluorescence, ellipsometry, FTIR) spectroscopies, ionic current–voltage (I–V) analysis, and scanning electron microscopy. Ellipsometry, FTIR, electronic absorption and emission spectroscopies showed a uniform DCDA deposition at each deposition cycle. Our optical spectroscopic analysis indicates that carboxylate-zirconium interlinking chemistry is robust. To explain the disorganization in the alkyl portion of PDCDA multilayer films, we propose carboxylate-zirconium interlinkages act as “locks” in between PDCDA layers which restrict the movement of alkyl portion in the films. Because of this locking, the induced-stresses in the polymer chains can not be efficiently relieved. Our ionic resistance data from I–V analysis correlate well with calculated resistance at smaller number of PDCDA layers but significantly deviated for thicker PDCDA nanotubes. These differences were attributed to ion-blocking because some of the PDCDA nanotubes were totally closed and the nonohmic and permselective ionic behaviors when the diameter of the pores approaches the double-layer thickness of the solution inside of the nanotubes. PMID:18823090

  6. Silver nanoparticles-decorated polyphosphazene nanotubes: synthesis and applications

    NASA Astrophysics Data System (ADS)

    Wang, Minghuan; Fu, Jianwei; Huang, Dandan; Zhang, Chao; Xu, Qun

    2013-08-01

    Herein, we report the preparation of poly (cyclotriphosphazene-co-4,4'-sulfonyldiphenol) (PZS) nanotubes decorated with Ag nanoparticles (NPs). The PZS nanotubes have been synthesized firstly via an in situ template approach, and then Ag nanoparticles were prepared via in situ reduction of AgNO3 with NaBH4 as the reductant, supported on the surface of the PZS nanotubes. The as-obtained PZS nanotubes and PZS@Ag NPs composites were characterized by means of Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) equipped with energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), atomic absorption spectroscopy (AAS), thermogravimetric analysis (TGA), and UV-vis spectroscopy. Characterization results showed that Ag NPs with good dispersibility were well anchored onto the surface of the PZS nanotubes with superior thermal stability. In addition, the catalytic activities and reusability of these composites were investigated by employing the reduction of 4-nitrophenol (4-NP) into 4-aminophenol (4-AP) by NaBH4 as a model reaction.

  7. Physically unclonable cryptographic primitives using self-assembled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Hu, Zhaoying; Comeras, Jose Miguel M. Lobez; Park, Hongsik; Tang, Jianshi; Afzali, Ali; Tulevski, George S.; Hannon, James B.; Liehr, Michael; Han, Shu-Jen

    2016-06-01

    Information security underpins many aspects of modern society. However, silicon chips are vulnerable to hazards such as counterfeiting, tampering and information leakage through side-channel attacks (for example, by measuring power consumption, timing or electromagnetic radiation). Single-walled carbon nanotubes are a potential replacement for silicon as the channel material of transistors due to their superb electrical properties and intrinsic ultrathin body, but problems such as limited semiconducting purity and non-ideal assembly still need to be addressed before they can deliver high-performance electronics. Here, we show that by using these inherent imperfections, an unclonable electronic random structure can be constructed at low cost from carbon nanotubes. The nanotubes are self-assembled into patterned HfO2 trenches using ion-exchange chemistry, and the width of the trench is optimized to maximize the randomness of the nanotube placement. With this approach, two-dimensional (2D) random bit arrays are created that can offer ternary-bit architecture by determining the connection yield and switching type of the nanotube devices. As a result, our cryptographic keys provide a significantly higher level of security than conventional binary-bit architecture with the same key size.

  8. Physically unclonable cryptographic primitives using self-assembled carbon nanotubes.

    PubMed

    Hu, Zhaoying; Comeras, Jose Miguel M Lobez; Park, Hongsik; Tang, Jianshi; Afzali, Ali; Tulevski, George S; Hannon, James B; Liehr, Michael; Han, Shu-Jen

    2016-06-01

    Information security underpins many aspects of modern society. However, silicon chips are vulnerable to hazards such as counterfeiting, tampering and information leakage through side-channel attacks (for example, by measuring power consumption, timing or electromagnetic radiation). Single-walled carbon nanotubes are a potential replacement for silicon as the channel material of transistors due to their superb electrical properties and intrinsic ultrathin body, but problems such as limited semiconducting purity and non-ideal assembly still need to be addressed before they can deliver high-performance electronics. Here, we show that by using these inherent imperfections, an unclonable electronic random structure can be constructed at low cost from carbon nanotubes. The nanotubes are self-assembled into patterned HfO2 trenches using ion-exchange chemistry, and the width of the trench is optimized to maximize the randomness of the nanotube placement. With this approach, two-dimensional (2D) random bit arrays are created that can offer ternary-bit architecture by determining the connection yield and switching type of the nanotube devices. As a result, our cryptographic keys provide a significantly higher level of security than conventional binary-bit architecture with the same key size. PMID:26900757

  9. Anomalous aharonov-bohm gap oscillations in carbon nanotubes.

    PubMed

    Sangalli, Davide; Marini, Andrea

    2011-10-12

    The gap oscillations caused by a magnetic flux penetrating a carbon nanotube represent one of the most spectacular observations of the Aharonov-Bohm effect at the nanoscale. Our understanding of this effect is, however, based on the assumption that the electrons are strictly confined on the tube surface, on trajectories that are not modified by curvature effects. Using an ab initio approach based on density functional theory, we show that this assumption fails at the nanoscale inducing important corrections to the physics of the Aharonov-Bohm effect. Curvature effects and electronic density that is spilled out of the nanotube surface are shown to break the periodicity of the gap oscillations. We predict the key phenomenological features of this anomalous Aharonov-Bohm effect in semiconductive and metallic tubes and the existence of a large metallic phase in the low flux regime of multiwalled nanotubes, also suggesting possible experiments to validate our results. PMID:21805987

  10. Symmetry-, time-, and temperature-dependent strength of carbon nanotubes

    PubMed Central

    Dumitrica, Traian; Hua, Ming; Yakobson, Boris I.

    2006-01-01

    Although the strength of carbon nanotubes has been of great interest, their ideal value has remained elusive both experimentally and theoretically. Here, we present a comprehensive analysis of underlying atomic mechanisms and evaluate the yield strain for arbitrary nanotubes at realistic conditions. For this purpose, we combine detailed quantum mechanical computations of failure nucleation and transition-state barriers with the probabilistic approach of the rate theory. The numerical results are then summarized in a concise set of equations for the breaking strain. We reveal a competition between two alternative routes of brittle bond breaking and plastic relaxation, determine the domains of their dominance, and map the nanotube strength as a function of chiral symmetry, tensile test time, and temperature. PMID:16581906

  11. Integrating Carbon Nanotubes For Atomic Force Microscopy Imaging Applications

    NASA Technical Reports Server (NTRS)

    Ye, Qi; Cassell, Alan M.; Liu, Hongbing; Han, Jie; Meyyappan, Meyya

    2004-01-01

    Carbon nanotube (CNT) related nanostructures possess remarkable electrical, mechanical, and thermal properties. To produce these nanostructures for real world applications, a large-scale controlled growth of carbon nanotubes is crucial for the integration and fabrication of nanodevices and nanosensors. We have taken the approach of integrating nanopatterning and nanomaterials synthesis with traditional silicon micro fabrication techniques. This integration requires a catalyst or nanomaterial protection scheme. In this paper, we report our recent work on fabricating wafer-scale carbon nanotube AFM cantilever probe tips. We will address the design and fabrication considerations in detail, and present the preliminary scanning probe test results. This work may serve as an example of rational design, fabrication, and integration of nanomaterials for advanced nanodevice and nanosensor applications.

  12. Chiral phosphorus nanotubes: structure, bonding, and electronic properties.

    PubMed

    Fernández-Escamilla, H N; Quijano-Briones, J J; Tlahuice-Flores, A

    2016-05-14

    The study of black phosphorus nanotubes (PNTs) had been devoted to zigzag and armchair structures, with no consideration of chiral structures to date. In this communication, we studied the structural and electronic (band structure) properties of chiral nanotubes using a periodic plane wave-pseudopotential approach. We found that some chiral nanotubes display similar bandgaps and binding energies per atom (BEA) as armchair PNTs and Born-Oppenheimer molecular dynamics (BOMD) calculations attest their thermal stability. Interestingly, we determined that the bandgap is tuned by varying the PNTs chirality and it is not related to their diameters. This feature can be exploited in optical and electronic applications wherein a direct and sizable bandgap is required. PMID:27094567

  13. Self-assembly of carbon nanotubes and antibodies on tumours for targeted amplified delivery

    NASA Astrophysics Data System (ADS)

    Mulvey, J. Justin; Villa, Carlos H.; McDevitt, Michael R.; Escorcia, Freddy E.; Casey, Emily; Scheinberg, David A.

    2013-10-01

    Single-walled carbon nanotubes (SWNTs) can deliver imaging agents or drugs to tumours and offer significant advantages over approaches based on antibodies or other nanomaterials. In particular, the nanotubes can carry a substantial amount of cargo (100 times more than a monoclonal antibody), but can still be rapidly eliminated from the circulation by renal filtration, like a small molecule, due to their high aspect ratio. Here we show that SWNTs can target tumours in a two-step approach in which nanotubes modified with morpholino oligonucleotide sequences bind to cancer cells that have been pretargeted with antibodies modified with oligonucleotide strands complementary to those on the nanotubes. The nanotubes can carry fluorophores or radioisotopes, and are shown to selectively bind to cancer cells in vitro and in tumour-bearing xenografted mice. The binding process is also found to lead to antigen capping and internalization of the antibody-nanotube complexes. The nanotube conjugates were labelled with both alpha-particle and gamma-ray emitting isotopes, at high specific activities. Conjugates labelled with alpha-particle-generating 225Ac were found to clear rapidly, thus mitigating radioisotope toxicity, and were shown to be therapeutically effective in vivo.

  14. Self-assembly of carbon nanotubes and antibodies on tumours for targeted, amplified delivery

    PubMed Central

    Mulvey, J. Justin; Villa, Carlos H.; McDevitt, Michael R.; Escorcia, Freddy E.; Casey, Emily; Scheinberg, David A.

    2013-01-01

    Single-walled carbon nanotubes (SWNTs) can deliver imaging agents or drugs to tumours and offer significant advantages over approaches based on antibodies or other nanomaterials. In particular, the nanotubes can carry a substantial amount of cargo (100 times more than a monoclonal antibody), but can still be rapidly eliminated from circulation by renal filtration, like a small molecule, due to their high aspect ratio. Here we show that SWNTs can target tumours in a two-step approach in which nanotubes modified with morpholino oligonucleotide sequences bind to cancer cells that have been pre-targeted with antibodies modified with oligonucleotide strands complementary to those on the nanotubes. The nanotubes can carry fluorophores or radioisotopes, and were shown to selectively bind to cancer cells in vitro and in tumour-bearing xenografted mice. The binding process is also found to lead to antigen capping and internalization of the antibody/nanotube complexes. The nanotube conjugates were labelled with both alpha-particle and gamma-ray emitting isotopes, at high specific activities. Conjugates labelled with alpha-particle generating 225Ac were found to clear rapidly, thus mitigating radioisotope toxicity, and were shown to be therapeutically effective in vivo. PMID:24077028

  15. Ultrastrong, Stiff and Multifunctional Carbon Nanotube Composites

    SciTech Connect

    Wang, Xin; Yong, Zhenzhong; Li, Qingwen; Bradford, Philip D.; Liu, Wei; Tucker, Dennis S.; Cai, Wei; Wang, Hsin; Yuan, Fuh-Gwo; Zhu, Yuntian

    2012-01-01

    Carbon nanotubes (CNTs) are an order of magnitude stronger than any current engineering fiber. However, for the past two decades it has been a challenge to utilize their reinforcement potential in composites. Here we report CNT composites with unprecedented multifunctionalities, including record high strength (3.8 GPa), Young s modulus (293 GPa), electrical conductivity (1230 S cm-1) and thermal conductivity (41 W m-1 K-1). These superior properties are derived from the long length, high volume fraction, good alignment and reduced waviness of the CNTs, which were produced by a novel processing approach that can be easily scaled up for industrial production.

  16. Carbon Nanotube Based Molecular Electronics

    NASA Technical Reports Server (NTRS)

    Srivastava, Deepak; Saini, Subhash; Menon, Madhu

    1998-01-01

    Carbon nanotubes and the nanotube heterojunctions have recently emerged as excellent candidates for nanoscale molecular electronic device components. Experimental measurements on the conductivity, rectifying behavior and conductivity-chirality correlation have also been made. While quasi-one dimensional simple heterojunctions between nanotubes with different electronic behavior can be generated by introduction of a pair of heptagon-pentagon defects in an otherwise all hexagon graphene sheet. Other complex 3- and 4-point junctions may require other mechanisms. Structural stability as well as local electronic density of states of various nanotube junctions are investigated using a generalized tight-binding molecular dynamics (GDBMD) scheme that incorporates non-orthogonality of the orbitals. The junctions investigated include straight and small angle heterojunctions of various chiralities and diameters; as well as more complex 'T' and 'Y' junctions which do not always obey the usual pentagon-heptagon pair rule. The study of local density of states (LDOS) reveal many interesting features, most prominent among them being the defect-induced states in the gap. The proposed three and four pointjunctions are one of the smallest possible tunnel junctions made entirely of carbon atoms. Furthermore the electronic behavior of the nanotube based device components can be taylored by doping with group III-V elements such as B and N, and BN nanotubes as a wide band gap semiconductor has also been realized in experiments. Structural properties of heteroatomic nanotubes comprising C, B and N will be discussed.

  17. Carbon Nanotubes for Polymer Photovoltaics

    NASA Astrophysics Data System (ADS)

    Anctil, Annick; Dileo, Roberta; Schauerman, Chris; Landi, Brian; Raffaelle, Ryne

    2007-03-01

    Carbon nanotubes are being investigated for optical absorption, exciton dissociation, and carrier transport in polymer photovoltaic devices. In the present work, single wall carbon nanotubes (SWNTs) were synthesized by an Alexandrite pulsed laser vaporization reactor at standard conditions and purified based upon our previously reported TOP procedure. The SWNTs were dispersed in polymer composites for pure MEH-PPV, pure P3HT, and [C60]-PCBM-P3HT (1:1 by weight) as a function of nanotube weight loading (0.1 -- 5% w/w). The AM0 current-voltage measurements for structures sandwiched between PEDOT/PSS coated ITO substrates and an evaporated aluminum contact demonstrate the dramatic effect of SWNT content on the short circuit current density, with conversions efficiencies consistently greater than 1%. The temperature coefficient for nanotube-containing polymer photovoltaics has been compared to conventional PCBM-P3HT devices, and the general relationship of increasing efficiency with increasing temperature is observed. However, the necessity to control nanotube percolation to prevent device shunting has led to recent developments which focus on controlling nanotube length through oxidative cutting, the deposition of intrinsic polymer layers, and the use of aligned carbon nanotube arrays for preferential charge transport.

  18. Supported lipid bilayer/carbon nanotube hybrids

    NASA Astrophysics Data System (ADS)

    Zhou, Xinjian; Moran-Mirabal, Jose M.; Craighead, Harold G.; McEuen, Paul L.

    2007-03-01

    Carbon nanotube transistors combine molecular-scale dimensions with excellent electronic properties, offering unique opportunities for chemical and biological sensing. Here, we form supported lipid bilayers over single-walled carbon nanotube transistors. We first study the physical properties of the nanotube/supported lipid bilayer structure using fluorescence techniques. Whereas lipid molecules can diffuse freely across the nanotube, a membrane-bound protein (tetanus toxin) sees the nanotube as a barrier. Moreover, the size of the barrier depends on the diameter of the nanotube-with larger nanotubes presenting bigger obstacles to diffusion. We then demonstrate detection of protein binding (streptavidin) to the supported lipid bilayer using the nanotube transistor as a charge sensor. This system can be used as a platform to examine the interactions of single molecules with carbon nanotubes and has many potential applications for the study of molecular recognition and other biological processes occurring at cell membranes.

  19. Functionalization of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Khare, Bishun N. (Inventor); Meyyappan, Meyya (Inventor)

    2007-01-01

    Method and system for functionalizing a collection of carbon nanotubes (CNTs). A selected precursor gas (e.g., H2, or F2, or CnHm) is irradiated to provide a cold plasma of selected target particles, such as atomic H or F, in a first chamber. The target particles are directed toward an array of CNTs located in a second chamber while suppressing transport of ultraviolet radiation to the second chamber. A CNT array is functionalized with the target particles, at or below room temperature, to a point of saturation, in an exposure time interval no longer than about 30 sec.

  20. Functionalization of carbon nanotubes

    NASA Technical Reports Server (NTRS)

    Khare, Bishun N. (Inventor); Meyyappan, Meyya (Inventor)

    2007-01-01

    Method and system for functionalizing a collection of carbon nanotubes (CNTs). A selected precursor gas (e.g., H.sub.2 or F.sub.2 or C.sub.nH.sub.m) is irradiated to provide a cold plasma of selected target particles, such as atomic H or F, in a first chamber. The target particles are directed toward an array of CNTs located in a second chamber while suppressing transport of ultraviolet radiation to the second chamber. A CNT array is functionalized with the target particles, at or below room temperature, to a point of saturation, in an exposure time interval no longer than about 30 sec.

  1. Carbon Nanotube Interconnect

    NASA Technical Reports Server (NTRS)

    Li, Jun (Inventor); Meyyappan, Meyya (Inventor)

    2006-01-01

    Method and system for fabricating an electrical interconnect capable of supporting very high current densities ( 10(exp 6)-10(exp 10) Amps/sq cm), using an array of one or more carbon nanotubes (CNTs). The CNT array is grown in a selected spaced apart pattern, preferably with multi-wall CNTs, and a selected insulating material, such as SiOw, or SiuNv is deposited using CVD to encapsulate each CNT in the array. An exposed surface of the insulating material is planarized to provide one or more exposed electrical contacts for one or more CNTs.

  2. Fabrication of titanium dioxide nanotube arrays using organic electrolytes

    NASA Astrophysics Data System (ADS)

    Yoriya, Sorachon

    to ~2 microm. In comparison to DMSO electrolyte, the electrochemical anodization rates are relatively slower in DEG electrolyte; as a result, the nanotube length is typically less than 10 microm. Pore size of nanotubes grown in DEG has been extended from 150 nm up to approximately 400 nm. The approach to pore widening could be achieved by using a specific condition of low HF concentration and prolonged anodization time. The study of evolution of nanotubes grown in DEG electrolytes showed that a fibrous layer was formed in the early growth stages and then was chemically and gradually removed after a long duration, leaving behind the nanotubes with large pore size. In DEG electrolyte, the closer spacing between Ti and Pt electrodes resulted in the larger nanotube morphological parameters due to the enhanced electrode kinetics facilitating the electrode reactions. Furthermore, this dissertation showed possibilities to crystallize the titania nanotube array films at room temperature via anodization in either DMSO or DEG electrolytes. The partially crystallized films could be achieved specifically in the optimum slow growth process conditions. Due to partial crystallization of the as-anodized samples, the high temperature annealing study revealed that the temperatures of phase transformation are 260 ºC and 430°C for respectively amorphous to anatase and anatase to rutile, which are accounted as the lowest phase transformation temperatures reported to date (2010). Finally, the photoelectrochemical properties of the DMSO fabricated nanotubes were investigated. The maximum photocurrent density of ~ 11 mA cm--2 was achieved by using the 46-microm long nanotube array sample with completely open pores, and photoconversion efficiencies of 5.425 % (+/- 0.087) (under UV light) and 0.197 % (+/- 0.001) (under solar spectrum AM 1.5) have been demonstrated. Biomedical applications of the DEG fabricated nanotube arrays films such as blood clotting, hemocompatibility, and drug

  3. Template based synthesis of gold nanotubes using biologically synthesized gold nanoparticles.

    PubMed

    Ballabh, R; Nara, S

    2015-12-01

    Reliable experimental protocols using green technologies to synthesize metallic nanostructures widen their applications, both biological as well as biomedical. Here, we describe a method for synthesizing gold nanotubes using biologically synthesized gold nanoparticles in a template based approach. E. coli DH5α was used as bionanofactory to synthesize gold nanoparticles. These nanoparticles were then deposited on sodium sulfate (Na2SO4) nanowires which were employed as sacrificial template for gold nanotube (Au-NT) formation. The gold nanoparticles, sodium sulphate nanowires and gold nanotubes were appropriately characterized using transmission electron microscopy. The TEM results showed that the average diameter of gold nanotubes was 72 nm and length up to 4-7 μm. The method discussed herein is better than other reported conventional chemical synthesis approaches as it uses biologically synthesized gold nanoparticles, and does not employ any harsh conditions/solvents for template removal which makes it a clean and ecofriendly method. PMID:26742328

  4. NASA Innovation Builds Better Nanotubes

    NASA Technical Reports Server (NTRS)

    2008-01-01

    Nanotailor Inc., based in Austin, Texas, licensed Goddard Space Flight Center's unique single-walled carbon nanotube (SWCNT) fabrication process with plans to make high-quality, low-cost SWCNTs available commercially. Carbon nanotubes are being used in a wide variety of applications, and NASA's improved production method will increase their applicability in medicine, microelectronics, advanced materials, and molecular containment. Nanotailor built and tested a prototype based on Goddard's process, and is using this technique to lower the cost and improve the integrity of nanotubes, offering a better product for use in biomaterials, advanced materials, space exploration, highway and building construction, and many other applications.

  5. Carbon nanotubes in hyperthermia therapy

    PubMed Central

    Singh, Ravi; Torti, Suzy V.

    2013-01-01

    Thermal tumor ablation therapies are being developed with a variety of nanomaterials, including single-and multiwalled carbon nanotubes. Carbon nanotubes (CNTs) have attracted interest due to their potential for simultaneous imaging and therapy. In this review, we highlight in vivo applications of carbon nanotube-mediated thermal therapy (CNMTT) and examine the rationale for use of this treatment in recurrent tumors or those resistant to conventional cancer therapies. Additionally, we discuss strategies to localize and enhance the cancer selectivity of this treatment and briefly examine issues relating the toxicity and long term fate of CNTs. PMID:23933617

  6. Multiscale Modeling with Carbon Nanotubes

    SciTech Connect

    Maiti, A

    2006-02-21

    Technologically important nanomaterials come in all shapes and sizes. They can range from small molecules to complex composites and mixtures. Depending upon the spatial dimensions of the system and properties under investigation computer modeling of such materials can range from equilibrium and nonequilibrium Quantum Mechanics, to force-field-based Molecular Mechanics and kinetic Monte Carlo, to Mesoscale simulation of evolving morphology, to Finite-Element computation of physical properties. This brief review illustrates some of the above modeling techniques through a number of recent applications with carbon nanotubes: nano electromechanical sensors (NEMS), chemical sensors, metal-nanotube contacts, and polymer-nanotube composites.

  7. Tunable synthesis of copper nanotubes

    NASA Astrophysics Data System (ADS)

    Kaniukov, E.; Kozlovsky, A.; Shlimas, D.; Yakimchuk, D.; Zdorovets, M.; Kadyrzhanov, K.

    2016-02-01

    Simple method of tunable synthesis of copper nanotubes based on template synthesis was developed. A comprehensive study of the structural, morphological and electrical characteristics of the obtained nanostructures was carried out. Characterization of structural features was made by methods of scanning electron microscopy, energy dispersive spectroscopy and X-ray diffractometry analysis. Evaluation of wall thickness is made by methods of gas permeability. Electrical conductivity of nanotubes was define in the study of their current-voltage characteristics. The possibility to control of copper nanotubes physical properties by variation of the deposition parameters was shown.

  8. Electronic properties of nanotube junctions

    NASA Astrophysics Data System (ADS)

    Lambin, Ph.; Meunier, V.

    1998-08-01

    The possibility of realizing junctions between two different nanotubes has recently attracted a great interest, even though much remains to be done for putting this idea in concrete form. Pentagon-heptagon pair defects in the otherwise perfect graphitic network make such connections possible, with virtually infinite varieties. In this paper, the literature devoted to nanotube junctions is briefly reviewed. A special emphasize is put on the electronic properties of C nanotube junctions, together with an indication on how their current-voltage characteristics may look like.

  9. Method of manufacturing carbon nanotubes

    NASA Technical Reports Server (NTRS)

    Benavides, Jeanette M. (Inventor); Leidecker, Henning W. (Inventor); Frazier, Jeffrey (Inventor)

    2004-01-01

    A process for manufacturing carbon nanotubes, including a step of inducing electrical current through a carbon anode and a carbon cathode under conditions effective to produce the carbon nanotubes, wherein the carbon cathode is larger than the carbon anode. Preferably, a welder is used to induce the electrical current via an arc welding process. Preferably, an exhaust hood is placed on the anode, and the process does not require a closed or pressurized chamber. The process provides high-quality, single-walled carbon nanotubes, while eliminating the need for a metal catalyst.

  10. Carbon nanotube core graphitic shell hybrid fibers.

    PubMed

    Hahm, Myung Gwan; Lee, Jae-Hwang; Hart, Amelia H C; Song, Sung Moo; Nam, Jaewook; Jung, Hyun Young; Hashim, Daniel Paul; Li, Bo; Narayanan, Tharangattu N; Park, Chi-Dong; Zhao, Yao; Vajtai, Robert; Kim, Yoong Ahm; Hayashi, Takuya; Ku, Bon-Cheol; Endo, Morinobu; Barrera, Enrique; Jung, Yung Joon; Thomas, Edwin L; Ajayan, Pulickel M

    2013-12-23

    A carbon nanotube yarn core graphitic shell hybrid fiber was fabricated via facile heat treatment of epoxy-based negative photoresist (SU-8) on carbon nanotube yarn. The effective encapsulation of carbon nanotube yarn in carbon fiber and a glassy carbon outer shell determines their physical properties. The higher electrical conductivity (than carbon fiber) of the carbon nanotube yarn overcomes the drawbacks of carbon fiber/glassy carbon, and the better properties (than carbon nanotubes) of the carbon fiber/glassy carbon make up for the lower thermal and mechanical properties of the carbon nanotube yarn via synergistic hybridization without any chemical doping and additional processes. PMID:24224730

  11. Bending fracture in carbon nanotubes.

    PubMed

    Kuo, Wen-Shyong; Lu, Hsin-Fang

    2008-12-10

    A novel approach was adopted to incur bending fracture in carbon nanotubes (CNTs). Expanded graphite (EG) was made by intercalating and exfoliating natural graphite flakes. The EG was deposited with nickel particles, from which CNTs were grown by chemical vapor deposition. The CNTs were tip-grown, and their roots were fixed on the EG flakes. The EG flakes were compressed, and many CNTs on the surface were fragmented due to the compression-induced bending. Two major modes of the bending fracture were observed: cone-shaped and shear-cut. High-resolution scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to examine the crack growth within the graphene layers. The bending fracture is characterized by two-region crack growth. An opening crack first appears around the outer-tube due to the bending-induced tensile stress. The crack then branches to grow along an inclined direction toward the inner-tube due to the presence of the shear stress in between graphene layers. An inner-tube pullout with inclined side surface is formed. The onset and development of the crack in these two regions are discussed. PMID:21730690

  12. Carbon nanotube based photocathodes

    NASA Astrophysics Data System (ADS)

    Hudanski, Ludovic; Minoux, Eric; Gangloff, Laurent; Teo, Kenneth B. K.; Schnell, Jean-Philippe; Xavier, Stephane; Robertson, John; Milne, William I.; Pribat, Didier; Legagneux, Pierre

    2008-03-01

    This paper describes a novel photocathode which is an array of vertically aligned multi-walled carbon nanotubes (MWCNTs), each MWCNT being associated with one p-i-n photodiode. Unlike conventional photocathodes, the functions of photon-electron conversion and subsequent electron emission are physically separated. Photon-electron conversion is achieved with p-i-n photodiodes and the electron emission occurs from the MWCNTs. The current modulation is highly efficient as it uses an optically controlled reconfiguration of the electric field at the MWCNT locations. Such devices are compatible with high frequency and very large bandwidth operation and could lead to their application in compact, light and efficient microwave amplifiers for satellite telecommunication. To demonstrate this new photocathode concept, we have fabricated the first carbon nanotube based photocathode using silicon p-i-n photodiodes and MWCNT bunches. Using a green laser, this photocathode delivers 0.5 mA with an internal quantum efficiency of 10% and an ION/IOFF ratio of 30.

  13. Studies of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Caneba, Gerard T.

    2005-01-01

    The fellowship experience for this summer for 2004 pertains to carbon nanotube coatings for various space-related applications. They involve the following projects: (a) EMI protection films from HiPco-polymers, and (b) Thermal protection nanosilica materials. EMI protection films are targeted to be eventually applied onto casings of laptop computers. These coatings are composites of electrically-conductive SWNTs and compatible polymers. The substrate polymer will be polycarbonate, since computer housings are typically made of carbon composites of this type of polymer. A new experimental copolymer was used last year to generate electrically-conductive and thermal films with HiPco at 50/50 wt/wt composition. This will be one of the possible formulations. Reference films will be base polycarbonate and neat HiPco onto polycarbonate films. Other coating materials that will be tried will be based on HiPco composites with commercial enamels (polyurethane, acrylic, polyester), which could be compatible with the polycarbonate substrate. Nanosilica fibers are planned for possible use as thermal protection tiles on the shuttle orbiter. Right now, microscale silica is used. Going to the nanoscale will increase the surface-volume-per-unit-area of radiative heat dissipation. Nanoscale carbon fibers/nanotubes can be used as templates for the generation of nanosilica. A sol-gel operation is employed for this purpose.

  14. Carbon nanotube array actuators

    NASA Astrophysics Data System (ADS)

    Geier, S.; Mahrholz, T.; Wierach, P.; Sinapius, M.

    2013-09-01

    Experimental investigations of highly vertically aligned carbon nanotubes (CNTs), also known as CNT-arrays, are the main focus of this paper. The free strain as result of an active material behavior is analyzed via a novel experimental setup. Previous test experiences of papers made of randomly oriented CNTs, also called Bucky-papers, reveal comparably low free strain. The anisotropy of aligned CNTs promises better performance. Via synthesis techniques like chemical vapor deposition (CVD) or plasma enhanced CVD (PECVD), highly aligned arrays of multi-walled carbon nanotubes (MWCNTs) are synthesized. Two different types of CNT-arrays are analyzed, morphologically first, and optically tested for their active characteristics afterwards. One type of the analyzed arrays features tube lengths of 750-2000 μm with a large variety of diameters between 20 and 50 nm and a wave-like CNT-shape. The second type features a maximum, almost uniform, length of 12 μm and a constant diameter of 50 nm. Different CNT-lengths and array types are tested due to their active behavior. As result of the presented tests, it is reported that the quality of orientation is the most decisive property for excellent active behavior. Due to their alignment, CNT-arrays feature the opportunity to clarify the actuation mechanism of architectures made of CNTs.

  15. Carbon Nanotubes as Thermionic Emitters

    NASA Astrophysics Data System (ADS)

    Loutfy, R. O.; Samandi, M.; Moravsky, A.; Strange, S.

    2004-02-01

    Thermionic converters are an interesting option for lightweight and long-life power generators due to a number of compelling advantages, including all solid construction, no moving parts, and waste heat rejection at high temperature. An experimental set up has been built that allows the screening of thermionic coatings and new nanomaterials from room temperature to 2000 K in high vacuum and at gap sizes as small as 1 μm. A new class of very high temperature compatible materials, carbon nanotubes, has been investigated for their performance as cathodes. Seven different types of carbon nanotubes have been screened as thermionic emitter cathodes and compared to tungsten and nitrogen doped diamond. It has been found that some carbon nanotubes combine excellent temperature stability with good thermal emission performance. Yet, other carbon nanotubes exhibited exceptional combined thermal and field enhanced emission performance.

  16. Carbon Nanotube-Nanocrystal Heterostructures

    SciTech Connect

    Peng, X.; Wong, S.

    2009-04-01

    The importance of generating carbon nanotube-nanoparticle heterostructures is that these composites ought to take advantage of and combine the unique physical and chemical properties of both carbon nanotubes and nanoparticles in one discrete structure. These materials have potential applicability in a range of diverse fields spanning heterogeneous catalysis to optoelectronic device development, of importance to chemists, physicists, materials scientists, and engineers. In this critical review, we present a host of diverse, complementary strategies for the reliable synthesis of carbon nanotube-nanoparticle heterostructures using both covalent as well as non-covalent protocols, incorporating not only single-walled and multi-walled carbon nanotubes but also diverse classes of metallic and semiconducting nanoparticles.

  17. Elastic modulus of viral nanotubes

    NASA Astrophysics Data System (ADS)

    Zhao, Yue; Ge, Zhibin; Fang, Jiyu

    2008-09-01

    We report an experimental and theoretical study of the radial elasticity of tobacco mosaic virus (TMV) nanotubes. An atomic force microscope tip is used to apply small radial indentations to deform TMV nanotubes. The initial elastic response of TMV nanotubes can be described by finite-element analysis in 5nm indentation depths and Hertz theory in 1.5nm indentation depths. The derived radial Young’s modulus of TMV nanotubes is 0.92±0.15GPa from finite-element analysis and 1.0±0.2GPa from the Hertz model, which are comparable with the reported axial Young’s modulus of 1.1GPa [Falvo , Biophys. J. 72, 1396 (1997)].

  18. Method for producing carbon nanotubes

    DOEpatents

    Phillips, Jonathan; Perry, William L.; Chen, Chun-Ku

    2006-02-14

    Method for producing carbon nanotubes. Carbon nanotubes were prepared using a low power, atmospheric pressure, microwave-generated plasma torch system. After generating carbon monoxide microwave plasma, a flow of carbon monoxide was directed first through a bed of metal particles/glass beads and then along the outer surface of a ceramic tube located in the plasma. As a flow of argon was introduced into the plasma through the ceramic tube, ropes of entangled carbon nanotubes, attached to the surface of the tube, were produced. Of these, longer ropes formed on the surface portion of the tube located in the center of the plasma. Transmission electron micrographs of individual nanotubes revealed that many were single-walled.

  19. Carbon nanotubes: artificial nanomaterials to engineer single neurons and neuronal networks.

    PubMed

    Fabbro, Alessandra; Bosi, Susanna; Ballerini, Laura; Prato, Maurizio

    2012-08-15

    In the past decade, nanotechnology applications to the nervous system have often involved the study and the use of novel nanomaterials to improve the diagnosis and therapy of neurological diseases. In the field of nanomedicine, carbon nanotubes are evaluated as promising materials for diverse therapeutic and diagnostic applications. Besides, carbon nanotubes are increasingly employed in basic neuroscience approaches, and they have been used in the design of neuronal interfaces or in that of scaffolds promoting neuronal growth in vitro. Ultimately, carbon nanotubes are thought to hold the potential for the development of innovative neurological implants. In this framework, it is particularly relevant to document the impact of interfacing such materials with nerve cells. Carbon nanotubes were shown, when modified with biologically active compounds or functionalized in order to alter their charge, to affect neurite outgrowth and branching. Notably, purified carbon nanotubes used as scaffolds can promote the formation of nanotube-neuron hybrid networks, able per se to affect neuron integrative abilities, network connectivity, and synaptic plasticity. We focus this review on our work over several years directed to investigate the ability of carbon nanotube platforms in providing a new tool for nongenetic manipulations of neuronal performance and network signaling. PMID:22896805

  20. Half-Metallic Properties of Single-Walled Polymeric Manganese Phthalocyanine Nanotubes

    PubMed Central

    Jiang, Hongbin; Bai, Meilin; Wei, Peng; Sun, Lili; Shen, Ziyong; Hou, Shimin

    2012-01-01

    We present a theoretical study of the electronic and magnetic properties of single-walled manganese phthalocyanine (MnPc) nanotubes which can be thought of as rolled-up ribbons of the two-dimensional (2D) polymeric MnPc sheet. Our density functional theory calculations show that all of the MnPc nanotubes investigated here are half-metals with 100% spin polarization around the Fermi level. Following the increase of the tube diameter, the number of spin-down energy bands of MnPc nanotubes is always increased while the spin-up band gap of MnPc nanotubes approaches that of the 2D MnPc sheet in an oscillatory manner. Because the half-metallic character of MnPc nanotubes is deeply rooted in the distribution of electrons in the energy bands dominated by the Mn 3d atomic orbitals, adsorption of CO molecules on the Mn ions leads to a redistribution of electrons in the Mn 3d orbitals and thus can tune precisely the spin state and electronic transport properties of MnPc nanotubes, demonstrating promising applications of MnPc nanotubes in future molecular spintronics and single-molecule sensors. PMID:23012498

  1. Optical visualization of individual ultralong carbon nanotubes by chemical vapour deposition of titanium dioxide nanoparticles.

    PubMed

    Zhang, Rufan; Zhang, Yingying; Zhang, Qiang; Xie, Huanhuan; Wang, Haidong; Nie, Jingqi; Wen, Qian; Wei, Fei

    2013-01-01

    Direct visualization and manipulation of individual carbon nanotubes in ambient conditions is of great significance for their characterizations and applications. However, the observation of individual carbon nanotubes usually requires electron microscopes under high vacuum. Optical microscopes are much more convenient to be used, yet their resolution is low. Here we realize the visualization and manipulation of individual ultralong carbon nanotubes under optical microscopes by deposition of TiO2 nanoparticles on them. The strong scattering of TiO2 nanoparticles to visible light renders them visible by optical microscopes. Micro-Raman-spectroscopy measurement of individual carbon nanotubes is greatly facilitated by their optical visualization. With the assistance of TiO2 nanoparticles, individual carbon nanotubes can be easily manipulated under an optical microscope at macroscopic scale and in ambient conditions. Based on our approach, various manipulation of ultralong carbon nanotubes, including cutting, transfer, fabrication of structures/devices and pulling out inner shells of multiwalled carbon nanotubes, are demonstrated. PMID:23591894

  2. P- and PN-Doped Nanotubes for Ultrasensitive and Selective Molecular Detection

    SciTech Connect

    Cruz Silva, Eduardo; Terrones Maldonado, Humberto; Terrones Maldonado, Mauricio; Charlier, Jean Christophe; Meunier, Vincent; Sumpter, Bobby G; Munoz-Sandoval, Emilio; Lopez, Florentino

    2010-01-01

    A first-principles approach is used to establish that substitutional phosphorus atoms strongly modify the chemical properties of the surface of carbon nanotubes, creating highly-localized sites with specific affinity towards acceptor molecules. Phosphorus-nitrogen co-dopants have a similar effect for acceptor molecules, but the P-N bond can also accept charge, resulting in affinity towards donor molecules. This molecular selectivity is illustrated in CO and NH3 adsorbed on PN doped nanotubes, O2 on P-doped nanotubes, and NO2 and SO2 on both P- and PN-doped nanotubes. The adsorption of different chemical species onto the doped nanotubes modifies the dopant-induced localized states, which subsequently alter electronic conductance. Although SO2 and CO adsorption cause minor shifts in electronic conductance; NH3, NO2, and O2 adsorptions induce the suppression of a conductance dip. Conversely, the adsorption of NO2 on PN-doped nanotubes is accompanied with the appearance of an additional dip in conductance, correlated with a shift of the existing ones. Overall these changes in electric conductance provide an efficient way to detect selectively the presence of specific molecules. Additionally, the high oxidation potential of the P-doped nanotubes makes them good candidates for electrode materials in hydrogen fuel cells.

  3. Phosphorus and phosphorus nitrogen doped carbon nanotubes for ultrasensitive and selective molecular detection

    SciTech Connect

    Cruz Silva, Eduardo; Lopez, Florentino; Munoz-Sandoval, Emilio; Sumpter, Bobby G; Terrones Maldonado, Humberto; Charlier, Jean Christophe; Meunier, Vincent; Terrones Maldonado, Mauricio

    2011-01-01

    A first-principles approach is used to establish that substitutional phosphorus atoms within carbon nanotubes strongly modify the chemical properties of the surface, thus creating highly localized sites with specific affinity towards acceptor molecules. Phosphorus nitrogen co-dopants within the tubes have a similar effect for acceptor molecules, but the P N bond can also accept charge, resulting in affinity towards donor molecules. This molecular selectivity is illustrated in CO and NH3 adsorbed on PN-doped nanotubes, O2 on P-doped nanotubes, and NO2 and SO2 on both P- and PN-doped nanotubes. The adsorption of different chemical species onto the doped nanotubes modifies the dopant-induced localized states, which subsequently alter the electronic conductance. Although SO2 and CO adsorptions cause minor shifts in electronic conductance, NH3, NO2, and O2 adsorptions induce the suppression of a conductance dip. Conversely, the adsorption of NO2 on PN-doped nanotubes is accompanied with the appearance of an additional dip in conductance, correlated with a shift of the existing ones. Overall these changes in electric conductance provide an efficient way to detect selectively the presence of specific molecules. Additionally, the high oxidation potential of the P-doped nanotubes makes them good candidates for electrode materials in hydrogen fuel cells.

  4. Molecular dynamics study of the stability of a carbon nanotube atop a catalytic nanoparticle

    NASA Astrophysics Data System (ADS)

    Verkhovtsev, Alexey V.; Schramm, Stefan; Solov'yov, Andrey V.

    2014-09-01

    The stability of a single-walled carbon nanotube placed on top of a catalytic nickel nanoparticle is investigated by means of molecular dynamics simulations. As a case study, we consider the (12,0) nanotube consisting of 720 carbon atoms and the icosahedral Ni309 cluster. An explicit set of constant-temperature simulations is performed in order to cover a broad temperature range from 400 to 1200 K, at which a successful growth of carbon nanotubes has been achieved experimentally by means of chemical vapor deposition. The stability of the system depending on parameters of the involved interatomic interactions is analyzed. It is demonstrated that different scenarios of the nanotube dynamics atop the nanoparticle are possible depending on the parameters of the Ni-C potential. When the interaction is weak the nanotube is stable and resembles its highly symmetric structure, while an increase of the interaction energy leads to the abrupt collapse of the nanotube in the initial stage of simulation. In order to validate the parameters of the Ni-C interaction utilized in the simulations, DFT calculations of the potential energy surface for carbon-nickel compounds are performed. The calculated dissociation energy of the Ni-C bond is in good agreement with the values, which correspond to the case of a stable and not deformed nanotube simulated within the MD approach.

  5. Selective functionalization of carbon nanotubes

    NASA Technical Reports Server (NTRS)

    Strano, Michael S. (Inventor); Usrey, Monica (Inventor); Barone, Paul (Inventor); Dyke, Christopher A. (Inventor); Tour, James M. (Inventor); Kittrell, W. Carter (Inventor); Hauge, Robert H. (Inventor); Smalley, Richard E. (Inventor)

    2009-01-01

    The present invention is directed toward methods of selectively functionalizing carbon nanotubes of a specific type or range of types, based on their electronic properties, using diazonium chemistry. The present invention is also directed toward methods of separating carbon nanotubes into populations of specific types or range(s) of types via selective functionalization and electrophoresis, and also to the novel compositions generated by such separations.

  6. PECVD Growth of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    McAninch, Ian; Arnold, James O. (Technical Monitor)

    2001-01-01

    Plasma enhanced chemical vapor deposition (PECVD), using inductively coupled plasma, has been used to grow carbon nanotubes (CNTs) and graphitic carbon fibers (GCF) on substrates sputtered with aluminum and iron catalyst. The capacitive plasma's power has been shown to cause a transition from nanotubes to nanofibers, depending on the strength of the plasma. The temperature, placement, and other factors have been shown to affect the height and density of the tube and fiber growth.

  7. Hemocompatibility of titania nanotube arrays.

    PubMed

    Smith, Barbara S; Yoriya, Sorachon; Grissom, Laura; Grimes, Craig A; Popat, Ketul C

    2010-11-01

    Hemocompatibility is a key consideration for the long-term success of blood contacting biomaterials; hence, there is a critical need to understand the physiological response elicited from blood/nano-biomaterial interactions. In this study, we have investigated the adsorption of key blood serum proteins, in vitro adhesion and activation of platelets, and clotting kinetics of whole blood on titania nanotube arrays. Previous studies have demonstrated improved mesenchymal stem cell functionality, osteoblast phenotypic behavior, localized drug delivery, and the production of endothelial cell ECM on titania nanotube arrays. Furthermore, these titania nanotube arrays have elicited minimal levels of monocyte activation and cytokine secretion, thus exhibiting a very low degree of immunogenicity. Titania nanotube arrays were fabricated using anodization technique and the surface morphology was examined through scanning electron microscopy (SEM). The crystalline phases were identified using glancing angled X-ray diffraction (GAXRD). Nanoindentation and scratch tests were used to characterize the mechanical properties of titania nanotube arrays. The adsorption of key blood proteins (albumin, fibrinogen, and immunoglobulin-g) was evaluated using a micro-BCA assay and X-ray photoelectron spectroscopy (XPS). The adhesion and activation of platelets was investigated using live-cell staining, MTT assay, and SEM. Whole blood clotting kinetics was evaluated by measuring the free hemoglobin concentration, and SEM was used to visualize the clot formation. Our results indicate increased blood serum protein adsorption, platelet adhesion and activation, and whole blood clotting kinetics on titania nanotube arrays. PMID:20629021

  8. Boron nitride nanotubes and nanosheets.

    PubMed

    Golberg, Dmitri; Bando, Yoshio; Huang, Yang; Terao, Takeshi; Mitome, Masanori; Tang, Chengchun; Zhi, Chunyi

    2010-06-22

    Hexagonal boron nitride (h-BN) is a layered material with a graphite-like structure in which planar networks of BN hexagons are regularly stacked. As the structural analogue of a carbon nanotube (CNT), a BN nanotube (BNNT) was first predicted in 1994; since then, it has become one of the most intriguing non-carbon nanotubes. Compared with metallic or semiconducting CNTs, a BNNT is an electrical insulator with a band gap of ca. 5 eV, basically independent of tube geometry. In addition, BNNTs possess a high chemical stability, excellent mechanical properties, and high thermal conductivity. The same advantages are likely applicable to a graphene analogue-a monatomic layer of a hexagonal BN. Such unique properties make BN nanotubes and nanosheets a promising nanomaterial in a variety of potential fields such as optoelectronic nanodevices, functional composites, hydrogen accumulators, electrically insulating substrates perfectly matching the CNT, and graphene lattices. This review gives an introduction to the rich BN nanotube/nanosheet field, including the latest achievements in the synthesis, structural analyses, and property evaluations, and presents the purpose and significance of this direction in the light of the general nanotube/nanosheet developments. PMID:20462272

  9. Redox sorting of carbon nanotubes.

    PubMed

    Gui, Hui; Streit, Jason K; Fagan, Jeffrey A; Hight Walker, Angela R; Zhou, Chongwu; Zheng, Ming

    2015-03-11

    This work expands the redox chemistry of single-wall carbon nanotubes (SWCNTs) by investigating its role in a number of SWCNT sorting processes. Using a polyethylene glycol (PEG)/dextran (DX) aqueous two-phase system, we show that electron-transfer between redox molecules and SWCNTs triggers reorganization of the surfactant coating layer, leading to strong modulation of nanotube partition in the two phases. While the DX phase is thermodynamically more favored by an oxidized SWCNT mixture, the mildly reducing PEG phase is able to recover SWCNTs from oxidation and extract them successively from the DX phase. Remarkably, the extraction order follows SWCNT bandgap: semiconducting nanotubes of larger bandgap first, followed by semiconducting nanotubes of smaller bandgap, then nonarmchair metallic tubes of small but nonvanishing bandgap, and finally armchair metallic nanotubes of zero bandgap. Furthermore, we show that redox-induced surfactant reorganization is a common phenomenon, affecting nanotube buoyancy in a density gradient field, affinity to polymer matrices, and solubility in organic solvents. These findings establish redox modulation of surfactant coating structures as a general mechanism for tuning a diverse range of SWCNT sorting processes and demonstrate for the first time that armchair and nonarmchair metallic SWCNTs can be separated by their differential response to redox. PMID:25719939

  10. Occupational Exposure to Carbon Nanotubes and Nanofibers

    MedlinePlus

    ... Current Intelligence Bulletin 65: Occupational Exposure to Carbon Nanotubes and Nanofibers Recommend on Facebook Tweet Share Compartir ... composed of engineered nanoparticles, such as metal oxides, nanotubes, nanowires, quantum dots, and carbon fullerenes (buckyballs), among ...

  11. Computational Nanotechnology of Nanotubes, Composites, and Electronics

    NASA Technical Reports Server (NTRS)

    Srivastava, D.; Biegel, Bryan A. (Technical Monitor)

    2002-01-01

    This viewgraph presentation addresses carbon nanotubes, their mechanical and thermal properties, and their structure, as well as possible miniature devices which may be assembled in the future from carbon nanotubes.

  12. Scanning tunneling microscopy imaging of nanotubes

    SciTech Connect

    Antonenko, S. V. Malinovskaya, O. S.; Mal'tsev, S. N.

    2007-07-15

    Samples of carbon paper containing multiwalled carbon nanotube films are produced by current annealing. A scanning tunneling microscope is used to examine the structure of the modified carbon paper. X-, Y-, and V-shaped nanotubes are found.

  13. Probing Photosensitization by Functionalized Carbon Nanotubes

    EPA Science Inventory

    Carbon nanotubes (CNTs) photosensitize the production of reactive oxygen species that can damage organisms by biomembrane oxidation or mediate CNTs' environmental transformations. The photosensitized nature of derivatized carbon nanotubes from various synthetic methods, and thus ...

  14. Oligomer functionalized nanotubes and composites formed therewith

    DOEpatents

    Zettl, Alexander K; Sainsbury, Toby; Frechet, Jean M.J.

    2014-03-18

    Disclosed herein is a sequential functionalization methodology for the covalent modification of nanotubes with between one and four repeat units of a polymer. Covalent attachment of oligomer units to the surface of nanotubes results in oligomer units forming an organic sheath around the nanotubes, polymer-functionalized-nanotubes (P-NTs). P-NTs possess chemical functionality identical to that of the functionalizing polymer, and thus provide nanoscale scaffolds which may be readily dispersed within a monomer solution and participate in the polymerization reaction to form a polymer-nanotube/polymer composite. Formation of polymer in the presence of P-NTs leads to a uniform dispersion of nanotubes within the polymer matrix, in contrast to aggregated masses of nanotubes in the case of pristine-NTs. The covalent attachment of oligomeric units to the surface of nanotubes represents the formation of a functional nanoscale building block which can be readily dispersed and integrated within the polymer to form a novel composite material.

  15. Carbon Nanotube Assemblies for Transparent Conducting Electrodes

    SciTech Connect

    Garrett, Matthew P; Gerhardt, Rosario

    2012-01-01

    The goal of this chapter is to introduce readers to the fundamental and practical aspects of nanotube assemblies made into transparent conducting networks and discuss some practical aspects of their characterization. Transparent conducting coatings (TCC) are an essential part of electro-optical devices, from photovoltaics and light emitting devices to electromagnetic shielding and electrochromic widows. The market for organic materials (including nanomaterials and polymers) based TCCs is expected to show a growth rate of 56.9% to reach nearly 20.3billionin2015,whilethemarketfortraditionalinorganictransparentelectronicswillexperiencegrowthwithratesof6.7103 billion in 2015. Emerging flexible electronic applications have brought additional requirements of flexibility and low cost for TCC. However, the price of indium (the major component in indium tin oxide TCC) continues to increase. On the other hand, the price of nanomaterials has continued to decrease due to development of high volume, quality production processes. Additional benefits come from the low cost, nonvacuum deposition of nanomaterials based TCC, compared to traditional coatings requiring energy intensive vacuum deposition. Among the materials actively researched as alternative TCC are nanoparticles, nanowires, and nanotubes with high aspect ratio as well as their composites. The figure of merit (FOM) can be used to compare TCCs made from dissimilar materials and with different transmittance and conductivity values. In the first part of this manuscript, we will discuss the seven FOM parameters that have been proposed, including one specifically intended for flexible applications. The approach for how to measure TCE electrical properties, including frequency dependence, will also be discussed. We will relate the macroscale electrical characteristics of TCCs to the nanoscale parameters of conducting networks. The fundamental aspects of nanomaterial assemblies in conducting networks will also be addressed

  16. LDRD final report on carbon nanotube composites

    SciTech Connect

    Cahill, P.A.; Rand, P.B.

    1997-04-01

    Carbon nanotubes and their composites were examined using computational and experimental techniques in order to modify the mechanical and electrical properties of resins. Single walled nanotubes were the focus of the first year effort; however, sufficient quantities of high purity single walled nanotubes could not be obtained for mechanical property investigations. The unusually high electrical conductivity of composites loaded with <1% of multiwalled nanotubes is useful, and is the focus of continuing, externally funded, research.

  17. Carbon nanotubes by the metallocene route

    NASA Astrophysics Data System (ADS)

    Sen, Rahul; Govindaraj, A.; Rao, C. N. R.

    1997-03-01

    Pyrolysis of metallocenes such as ferrocene, cobaltocene and nickelocene, is shown to yield carbon nanotubes and metal-filled onion-like structures. Pyrolysis of benzene in the presence of a metallocene gives high yields of nanotubes, the wall thickness of the nanotubes depending on the metallocene content. Pyrolysis of benzene in the absence of any metal however gives monodispersed nanospheres of carbon rather than nanotubes.

  18. Carbon nanotube biosensors

    PubMed Central

    Tîlmaciu, Carmen-Mihaela; Morris, May C.

    2015-01-01

    Nanomaterials possess unique features which make them particularly attractive for biosensing applications. In particular, carbon nanotubes (CNTs) can serve as scaffolds for immobilization of biomolecules at their surface, and combine several exceptional physical, chemical, electrical, and optical characteristics properties which make them one of the best suited materials for the transduction of signals associated with the recognition of analytes, metabolites, or disease biomarkers. Here we provide a comprehensive review on these carbon nanostructures, in which we describe their structural and physical properties, functionalization and cellular uptake, biocompatibility, and toxicity issues. We further review historical developments in the field of biosensors, and describe the different types of biosensors which have been developed over time, with specific focus on CNT-conjugates engineered for biosensing applications, and in particular detection of cancer biomarkers. PMID:26579509

  19. Cantilevered carbon nanotube hygrometer

    NASA Astrophysics Data System (ADS)

    Kuroyanagi, Toshinori; Terada, Yuki; Takei, Kuniharu; Akita, Seiji; Arie, Takayuki

    2014-05-01

    We investigate the effects of humidity on the vibrations of carbon nanotubes (CNTs) using two types of CNT cantilevers: open-ended and close-ended CNT cantilevers. As the humidity increases, the resonant frequency of the open-ended CNT cantilever decreases due to the adsorption of water molecules onto the CNT tip, whereas that of the close-ended CNT cantilever increases probably due to the change in the viscosity of the air surrounding the CNT cantilever, which is negatively correlated with the humidity of air. Our findings suggest that a close-ended CNT cantilever is more suitable for a quick-response and ultrasensitive hygrometer because it continuously reads the viscosity change of moist air in the vicinity of the CNT.

  20. On carbon nanotube resonators

    NASA Astrophysics Data System (ADS)

    Caruntu, Dumitru I.; Salinas Trevino, Cone S.

    2011-04-01

    This paper deals with electrostatically actuated Carbon NanoTubes (CNT) cantilevers for sensor applications. There are three kinds of forces acting on the CNT cantilever: electrostatic, elastostatic, and van der Waals. The van der Waals forces are significant for values of 50 nm or lower of the gap between the CNT and the ground plate. As both forces, electrostatic and van der Waals, are nonlinear, and the CNT electrostatic actuation is given by AC voltage, the CNT dynamics is nonlinear parametric. The method of multiple scales is used to investigate the system under soft excitations and/or weakly nonlinearities. The frequency-amplitude and frequency-phase behavior are found in the case of primary resonance.

  1. Carbon nanotube biconvex microcavities

    SciTech Connect

    Butt, Haider Ahmed, Rajib; Yetisen, Ali K.; Yun, Seok Hyun; Dai, Qing

    2015-03-23

    Developing highly efficient microcavities with predictive narrow-band resonance frequencies using the least amount of material will allow the applications in nonlinear photonic devices. We have developed a microcavity array that comprised multi-walled carbon nanotubes (MWCNT) organized in a biconvex pattern. The finite element model allowed designing microcavity arrays with predictive transmission properties and assessing the effects of the microarray geometry. The microcavity array demonstrated negative index and produced high Q factors. 2–3 μm tall MWCNTs were patterned as biconvex microcavities, which were separated by 10 μm in an array. The microcavity was iridescent and had optical control over the diffracted elliptical patterns with a far-field pattern, whose properties were predicted by the model. It is anticipated that the MWCNT biconvex microcavities will have implications for the development of highly efficient lenses, metamaterial antennas, and photonic circuits.

  2. Carbon nanotube optical mirrors

    NASA Astrophysics Data System (ADS)

    Chen, Peter C.; Rabin, Douglas

    2015-01-01

    We report the fabrication of imaging quality optical mirrors with smooth surfaces using carbon nanotubes (CNT) embedded in an epoxy matrix. CNT/epoxy is a multifunctional composite material that has sensing capabilities and can be made to incorporate self-actuation. Moreover, as the precursor is a low density liquid, large and lightweight mirrors can be fabricated by processes such as replication, spincasting, and three-dimensional printing. Therefore, the technology holds promise for the development of a new generation of lightweight, compact "smart" telescope mirrors with figure sensing and active or adaptive figure control. We report on measurements made of optical and mechanical characteristics, active optics experiments, and numerical modeling. We discuss possible paths for future development.

  3. Carbon Nanotube Biosensors

    NASA Astrophysics Data System (ADS)

    Tilmaciu, Carmen-Mihaela; Morris, May

    2015-10-01

    Nanomaterials possess unique features which make them particularly attractive for biosensing applications. In particular Carbon Nanotubes (CNTs) can serve as scaffolds for immobilization of biomolecules at their surface, and combine several exceptional physical, chemical, electrical and optical characteristics properties which make them one of the best suited materials for the transduction of signals associated with the recognition of analytes, metabolites or disease biomarkers. Here we provide a comprehensive review on these carbon nanostructures, in which we will describe their structural and physical properties, discuss functionalization and cellular uptake, biocompatibility and toxicity issues. We further review historical developments in the field of biosensors, and describe the different types of biosensors which have been developed over time, with specific focus on CNT-conjugates engineered for biosensing applications, and in particular detection of cancer biomarkers.

  4. Functionalization of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Khare, Bishun N. (Inventor); Meyyappan, Meyya (Inventor)

    2009-01-01

    Method and system for functionalizing a collection of carbon nanotubes (CNTs). A selected precursor gas (e.g., H2 or F2 or CnHm) is irradiated to provide a cold plasma of selected target species particles, such as atomic H or F, in a first chamber. The target species particles are d irected toward an array of CNTs located in a second chamber while suppressing transport of ultraviolet radiation to the second chamber. A CNT array is functionalized with the target species particles, at or below room temperature, to a point of saturation, in an exposure time interval no longer than about 30 sec. *Discrimination against non-target species is provided by (i) use of a target species having a lifetime that is much greater than a lifetime of a non-target species and/or (2) use of an applied magnetic field to discriminate between charged particle trajectories for target species and for non-target species.

  5. Carbon Nanotube Electron Gun

    NASA Technical Reports Server (NTRS)

    Nguyen, Cattien V. (Inventor); Ribaya, Bryan P. (Inventor)

    2013-01-01

    An electron gun, an electron source for an electron gun, an extractor for an electron gun, and a respective method for producing the electron gun, the electron source and the extractor are disclosed. Embodiments provide an electron source utilizing a carbon nanotube (CNT) bonded to a substrate for increased stability, reliability, and durability. An extractor with an aperture in a conductive material is used to extract electrons from the electron source, where the aperture may substantially align with the CNT of the electron source when the extractor and electron source are mated to form the electron gun. The electron source and extractor may have alignment features for aligning the electron source and the extractor, thereby bringing the aperture and CNT into substantial alignment when assembled. The alignment features may provide and maintain this alignment during operation to improve the field emission characteristics and overall system stability of the electron gun.

  6. Carbon nanotube electron gun

    NASA Technical Reports Server (NTRS)

    Nguyen, Cattien V. (Inventor); Ribaya, Bryan P. (Inventor)

    2010-01-01

    An electron gun, an electron source for an electron gun, an extractor for an electron gun, and a respective method for producing the electron gun, the electron source and the extractor are disclosed. Embodiments provide an electron source utilizing a carbon nanotube (CNT) bonded to a substrate for increased stability, reliability, and durability. An extractor with an aperture in a conductive material is used to extract electrons from the electron source, where the aperture may substantially align with the CNT of the electron source when the extractor and electron source are mated to form the electron gun. The electron source and extractor may have alignment features for aligning the electron source and the extractor, thereby bringing the aperture and CNT into substantial alignment when assembled. The alignment features may provide and maintain this alignment during operation to improve the field emission characteristics and overall system stability of the electron gun.

  7. Development of Metal-impregnated Single Walled Carbon Nanotubes for Toxic Gas Contaminant Control in Advanced Life Support Systems

    NASA Technical Reports Server (NTRS)

    Pisharody, Suresh A.; Fisher, John W.; Wignarajah, K.

    2002-01-01

    The success of physico-chemical waste processing and resource recovery technologies for life support application depends partly on the ability of gas clean-up systems to efficiently remove trace contaminants generated during the process with minimal use of expendables. Carbon nanotubes promise superior performance over conventional approaches to gas clean-up due to their ability to direct the selective uptake of gaseous species based on their controlled pore size, high surface area, ordered chemical structure that allows functionalization and their effectiveness also as catalyst support materials for toxic gas conversion. We present results and findings from a preliminary study on the effectiveness of metal impregnated single walled nanotubes as catalyst/catalyst support materials for toxic gas contaminate control. The study included the purification of single walled nanotubes, the catalyst impregnation of the purified nanotubes, the experimental characterization of the surface properties of purified single walled nanotubes and the characterization of physisorption and chemisorption of uptake molecules.

  8. Self-assembled supramolecular nanotube yarn.

    PubMed

    Liu, Yaqing; Wang, Tianyu; Huan, Yong; Li, Zhibo; He, Guowei; Liu, Minghua

    2013-11-01

    Metric length supramolecular nanotube yarns are fabricated though a spinning process from the diluted aqueous solution of self-assembled nanotubes, with bolaamphiphiles working as molecular building blocks. These non-covalent bonding based nanotube yarns show outstanding mechanical strength compared with some conventional polymers and could be operated under the macro conditions. PMID:23943418

  9. Dispersions of Carbon nanotubes in Polymer Matrices

    NASA Technical Reports Server (NTRS)

    Wise, Kristopher Eric (Inventor); Park, Cheol (Inventor); Siochi, Emilie J. (Inventor); Harrison, Joycelyn S. (Inventor); Lillehei, Peter T. (Inventor); Lowther, Sharon E. (Inventor)

    2010-01-01

    Dispersions of carbon nanotubes exhibiting long term stability are based on a polymer matrix having moieties therein which are capable of a donor-acceptor complexation with carbon nanotubes. The carbon nanotubes are introduced into the polymer matrix and separated therein by standard means. Nanocomposites produced from these dispersions are useful in the fabrication of structures, e.g., lightweight aerospace structures.

  10. Conductance Oscillations in Squashed Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Mehrez, H.; Anantram, M. P.; Svizhenko, A.

    2003-01-01

    A combination of molecular dynamics and electrical conductance calculations are used to probe the electromechanical properties of squashed metallic carbon nanotubes. We find that the conductance and bandgap of armchair nanotubes show oscillations upon squashing. The physical origin of these oscillations is attributed to interaction of carbon atoms with a fourth neighbor. Squashing of armchair and zigzag nanotubes ultimately leads to metallic behavior.

  11. Nanotubes in Nanoelectronics: Transport, Growth and Modeling

    NASA Technical Reports Server (NTRS)

    Anantram, M.; Delzeit, Lance; Cassell, Alan; Han, Jie; Meyyappan, M.; Arnold, Jim (Technical Monitor)

    2001-01-01

    Carbon nanotube (CNT) baud nanotechnology appears to be promising for future Theoretical analysis and results for the ballistic current carrying capacity of nanotube wires am presented. Aspects of metal-nanotube coupling are examined. Results am also presented for chemical vapor deposition of CNT from hydrocarbon feedstock.

  12. Water transport control in carbon nanotube arrays

    PubMed Central

    2014-01-01

    Based on a recent scaling law of the water mobility under nanoconfined conditions, we envision novel strategies for precise modulation of water diffusion within membranes made of carbon nanotube arrays (CNAs). In a first approach, the water diffusion coefficient D may be tuned by finely controlling the size distribution of the pore size. In the second approach, D can be varied at will by means of externally induced electrostatic fields. Starting from the latter strategy, switchable molecular sieves are proposed, where membranes are properly designed with sieving and permeation features that can be dynamically activated/deactivated. Areas where a precise control of water transport properties is beneficial range from energy and environmental engineering up to nanomedicine. PMID:25313305

  13. Oscillation control of carbon nanotube mechanical resonator by electrostatic interaction induced retardation

    NASA Astrophysics Data System (ADS)

    Yasuda, Masaaki; Takei, Kuniharu; Arie, Takayuki; Akita, Seiji

    2016-03-01

    Despite the superb intrinsic properties of carbon nanotube mechanical resonators, the quality factors at room temperature are 1,000 or less, even in vacuum, which is much lower than that of mechanical resonators fabricated using a top-down approach. This study demonstrates the improvement of the quality factor and the control of nonlinearity of the mechanical resonance of the cantilevered nanotube by electrostatic interaction. The apparent quality factor of the nanotube supported by insulator is improved drastically from approximately 630 to 3200 at room temperature. Results show that retardation of the electrostatic force induced by the contact resistance between the nanotube and the insulator support improves the quality factor. Finite element method calculation reveals that the nonuniform pileup charge on the insulator support strongly influences the nonlinearity of the resonance.

  14. Direct Measurement of Polarized Absorption Cross-Section of Single-Wall Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Islam, M. F.; Milkie, D. E.; Kane, C. L.; Yodh, A. Y.; Kikkawa, J. M.

    2004-03-01

    We use a combination of polarized Raman scattering and linear optical absorption to infer optical absorption cross-sections of single-wall carbon nanotube ensembles for visible light co- and cross-polarized with respect to the nanotube axes. These data reveal a strong linear absorption anisotropy, and provide a rapid method by which linear absorption spectra can be used to quantitatively measure the orientation of dispersed nanotubes, even in strongly absorbing media for which Raman approaches are complicated by anisotropic re-absorption processes. Comparison with theory demonstrates that local field depolarization plays a crucial role in affecting optical spectra of the nanotubes. This work supported by NSF through DMR-0203378, DMR-079909 and DGE-0221664, NASA through NAG8-2172, DARPA/ONR through N00014-01-1-0831, and SENS.

  15. Oscillation control of carbon nanotube mechanical resonator by electrostatic interaction induced retardation

    PubMed Central

    Yasuda, Masaaki; Takei, Kuniharu; Arie, Takayuki; Akita, Seiji

    2016-01-01

    Despite the superb intrinsic properties of carbon nanotube mechanical resonators, the quality factors at room temperature are 1,000 or less, even in vacuum, which is much lower than that of mechanical resonators fabricated using a top-down approach. This study demonstrates the improvement of the quality factor and the control of nonlinearity of the mechanical resonance of the cantilevered nanotube by electrostatic interaction. The apparent quality factor of the nanotube supported by insulator is improved drastically from approximately 630 to 3200 at room temperature. Results show that retardation of the electrostatic force induced by the contact resistance between the nanotube and the insulator support improves the quality factor. Finite element method calculation reveals that the nonuniform pileup charge on the insulator support strongly influences the nonlinearity of the resonance. PMID:26935657

  16. Magnetic Property Measurements on Single Wall Carbon Nanotube-Polyimide Composites

    NASA Technical Reports Server (NTRS)

    Sun, Keun J.; Wincheski, Russell A.; Park, Cheol

    2008-01-01

    Temperature and magnetic field dependent magnetization measurements were performed on polyimide nanocomposite samples, synthesized with various weight percentages of single wall carbon nanotubes. It was found that the magnetization of the composite, normalized to the mass of nanotube material in the sample, decreased with increasing weight percentage of nanotubes. It is possible that the interfacial coupling between the carbon nanotube (CNT) fillers and the polyimide matrix promotes the diamagnetic response from CNTs and reduces the total magnetization of the composite. The coercivity of the samples, believed to originate from the residual magnetic catalyst particles, was enhanced and had a stronger temperature dependence as a result of the composite synthesis. These changes in magnetic properties can form the basis of a new approach to investigate the interfacial properties in the CNT nanocomposites through magnetic property measurements.

  17. Giant Surface Conductivity Enhancement in a Carbon Nanotube Composite by Ultraviolet Light Exposure.

    PubMed

    Long, Christian J; Orloff, Nathan D; Twedt, Kevin A; Lam, Thomas; Vargas-Lara, Fernando; Zhao, Minhua; Natarajan, Bharath; Scott, Keana C; Marksz, Eric; Nguyen, Tinh; Douglas, Jack F; McClelland, Jabez; Garboczi, Edward; Obrzut, Jan; Liddle, J Alexander

    2016-09-01

    Carbon nanotube composites are lightweight, multifunctional materials with readily adjustable mechanical and electrical properties-relevant to the aerospace, automotive, and sporting goods industries as high-performance structural materials. Here, we combine well-established and newly developed characterization techniques to demonstrate that ultraviolet (UV) light exposure provides a controllable means to enhance the electrical conductivity of the surface of a commercial carbon nanotube-epoxy composite by over 5 orders of magnitude. Our observations, combined with theory and simulations, reveal that the increase in conductivity is due to the formation of a concentrated layer of nanotubes on the composite surface. Our model implies that contacts between nanotube-rich microdomains dominate the conductivity of this layer at low UV dose, while tube-tube transport dominates at high UV dose. Further, we use this model to predictably pattern conductive traces with a UV laser, providing a facile approach for direct integration of lightweight conductors on nanocomposite surfaces. PMID:27468781

  18. Study on a novel dosimeter based on polyethylene-carbon nanotube composite

    NASA Astrophysics Data System (ADS)

    Malekie, S.; Ziaie, F.

    2015-08-01

    In this research work, the electric current of polyethylene-carbon nanotube composite, in the electrical percolation threshold region, over the absorbed dose under the applied bias voltage was investigated via the finite element method. The investigated geometry was formed by a two-dimensional cross-sectional view of randomly orientated nanotubes as ellipses. The variable range hopping model developed by Mott and thermally activated hopping model was used to calculate the electrical conductivity of carbon nanotubes and polymer, respectively. Regarding the calorimetric approach, we considered the absorbed dose equal to heat capacity of polyethylene-carbon nanotube composite multiplied by temperature rise. Results showed that this kind of composite can be used for low dose rate applications for monitoring and radiation protection utilizations.

  19. Scalable fabrication of carbon nanotube/polymer nanocomposite membranes for high flux gas transport.

    PubMed

    Kim, Sangil; Jinschek, Joerg R; Chen, Haibin; Sholl, David S; Marand, Eva

    2007-09-01

    We present a simple, fast, and practical route to vertically align carbon nanotubes on a porous support using a combination of self-assembly and filtration methods. The advantage of this approach is that it can be easily scaled up to large surface areas, allowing the fabrication of membranes for practical gas separation applications. The gas transport properties of thus constructed nanotube/polymer nanocomposite membranes are analogous to those of carbon nanotube membranes grown by chemical vapor deposition. This paper shows the first data for transport of gas mixtures through carbon nanotube membranes. The permeation of gas mixtures through the membranes exhibits different properties than those observed using single-gas experiments, confirming that non-Knudsen transport occurs. PMID:17685662

  20. Horseradish peroxidase-driven fluorescent labeling of nanotubes with quantum dots.

    PubMed

    Didenko, Vladimir V; Baskin, David S

    2006-03-01

    We describe the first enzyme-driven technique for fluorescent labeling of single-walled carbon nanotubes (SWNTs). The labeling was performed via enzymatic biotinylation of nanotubes in the tyramide-horseradish peroxidase (HRP) reaction. Both direct and indirect fuorescent labeling of SWNTs was achieved using either biotinyl tyramide or fluorescently tagged tyramides. Biotinylated SWNTs later reacted with streptavidin-conjugated fluorophores. Linking semiconductor nanocrystals, quantum dots (Q-dots), to the surface of nanotubes resulted in their fluorescent visualization, whereas conventional fluorophores bound to SWNTs directly or through biotin-streptavidin linkage, were completely quenched. Enzymatic biotinylation permits fluorescent visualization of carbon nanotubes, which could be useful for a number of biomedical applications. In addition, other organic molecules such as proteins, antibodies, or DNA can be conjugated to biotinylated SWNTs using this approach. PMID:16568818

  1. Shape transition of unstrained flattest single-walled carbon nanotubes under pressure

    SciTech Connect

    Mu, Weihua E-mail: muwh@itp.ac.cn; Cao, Jianshu; Ou-Yang, Zhong-can

    2014-01-28

    Single walled carbon nanotube's (SWCNT's) cross section can be flattened under hydrostatic pressure. One example is the cross section of a single walled carbon nanotube successively deforms from the original round shape to oval shape, then to peanut-like shape. At the transition point of reversible deformation between convex shape and concave shape, the side wall of nanotube is flattest. This flattest tube has many attractive properties. In the present work, an approximate approach is developed to determine the equilibrium shape of this unstrained flattest tube and the curvature distribution of this tube. Our results are in good agreement with recent numerical results, and can be applied to the study of pressure controlled electric properties of single walled carbon nanotubes. The present method can also be used to study other deformed inorganic and organic tube-like structures.

  2. FAST TRACK COMMUNICATION: Mechanical properties of non-reconstructed defective single-wall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Scarpa, F.; Adhikari, S.; Wang, C. Y.

    2009-07-01

    This paper describes the equivalent homogeneous uniaxial mechanical properties of defective single-wall carbon nanotubes. In particular, non-reconstructed defects that can be produced by ion or electronic irradiation have been considered. A discrete nonlinear finite-element approach based on the mechanical properties of individual carbon-carbon (C-C) bonds has been used. The individual C-C bonds in turn were simulated as beam structural elements. Extensive Monte Carlo based numerical simulation has been reported in the paper. The results show that the homogeneous elastic properties of the defective nanotubes can be qualitatively and quantitatively different from the pristine configurations. The defective nanotubes show a slight reduction in axial stiffness (Young's modulus), but large variations of Poisson's ratio outside the elastic bounds for isotropic materials, depending on the locations of the vacancies. The large fluctuations of Poisson's ratio can lead to extreme positive transversal contractions or to auxetic behaviour when the nanotubes are subjected to tensile loading.

  3. Room temperature synthesis of indium tin oxide nanotubes with high precision wall thickness by electroless deposition

    PubMed Central

    Ionescu, Emanuel; Fu, Ganhua; Ensinger, Wolfgang

    2011-01-01

    Summary Conductive nanotubes consisting of indium tin oxide (ITO) were fabricated by electroless deposition using ion track etched polycarbonate templates. To produce nanotubes (NTs) with thin walls and small surface roughness, the tubes were generated by a multi-step procedure under aqueous conditions. The approach reported below yields open end nanotubes with well defined outer diameter and wall thickness. In the past, zinc oxide films were mostly preferred and were synthesized using electroless deposition based on aqueous solutions. All these methods previously developed, are not adaptable in the case of ITO nanotubes, even with modifications. In the present work, therefore, we investigated the necessary conditions for the growth of ITO-NTs to achieve a wall thickness of around 10 nm. In addition, the effects of pH and reductive concentrations for the formation of ITO-NTs are also discussed. PMID:21977422

  4. A novel silica-coated multiwall carbon nanotube with CdTe quantum dots nanocomposite

    NASA Astrophysics Data System (ADS)

    Fei, Qiang; Xiao, Dehai; Zhang, Zhiquan; Huan, Yanfu; Feng, Guodong

    2009-10-01

    A novel silica-coated multiwall carbon nanotube (MWNTs) with CdTe quantum dots nanocomposite was synthesized in this paper. Here, we show the in situ growth of crystalline CdTe quantum dots on the surfaces of oxidized MWNTs. The approach proposed herein differs from previous attempts to synthesize nanotube assemblies in that we mix the oxidized MWNTs into CdCl 2 solution of CdTe nanocrystals synthesized in aqueous solution. Reinforced the QD-MWNTs heterostructures with silica coating, this method is not invasive and does not introduce defects to the structure of carbon nanotubes (CNTs), and it ensures high stability in a range of organic solvents. Furthermore, a narrow SiO 2 layer on the MWNT-CdTe heterostructures can eliminate the biological toxicity of quantum dots and carbon nanotubes. This is not only a breakthrough in the synthesis of one-dimensional nanostructures, but also taking new elements into bio-nanotechnology.

  5. Characterization of bundled and individual triple-walled carbon nanotubes by resonant Raman spectroscopy.

    PubMed

    Hirschmann, Thomas Ch; Araujo, Paulo T; Muramatsu, Hiroyuki; Zhang, Xu; Nielsch, Kornelius; Kim, Yoong Ahm; Dresselhaus, Mildred S

    2013-03-26

    The optical characterization of bundled and individual triple-walled carbon nanotubes was studied for the first time in detail by using resonant Raman spectroscopy. In our approach, the outer tube of a triple-walled carbon nanotube system protects the two inner tubes (or equivalently the inner double-walled carbon nanotube) from external environment interactions making them a partially isolated system. Following the spectral changes and line-widths of the radial breathing modes and G-band by performing laser energy dependent Raman spectroscopy, it is possible to extract important information as regards to the electronic and vibrational properties, tube diameters, wall-to-wall distances, radial breathing mode, and G-band resonance evolutions as well as high-curvature intertube interactions in isolated double- and triple-walled carbon nanotube systems. PMID:23311296

  6. Control of Effluent Gases from Solid Waste Processing Using Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Fisher, John; Cinke, Martin; Wignarajab, Kanapathipillai

    2005-01-01

    One of the major problems associated with solid waste processing technologies is the release of effluent gases and contaminants that are in gaseous formed from the processes. A number of other gases, in particular NO(x), SO2, NH3, Hydrocarbons (e.g. CH4) do present hazards to the crew in space habitats. Reduction of mass, power, volume and resupply can be achieved by using catalyst impregnated carbon nanotubes as compared to other catalytic systems. The development and characterization of an innovative approach for the control and elimination of gaseous toxins using single walled carbon nanotubes (SWNTs) promise superior performance over conventional approaches. This is due to the ability to direct the selective uptake of gaseous species based on their controllable pore size, high adsorptive capacity and the effectiveness of carbon nanotubes as catalyst supports for gaseous conversion. For example, SWNTs have high adsorptive capacity for NO and the adsorbed NO can be decomposed to N2 and O2 . Experimental results showing the decomposition of NO on metal impregnated carbon nanotubes is presented. Equivalent System Mass (ESM) comparisons are made of the existing TCCS systems with the carbon nanotube technology for removing NO(x). The potential for methane decomposition using carbon nanotubes catalysts is also discussed.

  7. Improvement of the identification of multiwall carbon nanotubes carpet thermal conductivity by pulsed photothermal method

    SciTech Connect

    Amin-Chalhoub, E.; Wattieaux, G.; Semmar, N.; Gaillard, M.; Petit, A.; Leborgne, C.

    2012-11-01

    Thermal properties in multiwall carbon nanotubes carpets and micro-devices are investigated using a nanosecond photothermal method. Gradually, the identification model and experimental protocol are performed to increase the method accuracy for the thermal conductivity determination. In the experimental protocol, a nanosecond UV monopulse laser beam is used to heat the surface of a multilayer (600 nm of Ti/20 {mu}m of carbon nanotube carpet) sample. In the 1D identification model with two layers and a thermal contact resistance, the effect of the laser excitation temporal shape is taken into account. In this study, this first approach allows to improve the accuracy of apparent thermal conductivity measurements of multiwall carbon nanotubes carpet. The carbon nanotubes carpet apparent thermal conductivity value went from being to 180 {+-} 5 W Multiplication-Sign m{sup -1} Multiplication-Sign K{sup -1}. In the second approach, two laser beams are coupled in order to increase the interaction time duration from 27 ns to 60 ns. It becomes possible to probe different depths in the carpet. The obtained value (180 W Multiplication-Sign m{sup -1} Multiplication-Sign K{sup -1}) confirms the pulsed photothermal method consistency for porous samples. Finally, assuming that the carbon nanotubes are parallel and without any defects, the equivalent intrinsic thermal conductivity of a single carbon nanotube is estimated to be around 3600 W Multiplication-Sign m{sup -1} Multiplication-Sign K{sup -1}.

  8. A nanoscale transmission system with novel-structured carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Kan, Biao; Ding, Jianning; Zhang, Yongbin; Zhang, Zhongqiang; Cheng, Guanggui

    2013-01-01

    We present a prototype of nanoscale transmission system consisted of three novel-structured carbon nanotubes, namely, the "T," "I," and "Ω" type nanotubes. Double-walled carbon nanotubes (DWCNTs) serve as joints and linear bearings in this system. Molecular dynamics simulations were carried out to investigate the transmission properties. The obtained results show that this system can work at ultrahigh rotation speeds ˜109 rps with a broad temperature range 10-1000 K. The maximum variations of the output displacement in the stroke and lateral directions caused by the vibration are, respectively, 2.3-2.6 Å and 0.27-0.95 Å, which are 6.1%-7.0% and 0.7%-2.5% of the stroke length, respectively. Moreover, the displacement precision can be effectively improved by decreasing the input rotation speed or the temperature. The small change of the van der Waals potential energy in the DWCNTs indicates ultra low frictions in the joints, which contributes to the smooth transmission motion of the system. These results may suggest a new approach to the design of nanoscale electromechanical systems by taking different types of novel-structured carbon nanotubes.

  9. A carbon nanotube based ammonia sensor on cotton textile

    NASA Astrophysics Data System (ADS)

    Han, Jin-Woo; Kim, Beomseok; Li, Jing; Meyyappan, M.

    2013-05-01

    A single-wall carbon nanotube (CNT) based ammonia (NH3) sensor was implemented on a cotton yarn. Two types of sensors were fabricated: Au/sensing CNT/Au and conducting/sensing/conducting all CNT structures. Two perpendicular Au wires were designed to contact CNT-cotton yarn for metal-CNT sensor, whereas nanotubes were used for the electrode as well as sensing material for the all CNT sensor. The resistance shift of the CNT network upon NH3 was monitored in a chemiresistor approach. The CNT-cotton yarn sensors exhibited uniformity and repeatability. Furthermore, the sensors displayed good mechanical robustness against bending. The present approach can be utilized for low-cost smart textile applications.

  10. Torsional properties of hexagonal boron nitride nanotubes, carbon nanotubes and their hybrid structures: A molecular dynamics study

    SciTech Connect

    Xiong, Qi-lin; Tian, Xiao Geng

    2015-10-15

    The torsional mechanical properties of hexagonal single-walled boron nitride nanotubes (SWBNNTs), single-walled carbon nanotubes (SWCNTs), and their hybrid structures (SWBN-CNTs) are investigated using molecular dynamics (MD) simulation. Two approaches - force approach and energy approach, are adopted to calculate the shear moduli of SWBNNTs and SWCNTs, the discrepancy between two approaches is analyzed. The results show that the shear moduli of single-walled nanotubes (SWNTs), including SWBNNTs and SWCNTs are dependent on the diameter, especially for armchair SWNTs. The armchair SWNTs show the better ability of resistance the twisting comparable to the zigzag SWNTs. The effects of diameter and length on the critical values of torque of SWNTs are obtained by comparing the torsional behaviors of SWNTs with different diameters and different lengths. It is observed that the MD results of the effect of diameter and length on the critical values of torque agrees well with the prediction of continuum shell model. The shear modulus of SWBN-CNT has a significant dependence on the percentages of SWCNT and the hybrid style has also an influence on shear modulus. The critical values of torque of SWBN-CNTs increase with the increase of the percentages of SWCNT. This phenomenon can be interpreted by the function relationship between the torque of different bonds (B-N-X, C-C-X, C-B-X, C-N-X) and the angles of bonds.

  11. Design and Characterization of Carbon Nanotube Nanocomposites

    NASA Technical Reports Server (NTRS)

    Siochi, Emilie J.; Lillehei, Peter T.; Wise, Kristopher E.; Park, Cheol; Rouse, Jason H.

    2003-01-01

    Revolutionary design concepts in future aerospace vehicles will depend on extraordinary material properties to permit significant reduction of mass and size of components, while imparting intelligence. Due to their combination of remarkable electrical and mechanical properties, carbon nanotubes (CNT) are expected to enable this paradigm shift in design concepts. However, significant challenges still exist in translating these CNT properties into the macrostructures required for future generations of aerospace vehicles. While an accepted route for making the leap from nanostructures to useful macrostructures has not been fully charted, this paper will give an overview of the approach taken by some researchers at NASA Langley Research Center to sort out issues involved in the development of CNT nanocomposites for multifunctional structures. Specifically, the dispersion of carbon nanotubes in polymer matrices, characterization of nanocomposites, the role of quantum computation in providing guidance for processing and the use of computational analysis in data interpretation will be covered. Significant improvements in mechanical and electrical properties of CNT nanocomposites with very low loadings of CNTs are described and lend credence to the potential for using CNTs in achieving technological leaps in composite development.

  12. Metal Nanoparticle Catalysts for Carbon Nanotube Growth

    NASA Technical Reports Server (NTRS)

    Pierce, Benjamin F.

    2003-01-01

    Work this summer involved and new and unique process for producing the metal nanoparticle catalysts needed for carbon nanotube (CNT) growth. There are many applications attributed to CNT's, and their properties have deemed them to be a hot spot in research today. Many groups have demonstrated the versatility in CNT's by exploring a wide spectrum of roles that these nanotubes are able to fill. A short list of such promising applications are: nanoscaled electronic circuitry, storage media, chemical sensors, microscope enhancement, and coating reinforcement. Different methods have been used to grow these CNT's. Some examples are laser ablation, flame synthesis, or furnace synthesis. Every single approach requires the presence of a metal catalyst (Fe, Co, and Ni are among the best) that is small enough to produce a CNT. Herein lies the uniqueness of this work. Microemulsions (containing inverse micelles) were used to generate these metal particles for subsequent CNT growth. The goal of this summer work was basically to accomplish as much preliminary work as possible. I strived to pinpoint which variable (experimental process, metal product, substrate, method of application, CVD conditions, etc.) was the determining factor in the results. The resulting SEM images were sufficient for the appropriate comparisons to be made. The future work of this project consists of the optimization of the more promising experimental procedures and further exploration onto what exactly dictated the results.

  13. Gears Based on Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Jaffe, Richard; Han, Jie; Globus, Al; Deardorff, Glenn

    2005-01-01

    Gears based on carbon nanotubes (see figure) have been proposed as components of an emerging generation of molecular- scale machines and sensors. In comparison with previously proposed nanogears based on diamondoid and fullerene molecules, the nanotube-based gears would have simpler structures and are more likely to be realizable by practical fabrication processes. The impetus for the practical development of carbon-nanotube- based gears arises, in part, from rapid recent progress in the fabrication of carbon nanotubes with prescribed diameters, lengths, chiralities, and numbers of concentric shells. The shafts of the proposed gears would be made from multiwalled carbon nanotubes. The gear teeth would be rigid molecules (typically, benzyne molecules), bonded to the nanotube shafts at atomically precise positions. For fabrication, it may be possible to position the molecular teeth by use of scanning tunneling microscopy (STM) or other related techniques. The capability to position individual organic molecules at room temperature by use of an STM tip has already been demonstrated. Routes to the chemical synthesis of carbon-nanotube-based gears are also under investigation. Chemical and physical aspects of the synthesis of molecular scale gears based on carbon nanotubes and related molecules, and dynamical properties of nanotube- based gears, have been investigated by computational simulations using established methods of quantum chemistry and molecular dynamics. Several particularly interesting and useful conclusions have been drawn from the dynamical simulations performed thus far: The forces acting on the gears would be more sensitive to local molecular motions than to gross mechanical motions of the overall gears. Although no breakage of teeth or of chemical bonds is expected at temperatures up to at least 3,000 K, the gears would not work well at temperatures above a critical range from about 600 to about 1,000 K. Gear temperature could probably be controlled by

  14. Novel nanotubes and encapsulated nanowires

    NASA Astrophysics Data System (ADS)

    Terrones, M.; Hsu, W. K.; Schilder, A.; Terrones, H.; Grobert, N.; Hare, J. P.; Zhu, Y. Q.; Schwoerer, M.; Prassides, K.; Kroto, H. W.; Walton, D. R. M.

    Carbon nanotubes, with or without encapsulated material, generated by arc discharge and electrolytic techniques have been studied. Microcrystals of refractory carbides (i.e. NbC, TaC, MoC), contained in nanotubes and polyhedral particles, produced by arcing electrodes of graphite/metal mixtures, were analysed by high hesolution transmission electron microscopy (HRTEM) and X-ray powder diffraction. Encapsulation of MoC was found to give rise to an unusual stable form, namely face-centered-cubic MoC. SQUID measurements indicate that the encapsulated carbides exhibit superconducting transitions at about 10-12 K, thus they differ from carbon nanotubes/nanoparticles which do not superconduct. Four-probe and microwave (contactless) conductivity measurements indicate that most of the analysed samples behave as semiconductors. However, metallic transport was observed in specimens containing single conglomerated carbon nanotube bundles and boron-doped carbon nanotubes. Novel metallic βSn nanowires were produced by electrolysis of graphite electrodes immersed in molten LiCl/SnCl2 mixtures. Prolonged electron irradiation of these nanowires leads to axial growth and to dynamic transformations. These observations suggest ways in which materials may be modified by microencapsulation and irradiation.

  15. Roping and wrapping carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Ausman, Kevin D.; O'Connell, Michael J.; Boul, Peter; Ericson, Lars M.; Casavant, Michael J.; Walters, Deron A.; Huffman, Chad; Saini, Rajesh; Wang, Yuhuang; Haroz, Erik; Billups, Edward W.; Smalley, Richard E.

    2001-11-01

    Single-walled carbon nanotubes can be dispersed into solvents by ultrasonication to the point that primarily individual tubes, cut to a few hundred nanometers in length, are present. However, when such dispersions are filtered to a thick mat, or paper, only tangles of uniform, seemingly endless ropes are observed. The factors contributing to this "roping" phenomenon, akin to aggregation or crystallization, will be discussed. We have developed methods for generating "super-ropes" more than twenty times the diameter of those formed by filtration, involving the extraction of nanotube material from an oleum dispersion. Nanotubes have been solubilized in water, largely individually, by non-covalently wrapping them with linear polymers. The general thermodynamic drive for this wrapping involves the polymer disrupting both the hydrophobic interface with water and the smooth tube-tube interaction in aggregates. The nanotubes can be recovered from their polymeric wrapping by changing their solvent system. This solubilization process opens the door to solution chemistry on pristine nanotubes, as well as their introduction into biologically relevant systems.

  16. Boron Nitride Nanotubes-Reinforced Glass Composites

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam; Hurst, Janet B.; Choi, Sung R.

    2005-01-01

    Boron nitride nanotubes of significant lengths were synthesized by reaction of boron with nitrogen. Barium calcium aluminosilicate glass composites reinforced with 4 weight percent of BN nanotubes were fabricated by hot pressing. Ambient-temperature flexure strength and fracture toughness of the glass-BN nanotube composites were determined. The strength and fracture toughness of the composite were higher by as much as 90 and 35 percent, respectively, than those of the unreinforced glass. Microscopic examination of the composite fracture surfaces showed pullout of the BN nanotubes. The preliminary results on the processing and improvement in mechanical properties of BN nanotube reinforced glass matrix composites are being reported here for the first time.

  17. Nanocapillarity and chemistry in carbon nanotubes

    SciTech Connect

    Ugarte, D.; Chatelain, A.; Heer, W.A. de

    1996-12-13

    Open carbon nanotubes were filled with molten silver nitrate by capillary forces. Only those tubes with inner diameters of 4 nanometers or more were filled, suggesting a capillarity size dependence as a result of the lowering of the nanotube-salt interface energy with increasing curvature of the nanotube walls. Nanotube cavities should also be less chemically reactive than graphite and may serve as nanosize test tubes. This property has been illustrated by monitoring the decomposition of silver nitrate within nanotubes in situ in an electron microscope, which produced chains of silver nanobeads separated by high-pressure gas pockets. 32 refs., 3 figs.

  18. Supported Lipid Bilayer/Carbon Nanotube Hybrids

    NASA Astrophysics Data System (ADS)

    Zhou, Xinjian; Moran-Mirabal, Jose; Craighead, Harold; McEuen, Paul

    2007-03-01

    We form supported lipid bilayers on single-walled carbon nanotubes and use this hybrid structure to probe the properties of lipid membranes and their functional constituents. We first demonstrate membrane continuity and lipid diffusion over the nanotube. A membrane-bound tetanus toxin protein, on the other hand, sees the nanotube as a diffusion barrier whose strength depends on the diameter of the nanotube. Finally, we present results on the electrical detection of specific binding of streptavidin to biotinylated lipids with nanotube field effect transistors. Possible techniques to extract dynamic information about the protein binding events will also be discussed.

  19. Nanomechanical Energy Storage in Twisted Nanotube Ropes

    NASA Astrophysics Data System (ADS)

    Teich, David; Fthenakis, Zacharias G.; Seifert, Gotthard; Tománek, David

    2012-12-01

    We determine the deformation energetics and energy density of twisted carbon nanotubes and nanotube ropes that effectively constitute a torsional spring. Using ab initio and parametrized density functional calculations, we identify structural changes in these systems and determine their elastic limits. The deformation energy of twisted nanotube ropes contains contributions associated not only with twisting but also with stretching, bending, and compression of individual nanotubes. We quantify these energy contributions and show that their relative role changes with the number of nanotubes in the rope.

  20. Boron nitride nanotubes for spintronics.

    PubMed

    Dhungana, Kamal B; Pati, Ranjit

    2014-01-01

    With the end of Moore's law in sight, researchers are in search of an alternative approach to manipulate information. Spintronics or spin-based electronics, which uses the spin state of electrons to store, process and communicate information, offers exciting opportunities to sustain the current growth in the information industry. For example, the discovery of the giant magneto resistance (GMR) effect, which provides the foundation behind modern high density data storage devices, is an important success story of spintronics; GMR-based sensors have wide applications, ranging from automotive industry to biology. In recent years, with the tremendous progress in nanotechnology, spintronics has crossed the boundary of conventional, all metallic, solid state multi-layered structures to reach a new frontier, where nanostructures provide a pathway for the spin-carriers. Different materials such as organic and inorganic nanostructures are explored for possible applications in spintronics. In this short review, we focus on the boron nitride nanotube (BNNT), which has recently been explored for possible applications in spintronics. Unlike many organic materials, BNNTs offer higher thermal stability and higher resistance to oxidation. It has been reported that the metal-free fluorinated BNNT exhibits long range ferromagnetic spin ordering, which is stable at a temperature much higher than room temperature. Due to their large band gap, BNNTs are also explored as a tunnel magneto resistance device. In addition, the F-BNNT has recently been predicted as an ideal spin-filter. The purpose of this review is to highlight these recent progresses so that a concerted effort by both experimentalists and theorists can be carried out in the future to realize the true potential of BNNT-based spintronics. PMID:25248070

  1. Boron Nitride Nanotubes for Spintronics

    PubMed Central

    Dhungana, Kamal B.; Pati, Ranjit

    2014-01-01

    With the end of Moore's law in sight, researchers are in search of an alternative approach to manipulate information. Spintronics or spin-based electronics, which uses the spin state of electrons to store, process and communicate information, offers exciting opportunities to sustain the current growth in the information industry. For example, the discovery of the giant magneto resistance (GMR) effect, which provides the foundation behind modern high density data storage devices, is an important success story of spintronics; GMR-based sensors have wide applications, ranging from automotive industry to biology. In recent years, with the tremendous progress in nanotechnology, spintronics has crossed the boundary of conventional, all metallic, solid state multi-layered structures to reach a new frontier, where nanostructures provide a pathway for the spin-carriers. Different materials such as organic and inorganic nanostructures are explored for possible applications in spintronics. In this short review, we focus on the boron nitride nanotube (BNNT), which has recently been explored for possible applications in spintronics. Unlike many organic materials, BNNTs offer higher thermal stability and higher resistance to oxidation. It has been reported that the metal-free fluorinated BNNT exhibits long range ferromagnetic spin ordering, which is stable at a temperature much higher than room temperature. Due to their large band gap, BNNTs are also explored as a tunnel magneto resistance device. In addition, the F-BNNT has recently been predicted as an ideal spin-filter. The purpose of this review is to highlight these recent progresses so that a concerted effort by both experimentalists and theorists can be carried out in the future to realize the true potential of BNNT-based spintronics. PMID:25248070

  2. All carbon nanotubes are not created equal

    SciTech Connect

    Geohegan, David B; Puretzky, Alexander A; Rouleau, Christopher M

    2010-01-01

    This chapter presents the various factors that enter into consideration when choosing the source of carbon nanotubes for a specific application. Carbon nanotubes are giant molecules made of pure carbon. They have captured the imagination of the scientific community by the unique structure that provides superior physical, chemical, and electrical properties. However, a surprisingly wide disparity exists between the intrinsic properties determined under ideal conditions and the properties that carbon nanotubes exhibit in real world situations. The lack of uniformity in carbon nanotube properties is likely to be the main obstacle holding back the development of carbon nanotube applications. This tutorial addresses the nonuniformity of carbon nanotube properties from the synthesis standpoint. This synthesis-related nonuniformity is on top of the intrinsic chirality distribution that gives the ~1:2 ratio of metallic to semiconducting nanotubes. From the standpoint of carbon bonding chemistry the variation in the quality and reproducibility of carbon nanotube materials is not unexpected. It is an intrinsic feature that is related to the metastability of carbon structures. The extent to which this effect is manifested in carbon nanotube formation is governed by the type and the kinetics of the carbon nanotube synthesis reaction. Addressing this variation is critical if nanotubes are to live up to the potential already demonstrated by their phenomenal physical properties.

  3. Effect of Carbon Nanotubes on Mammalian Cells

    NASA Astrophysics Data System (ADS)

    Chen, Michelle; Ahmed, Asma; Black, Melanie; Kawamoto, Nicole; Lucas, Jessica; Pagala, Armie; Pham, Tram; Stankiewicz, Sara; Chen, Howard

    2010-03-01

    Carbon Nanotubes possess extraordinary electrical, mechanical, and thermal properties. Research on applying the carbon nanotubes for ultrasensitive detection, disease diagnosis, and drug delivery is rapidly developing. While the fundamental and technological findings on carbon nanotubes show great promise, it is extremely important to investigate the effect of the carbon nanotubes on human health. In our experiments, we introduce purified carbon nanotubes in suspension to ovary cells cultured from Hamsters. These cells are chosen since they show robust morphological changes associated with cytotoxicity that can easily be observed under a light microscope. We will discuss the toxicity of carbon nanotubes by characterizing the cell morphology and viability as a function of time and the concentration of carbon nanotube suspension.

  4. Architecture and Characteristics of Bacterial Nanotubes.

    PubMed

    Dubey, Gyanendra P; Malli Mohan, Ganesh Babu; Dubrovsky, Anna; Amen, Triana; Tsipshtein, Shai; Rouvinski, Alex; Rosenberg, Alex; Kaganovich, Daniel; Sherman, Eilon; Medalia, Ohad; Ben-Yehuda, Sigal

    2016-02-22

    Bacteria display an array of contact-dependent interaction systems that have evolved to facilitate direct cell-to-cell communication. We have previously identified a mode of bacterial communication mediated by nanotubes bridging neighboring cells. Here, we elucidate nanotube architecture, dynamics, and molecular components. Utilizing Bacillus subtilis as a model organism, we found that at low cell density, nanotubes exhibit remarkable complexity, existing as both intercellular tubes and extending tubes, with the latter frequently surrounding the cells in a "root-like" fashion. Observing nanotube formation in real time showed that these structures are formed in the course of minutes, displaying rapid movements. Utilizing a combination of super-resolution, light, and electron microscopy, we revealed that nanotubes are composed of chains of membranous segments harboring a continuous lumen. Furthermore, we discovered that a conserved calcineurin-like protein, YmdB, presents in nanotubes and is required for both nanotube production and intercellular molecular trade. PMID:26906740

  5. Carbon Nanotube Material Quality Assessment

    NASA Technical Reports Server (NTRS)

    Yowell, Leonard; Arepalli, Sivaram; Sosa, Edward; Niolaev, Pavel; Gorelik, Olga

    2006-01-01

    The nanomaterial activities at NASA Johnson Space Center focus on carbon nanotube production, characterization and their applications for aerospace systems. Single wall carbon nanotubes are produced by arc and laser methods. Characterization of the nanotube material is performed using the NASA JSC protocol developed by combining analytical techniques of SEM, TEM, UV-VIS-NIR absorption, Raman, and TGA. A possible addition of other techniques such as XPS, and ICP to the existing protocol will be discussed. Changes in the quality of the material collected in different regions of the arc and laser production chambers is assessed using the original JSC protocol. The observed variations indicate different growth conditions in different regions of the production chambers.

  6. Plasma CVD of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Delzeit, Lance; Cruden, B.; Hash, D.; Meyyappan, M.; DeVincenzi, Donald L. (Technical Monitor)

    2001-01-01

    Carbon nanotubes(CNT) exhibit remarkable mechanical and unique electronic properties and thus have created excitement in the research community about their potential in electronics, computing, sensor and structural applications. Realization of these applications critically depends on the ability to control the properties(such as diameter, chirality) as well purity. We have investigated CNT growth using an inductively coupled plasma(ICP) process using hydrocarbon feedstock. The catalyst required for nanotube growth consists of thin sputtered layers of aluminum and iron(10 nm each) and aligned carbon nanotubes have been obtained. Optical emission diagnostics as well as a plasma modeling effort have been undertaken to understand growth mechanisms. This presentation will discuss growth characteristics under various pressure, power and feedgas compositions and our understanding from modeling and diagnostics.

  7. Carbon nanotube devices: Sorting, Assembling, Characterizing

    NASA Astrophysics Data System (ADS)

    Krupke, Ralph

    2009-03-01

    Carbon nanotubes have been studied extensively over the last decade. Various exceptional properties have been revealed which still drive the vision about using carbon nanotube in future electronics, for instance as molecular nanoscale transistors or electromigration resistant interconnects. For many years a major obstacle was the inability to grow nanotubes with defined dimensions (length, diameter) and electronic properties (metallic,semiconducting). Recently those problems have been solved to a large extent by advanced sorting techniques. Today the challenge is to assemble nanotubes devices with defined properties to form a complex circuitry. As progress is made in making highly-integrated nanotube device arrays new characterization techniques have to be developed which allow testing large number of devices within an acceptable time. Along this line I will report on the state-of-the-art of sorting of carbon nanotube, as a base for nanotube device fabrication [1]. I will then explain our strategy to assemble high-density arrays of nanotube devices [2] and discuss a new characterization technique for nanotube devices [3]. Finally I will introduce a novel device engineering tool [4]. [4pt] [1] R. Krupke et al., ``Separation techniques for carbon nanotubes'' in Chemistry of Carbon Nanotubes, p.129-139, American Scientific Publishers 2008[0pt] [2] A. Vijayaraghavan et al., ``Ultra-Large-Scale Directed Assembly of Single-Walled Carbon Nanotube Devices'', Nano Lett. 7 (2007) 1556-1560[0pt] [3] A. Vijayaraghavan et al., ``Imaging Electronic Structure of Carbon Nanotubes by Voltage-Contrast Scanning Electron Microscopy'', Nano Resarch 1 (2008) 321-332[0pt] [4] C. W. Marquardt et al., ``Reversible metal-insulator transitions in metallic single-walled carbon nanotubes'', Nano Lett. 9 (2008) 2767-2772

  8. Quantum transport in carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Laird, Edward A.; Kuemmeth, Ferdinand; Steele, Gary A.; Grove-Rasmussen, Kasper; Nygârd, Jesper; Flensberg, Karsten; Kouwenhoven, Leo P.

    2015-07-01

    Carbon nanotubes are a versatile material in which many aspects of condensed matter physics come together. Recent discoveries have uncovered new phenomena that completely change our understanding of transport in these devices, especially the role of the spin and valley degrees of freedom. This review describes the modern understanding of transport through nanotube devices. Unlike in conventional semiconductors, electrons in nanotubes have two angular momentum quantum numbers, arising from spin and valley freedom. The interplay between the two is the focus of this review. The energy levels associated with each degree of freedom, and the spin-orbit coupling between them, are explained, together with their consequences for transport measurements through nanotube quantum dots. In double quantum dots, the combination of quantum numbers modifies the selection rules of Pauli blockade. This can be exploited to read out spin and valley qubits and to measure the decay of these states through coupling to nuclear spins and phonons. A second unique property of carbon nanotubes is that the combination of valley freedom and electron-electron interactions in one dimension strongly modifies their transport behavior. Interaction between electrons inside and outside a quantum dot is manifested in SU(4) Kondo behavior and level renormalization. Interaction within a dot leads to Wigner molecules and more complex correlated states. This review takes an experimental perspective informed by recent advances in theory. As well as the well-understood overall picture, open questions for the field are also clearly stated. These advances position nanotubes as a leading system for the study of spin and valley physics in one dimension where electronic disorder and hyperfine interaction can both be reduced to a low level.

  9. Novel Nanotube Manufacturing Streamlines Production

    NASA Technical Reports Server (NTRS)

    2007-01-01

    Nanotubes have novel qualities that make them uniquely qualified for a plethora of uses, including applications in electronics, optics, and other scientific and industrial fields. The NASA process for creating these nanostructures involves using helium arc welding to vaporize an amorphous carbon rod and then form nanotubes by depositing the vapor onto a water-cooled carbon cathode, which then yields bundles, or ropes, of single-walled nanotubes at a rate of 2 grams per hour using a single setup. This eliminates costs associated with the use of metal catalysts, including the cost of product purification, resulting in a relatively inexpensive, high-quality, very pure end product. While managing to be less expensive, safer, and simpler, the process also increases the quality of the nanotubes. Goddard's Innovative Partnerships Program (IPP) Office promoted the technology, and in 2005, Boise-based Idaho Space Materials Inc. (ISM) was formed and applied for a nonexclusive license for the single-walled carbon nanotube (SWCNT) manufacturing technology. ISM commercialized its products, and the inexpensive, robust nanotubes are now in the hands of the scientists who will create the next generation of composite polymers, metals, and ceramics that will impact the way we live. In fact, researchers are examining ways for these newfound materials to be used in the manufacture of transistors and fuel cells, large screen televisions, ultra-sensitive sensors, high-resolution atomic force microscopy probes, supercapacitors, transparent conducting films, drug carriers, catalysts, and advanced composite materials, to name just a few of the myriad technologies to benefit.

  10. Endohedral impurities in carbon nanotubes.

    PubMed

    Clougherty, Dennis P

    2003-01-24

    A generalization of the Anderson model that includes pseudo-Jahn-Teller impurity coupling is proposed to describe distortions of an endohedral impurity in a carbon nanotube. Within mean-field theory, spontaneous axial symmetry breaking is found when the vibronic coupling strength g exceeds a critical value. The effective potential is found to have O(2) symmetry, in agreement with numerical calculations. For metallic zigzag nanotubes endohedrally doped with transition metals in the dilute limit, the low-energy properties of the system may display two-channel Kondo behavior; however, strong vibronic coupling is seen to exponentially suppress the Kondo energy scale. PMID:12570507

  11. Endohedral Impurities in Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Clougherty, Dennis P.

    2003-01-01

    A generalization of the Anderson model that includes pseudo-Jahn-Teller impurity coupling is proposed to describe distortions of an endohedral impurity in a carbon nanotube. Within mean-field theory, spontaneous axial symmetry breaking is found when the vibronic coupling strength g exceeds a critical value. The effective potential is found to have O(2) symmetry, in agreement with numerical calculations. For metallic zigzag nanotubes endohedrally doped with transition metals in the dilute limit, the low-energy properties of the system may display two-channel Kondo behavior; however, strong vibronic coupling is seen to exponentially suppress the Kondo energy scale.

  12. CMOS Integrated Carbon Nanotube Sensor

    SciTech Connect

    Perez, M. S.; Lerner, B.; Boselli, A.; Lamagna, A.; Obregon, P. D. Pareja; Julian, P. M.; Mandolesi, P. S.; Buffa, F. A.

    2009-05-23

    Recently carbon nanotubes (CNTs) have been gaining their importance as sensors for gases, temperature and chemicals. Advances in fabrication processes simplify the formation of CNT sensor on silicon substrate. We have integrated single wall carbon nanotubes (SWCNTs) with complementary metal oxide semiconductor process (CMOS) to produce a chip sensor system. The sensor prototype was designed and fabricated using a 0.30 um CMOS process. The main advantage is that the device has a voltage amplifier so the electrical measure can be taken and amplified inside the sensor. When the conductance of the SWCNTs varies in response to media changes, this is observed as a variation in the output tension accordingly.

  13. Polymerized nanotube structures new zeolites?

    NASA Astrophysics Data System (ADS)

    Chernozatonskii, Leonid A.

    1998-11-01

    Polymers of single-wall carbon nanotubes - possible new zeolites - are modeled by molecular mechanics (MM2 calculation method). The polymerization at issue occurs by bonding of 6 sp 3 atomic pairs in each nanotube unit cell with similar atomic pairs located on 6 neighboring tubes like 2+2 cycloaddition in a rhombic two-dimensional C 60 polymer. It is shown these bonding in armchair ( n, n) SWNT ropes ( n=6, 8, 10, 12) changes positive radial curvature of tube segments to a negative one.

  14. EDITORIAL: Focus on Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    2003-09-01

    The study of carbon nanotubes, since their discovery by Iijima in 1991, has become a full research field with significant contributions from all areas of research in solid-state and molecular physics and also from chemistry. This Focus Issue in New Journal of Physics reflects this active research, and presents articles detailing significant advances in the production of carbon nanotubes, the study of their mechanical and vibrational properties, electronic properties and optical transitions, and electrical and transport properties. Fundamental research, both theoretical and experimental, represents part of this progress. The potential applications of nanotubes will rely on the progress made in understanding their fundamental physics and chemistry, as presented here. We believe this Focus Issue will be an excellent guide for both beginners and experts in the research field of carbon nanotubes. It has been a great pleasure to edit the many excellent contributions from Europe, Japan, and the US, as well from a number of other countries, and to witness the remarkable effort put into the manuscripts by the contributors. We thank all the authors and referees involved in the process. In particular, we would like to express our gratitude to Alexander Bradshaw, who invited us put together this Focus Issue, and to Tim Smith and the New Journal of Physics staff for their extremely efficient handling of the manuscripts. Focus on Carbon Nanotubes Contents Transport theory of carbon nanotube Y junctions R Egger, B Trauzettel, S Chen and F Siano The tubular conical helix of graphitic boron nitride F F Xu, Y Bando and D Golberg Formation pathways for single-wall carbon nanotube multiterminal junctions Inna Ponomareva, Leonid A Chernozatonskii, Antonis N Andriotis and Madhu Menon Synthesis and manipulation of carbon nanotubes J W Seo, E Couteau, P Umek, K Hernadi, P Marcoux, B Lukic, Cs Mikó, M Milas, R Gaál and L Forró Transitional behaviour in the transformation from active end

  15. Photodetector based on carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Pavlov, A.; Kitsyuk, E.; Ryazanov, R.; Timoshenkov, V.; Adamov, Y.

    2015-09-01

    Photodetector based on carbon nanotubes (CNT) was investigated. Sensors were done on quartz and silicon susbtrate. Samples of photodetectors sensors were produced by planar technology. This technology included deposition of first metal layer (Al), lithography for pads formation, etching, and formation of local catalyst area by inverse lithography. Vertically-aligned multi-wall carbon nanotubes were directly synthesized on substrate by PECVD method. I-V analysis and spectrum sensitivity of photodetector were investigated for 0.4 μm - 1.2 μm wavelength. Resistivity of CNT layers over temperature was detected in the range of -20°C to 100°C.

  16. Branchy alumina nanotubes

    NASA Astrophysics Data System (ADS)

    Zou, Jianping; Pu, Lin; Bao, Ximao; Feng, Duan

    2002-02-01

    Branchy alumina nanotubes (bANTs) have been shown to exist in aluminum oxide. Electron-beam evaporated 400 nm Al film on Si substrate is stepwise anodized in dilute sulfuric acid under the constant dc voltage 40 V at 10.0 °C. This electrochemical-anodizing route resulted in the formation of individual bANTs. Transmission electron microscopy showed that the length of the bANTs was around 450 nm, and the inner diameter was around 10-20 nm. We deduced that the bANTs, the completely detached multibranchy cells of anodic porous alumina (APA) film, should be evolved from the stagnant cells of the APA mother film. The bANTs may be used as templates in fabrication of individual branchy nanoscale cables, jacks, and heterojunctions. The proposed formation mechanisms of the bANTs and the stagnant cells should give some insights into the long-standing problem of APA film, i.e., the self-ordering mechanism of the cells arrangement in porous anodization of aluminum.

  17. Carbon Nanotube Purification

    NASA Technical Reports Server (NTRS)

    Delzeit, Lance D. (Inventor); Delzeit, Clement J. (Inventor)

    2005-01-01

    A method for cleaning or otherwise removing amorphous carbon and other residues that arise in growth of a carbon nanotube (CNT) array. The CNT array is exposed to a plurality of hydroxyls or hydrogen, produced from a selected vapor or liquid source such as H2O or H2O2. and the hydroxyls or hydrogen (neutral or electrically charged) react with the residues to produce partly or fully dissolved or hydrogenated or hydroxylizated products that can be removed or separated from the CNT array. The hydroxyls or hydrogen can be produced by heating the CNT array, residue and selected vapor or liquid source or by application of an electromagnetic excitation signal with a selected frequency or range of frequencies to dissociate the selected vapor or liquid. The excitation frequency can be chirped to cover a selected range of frequencies corresponding to dissociation of the selected vapor or liquid. Sonication may be uscd to supplement dissociation of the H2O and/or H2O2.

  18. Coupling of semiconductor carbon nanotubes emission with silicon photonic micro ring resonators

    NASA Astrophysics Data System (ADS)

    Sarti, Francesco; Caselli, Niccolò; La China, Federico; Biccari, Francesco; Torrini, Ughetta; Intonti, Francesca; Vinattieri, Anna; Durán-Valdeiglesias, Elena; Zhang, Weiwei; Noury, Adrien; Alonso-Ramos, Carlos; Hoang, ThiHong Cam; Serna, Samuel; Le Roux, Xavier; Cassan, Eric; Izard, Nicolas; Yang, Hongliu; Bezugly, Viktor; Cuniberti, Gianaurelio; Filoramo, Arianna; Vivien, Laurent; Gurioli, Massimo

    2016-05-01

    Hybrid structures are needed to fully exploit the great advantages of Si photonics and several approaches have been addressed where Si devices are bonded to different materials and nanostructures. Here we study the use of semiconductor carbon nanotubes for emission in the 1300 nm wavelength range to functionalize Si photonic structures in view of optoelectronic applications. The Si micro-rings are fully characterized by near field forward resonant scattering with 100 nm resolution. We show that both TE and TM modes can be addressed on the top of the micro-rings in a vectorial imaging of the in-plane polarization components. We coupled the Si micro-resonators with selected carbon nanotubes for high photoluminescence emission. Coupling nanotubes with the evanescent tails in air of the electric field localized in the photonic modes of the micro-resonators is demonstrated by sharp resonances over imposed to the nanotube emission bands. By mapping the Si and the nanotube emission we demonstrate that strong enhancement of the nanotube photoluminescence can be achieved both in the photonic modes of micro-disks and slot micro-rings, whenever the spatial overlap between nano-emitters and photonic modes is fulfilled.

  19. Separated Carbon Nanotube Macroelectronics for Active Matrix Organic Light-Emitting Diode Displays

    NASA Astrophysics Data System (ADS)

    Fu, Yue; Zhang, Jialu; Wang, Chuan; Chen, Pochiang; Zhou, Chongwu

    2012-02-01

    Active matrix organic light-emitting diode (AMOLED) display holds great potential for the next generation visual technologies due to its high light efficiency, flexibility, lightweight, and low-temperature processing. However, suitable thin-film transistors (TFTs) are required to realize the advantages of AMOLED. Pre-separated, semiconducting enriched carbon nanotubes are excellent candidates for this purpose because of their excellent mobility, high percentage of semiconducting nanotubes, and room-temperature processing compatibility. Here we report, for the first time, the demonstration of AMOLED displays driven by separated nanotube thin-film transistors (SN-TFTs) including key technology components such as large-scale high-yield fabrication of devices with superior performance, carbon nanotube film density optimization, bilayer gate dielectric for improved substrate adhesion to the deposited nanotube film, and the demonstration of monolithically integrated AMOLED display elements with 500 pixels driven by 1000 SN-TFTs. Our approach can serve as the critical foundation for future nanotube-based thin-film display electronics.

  20. Separated carbon nanotube macroelectronics for active matrix organic light-emitting diode displays.

    PubMed

    Zhang, Jialu; Fu, Yue; Wang, Chuan; Chen, Po-Chiang; Liu, Zhiwei; Wei, Wei; Wu, Chao; Thompson, Mark E; Zhou, Chongwu

    2011-11-01

    Active matrix organic light-emitting diode (AMOLED) display holds great potential for the next generation visual technologies due to its high light efficiency, flexibility, lightweight, and low-temperature processing. However, suitable thin-film transistors (TFTs) are required to realize the advantages of AMOLED. Preseparated, semiconducting enriched carbon nanotubes are excellent candidates for this purpose because of their excellent mobility, high percentage of semiconducting nanotubes, and room-temperature processing compatibility. Here we report, for the first time, the demonstration of AMOLED displays driven by separated nanotube thin-film transistors (SN-TFTs) including key technology components, such as large-scale high-yield fabrication of devices with superior performance, carbon nanotube film density optimization, bilayer gate dielectric for improved substrate adhesion to the deposited nanotube film, and the demonstration of monolithically integrated AMOLED display elements with 500 pixels driven by 1000 SN-TFTs. Our approach can serve as the critical foundation for future nanotube-based thin-film display electronics. PMID:21942351

  1. Controlling the Physical Dimensions of Peptide Nanotubes by Supramolecular Polymer Coassembly.

    PubMed

    Adler-Abramovich, Lihi; Marco, Pini; Arnon, Zohar A; Creasey, Rhiannon C G; Michaels, Thomas C T; Levin, Aviad; Scurr, David J; Roberts, Clive J; Knowles, Tuomas P J; Tendler, Saul J B; Gazit, Ehud

    2016-08-23

    Molecular self-assembly of peptides into ordered nanotubes is highly important for various technological applications. Very short peptide building blocks, as short as dipeptides, can form assemblies with unique mechanical, optical, piezoelectric, and semiconductive properties. Yet, the control over nanotube length in solution has remained challenging, due to the inherent sequential self-assembly mechanism. Here, in line with polymer chemistry paradigms, we applied a supramolecular polymer coassembly methodology to modulate peptide nanotube elongation. Utilizing this approach, we achieved a narrow, controllable nanotube length distribution by adjusting the molecular ratio of the diphenylalanine assembly unit and its end-capped analogue. Kinetic analysis suggested a slower coassembly organization process as compared to the self-assembly dynamics of each of the building blocks separately. This is consistent with a hierarchal arrangement of the peptide moieties within the coassemblies. Mass spectrometry analysis demonstrated the bimolecular composition of the coassembled nanostructures. Moreover, the peptide nanotubes' length distribution, as determined by electron microscopy, was shown to fit a fragmentation kinetics model. Our results reveal a simple and efficient mechanism for the control of nanotube sizes through the coassembly of peptide entities at various ratios, allowing for the desired end-product formation. This dynamic size control offers tools for molecular engineering at the nanoscale exploiting the advantages of molecular coassembly. PMID:27351519

  2. Quantum fluctuations increase the self-diffusive motion of para-hydrogen in narrow carbon nanotubes.

    PubMed

    Kowalczyk, Piotr; Gauden, Piotr A; Terzyk, Artur P; Furmaniak, Sylwester

    2011-05-28

    Quantum fluctuations significantly increase the self-diffusive motion of para-hydrogen adsorbed in narrow carbon nanotubes at 30 K comparing to its classical counterpart. Rigorous Feynman's path integral calculations reveal that self-diffusive motion of para-hydrogen in a narrow (6,6) carbon nanotube at 30 K and pore densities below ∼29 mmol cm(-3) is one order of magnitude faster than the classical counterpart. We find that the zero-point energy and tunneling significantly smoothed out the free energy landscape of para-hydrogen molecules adsorbed in a narrow (6,6) carbon nanotube. This promotes a delocalization of the confined para-hydrogen at 30 K (i.e., population of unclassical paths due to quantum effects). Contrary the self-diffusive motion of classical para-hydrogen molecules in a narrow (6,6) carbon nanotube at 30 K is very slow. This is because classical para-hydrogen molecules undergo highly correlated movement when their collision diameter approached the carbon nanotube size (i.e., anomalous diffusion in quasi-one dimensional pores). On the basis of current results we predict that narrow single-walled carbon nanotubes are promising nanoporous molecular sieves being able to separate para-hydrogen molecules from mixtures of classical particles at cryogenic temperatures. PMID:21503294

  3. Wafer-scale monodomain films of spontaneously aligned single-walled carbon nanotubes.

    PubMed

    He, Xiaowei; Gao, Weilu; Xie, Lijuan; Li, Bo; Zhang, Qi; Lei, Sidong; Robinson, John M; Hároz, Erik H; Doorn, Stephen K; Wang, Weipeng; Vajtai, Robert; Ajayan, Pulickel M; Adams, W Wade; Hauge, Robert H; Kono, Junichiro

    2016-07-01

    The one-dimensional character of electrons, phonons and excitons in individual single-walled carbon nanotubes leads to extremely anisotropic electronic, thermal and optical properties. However, despite significant efforts to develop ways to produce large-scale architectures of aligned nanotubes, macroscopic manifestations of such properties remain limited. Here, we show that large (>cm(2)) monodomain films of aligned single-walled carbon nanotubes can be prepared using slow vacuum filtration. The produced films are globally aligned within ±1.5° (a nematic order parameter of ∼1) and are highly packed, containing 1 × 10(6) nanotubes in a cross-sectional area of 1 μm(2). The method works for nanotubes synthesized by various methods, and film thickness is controllable from a few nanometres to ∼100 nm. We use the approach to create ideal polarizers in the terahertz frequency range and, by combining the method with recently developed sorting techniques, highly aligned and chirality-enriched nanotube thin-film devices. Semiconductor-enriched devices exhibit polarized light emission and polarization-dependent photocurrent, as well as anisotropic conductivities and transistor action with high on/off ratios. PMID:27043199

  4. Wafer-scale monodomain films of spontaneously aligned single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    He, Xiaowei; Gao, Weilu; Xie, Lijuan; Li, Bo; Zhang, Qi; Lei, Sidong; Robinson, John M.; Hároz, Erik H.; Doorn, Stephen K.; Wang, Weipeng; Vajtai, Robert; Ajayan, Pulickel M.; Adams, W. Wade; Hauge, Robert H.; Kono, Junichiro

    2016-07-01

    The one-dimensional character of electrons, phonons and excitons in individual single-walled carbon nanotubes leads to extremely anisotropic electronic, thermal and optical properties. However, despite significant efforts to develop ways to produce large-scale architectures of aligned nanotubes, macroscopic manifestations of such properties remain limited. Here, we show that large (>cm2) monodomain films of aligned single-walled carbon nanotubes can be prepared using slow vacuum filtration. The produced films are globally aligned within ±1.5° (a nematic order parameter of ∼1) and are highly packed, containing 1 × 106 nanotubes in a cross-sectional area of 1 μm2. The method works for nanotubes synthesized by various methods, and film thickness is controllable from a few nanometres to ∼100 nm. We use the approach to create ideal polarizers in the terahertz frequency range and, by combining the method with recently developed sorting techniques, highly aligned and chirality-enriched nanotube thin-film devices. Semiconductor-enriched devices exhibit polarized light emission and polarization-dependent photocurrent, as well as anisotropic conductivities and transistor action with high on/off ratios.

  5. Fabrication of selenium-deposited and chitosan-coated titania nanotubes with anticancer and antibacterial properties.

    PubMed

    Chen, Xiuyong; Cai, Kaiyong; Fang, Jiajia; Lai, Min; Hou, Yanhua; Li, Jinghua; Luo, Zhong; Hu, Yan; Tang, Liling

    2013-03-01

    To exploit titanium materials with anticancer and antibacterial properties, TiO(2) nanotubes arrays as nanoreservoirs for deposition of selenium were generated onto titanium substrates and then covered with chitosan layer. The deposition of selenium in TiO(2) nanotubes was performed with electrodeposition. The physical properties (surface morphologies, chemical compositions and wettability) of the substrates were characterized by field-emission scanning electron microscopy (FE-SEM) equipped with energy dispersive X-ray spectroscopy (EDS) and contact angle measurement, respectively. The growth behaviors of both healthy osteoblasts and cancerous osteoblasts on the substrates were investigated in vitro. The selenium-deposited and chitosan-coated TiO(2) nanotubes substrates (TiO(2) nanotubes-Se-Chi) demonstrated great potential for promoting the proliferation of healthy osteoblasts and inhibiting the growth of cancerous osteoblasts. Meanwhile, the TiO(2) nanotubes-Se-Chi substrates displayed a sustained release of selenium for 21 days. The antibacterial properties of the prepared substrates were evaluated with Escherichia coli (E. coli). The result showed that TiO(2) nanotubes-Se-Chi substrates had long term antibacterial capacity. The approach in this study provides an alternative to fabricate anticancer and antibacterial titanium-based implants for potential clinical application. PMID:23201732

  6. DNA nanotubes and helical nanotapes via self-assembly of ssDNA-amphiphiles.

    PubMed

    Pearce, Timothy R; Kokkoli, Efrosini

    2015-01-01

    DNA nanotubes were created using molecular self-assembly of single-stranded DNA (ssDNA)-amphiphiles composed of a hydrophobic dialkyl tail and polycarbon spacer and a hydrophilic ssDNA headgroup. The nanotube structures were formed by bilayers of amphiphiles, with the hydrophobic components forming an inner layer that was shielded from the aqueous solvent by an outer layer of ssDNA. The nanotubes appeared to form via an assembly process that included transitions from twisted nanotapes to helical nanotapes to nanotubes. Amphiphiles that contained different ssDNA headgroups were created to explore the effect of the length and secondary structure of the ssDNA headgroup on the self-assembly behavior of the amphiphiles in the presence and absence of the polycarbon spacer. It was found that nanotubes could be formed using a variety of headgroup lengths and sequences. The ability to create nanotubes via ssDNA-amphiphile self-assembly offers an alternative to the other purely DNA-based approaches like DNA origami and DNA tile assembly for constructing these structures and may be useful for applications in drug delivery, biosensing, and electronics. PMID:25370121

  7. Modeling of Interfacial Modification Effects on Thermal Conductivity of Carbon Nanotube Composites

    NASA Technical Reports Server (NTRS)

    Clancy, Thomas C.; Gates, Thomas S.

    2006-01-01

    The effect of functionalization of carbon nanotubes on the thermal conductivity of nanocomposites has been studied using a multi-scale modeling approach. These results predict that grafting linear hydrocarbon chains to the surface of a single wall carbon nanotube with covalent chemical bonds should result in a significant increase in the thermal conductivity of these nanocomposites. This is due to the decrease in the interfacial thermal (Kapitza) resistance between the single wall carbon nanotube and the surrounding polymer matrix upon chemical functionalization. The nanocomposites studied here consist of single wall carbon nanotubes in a bulk poly(ethylene vinyl acetate) matrix. The nanotubes are functionalized by end-grafting linear hydrocarbon chains of varying length to the surface of the nanotube. The effect which this functionalization has on the interfacial thermal resistance is studied by molecular dynamics simulation. Interfacial thermal resistance values are calculated for a range of chemical grafting densities and with several chain lengths. These results are subsequently used in an analytical model to predict the resulting effect on the bulk thermal conductivity of the nanocomposite.

  8. Modified carbon nanotubes and methods of forming carbon nanotubes

    DOEpatents

    Heintz, Amy M.; Risser, Steven; Elhard, Joel D.; Moore, Bryon P.; Liu, Tao; Vijayendran, Bhima R.

    2016-06-14

    In this invention, processes which can be used to achieve stable doped carbon nanotubes are disclosed. Preferred CNT structures and morphologies for achieving maximum doping effects are also described. Dopant formulations and methods for achieving doping of a broad distribution of tube types are also described.

  9. Control of the Diameter and Chiral Angle Distributions during Production of Single-Wall Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Nikolaev, Pavel

    2009-01-01

    Many applications of single wall carbon nanotubes (SWCNT), especially in microelectronics, will benefit from use of certain (n,m) nanotube types (metallic, small gap semiconductor, etc.) Especially fascinating is the possibility of quantum conductors that require metallic armchair nanotubes. However, as produced SWCNT samples are polydisperse, with many (n,m) types present and typical approx.1:2 metal/semiconductor ratio. Nanotube nucleation models predict that armchair nuclei are energetically preferential due to formation of partial triple bonds along the armchair edge. However, nuclei can not reach any meaningful thermal equilibrium in a rapidly expanding and cooling plume of carbon clusters, leading to polydispersity. In the present work, SWCNTs were produced by a pulsed laser vaporization (PLV) technique. The carbon vapor plume cooling rate was either increased by change in the oven temperature (expansion into colder gas), or decreased via "warm-up" with a laser pulse at the moment of nucleation. The effect of oven temperature and "warm-up" on nanotube type population was studied via photoluminescence, UV-Vis-NIR absorption and Raman spectroscopy. It was found that reduced temperatures leads to smaller average diameters, progressively narrower diameter distributions, and some preference toward armchair structures. "Warm-up" shifts nanotube population towards arm-chair structures as well, but the effect is small. Possible improvement of the "warm-up" approach to produce armchair SWCNTs will be discussed. These results demonstrate that PLV production technique can provide at least partial control over the nanotube (n,m) population. In addition, these results have implications for the understanding the nanotube nucleation mechanism in the laser oven.

  10. Carbon nanotube transistors, sensors, and beyond

    NASA Astrophysics Data System (ADS)

    Zhou, Xinjian

    Carbon nanotubes are tiny hollow cylinders, made from a single graphene sheet, that possess many amazing properties. Another reason why nanotubes have generated intense research activities from scientists of various disciplines is they represent a new class of materials for the study of one-dimensional physics. In this thesis we investigate the electrical transport of semiconducting single-walled carbon nanotubes and their potential applications as biological sensors. Electrons have been predicted, by theoretical physicists, to go through nanotubes without much resistance. But this has not been properly quantified experimentally, and the origin of the routinely observed large resistance in nanotubes is not clear. In this thesis we show that in moderate long high quality nanotubes the electrical transport is limited by electron-phonon scattering. Systematic studies are carried out using many devices of different diameters at various temperatures. The resistance and inverse of peak mobility are observed to decrease linearly with temperature, indicating the influence of phonons. The conductance and peak mobility scales with nanotube diameters also, in a linear fashion and quadratic fashion respectively. Based on electron-phonon scattering, a theory model is developed that can not only predict how the resistance changes with gate voltage but also explain the observed temperature and diameter dependence. This work clarifies the nature of electrical transport in nanotubes and sets a performance limit of nanotube devices in diffusive regime. The electrical transport in nanotubes is extremely sensitive to local electrostatic environment due to their small size, large surface to volume ratio and high mobility, making nanotubes ideal key elements in biological sensors. In the second part of this thesis, we integrate nanotubes with supported lipid bilayers, mimic structures of cell membranes, and use this platform as a way to introduce biomolecules into the vicinity of

  11. Biochemical Sensors Using Carbon Nanotube Arrays

    NASA Technical Reports Server (NTRS)

    Li, Jun (Inventor); Meyyappan, Meyya (Inventor); Cassell, Alan M. (Inventor)

    2011-01-01

    Method and system for detecting presence of biomolecules in a selected subset, or in each of several selected subsets, in a fluid. Each of an array of two or more carbon nanotubes ("CNTs") is connected at a first CNT end to one or more electronics devices, each of which senses a selected electrochemical signal that is generated when a target biomolecule in the selected subset becomes attached to a functionalized second end of the CNT, which is covalently bonded with a probe molecule. This approach indicates when target biomolecules in the selected subset are present and indicates presence or absence of target biomolecules in two or more selected subsets. Alternatively, presence of absence of an analyte can be detected.

  12. Thermal Conductivity of Carbon Nanotube Composite Films

    NASA Technical Reports Server (NTRS)

    Ngo, Quoc; Cruden, Brett A.; Cassell, Alan M.; Walker, Megan D.; Koehne, Jessica E.; Meyyappan, M.; Li, Jun; Yang, Cary Y.

    2004-01-01

    State-of-the-art ICs for microprocessors routinely dissipate power densities on the order of 50 W/sq cm. This large power is due to the localized heating of ICs operating at high frequencies, and must be managed for future high-frequency microelectronic applications. Our approach involves finding new and efficient thermally conductive materials. Exploiting carbon nanotube (CNT) films and composites for their superior axial thermal conductance properties has the potential for such an application requiring efficient heat transfer. In this work, we present thermal contact resistance measurement results for CNT and CNT-Cu composite films. It is shown that Cu-filled CNT arrays enhance thermal conductance when compared to as-grown CNT arrays. Furthermore, the CNT-Cu composite material provides a mechanically robust alternative to current IC packaging technology.

  13. Carbon nanotube atomic force microscopy probes

    NASA Astrophysics Data System (ADS)

    Yamanaka, Shigenobu; Okawa, Takashi; Akita, Seiji; Nakayama, Yoshikazu

    2005-05-01

    We have developed a carbon nanotube atomic force microscope probe. Because the carbon nanotube are well known to have high aspect ratios, small tip radii and high stiffness, carbon nanotube probes have a long lifetime and can be applied for the observation deep trenches. Carbon nanotubes were synthesized by a well-controlled DC arc discharge method, because this method can make nanotubes to have straight shape and high crystalline. The nanotubes were aligned on the knife-edge using an alternating current electrophoresis technique. A commercially available Si probe was used for the base of the nanotube probe. The nanotube probe was fabricated by the SEM manipulation method. The nanotube was then attached tightly to the Si probe by deposition of amorphous carbon. We demonstrate the measurement of a fine pith grating that has vertical walls. However, a carbon nanotube has a problem that is called "Sticking". The sticking is a chatter image on vertical like region in a sample. We solved this problem by applying 2 methods, 1. a large cantilever vibration amplitude in tapping mode, 2. an attractive mode measurement. We demonstrate the non-sticking images by these methods.

  14. Lipid Bilayers Covalently Anchored to Carbon Nanotubes

    PubMed Central

    Dayani, Yasaman; Malmstadt, Noah

    2012-01-01

    The unique physical and electrical properties of carbon nanotubes make them an exciting material for applications in various fields such as bioelectronics and biosensing. Due to the poor water solubility of carbon nanotubes, functionalization for such applications has been a challenge. Of particular need are functionalization methods for integrating carbon nanotubes with biomolecules and constructing novel hybrid nanostructures for bionanoelectronic applications. We present a novel method for the fabrication of dispersible, biocompatible carbon nanotube-based materials. Multi-walled carbon nanotubes (MWCNTs) are covalently modified with primary amine-bearing phospholipids in a carbodiimide-activated reaction. These modified carbon nanotubes have good dispersibility in nonpolar solvents. Fourier transform infrared (FTIR) spectroscopy shows peaks attributable to the formation of amide bonds between lipids and the nanotube surface. Simple sonication of lipid-modified nanotubes with other lipid molecules leads to the formation of a uniform lipid bilayer coating the nanotubes. These bilayer-coated nanotubes are highly dispersible and stable in aqueous solution. Confocal fluorescence microscopy shows labeled lipids on the surface of bilayer-modified nanotubes. Transmission electron microscopy (TEM) shows the morphology of dispersed bilayer-coated MWCNTs. Fluorescence quenching of lipid-coated MWCNTs confirms the bilayer configuration of the lipids on the nanotube surface and fluorescence anisotropy measurements show that the bilayer is fluid above the gel-to-liquid transition temperature. The membrane protein α-hemolysin spontaneously inserts into the MWCNT-supported bilayer, confirming the biomimetic membrane structure. These biomimetic nanostructures are a promising platform for the integration of carbon nanotube-based materials with biomolecules. PMID:22568448

  15. Gas Composition Sensing Using Carbon Nanotube Arrays

    NASA Technical Reports Server (NTRS)

    Li, Jing; Meyyappan, Meyya

    2012-01-01

    This innovation is a lightweight, small sensor for inert gases that consumes a relatively small amount of power and provides measurements that are as accurate as conventional approaches. The sensing approach is based on generating an electrical discharge and measuring the specific gas breakdown voltage associated with each gas present in a sample. An array of carbon nanotubes (CNTs) in a substrate is connected to a variable-pulse voltage source. The CNT tips are spaced appropriately from the second electrode maintained at a constant voltage. A sequence of voltage pulses is applied and a pulse discharge breakdown threshold voltage is estimated for one or more gas components, from an analysis of the current-voltage characteristics. Each estimated pulse discharge breakdown threshold voltage is compared with known threshold voltages for candidate gas components to estimate whether at least one candidate gas component is present in the gas. The procedure can be repeated at higher pulse voltages to estimate a pulse discharge breakdown threshold voltage for a second component present in the gas. The CNTs in the gas sensor have a sharp (low radius of curvature) tip; they are preferably multi-wall carbon nanotubes (MWCNTs) or carbon nanofibers (CNFs), to generate high-strength electrical fields adjacent to the tips for breakdown of the gas components with lower voltage application and generation of high current. The sensor system can provide a high-sensitivity, low-power-consumption tool that is very specific for identification of one or more gas components. The sensor can be multiplexed to measure current from multiple CNT arrays for simultaneous detection of several gas components.

  16. Reinforcement and rupture behavior of carbon nanotubes-polymer nanofibers

    NASA Astrophysics Data System (ADS)

    Ye, Haihui; Lam, Hoa; Titchenal, Nick; Gogotsi, Yury; Ko, Frank

    2004-09-01

    High-resolution transmission electron microscopy examination of carbon nanotube-polyacrylonitrile composite fibers synthesized by electrospinning was conducted. Both single-wall carbon nanotubes and multi-wall carbon nanotubes have been used to reinforce the polymer fibers. A two-stage rupture behavior of the composite fibers under tension, including crazing of polymer matrix and pull-out of carbon nanotubes, has been observed. Carbon nanotubes reinforce the polymer fibers by hindering crazing extension, reducing stress concentration, and dissipating energy by pullout. Distribution of nanotubes in the polymer matrix and interfacial adhesion between nanotubes and polymers are two major factors to determine the reinforcement effect of carbon nanotubes in polymer fibers.

  17. Thermoelectrics: Carbon nanotubes get high

    NASA Astrophysics Data System (ADS)

    Crispin, Xavier

    2016-04-01

    Waste heat can be converted to electricity by thermoelectric generators, but their development is hindered by the lack of cheap materials with good thermoelectric properties. Now, carbon-nanotube-based materials are shown to have improved properties when purified to contain only semiconducting species and then doped.

  18. Terahertz detection and carbon nanotubes

    ScienceCinema

    Leonard, Francois

    2014-06-13

    Researchers at Sandia National Laboratories, along with collaborators from Rice University and the Tokyo Institute of Technology, are developing new terahertz detectors based on carbon nanotubes that could lead to significant improvements in medical imaging, airport passenger screening, food inspection and other applications.

  19. Terahertz detection and carbon nanotubes

    SciTech Connect

    Leonard, Francois

    2014-06-11

    Researchers at Sandia National Laboratories, along with collaborators from Rice University and the Tokyo Institute of Technology, are developing new terahertz detectors based on carbon nanotubes that could lead to significant improvements in medical imaging, airport passenger screening, food inspection and other applications.

  20. Carbon Nanotubes and Human Cells?

    ERIC Educational Resources Information Center

    King, G. Angela

    2005-01-01

    Single-walled carbon nanotubes that were chemically altered to be water soluble are shown to enter fibroblasts, T cells, and HL60 cells. Nanoparticles adversely affect immortalized HaCaT human keratinocyte cultures, indicating that they may enter cells.

  1. Method for synthesizing carbon nanotubes

    DOEpatents

    Fan, Hongyou

    2012-09-04

    A method for preparing a precursor solution for synthesis of carbon nanomaterials, where a polar solvent is added to at least one block copolymer and at least one carbohydrate compound, and the precursor solution is processed using a self-assembly process and subsequent heating to form nanoporous carbon films, porous carbon nanotubes, and porous carbon nanoparticles.

  2. Carbon Nanotube Passive Intermodulation Device for Nonlinear Energy Harvesting

    NASA Astrophysics Data System (ADS)

    Lerner, Mitchell; Perez, Israel; Rockway, John

    2014-03-01

    The navy is interested in designing RF front-ends for receivers to handle high power jammers and other strong interferers. Instead of blocking that energy or dissipating it as heat in filters or amplifiers, this project investigates re-directing that energy for harvesting and storage. The approach is based on channelizing a high power jamming signal into a passive intermodulation device to create intermodulation products in sub-band frequencies, which could then be harvested for energy. The intermodulation device is fabricated using carbon nanotube transistors and such devices can be modified by creating chemical defects in the sidewalls of the nanotubes and locally gating the devices with a slowly varying electric field. These effects controllably enhance the hysteretic non-linearity in the transistors IV behavior. Combining these components with a RF energy harvester on the back-end should optimize the re-use of inbound jamming energy while maximizing the utility of standard back end radio components.

  3. Plasma Enhanced Growth of Carbon Nanotubes For Ultrasensitive Biosensors

    NASA Technical Reports Server (NTRS)

    Cassell, Alan M.; Li, J.; Ye, Q.; Koehne, J.; Chen, H.; Meyyappan, M.

    2004-01-01

    The multitude of considerations facing nanostructure growth and integration lends itself to combinatorial optimization approaches. Rapid optimization becomes even more important with wafer-scale growth and integration processes. Here we discuss methodology for developing plasma enhanced CVD growth techniques for achieving individual, vertically aligned carbon nanostructures that show excellent properties as ultrasensitive electrodes for nucleic acid detection. We utilize high throughput strategies for optimizing the upstream and downstream processing and integration of carbon nanotube electrodes as functional elements in various device types. An overview of ultrasensitive carbon nanotube based sensor arrays for electrochemical biosensing applications and the high throughput methodology utilized to combine novel electrode technology with conventional MEMS processing will be presented.

  4. Plasma Enhanced Growth of Carbon Nanotubes For Ultrasensitive Biosensors

    NASA Technical Reports Server (NTRS)

    Cassell, Alan M.; Meyyappan, M.

    2004-01-01

    The multitude of considerations facing nanostructure growth and integration lends itself to combinatorial optimization approaches. Rapid optimization becomes even more important with wafer-scale growth and integration processes. Here we discuss methodology for developing plasma enhanced CVD growth techniques for achieving individual, vertically aligned carbon nanostructures that show excellent properties as ultrasensitive electrodes for nucleic acid detection. We utilize high throughput strategies for optimizing the upstream and downstream processing and integration of carbon nanotube electrodes as functional elements in various device types. An overview of ultrasensitive carbon nanotube based sensor arrays for electrochemical bio-sensing applications and the high throughput methodology utilized to combine novel electrode technology with conventional MEMS processing will be presented.

  5. Mechanical capping of silica nanotubes for encapsulation of molecules.

    PubMed

    Yu, Jaeeun; Bai, Xia; Suh, Junghun; Lee, Sang Bok; Son, Sang Jun

    2009-11-01

    Multifunctional silica nanotubes (SNTs) are being widely used for many biomedical applications due to their structural benefits. Controlling the structure of the open end of an SNT is a crucial step for drug/gene delivery and for fabrication of multifunctional SNTs. We developed a mechanical capsulation method to fabricate caps at the ends of SNTs. A thin layer of malleable capping materials (Au, Ag, PLGA) was deposited onto the surface of an SNT-grown AAO template. Capped SNTs were then obtained by hammering with alumina microbeads. For a proof-of-concept experiment, we demonstrated dye-encapsulated SNTs without any chemical functionalizations. Since a mechanical approach is free of the issue of chemical compatibility between cargo molecules and capping materials, the method can provide an effective platform for the preparation of smart multifunctional nanotubes for biomedical applications. PMID:19824675

  6. Impact of SWCNT processing on nanotube-silicon heterojunctions.

    PubMed

    Harris, John M; Headrick, Robert J; Semler, Matthew R; Fagan, Jeffrey A; Pasquali, Matteo; Hobbie, Erik K

    2016-04-14

    Single-wall carbon nanotube (SWCNT) films are ideal components for thin, flexible, and durable electronic devices. Here, we use a variety of processing approaches to fabricate SWCNT-silicon heterojunctions from both unsorted and chirality-enriched SWCNTs. Through measured structure/processing/property relationships, we quantify the influence of SWCNT purity, alignment and residual doping on device performance and diode characteristics. Our results show that mixed-type unaligned SWCNTs processed in super-acid solvents can achieve state-of-the-art performance. The devices perform comparably to those fabricated from type or chiral-purified SWCNTs, despite what appear to be significant deviations from ideal diode behavior. Our results clarify a direct route for processing nanotube-silicon heterojunctions while providing additional insight into the underlying nature of these devices. PMID:27009759

  7. Applications and production of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Hafner, Jason Howard

    Carbon nanotubes, a recently discovered form of carbon fiber with structural perfection similar to that of a fullerene molecule, have interesting electronic, chemical and mechanical properties due to their size and structure. Nanotubes have great potential as a bulk material for strong, lightweight composite materials, and as individual nano-scale tools or devices. Initial work on applications with individual multiwalled nanotubes as field emission sources and scanning force microscopy tips is described. The nanotubes display intriguing field emission behavior interpreted as the nanotube unraveling under the influence of the electric field. The unraveling process is believed to result in facile field emission from linear atomic carbon chains at the end of the nanotube. Such atomic wires represent an excellent field emitter. The work on multiwalled nanotube SFM tips was equally encouraging. The high aspect ratio of the nanotube allows it to image deep trenches inaccessible to commercially available Si pyramidal tips, and it reduces the interaction with the ambient water layer on the sample which perturbs image quality. The most remarkable advantage of nanotube SFM tips is a result of their mechanical properties. It was found that the nanotubes will remain rigid during normal imaging, but conveniently buckle to the side if circumstances arise which create large forces known to damage the tip and sample. This feature makes the tip more durable than Si tips, and is especially important for soft biological samples. In these two applications, as well as others, and in the measurements of novel nanotube properties, high quality, small diameter (0.5 to 2 nm) diameter single-walled nanotubes are most interesting. Such material can be produced slowly and in small amounts by catalytic arc vaporization and catalytic laser vaporization of graphite. It is well known that nanotubes can be mass produced by catalytic chemical vapor deposition (CCVD), but the product consists only

  8. Carbon-Nanotube Schottky Diodes

    NASA Technical Reports Server (NTRS)

    Manohara, Harish; Wong, Eric; Schlecht, Erich; Hunt, Brian; Siegel, Peter

    2006-01-01

    Schottky diodes based on semiconducting single-walled carbon nanotubes are being developed as essential components of the next generation of submillimeter-wave sensors and sources. Initial performance predictions have shown that the performance characteristics of these devices can exceed those of the state-of-the-art solid-state Schottky diodes that have been the components of choice for room-temperature submillimeter-wave sensors for more than 50 years. For state-of-the-art Schottky diodes used as detectors at frequencies above a few hundred gigahertz, the inherent parasitic capacitances associated with their semiconductor junction areas and the resistances associated with low electron mobilities limit achievable sensitivity. The performance of such a detector falls off approximately exponentially with frequency above 500 GHz. Moreover, when used as frequency multipliers for generating signals, state-of-the-art solid-state Schottky diodes exhibit extremely low efficiencies, generally putting out only micro-watts of power at frequencies up to 1.5 THz. The shortcomings of the state-of-the-art solid-state Schottky diodes can be overcome by exploiting the unique electronic properties of semiconducting carbon nanotubes. A single-walled carbon nanotube can be metallic or semiconducting, depending on its chirality, and exhibits high electron mobility (recently reported to be approx.= 2x10(exp 5)sq cm/V-s) and low parasitic capacitance. Because of the narrowness of nanotubes, Schottky diodes based on carbon nanotubes have ultra-small junction areas (of the order of a few square nanometers) and consequent junction capacitances of the order of 10(exp -18) F, which translates to cutoff frequency >5 THz. Because the turn-on power levels of these devices are very low (of the order of nano-watts), the input power levels needed for pumping local oscillators containing these devices should be lower than those needed for local oscillators containing state-of-the-art solid

  9. A novel method for studying the buckling of nanotubes considering geometrical imperfections

    NASA Astrophysics Data System (ADS)

    Anoop Krishnan, N. M.; Ghosh, Debraj

    2014-05-01

    Buckling of nanotubes has been studied using many methods such as molecular dynamics (MD), molecular mechanics, and continuum-based shell theories. In MD, motion of the individual atoms is tracked under applied temperature and pressure, ensuring a reliable estimate of the material response. The response thus simulated varies for individual nanotubes and is only as accurate as the force field used to model the atomic interactions. On the other hand, there exists a rich literature on the understanding of continuum mechanics-based shell theories. Based on the observations on the behavior of nanotubes, there have been a number of shell theory-based approaches to study the buckling of nanotubes. Although some of these methods yield a reasonable estimate of the buckling stress, investigation and comparison of buckled mode shapes obtained from continuum analysis and MD are sparse. Previous studies show that the direct application of shell theories to study nanotube buckling often leads to erroneous results. The present study reveals that a major source of this error can be attributed to the departure of the shape of the nanotube from a perfect cylindrical shell. Analogous to the shell buckling in the macro-scale, in this work, the nanotube is modeled as a thin-shell with initial imperfection. Then, a nonlinear buckling analysis is carried out using the Riks method. It is observed that this proposed approach yields significantly improved estimate of the buckling stress and mode shapes. It is also shown that the present method can account for the variation of buckling stress as a function of the temperature considered. Hence, this can prove to be a robust method for a continuum analysis of nanosystems taking in the effect of variation of temperature as well.

  10. Electrokinetics of scalable, electric-field-assisted fabrication of vertically aligned carbon-nanotube/polymer composites

    NASA Astrophysics Data System (ADS)

    Castellano, Richard J.; Akin, Cevat; Giraldo, Gabriel; Kim, Sangil; Fornasiero, Francesco; Shan, Jerry W.

    2015-06-01

    Composite thin films incorporating vertically aligned carbon nanotubes (VACNTs) offer promise for a variety of applications where the vertical alignment of the CNTs is critical to meet performance requirements, e.g., highly permeable membranes, thermal interfaces, dry adhesives, and films with anisotropic electrical conductivity. However, current VACNT fabrication techniques are complex and difficult to scale up. Here, we describe a solution-based, electric-field-assisted approach as a cost-effective and scalable method to produce large-area VACNT composites. Multiwall-carbon nanotubes are dispersed in a polymeric matrix, aligned with an alternating-current (AC) electric field, and electrophoretically concentrated to one side of the thin film with a direct-current (DC) component to the electric field. This approach enables the fabrication of highly concentrated, individually aligned nanotube composites from suspensions of very dilute ( ϕ = 4 × 10 - 4 ) volume fraction. We experimentally investigate the basic electrokinetics of nanotube alignment under AC electric fields, and show that simple models can adequately predict the rate and degree of nanotube alignment using classical expressions for the induced dipole moment, hydrodynamic drag, and the effects of Brownian motion. The composite AC + DC field also introduces complex fluid motion associated with AC electro-osmosis and the electrochemistry of the fluid/electrode interface. We experimentally probe the electric-field parameters behind these electrokinetic phenomena, and demonstrate, with suitable choices of processing parameters, the ability to scalably produce large-area composites containing VACNTs at number densities up to 1010 nanotubes/cm2. This VACNT number density exceeds that of previous electric-field-fabricated composites by an order of magnitude, and the surface-area coverage of the 40 nm VACNTs is comparable to that of chemical-vapor-deposition-grown arrays of smaller-diameter nanotubes.

  11. Synthesis of yttrium hydroxide and oxide nanotubes

    NASA Astrophysics Data System (ADS)

    Tang, Qun; Liu, Zhaoping; Li, Shu; Zhang, Shuyuan; Liu, Xianming; Qian, Yitai

    2003-11-01

    Yttrium hydroxide nanotubes were hydrothermally synthesized via a metastable precursor, PEG-Y(NO 3) 3 complex. XRD patterns showed the product was a pure hexagonal phase of Y(OH) 3. TEM images displayed that the nanotubes have outer diameters ranging from 80 to 200 nm, wall thicknesses of about 30 nm, and lengths up to several micrometers. The nanotube growth may have three stages: formation of a metastable PEG-Y(NO 3) 3 complex; nucleation and formation of Y(OH) 3 nanorods; developing Y(OH) 3 nanotubes. We proposed the Y(OH) 3 nanotubes growth mechanism to be a nucleation-diffusion growth based on the characterization results. Y 2O 3 nanotubes were formed with smaller diameters after post-treatment at 500°C for 2 h.

  12. Carbon Nanotube Composites: Strongest Engineering Material Ever?

    NASA Technical Reports Server (NTRS)

    Mayeaux, Brian; Nikolaev, Pavel; Proft, William; Nicholson, Leonard S. (Technical Monitor)

    1999-01-01

    The primary goal of the carbon nanotube project at Johnson Space Center (JSC) is to fabricate structural materials with a much higher strength-to-weight ratio than any engineered material today, Single-wall nanotubes present extraordinary mechanical properties along with new challenges for materials processing. Our project includes nanotube production, characterization, purification, and incorporation into applications studies. Now is the time to move from studying individual nanotubes to applications work. Current research at JSC focuses on structural polymeric materials to attempt to lower the weight of spacecraft necessary for interplanetary missions. These nanoscale fibers present unique new challenges to composites engineers. Preliminary studies show good nanotube dispersion and wetting by the epoxy materials. Results of tensile strength tests will also be reported. Other applications of nanotubes are also of interest for energy storage, gas storage, nanoelectronics, field emission, and biomedical uses.

  13. Purification of Carbon Nanotubes: Alternative Methods

    NASA Technical Reports Server (NTRS)

    Files, Bradley; Scott, Carl; Gorelik, Olga; Nikolaev, Pasha; Hulse, Lou; Arepalli, Sivaram

    2000-01-01

    Traditional carbon nanotube purification process involves nitric acid refluxing and cross flow filtration using surfactant TritonX. This is believed to result in damage to nanotubes and surfactant residue on nanotube surface. Alternative purification procedures involving solvent extraction, thermal zone refining and nitric acid refiuxing are used in the current study. The effect of duration and type of solvent to dissolve impurities including fullerenes and P ACs (polyaromatic compounds) are monitored by nuclear magnetic reasonance, high performance liquid chromatography, and thermogravimetric analysis. Thermal zone refining yielded sample areas rich in nanotubes as seen by scanning electric microscopy. Refluxing in boiling nitric acid seem to improve the nanotube content. Different procedural steps are needed to purify samples produced by laser process compared to arc process. These alternative methods of nanotube purification will be presented along with results from supporting analytical techniques.

  14. Development of Carbon-Nanotube/Polymer Composites

    NASA Technical Reports Server (NTRS)

    Reynolds, Thomas A.

    2005-01-01

    A report presents a short discussion of one company's effort to develop composites of carbon nanotubes in epoxy and other polymer matrices. The focus of the discussion is on the desirability of chemically modifying carbon nanotubes to overcome their inherent chemical nonreactivity and thereby enable the formation of strong chemical bonds between nanotubes and epoxies (or other polymeric matrix materials or their monomeric precursors). The chemical modification is effected in a process in which discrete functional groups are covalently attached to the nanotube surfaces. The functionalization process was proposed by the company and demonstrated in practice for the first time during this development effort. The covalently attached functional groups are capable of reacting with the epoxy or other matrix resin to form covalent bonds. Furthermore, the company uses this process to chemically modify the nanotube surfaces, affording tunable adhesion to polymers and solubility in select solvents. Flat-sheet composites containing functionalized nanotubes demonstrate significantly improved mechanical, thermal, and electrical properties.

  15. Telescopic nanotube device for hot nanolithography

    DOEpatents

    Popescu, Adrian; Woods, Lilia M

    2014-12-30

    A device for maintaining a constant tip-surface distance for producing nanolithography patterns on a surface using a telescopic nanotube for hot nanolithography. An outer nanotube is attached to an AFM cantilever opposite a support end. An inner nanotube is telescopically disposed within the outer nanotube. The tip of the inner nanotube is heated to a sufficiently high temperature and brought in the vicinity of the surface. Heat is transmitted to the surface for thermal imprinting. Because the inner tube moves telescopically along the outer nanotube axis, a tip-surface distance is maintained constant due to the vdW force interaction, which in turn eliminates the need of an active feedback loop.

  16. Deconvoluting hepatic processing of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Alidori, Simone; Bowman, Robert L.; Yarilin, Dmitry; Romin, Yevgeniy; Barlas, Afsar; Mulvey, J. Justin; Fujisawa, Sho; Xu, Ke; Ruggiero, Alessandro; Riabov, Vladimir; Thorek, Daniel L. J.; Ulmert, Hans David S.; Brea, Elliott J.; Behling, Katja; Kzhyshkowska, Julia; Manova-Todorova, Katia; Scheinberg, David A.; McDevitt, Michael R.

    2016-07-01

    Single-wall carbon nanotubes present unique opportunities for drug delivery, but have not advanced into the clinic. Differential nanotube accretion and clearance from critical organs have been observed, but the mechanism not fully elucidated. The liver has a complex cellular composition that regulates a range of metabolic functions and coincidently accumulates most particulate drugs. Here we provide the unexpected details of hepatic processing of covalently functionalized nanotubes including receptor-mediated endocytosis, cellular trafficking and biliary elimination. Ammonium-functionalized fibrillar nanocarbon is found to preferentially localize in the fenestrated sinusoidal endothelium of the liver but not resident macrophages. Stabilin receptors mediate the endocytic clearance of nanotubes. Biocompatibility is evidenced by the absence of cell death and no immune cell infiltration. Towards clinical application of this platform, nanotubes were evaluated for the first time in non-human primates. The pharmacologic profile in cynomolgus monkeys is equivalent to what was reported in mice and suggests that nanotubes should behave similarly in humans.

  17. Impact of SWCNT processing on nanotube-silicon heterojunctions

    NASA Astrophysics Data System (ADS)

    Harris, John M.; Headrick, Robert J.; Semler, Matthew R.; Fagan, Jeffrey A.; Pasquali, Matteo; Hobbie, Erik K.

    2016-04-01

    Single-wall carbon nanotube (SWCNT) films are ideal components for thin, flexible, and durable electronic devices. Here, we use a variety of processing approaches to fabricate SWCNT-silicon heterojunctions from both unsorted and chirality-enriched SWCNTs. Through measured structure/processing/property relationships, we quantify the influence of SWCNT purity, alignment and residual doping on device performance and diode characteristics. Our results show that mixed-type unaligned SWCNTs processed in super-acid solvents can achieve state-of-the-art performance. The devices perform comparably to those fabricated from type or chiral-purified SWCNTs, despite what appear to be significant deviations from ideal diode behavior. Our results clarify a direct route for processing nanotube-silicon heterojunctions while providing additional insight into the underlying nature of these devices.Single-wall carbon nanotube (SWCNT) films are ideal components for thin, flexible, and durable electronic devices. Here, we use a variety of processing approaches to fabricate SWCNT-silicon heterojunctions from both unsorted and chirality-enriched SWCNTs. Through measured structure/processing/property relationships, we quantify the influence of SWCNT purity, alignment and residual doping on device performance and diode characteristics. Our results show that mixed-type unaligned SWCNTs processed in super-acid solvents can achieve state-of-the-art performance. The devices perform comparably to those fabricated from type or chiral-purified SWCNTs, despite what appear to be significant deviations from ideal diode behavior. Our results clarify a direct route for processing nanotube-silicon heterojunctions while providing additional insight into the underlying nature of these devices. Electronic supplementary information (ESI) available: Details related to SWCNT purification, device fabrication and assembly, CSA doping and film anisotropy. See DOI: 10.1039/c5nr08703a

  18. Bright and dark excitons in semiconductor carbon nanotubes

    SciTech Connect

    Tretiak, Sergei

    2008-01-01

    We report electronic structure calculations of finite-length semiconducting carbon nanotubes using the time dependent density functional theory (TD-DFT) and the time dependent Hartree Fock (TD-HF) approach coupled with semiempirical AM1 and ZINDO Hamiltonians. We specifically focus on the energy splitting, relative ordering, and localization properties of the optically active (bright) and optically forbidden (dark) states from the lowest excitonic band of the nanotubes. These excitonic states are very important in competing radiative and non-radiative processes in these systems. Our analysis of excitonic transition density matrices demonstrates that pure DFT functionals overdelocalize excitons making an electron-hole pair unbound; consequently, excitonic features are not presented in this method. In contrast, the pure HF and A111 calculations overbind excitons inaccurately predicting the lowest energy state as a bright exciton. Changing AM1 with ZINDO Hamiltonian in TD-HF calculations, predicts the bright exciton as the second state after the dark one. However, in contrast to AM1 calculations, the diameter dependence of the excitation energies obtained by ZINDO does not follow the experimental trends. Finally, the TD-DFT approach incorporating hybrid functions with a moderate portion of the long-range HF exchange, such as B3LYP, has the most generality and predictive capacity providing a sufficiently accurate description of excitonic structure in finite-size nanotubes. These methods characterize four important lower exciton bands. The lowest state is dark, the upper band is bright, and the two other dark and nearly degenerate excitons lie in-between. Although the calculated energy splittings between the lowest dark and the bright excitons are relatively large ({approx}0.1 eV), the dense excitonic manifold below the bright exciton allows for fast non-radiative relaxation leasing to the fast population of the lowest dark exciton. This rationalizes the low

  19. Sustained ibuprofen release using composite poly(lactic-co-glycolic acid)/titanium dioxide nanotubes from Ti implant surface.

    PubMed

    Jia, Huiying; Kerr, Lei L

    2013-07-01

    Developing coatings on implant surface as drug carriers can reduce organ toxicity and effectively deliver drug locally to the target compared with the oral approach. Titanium dioxide (TiO2) nanotube has great potential for this application for widely used Ti implants because of its high surface area, ability to promote bone growth, and biocompatibility. However, there are two issues needed to be solved before further advancing TiO2 nanotubes technology as drug carriers: uncontrolled drug release and poor mechanical properties. In this study, a drug carrier using a composite of biodegradable polymer/TiO2 nanotubes is engineered. Ibuprofen is selected as a concept drug because it is a commonly used anti-inflammatory, fever, and pain-reducing drug. In addition, ibuprofen has a very short plasma half-life of only 1-3 h. A simple characterization method is developed to investigate the infiltration of polymer into TiO2 nanotubes. Good infiltration was observed of polymer into TiO2 nanotubes. The synthesized drug carrier demonstrated much better sustained drug release profiles for ibuprofen of 5 days (low-molecular-weight polymer) and 9 days (high-molecular-weight polymer) compared with 30 min of pure TiO2 nanotubes. The drug carrier also exhibited much improved mechanical strength and flexibility compared with pure TiO2 nanotubes. PMID:23657983

  20. Amorphous Carbon-Boron Nitride Nanotube Hybrids

    NASA Technical Reports Server (NTRS)

    Kim, Jae Woo (Inventor); Siochi, Emilie J. (Inventor); Wise, Kristopher E. (Inventor); Lin, Yi (Inventor); Connell, John (Inventor)

    2016-01-01

    A method for joining or repairing boron nitride nanotubes (BNNTs). In joining BNNTs, the nanotube structure is modified with amorphous carbon deposited by controlled electron beam irradiation to form well bonded hybrid a-C/BNNT structures. In repairing BNNTs, the damaged site of the nanotube structure is modified with amorphous carbon deposited by controlled electron beam irradiation to form well bonded hybrid a-C/BNNT structures at the damage site.

  1. Carbon nanotube oscillators toward zeptogram detection

    SciTech Connect

    Nishio, Mitsumasa; Sawaya, Shintaro; Akita, Seiji; Nakayama, Yoshikazu

    2005-03-28

    We demonstrate an application of a nanotube cantilever for zeptogram-level mass detection. This letter presents a quantitative method to measure the oscillation amplitude of a nanotube cantilever using a focused electron beam of a scanning electron microscope. The quality factor of {approx}1000 for the nanotube cantilever is revealed and the resolution of the resonant frequency is achieved to be {approx}10 Hz, which corresponds to a mass range of less than 100 zg at room temperature.

  2. Method of making carbon nanotube composite materials

    DOEpatents

    O'Bryan, Gregory; Skinner, Jack L; Vance, Andrew; Yang, Elaine Lai; Zifer, Thomas

    2014-05-20

    The present invention is a method of making a composite polymeric material by dissolving a vinyl thermoplastic polymer, un-functionalized carbon nanotubes and hydroxylated carbon nanotubes and optionally additives in a solvent to make a solution and removing at least a portion of the solvent after casting onto a substrate to make thin films. The material has enhanced conductivity properties due to the blending of the un-functionalized and hydroxylated carbon nanotubes.

  3. Covalent Sidewall Functionalization of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Chiang, I.W.; Saini, R. K.; Mickelson, E. T.; Billups, W. E.; Hauge, R. H.; Margrave, J. L.

    2001-01-01

    Progress of fluorination of single-wall carbon nanotubes is being reported. Covalent attachment of alkyl groups including methyl, n-butyl and n-hexyl groups to the sidewalls of single wall carbon nanotubes (SWNTs) has been achieved. Quantitative measurement of the alkylation was done by thermal gravimetric analysis. FTIR, Raman and UV-Vis-NIR were used to characterize these alkylated SWNTs. Application of these nanotubes are being investigated-fibers, composites, batteries, lubricants, etc.

  4. Symmetry-adapted phonon analysis of nanotubes

    NASA Astrophysics Data System (ADS)

    Aghaei, Amin; Dayal, Kaushik; Elliott, Ryan S.

    2013-02-01

    The characteristics of phonons, i.e. linearized normal modes of vibration, provide important insights into many aspects of crystals, e.g. stability and thermodynamics. In this paper, we use the Objective Structures framework to make concrete analogies between crystalline phonons and normal modes of vibration in non-crystalline but highly symmetric nanostructures. Our strategy is to use an intermediate linear transformation from real-space to an intermediate space in which the Hessian matrix of second derivatives is block-circulant. The block-circulant nature of the Hessian enables us to then follow the procedure to obtain phonons in crystals: namely, we use the Discrete Fourier Transform from this intermediate space to obtain a block-diagonal matrix that is readily diagonalizable. We formulate this for general Objective Structures and then apply it to study carbon nanotubes of various chiralities that are subjected to axial elongation and torsional deformation. We compare the phonon spectra computed in the Objective Framework with spectra computed for armchair and zigzag nanotubes. We also demonstrate the approach by computing the Density of States. In addition to the computational efficiency afforded by Objective Structures in providing the transformations to almost-diagonalize the Hessian, the framework provides an important conceptual simplification to interpret the phonon curves. Our findings include that, first, not all non-optic long-wavelength modes are zero energy and conversely not all zero energy modes are long-wavelength; second, the phonon curves accurately predict both the onset as well as the soft modes for instabilities such as torsional buckling; and third, unlike crystals where phonon stability does not provide information on stability with respect to non-rank-one deformation modes, phonon stability in nanotubes is sufficient to guarantee stability with respect to all perturbations that do not involve structural modes. Our finding of characteristic

  5. Plasticity and Kinky Chemistry of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Srivastava, Deepak; Dzegilenko, Fedor

    2000-01-01

    Since their discovery in 1991, carbon nanotubes have been the subject of intense research interest based on early predictions of their unique mechanical, electronic, and chemical properties. Materials with the predicted unique properties of carbon nanotubes are of great interest for use in future generations of aerospace vehicles. For their structural properties, carbon nanotubes could be used as reinforcing fibers in ultralight multifunctional composites. For their electronic properties, carbon nanotubes offer the potential of very high-speed, low-power computing elements, high-density data storage, and unique sensors. In a continuing effort to model and predict the properties of carbon nanotubes, Ames accomplished three significant results during FY99. First, accurate values of the nanomechanics and plasticity of carbon nanotubes based on quantum molecular dynamics simulations were computed. Second, the concept of mechanical deformation catalyzed-kinky-chemistry as a means to control local chemistry of nanotubes was discovered. Third, the ease of nano-indentation of silicon surfaces with carbon nanotubes was established. The elastic response and plastic failure mechanisms of single-wall nanotubes were investigated by means of quantum molecular dynamics simulations.

  6. Field emission and growth of fullerene nanotubes

    SciTech Connect

    Rinzler, A.G.; Hafner, J.H.; Nilolaev, P.; Colbert, D.T.; Smalley, R.E.

    1994-11-01

    Efforts to control the growth of individual carbon nanotubes from nanotube seed crystals have led to a characterization of their field-induced electron emission behavior. The application of a bias voltage in the growth apparatus was motivated by the prolific formation of nanotubes in the carbon are growth method, in which the electric field appears to play a central role. The authors report here the ability to achieve various tube tip configurations by the controlled application of voltage, heat and chemicals to an individual nanotube, and that these states are well characterized by the emission currents they induce.

  7. Quantum conductance of carbon nanotube peapods

    SciTech Connect

    Yoon, Young-Gui; Mazzoni, Mario S.C.; Louie, Steven G.

    2003-08-01

    We present a first-principles study of the quantum conductance of hybrid nanotube systems consisting of single-walled carbon nanotubes (SWCNTs) encapsulating either an isolated single C60 molecule or a chain of C60 molecules (nanotube peapods). The calculations show a rather weak bonding interaction between the fullerenes and the SWCNTs. The conductance of a (10,10) SWCNT with a single C60 molecule is virtually unaffected at the Fermi level, but exhibits quantized resonant reductions at the molecular levels. The nanotube peapod arrangement gives rise to high density of states for the fullerene highest occupied molecular orbital and lowest unoccupied molecular orbital bands.

  8. Carbon nanotube coatings as chemical absorbers

    DOEpatents

    Tillotson, Thomas M.; Andresen, Brian D.; Alcaraz, Armando

    2004-06-15

    Airborne or aqueous organic compound collection using carbon nanotubes. Exposure of carbon nanotube-coated disks to controlled atmospheres of chemical warefare (CW)-related compounds provide superior extraction and retention efficiencies compared to commercially available airborne organic compound collectors. For example, the carbon nanotube-coated collectors were four (4) times more efficient toward concentrating dimethylmethyl-phosphonate (DMMP), a CW surrogate, than Carboxen, the optimized carbonized polymer for CW-related vapor collections. In addition to DMMP, the carbon nanotube-coated material possesses high collection efficiencies for the CW-related compounds diisopropylaminoethanol (DIEA), and diisopropylmethylphosphonate (DIMP).

  9. From carbon nanobells to nickel nanotubes

    SciTech Connect

    Ma, S.; Srikanth, V. V. S. S.; Maik, D.; Zhang, G. Y.; Staedler, T.; Jiang, X.

    2009-01-05

    A generic strategy is proposed to prepare one dimensional (1D) metallic nanotubes by using 1D carbon nanostructures as the initial templates. Following the strategy, nickel (Ni) nanotubes are prepared by using carbon nanobells (CNBs) as the initial templates. CNBs are first prepared by microwave plasma enhanced chemical vapor deposition technique. Carbon/nickel core/shell structures are then prepared by electroplating the CNBs in a nickel-Watts electrolytic cell. In the final step, the carbon core is selectively removed by employing hydrogen plasma etching to obtain Ni nanotubes. The mechanism leading to Ni nanotubes is briefly discussed.

  10. Influence of carbon nanotube dimensions on the percolation characteristics of carbon nanotube/polymer composites

    NASA Astrophysics Data System (ADS)

    Shehzad, Khurram; Ahmad, Mirza Nadeem; Hussain, Tajamal; Mumtaz, Muhammad; Shah, Asma Tufail; Mujahid, Adnan; Wang, Chao; Ellingsen, Josef; Dang, Zhi-Min

    2014-08-01

    The effect of carbon nanotube aspect ratio (AR) on the percolation characteristics of their polymer composites was investigated by melt blending the multi-wall carbon nanotubes (MWCNTs) with different AR with a thermoplastic elastomer. Previously, most studies reported the effect of aspect ratio of MWCNTs only in the context of achieving the maximum electrical conductivity at lower percolation thresholds in the polymer composites. In this study, our results indicate that aspect ratio can also influence other percolation properties such as the pre-percolation conductivity, percolation conductivity and post-percolation conductivity, shape of the percolation curve, and the width of the insulator-conductor transition. We have established that AR can be used to tailor the percolation curves from sharp to quasi-linear ones, which can help us fabricate the percolative composites with stable electrical properties. Experimental results suggested that the mathematically calculated nominal AR of the MWCNTs was an unclear parameter to correlate with the percolation characteristics of the composites. Instead, an approach taking into consideration the nominal length (l) and the diameter (d) of the MWCNTs individually rather than as a combined AR (l/d) parameter gave a better explanation of the relation between MWCNT dimensions and percolation characteristics.

  11. Peridynamic modeling and simulation of polymer-nanotube composites

    NASA Astrophysics Data System (ADS)

    Henke, Steven F.

    In this document, we develop and demonstrate a framework for simulating the mechanics of polymer materials that are reinforced by carbon nanotubes. Our model utilizes peridynamic theory to describe the mechanical response of the polymer and polymer-nanotube interfaces. We benefit from the continuum formulation used in peridynamics because (1) it allows the polymer material to be coarse-grained to the scale of the reinforcing nanofibers, and (2) failure via nanotube pull-out and matrix tearing are possible based on energetic considerations alone (i.e. without special treatment). To reduce the degrees of freedom that must be simulated, the reinforcement effect of the nanotubes is represented by a mesoscale bead-spring model. This approach permits the arbitrary placement of reinforcement ``strands'' in the problem domain and motivates the need for irregular quadrature point distributions, which have not yet been explored in the peridynamic setting. We address this matter in detail and report on aspects of mesh sensitivity that we uncovered in peridynamic simulations. Using a manufactured solution, we study the effects of quadrature point placement on the accuracy of the solution scheme in one and two dimensions. We demonstrate that square grids and the generator points of a centroidal Voronoi tessellation (CVT) support solutions of similar accuracy, but CVT grids have desirable characteristics that may justify the additional computational cost required for their construction. Impact simulations provide evidence that CVT grids support fracture patterns that resemble those obtained on higher resolution cubic Cartesian grids with a reduced computational burden. With the efficacy of irregular meshing schemes established, we exercise our model by dynamically stretching a cylindrical specimen composed of the polymer-nanotube composite. We vary the number of reinforcements, alignment of the filler, and the properties of the polymer-nanotube interface. Our results suggest

  12. Symmetric space description of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Caselle, Michele; Magnea, Ulrika

    2006-01-01

    Using an innovative technique arising from the theory of symmetric spaces, we obtain an approximate analytic solution of the Dorokhov-Mello-Pereyra-Kumar (DMPK) equation in the insulating regime of a metallic carbon nanotube with symplectic symmetry and an odd number of conducting channels. This symmetry class is characterized by the presence of a perfectly conducting channel in the limit of infinite length of the nanotube. The derivation of the DMPK equation for this system has recently been performed by Takane, who also obtained the average conductance both analytically and numerically. Using the Jacobian corresponding to the transformation to radial coordinates and the parametrization of the transfer matrix given by Takane, we identify the ensemble of transfer matrices as the symmetric space of negative curvature SO*(4m + 2)/[SU(2m + 1) × U(1)] belonging to the DIII-odd Cartan class. We rederive the leading-order correction to the conductance of the perfectly conducting channel \\langle \\ln \\delta g \\rangle and its variance Var(ln δg). Our results are in complete agreement with Takane's. In addition, our approach based on the mapping to a symmetric space enables us to obtain new universal quantities: a universal group theoretical expression for the ratio \\mathrm {Var}(\\ln \\delta g)/\\langle \\ln \\delta g\\rangle , and as a by-product a novel expression for the localization length for the most general case of a symmetric space with BCm root system, in which all three types of roots are present.

  13. A facile vapor-phase hydrothermal method for direct growth of titanate nanotubes on a titanium substrate via a distinctive nanosheet roll-up mechanism.

    PubMed

    Liu, Porun; Zhang, Haimin; Liu, Hongwei; Wang, Yun; Yao, Xiangdong; Zhu, Guangshan; Zhang, Shanqing; Zhao, Huijun

    2011-11-30

    We present a facile vapor-phase hydrothermal approach for direct growth of vertically aligned titanate nanotubes on a titanium foil substrate. The resultant nanotubes display external diameters of 50-80 nm and walls with an average thickness of 10 nm that consist of more than 10 titanate layers. This is in strong contrast to the titanate nanotubes obtained from alkaline liquid-phase hydrothermal methods, which are generally smaller than 12 nm in external diameter and have walls consisting of less than five titanate layers. Importantly, the investigation confirmed that under vapor-phase hydrothermal conditions, the nanotubes were formed via a distinctive nanosheet roll-up mechanism that differs remarkably from those of conventional liquid-phase hydrothermal processes. For the first time, a coaxial circular cylinder crystal structure of the resultant nanotubes was confirmed. PMID:22035232

  14. Nanotube reinforced thermoplastic polymer matrix composites

    NASA Astrophysics Data System (ADS)

    Shofner, Meisha Lei

    The inherent high strength, thermal conductivity, and electrical conductivity make nanotubes attractive reinforcements for polymer matrix composites. However, the structure that makes them desirable also causes highly anisotropic properties and limited reactivity with other materials. This thesis isolates these problems in two separate studies aimed at improving mechanical properties with single wall nanotube (SWNT) reinforced thermoplastic polymer composites. The two studies demonstrate the effect of solid freeform fabrication (SFF) and chemical functionalization on anisotropy and limited reactivity, respectively. Both studies showed mechanical property improvements. The alignment study demonstrates a maximum increase of 93% in tensile modulus with single wall nanotubes (SWNTs). The chemical functionalization study shows a larger increase in storage modulus for functionalized SWNTs as compared to purified SVWNTs with respective increases of 9% and 44% in storage modulus. Improved interfacial properties are also observed as a decrease in mechanical damping. Maximum property increases in composites are obtained when nanotubes are aligned, requiring additional processing consideration to the anisotropic structure. Melt spinning and extrusion processing effectively align nanotubes, but the end product of these techniques, composite fibers, requires further processing to be incorporated into finished parts. Extrusion-based SFF is a novel technique for processing nanotube reinforced composites because it allows for the direct fabrication of finished parts containing aligned nanotubes. SFF processing produces parts containing preferentially oriented nanotubes with improved mechanical properties when compared to isotropic composites. Functionalization of the nanotube surface disrupts the rope structure to obtain smaller ropes and promote further interfacial bonding. The chemically inert nature of nanotubes resulting from a structure containing few defects and the

  15. Fundamental optical processes in armchair carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Hároz, Erik H.; Duque, Juan G.; Tu, Xiaomin; Zheng, Ming; Hight Walker, Angela R.; Hauge, Robert H.; Doorn, Stephen K.; Kono, Junichiro

    2013-01-01

    Single-wall carbon nanotubes provide ideal model one-dimensional (1-D) condensed matter systems in which to address fundamental questions in many-body physics, while, at the same time, they are leading candidates for building blocks in nanoscale optoelectronic circuits. Much attention has been recently paid to their optical properties, arising from 1-D excitons and phonons, which have been revealed via photoluminescence, Raman scattering, and ultrafast optical spectroscopy of semiconducting carbon nanotubes. On the other hand, dynamical properties of metallic nanotubes have been poorly explored, although they are expected to provide a novel setting for the study of electron-hole pairs in the presence of degenerate 1-D electrons. In particular, (n,n)-chirality, or armchair, metallic nanotubes are truly gapless with massless carriers, ideally suited for dynamical studies of Tomonaga-Luttinger liquids. Unfortunately, progress towards such studies has been slowed by the inherent problem of nanotube synthesis whereby both semiconducting and metallic nanotubes are produced. Here, we use post-synthesis separation methods based on density gradient ultracentrifugation and DNA-based ion-exchange chromatography to produce aqueous suspensions strongly enriched in armchair nanotubes. Through resonant Raman spectroscopy of the radial breathing mode phonons, we provide macroscopic and unambiguous evidence that density gradient ultracentrifugation can enrich ensemble samples in armchair nanotubes. Furthermore, using conventional, optical absorption spectroscopy in the near-infrared and visible range, we show that interband absorption in armchair nanotubes is strongly excitonic. Lastly, by examining the G-band mode in Raman spectra, we determine that observation of the broad, lower frequency (G-) feature is a result of resonance with non-armchair ``metallic'' nanotubes. These findings regarding the fundamental optical absorption and scattering processes in metallic carbon nanotubes

  16. Directed Assembly of Single Wall Carbon Nanotube Field Effect Transistors.

    PubMed

    Penzo, Erika; Palma, Matteo; Chenet, Daniel A; Ao, Geyou; Zheng, Ming; Hone, James C; Wind, Shalom J

    2016-02-23

    The outstanding electronic properties of single wall carbon nanotubes (SWCNTs) have made them prime candidates for future nanoelectronics technologies. One of the main obstacles to the implementation of advanced SWCNT electronics to date is the inability to arrange them in a manner suitable for complex circuits. Directed assembly of SWCNT segments onto lithographically patterned and chemically functionalized substrates is a promising way to organize SWCNTs in topologies that are amenable to integration for advanced applications, but the placement and orientational control required have not yet been demonstrated. We have developed a technique for assembling length sorted and chirality monodisperse DNA-wrapped SWCNT segments on hydrophilic lines patterned on a passivated oxidized silicon substrate. Placement of individual SWCNT segments at predetermined locations was achieved with nanometer accuracy. Three terminal electronic devices, consisting of a single SWCNT segment placed either beneath or on top of metallic source/drain electrodes were fabricated. Devices made with semiconducting nanotubes behaved as typical p-type field effect transistors (FETs), whereas devices made with metallic nanotubes had a finite resistance with little or no gate modulation. This scalable, high resolution approach represents an important step forward toward the potential implementation of complex SWCNT devices and circuits. PMID:26807948

  17. Quantum rainbow channeling of positrons in very short carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Petrović, S.; Ćosić, M.; Nešković, N.

    2013-07-01

    This is a theoretical study of transmission of positrons of kinetic energies of 1 and 10 MeV through very short (11,9) single-wall carbon nanotubes of lengths of 200 and 560 nm, respectively. The needed continuum interaction potential of the positron and nanotube is obtained starting from the Molière's approximation of the Thomas-Fermi interaction potential of a positron and a nanotube atom. We calculate the classical and quantum angular distributions of transmitted positrons. In the classical calculations, the approach is via the equations of motion, and in the quantum calculations, the time-dependent Schrödinger equation is solved. The solutions of these equations are obtained numerically. In the quantum calculations, the initial beam is taken to be an ensemble of noninteracting Gaussian wave packets. The angular distributions are generated using the computer simulation method. Our analysis is concentrated on the rainbow effect, which is clearly seen in the angular distributions. The obtained classical and quantum rainbows are analyzed in detail and compared with each other.

  18. Fabrication and characterization of vertically aligned carbon-nanotube membranes

    NASA Astrophysics Data System (ADS)

    Castellano, Richard; Akin, Cevat; Purri, Matt; Shan, Jerry; Kim, Sangil; Fornasiero, Francesco

    2015-11-01

    Membranes having vertically-aligned carbon-nanotube (VACNT) pores offer promise as highly efficient and permeable membranes for use as breathable thin films, or in filtration and separation applications, among others. However, current membrane-fabrication techniques utilizing chemical-vapor-deposition-grown VACNT arrays are costly and difficult to scale up. We have developed a solution-based, electric-field-assisted approach as a cost-effective and scalable method to produce large-area VACNT membranes. Nanotubes are dispersed in a liquid polymer, and aligned and electrodeposited with the aid of an electric field prior to crosslinking the polymer to create VACNT membranes. We experimentally examine the electrodeposition process, focusing on parameters including the electric field, composition of the solution, and CNT functionalization that can affect the nanotube number density in the resulting membrane. We characterize the CNT pore size and number density and investigate the transport properties of the membrane. Size-exclusion tests are used to check for defects and infer the pore size of the VACNT membranes. Dry-gas membrane permeability is measured with a pressurized nitrogen-flow system, while moisture-vapor-transfer rate is measured with the ASTM-E96 upright-cup test. We discuss the measured transport properties of the solution-based, electric-field-fabricated VACNT membranes in reference to their application as breathable thin films. We would like to acknowledge DTRA for their funding and support of our research.

  19. Mass Transport Through Carbon Nanotube-Polystyrene Bundles

    NASA Astrophysics Data System (ADS)

    Lin, Rongzhou; Tran, Tuan

    2016-05-01

    Carbon nanotubes have been widely used as test channels to study nanofluidic transport, which has been found to have distinctive properties compared to transport of fluids in macroscopic channels. A long-standing challenge in the study of mass transport through carbon nanotubes (CNTs) is the determination of flow enhancement. Various experimental investigations have been conducted to measure the flow rate through CNTs, mainly based on either vertically aligned CNT membranes or individual CNTs. Here, we proposed an alternative approach that can be used to quantify the mass transport through CNTs. This is a simple method relying on the use of carbon nanotube-polystyrene bundles, which are made of CNTs pulled out from a vertically aligned CNT array and glued together by polystyrene. We experimentally showed by using fluorescent tagging that the composite bundles allowed measureable and selective mass transport through CNTs. This type of composite bundle may be useful in various CNT research areas as they are simple to fabricate, less likely to form macroscopic cracks, and offer a high density of CNT pores while maintaining the aligned morphology of CNTs.

  20. Growth of carbon nanotubes via twisted graphene nanoribbons

    PubMed Central

    Lim, Hong En; Miyata, Yasumitsu; Kitaura, Ryo; Nishimura, Yoshifumi; Nishimoto, Yoshio; Irle, Stephan; Warner, Jamie H.; Kataura, Hiromichi; Shinohara, Hisanori

    2013-01-01

    Carbon nanotubes have long been described as rolled-up graphene sheets. It is only fairly recently observed that longitudinal cleavage of carbon nanotubes, using chemical, catalytical and electrical approaches, unzips them into thin graphene strips of various widths, the so-called graphene nanoribbons. In contrast, rolling up these flimsy ribbons into tubes in a real experiment has not been possible. Theoretical studies conducted by Kit et al. recently demonstrated the tube formation through twisting of graphene nanoribbon, an idea very different from the rolling-up postulation. Here we report the first experimental evidence of a thermally induced self-intertwining of graphene nanoribbons for the preferential synthesis of (7, 2) and (8, 1) tubes within parent-tube templates. Through the tailoring of ribbon’s width and edge, the present finding adds a radically new aspect to the understanding of carbon nanotube formation, shedding much light on not only the future chirality tuning, but also contemporary nanomaterials engineering. PMID:24091379

  1. Growth of vertically aligned multiwall carbon nanotubes columns

    NASA Astrophysics Data System (ADS)

    Shahzad, M. I.; Giorcelli, M.; Perrone, D.; Virga, A.; Shahzad, N.; Jagdale, P.; Cocuzza, M.; Tagliaferro, A.

    2013-06-01

    Capability of patterning carbon nanotubes (CNTs) growth is of tantamount importance for a number of applications ranging from thermal to electronic. This article reports on the columnar growth of vertically aligned multiwall carbon nanotubes (VA-MWCNTs) on patterned Silicon (Si) surface. We have developed procedures based on negative as well as positive masking approaches which allows the growth of predetermined MWCNTs patterns. We describe in detail the process steps leading to Si surface patterning. As quoted above, patterns are exploited to grow VA-MWCNTs. We have focused in particular on the growth of CNT pillars by chemical vapor despoition (CVD) technique at 850°C with camphor and ferrocene as carbon precursors and catalyst respectively. Field emission scanning electron microscopy (FESEM) is employed at low magnification to verify the correct patterning, and at high magnification to examine the surface morphology of CNTs pillars. The pillars are up to 2 mm high, their height being tailored through the deposition time. The diameter of each MWCNT is in the range 30-70 nm and the length is up to few hundred micrometers. The small CNT pillars produced, have several electrical and thermal applications. For instance they can be very useful for heat transfer systems as the lower thermal conductivity of fluids can be improved by the inclusion of nanotubes thanks to their peculiar 1-dimensional heat transfer characteristics.

  2. Longitudinal solitons in carbon nanotubes

    SciTech Connect

    Astakhova, T. Yu.; Gurin, O. D.; Menon, M.; Vinogradov, G. A.

    2001-07-15

    We present results on soliton excitations in carbon nanotubes (CNT's) using Brenner's many-body potential. Our numerical simulations demonstrate high soliton stability in (10,10) CNT's. The interactions of solitons and solitary excitation with CNT defect are found to be inelastic if the excitations and defects length scales are comparable, resulting in a substantial part of soliton energy being distributed inhomogeneously over the defect bonds. In these solitary-excitation--cap collisions the local energy of a few bonds in the cap can exceed the average energy by an order of magnitude and more. This phenomenon, denoted the ''Tsunami effect,'' can contribute dynamically to the recently proposed ''kinky chemistry.'' We also present results of changes in the local density of states and variations in the atomic partial charges estimated at different time instants of the solitary-excitation Tsunami at the nanotube cap.

  3. Sagnac interference in carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Bishara, Waheb; Refael, Gil; Bockrath, Marc

    2008-10-01

    The Sagnac interference mode arises when two interfering counterpropogating beams traverse a loop, but with their velocities detuned by a small amount 2u , with vR/L=vF±u . In this paper we perform a perturbative nonequilibrium calculation of Sagnac interference in single-channel wires as well as armchair nanotube loops. We study the dependence of the Sagnac conductance oscillations on temperature and interactions. We find that the Sagnac interference is not destroyed by strong interactions, but becomes weakly dependent on the velocity detuning u . In armchairs nanotubes with typical interaction strength, 0.25≤g≤0.5 , we find that the necessary temperature for observing the interference effect, TSAG is also only weakly dependent on the interaction, and is enhanced by a factor of 8 relative to the temperature necessary for observing Fabry-Pérot interference in the same system, TFP .

  4. Carbon Nanotubes: Molecular Electronic Components

    NASA Technical Reports Server (NTRS)

    Srivastava, Deepak; Saini, Subhash; Menon, Madhu

    1997-01-01

    The carbon Nanotube junctions have recently emerged as excellent candidates for use as the building blocks in the formation of nanoscale molecular electronic networks. While the simple joint of two dissimilar tubes can be generated by the introduction of a pair of heptagon-pentagon defects in an otherwise perfect hexagonal graphene sheet, more complex joints require other mechanisms. In this work we explore structural characteristics of complex 3-point junctions of carbon nanotubes using a generalized tight-binding molecular-dynamics scheme. The study of pi-electron local densities of states (LDOS) of these junctions reveal many interesting features, most prominent among them being the defect-induced states in the gap.

  5. Torsional Carbon Nanotube Artificial Muscles

    NASA Astrophysics Data System (ADS)

    Foroughi, Javad; Spinks, Geoffrey M.; Wallace, Gordon G.; Oh, Jiyoung; Kozlov, Mikhail E.; Fang, Shaoli; Mirfakhrai, Tissaphern; Madden, John D. W.; Shin, Min Kyoon; Kim, Seon Jeong; Baughman, Ray H.

    2011-10-01

    Rotary motors of conventional design can be rather complex and are therefore difficult to miniaturize; previous carbon nanotube artificial muscles provide contraction and bending, but not rotation. We show that an electrolyte-filled twist-spun carbon nanotube yarn, much thinner than a human hair, functions as a torsional artificial muscle in a simple three-electrode electrochemical system, providing a reversible 15,000° rotation and 590 revolutions per minute. A hydrostatic actuation mechanism, as seen in muscular hydrostats in nature, explains the simultaneous occurrence of lengthwise contraction and torsional rotation during the yarn volume increase caused by electrochemical double-layer charge injection. The use of a torsional yarn muscle as a mixer for a fluidic chip is demonstrated.

  6. Effect of the rheological properties of carbon nanotube dispersions on the processing and properties of transparent conductive electrodes.

    PubMed

    Maillaud, Laurent; Poulin, Philippe; Pasquali, Matteo; Zakri, Cécile

    2015-06-01

    Transparent conductive films are made from aqueous surfactant stabilized dispersions of carbon nanotubes using an up-scalable rod coating method. The processability of the films is governed by the amount of surfactant which is shown to alter strongly the wetting and viscosity of the ink. The increase of viscosity results from surfactant mediated attractive interactions between the carbon nanotubes. Links between the formulation, ink rheological properties, and electro-optical properties of the films are determined. The provided guidelines are generalized and used to fabricate optimized electrodes using conductive polymers and carbon nanotubes. In these electrodes, the carbon nanotubes act as highly efficient viscosifiers that allow the optimized ink to be homogeneously spread using the rod coating method. From a general point of view and in contrast to previous studies, the CNTs are optimally used in the present approach as conductive additives for viscosity enhancements of electronic inks. PMID:25961667

  7. Development of Metal-impregnated Single Walled Carbon Nanotubes for Toxic Gas Contaminant Control in Advanced Life Support Systems

    NASA Technical Reports Server (NTRS)

    Cinke, Martin; Li, Jing; Chen, Bin; Wignarajah, Kanapathipillai; Pisharody, Suresh A.; Fisher, John W.; Delzeit, Lance; Meyyappan, Meyya; Partridge, Harry; Clark, Kimberlee

    2003-01-01

    The success of physico-chemical waste processing and resource recovery technologies for life support application depends partly on the ability of gas clean-up systems to efficiently remove trace contaminants generated during the process with minimal use of expendables. Highly purified metal-impregnated carbon nanotubes promise superior performance over conventional approaches to gas clean-up due to their ability to direct the selective uptake gaseous species based both on the nanotube s controlled pore size, high surface area, and ordered chemical structure that allows functionalization and on the nanotube s effectiveness as a catalyst support material for toxic contaminants removal. We present results on the purification of single walled carbon nanotubes (SWCNT) and efforts at metal impregnation of the SWCNT's.

  8. Oriented nanotube electrodes for lithium ion batteries and supercapacitors

    DOEpatents

    Frank, Arthur J.; Zhu, Kai; Wang, Qing

    2013-03-05

    An electrode having an oriented array of multiple nanotubes is disclosed. Individual nanotubes have a lengthwise inner pore defined by interior tube walls which extends at least partially through the length of the nanotube. The nanotubes of the array may be oriented according to any identifiable pattern. Also disclosed is a device featuring an electrode and methods of fabrication.

  9. Synthesis of nano-sized cyanide ion-imprinted polymer via non-covalent approach and its use for the fabrication of a CN(-)-selective carbon nanotube impregnated carbon paste electrode.

    PubMed

    Alizadeh, Taher; Sabzi, Reza Emamali; Alizadeh, Hassan

    2016-01-15

    Nano-sized CN(-)-imprinted polymer was synthesized by the copolymerization of methyl methacrylic acid (MAA), vinyl pyridine (VP) and ethylene glycol dimethacrylate in the presence of cyanide ion. The obtained polymeric nanoparticles were incorporated with carbon paste electrode (CPE) to produce a CN(-)-selective electrode. Functional monomer kind had crucial influence on the efficiency of the sensor. The presence of both VP and MAA in the structure of the imprinted polymer improved the sensing characteristics of the electrode. Also, the mole ratio of MAA/VP, cross-liker kind, cross-linker amount, solvent kind and amount were found to be effective factors in the electrode behavior. Presence of little amount of multi-walled carbon nanotubes (MWCNTs) in the CPE improved the detection range and response time of the electrode at the expense of small decrease in Nernstian slope. The electrode, containing CN(-)-imprinted polymer and MWCNTs showed a dynamic linear range of 1×10(-6)-1×10(-1)mol L(-1), Nernstian slope of 46.3±(0.6) mV and detection limit of 7.5×10(-7)mol L(-1); whereas, the same electrode in the absence of MWCNTs led to linear range, Nernstian slope and detection limit of 1×10(-5)-1×10(-1)molL(-1), 55.3±(0.7) mV and 8×10(-6)mol L(-1), respectively. The utility of the electrodes was checked by determination of cyanide ion in some real samples. PMID:26592581

  10. Flame Synthesis of Single- and Multi-Walled Carbon Nanotubes and Nanofibers

    NASA Technical Reports Server (NTRS)

    VanderWal, R. L.; Ticich, Thomas M.

    2001-01-01

    Metal-catalyzed carbon nanotubes are highly sought for a diverse range of applications that include nanoelectronics, battery electrode material, catalysis, hydrogen storage media and reinforcing agents in polymer composites. These latter applications will require vast quantities of nanotubes at competitive prices to be economically feasible. Moreover, reinforcing applications may not require ultrahigh purity nanotubes. Indeed, functionalization of nanotubes to facilitate interfacial bonding within composites will naturally introduce defects into the tube walls, lessening their tensile strength. Current methods of aerosol synthesis of carbon nanotubes include laser ablation of composite targets of carbon and catalyst metal within high temperature furnaces and decomposition of a organometallics in hydrocarbons mixtures within a tube furnace. Common to each approach is the generation of particles in the presence of the reactive hydrocarbon species at elevated temperatures. In the laser-ablation approach, the situation is even more dynamic in that particles and nanotubes are borne during the transient cooling phase of the laser-induced plasma for which the temperature far exceeds that of the surrounding hot gases within the furnace process tube. A shared limitation is that more efficient methods of nanoparticle synthesis are not readily incorporated into these approaches. In contrast, combustion can quite naturally create nanomaterials such as carbon black. Flame synthesis is well known for its commercial scalability and energy efficiency. However, flames do present a complex chemical environment with steep gradients in temperature and species concentrations. Moreover, reaction times are limited within buoyant driven flows to tens of milliseconds. Therein microgravity can greatly lessen temperature and spatial gradients while allowing independent control of flame residence times. In preparation for defining the microgravity experiments, the work presented here focuses

  11. Micromechanics Modeling of Functionally Graded Interphase Regions in Carbon Nanotube-Polymer Composites

    NASA Technical Reports Server (NTRS)

    Seidel, Gary D.; Lagoudas, Dimitris C.; Frankland, Sarah Jane V.; Gates, Thomas S.

    2006-01-01

    The effective elastic properties of a unidirectional carbon fiber/epoxy lamina in which the carbon fibers are coated with single-walled carbon nanotubes are modeled herein through the use of a multi-scale method involving the molecular dynamics/equivalent continuum and micromechanics methods. The specific lamina representative volume element studied consists of a carbon fiber surrounded by a region of epoxy containing a radially varying concentration of carbon nanotubes which is then embedded in the pure epoxy matrix. The variable concentration of carbon nanotubes surrounding the carbon fiber results in a functionally graded interphase region as the properties of the interphase region vary according to the carbon nanotube volume fraction. Molecular dynamics and equivalent continuum methods are used to assess the local effective properties of the carbon nanotube/epoxy comprising the interphase region. Micromechanics in the form of the Mori-Tanaka method are then applied to obtain the global effective properties of the graded interphase region wherein the carbon nanotubes are randomly oriented. Finally, the multi-layer composite cylinders micromechanics approach is used to obtain the effective lamina properties from the lamina representative volume element. It was found that even very small quantities of carbon nanotubes (0.36% of lamina by volume) coating the surface of the carbon fibers in the lamina can have a significant effect (8% increase) on the transverse properties of the lamina (E22, k23, G23 and G12) with almost no affect on the lamina properties in the fiber direction (E11 and v12).

  12. Adsorption site analysis of impurity embedded single-walled carbon nanotube bundles

    USGS Publications Warehouse

    Agnihotri, S.; Mota, J.P.B.; Rostam-Abadi, M.; Rood, M.J.

    2006-01-01

    Bundle morphology and adsorptive contributions from nanotubes and impurities are studied both experimentally and by simulation using a computer-aided methodology, which employs a small physisorbed probe molecule to explore the porosity of nanotube samples. Grand canonical Monte Carlo simulation of nitrogen adsorption on localized sites of a bundle is carried out to predict adsorption in its accessible internal pore volume and on its external surface as a function of tube diameter. External adsorption is split into the contributions from the clean surface of the outermost nanotubes of the bundle and from the surface of the impurities. The site-specific isotherms are then combined into a global isotherm for a given sample using knowledge of its tube-diameter distribution obtained by Raman spectroscopy. The structural parameters of the sample, such as the fraction of open-ended nanotubes and the contributions from impurities and nanotube bundles to total external surface area, are determined by fitting the experimental nitrogen adsorption data to the simulated isotherm. The degree of closure between experimental and calculated adsorption isotherms for samples manufactured by two different methods, to provide different nanotube morphology and contamination level, further strengthens the validity and resulting interpretations based on the proposed approach. The average number of nanotubes per bundle and average bundle size, within a sample, are also quantified. The proposed method allows for extrapolation of adsorption properties to conditions where the purification process is 100% effective at removing all impurities and opening access to all intrabundle adsorption sites. ?? 2006 Elsevier Ltd. All rights reserved.

  13. Self-assembling Functionalized Single-walled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Gao, Yan

    Single-walled carbon nanotubes (SWCNTs) are promising bottom-up building materials due to their superior properties. However, the lack of an effective method to arrange large quantities of SWCNTs poses an obstacle toward their applications. Existing studies to functionalize, disperse, position, and assemble SWCNTs provide a broad understandings regarding SWCNTs behavior, especially in aqueous electrolyte solution. Inspired by ionic polymer metal composite (IPMC) materials, this dissertation envisions fabrication of orderly SWCNTs network structure via their ionic clustering-mediated self-assembly. SWCNTs tend to bundle together due to inter-nanotube VDW attractions, which increase with nanotube length. The author seeks short SWCNTs with long chain molecules bearing ionic termini to facilitate debundling and self-assembly in aqueous electrolyte solution through end-clustering. First, a simple model was applied based on essential physical factors. The results indicated that SWCNTs must be shorter than ˜100 nm to achieve stable network structures. Experiments were then carried out based upon the results. Short SWCNTs (50-100 nm) were end-functionalized with hexaethylene glycol (HEG) linkers bearing terminal carboxylate anions. Both 2D and 3D network structures were observed after placing the functionalized SWCNTs in aqueous electrolyte (sodium ion). The network structures were characterized by microscopic and spectroscopic methods. A novel approach was applied via electron tomography to study the 3D structures of SWCNTs structure in aqueous electrolyte. Free energy analysis of the SWCNTs network structure was implemented with the assistance of both analytical tools and molecular simulations. The results indicate that, when a cluster is formed by three functionalized SWCNTs ends, the resulting network structure is most stable. Indeed, 72% of the clusters/joints were formed by three nanotubes, as observed in experiments. Finally, Monte Carlo simulations of coarse

  14. Short Channel Field-Effect-Transistors with Inkjet-Printed Semiconducting Carbon Nanotubes.

    PubMed

    Jang, Seonpil; Kim, Bongjun; Geier, Michael L; Hersam, Mark C; Dodabalapur, Ananth

    2015-11-01

    Short channel field-effect-transistors with inkjet-printed semiconducting carbon nanotubes are fabricated using a novel strategy to minimize material consumption, confining the inkjet droplet into the active channel area. This fabrication approach is compatible with roll-to-roll processing and enables the formation of high-performance short channel device arrays based on inkjet printing. PMID:26312458

  15. EDITORIAL: Focus on Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    2003-09-01

    The study of carbon nanotubes, since their discovery by Iijima in 1991, has become a full research field with significant contributions from all areas of research in solid-state and molecular physics and also from chemistry. This Focus Issue in New Journal of Physics reflects this active research, and presents articles detailing significant advances in the production of carbon nanotubes, the study of their mechanical and vibrational properties, electronic properties and optical transitions, and electrical and transport properties. Fundamental research, both theoretical and experimental, represents part of this progress. The potential applications of nanotubes will rely on the progress made in understanding their fundamental physics and chemistry, as presented here. We believe this Focus Issue will be an excellent guide for both beginners and experts in the research field of carbon nanotubes. It has been a great pleasure to edit the many excellent contributions from Europe, Japan, and the US, as well from a number of other countries, and to witness the remarkable effort put into the manuscripts by the contributors. We thank all the authors and referees involved in the process. In particular, we would like to express our gratitude to Alexander Bradshaw, who invited us put together this Focus Issue, and to Tim Smith and the New Journal of Physics staff for their extremely efficient handling of the manuscripts. Focus on Carbon Nanotubes Contents <;A article="1367-2630/5/1/117">Transport theory of carbon nanotube Y junctions R Egger, B Trauzettel, S Chen and F Siano The tubular conical helix of graphitic boron nitride F F Xu, Y Bando and D Golberg Formation pathways for single-wall carbon nanotube multiterminal junctions Inna Ponomareva, Leonid A Chernozatonskii, Antonis N Andriotis and Madhu Menon Synthesis and manipulation of carbon nanotubes J W Seo, E Couteau

  16. Spectroscopic study of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Curran, Seamus; Weldon, Declan N.; Blau, Werner J.; Zandbergen, Henny W.; Kastner, J.; Kuzmany, Hans

    1994-11-01

    We present a comprehensive experimental study of the vibrational spectra of nanotubes. There are two main lines observed in the Raman spectrum, one positioned at 1350 cm-1, the D line, and the other at 1580 cm-1, the G line. Both these lines are very similar to those seen with disordered graphite. The disorder induced D line is very weak compared to the G line which is indicative of high crystalline materials. The position and intensity of the D line strongly depends on the energy of the exciting laser. This dispersion effect was also observed for graphitic particles and may be explained by a photoselective resonance process of nanotubes with different sizes. There are two optically active modes in the Infrared spectrum for highly orientated polycrystalline graphite which are the E1u and A2u modes. The E1u mode is positioned at 1587 cm-1 while the A2u mode is positioned at 868 cm-1. The Infrared spectrum of the nanotubes shows both modes although the E1u mode is downshifted to 1575 cm-1.

  17. Hydrogen storage in carbon nanotubes.

    PubMed

    Hirscher, M; Becher, M

    2003-01-01

    The article gives a comprehensive overview of hydrogen storage in carbon nanostructures, including experimental results and theoretical calculations. Soon after the discovery of carbon nanotubes in 1991, different research groups succeeded in filling carbon nanotubes with some elements, and, therefore, the question arose of filling carbon nanotubes with hydrogen by possibly using new effects such as nano-capillarity. Subsequently, very promising experiments claiming high hydrogen storage capacities in different carbon nanostructures initiated enormous research activity. Hydrogen storage capacities have been reported that exceed the benchmark for automotive application of 6.5 wt% set by the U.S. Department of Energy. However, the experimental data obtained with different methods for various carbon nanostructures show an extreme scatter. Classical calculations based on physisorption of hydrogen molecules could not explain the high storage capacities measured at ambient temperature, and, assuming chemisorption of hydrogen atoms, hydrogen release requires temperatures too high for technical applications. Up to now, only a few calculations and experiments indicate the possibility of an intermediate binding energy. Recently, serious doubt has arisen in relation to several key experiments, causing considerable controversy. Furthermore, high hydrogen storage capacities measured for carbon nanofibers did not survive cross-checking in different laboratories. Therefore, in light of today's knowledge, it is becoming less likely that at moderate pressures around room temperature carbon nanostructures can store the amount of hydrogen required for automotive applications. PMID:12908227

  18. Method for nano-pumping using carbon nanotubes

    DOEpatents

    Insepov, Zeke; Hassanein, Ahmed

    2009-12-15

    The present invention relates generally to the field of nanotechnology, carbon nanotubes and, more specifically, to a method and system for nano-pumping media through carbon nanotubes. One preferred embodiment of the invention generally comprises: method for nano-pumping, comprising the following steps: providing one or more media; providing one or more carbon nanotubes, the one or more nanotubes having a first end and a second end, wherein said first end of one or more nanotubes is in contact with the media; and creating surface waves on the carbon nanotubes, wherein at least a portion of the media is pumped through the nanotube.

  19. Molecular Dynamics Modeling of Carbon Nanotubes and Their Composites

    NASA Astrophysics Data System (ADS)

    Jensen, Lars R.; Pyrz, Ryszard

    2004-06-01

    The tensile modulus of individual nanotubes and nanotube-polypropylene composites has been determined using molecular dynamics simulations. Simulations of individual single-walled carbon nanotubes showed that their tensile modulus was dependent on the tube structure and the diameter if the diameter was below 1,6 nm. The tensile modulus was determined for an infinite single-walled carbon nanotube embedded in an amorphous polypropylene matrix and for a finite and capped single-walled carbon nanotube embedded in a polypropylene matrix. For the infinite nanotube-polypropylene system the modulus was found to correspond to the one given by the Voigt approximation. For the finite nanotube-polypropylene system the reinforcing effect of the nanotube was not very pronounced. A pull out simulation showed that the length of the nanotube in the simulation was much smaller than the critical length and hence no load transfer between the nanotube and the matrix existed.

  20. Metallic Electrode: Semiconducting Nanotube Junction Model

    NASA Technical Reports Server (NTRS)

    Yamada, Toshishige; Biegel, Bryon (Technical Monitor)

    2001-01-01

    A model is proposed for two observed current-voltage (I-V) patterns in an experiment with a scanning tunneling microscope tip and a carbon nanotube [Collins et al., Science 278, 100 ('97)]. We claim that there are two contact modes for a tip (metal) -nanotube semi conductor) junction depending whether the alignment of the metal and semiconductor band structure is (1) variable (vacuum-gap) or (2) fixed (touching) with V. With the tip grounded, the tunneling case in (1) would produce large dI/dV with V > 0, small dI/dV with V < 0, and I = 0 near V = 0 for an either n- or p-nanotube. However, the Schottky mechanism in (2) would result in forward current with V < 0 for an n-nanotube, while with V > 0 for an p-nanotube. The two observed I-V patterns are thus entirely explained by a tip-nanotube contact of the two types, where the nanotube must be n-type. We apply this picture to the source-drain I-V characteristics in a long nanotube-channel field-effect-transistor (Zhou et al., Appl. Phys. Lett. 76, 1597 ('00)], and show that two independent metal-semiconductor junctions connected in series are responsible for the observed behavior.

  1. Ophthalmologial Applications of Carbon Nanotube Nanotechology

    NASA Technical Reports Server (NTRS)

    Loftus, David; Girten, Beverly (Technical Monitor)

    2002-01-01

    The development of an implantable device consisting of an array of carbon nanotubes on a silicon chip for restoration of vision in patients with macular degeneration and other retinal disorders is presented. The use of carbon nanotube bucky paper for retinal cell transplantation is proposed. This paper is in viewgraph form.

  2. Mechanical properties of hybrid polymer nanotube systems

    NASA Astrophysics Data System (ADS)

    Coleman, Jonathan N.; Cadek, Martin; Dalton, Alan B.; Munoz, Edgar; Razal, Joselito; Baughman, Ray H.; Blau, Werner J.

    2003-04-01

    In this work, mechanical properties of hybrid materials fabricated from nanotubes and commercially available polymers were investigated. It was found that, by adding various concentrations of arc discharge multiwall nanotubes, both Young"s modulus and hardness increased by factors of 1.8 and 1.6 at 1wt% in PVA and 2.8 and 2.0 at 8wt% in PVK, in reasonable agreement with the Halpin-Tsai theory. Furthermore, the presence of the nanotubes was found to nucleate crystallization of the PVA. This crystal growth is thought to enhance matrix-nanotube stress transfer. In addition, microscopy studies suggest extremely strong interfacial bonding in the PVA-based composite. This is manifested by the fracture of the polymer rather that the polymer-nanotube interface. The dependence of the polymer nanotube interfacial interaction on host polymer was studied by intercalating various polymers (PVA, PVP and PS) into single wall nanotube buckypaper. Even for short soak times, significant polymer intercalation into existing free volume was observed. Depending on the polymer and the level of intercalation tensile tests on intercalated sheets showed that the Young"s modulus, strength and toughness increased by factors of 3, 9 and 28, respectively. This indicates that the intercalated polymer enhances load transmission between nanotubes due the significant stress transfer. The level of stress transfer was observed to scale with polymer hydrophobicity as expected.

  3. Nanotubes based on monolayer blue phosphorus

    NASA Astrophysics Data System (ADS)

    Montes, E.; Schwingenschlögl, U.

    2016-07-01

    We demonstrate structural stability of monolayer zigzag and armchair blue phosphorus nanotubes by means of molecular dynamics simulations. The vibrational spectrum and electronic band structure are determined and analyzed as functions of the tube diameter and axial strain. The nanotubes are found to be semiconductors with a sensitive indirect band gap that allows flexible tuning.

  4. Invisible Hyperbolic Metamaterial Nanotube at Visible Frequency.

    PubMed

    Kim, Kyoung-Ho; No, You-Shin; Chang, Sehwan; Choi, Jae-Hyuck; Park, Hong-Gyu

    2015-01-01

    Subwavelength-scale metal and dielectric nanostructures have served as important building blocks for electromagnetic metamaterials, providing unprecedented opportunities for manipulating the optical response of the matter. Recently, hyperbolic metamaterials have been drawing particular interest because of their unusual optical properties and functionalities, such as negative refraction and hyperlensing of light. Here, as a promising application of a hyperbolic metamaterial at visible frequency, we propose an invisible nanotube that consists of metal and dielectric alternating thin layers. The theoretical study of the light scattering of the layered nanotube reveals that almost-zero scattering can be achieved at a specific wavelength when the transverse-electric- or transverse-magnetic-polarized light is incident to the nanotube. In addition, the layered nanotube can be described as a radial-anisotropic hyperbolic metamaterial nanotube. The low scattering occurs when the effective permittivity of the hyperbolic nanotube in the angular direction is near zero, and thus the invisibility of the layered nanotube can be efficiently obtained by analyzing the equivalent hyperbolic nanotube. Our new method to design and tune an invisible nanostructure represents a significant step toward the practical implementation of unique nanophotonic devices such as invisible photodetectors and low-scattering near-field optical microscopes. PMID:26522815

  5. Invisible Hyperbolic Metamaterial Nanotube at Visible Frequency

    PubMed Central

    Kim, Kyoung-Ho; No, You-Shin; Chang, Sehwan; Choi, Jae-Hyuck; Park, Hong-Gyu

    2015-01-01

    Subwavelength-scale metal and dielectric nanostructures have served as important building blocks for electromagnetic metamaterials, providing unprecedented opportunities for manipulating the optical response of the matter. Recently, hyperbolic metamaterials have been drawing particular interest because of their unusual optical properties and functionalities, such as negative refraction and hyperlensing of light. Here, as a promising application of a hyperbolic metamaterial at visible frequency, we propose an invisible nanotube that consists of metal and dielectric alternating thin layers. The theoretical study of the light scattering of the layered nanotube reveals that almost-zero scattering can be achieved at a specific wavelength when the transverse-electric- or transverse-magnetic-polarized light is incident to the nanotube. In addition, the layered nanotube can be described as a radial-anisotropic hyperbolic metamaterial nanotube. The low scattering occurs when the effective permittivity of the hyperbolic nanotube in the angular direction is near zero, and thus the invisibility of the layered nanotube can be efficiently obtained by analyzing the equivalent hyperbolic nanotube. Our new method to design and tune an invisible nanostructure represents a significant step toward the practical implementation of unique nanophotonic devices such as invisible photodetectors and low-scattering near-field optical microscopes. PMID:26522815

  6. Defect-Free Carbon Nanotube Coils.

    PubMed

    Shadmi, Nitzan; Kremen, Anna; Frenkel, Yiftach; Lapin, Zachary J; Machado, Leonardo D; Legoas, Sergio B; Bitton, Ora; Rechav, Katya; Popovitz-Biro, Ronit; Galvão, Douglas S; Jorio, Ado; Novotny, Lukas; Kalisky, Beena; Joselevich, Ernesto

    2016-04-13

    Carbon nanotubes are promising building blocks for various nanoelectronic components. A highly desirable geometry for such applications is a coil. However, coiled nanotube structures reported so far were inherently defective or had no free ends accessible for contacting. Here we demonstrate the spontaneous self-coiling of single-wall carbon nanotubes into defect-free coils of up to more than 70 turns with identical diameter and chirality, and free ends. We characterize the structure, formation mechanism, and electrical properties of these coils by different microscopies, molecular dynamics simulations, Raman spectroscopy, and electrical and magnetic measurements. The coils are highly conductive, as expected for defect-free carbon nanotubes, but adjacent nanotube segments in the coil are more highly coupled than in regular bundles of single-wall carbon nanotubes, owing to their perfect crystal momentum matching, which enables tunneling between the turns. Although this behavior does not yet enable the performance of these nanotube coils as inductive devices, it does point a clear path for their realization. Hence, this study represents a major step toward the production of many different nanotube coil devices, including inductors, electromagnets, transformers, and dynamos. PMID:26708150

  7. Long conducting polymer nanonecklaces with a `beads-on-a-string' morphology: DNA nanotube-template synthesis and electrical properties

    NASA Astrophysics Data System (ADS)

    Chen, Guofang; Mao, Chengde

    2016-05-01

    Complex and functional nanostructures are always desired. Herein, we present the synthesis of novel long conducting polymer nanonecklaces with a `beads-on-a-string' morphology by the DNA nanotube-template approach and in situ oxidative polymerization of the 3-methylthiophene monomer with FeCl3 as the oxidant/catalyst. The length of the nanonecklaces is up to 60 μm, and the polymer beads of around 20-25 nm in diameter are closely packed along the axis of the DNA nanotube template with a density of ca. 45 particles per μm. The formation of porous DNA nanotubes impregnated with FeCl3 was also demonstrated as intermediate nanostructures. The mechanisms for the formation of both the porous DNA nanotubes and the conducting polymer nanonecklaces are discussed in detail. The as-synthesized polymer/DNA nanonecklaces exhibit good electrical properties.Complex and functional nanostructures are always desired. Herein, we present the synthesis of novel long conducting polymer nanonecklaces with a `beads-on-a-string' morphology by the DNA nanotube-template approach and in situ oxidative polymerization of the 3-methylthiophene monomer with FeCl3 as the oxidant/catalyst. The length of the nanonecklaces is up to 60 μm, and the polymer beads of around 20-25 nm in diameter are closely packed along the axis of the DNA nanotube template with a density of ca. 45 particles per μm. The formation of porous DNA nanotubes impregnated with FeCl3 was also demonstrated as intermediate nanostructures. The mechanisms for the formation of both the porous DNA nanotubes and the conducting polymer nanonecklaces are discussed in detail. The as-synthesized polymer/DNA nanonecklaces exhibit good electrical properties. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr01603k

  8. Atom Vacancies on a Carbon Nanotube: To What Extent Can We Simulate their Effects?

    PubMed

    Kroes, Jaap M H; Pietrucci, Fabio; van Duin, Adri C T; Andreoni, Wanda

    2015-07-14

    Atom vacancies are intrinsic defects of carbon nanotubes. Using a zigzag nanotube as reference, this paper focuses on the comparison of calculations performed within density functional theory and a number of classical force fields widely used for carbon systems. The results refer to single and double vacancies and, in particular, to the induced structural changes, the formation energies, and the energy barriers relative to elementary processes such as reconstruction, migration, and coalescence. Characterization of these processes is remarkably different in the different approaches. These findings are meant to contribute to the construction of DFT-based classical schemes for carbon nanostructures. PMID:26575773

  9. High Coverages of Hydrogen on a (10,0) Carbon Nanotube

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Arnold, James (Technical Monitor)

    2001-01-01

    The binding energy of H to a (10,0) carbon nanotube is calculated at 24, 50, and 100% coverage. Several different bonding configurations are considered for the 50% coverage case. Using the ONIOM (our own n-layered integrated molecular orbital and molecular mechanics) approach, the average C-H bond energy for the most stable 50% coverage and for the 100% coverage are 57.3 and 38.6 kcal/mol, respectively. Considering the size of the bond energy of H2, these values suggest that it will be difficult to achieve 100% atomic H coverage on a (10,0) nanotube.

  10. Quasi-One-Dimensional Electronic States Inside and Outside Helium-Plated Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Motta, M.; Galli, D. E.; Liebrecht, M.; Del Maestro, A.; Cole, M. W.

    2016-06-01

    About one-half a century ago, it was realized that electrons experience a repulsive barrier when approaching the surface of condensed phases of helium, hydrogen, and neon. This led to the proposal and subsequent observation of image-potential surface-bound electronic states, which exhibit intriguing quasi-two-dimensional behavior. In the present work, we report similar quasi-one-dimensional electronic states by exploring single-wall carbon nanotubes coated both inside and outside by thin helium films. Electrons near such structures are localized in the radial direction, but free to move along the nanotube axis. The many-body aspects of the system are discussed qualitatively.

  11. Tunable carbon nanotube-tungsten carbide nanoparticles heterostructures by vapor deposition

    SciTech Connect

    Xia, Min; Guo, Hongyan; Ge, Changchun; Yan, Qingzhi Lang, Shaoting

    2014-05-14

    A simple, versatile route for the synthesis of carbon nanotube (CNT)-tungsten carbide nanoparticles heterostructures was set up via vapor deposition process. For the first time, amorphous CNTs (α-CNTs) were used to immobilized tungsten carbide nanoparticles. By adjusting the synthesis and annealing temperature, α-CNTs/amorphous tungsten carbide, α-CNTs/W{sub 2}C, and CNTs/W{sub 2}C/WC heterostructures were prepared. This approach provides an efficient method to attach other metal carbides and other nanoparticles to carbon nanotubes with tunable properties.

  12. Analytic and computational micromechanics of clustering and interphase effects in carbon nanotube composites.

    SciTech Connect

    Seidel, Gary D.; Hammerand, Daniel Carl; Lagoudas, Dimitris C.

    2006-01-01

    Effective elastic properties for carbon nanotube reinforced composites are obtained through a variety of micromechanics techniques. Using the in-plane elastic properties of graphene, the effective properties of carbon nanotubes are calculated utilizing a composite cylinders micromechanics technique as a first step in a two-step process. These effective properties are then used in the self-consistent and Mori-Tanaka methods to obtain effective elastic properties of composites consisting of aligned single or multi-walled carbon nanotubes embedded in a polymer matrix. Effective composite properties from these averaging methods are compared to a direct composite cylinders approach extended from the work of Hashin and Rosen (1964) and Christensen and Lo (1979). Comparisons with finite element simulations are also performed. The effects of an interphase layer between the nanotubes and the polymer matrix as result of functionalization is also investigated using a multi-layer composite cylinders approach. Finally, the modeling of the clustering of nanotubes into bundles due to interatomic forces is accomplished herein using a tessellation method in conjunction with a multi-phase Mori-Tanaka technique. In addition to aligned nanotube composites, modeling of the effective elastic properties of randomly dispersed nanotubes into a matrix is performed using the Mori-Tanaka method, and comparisons with experimental data are made. Computational micromechanical analysis of high-stiffness hollow fiber nanocomposites is performed using the finite element method. The high-stiffness hollow fibers are modeled either directly as isotropic hollow tubes or equivalent transversely isotropic effective solid cylinders with properties computed using a micromechanics based composite cylinders method. Using a representative volume element for clustered high-stiffness hollow fibers embedded in a compliant matrix with the appropriate periodic boundary conditions, the effective elastic properties

  13. CARBON NANOTUBES: PROPERTIES AND APPLICATIONS

    SciTech Connect

    Fischer, John, E.

    2009-07-24

    Carbon nanotubes were discovered in 1991 as a minority byproduct of fullerene synthesis. Remarkable progress has been made in the ensuing years, including the discovery of two basic types of nanotubes (single-wall and multi-wall), great strides in synthesis and purification, elucidation of many fundamental physical properties, and important steps towards practical applications. Both the underlying science and technological potential of SWNT can profitably be studied at the scale of individual tubes and on macroscopic assemblies such as fibers. Experiments on single tubes directly reveal many of the predicted quantum confinement and mechanical properties. Semiconductor nanowires have many features in common with nanotubes, and many of the same fundamental and practical issues are in play – quantum confinement and its effect on properties; possible device structures and circuit architectures; thermal management; optimal synthesis, defect morphology and control, etc. In 2000 we began a small effort in this direction, conducted entirely by undergraduates with minimal consumables support from this grant. With DOE-BES approval, this grew into a project in parallel with the carbon nanotube work, in which we studied of inorganic semiconductor nanowire growth, characterization and novel strategies for electronic and electromechanical device fabrication. From the beginnings of research on carbon nanotubes, one of the major applications envisioned was hydrogen storage for fuel-cell powered cars and trucks. Subsequent theoretical models gave mixed results, the most pessimistic indicating that the fundamental H2-SWNT interaction was similar to flat graphite (physisorption) with only modest binding energies implying cryogenic operation at best. New material families with encouraging measured properties have emerged, and materials modeling has gained enormously in predictive power, sophistication, and the ability to treat a realistically representative number of atoms. One of

  14. Bulk Cutting of Carbon Nanotubes Using Electron Beam Irradiation

    NASA Technical Reports Server (NTRS)

    Ziegler, Kirk J. (Inventor); Rauwald, Urs (Inventor); Hauge, Robert H. (Inventor); Schmidt, Howard K. (Inventor); Smalley, Richard E. (Inventor); Kittrell, W. Carter (Inventor); Gu, Zhenning (Inventor)

    2013-01-01

    According to some embodiments, the present invention provides a method for attaining short carbon nanotubes utilizing electron beam irradiation, for example, of a carbon nanotube sample. The sample may be pretreated, for example by oxonation. The pretreatment may introduce defects to the sidewalls of the nanotubes. The method is shown to produces nanotubes with a distribution of lengths, with the majority of lengths shorter than 100 tun. Further, the median length of the nanotubes is between about 20 nm and about 100 nm.

  15. Symmetry Properties of Single-Walled BC2N Nanotubes

    SciTech Connect

    Pan, Hui; Feng, Yuan Ping; Lin, Jainyi

    2009-06-01

    The symmetry properties of the single-walled BC2N nanotubes were investigated. All the BC2N nanotubes possess nonsymmorphic line groups. In contrast with the carbon and boron nitride nanotubes, armchair and zigzag BC2N nanotubes belong to different line groups, depending on the index n (even or odd) and the vector chosen. The number of Raman- active phonon modes is almost twice that of the infrared-active phonon modes for all kinds of BC2N nanotubes.

  16. Carbon Nanotube Based Microfluidic Elements for Filtration and Concentration

    SciTech Connect

    Bakajin, O; Ben-Barak, N; Peng, J; Noy, A

    2003-06-25

    We have developed a method for integration of patterned arrays of carbon nanotubes or the ''nanotube mesh'' into microfabricated channels. The method includes standard lithographic methods for patterning and etching the substrate, followed by catalyst patterning, CVD deposition of nanotubes, and anodic bonding of coverslip top. We will describe a carbon nanotube filtering device fabricated using this method and discuss the use of carbon nanotube arrays as molecular concentration and separation media.

  17. Synergistic toughening of composite fibres by self-alignment of reduced graphene oxide and carbon nanotubes.

    PubMed

    Shin, Min Kyoon; Lee, Bommy; Kim, Shi Hyeong; Lee, Jae Ah; Spinks, Geoffrey M; Gambhir, Sanjeev; Wallace, Gordon G; Kozlov, Mikhail E; Baughman, Ray H; Kim, Seon Jeong

    2012-01-01

    The extraordinary properties of graphene and carbon nanotubes motivate the development of methods for their use in producing continuous, strong, tough fibres. Previous work has shown that the toughness of the carbon nanotube-reinforced polymer fibres exceeds that of previously known materials. Here we show that further increased toughness results from combining carbon nanotubes and reduced graphene oxide flakes in solution-spun polymer fibres. The gravimetric toughness approaches 1,000 J g(-1), far exceeding spider dragline silk (165 J g(-1)) and Kevlar (78 J g(-1)). This toughness enhancement is consistent with the observed formation of an interconnected network of partially aligned reduced graphene oxide flakes and carbon nanotubes during solution spinning, which act to deflect cracks and allow energy-consuming polymer deformation. Toughness is sensitive to the volume ratio of the reduced graphene oxide flakes to the carbon nanotubes in the spinning solution and the degree of graphene oxidation. The hybrid fibres were sewable and weavable, and could be shaped into high-modulus helical springs. PMID:22337128

  18. Synergistic toughening of composite fibres by self-alignment of reduced graphene oxide and carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Shin, Min Kyoon; Lee, Bommy; Kim, Shi Hyeong; Lee, Jae Ah; Spinks, Geoffrey M.; Gambhir, Sanjeev; Wallace, Gordon G.; Kozlov, Mikhail E.; Baughman, Ray H.; Kim, Seon Jeong

    2012-01-01

    The extraordinary properties of graphene and carbon nanotubes motivate the development of methods for their use in producing continuous, strong, tough fibres. Previous work has shown that the toughness of the carbon nanotube-reinforced polymer fibres exceeds that of previously known materials. Here we show that further increased toughness results from combining carbon nanotubes and reduced graphene oxide flakes in solution-spun polymer fibres. The gravimetric toughness approaches 1,000 J g-1, far exceeding spider dragline silk (165 J g-1) and Kevlar (78 J g-1). This toughness enhancement is consistent with the observed formation of an interconnected network of partially aligned reduced graphene oxide flakes and carbon nanotubes during solution spinning, which act to deflect cracks and allow energy-consuming polymer deformation. Toughness is sensitive to the volume ratio of the reduced graphene oxide flakes to the carbon nanotubes in the spinning solution and the degree of graphene oxidation. The hybrid fibres were sewable and weavable, and could be shaped into high-modulus helical springs.

  19. Efficient Transfer Doping of Carbon Nanotube Forests by MoO3.

    PubMed

    Esconjauregui, Santiago; D'Arsié, Lorenzo; Guo, Yuzheng; Yang, Junwei; Sugime, Hisashi; Caneva, Sabina; Cepek, Cinzia; Robertson, John

    2015-10-27

    We dope nanotube forests using evaporated MoO3 and observe the forest resistivity to decrease by 2 orders of magnitude, reaching values as low as ∼5 × 10(-5) Ωcm, thus approaching that of copper. Using in situ photoemission spectroscopy, we determine the minimum necessary MoO3 thickness to dope a forest and study the underlying doping mechanism. Homogenous coating and tube compaction emerge as key factors for decreasing the forest resistivity. When all nanotubes are fully coated with MoO3 and packed, conduction channels are created both inside the nanotubes and on the outside oxide layer. This is supported by density functional theory calculations, which show a shift of the Fermi energy of the nanotubes and the conversion of the oxide into a layer of metallic character. MoO3 doping removes the need for chirality control during nanotube growth and represents a step forward toward the use of forests in next-generation electronics and in power cables or conductive polymers. PMID:26375167

  20. Subnanometer Porous Thin Films by the Co-assembly of Nanotube Subunits and Block Copolymers

    SciTech Connect

    Xu, Ting; Zhao, Nana; Ren, Feng; Hourani, Rami; Lee, Ming Tsang; Shu, Jessica Y; Mao, Samuel; Helms, Brett A

    2011-02-22

    Porous thin films containing subnanometer channels oriented normal to the surface exhibit unique transport and separation properties and can serve as selective membranes for separation and protective coatings. While molecularly defined nanoporous inorganic and organic materials abound, generating flexible nanoporous thin films with highly aligned channels over large areas has been elusive. Here, we developed a new approach where the growth of cyclic peptide nanotubes can be directed in a structural framework set by the self-assembly of block copolymers. By conjugating polymers to cyclic peptides, the subunit of an organic nanotube can be selectively solubilized in one copolymer microdomain. The conjugated polymers also mediate the interactions between nanotube and local medium and guide the growth of nanotubes in a confined geometry. This led to subnanometer porous membranes containing high-density arrays of through channels. This new strategy takes full advantage of nanoscopic assembly of BCPs and the reversibility of organic nanotube growth and circumvents impediments associated with aligning and organizing high aspect ratio nano-objects normal to the surface. Furthermore, the hierarchical coassembly strategy described demonstrates the feasibility of synchronizing multiple self-assembly processes to achieve hierarchically structured soft materials with molecular level control.

  1. Well-ordered ZnO nanotube arrays and networks grown by atomic layer deposition

    NASA Astrophysics Data System (ADS)

    Zhang, Yijun; Liu, Ming; Ren, Wei; Ye, Zuo-Guang

    2015-06-01

    Semiconductor ZnO, possessing a large exciton binding energy and wide band gap, has received a great deal of attention because it shows great potential for applications in optoelectronics. Precisely controlling the growth of three-dimensional ZnO nanotube structures with a uniform morphology constitutes an important step forward toward integrating ZnO nanostructures into microelectronic devices. Atomic layer deposition (ALD) technique, featured with self-limiting surface reactions, is an ideal approach to the fabrication of ZnO nanostructures, because it allows for accurate control of the thickness at atomic level and conformal coverage in complex 3D structures. In this work, well-ordered ZnO nanotube arrays and networks are prepared by ALD. The morphology, crystallinity and wall thickness of these nanotube structures are examined for different growth conditions. The microstructure of the ZnO nanotubes is investigated by transmission electron microscopy and X-ray diffraction. The high aspect ratio of ZnO nanotubes provides a large specific area which could enhance the kinetics of chemical reactions taking place between the ZnO and its surroundings, making the potential devices more efficient and compact.

  2. Continuum study on the oscillatory characteristics of carbon nanocones inside single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Ansari, R.; Sadeghi, F.; Darvizeh, M.

    2016-02-01

    This article aims to present a comprehensive study on the oscillatory behavior of concentric carbon nanocones (CNCs) inside carbon nanotubes (CNTs) using a continuum approach. To this end, the optimum radius of nanotube for which the nanocone lies on the tube axis is determined based on the distribution of suction energy. Using the Runge-Kutta numerical integration scheme, the equation of motion is solved numerically to attain the time history of displacement and velocity of nanocone. It is observed that the oscillation of nanocone occurs with respect to its axial equilibrium distance which moves further away from the middle axis of nanotube as the number of pentagons increases. A novel semi-analytical expression as a function of geometrical parameters, initial conditions and cone vertex direction is also proposed for the precise evaluation of oscillation frequency. With respect to the proposed frequency expression, a detailed parametric study is conducted to get an insight into the effects of number of pentagons, cone vertex direction and initial conditions on the oscillatory behavior of CNC-CNT oscillators. It is found that nanocones with more pentagons generate greater maximum frequencies inside nanotubes. Furthermore, it is shown that higher maximum frequencies can be achieved if the nanocone enters the nanotube from base.

  3. Coarse-grained molecular dynamics simulation of water diffusion in the presence of carbon nanotubes.

    PubMed

    Lado Touriño, Isabel; Naranjo, Arisbel Cerpa; Negri, Viviana; Cerdán, Sebastián; Ballesteros, Paloma

    2015-11-01

    Computational modeling of the translational diffusion of water molecules in anisotropic environments entails vital relevance to understand correctly the information contained in the magnetic resonance images weighted in diffusion (DWI) and of the diffusion tensor images (DTI). In the present work we investigated the validity, strengths and weaknesses of a coarse-grained (CG) model based on the MARTINI force field to simulate water diffusion in a medium containing carbon nanotubes (CNTs) as models of anisotropic water diffusion behavior. We show that water diffusion outside the nanotubes follows Ficḱs law, while water diffusion inside the nanotubes is not described by a Ficḱs behavior. We report on the influence on water diffusion of various parameters such as length and concentration of CNTs, comparing the CG results with those obtained from the more accurate classic force field calculation, like the all-atom approach. Calculated water diffusion coefficients decreased in the presence of nanotubes in a concentration dependent manner. We also observed smaller water diffusion coefficients for longer CNTs. Using the CG methodology we were able to demonstrate anisotropic diffusion of water inside the nanotube scaffold, but we could not prove anisotropy in the surrounding medium, suggesting that grouping several water molecules in a single diffusing unit may affect the diffusional anisotropy calculated. The methodologies investigated in this work represent a first step towards the study of more complex models, including anisotropic cohorts of CNTs or even neuronal axons, with reasonable savings in computation time. PMID:26386454

  4. Synergistic toughening of composite fibres by self-alignment of reduced graphene oxide and carbon nanotubes

    PubMed Central

    Shin, Min Kyoon; Lee, Bommy; Kim, Shi Hyeong; Lee, Jae Ah; Spinks, Geoffrey M.; Gambhir, Sanjeev; Wallace, Gordon G.; Kozlov, Mikhail E.; Baughman, Ray H.; Kim, Seon Jeong

    2012-01-01

    The extraordinary properties of graphene and carbon nanotubes motivate the development of methods for their use in producing continuous, strong, tough fibres. Previous work has shown that the toughness of the carbon nanotube-reinforced polymer fibres exceeds that of previously known materials. Here we show that further increased toughness results from combining carbon nanotubes and reduced graphene oxide flakes in solution-spun polymer fibres. The gravimetric toughness approaches 1,000 J g−1, far exceeding spider dragline silk (165 J g−1) and Kevlar (78 J g−1). This toughness enhancement is consistent with the observed formation of an interconnected network of partially aligned reduced graphene oxide flakes and carbon nanotubes during solution spinning, which act to deflect cracks and allow energy-consuming polymer deformation. Toughness is sensitive to the volume ratio of the reduced graphene oxide flakes to the carbon nanotubes in the spinning solution and the degree of graphene oxidation. The hybrid fibres were sewable and weavable, and could be shaped into high-modulus helical springs. PMID:22337128

  5. Broken SU(4) symmetry in a Kondo-correlated carbon nanotube

    NASA Astrophysics Data System (ADS)

    Schmid, Daniel R.; Smirnov, Sergey; Margańska, Magdalena; Dirnaichner, Alois; Stiller, Peter L.; Grifoni, Milena; Hüttel, Andreas K.; Strunk, Christoph

    2015-04-01

    Understanding the interplay between many-body phenomena and nonequilibrium in systems with entangled spin and orbital degrees of freedom is a central objective in nanoelectronics. We demonstrate that the combination of Coulomb interaction, spin-orbit coupling, and valley mixing results in a particular selection of the inelastic virtual processes contributing to the Kondo resonance in carbon nanotubes at low temperatures. This effect is dictated by conjugation properties of the underlying carbon nanotube spectrum at zero and finite magnetic field. Our measurements on a clean carbon nanotube are complemented by calculations based on a field-theoretical Keldysh approach to the nonequilibrium Kondo problem which well reproduces the rich experimental observations in Kondo transport.

  6. Three-particle correlation from a Many-Body Perspective: Trions in a Carbon Nanotube.

    PubMed

    Deilmann, Thorsten; Drüppel, Matthias; Rohlfing, Michael

    2016-05-13

    Trion states of three correlated particles (e.g., two electrons and one hole) are essential to understand the optical spectra of doped or gated nanostructures, like carbon nanotubes or transition-metal dichalcogenides. We develop a theoretical many-body description for such correlated states using an ab initio approach. It can be regarded as an extension of the widely used GW method and Bethe-Salpeter equation, thus allowing for a direct comparison with excitons. We apply this method to a semiconducting (8,0) carbon nanotube, and find that the lowest optically active trions are redshifted by ∼130  meV compared to the excitons, confirming experimental findings for similar tubes. Moreover, our method provides detailed insights in the physical nature of trion states. In the prototypical carbon nanotube we find a variety of different excitations, discuss the spectra, energy compositions, and correlated wave functions. PMID:27232034

  7. Imaging the operation of a carbon nanotube charge sensor at the nanoscale.

    PubMed

    Brunel, David; Mayer, Alexandre; Mélin, Thierry

    2010-10-26

    Carbon nanotube field effect transistors (CNTFETs) are of great interest for nanoelectronics applications such as nonvolatile memory elements (NVMEs) or charge sensors. In this work, we use a scanning-probe approach based on a local charge perturbation of CNTFET-based NVMEs and investigate their fundamental operation from combined transport, electrostatic scanning probe techniques and atomistic simulations. We experimentally demonstrate operating devices with threshold voltages shifts opposite to conventional gating and with almost unchanged hysteresis. The former effect is quantitatively understood as the emission of a delocalized image charge pattern in the nanotube environment, in response to local charge storage, while the latter effect points out the dominant dipolar nature of hysteresis in CNTFETs. We propose a simple model for charge sensing using CNTFETs, based on the redistribution of the nanotube image charges. This model could be extended to gas or biosensing, for example. PMID:20866060

  8. Three-particle correlation from a Many-Body Perspective: Trions in a Carbon Nanotube

    NASA Astrophysics Data System (ADS)

    Deilmann, Thorsten; Drüppel, Matthias; Rohlfing, Michael

    2016-05-01

    Trion states of three correlated particles (e.g., two electrons and one hole) are essential to understand the optical spectra of doped or gated nanostructures, like carbon nanotubes or transition-metal dichalcogenides. We develop a theoretical many-body description for such correlated states using an ab initio approach. It can be regarded as an extension of the widely used G W method and Bethe-Salpeter equation, thus allowing for a direct comparison with excitons. We apply this method to a semiconducting (8,0) carbon nanotube, and find that the lowest optically active trions are redshifted by ˜130 meV compared to the excitons, confirming experimental findings for similar tubes. Moreover, our method provides detailed insights in the physical nature of trion states. In the prototypical carbon nanotube we find a variety of different excitations, discuss the spectra, energy compositions, and correlated wave functions.

  9. Liquid crystal cells with built-in CdSe nanotubes for chromogenic smart emission devices.

    PubMed

    Lin, Tsung Ju; Chen, Chin-Chang; Cheng, Soofin; Chen, Yang Fang

    2008-01-21

    A simple and general approach for controlling optical anisotropy of nanostructured semiconductors is reported. Our design involves the fabrication of liquid crystal devices with built-in semiconductor nanotubes. Quite interestingly, it is found that semiconductor nanotubes can be well aligned along the orientation of liquid crystals molecules automatically, resulting in a very large emission anisotropy with the degree of polarization up to 72%. This intriguing result manifests a way to obtain well aligned semiconductor nanotubes and the emission anisotropy can be easily manipulated by an external bias. The ability to well control the emission anisotropy should open up new opportunities for nanostructured semiconductors, including optical filters, polarized light emitting diodes, flat panel displays, and many other chromogenic smart devices. PMID:18542142

  10. Hydrogen-bond acidic functionalized carbon nanotubes (CNTs) with covalently-bound hexafluoroisopropanol groups

    SciTech Connect

    Fifield, Leonard S.; Grate, Jay W.

    2010-06-01

    Fluorinated hydrogen-bond acidic groups are directly attached to the backbone of single walled carbon nanotubes (SWCNTs) without the introduction of intermediate electron donating surface groups. Hexafluoroalcohol functional groups are exceptionally strong hydrogen bond acids, and are added to the nanotube surface using the aryl diazonium approach to create hydrogen-bond acidic carbon nanotube (CNT) surfaces. These groups can promote strong hydrogen-bonding interactions with matrix materials in composites or with molecular species to be concentrated and sensed. In the latter case, this newly developed material is expected to find useful application in chemical sensors and in CNT-based preconcentrator devices for the detection of pesticides, chemical warfare agents and explosives.

  11. Remote Biodegradation of Ge-Imogolite Nanotubes Controlled by the Iron Homeostasis of Pseudomonas brassicacearum.

    PubMed

    Avellan, Astrid; Auffan, Melanie; Masion, Armand; Levard, Clément; Bertrand, Marie; Rose, Jérôme; Santaella, Catherine; Achouak, Wafa

    2016-07-19

    The toxicity of high-aspect-ratio nanomaterials (HARNs) is often associated with oxidative stress. The essential nutrient Fe may also be responsible of oxidative stress through the production of reactive oxygen species. In the present study, it has been examined to what extent adding Fenton reaction promoting Fe impacted the toxicity of an alumino-germanate model HARN. Structural addition of only 0.95% wt Fe to Ge-imogolite not only alleviated the toxicity observed in the case of Fe-free nanotubes but also stimulated bacterial growth. This was attributed to the metabolization of siderophore-mobilized Fe from the nanotube structure. This was evidenced by the regulation of the homeostasis-monitoring intracellular Fe levels. This was accompanied by a biodegradation of the nanotubes approaching 40%, whereas the Fe-free nanomaterial remained nearly untouched. PMID:27347687

  12. Torsional vibration of single-walled carbon nanotubes using doublet mechanics

    NASA Astrophysics Data System (ADS)

    Fatahi-Vajari, Alireza; Imam, Ali

    2016-08-01

    This paper investigates the torsional vibration of single-walled carbon nanotubes (SWCNTs) using a new approach based on doublet mechanics (DM) incorporating explicitly scale parameter and chiral effects. A fourth-order partial differential equation that governs the torsional vibration of nanotubes is derived. Using DM, an explicit equation for the natural frequency in terms of geometrical and mechanical property of CNTs is obtained for both the Zigzag and Armchair nanotube for the torsional vibration mode. It is shown that chiral effects along with the scale parameter play a significant role in the vibration behavior of SWCNTs in torsional vibration mode. Such effects decrease the natural frequency obtained by DM compared to the classical continuum mechanics and nonlocal theory predictions. However, with increase in the length and/or the radius of the tube, the effect of the chiral and scale parameter on the natural frequency decreases.

  13. Design of porous C@Fe3O4 hybrid nanotubes with excellent microwave absorption.

    PubMed

    Meng, Fanbin; Wei, Wei; Chen, Xiangnan; Xu, Xiaoling; Jiang, Man; Jun, Lu; Wang, Yong; Zhou, Zuowan

    2016-01-28

    An efficient method was developed to fabricate a porous hybridizing nanotubes structure of amorphous carbon interspersed among Fe3O4 (C@Fe3O4) with a ∼200 nm diameter and ∼70 nm wall thickness. The as-structured porous nanotubes with ferromagnetic behaviour exhibited excellent microwave absorption properties, including a strong ability to attenuate the electromagnetic (EM) wave, and they are also lightweight. Adding only 10 wt% of the as-prepared sample into paraffin can show a maximum reflection loss of -45.0 dB at 6.18 GHz with a sample thickness of 3.4 mm. The absorption mechanism, which results from its porous nanotubes structure, multi-interfaces, dielectric-magnetic integration and geometric effect, is proposed to explain the excellent EM absorption performance. Furthermore, the synthesis strategy presented herein can be expended as a facile approach to synthesizing related carbon-based nanostructures for functional design and applications. PMID:26698330

  14. Enhanced light emission from carbon nanotubes integrated in silicon micro-resonator

    NASA Astrophysics Data System (ADS)

    Noury, Adrien; Le Roux, Xavier; Vivien, Laurent; Izard, Nicolas

    2015-08-01

    Single-walled carbon nanotubes are considered a fascinating nanomaterial for photonic applications and are especially promising for efficient light emitters in the telecommunication wavelength range. Furthermore, their hybrid integration with silicon photonic structures makes them an ideal platform to explore their intrinsic properties. Here we report on the strong photoluminescence enhancement from carbon nanotubes integrated in silicon ring resonator circuits under two pumping configurations: surface-illuminated pumping at 735 nm and collinear pumping at 1.26 μ {{m}}. Extremely efficient rejection of the non-resonant photoluminescence was obtained. In the collinear approach, an emission efficiency enhancement by a factor of 26 has been demonstrated in comparison with the classical pumping scheme. This demonstration paves the way for the development of integrated light sources in silicon based on carbon nanotubes.

  15. The atomistic mechanism of carbon nanotube cutting catalyzed by nickel under an electron beam

    NASA Astrophysics Data System (ADS)

    Lebedeva, Irina V.; Chamberlain, Thomas W.; Popov, Andrey M.; Knizhnik, Andrey A.; Zoberbier, Thilo; Biskupek, Johannes; Kaiser, Ute; Khlobystov, Andrei N.

    2014-11-01

    The cutting of single-walled carbon nanotubes by an 80 keV electron beam catalyzed by nickel clusters is imaged in situ using aberration-corrected high-resolution transmission electron microscopy. Extensive molecular dynamics simulations within the CompuTEM approach provide insight into the mechanism of this process and demonstrate that the combination of irradiation and the nickel catalyst is crucial for the cutting process to take place. The atomistic mechanism of cutting is revealed by a detailed analysis of irradiation-induced reactions of bond reorganization and atom ejection in the vicinity of the nickel cluster, showing a highly complex interplay of different chemical transformations catalysed by the metal cluster. One of the most prevalent pathways includes three consecutive stages: formation of polyyne carbon chains from the carbon nanotube, dissociation of the carbon chains into single and pairs of adatoms adsorbed on the nickel cluster, and ejection of these adatoms leading to the cutting of the nanotube. Significant variations in the atom ejection rate are discovered depending on the process stage and nanotube diameter. The revealed mechanism and kinetic characteristics of the cutting process provide fundamental knowledge for the development of new methodologies for control and manipulation of carbon structures at the nanoscale.The cutting of single-walled carbon nanotubes by an 80 keV electron beam catalyzed by nickel clusters is imaged in situ using aberration-corrected high-resolution transmission electron microscopy. Extensive molecular dynamics simulations within the CompuTEM approach provide insight into the mechanism of this process and demonstrate that the combination of irradiation and the nickel catalyst is crucial for the cutting process to take place. The atomistic mechanism of cutting is revealed by a detailed analysis of irradiation-induced reactions of bond reorganization and atom ejection in the vicinity of the nickel cluster, showing a

  16. Label-free electronic detection of bio-toxins using aligned carbon nanotubes.

    PubMed

    Palaniappan, Al; Goh, W H; Fam, D W H; Rajaseger, G; Chan, C E Z; Hanson, B J; Moochhala, S M; Mhaisalkar, S G; Liedberg, B

    2013-05-15

    A facile route for sensitive label-free detection of bio-toxins using aligned single walled carbon nanotubes is described. This approach involves patterning of a catalyst on the surface of a quartz substrate using a sub-100 μm stripe-patterned polydimethylsiloxane stamp for aligned carbon nanotube generation followed by fabrication of field effect transistor (FET). Atomic force microscopy, field emission scanning electron microscopy and Raman spectroscopy are employed to characterize the synthesized nanotubes. Unlike previous reports, the adopted approach enables direct electronic detection of bio-toxins with sensitivities comparable to ELISA. As a proof of concept, the fabricated FET responds to nM concentration levels (with a LOD of ∼2 nM) of epsilon toxin produced by Clostridium perfringens and a prominent food toxin. This facile approach could be customized to detect other classes of toxins and biomarkers upon appropriate functionalization of the aligned carbon nanotubes. Finally, we demonstrate the use of the FET-platform for detection of toxin in more complex matrices such as orange juice. PMID:23298625

  17. Molecular dynamics simulations of electron and ion beam irradiation of multiwalled carbon nanotubes: The effects on failure by inner tube sliding

    SciTech Connect

    Pregler, Sharon K.; Sinnott, Susan B.

    2006-06-01

    Irradiation of nanotube structures with electron and ion beams has been used to produce functionalized nanotubes and fundamentally new structures, including junctions. Here, we build on previous studies to investigate the low-energy electron and ion (Ar and CF{sub 3}) beam irradiation of triple-walled carbon nanotubes that consist entirely of either chiral or armchair tubes. Effective incident energies of 50 eV/ion and 50 keV/electron are considered. The approach is classical molecular dynamic simulations using reactive empirical bond-order potentials and the primary knock-on atom approach to model the effects of electron irradiation. The results indicate that these various irradiation processes produce local damage to the nanotubes that includes crosslinking, that the degree of damage depends to some degree on the chirality of the nanotubes, and that the radial distribution of crosslinks depends significantly on the irradiating particle. Importantly, the effect of these crosslinks, and their radial distribution along the circumference of the nanotube, on the tendency of multiwalled nanotubes to fail by the sword-in-sheath mechanism is examined.

  18. Vibration, buckling and impact of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Pentaras, Demetris

    Natural frequencies of the double and triple-walled carbon nanotubes are determined exactly and approximately for both types. Approximate solutions are found by using Bubnov-Galerkin and Petrov-Galerkin methods. For the first time explicit expressions are obtained for the natural frequencies of double and triple-walled carbon nanotubes for different combinations of boundary conditions. Comparison of the results with recent studies shows that the above methods constitute quick and effective alternative techniques to exact solution for studying the vibration properties of carbon nanotubes. The natural frequencies of the clamped-clamped double-walled carbon nanotubes are obtained; exact solution is provided and compared with the solution reported in the literature. In contrast to earlier investigation, an analytical criterion is derived to establish the behavior of the roots of the characteristic equation. Approximate Bubnov-Galerkin solution is also obtained to compare natural frequencies at the lower end of the spectrum. Simplified version of the Bresse-Timoshenko theory that incorporates the shear deformation and the rotary inertia is proposed for free vibration study of double-walled carbon nanotubes. It is demonstrated that the suggested set yields extremely accurate results for the lower spectrum of double-walled carbon nanotube. The natural frequencies of double-walled carbon nanotubes based on simplified versions of Donnell shell theory are also obtained. The buckling behavior of the double-walled carbon nanotubes under various boundary conditions is studied. First, the case of the simply supported double-walled carbon nanotubes at both ends is considered which is amenable to exact solution. Then, approximate methods of Bubnov-Galerkin and Petrov-Galerkin are utilized to check the efficacy of these approximations for the simply supported double-walled carbon nanotubes. Once the extreme accuracy is demonstrated for simply supported conditions, the approximate

  19. Nanorods and nanotubes: Synthesis, manipulation and properties

    NASA Astrophysics Data System (ADS)

    Wong, Eric Warren

    Nanorods and nanotubes represent idealized structures for investigating phenomena associated with reduced dimensionality and are potential building blocks for nanostructured materials. Understanding their synthesis as well as physical properties is crucial if they are to form the basis for future devices. The synthesis of carbide nanotubes and nanorods is described. Also presented is a general method that combines micropatterning techniques with scanning force microscopy (SFM) to probe individual quasi-one-dimensional materials. Polycrystalline TiC and NbC nanorods, with 20-30 nm diameters and lengths exceeding 1 mum, were synthesized by reacting gaseous Ti-I or Nb-I at 550-1100sp°C with carbon nanotubes which served as structural templates. Template growth from nanotubes appears general since polycrystalline BCsb{x} and amorphous Fesb3C nanorods were produced from Bsb2Osb2 and FeClsb3, respectively. However, reaction of Si-I precursors with nanotubes or graphite above 1050sp°C resulted in single crystal SiC nanorods, with 1-20 nm diameters and 1-20 mum lengths, that grew catalytically from MoSisb2 nanoparticles by a vapor-solid mechanism. Above 1200sp°C, single crystal TiC nanorods grew from nanotubes and Ti-I or TiO by an undetermined mechanism. To probe electrical transport in carbon nanotubes, a method was devised where a static gold contact was lithographically formed with one end of a nanotube while a second dynamic contact was made by a conducting SFM probe. The conducting SFM tip can simultaneously map the topography and conductance of the nanotube. The transport properties of a series of structurally distinct nanotubes were studied and shown to sensitively depend on their structure, the presence of defects causing dramatic increases in resistivity. The mechanics of SiC nanorods and carbon nanotubes were studied using an analogous technique. An SFM tip was used to measure the forces required to bend nanobeams. The SiC nanorods had elastic moduli in close

  20. Nanosensing applications of In IIO 3 nanowires and carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Zhou, Chongwu; Li, Chao; Curreli, Marco; Lin, Henry; Ishikawa, Fumiaki N.; Datar, Ram; Cote, Richard J.; Thompson, Mark E.

    2005-11-01

    We report complementary detection of prostate-specific antigen (PSA) using n-type In IIO 3 nanowires and p-type carbon nanotubes. Our innovation involves developing an approach to covalently attach antibodies to In IIO 3 NW surfaces via the onsite surface synthesis of phosphoric acid-succinylimide ester. Electronic measurements under dry conditions revealed complementary response for In IIO 3 NW and SWNT devices after the binding of PSA. Real time detection in solution has also been demonstrated for PSA down to 5 ng/mL, a benchmark concentration significant for clinical diagnosis of prostate cancer, which is the most frequently diagnosed cancer.

  1. Enhanced shot noise in carbon nanotube field-effect transistors

    SciTech Connect

    Betti, A.; Fiori, G.; Iannaccone, G.

    2009-12-21

    We predict shot noise enhancement in defect-free carbon nanotube field-effect transistors through a numerical investigation based on the self-consistent solution of the Poisson and Schroedinger equations within the nonequilibrium Green's functions formalism, and on a Monte Carlo approach to reproduce injection statistics. Noise enhancement is due to the correlation between trapping of holes from the drain into quasibound states in the channel and thermionic injection of electrons from the source, and can lead to an appreciable Fano factor of 1.22 at room temperature.

  2. Measurement of the rate of water translocation through carbon nanotubes.

    PubMed

    Qin, Xingcai; Yuan, Quanzi; Zhao, Yapu; Xie, Shubao; Liu, Zhongfan

    2011-05-11

    We present an approach for measuring the water flow rate through individual ultralong carbon nanotubes (CNTs) using field effect transistors array defined on individual tubes. Our work exhibits a rate enhancement of 882-51 and a slip length of 53-8 nm for CNTs with diameters of 0.81-1.59 nm. We also found that the enhancement factor does not increase monotonically with shrinking tube diameter and there exists a discontinuous region around 0.98-1.10 nm. We believe that these single-tube level results would help understand the intrinsic nanofluidics of water in CNTs. PMID:21462938

  3. Use of Functionalized Carbon Nanotubes for Covalent Attachment of Nanotubes to Silicon

    NASA Technical Reports Server (NTRS)

    Tour, James M.; Dyke, Christopher A.; Maya, Francisco; Stewart, Michael P.; Chen, Bo; Flatt, Austen K.

    2012-01-01

    The purpose of the invention is to covalently attach functionalized carbon nanotubes to silicon. This step allows for the introduction of carbon nanotubes onto all manner of silicon surfaces, and thereby introduction of carbon nano - tubes covalently into silicon-based devices, onto silicon particles, and onto silicon surfaces. Single-walled carbon nanotubes (SWNTs) dispersed as individuals in surfactant were functionalized. The nano - tube was first treated with 4-t-butylbenzenediazonium tetrafluoroborate to give increased solubility to the carbon nanotube; the second group attached to the sidewall of the nanotube has a silyl-protected terminal alkyne that is de-protected in situ. This gives a soluble carbon nanotube that has functional groups appended to the sidewall that can be attached covalently to silicon. This reaction was monitored by UV/vis/NJR to assure direct covalent functionalization.

  4. Assembly of supramolecular nanotubes from molecular triangles and 1,2-dihalohydrocarbons.

    PubMed

    Liu, Zhichang; Liu, Guoliang; Wu, Yilei; Cao, Dennis; Sun, Junling; Schneebeli, Severin T; Nassar, Majed S; Mirkin, Chad A; Stoddart, J Fraser

    2014-11-26

    Precise control of molecular assembly is a challenging goal facing supramolecular chemists. Herein, we report the highly specific assembly of a range of supramolecular nanotubes from the enantiomeric triangular naphthalenediimide-based macrocycles (RRRRRR)- and (SSSSSS)-NDI-Δ and a class of similar solvents, namely, the 1,2-dihalo-ethanes and -ethenes (DXEs). Three kinds of supramolecular nanotubes are formed from the columnar stacking of NDI-Δ units with a 60° mutual rotation angle as a result of cooperative [C-H···O] interactions, directing interactions of the [X···X]-bonded DXE chains inside the nanotubes and lateral [X···π] or [π···π] interactions. They include (i) semiflexible infinite nanotubes formed in the gel state from NDI-Δ and (E)-1,2-dichloroethene, (ii) rigid infinite nonhelical nanotubes produced in the solid state from NDI-Δ and BrCH2CH2Br, ClCH2CH2Br, and ClCH2CH2I, and (iii) a pair of rigid tetrameric, enantiomeric single-handed (P)- and (M)-helical nanotubes formed in the solid state from the corresponding (RRRRRR)- and (SSSSSS)-NDI-Δ with ClCH2CH2Cl. In case (i), only the electron-rich C═C double bond of (E)-1,2-dichloroethene facilitates the gelation of NDI-Δ. In cases (ii) and (iii), the lengths of anti-DXEs determine the translation of the chirality of NDI-Δ into the helicity of nanotubes. Only ClCH2CH2Cl induces single-handed helicity into the nanotubes. The subtle interplay of noncovalent bonding interactions, resulting from the tiny structural variations involving the DXE guests, is responsible for the diverse and highly specific assembly of NDI-Δ. This research highlights the critical role that guests play in constructing assembled superstructures of hosts and offers a novel approach to creating supramolecular nanotubes. PMID:25357152

  5. Carbon nanotubes randomly decorated with gold clusters: from nano2hybrid atomic structures to gas sensing prototypes

    NASA Astrophysics Data System (ADS)

    Charlier, J.-C.; Arnaud, L.; Avilov, I. V.; Delgado, M.; Demoisson, F.; Espinosa, E. H.; Ewels, C. P.; Felten, A.; Guillot, J.; Ionescu, R.; Leghrib, R.; Llobet, E.; Mansour, A.; Migeon, H.-N.; Pireaux, J.-J.; Reniers, F.; Suarez-Martinez, I.; Watson, G. E.; Zanolli, Z.

    2009-09-01

    Carbon nanotube surfaces, activated and randomly decorated with metal nanoclusters, have been studied in uniquely combined theoretical and experimental approaches as prototypes for molecular recognition. The key concept is to shape metallic clusters that donate or accept a fractional charge upon adsorption of a target molecule, and modify the electron transport in the nanotube. The present work focuses on a simple system, carbon nanotubes with gold clusters. The nature of the gold-nanotube interaction is studied using first-principles techniques. The numerical simulations predict the binding and diffusion energies of gold atoms at the tube surface, including realistic atomic models for defects potentially present at the nanotube surface. The atomic structure of the gold nanoclusters and their effect on the intrinsic electronic quantum transport properties of the nanotube are also predicted. Experimentally, multi-wall CNTs are decorated with gold clusters using (1) vacuum evaporation, after activation with an RF oxygen plasma and (2) colloid solution injected into an RF atmospheric plasma; the hybrid systems are accurately characterized using XPS and TEM techniques. The response of gas sensors based on these nano2hybrids is quantified for the detection of toxic species like NO2, CO, C2H5OH and C2H4.

  6. Nearly exclusive growth of small diameter semiconducting single-wall carbon nanotubes from organic chemistry synthetic end-cap molecules.

    PubMed

    Liu, Bilu; Liu, Jia; Li, Hai-Bei; Bhola, Radha; Jackson, Edward A; Scott, Lawrence T; Page, Alister; Irle, Stephan; Morokuma, Keiji; Zhou, Chongwu

    2015-01-14

    The inability to synthesize single-wall carbon nanotubes (SWCNTs) possessing uniform electronic properties and chirality represents the major impediment to their widespread applications. Recently, there is growing interest to explore and synthesize well-defined carbon nanostructures, including fullerenes, short nanotubes, and sidewalls of nanotubes, aiming for controlled synthesis of SWCNTs. One noticeable advantage of such processes is that no metal catalysts are used, and the produced nanotubes will be free of metal contamination. Many of these methods, however, suffer shortcomings of either low yield or poor controllability of nanotube uniformity. Here, we report a brand new approach to achieve high-efficiency metal-free growth of nearly pure SWCNT semiconductors, as supported by extensive spectroscopic characterization, electrical transport measurements, and density functional theory calculations. Our strategy combines bottom-up organic chemistry synthesis with vapor phase epitaxy elongation. We identify a strong correlation between the electronic properties of SWCNTs and their diameters in nanotube growth. This study not only provides material platforms for electronic applications of semiconducting SWCNTs but also contributes to fundamental understanding of the growth mechanism and controlled synthesis of SWCNTs. PMID:25521257

  7. ZnO nanorod-templated well-aligned ZrO2 nanotube arrays for fibroblast adhesion and proliferation

    NASA Astrophysics Data System (ADS)

    Lu, Zhisong; Zhu, Zhihong; Liu, Jinping; Hu, Weihua; Li, Chang Ming

    2014-05-01

    Cellular responses to porous tubular structures have recently been investigated in highly ordered ZrO2 nanotube arrays fabricated with anodization. However, the potential applications of the nanotube arrays are hindered by instrument requirements and substrate limitations, as well as by the complicated processes needed for synthesis. In this work, ZrO2 nanotube arrays were synthesized by in situ hydrolysis of zirconium propoxide with a zinc oxide nanorod array-based template. Fibroblast cells were able to grow on the nanotube array surface with produced elongated filopodia. Studies of the capability of cell growth and the expression of adhesion- and proliferation-related genes reveal that ZrO2 nanotube arrays may provide a better environment for cell adhesion and growth than a flat titanium surface. These findings not only provide fundamental insight into cell response to nanostructures but also provide an opportunity to use a unique approach to fabricate ZrO2 nanotube array structures for potential implant applications.

  8. Optical properties of titanium dioxide nanotube arrays

    SciTech Connect

    Abdelmoula, Mohamed; Sokoloff, Jeffrey; Lu, Wen-Tao; Menon, Latika; Close, Thomas; Richter, Christiaan

    2014-01-07

    We present experimental measurements and a theoretical analysis of the near UV to NIR optical properties of free standing titania nanotube arrays. An improved understanding of the optical physics of this type of nanostructure is important to several next generation solar energy conversion technologies. We measured the transmission, reflection, and absorption of the electromagnetic spectrum from 300 nm to 1000 nm (UV to NIR) of titania nanotube arrays. We measured the total, specular, and diffuse reflection and transmission using both single point detection and an integrating sphere spectrometer. We find that the transmission, but not the reflection, of light (UV to NIR) through the nanotube array is well-explained by classic geometric optics using an effective medium model taking into account the conical geometry of the nanotubes. For wavelengths shorter than ∼500 nm, we find the surprising result that the reflection coefficient for light incident on the open side of the nanotube array is greater than the reflection coefficient for light incident on the closed “floor” of the nanotube array. We consider theoretical models based on the eikonal approximation, photonic crystal band theory, and a statistical treatment of scattering to explain the observed data. We attribute the fact that light with wavelengths shorter than 500 nm is more highly reflected from the open than the closed tube side as being due to disorder scattering inside the nanotube array.

  9. Real Time Observation of DNA Nanotube Assembly

    NASA Astrophysics Data System (ADS)

    Verde, Lisa Val

    2006-03-01

    DNA nanotubes are of interest for applications ranging from nanofabrication to biophysical studies. The DNA Nanotubes used in this research are self-assembling structures composed of DNA double-crossover tiles. These tiles are simply two connected helices composed of five single stranded DNA oligomers. Each tile exposes four sticky ends responsible for the linkage between neighboring tiles. This linkage creates the nanotube lattice, with intrinsic curvature. The curvature orients each tile with a 60^o angle from the previous one so that six tiles make up the circumference of a nanotube. Nanotube stability depends on conditions such as ionic strength and temperature. A PCR machine is used to anneal the strands into nanotubes. A duplicated annealing process was constructed under a light microscope. PVP (polyvinyl prolidone) coated glass both confined the DNA nanotubes to a 2-3 μm focal plane and prevented them from sticking to the sample surface. By the time the tubes were long enough to track (>= 3 μm), they continued to lengthen primarily via end-to-end joining with some reaching lengths greater than 100 μm. These observations helped define more efficient annealing protocols that resulted in tubes with fewer imperfections.

  10. Functionalization of carbon nanotubes with silver clusters

    NASA Astrophysics Data System (ADS)

    Cveticanin, Jelena; Krkljes, Aleksandra; Kacarevic-Popovic, Zorica; Mitric, Miodrag; Rakocevic, Zlatko; Trpkov, Djordje; Neskovic, Olivera

    2010-09-01

    In this paper, an advanced method of one-step functionalization of single and multi walled carbon nanotubes (SWCNTs and MWCNTs) using γ-irradiation was described. Two synthesis procedures, related with different reduction species, were employed. For the first time, poly(vinyl alcohol) PVA is successfully utilized as a source to reduce silver (Ag) metal ions without having any additional reducing agents to obtain Ag nanoparticles on CNTs. The decoration of carbon nanotubes with Ag nanoparticles takes place through anchoring of (PVA) on nanotube's surface. Optical properties of as-prepared samples and mechanism responsible for the functionalization of carbon nanotubes were investigated using UV-vis and FTIR spectroscopy, respectively. Decorated carbon nanotubes were visualized using microscopic techniques: transmission electron microscopy and scanning tunneling microscopy. Also, the presence of Ag on the nanotubes was confirmed using energy dispersive X-ray spectroscopy. This simple and effective method of making a carbon nanotube type of composites is of interest not only for an application in various areas of technology and biology, but for investigation of the potential of radiation technology for nanoengineering of materials.

  11. Liquid crystal-carbon nanotubes mixtures

    NASA Astrophysics Data System (ADS)

    Popa-Nita, V.; Kralj, S.

    2010-01-01

    The self-organizing properties of nematic liquid crystals (LCs) can be used to align carbon nanotubes (CNTs) dispersed in them. In the previous paper [P. van der Schoot, V. Popa-Nita, and S. Kralj, J. Phys. Chem. B 112, 4512 (2008)], we have considered the weak anchoring limit of the nematic LC molecules at the nanotube's surface, where the CNT alignment is caused by the anisotropic interfacial tension of the nanotubes in the nematic host fluid. In this paper, we present the theoretical results obtained for strong enough anchoring at the CNT-LC interface for which the nematic ordering around nanotube is apparently distorted. Consequently, relatively strong long-range and anisotropic interactions can emerge within the system. In order to get insight into the impact of LC ordering on the alignment of nanotubes we treat the two mixture components on the same footing and combine Landau-de Gennes free energy for the thermotropic ordering of the liquid crystal and Doi free energy for lyotropic nematic ordering of carbon nanotubes caused by their mutually excluded volume. The phase ordering of the binary mixture is analyzed as a function of the volume fraction of the carbon nanotubes, the strength of coupling, and the temperature. We find that the degree of ordering of the nanorods can be tuned by raising or lowering the temperature or by increasing or decreasing their concentration.

  12. Nanotube Production and Applications at Johnson Space Center

    NASA Technical Reports Server (NTRS)

    Nikolaev, Pavel; Files, Bradley; Arepalli, Sivaram; Scott, Carl; Holmes, William; Nicholson, Leonard S. (Technical Monitor)

    2000-01-01

    Promise of applications of carbon nanotubes has led to an intense effort at NASA/JSC, especially in the area of nanotube composites. Using the extraordinary mechanical strength of nanotubes, NASA hopes to design this revolutionary lightweight material for use in aerospace applications. Current research focuses on structural polymeric materials to attempt to lower the weight of spacecraft necessary for interplanetary missions. Other applications of nanotubes are also of interest for energy storage, gas storage, nanoelectronics, field emission, and biomedical applications. In pursuit of these goals, we have set up both laser and arc production processes for nanotubes. An in-depth diagnostic study of the plasma plume in front of the laser target has been studied to try to determine nanotube growth mechanisms. Complementary studies of characterization of nanotube product have added to knowledge of growth conditions. Results of our preliminary experiments in incorporating nanotubes into composites will be presented. Morphology and mechanical properties of the nanotubes composites will be discussed.

  13. Formation mechanism of silicon carbide nanotubes with special morphology

    NASA Astrophysics Data System (ADS)

    Pei, L. Z.; Tang, Y. H.; Zhao, X. Q.; Chen, Y. W.; Guo, C.

    2006-08-01

    SiC nanotubes have been synthesized under hydrothermal conditions. Research results show that SiC nanotubes consist of hollow inner pore, crystalline SiC wall layers, and thin amorphous silica sheath. Besides most abundant normal nanotubes, bamboo-shaped SiC nanotubes and elliptically hollow SiC nanospheres were also observed. The different morphologies of the SiC nanotubes are closely relative to the diameter of the SiC nanotubes. The confinement effect of other SiC nanotubes may play an important effect retarding the growth of SiC nanotubes to form the hollow SiC nanospheres. Defect inducing growth is proposed to explain the formation of bamboo-shaped SiC nanotubes.

  14. Relevance of octanol-water distribution measurements to the potential ecological uptake of multi-walled carbon nanotubes.

    PubMed

    Petersen, Elijah J; Huang, Qingguo; Weber, Walter J

    2010-05-01

    Many potential applications of carbon nanotubes (CNTs) require various physicochemical modifications prior to use, suggesting that nanotubes having varied properties may pose risks in ecosystems. A means for estimating bioaccumulation potentials of variously modified CNTs for incorporation in predictive fate models would be highly valuable. An approach commonly used for sparingly soluble organic contaminants, and previously suggested for use as well with carbonaceous nanomaterials, involves measurement of their octanol-water partitioning coefficient (KOW) values. To test the applicability of this approach, a methodology was developed to measure apparent octanol-water distribution behaviors for purified multi-walled carbon nanotubes and those acid treated. Substantial differences in apparent distribution coefficients between the two types of CNTs were observed, but these differences did not influence accumulation by either earthworms (Eisenia foetida) or oligochaetes (Lumbriculus variegatus), both of which showed minimal nanotube uptake for both types of nanotubes. The results suggest that traditional distribution behavior-based KOW approaches are likely not appropriate for predicting CNT bioaccumulation. PMID:20821546

  15. Carbon nanotube growth density control

    NASA Technical Reports Server (NTRS)

    Delzeit, Lance D. (Inventor); Schipper, John F. (Inventor)

    2010-01-01

    Method and system for combined coarse scale control and fine scale control of growth density of a carbon nanotube (CNT) array on a substrate, using a selected electrical field adjacent to a substrate surface for coarse scale density control (by one or more orders of magnitude) and a selected CNT growth temperature range for fine scale density control (by multiplicative factors of less than an order of magnitude) of CNT growth density. Two spaced apart regions on a substrate may have different CNT growth densities and/or may use different feed gases for CNT growth.

  16. Endohedral Impurities in Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Clougherty, Dennis

    2003-03-01

    A generalization of the Anderson model that includes pseudo-Jahn-Teller impurity coupling is proposed to describe distortions of an endohedral impurity in a carbon nanotube. Treating the distortion within mean-field theory, spontaneous axial symmetry breaking is found when the vibronic coupling strength g exceeds a critical value g_c. The effective potential in the symmetry-broken state is found to have O(2) symmetry, in agreement with numerical calculations. The consequences of such a distortion on electronic transport will be discussed.

  17. A tunable carbon nanotube polarizer.

    PubMed

    Kang, Byeong Gyun; Lim, Young Jin; Jeong, Kwang-Un; Lee, Kyu; Lee, Young Hee; Lee, Seung Hee

    2010-10-01

    The electro-optic response of a carbon nanotube (CNT) cluster has been investigated. The cluster absorbs incident light before stretching. In the presence of an electric field, the cluster starts stretching along the field direction and contracts back to its original stage when the applied voltage is removed. The stretched cluster absorbs and transmits incident light with its electric vector propagating parallel and perpendicular to the long axis of the stretched cluster, respectively. Utilizing this selective light absorption property of a CNT cluster, a tunable polarizer or non-emissive light modulator can be realized. PMID:20829567

  18. Coated carbon nanotube array electrodes

    DOEpatents

    Ren, Zhifeng; Wen, Jian; Chen, Jinghua; Huang, Zhongping; Wang, Dezhi

    2008-10-28

    The present invention provides conductive carbon nanotube (CNT) electrode materials comprising aligned CNT substrates coated with an electrically conducting polymer, and the fabrication of electrodes for use in high performance electrical energy storage devices. In particular, the present invention provides conductive CNTs electrode material whose electrical properties render them especially suitable for use in high efficiency rechargeable batteries. The present invention also provides methods for obtaining surface modified conductive CNT electrode materials comprising an array of individual linear, aligned CNTs having a uniform surface coating of an electrically conductive polymer such as polypyrrole, and their use in electrical energy storage devices.

  19. Coated carbon nanotube array electrodes

    DOEpatents

    Ren, Zhifeng; Wen, Jian; Chen, Jinghua; Huang, Zhongping; Wang, Dezhi

    2006-12-12

    The present invention provides conductive carbon nanotube (CNT) electrode materials comprising aligned CNT substrates coated with an electrically conducting polymer, and the fabrication of electrodes for use in high performance electrical energy storage devices. In particular, the present invention provides conductive CNTs electrode material whose electrical properties render them especially suitable for use in high efficiency rechargeable batteries. The present invention also provides methods for obtaining surface modified conductive CNT electrode materials comprising an array of individual linear, aligned CNTs having a uniform surface coating of an electrically conductive polymer such as polypyrrole, and their use in electrical energy storage devices.

  20. Charge-tunable insertion process of carbon nanotubes into DNA nanotubes.

    PubMed

    Liang, Lijun; Zhang, Zhisen; Kong, Zhe; Liu, Yong; Shen, Jia-Wei; Li, Debing; Wang, Qi

    2016-05-01

    Control over interactions with biomolecules holds the key of the applications of carbon nanotubes (CNTs) in biotechnology. Here we report a molecule dynamics study on the encapsulation process of different charged CNTs into DNA nanotubes. Our results demonstrated that insertion process of CNTs into DNA nanotubes are charge-tunable. The positive charged CNTs could spontaneously encapsulate and confined in the hollow of DNA nanotubes under the combination of electrostatic and vdW interaction in our ns scale simulation. The conformation of DNA nanotubes is very stable even after the insertion of CNTs. For pristine CNTs, it could not entirely encapsulated by DNA nanotubes in simulation scale in this study. The encapsulation time of pristine CNTs into DNA nanotubes was estimated about 21.9s based on the potential of mean force along the reaction coordination of encapsulation process of CNTs into DNA nanotubes. In addition, the encapsulation process was also affected by the diameter of CNTs. These findings highlight the charge-tunable self-assembly process of nanomaterials and biomolecules. Our study suggests that the encapsulated CNTs-DNA nanotubes could be used as building blocks for constructing organic-inorganic hybrid materials and has the potential applications in the field of biosensor, drug delivery system and biomaterials etc. PMID:27017425

  1. Fabrication of Carbon Nanotube Field Effect Transistors Using Plasma-Enhanced Chemical Vapor Deposition Grown Nanotubes

    NASA Astrophysics Data System (ADS)

    Ohnaka, Hirofumi; Kojima, Yoshihiro; Kishimoto, Shigeru; Ohno, Yutaka; Mizutani, Takashi

    2006-06-01

    Single-walled carbon nanotubes are grown using grid-inserted plasma-enhanced chemical vapor deposition (PECVD). The field effect transistor operation was confirmed using the PECVD grown carbon nanotubes (CNTs). The preferential growth of the semiconducting nanotubes was confirmed in the grid-inserted PECVD by measuring current-voltage (I-V) characteristics of the devices. Based on the measurement of the electrical breakdown of the metallic CNTs, the probability of growing the semiconducting nanotubes has been estimated to be more than 90%.

  2. Directional dark matter searches with carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Capparelli, L. M.; Cavoto, G.; Mazzilli, D.; Polosa, A. D.

    2015-09-01

    A new solution to the problem of dark matter directional detection might come from the use of large arrays of aligned carbon nanotubes. We calculate the expected rate of carbon ions channeled in single-wall nanotubes once extracted by the scattering with a massive dark matter particle. Depending on its initial kinematic conditions, the ejected carbon ion may be channeled in the nanotube array or stop in the bulk. The orientation of the array with respect to the direction of motion of the Sun has an appreciable effect on the channeling probability. This provides the required anisotropic response for a directional detector.

  3. Electromagnetic SERS effect in carbon nanotube systems

    NASA Astrophysics Data System (ADS)

    Bondarev, I. V.; Gulyuk, A. V.

    2015-11-01

    Quantum electrodynamics theory of the resonance Raman scattering is developed for an atom in a close proximity to a carbon nanotube. The theory describes both weak and strong atomic coupling to nanotube plasmon near fields, and predicts a dramatic enhancement of the Raman intensity in the strong coupling regime. This resonance scattering is a manifestation of the surface enhanced Raman scattering effect, and can be used in designing efficient nanotube based optical sensing substrates for single atom detection, precision spontaneous emission control, and manipulation.

  4. Characterization of Carbon Nanotube Reinforced Nickel

    NASA Technical Reports Server (NTRS)

    Gill, Hansel; Hudson, Steve; Bhat, Biliyar; Munafo, Paul M. (Technical Monitor)

    2002-01-01

    Carbon nanotubes are cylindrical molecules composed of carbon atoms in a regular hexagonal arrangement. If nanotubes can be uniformly dispersed in a supporting matrix to form structural materials, the resulting structures could be significantly lighter and stronger than current aerospace materials. Work is currently being done to develop an electrolyte-based self-assembly process that produces a Carbon Nanotube/Nickel composite material with high specific strength. This process is expected to produce a lightweight metal matrix composite material, which maintains it's thermal and electrical conductivities, and is potentially suitable for applications such as advanced structures, space based optics, and cryogenic tanks.

  5. Methods for producing reinforced carbon nanotubes

    DOEpatents

    Ren, Zhifen; Wen, Jian Guo; Lao, Jing Y.; Li, Wenzhi

    2008-10-28

    Methods for producing reinforced carbon nanotubes having a plurality of microparticulate carbide or oxide materials formed substantially on the surface of such reinforced carbon nanotubes composite materials are disclosed. In particular, the present invention provides reinforced carbon nanotubes (CNTs) having a plurality of boron carbide nanolumps formed substantially on a surface of the reinforced CNTs that provide a reinforcing effect on CNTs, enabling their use as effective reinforcing fillers for matrix materials to give high-strength composites. The present invention also provides methods for producing such carbide reinforced CNTs.

  6. Carbon nanotube fiber spun from wetted ribbon

    DOEpatents

    Zhu, Yuntian T; Arendt, Paul; Zhang, Xiefei; Li, Qingwen; Fu, Lei; Zheng, Lianxi

    2014-04-29

    A fiber of carbon nanotubes was prepared by a wet-spinning method involving drawing carbon nanotubes away from a substantially aligned, supported array of carbon nanotubes to form a ribbon, wetting the ribbon with a liquid, and spinning a fiber from the wetted ribbon. The liquid can be a polymer solution and after forming the fiber, the polymer can be cured. The resulting fiber has a higher tensile strength and higher conductivity compared to dry-spun fibers and to wet-spun fibers prepared by other methods.

  7. Unzipped multiwalled carbon nanotube oxide/multiwalled carbon nanotube hybrids for polymer reinforcement.

    PubMed

    Fan, Jinchen; Shi, Zixing; Tian, Ming; Wang, Jialiang; Yin, Jie

    2012-11-01

    Multiwalled carbon nanotubes (MWNTs) have been widely used as nanofillers for polymer reinforcement. However, it has been restricted by the limited available interface area of MWNTs in the polymer matrices. Oxidation unzipping of MWNTs is an effective way to solve this problem. The unzipped multiwalled carbon nanotube oxides (UMCNOs) exhibit excellent enhancement effect with low weight fractions, but agglomeration of UMCNOs at a relatively higher loading still hampered the mechanical reinforcement of polymer composites. In this paper, we interestingly found that the dispersion of UMCNOs in polymer matrices can be significantly improved with the combination of pristine MWNTs. The hybrids of MWNTs and UMCNOs (U/Ms) can be easily obtained by adding the pristine MWNTs into the UMCNOs aqueous dispersion, followed by sonication. With a π-stacking interaction, the UMCNOs were attached onto the outwalls of MWNTs. The morphologies and structure of the U/Ms were characterized by several measurements. The mechanical testing of the resultant poly(vinyl alcohol) (PVA)-based composites demonstrated that the U/Ms can be used as ideal reinforcing fillers. Compared to PVA, the yield strength and Young's modulus of U/M-PVA composites with a loading of 0.7 wt % of the U/Ms approached ∼145.8 MPa and 6.9 GPa, respectively, which are increases of ∼107.4% and ∼122.5%, respectively. The results of tensile tests demonstrated that the reinforcement effect of U/Ms is superior to the individual UMCNOs and MWNTs, because of the synergistic interaction of UMCNOs and MWNTs. PMID:23121120

  8. Splitting and joining in carbon nanotube/nanoribbon/nanotetrahedron growth.

    PubMed

    Hasegawa, Takayuki; Kohno, Hideo

    2015-02-01

    We report a novel phenomenon for carbon nanotube growth that results in a new carbon nanotube morphology. A carbon nanotube grown via metal nanoparticle-catalyzed chemical vapor deposition splits into two flattened nanotubes during growth and the two flattened nanotubes merge to form a ring of carbon nanotube/nanoribbon. This novel process is revealed by transmission electron microscopy observations of the carbon nanostructures. We propose that the splitting-and-joining process involves only one metal catalyst nanoparticle and a self-folding mechanism that we have named the origami mechanism to explain the process and the formation of nanoribbons and nanotetrahedra. PMID:25559588

  9. Processing and Characterization of Carbon Nanotube Composites

    NASA Technical Reports Server (NTRS)

    Can, Roberto J.; Grimsley, Brian W.; Czabaj, Michael W.; Siochi, Emilie J.; Hull, Brandon

    2014-01-01

    Recent advances in the synthesis of large-scale quantities of carbon nanotubes (CNT) have provided the opportunity to study the mechanical properties of polymer matrix composites using these novel materials as reinforcement. Nanocomp Technologies, Inc. currently supplies large sheets with dimensions up to 122 cm x 244 cm containing both single-wall and few-wall CNTs. The tubes are approximately 1 mm in length with diameters ranging from 8 to 12 nm. In the present study being conducted at NASA Langley Research Center (LaRC), single and multiple layers of CNT sheets were infused or coated with various polymer solutions that included commercial toughened-epoxies and bismaleimides, as well as a LaRC developed polyimide. The resulting CNT composites were tested in tension using a modified version of ASTM D882-12 to determine their strength and modulus values. The effects of solvent treatment and mechanical elongation/alignment of the CNT sheets on the tensile performance of the composite were determined. Thin composites (around 50 wt% CNT) fabricated from acetone condensed and elongated CNT sheets with either a BMI or polyimide resin solution exhibited specific tensile moduli approaching that of toughened epoxy/ IM7 carbon fiber unidirectional composites.

  10. Biomolecules Functionalized Carbon Nanotubes and Their Applications

    NASA Astrophysics Data System (ADS)

    Cui, Daxiang

    In recent years, functionalization of carbon nanotubes (CNTs) with biomolecules such as nucleotide acids, proteins, and artificial polymers have emerged as a new exciting field. Theoretical and experimental studies of structure and function of bio-inspired CNT composites have made great advances. The importance of nucleic acids, proteins, and synthesized polymers to the fundamental developments in CNT-based bio-nano-composites or devices has been recognized. In particular, biomechanics, biochemistry, thermodynamics, electronic, optical and magnetic properties, and biocompatibility and toxicology of the bio-inspired CNT composites have become a new interdisciplinary frontier in life science and nanomaterial science. Bio-inspired CNT composites have been actively exploited potentials in applications such as gene/drug delivery system, tissue engineering scaffolds, hydrogen storage, molecular imaging, biocatalyst systems, biosensors, and antifouling films. Here we review the main advances in this field over the past few years, explore their application prospects, and discuss the issues, approaches, and challenges, with the aim of improving and developing CNT-based bio-nanotechnology.

  11. Microcavity-Integrated Carbon Nanotube Photodetectors.

    PubMed

    Liang, Shuang; Ma, Ze; Wu, Gongtao; Wei, Nan; Huang, Le; Huang, Huixin; Liu, Huaping; Wang, Sheng; Peng, Lian-Mao

    2016-07-26

    Carbon nanotubes (CNTs) are considered to be highly promising nanomaterials for multiwavelength, room-temperature infrared detection applications. Here, we demonstrate a single-tube diode photodetector monolithically integrated with a Fabry-Pérot microcavity. A ∼6-fold enhanced optical absorption can be achieved, because of the confined effect of the designed optical mode. Furthermore, taking advantage of Van-Hove-singularity band structures in CNTs, we open the possibility of developing chirality-specific (n,m) CNT-film-based signal detectors. Utilizing a concept of the "resonance and off-resonance" cavity, we achieved cavity-integrated chirality-sorted CNT-film detectors working at zero bias and resonance-allowed mode, for specific target signal detection. The detectors exhibited a higher suppression ratio until a power density of 0.07 W cm(-2) and photocurrent of 5 pA, and the spectral full width at half-maximum is ∼33 nm at a signal wavelength of 1200 nm. Further, with multiple array detectors aiming at different target signals integrated on a chip, a multiwavelength signal detector system can be expected to have applications in the fields of monitoring, biosensing, color imaging, signal capture, and on-chip or space information transfers. The approach can also bring other nanomaterials into on-chip or information optoelectronics, regardless of the available doping polarity. PMID:27379375

  12. Freely drawn single lipid nanotube patterns.

    PubMed

    Sugihara, Kaori; Rustom, Amin; Spatz, Joachim P

    2015-03-14

    LNTs are unique 3D structures made only of safe and abundant biomaterials by self-assembly. The current bottleneck for developing applications using LNTs is the lack of an easy technique to pattern them on substrates. We report a method to free-draw single lipid nanotube (LNT) patterns in any shape on surfaces with 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) that takes an inverted hexagonal (HII) phase. We used pre-self-assembled LNTs or HII lipid blocks as a lipid reservoir from which new LNTs were pulled by applying a point load with a micromanipulator. The extreme simplicity of our technique originates from the fundamental nature of DOPE lipids that prefer a HII phase, while all the conventional approaches use PC lipids that form a lamellar phase. By adjusting the surface properties with polyelectrolyte multilayers, the created single LNT objects are able to remain adhered to the surface for over a week. Importantly, it could be shown that two vesicles loaded with caged fluorescent molecules were able to fuse well with a LNT, enabling diffusive transport of uncaged fluorescent molecules from one vesicle to the other. PMID:25626419

  13. Engineering radial deformations in single-walled carbon and boron nitride nanotubes using ultrathin nanomembranes.

    PubMed

    Zheng, Meng; Zou, Lian-Feng; Wang, Howard; Park, Cheol; Ke, Changhong

    2012-02-28

    Radial deformations of carbon and boron-nitride nanotubes are of great importance to their respective electronic properties and applications. In this paper, we present a simple and practical approach of engineering radial deformations in single-walled carbon and boron-nitride nanotubes (SWCNTs and SW-BNNTs) through covering individual nanotubes lying on flat substrates with subnanometer-thick monolayer graphene oxide (GO) nanomembranes. The GO membrane conforms to and transversely compresses the underlying nanotube as a result of its adhesion binding interaction with the substrate. Our atomic force microscopy (AFM) imaging measurements reveal that the engineered net radial deformations of both types of tubes increase with the tube diameter and are more for SW-BNNTs compared with SWCNTs of the same tube diameter. Our results capture the net cross-section height reductions of up to 44.1% for SW-BNNTs and up to 29.7% for SWCNTs. Our work clearly demonstrates the effectiveness of our proposed approach for engineering and controlling the radial deformation in one-dimensional tubular nanostructures and opens a promising route for mechanical tuning of their electronic properties for novel nanoelectronics applications. PMID:22280493

  14. Flightweight Carbon Nanotube Magnet Technology

    NASA Technical Reports Server (NTRS)

    Chapman, J. N.; Schmidt, H. J.; Ruoff, R. S.; Chandrasekhar, V.; Dikin, D. A.; Litchford, R. J.

    2003-01-01

    Virtually all plasma-based systems for advanced airborne/spaceborne propulsion and power depend upon the future availability of flightweight magnet technology. Unfortunately, current technology for resistive and superconducting magnets yields system weights that tend to counteract the performance advantages normally associated with advanced plasma-based concepts. The ongoing nanotechnology revolution and the continuing development of carbon nanotubes (CNT), however, may ultimately relieve this limitation in the near future. Projections based on recent research indicate that CNTs may achieve current densities at least three orders of magnitude larger than known superconductors and mechanical strength two orders of magnitude larger than steel. In fact, some published work suggests that CNTs are superconductors. Such attributes imply a dramatic increase in magnet performance-to-weight ratio and offer real hope for the construction of true flightweight magnets. This Technical Publication reviews the technology status of CNTs with respect to potential magnet applications and discusses potential techniques for using CNT wires and ropes as a winding material and as an integral component of the containment structure. The technology shortfalls are identified and a research and technology strategy is described that addresses the following major issues: (1) Investigation and verification of mechanical and electrical properties, (2) development of tools for manipulation and fabrication on the nanoscale, (3) continuum/molecular dynamics analysis of nanotube behavior when exposed to practical bending and twisting loads, and (4) exploration of innovative magnet fabrication techniques that exploit the natural attributes of CNTs.

  15. Vanadium pentoxide nanotubes by eelectrospinning

    NASA Astrophysics Data System (ADS)

    Lala, Neeta L.; Jose, R.; Yusoff, M. M.

    2012-11-01

    Nanofibers of vanadium pentoxide (V2O5) were synthesized by electrospinning a polymeric solution containing vanadium ion and with subsequent sintering. Conventionally, electrospun TNFs were produced by using a co-axial spinneret; however, TNFs in the present study were obtained by manipulating the concentration ratio of the precursor solution, distance, humidity and flow rate during electrospinning using a single spinneret and sintering with time and temperature change. On the basis of this hypothesis, nanofibers could be altered from elongated 1-D nanofibers to nanowires, nanotubes, spheres and flakes respectively. The surface morphology, structure, roughness and the crystal structure were analyzed using Field Emission Scanning Electron Microscopy (FE-SEM), Transmission Electron Microscopy (TEM), and X-ray diffraction (XRD). The current work has demonstrated a case study for energy storage where V2O5 nanotubes when tested shows the capacitance of 190 Fg-1 in 2M KCl electrolyte indicating an example for the energy storage which may be applicable for other electrochemical devices such as Li-ion batteries, fuel cells, hydrogen storage etc.

  16. Hydrogen Storage in Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Gilbert, Joseph; Gilbert, Matthew; Naab, Fabian; Savage, Lauren; Holland, Wayne; Duggan, Jerome; McDaniel, Floyd

    2004-10-01

    Hydrogen as a fuel source is an attractive, relatively clean alternative to fossil fuels. However, a major limitation in its use for the application of automobiles has been the requirement for an efficient hydrogen storage medium. Current hydrogen storage systems are: physical storage in high pressure tanks, metal hydride, and gas-on-solid absorption. However, these methods do not fulfill the Department of Energy's targeted requirements for a usable hydrogen storage capacity of 6.5 wt.%, operation near ambient temperature and pressure, quick extraction and refueling, reliability and reusability.Reports showing high capacity hydrogen storage in single-walled carbon nanotubes originally prompted great excitement in the field, but further research has shown conflicting results. Results for carbon nanostructures have ranged from less than 1 wt.% to 70 wt.%. The wide range of adsorption found in previous experiments results from the difficulty in measuring hydrogen in objects just nanometers in size. Most previous experiments relied on weight analysis and residual gas analysis to determine the amount of hydrogen being adsorbed by the CNTs. These differing results encouraged us to perform our own analysis on single-walled (SWNTs), double-walled (DWNTs), and multi-walled carbon nanotubes (MWNTs), as well as carbon fiber. We chose to utilize direct measurement of hydrogen in the materials using elastic recoil detection analysis (ERDA). This work was supported by the National Science Foundation's Research Experience for Undergraduates and the University of North Texas.

  17. Multiwall carbon nanotube microcavity arrays

    NASA Astrophysics Data System (ADS)

    Ahmed, Rajib; Rifat, Ahmmed A.; Yetisen, Ali K.; Dai, Qing; Yun, Seok Hyun; Butt, Haider

    2016-03-01

    Periodic highly dense multi-wall carbon nanotube (MWCNT) arrays can act as photonic materials exhibiting band gaps in the visible regime and beyond terahertz range. MWCNT arrays in square arrangement for nanoscale lattice constants can be configured as a microcavity with predictable resonance frequencies. Here, computational analyses of compact square microcavities (≈0.8 × 0.8 μm2) in MWCNT arrays were demonstrated to obtain enhanced quality factors (≈170-180) and narrow-band resonance peaks. Cavity resonances were rationally designed and optimized (nanotube geometry and cavity size) with finite element method. Series (1 × 2 and 1 × 3) and parallel (2 × 1 and 3 × 1) combinations of microcavities were modeled and resonance modes were analyzed. Higher order MWCNT microcavities showed enhanced resonance modes, which were red shifted with increasing Q-factors. Parallel microcavity geometries were also optimized to obtain narrow-band tunable filtering in low-loss communication windows (810, 1336, and 1558 nm). Compact series and parallel MWCNT microcavity arrays may have applications in optical filters and miniaturized optical communication devices.

  18. Carbon nanotubes on carbon fibers: Synthesis, structures and properties

    NASA Astrophysics Data System (ADS)

    Zhang, Qiuhong

    The interface between carbon fibers (CFs) and the resin matrix in traditional high performance composites is characterized by a large discontinuity in mechanical, electrical, and thermal properties which can cause inefficient energy transfer. Due to the exceptional properties of carbon nanotubes (CNTs), their growth at the surface of carbon fibers is a promising approach to controlling interfacial interactions and achieving the enhanced bulk properties. However, the reactive conditions used to grow carbon nanotubes also have the potential to introduce defects that can degrade the mechanical properties of the carbon fiber (CF) substrate. In this study, using thermal chemical vapor deposition (CVD) method, high density multi-wall carbon nanotubes have been successfully synthesized directly on PAN-based CF surface without significantly compromising tensile properties. The influence of CVD growth conditions on the single CF tensile properties and carbon nanotube (CNT) morphology was investigated. The experimental results revealed that under high temperature growth conditions, the tensile strength of CF was greatly decreased at the beginning of CNT growth process with the largest decrease observed for sized CFs. However, the tensile strength of unsized CFs with CNT was approximately the same as the initial CF at lower growth temperature. The interfacial shear strength of CNT coated CF (CNT/CF) in epoxy was studied by means of the single-fiber fragmentation test. Results of the test indicate an improvement in interfacial shear strength with the addition of a CNT coating. This improvement can most likely be attributed to an increase in the interphase yield strength as well as an improvement in interfacial adhesion due to the presence of the nanotubes. CNT/CF also offers promise as stress and strain sensors in CF reinforced composite materials. This study investigates fundamental mechanical and electrical properties of CNT/CF using nanoindentation method by designed

  19. Design, fabrication and properties of novel architectures made from carbon nanotubes and nano-porous materials

    NASA Astrophysics Data System (ADS)

    Kaur, Sumanjeet

    Nanomaterials like carbon nanotubes (CNT) have numerous potential applications due to their unique electrical, thermal and mechanical properties. Building macroscopic architectures using these nanocomponents requires new approaches for organization or assembly of these components. This can be achieved by using various techniques like capillary-induced compaction, template-assisted growth and other synthesis techniques. The vertically aligned multiwalled carbon nanotube arrays were grown using chemical vapor deposition (CVD). Evaporation of liquid from such vertically aligned nanotube arrays induces the assembly of nanotubes into cellular patterns. The role of substrate and orientation of the carbon nanotube array was investigated and analyzed to gain more control over the pattern formation that could help in designing new structures. Electrical measurements on the CNT patterns before and after capillary-induced compaction revealed that compaction results in four-fold increase in electrical conductivity, making them a potential candidate for vertical interconnects. A new method to fabricate a syringe with nanopores by using anodization technique was demonstrated. Experimental parameters were investigated to control the dimension and morphology of the nanopores in the syringe. Capillary force was used to infiltrate and replicate the complete 3D architecture into polymers. The usefulness of syringe as a biological sampler (DNA-RNA separation) was demonstrated. Layered structure of exfoliated mica was used as a substrate for growth of CNTs. This resulted in novel layered hybrid architecture of mica and carbon nanotube arrays. Mechanical properties of such architectures were investigated. Such architectures could be very useful as foams. These simple techniques can be used to assemble nanoscale components into well-defined macroscopic architectures and thus broaden the range of applications where their unique properties can be put into use.

  20. Sub percolation threshold carbon nanotube based polyvinylidene fluoride polymer-polymer composites

    NASA Astrophysics Data System (ADS)

    Jacob, Cedric Antony

    The study of piezoelectric materials has traditionally focused largely on homogeneous crystalline or semi-crystalline materials. This research focuses on the concept of piezoelectric composites using selective microstructural reinforcement in the piezoelectric material to improve the piezoelectric properties. This is done using a polyvinylidene fluoride (PVDF) and carbon nanotube composite as the model system. A multi-tiered engineering approach is taken to understand the material (experimental and computational analyses) and design a composite system which provides an effective platform for future research in piezoelectric improvement. A finite element analysis is used to evaluate the ability of carbon nanotubes to generate a heterogeneous electric field where local improvements in electric field produce an increase in the effective piezoelectric strength. The study finds that weight percent and aspect ratio of the carbon nanotubes are of key importance while formations of percolating networks are detrimental to performance. This motivates investigation into electrospinning into a method of producing sub percolation threshold composites with large carbon nanotube content. However, the electrospun fabrics have too low of a dielectric strength to sustain high strength electric fields. This is studied within the context of high voltage physics and a solution inspired by traditional composites manufacturing is proposed wherein the electrospun fiber mat is used as the fiber reinforcing component of a polymer-polymer composite. This composite is thoroughly analyzed to show that it allows for a high dielectric strength combined with high carbon nanotube content. It is also shown that the PVDF contains the proper crystal structure to allow for piezoelectric properties. Furthermore, the addition of carbon nanotubes greatly improves the strength and stiffness of the composite, as well as affecting the internal electric field response to an applied voltage. These qualities