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Sample records for 2-aminophenoxazin-3-one-functionalized multiwalled carbon

  1. Electrical properties of multiwalled carbon nanotube film

    SciTech Connect

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

    2007-07-15

    The multiwalled carbon nanotube films examined in this study are produced by two methods: current annealing of carbon paper and dc magnetron sputtering. The conductivity and the temperature dependence of resistance of the samples are measured. The thermal conductivity of the film-substrate system is evaluated.

  2. Ultralight multiwalled carbon nanotube aerogel.

    PubMed

    Zou, Jianhua; Liu, Jianhua; Karakoti, Ajay Singh; Kumar, Amit; Joung, Daeha; Li, Qiang; Khondaker, Saiful I; Seal, Sudipta; Zhai, Lei

    2010-12-28

    Ultralight multiwalled carbon nanotube (MWCNT) aerogel is fabricated from a wet gel of well-dispersed pristine MWCNTs. On the basis of a theoretical prediction that increasing interaction potential between CNTs lowers their critical concentration to form an infinite percolation network, poly(3-(trimethoxysilyl) propyl methacrylate) (PTMSPMA) is used to disperse and functionalize MWCNTs where the subsequent hydrolysis and condensation of PTMSPMA introduces strong and permanent chemical bonding between MWCNTs. The interaction is both experimentally and theoretically proven to facilitate the formation of a MWCNT percolation network, which leads to the gelation of MWCNT dispersion at ultralow MWCNT concentration. After removing the liquid component from the MWCNT wet gel, the lightest ever free-standing MWCNT aerogel monolith with a density of 4 mg/cm(3) is obtained. The MWCNT aerogel has an ordered macroporous honeycomb structure with straight and parallel voids in 50-150 μm separated by less than 100 nm thick walls. The entangled MWCNTs generate mesoporous structures on the honeycomb walls, creating aerogels with a surface area of 580 m(2)/g which is much higher than that of pristine MWCNTs (241 m(2)/g). Despite the ultralow density, the MWCNT aerogels have an excellent compression recoverable property as demonstrated by the compression test. The aerogels have an electrical conductivity of 3.2 × 10(-2) S·cm(-1) that can be further increased to 0.67 S·cm(-1) by a high-current pulse method without degrading their structures. The excellent compression recoverable property, hierarchically porous structure with large surface area, and high conductivity grant the MWCNT aerogels exceptional pressure and chemical vapor sensing capabilities. PMID:21090673

  3. 77 FR 39236 - Nanomaterial Case Study: A Comparison of Multiwalled Carbon Nanotubes and Decabromodiphenyl Ether...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-02

    ... AGENCY Nanomaterial Case Study: A Comparison of Multiwalled Carbon Nanotubes and Decabromodiphenyl Ether... Study: A Comparison of Multiwalled Carbon Nanotubes and Decabromodiphenyl Ether Flame-Retardant Coatings... ``Nanomaterial Case Study: A Comparison of Multiwalled Carbon Nanotubes and Decabromodiphenyl Ether...

  4. Radial elasticity of multiwalled carbon nanotubes.

    PubMed

    Palaci, I; Fedrigo, S; Brune, H; Klinke, C; Chen, M; Riedo, E

    2005-05-01

    We report an experimental and a theoretical study of the radial elasticity of multiwalled carbon nanotubes as a function of external radius. We use atomic force microscopy and apply small indentation amplitudes in order to stay in the linear elasticity regime. The number of layers for a given tube radius is inferred from transmission electron microscopy, revealing constant ratios of external to internal radii. This enables a comparison with molecular dynamics results, which also shed some light onto the applicability of Hertz theory in this context. Using this theory, we find a radial Young modulus strongly decreasing with increasing radius and reaching an asymptotic value of 30+/-10 GPa.

  5. Bio-functionalization of multi-walled carbon nanotubes.

    PubMed

    Majumder, Anindya; Khazaee, Maryam; Opitz, Jörg; Beyer, Eckhard; Baraban, Larysa; Cuniberti, Gianaurelio

    2013-10-28

    Here we present a hybrid approach to functionalize multi-walled carbon nanotubes in aqueous solution, exploring a non-covalent binding strategy. We focus on formation of hybrid complexes consisting of carbon nanotubes decorated by single stranded DNA, non-covalently attached using surfactants as intermediate layers. Unlike single walled carbon nanotubes, revealing easy side wall wrapping of DNA, we observe that wrapping of nucleic acids around multi-walled carbon nanotubes is diameter dependent. PMID:24013382

  6. Multiwalled Carbon nanotube - Strength to polymer composite

    NASA Astrophysics Data System (ADS)

    Pravin, Jagdale; Khan, Aamer. A.; Massimo, Rovere; Carlo, Rosso; Alberto, Tagliaferro

    2016-02-01

    Carbon nanotubes (CNTs), a rather fascinating material, are among the pillars of nanotechnology. CNTs exhibit unique electrical, mechanical, adsorption, and thermal properties with high aspect ratio, exceptional stiffness, excellent strength, and low density, which can be exploited in the manufacturing of revolutionary smart nano composite materials. The demand for lighter and stronger polymer composite material in various applications is increasing every day. Among all the possibilities to research and exploit the exceptional properties of CNTs in polymer composites we focused on the reinforcement of epoxy resin with different types of multiwalled carbon nano tubes (MWCNTs). We studied mechanical properties such as stress, strain, ultimate tensile strength, yield point, modulus and fracture toughness, and Young's modulus by plotting and calculating by means of the off-set method. The mechanical strength of epoxy composite is increased intensely with 1 and 3 wt.% of filler.

  7. Multiwall carbon nanotubes reinforced epoxy nanocomposites

    NASA Astrophysics Data System (ADS)

    Chen, Wei

    The emergence of carbon nanotubes (CNTs) has led to myriad possibilities for structural polymer composites with superior specific modulus, strength, and toughness. While the research activities in carbon nanotube reinforced polymer composites (NRPs) have made enormous progress towards fabricating next-generation advanced structural materials with added thermal, optical, and electrical advantages, questions concerning the filler dispersion, interface, and CNT alignment in these composites remain partially addressed. In this dissertation, the key technical challenges related to the synthesis, processing, and reinforcing mechanics governing the effective mechanical properties of NRPs were introduced and reviewed in the first two chapters. Subsequently, issues on the dispersion, interface control, hierarchical structure, and multi-functionality of NRPs were addressed based on functionalized multi-walled carbon nanotube reinforced DGEBA epoxy systems (NREs). In chapter 3, NREs with enhanced flexural properties were discussed in the context of improved dispersion and in-situ formation of covalent bonds at the interface. In chapter 4, NREs with controlled interface and tailored thermomechanical properties were demonstrated through the judicious choice of surface functionality and resin chemistry. In chapter 5, processing-condition-induced CNT organization in hierarchical epoxy nanocomposites was analyzed. In Chapter 6, possibilities were explored for multi-functional NREs for underwater acoustic structural applications. Finally, the findings of this dissertation were concluded and future research was proposed for ordered carbon nanotube array reinforced nanocomposites in the last chapter. Four journal publications resulted from this work are listed in Appendix.

  8. Synthetic gecko foot-hairs from multiwalled carbon nanotubes.

    PubMed

    Yurdumakan, Betul; Raravikar, Nachiket R; Ajayan, Pulickel M; Dhinojwala, Ali

    2005-08-14

    We report a fabrication process for constructing polymer surfaces with multiwalled carbon nanotube hairs, with strong nanometer-level adhesion forces that are 200 times higher than those observed for gecko foot-hairs.

  9. Multiwalled Carbon Nanotube Deposition on Model Environmental Surfaces

    EPA Science Inventory

    Deposition of multiwalled carbon nanotubes (MWNTs) on model environmental surfaces was investigated using a quartz crystal microbalance with dissipation monitoring (QCM-D). Deposition behaviors of MWNTs on positively and negatively charged surfaces were in good agreement with Der...

  10. Torsional wave propagation in multiwalled carbon nanotubes using nonlocal elasticity

    NASA Astrophysics Data System (ADS)

    Arda, Mustafa; Aydogdu, Metin

    2016-03-01

    Torsional wave propagation in multiwalled carbon nanotubes is studied in the present work. Governing equation of motion of multiwalled carbon nanotube is obtained using Eringen's nonlocal elasticity theory. The effect of van der Waals interaction coefficient is considered between inner and outer nanotubes. Dispersion relations are obtained and discussed in detail. Effect of nonlocal parameter and van der Waals interaction to the torsional wave propagation behavior of multiwalled carbon nanotubes is investigated. It is obtained that torsional van der Waals interaction between adjacent tubes can change the rotational direction of multiwalled carbon nanotube as in-phase or anti-phase. The group and escape velocity of the waves converge to a limit value in the nonlocal elasticity approach.

  11. A thermodynamic model for growth mechanisms of multiwall carbon nanotubes.

    SciTech Connect

    Kaatz, Forrest H.; Overmyer, Donald L.; Siegal, Michael P.

    2006-02-01

    Multiwall carbon nanotubes are grown via thermal chemical vapor deposition between temperatures of 630 and 830 C using acetylene in nitrogen as the carbon source. This process is modeled using classical thermodynamics to explain the total carbon deposition as a function of time and temperature. An activation energy of 1.60 eV is inferred for nanotube growth after considering the carbon solubility term. Scanning electron microscopy shows growth with diameters increasing linearly with time. Transmission electron microscopy and Raman spectroscopy show multiwall nanotubes surrounded by a glassy-carbon sheath, which grows with increasing wall thickness as growth temperatures and times rise.

  12. Multi-Walled Carbon Nanotube Growth in Multi-Walled Carbon Nanotubes by Chemical Vapor Deposition.

    PubMed

    Hasegawa, Takayuki; Arenas, Daniel J; Kohno, Hideo

    2015-02-01

    We report chemical vapor deposition (CVD) growth of a multi-walled carbon nanotube (MWCNT) inside another MWCNTs from a cementite (Fe3C) catalyst nanoparticles. The CNTs have bi or tri-layered core(s)-sheath structure with various crystallinity. The sheath grows first at a lower temperature, and then the catalyst nanoparticle works again to grow the core(s) at a higher temperature in the tip or root growth mode. Transmission electron microscopy (TEM) observation provides a clear piece of evidence of reverse-inward growth. PMID:26353735

  13. A promising pathway to make multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Setlur, A. A.; Doherty, S. P.; Dai, J. Y.; Chang, R. P. H.

    2000-05-01

    Current theories for multiwalled nanotube growth (without metal catalysts) describe the growth of multiwalled nanotubes by the addition of carbon atoms, ions, or small molecules to an open ended nanotube nucleus. In this letter, we describe a method to make carbon nanotubes similar in quality to those found on the cathode deposit of the carbon arc by manipulating the heat treatment of various nongraphitizable carbon precursors. It is proposed that this method of making nanotubes via heat treatments is analogous to a graphitization process, where aromatic/graphitic fragments in disordered carbons assemble into three-dimensional graphitic structures. In addition, we have demonstrated that simple precursors, such as sucrose, can be used as starting materials. These experiments offer new opportunities to understand nanotube growth and could lead to scalable methods to make multiwalled nanotubes.

  14. A promising pathway to make multiwalled carbon nanotubes

    SciTech Connect

    Setlur, A. A.; Doherty, S. P.; Dai, J. Y.; Chang, R. P. H.

    2000-05-22

    Current theories for multiwalled nanotube growth (without metal catalysts) describe the growth of multiwalled nanotubes by the addition of carbon atoms, ions, or small molecules to an open ended nanotube nucleus. In this letter, we describe a method to make carbon nanotubes similar in quality to those found on the cathode deposit of the carbon arc by manipulating the heat treatment of various nongraphitizable carbon precursors. It is proposed that this method of making nanotubes via heat treatments is analogous to a graphitization process, where aromatic/graphitic fragments in disordered carbons assemble into three-dimensional graphitic structures. In addition, we have demonstrated that simple precursors, such as sucrose, can be used as starting materials. These experiments offer new opportunities to understand nanotube growth and could lead to scalable methods to make multiwalled nanotubes. (c) 2000 American Institute of Physics.

  15. Resistance-based biosensor of Multi-Walled Carbon Nanotubes.

    PubMed

    Kolosovas-Machuca, E S; Vera-Reveles, G; Rodríguez-Aranda, M C; Ortiz-Dosal, L C; Segura-Cardenas, Emmanuel; Gonzalez, Francisco J

    2015-01-01

    Multi-Walled Carbon Nanotubes (MWNTs) are a good choice for resistive biosensors due to their great resistance changes when immunoreactions take place, they are also low-cost, more biocompatible than single-walled carbon nanotubes, and resistive measurement equipment is usually not expensive and readily available. In this work a novel resistive biosensor based on the immobilization of an antigen through a silanization process over the surface of Multi-Walled Carbon Nanotubes (MWNTs) is reported. Results show that the biosensor increases its conductivity when adding the antigen and decreases when adding the antibody making them good candidates for disease diagnosis.

  16. Flattened Multiwalled Carbon Nanotube with Multi-Layered Structure.

    PubMed

    Kohno, Hideo; Hasegawa, Takayuki; Ichikawa, Satoshi

    2015-08-01

    Fabrication of novel nanostructures based on carbon nanotubes has been a focus of recent interest since they are expected to inherit excellent properties of carbon nanotube. To find new nanotube-based nanostructures, it is important to find a new growth mode or process. This paper reports the formation of a multiwalled carbon nanotube that has bi-layered structure and is partly flattened. Transmission electron microscopy observations suggest that the outer multiwalled layer was formed first from a Fe catalyst nanoparticle, and was partly flattened during the growth. Then the catalyst nanoparticle worked again to form the inner multiwalled tube moving inside the outer tube and became flattened at the same position of the outer tube. It is likely that the inner growth gave an expansion stress against the flattened outer tube; nevertheless, the flattened part of the outer tube remained. This observation evidences that the flattening of the nanotube occurred simultaneously during the growth and was stabilized by structural defect.

  17. Fractionation of multiwalled carbon nanotubes by cascade membrane microfiltration

    SciTech Connect

    Abatemarco, T.; Stickel, J.; Belfort, J.; Frank, B.P.; Ajayan, P.M.; Belfort, G.

    1999-05-06

    Multiwalled carbon nanotubes were purified and size-separated by a multistep microfiltration process through a sequence of track-etched polycarbonate membranes of various pore sizes in both dead-ended and cross-flow mode. For this cascade microfiltration, the electric arc derived raw multiwalled samples were suspended in an aqueous solution of sodium dodecyl sulfate in deionized water. By examining the deposits on the membrane surfaces and in the permeate suspensions with scanning electron microscopy and atomic force microscopy, the nanotube fractionation was confirmed and analyzed. These scanning techniques showed that the components of the crude sample, which included carbon nanotubes, polyhedral nanoparticles, and large aggregates, were separated from each other during the filtration. In addition, fractionation of the multiwalled carbon nanotubes according to length was possible.

  18. 40 CFR 721.10183 - Multi-walled carbon nanotubes (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Multi-walled carbon nanotubes (generic... Specific Chemical Substances § 721.10183 Multi-walled carbon nanotubes (generic). (a) Chemical substance... multi-walled carbon nanotubes (PMN P-08-199) is subject to reporting under this section for...

  19. 40 CFR 721.10279 - Multi-walled carbon nanotubes (generic) (P-10-246).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Multi-walled carbon nanotubes (generic... Specific Chemical Substances § 721.10279 Multi-walled carbon nanotubes (generic) (P-10-246). (a) Chemical... as multi-walled carbon nanotubes (PMN P-10-246) is subject to reporting under this section for...

  20. 40 CFR 721.10183 - Multi-walled carbon nanotubes (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Multi-walled carbon nanotubes (generic... Specific Chemical Substances § 721.10183 Multi-walled carbon nanotubes (generic). (a) Chemical substance... multi-walled carbon nanotubes (PMN P-08-199) is subject to reporting under this section for...

  1. 40 CFR 721.10275 - Multi-walled carbon nanotubes (generic) (P-09-0417).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Multi-walled carbon nanotubes (generic... Specific Chemical Substances § 721.10275 Multi-walled carbon nanotubes (generic) (P-09-0417). (a) Chemical... as multi-walled carbon nanotubes (PMN P-09-417) is subject to reporting under this section for...

  2. 40 CFR 721.10183 - Multi-walled carbon nanotubes (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Multi-walled carbon nanotubes (generic... Specific Chemical Substances § 721.10183 Multi-walled carbon nanotubes (generic). (a) Chemical substance... multi-walled carbon nanotubes (PMN P-08-199) is subject to reporting under this section for...

  3. 40 CFR 721.10183 - Multi-walled carbon nanotubes (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Multi-walled carbon nanotubes (generic... Specific Chemical Substances § 721.10183 Multi-walled carbon nanotubes (generic). (a) Chemical substance... multi-walled carbon nanotubes (PMN P-08-199) is subject to reporting under this section for...

  4. 40 CFR 721.10274 - Multi-walled carbon nanotubes (generic) (P-09-188).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Multi-walled carbon nanotubes (generic... Specific Chemical Substances § 721.10274 Multi-walled carbon nanotubes (generic) (P-09-188). (a) Chemical... as multi-walled carbon nanotubes (PMN P-09-188) is subject to reporting under this section for...

  5. 40 CFR 721.10155 - Multi-walled carbon nanotubes (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Multi-walled carbon nanotubes (generic... Specific Chemical Substances § 721.10155 Multi-walled carbon nanotubes (generic). (a) Chemical substance... multi-walled carbon nanotubes (PMN P-08-177) is subject to reporting under this section for...

  6. 40 CFR 721.10155 - Multi-walled carbon nanotubes (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Multi-walled carbon nanotubes (generic... Specific Chemical Substances § 721.10155 Multi-walled carbon nanotubes (generic). (a) Chemical substance... multi-walled carbon nanotubes (PMN P-08-177) is subject to reporting under this section for...

  7. 40 CFR 721.10276 - Multi-walled carbon nanotubes (generic) (P-10-39).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Multi-walled carbon nanotubes (generic... Specific Chemical Substances § 721.10276 Multi-walled carbon nanotubes (generic) (P-10-39). (a) Chemical... as multi-walled carbon nanotubes (PMN P-10-39) is subject to reporting under this section for...

  8. 40 CFR 721.10155 - Multi-walled carbon nanotubes (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Multi-walled carbon nanotubes (generic... Specific Chemical Substances § 721.10155 Multi-walled carbon nanotubes (generic). (a) Chemical substance... multi-walled carbon nanotubes (PMN P-08-177) is subject to reporting under this section for...

  9. Ag-catalysed cutting of multi-walled carbon nanotubes.

    PubMed

    La Torre, A; Rance, G A; Miners, S A; Herreros Lucas, C; Smith, E F; Fay, M W; Zoberbier, T; Giménez-López, M C; Kaiser, U; Brown, P D; Khlobystov, A N

    2016-04-29

    In this work, the cutting of carbon nanotubes is investigated using silver nanoparticles deposited on arc discharge multi-walled carbon nanotubes. The composite is subsequently heated in air to fabricate shortened multi-walled nanotubes. Complementary transmission electron microscopy and spectroscopy techniques shed light on the cutting mechanism. The nanotube cutting is catalysed by the fundamental mechanism based on the coordination of the silver atoms to the π-bonds of carbon nanotubes. As a result of the metal coordination, the strength of the carbon-carbon bond is reduced, promoting the oxidation of carbon at lower temperature when heated in air, or lowering the activation energy required for the removal of carbon atoms by electron beam irradiation, assuring in both cases the cutting of the nanotubes.

  10. Ag-catalysed cutting of multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    La Torre, A.; Rance, G. A.; Miners, S. A.; Herreros Lucas, C.; Smith, E. F.; Fay, M. W.; Zoberbier, T.; Giménez-López, M. C.; Kaiser, U.; Brown, P. D.; Khlobystov, A. N.

    2016-04-01

    In this work, the cutting of carbon nanotubes is investigated using silver nanoparticles deposited on arc discharge multi-walled carbon nanotubes. The composite is subsequently heated in air to fabricate shortened multi-walled nanotubes. Complementary transmission electron microscopy and spectroscopy techniques shed light on the cutting mechanism. The nanotube cutting is catalysed by the fundamental mechanism based on the coordination of the silver atoms to the π-bonds of carbon nanotubes. As a result of the metal coordination, the strength of the carbon-carbon bond is reduced, promoting the oxidation of carbon at lower temperature when heated in air, or lowering the activation energy required for the removal of carbon atoms by electron beam irradiation, assuring in both cases the cutting of the nanotubes.

  11. 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.

  12. 40 CFR 721.10663 - Functionalized multi-walled carbon nanotubes (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Specific Chemical Substances § 721.10663 Functionalized multi-walled carbon nanotubes (generic). (a... generically as functionalized multi-walled carbon nanotubes (PMN P-12-44) is subject to reporting under this... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Functionalized multi-walled...

  13. 40 CFR 721.10663 - Functionalized multi-walled carbon nanotubes (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Specific Chemical Substances § 721.10663 Functionalized multi-walled carbon nanotubes (generic). (a... generically as functionalized multi-walled carbon nanotubes (PMN P-12-44) is subject to reporting under this... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Functionalized multi-walled...

  14. Synthesis and thermal transport studies of nanofluids based on metal decorated photochemically oxidized multiwalled carbon nanotubes.

    PubMed

    Aravind, S S Jyothirmayee; Ramaprabhu, S

    2012-08-01

    Nanoparticle fluid suspensions were prepared using photochemically functionalized multiwalled carbon nanotubes in polar base fluids. Multiwalled carbon nanotubes prepared by catalytic chemical vapour deposition technique have been functionalized by irradiating with ultraviolet light of wavelength 254 nm. The photochemical oxidation of multiwalled carbon nanotubes under UV irradiation introduces oxygen containing functional groups onto the surface of the nanotubes, generating new defects on their structure. Silver nanoparticles have been deposited over multiwalled carbon nanotubes by chemical method. The enhancement in thermal conductivity of the prepared nanofluids using functionalized multiwalled carbon nanotubes and Ag nanoparticles deposited functionalized multiwalled carbon nanotubes with volume fraction, temperature and aspect ratio has been demonstrated. Silver deposited functionalized multiwalled carbon nanotubes based nanofluids in DI water with 0.02% volume fraction exhibit a thermal conductivity enhancement of 9.9% and 47% at room temperature and at 50 degrees C respectively.

  15. Functionalization of the surface of multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Glebova, N. V.; Nechitaĭlov, A. A.

    2010-10-01

    Features of functionalization of the surface of domestic commercial multiwalled carbon nanotubes by means of the thermal oxidation in air and treatment in nitric acid or a nitric-sulfuric acid mixture has been studied using the method of differential thermal analysis.

  16. Preparation of supported electrocatalyst comprising multiwalled carbon nanotubes

    DOEpatents

    Wu, Gang; Zelenay, Piotr

    2013-08-27

    A process for preparing a durable non-precious metal oxygen reduction electrocatalyst involves heat treatment of a ball-milled mixture of polyaniline and multiwalled carbon nanotubes in the presence of a Fe species. The catalyst is more durable than catalysts that use carbon black supports. Performance degradation was minimal or absent after 500 hours of operation at constant cell voltage of 0.40 V.

  17. Electrical conductivity of polyvinyl alcohol-multiwall carbon nanotubes composites

    NASA Astrophysics Data System (ADS)

    Amrin, Sayed; Deshpande, V. D.

    2013-06-01

    The dc and ac conductivity of polyvinyl alcohol (PVA)-multiwalled carbon nanotube (MWNT) nanocomposites prepared by solution casting were investigated by employing dielectric relaxation spectroscopy in broad frequency range (0.1 Hz-10 MHz) at room temperature as a function of the conductive weight fraction (p) ranging from 0 to 2wt.%. The frequency dependence of the measured conductivity obeys the universal dynamic response (UDR); a dc plateau followed, by the power law above a critical frequency (fc).

  18. Tensile Yielding of Multi-Wall Carbon Nanotube

    NASA Technical Reports Server (NTRS)

    Wei, Chenyu; Cho, Kyeongjae; Srivastava, Deepak; Parks, John W. (Technical Monitor)

    2002-01-01

    The tensile yielding of multiwall carbon nanotubes (MWCNTs) has been studied using Molecular Dynamics simulations and a Transition State Theory based model. We find a strong dependence of the yielding on the strain rate. A critical strain rate has been predicted above/below which yielding strain of a MWCNT is larger/smaller than that of the corresponding single-wall carbon nanotubes. At experimentally feasible strain rate of 1% /hour and T = 300K, the yield strain of a MWCNT is estimated to be about 3-4 % higher than that of an equivalent SWCNT (Single Wall Carbon Nanotube), in good agreement with recent experimental observations.

  19. Characterization of phosphorus-doped multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Larrude, D. G.; Maia da Costa, M. E. H.; Monteiro, F. H.; Pinto, A. L.; Freire, F. L.

    2012-03-01

    Phosphorus-doped multiwalled carbon nanotubes (P-MWNTs) have been successfully synthesized by spray pyrolysis methods using a solution of ferrocene and triphenylphosphine in toluene. Electron microscopy images reveal corrugated tubes with a special morphology, similar to a carbon necklace. P-MWNTs are shorter compared to undoped tubes grown in the same conditions using ferrocene and toluene as precursors. Raman spectroscopy characterization suggests the formation of more defective tubes as the phosphorus in the precursor solution was increased. X-ray photoelectron spectroscopy (XPS) revealing the chemical environment of the phosphorus atoms clearly indicates the presence of substitutional phosphorus in the nanotubes.

  20. Microwave characterization of vertically aligned multiwalled carbon nanotube arrays

    NASA Astrophysics Data System (ADS)

    Katsounaros, Anestis; Rajab, Khalid Z.; Hao, Yang; Mann, Mark; Milne, William I.

    2011-05-01

    Vertically aligned multiwalled carbon nanotube (VACNT) films have been characterized by rectangular waveguide measurements. The complex scattering parameters (S-parameters) are measured by a vector network analyzer at X-band frequencies. The effective complex permittivity and permeability of the VACNT films have been extracted. The extracted parameters are verified by full wave simulations and very good agreement has been obtained. The results of the systematic error analysis are presented and the errors are within the acceptable range. The performance of VACNT films as an absorber is examined, and comparison with the conventional carbon loaded materials shows that a 90% size reduction is possible while maintaining the same absorption level.

  1. Augmentation of acrylic bone cement with multiwall carbon nanotubes.

    PubMed

    Marrs, Brock; Andrews, Rodney; Rantell, Terry; Pienkowski, David

    2006-05-01

    Acrylic bone cement, based on polymethylmethacrylate (PMMA), is a proven polymer having important applications in medicine and dentistry, but this polymer continues to have less than ideal resistance to mechanical fatigue and impact. A variety of materials have been added to bone cement to augment its mechanical strength, but none of these augmentative materials has proven successful. Carbon nanotubes, a new hollow multiwalled tubular material 10-40 nm in diameter, 10-100 microm long, and 50-100 times the strength of steel at 1/6 the weight, have emerged as a viable augmentation candidate because of their large surface area to volume ratio. The objective of this study was to determine if the addition of multiwall carbon nanotubes to bone cement can alter its static or dynamic mechanical properties. Bar-shaped specimens made from six different (0-10% by weight) concentrations of multiwall carbon nanotubes were tested to failure in quasi-static 3-point bending and in 4-point bending fatigue (5 Hz). Analyses of variance and the 3-Parameter Weibull model were used to analyze the material performance data. The 2 wt % MWNT concentration enhanced flexural strength by 12.8% (p=0.003) and produced a 13.1% enhancement in yield stress (p=0.002). Bending modulus increased slightly with the smaller (<5 wt % MWNT) concentrations, but increased 24.1% (p<0.001) in response to the 10 wt % loading. While the 2 wt % loading produced slightly improved quasi-static test results, it was associated with clearly superior fatigue performance (3.3x increase in the Weibull mean fatigue life). Weibull minimum fatigue life (No), Weibull modulus (alpha), and characteristic fatigue life (beta) for bone cement augmented with carbon nanotubes were enhanced versus that observed in the control group. These data unambiguously showed that the bone cement-MWNT polymer system has an enhanced fatigue life compared to "control" bone cement (no added nanotubes). It is concluded that specific multiwall

  2. Electrocatalytic oxygen evolution at surface-oxidized multiwall carbon nanotubes.

    PubMed

    Lu, Xunyu; Yim, Wai-Leung; Suryanto, Bryan H R; Zhao, Chuan

    2015-03-01

    Large-scale storage of renewable energy in the form of hydrogen (H2) fuel via electrolytic water splitting requires the development of water oxidation catalysts that are efficient and abundant. Carbon-based nanomaterials such as carbon nanotubes have attracted significant applications for use as substrates for anchoring metal-based nanoparticles. We show that, upon mild surface oxidation, hydrothermal annealing and electrochemical activation, multiwall carbon nanotubes (MWCNTs) themselves are effective water oxidation catalysts, which can initiate the oxygen evolution reaction (OER) at overpotentials of 0.3 V in alkaline media. Oxygen-containing functional groups such as ketonic C═O generated on the outer wall of MWCNTs are found to play crucial roles in catalyzing OER by altering the electronic structures of the adjacent carbon atoms and facilitates the adsorption of OER intermediates. The well-preserved microscopic structures and highly conductive inner walls of MWCNTs enable efficient transport of the electrons generated during OER.

  3. 40 CFR 721.10266 - Multi-walled carbon nanotubes (generic) (P-08-733 and P-08-734).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Multi-walled carbon nanotubes (generic... Significant New Uses for Specific Chemical Substances § 721.10266 Multi-walled carbon nanotubes (generic) (P... chemical substances identified generically as multi-walled carbon nanotubes (PMNs P-08-733 and...

  4. Plasma-enhanced chemical vapor deposition of multiwalled carbon nanofibers

    NASA Technical Reports Server (NTRS)

    Matthews, Kristopher; Cruden, Brett A.; Chen, Bin; Meyyappan, M.; Delzeit, Lance

    2002-01-01

    Plasma-enhanced chemical vapor deposition is used to grow vertically aligned multiwalled carbon nanofibers (MWNFs). The graphite basal planes in these nanofibers are not parallel as in nanotubes; instead they exhibit a small angle resembling a stacked cone arrangement. A parametric study with varying process parameters such as growth temperature, feedstock composition, and substrate power has been conducted, and these parameters are found to influence the growth rate, diameter, and morphology. The well-aligned MWNFs are suitable for fabricating electrode systems in sensor and device development.

  5. Multiwalled carbon nanotubes as apertures and conduits for energetic ions

    SciTech Connect

    Krasheninnikov, A.V.; Nordlund, K.

    2005-06-15

    We perform molecular dynamics simulations to study motion of heavy ions with kilo-electron-volt energies through multiwalled carbon nanotubes. We show that under certain conditions on the tube alignment with respect to the ion beam and on ion energies, the ions can efficiently channel through the empty cores of the nanotubes. We demonstrate that the dependence of the critical angle on ion energy obeys a simple continuum-theory-based equation. We further discuss making a nanotube-based conduit for energetic ions, which should work as an aperture and allow one to manipulate ion beams at the nanoscale.

  6. Multiwalled carbon nanotube reinforced biomimetic bundled gel fibres.

    PubMed

    Kim, Young-Jin; Yamamoto, Seiichiro; Takahashi, Haruko; Sasaki, Naruo; Matsunaga, Yukiko T

    2016-08-19

    This work describes the fabrication and characterization of hydroxypropyl cellulose (HPC)-based biomimetic bundled gel fibres. The bundled gel fibres were reinforced with multiwalled carbon nanotubes (MWCNTs). A phase-separated aqueous solution with MWCNT and HPC was transformed into a bundled fibrous structure after being injected into a co-flow microfluidic device and applying the sheath flow. The resulting MWCNT-bundled gel fibres consist of multiple parallel microfibres. The mechanical and electrical properties of MWCNT-bundled gel fibres were improved and their potential for tissue engineering applications as a cell scaffold was demonstrated. PMID:27200527

  7. Hyper-crosslinked resins filled with multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Castaldo, R.; Ambrogi, V.; Avolio, R.; Cocca, C.; Errico, M. E.; Gentile, G.; Avella, M.; Carfagna, C.

    2016-05-01

    Hyper-crosslinked styrenic resins are tipically prepared by suspension polymerization of a gel-type precursor and successive crosslinking by Friedel-Crafts reaction. This kind of polymers displays high specific surface area and excellent sorption properties. Hyper-crosslinked resins and nanocomposites containing multiwalled carbon nanotubes (MWCNT) were prepared in this study. Structure and properties of hyper-crosslinked resins containing MWCNT were investigated. Moreover, a new synthetic process of the nanocomposites was developed, based on the bulk polymerization of the precursor resin. The effect of the synthetic procedure and the addition of nanofillers on the material specific surface area, porosity and adsorption properties were explored.

  8. Macrodispersion of multi-walled carbon nanotubes for conductive films.

    PubMed

    Kim, Duckjong; Zhu, Lijing; Kim, Jae-Hyun; Han, Chang-Soo; Baik, Seunghyun

    2012-04-01

    Understanding of the effect of the multi-walled carbon nanotube (MWCNT) dispersion process on physical properties of MWCNT film is crucial in process optimization of MWCNT film-based products. In the present work, the electrical conduction property of MWCNT films according to various conditions in MWCNT dispersion is investigated. Spectroscopic analysis of dispersed MWCNTs show that the electrical resistance of the MWCNT conductive film is affected by an increase in the electrical contacts between adjacent CNTs due to CNT debundling and physical damage caused by ultrasonic processing. Based on the two conflicting parameters, dispersion guidelines for highly conductive MWCNT film are presented. PMID:22849134

  9. Morphological variation of multiwall carbon nanotubes in supercritical water oxidation

    NASA Astrophysics Data System (ADS)

    Chang, Jia-Yaw; Lo, Bertrand; Jeng, Meili; Tzing, Shin-Hwa; Ling, Yong-Chien

    2004-09-01

    Multiwall carbon nanotubes (MWNTs) with different morphology were prepared using supercritical water (SCW) oxidation and investigated by transmission electron microscope (TEM) and electron energy-loss spectroscopy (EELS). TEM results indicate that the peeling and sharpening of MWNTs are influenced by the etching process in SCW oxidation, of which oxidation time and amount of oxygen used is crucial. A simplified etching model is proposed, which indicates that the difference of mean etching rate between two adjoining blocks causes the morphological variation of MWNTs. The EELS results show change in characteristic energy-loss peaks as a function of total shell numbers along longitudinal axis of individual peeled tube.

  10. Correlating electrical resistance to growth conditions for multiwalled carbon nanotubes

    SciTech Connect

    Lan, Chun; Amama, Placidus B.; Fisher, Timothy S.; Reifenberger, Ronald G.

    2007-08-27

    A correlation between growth temperature and electrical resistance of multiwalled carbon nanotubes (MWNTs) has been established by measuring the resistance of individual MWNTs grown by microwave plasma-enhanced chemical vapor deposition (PECVD) at 800, 900, and 950 deg. C. The lowest resistances were obtained mainly from MWNTs grown at 900 deg. C. The MWNT resistance is larger on average at lower (800 deg. C) and higher (950 deg. C) growth temperatures. The resistance of MWNTs correlated well with other MWNT quality indices obtained from Raman spectra. This study identifies a temperature window for growing higher-quality MWNTs with fewer defects and lower resistance by PECVD.

  11. Correlating electrical resistance to growth conditions for multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Lan, Chun; Amama, Placidus B.; Fisher, Timothy S.; Reifenberger, Ronald G.

    2007-08-01

    A correlation between growth temperature and electrical resistance of multiwalled carbon nanotubes (MWNTs) has been established by measuring the resistance of individual MWNTs grown by microwave plasma-enhanced chemical vapor deposition (PECVD) at 800, 900, and 950°C. The lowest resistances were obtained mainly from MWNTs grown at 900°C. The MWNT resistance is larger on average at lower (800°C) and higher (950°C) growth temperatures. The resistance of MWNTs correlated well with other MWNT quality indices obtained from Raman spectra. This study identifies a temperature window for growing higher-quality MWNTs with fewer defects and lower resistance by PECVD.

  12. Hot wire production of single-wall and multi-wall carbon nanotubes

    DOEpatents

    Dillon, Anne C.; Mahan, Archie H.; Alleman, Jeffrey L.

    2010-10-26

    Apparatus (210) for producing a multi-wall carbon nanotube (213) may comprise a process chamber (216), a furnace (217) operatively associated with the process chamber (216), and at least one filament (218) positioned within the process chamber (216). At least one power supply (220) operatively associated with the at least one filament (218) heats the at least one filament (218) to a process temperature. A gaseous carbon precursor material (214) operatively associated with the process chamber (216) provides carbon for forming the multi-wall carbon nanotube (213). A metal catalyst material (224) operatively associated with the process (216) catalyzes the formation of the multi-wall carbon nanotube (213).

  13. Adsorption of emerging pollutants on functionalized multiwall carbon nanotubes.

    PubMed

    Patiño, Yolanda; Díaz, Eva; Ordóñez, Salvador; Gallegos-Suarez, Esteban; Guerrero-Ruiz, Antonio; Rodríguez-Ramos, Inmaculada

    2015-10-01

    Adsorption of three representative emerging pollutants - 1,8-dichlorooctane, nalidixic acid and 2-(4-methylphenoxy)ethanol- on different carbon nanotubes was studied in order to determine the influence of the morphological and chemical properties of the materials on their adsorption properties. As adsorbents, multiwall carbon nanotubes (MWCNTs) without functionalization and with oxygen or nitrogen surface groups, as well as carbon nanotubes doped with nitrogen were used. The adsorption was studied in aqueous phase using batch adsorption experiments, results being fitted to both Langmuir and Freundlich models. The adsorption capacity is strongly dependent on both the hydrophobicity of the adsorbates and the morphology of the adsorbents. Thermodynamic parameters were determined observing strong interactions between the aromatic rings of the emerging pollutant and the nitrogen modified adsorbents.

  14. Controlled modification of multiwalled carbon nanotubes with Zno nanostructures

    SciTech Connect

    Wang Xiuying; Xia Baiying; Zhu Xingfu; Chen Jiesheng; Qiu Shilun; Li Jixue

    2008-04-15

    Multiwalled carbon nanotubes (MWNTs) have been successfully modified with ZnO nanostructures by zinc-ammonitum complex ion covalently attached to the MWNTs through the C-N bonds. Flower-like ZnO on the tips of MWNTs and ZnO nanoparticles on the surface of MWNTs have been obtained, respectively, via adjusting the reaction time. The modified MWNTs have been characterized with X-ray diffraction, scanning electron and transmission electron microscopy. A growth mechanism has been proposed in which the soaking time plays a key role in controlling the size, morphology, and site of ZnO nanostructures. Photoluminescence properties of the as-synthesized products have also been investigated. - Multiwalled carbon nanotube (MWNT)/flower-like ZnO heterojunctions and MWNT/ZnO nanoparticle composites were prepared by zinc-ammonitum complex ion covalently attached to the MWNTs through the C-N bonds via adjusting the reaction time. A growth mechanism has been proposed in which the soaking time plays a key role in controlling the size, morphology, and site of ZnO nanostructures.

  15. Bacterial remediation from effluent containing multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Lemes, A. P.; Cordi, L.; Santos, A.; Durán, N.

    2011-07-01

    Multi-wall carbon nanotubes (MWCNT) were functionalized with functional groups containing oxygen, mainly carboxylic groups (-COOH), through reaction with a mixture of H2SO4/HNO3 (3:1 v/v). The oxidized multi-wall carbon nanotubes (MWCNTOOH) were used to prepare an effluent, 2 mg L-1 in a saline solution of NaCl (0.9%), to study of remediation of MWCNTOOH in aqueous suspension by utilization of Escherichia coli. The suspensions of E. coli (4.5 × 105 CFU mL-1 and 4.5 × 108 CFU mL-1) in test tubes with MWCNTOOH effluent caused the precipitation of a large amount of MWCNTOOH and supernatant clearing. The scanning electron microscopy (SEM) analysis of the precipitate and supernatant showed the adhesion and interlace of MWCNTOOH in bacteria surface. Although the precipitate consist of a large quantity of MWCNTOOH and bacteria, it was verified their presence in the supernatant. The spread plate technique showed that MWCNTOOH caused no cellular death of E. coli in the supernatant.

  16. Modeling Composites of Multi-Walled Carbon Nanotubes in Polycarbonate

    NASA Astrophysics Data System (ADS)

    Jindal, Prashant; Goyal, Meenakshi; Kumar, Navin

    2013-10-01

    High strain rate experiments performed on multi-walled carbon nanotubes, polycarbonate composites (MWCNT-PC) have exhibited enhanced impact resistance under a dynamic strain rate of nearly 2500/s with composition of only 0.5 to 2.0% multi-walled carbon nanotubes (MWCNTs) in pure polycarbonate (PC). Similarly, hardness and elastic modulus under static loads resulted in a significant increase, depending upon the composition of MWCNTs in PC. The present work aims to analyze these results by correlating the data to fit expressions in generalizing the behavior of MWCNTs composition for MWCNT-PC composites under both static and impact loads. As a result, we found that an optimum composition of 2.1 weight % of MWCNTs exhibits maximum stress resistance within elastic range under strain rates of nearly 2500/s for MWCNT-PC composites. The composition of MWCNTs plays a crucial role in maximizing modification of static and dynamic impact-based mechanical properties of polycarbonates. Further, a simple model based on Lennard-Jones 6-12 atom-atom based potential is formulated and used to compute preliminary estimates of static properties of pure as well as composite PC with the aim to modify this in subsequent approaches.

  17. Gate-controlled superconductivity in diffusive multiwalled carbon nanotube

    NASA Astrophysics Data System (ADS)

    Hakonen, Pertti

    2007-03-01

    We have investigated electrical transport in a diffusive, PECVD-grown multiwalled carbon nanotube contacted using superconducting leads made of Al/Ti sandwich structure. We find proximity-induced superconductivity with measured critical currents up to Icm= 1.3 nA, tunable by gate voltage. The supercurrent branch displays a finite zero bias resistance which varies as R0Icm^-α with α=0.74. We discuss the interpretation of these findings in terms of the RCSJ-model as well as the diffusive junction model for long SNS structures. In addition, we will compare the results with our recent data on proximity-induced supercurrents in singlewalled carbon nanotubes.

  18. Synthesis and characterization of chitosan-multiwalled carbon nanotubes/hydroxyapatite nanocomposites for bone tissue engineering.

    PubMed

    Chen, Li; Hu, Jingxiao; Shen, Xinyu; Tong, Hua

    2013-08-01

    Chitosan-multiwalled carbon nanotubes/hydroxyapatite nanocomposites were synthesized by a novel in situ precipitation method. The electrostatic adsorption between multiwalled carbon nanotubes and chitosan was investigated and explained by Fourier transform infrared spectroscopy analysis. Morphology studies showed that uniform distribution of hydroxyapatite particles and multiwalled carbon nanotubes in the polymer matrix was observed. In chitosan-multiwalled carbon nanotubes/hydroxyapatite nanocomposites, the diameters of multiwalled carbon nanotubes were about 10 nm. The mechanical properties of the composites were evaluated by measuring their compressive strength and elastic modulus. The elastic modulus and compressive strength increased sharply from 509.9 to 1089.1 MPa and from 33.2 to 105.5 MPa with an increase of multiwalled carbon/chitosan weight ratios from 0 to 5 %, respectively. Finally, the cell biocompatibility of the composites was tested in vitro, which showed that they have good biocompatibility. These results suggest that the chitosan-multiwalled carbon nanotubes/hydroxyapatite nanocomposites are promising biomaterials for bone tissue engineering.

  19. Multiwalled carbon nanotubes in alfalfa and wheat: toxicology and uptake

    PubMed Central

    Miralles, Pola; Johnson, Errin; Church, Tamara L.; Harris, Andrew T.

    2012-01-01

    Data on the bioavailability and toxicity of carbon nanotubes (CNTs) in the environment, and, in particular, on their interactions with vascular plants, are limited. We investigated the effects of industrial-grade multiwalled CNTs (75 wt% CNTs) and their impurities on alfalfa and wheat. Phytotoxicity assays were performed during both seed germination and seedling growth. The germinations of both species were tolerant of up to 2560 mg l−1 CNTs, and root elongation was enhanced in alfalfa and wheat seedlings exposed to CNTs. Remarkably, catalyst impurities also enhanced root elongation in alfalfa seedlings as well as wheat germination. Thus the impurities, not solely the CNTs, impacted the plants. CNT internalization by plants was investigated using electron microscopy and two-dimensional Raman mapping. The latter showed that CNTs were adsorbed onto the root surfaces of alfalfa and wheat without significant uptake or translocation. Electron microscopy investigations of internalization were inconclusive owing to poor contrast, so Fe3O4-functionalized CNTs were prepared and studied using energy-filter mapping of Fe3O4. CNTs bearing Fe3O4 nanoparticles were detected in the epidermis of one wheat root tip only, suggesting that internalization was possible but unusual. Thus, alfalfa and wheat tolerated high concentrations of industrial-grade multiwalled CNTs, which adsorbed onto their roots but were rarely taken up. PMID:22977097

  20. Thermal expansion of multiwall carbon nanotube reinforced nanocrystalline silver matrix composite

    SciTech Connect

    Sharma, Manjula Sharma, Vimal; Pal, Hemant

    2014-04-24

    Multiwall carbon nanotube reinforced silver matrix composite was fabricated by novel molecular level mixing method, which involves nucleation of Ag ions inside carbon nanotube dispersion at the molecular level. As a result the carbon nanotubes get embedded within the powder rather than on the surfaces. Micro structural characterization by X- ray diffraction and scanning electron microscopy reveals that the nanotubes are homogeneously dispersed and anchored within the matrix. The thermal expansion of the composite with the multiwall nanotube content (0, 1.5 vol%) were investigated and it is found that coefficient of thermal expansion decreases with the addition of multiwall nanotube content and reduce to about 63% to that of pure Ag.

  1. Analysis of the low-temperature specific heat of multiwalled carbon nanotubes and carbon nanotube ropes

    SciTech Connect

    Mizel, A.; Benedict, L.X. |; Cohen, M.L.; Louie, S.G.; Zettl, A.; Budraa, N.K.; Beyermann, W.P.

    1999-08-01

    We analyze specific-heat measurements in the temperature range 1{lt}T{lt}200 K for two types of carbon nanotube samples: multiwalled tubes and ropes of single-walled tubes. The multiwalled tube sample has a specific-heat not unlike that of graphite, which we maintain is reasonable given the structural similarities between the two materials. In contrast, the low-temperature specific-heat data for ropes are surprisingly large in magnitude and have surprisingly strong temperature dependence. We present model calculations that highlight the puzzling nature of these results and then suggest explanations. {copyright} {ital 1999} {ital The American Physical Society}

  2. Noncovalent functionalization of multiwalled carbon nanotubes: application in hybrid nanostructures.

    PubMed

    Wang, Tie; Hu, Xiaoge; Qu, Xiaohu; Dong, Shaojun

    2006-04-01

    We developed a reproducible, noncovalent strategy to functionalize multiwalled carbon nanotubes (MWNTs) via embedding nanotubes in polysiloxane shells. (3-Aminopropyl)triethoxysilane molecules adsorbed to the nanotube surfaces via hydrophobic interactions are polymerized simply by acid catalysis and form a thin polysiloxane layer. On the basis of the embedded MWNTs, negatively charged gold nanoparticles are anchored to the nanotube surfaces via electrostatic interactions between the protonated amino groups and the gold nanoparticles. Furthermore, these gold nanoparticles can further grow and magnify along the nanotubes through heating in HAuCl4 aqueous solution at 100 degrees C; as a result these nanoparticles are joined to form continuous gold nanowires with MWNTs acting as templates. PMID:16570965

  3. Magnetic Multi-Walled Carbon Nanotubes for Tumor Theranostics.

    PubMed

    Wang, Lei; Shi, Jinjin; Hao, Yongwei; Zhang, Panpan; Zhao, Yalin; Meng, Dehui; Li, Dong; Chang, Junbiao; Zhang, Zhenzhong

    2015-09-01

    Current diagnostic techniques do not reliably detect cancer at early stages, and traditional chemotherapy lacks specificity and causes systemic toxicity. To address these issues, multifunctional nanomaterials are becoming more widely studied as a means of cancer detection, therapy, and monitoring. Here, iron oxide (Fe3O4) nanoparticles were conjugated onto the surface of multi-walled carbon nanotubes (MWNTs), which were then modified with polyethylenimine (PEI) and polyethylene glycol (PEG) to improve their solubility and biocompatibility. Finally, human telomerase reverse transcriptase (hTERT) siRNA was loaded on the MWNT surface by electrostatic interaction to obtain a multifunctional delivery system (MWNT-Fe3O4-PEI-PEG/siRNA). This delivery system efficiently delivered siRNA, allowed targeting of certain sites by magnetic fields, facilitated photothermal heating by near infrared irradiation, and enabled magnetic resonance imaging, thereby indicating great potential for cancer theranostic applications. PMID:26485934

  4. Electric current distribution of a multiwall carbon nanotube

    NASA Astrophysics Data System (ADS)

    Chen, Li-Ying; Chen, Yu-Jyun; Chang, Chia-Seng

    2016-07-01

    The electric current distribution in a multiwall carbon nanotube (MWCNT) was studied by in situ measuring the electric potential along an individual MWCNT in the ultra-high vacuum transmission electron microscope (TEM). The current induced voltage drop along each section of a side-bonded MWCNT was measured by a potentiometric probe in TEM. We have quantitatively derived that the current on the outermost shell depends on the applied current and the shell diameter. More proportion of the total electronic carriers hop into the inner shells when the applied current is increased. The larger a MWCNT's diameter is, the easier the electronic carriers can hop into the inner shells. We observed that, for an 8 nm MWCNT with 10 μA current applied, 99% of the total current was distributed on the outer two shells.

  5. Microwave attenuation of multiwalled carbon nanotube-fused silica composites

    SciTech Connect

    Xiang Changshu; Pan Yubai; Liu Xuejian; Sun Xingwei; Shi Xiaomei; Guo Jingkun

    2005-09-19

    Multiwalled carbon nanotubes (MWCNTs) were used to convert radome materials to microwave absorbing materials. Dense MWCNT-fused silica composites were prepared by hot-pressing technique. The composites exhibit high complex permittivities at X-band frequencies, depending on the content of MWCNTs. The value of the loss tangent increases three orders over pure fused silica only by incorporating 2.5 vol % MWCNTs into the composites. The average magnitude of microwave transmission reaches -33 dB at 11-12 GHz in the 10 vol % MWCNT-fused silica composites, which indicates the composites have excellent microwave attenuation properties. The attenuation properties mainly originate from the electric loss of MWCNTs by the motion of conducting electrons.

  6. Freestanding Aligned Multi-walled Carbon Nanotubes for Supercapacitor Devices

    NASA Astrophysics Data System (ADS)

    Moreira, João Vitor Silva; Corat, Evaldo José; May, Paul William; Cardoso, Lays Dias Ribeiro; Lelis, Pedro Almeida; Zanin, Hudson

    2016-08-01

    We report on the synthesis and electrochemical properties of multi-walled carbon nanotubes (MWCNTs) for supercapacitor devices. Freestanding vertically-aligned MWCNTs and MWCNT powder were grown concomitantly in a one-step chemical vapour deposition process. Samples were characterized by scanning and transmission electron microscopies and Fourier transform infrared and Raman spectroscopies. At similar film thicknesses and surface areas, the freestanding MWCNT electrodes showed higher electrochemical capacitance and gravimetric specific energy and power than the randomly-packed nanoparticle-based electrodes. This suggests that more ordered electrode film architectures facilitate faster electron and ion transport during the charge-discharge processes. Energy storage and supply or supercapacitor devices made from these materials could bridge the gap between rechargeable batteries and conventional high-power electrostatic capacitors.

  7. Features of the oxidation of multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Savilov, S. V.; Ivanov, A. S.; Chernyak, S. A.; Kirikova, M. N.; Ni, J.; Lunin, V. V.

    2015-11-01

    Features of the functionalization of multiwalled carbon nanotubes (MWCNTs) with a conical (Ni precursor) and cylindrical (Fe precursor) arrangement of graphene layers using various oxidizing agents are studied. The initial diameter of pyrolytically prepared tubes varies from 20 to 80 nm with a maximum at 40-45 nm and from 10 to 30 nm with a maximum at 18 nm in the first and second cases, respectively. Oxidative modification of the MWCNT surfaces is conducted using HNO3 and H2O2 with ultrasound activation, ozonation in a glow discharge plasma of oxygen, and treatment with liquid ozone. Thermal and elemental analyses and IR spectroscopy show that the highest content of functional groups is achieved in the samples treated with nitric acid, where the conical MWCNTs are subject to surface functionalization. It is concluded that in order to achieve a similar result, cylindrical tubes must be treated with liquid ozone.

  8. Control of growth mode of multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Quang, Nguyen Hong; Kim, Do-Hyung

    2009-09-01

    We have conducted an experimental study to investigate the synthesis of multi-walled carbon nanotubes (CNTs) by a dc plasma-enhanced chemical vapour deposition (PECVD) technique. The synthesis of base and tip-type of CNTs was selectively controlled by changing the catalyst size, catalyst film thickness correlated with altering the NH3 pretreatment plasma current. These types of CNT showed distinctive properties in nanotube structure, growth rate and vertical alignment, which were confirmed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and in situ optical interference measurement. The vertically aligned behaviour of CNT was systematically studied by using a fine-patterned catalyst layer with diverse critical dimensions. Freestanding single CNT was successfully realized by optimum tip-type CNT growth, conventional photolithography and wet-etch process.

  9. Multiwalled carbon nanotube deposition on model environmental surfaces.

    PubMed

    Chang, Xiaojun; Bouchard, Dermont C

    2013-09-17

    Deposition of multiwalled carbon nanotubes (MWNTs) on model environmental surfaces was investigated using a quartz crystal microbalance with dissipation monitoring (QCM-D). Deposition behaviors of MWNTs on positively and negatively charged surfaces were in good agreement with Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, although hydrophobic interactions dominated MWNTs deposition on a hydrophobic polystyrene surface. Initial deposition rates (rf) and deposition attachment efficiencies (αD) depended on solution ionic strengths (IS) and surface electrostatic properties. Identical rf and αD values at constant IS on similar surfaces suggested that deposition was insensitive to surface morphology (i.e., bare crystal surface vs coated surface). The dissipation unit (D) was used with frequency (f) to investigate nanoparticle deposition: |ΔD/Δf| values varied for deposition on different surfaces, indicating that the nature of MWNT association with surfaces varied despite constant rf and αD values.

  10. Freestanding Aligned Multi-walled Carbon Nanotubes for Supercapacitor Devices

    NASA Astrophysics Data System (ADS)

    Moreira, João Vitor Silva; Corat, Evaldo José; May, Paul William; Cardoso, Lays Dias Ribeiro; Lelis, Pedro Almeida; Zanin, Hudson

    2016-11-01

    We report on the synthesis and electrochemical properties of multi-walled carbon nanotubes (MWCNTs) for supercapacitor devices. Freestanding vertically-aligned MWCNTs and MWCNT powder were grown concomitantly in a one-step chemical vapour deposition process. Samples were characterized by scanning and transmission electron microscopies and Fourier transform infrared and Raman spectroscopies. At similar film thicknesses and surface areas, the freestanding MWCNT electrodes showed higher electrochemical capacitance and gravimetric specific energy and power than the randomly-packed nanoparticle-based electrodes. This suggests that more ordered electrode film architectures facilitate faster electron and ion transport during the charge-discharge processes. Energy storage and supply or supercapacitor devices made from these materials could bridge the gap between rechargeable batteries and conventional high-power electrostatic capacitors.

  11. Magnetic Multi-Walled Carbon Nanotubes for Tumor Theranostics.

    PubMed

    Wang, Lei; Shi, Jinjin; Hao, Yongwei; Zhang, Panpan; Zhao, Yalin; Meng, Dehui; Li, Dong; Chang, Junbiao; Zhang, Zhenzhong

    2015-09-01

    Current diagnostic techniques do not reliably detect cancer at early stages, and traditional chemotherapy lacks specificity and causes systemic toxicity. To address these issues, multifunctional nanomaterials are becoming more widely studied as a means of cancer detection, therapy, and monitoring. Here, iron oxide (Fe3O4) nanoparticles were conjugated onto the surface of multi-walled carbon nanotubes (MWNTs), which were then modified with polyethylenimine (PEI) and polyethylene glycol (PEG) to improve their solubility and biocompatibility. Finally, human telomerase reverse transcriptase (hTERT) siRNA was loaded on the MWNT surface by electrostatic interaction to obtain a multifunctional delivery system (MWNT-Fe3O4-PEI-PEG/siRNA). This delivery system efficiently delivered siRNA, allowed targeting of certain sites by magnetic fields, facilitated photothermal heating by near infrared irradiation, and enabled magnetic resonance imaging, thereby indicating great potential for cancer theranostic applications.

  12. 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.

  13. 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

  14. Synthesis of multiwalled carbon nanotube from different grades of carbon black using arc discharge method

    NASA Astrophysics Data System (ADS)

    Arora, Neha; Sharma, N. N.

    2016-04-01

    This paper describes the synthesis of nanotube from different grades (Tread * A(non-ASTM), N134,N121,N660 and N330)of carbon black using DC arc discharge method at 40A current for 60sec. Carbon black samples of different grades were procured from industry (Aditya Birla Science and Technology Limited, India). Scanning Electron Micrographs (SEM) of the deposited carbon nanostructures suggests that MWCNTs are formed at 40A and for a minimal exposure time of 60sec.The result formed indicates the N330 grade of carbon black gets converted to MWCNTs (Multiwall Carbon nanotube) as compared to other grades.

  15. Exchange of Surfactant by Natural Organic Matter on the Surfaces of Multi-Walled Carbon Nanotubes

    EPA Science Inventory

    The increasing production and applications of multi-walled carbon nanotubes (MWCNTs) have elicited concerns regarding their release and potential adverse effects in the environment. To form stable aqueous MWCNTs suspensions, surfactants are often employed to facilitate dispersion...

  16. Supramolecular assembly and antitumor activity of multiwalled carbon nanotube-camptothecin complexes.

    PubMed

    Tian, Zhong; Yin, Min; Ma, Hongmei; Zhu, Longzhang; Shen, Hebei; Jia, Nengqin

    2011-02-01

    The novel supramolecular complexes were prepared with a water-insoluble anticancer drug camptothecin (CPT) loading onto functionalized multiwalled carbon nanotubes via pi-stacking, in order to improve their solubility and antitumor activity. The multiwalled carbon nanotubes were firstly coated with the tri-block copolymer (Pluronic P123) to render high aqueous solubility. The copolymer-coated multiwalled carbon nanotubes can effectively form non-covalent supramolecular complexes with camptothecin. The supramolecular assembly of the complexes (f-MWNTs-CPT) were systematically characterized by transmission electron microscopy (TEM), UV-vis spectrophotometry (UV), fluorescence spectrophotometry, atomic force microscopy (AFM) and electrochemical impedance spectroscopy (EIS). Furthermore, in vitro cytotoxicity studies of f-MWNTs-CPT supramolecular complexes using the MTT assay exhibit enhanced antitumor activity, suggesting that the functionalized multiwalled carbon nanotubes can facilitate intracellular delivery of anticancer drug and improve drug activity.

  17. Multiwalled Carbon Nanotube Dispersion Methods Affect Their Aggregation, Deposition, and Biomarker Response

    EPA Science Inventory

    To systematically evaluate how dispersion methods affect the environmental behaviors of multiwalled carbon nanotubes (MWNTs), MWNTs were dispersed in various solutions (e.g., surfactants, natural organic matter (NOM), and etc.) via ultrasonication (SON) and long-term stirring (LT...

  18. Hydrophilic multi-walled carbon nanotubes decorated with magnetite nanoparticles as lymphatic targeted drug delivery vehicles.

    PubMed

    Yang, Dong; Yang, Feng; Hu, Jianhua; Long, Jiang; Wang, Changchun; Fu, Deliang; Ni, Quanxing

    2009-08-01

    Hydrophilic multi-walled carbon nanotubes decorated with magnetite nanoparticles were readily taken up into lymph vessels and delivered gemcitabine to lymph nodes with high efficiency under the guidance of a magnetic field.

  19. 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.

  20. Composite yarns of multiwalled carbon nanotubes with metallic electrical conductivity.

    PubMed

    Randeniya, Lakshman K; Bendavid, Avi; Martin, Philip J; Tran, Canh-Dung

    2010-08-16

    Unique macrostructures known as spun carbon-nanotube fibers (CNT yarns) can be manufactured from vertically aligned forests of multiwalled carbon nanotubes (MWCNTs). These yarns behave as semiconductors with room-temperature conductivities of about 5 x 10(2) S cm(-1). Their potential use as, for example, microelectrodes in medical implants, wires in microelectronics, or lightweight conductors in the aviation industry has hitherto been hampered by their insufficient electrical conductivity. In this Full Paper, the synthesis of metal-CNT composite yarns, which combine the unique properties of CNT yarns and nanocrystalline metals to obtain a new class of materials with enhanced electrical conductivity, is presented. The synthesis is achieved using a new technique, self-fuelled electrodeposition (SFED), which combines a metal reducing agent and an external circuit for transfer of electrons to the CNT surface, where the deposition of metal nanoparticles takes place. In particular, the Cu-CNT and Au-CNT composite yarns prepared by this method have metal-like electrical conductivities (2-3 x 10(5) S cm(-1)) and are mechanically robust against stringent tape tests. However, the tensile strengths of the composite yarns are 30-50% smaller than that of the unmodified CNT yarn. The SFED technique described here can also be used as a convenient means for the deposition of metal nanoparticles on solid electrode supports, such as conducting glass or carbon black, for catalytic applications.

  1. Optical Study of Liquid Crystal Doped with Multiwalled Carbon Nanotube

    NASA Astrophysics Data System (ADS)

    Gharde, Rita A.; Thakare, Sangeeta Y.

    2014-11-01

    Liquid crystalline materials have been useful for display devices i.e watches, calculators, automobile dashboards, televisions, multi media projectors etc. as well as in electro tunable lasers, optical fibers and lenses. Carbon nanotube is chosen as the main experimental factor in this study as it has been observed that Carbon Nano Tube influence the existing properties of liquid crystal host and with the doping of CNT can enhance1 the properties of LC. The combination of carbon nanotube (CNT) and liquid crystal (LC) materials show considerable interest in the scientific community due to unique physical properties of CNT in liquid crystal. Dispersion of CNTs in LCs can provide us a cheap, simple, versatile and effective means of controlling nanotube orientation on macroscopic scale with no restrictions on nanotube type. LCs have the long range orientational order rendering them to be anisotropic phases. If CNTs can be well dispersed in LC matrix, they will align with their long axes along the LC director to minimize distortions of the LC director field and the free energy. In this paper, we doped liquid crystal (Cholesteryl Nonanoate) by a small amount of multiwall carbon nanotube 0.05% and 0.1% wt. We found that by adding carbon nanotube to liquid crystals the melting point of the mixture is decreased but TNI is increased. It has been also observed that with incereas in concentration of carbon nanotube into liquid crystal shows conciderable effect on LC. The prepared samples were characterized using various techniques to study structural, thermal and optical properties i.e PMS, FPSS, UV-Vis spectroscopy, FT-IR measurements, and DTA.

  2. Polymer Grafted Janus Multi-Walled Carbon Nanotubes

    SciTech Connect

    Priftis, Dimitrios; Sakellariou, Georgios; Baskaran, Durairaj; Mays, Jimmy; Hadjichristidis, Nikos

    2009-01-01

    We describe a novel and facile strategy to modify the surface of carbon nanotubes (CNTs) with two chemically different polymer brushes utilizing the grafting from technique. A [4 + 2] Diels Alder cycloaddition reaction was used to functionalize multi-walled carbon nanotubes (MWNTs) with two different precursor initiators, one for ring opening polymerization (ROP) and one for atom transfer radical polymerization (ATRP). The binary functionalized MWNTs were used for the simultaneous surface initiated polymerizations of different monomers resulting in polymer grafted MWNTs that can form Janus type structures under appropriate conditions. 1H NMR, FTIR and Raman spectra showed that the precursor initiators were successfully synthesized and covalently attached on the CNT surface. Thermogravimetric analysis (TGA) revealed that the grafted polymer content varies when different monomer ratios and polymerization times are used. The presence of an organic layer around the CNTs was observed through transmission electron microscopy (TEM). Differential scanning calorimetry (DSC) proved that the glass transition (Tg) and melting (Tm) temperatures of the grafted polymers are affected by the presence of the CNTs, while circular dichroism (CD) spectra indicated that the PLLA ahelix conformation remains intact.

  3. Heat dissipation for microprocessor using multiwalled carbon nanotubes based liquid.

    PubMed

    Hung Thang, Bui; Trinh, Pham Van; Chuc, Nguyen Van; Khoi, Phan Hong; Minh, Phan Ngoc

    2013-01-01

    Carbon nanotubes (CNTs) are one of the most valuable materials with high thermal conductivity (2000 W/m · K compared with thermal conductivity of Ag 419 W/m · K). This suggested an approach in applying the CNTs in thermal dissipation system for high power electronic devices, such as computer processor and high brightness light emitting diode (HB-LED). In this work, multiwalled carbon nanotubes (MWCNTs) based liquid was made by COOH functionalized MWCNTs dispersed in distilled water with concentration in the range between 0.2 and 1.2 gram/liter. MWCNT based liquid was used in liquid cooling system to enhance thermal dissipation for computer processor. By using distilled water in liquid cooling system, CPU's temperature decreases by about 10°C compared with using fan cooling system. By using MWCNT liquid with concentration of 1 gram/liter MWCNTs, the CPU's temperature decreases by 7°C compared with using distilled water in cooling system. Theoretically, we also showed that the presence of MWCNTs reduced thermal resistance and increased the thermal conductivity of liquid cooling system. The results have confirmed the advantages of the MWCNTs for thermal dissipation systems for the μ -processor and other high power electronic devices.

  4. Effect of multiwalled carbon nanotubes on UASB microbial consortium.

    PubMed

    Yadav, Tushar; Mungray, Alka A; Mungray, Arvind K

    2016-03-01

    The continuous rise in production and applications of carbon nanotubes (CNTs) has grown a concern about their fate and toxicity in the environment. After use, these nanomaterials pass through sewage and accumulate in wastewater treatment plants. Since, such plants rely on biological degradation of wastes; their activity may decrease due to the presence of CNTs. This study investigated the effect of multiwalled carbon nanotubes (MWCNTs) on upflow anaerobic sludge blanket (UASB) microbial activity. The toxic effect on microbial viability, extracellular polymeric substances (EPS), volatile fatty acids (VFA), and biogas generation was determined. The reduction in a colony-forming unit (CFU) was 29 and 58 % in 1 and 100 mg/L test samples, respectively, as compared to control. The volatile fatty acids and biogas production was also found reduced. The scanning electron microscopy (SEM) and fluorescent microscopy images confirmed that the MWCNT mediated microbial cell damage. This damage caused the increase in EPS carbohydrate, protein, and DNA concentration. Fourier transform infrared (FTIR) spectroscopy results supported the alterations in sludge EPS due to MWCNT. Our observations offer a new insight to understand the nanotoxic effect of MWCNTs on UASB microflora in a complex environment system.

  5. Heat Dissipation for Microprocessor Using Multiwalled Carbon Nanotubes Based Liquid

    PubMed Central

    Trinh, Pham Van; Chuc, Nguyen Van; Khoi, Phan Hong; Minh, Phan Ngoc

    2013-01-01

    Carbon nanotubes (CNTs) are one of the most valuable materials with high thermal conductivity (2000 W/m · K compared with thermal conductivity of Ag 419 W/m · K). This suggested an approach in applying the CNTs in thermal dissipation system for high power electronic devices, such as computer processor and high brightness light emitting diode (HB-LED). In this work, multiwalled carbon nanotubes (MWCNTs) based liquid was made by COOH functionalized MWCNTs dispersed in distilled water with concentration in the range between 0.2 and 1.2 gram/liter. MWCNT based liquid was used in liquid cooling system to enhance thermal dissipation for computer processor. By using distilled water in liquid cooling system, CPU's temperature decreases by about 10°C compared with using fan cooling system. By using MWCNT liquid with concentration of 1 gram/liter MWCNTs, the CPU's temperature decreases by 7°C compared with using distilled water in cooling system. Theoretically, we also showed that the presence of MWCNTs reduced thermal resistance and increased the thermal conductivity of liquid cooling system. The results have confirmed the advantages of the MWCNTs for thermal dissipation systems for the μ-processor and other high power electronic devices. PMID:24453829

  6. Turning refuse plastic into multi-walled carbon nanotube forest

    NASA Astrophysics Data System (ADS)

    Oh, Eugene; Lee, Jaegeun; Jung, Seung-Ho; Cho, Seungho; Kim, Hye-Jin; Lee, Sung-Hyun; Lee, Kun-Hong; Song, Kyong-Hwa; Choi, Chi-Hoon; Han, Do Suck

    2012-04-01

    A novel and effective method was devised for synthesizing a vertically aligned carbon nanotube (CNT) forest on a substrate using waste plastic obtained from commercially available water bottles. The advantages of the proposed method are the speed of processing and the use of waste as a raw material. A mechanism for the CNT growth was also proposed. The growth rate of the CNT forest was ~2.5 μm min-1. Transmission electron microscopy images indicated that the outer diameters of the CNTs were 20-30 nm on average. The intensity ratio of the G and D Raman bands was 1.27 for the vertically aligned CNT forest. The Raman spectrum showed that the wall graphitization of the CNTs, synthesized via the proposed method was slightly higher than that of commercially available multi-walled carbon nanotubes (MWCNTs). We expect that the proposed method can be easily adapted to the disposal of other refuse materials and applied to MWCNT production industries.

  7. Field emission energy distributions from individual multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Fransen, M. J.; van Rooy, Th. L.; Kruit, P.

    1999-05-01

    We measured field emission energy distributions of electrons emitted from individual multiwalled carbon nanotubes mounted on tungsten tips. The shape of the energy distribution is strongly sample dependent. Some nanotube emitters exhibit an almost metallic behaviour, while others show sharply peaked energy distributions. The smallest half-width we measured was only 0.11 eV, without correction for the broadening of the energy analyzer. A common feature of both types of carbon nanotube energy spectra is that the position of the peaks in the spectrum depends linearly on the extraction voltage, unlike metallic emitters, where the position stays in the vicinity of the Fermi level. With a small modification to the field emission theory for metals we extract the distance between the highest filled energy level of the nanotube and the vacuum potential, the field on the emitter surface, the emitter radius and the emitting area, from the energy distribution and the Fowler-Nordheim plot. The last two parameters are in good agreement with transmission electron micrographs of such samples. The sharply-peaked energy distributions from other samples indicate that resonant states can exist at the top of the nanotube.

  8. Surface modification of multiwall carbon nanotubes by sulfonitric treatment

    NASA Astrophysics Data System (ADS)

    Gómez, Sofía; Rendtorff, Nicolás M.; Aglietti, Esteban F.; Sakka, Yoshio; Suárez, Gustavo

    2016-08-01

    Carbon nanotubes are widely used for electronic, mechanical, and optical devices due to their unique structural and quantum characteristics. The species generated by oxidation on the surface of these materials permit binding new reaction chains, which improves the dispersibility, processing and compatibility with other materials. Even though different acid treatments and applications of these CNT have been reported, relatively few research studies have focused on the relationship between the acid treatment and the formation of nanodefects, specific oxidized species or CNT surface defects. In this work, multiwall carbon nanotube (MWCNT) oxidation at 90 °C was characterized in order to determine the acid treatment effect on the surface. It was found that oxidized species are already present in MWCNT without an acid treatment, but there are not enough to cause water-based dispersion. The species were identified and quantified by infrared spectroscopy and X-ray photoelectron spectroscopy. Also, transmission electron microscopy observations showed not only modifications of the oxidized species, but also morphological damage on the surfaces of MWCNT after being subjected to the acid treatment. This effect was also confirmed by Raman spectroscopy. The acid treatment generates higher oxidized species, decreasing the zeta potential in the whole pH range.

  9. Controlled fabrication of theophylline imprinted polymers on multiwalled carbon nanotubes via atom transfer radical polymerization.

    PubMed

    Xu, Jianxiong; Gao, Yong; Li, Huaming

    2011-02-01

    Theophylline imprinted polymers were synthesized on the surface of multiwalled carbon nanotubes via atom transfer radical polymerization using brominated multiwalled carbon nanotubes as an initiator. The nanotube-based initiator was prepared by directly reacting acyl chloride-modified multiwalled carbon nanotubes with 2-hydroxylethyl-2'-bromoisobutyrate. The grafting copolymerization of 2-hydroxyethyl-2-methyl-2-propenoate and ethylene glycol dimethacrylate in the presence of template theophylline led to thin molecularly imprinted polymer films coating multiwalled carbon nanotubes. The thickness of molecularly imprinted polymer films prepared in this study was about 5 nm as determined by transmission electron microscopy. Fourier-transform infrared spectroscopy was utilized to follow the introduction of initiator groups as well as polymers on the carbon nanotube surfaces. Thermogravimetric analysis indicated that the molecularly imprinted polymers were successfully grown from the carbon nanotube surfaces, with the final products having a polymer weight percentage of ca. 50 wt%. The adsorption properties, such as adsorption dynamics, special binding and selective recognition capacity, of the as-prepared molecularly imprinted polymer films were evaluated. The results demonstrated that the composite of molecularly imprinted polymers and multiwalled carbon nanotubes not only possessed a rapid dynamics but also exhibited a good selectivity toward theophylline, compared to caffeine.

  10. Multi-walled carbon nanotubes with rectangular or square cross-section

    NASA Astrophysics Data System (ADS)

    Mizutani, Kanako; Kohno, Hideo

    2016-06-01

    Multi-walled carbon nanotubes with rectangular or square cross-section are formed. The nanotubes are about 50-200 nm in width, and their walls are around 5-30 nm thick. It is very likely that the rectangular cross-section is shaped simultaneously when nanotubes are formed from catalyst Fe nanoparticles during chemical vapor deposition process, and the shape is stabilized by the bonding between adjoining graphene layers in the multi-walled structure.

  11. Mobility of Multi-walled Carbon Nanotubes in Porous Media

    NASA Astrophysics Data System (ADS)

    O'Carroll, D. M.; Liu, X.; Petersen, E.; Huang, Q.; Anderson, L.

    2007-12-01

    Engineered multi-walled carbon nanotubes (MWCNTs) are the subject of intense research and are expected to gain widespread usage in a broad variety of commercial products. However concerns have been raised regarding their potential environmental and health risks. The mobility of MWCNTs in porous media is examined in this study through one dimensional flow-through column experiments under conditions representative of subsurface and drinking water treatment systems. The goal of this work was to determine dominant MWCNT removal mechanisms and factors that control MWCNT transport. Results demonstrate that pore water velocity strongly influenced MWCNT transport, a result that stands in contrast to traditional colloid filtration theory, which suggests a relatively minor effect of flow velocity in comparison to Brownian diffusion. Experiments conducted at different ionic strengths indicate that both particle deposition and straining are important MWCNT removal mechanisms from the aqueous phase. Given these findings, traditional colloid filtration theory may not be appropriate for the prediction of MWCNT mobility in porous media. This may be due to the large aspect ratio of the MWCNTs and the importance of straining in MWCNT removal.

  12. Impact of source water quality on multiwall carbon nanotube coagulation.

    PubMed

    Holbrook, R David; Kline, Carly N; Filliben, James J

    2010-02-15

    Potable water treatment facilities may become an important barrier in limiting human exposure to engineered nanoparticles (ENPs) as ENPs begin to contaminate natural aquatic systems. Coagulation of ENPs will likely be a major process that controls the ENP fate and the subsequent removal in the aqueous phase. The influence that source water quality has on ENP coagulation is still relatively unknown. The current study uses a 2(3) x 2(4-1) fractional factorial design to identify seven key surface water constituents that affect multiwall carbon nanotube (MWCNT) coagulation. These seven factors include: influent concentrations of kaolin, organic matter (OM), alginate, and MWCNTs; type and dosage of coagulant; and method of MWCNT stabilization. MWCNT removal was most affected by coagulant type and dosage, with alum outperforming ferric chloride at circumneutral pH. None of the other factors were universally significant but instead depended on coagulant type, dose, and method of stabilization. In all cases where factors were found to have a significant impact on MWCNT removal, however, the relationship was consistent: higher influent concentrations of kaolin and alginate improved MWCNT removal while higher influent concentrations of OM hindered MWCNT coagulation. Once MWCNTs are released into the natural environment, their coagulation behavior will be determined by the type and quantity of pollutants (i.e., factors) present in the aquatic environment and are governed by the same mechanisms that influence the colloidal stability of "natural" nanoparticles. PMID:20092299

  13. Functionalized multiwalled carbon nanotubes as ultrasound contrast agents.

    PubMed

    Delogu, Lucia Gemma; Vidili, Gianpaolo; Venturelli, Enrica; Ménard-Moyon, Cécilia; Zoroddu, Maria Antonietta; Pilo, Giovannantonio; Nicolussi, Paola; Ligios, Ciriaco; Bedognetti, Davide; Sgarrella, Francesco; Manetti, Roberto; Bianco, Alberto

    2012-10-01

    Ultrasonography is a fundamental diagnostic imaging tool in everyday clinical practice. Here, we are unique in describing the use of functionalized multiwalled carbon nanotubes (MWCNTs) as hyperechogenic material, suggesting their potential application as ultrasound contrast agents. Initially, we carried out a thorough investigation to assess the echogenic property of the nanotubes in vitro. We demonstrated their long-lasting ultrasound contrast properties. We also showed that ultrasound signal of functionalized MWCNTs is higher than graphene oxide, pristine MWCNTs, and functionalized single-walled CNTs. Qualitatively, the ultrasound signal of CNTs was equal to that of sulfur hexafluoride (SonoVue), a commercially available contrast agent. Then, we found that MWCNTs were highly echogenic in liver and heart through ex vivo experiments using pig as an animal model. In contrast to the majority of ultrasound contrast agents, we observed in a phantom bladder that the tubes can be visualized within a wide variety of frequencies (i.e., 5.5-10 MHz) and 12.5 MHz using tissue harmonic imaging modality. Finally, we demonstrated in vivo in the pig bladder that MWCNTs can be observed at low frequencies, which are appropriate for abdominal organs. Importantly, we did not report any toxicity of CNTs after 7 d from the injection by animal autopsy, organ histology and immunostaining, blood count, and chemical profile. Our results reveal the enormous potential of CNTs as ultrasound contrast agents, giving support for their future applications as theranostic nanoparticles, combining diagnostic and therapeutic modalities.

  14. Preparation and Characterization of PETI-330/Multiwalled Carbon Nanotube Composites

    NASA Technical Reports Server (NTRS)

    Ghose, Sayata; Watson, Kent A.; Working, Dennis C.; Delozier, Donavon M.; Criss, Jim M.; Siochi, Emilie J.; Connell, John W.

    2005-01-01

    As part of an ongoing effort to incorporate multi-functionality into advanced composites, blends of PETI-330 and multi-walled carbon nanotubes (MWCNTs) were prepared, characterized and fabricated into moldings. The PETI-330/MWCNT mixtures were prepared at concentrations ranging from 3 to 25 weight percent by dry mixing the components in a ball mill. The resulting powders were characterized for degree of mixing, thermal and rheological properties. Based on the characterization results, PETI-330/MWCNT samples were scaled up to approx. 300 g and used to fabricate moldings 10.2 cm x 15.2 cm x 0.32 cm thick. The moldings were fabricated by injecting the mixtures at 260-280 C into a stainless steel tool followed by curing for 1 h at 371 C. The tool was designed to impart high shear during the injection process in an attempt to achieve some alignment of the MWCNTs in the flow direction. Good quality moldings were obtained that were subsequently characterized for thermal, mechanical and electrical properties. The degree of dispersion and alignment of the MWCNTs were investigated using high-resolution scanning electron microscopy and Raman spectroscopy. The preparation and preliminary characterization of PETI-330/MWCNT composites will be discussed. Keywords: phenylethynyl terminated imides, high temperature polymers, nanocomposites,

  15. Microbial toxicity of ethanolamines--multiwalled carbon nanotubes.

    PubMed

    Zardini, Hadi Zare; Davarpanah, Morteza; Shanbedi, Mehdi; Amiri, Ahmad; Maghrebi, Morteza; Ebrahimi, Leila

    2014-06-01

    In the present study, antimicrobial activities of multiwalled carbon nanotubes (MWCNTs) functionalized with ethanolamine (EA) groups were investigated. Therefore, MWCNT were first functionalized with mono-, di-, and triethanolamine (MEA, DEA, and TEA) under microwave technique. Development of functional groups on the MWCNT surface was confirmed by Fourier transform infrared and thermogravimetric analysis. Morphological variation was investigated by transmission electron microscopy. Then, antimicrobial activities of pristine and functionalized MWCNT (MWCNT-MEA, -DEA, and -TEA) were tested against different bacteria species. The studies have been done on four Gram-negative bacteria (Escherichia coli, Klebsiella pneumonia, Pseudomonas aeroginosa, and Salmonella typhimurium) as well as four Gram-positive bacteria (Bacillus subtilis, Staphylococcus aureus, Bacillus cereus, and Streptococcus pneumonia). The results based on minimal inhibitory concentration and radial diffusion assay were shown that the antimicrobial activity of MWCNT-TEA > MWCNT-DEA > MWCNT-MEA > pristine MWCNT. Based on the results, it seems that EA groups could play an important role in antimicrobial activity of MWCNT.

  16. Nanoporous silica membranes fabricated using multiwalled carbon nanotubes.

    PubMed

    Kim, Hun-Sik; Kwon, Ha Il; Yun, Young Soo; Bak, Hyeonseong; Yoon, Jin-San; Jin, Hyoung-Joon

    2011-05-01

    Nanoporous silica membranes were fabricated using 3-aminopropyltriethoxysilane (APS) and acyl chloride-functionalized multiwalled carbon nanotubes (MWCNTs). The amine groups of silane reacted with the functional groups (e.g., acid chloride) that were attached to the sidewall of the MWCNTs. The APS that was grafted to the sidewall of the MWCNTs was polymerized in order to coat the MWCNTs wall through heating. The thickness of the silica layer on the surface of the MWCNTs was controlled by adjusting the growth time of the SiO2 layer. Approximately 20 nm-sized pores were formed through the removal of the MWCNTs using a simple thermal process, but some traces of the MWCNTs still remained. The porous properties of the nanoporous silica membrane were analyzed from the nitrogen adsorption-desorption isotherms that were obtained using a surface area and porosimetry analyzer. The structure and composition of the silane-modified MWCNTs were characterized using scanning electron microscopy, energy dispersive spectroscopy and transmission electron microscopy. PMID:21780471

  17. Preparation and Characterization of PETI-330/Multiwalled Carbon Nanotube

    NASA Technical Reports Server (NTRS)

    Ghose, Sayata; Watson, Kent A.; Working, Dennis C.; Criss, Jim M.; Siochi, Emilie J.; Connell, John W.

    2005-01-01

    As part of an ongoing effort to incorporate multifunctionality into advanced composites, blends of PETI-330 and multi-walled carbon nanotubes (MWCNTs) were prepared, characterized and fabricated into moldings. The PETI-330/MWCNT mixtures were prepared at concentrations ranging from 3 to 25 weight percent by dry mixing the components in a ball mill. The resulting powders were characterized for degree of mixing, thermal and rheological properties. Based on the characterization results, PETI-330/MWCNT samples were scaled up to 300 g and used to fabricate moldings 10.2 cm x 15.2 cm x 0.32 cm thick. The moldings were made by injecting the mixtures at 260-280 C into an Invar tool followed by curing for 1 h at 371 C. The tool was designed to impart shear during the injection process in an attempt to achieve some alignment of the MWCNTs in the flow direction. Good quality moldings were obtained that were subsequently characterized for thermal, mechanical and electrical properties. The degree of dispersion and alignment of the MWCNTs were investigated using high-resolution scanning electron microscopy. The preparation and preliminary characterization of PETI-330/MWCNT composites will be discussed. Keywords: phenylethynyl terminated imides, high temperature polymers, nanocomposites, moldings

  18. Nanofluids containing multiwalled carbon nanotubes and their enhanced thermal conductivities

    NASA Astrophysics Data System (ADS)

    Xie, Huaqing; Lee, Hohyun; Youn, Wonjin; Choi, Mansoo

    2003-10-01

    Multiwalled carbon nanotubes (CNTs) as produced are usually entangled and not ready to be dispersed into fluids. We treated CNTs by using a concentrated nitric acid to disentangle CNT aggregates for producing CNT nanofluids. Oxygen-containing functional groups have been introduced on the CNT surfaces and more hydrophilic surfaces have been formed during this treatment, which enabled to make stable and homogeneous CNT nanofluids. Treated CNTs were successfully dispersed into polar liquids like distilled water, ethylene glycol without the need of surfactant and into nonpolar fluid like decene with oleylamine as surfactant. We measured the thermal conductivities of these nanotube suspensions using a transient hot wire apparatus. Nanotube suspensions, containing a small amount of CNTs, have substantially higher thermal conductivities than the base fluids, with the enhancement increasing with the volume fraction of CNTs. For the suspensions with the same loading, the enhanced thermal conductivity ratios are reduced with the increasing thermal conductivity of the base fluid. Comparison between the experimental data and the theoretical model indicates that the thermal conductivities of nanotube suspensions seem to be very dependent on the interfacial layer that exists between the nanotube and the liquid.

  19. Reinforcing multiwall carbon nanotubes by electron beam irradiation

    SciTech Connect

    Duchamp, Martial; Meunier, Richard; Smajda, Rita; Mionic, Marijana; Forro, Laszlo; Magrez, Arnaud; Seo, Jin Won; Song, Bo; Tomanek, David

    2010-10-15

    We study the effect of electron beam irradiation on the bending modulus of multiwall carbon nanotubes grown by chemical vapor deposition. Atomic force microscopy observations of the nanotube deflection in the suspended-beam geometry suggest an internal, reversible stick-slip motion prior to irradiation, indicating presence of extended defects. Upon electron beam irradiation, nanotubes with an initial bending modulus exceeding 10 GPa initially get stiffer, before softening at high doses. Highly defective nanotubes with smaller initial bending moduli do not exhibit the initial reinforcement. These data are explained by ab initio molecular dynamics calculations suggesting a spontaneous cross-linking of neighboring nanotube walls at extended vacancy defects created by the electron beam, in agreement with electron microscopy observations. At low defect concentration, depending on the edge morphology, the covalent bonds between neighboring nanotube walls cause reinforcement by resisting relative motion of neighboring walls. At high concentration of defects that are present initially or induced by high electron beam dose, the structural integrity of the entire system suffers from increasing electron beam damage.

  20. Multi-walled carbon nanotube-based RF antennas.

    PubMed

    Elwi, Taha A; Al-Rizzo, Hussain M; Rucker, Daniel G; Dervishi, Enkeleda; Li, Zhongrui; Biris, Alexandru S

    2010-01-29

    A novel application that utilizes conductive patches composed of purified multi-walled carbon nanotubes (MWCNTs) embedded in a sodium cholate composite thin film to create microstrip antennas operating in the microwave frequency regime is proposed. The MWCNTs are suspended in an adhesive solvent to form a conductive ink that is printed on flexible polymer substrates. The DC conductivity of the printed patches was measured by the four probe technique and the complex relative permittivity was measured by an Agilent E5071B probe. The commercial software package, CST Microwave Studio (MWS), was used to simulate the proposed antennas based on the measured constitutive parameters. An excellent agreement of less than 0.2% difference in resonant frequency is shown. Simulated and measured results were also compared against identical microstrip antennas that utilize copper conducting patches. The proposed MWCNT-based antennas demonstrate a 5.6% to 2.2% increase in bandwidth, with respect to their corresponding copper-based prototypes, without significant degradation in gain and/or far-field radiation patterns.

  1. Surface studies of hydroxylated multi-wall carbon nanotubes

    SciTech Connect

    Bradley, Robert; Cassity, Kelby; Andrews, Rodney; Meier, Mark; Osbeck, Susan; Andreu, Aurik; Johnston, Colin; Crossley, Alison

    2012-01-01

    CVD grown MWCNTs, of typical diameter 5 to 50 nm and with approximately 15-20 concentric graphene layers in the multi-walls, have been surface functionalised using the Fenton hydroxylation reaction. HRTEM reveals little physical difference between the treated and untreated materials; images from both exhibit similar multi-wall structure and contain evidence for some low-level disruption of the very outermost layers. Raman spectra from the two types of nanotubes are almost identical displaying the disorder (D) peaks at approximately 1350 cm{sup -1} and graphite (G) peaks at approximately 1580 cm{sup -1}, characteristic of graphene-based carbon materials, in approximately equal intensity ratios. Equilibrium adsorption data for nitrogen at 77 K leads to BET surface areas of 60.4 m{sup 2} g{sup -1} for the untreated and 71.8 m{sup 2} g{sup -1} for the hydroxylated samples; the increase in area being due to separation of the tube-bundles during functionalization. This is accompanied by a decrease in measured porosity, mostly at high relative pressures of nitrogen, i.e. where larger (meso 2-5 nm and macro >5 nm) pores are being filled, which is consistent with an attendant loss of inter-tube capillarity. X-ray photoelectron spectroscopy (XPS) shows that hydroxylation increases the nanotube surface oxygen level from 4.3 at.% to 22.3 at.%; chemical shift data indicate that approximately 75% of that oxygen is present as hydroxyl (-OH) groups. Water vapour adsorption by the hydroxylated surfaces leads to Type II isotherms which are characteristic of relatively high numbers of hydrogen bonding interactions compared to the untreated materials which exhibit Type III curves. This difference in polar surface energy is confirmed by calorimetric enthalpies of immersion in water which are -54 mJ m{sup -2} for the untreated and -192 mJ m{sup -2} for the hydroxylated materials. The treated materials therefore have significantly increased water wettability/dispersivity and a greater

  2. Mechanical Properties of Individual Composite Poly(methyl-methacrylate) -Multiwalled Carbon Nanotubes Nanofibers

    NASA Astrophysics Data System (ADS)

    Grabbert, Niels; Wang, Bei; Avnon, Asaf; Zhuo, Shuyao; Datsyuk, Vitaliy; Trotsenko, Svitlana; Mackowiak, Piotr; Kaletta, Katrin; Lang, Klaus-Dieter; Ngo, Ha-Duong

    2014-08-01

    Multiwalled carbon nanotubes with their superb mechanical properties are an unique filler material for polymer composites. Here, we present an investigation of mechanical properties of electrospun Poly-(methyl-methacrylate) multiwalled carbon nanotubes composite nanofibers. The method of electrospinning was used to fabricate suspended individual Poly-(methyl-methacrylate) multiwalled carbon nanotubes nanofibers. In order to reinforce the nanofibers, different high concentration of multiwalled carbon nanotubes were used. Transmission electron microscopy measurements reveal a successful filling of the nanofibers. The different types of nanofibers were deposited at SiO2 substrates. Which were previously etched, to create trenches for bend tests. Followed by fixing the nanofiber with a focus ion beam platinum deposition at the trench edges. An atomic force microscopy was used to perform the mechanical nanofiber bending tests over trenches. The results were compared with pristine Poly-(methyl- methacrylate) nanofibers to nanofibers with 15 weight% and 20 weight% multiwalled carbon nanotubes composite fibers. We observed that pristine nanofibers have Young's modulus of 136 MPa, while for composite nanofibers with 15 weight% have 2.65 GPa and with 20 weight% have 6.06 GPa (at room temperature and air ambiance). This corresponds to an increase of Young's modulus of 19 fold between the pristine nanofibers and the 15 weight% of mutliwalled carbon nanotubes filled nanofibers. Therefore the increase of the Young's modulus compared between the pristine and the 20 weight% MWCNT filled nanofibers corresponds to 45 fold.

  3. Multi-walled carbon nanotubes: sampling criteria and aerosol characterization

    PubMed Central

    Chen, Bean T.; Schwegler-Berry, Diane; McKinney, Walter; Stone, Samuel; Cumpston, Jared L.; Friend, Sherri; Porter, Dale W.; Castranova, Vincent; Frazer, David G.

    2015-01-01

    This study intends to develop protocols for sampling and characterizing multi-walled carbon nanotube (MWCNT) aerosols in workplaces or during inhalation studies. Manufactured dry powder containing MWCNT’s, combined with soot and metal catalysts, form complex morphologies and diverse shapes. The aerosols, examined in this study, were produced using an acoustical generator. Representative samples were collected from an exposure chamber using filters and a cascade impactor for microscopic and gravimetric analyses. Results from filters showed that a density of 0.008–0.10 particles per µm2 filter surface provided adequate samples for particle counting and sizing. Microscopic counting indicated that MWCNT’s, resuspended at a concentration of 10 mg/m3, contained 2.7 × 104 particles/cm3. Each particle structure contained an average of 18 nanotubes, resulting in a total of 4.9 × 105 nanotubes/cm3. In addition, fibrous particles within the aerosol had a count median length of 3.04 µm and a width of 100.3 nm, while the isometric particles had a count median diameter of 0.90 µm. A combination of impactor and microscopic measurements established that the mass median aerodynamic diameter of the mixture was 1.5 µm. It was also determined that the mean effective density of well-defined isometric particles was between 0.71 and 0.88 g/cm3, and the mean shape factor of individual nanotubes was between 1.94 and 2.71. The information obtained from this study can be used for designing animal inhalation exposure studies and adopted as guidance for sampling and characterizing MWCNT aerosols in workplaces. The measurement scheme should be relevant for any carbon nanotube aerosol. PMID:23033994

  4. Multiwalled carbon nanotube hybrids as MRI contrast agents.

    PubMed

    Kuźnik, Nikodem; Tomczyk, Mateusz Michał

    2016-01-01

    Magnetic resonance imaging (MRI) is one of the most commonly used tomography techniques in medical diagnosis due to the non-invasive character, the high spatial resolution and the possibility of soft tissue imaging. Contrast agents, such as gadolinium complexes and superparamagnetic iron oxides, are administered to spotlight certain organs and their pathologies. Many new models have been proposed that reduce side effects and required doses of these already clinically approved contrast agents. These new candidates often possess additional functionalities, e.g., the possibility of bioactivation upon action of particular stimuli, thus serving as smart molecular probes, or the coupling with therapeutic agents and therefore combining both a diagnostic and therapeutic role. Nanomaterials have been found to be an excellent scaffold for contrast agents, among which carbon nanotubes offer vast possibilities. The morphology of multiwalled carbon nanotubes (MWCNTs), their magnetic and electronic properties, the possibility of different functionalization and the potential to penetrate cell membranes result in a unique and very attractive candidate for a new MRI contrast agent. In this review we describe the different issues connected with MWCNT hybrids designed for MRI contrast agents, i.e., their synthesis and magnetic and dispersion properties, as well as both in vitro and in vivo behavior, which is important for diagnostic purposes. An introduction to MRI contrast agent theory is elaborated here in order to point to the specific expectations regarding nanomaterials. Finally, we propose a promising, general model of MWCNTs as MRI contrast agent candidates based on the studies presented here and supported by appropriate theories.

  5. Multiwalled carbon nanotube hybrids as MRI contrast agents

    PubMed Central

    Tomczyk, Mateusz Michał

    2016-01-01

    Summary Magnetic resonance imaging (MRI) is one of the most commonly used tomography techniques in medical diagnosis due to the non-invasive character, the high spatial resolution and the possibility of soft tissue imaging. Contrast agents, such as gadolinium complexes and superparamagnetic iron oxides, are administered to spotlight certain organs and their pathologies. Many new models have been proposed that reduce side effects and required doses of these already clinically approved contrast agents. These new candidates often possess additional functionalities, e.g., the possibility of bioactivation upon action of particular stimuli, thus serving as smart molecular probes, or the coupling with therapeutic agents and therefore combining both a diagnostic and therapeutic role. Nanomaterials have been found to be an excellent scaffold for contrast agents, among which carbon nanotubes offer vast possibilities. The morphology of multiwalled carbon nanotubes (MWCNTs), their magnetic and electronic properties, the possibility of different functionalization and the potential to penetrate cell membranes result in a unique and very attractive candidate for a new MRI contrast agent. In this review we describe the different issues connected with MWCNT hybrids designed for MRI contrast agents, i.e., their synthesis and magnetic and dispersion properties, as well as both in vitro and in vivo behavior, which is important for diagnostic purposes. An introduction to MRI contrast agent theory is elaborated here in order to point to the specific expectations regarding nanomaterials. Finally, we propose a promising, general model of MWCNTs as MRI contrast agent candidates based on the studies presented here and supported by appropriate theories. PMID:27547627

  6. Multiwalled carbon nanotube hybrids as MRI contrast agents.

    PubMed

    Kuźnik, Nikodem; Tomczyk, Mateusz Michał

    2016-01-01

    Magnetic resonance imaging (MRI) is one of the most commonly used tomography techniques in medical diagnosis due to the non-invasive character, the high spatial resolution and the possibility of soft tissue imaging. Contrast agents, such as gadolinium complexes and superparamagnetic iron oxides, are administered to spotlight certain organs and their pathologies. Many new models have been proposed that reduce side effects and required doses of these already clinically approved contrast agents. These new candidates often possess additional functionalities, e.g., the possibility of bioactivation upon action of particular stimuli, thus serving as smart molecular probes, or the coupling with therapeutic agents and therefore combining both a diagnostic and therapeutic role. Nanomaterials have been found to be an excellent scaffold for contrast agents, among which carbon nanotubes offer vast possibilities. The morphology of multiwalled carbon nanotubes (MWCNTs), their magnetic and electronic properties, the possibility of different functionalization and the potential to penetrate cell membranes result in a unique and very attractive candidate for a new MRI contrast agent. In this review we describe the different issues connected with MWCNT hybrids designed for MRI contrast agents, i.e., their synthesis and magnetic and dispersion properties, as well as both in vitro and in vivo behavior, which is important for diagnostic purposes. An introduction to MRI contrast agent theory is elaborated here in order to point to the specific expectations regarding nanomaterials. Finally, we propose a promising, general model of MWCNTs as MRI contrast agent candidates based on the studies presented here and supported by appropriate theories. PMID:27547627

  7. Electrical Conductivity in Polymer Blends/ Multiwall Carbon Nanotubes

    SciTech Connect

    Kulkarni, Ajit R.; Bose, Suryasarathi; Bhattacharyya, Arup R.

    2008-10-23

    Carbon nanotubes (CNT) based polymer composites have emerged as the future multifunctional materials in view of its exceptional mechanical, thermal and electrical properties. One of the major interests is to develop conductive polymer composites preferably at low concentration of CNT utilizing their high aspect ratio (L/D) for numerous applications, which include antistatic devices, capacitors and materials for EMI shielding. In this context, polymer blends have emerged as a potential candidate in lowering the percolation thresholds further by the utilization of 'double-percolation' which arises from the synergistic improvements in blend properties associated with the co-continuous morphology. Due to strong inter-tube van der Waals' forces, they often tend to aggregate and uniform dispersion remains a challenge. To overcome this challenge, we exploited sodium salt of 6-aminohexanoic acid (Na-AHA) which was able to assist in debundlling the multiwall carbon nanotubes (MWNT) through 'cation-{pi}' interactions during melt-mixing leading to percolative 'network-like' structure of MWNT within polyamide6 (PA6) phase in co-continuous PA6/acrylonitrile butadiene styrene (ABS) blends. The composite exhibited low electrical percolation thresholds of 0.25 wt% of MWNT, the lowest reported value in this system so far. Retention of 'network-like structure' in the solid state with significant refinement was observed even at lower MWNT concentration in presence Na-AHA, which was assessed through AC electrical conductivity measurements. Reactive coupling was found to be a dominant factor besides 'cation-{pi}' interactions in achieving low electrical percolation in PA6/ABS+MWNT composites.

  8. Blood biocompatibility of surface-bound multi-walled carbon nanotubes.

    PubMed

    Gaffney, Alan M; Santos-Martinez, Maria J; Satti, Amro; Major, Terry C; Wynne, Kieran J; Gun'ko, Yurii K; Annich, Gail M; Elia, Giuliano; Radomski, Marek W

    2015-01-01

    Blood clots when it contacts foreign surfaces following platelet activation. This can be catastrophic in clinical settings involving extracorporeal circulation such as during heart-lung bypass where blood is circulated in polyvinyl chloride tubing. Studies have shown, however, that surface-bound carbon nanotubes may prevent platelet activation, the initiator of thrombosis. We studied the blood biocompatibility of polyvinyl chloride, surface-modified with multi-walled carbon nanotubes in vitro and in vivo. Our results show that surface-bound multi-walled carbon nanotubes cause platelet activation in vitro and devastating thrombosis in an in vivo animal model of extracorporeal circulation. The mechanism of the pro-thrombotic effect likely involves direct multi-walled carbon nanotube-platelet interaction with Ca(2+)-dependant platelet activation. These experiments provide evidence, for the first time, that modification of surfaces with nanomaterials modulates blood biocompatibility in extracorporeal circulation.

  9. Effect of doping of multi-walled carbon nanotubes on phenolic based carbon fiber reinforced nanocomposites

    NASA Astrophysics Data System (ADS)

    Saeed, Sadaf; Hakeem, Saira; Faheem, Muhammad; Alvi, Rashid Ahmed; Farooq, Khawar; Tajammul Hussain, Syed; Nisar Ahmad, Shahid

    2013-06-01

    We report on the effect of multi-walled carbon nanotubes (MWCNTs) on different properties of phenolic resin. A low content of MWCNTs (~ 0.05 wt%) was mixed in phenolic resin and a stable dispersion was achieved by ultrasonication, followed by melt mixing. After curing the characterization of these composites was done by using scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and Fourier transform infra-red spectroscopy (FTIR). The thermal and ablative properties of carbon fiber reinforced MWCNTs-phenolic nanocomposites were also studied. The addition of MWCNTs showed improvement in thermal stability and ablation properties.

  10. The effects of multi-walled carbon nanotubes on soil microbial community functional and structural diversity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Applications of nanomaterials, including carbon nanotubes (CNTs), are increasing; however, their impact on the environment is still not well understood. A semi-arid soil was treated with multi-walled carbon nanotubes (MWCNTs) at four different concentrations (10-10000 mgMWCNTs kg-1soil), and incubat...

  11. Functionalized multi-walled carbon nanotubes in an aldol reaction

    NASA Astrophysics Data System (ADS)

    Chronopoulos, D. D.; Kokotos, C. G.; Karousis, N.; Kokotos, G.; Tagmatarchis, N.

    2015-01-01

    The covalent functionalization of multi-walled carbon nanotubes (MWCNTs) with a proline-based derivative is reported. Initially, MWCNTs were oxidized in order to introduce a large number of carboxylic units on their tips followed by N-tert-butoxycarbonyl-2,2'(ethylenedioxy)bis-(ethylamine) conjugation through an amide bond. Then, a proline derivative bearing a carboxylic terminal moiety at the 4-position was coupled furnishing proline-modified MWCNTs. This new hybrid material was fully characterized by spectroscopic and microscopy means and its catalytic activity in the asymmetric aldol reaction between acetone and 4-nitrobenzaldehyde was evaluated for the first time, showing to proceed almost quantitatively in aqueous media. Furthermore, several amino-modified MWCNTs were prepared and examined in the particular aldol reaction. These new hybrid materials exhibited an enhanced catalytic activity in water, contrasting with the pristine MWCNTs as well as the parent organic molecule, which failed to catalyze the reaction efficiently. Furthermore, the modified MWCNTs proved to catalyze the aldol reaction even after three repetitive cycles. Overall, a green approach for the aldol reaction is presented, where water can be employed as the solvent and modified MWCNTs can be used as catalysts, which can be successfully recovered and reused, while their catalytic activity is retained.The covalent functionalization of multi-walled carbon nanotubes (MWCNTs) with a proline-based derivative is reported. Initially, MWCNTs were oxidized in order to introduce a large number of carboxylic units on their tips followed by N-tert-butoxycarbonyl-2,2'(ethylenedioxy)bis-(ethylamine) conjugation through an amide bond. Then, a proline derivative bearing a carboxylic terminal moiety at the 4-position was coupled furnishing proline-modified MWCNTs. This new hybrid material was fully characterized by spectroscopic and microscopy means and its catalytic activity in the asymmetric aldol reaction

  12. 40 CFR 721.10277 - Single-walled and multi-walled carbon nanotubes (generic) (P-10-40).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... chemical substance identified generically as single-walled and multi-walled carbon nanotubes (PMN P-10-40... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Single-walled and multi-walled carbon nanotubes (generic) (P-10-40). 721.10277 Section 721.10277 Protection of Environment...

  13. 75 FR 44198 - Proposed Significant New Use Rule for Multi-walled Carbon Nanotubes; Reopening of Comment Period

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-28

    ... public comment period established in the Federal Register of February 3, 2010 (75 FR 5546) (FRL-8796-7... AGENCY 40 CFR Part 721 RIN 2070-AB27 Proposed Significant New Use Rule for Multi-walled Carbon Nanotubes... multi-walled carbon nanotubes (P-08-199). In order to address public comments, EPA is adding...

  14. Synthetic Gecko Foot-hairs from Multiwalled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Dhinojwala, Ali

    2006-03-01

    The mechanism that allows a gecko lizard to climb any vertical surface and hang from a ceiling with one toe has attracted considerable interest and awe for over two millennia. Recent studies have discovered that the gecko's ability to defy gravity comes from its remarkable feet and toes. Each five-toed foot is covered with microscopic elastic hairs called setae. The ends of these hairs split into spatulas which come in contact with the surface and induce enough intermolecular [van der Waals, (VdW)] forces to hold them in place. Similarly, the same VdW forces act between our two hands when they are held together, but in this case, they do not stick to each other. The reason is that the roughness of our hands prevents them from coming close to each other at separations relevant for VdW forces. On the other hand, based on the gecko's foot anatomy, if our hands were made up of tiny elastic structures that were able to deform or bend at different length scales in accordance with the contact surface and correct for the roughness, then perhaps our hands could also adhere to the surfaces we touch. In my talk, I will present the recent advances we have made in fabricating polymer surfaces with multiwalled carbon nanotube hairs with strong nanometer-level adhesion forces that are 200 times higher than those observed for Gecko foot-hairs. This fabrication process allows the flexibility to create structures that are found in nature on the Gecko's foot and offer excellent potential for applications as dry adhesives for space, microelectronics and MEMS devices. This work was done in collaboration with Betul Yurdumakan, Nachiket Raravikar and Pulickel Ajayan.

  15. Nanostructured copper phthalocyanine-sensitized multiwall carbon nanotube films.

    PubMed

    Hatton, Ross A; Blanchard, Nicholas P; Stolojan, Vlad; Miller, Anthony J; Silva, S Ravi P

    2007-05-22

    We report a detailed study of the interaction between surface-oxidized multiwall carbon nanotubes (o-MWCNTs) and the molecular semiconductor tetrasulfonate copper phthalocyanine (TS-CuPc). Concentrated dispersions of o-MWCNT in aqueous solutions of TS-CuPc are stable toward nanotube flocculation and exhibit spontaneous nanostructuring upon rapid drying. In addition to hydrogen-bonding interactions, the compatibility between the two components is shown to result from a ground-state charge-transfer interaction with partial charge transfer from o-MWCNT to TS-CuPc molecules orientated such that the plane of the macrocycle is parallel to the nanotube surface. The electronegativity of TS-CuPc as compared to unsubsubtituted copper phthalocyanine is shown to result from the electron-withdrawing character of the sulfonate substituents, which increase the molecular ionization potential and promote cofacial molecular aggregation upon drying. Upon spin casting to form uniform thin films, the experimental evidence is consistent with an o-MWCNT scaffold decorated with phthalocyanine molecules self-assembled into extended aggregates reminiscent of 1-D linearly stacked phthalocyanine polymers. Remarkably, this self-organization occurs in a fraction of a second during the spin-coating process. To demonstrate the potential utility of this hybrid material, it is successfully incorporated into a model organic photovoltaic cell at the interface between a poly(3-hexylthiophene):[6,6]-phenyl-C61 butyric acid methyl ester bulk heterojunction layer and an indium-tin oxide-coated glass electrode to increase the light-harvesting capability of the device and facilitate hole extraction. The resulting enhancement in power conversion efficiency is rationalized in terms of the electronic, optical, and morphological properties of the nanostructured thin film. PMID:17439261

  16. Nanostructured copper phthalocyanine-sensitized multiwall carbon nanotube films.

    PubMed

    Hatton, Ross A; Blanchard, Nicholas P; Stolojan, Vlad; Miller, Anthony J; Silva, S Ravi P

    2007-05-22

    We report a detailed study of the interaction between surface-oxidized multiwall carbon nanotubes (o-MWCNTs) and the molecular semiconductor tetrasulfonate copper phthalocyanine (TS-CuPc). Concentrated dispersions of o-MWCNT in aqueous solutions of TS-CuPc are stable toward nanotube flocculation and exhibit spontaneous nanostructuring upon rapid drying. In addition to hydrogen-bonding interactions, the compatibility between the two components is shown to result from a ground-state charge-transfer interaction with partial charge transfer from o-MWCNT to TS-CuPc molecules orientated such that the plane of the macrocycle is parallel to the nanotube surface. The electronegativity of TS-CuPc as compared to unsubsubtituted copper phthalocyanine is shown to result from the electron-withdrawing character of the sulfonate substituents, which increase the molecular ionization potential and promote cofacial molecular aggregation upon drying. Upon spin casting to form uniform thin films, the experimental evidence is consistent with an o-MWCNT scaffold decorated with phthalocyanine molecules self-assembled into extended aggregates reminiscent of 1-D linearly stacked phthalocyanine polymers. Remarkably, this self-organization occurs in a fraction of a second during the spin-coating process. To demonstrate the potential utility of this hybrid material, it is successfully incorporated into a model organic photovoltaic cell at the interface between a poly(3-hexylthiophene):[6,6]-phenyl-C61 butyric acid methyl ester bulk heterojunction layer and an indium-tin oxide-coated glass electrode to increase the light-harvesting capability of the device and facilitate hole extraction. The resulting enhancement in power conversion efficiency is rationalized in terms of the electronic, optical, and morphological properties of the nanostructured thin film.

  17. The hepatotoxicity of multi-walled carbon nanotubes in mice

    NASA Astrophysics Data System (ADS)

    Ji, Zongfei; Zhang, Danying; Li, Ling; Shen, Xizhong; Deng, Xiaoyong; Dong, Ling; Wu, Minhong; Liu, Yuanfang

    2009-11-01

    The hepatotoxicity of two types of multi-walled carbon nanotubes (MWCNTs), acid-oxidized MWCNTs (O-MWCNTs) and Tween-80-dispersed MWCNTs (T-MWCNTs), were investigated with Kunming mice exposed to 10 and 60 mg kg-1 by intravenous injection for 15 and 60 d. Compared with the PBS group, the body-weight gain of the mice decreased and the level of total bilirubin and aspartate aminotransferase increased in the MWCNT-exposed group with a significant dose-effect relationship, while tumor necrosis factor alpha level did not show significant statistical change within 60 d. Spotty necrosis, inflammatory cell infiltration in portal region, hepatocyte mitochondria swelling and lysis were observed with a significant dose-effect relationship in the MWCNT groups. Liver damage of the T-MWCNT group was more severe than that of the O-MWCNT group according to the Roenigk classification system. Furthermore, T-MWCNTs induce slight liver oxidative damage in mice at 15 d, which was recovered at 60 d. Part of the gene expressions of mouse liver in the MWCNT groups changed compared to the PBS group, including GPCRs (G protein-coupled receptors), cholesterol biosynthesis, metabolism by cytochrome P450, natural-killer-cell-mediated cytotoxicity, TNF- α, NF-κB signaling pathway, etc. In the P450 pathway, the gene expressions of Gsta2 (down-regulated), Cyp2B19 (up-regulated) and Cyp2C50 (down-regulated) had significant changes in the MWCNT groups. These results show that a high dose of T-MWCNTs can induce hepatic toxicity in mice while O-MWCNTs seem to have less toxicity.

  18. Inducing injection barrier by covalent functionalization of multiwall carbon nanotubes acting as Moiré crystals

    NASA Astrophysics Data System (ADS)

    Bonnet, Roméo; Barraud, Clément; Martin, Pascal; Della Rocca, Maria Luisa; Lafarge, Philippe

    2016-10-01

    Covalent functionalization of multiwall carbon nanotubes is a direct method to suppress the conduction of the outermost shell, subject to interactions with the environment. The rehybridized sp3 external shell of the functionalized multiwall carbon nanotubes becomes naturally a hybrid injection barrier allowing the control of the contact resistances and the study of quantum transport in the more protected inner shells. Charge transport measurements performed on isolated multiwall carbon nanotubes of large diameter show an increase of the contact resistance and stabilization in the MΩ range. Electronic quantum properties of the inner shells are highlighted by the observation of superlattice structures in the conductance, recently attributed to the formation of a one-dimensional Moiré pattern.

  19. 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.

  20. Evaluation of Fibrogenic Potential of Industrial Multi-Walled Carbon Nanotubes in Acute Aspiration Experiment

    PubMed Central

    Khaliullin, T. O.; Shvedova, A. A.; Kisin, E. R.; Zalyalov, R. R.; Fatkhutdinova, L. M.

    2015-01-01

    Local inflammatory response in the lungs and fibrogenic potential of multi-walled carbon nanotubes were studied in an acute aspiration experiment in mice. The doses were chosen based on the concentration of nanotubes in the air at a workplace of the company-producer. ELISA, flow cytometry, enhanced darkfield microscopy, and histological examination showed that multi-walled carbon nanotubes induced local inflammation, oxidative stress, and connective tissue growth (fibrosis). Serum levels of TGF-β1 and osteopontin proteins can serve as potential exposure biomarkers. PMID:25778660

  1. Structural and electrical properties of functionalized multiwalled carbon nanotube/epoxy composite

    NASA Astrophysics Data System (ADS)

    Gantayat, S.; Rout, D.; Swain, S. K.

    2016-05-01

    The effect of the functionalization of multiwalled carbon nanotube on the structure and electrical properties of composites was investigated. Samples based on epoxy resin with different weight percentage of MWCNTs were prepared and characterized. The interaction between MWCNT & epoxy resin was noticed by Fourier transform infrared spectroscopy (FTIR). The structure of functionalized multiwalled carbon nanotube (f-MWCNT) reinforced epoxy composite was studied by field emission scanning electron microscope (FESEM). The dispersion of f-MWCNT in epoxy resin was evidenced by high resolution transmission electron microscope (HRTEM). Electrical properties of epoxy/f-MWCNT nanocomposites were measured & the result indicated that the conductivity increased with increasing concentration of f-MWCNTs.

  2. Determination of multi-walled carbon nanotube bioaccumulation in earthworms measured by a microwave-based detection technique

    EPA Science Inventory

    Reliable quantification techniques for carbon nanotubes (CNTs) are limited. In this study, a new procedure was developed for quantifying multi-walled carbon nanotubes (MWNTs) in earthworms (Eisenia fetida) based on freeze drying and microwave-induced heating. Specifically, earthw...

  3. The genotype-dependent influence of functionalized multiwalled carbon nanotubes on fetal development.

    PubMed

    Huang, Xinglu; Zhang, Fan; Sun, Xiaolian; Choi, Ki-Young; Niu, Gang; Zhang, Guofeng; Guo, Jinxia; Lee, Seulki; Chen, Xiaoyuan

    2014-01-01

    In many cases cancer is caused by gene deficiency that is being passed along from generation to generation. Soluble carbon nanotubes (CNTs) have shown promising applications in the diagnosis and therapy of cancer, however, the potential relationship between cancer-prone individuals and response to CNT exposure as a prerequisite for development of personalized nanomedicine, is still poorly understood. Here we report that intravenous injections of multi-walled carbon nanotubes into p53 (a well-known cancer-susceptible gene) heterozygous pregnant mice can induce p53- dependent responses in fetal development. Larger sized multi-walled carbon nanotubes moved across the blood-placenta barrier (BPB), restricted the development of fetuses, and induced brain deformity, whereas single-walled and smaller sized multi-walled carbon nanotubes showed no or less fetotoxicity. A molecular mechanism study found that multi-walled carbon nanotubes directly triggered p53-dependent apoptosis and cell cycle arrest in response to DNA damage. Based on the molecular mechanism, we also incorporated N-acetylcysteine (NAC), an FDA approved antioxidant, to prevent CNTs induced nuclear DNA damage and reduce brain development abnormalities. Our findings suggest that CNTs might have genetic background-dependent toxic effect on the normal development of the embryo, and provide new insights into protection against nanoparticle-induced toxicity in potential clinical applications.

  4. The genotype-dependent influence of functionalized multiwalled carbon nanotubes on fetal development.

    PubMed

    Huang, Xinglu; Zhang, Fan; Sun, Xiaolian; Choi, Ki-Young; Niu, Gang; Zhang, Guofeng; Guo, Jinxia; Lee, Seulki; Chen, Xiaoyuan

    2014-01-01

    In many cases cancer is caused by gene deficiency that is being passed along from generation to generation. Soluble carbon nanotubes (CNTs) have shown promising applications in the diagnosis and therapy of cancer, however, the potential relationship between cancer-prone individuals and response to CNT exposure as a prerequisite for development of personalized nanomedicine, is still poorly understood. Here we report that intravenous injections of multi-walled carbon nanotubes into p53 (a well-known cancer-susceptible gene) heterozygous pregnant mice can induce p53- dependent responses in fetal development. Larger sized multi-walled carbon nanotubes moved across the blood-placenta barrier (BPB), restricted the development of fetuses, and induced brain deformity, whereas single-walled and smaller sized multi-walled carbon nanotubes showed no or less fetotoxicity. A molecular mechanism study found that multi-walled carbon nanotubes directly triggered p53-dependent apoptosis and cell cycle arrest in response to DNA damage. Based on the molecular mechanism, we also incorporated N-acetylcysteine (NAC), an FDA approved antioxidant, to prevent CNTs induced nuclear DNA damage and reduce brain development abnormalities. Our findings suggest that CNTs might have genetic background-dependent toxic effect on the normal development of the embryo, and provide new insights into protection against nanoparticle-induced toxicity in potential clinical applications. PMID:24344357

  5. Multiwalled carbon nanotube CVD synthesis, modification, and composite applications

    NASA Astrophysics Data System (ADS)

    Qian, Dali

    Well-aligned carbon multiwall nanotube (MWNT) arrays have been continuously synthesized by a floating catalytic chemical vapor deposition (CVD) method involving the pyrolysis of xylene-ferrocene mixtures. The CVD parameters have been studied to selectively synthesize nanotubes with required dimensions. A mixed tip-root growth model has been proposed for the floating catalytic CVD synthesis. Coarsening of the catalyst particle at the root end promoted MWNT wall coarsening (addition of new concentric graphene shells), while the smaller catalyst particle at the tip contributed to MWNT elongation. A two-step process in which ferrocene was fed for only five minutes to nucleate the DTs was developed to understand if a continuous supply of catalyst was necessary for continued growth. The results show that the ferrocene was only necessary for initial nucleation. To simplify the CVD process further, another two-step synthesis method was developed in which the ferrocene was pre-decomposed so that the nanotube nucleation could be isolated from the growth, enabling quantification of growth mechanisms and kinetics. Mass spectra and hydrocarbon analyses of the CVD reactor tail gas were performed to understand the pyrolysis chemistry. Well-aligned N-doped and Ru-doped MWNT arrays have been produced by pyrolysis of pyridine ferrocene mixtures and xylene-ferrocene-ruthenocene mixtures, respectively. Various material characterization techniques were used to measure the dopant distributions and correlate the catalyst phase with the novel nanotube structures. High-temperature annealing has been shown to be a viable means to remove both the catalyst particles and certain microstructural defects within the CVD-derived DTs. The phase transformation of catalyst during annealing has also been studied. Homogeneous distribution of MWNTs in polystyrene matrices was achieved by an ultrasonic assisted solution-evaporation method. Addition of only 1 wt % DTs to polystyrene increased the polymer

  6. Infrared photoluminescence of composite films containing quasi-isolated multiwalled carbon nanotubes and carbon nanoshells.

    PubMed

    Reyes-Reyes, M; Segura-Cardenas, E; Gorbatchev, A Yu; López-Sandoval, R

    2010-07-01

    Films of small irregular-shaped aggregates composed by several layers of turbostratic graphite encapsulating iron nanoparticles, like carbon nanoshells, and quasi-isolated multi-walled carbon nanotubes (MWCNTs), were synthesized by the chemical vapor deposition method on glass substrates. Quasi-isolated MWCNTs were found emerging in different directions on the agglomerates composed of carbon nanoshells. The morphological properties of the films were characterized using scanning electron microscopy, high-resolution transmission electron microscopy and Raman spectroscopy, whereas their optical properties were investigated using optical absorption and photoluminescence (PL) spectroscopy. The studies show a high-intensity PL signal in the infrared at room temperature. This PL signal shows several peaks, which cannot be explained by a blackbody emission. However, the overall PL signal could be a combination of the black emission and electronic transitions. Furthermore, the observed infrared PL emission could be ideal for potential applications such as in gas sensors, infrared detectors and so on. PMID:21128424

  7. Nitrogen-doped, boron-doped and undoped multiwalled carbon nanotube/polymer composites in WORM memory devices.

    PubMed

    Mamo, Messai A; Sustaita, Alan O; Tetana, Zikhona N; Coville, Neil J; Hümmelgen, Ivo A

    2013-03-29

    We report the preparation of write-once-read-many times memory devices using composites of carbon nanotubes and poly(vinyl phenol) sandwiched between Al electrodes. Three types of nanotubes (undoped multiwalled carbon nanotubes, nitrogen-doped multiwalled carbon nanotubes and boron-doped multiwalled carbon nanotubes) are investigated for this application. The OFF to ON state switching threshold is only slightly dependent on nanotube type, but the ON/OFF current ratio depends on both nanotube type and concentration and varies up to 10(6), decreasing for nanotube concentrations larger than 0.50 wt% in the composite.

  8. Nitrogen-doped, boron-doped and undoped multiwalled carbon nanotube/polymer composites in WORM memory devices

    NASA Astrophysics Data System (ADS)

    Mamo, Messai A.; Sustaita, Alan O.; Tetana, Zikhona N.; Coville, Neil J.; Hümmelgen, Ivo A.

    2013-03-01

    We report the preparation of write-once-read-many times memory devices using composites of carbon nanotubes and poly(vinyl phenol) sandwiched between Al electrodes. Three types of nanotubes (undoped multiwalled carbon nanotubes, nitrogen-doped multiwalled carbon nanotubes and boron-doped multiwalled carbon nanotubes) are investigated for this application. The OFF to ON state switching threshold is only slightly dependent on nanotube type, but the ON/OFF current ratio depends on both nanotube type and concentration and varies up to 106, decreasing for nanotube concentrations larger than 0.50 wt% in the composite.

  9. Comprehensive Environmental Assessment Applied to Multiwalled Carbon Nanotube Flame-Retardant Coatings in Upholstery Textiles: A Case Study Presenting Priority Research Gaps for Future Risk Assessments (Final Report)

    EPA Science Inventory

    multiwalled_cover.jpg" alt="Cover of the Multiwalled Carbon Nanotube Case Study Final Report" vspace = "5" hspace="5" align="right" border="1" /> This final report presents a case study of multiwalled carbon nanotube...

  10. A Comparative Study on AC Conductivity and Dielectric Behavior of Multiwalled Carbon Nanotubes and Polyaniline Coated Multiwalled Carbon Nanotubes Filled High Density Polyethylene-Carbon Black Nanocomposites

    SciTech Connect

    Dinesh, P.; Renukappa, N. M.; Siddaramaiah; Lee, J. H.; Jeevananda, T.

    2010-10-04

    This paper presents an experimental investigation on AC conductivity and dielectric behavior of carbon black reinforced high density polyethylene (HDPE-CB) and HDPE-CB filled with multiwalled carbon nanotubes (MWNTs-CB-HDPE) and Polyaniline (PAni) coated MWNTs-CB-HDPE nanocomposites. The electrical properties such as dielectric constant ({epsilon}'), dissipation factor (tan {delta}) and AC conductivity ({sigma}{sub ac}) of nanocomposites have been measured with reference to the weight fraction (0.5 and 1 wt% MWNTs), frequency (75 KHz-30 MHz), temperature (25-90 deg. C) and sea water ageing. The experimental results showed that the increased AC conductivity and dielectric constant of the nanocomposites were influenced by PAni coated MWNTs in HDPE-CB nanocomposites. The value of dielectric constant and tan {delta} decreased with increasing frequency. Further more, above 5 MHz the AC conductivity increases drastically whereas significant effect on tan {delta} was observed in less than 1 MHz.

  11. 40 CFR 721.10279 - Multi-walled carbon nanotubes (generic) (P-10-246).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10279 Multi-walled carbon nanotubes (generic) (P-10-246). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified...

  12. Enhanced sensing of NH3 gas by decorated multiwalled carbon nanotube

    NASA Astrophysics Data System (ADS)

    Hasnahena, S. T.; Satpati, Biswarup; Roy, Madhusudan

    2016-05-01

    The present study describes synthesis of Barium Oxide Nanoparticles decorated Multiwalled Carbon Nanotubes and its gas sensing behavior towards NH3 and CO gases. The decorated MWCNT sensor has an enhanced sensing towards NH3 gas compare to pure MWCNT sensor and also has much reduced response and recovery time. The prepared sensing material is characterized by TEM, XRD and Thermal Gravimetric analysis.

  13. Fabrication of high-performance flexible alkaline batteries by implementing multiwalled carbon nanotubes and copolymer separator.

    PubMed

    Wang, Zhiqian; Wu, Zheqiong; Bramnik, Natalia; Mitra, Somenath

    2014-02-12

    A flexible alkaline battery with multiwalled carbon nanotube (MWCNT) enhanced composite electrodes and polyvinyl alcohol (PVA)-poly (acrylic acid) (PAA) copolymer separator has been developed. Purified MWCNTs appear to be the most effective conductive additive, while the flexible copolymer separator not only enhances flexibility but also serves as electrolyte storage. PMID:24510667

  14. Limited transport of functionalized multi-walled carbon nanotubes in two natural soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Column experiments were conducted in undisturbed and in repacked soil columns at water contents close to saturation (85–96%) to investigate the transport and retention of functionalized 14C-labeled multi-walled carbon nanotubes (MWCNT) in two natural soils. Additionally, a field lysimeter experiment...

  15. Activity of site-specific endonucleases on complexes of plasmid DNA with multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Egorova, V. P.; Krylova, H. V.; Lipnevich, I. V.; Veligura, A. A.; Shulitsky, B. G.; Asayonok, A. A.; Vaskovtsev, E. V.

    2016-08-01

    We have synthesized and investigated structural and functional properties of plasmid DNA complexes with multi-walled carbon nanotubes (MWCNTs) for detection of changes in structural state of the plasmid DNA at its recognition by site-specific endonuclease. It has been also established that the site-specific endonuclease is functionally active on the surface of MWCNTs.

  16. Planar gas chromatography column on aluminum plate with multi-walled carbon nanotubes as stationary phase

    NASA Astrophysics Data System (ADS)

    Platonov, I. A.; Platonov, V. I.; Pavelyev, V. S.

    2016-04-01

    The high selectivity of the adsorption layer for low-boiling alkanes is shown, the separation factor (α) couple iso-butane / butane is 1.9 at a column temperature of 50 °C.The paper presents sorption and selective properties of planar gas chromatography column on aluminum plate with multi-walled carbon nanotubes as the stationary phase.

  17. Fast preparation of hydroxyapatite/superhydrophilic vertically aligned multiwalled carbon nanotube composites for bioactive application.

    PubMed

    Lobo, Anderson O; Corat, Marcus A F; Ramos, Sandra C; Matsushima, Jorge T; Granato, Alessandro E C; Pacheco-Soares, Cristina; Corat, Evaldo J

    2010-12-01

    A method for the electrodeposition of hydroxyapatite films on superhydrophilic vertically aligned multiwalled carbon nanotubes is presented. The formation of a thin homogeneous film with high crystallinity was observed without any thermal treatment and with bioactivity properties that accelerate the in vitro biomineralization process and osteoblast adhesion.

  18. A Multi-Walled Carbon Nanotube-based Biosensor for Monitoring Microcystin-LR in Sources of Drinking Water Supplies

    EPA Science Inventory

    A multi-walled carbon nanotube-based electrochemical biosensor is developed for monitoring microcystin-LR (MC-LR), a toxic cyanobacterial toxin, in sources of drinking water supplies. The biosensor electrodes are fabricated using dense, mm-long multi-walled CNT (MWCNT) arrays gro...

  19. Phosphorylated multiwalled carbon nanotube-cyclodextrin polymer: synthesis, characterisation and potential application in water purification.

    PubMed

    Mamba, G; Mbianda, X Y; Govender, P P

    2013-10-15

    Multiwalled carbon nanotubes were synthesised by the nebulised spray pyrolysis method and purified to remove amorphous carbon and fullerenes. The purified multiwalled carbon nanotubes were oxidised using a 3:1 H2SO4/HNO3 mixture to introduce carboxylic groups and to a smaller extent hydroxyl groups on the walls of the carbon nanotubes. Subsequently, the oxidised carbon nanotubes were chlorinated using oxalyl chloride to generate acyl chloride groups through which phosphorylation took place. 4-Aminophenyl methylphosphonate was attached to the multiwalled carbon nanotubes via an amidation reaction. FT-IR and XPS confirmed the presence of PO, PO and PCP functional groups in the phosphorylated carbon nanotubes. Polymerisation of the phosphorylated carbon nanotubes with cyclodextrins was achieved using hexamethylene diisocyanate as a bifunctional linker. Surface morphology of the polymer was investigated by SEM while FT-IR was used to confirm the polymerisation reaction. Moreover, the thermal stability of the polymer was probed using TGA while BET was employed to determine the surface area and pore volume of the polymer. Furthermore, the polymer was tested for the removal of cobalt and 4-chlorophenol from synthetic aqueous solutions of the pollutants. The polymer displayed potential as an adsorbent for both cobalt and 4-chlorophenol.

  20. In situ tuning and probing the ambipolar field effect on multiwall carbon nanotubes

    SciTech Connect

    Chen, Li-Ying; Chang, Chia-Seng

    2014-12-15

    We report a method of fabricating ultra-clean and hysteresis-free multiwall carbon nanotube field-effect transistors (CNFETs) inside the ultra-high vacuum transmission electron microscope equipped with a movable gold tip as a local gate. By tailoring the shell structure of the nanotube and varying the drain-source voltage (V{sub ds}), we can tune the electronic characteristic of a multiwall CNFET in situ. We have also found that the Schottky barriers of a multiwall CNFET are generated within the nanotube, but not at the nanotube/electrode contacts, and the barrier height has been derived. We have subsequently demonstrated the ambipolar characteristics of the CNFET with concurrent high-resolution imaging and local gating.

  1. Template directed formation of nanoparticle decorated multi-walled carbon nanotube bundles with uniform diameter

    NASA Astrophysics Data System (ADS)

    Yong-Jin Han, T.; Stadermann, Michael; Baumann, Theodore F.; Murphy, Kristen E.; Satcher, Joe H., Jr.

    2011-10-01

    Bundles of multi-walled carbon nanotubes of uniform diameter decorated with Ni nanoparticles were synthesized using mesoporous silicates as templates. The ordered morphology and the narrow pore size distribution of mesoporous silicates provide an ideal platform to synthesize uniformly sized carbon nanotubes. In addition, homogeneous sub-10 nm pore sizes of the templates allow in situ formation of catalytic nanoparticles with uniform diameters which end up decorating the carbon nanotubes. The resulting carbon nanotubes are multi-walled with a uniform diameter corresponding to the pore diameter of the template used during the synthesis that are decorated with the catalysts used to synthesize them. They have a narrow size distribution which can be used in many energy related fields of research.

  2. Accurate determination of atomic structure of multiwalled carbon nanotubes by nondestructive nanobeam electron diffraction

    SciTech Connect

    Liu Zejian; Zhang Qi; Qin Luchang

    2005-05-09

    We report a method that allows direct, systematic, and accurate determination of the atomic structure of multiwalled carbon nanotubes by analyzing the scattering intensities on the nonequatorial layer lines in the electron diffraction pattern. Complete structure determination of a quadruple-walled carbon nanotube is described as an example, and it was found that the intertubular distance varied from 0.36 nm to 0.5 nm with a mean value of 0.42 nm.

  3. Direct measurement of chiral structure and transport in single- and multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Cui, Taoran; Lin, Letian; Qin, Lu-Chang; Washburn, Sean

    2016-11-01

    Electrical devices based on suspended multi-wall carbon nanotubes were constructed and studied. The chiral structure of each shell in a particular nanotube was determined using nanobeam electron diffraction in a transmission electron microscope. The transport properties of the carbon nanotube were also measured. The nanotube device length was short enough that the transport was nearly ballistic, and multiple subbands contributed to the conductance. Thermal excitation of carriers significantly affected nanotube resistance at room temperature.

  4. Direct measurement of chiral structure and transport in single- and multi-walled carbon nanotubes.

    PubMed

    Cui, Taoran; Lin, Letian; Qin, Lu-Chang; Washburn, Sean

    2016-11-30

    Electrical devices based on suspended multi-wall carbon nanotubes were constructed and studied. The chiral structure of each shell in a particular nanotube was determined using nanobeam electron diffraction in a transmission electron microscope. The transport properties of the carbon nanotube were also measured. The nanotube device length was short enough that the transport was nearly ballistic, and multiple subbands contributed to the conductance. Thermal excitation of carriers significantly affected nanotube resistance at room temperature. PMID:27633072

  5. Direct measurement of chiral structure and transport in single- and multi-walled carbon nanotubes.

    PubMed

    Cui, Taoran; Lin, Letian; Qin, Lu-Chang; Washburn, Sean

    2016-11-30

    Electrical devices based on suspended multi-wall carbon nanotubes were constructed and studied. The chiral structure of each shell in a particular nanotube was determined using nanobeam electron diffraction in a transmission electron microscope. The transport properties of the carbon nanotube were also measured. The nanotube device length was short enough that the transport was nearly ballistic, and multiple subbands contributed to the conductance. Thermal excitation of carriers significantly affected nanotube resistance at room temperature.

  6. [Comparison study on adsorption of middle molecular substances with multiwalled carbon nanotubes and activated carbon].

    PubMed

    Li, Guifeng; Wan, Jianxin; Huang, Xiangqian; Zeng, Qiao; Tang, Jing

    2011-08-01

    In recent years, multi-walled carbon nanotubes (MWCTs) are very favorable to the adsorption of middle molecular substances in the hemoperfusion because of their multiporous structure, large surface area and high reactivity, which are beneficial to the excellent absorption properties. The purpose of this study was to study the MWCTs on the adsorption capacity of the middle molecular substances. Vitamin B12 (VB12) was selected as a model of the middle molecular substances. The morphologies of MWCTs and activated carbon from commercial "carbon kidney" were observed with scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The adsorption behavior of VB12 was compared to each other with UV-visible absorption spectra. The MWCTs formed a sophistaicate gap structure, and compared to the activated carbon, MWCTs had a larger surface area. By Langmuir equation and Freundlich equation fitting analysis, VB12 adsorption on MWCTs is fit for multi-molecular layer adsorption, and the adsorption type of activated carbon is more inclined to the model corresponding to Langmuir monolayer adsorption. The adsorption rate of MWCTs is faster than that of the activated carbon and the adsorption capacity is greater, which could be expected to become the new adsorbent in the hemoperfusion. PMID:21936376

  7. Fabrication and Characterization of Multi-Walled Carbon Nanotube (MWCNT) and Ni-Coated Multi-Walled Carbon Nanotube (Ni-MWCNT) Repair Patches for Carbon Fiber Reinforced Composite Systems

    NASA Technical Reports Server (NTRS)

    Johnson, Brienne; Caraccio, Anne; Tate, LaNetra; Jackson, Dionne

    2011-01-01

    Multi-walled carbon nanotube (MWCNT)/epoxy and nickel-coated multi-walled carbon nanotube (Ni-MWCNT)/epoxy systems were fabricated into carbon fiber composite repair patches via vacuum resin infusion. Two 4 ply patches were manufactured with fiber orientations of [90/ 90/ 4590] and [0/90/ +45/ -45]. Prior to resin infusion, the MWCNT/Epoxy system and NiMWCNT/ epoxy systems were optimized for dispersion quality. Scanning electron microscopy (SEM) and optical microscopy (OM) were used to determine the presence ofcarbon nanotubes and assess dispersion quality. Decomposition temperatures were determined via thermogravametric analysis (TGA). SEM and TGA were also used to evaluate the composite repair patches.

  8. Synthesis and Characterization of Magnetic Metal-encapsulated Multi-walled Carbon Nanobeads

    PubMed Central

    2008-01-01

    A novel, cost-effective, easy and single-step process for the synthesis of large quantities of magnetic metal-encapsulated multi-walled carbon nanobeads (MWNB) and multi-walled carbon nanotubes (MWNT) using catalytic chemical vapour deposition of methane over Mischmetal-based AB3alloy hydride catalyst is presented. The growth mechanism of metal-encapsulated MWNB and MWNT has been discussed based on the catalytically controlled root-growth mode. These carbon nanostructures have been characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM and HRTEM), energy dispersive analysis of X-ray (EDAX) and thermogravimetric analysis (TGA). Magnetic properties of metal-filled nanobeads have been studied using PAR vibrating sample magnetometer up to a magnetic field of 10 kOe, and the results have been compared with those of metal-filled MWNT.

  9. Deformation and Failure of a Multi-Wall Carbon Nanotube Yarn Composite

    NASA Technical Reports Server (NTRS)

    Gates, Thomas S.; Jefferson, Gail D.; Frankland, Sarah-Jane V.

    2008-01-01

    Forests of multi-walled carbon nanotubes can be twisted and manipulated into continuous fibers or yarns that exhibit many of the characteristics of traditional textiles. Macro-scale analysis and test may provide strength and stiffness predictions for a composite composed of a polymer matrix and low-volume fraction yarns. However, due to the nano-scale of the carbon nanotubes, it is desirable to use atomistic calculations to consider tube-tube interactions and the influence of simulated twist on the effective friction coefficient. This paper reports laboratory test data on the mechanical response of a multi-walled, carbon nanotube yarn/polymer composite from both dynamic and quasi-static tensile tests. Macroscale and nano-scale analysis methods are explored and used to define some of the key structure-property relationships. The measured influence of hot-wet aging on the tensile properties is also reported.

  10. X-ray and synchrotron investigations of heterogeneous systems based on multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Sivkov, V. N.; Ob"edkov, A. M.; Petrova, O. V.; Nekipelov, S. V.; Kremlev, K. V.; Kaverin, B. S.; Semenov, N. M.; Gusev, S. A.

    2015-01-01

    This paper presents the results of a complex investigation of heterogeneous systems based on multiwalled carbon nanotubes with the outer surfaces covered by iron oxide (Fe3O4) nanocoatings deposited using iron pentacarbonyl as a precursor. Investigations were performed by the methods of electron microscopy, X-ray diffractometry, and ultrasoft X-ray spectroscopy with synchrotron radiation. It was established that the formed thin coatings are continuous and nonuniform in thickness. It was shown that good adhesion of iron oxide on the multiwalled carbon nanotube surface is provided by the formation of epoxy and double carbon-oxygen bonds; in this case, the outer graphene layer of nanotubes is not destroyed and retains the hexagonal structure.

  11. Enhanced rate performance of multiwalled carbon nanotube encrusted olivine type composite cathode material using polyol technique

    NASA Astrophysics Data System (ADS)

    Muruganantham, R.; Sivakumar, M.; Subadevi, R.

    2015-12-01

    Olivine type multi-walled carbon nanotube encrusted LiFePO4/C composites have been prepared using economic and energy efficient simple polyol technique without any subsequent heat treatment. The prepared material has an olivine type orthorhombic phase. Also, the iron oxidation state is 2+, which is identified by X-ray diffraction and X-ray photoelectron spectroscopy. It is possible to attain the discharge capacity almost close to theoretical capacity of LiFePO4 as in high temperature methods with ∼100% coulombic efficiency. The specific surface area has been increased upon encrusting multi walled carbon nano tube on LiFePO4/C, which results in enhanced reversible capacity upto 166 mAh g-1 at C/10. Also, it exhibits 89 mAh g-1 even at 30 C rate. This is due to the formation of conductive networks by carbon nanotube, and excellent attachment of LiFePO4/C composite particles on multi-walled carbon nanotube, which induced the kinetics during intercalation/deintercalation process. Multi-walled carbon nanotube acts as the electro-conductive filler on the LiFePO4 surface. The direct addition of MWCNT would result better performances than blending the MWCNT with LiFePO4/C.

  12. Multiwalled Carbon Nanotube Forest Grown via Chemical Vapor Deposition from Iron Catalyst Nanoparticles, by XPS

    SciTech Connect

    Jensen, David S.; Kanyal, Supriya S.; Madaan, Nitesh; Vail, Michael A.; Dadson, Andrew; Engelhard, Mark H.; Linford, Matthew R.

    2013-09-25

    Carbon nanotubes (CNTs) have unique chemical and physical properties. Herein, we report an XPS analysis of a forest of multiwalled CNTs using monochromatic Al Kα radiation. Survey scans show only one element: carbon. The carbon 1s peak is centered 284.5 eV. The C 1s envelope also shows the expected π → π* shake-up peak at ca. 291 eV. The valence band and carbon KVV Auger signals are presented. When patterned, the CNT forests can be used as a template for subsequent deposition of metal oxides to make thin layer chromatography plates.1-3

  13. Enhanced preconcentration of selected chlorofluorocarbons on multiwalled carbon nanotubes with polar functionalities.

    PubMed

    Saridara, Chutarat; Hussain, Chaudhery Mustansar; Ragunath, Smruti; Mitra, Somenath

    2015-02-01

    Chromatographic monitoring of chlorofluorocarbons in air requires the preconcentration of these highly volatile species. In this paper, we present functionalized multiwalled carbon nanotubes as effective sorbents for a microtrap designed for chlorofluorocarbons preconcentration. Among the commercial carbons and carbon nanotubes studied, functionalization via carboxylation and propyl amine was most effective for dichlorofluoromethane and trichlorofluoromethane (Freon 11), which were selected as representative chlorofluorocarbons. The results show that carbon nanotubes functionalized with a polar groups led to as much as a 300% increase in breakthrough volume and the desorption bandwidth was reduced by 2.5 times. PMID:25403651

  14. Enhanced preconcentration of selected chlorofluorocarbons on multiwalled carbon nanotubes with polar functionalities.

    PubMed

    Saridara, Chutarat; Hussain, Chaudhery Mustansar; Ragunath, Smruti; Mitra, Somenath

    2015-02-01

    Chromatographic monitoring of chlorofluorocarbons in air requires the preconcentration of these highly volatile species. In this paper, we present functionalized multiwalled carbon nanotubes as effective sorbents for a microtrap designed for chlorofluorocarbons preconcentration. Among the commercial carbons and carbon nanotubes studied, functionalization via carboxylation and propyl amine was most effective for dichlorofluoromethane and trichlorofluoromethane (Freon 11), which were selected as representative chlorofluorocarbons. The results show that carbon nanotubes functionalized with a polar groups led to as much as a 300% increase in breakthrough volume and the desorption bandwidth was reduced by 2.5 times.

  15. Electrochemical biosensing of galactose based on carbon materials: graphene versus multi-walled carbon nanotubes.

    PubMed

    Dalkıran, Berna; Erden, Pınar Esra; Kılıç, Esma

    2016-06-01

    In this study, two enzyme electrodes based on graphene (GR), Co3O4 nanoparticles and chitosan (CS) or multi-walled carbon nanotubes (MWCNTs), Co3O4 nanoparticles, and CS, were fabricated as novel biosensing platforms for galactose determination, and their performances were compared. Galactose oxidase (GaOx) was immobilized onto the electrode surfaces by crosslinking with glutaraldehyde. Optimum working conditions of the biosensors were investigated and the analytical performance of the biosensors was compared with respect to detection limit, linearity, repeatability, and stability. The MWCNTs-based galactose biosensor provided about 1.6-fold higher sensitivity than its graphene counterpart. Moreover, the linear working range and detection limit of the MWCNTs-based galactose biosensor was superior to the graphene-modified biosensor. The successful application of the purposed biosensors for galactose biosensing in human serum samples was also investigated. PMID:27074783

  16. SEPARATION OF CO2 FROM FLUE GASES BY CARBON-MULTIWALL CARBON NANOTUBE MEMBRANES

    SciTech Connect

    Rodney Andrews

    2001-11-01

    Multiwalled carbon nanotubes (MWNT) were found to be an effective separation media for removing CO{sub 2} from N{sub 2}. The separation mechanism favors the selective condensation of CO{sub 2} from the flowing gas stream. Significant uptakes of CO{sub 2} were measured at 30 C, 150 C and 300 C over the pressure range 0.5 to 5 bar. No measurable uptake of nitrogen was found for this range of conditions. The mass uptake of CO{sub 2} by MWNT was found to increase with increasing temperature. A packed bed of MWNT completely removed CO{sub 2} from a flowing stream of CO{sub 2}/N{sub 2}, and exhibited rapid uptake kinetics for CO{sub 2}.

  17. SEPARATION OF CO2 FROM FLUE GASES BY CARBON-MULTIWALL CARBON NANOTUBE MEMBRANES

    SciTech Connect

    Rodney Andrews

    2001-03-01

    Multiwalled carbon nanotubes (MWNT) were found to be an effective separation media for removing CO{sub 2} from N{sub 2}. The separation mechanism favors the selective condensation of CO{sub 2} from the flowing gas stream. Significant uptakes of CO{sub 2} were measured at 30 C and 150 C over the pressure range 0.5 to 5 bar. No measurable uptake of nitrogen was found for this range of conditions. The mass uptake of CO{sub 2} by MWNT was found to increase with increasing temperature. A packed bed of MWNT completely removed CO{sub 2} from a flowing stream of CO{sub 2}/N{sub 2}, and exhibited rapid uptake kinetics for CO{sub 2}.

  18. A possible formation mechanism of double-walled and multi-walled carbon nanotube: a molecular dynamics study

    NASA Astrophysics Data System (ADS)

    Han, Dianrong; Luo, Chenglin; Dai, Yafei; Zhu, Xingfeng

    2016-09-01

    Molecular dynamics simulations based on an empirical potential were performed to study the interaction of graphene nanoribbons and the single-walled carbon nanotubes. The results indicated that a piece of graphene nanoribbon can form a tube structure inside or outside single-walled carbon nanotubes spontaneously under certain condition. Based on this kind of spontaneous phenomenon, we proposed a new possible formation mechanism of double walled carbon nanotube and multi-walled carbon nanotube, and suggested the possibility of controlling the structure of double-walled carbon nanotube and/or multi-walled carbon nanotube.

  19. Growth of long and aligned multi-walled carbon nanotubes on carbon and metal substrates

    NASA Astrophysics Data System (ADS)

    Delmas, M.; Pinault, M.; Patel, S.; Porterat, D.; Reynaud, C.; Mayne-L'Hermite, M.

    2012-03-01

    Well aligned, long and dense multi-walled carbon nanotubes (CNT) can be grown on both carbon fibres and any metal substrates compatible with the CNT synthesis temperature. The injection-CVD process developed involves two stages, including fibre pretreatment by depositing a SiO2-based sub-layer from an organometallic precursor followed by CNT growth from toluene/ferrocene precursor mixture. Carbon substrates, as well as metals, can easily be treated with this process, which takes place in the same reactor and does not need any handling in between the two stages. The aligned CNT carpets obtained are similar to the ones grown on reference quartz substrates. The CNT growth rate is fairly high (ca. 30 μm min-1) and it is possible to control CNT length by varying the CNT synthesis duration. The thickness of the SiO2-based sub-layer can be varied and is shown to have an influence on the CNT growth. This layer is assumed to play a diffusion barrier layer role between the substrate and the iron based catalyst nanoparticles producing CNT. The CNT anchorage to the carbon fibres has been checked and good overall adhesion proved, which is in favour of a good transfer of electrical charge and heat between the nanotubes and fibre.

  20. Effect of nitrogen-containing groups on enhanced capacitive behaviors of multi-walled carbon nanotubes

    SciTech Connect

    Kim, Ji-Il; Park, Soo-Jin

    2011-08-15

    In this work, electrochemical properties of surface treated multi-walled carbon nanotubes (MWNTs) are studied in supercapacitors. Nitrogen and oxygen functional groups containing MWNTs are prepared by urea and acidic treatments, respectively. The surface properties of the MWNTs are confirmed by X-ray photoelectron spectroscopy (XPS) and zeta-potential measurements. The textural properties are characterized by N{sub 2} adsorption/desorption isotherm at 77 K using the BET eqaution, BJH method, and HK method. The electrochemical properties of the MWNTs are accumulated by cyclic voltammetry, impedance spectra, and charge-discharge cycling performance in 1 M H{sub 2}SO{sub 4} at room temperature. As a result, the functionalized MWNTs lead to an increase in capacitance as compared with pristine MWNTs. It suggests that the pyridinic and pyridinic-N-oxides nitrogen species have effects on the specific capacitance due to the positive charge, and thus an improved electron transfer at high current loads results, the most important functional groups affecting capacitive behaviors. - Graphical Abstract: The N{sub 1s} spectra of nitrogen functionalized multi-walled carbon nanotubes are measured by X-ray photoelectron spectroscopy. Highlights: > Facile method of increasing elemental composition of nitrogen functional groups on carbon materials. > Increased specific capacitance multi-walled carbon nanotubes (MWNTs) for electrode materials as high as general chemical activation process. > Enhanced capacitive behaviors via introducing pyridinic and pyridinic-N-oxides nitrogen species onto the MWNTs. > Improvement of electron transfer at high current loads.

  1. Heterodoped nanotubes: theory, synthesis, and characterization of phosphorus-nitrogen doped multiwalled carbon nanotubes.

    PubMed

    Cruz-Silva, Eduardo; Cullen, David A; Gu, Lin; Romo-Herrera, Jose Manuel; Muñoz-Sandoval, Emilio; López-Urías, Florentino; Sumpter, Bobby G; Meunier, Vincent; Charlier, Jean-Christophe; Smith, David J; Terrones, Humberto; Terrones, Mauricio

    2008-03-01

    Arrays of multiwalled carbon nanotubes doped with phosphorus (P) and nitrogen (N) are synthesized using a solution of ferrocene, triphenyl-phosphine, and benzylamine in conjunction with spray pyrolysis. We demonstrate that iron phosphide (Fe(3)P) nanoparticles act as catalysts during nanotube growth, leading to the formation of novel PN-doped multiwalled carbon nanotubes. The samples were examined by high resolution electron microscopy and microanalysis techniques, and their chemical stability was explored by means of thermogravimetric analysis in the presence of oxygen. The PN-doped structures reveal important morphology and chemical changes when compared to N-doped nanotubes. These types of heterodoped nanotubes are predicted to offer many new opportunities in the fabrication of fast-response chemical sensors.

  2. Synthesis of Multi-Walled Carbon Nanotubes/TiO2 Composite and Its Photocatalytic Activity.

    PubMed

    Dong, Hongying; Qu, Caifeng; Zhang, Tingting; Zhu, Liwei; Ma, Wen

    2016-03-01

    TiO2 particles coated Multi-walled carbon nanotubes (MWCNT/TiO2 composite) were prepared via a sol-gel method using Multi-walled carbon nanotubes (MWCNT) and tetrabutyl titanate as raw materials. The phase constitutes and microstructures of the prepared composite were analyzed by XRD and TEM, respectively. Their photocatalytic activities were investigated under simulated ultra-violet light and visible-light irradiation for the degradation of methyl orange (MO) and methylene blue (MB) aqueous solution, respectively. The experimental results indicated that TiO2 calcined at temperatures of 400-600 degrees C in the MWCNT/TiO2 composite was mainly composed of nanometric anatase. The composite exhibited enhanced absorption properties in the visible-light region compared to pure TiO2, which was attributed to the enhanced light electron-hole separation by adding MWCNTs.

  3. Effect of multi-walled carbon nanotubes on the vibration-reduction behavior of cement

    NASA Astrophysics Data System (ADS)

    Duan, Zhongdong; Luo, Jianlin

    2007-07-01

    In this paper, the vibration damping capacities of cement-based matrix with some additions of multi-walled carbon nanotubes (MWNTs) are investigated with free vibration testing method in an elastic system. The experimental results show that there are positive effects on the critical damping ratio ζ of the cement-based matrix with small amount MWNTs additions. The nanotubes increase the damping ratios (ζ) of the MWNTs reinforced cement composites due to the contribution of excellent frictions among multiple inter-tubes and multi-walled carbon nanotubes-matrix large interface area to damping. The flexural and compressive strength tests of those are subsequently implemented. Results indicate that the nanotubes has the reinforcing function to cement on the flexural strength in some degree, while has the negative impact on its compressive strength.

  4. Synthesis and characterization of polyvinyl alcohol based multiwalled carbon nanotube nanocomposites

    NASA Astrophysics Data System (ADS)

    Malikov, E. Y.; Muradov, M. B.; Akperov, O. H.; Eyvazova, G. M.; Puskás, R.; Madarász, D.; Nagy, L.; Kukovecz, Á.; Kónya, Z.

    2014-07-01

    Multiwalled carbon nanotubes were synthesized by chemical vapor deposition over an Fe-Co/alumina catalyst. Nanotubes were then oxidized and grafted with polyvinyl alcohol (PVA). The obtained nanostructure was characterized by Raman spectroscopy, XRD, FTIR, EDX, SEM, TEM and TGA methods. FTIR confirmed the presence of the characteristic peaks of the anticipated ester group. The formation of polymer nanocomposites based on polyvinyl alcohol and multiwalled carbon nanotubes was confirmed by SEM and TEM. High resolution electron micrographs revealed that the primary binding sites for PVA grafting are the sidewall defects of the nanotubes. The novelty of this work is the use of the Fischer esterification reaction for creating the permanent link between the nanotubes and the PVA matrix.

  5. Hetero-doped Nanotubes: Theory, Synthesis and Characterization of Phosphorus-Nitrogen Doped Multiwalled Carbon Nanotubes

    SciTech Connect

    Sumpter, Bobby G; Cruz Silva, Eduardo; Romo Herrera, Jose M; Smith, David J; Terrones Maldonado, Humberto; Terrones Maldonado, Mauricio; Meunier, Vincent; Cullen, David A; Charlier, Jean Christophe; Lopez, Florentino; Gu, Lin; Munoz-Sandoval, Emilio

    2008-01-01

    Arrays of multiwalled carbon nanotubes doped with phosphorous and nitrogen are synthesized using a solution of ferrocene and triphenyl-phosphine in benzylamine in conjunction with spray pyrolysis. We demonstrate that iron phosphide (Fe3P) nanoparticles act as catalysts during nanotube growth, leading to the formation of novel PN-doped multiwalled carbon nanotubes. The samples produced were examined by SEM, HRTEM and STEM, as well as high-resolution elemental analyses using EELS and EDX spectroscopy, and their chemical stability was explored by means of thermogravimetric analysis in the presence of oxygen. The results reveal striking differences when compared to other types of doped nanotubes. These types of hetero-doped nanotubes with the underlying theory and synthesis are predicted to offer great opportunities in the fabrication of fast responsive chemical sensors.

  6. Synthesis and characterization of multiwalled carbon nanotube/IPMC actuator for imitating locomotion of gecko's toes

    NASA Astrophysics Data System (ADS)

    He, Qingsong; Yu, Min; Ding, Yan; Dai, Zhendong

    2012-04-01

    A multi-walled carbon nanotube (MCNT)/Nafion nanocomposite was fabricated by dispersion of treated MCNTs in a Nafion solution. The multi-walled carbon nanotube (MCNT) filler was prepared with the cationic surfactant cetyl trimethyl ammonium bromide. Starting from cast Nafion membranes, IPMCs were manufactured by electroless plating. The current and the blocking force were measured with an IPMC actuation testing apparatus. Compared with a bare Nafion-based IPMC, the blocking force of the new IPMC improved 1-1.4 times, and the current increased by 33%-67%. The clearly enhanced performance of the new MCNT filler-based IPMC is attributed to the well-distributed MCNTs that improved the electrical properties of the IPMC. Finally, the new IPMC was successfully employed to directly actuate gecko-inspired adhesive arrays that we fabricated by ourselves.

  7. Synthesis of Multi-Walled Carbon Nanotubes/TiO2 Composite and Its Photocatalytic Activity.

    PubMed

    Dong, Hongying; Qu, Caifeng; Zhang, Tingting; Zhu, Liwei; Ma, Wen

    2016-03-01

    TiO2 particles coated Multi-walled carbon nanotubes (MWCNT/TiO2 composite) were prepared via a sol-gel method using Multi-walled carbon nanotubes (MWCNT) and tetrabutyl titanate as raw materials. The phase constitutes and microstructures of the prepared composite were analyzed by XRD and TEM, respectively. Their photocatalytic activities were investigated under simulated ultra-violet light and visible-light irradiation for the degradation of methyl orange (MO) and methylene blue (MB) aqueous solution, respectively. The experimental results indicated that TiO2 calcined at temperatures of 400-600 degrees C in the MWCNT/TiO2 composite was mainly composed of nanometric anatase. The composite exhibited enhanced absorption properties in the visible-light region compared to pure TiO2, which was attributed to the enhanced light electron-hole separation by adding MWCNTs. PMID:27455683

  8. Structural ordering of multi-walled carbon nanotubes (MWCNTs) caused by gamma (γ)-ray irradiation

    SciTech Connect

    Silambarasan, D. Vasu, V.; Iyakutti, K.; Asokan, K.

    2015-06-24

    Multi-walled carbon nanotubes (MWCNTs) were irradiated by Gamma (γ)-rays in air with absorbed doses of 25 and 50 kGy. As a result of γ-ray irradiation, the inter-wall distance of MWCNTs was decreased and their graphitic order was improved. The reduction in inter-wall distance and structural ordering was improved with the increasing dosage of irradiation. Experimental evidences are provided by powder XRD and micro-Raman analyses.

  9. Synthesis of Meltspun Multiwall Carbon Nanotube/Polycarbonate Fibers Through Solvent Casting and Melt Extrusion.

    PubMed

    Yadav, Poonam; Park, Sang Whan; Lee, Dong Bok

    2015-11-01

    Films and strands consisting of polycarbonate (PC) containing 0.55 or 0.75 wt% multiwall carbon nanotubes (MWNTs) were synthesized through solvent casting and melt extrusion methods, respectively. They were further processed into fibers through melt spinning. Fibers made from melt-extruded strands exhibited a smoother surface, more uniform morphology, and better dispersion of MWNTs in PC than those made from solvent-cast films. PMID:26726657

  10. Dust-ion-acoustic wave oscillation in metallic multiwalled carbon nanotubes

    SciTech Connect

    Fathalian, Ali; Nikjo, Shahram

    2010-10-15

    In this paper, a charged multiwalled carbon nanotube (MWCNT), which is surrounded by charged nanoparticles, is modeled as a cylindrical shell of electron-ion-dust plasma. By employing the classical electrodynamics formulations and linearized hydrodynamic model, the dispersion relation of the dust-ion-acoustic wave oscillations in the composed system is investigated. We obtain a new low-frequency electrostatic excitation in the MWCNTs, i.e., dust-ion-acoustic wave oscillations.

  11. Origin of enhanced field emission characteristics postplasma treatment of multiwalled carbon nanotube array

    SciTech Connect

    Lee, Kyu; Lim, Seong Chu; Lee, Young Hee; Choi, Young Chul

    2008-08-11

    Field emission properties of chemical-vapor-deposition-grown multiwalled carbon nanotubes (MWCNTs) with plasma treatment have been investigated. Origin of the enhanced field emission current was interpreted in terms of surface morphology of MWCNTs, work function, field enhancement factor, and emission area. Contrary to the general belief, the change in the work function increased slightly with the plasma treatment time, whereas the field enhancement factor decreased. We found that the number of emittable MWCNTs played a dominant role in the current enhancement.

  12. Multi-wall carbon nanotube@zeolite imidazolate framework composite from a nanoscale zinc oxide precursor

    SciTech Connect

    Yue, Yanfeng; Guo, Bingkun; Qiao, Zhenan; Fulvio, Pasquale F.; Chen, Jihua; Binder, Andrew J.; Tian, Chengcheng; Dai, Sheng

    2014-07-24

    Nanocomposite of multi-walled carbon nanotube@zeolite imidazolate frameworks (MWNT@ZIF) was prepared through a nanotube-facilitated growth based on a nanosized ZnO precursor. The electrically conductive nanocomposite displays a capacity of 380 mAh/g at 0.1 °C in Li–sulfur battery, transforming electrically inactive ZIF into the active one for battery applications.

  13. Multifunctional PEGylated multiwalled carbon nanotubes for enhanced blood pool and tumor MR imaging.

    PubMed

    Wen, Shihui; Zhao, Qinghua; An, Xiao; Zhu, Jingyi; Hou, Wenxiu; Li, Kai; Huang, Yunpeng; Shen, Mingwu; Zhu, Wei; Shi, Xiangyang

    2014-10-01

    Long-circulating multifunctional Gd(III)-loaded multiwalled carbon nanotubes (MWCNTs) modified with polyethylene glycol are designed and synthesized. The formed MWCNTs are water-dispersible, stable, and have good cytocompatibility and antifouling property. With the low r 2 /r 1 relaxivity ratio and relatively long blood circulation time, the multifunctional MWCNTs are able to be used as a platform for enhanced blood pool and tumor MR imaging.

  14. Functionalization of multiwalled carbon nanotubes and their pH-responsive hydrogels with amyloid fibrils.

    PubMed

    Li, Chaoxu; Mezzenga, Raffaele

    2012-07-10

    New biocompatible, pH-responsive, and fully fibrous hydrogels have been prepared based on amyloid fibrils hybridized and gelled by functionalized multiwalled carbon nanotubes (MWNTs) far below the gelling concentration of amyloid fibrils. Sulfonic functional groups were introduced on the surfaces of MWNTs either by a covalent diazonium reaction or by physical π-π interactions. The presence of the isoelectric point of amyloid fibrils allows a reversible gelling behavior through ionic interactions with functionalized MWNTs.

  15. Carboxyl multiwalled carbon nanotubes modified polypyrrole (PPy) aerogel for enhanced electromagnetic absorption

    NASA Astrophysics Data System (ADS)

    Zhang, Kun; Xie, Aming; Wu, Fan; Jiang, Wanchun; Wang, Mingyang; Dong, Wei

    2016-05-01

    Polypyrrole (PPy) aerogel is a low-cost and lightweight material with high-performance electromagnetic absorption (EA). However, it does not always meet the requirements of practical applications. In this study, we used trace amounts of carboxyl multiwalled carbon nanotubes to regulate the dielectric property of PPy aerogel, thus enhancing the EA performance. Furthermore, the reason for enhanced EA performance can be elaborated by an electron blocking mechanism.

  16. Pyrolytic deposition of nanostructured titanium carbide coatings on the surface of multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Kremlev, K. V.; Ob"edkov, A. M.; Ketkov, S. Yu.; Kaverin, B. S.; Semenov, N. M.; Gusev, S. A.; Tatarskii, D. A.; Yunin, P. A.

    2016-05-01

    Nanostructured titanium carbide coatings have been deposited on the surface of multiwalled carbon nanotubes (MWCNTs) by the MOCVD method with bis(cyclopentadienyl)titanium dichloride precursor. The obtained TiC/MWCNT hybrid materials were characterized by X-ray diffraction, scanning electron microscopy, and high-resolution transmission electron microscopy. It is established that a TiC coating deposits onto the MWCNT surface with the formation of a core-shell (MWSNT-TiC) type structure.

  17. Synthesis of Meltspun Multiwall Carbon Nanotube/Polycarbonate Fibers Through Solvent Casting and Melt Extrusion.

    PubMed

    Yadav, Poonam; Park, Sang Whan; Lee, Dong Bok

    2015-11-01

    Films and strands consisting of polycarbonate (PC) containing 0.55 or 0.75 wt% multiwall carbon nanotubes (MWNTs) were synthesized through solvent casting and melt extrusion methods, respectively. They were further processed into fibers through melt spinning. Fibers made from melt-extruded strands exhibited a smoother surface, more uniform morphology, and better dispersion of MWNTs in PC than those made from solvent-cast films.

  18. Control of neuronal network organization by chemical surface functionalization of multi-walled carbon nanotube arrays

    PubMed Central

    Liu, Jie; Appaix, Florence; Bibari, Olivier; Marchand, Gilles; Benabid, Alim-Louis; Sauter-Starace, Fabien; Waard, Michel De

    2011-01-01

    Carbon nanotube substrates are promising candidates for biological applications and devices. Interfacing of these carbon nanotubes with neurons can be controlled by chemical modifications. In this study, we investigated how chemical surface functionalisation of multi-walled carbon nanotube arrays (MWNT-A) influences neuronal adhesion and network organization. Functionalisation of MWNT-A dramatically modifies length of neurite fascicles, cluster interconnection success rate, and percentage of neurites that escape from the clusters. We propose that chemical functionalisation represents a method of choice for developing applications in which neuronal patterning on MWNT-A substrates is a must. PMID:21436508

  19. Multiwalled carbon nanotubes as masks against carbon and argon irradiation. A molecular dynamics study

    NASA Astrophysics Data System (ADS)

    Denton, Cristian D.; Moreno-Marín, Juan Carlos; Heredia-Avalos, Santiago

    2016-04-01

    Experiments showed that multiwalled carbon nanotubes (MWCNT) can be used as masks against irradiation to create metallic nanowires in a substrate. In order to understand the limitations of this application, it is interesting to know the energy and number of carbon atoms emerging from the MWCNT after the irradiation and how the structure of the MWCNT is modified. Using a molecular dynamics code that we have previously developed, we have simulated the continuous irradiation of MWCNT with carbon and argon projectiles. We have obtained that the use of carbon instead of argon to irradiate the MWCNT increases de effectiveness of the MWCNTs as masks, due to the ability of the carbon projectiles to be part of the MWCNT structure and partially mend the damage produced during irradiation. We have analyzed the number, energy, and spatial distribution of the recoils generated during irradiation and the change of the MWCNT structure as a function of the incident energy (100 and 500 eV), fluence (up to 4.5 ·1015ions /cm2), and number of shells (up to 5-shells) of the MWCNT. These results determine the effectiveness of MWCNT as a mask, being useful to understand whether the atoms emerging from the MWCNT produce damage in the substrate or not. We find that for carbon projectiles the efficiency of MWCNT as masks does not depend much on the fluence, but on the number of nanotube shells and projectile incident energy. On the other hand, for a given nanotube and fluence, we observe a threshold incident energy below which the nanotube acts as a perfect mask.

  20. Ultrasonic deagglomeration of aluminum nanopowders with multi-walled carbon nanotube mixtures

    SciTech Connect

    Kozulin, Alexander A. Vorozhtsov, Sergey A. Kulkov, Sergey S.; Kulkov, Sergey N.; Teipel, U.

    2015-10-27

    Comprehensive investigations of aluminum nanopowders, multi-walled carbon nanotubes, and aluminum mixtures with multi-walled carbon nanotubes subjected to ultrasonic deagglomeration in a liquid medium were performed, using microstructural, X-ray diffraction, thermogravimetric, and calorimetric analyses, and specific surface area measurements. The regime of ultrasonic deagglomeration of aluminum nanopowders with multi-walled carbon nanotubes in a liquid medium is described, during which the division of large agglomerates and creation of homogeneous distribution of mixtures components in the volume takes place. It was determined that ultrasonic treatment influences the morphology and crystalline structure of investigated mixtures, contributes to the appearance of X-ray amorphous phase, decreases the specific surface area of the aluminum nanopowder from 13 to 12 m{sup 2}/g, and increases the pore volume and average size from 0.04 to 0.06 cm{sup 3}/g and from 12 to 19 nm, respectively. The size of coherently-diffracting domain was determined by the X-ray diffraction analysis is close to that estimated from the specific surface area and corresponds to average crystallites size in the materials under study.

  1. Processing route to disentangle multi-walled carbon nanotube towards ceramic composite.

    PubMed

    Belmonte, M; Vallés, C; Maser, W K; Benito, A M; Martinez, M T; Miranzo, P; Osendi, M I

    2009-10-01

    Multi-walled carbon nanotubes were highly aggregated into ropes after their synthesis by chemical vapour deposition and, therefore, two different methods for disentangling the bundles of nanotubes were studied. One method compared the use of mild and vigorous mechanical treatments in ethanol and the other one employed dispersants in aqueous media. For comparison purposes and according to their different exfoliating behaviour, sodium dodecyl sulphate and gum arabic were selected as dispersants. The results evidenced that mechanical sonication was insufficient for disentangling the ropes, whereas, the combined action of mild sonication in an ultrasonic bath with the addition of gum arabic to an aqueous suspension containing nanotubes improved the exfoliating performance. Stable suspensions of unbundled multi-walled carbon nanotubes were obtained adding only 0.05 wt% of gum arabic with a dispersant/MWNTs concentration ratio of 0.25. These values corresponded to a reduction in the dispersant concentration between 1 to 2 orders of magnitude compared to those commonly employed. In addition, a processing route for manufacturing dense and homogenous silicon nitride composites using spark plasma sintering with 1.8 vol% of multi-walled carbon nanotubes almost free of organics was developed without nanotubes degradation and aggregation.

  2. Effects of different carbon precursors on synthesis of multiwall carbon nanotubes: Purification and Functionalization

    NASA Astrophysics Data System (ADS)

    Shirazi, Yaser; Tofighy, Maryam Ahmadzadeh; Mohammadi, Toraj; Pak, Afshin

    2011-06-01

    Cyclohexanol and xylene were used as carbon precursors, for synthesis of multiwall carbon nanotubes (MWCNTs) arrays in a CVD system at temperature of 750 °C, using nitrogen as carrier gas and ferrocene as catalyst. Different characterization methods were employed to compare the MWCNTs structure synthesized by these two precursors. All scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermal gravimetric analysis (TGA) and Raman spectroscopy results illustrated that using cyclohexanol could significantly reduce formation of amorphous carbon and catalyst particles in the as-grown CNTs. The less amorphous carbon can be attributed to in situ oxidation in presence of oxygen atom of cyclohexanol. Characterizations showed that MWCNTs with high purity could be obtained using cyclohexanol as carbon precursor. The as-grown MWCNTs were purified by oxidation and acid treatment. Characterization of the purified MWCNTs using HNO 3/H 2SO 4 (1/3 or 1/1), 8 M HCl or 8 M HNO 3 was carried out. The results showed that 8 M HNO 3 could be considered as the best chemical to obtain more pure MWCNTs, less amorphous and metal particles and less damaged MWCNTs. The Raman spectroscopy results demonstrated that HNO 3/H 2SO 4 (1/3) treatment could more disorder the MWCNTs structure and this was attributed to the bigger destroying effect of this acid treatment. Furthermore, the TEM analysis of MWCNTs before and after acid treatment revealed that acid treatment could remove encapsulated catalyst particles. The FTIR analysis illustrated that purification of the MWCNTs with nitric acid could connect the functional groups onto the outer surface of MWCNTs and this resulted in more dispersion of the MWCNTs in water.

  3. Electroanalysis of some common pesticides using conducting polymer/multiwalled carbon nanotubes modified glassy carbon electrode.

    PubMed

    Manisankar, P; Sundari, Pl Abirama; Sasikumar, R; Palaniappan, Sp

    2008-09-15

    The cyclic voltammetric behaviour of three common pesticides such as isoproturon (ISO), voltage (VOL) and dicofol (DCF) was investigated at glassy carbon electrode (GCE), multiwalled carbon nanotubes modified GCE (MWCNTs/GCE), polyaniline (PANI) and polypyrrole (PPY) deposited MWCNT/GCE. The modified electrode film was characterized by scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD). The electroactive behaviour of the pesticides was realized from the cyclic voltammetric studies. The differential pulse voltammetric principle was used to analyze the above-mentioned pesticides using MWCNT/GCE, PANI/MWCNT/GCE and PPY/MWCNT/GCE. Effects of accumulation potential, accumulation time, Initial scan potential, amplitude and pulse width were examined for the optimization of stripping conditions. The PANI/MWCNT/GCE performed well among the three electrode systems and the determination range obtained was 0.01-100 mgL(-1) for ISO, VOL and DCF respectively. The limit of detection (LOD) was 0.1 microgL(-1) for ISO, 0.01 microgL(-1) for VOL and 0.05 microgL(-1) for DCF on PANI/MWCNT/GCE modified system. It is significant to note that the PANI/MWCNT/GCE modified system results in the lowest LOD in comparison with the earlier reports. Suitability of this method for the trace determination of pesticide in spiked samples was also realized.

  4. Binding energy and mechanical stability of single- and multi-walled carbon nanotube serpentines.

    PubMed

    Zhao, Junhua; Lu, Lixin; Rabczuk, Timon

    2014-05-28

    Recently, Geblinger et al. [Nat. Nanotechnol. 3, 195 (2008)] and Machado et al. [Phys. Rev. Lett. 110, 105502 (2013)] reported the experimental and molecular dynamics realization of S-like shaped single-walled carbon nanotubes (CNTs), the so-called CNT serpentines. We reported here results from continuum modeling of the binding energy γ between different single- and multi-walled CNT serpentines and substrates as well as the mechanical stability of the CNT serpentine formation. The critical length for the mechanical stability and adhesion of different CNT serpentines are determined in dependence of EiIi, d, and γ, where EiIi and d are the CNT bending stiffness and distance of the CNT translation period. Our continuum model is validated by comparing its solution to full-atom molecular dynamics calculations. The derived analytical solutions are of great importance for understanding the interaction mechanism between different single- and multi-walled CNT serpentines and substrates. PMID:24880308

  5. Unraveling the growth of vertically aligned multi-walled carbon nanotubes by chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Ramirez, A.; Royo, C.; Latorre, N.; Mallada, R.; Tiggelaar, R. M.; Monzón, A.

    2014-12-01

    The interaction between the main operational variables during the growth of vertically aligned multiwalled carbon nanotubes (VA-MWCNTs) by catalytic chemical vapor deposition is studied. In this contribution, we report the influence of the carbon source (i.e. acetylene, ethylene and propylene), the reaction/activation temperature, the rate of heating, the reaction time, the metal loading, and the metallic nanoparticle size and distribution on the growth and alignment of carbon nanotubes. Fe/Al thin films deposited onto silicon samples by electron-beam evaporation are used as catalyst. A phenomenological growth mechanism is proposed to explain the interaction between these multiple factors. Three different outcomes of the synthesis process are found: i) formation of forests of non-aligned, randomly oriented multi-walled carbon nanotubes, ii) growth of vertically aligned tubes with a thin and homogeneous carbonaceous layer on the top, and iii) formation of vertically aligned carbon nanotubes. This carbonaceous layer (ii) has not been reported before. The main requirements to promote vertically aligned carbon nanotube growth are determined.

  6. 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}.

  7. The effects of liquid-phase oxidation of multiwall carbon nanotubes on their surface characteristics

    NASA Astrophysics Data System (ADS)

    Burmistrov, I. N.; Muratov, D. S.; Ilinykh, I. A.; Kolesnikov, E. A.; Godymchuk, A. Yu; Kuznetsov, D. V.

    2016-01-01

    The development of new sorbents based on nanostructured carbon materials recently became a perspective field of research. Main topic of current study is to investigate the effect of different regimes of multiwall carbon nanotubes (MWCNT) surface modification process on their structural characteristics. MWCNT samples were treated with nitric acid at high temperature. Structural properties were studied using low temperature nitrogen adsorption and acid-base back titration methods. The study showed that diluted nitric acid does not affect MWCNT structure. Concentrated nitric acid treatment leads to formation of 2.8 carboxylic groups per 1 nm2 of the sample surface.

  8. Multi-walled carbon nanotubes in aqueous phytic acid for enhancing biosensor

    NASA Astrophysics Data System (ADS)

    Guo, Xiaoyu; Miao, Yun; Ye, Pingping; Wen, Ying; Yang, Haifeng

    2014-04-01

    The poor dispersion of carbon based nanomaterials without strong acid pretreatment in aqueous solution is a fundamental problem, limiting its applications in biology-related fields. A good dispersion of multi-walled carbon nanotubes (MWCNTs) in water was realized by 50 wt.% phytic acid (PA) solution. As an application case, the PA-MWCNTs dispersion in aqueous solution was used for the immobilization of horseradish peroxidase (HRP) and its direct electrochemistry was realized. The constructed biosensor has a sound limit of detection, wide linear range, and high affinity for hydrogen peroxide (H2O2) as well as being free from interference of co-existing electro-active species.

  9. Diameter-dependent dissipation of vibration energy of cantilevered multiwall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Sawaya, Shintaro; Arie, Takayuki; Akita, Seiji

    2011-04-01

    This study investigated the mechanical properties of vibrating cantilevered multiwall carbon nanotubes in terms of energy loss in a vibrating nanotube. Young's moduli of the nanotubes show a clear dependence of the perfection of the sp2 carbon network, as determined from Raman spectroscopy. The energy loss corresponding to the inverse of the quality factor increases with increasing tube diameter, although the nanotube maintains high mechanical strength around 0.5 TPa. This fact implies that the vibration energy is dissipated mainly not by defects, but by van der Waals interactions between walls.

  10. The nanocrystal-carbon cage- interface effect on surface superconductivity in YC 2 encapsulated in the multiwall carbon nanocages

    NASA Astrophysics Data System (ADS)

    Yosida, Y.; Oguro, I.

    2005-09-01

    The upper critical magnetic field for the vortex state, Hc2, for the bulk crystals YC 2 and the critical field for the state of surface superconductivity, Hc3, for the single-crystals YC 2 encapsulated in the multiwall carbon nanocages as a function of t ( T/ Tc, Tc = 3.838 K) are reported. The ratio Hc3/ Hc2 increases with increasing t from 1.6 ± 0.2 at t = 0.6 to 2.0 ± 0.3 at t = 0.99. The present data accord with the reported experimental results for the type-II superconductors surrounded by the insulators. The role of the interface between the single-crystal YC 2 and the multiwall carbon nanocage in surface superconductivity is discussed in terms of the boundary effects.

  11. Parameterizing A Surface Water Model for Multiwalled Carbon Nanotubes

    EPA Science Inventory

    The unique electronic, mechanical, and structural properties of carbon nanotubes (CNTs) has lead to increasing production of these versatile materials; currently, the use of carbon-based nanomaterials in consumer products is second only to that of nano-scale silver. Although ther...

  12. Effects of nitrogen-doped multi-walled carbon nanotubes compared to pristine multi-walled carbon nanotubes on human small airway epithelial cells.

    PubMed

    Mihalchik, Amy L; Ding, Weiqiang; Porter, Dale W; McLoughlin, Colleen; Schwegler-Berry, Diane; Sisler, Jennifer D; Stefaniak, Aleksandr B; Snyder-Talkington, Brandi N; Cruz-Silva, Rodolfo; Terrones, Mauricio; Tsuruoka, Shuji; Endo, Morinobu; Castranova, Vincent; Qian, Yong

    2015-07-01

    Nitrogen-doped multi-walled carbon nanotubes (ND-MWCNTs) are modified multi-walled carbon nanotubes (MWCNTs) with enhanced electrical properties that are used in a variety of applications, including fuel cells and sensors; however, the mode of toxic action of ND-MWCNT has yet to be fully elucidated. In the present study, we compared the interaction of ND-MWCNT or pristine MWCNT-7 with human small airway epithelial cells (SAEC) and evaluated their subsequent bioactive effects. Transmission electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and X-ray diffraction suggested the presence of N-containing defects in the lattice of the nanotube. The ND-MWCNTs were determined to be 93.3% carbon, 3.8% oxygen, and 2.9% nitrogen. A dose-response cell proliferation assay showed that low doses of ND-MWCNT (1.2μg/ml) or MWCNT-7 (0.12μg/ml) increased cellular proliferation, while the highest dose of 120μg/ml of either material decreased proliferation. ND-MWCNT and MWCNT-7 appeared to interact with SAEC at 6h and were internalized by 24h. ROS were elevated at 6 and 24h in ND-MWCNT exposed cells, but only at 6h in MWCNT-7 exposed cells. Significant alterations to the cell cycle were observed in SAEC exposed to either 1.2μg/ml of ND-MWCNT or MWCNT-7 in a time and material-dependent manner, possibly suggesting potential damage or alterations to cell cycle machinery. Our results indicate that ND-MWCNT induce effects in SAEC over a time and dose-related manner which differ from MWCNT-7. Therefore, the physicochemical characteristics of the materials appear to alter their biological effects.

  13. Effects of nitrogen-doped multi-walled carbon nanotubes compared to pristine multi-walled carbon nanotubes on human small airway epithelial cells

    PubMed Central

    Mihalchik, Amy L.; Ding, Weiqiang; Porter, Dale W.; McLoughlin, Colleen; Schwegler-Berry, Diane; Sisler, Jennifer D.; Stefaniak, Aleksandr B.; Snyder-Talkington, Brandi N.; Cruz-Silva, Rodolfo; Terrones, Mauricio; Tsuruoka, Shuji; Endo, Morinobu; Castranova, Vincent; Qian, Yong

    2015-01-01

    Nitrogen-doped multi-walled carbon nanotubes (ND-MWCNTs) are modified multi-walled carbon nanotubes (MWCNTs) with enhanced electrical properties that are used in a variety of applications, including fuel cells and sensors; however, the mode of toxic action of ND-MWCNT has yet to be fully elucidated. In the present study, we compared the interaction of ND-MWCNT or pristine MWCNT-7 with human small airway epithelial cells (SAEC) and evaluated their subsequent bioactive effects. Transmission electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and X-ray diffraction suggested the presence of N-containing defects in the lattice of the nanotube. The ND-MWCNTs were determined to be 93.3% carbon, 3.8% oxygen, and 2.9% nitrogen. A dose–response cell proliferation assay showed that low doses of ND-MWCNT (1.2 mg/ml) or MWCNT-7 (0.1 mg/ml) increased cellular proliferation, while the highest dose of 120 mg/ml of either material decreased proliferation. ND-MWCNT and MWCNT-7 appeared to interact with SAEC at 6 h and were internalized by 24 h. ROS were elevated at 6 and 24 h in ND-MWCNT exposed cells, but only at 6 h in MWCNT-7 exposed cells. Significant alterations to the cell cycle were observed in SAEC exposed to either 1.2 mg/ml of ND-MWCNT or MWCNT-7 in a time and material-dependent manner, possibly suggesting potential damage or alterations to cell cycle machinery. Our results indicate that ND-MWCNT induce effects in SAEC over a time and dose-related manner which differ from MWCNT-7. Therefore, the physicochemical characteristics of the materials appear to alter their biological effects. PMID:25797581

  14. Composites of polyvinyl alcohol and carbon (coils, undoped and nitrogen doped multiwalled carbon nanotubes) as ethanol, methanol and toluene vapor sensors.

    PubMed

    Greenshields, Márcia W C C; Hümmelgen, Ivo A; Mamo, Messai A; Shaikjee, Ahmed; Mhlanga, Sabelo D; van Otterlo, Willem A L; Coville, Neil J

    2011-11-01

    We investigate the chemical sensing behavior of composites prepared with polyvinyl alcohol and carbon materials (undoped multiwalled carbon nanotubes, nitrogen-doped multiwalled carbon nanotubes and carbon nanocoils). We determine the sensitivity of thin films of these composites for ethanol, methanol and toluene vapor, comparing their conductance and capacitance responses. The composite that exhibits highest sensitivity depends on specific vapor, vapor concentration and measured electrical response, showing that the interactivity of the carbon structure with chemical species depend on structural specificities of the carbon structure and doping.

  15. Multi-walled Carbon Nanotubes/Graphite Nanosheets Modified Glassy Carbon Electrode for the Simultaneous Determination of Acetaminophen and Dopamine.

    PubMed

    Zhang, Susu; He, Ping; Zhang, Guangli; Lei, Wen; He, Huichao

    2015-01-01

    Graphite nanosheets prepared by thermal expansion and successive sonication were utilized for the construction of a multi-walled carbon nanotubes/graphite nanosheets based amperometric sensing platform to simultaneously determine acetaminophen and dopamine in the presence of ascorbic acid in physiological conditions. The synergistic effect of multi-walled carbon nanotubes and graphite nanosheets catalyzed the electrooxidation of acetaminophen and dopamine, leading to a remarkable potential difference up to 200 mV. The as-prepared modified electrode exhibited linear responses to acetaminophen and dopamine in the concentration ranges of 2.0 × 10(-6) - 2.4 × 10(-4) M (R = 0.999) and 2.0 × 10(-6) - 2.0 × 10(-4) M (R = 0.998), respectively. The detection limits were down to 2.3 × 10(-7) M for acetaminophen and 3.5 × 10(-7) M for dopamine (S/N = 3). Based on the simple preparation and prominent electrochemical properties, the obtained multi-walled carbon nanotubes/graphite nanosheets modified electrode would be a good candidate for the determination of acetaminophen and dopamine without the interference of ascorbic acid.

  16. Sodium insertion/extraction from single-walled and multi-walled carbon nanotubes: The differences and similarities

    NASA Astrophysics Data System (ADS)

    Goonetilleke, Damian; Pramudita, James C.; Choucair, Mohammad; Rawal, Aditya; Sharma, Neeraj

    2016-05-01

    A comparative study on the sodium-ion insertion and extraction of commercially-available multi-wall and single-wall carbon nanotubes is reported. Single-wall carbon nanotubes exhibit charge/discharge capacities of 126 mA h g-1 and multi-wall carbon nanotubes produce a lower capacity of 28 mA h g-1 after 50 cycles at 25 mA g-1. To understand these differences, a combination of X-ray diffraction and solid state nuclear magnetic resonance measurements were performed at various states of sodium insertion and extraction.23Na nuclear magnetic resonance studies, a technique previously rarely used for characterising electrodes from sodium-ion batteries, shows differences in the sodium chemical environment near multi-wall compared to single-wall carbon nanotubes with distinct sodium sites found to be active during sodium insertion and extraction for the carbon nanotubes. Both types of carbon nanotubes show a similar amount of reversible sodium available for insertion/extraction reactions, but multi-wall carbon nanotubes feature half the initial insertion capacity relative to single-wall carbon nanotubes. The electrochemical performance of the carbon nanotube electrodes are discussed in relation to the observed mechanism of sodium insertion.

  17. Inelastic x-ray study of plasmons in oriented single and multi-walled carbon nanotubes.

    SciTech Connect

    Casa, D. M.; Upton, M. H.; Gog, T.; Misewich, J.; Hill, J.P.; Lowndes, D.; Eres, G.; BNL; ORNL

    2006-01-01

    Carbon nanotubes (CNT) have a wide variety of interesting properties and a large number of potential aplications in electronic and optical devices. In this study we concentrate on one important aspect of their electronic stucture: the plasmon dispersions in both single- and multi-wall CNTs and their relation to those in graphite. For the first time inelastic X-ray scattering is used to study these collective electronic excitations in oriented CNT samples. The experiments were performed on the IXS instrument at beamline 9ID CMC-XOR, APS, ANL. The incident energy was defined by a Si(333) monochromator, a spherically bent Ge(733) diced analyzer at the end of a 1-m arm focused the incident radiation onto a solid-state detector. The overall resolution was {approx}300 meV FWHM. The incident photons were linearly polarized perpendicular to the scattering plane. Energy loss scans were taken by varying the incident energy while keeping the exit energy fixed at 8.9805 keV. The momentum transfer was kept along the nanotubes axis. Spectra were taken at room temperature. The samples were oriented CNTs (both single- and multi-wall) grown on a Si substrate. The samples referred to as 'single-wall' were in fact a few walls at most (1-5) while the multi-walled ones had {approx}12 walls. Fig. 1. shows the inelastic spectra for the single-, multi-wall, and highly oriented pyrolithic graphite (HOPG) from top to bottom. Momentum transfer was Q = 0.79 {angstrom}{sup -1} in all cases, its direction was along the tubes for the first two samples or parallel to the sheets for graphite. The peaks at {approx}10 and {approx}30 eV are known as the {pi} and {sigma} + {pi} plasmons respectively. Fig. 2. shows the complete dispersion curves for both plasmon modes as a function of momentum transfer for all three samples.

  18. An evaluation of the impact of multi-walled carbon nanotubes on soil microbial community structure and functional diversity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Increasing application of carbon nanotubes (CNTs) triggers the need for an assessment of their effects on organisms in the environment. Soil microbial communities play a significant role in soil organic matter dynamics and nutrient cycling. This study evaluated the impacts of multi-walled carbon nan...

  19. Carbon nanotube ecotoxicity in amphibians: assessment of multiwalled carbon nanotubes and comparison with double-walled carbon nanotubes.

    PubMed

    Mouchet, Florence; Landois, Perine; Puech, Pascal; Pinelli, Eric; Flahaut, Emmanuel; Gauthier, Laury

    2010-08-01

    The potential impact of industrial multiwalled carbon nanotubes (MWNTs) was investigated under normalized laboratory conditions according to the International Standard micronucleus assay ISO 21427-1 for 12 days of half-static exposure to 0.1, 1, 10 and 50 mg/l of MWNTs in water. Three different end points were carried out for 12 days of exposure: mortality, growth inhibition and micronuclei induction in erythrocytes of the circulating blood of larvae. Raman spectroscopy analysis was used to study the presence of carbon nanotubes in the biological samples. Considering the high diversity of carbon nanotubes according to their different characteristics, MWNTs were analyzed in Xenopus larvae, comparatively to double-walled carbon nanotubes used in a previous study in similar conditions. Growth inhibition in larvae exposed to 50 mg/l of MWNTs was evidenced; however, no genetoxicity (micronucleus assay) was noticed, at any concentration. Carbon nanotube localization in the larvae leads to different possible hypothesis of mechanisms explaining toxicity in Xenopus.

  20. Rapid prototyping of three-dimensional microstructures from multiwalled carbon nanotubes

    SciTech Connect

    Hung, W.H.; Kumar, Rajay; Bushmaker, Adam; Cronin, Stephen B.; Bronikowski, Michael J.

    2007-08-27

    The authors report a method for creating three-dimensional carbon nanotube structures, whereby a focused laser beam is used to selectively burn local regions of a dense forest of multiwalled carbon nanotubes. Raman spectroscopy and scanning electron microscopy are used to quantify the threshold for laser burnout and depth of burnout. The minimum power density for burning carbon nanotubes in air is found to be 244 {mu}W/{mu}m{sup 2}. We create various three-dimensional patterns using this method, illustrating its potential use for the rapid prototyping of carbon nanotube microstructures. Undercut profiles, changes in nanotube density, and nanoparticle formation are observed after laser surface treatment and provide insight into the dynamic process of the burnout mechanism.

  1. Facile synthesis of highly aligned multiwalled carbon nanotubes from polymer precursors.

    SciTech Connect

    Han, C. Y.; Xiao, Z.-L.; Wang, H. H.; Lin, X.-M.; Trasobares, S.; Cook, R. E.; Richard J. Daley Coll.; Northern Illinois Univ.; Univ. de Cadiz

    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 carbon 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.

  2. Distinct electrical effects of multi-walled carbon nanotubes in two composites

    NASA Astrophysics Data System (ADS)

    Wang, Leizhi; Wang, Hua; Datta, Timir; Yin, Ming; Tian, Xingyou

    2014-11-01

    The temperature dependent conductivity of multi-walled carbon nanotube film (MWNT) is reported and the different electrical properties of nanotubes in two composites are compared. Due to the disordered structures, our carbon nanotube film displays variable range hopping behavior. While the geometric distributions of carbon nanotubes in the conducting polyaniline (PANI) and insulating polyamide (PA66) are similar, charge carriers transport distinctly. The conductive PANI, following one-dimensional variable range hopping, dominates the electrical properties of MWNT/PANI composites. The effect of MWNTs becomes prominent only at low temperature range. However, the contact junctions composed by adjacent carbon nanotubes, instead of nanotubes themselves or the polymer matrix, determine the electrical properties of MWNT/PA66 composites, showing the fluctuation induced tunneling characteristic.

  3. Polarization Losses under Accelerated Stress Test Using Multiwalled Carbon Nanotube Supported Pt Catalyst in PEM Fuel Cells

    SciTech Connect

    Park, Seh K.; Shao, Yuyan; Kou, Rong; Viswanathan, Vilayanur V.; Towne, Silas A.; Rieke, Peter C.; Liu, Jun; Lin, Yuehe; Wang, Yong

    2011-03-01

    The electrochemical behavior for Pt catalysts supported on multiwalled carbon nanotubes and Vulcan XC-72 in proton exchange membrane fuel cells under accelerated stress test was examined by cyclic voltammetry, electrochemical impedance spectroscopy, and polarization technique. Pt catalyst supported on multiwalled carbon nanotubes exhibited highly stable electrochemical surface area, oxygen reduction kinetics, and fuel cell performance at a highly oxidizing condition, indicating multiwalled carbon nanotubes show high corrosion resistance and strong interaction with Pt nanoparticles. The Tafel slope, ohmic resistances, and limiting current density determined were used to differentiate kinetic, ohmic, mass-transfer polarization losses from the actual polarization curve. Kinetic contribution to the total overpotential was larger throughout the stress test. However, the fraction of kinetic overpotential decreased and mass-transfer overpotential portion remained quite constant during accelerated stress test, whereas the fraction of ohmic overpotential primarily originating from severe proton transport limitation in the catalyst layer increased under the anodic potential hold.

  4. Breakdown voltage reduction by field emission in multi-walled carbon nanotubes based ionization gas sensor

    SciTech Connect

    Saheed, M. Shuaib M.; Muti Mohamed, Norani; Arif Burhanudin, Zainal

    2014-03-24

    Ionization gas sensors using vertically aligned multi-wall carbon nanotubes (MWCNT) are demonstrated. The sharp tips of the nanotubes generate large non-uniform electric fields at relatively low applied voltage. The enhancement of the electric field results in field emission of electrons that dominates the breakdown mechanism in gas sensor with gap spacing below 14 μm. More than 90% reduction in breakdown voltage is observed for sensors with MWCNT and 7 μm gap spacing. Transition of breakdown mechanism, dominated by avalanche electrons to field emission electrons, as decreasing gap spacing is also observed and discussed.

  5. Magnetoresistance and Phase Breaking Behavior of a Nitrogen Doped Multi-Walled Carbon Nanotube

    NASA Astrophysics Data System (ADS)

    Yuko Togashi,; Tetsuya Hatori,; Yoshihide Nakamura,; Nobuyuki Aoki,; Janathan P. Bird,; Mauricio Terrones,; Katsumi Kanako,; Yuichi Ochiai,

    2010-02-01

    The low temperature magnetoresistance (MR) has been studied in a nitrogen doped multi-walled carbon nanotube (CNxMWNT) with a four terminal resistance measurement. The phase coherent properties of electron transport in the CNxMWNT have been deduced from results of quantum-transport analysis. A zero-field peak of the weak localization can be observed in the low-temperature MR, however, there exhibits a clear boundary between the phase braking processes around 10 K. The phase coherence has been analyzed and the quasi-one-dimensional properties have been discussed in weakly localized metallic transport with a low temperature MR in terms of quantum interference.

  6. Air-brush multi-walled carbon nanotube capacitive sensor for dimethyl methylphosphonate detection

    NASA Astrophysics Data System (ADS)

    Jing, Hongjun; Jiang, Yadong; Du, Xiaosong

    2012-10-01

    Multi-walled carbon nanotube (MWNT) films were prepared on interdigital electrodes by air-brush technique, and their sensing properties to dimethyl methylphosphonate (DMMP) were studied. The MWNT films were observed by scanning electron microscope. The capacitive response to different concentrations of DMMP vapor was investigated at room temperature. The results showed that the capacitance and loss tangent of the air-brush MWNT sensor both decreased rapidly in varying concentrations ranging from 2.4 to 12 ppm. The sensitivity of capacitance was higher than that of the loss tangent at all the concentrations of DMMP vapors. The sensor exhibited high sensitivity and fast response for DMMP vapor detection.

  7. Direct evaluation of ballistic phonon transport in a multi-walled carbon nanotube

    SciTech Connect

    Hayashi, Hiroyuki; Takahashi, Koji; Ikuta, Tatsuya; Nishiyama, Takashi; Takata, Yasuyuki; Zhang, Xing

    2014-03-17

    Phonon confinement and in situ thermal conductance measurements in an individual multi-walled carbon nanotube (MWNT) are reported. Focused ion beam (FIB) irradiation was used to successively shorten a 4.8 μm long MWNT, eventually yielding a 0.3 μm long MWNT. After the first FIB irradiation, a 41% reduction in conductance was achieved, compared with that of the pristine MWNT. This was because the contributions from phonons with long free paths were excluded by scattering at FIB-induced defects. Phonon transport in linked multiple-length nanotubes was also investigated.

  8. Multiwalled carbon nanotubes sensor for organic liquid detection at room temperature

    NASA Astrophysics Data System (ADS)

    Chaudhary, Deepti; Khare, Neeraj; Vankar, V. D.

    2016-04-01

    We have explored the possibility of using multiwalled carbon nanotubes (MWCNTs) as room temperature chemical sensor for the detection of organic liquids such as ethanol, propanol, methanol and toluene. MWCNTs were synthesized by thermal chemical vapor deposition (TCVD) technique. The interdigitated electrodes were fabricated by conventional photolithography technique. The sensor was fabricated by drop depositing MWCNT suspension onto the interdigitated electrodes. The sensing properties of MWCNTs sensor was studied for organic liquids detection. The resistance of sensor was found to increase upon exposure to these liquids. Sensor shows good reversibility and fast response at room temperature. Charge transfer between the organic liquid and sensing element is the dominant sensing mechanism.

  9. Growth of apatite on chitosan-multiwall carbon nanotube composite membranes

    NASA Astrophysics Data System (ADS)

    Yang, Jun; Yao, Zhiwen; Tang, Changyu; Darvell, B. W.; Zhang, Hualin; Pan, Lingzhan; Liu, Jingsong; Chen, Zhiqing

    2009-07-01

    Bioactive membranes for guided tissue regeneration would be of value for periodontal therapy. Chitosan-multiwall carbon nanotube (CS-MWNT) composites were treated to deposit nanoscopic apatite for MWNT proportions of 0-4 mass%. Fourier-transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray analysis, and X-ray diffraction were used for characterization. Apatite was formed on the CS-MWNT composites at low MWNT concentrations, but the dispersion of the MWNT affects the crystallite size and the Ca/P molar ratio of the composite. The smallest crystallite size was 9 nm at 1 mass% MWNT.

  10. Charge transport properties of water dispersible multiwall carbon nanotube-polyaniline composites

    NASA Astrophysics Data System (ADS)

    Sangeeth, C. S. Suchand; Jiménez, Pablo; Benito, Ana M.; Maser, Wolfgang K.; Menon, Reghu

    2010-05-01

    The transmission electron microscopy images of in situ prepared multiwall carbon nanotubes (MWNTs) and polyaniline (PANI) composites show that nanotubes are well dispersed in aqueous medium, and the nanofibers of PANI facilitate intertube transport. Although low temperature transport indicates variable range hopping (VRH) mechanism, the dc and ac conductivity become temperature independent as the MWNT content increases. The onset frequency for the increase in conductivity is observed to be strongly dependent on the MWNT weight percent, and the ac conductivity can be scaled onto a master curve. The negative magnetoresistance is attributed to the forward interference scattering mechanism in VRH transport.

  11. Synthesis of multi-walled carbon nanotubes and their application in resin based nanocomposites

    NASA Astrophysics Data System (ADS)

    Nisar Ahmad, Shahid; Hakeem, Saira; Alvi, Rashid Ahmed; Farooq, Khawar; Farooq, Naveed; Yasmin, Farida; Saeed, Sadaf

    2013-06-01

    Multi-walled carbon nanotubes (MWCNTs) were synthesized by catalytic decomposition of hydrocarbon gas using chemical vapor deposition method. Synthesis was done at different growth temperatures and catalyst ratios. These MWCNTs were dispersed in epoxy resin (E-51) and their effect on mechanical strength of epoxy nanocomposites was studied. Increase in the mechanical strength of epoxy was observed with the addition of CNTs. The surface characterization was done by using optical microscope and scanning electron microscope (SEM). Mechanical properties were determined by the general tensile strength testing method.

  12. Seeking optimal performance of multiwall carbon nanotubes in field emission: Tight-binding approach

    NASA Astrophysics Data System (ADS)

    Liang, Shi-Dong; Deng, Shao Zhi; Xu, Ning Sheng

    2006-10-01

    The field emission performance of different components of multiwall carbon nanotubes (MWCNs) is systematically studied by quantum tunneling theory with the tight-binding approach. We find that the current-voltage characteristic in field emission of MWCNs still approximately follows the Fowler-Nordheim theory. The key characteristics of all MWCNs are almost independent of the component and the layer number of MWCNs that have more three layers. The interlayer coupling of MWCNs can induce a semiconductor-metal phase transition, which leads to most MWCNs being actually metallic, and the chiral and quantum size effects disappear.

  13. Biofunctionalization of multiwalled carbon nanotubes by electropolymerized poly(pyrrole-concanavalin A) films.

    PubMed

    Papper, Vladislav; Elouarzaki, Kamal; Gorgy, Karine; Sukharaharja, Ayrine; Cosnier, Serge; Marks, Robert S

    2014-10-13

    The synthesis and electropolymerization of a pyrrolic concanavalin A derivative (pyrrole-Con A) onto a multiwalled carbon nanotube (MWCNT) deposit is reported. Glucose oxidase was then immobilized onto the MWCNT-poly(pyrrole-Con A) coating by affinity carbohydrate interactions with the polymerized Con A protein. The resulting enzyme electrode was applied to the amperometric detection of glucose exhibiting a high sensitivity of 36 mA cm(-2) mol(-1) L and a maximum current density of 350 μA cm(-2) . PMID:25179428

  14. Carboxylic multi-walled carbon nanotubes as immobilized stationary phase in capillary electrochromatography.

    PubMed

    Sombra, Lorena; Moliner-Martínez, Yolanda; Cárdenas, Soledad; Valcárcel, Miguel

    2008-09-01

    Carboxylic multi-walled carbon nanotubes (c-MWNT) have been immobilized into a fused-silica capillary for capillary electrochromatography. The c-MWNT were successfully incorporated after the silanization and coupling with glutaraldehyde on the inner surface of the capillary. The electrochromatographic features of the c-MWNT immobilized stationary phase have been evaluated for the analysis of different compounds of pharmaceutical interest. The results indicated high electrochromatographic resolution, good capillary efficiency and retention factors. In addition, highly reproducible results between runs, days and capillaries were obtained.

  15. Fabrication of multi-walled carbon nanotubes-aluminum matrix composite by powder metallurgy technique

    NASA Astrophysics Data System (ADS)

    Bunakov, N. A.; Kozlov, D. V.; Golovanov, V. N.; Klimov, E. S.; Grebchuk, E. E.; Efimov, M. S.; Kostishko, B. B.

    We report on fabrication of an aluminum matrix composite containing multi-walled carbon nanotubes (MWCNTs) produced by MOCVD method and functionalized via acid treatment by a H2SO4/HNO3 mixture. Specimens were prepared by spark plasma sintering (SPS) of the aluminum powder with different amounts of functionalized MWCNTs (FMWCNTs) in the range of 0.1-1 wt.%. We studied the effect of FMWCNTs amount on microstructure and mechanical properties of composites. It is shown that functionalization allows homogeneous dispersing of the MWCNTs in Al powder. The maximal increase in micro-hardness and tensile strength is registered at 0.1 wt.%.

  16. Interlayer Forces and Ultralow Sliding Friction in MultiwalledCarbon Nanotubes

    SciTech Connect

    Kis, A.; Jensen, K.; Aloni, S.; Mickelson, W.; Zettl, A.

    2006-03-30

    We describe interlayer force measurements during prolonged,cyclic telescoping motion of a multiwalled carbon nanotube. The forceacting between the core and the outer casing is modulated by the presenceof stable defects and generally exhibits ultralow friction, below themeasurement limit of 1.4x10-15 N/atom and total dissipation per cyclelower than 0.4 meV/atom. Defects intentionally introduced in the form ofdangling bonds lead to temporary mechanical dissipation, but the innateability of nanotubes to self heal rapidly optimizes the atomic structureand restores smooth motion.

  17. Biofunctionalization of multiwalled carbon nanotubes by electropolymerized poly(pyrrole-concanavalin A) films.

    PubMed

    Papper, Vladislav; Elouarzaki, Kamal; Gorgy, Karine; Sukharaharja, Ayrine; Cosnier, Serge; Marks, Robert S

    2014-10-13

    The synthesis and electropolymerization of a pyrrolic concanavalin A derivative (pyrrole-Con A) onto a multiwalled carbon nanotube (MWCNT) deposit is reported. Glucose oxidase was then immobilized onto the MWCNT-poly(pyrrole-Con A) coating by affinity carbohydrate interactions with the polymerized Con A protein. The resulting enzyme electrode was applied to the amperometric detection of glucose exhibiting a high sensitivity of 36 mA cm(-2) mol(-1) L and a maximum current density of 350 μA cm(-2) .

  18. Time-resolved laser-induced incandescence from multiwalled carbon nanotubes in air

    SciTech Connect

    Mitrani, J. M.; Shneider, M. N.

    2015-01-26

    We observed temporal laser-induced incandescence (LII) signals from multiwalled carbon nanotubes(MWCNTs) suspended in ambient air. Unlike previous LII experiments with soot particles, which showed that primary particles with larger diameters cool at slower timescales relative to smaller particles, we observed that thicker MWCNTs with larger outer diameters (ODs) cool at faster timescales relative to thinner MWCNTs with smaller ODs. We suggested a simple explanation of this effect, based on the solution of one-dimensional nonstationary heat conduction equation for the initial non-uniform heating of MWCNTs with ODs greater than the skin depth.

  19. Strong visible light emission from well-aligned multiwalled carbon nanotube films under infrared laser irradiation

    SciTech Connect

    Zhang Yong; Gong Tao; Liu Wenjin; Zhang Xianfeng; Chang Jianguo; Wang Kunlin; Wu Dehai

    2005-10-24

    We report strong and brilliant visible light emission from well-aligned multiwalled carbon nanotube (AMWNT) films under infrared (IR) laser irradiation with wavelength at 1.06 and 10.6 {mu}m, respectively. The AMWNT film shows a high durability against laser irradiation and achieved a conversion from IR laser to visible light. It is a good candidate for optical converter. Light emission spectra versus different wavelengths and various powers were found to have similar line shapes. It could be explained as combination of laser-induced photoluminescence and resistive heating.

  20. Preparation and characterization of multiwall carbon nanotube/polypyrrole coaxial fibrils

    NASA Astrophysics Data System (ADS)

    Bhatia, Ravi; Sangeeth, C. S. Suchand; Prasad, V.; Menon, Reghu

    2011-04-01

    Multiwall carbon nanotube (MWNT)/polypyrrole (PPy) fibrils were fabricated by template-free in situ electrochemical deposition of PPy over MWNTs, and characterized by electron microscopy and electrical measurements. Scanning and transmission electron microscopy studies reveal that PPy coating on the surface of nanotube is quite uniform throughout the length, with the possibility of forming unique Y-junctions. Current (I)-voltage (V) characteristics at various temperatures show nonlinearity due to tunneling and hopping contributions to transport across the barriers. AC conductivity measurements (300-4.2 K) show that the onset frequency scales with temperature, and the nanoscale connectivity in MWNT/PPy fibrils decreases with the lowering of temperature.

  1. Spectrophotometric Detection of Rhodamine B after Separation-Enrichment by Using Multi-walled Carbon Nanotubes.

    PubMed

    Unsal, Yunus Emre; Soylak, Mustafa; Tuzen, Mustafa

    2014-01-01

    A new, simple UV-Vis spectrophotometric method for the separation-preconcentration and determination of rhodamine B based on its adsorption onto multi-walled carbon nanotubes has been described. The effects of parameters for the quantitative recoveries of rhodamine B, including pH, flow, sample volumes, etc., were optimized. Matrix effects of concomitant ions or other dyes were also examined. The preconcentration factor and LOD were calculated as 125 and 0.80 μg/L, respectively. The procedure was applied to the spectrophotometric detection of rhodamine B in a soft drink, dialysis water, textile industry wastewater, and nail polish samples. PMID:25903000

  2. Electrical Transport Properties of Polyaniline Containing HCl, CuCl2 and Multiwall Carbon Nanotube

    NASA Astrophysics Data System (ADS)

    Meikap, A. K.

    2011-07-01

    Electrical transport properties of hydrochloric acid (HCl) doped polyaniline (PANI) and composite of PANI with Copper Chloride (CuCl2) and multiwall Carbon Nanotube (MWNT) was measured within a temperature range 77⩽T⩽300 K in presence and in absence of a magnetic field up to 1Tesla. The electrical transport properties can be explained by the variable range hopping (VRH) theory. All the samples have shown negative d.c magnetoconductivity at the room temperature but PANI-HCl sample has shown a transition from positive to negative magnetoconductivity as the temperature is increased.

  3. Monolayer formation of human osteoblastic cells on vertically aligned multiwalled carbon nanotube scaffolds.

    PubMed

    Lobo, Anderson O; Antunes, Erica F; Palma, Mariana Bs; Pacheco-Soares, Cristina; Trava-Airoldi, Vladimir J; Corat, Evaldo J

    2010-04-01

    Monolayer formation of SaOS-2 (human osteoblast-like cells) was observed on VACNT (vertically aligned multiwalled carbon nanotubes) scaffolds without purification or functionalization. The VACNT were produced by a microwave plasma chemical vapour deposition on titanium surfaces with nickel or iron as catalyst. Cell viability and morphology studies were evaluated by LDH (lactate dehydrogenase) release assay and SEM (scanning electron microscopy), respectively. The non-toxicity and the flat spreading with monolayer formation of the SaOs-2 on VACNT scaffolds surface indicate that they can be used for biomedical applications. PMID:19947917

  4. Measurement of magnetic anisotropy of multiwalled carbon nanotubes in nematic host

    NASA Astrophysics Data System (ADS)

    Cirtoaje, Cristina; Petrescu, Emil

    2016-10-01

    The magnetic anisotropy of multiwalled carbon nanotubes (MWCNT-s) is measured using their dispersion in nematic liquid crystal (NLC). Due to their ability to align themselves with inserted nano-particles, NLC are very useful for the study of the physical properties of MWCNT as well as for other micro or nano-particles. Thus an organized system is obtained from the beginning and the influence of initial random orientation is considerably reduced. The average magnetic anisotropy of MWCNT dispersed in NLC was calculated from the system relaxation time and the obtained value (6.61 ×10-5) was in good agreement with other reported results.

  5. Broad-frequency dielectric behaviors in multiwalled carbon nanotube/rubber nanocomposites

    NASA Astrophysics Data System (ADS)

    Jiang, Mei-Juan; Dang, Zhi-Min; Bozlar, Michael; Miomandre, Fabien; Bai, Jinbo

    2009-10-01

    Broad-frequency dielectric behaviors of multiwalled carbon nanotubes (MWCNTs) embedded in room temperature vulcanization silicone rubber (RT-SR) matrix were studied by analyzing alternating current (ac) impedance spectra, which would make a remarkable contribution for understanding some fundamental electrical properties in the MWCNT/RT-SR nanocomposites. Equivalent circuits of the MWCNT/RT-SR nanocomposites were built, and the law of polarization and mechanism of electric conductance under the ac field were acquired. Two parallel RC circuits in series are the equivalent circuits of the MWCNT/RT-SR composites. At different frequency ranges, dielectric parameters including conductivity, dielectric permittivity, dielectric loss, impedance phase, and magnitude present different behaviors.

  6. Photothermal Actuation of Cantilevered Multiwall Carbon Nanotubes with Bimaterial Configuration toward Calorimeter

    NASA Astrophysics Data System (ADS)

    Hiroshima, Seiya; Yoshinaka, Atsushi; Arie, Takayuki; Akita, Seiji

    2013-06-01

    We investigated the bimaterial effect on a multiwall carbon nanotube (CNT) cantilever by means of a photothermal actuation method toward sensitivity enhancement for calorimetry. The coating of a 10-nm-thick Ti layer on top of the CNT cantilever of 50 nm diameter successfully enhanced the photothermal vibration amplitude by 10-50 times. This implies that the expected resolution for the heat capacity measurement is as high as ˜0.1 fJ/K on the base of a simple lumped model for the photothermally excited Ti-coated CNT cantilever.

  7. Ultrasonic-assisted chemical oxidative cutting of multiwalled carbon nanotubes with ammonium persulfate in neutral media

    NASA Astrophysics Data System (ADS)

    Liu, Peng; Wang, Tingmei

    2009-12-01

    A new, facile, and mild approach was developed to cut the conventional long and entangled multiwalled carbon nanotubes (MWCNTs) to short and dispersed ones with length of less than 1 μm by ultrasonic-assisted chemical oxidation with ammonium persulfate (APS) in neutral aqueous solution at room temperature. The resulting products were characterized with Fourier transform infrared (FTIR), Raman, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and transmission electron microscope (TEM) techniques. The shortened MWCNTs formed stable dispersion state in water without the help of surfactants that provided possibility for further functionalizations and applications.

  8. Effect of Multiwall Carbon Nanotubes on Electrical and Structural Properties of Polyaniline

    NASA Astrophysics Data System (ADS)

    Nagaraja, M.; Mahesh, H. M.; Manjanna, J.; Rajanna, K.; Kurian, M. Z.; Lokesh, S. V.

    2012-07-01

    Polyaniline (PANI) and PANI/CNT (multiwall carbon nanotubes, CNT) composites were prepared using an oxidative chemical polymerization method with ammonium persulfate and dodecyl benzene sulfonic acid as the oxidizing agent and surfactant, respectively. Fourier-transform infrared spectroscopy spectra illustrate the presence of PANI in the composite and show that some interaction exists between PANI and CNT. Embedding of CNT in the PANI matrix is confirmed by scanning electron micrography. Conductivity of the PANI/CNT composites was higher than that of pure PANI, and the maximum conductivity obtained was 4.44 S/cm at 20 wt.% CNT.

  9. Multiband microwave absorption films based on defective multiwalled carbon nanotubes added carbonyl iron/acrylic resin

    NASA Astrophysics Data System (ADS)

    Li, Yong; Chen, Changxin; Pan, Xiaoyan; Ni, Yuwei; Zhang, Song; Huang, Jie; Chen, Da; Zhang, Yafei

    2009-05-01

    Defective multiwalled carbon nanotubes (MWCNTs) were introduced to the carbonyl iron (CI) based composites to improve its microwave absorption by a simple ultrasonic mixing process. The electromagnetic parameters were measured in the 2-18 GHz range. Microwave absorption of CI based composites with 2 mm in thickness was evidently enhanced by adding as little as 1.0 wt% defective MWCNTs with two well separated absorption peaks exceeding -20 dB, as compared with that of pure CI based and defective MWCNTs composites. The enhancement mechanism is thought due to the interaction and better electromagnetic match between defective MWCNTs and ferromagnetic CI particles.

  10. Application of multiwalled carbon nanotubes-graphene hybrid nanocomposite for nonenzymatic H2O2 biosensor

    NASA Astrophysics Data System (ADS)

    Nayak, Pranati; Santhosh, P. N.; Ramaprabhu, S.

    2013-02-01

    In the present work, we report the fabrication of nonenzymatic hydrogen peroxide (H2O2) biosensor using multiwalled carbon nanotubes-solar exfoliated graphene hybrid nanocomposite (MWCNTs-sG) as a transducer candidate. The hybrid material has been synthesized by solar reduction technique from a mixture of MWCNTs and graphite oxide (GO). The fabricated MWCNTs-sG based biosensor shows a high catalytic response towards H2O2 reduction at a low potential of -0.4 V and good linearity over a wide range of concentration from 2 mM to 344 mM.

  11. Monolayer formation of human osteoblastic cells on vertically aligned multiwalled carbon nanotube scaffolds.

    PubMed

    Lobo, Anderson O; Antunes, Erica F; Palma, Mariana Bs; Pacheco-Soares, Cristina; Trava-Airoldi, Vladimir J; Corat, Evaldo J

    2010-03-12

    Monolayer formation of SaOS-2 (human osteoblast-like cells) was observed on VACNT (vertically aligned multiwalled carbon nanotubes) scaffolds without purification or functionalization. The VACNT were produced by a microwave plasma chemical vapour deposition on titanium surfaces with nickel or iron as catalyst. Cell viability and morphology studies were evaluated by LDH (lactate dehydrogenase) release assay and SEM (scanning electron microscopy), respectively. The non-toxicity and the flat spreading with monolayer formation of the SaOs-2 on VACNT scaffolds surface indicate that they can be used for biomedical applications.

  12. Flexible infrared detectors based on p-n junctions of multi-walled carbon nanotubes.

    PubMed

    Huang, Zhenlong; Gao, Min; Yan, Zhuocheng; Pan, Taisong; Liao, Feiyi; Lin, Yuan

    2016-05-14

    Different types of multi-walled carbon nanotubes (CNTs), synthesized by chemical vapor deposition, are used to fabricate infrared (IR) detectors on flexible substrates based on CNT p-n junctions. It is found that this kind of detector is sensitive to infrared signals with a power density as low as 90 μW mm(-2) even at room temperature. Besides, unlike other devices, the detector with this unique structure can be bent for 100 cycles without any damage and its functionality does not degenerate once it recovers to the initial state. The results give a good reference for developing efficient, low-cost, and flexible IR detectors. PMID:27101973

  13. Covalent layer-by-layer functionalization of multiwalled carbon nanotubes by click chemistry.

    PubMed

    Zhang, Yu; He, Hongkun; Gao, Chao; Wu, Jiayan

    2009-05-19

    The covalent functionalization of multiwalled carbon nanotubes (MWNTs) by layer-by-layer (LbL) click chemistry is reported. The clickable polymers of poly(2-azidoethyl methacrylate) and poly(propargyl methacrylate) were synthesized at first by atom transfer radical polymerization (ATRP) of 2-azidoethyl methacrylate and reverse addition-fragmentation chain transfer (RAFT) polymerization of propargyl methacrylate, respectively. The two polymers were then alternately coated on alkyne-modified multiwalled carbon nanotubes using Cu(I)-catalyzed click reaction of Huisgen 1,3-dipolar cycloaddition between azides and alkynes. Thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) measurements confirm that the quantity and thickness of the clicked polymer shell on MWNTs can be well controlled by adjusting the cycles or numbers of click reaction and the polymer shell is uniform and even. X-ray photoelectron spectroscopy (XPS) and Fourier tranform infrared (FTIR) measurements showed that there were still a great amount of residual azido groups on the surfaces of the functionalized MWNTs after clicking three layers of polymers. Furthermore, alkyne-modified rhodamine B and monoalkyne-terminated polystyrene were subsequently used to functionalize the clickable polymer grafted MWNTs, giving rise to fluorescent carbon nanotubes (CNTs) and CNT-based polystyrene brushes, respectively. It demonstrates that the residual azido groups on the surfaces of MWNTs are available for further click reaction with various functional molecules. PMID:19374339

  14. Controlled Patterning and Growth of Single Wall and Multi-wall Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Delzeit, Lance D. (Inventor)

    2005-01-01

    Method and system for producing a selected pattern or array of at least one of a single wall nanotube and/or a multi-wall nanotube containing primarily carbon. A substrate is coated with a first layer (optional) of a first selected metal (e.g., Al and/or Ir) and with a second layer of a catalyst (e.g., Fe, Co, Ni and/or Mo), having selected first and second layer thicknesses provided by ion sputtering, arc discharge, laser ablation, evaporation or CVD. The first layer and/or the second layer may be formed in a desired non-uniform pattern, using a mask with suitable aperture(s), to promote growth of carbon nanotubes in a corresponding pattern. A selected heated feed gas (primarily CH4 or C2Hn with n=2 and/or 4) is passed over the coated substrate and forms primarily single wall nanotubes or multiple wall nanotubes, depending upon the selected feed gas and its temperature. Nanofibers, as well as single wall and multi-wall nanotubes, are produced using plasma-aided growth from the second (catalyst) layer. An overcoating of a selected metal or alloy can be deposited, over the second layer, to provide a coating for the carbon nanotubes grown in this manner.

  15. Effects of suspended multi-walled carbon nanotubes on daphnid growth and reproduction.

    PubMed

    Alloy, Matthew M; Roberts, Aaron P

    2011-10-01

    Relatively little is known about the potential impacts of engineered nanoparticles on aquatic biota. Particularly relevant to aquatic ecosystems are those particles, which display increased solubility either through specialized coatings or through an ability to interact with water column constituents such as natural organic matter (NOM). Previous research has indicated that grazing zooplankton (Daphnia magna) are able to ingest lipid-coated single-walled carbon nanotubes (SWNTs) from the water column during their normal feeding behavior (Roberts et al., 2007). Acute mortality was observed only at high concentrations (>5mg/L). In this research NOM was used in place of a surfactant to stabilize suspensions. Water chemistry (ionic strength, hardness, and pH) has been shown to alter the behavior of NOM in natural systems. We hypothesized that these same variables may also affect the toxicity of multi-walled carbon nanotubes (MWNT) stabilized in NOM. The purpose of this research was to examine the potential for sublethal effects to occur following exposure to multi-walled carbon nanotubes suspended in NOM and to determine whether those effects vary with pH alterations.

  16. Strain and Temperature Sensing Properties of Multiwalled Carbon Nanotube Yarn Composites

    NASA Technical Reports Server (NTRS)

    Kahng, Seun K.; Gates, Thomas S.; Jefferson, Gail D.

    2008-01-01

    Strain and temperature response of Multiwalled Carbon Nanotube (MWCNT/CNT) yarns on a stainless steel test beam has been studied. The carbon nanotube yarns are spun from a multiwalled carbon nanotube forest grown on a silicon substrate to a 4-ply yarn with a diameter of about 15-20 microns. Four of the 4-ply CNT yarns are arranged in a Wheatstone bridge configuration on the stainless steel test beam using a thin layer of polyurethane resin that insulates and protects the yarns from the test beam. Strain sensitivities of the CNT yarn sensors range from 1.39 to 1.75 mV/V/1000 microstrain at room temperature, and temperature sensitivity of the CNT yarn bridge is 91 microA/degC. Resistance of the yarns range from 215 to 270 ohms for CNT yarn length of approximately 5 mm. Processes used in attaching the CNT yarns on the test beam and experimental procedures used for the measurements are described. Conventional metallic foil strain gages are attached to the test beam to compare with the CNT sensors. The study demonstrates multifunctional capability of the sensor for strain and temperature measurements and shows its applicability where engineering strain is less than 3%.

  17. Decorating multi-walled carbon nanotubes with nickel nanoparticles for selective hydrogenation of citral

    SciTech Connect

    Tang Yuechao; Yang Dong; Qin Feng; Hu Jianhua; Wang Changchun; Xu Hualong

    2009-08-15

    The nanocomposites of multi-walled carbon nanotubes (MWNTs) decorated with nickel nanoparticles were conveniently prepared by a chemical reduction of nickel salt in the present of poly(acrylic acid) grafted MWNTs (PAA-g-MWNTs). Due to the strong interaction between Ni{sup 2+} and -COOH, PAA-g-MWNTs became an excellent supporting material for Ni nanoparticles. The morphology and distribution of Ni nanoparticles on the surface of MWNTs were greatly influenced by the reduction temperatures, the experimental results also showed that the distribution of Ni nanoparticles was greatly improved while the MWNTs were modified by poly(acrylic acid) (PAA). The hydrogenation activity and selectivity of MWNTs decorated with Ni nanoparticles (Ni-MWNTs) for alpha, beta-unsaturated aldehyde (citral) were also studied, and the experimental results showed that the citronellal, an important raw material for flavoring and perfumery industries, is the favorable product with a percentage as high as 86.9%, which is 7 times higher than that of catalyst by Ni-supported active carbon (Ni-AC). - Abstract: Nickel nanoparticles decorated multi-walled carbon nanotubes (Ni-MWNTs) nanocomposites were conveniently prepared by a chemical reduction of nickel salt in the present of poly(acrylic acid) grafted MWNTs (PAA-g-MWNTs). These nanocomposites possessed excellent catalytic activity and selectivity for hydrogenation of citral.

  18. Supercapacitor electrode with a homogeneously Co3O4-coated multiwalled carbon nanotube for a high capacitance

    NASA Astrophysics Data System (ADS)

    Tao, Li; Shengjun, Li; Bowen, Zhang; Bei, Wang; Dayong, Nie; Zeng, Chen; Ying, Yan; Ning, Wan; Weifeng, Zhang

    2015-05-01

    Cobalt oxide (Co3O4) was homogeneously coated on multiwalled carbon nanotube through a simple chemical deposition method and employed in supercapacitor electrodes. SEM image indicated the uniform distribution of Co3O4 nanoparticles on the surface of the multiwalled carbon nanotube. A maximum specific capacitance of 273 Fg-1 was obtained at the charge-discharge current density of 0.5 Ag-1. After 500 cycles of continuous charge-discharge process, about 88% of the initial capacity could be retained.

  19. Superhydrophobicity of a material made from multiwalled carbon nanotubes

    SciTech Connect

    Hong, Yong Cheol; Uhm, Han Sup

    2006-06-12

    Superhydrophobic carbon nanotubes (CNTs) were prepared by low-pressure CF{sub 4} glow plasma to provide roughness and fluorination in CNTs. The water droplet falling freely on the superhydrophobic CNT powders bounced dynamically. The superhydrophobicity resulted from the combined effects of the chemical modification and surface roughness. Using the contact angles obtained from the capillary rise method based on the Washburn equation, the total surface free energy of CNT powder treated by CF{sub 4} plasma for 20 min was calculated to be drastically decreased from 27.04 to 4.06x10{sup -7}mJ/m{sup 2}.

  20. Tunneling phenomena in aligned multi-walled carbon nanotube sheets: conductivity and Raman correlations

    NASA Astrophysics Data System (ADS)

    del Corro, E.; Castillo-Martínez, E.; Taravillo, M.; Baonza, V. G.

    2014-12-01

    We performed simultaneous Raman spectroscopy and electrical conductivity measurements on self-standing aligned multi-walled carbon nanotubes sheets at varying inter-tube distances. A sapphire anvil cell is used here to modulate the inter-tube distance and promote the subsequent electronic tunneling phenomena. We observe a singular correlation between the intensity of the so called defect bands of carbon materials and their conductivity. This indicates that the conditions of the resonant processes that originate these bands are modified by the tunneling phenomena. Such an issue has never been reported before and has potential technological applications. Additionally, the provided AFM images evidence the debundling of the carbon nanotubes that had been described to occur after small compression.

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

    DOE PAGES

    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

  2. Effect of Acid Oxidation on the Dispersion Property of Multiwalled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Goh, P. S.; Ismail, A. F.; Aziz, M.

    2009-06-01

    A means of dispersion of multiwalled carbon nanotube (MWCNT) via mixed acid (HNO3 and H2SO4) oxidation with different treatment durations was investigated through the solubility study of the treated carbon nanotubes in some common solvents. Fourier transformed infrared (FTIR) characterization of the reaction products revealed that the surface of MWCNTs was successfully functionalized with surface acidic groups. The acid-base titration demonstrated that the amount of surface acidic groups increased in parallel with the refluxing duration. The acid modified MWCNTs were found to be well dispersed in polar solvents, such as ethanol and water due to the presence of the hydrophilic acid functional groups on the surface of raw MWCNTs. Such chemical modification of carbon nanotube properties will pave the way towards the realistic applications in the nanotechnology world.

  3. Dielectric constants of multiwall carbon nanotubes from direct current to microwave frequencies.

    PubMed

    Wang, Y C; Lue, J T; Pauw, K F

    2009-03-01

    A cylindrical rod constructed from a uniform mixture of multiwall carbon nanotubes and alumina powders dissolved in paraffin was inserted in the center of a radio frequency cavity. The real and imaginary dielectric constants of carbon tubes at various frequencies were measured, respectively, from the resonant frequencies and the quality factors, by a resistance-inductance-cacitance (RLC) meter and a microwave network analyzer. The dielectric rod benefits the protection of the sample from adsorbing moisture and preventing the rod from filling with air, thus making accurate measurments. A tunable probe specifically designed for the field pattern of a TM010 mode is delineated to improve the microwave coupling of the dielectric microwave resonator. This refined design is expected to facilitate the measurement yielding a significant manner. The real and imaginary parts of the dielectric constant of carbon nanotubes increase and decrease, respectively as frequencies increase satisfactorily in complying with the description from the free electron Drude model.

  4. Atomic-Scale Investigations of Multiwall Carbon Nanotube Growth

    NASA Astrophysics Data System (ADS)

    Behr, Michael John

    The combination of unique mechanical, thermal, optical, and electronic properties of carbon nanotubes (CNTs) make them a desirable material for use in a wide range of applications. Many of these unique properties are highly sensitive to how carbon atoms are arranged within the graphene nanotube wall. Precise structural control of this arrangement remains the key challenge of CNT growth to realizing their technological potential. Plasma-enhanced chemical vapor deposition (PECVD) from methane-hydrogen gas mixtures using catalytic nanoparticles enables large-scale growth of CNT films and controlled spatial placement of CNTs on a substrate, however, much is still unknown about what happens to the catalyst particle during growth, the atomistic mechanisms involved, and how these dictate the final nanotube structure. To investigate the fundamental processes of CNT growth by PECVD, a suite of characterization techniques were implemented, including attenuated total-reflection Fourier transform infrared spectroscopy (ATR-FTIR), optical emission spectroscopy (OES), Raman spectroscopy, convergent-beam electron diffraction (CBED), high-resolution transmission and scanning-transmission electron microscopy (TEM, STEM), energy dispersive x-ray spectroscopy, and electron energy-loss spectroscopy (EELS). It is found that hydrogen plays a critical role in determining the final CNT structure through controlling catalyst crystal phase and morphology. At low hydrogen concentrations in the plasma iron catalysts are converted to Fe3C, from which high-quality CNTs grow; however, catalyst particles remain as pure iron when hydrogen is in abundance, and produce highly defective CNTs with large diameters. The initially faceted and equiaxed catalyst nanocrystals become deformed and are elongated into a teardrop morphology once a tubular CNT structure is formed around the catalyst particles. Although catalyst particles are single crystalline, they exhibit combinations of small-angle (˜1°-3

  5. The Influence of Multiwalled Carbon Nanotubes on Polycyclic Aromatic Hydrocarbon (PAH) Bioavailability and Toxicity to Soil Microbial Communities in Alfalfa Rhizosphere

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Carbon nanotubes (CNTs) may affect bioavailability and toxicity of organic contaminants due to their adsorption properties. Recent studies have observed the influence of multiwalled carbon nanotubes (MWNTs) on the fate of polycyclic aromatic hydrocarbons (PAHs) and other organic contaminants. Greenh...

  6. Flexible infrared detectors based on p-n junctions of multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Huang, Zhenlong; Gao, Min; Yan, Zhuocheng; Pan, Taisong; Liao, Feiyi; Lin, Yuan

    2016-05-01

    Different types of multi-walled carbon nanotubes (CNTs), synthesized by chemical vapor deposition, are used to fabricate infrared (IR) detectors on flexible substrates based on CNT p-n junctions. It is found that this kind of detector is sensitive to infrared signals with a power density as low as 90 μW mm-2 even at room temperature. Besides, unlike other devices, the detector with this unique structure can be bent for 100 cycles without any damage and its functionality does not degenerate once it recovers to the initial state. The results give a good reference for developing efficient, low-cost, and flexible IR detectors.Different types of multi-walled carbon nanotubes (CNTs), synthesized by chemical vapor deposition, are used to fabricate infrared (IR) detectors on flexible substrates based on CNT p-n junctions. It is found that this kind of detector is sensitive to infrared signals with a power density as low as 90 μW mm-2 even at room temperature. Besides, unlike other devices, the detector with this unique structure can be bent for 100 cycles without any damage and its functionality does not degenerate once it recovers to the initial state. The results give a good reference for developing efficient, low-cost, and flexible IR detectors. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr08791k

  7. Selective decoration of nickel and nickel oxide nanocrystals on multiwalled carbon nanotubes

    SciTech Connect

    Martis, P.; Venugopal, B.R.; Delhalle, J.; Mekhalif, Z.

    2011-05-15

    A simple route to selective decoration of nickel and nickel oxide nanocrystals on multiwalled carbon nanotubes (MWCNTs) using nickel acetylacetonate (NAA) was successfully achieved for the first time. The homogeneously decorated nanocrystals on MWCNTs were investigated for their structure and morphology by various techniques, such as powder X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, field emission scanning electron microscopy and thermogravimetric analysis. It was found that the size distributions of the nanocrystals on MWCNTs ranged from 8 to 15 nm and they were well resolved. The precursor, NAA, was effectively employed to impregnate the MWCNTs, which on calcination at suitable temperatures and in the presence of hydrogen and nitrogen atmosphere gave rise to nickel and nickel oxide nanocrystals, respectively. -- Graphical abstract: Nickel and nickel oxide nanocrystals were selectively and homogeneously decorated on multiwalled carbon nanotubes using nickel acetylacetonate, as a precursor in a simple and efficient route. Display Omitted Highlights: {yields} A simple route for decoration of nickel and nickel oxide nanocrystals on MWCNTs. {yields} Nickel acetylacetonate used as nickel source for the first time to impregnate on MWCNTs. {yields} Selective decoration was achieved by calcination in hydrogen and nitrogen atmospheres. {yields} The as-decorated nickel and nickel oxide nanocrystals are in the range of 8-15 nm.

  8. Preparation of multiwalled carbon nanotube-supported nickel catalysts using incipient wetness method.

    PubMed

    Azadi, Pooya; Farnood, Ramin; Meier, Emanuel

    2010-03-25

    In this paper, a systematic study on preparation of multiwalled carbon nanotube (MWCNT)-supported nickel catalyst is pursued. Functional groups are introduced on the surface of MWCNTs using nitric acid, sulfuric acid, and partial oxidation in air. Nickel oxide nanoparticles are formed on the surface of functionalized multiwalled carbon nanotubes by incipient wetness impregnation of nickel nitrate, followed by calcination in air. The effects of acid type and concentration, acid treatment time, partial oxidation, nickel loading, precursor solvent, and calcination temperature on the size of the nickel nanoparticles and homogeneity of the composite material are evaluated. Characteristics of the Ni/MWCNT catalysts were examined using BET, scanning transmission electron microscopy, X-ray diffraction, thermogravimetric analysis in air and nitrogen, temperature-programmed reduction, X-ray photoelectron spectroscopy, acid-base titration, and zeta-potential analyzer. Results of this work are useful for formulating CNT-supported nickel catalysts for a wide range of different applications, such as reforming of hydrocarbons, catalytic hydrothermal gasification of biomass, and energy storage.

  9. Dispersion Characteristics of Multi-Walled Carbon Nanotubes with Gallic Acid.

    PubMed

    Jiang, Xiaosong; Shao, Zhenyi; Li, Jingrui; Liu, Wanxia; Zhu, Degui; Liu, Dan

    2015-12-01

    Dispersions of multi-walled carbon nanotubes (MW-CNTs) assisted by non-covalent surface modification and covalent surface modification were prepared using different concentration of gallic acid aqueous solution. Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to investigate the dispersion states and effect of MWNTs. FTIR results demonstrate that concentration of gallic acid has great effect on the surface modification of multi-walled carbon nanotubes. With the content of gallic acid increasing, modification effect were firstly increased and then decreased in that the optimal concentration is about 10 μg/ml as it is its solubility in water. SEM and TEM results also show that gallic acid not only can ensure the integrity of the MW-CNTs, but also can purify it. These results confirmed achievement of a good dispersion state and effect of MW-CNTs with gallic acid. The dispersion mechanism of non-covalent surface modification and covalent surface modification was analyzed.

  10. Hybrid multiwalled carbon nanotube--Laponite sorbent for removal of methylene blue from aqueous solutions.

    PubMed

    Loginov, Maksym; Lebovka, Nikolai; Vorobiev, Eugene

    2014-10-01

    The article discusses adsorption of methylene blue dye by novel hybrid sorbent consisting of Laponite and multiwalled carbon nanotubes. The sorbent was obtained by sonication of the aqueous suspensions of nanotubes at different concentrations of Laponite. The methods of the methylene blue adsorption, dead-end membrane filtration and environmental scanning electron microscopy were used for the sorbent characterization. It may be concluded from the results of filtration and adsorption experiments that sonication of mixed aqueous suspensions of Laponite and multiwalled carbon nanotubes leads to the formation of hybrid particles (ML-particles) with a core-shell structure. The size and the shape of hybrid particles were determined by nanotubes, while their adsorption properties were determined by Laponite particles attached to the surface of nanotubes. The Laponite content in hybrid particles was corresponding to the Laponite to nanotubes ratio in the initial suspension X(L)=0-1. Due to the presence of Laponite in the sorbent, its adsorbing capacity was much higher as compared to the adsorbing capacity of pure nanotubes, and it was directly proportional to the Laponite content. This sorbent may be used either as a purifying additive or as a filtering layer if it is deposited on the surface of a supporting membrane. Due to relatively large size of hybrid particles, they can be easily separated from the purified solution by filtration or centrifugation.

  11. Synthesis of gas barrier starch by dispersion of functionalized multiwalled carbon nanotubes.

    PubMed

    Swain, Sarat K; Pradhan, Ajaya K; Sahu, Hari S

    2013-04-15

    Nanocomposite films were prepared successfully by simple solution casting method from plasticized starch/functionalized multiwalled carbon nanotubes (PS/f-MWCNTs). The interaction of starch with functionalized multiwalled carbon nanotube (f-MWCNT) was evidenced by ultraviolet-visible (UV-vis) spectroscopy and Fourier transforms infrared (FTIR) spectroscopy. The morphological and thermal properties of the composite films were investigated using scanning electron microscope (SEM), high resolution transmission electron microscope (HRTEM), X-ray diffraction (XRD) and thermo gravimetric analysis (TGA). The electrical conductivity of the composites was increased significantly by sixteen times, from 0.1×10(-9) to 1.6×10(-9) S/cm. This reveals better dispersion of f-MWCNT with low concentration of f-MWCNT. The oxygen permeability of the composites was reduced by half as compared to virgin PS. This indicates better dispersion of f-MWCNT in PS matrix due to formation of strong hydrogen bonding with PS matrix.

  12. Preparation of multiwalled carbon nanotube-supported nickel catalysts using incipient wetness method.

    PubMed

    Azadi, Pooya; Farnood, Ramin; Meier, Emanuel

    2010-03-25

    In this paper, a systematic study on preparation of multiwalled carbon nanotube (MWCNT)-supported nickel catalyst is pursued. Functional groups are introduced on the surface of MWCNTs using nitric acid, sulfuric acid, and partial oxidation in air. Nickel oxide nanoparticles are formed on the surface of functionalized multiwalled carbon nanotubes by incipient wetness impregnation of nickel nitrate, followed by calcination in air. The effects of acid type and concentration, acid treatment time, partial oxidation, nickel loading, precursor solvent, and calcination temperature on the size of the nickel nanoparticles and homogeneity of the composite material are evaluated. Characteristics of the Ni/MWCNT catalysts were examined using BET, scanning transmission electron microscopy, X-ray diffraction, thermogravimetric analysis in air and nitrogen, temperature-programmed reduction, X-ray photoelectron spectroscopy, acid-base titration, and zeta-potential analyzer. Results of this work are useful for formulating CNT-supported nickel catalysts for a wide range of different applications, such as reforming of hydrocarbons, catalytic hydrothermal gasification of biomass, and energy storage. PMID:19821594

  13. Multiwalled carbon nanotubes/gold nanocomposites-based electrochemiluminescent sensor for sensitive determination of bisphenol A.

    PubMed

    Guo, Weiwei; Zhang, Amin; Zhang, Xin; Huang, Chusen; Yang, Dapeng; Jia, Nengqin

    2016-10-01

    An electrochemiluminescence (ECL) sensor for bisphenol A was proposed by using L-cysteine-functionalized multiwalled carbon nanotubes/gold nanocomposites-modified glassy carbon electrode (MWCNTs-Au/GCE) based on ECL of peroxydisulfate solution. The ECL behaviors of peroxydisulfate solution had been investigated at the chitosan/MWCNTs-Au/GCE, and bisphenol A was found to have quenching effects on the ECL of peroxydisulfate solution. Both Au nanoparticles (AuNPs) and multiwalled CNTs could promote the electron transfer and synergetically amplify the ECL signal of peroxydisulfate solution. Under the optimized conditions, the ECL signal intensity was linear with the concentration of bisphenol A in the concentration range between 0.25 and 100 μM (R = 0.9931) with a detection limit (S/N = 3) of 0.083 μM. The constructed ECL sensor has the advantages of simplicity, sensitivity, good selectivity, and reproducibility, exhibiting a great potential application in the determination of bisphenol A.

  14. Effect of Purity and Substrate on Field Emission Properties of Multi-walled Carbon Nanotubes

    PubMed Central

    2007-01-01

    Multi-walled carbon nanotubes (MWNT) have been synthesized by chemical vapour decomposition (CVD) of acetylene over Rare Earth (RE) based AB2(DyNi2) alloy hydride catalyst. The as-grown carbon nanotubes were purified by acid and heat treatments and characterized using powder X-ray diffraction, Scanning Electron Microscopy, Transmission Electron Microscopy, Thermo Gravimetric Analysis and Raman Spectroscopy. Fully carbon based field emitters have been fabricated by spin coating a solutions of both as-grown and purified MWNT and dichloro ethane (DCE) over carbon paper with and without graphitized layer. The use of graphitized carbon paper as substrate opens several new possibilities for carbon nanotube (CNT) field emitters, as the presence of the graphitic layer provides strong adhesion between the nanotubes and carbon paper and reduces contact resistance. The field emission characteristics have been studied using an indigenously fabricated set up and the results are discussed. CNT field emitter prepared by spin coating of the purified MWNT–DCE solution over graphitized carbon paper shows excellent emission properties with a fairly stable emission current over a period of 4 h. Analysis of the field emission characteristics based on the Fowler–Nordheim (FN) theory reveals current saturation effects at high applied fields for all the samples. PMID:21798103

  15. Effect of Purity and Substrate on Field Emission Properties of Multi-walled Carbon Nanotubes.

    PubMed

    Rakhi, Rb; Sethupathi, K; Ramaprabhu, S

    2007-06-21

    Multi-walled carbon nanotubes (MWNT) have been synthesized by chemical vapour decomposition (CVD) of acetylene over Rare Earth (RE) based AB2(DyNi2) alloy hydride catalyst. The as-grown carbon nanotubes were purified by acid and heat treatments and characterized using powder X-ray diffraction, Scanning Electron Microscopy, Transmission Electron Microscopy, Thermo Gravimetric Analysis and Raman Spectroscopy. Fully carbon based field emitters have been fabricated by spin coating a solutions of both as-grown and purified MWNT and dichloro ethane (DCE) over carbon paper with and without graphitized layer. The use of graphitized carbon paper as substrate opens several new possibilities for carbon nanotube (CNT) field emitters, as the presence of the graphitic layer provides strong adhesion between the nanotubes and carbon paper and reduces contact resistance. The field emission characteristics have been studied using an indigenously fabricated set up and the results are discussed. CNT field emitter prepared by spin coating of the purified MWNT-DCE solution over graphitized carbon paper shows excellent emission properties with a fairly stable emission current over a period of 4 h. Analysis of the field emission characteristics based on the Fowler-Nordheim (FN) theory reveals current saturation effects at high applied fields for all the samples.

  16. Microtubule guiding in a multi-walled carbon nanotube circuit.

    PubMed

    Sikora, Aurélien; Ramón-Azcón, Javier; Sen, Mustafa; Kim, Kyongwan; Nakazawa, Hikaru; Umetsu, Mitsuo; Kumagai, Izumi; Shiku, Hitoshi; Matsue, Tomokazu; Teizer, Winfried

    2015-08-01

    In nanotechnological devices, mass transport can be initiated by pressure driven flow, diffusion or by employing molecular motors. As the scale decreases, molecular motors can be helpful as they are not limited by increased viscous resistance. Moreover, molecular motors can move against diffusion gradients and are naturally fitted for nanoscale transportation. Among motor proteins, kinesin has particular potential for lab-on-a-chip applications. It can be used for sorting, concentrating or as a mechanical sensor. When bound to a surface, kinesin motors propel microtubules in random directions, depending on their landing orientation. In order to circumvent this complication, the microtubule motion should be confined or guided. To this end, dielectrophoretically aligned multi-walled-carbon nanotubes (MWCNT) can be employed as nanotracks. In order to control more precisely the spatial repartition of the MWCNTs, a screening method has been implemented and tested. Polygonal patterns have been fabricated with the aim of studying the guiding and the microtubule displacement between MWCNT segments. Microtubules are observed to transfer between MWCNT segments, a prerequisite for the guiding of microtubules in MWCNT circuit-based biodevices. The effect of the MWCNT organization (crenellated or hexagonal) on the MT travel distance has been investigated as well.

  17. Carbon dots-decorated multiwalled carbon nanotubes nanocomposites as a high-performance electrochemical sensor for detection of H2O2 in living cells.

    PubMed

    Bai, Jing; Sun, Chunhe; Jiang, Xiue

    2016-07-01

    A novel enzyme-free hydrogen peroxide sensor composed of carbon dots (CDs) and multi-walled carbon nanotubes (MWCNTs) was prepared. It was found that the carbon dots-decorated multi-walled carbon nanotubes nanocomposites (CDs/MWCNTs) modified glassy carbon (GC) electrode (CDs/MWCNTs/GCE) exhibited a significant synergistic electrocatalytic activity towards hydrogen peroxide reduction as compared to carbon dots or multi-walled carbon nanotubes alone, and the CDs/MWCNTs/GCE has shown a low detection limit as well as excellent stability, selectivity, and reproducibility. These remarkable analytical advantages enable the practical application of CDs/MWCNTs/GCE for the real-time tracking of hydrogen peroxide (H2O2) released from human cervical cancer cells with satisfactory results. The enhanced electrochemical activity can be assigned to the edge plane-like defective sites and lattice oxygen in the CDs/MWCNTs nanocomposites due to the small amount of decoration of carbon dots on the multi-walled carbon nanotubes. Based on a facile preparation method and with good electrochemical properties, the CDs/MWCNTs nanocomposites represent a new class of carbon electrode for electrochemical sensor applications. Graphical Abstract CDs/MWCNTs exhibited good electrocatalytic activity and stability to H2O2 reduction and can be used for real-time detection of H2O2 released from living cells.

  18. On-chip purification via liquid immersion of arc-discharge synthesized multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Hokkanen, Matti J.; Lautala, Saara; Shao, Dongkai; Turpeinen, Tuomas; Koivistoinen, Juha; Ahlskog, Markus

    2016-07-01

    Arc-discharge synthesized multiwalled carbon nanotubes (AD-MWNT) have been proven to be of high quality, but their use is very limited due to difficulties in obtaining them in a clean and undamaged form. Here, we present a simple method that purifies raw AD-MWNT material in laboratory scale without damage, and that in principle can be scaled up. The method consists of depositing raw AD-MWNT material on a flat substrate and immersing the substrate slowly in water, whereby the surface tension force of the liquid-substrate contact line selectively sweeps away the larger amorphous carbon debris and leaves relatively clean MWNTs on the substrate. We demonstrate the utility of the method by preparing clean individual MWNTs for measurement of their Raman spectra. The spectra exhibit the characteristics of high-quality tubes free from contaminants. We also show how one concomitantly with the purification process can obtain large numbers of clean suspended MWNTs.

  19. Unzipped Nanotube Sheet Films Converted from Spun Multi-Walled Carbon Nanotubes by O2 Plasma.

    PubMed

    Jangr, Hoon-Sik; Jeon, Sang Koo; Shim, Dae Seob; Lee, Nam Hee; Nahm, Seung Hoon

    2015-11-01

    Large-scale graphene or carbon nanotube (CNT) films are good candidates for transparent flexible electrodes, and the strong interest in graphene and CNT films has motivated the scalable production of a good-conductivity and an optically transmitting film. Unzipping techniques for converting CNTs to graphene are especially worthy of notice. Here, we performed nanotube unzipping of the spun multi-walled carbon nanotubes (MWCNTs) to produce networked graphene nanoribbon (GNR) sheet films using an 02 plasma etching method, after which we produced the spun MWCNT film by continually pulling MWCNTs down from the vertical well aligned MWCNTs on the substrate. The electrical resistance was slightly decreased and the optical transmittance was significantly increased when the spun MWCNT films were etched for 20 min by O2 plasma of 100 mA. Plasma etching for the optimized time, which does not change the thickness of the spun MWCNT films, improved the electrical resistance and the optical transmittance.

  20. H2 adsorption on multiwalled carbon nanotubes at low temperatures and low pressures

    NASA Astrophysics Data System (ADS)

    Xu, F.; Barberio, M.; Vasta, R.; Barone, P.; Bonanno, A.; Pirronello, V.

    2008-11-01

    We present an experimental study on H2 adsorption on multiwalled carbon nanotubes (MWCNTs) at low temperatures (12-30 K) and low pressures (2×10-5Torr) using the temperature programmed desorption technique. Our results show that the molecular hydrogen uptake increases nearly exponentially from 6×10-9wt.% at 24.5 K to 2×10-7wt.% at 12.5 K and that the desorption kinetics is of the first order. Comparative measurements indicate that MWCNTs have an adsorption capacity about two orders higher than that of activated carbon (charcoal) making them a possible candidate as hydrogen cryosorber for eventual applications in accelerators and synchrotrons.

  1. Capillary effect of multi-walled carbon nanotubes suspension in composite processing.

    PubMed

    Fan, Zhihang; Advani, Suresh G

    2008-04-01

    Carbon nanotubes (CNTs) do have the potential to improve the interlaminar shear strength (ILSS) of composites if they can be successfully integrated into the matrix as it infuses into the fiber preform. The infusion under capillary action of Multi-Walled Carbon Nanotubes (MWNT)/Epoxy suspension with tubes of length 0.3 approximately 1 microm in glass fiber bundles containing pores of the order of 5 nm approximately100 microm was investigated. The influence of parameters such as suspension concentration, viscosity, porous media architecture, surface tension and contact angle were explored. It was found that filtering of the suspension is a major challenge for uniform infusion for concentrations beyond 0.5% MWNT by weight. This is even truer for fiber bundles that are compacted. Hence for successful manufacturing, new infusion techniques that rely on fabrics of high permeability will have to be developed to fabricate such nanocomposites.

  2. Modeling and simulation of vibrational breathing-like modes in individual multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Sbai, K.; Rahmani, A.; Fakrach, B.; Chadli, H.; Benhamou, M.

    2014-02-01

    We study the collective vibrational breathing modes in the Raman spectrum of multiwalled carbon nanotubes (MCNTs). First, a bond polarization theory and the spectral moment's method (SMM) are used to calculate the non-resonant Raman frequencies of the breathing-like modes (BLMs) and the tangential-like ones (TLMs). Second, the Raman active modes of MCNTs are computed for different diameters and numbers of layers. The obtained low frequency modes in MCNTs can be identified to each single-walled carbon nanotubes. These modes that originate from the radial breathing ones of the individual walls are strongly coupled through the concentric tube-tube van der Waals interaction. The calculated BLMs in the low-frequency region are compared with the experimental Raman data obtained from other studies. Finally, special attention is given to the comparison with Raman data on MCNTs composed of six layers.

  3. Interactions of 14C-labeled multi-walled carbon nanotubes with soil minerals in water.

    PubMed

    Zhang, Liwen; Petersen, Elijah J; Zhang, Wen; Chen, Yongsheng; Cabrera, Miguel; Huang, Qingguo

    2012-07-01

    Carbon nanotubes are often modified to be stable in the aqueous phase by adding extensive hydrophilic surface functional groups. The stability of such CNTs in water with soil or sediment is one critical factor controlling their environmental fate. We conducted a series of experiments to quantitatively assess the association between water dispersed multi-walled carbon nanotubes (MWCNTs) and three soil minerals (kaolinite, smectite, or shale) in aqueous solution under different sodium concentrations. (14)C-labeling was used in these experiments to unambiguously quantify MWCNTs. The results showed that increasing ionic strength strongly promoted the removal of MWCNTs from aqueous phase. The removal tendency is inversely correlated with the soil minerals' surface potential and directly correlated with their hydrophobicity. This removal can be interpreted by the extended Derjaguin-Landau-Verwey-Overbeek (EDLVO) theory especially for kaolinite and smectite. Shale, which contains large and insoluble organic materials, sorbed MWCNTs the most strongly.

  4. Elastic Response and Failure Studies of Multi-Wall Carbon Nanotube Twisted Yarns

    NASA Technical Reports Server (NTRS)

    Gates, Thomas S.; Jefferson, Gail D.; Frankland, Sarah-Jane V.

    2007-01-01

    Experimental data on the stress-strain behavior of a polymer multiwall carbon nanotube (MWCNT) yarn composite are used to motivate an initial study in multi-scale modeling of strength and stiffness. Atomistic and continuum length scale modeling methods are outlined to illustrate the range of parameters required to accurately model behavior. The carbon nanotubes yarns are four-ply, twisted, and combined with an elastomer to form a single-layer, unidirectional composite. Due to this textile structure, the yarn is a complicated system of unique geometric relationships subjected to combined loads. Experimental data illustrate the local failure modes induced by static, tensile tests. Key structure-property relationships are highlighted at each length scale indicating opportunities for parametric studies to assist the selection of advantageous material development and manufacturing methods.

  5. Efficient delivery of DNA into bovine preimplantation embryos by multiwall carbon nanotubes

    PubMed Central

    Munk, Michele; Ladeira, Luiz O.; Carvalho, Bruno C.; Camargo, Luiz S. A.; Raposo, Nádia R. B.; Serapião, Raquel V.; Quintão, Carolina C. R.; Silva, Saulo R.; Soares, Jaqueline S.; Jorio, Ado; Brandão, Humberto M.

    2016-01-01

    The pellucid zone (PZ) is a protective embryonic cells barrier against chemical, physical or biological substances. This put, usual transfection methods are not efficient for mammal oocytes and embryos as they are exclusively for somatic cells. Carbon nanotubes have emerged as a new method for gene delivery, and they can be an alternative for embryos transfection, however its ability to cross the PZ and mediated gene transfer is unknown. Our data confirm that multiwall carbon nanotubes (MWNTs) can cross the PZ and delivery of pDNA into in vitro-fertilized bovine embryos. The degeneration rate and the expression of genes associated to cell viability were not affected in embryos exposed to MWNTs. Those embryos, however, had lower cell number and higher apoptotic cell index, but this did not impair the embryonic development. This study shows the potential utility of the MWNT for the development of new method for delivery of DNA into bovine embryos. PMID:27642034

  6. Conductivity enhancement of multiwalled carbon nanotube thin film via thermal compression method

    NASA Astrophysics Data System (ADS)

    Tsai, Wan-Lin; Wang, Kuang-Yu; Chang, Yao-Jen; Li, Yu-Ren; Yang, Po-Yu; Chen, Kuan-Neng; Cheng, Huang-Chung

    2014-08-01

    For the first time, the thermal compression method is applied to effectively enhance the electrical conductivity of carbon nanotube thin films (CNTFs). With the assistance of heat and pressure on the CNTFs, the neighbor multiwalled carbon nanotubes (CNTs) start to link with each other, and then these separated CNTs are twined into a continuous film while the compression force, duration, and temperature are quite enough for the reaction. Under the compression temperature of 400°C and the compression force of 100 N for 50 min, the sheet resistance can be reduced from 17 to 0.9 k Ω/sq for the CNTFs with a thickness of 230 nm. Moreover, the effects of compression temperature and the duration of thermal compression on the conductivity of CNTF are also discussed in this work.

  7. Modified dispersion of functionalized multi-walled carbon nanotubes in acetonitrile

    NASA Astrophysics Data System (ADS)

    Li, Heng; Nie, Jia Cai; Kunsági-Máté, Sándor

    2010-06-01

    The dispersion of hydroxylated multi-walled carbon nanotubes was modified in non-protic acetonitrile solvent using a treatment by ethanol. The dispersion was examined by photoluminescence and Rayleigh-scattering methods. In spite of well known very low solubility of nanotubes, present results showed presence of nanotube dimers in the solution with considerable concentration. Applying a qualitative model, Δ H = -46.6 ± 12 kJ/mol and Δ S = -29.9 ± 7 J/K mol enthalpy and entropy changes were obtained during formation of nanotube dimers. This highly negative entropy term is of great importance for the deposition of carbon nanotubes by liquid phase epitaxy to enlarge the surface coverage.

  8. Conductivity enhancement of multiwalled carbon nanotube thin film via thermal compression method

    PubMed Central

    2014-01-01

    For the first time, the thermal compression method is applied to effectively enhance the electrical conductivity of carbon nanotube thin films (CNTFs). With the assistance of heat and pressure on the CNTFs, the neighbor multiwalled carbon nanotubes (CNTs) start to link with each other, and then these separated CNTs are twined into a continuous film while the compression force, duration, and temperature are quite enough for the reaction. Under the compression temperature of 400°C and the compression force of 100 N for 50 min, the sheet resistance can be reduced from 17 to 0.9 k Ω/sq for the CNTFs with a thickness of 230 nm. Moreover, the effects of compression temperature and the duration of thermal compression on the conductivity of CNTF are also discussed in this work. PMID:25232300

  9. Magnetic studies of polystyrene/iron-filled multi-wall carbon nanotube composite films

    NASA Astrophysics Data System (ADS)

    Makarova, T. L.; Zakharchuk, I.; Geydt, P.; Lahderanta, E.; Komlev, A. A.; Zyrianova, A. A.; Kanygin, M. A.; Sedelnikova, O. V.; Suslyaev, V. I.; Bulusheva, L. G.; Okotrub, A. V.

    2016-10-01

    Polystyrene/iron-filled multi-wall carbon nanotube composite films were prepared by solution processing, forge-rolling and stretching methods. Elongated iron carbide nanoparticles formed because of catalytic growth are situated inside the hollow cavity of the nanotubes. Magnetic susceptibility measurements as well as records of isothermal hysteresis loops performed in three perpendicular directions of magnetic field confirmed that the nanotubes have a preferential alignment in the matrix. Strong diamagnetic anisotropy in the composites emerges not only from the MWCNTs but also from the polystyrene matrix. The polymer sticks to the honeycomb lattice through the interaction of the π-orbitals of the phenyl ring and those of the carbon nanotube, contributing to anisotropic diamagnetic response. The contribution of iron nanoparticles to overall magnetic response strongly depends on nanotube concentration in the composite as well as on matrix-filler non-covalent stacking, which influences magnetic interparticle interactions.

  10. Morphological and structural modifications of multiwalled carbon nanotubes by electron beam irradiation

    NASA Astrophysics Data System (ADS)

    Elsehly, Emad M.; Chechenin, N. G.; Makunin, A. V.; Motaweh, H. A.

    2016-10-01

    Effects of electron beam irradiation on a morphology and structure of multiwalled carbon nanotubes sample in a normal imaging regime of a scanning electron microscope (SEM) were investigated. Direct SEM observations give evidence that irradiation by electron beam in SEM eliminates morphological unevenness, in the form of round spots of white contrast, on the surface of carbon nanotubes (CNTs) and makes the tubes thinner. Electron dispersive analysis and Raman spectroscopy are used to explore the origin and nature of these spots. From this analysis we found that e-beam irradiation improves the CNTs graphitization. The synergy of thermal heating and ionization produced by the irradiation are discussed as possible mechanisms of the observed effects.

  11. Microstructure and mechanical properties of silicon carbide ceramics reinforced with multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Barmin, A.; Bortnikova, V.; Ivanov, A.; Kornev, V.; Lurie, S.; Solyaev, Y.

    2016-04-01

    A microstructure, a composition and mechanical properties of multi-walled carbon of nanotube-reinforced silicon carbide ceramics were examined. The amount of carbon nanotubes was up to 1% wt. Samples was prepared by spark plasma sintering. It has been found that the optimal sintering temperature is 2000°C with an exposure duration of 5 minutes and a pressure of 50 MPa. The effect of the CNT mass fraction on the Young modulus of silicon carbide ceramics composites was investigated for different temperatures and processing conditions of samples using ultrasonic techniques. It has been established that Young's modulus of ceramics decreases due to addition of CNT. Elastic properties of the composites cross section were characterized using nano-indentation. It has been revealed that the stiffness of the ceramics intergranular phase decreases due to addition of CNT.

  12. Multiwall carbon nanotubes as MRI contrast agents for tracking stem cells

    NASA Astrophysics Data System (ADS)

    Vittorio, Orazio; Duce, Suzanne L.; Pietrabissa, Andrea; Cuschieri, Alfred

    2011-03-01

    In this study we investigate the potential of multiwall carbon nanotubes (MWCNTs) with low metal impurities (2.57% iron) as magnetic resonance imaging (MRI) contrast agents. Taking into account probable aggregation at high MWCNTs concentration analysis shows that the r2 relaxivity of MWCNTs in 1% agarose gels at 19 °C is 564 ± 41 s - 1 mM - 1; this is attributed to both the presence of iron oxide impurities and also to the carbon MWCNT structure itself. Stem cells were labelled with MWCNTs to demonstrate the effectiveness of MWCNTs as MRI contrast agents for cellular MRI. The MWCNTs did not impair cell viability or proliferation. These results suggest that the MRI contrast agent properties of the MWCNTs could be used in vivo for stem cell tracking/imaging and during MWCNT-mediated targeted electro-chemotherapy of tumours.

  13. Ultra-high crystallinity millimeter long multiwall carbon nanotubes fabricated by mechanothermal method

    NASA Astrophysics Data System (ADS)

    Manafi, S. A.; Rahimipour, M. R.; Soltanmoradi, A.

    2012-09-01

    In this work, multi-walled carbon nanotubes (MWCNTs) with ultra-high crystalline structure have been prepared by mechanothermal (MT) method. The novel super nanostructure is introduced for the first time as an extraordinary fullerene-carbon based material which, due to its special electronic and mechanical properties, can be used to construct unique building blocks for nanoengineering. Initially, high ultra-active graphite powder has been obtained by mechanical activation under Ar atmosphere. Finally, the mechanically activated product is heat-treated at 1350 °C for 3-4 h under an Ar gas flow. However, the crystallite size and crystallinity degree of the MWCNTs increased with the increase in annealing temperature.

  14. Efficient delivery of DNA into bovine preimplantation embryos by multiwall carbon nanotubes.

    PubMed

    Munk, Michele; Ladeira, Luiz O; Carvalho, Bruno C; Camargo, Luiz S A; Raposo, Nádia R B; Serapião, Raquel V; Quintão, Carolina C R; Silva, Saulo R; Soares, Jaqueline S; Jorio, Ado; Brandão, Humberto M

    2016-01-01

    The pellucid zone (PZ) is a protective embryonic cells barrier against chemical, physical or biological substances. This put, usual transfection methods are not efficient for mammal oocytes and embryos as they are exclusively for somatic cells. Carbon nanotubes have emerged as a new method for gene delivery, and they can be an alternative for embryos transfection, however its ability to cross the PZ and mediated gene transfer is unknown. Our data confirm that multiwall carbon nanotubes (MWNTs) can cross the PZ and delivery of pDNA into in vitro-fertilized bovine embryos. The degeneration rate and the expression of genes associated to cell viability were not affected in embryos exposed to MWNTs. Those embryos, however, had lower cell number and higher apoptotic cell index, but this did not impair the embryonic development. This study shows the potential utility of the MWNT for the development of new method for delivery of DNA into bovine embryos. PMID:27642034

  15. Ultraviolet laser treatment of multiwall carbon nanotubes grown at low temperature

    NASA Astrophysics Data System (ADS)

    Kim, J. S.; Ahn, K. S.; Kim, C. O.; Hong, J. P.

    2003-03-01

    Simple laser irradiation of well-aligned multiwall carbon nanotubes (MWCNTs) was performed to intentionally modify structural defects and to ablate possible contamination of the MWCNTs. Scanning electron microscopy and transmission electron microscopy confirmed the clear presence of the MWCNTs with open tips. A Raman spectra exhibited a decrease in an intensity ratio (ID/IG) of 1352 cm-1 (D band) over 1583 cm-1 (G band) peaks by significantly reducing the amorphous carbon phases of D band peaks. The structural improvement in the MWCNTs after optimum laser exposure resulted in a reduction of the turn-on voltage from 1.0 to 0.6 V/μm and an increase in the emission current.

  16. Multi-Walled Carbon Nanotube Functionalization by Radical Addition Using Hydroxymethylene Groups.

    PubMed

    Rodríguez-Jiménez, Rubén; Alonso-Núñez, Gabriel; Paraguay-Delgado, Francisco; Espinoza-Gómez, Heriberto; Vélez-López, Ernesto; Rogel-Hernández, Eduardo

    2016-01-01

    Synthetic methodology and characterization of multi-walled carbon nanotubes (MWCNTs) function- alized with hydroxymethylene groups are reported. The MWCNTs were synthesized by the spray pyrolysis technique using toluene as carbon source and ferrocene as catalyst. Hydroxymethylation of MWCNTs was carried out by methanol using benzoyl peroxide (BPO) at different quantities (300 to 900 mg); the optimum BPO quantity was 300 mg. The resulting materials were characterized by FT-IR, Raman Spectroscopy, Thermal Gravimetric Analysis (TGA) and Transmission Electron Microscopy (TEM). The presence of the hydroxymethylene group on the MWCNTs surface was demonstrated by FT-IR, Raman Spectroscopy, TGA, EDS, TEM and Mass Spectrometry. The func- tionalized MWCNTs were not damaged by this methodology. PMID:27398563

  17. Crystallographic order in multi-walled carbon nanotubes synthesized in the presence of nitrogen.

    PubMed

    Ducati, Caterina; Koziol, Krzystof; Friedrichs, Steffi; Yates, Timothy J V; Shaffer, Milo S; Midgley, Paul A; Windle, Alan H

    2006-06-01

    Multi-walled carbon nanotubes were synthesized by chemical vapor deposition from pure toluene and toluene/diazine mixtures using ferrocene as a catalyst precursor at 760 degrees C. As recently announced, characterization of the resulting nanotube films showed that, unlike pure carbon nanotubes, those grown in the presence of nitrogen have an extremely high degree of internal order, both in terms of the uniform chirality in the nanotube walls and of the crystallographic register between them. Here, the structure, defects, and morphology of the nanotubes were analyzed in depth using advanced electron microscopy techniques, and compared with existing models and observations. Nitrogen, which seems to be responsible for the dramatic structural order, was found to segregate preferentially within the core of the nanotubes.

  18. Preparation and Characterization of Iodine-doped Multi-wall Carbon Nanotubes

    SciTech Connect

    Zainal, N. F. A.; Kudin, T. I. Tunku; Azira, A.; Ahmed, A. Z.; Abdullah, S.; Rusop, M.

    2008-05-20

    Multi-wall carbon nanotubes (MWCNTs) were synthesized by thermal chemical vapor deposition (CVD) and were intercalated with iodine at several different temperatures. Iodine doping was achieved by immersing the nanotubes in molten iodine. The sample produced was characterized by means of infrared IR as a point to the presence of covalent C-I bonds in the sample with retention of the sp{sup 2}-hybridizated carbon atoms. For all samples doped at different temperatures, the C-I bonding happen to occur based on IR spectra which was indicated by peaks around 600-650 cm{sup -1}. X-ray diffraction (XRD) characterization was used to study on the crystallinity of the undoped and iodine-doped MWCNTs. It was shown that, iodine-doping of the MWCNTs gives significant changes in the XRD spectra compared to the undoped MWCNTs. With various doping temperature, the XRD spectra shows the different crystallinity.

  19. Modification of multi-walled carbon nanotubes by Diels-Alder and Sandmeyer reactions.

    PubMed

    Gergely, A; Telegdi, J; Mészáros, E; Pászti, Z; Tárkanyi, G; Kármán, F H; Kálmán, E

    2007-08-01

    Random (L) and aligned (A) multi-walled carbon nanotubes (MWNTs) were modified by Diels-Alder (DA) [4+2] cycloaddition, Sandmeyer (SM) reaction and by catalytic oxidation (OX). The properties of modified carbon nanotubes were studied by dispersability tests, elemental analysis, thermogravimetry/mass spectrometry, X-ray photoelectron spectroscopy, and NMR spectroscopy. The cycloaddition reaction could only be successfully performed with the L-MWNTs in molten and in solution state by using an aluminum chloride homogeneous catalyst. The efficiency and thermal stability of the solution phase cycloaddition were much higher than in the case of modification in the molten phase. The functionalization of both types of MWNTs by Sandmeyer reaction was carried out by copper(I) and iron(ll) ions that helped in the radical decomposition of diazonium salts. Successful functionalization of nanotubes is achieved by a long decomposition time of the thermally activated diazonium salts. To the contrary, in the case of radical decomposition of diazonium salts, the time is not a decisive parameter. The dispersability tests have proved the changes in the physical features of modified carbon nanotubes depending on the hydrophobic and hydrophilic character of the solvents. The presence of the modifying groups and their fragments from the functionalized MWNTs has been demonstrated by thermogravimetry/mass spectrometry (TG/MS). Relatively high concentration of sulfur atoms was detected by X-ray photoelectron spectroscopy in nanotubes modified by sulfur substituent groups. In the case of catalytic oxidation, the X-ray photoelectron spectroscopic signal of oxygen bound to nanotubes showed considerable change as compared to pristine nanotubes. Due to the high thermal stability of modified multi-walled carbon nanotubes, the functionalized derivatives are applicable in several industrial fields. PMID:17685300

  20. Effects of acid treatment duration and sulfuric acid molarity on purification of multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Mortazavi, Seyedeh Z.; Novinrooz, Abdul J.; Reyhani, Ali; Mirershadi, Soghra

    2010-12-01

    Multi-walled carbon nanotubes were synthesized using a Fe-Ni bimetallic catalyst supported by MgO using thermal chemical vapor deposition. Purification processes to remove unwanted carbon structures and other metallic impurities were carried out by boiling in sulfuric acid solution. Various analytical techniques such as TGA/DSC, Raman spectroscopy, SEM, HRTEM and EDAX were employed to investigate the morphology, graphitization and quality of the carbon nanotubes. The obtained results reveal the molarity of sulfuric acid and immersed time of the carbon nanotubes in the acid solution is very effective at purifying multi-walled carbon nanotubes. It was also found that 5 M concentration of boiling sulfuric acid for a 3 h treatment duration led to the highest removal of the impurities with the least destructive effect. Moreover, it was observed that acid treatment results in decreasing of CNTs’ diameter.

  1. Effects of acid treatment duration and sulfuric acid molarity on purification of multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Mortazavi, Seyedeh; Novinrooz, Abdul; Reyhani, Ali; Mirershadi, Soghra

    2010-12-01

    Multi-walled carbon nanotubes were synthesized using a Fe-Ni bimetallic catalyst supported by MgO using thermal chemical vapor deposition. Purification processes to remove unwanted carbon structures and other metallic impurities were carried out by boiling in sulfuric acid solution. Various analytical techniques such as TGA/DSC, Raman spectroscopy, SEM, HRTEM and EDAX were employed to investigate the morphology, graphitization and quality of the carbon nanotubes. The obtained results reveal the molarity of sulfuric acid and immersed time of the carbon nanotubes in the acid solution is very effective at purifying multi-walled carbon nanotubes. It was also found that 5 M concentration of boiling sulfuric acid for a 3 h treatment duration led to the highest removal of the impurities with the least destructive effect. Moreover, it was observed that acid treatment results in decreasing of CNTs' diameter.

  2. ZnO Functionalization of Multi-walled Carbon Nanotubes for Methane Sensing at Single Parts Per Million Concentration Levels

    EPA Science Inventory

    This paper presents a novel atomic layer deposition (ALD) based ZnO functionalization of surface pre-treated multi-walled carbon nanotubes (MWCNTs) for highly sensitive methane chemoresistive sensors. The temperature optimization of the ALD process leads to enhanced ZnO nanopart...

  3. Transport and retention of multi-walled carbon nanotubes in saturated porous media: Effects of input concentration and grain size

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Water-saturated column experiments were conducted to investigate the effect of input concentration (Co) and sand grain size on the transport and retention of low concentrations (1, 0.01, and 0.005 mg L/1) of functionalized 14C-labeled multi-walled carbon nanotubes (MWCNT) under repulsive electrostat...

  4. Effect of Acid and Alcohol Network Forces within Functionalized Multiwall Carbon Nanotubes Bundles on Adsorption of Copper (II) Species

    EPA Science Inventory

    Adsorption of metals on carbon nanotubes (CNTs) has important applications in sensors, membranes, and water treatment. The adsorptive capacity of multiwall CNTs for copper species in water depends on the type of functional group present on their surface. The alcohol (COOH) and ac...

  5. Nanocomposites of nitrile (NBR) rubber with multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Warasitthinon, Nuthathai

    Nanotechnology offers the promise of creating new materials with enhanced performance. There are different kinds of fillers used in rubber nanocomposites, such as carbon black, silica, carbon fibers, and organoclays. Carbon nanotube reinforced elastomers have potential for improved rubber properties in aggressive environments. The first chapter is an introduction to the literature. The second chapter investigated the incorporation of multi-walled carbon nanotubes (MWCNTs) into rubber matrix for potential use in high temperature applications. The vulcanization kinetics of acrylonitrile butadiene rubber (NBR) reinforced with multi-walled carbon nanotubes was investigated. The vulcanized NBR rubber with different loading percentages of MWCNTs was also compared to NBR reinforced with carbon black N330. The optimum curing time at 170°C (T90) was found to decrease with increasing content of MWCNTs. Increased filler loading of both carbon black and MWCNTs gave higher modulus and strength. The MWCNTs filled materials gave better retention of modulus and tensile strength at high temperatures, but lower strength as compared to the carbon black filled samples. In the third chapter, carbon black (CB, 50phr) content in nitrile rubber (NBR) nanocomposites was partially replaced by multi-walled carbon nanotubes (MWCNTs). NBR/CB/CNTs nanocomposites with varying ratio of CB/CNTs (50/0 phr to 40/10 phr) were formulated via the melt-mixing method using an internal mixer. The reinforcing effect of single filler (CB) and mixture of fillers (CB and CNTs) on the properties of NBR nanocomposites was investigated. The cure kinetics and bound rubber content were analyzed using rheometry and solvent swelling method. In addition, mechanical behavior at both room temperature and high temperature (350°F/ 121°C) were examined. The scorch time and curing time values showed that there was no significant effect on the curing behavior of NBR nanocomposites after the partial replacement of CB with

  6. Integrative characterization of the thermoelectric performance of an individual multiwalled carbon nanotube

    NASA Astrophysics Data System (ADS)

    Miao, Tingting; Shi, Shaoyi; Yan, Shen; Ma, Weigang; Zhang, Xing; Takahashi, Koji; Ikuta, Tatsuya

    2016-09-01

    Carbon nanotube-based organic composites and carbon nanotube networks are important flexible and lightweight thermoelectric materials. Characterization of the thermoelectric performance of individual carbon nanotubes is of vital importance for exploring the coupling mechanism between carbon nanotubes and organic composites, and proposing further improvement measures. The thermoelectric performance of an individual multiwalled carbon nanotube with a diameter of 66 nm has been comprehensively studied by applying our T-type method from 260 K to 420 K, using the same measurement configuration. The figure of merit increases from 4.84 × 10-8 to 1.32 × 10-6 on increasing the temperature, which is smaller than previous experimental results on carbon nanotube samples. The thermal conductivity increases from 706 W m-1 K-1 at 260 K to 769.3 W m-1 K-1 at 320 K, and then stays nearly constant until 420 K. The phonons dominate the thermal transport. The electrical conductivity exhibits thermally activated carrier generation and transport with an energy barrier of 194.5 meV. The Seebeck coefficient is in the range of 29.4-41.0 μV K-1 and tends to decrease with temperature.

  7. Structural and proactive safety aspects of oxidation debris from multiwalled carbon nanotubes.

    PubMed

    Stéfani, Diego; Paula, Amauri J; Vaz, Boniek G; Silva, Rodrigo A; Andrade, Nádia F; Justo, Giselle Z; Ferreira, Carmen V; Filho, Antonio G Souza; Eberlin, Marcos N; Alves, Oswaldo L

    2011-05-15

    The removal of oxidation debris from the oxidized carbon nanotube surface with a NaOH treatment is a key step for an effective functionalization and quality improvement of the carbon nanotube samples. In this work, we show via infrared spectroscopy and ultrahigh resolution and accuracy mass spectrometry that oxidation debris obtained from HNO(3)-treated multiwalled carbon nanotubes is a complex mixture of highly condensed aromatic oxygenated carbonaceous fragments. We have also evaluated their cytotoxicity by using BALB/c 3T3 mouse fibroblasts and HaCaT human keratinocytes as models. By knowing the negative aspects of dissolved organic carbon (DOC) to the water quality, we have demonstrated the removal of these carbon nanotube residues from the NaOH solution (wastewater) by using aluminium sulphate, which is a standard coagulant agent used in conventional drinking water purification and wastewater treatment plants. Our results contribute to elucidate the structural and proactive safety aspects of oxidation debris from oxidized carbon nanotubes towards a greener nanotechnology.

  8. Mass production of multi-wall carbon nanotubes by metal dusting process with high yield

    SciTech Connect

    Ghorbani, H.; Rashidi, A.M.; Rastegari, S.; Mirdamadi, S.; Alaei, M.

    2011-05-15

    Research highlights: {yields} Synthesis of carbon nanotubes over Fe-Ni nanoparticles supported alloy 304L. {yields} Production of carbon nanotubes with high yield (700-1000%) and low cost catalyst. {yields} Optimum growth condition is CO/H{sub 2} = 1/1, 100 cm{sup 3}/min, at 620 {sup o}C under long term repetitive thermal cycling. {yields} Possibility of the mass production by metal dusting process with low cost. -- Abstract: Carbon nanotube materials were synthesized over Fe-Ni nanoparticles generated during disintegration of the surface of alloy 304L under metal dusting environment. The metal dusting condition was simulated and optimized through exposing stainless steel samples during long term repetitive thermal cycling in CO/H{sub 2} = 1/1, total gas flow rate 100 cm{sup 3}/min, at 620 {sup o}C for 300 h. After reaction, surface morphology of the samples and also carbonaceous deposition which had grown on sample surfaces were examined by stereoscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Results revealed that multi-wall carbon nanotubes could be formed over nanocatalyst generated on the alloy surface by exploiting metal dusting process. By optimization of reaction parameters the yields of carbon nanotube materials obtained were 700-1000%. Also it has been shown herein that the amount of carbon nanotube materials remarkably increases when the reaction time is extended up to 300 h, indicating a possibility of the mass production by this easy method.

  9. MICROWAVE-ASSISTED SYNTHESIS OF CROSSLINKED POLY(VINYL ALCOHOL) NANOCOMPOSITES COMPRISING SINGLE-WALLED CARBON NANOTUBES, MULTI-WALLED CARBON NANOTUBES AND BUCKMINSTERFULLERENE

    EPA Science Inventory

    We report a facile method to accomplish cross-linking reaction of poly (vinyl alcohol) (PVA) with single-wall carbon nanotubes (SWNT), multi-wall carbon nanotubes (MWNT), and Buckminsterfullerene (C-60) using microwave (MW) irradiation. Nanocomposites of PVA cross-linked with SW...

  10. Ultrathin transparent conductive films of polymer-modified multiwalled carbon nanotubes.

    PubMed

    Bocharova, Vera; Kiriy, Anton; Oertel, Ulrich; Stamm, Manfred; Stoffelbach, François; Jérôme, Robert; Detrembleur, Christophe

    2006-08-01

    Deposition of multiwalled carbon nanotubes modified by poly(2-vinylpyridine) (CNT-g-P2VP) from aqueous dispersions at low pH is an effective method to prepare homogeneous ultrathin films with a tunable CNTs density. A percolation threshold of 0.25 mug/cm2 and a critical exponent alpha = 1.24 have been found from dc conductivity measurements. The sheet resistance value agrees with the percolation theory for 2D films. According to AFM and electrical measurements, even when only 5% of the surface is covered by CNT-g-P2VPs, the sheet resistance is of the order of 1 MOmega/sq, which indicates that conductivity is imparted by a network of an ultralow density. When the film transmittance decreases down to approximately 70% at 550 nm, the occupied surface area is approximately 15% and sheet resistance falls down to approximately 90 kOmega/sq. These data show that undesired in-plane clustering does not occur upon the dispersion casting of the films and that high-quality networks of CNT-g-P2VPs are built up. The electrosteric stabilization of the CNT-g-P2VP dispersions in water at low pH is at the origin of this desired behavior. Although the multiwalled CNT films prepared in this work are less conductive and less transparent than the SWNTs films, they could find applications, e.g., in touch screens, reflective displays, EMI shielding, and static charge dissipation.

  11. Binding energy and mechanical stability of single- and multi-walled carbon nanotube serpentines

    SciTech Connect

    Zhao, Junhua E-mail: timon.rabczuk@uni-weimar.de; Lu, Lixin; Rabczuk, Timon E-mail: timon.rabczuk@uni-weimar.de

    2014-05-28

    Recently, Geblinger et al. [Nat. Nanotechnol. 3, 195 (2008)] and Machado et al. [Phys. Rev. Lett. 110, 105502 (2013)] reported the experimental and molecular dynamics realization of S-like shaped single-walled carbon nanotubes (CNTs), the so-called CNT serpentines. We reported here results from continuum modeling of the binding energy γ between different single- and multi-walled CNT serpentines and substrates as well as the mechanical stability of the CNT serpentine formation. The critical length for the mechanical stability and adhesion of different CNT serpentines are determined in dependence of E{sub i}I{sub i}, d, and γ, where E{sub i}I{sub i} and d are the CNT bending stiffness and distance of the CNT translation period. Our continuum model is validated by comparing its solution to full-atom molecular dynamics calculations. The derived analytical solutions are of great importance for understanding the interaction mechanism between different single- and multi-walled CNT serpentines and substrates.

  12. Multiwall carbon nanotube polyvinyl alcohol-based saturable absorber in passively Q-switched fiber laser.

    PubMed

    Ahmad, H; Ismail, M F; Hassan, S N M; Ahmad, F; Zulkifli, M Z; Harun, S W

    2014-10-20

    In this work, we demonstrated a compact Q-switched erbium-doped fiber laser capable of generating high-energy pulses using a newly developed multiwall carbon nanotube (CNT) polyvinyl alcohol (PVA) thin film based saturable absorber. Q-switched pulse operation is obtained by sandwiching the thin film between two fiber ferrules forming a saturable absorber. A saturable absorber with 1.25 wt. % of PVA concentration shows a consistency in generating pulsed laser with a good range of tunable repetition rate, shortest pulse width, and produces a high pulse energy and peak power. The pulse train generated has a maximum repetition rate of 29.9 kHz with a corresponding pulse width of 3.49 μs as a function of maximum pump power of 32.15 mW. The maximum average output power of the Q-switched fiber laser system is 1.49 mW, which translates to a pulse energy of 49.8 nJ. The proposed method of multiwall CNT/PVA thin film fabrication is low in cost and involves uncomplicated processes. PMID:25402790

  13. Acoustic modes of finite length homogeneous and layered cylindrical shells: Single and multiwall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Li, Guangyan; Lamberton, G. A.; Gladden, J. R.

    2008-08-01

    We present a numerical study of the normal modes of vibration of both homogeneous and heterogeneous finite length cylindrical shells of arbitrary wall thickness with applications toward single and multiwall carbon nanotubes in the continuum limit. The method is checked by comparison of computed and measured resonance spectra for a machined aluminum cylindrical shell. The dependence of the natural frequencies of various radial modes with the length and radius of single wall tubes is investigated and compared to atomistic models and Raman spectroscopy data. The radial dependence for the radial breathing mode and four harmonics of the squash mode are found to be well fitted by power laws and agree with analytical solutions in the thin wall limit. A general model for an elastically heterogeneous layered cylindrical shell is applied to multiwall tubes with graphene sheets and gaps between the sheets represented by two different materials. The frequency dependence on length and diameter is investigated for tubes composed of two to four concentric shells.

  14. Voltammetric oxidation and determination of cinnarizine at glassy carbon electrode modified with multi-walled carbon nanotubes.

    PubMed

    Hegde, Rajesh N; Hosamani, Ragunatharaddi R; Nandibewoor, Sharanappa T

    2009-09-01

    The voltammetric oxidation of cinnarizine was investigated. In pH 2.5 Britton-Robinson buffer, cinnarizine shows an irreversible oxidation peak at about 1.20 V at a multi-walled carbon nanotube (MWCNT)-modified glassy carbon electrode. The cyclic voltammetric results indicate that MWCNT-modified glassy carbon electrode can remarkably enhance electrocatalytic activity towards the oxidation of cinnarizine. The electrocatalytic behavior was further exploited as a sensitive detection scheme for the cinnarizine determination by differential-pulse voltammetry. Under optimized conditions, the concentration range and detection limit are 9.0x10(-8) to 6.0x10(-6) M and 2.58x10(-9) M, respectively for cinnarizine. The proposed method was successfully applied to cinnarizine determination in pharmaceutical samples. The analytical performance of this sensor has been evaluated for the detection of analyte in urine as a real sample. PMID:19446444

  15. Cellular uptake mechanisms of functionalised multi-walled carbon nanotubes by 3D electron tomography imaging

    NASA Astrophysics Data System (ADS)

    Al-Jamal, Khuloud T.; Nerl, Hannah; Müller, Karin H.; Ali-Boucetta, Hanene; Li, Shouping; Haynes, Peter D.; Jinschek, Joerg R.; Prato, Maurizio; Bianco, Alberto; Kostarelos, Kostas; Porter, Alexandra E.

    2011-06-01

    Carbon nanotubes (CNTs) are being investigated for a variety of biomedical applications. Despite numerous studies, the pathways by which carbon nanotubes enter cells and their subsequent intracellular trafficking and distribution remain poorly determined. Here, we use 3-D electron tomography techniques that offer optimum enhancement of contrast between carbon nanotubes and the plasma membrane to investigate the mechanisms involved in the cellular uptake of shortened, functionalised multi-walled carbon nanotubes (MWNT-NH3+). Both human lung epithelial (A549) cells, that are almost incapable of phagocytosis and primary macrophages, capable of extremely efficient phagocytosis, were used. We observed that MWNT-NH3+ were internalised in both phagocytic and non-phagocytic cells by any one of three mechanisms: (a) individually via membrane wrapping; (b) individually by direct membrane translocation; and (c) in clusters within vesicular compartments. At early time points following intracellular translocation, we noticed accumulation of nanotube material within various intracellular compartments, while a long-term (14-day) study using primary human macrophages revealed that MWNT-NH3+ were able to escape vesicular (phagosome) entrapment by translocating directly into the cytoplasm.Carbon nanotubes (CNTs) are being investigated for a variety of biomedical applications. Despite numerous studies, the pathways by which carbon nanotubes enter cells and their subsequent intracellular trafficking and distribution remain poorly determined. Here, we use 3-D electron tomography techniques that offer optimum enhancement of contrast between carbon nanotubes and the plasma membrane to investigate the mechanisms involved in the cellular uptake of shortened, functionalised multi-walled carbon nanotubes (MWNT-NH3+). Both human lung epithelial (A549) cells, that are almost incapable of phagocytosis and primary macrophages, capable of extremely efficient phagocytosis, were used. We observed

  16. Multi-walled carbon nanotubes as electrode material for microbial fuel cells.

    PubMed

    Thepsuparungsikul, N; Phonthamachai, N; Ng, H Y

    2012-01-01

    The microbial fuel cell (MFC) is a novel and innovative technology that could allow direct harvesting of energy from wastewater through microbial activity with simultaneous oxidation of organic matter in wastewater. Among all MFC parts, electrode materials play a crucial role in electricity generation. A variety of electrode materials have been used, including plain graphite, carbon paper and carbon cloth. However, these electrode materials generated only limited electricity or power. Recently, many research studies have been conducted on carbon nanotubes (CNTs) because of their unique physical and chemical properties that include high conductivity, high surface area, corrosion resistance, and electrochemical stability. These properties make them extremely attractive for fabricating electrodes and catalyst supports. In this study, CNT-based electrodes had been developed to improve MFC performance in terms of electricity generation and treatment efficiency. Multi-walled carbon nanotubes (MWCNTs) with carboxyl groups have been employed to fabricate electrodes for single-chamber air-cathode MFCs. The quality of the prepared MWCNTs-based electrodes was evaluated by morphology, electrical conductivity and specific surface area using a field emission scanning electron microscope, four-probe method and Brunauer-Emmerr-Teller method, respectively. The performance of MFCs equipped with MWCNT-based electrodes was evaluated by chemical analysis and electrical monitoring and calculation. In addition, the performance of these MFCs, using MWCNTs as electrodes, was compared against that using commercial carbon cloth.

  17. Multi-walled carbon nanotubes as electrode material for microbial fuel cells.

    PubMed

    Thepsuparungsikul, N; Phonthamachai, N; Ng, H Y

    2012-01-01

    The microbial fuel cell (MFC) is a novel and innovative technology that could allow direct harvesting of energy from wastewater through microbial activity with simultaneous oxidation of organic matter in wastewater. Among all MFC parts, electrode materials play a crucial role in electricity generation. A variety of electrode materials have been used, including plain graphite, carbon paper and carbon cloth. However, these electrode materials generated only limited electricity or power. Recently, many research studies have been conducted on carbon nanotubes (CNTs) because of their unique physical and chemical properties that include high conductivity, high surface area, corrosion resistance, and electrochemical stability. These properties make them extremely attractive for fabricating electrodes and catalyst supports. In this study, CNT-based electrodes had been developed to improve MFC performance in terms of electricity generation and treatment efficiency. Multi-walled carbon nanotubes (MWCNTs) with carboxyl groups have been employed to fabricate electrodes for single-chamber air-cathode MFCs. The quality of the prepared MWCNTs-based electrodes was evaluated by morphology, electrical conductivity and specific surface area using a field emission scanning electron microscope, four-probe method and Brunauer-Emmerr-Teller method, respectively. The performance of MFCs equipped with MWCNT-based electrodes was evaluated by chemical analysis and electrical monitoring and calculation. In addition, the performance of these MFCs, using MWCNTs as electrodes, was compared against that using commercial carbon cloth. PMID:22437017

  18. Silica-coated multi-walled carbon nanotubes impregnated with polyethyleneimine for carbon dioxide capture under the flue gas condition

    SciTech Connect

    Lee, Min-Sang; Park, Soo-Jin

    2015-03-15

    In this study, silica-coated multi-walled carbon nanotubes impregnated with polyethyleneimine (PEI) were prepared via a two-step process: (i) hydrolysis of tetraethylorthosilicate onto multi-walled carbon nanotubes, and (ii) impregnation of PEI. The adsorption properties of CO{sub 2} were investigated using CO{sub 2} adsorption–desorption isotherms at 298 K and thermogravimetric analysis under the flue gas condition (15% CO{sub 2}/85% N{sub 2}). The results obtained in this study indicate that CO{sub 2} adsorption increases after impregnation of PEI. The increase in CO{sub 2} capture was attributed to the affinity between CO{sub 2} and the amine groups. CO{sub 2} adsorption–desorption experiments, which were repeated five times, also showed that the prepared adsorbents have excellent regeneration properties. - Graphical abstract: Fabrication and CO{sub 2} adsorption process of the S-MWCNTs impregnated with PEI. - Highlights: • Silica coated-MWCNT impregnated with PEI was synthesized. • Amine groups of PEI gave CO{sub 2} affinity sites on MWCNT surfaces. • The S-MWCNT/PEI(50) exhibited the highest CO{sub 2} adsorption capacity.

  19. The functionalization of multi-walled carbon nanotubes by in situ deposition of hydroxyapatite.

    PubMed

    Xiao, Yu; Gong, Tao; Zhou, Shaobing

    2010-07-01

    A simple and effective approach was introduced to functionalize multi-walled carbon nanotubes (MWNTs) by in situ deposition of hydroxyapatite (HA) to improve their hydrophilicity and biocompatibility. Firstly, we prepared two types of pre-functionalized MWNTs: acid-oxidated MWNTs and covalently modified MWNTs by poly (ethylene glycol) (PEG). The influences of the acid-oxidated time, pre-phosphorylation, and PEGylation of MWNTs on in situ growth of HA were further investigated in simulated body fluid (SBF) with ionic concentration: 2, 5 and 10 times, respectively, at 37 degrees C for 24h. The results exhibited that all these factors have positive effects on the HA crystals growth, especially the PEGylation of MWNTs plays a key role during the deposition. Finally, the methyl thiazolyl tetrazolium (MTT) assay was performed to evaluate their cytotoxicity, which showed that the PEGylated MWNTs wrapped by HA crystals have the best biocompatibility. PMID:20392491

  20. Soft purification of N-doped and undoped multi-wall carbon nanotubes.

    PubMed

    Alvizo-Paez, Edgar Rogelio; Romo-Herrera, Jose Manuel; Terrones, Humberto; Terrones, Mauricio; Ruiz-Garcia, Jaime; Hernandez-Lopez, Jose Luis

    2008-04-16

    A soft method for purifying multi-wall carbon nanotubes (N-doped and undoped) is presented. The technique includes a hydrothermal/ultrasonic treatment of the material in conjunction with other subsequent treatments, including the extraction of polyaromatic compounds, dissolution of metal particles, bundle exfoliation, and uniform dispersion. This method avoids harsh oxidation protocols that burn (via thermal treatments) or functionalize (by introducing chemical groups) the nanotubes. We show a careful analysis of each purification step and demonstrate that the technique is extremely efficient when characterizing the materials using scanning electron microscopy (SEM), energy dispersive x-ray analysis (EDAX), scanning tuneling electron microscopy (STEM), x-ray powder diffraction (XRD), diffuse reflectance Fourier transform infrared (DRFTIR) spectroscopy and thermogravimetric analysis (TGA). PMID:21825625

  1. Electrical response of liquid crystal cells doped with multi-walled carbon nanotubes.

    PubMed

    García-García, Amanda; Vergaz, Ricardo; Algorri, José Francisco; Quintana, Xabier; Otón, José Manuel

    2015-01-01

    The inclusion of nanoparticles modifies a number of fundamental properties of many materials. Doping of nanoparticles in self-organized materials such as liquid crystals may be of interest for the reciprocal interaction between the matrix and the nanoparticles. Elongated nanoparticles and nanotubes can be aligned and reoriented by the liquid crystal, inducing noticeable changes in their optical and electrical properties. In this work, cells of liquid crystal doped with high aspect ratio multi-walled carbon nanotubes have been prepared, and their characteristic impedance has been studied at different frequencies and excitation voltages. The results demonstrate alterations in the anisotropic conductivity of the samples with the applied electric field, which can be followed by monitoring the impedance evolution with the excitation voltage. Results are consistent with a possible electric contact between the coated substrates of the LC cell caused by the reorientation of the nanotubes. The reversibility of the doped system upon removal of the electric field is quite low.

  2. Multiwalled carbon nanotubes anchored with maghemite nanocrystals for high-performance lithium storage

    SciTech Connect

    Wu, Ping Xie, Kongwei; Xu, Xiali; Li, Jianping; Tang, Yawen; Zhou, Yiming Lu, Tianhong

    2015-04-15

    Highlights: • γ-Fe{sub 2}O{sub 3} nanocrystals uniformly anchored on MWCNT via facile layer-by-layer technique. • The hybrid exhibits enhanced structural stability and charge transport capability. • Superior lithium storage performance by virtue of unique structural characteristics. - Abstract: In this paper, we have anchored maghemite (γ-Fe{sub 2}O{sub 3}) nanocrystals compactly and uniformly on multiwalled carbon nanotubes (MWCNT) via a polyelectrolyte-assisted layer-by-layer assembly approach based on electrostatic attraction. When evaluated as an anode for lithium-ion batteries (LIBs), the as-synthesized MWCNT-γ-Fe{sub 2}O{sub 3} nanohybrid displays high reversible capacities, remarkable cycling stability, and magnificent high rate capability, facilitating its application as an advanced anode for high-energy, long-life, and high-power LIBs.

  3. In situ Raman spectroscopy for growth monitoring of vertically aligned multiwall carbon nanotubes in plasma reactor

    SciTech Connect

    Labbaye, T.; Gaillard, M.; Lecas, T.; Kovacevic, E.; Boulmer-Leborgne, Ch.; Guimbretière, G.; Canizarès, A.; Raimboux, N.; Simon, P.; Ammar, M. R.; Strunskus, T.

    2014-11-24

    Portable and highly sensitive Raman setup was associated with a plasma-enhanced chemical vapor deposition reactor enabling in situ growth monitoring of multi-wall carbon nanotubes despite the combination of huge working distance, high growth speed and process temperature and reactive plasma condition. Near Edge X-ray absorption fine structure spectroscopy was used for ex situ sample analysis as a complementary method to in situ Raman spectroscopy. The results confirmed the fact that the “alternating” method developed here can accurately be used for in situ Raman monitoring under reactive plasma condition. The original analytic tool can be of great importance to monitor the characteristics of these nanostructured materials and readily define the ultimate conditions for targeted results.

  4. Three-dimensional nitrogen-doped multiwall carbon nanotube sponges with tunable properties.

    PubMed

    Shan, Changsheng; Zhao, Wenjie; Lu, X Lucas; O'Brien, Daniel J; Li, Yupeng; Cao, Zeyuan; Elias, Ana Laura; Cruz-Silva, Rodolfo; Terrones, Mauricio; Wei, Bingqing; Suhr, Jonghwan

    2013-01-01

    A three-dimensional (3D) nitrogen-doped multiwall carbon nanotube (N-MWCNT) sponge possessing junctions induced by both nitrogen and sulfur was synthesized by chemical vapor deposition (CVD). The formation of "elbow" junctions as well as "welded" junctions, which are attributed to the synergistic effect of the nitrogen dopant and the sulfur promoter, plays a critically important role in the formation of 3D nanotube sponges. To the best of our knowledge, this is the first report showing the synthesis of macroscale 3D N-MWCNT sponges. Most importantly, the diameter of N-MWCNT can be simply controlled by varying the concentration of sulfur, which in turn controls both the sponge's mechanical and its electrical properties. It was experimentally shown that, with increasing diameter of N-MWCNT, the elastic modulus of the sponge increased while the electrical conductivity decreased. The mechanical behaviors of the sponges have also been quantitatively analyzed by employing strain energy function modeling.

  5. One-step preparation of multiwall carbon nanotube/silicon hybrids for solar energy conversion

    NASA Astrophysics Data System (ADS)

    Lobiak, Egor V.; Bychanok, Dzmitry S.; Shlyakhova, Elena V.; Kuzhir, Polina P.; Maksimenko, Sergey A.; Bulusheva, Lyubov G.; Okotrub, Alexander V.

    2016-03-01

    The hybrid material consisting of a thin layer of multiwall carbon nanotubes (MWCNTs) on an n-doped silicon wafer was obtained in one step using an aerosol-assisted catalytic chemical vapor deposition. The MWCNTs were grown from a mixture of acetone and ethanol with ˜0.2 wt.% of iron polyoxomolybdate nanocluster of the keplerate-type structure. The samples produced at 800°C and 1050°C were tested as a solar energy converter. It was shown that photoresponse of the hybrid material significantly depends on the presence of structural defects in MWCNTs, being much higher in the case of more defective nanotubes. This is because defects lead to p-doping of nanotubes, whereas the p-n heterojunction between MWCNTs and silicon provides a high efficiency of the solar cell.

  6. The toxicity to plants of the sewage sludges containing multiwalled carbon nanotubes.

    PubMed

    Oleszczuk, Patryk; Jośko, Izabela; Xing, Baoshan

    2011-02-15

    The aim of this study was to evaluate the toxicity of sewage sludges containing multiwalled carbon nanotubes (CNTs) with an outer diameter <10 nm (CNT10) or 40-60 nm (CNT60) to Lepidium sativum (cress), Sorghum saccharatum (sorgo), Solanum lycopersicon (tomato), Raphanus sativus (radish) and Cucumis sativus (cucumber). CNTs were also incubated in sewage sludge for 7 or 31 days to determine the effect of CNT aging on sewage sludge phytotoxicity. The influence of CNTs on 4 different sewage sludges was tested. The CNTs' influence on sludge toxicity varied with respect to the CNTs' outer diameter, type of sewage sludges and the plants tested. No significant influence of CNT concentration on phytotoxicity was noted. In the case of two sludges, a positive influence of CNTs on seed germination and root growth was observed. Depending on the CNTs' outer diameter, CNT aging decreased (CNT10) or increased (CNT60) sewage sludge phytotoxicity. PMID:21145166

  7. Externally limited defect generation in multiwalled carbon nanotubes upon thermal annealing, and possible mechanism

    NASA Astrophysics Data System (ADS)

    Bhalerao, G. M.; Sinha, A. K.; Srivastava, A. K.; Sathe, V.; Amarendra, G.

    2016-09-01

    Structural defects in multiwalled carbon nanotubes (MWCNTs) are found to increase upon moderate thermal annealing below 1400 K in an argon atmosphere. The defects are estimated using the ID/IG ratio in Raman spectroscopy of MWCNTs and confirmed by a direct observation using high-resolution transmission electron microscopy (HRTEM). HRTEM shows that the structural defects are created due to large damage to the outer walls of the nanotubes, while inner walls do not sustain any damage. The generation of defects on MWCNTs is attibuted to mechanical abrasion between the MWCNTs in contact, augmented by the momentum transfer from the flow of hot gas. A possible mechanism is proposed and experimentally validated by means of modulating the chemical environment of annealing from argon to hydrogen.

  8. Morphology adjustments of multi-walled carbon nanotubes by laser irradiation

    NASA Astrophysics Data System (ADS)

    Yuan, Yanping; Chen, Jimin

    2016-06-01

    In this study, nanoscale welding quality and morphology changes of multi-walled carbon nanotubes are investigated by changing laser wavelengths and the irradiation time. Lasers with 1064 nm and 355 nm are used in our experiments. The 1064 nm laser can lead to nanowelding with good quality, while the 355 nm laser changes the curvature. The experiments demonstrate that the morphology, structures and the welding quality can be adjusted by changing laser wavelengths. In this letter, the dynamic process of nanostructures changing is studied by changing the irradiation time. The experimental results show that the morphology and structures can be controlled by adjusting the irradiation time. The detailed dynamic process of nanostructures changing confirms the formation mechanism of nano-welding and the thermal effects during the process.

  9. Preparation, purification and characterization of high purity multi-wall carbon nanotube

    NASA Astrophysics Data System (ADS)

    Morsy, Mohamed; Helal, Magdy; El-Okr, Mohamed; Ibrahim, Medhat

    2014-11-01

    Chemical vapor deposition (CVD) was optimized in order to prepare multi-wall carbon nanotubes (MWCNTs). Preparation of MWCNTs was achieved by the help of ferrocene as a catalyst with continuous flow of xylene. Morphology and structure of as grown and purified MWCNTs were characterized by Scanning Electron Microscope (SEM) and High-Resolution Transmission Electron Microscope (HRTEM). Energy Dispersive X-ray (EDX) spectra for the as grown MWCNTs confirm that the deposits are carbonaceous materials. XRD pattern of purified sample indicates that the Fe peaks at 44.6 and 50.9 have been decreased. This confirms that purification process is effectively reducing Fe component. Further qualitative information on the purification process are indicated and confirmed by the thermal analysis measurements. Finally, FTIR studies have been performed for the identification of the functional group attached on the surface of the MWCNTs. Collecting these results revealed that the optimized CVD is suitable for the production of MWCNTs.

  10. Anchorage of γ-Al2O3 nanoparticles on nitrogen-doped multiwalled carbon nanotubes

    DOE PAGES

    Rodríguez-Pulido, A.; Martínez-Gutiérrez, H.; Calderon-Polania, G. A.; Lozano, M. A. Gonzalez; Cullen, D. A.; Terrones, H.; Smith, D. J.; Terrones, M.

    2016-06-07

    Nitrogen-doped multiwalled carbon nanotubes (CNx-MWNTs) have been decorated with γ-Al2O3 nanoparticles by a novel method. This process involved a wet chemical approach in conjunction with thermal treatment. During the particle anchoring process, individual CNx-MWNT nanotubes agglomerated into bundles, resulting in arrays of aligned CNx-MWNT coated with γ-Al2O3. Extensive characterization of the resulting γ-Al2O3/CNx-MWNT bundles was performed using a range of electron microscopy imaging and microanalytical techniques. In conclusion, a possible mechanism explaining the nanobundle alignment is described, and possible applications of these materials for the fabrication of ceramic composites using CNx-MWNTs are briefly discussed.

  11. Vertically aligned multiwalled carbon nanotubes for pressure, tactile and vibration sensing

    NASA Astrophysics Data System (ADS)

    Yilmazoglu, O.; Popp, A.; Pavlidis, D.; Schneider, J. J.; Garth, D.; Schüttler, F.; Battenberg, G.

    2012-03-01

    We report a simple method for the micro-nano integration of flexible, vertically aligned multiwalled CNT arrays sandwiched between a top and bottom carbon layer via a porous alumina (Al2O3) template approach. The electromechanical properties of the flexible CNT arrays have been investigated under mechanical stress conditions. First experiments show highly sensitive piezoresistive sensors with a resistance decrease of up to ˜35% and a spatial resolution of <1 mm. The results indicate that these CNT structures can be utilized for tactile sensing components. They also confirm the feasibility of accessing and utilizing nanoscopic CNT bundles via lithographic processing. The method involves room-temperature processing steps and standard microfabrication techniques.

  12. Planarized arrays of aligned, untangled multiwall carbon nanotubes with Ohmic back contacts

    DOE PAGES

    Rochford, C.; Limmer, S. J.; Howell, S. W.; Beechem, T. E.; Siegal, M. P.

    2014-11-26

    Vertically aligned, untangled planarized arrays of multiwall carbon nanotubes (MWNTs) with Ohmic back contacts were grown in nanopore templates on arbitrary substrates. The templates were prepared by sputter depositing Nd-doped Al films onto W-coated substrates, followed by anodization to form an aluminum oxide nanopore array. The W underlayer helps eliminate the aluminum oxide barrier that typically occurs at the nanopore bottoms by instead forming a thin WO3 layer. The WO3 can be selectively etched to enable electrodeposition of Co catalysts with control over the Co site density. This led to control of the site density of MWNTs grown by thermalmore » chemical vapor deposition, with the W also serving as a back electrical contact. As a result, Ohmic contact to MWNTs was confirmed, even following ultrasonic cutting of the entire array to a uniform height.« less

  13. The functionalization and characterization of multi-walled carbon nanotubes (MWCNTs)

    SciTech Connect

    Abdullah, Mohd Pauzi; Zulkepli, Siti Aminah

    2015-09-25

    Functionalization is the process of introducing chemical functional groups on the surface of the material. In this study, a multi-walled carbon nanotube (MWCNTs) was functionalized by oxidation treatment using concentrated nitric acid. The functionalized and pristine MWCNTs were analyzed by using Fourier Transform Infrared Spectroscopy (FT-IR) and X-Ray Diffraction (XRD). The XRD patterns exhibit the graphitic properties for all samples. Besides, the XRD results also demonstrate that the percent of crystallinity of MWCNTs increases as the duration of acid treatment increases. The percent of crystallinity increases from 66% to 80% when the pristine MWCNT treated for 12 hours with additional 12 hours reflux process with nitric acid. The IR spectrum for the 12 hours-treated MWCNTs shows the formation of carboxyl functional group. Additional 12 hours reflux process with nitric acid on the 12 hours-treated MWCNTs have shown the loss of existing carboxyl group and only hydroxyl group formed.

  14. Electrical response of liquid crystal cells doped with multi-walled carbon nanotubes.

    PubMed

    García-García, Amanda; Vergaz, Ricardo; Algorri, José Francisco; Quintana, Xabier; Otón, José Manuel

    2015-01-01

    The inclusion of nanoparticles modifies a number of fundamental properties of many materials. Doping of nanoparticles in self-organized materials such as liquid crystals may be of interest for the reciprocal interaction between the matrix and the nanoparticles. Elongated nanoparticles and nanotubes can be aligned and reoriented by the liquid crystal, inducing noticeable changes in their optical and electrical properties. In this work, cells of liquid crystal doped with high aspect ratio multi-walled carbon nanotubes have been prepared, and their characteristic impedance has been studied at different frequencies and excitation voltages. The results demonstrate alterations in the anisotropic conductivity of the samples with the applied electric field, which can be followed by monitoring the impedance evolution with the excitation voltage. Results are consistent with a possible electric contact between the coated substrates of the LC cell caused by the reorientation of the nanotubes. The reversibility of the doped system upon removal of the electric field is quite low. PMID:25821679

  15. Skin effect mitigation in laser processed multi-walled carbon nanotube/copper conductors

    SciTech Connect

    Keramatnejad, K.; Zhou, Y. S.; Gao, Y.; Rabiee Golgir, H.; Wang, M.; Lu, Y. F.; Jiang, L.; Silvain, J.-F.

    2015-10-21

    In this study, laser-processed multi-walled carbon nanotube (MWCNT)/Cu conductors are introduced as potential passive components to mitigate the skin effect of Cu at high frequencies (0–10 MHz). Suppressed skin effect is observed in the MWCNT/Cu conductors compared to primitive Cu. At an AC frequency of 10 MHz, a maximum AC resistance reduction of 94% was observed in a MWCNT/Cu conductor after being irradiated at a laser power density of 189 W/cm{sup 2}. The reduced skin effect in the MWCNT/Cu conductors is ascribed to the presence of MWCNT channels which are insensitive to AC frequencies. The laser irradiation process is observed to play a crucial role in reducing contact resistance at the MWCNT-Cu interfaces, removing impurities in MWCNTs, and densifying MWCNT films.

  16. Substituted copper phthalocyanine/multiwalled carbon nanotubes hybrid material for Cl{sub 2} sensing application

    SciTech Connect

    Sharma, Anshul Kumar Saini, Rajan Singh, Rajinder Mahajan, Aman Bedi, R. K.; Aswal, D. K.

    2014-04-24

    In this work, hybrid of soluble copper phthalocyanine (CuPcOC{sub 8}) and functionalized multi-walled carbon nanotubes (MWCNTs) has been synthesized. The formation of CuPcOC{sub 8}-MWCNTs hybrid is confirmed by atomic force microscopy, UV-Visible and FTIR spectroscopy. Subsequently, a chemi-resistive sensor is fabricated by drop casting CuPcOC{sub 8}-MWCNTs hybrid onto glass substrate. It has been demonstrated that CuPcOC{sub 8}-MWCNTs hybrid is highly selective towards Cl{sub 2} gas with minimum detection limit of 100 ppb. The response of sensor increases linearly with increase in the concentration of Cl{sub 2} gas. For 2000 ppb of Cl{sub 2}, CuPcOC{sub 8}-MWCNTs hybrid gives a response as large as 53% in 40 seconds.

  17. Tuning the dispersion of multiwall carbon nanotubes in co-continuous polymer blends: a generic approach

    NASA Astrophysics Data System (ADS)

    Bose, Suryasarathi; Bhattacharyya, Arup R.; Khare, Rupesh A.; Kulkarni, Ajit R.; Umasankar Patro, T.; Sivaraman, P.

    2008-08-01

    Melt-mixed blends of polyamide 6 and acrylonitrile-butadiene-styrene (PA6/ABS) with multiwall carbon nanotubes (MWNTs) were prepared with the intention to develop conducting composites. A generic strategy, namely specific interactions combined with reactive coupling, was adopted to facilitate and to retain the 'network-like' structure of MWNTs during melt-mixing. This was facilitated by the sodium salt of 6-amino hexanoic acid (Na-AHA) and certain phosphonium based modifiers, where it was envisaged that these modifiers would establish specific interactions (either 'cation-π' or 'π-π' ) with the 'π-electron' clouds of MWNTs, as well as restricting them in the PA6 phase of the blends via reactive coupling. This route eventually led to a remarkable increase in the electrical conductivity and dielectric constant in the blends with MWNTs. Raman, FTIR and TEM investigations further supported these observations.

  18. Nickel and nickel oxide nanocrystals selectively grafting on multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Prabhu, Yendrapati Taraka; Rao, Kalagadda Venkateswara; Kumari, Bandla Siva; Sai, Vemula Sesha; Pavani, Tambur

    2015-01-01

    Nickel and nickel oxide nanocrystals in their pure phase are carefully embellished by a facial method on oxygen-functionalized multi-walled carbon nanotubes (O-MWCNTs) using nickel nitrate (NN) was effectively accomplished for the first time by calcining them in hydrogen, nitrogen and air, respectively, at suitable temperatures. Nickel and nickel oxide nanocrystals impregnated O-MWCNTs were examined for its structure and morphology by various techniques, such as powder X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy and field emission scanning electron microscopy. The nanocrystals on the O-MWCNTs were determined of 15-20 nm size. Decorated nanocrystals on CNT's have potential applications in semiconductor industries.

  19. Current-conducting properties of paper consisting of multiwall carbon nanotubes

    SciTech Connect

    Tkachev, E. N.; Buryakov, T. I.; Kuznetsov, V. L.; Moseenkov, S. I.; Mazov, I. N.; Popkov, S. I.; Shaikhutdinov, K. A.

    2013-05-15

    Electrical conductivity {sigma}(T) of the paper consisting of multiwalled carbon nanotubes (MWCNTs) is studied in the temperature range 4.2-295 K, and its magnetoresistivity {rho}(B) at various temperatures in magnetic fields up to 9 T is analyzed. The temperature dependence of the paper electrical conductivity {sigma}(T) exhibits two-dimensional quantum corrections to the conductivity below 10 K. The dependences of negative magnetoresistivity {rho}(B) measured at various temperatures are used to estimate the wavefunction phase breakdown length L{sub {phi}} of conduction electrons and to obtain the temperature dependence L{sub {phi}} = constT{sup -p/2}, where p Almost-Equal-To 1/3. Similar dependences of electrical conductivity {sigma}(T), magnetoresistivity {rho}(B), and phase breakdown length L{sub {phi}}(T) are detected for the initial MWCNTs used to prepare the paper.

  20. Heating efficiency of multi-walled carbon nanotubes in the first and second biological windows.

    PubMed

    Maestro, Laura Martínez; Haro-González, Patricia; del Rosal, Blanca; Ramiro, Julio; Caamaño, A J; Carrasco, Elisa; Juarranz, Angeles; Sanz-Rodríguez, Francisco; Solé, José García; Jaque, Daniel

    2013-09-01

    Quantum dot based-thermometry, in combination with double beam confocal microscopy and infrared thermal imaging, has been used to investigate the heating efficiency of multi-walled carbon nanotubes (MWCNTs) under optical excitation within the first (808 nm) and second (1090 nm) biological windows as well as in the spectral region separating them (980 nm). It has been found that for the three excitation wavelengths the heating efficiency of MWCNTs (10 nm in diameter and 1.5 μm in length) is close to 50%. Despite this "flat" heating efficiency, we have found that the excitation wavelength is, indeed, critical during in vivo experiments due to the spectral dependence of both tissue absorption and scattering coefficients. It has been concluded that efficiency and selectivity of in vivo photothermal treatments based on MWCNTs are simultaneously optimized when laser irradiation lies within the first or second biological window.

  1. Effect of multiwalled carbon nanotubes on electrical conductivity and magnetoconductivity of polyaniline

    NASA Astrophysics Data System (ADS)

    Chakraborty, Goutam; Gupta, Kajal; Rana, Dipak; Meikap, Ajit Kumar

    2012-09-01

    An in situ chemical polymerization method was applied in order to prepare polyaniline-multiwalled carbon nanotube (PANI-MWCNT) composites with different concentrations of MWCNT. X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, optical absorption and photoluminescence analyses of the composites were performed to investigate the structural, morphological and optical properties of the composites. Electrical transport properties of different PANI-MWCNT composites were investigated in the temperature range 77 K ⩽ T ⩽ 300 K in the presence and also in the absence of a magnetic field up to 1 T. The dc resistivity of the composites follows Mott's variable range hopping theory. Two different slopes have been observed in temperature variation of resistivity, which occurs due to the presence of MWCNT in the polymer matrix. The magnetoconductivity of the samples at different temperatures is negative, which can be explained by the wavefunction shrinkage effect.

  2. Solid Lubrication by Multiwalled Carbon Nanotubes in Air and in Vacuum for Space and Aeronautics Applications

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa; Street, Kenneth W., Jr.; Andraws, Rodney; Jacques, David; VanderWal, Randy L.; Sayir, Ali

    2005-01-01

    To evaluate recently developed aligned multiwalled carbon nanotubes (MWNTs) and dispersed MWNTs for solid lubrication applications, unidirectional sliding friction experiments were conducted with 440 C stainless steel balls and hemispherical alumina-yttria stabilized zirconia pins in sliding contact with the MWNTs deposited on quartz disks in air and in vacuum. The results indicate that MWNTs have superior solid lubrication friction properties and endurance lives in air and vacuum under dry conditions. The coefficient of friction of the dispersed MWNTs is close to 0.05 and 0.009 in air and in vacuum, respectively, showing good dry lubricating ability. The wear life of MWNTs exceeds 1 million passes in both air and vacuum showing good durability. In general, the low coefficient of friction can be attributed to the combination of the transferred, agglomerated patches of MWNTs on the counterpart ball or pin surfaces and the presence of tubular MWNTs at interfaces.

  3. Displacement and competitive sorption of organic pollutants on multiwalled carbon nanotubes.

    PubMed

    Shen, Xiaofang; Wang, Xilong; Tao, Shu; Xing, Baoshan

    2014-10-01

    Displacement of lindane presorbed on the pristine and OH-functionalized multiwalled carbon nanotubes (MWCNTs) by phenanthrene, naphthalene, and atrazine, and competition of these compounds with lindane on the aforementioned sorbents were investigated. Displacement of lindane presorbed on MWCNTs by atrazine, naphthalene, and phenanthrene, and competitive sorption effect of these chemicals with lindane on MWCNTs followed the same order: atrazine > naphthalene > phenanthrene. The lowest competition and displacement of lindane by phenanthrene were mainly because of the strong interactions between these two chemicals, whereas interaction of lindane with atrazine and naphthalene was quite low. The more pronounced displacement of lindane by atrazine than naphthalene and higher competitive sorption of lindane with atrazine than with naphthalene can be ascribed to the larger molecular volume of atrazine; thus, the steric hindrance effect is higher relative to naphthalene. This study is valuable for evaluating influence of the coexisting organic compounds on sorption of primary solute towards MWCNTs in the environment.

  4. Multiwalled carbon nanotube/polydimethylsiloxane composite films as high performance flexible electric heating elements

    NASA Astrophysics Data System (ADS)

    Yan, Jing; Jeong, Young Gyu

    2014-08-01

    High performance elastomeric electric heating elements were prepared by incorporating various contents of pristine multiwalled carbon nanotube (MWCNT) in polydimethylsiloxane (PDMS) matrix by using an efficient solution-casting and curing technique. The pristine MWCNTs were identified to be uniformly dispersed in the PDMS matrix and the electrical percolation of MWCNTs was evaluated to be at ˜0.27 wt. %, where the electrical resistivity of the MWCNT/PDMS composite films dropped remarkably. Accordingly, the composite films with higher MWCNT contents above 0.3 wt. % exhibit excellent electric heating performance in terms of temperature response rapidity and electric energy efficiency at constant applied voltages. In addition, the composite films, which were thermally stable up to 250 °C, showed excellent heating-cooling cyclic performance, which was associated with operational stability in actual electric heating applications.

  5. Facile synthesis of stable superhydrophobic nanocomposite based on multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Mokarian, Zahra; Rasuli, Reza; Abedini, Yousefali

    2016-04-01

    A facile approach to fabricate a stable superhydrophobic composite comprising multi-walled carbon nanotubes and silicone rubber has been reported. Contact angle of de-ionized water droplets on the prepared surface was measured with the value of near 159°; while water droplets easily rolled off and bounced on it. Surface free energy of the superhydrophobic coating was examined by three methods about 26 mJ/m2. The prepared film shows good stability under high stress conditions such as ultraviolet exposure, heating, pencil hardness test, attacking with different pH value and ionic-strength solutions. In addition, remarkable stability of the coating was observed after soaking in condensed hydrochloric acid, 5 wt.% NaCl aqueous solution, boiling water and tape test.

  6. Development of multi-walled carbon nanotubes reinforced monetite bionanocomposite cements for orthopedic applications.

    PubMed

    Boroujeni, Nariman Mansoori; Zhou, Huan; Luchini, Timothy J F; Bhaduri, Sarit B

    2013-10-01

    In this study, we present results of our research on biodegradable monetite (DCPA, CaHPO4) cement with surface-modified multi-walled carbon nanotubes (mMWCNTs) as potential bone defect repair material. The cement pastes showed desirable handling properties and possessed a suitable setting time for use in surgical setting. The incorporation of mMWCNTs shortened the setting time of DCPA and increased the compressive strength of DCPA cement from 11.09±1.85 MPa to 21.56±2.47 MPa. The cytocompatibility of the materials was investigated in vitro using the preosteoblast cell line MC3T3-E1. An increase of cell numbers was observed on both DCPA and DCPA-mMWCNTs. Scanning electron microscopy (SEM) results also revealed an obvious cell growth on the surface of the cements. Based on these results, DCPA-mMWCNTs composite cements can be considered as potential bone defect repair materials.

  7. Comparison of quasistatic to impact mechanical properties of multiwall carbon nanotube/polycarbonate composites

    SciTech Connect

    Brühwiler, Paul A.; Barbezat, Michel; Necola, Adly; Kohls, Doug J.; Bunk, Oliver; Schaefer, Dale W.; Pötschke, Petra

    2010-10-22

    We report the quasistatic tensile and impact penetration properties (falling dart test) of injection-molded polycarbonate samples, as a function of multiwall carbon nanotube (MWNT) concentration (0.0-2.5%). The MWNT were incorporated by dilution of a commercial MWNT/polycarbonate masterbatch. The stiffness and quasistatic yield strength of the composites increased approximately linearly with MWNT concentration in all measurements. The energy absorbed in fracture was, however, a negative function of the MWNT concentration, and exhibited different dependencies in quasistatic and impact tests. Small-angle x-ray scattering (SAXS) showed that the dispersion of the MWNT was similar at all concentrations. The negative effects on energy absorption are attributed to agglomerates remaining in the samples, which were observed in optical microscopy and SAXS. Overall, there was a good correspondence between static and dynamic energy absorption.

  8. Micro/Nanomechanical characterization of multi-walled carbon nanotubes reinforced epoxy composite.

    PubMed

    Cui, Peng; Wang, Xinnan; Tangpong, X W

    2012-11-01

    In this paper, the mechanical properties of 1 wt.% multi-walled carbon nanotubes (MWCNTs) reinforced epoxy nanocomposites were characterized using a self-designed micro/nano three point bending tester that was on an atomic force microscope (AFM) to in situ observe MWCNTs movement on the sample surface under loading. The migration of an individual MWCNT at the surface of the nanocomposite was tracked to address the nanomechanical reinforcing mechanism of the nanocomposites. Through morphology analysis of the nanocomposite via scanning electron microscopy, AFM, and digital image correlation technique, it was found that the MWCNTs agglomerate and the bundles were the main factors for limiting the bending strength of the composites. The agglomeration/bundle effect was included in the Halpin-Tsai model to account for the elastic modulus of the nanocomposites.

  9. Comparative temporal analysis of multiwalled carbon nanotube oxidation reactions: Evaluating chemical modifications on true nanotube surface

    NASA Astrophysics Data System (ADS)

    Pacheco, Flávia G.; Cotta, Alexandre A. C.; Gorgulho, Honória F.; Santos, Adelina P.; Macedo, Waldemar A. A.; Furtado, Clascídia A.

    2015-12-01

    The influence of extensive purification on oxidized multiwalled carbon nanotube surface composition was studied through the characterization and differentiation of the actual surface submitted to three oxidation methods: microwave-assisted acid oxidation, hydrogen peroxide reflux, and Fenton reaction. The oxidized samples were purified by a multi-step procedure including the sequential use of basic reflux and dispersion in dimethylformamide (DMF). The results showed a significant increase in the amount of oxidation debris with hydrogen peroxide and Fenton reaction times longer than 8 h and strong surface characteristic modification. With regard to sample purification, basic reflux led to a reduction in oxygenated group concentration of only 10% in the samples treated by acid oxidation. On the other hand, the subsequent use of DMF led to a further decrease in concentration of 39%, proving to be a more efficient method for the removal of oxidation debris.

  10. Rheology, Morphology and Temperature Dependency of Nanotube Networks in Polycarbonate/Multiwalled Carbon Nanotube Composites

    SciTech Connect

    Abbasi, Samaneh; Carreau, Pierre J.; Derdouri, Abdessalem

    2008-07-07

    We present several issues related to the state of dispersion and rheological behavior of polycarbonate/multiwalled carbon nanotube (MWCNT) composites. The composites were prepared by diluting a commercial masterbatch containing 15 wt% nanotubes using optimized melt-mixing conditions. The state of dispersion was then analyzed by scanning and transmission electron microscopy (SEM, TEM). Rheological characterization was also used to assess the final morphology. Further, it was found that the rheological percolation threshold decreased significantly with increasing temperature and finally reached a constant value. This is described in terms of the Brownian motion, which increases with temperature. However, by increasing the nanotube content, the temperature effects on the complex viscosity at low frequency decreased significantly. Finally, the percolation thresholds were found to be approximately equal to 0.3 and 2 wt% for rheological and electrical conductivity measurements, respectively.

  11. Multiwalled carbon nanotube/polydimethylsiloxane composite films as high performance flexible electric heating elements

    SciTech Connect

    Yan, Jing; Jeong, Young Gyu

    2014-08-04

    High performance elastomeric electric heating elements were prepared by incorporating various contents of pristine multiwalled carbon nanotube (MWCNT) in polydimethylsiloxane (PDMS) matrix by using an efficient solution-casting and curing technique. The pristine MWCNTs were identified to be uniformly dispersed in the PDMS matrix and the electrical percolation of MWCNTs was evaluated to be at ∼0.27 wt. %, where the electrical resistivity of the MWCNT/PDMS composite films dropped remarkably. Accordingly, the composite films with higher MWCNT contents above 0.3 wt. % exhibit excellent electric heating performance in terms of temperature response rapidity and electric energy efficiency at constant applied voltages. In addition, the composite films, which were thermally stable up to 250 °C, showed excellent heating-cooling cyclic performance, which was associated with operational stability in actual electric heating applications.

  12. Effect of top metal contact on the electrical properties of suspended spiral multiwalled carbon nanotube

    SciTech Connect

    Dhall, Shivani Jaggi, Neena

    2014-04-24

    The electrical transport behavior of individual spiral multiwalled carbon nanotube (MWCNT), functionalized via chemical route, has been investigated. The electrical current and conductance of such dangling bond attached tube, has been increased, after deposition of platinum (Pt) metal contacts at the two ends using electron beam induced deposition technique (EBID). The increment in the conductance is explained in terms of the change in the density of the states (DOS) near the Fermi level by dangling bonds and Pt atoms presence on the tube. Scanning electron microscope (SEM) image confirms its spiral nature after functionalization. Current –voltage measurements reveal a significant enhancement in the electrical transport of the same tube after the deposition of side metal contact. These results can be useful for the fabrication of nanoelectronic devices.

  13. Multiwalled carbon nanotubes grown in hydrogen atmosphere: An x-ray diffraction study

    SciTech Connect

    Maniwa, Yutaka; Fujiwara, Ryuji; Kira, Hiroshi; Tou, Hideki; Nishibori, Eiji; Takata, Masaki; Sakata, Makoto; Fujiwara, Akihiko; Zhao, Xinluo; Iijima, Sumio

    2001-08-15

    X-ray diffraction study of multiwalled carbon nanotube (MWNT) grown by arc discharge in hydrogen atmosphere is presented. It is found that the thermal-expansion coefficient along the radial direction of MWNT is widely distributed in a range from 1.6 x 10{sup -5} K{sup -1} to 2.6 x 10{sup -5} K{sup -1}, indicating the existence of both of Russian doll MWNT and highly defective MWNT. Russian doll MWNT is suggested to have the outer diameter less than {approx}100 Aa. Thicker MWNT's are typically highly defective, and may have the jelly roll (scroll) or defective polygonal structure consisting of flat graphite domains.

  14. Planarized arrays of aligned, untangled multiwall carbon nanotubes with Ohmic back contacts

    SciTech Connect

    Rochford, C.; Limmer, S. J.; Howell, S. W.; Beechem, T. E.; Siegal, M. P.

    2014-11-26

    Vertically aligned, untangled planarized arrays of multiwall carbon nanotubes (MWNTs) with Ohmic back contacts were grown in nanopore templates on arbitrary substrates. The templates were prepared by sputter depositing Nd-doped Al films onto W-coated substrates, followed by anodization to form an aluminum oxide nanopore array. The W underlayer helps eliminate the aluminum oxide barrier that typically occurs at the nanopore bottoms by instead forming a thin WO3 layer. The WO3 can be selectively etched to enable electrodeposition of Co catalysts with control over the Co site density. This led to control of the site density of MWNTs grown by thermal chemical vapor deposition, with the W also serving as a back electrical contact. As a result, Ohmic contact to MWNTs was confirmed, even following ultrasonic cutting of the entire array to a uniform height.

  15. Magnetic molecularly imprinted polydopamine nanolayer on multiwalled carbon nanotubes surface for protein capture.

    PubMed

    Yin, Yuli; Yan, Liang; Zhang, Zhaohui; Wang, Jing

    2015-11-01

    A novel, facile and low cost process for imprinting protein on the surface of magnetic multiwalled carbon nanotubes (MMWNTs) was developed using human serum albumin (HSA) as the template and dopamine as the functional monomer. The magnetic imprinted polymers were characterized with transmission electron microscope (TEM), scanning electron microscope (SEM), Fourier-transform infrared spectrometry (FT-IR), vibrating sample magnetometer (VSM) and thermogravimetric analysis (TGA) in detail. The maximum adsorption capacity of the magnetic imprinted polymers toward HSA was 66.23 mg g(-1) and it took 20 min to achieve the adsorption equilibrium. The magnetic imprinted polymers exhibited the specific selective adsorption toward HSA. Coupled with high performance liquid chromatography (HPLC) analysis, the magnetic imprinted polymers were used to solid-phase extract and detect HSA in urine samples successfully with the recoveries of 91.95-97.8%.

  16. Adsorption of Arsenic on Multiwall Carbon Nanotube–Zirconia Nanohybrid for Potential Drinking Water Purification

    PubMed Central

    AddoNtim, Susana; Mitra, Somenath

    2012-01-01

    The adsorptive removal of arsenic from water using a multiwall carbon nanotube-zirconia nanohybrid (MWCNT-ZrO2) is presented. The MWCNT-ZrO2 with 4.85% zirconia was effective in meeting the drinking water standard levels of 10 μg L−1. The absorption capacity of the composite were 2000 μg g−1 and 5000 μg g−1 for As (III) and As (V) respectively, which were significantly higher than those reported previously for iron oxide coated MWCNTs. The adsorption of As (V) on MWCNT-ZrO2 was faster than that of As (III), and a pseudo-second order rate equation effectively described the uptake kinetics. The adsorption isotherms for As (III) and As (V) fitted both the Langmuir and Freundlich models. A major advantage of the MWCNT-ZrO2 was that the adsorption capacity was not a function of pH. PMID:22424815

  17. Electrophoretically deposited multiwalled carbon nanotube based amperometric genosensor for E.coli detection

    NASA Astrophysics Data System (ADS)

    Bhardwaj, Hema; Solanki, Shipra; Sumana, Gajjala

    2016-04-01

    This work reports on a sensitive and selective genosensor fabrication method for Escherichia coli (E.coli) detection. The functionalized multiwalled carbon nanotubes (MWCNT) synthesized via chemical vapour deposition have been deposited electrophoretically onto indium tin oxide coated glass surface and have been utilized as matrices for the covalent immobilization of E.coli specific probe oligonucleotide that was identified from the 16s rRNA coding region of the E.coli genome. This fabricated functionalized MWCNT based platform sought to provide improved fundamental characteristics to electrode interface in terms of electro-active surface area and diffusion coefficient. Electrochemical cyclic voltammetry revealed that this genosensor exhibits a linear response to complementary DNA in the concentration range of 10-7 to 10-12 M with a detection limit of 1×10-12 M.

  18. Phytotoxicity of multi-walled carbon nanotubes assessed by selected plant species in the seedling stage

    NASA Astrophysics Data System (ADS)

    Begum, Parvin; Ikhtiari, Refi; Fugetsu, Bunshi; Matsuoka, Makoto; Akasaka, Tsukasa; Watari, Fumio

    2012-12-01

    Abundant experimental data have shown that multi-walled carbon nanotubes (MWNTs) are toxic to plants, but the potential impacts of exposure remain unclear. The objective of the present study was to evaluate possible phytotoxicity of MWNTs at 0, 20, 200, 1000, and 2000 mg/L with red spinach, lettuce, rice, cucumber, chili, lady's finger, and soybean based on root and shoot growth, cell death, and electrolyte leakage at the seedling stage. After 15 days of hydroponic culture, the root and shoot lengths of red spinach, lettuce, and cucumber were significantly reduced following exposure to 1000 mg/L and 2000 mg/L MWNTs. Similar toxic effects occurred regarding cell death and electrolyte leakage. Red spinach and lettuce were most sensitive to MWNTs, followed by rice and cucumber. Very little or no toxic effects were observed for chili, lady's finger, and soybean.

  19. Development of micro engine oil condition sensor using multi-wall carbon nanotube films

    NASA Astrophysics Data System (ADS)

    Na, Dae Seok; Jung-Ho Pak, James; Kyeong Kim, Jai

    2007-03-01

    A new interdigit-type micro oil condition sensor was designed and fabricated for monitoring the deterioration of lubricating and insulating oils. The designed sensor operates based on the change of the dielectric constant and electrical conductivity. In order to improve sensor performance, an oil condition sensor was fabricated using MEMS technology and multi-wall carbon nanotube film. The experiment was performed with automobile engine oils with the same brand and quality so as to ensure measurement reliability. Capacitance changes were measured according to increasing mileage and the sensors' performance was improved. These results show that the proposed sensor could measure the degree of oil deterioration with a high sensitivity and it is applicable to other lubricating systems as well as insulating systems.

  20. Limited transport of functionalized multi-walled carbon nanotubes in two natural soils.

    PubMed

    Kasel, Daniela; Bradford, Scott A; Simůnek, Jiří; Pütz, Thomas; Vereecken, Harry; Klumpp, Erwin

    2013-09-01

    Column experiments were conducted in undisturbed and in repacked soil columns at water contents close to saturation (85-96%) to investigate the transport and retention of functionalized (14)C-labeled multi-walled carbon nanotubes (MWCNT) in two natural soils. Additionally, a field lysimeter experiment was performed to provide long-term information at a larger scale. In all experiments, no breakthrough of MWCNTs was detectable and more than 85% of the applied radioactivity was recovered in the soil profiles. The retention profiles exhibited a hyper-exponential shape with greater retention near the column or lysimeter inlet and were successfully simulated using a numerical model that accounted for depth-dependent retention. In conclusion, results indicated that the soils acted as a strong sink for MWCNTs. Little transport of MWCNTs is therefore likely to occur in the vadose zone, and this implies limited potential for groundwater contamination in the investigated soils.

  1. MHDA-Functionalized Multiwall Carbon Nanotubes for detecting non-aromatic VOCs

    PubMed Central

    Thamri, Atef; Baccar, Hamdi; Struzzi, Claudia; Bittencourt, Carla; Abdelghani, Adnane; Llobet, Eduard

    2016-01-01

    The chemical modification of multiwalled carbon nanotubes (MWCNTs) with a long chain mercapto acid is reported as a way to improve sensitivity and response time of gas sensors for detecting alcohols, acetone and toxic gases such as DMMP. We have developed sensors employing MWCNTs decorated with gold nanoparticles and modified with a 16-mercaptohexadecanoic acid (MHDA) monolayer. Morphological and compositional analysis by Transmission Electron Microscopy (TEM), Fourier Transform Infra-red Spectroscopy (FTIR) and X-ray photoelectron spectroscopy were performed to characterize the gold nanoparticles and to check the bonding of the thiol monolayer. The detection of aromatic and non-aromatic volatiles and DMMP vapors by MWCNT/Au and MWCNT/Au/MHDA shows that the presence of the self-assembled layer increases sensitivity and selectivity towards non-aromatics. Furthermore, it ameliorates response dynamics, and significantly reduces nitrogen dioxide and moisture cross-sensitivity. PMID:27721503

  2. MHDA-Functionalized Multiwall Carbon Nanotubes for detecting non-aromatic VOCs

    NASA Astrophysics Data System (ADS)

    Thamri, Atef; Baccar, Hamdi; Struzzi, Claudia; Bittencourt, Carla; Abdelghani, Adnane; Llobet, Eduard

    2016-10-01

    The chemical modification of multiwalled carbon nanotubes (MWCNTs) with a long chain mercapto acid is reported as a way to improve sensitivity and response time of gas sensors for detecting alcohols, acetone and toxic gases such as DMMP. We have developed sensors employing MWCNTs decorated with gold nanoparticles and modified with a 16-mercaptohexadecanoic acid (MHDA) monolayer. Morphological and compositional analysis by Transmission Electron Microscopy (TEM), Fourier Transform Infra-red Spectroscopy (FTIR) and X-ray photoelectron spectroscopy were performed to characterize the gold nanoparticles and to check the bonding of the thiol monolayer. The detection of aromatic and non-aromatic volatiles and DMMP vapors by MWCNT/Au and MWCNT/Au/MHDA shows that the presence of the self-assembled layer increases sensitivity and selectivity towards non-aromatics. Furthermore, it ameliorates response dynamics, and significantly reduces nitrogen dioxide and moisture cross-sensitivity.

  3. Improved field emission from indium decorated multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Sreekanth, M.; Ghosh, S.; Biswas, P.; Kumar, S.; Srivastava, P.

    2016-10-01

    Multi-walled carbon nanotube (MWCNT) films were grown using thermal chemical vapor deposition (T-CVD) process and were decorated with indium metal particles by thermal evaporation technique. The In metal particles are found to get oxidized. The In decorated films show 250% enhancement in the FE current density, lower turn-on and threshold fields, and better temporal stability as compared to their undecorated counterpart. This improvement in field emission properties is primarily attributed to increased density of states near the Fermi level. The presence of O 2p states along with a small contribution from In 5s states results in the enhancement of density of states in the vicinity of the Fermi level.

  4. Externally limited defect generation in multiwalled carbon nanotubes upon thermal annealing, and possible mechanism.

    PubMed

    Bhalerao, G M; Sinha, A K; Srivastava, A K; Sathe, V; Amarendra, G

    2016-09-01

    Structural defects in multiwalled carbon nanotubes (MWCNTs) are found to increase upon moderate thermal annealing below 1400 K in an argon atmosphere. The defects are estimated using the ID/IG ratio in Raman spectroscopy of MWCNTs and confirmed by a direct observation using high-resolution transmission electron microscopy (HRTEM). HRTEM shows that the structural defects are created due to large damage to the outer walls of the nanotubes, while inner walls do not sustain any damage. The generation of defects on MWCNTs is attibuted to mechanical abrasion between the MWCNTs in contact, augmented by the momentum transfer from the flow of hot gas. A possible mechanism is proposed and experimentally validated by means of modulating the chemical environment of annealing from argon to hydrogen. PMID:27456152

  5. Properties and electrochemical characteristics of boron-doped multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Tsierkezos, Nikos G.; Ritter, Uwe; Nugraha Thaha, Yudi; Krischok, Stefan; Himmerlich, Marcel; Downing, Clive

    2015-10-01

    Boron-doped multi-walled carbon nanotubes were synthesized upon decomposition of ethyl alcohol and boric acid via chemical vapor deposition. The boron-doped nanotubes were treated with hydrochloric acid and were characterized by means of scanning electron and transmission electron microscopy in conjunction with energy-dispersive X-ray spectrometry and X-ray photoelectron spectroscopy. The electrochemistry of ferrocyanide/ferricyanide on boron-doped nanotubes was studied in temperature range of 283.15-303.15 K. The findings exhibit an improvement of films' current response and kinetics of electron transfer with the rise in temperature. The kinetics for electron transfer enhances and the redox process occurs slightly more spontaneously upon acid treatment.

  6. Thermoelectric properties of porous multi-walled carbon nanotube/polyaniline core/shell nanocomposites.

    PubMed

    Zhang, Kun; Davis, Marauo; Qiu, Jingjing; Hope-Weeks, Louisa; Wang, Shiren

    2012-09-28

    Porous polyaniline (PANI)-coated multi-walled carbon nanotube (MWNT) core/shell nanohybrids were fabricated through in situ polymerization and subsequently assembled into macroscopic composites. N(2) adsorption/desorption analysis indicated that the volume of nanopores increased significantly, which could make a significant contribution to phonon scattering. Thermal annealing was also carried out to improve the Seebeck coefficient of the as-produced nanocomposites. The optimal sample showed electrical conductivity of 14.1 S cm(-1), a Seebeck coefficient of 79.8 μV K(-1) and thermal conductivity of 0.27 W mK(-1), resulting in a highest figure of merit (ZT) of 0.01 at a very low loading of MWNTs (<1 wt%). These results will provide a potential direction to enhance thermoelectric performance of organic materials and also facilitate the application of organic materials in thermal energy harvesting or cooling.

  7. Optical properties of fluorescent zigzag graphene quantum dots derived from multi-walled carbon nanotubes

    SciTech Connect

    Chen, Wei; Li, Fushan Wu, Chaoxing; Guo, Tailiang

    2014-02-10

    Graphene quantum dots (GQDs), which are edge-bound nanometer-size graphene pieces, have fascinating electronic and optical properties due to their quantum confinement and edge effect. In this paper, GQDs were synthesized by using acid treatment and chemical exfoliation of multi-walled carbon nanotubes (MWCNTs). The structure of the GQDs was investigated by transmission electron microscope. The GQDs have a uniform size distribution, zigzag edge structure and two-dimensional morphology. The results indicated that the GQDs have bright blue emission upon UV excitation. The highly fluorescent GQDs exhibited high water solubility and good stability. It is shown that the acid treatment of MWCNTs leads to the formation of the functional group in zigzag sites, which results in the pH-dependent fluorescence of the GQDs.

  8. Vertically aligned multiwalled carbon nanotubes for pressure, tactile and vibration sensing.

    PubMed

    Yilmazoglu, O; Popp, A; Pavlidis, D; Schneider, J J; Garth, D; Schüttler, F; Battenberg, G

    2012-03-01

    We report a simple method for the micro-nano integration of flexible, vertically aligned multiwalled CNT arrays sandwiched between a top and bottom carbon layer via a porous alumina (Al(2)O(3)) template approach. The electromechanical properties of the flexible CNT arrays have been investigated under mechanical stress conditions. First experiments show highly sensitive piezoresistive sensors with a resistance decrease of up to ∼35% and a spatial resolution of <1 mm. The results indicate that these CNT structures can be utilized for tactile sensing components. They also confirm the feasibility of accessing and utilizing nanoscopic CNT bundles via lithographic processing. The method involves room-temperature processing steps and standard microfabrication techniques.

  9. Radial Corrugations of Multi-Walled Carbon Nanotubes Driven by Inter-Wall Nonbonding Interactions

    PubMed Central

    2011-01-01

    We perform large-scale quasi-continuum simulations to determine the stable cross-sectional configurations of free-standing multi-walled carbon nanotubes (MWCNTs). We show that at an inter-wall spacing larger than the equilibrium distance set by the inter-wall van der Waals (vdW) interactions, the initial circular cross-sections of the MWCNTs are transformed into symmetric polygonal shapes or asymmetric water-drop-like shapes. Our simulations also show that removing several innermost walls causes even more drastic cross-sectional polygonization of the MWCNTs. The predicted cross-sectional configurations agree with prior experimental observations. We attribute the radial corrugations to the compressive stresses induced by the excessive inter-wall vdW energy release of the MWCNTs. The stable cross-sectional configurations provide fundamental guidance to the design of single MWCNT-based devices and shed lights on the mechanical control of electrical properties. PMID:27502675

  10. Thermal conductivity studies of metal dispersed multiwalled carbon nanotubes in water and ethylene glycol based nanofluids

    SciTech Connect

    Jha, Neetu; Ramaprabhu, S.

    2009-10-15

    High thermal conducting metal nanoparticles have been dispersed on the multiwalled carbon nanotubes (MWNTs) outer surface. Structural and morphological characterizations of metal dispersed MWNTs have been carried out using x-ray diffraction analysis, high resolution transmission electron microscopy, energy dispersive x-ray analysis, and Fourier transform infrared spectroscopy. Nanofluids have been synthesized using metal-MWNTs in de-ionized water (DI water) and ethylene glycol (EG) base fluids. It has been observed that nanofluids maintain the same sequence of thermal conductivity as that of metal nanoparticles Ag-MWNTs>Au-MWNTs>Pd-MWNTs. A maximum enhancement of 37.3% and 11.3% in thermal conductivity has been obtained in Ag-MWNTs nanofluid with DI water and EG as base fluids, respectively, at a volume fraction of 0.03%. Temperature dependence study also shows enhancement of thermal conductivity with temperature.

  11. Simple quantification of surface carboxylic acids on chemically oxidized multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Gong, Hyejin; Kim, Seong-Taek; Lee, Jong Doo; Yim, Sanggyu

    2013-02-01

    The surface of multi-walled carbon nanotube (MWCNT) was chemically oxidized using nitric acid and sulfuric-nitric acid mixtures. Thermogravimetric analysis, transmission electron microscopy and infrared spectroscopy revealed that the use of acid mixtures led to higher degree of oxidation. More quantitative identification of surface carboxylic acids was carried out using X-ray photoelectron spectroscopy (XPS) and acid-base titration. However, these techniques are costly and require very long analysis times to promptly respond to the extent of the reaction. We propose a much simpler method using pH measurements and pre-determined pKa value in order to estimate the concentration of carboxylic acids on the oxidized MWCNT surfaces. The results from this technique were consistent with those obtained from XPS and titration, and it is expected that this simple quantification method can provide a cheap and fast way to monitor and control the oxidation reaction of MWCNT.

  12. Ultraviolet pulsed laser irradiation of multi-walled carbon nanotubes in nitrogen atmosphere

    SciTech Connect

    Pérez del Pino, Ángel Cabana, Laura; Tobias, Gerard; György, Enikö; Ballesteros, Belén

    2014-03-07

    Laser irradiation of randomly oriented multi-walled carbon nanotube (MWCNT) networks has been carried out using a pulsed Nd:YAG UV laser in nitrogen gas environment. The evolution of the MWCNT morphology and structure as a function of laser fluence and number of accumulated laser pulses has been studied using electron microscopies and Raman spectroscopy. The observed changes are discussed and correlated with thermal simulations. The obtained results indicate that laser irradiation induces very fast, high temperature thermal cycles in MWCNTs which produce the formation of different nanocarbon forms, such as nanodiamonds. Premelting processes have been observed in localized sites by irradiation at low number of laser pulses and low fluence values. The accumulation of laser pulses and the increase in the fluence cause the full melting and amorphization of MWCNTs. The observed structural changes differ from that of conventional high temperature annealing treatments of MWCNTs.

  13. Incorporation of Multiwalled Carbon Nanotubes into High Temperature Resin Using Dry Mixing Techniques

    NASA Technical Reports Server (NTRS)

    Ghose, Sayata; Watson, Kent A.; Delozier, Donavon M.; Working, Dennis C.; Siochi, Emilie J.; Connell, John W.

    2006-01-01

    As part of an ongoing effort to develop multifunctional advanced composites, blends of PETI330 and multiwalled carbon nanotubes (MWNTs) were prepared and characterized. Dry mixing techniques were employed and the maximum loading level of the MWNT chosen was based primarily on its effect on melt viscosity. The PETI330/ MWNT mixtures were prepared at concentrations ranging from 3 to 25 wt %. The resulting powders were characterized for homogeneity, thermal and rheological properties and extrudability as continuous fibers. Based on the characterization results, samples containing 10, 15 and 20 wt % MWNTs were chosen for more comprehensive evaluation. Samples were also prepared using in situ polymerization and solution mixing techniques and their properties were compared with the ball-mill prepared samples. The preparation and characterization of PETI330/ MWNT nanocomposites are discussed herein.

  14. Removal of polychlorinated biphenyls from aqueous solutions using beta-cyclodextrin grafted multiwalled carbon nanotubes.

    PubMed

    Shao, Dadong; Sheng, Guodong; Chen, Changlun; Wang, Xiangke; Nagatsu, Masaaki

    2010-04-01

    Cyclodextrins have excellent ability in the preconcentration of organic pollutants from aqueous solutions by forming inclusion complexes. Multiwalled carbon nanotubes (MWCNTs) possess high adsorption capacity in the removal of organic pollutants through the formation of conjugated complexes. In this paper, beta-cyclodextrin (beta-CD) was grafted on the surfaces of MWCNTs by using plasma technique. The beta-CD grafted MWCNTs (MWCNT-g-CD) were characterized by using Raman spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, thermo gravimetric analysis-differential thermal analysis, and scanning electron microscopy in detail. The prepared MWCNT-g-CD were used to remove polychlorinated biphenyls (PCBs) from aqueous solutions under ambient conditions. The results suggest that MWCNT-g-CD have much higher adsorption capacity than MWCNTs in the removal of PCBs from aqueous solutions. MWCNT-g-CD are suitable materials in the preconcentration and immobilization of PCBs from large volumes of aqueous solutions in environmental pollution cleanup.

  15. Growth of Aligned Multiwall Carbon Nanotubes and the Effect of Adsorbates on the Field Emission Properties

    NASA Astrophysics Data System (ADS)

    Milne, W. I.; Teo, K. B. K.; Lansley, S. B.; Chhowalla, M.; Amaratunga, G. A. J.; Semet, V.; Binh, Vu Thien; Pirio, G.; Legagneux, P.

    2003-10-01

    In attempt to decipher the field emission characteristics of multiwall carbon nanotubes (MWCNTs), we have developed a fabrication method based on plasma enhanced chemical vapour deposition (PECVD) to provide utmost control of the nanotube structure such as their alignment, individual position, diameter, length and morphology. We investigated the field emission properties of these nanotubes to elucidate the effect of adsorbates on the nanotubes. Our results show that although the adsorbates cause an apparent lowering of the required turn on voltage/field of the nanotubes, the adsorbates undesirably cause a saturation of the current, large temporal fluctuations in the current, and also a deviation of the emission characteristics from Fowler-Nordheim like emission. The adsorbates are easily removed by extracting an emission current of 1 uA per nanotube or using a high applied electric field (˜25V/um).

  16. Ultraviolet pulsed laser irradiation of multi-walled carbon nanotubes in nitrogen atmosphere

    NASA Astrophysics Data System (ADS)

    Pérez del Pino, Ángel; György, Enikö; Cabana, Laura; Ballesteros, Belén; Tobias, Gerard

    2014-03-01

    Laser irradiation of randomly oriented multi-walled carbon nanotube (MWCNT) networks has been carried out using a pulsed Nd:YAG UV laser in nitrogen gas environment. The evolution of the MWCNT morphology and structure as a function of laser fluence and number of accumulated laser pulses has been studied using electron microscopies and Raman spectroscopy. The observed changes are discussed and correlated with thermal simulations. The obtained results indicate that laser irradiation induces very fast, high temperature thermal cycles in MWCNTs which produce the formation of different nanocarbon forms, such as nanodiamonds. Premelting processes have been observed in localized sites by irradiation at low number of laser pulses and low fluence values. The accumulation of laser pulses and the increase in the fluence cause the full melting and amorphization of MWCNTs. The observed structural changes differ from that of conventional high temperature annealing treatments of MWCNTs.

  17. Preparation, purification and characterization of high purity multi-wall carbon nanotube.

    PubMed

    Morsy, Mohamed; Helal, Magdy; El-Okr, Mohamed; Ibrahim, Medhat

    2014-11-11

    Chemical vapor deposition (CVD) was optimized in order to prepare multi-wall carbon nanotubes (MWCNTs). Preparation of MWCNTs was achieved by the help of ferrocene as a catalyst with continuous flow of xylene. Morphology and structure of as grown and purified MWCNTs were characterized by Scanning Electron Microscope (SEM) and High-Resolution Transmission Electron Microscope (HRTEM). Energy Dispersive X-ray (EDX) spectra for the as grown MWCNTs confirm that the deposits are carbonaceous materials. XRD pattern of purified sample indicates that the Fe peaks at 44.6 and 50.9 have been decreased. This confirms that purification process is effectively reducing Fe component. Further qualitative information on the purification process are indicated and confirmed by the thermal analysis measurements. Finally, FTIR studies have been performed for the identification of the functional group attached on the surface of the MWCNTs. Collecting these results revealed that the optimized CVD is suitable for the production of MWCNTs. PMID:24892539

  18. Effect of gases on the temperature dependence of the electric conductivity of CVD multiwalled carbon nanotubes

    SciTech Connect

    Buryakov, T. I. Romanenko, A. I.; Anikeeva, O. B.; Kuznetsov, V. L.; Usol'tseva, A. N.; Tkachev, E. N.

    2007-07-15

    The influence of various gaseous media on the temperature dependence of the electric conductivity {sigma} of multiwalled carbon nanotubes (MWNTs) synthesized using the method of catalytical chemical vapor deposition (CVD) has been studied. The {sigma}(T) curves were measured in a temperature range from 4.2 to 300 K in helium and its mixtures with air, methane, oxygen, and hydrogen. The introduction of various gaseous components into a helium atmosphere leads to a significant decrease in the conductivity of MWNTs in the interval between the temperatures of condensation and melting of the corresponding gas. Upon a heating-cooling cycle, the conductivity restores on the initial level. It is concluded that a decrease in {sigma} is caused by the adsorption of gases on the surface of nanotubes.

  19. Size- and shape-dependent pleural translocation, deposition, fibrogenesis, and mesothelial proliferation by multiwalled carbon nanotubes.

    PubMed

    Xu, Jiegou; Alexander, David B; Futakuchi, Mitsuru; Numano, Takamasa; Fukamachi, Katsumi; Suzui, Masumi; Omori, Toyonori; Kanno, Jun; Hirose, Akihiko; Tsuda, Hiroyuki

    2014-07-01

    Multiwalled carbon nanotubes (MWCNT) have a fibrous structure similar to asbestos, raising concern that MWCNT exposure may lead to asbestos-like diseases. Previously we showed that MWCNT translocated from the lung alveoli into the pleural cavity and caused mesothelial proliferation and fibrosis in the visceral pleura. Multiwalled carbon nanotubes were not found in the parietal pleura, the initial site of development of asbestos-caused pleural diseases in humans, probably due to the short exposure period of the study. In the present study, we extended the exposure period to 24 weeks to determine whether the size and shape of MWCNT impact on deposition and lesion development in the pleura and lung. Two different MWCNTs were chosen for this study: a larger sized needle-like MWCNT (MWCNT-L; l = 8 μm, d = 150 nm), and a smaller sized MWCNT (MWCNT-S; l = 3 μm, d = 15 nm), which forms cotton candy-like aggregates. Both MWCNT-L and MWCNT-S suspensions were administered to the rat lung once every 2 weeks for 24 weeks by transtracheal intrapulmonary spraying. It was found that MWCNT-L, but not MWCNT-S, translocated into the pleural cavity, deposited in the parietal pleura, and induced fibrosis and patchy parietal mesothelial proliferation lesions. In addition, MWCNT-L induced stronger inflammatory reactions including increased inflammatory cell number and cytokine/chemokine levels in the pleural cavity lavage than MWCNT-S. In contrast, MWCNT-S induced stronger inflammation and higher 8-hydroxydeoxyguanosine level in the lung tissue than MWCNT-L. These results suggest that MWCNT-L has higher risk of causing asbestos-like pleural lesions relevant to mesothelioma development.

  20. Enhanced-Adhesion Multi-Walled Carbon Nanotubes on Titanium Substrates for Stray Light Control

    NASA Technical Reports Server (NTRS)

    Hagopian, John; Getty, Stephanie; Quijada, Manuel

    2012-01-01

    Carbon nanotubes previously grown on silicon have extremely low reflectance, making them a good candidate for stray light suppression. Silicon, however, is not a good structural material for stray light components such as tubes, stops, and baffles. Titanium is a good structural material and can tolerate the 700 C nanotube growth process. The ability to grow carbon nanotubes on a titanium substrate that are ten times blacker than the current NASA state-of-the-art paints in the visible to near infrared spectra has been achieved. This innovation will allow significant improvement of stray light performance in scientific instruments or any other optical system. This innovation is a refinement of the utilization of multiwalled carbon nano tubes for stray light suppression in spaceflight instruments. The innovation is a process to make the surface darker and improve the adhesion to the substrate, improving robustness for spaceflight use. Bright objects such as clouds or ice scatter light off of instrument structures and components and make it difficult to see dim objects in Earth observations. A darker material to suppress this stray light has multiple benefits to these observations, including enabling scientific observations not currently possible, increasing observational efficiencies in high-contrast scenes, and simplifying instruments and lowering their cost by utilizing fewer stray light components and achieving equivalent performance. The prior art was to use commercially available black paint, which resulted in approximately 4% of the light being reflected (hemispherical reflectance or total integrated scatter, or TIS). Use of multiwalled carbon nanotubes on titanium components such as baffles, entrance aperture, tubes, and stops, can decrease this scattered light by a factor of ten per bounce over the 200-nm to 2,500-nm wavelength range. This can improve system stray light performance by orders of magnitude. The purpose of the innovation is to provide an enhanced

  1. Field Emission Properties of Multi-walled Carbon Nanotubes Grown on Silicon Nanoporous Pillar Array

    NASA Astrophysics Data System (ADS)

    Jiang, Wei-fen; Li, Long-yu; Xiao, Shun-hua; Yang, Xiao-hui; Jia, Min; Li, Xin-jian

    2007-12-01

    Multi-walled carbon nanotubes (CNTs) were grown on a silicon nanoporous pillar array (Si-NPA) by thermal chemical vapor deposition. Surface morphologies and microstructure of the resultant were studied by a field emission scanning electron microscope, Raman spectrum, transmission electron microscope, and high-resolution transmission electron microscopy. The composition of samples was determined by energy dispersive X-ray spectroscopy (EDS). The results showed that a great deal of CNTs, with diameter in the range of 20-70 nm, incorporated with Si-NPA and a large scale nest array of CNTs/Si-NPA (NACNT/Si-NPA) was formed. EDS analysis showed that the composition of carbon nanotubes was carbon. Field emission measurements showed that a current density of 5 mA/cm2 was obtained at an electric field of 4.26 V/μm, with a turn-on field of 1.3 V/μm. The enhancement factor calculated according to the Fowler-Nordheim theory was ~11,000. This excellent field emission performance is attributed to the unique structure and morphology of NACNT/Si-NPA, especially the formation of a nest-shaped carbon nanotube array. A schematic drawing that illustrates the experimental configuration is given. These results indicate that NACNT/Si-NPA might be an ideal candidate cathode for potential applications in flat panel displays.

  2. Realizing comparable oxidative and cytotoxic potential of single- and multiwalled carbon nanotubes through annealing.

    PubMed

    Pasquini, Leanne M; Sekol, Ryan C; Taylor, André D; Pfefferle, Lisa D; Zimmerman, Julie B

    2013-08-01

    The potential applications as well as the environmental and human health implications of carbon nanomaterials are well represented in the literature. There has been a recent focus on how specific physicochemical properties influence carbon nanotube (CNT) function as well as cytotoxicity. The ultimate goal is a better understanding of the causal relationship between fundamental physiochemical properties and cytotoxic mechanism in order to both advance functional design and to minimize unintended consequences of CNTs. This study provides characterization data on a series of multiwalled carbon nanotubes (MWNTs) that underwent acid treatment followed by annealing at increasing temperatures, ranging from 400 to 900 °C. These results show that MWNTs can be imparted with the same toxicity as single-walled carbon nanotubes (SWNTs) by acid treatment and annealing. Further, we were able to correlate this toxicity to the chemical reactivity of the MWNT suggesting that it is a chemical rather than physical hazard. This informs the design of MWNT to be less hazardous or enables their implementation in antimicrobial applications. Given the reduced cost and ready dispersivity of MWNTs as compared to SWNTs, there is a significant opportunity to pursue the use of MWNTs in novel applications previously thought reserved for SWNTs.

  3. Multi-walled carbon nanotubes/polymer composites in absence and presence of acrylic elastomer (ACM).

    PubMed

    Kumar, S; Rath, T; Mahaling, R N; Mukherjee, M; Khatua, B B; Das, C K

    2009-05-01

    Polyetherimide/Multiwall carbon nanotube (MWNTs) nanocomposites containing as-received and modified (COOH-MWNT) carbon nanotubes were prepared through melt process in extruder and then compression molded. Thermal properties of the composites were characterized by thermo-gravimetric analysis (TGA). Field emission scanning electron microscopy (FESEM) images showed that the MWNTs were well dispersed and formed an intimate contact with the polymer matrix without any agglomeration. However the incorporation of modified carbon nanotubes formed fascinating, highly crosslinked, and compact network structure throughout the polymer matrix. This showed the increased adhesion of PEI with modified MWNTs. Scanning electron microscopy (SEM) also showed high degree of dispersion of modified MWNTs along with broken ends. Dynamic mechanical analysis (DMA) results showed a marginal increase in storage modulus (E') and glass transition temperature (T(g)) with the addition of MWNTs. Increase in tensile strength and impact strength of composites confirmed the use the MWNTs as possible reinforcement agent. Both thermal and electrical conductivity of composites increased, but effect is more pronounced on modification due to formation of network of carbon nanotubes. Addition of acrylic elastomer to developed PEI/MWNTs (modified) nanocomposites resulted in the further increase in thermal and electrical properties due to the formation of additional bond between MWNTs and acrylic elastomers at the interface. All the results presented are well corroborated by SEM and FESEM studies. PMID:19452959

  4. Heat dissipation for the Intel Core i5 processor using multiwalled carbon-nanotube-based ethylene glycol

    NASA Astrophysics Data System (ADS)

    Thang, Bui Hung; Van Trinh, Pham; Quang, Le Dinh; Huong, Nguyen Thi; Khoi, Phan Hong; Minh, Phan Ngoc

    2014-08-01

    Carbon nanotubes (CNTs) are some of the most valuable materials with high thermal conductivity. The thermal conductivity of individual multiwalled carbon nanotubes (MWCNTs) grown by using chemical vapor deposition is 600 ± 100 Wm-1K-1 compared with the thermal conductivity 419 Wm-1K-1 of Ag. Carbon-nanotube-based liquids — a new class of nanomaterials, have shown many interesting properties and distinctive features offering potential in heat dissipation applications for electronic devices, such as computer microprocessor, high power LED, etc. In this work, a multiwalled carbon-nanotube-based liquid was made of well-dispersed hydroxyl-functional multiwalled carbon nanotubes (MWCNT-OH) in ethylene glycol (EG)/distilled water (DW) solutions by using Tween-80 surfactant and an ultrasonication method. The concentration of MWCNT-OH in EG/DW solutions ranged from 0.1 to 1.2 gram/liter. The dispersion of the MWCNT-OH-based EG/DW solutions was evaluated by using a Zeta-Sizer analyzer. The MWCNT-OH-based EG/DW solutions were used as coolants in the liquid cooling system for the Intel Core i5 processor. The thermal dissipation efficiency and the thermal response of the system were evaluated by directly measuring the temperature of the micro-processor using the Core Temp software and the temperature sensors built inside the micro-processor. The results confirmed the advantages of CNTs in thermal dissipation systems for computer processors and other high-power electronic devices.

  5. Scratch and wear resistance of polyamide 6 reinforced with multiwall carbon nanotubes.

    PubMed

    Giraldo, Luis F; Brostow, Witold; Devaux, Eric; López, Betty L; Pérez, León D

    2008-06-01

    While carbon nanotubes have been used for a variety of purposes, it was not known whether they can improve tribological properties of polymers. Polyamide 6 (PA6) has been reinforced with 0.2, 0.5 and 1.0 wt% of multiwall carbon nanotubes (MWCNTs) by melt mixing process and characterized by scanning electron microscopy (SEM), transmission electron microscopy, thermogravimetric analysis (TGA), scratching, sliding wear and tensile testing. TGA results for the air atmosphere show that MWCNTs shift the onset of thermal degradation to higher temperatures. Sliding wear tests show that the penetration depth decreases as the concentration of carbon nanotubes increases. However, the viscoelastic healing is hampered by the MWCNTs presence and the residual depths increase at the same time. Narrower scratch groove widths are seen in SEM for composites with MWCNTs, and scratch hardness increases. Tensile tests show an increase of 27% in the Young modulus value upon addition of 1.0% of MWCNTs. The stress at yield is also higher for the nanocomposites.

  6. Solid-contact pH-selective electrode using multi-walled carbon nanotubes.

    PubMed

    Crespo, Gastón A; Gugsa, Derese; Macho, Santiago; Rius, F Xavier

    2009-12-01

    Multi-walled carbon nanotubes (MWCNT) are shown to be efficient transducers of the ionic-to-electronic current. This enables the development of a new solid-contact pH-selective electrode that is based on the deposition of a 35-microm thick layer of MWCNT between the acrylic ion-selective membrane and the glassy carbon rod used as the electrical conductor. The ion-selective membrane was prepared by incorporating tridodecylamine as the ionophore, potassium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate as the lipophilic additive in a polymerized methylmethacrylate and an n-butyl acrylate matrix. The potentiometric response shows Nernstian behaviour and a linear dynamic range between 2.89 and 9.90 pH values. The response time for this electrode was less than 10 s throughout the whole working range. The electrode shows a high selectivity towards interfering ions. Electrochemical impedance spectroscopy and chronopotentiometry techniques were used to characterise the electrochemical behaviour and the stability of the carbon-nanotube-based ion-selective electrodes. PMID:19760402

  7. Graphene wrapped multiwalled carbon nanotubes dispersed nanofluids for heat transfer applications

    NASA Astrophysics Data System (ADS)

    Jyothirmayee Aravind, S. S.; Ramaprabhu, S.

    2012-12-01

    A two step method is employed for the preparation of graphene wrapped multiwalled carbon nanotubes (MWNT) dispersed nanofluids. Graphene wrapped MWNT composite is prepared by simple chemical vapor deposition technique and further purified prior to the synthesis of nanofluids. The functionalization of MWNT with the poly electrolyte, graphene drives out the need for surfactants or long term harsh chemical treatments as in the case of pristine carbon materials based nanofluids. The enhancement in thermal transport properties of surfactant free graphene wrapped MWNT composite in de-ionized (DI) water and ethylene glycol (EG) base fluids than that of pristine carbon nanomaterial based nanofluids indicates the potential usage of the hybrid composite based nanofluids in heat transfer applications. An enhancement in thermal conductivity of 11.3% and 13.7% has been attained with 0.04% volume fraction of hybrid composite based DI water and EG nanofluids at 25 °C. The nanocomposite possesses extreme stability in a variety of aqueous solvents without any surfactant. Electrical conductivity of the nanofluids analyzed as a function of volume fraction of nanoparticles and temperature shows a positive effect. Further, the analysis of forced convective heat transfer coefficients of the nanofluids flowing through a stain less steel tube shows significant enhancement in heat transfer, attributed to good aspect ratio of graphene wrapped MWNT and synergistic effect of high thermally conducting graphene and MWNT.

  8. Long-Term Effects of Multiwalled Carbon Nanotubes and Graphene on Microbial Communities in Dry Soil.

    PubMed

    Ge, Yuan; Priester, John H; Mortimer, Monika; Chang, Chong Hyun; Ji, Zhaoxia; Schimel, Joshua P; Holden, Patricia A

    2016-04-01

    Little is known about the long-term effects of engineered carbonaceous nanomaterials (ECNMs) on soil microbial communities, especially when compared to possible effects of natural or industrial carbonaceous materials. To address these issues, we exposed dry grassland soil for 1 year to 1 mg g(-1) of either natural nanostructured material (biochar), industrial carbon black, three types of multiwalled carbon nanotubes (MWCNTs), or graphene. Soil microbial biomass was assessed by substrate induced respiration and by extractable DNA. Bacterial and fungal communities were examined by terminal restriction fragment length polymorphism (T-RFLP). Microbial activity was assessed by soil basal respiration. At day 0, there was no treatment effect on soil DNA or T-RFLP profiles, indicating negligible interference between the amended materials and the methods for DNA extraction, quantification, and community analysis. After a 1-year exposure, compared to the no amendment control, some treatments reduced soil DNA (e.g., biochar, all three MWCNT types, and graphene; P < 0.05) and altered bacterial communities (e.g., biochar, carbon black, narrow MWCNTs, and graphene); however, there were no significant differences across the amended treatments. These findings suggest that ECNMs may moderately affect dry soil microbial communities but that the effects are similar to those from natural and industrial carbonaceous materials, even after 1-year exposure. PMID:26962674

  9. Evaluation of a pyroelectric detector with a carbon multiwalled nanotube black coating in the infrared

    NASA Astrophysics Data System (ADS)

    Theocharous, E.; Deshpande, R.; Dillon, A. C.; Lehman, J.

    2006-02-01

    The performance of a pyroelectric detector with a carbon multiwalled nanotube coating was evaluated in the 0.9-14 µm wavelength range. The relative spectral responsivity of this detector was shown to be flat over most of the wavelength range examined, and the spectral flatness was shown to be comparable to the best infrared black coatings currently available. This finding is promising because black coatings with spectrally flat absorbance profiles are usually associated with the highest absorbance values. The performance of the detector (in terms of noise equivalent power and specific detectivity) was limited by the very thick (250 µm thick) LiNbO3 pyroelectric crystal onto which the coating was deposited. The responsivity of this detector was shown to be linear in the 0.06-2.8 mW radiant power range, and its spatial uniformity was comparable to that of other pyroelectric detectors that use different types of black coating. The carbon nanotube coatings were reported to be much more durable than other infrared black coatings, such as metal blacks, that are commonly used to coat thermal detectors in the infrared. This, in combination with their excellent spectral flatness, suggests that carbon nanotube coatings appear extremely promising for thermal detection applications in the infrared.

  10. Multiwall carbon nanotubes increase the microbial community in crude oil contaminated fresh water sediments.

    PubMed

    Abbasian, Firouz; Lockington, Robin; Palanisami, Thavamani; Megharaj, Mallavarapu; Naidu, Ravi

    2016-01-01

    Since crude oil contamination is one of the biggest environmental concerns, its removal from contaminated sites is of interest for both researchers and industries. In situ bioremediation is a promising technique for decreasing or even eliminating crude oil and hydrocarbon contamination. However, since these compounds are potentially toxic for many microorganisms, high loads of contamination can inhibit the microbial community and therefore reduce the removal rate. Therefore, any strategy with the ability to increase the microbial population in such circumstances can be of promise in improving the remediation process. In this study, multiwall carbon nanotubes were employed to support microbial growth in sediments contaminated with crude oil. Following spiking of fresh water sediments with different concentrations of crude oil alone and in a mixture with carbon nanotubes for 30days, the microbial profiles in these sediments were obtained using FLX-pyrosequencing. Next, the ratios of each member of the microbial population in these sediments were compared with those values in the untreated control sediment. This study showed that combination of crude oil and carbon nanotubes can increase the diversity of the total microbial population. Furthermore, these treatments could increase the ratios of several microorganisms that are known to be effective in the degradation of hydrocarbons.

  11. Field emission performance of multiwalled carbon nanotubes for a low-power spacecraft neutraliser

    NASA Astrophysics Data System (ADS)

    Aplin, K. L.; Kent, B. J.; Song, W.; Castelli, C.

    2009-05-01

    Field electron emission from aligned multiwalled carbon nanotubes has been assessed to determine if the performance, defined by power consumption, lifetime and emission current, is suitable for use in spacecraft charge neutralisation for field emission electric propulsion (FEEP). Carbon nanotubes grown by chemical vapour deposition (CVD) were mounted on a dual in line chip with a macroscopic (nickel mesh) extractor electrode mounted ˜1 mm above the tubes. The nanotubes' field emission characteristics (emission currents, electron losses and operating voltage) were measured at ˜10 -4 Pa. An endurance test of one sample, running at a software-controlled constant emission current lasted >1400 h, approaching the longest known FEEP thruster lifetime. The emission corresponds to a current density of ˜10 mA/cm 2 at a voltage of 150 V. These results, implementing mature extractor-electrode geometry, indicate that carbon nanotubes have considerable potential for development as robust, low-power, long-lived electron emitters for use in space.

  12. Using multi-walled carbon nanotubes (MWNTs) for oilfield produced water treatment with environmentally acceptable endpoints.

    PubMed

    Zaib, Qammer; Aina, Oluwajinmi Daniel; Ahmad, Farrukh

    2014-08-01

    In this study, multi-walled carbon nanotubes (MWNTs) were employed to remove benzene, toluene, ethylbenzene, and xylenes (BTEX) from low and high salinity water pre-equilibrated with crude oil. The treatment endpoint of crude oil-contaminated water is often controlled by BTEX compounds owing to their higher aqueous solubility and human-health toxicity compared to other hydrocarbons. The MWNT sorbent was extensively characterized and the depletion of the organic sorbate from the produced water was monitored by gas chromatography-mass spectrometry (GC-MS) and total organic carbon (TOC) analyses. The equilibrium sorptive removal of BTEX followed the order: ethylbenzene/o-xylene > m-xylene > toluene > benzene in the presence of other competing organics in produced water. Sorption mechanisms were explored through the application of a variety of kinetics and equilibrium models. Pseudo 2(nd) order kinetics and Freundlich equilibrium models were the best at describing BTEX removal from produced water. Hydrophobic interactions between the MWNTs and BTEX, as well as the physical characteristics of the sorbate molecules, were regarded as primary factors responsible for regulating competitive adsorption. Salinity played a critical role in limiting sorptive removal, with BTEX and total organic carbon (TOC) removal falling by 27% and 25%, respectively, upon the introduction of saline conditions. Results suggest that MWNTs are effective in removing risk-driving BTEX compounds from low-salinity oilfield produced water.

  13. Wrapping and dispersion of multiwalled carbon nanotubes improves electrical conductivity of protein-nanotube composite biomaterials.

    PubMed

    Voge, Christopher M; Johns, Jeremy; Raghavan, Mekhala; Morris, Michael D; Stegemann, Jan P

    2013-01-01

    Composites of extracellular matrix proteins reinforced with carbon nanotubes have the potential to be used as conductive biopolymers in a variety of biomaterial applications. In this study, the effect of functionalization and polymer wrapping on the dispersion of multiwalled carbon nanotubes (MWCNT) in aqueous media was examined. Carboxylated MWCNT were wrapped in either Pluronic(®) F127 or gelatin. Raman spectroscopy and X-ray photoelectron spectroscopy showed that covalent functionalization of the pristine nanotubes disrupted the carbon lattice and added carboxyl groups. Polymer and gelatin wrapping resulted in increased surface adsorbed oxygen and nitrogen, respectively. Wrapping also markedly increased the stability of MWCNT suspensions in water as measured by settling time and zeta potential, with Pluronic(®)-wrapped nanotubes showing the greatest effect. Treated MWCNT were used to make 3D collagen-fibrin-MWCNT composite materials. Carboxylated MWCNT resulted in a decrease in construct impedance by an order of magnitude, and wrapping with Pluronic(®) resulted in a further order of magnitude decrease. Functionalization and wrapping also were associated with maintenance of fibroblast function within protein-MWCNT materials. These data show that increased dispersion of nanotubes in protein-MWCNT composites leads to higher conductivity and improved cytocompatibility. Understanding how nanotubes interact with biological systems is important in enabling the development of new biomedical technologies.

  14. Electrochemical sensor for chloramphenicol based on novel multiwalled carbon nanotubes@molecularly imprinted polymer.

    PubMed

    Yang, Guangming; Zhao, Faqiong

    2015-02-15

    Herein, we present a novel electrochemical sensor for the determination of chloramphenicol (CAP), which is based on multiwalled carbon nanotubes@molecularly imprinted polymer (MWCNTs@MIP), mesoporous carbon (CKM-3) and three-dimensional porous graphene (P-r-GO). Firstly, 3-hexadecyl-1-vinylimidazolium chloride (C16VimCl) was synthetized by using 1-vinylimidazole and 1-chlorohexadecane as precursors. Then, C16VImCl was used to improve the dispersion of MWCNT and as monomer to prepare MIP on MWCNT surface to obtain MWCNTs@MIP. After that, the obtained MWCNTs@MIP was coated on the CKM-3 and P-r-GO modified glassy carbon electrode to construct an electrochemical sensor for the determination of CAP. The parameters concerning this assay strategy were carefully considered. Under the optimal conditions, the electrochemical sensor offered an excellent response for CAP. The linear response ranges were 5.0 × 10(-9)-5 × 10(-7)mol L(-1) and 5.0 × 10(-7)-4.0 × 10(-6), respectively, and the detection limit was 1.0 × 10(-10)mol L(-1). The electrochemical sensor was applied to determine CAP in real samples with satisfactory results.

  15. Nanoscale Analysis of Interwall Interaction in a Multiwalled Carbon Nanotube by Tip-Enhanced Raman Spectroscopy

    NASA Astrophysics Data System (ADS)

    Chaunchaiyakul, Songpol; Yano, Takeshi; Khoklang, Kamonchanok; Krukowski, Pawel; Akai-Kasaya, Megumi; Saito, Akira; Kuwahara, Yuji

    Raman spectroscopy is a useful tool for the study of carbon materials, but its spatial resolution is limited by the optical diffraction limit. Recently, we constructed a scanning tunneling microscope-based tip-enhanced Raman spectroscopy (STM-TERS) system in ultrahigh vacuum, which overcomes the optical diffraction limit, and enables the investigation of single-molecular Raman spectra simultaneously with topographic imaging. We have investigated position-sensitive Raman spectra along the tube axis of an isolated multiwalled carbon nanotube, which is a result of the different number of nanotube walls at each location. We found that the intensity ratio between the 2D to the G band increases with the number of walls. This indicates that the quantum interference between Raman scattering pathways affects each Raman mode differently. The interaction between nanotube walls induces splitting of the π and π* bands which increases the number of the 2D band scattering pathways owing to double resonance, eventually increasing the probability of scattering for the 2D band relative to the G band. These results provide a deeper understanding of the single-molecule interaction of carbon materials in the nanoscale.

  16. Plasma-activated multi-walled carbon nanotube-polystyrene composite substrates for biosensing

    NASA Astrophysics Data System (ADS)

    Fernández-Sánchez, César; Pellicer, Eva; Orozco, Jahir; Jiménez-Jorquera, Cecilia; Lechuga, Laura M.; Mendoza, Ernest

    2009-08-01

    Carbon nanotube-polymer composites have shown to be suitable materials for the fabrication of electrochemical transducers. The exposed surface of these materials is commonly passivated by a very thin layer of the polymer component that buries the conductive carbon particles. Working with multi-walled carbon nanotube-polystyrene (MWCNT-PS) composite structures, it was previously described how a simple low power oxygen plasma process produced an effective etching of the composite surface, thereby exposing the conductive surface of CNTs. This work shows how this plasma process not only gave rise to a suitable composite conductive surface for electrochemical sensing but simultaneously exposed and created a high density of oxygen-containing functional groups at both the CNT and the PS components, without affecting the material's mechanical stability. These chemical groups could be effectively modified for the stable immobilization of biological receptors. A detailed chemical characterization of the plasma-activated composite surface was possible using x-ray photoelectron spectroscopy. The material reactivity towards the tethering of a protein was studied and protein-protein interactions were then evaluated on the modified composite transducers by scanning electron microscopy. Finally, an amperometric immunosensor approach for the detection of rabbit Immunoglobulin G target analyte was described and a minimum concentration of 3 ng ml-1 was easily measured.

  17. Long-Term Effects of Multiwalled Carbon Nanotubes and Graphene on Microbial Communities in Dry Soil.

    PubMed

    Ge, Yuan; Priester, John H; Mortimer, Monika; Chang, Chong Hyun; Ji, Zhaoxia; Schimel, Joshua P; Holden, Patricia A

    2016-04-01

    Little is known about the long-term effects of engineered carbonaceous nanomaterials (ECNMs) on soil microbial communities, especially when compared to possible effects of natural or industrial carbonaceous materials. To address these issues, we exposed dry grassland soil for 1 year to 1 mg g(-1) of either natural nanostructured material (biochar), industrial carbon black, three types of multiwalled carbon nanotubes (MWCNTs), or graphene. Soil microbial biomass was assessed by substrate induced respiration and by extractable DNA. Bacterial and fungal communities were examined by terminal restriction fragment length polymorphism (T-RFLP). Microbial activity was assessed by soil basal respiration. At day 0, there was no treatment effect on soil DNA or T-RFLP profiles, indicating negligible interference between the amended materials and the methods for DNA extraction, quantification, and community analysis. After a 1-year exposure, compared to the no amendment control, some treatments reduced soil DNA (e.g., biochar, all three MWCNT types, and graphene; P < 0.05) and altered bacterial communities (e.g., biochar, carbon black, narrow MWCNTs, and graphene); however, there were no significant differences across the amended treatments. These findings suggest that ECNMs may moderately affect dry soil microbial communities but that the effects are similar to those from natural and industrial carbonaceous materials, even after 1-year exposure.

  18. Multiwalled carbon nanotubes at environmentally relevant concentrations affect the composition of benthic communities.

    PubMed

    Velzeboer, I; Peeters, E T H M; Koelmans, A A

    2013-07-01

    To date, chronic effect studies with manufactured nanomaterials under field conditions are scarce. Here, we report in situ effects of 0, 0.002, 0.02, 0.2, and 2 g/kg multiwalled carbon nanotubes (MWCNTs) in sediment on the benthic community composition after 15 months of exposure. Effects observed after 15 months were compared to those observed after 3 months and to community effects of another carbonaceous material (activated carbon; AC), which was simultaneously tested in a parallel study. Redundancy analysis with variance partitioning revealed a total explained variance of 51.7% of the variation in community composition after 15 months, of which MWCNT dose explained a statistically significant 9.9%. By stepwise excluding the highest MWCNT concentrations in the statistical analyses, MWCNT effects were shown to be statistically significant already at the lowest dose investigated, which can be considered environmentally relevant. We conclude that despite prolonged aging, encapsulation, and burial, MWCNTs can affect the structure of natural benthic communities in the field. This effect was similar to that of AC observed in a parallel experiment, which however was applied at a 50 times higher maximum dose. This suggests that the benthic community was more sensitive to MWCNTs than to the bulk carbon material AC.

  19. Single step synthesis of graphene nanoribbons by catalyst particle size dependent cutting of multiwalled carbon nanotubes.

    PubMed

    Parashar, Upendra Kumar; Bhandari, Suraj; Srivastava, Rajesh Kumar; Jariwala, Deep; Srivastava, Anchal

    2011-09-01

    Graphene nanoribbons are emerging as an interesting material for the study of low dimensional physics and for the applications in future electronics due to its finite energy band gap. However, its applicability for large scale nanoelectronics may not be effectively realized unless graphene nanoribbons could be produced using a simple, viable, cost-effective and scalable technique. Here, we report the one step facile synthesis of few layered graphene nanoribbons (GNRs) by catalytically unzipping multi-walled carbon nanotubes (MWCNTs) based on the solubility of carbon atoms in transition metals. The process is free from aggressive oxidants (such as KMnO(4), KClO(4), H(2)SO(4), HNO(3), etc.) and utilizes the in situ grown nickel nanoparticles for nanotube unzipping. This is an additional advantage over previously used techniques to synthesize GNRs. To observe the effect of catalyst particle size and reaction temperature on cutting length of the nanotubes, a simulation study has been done based on solubility of carbon atoms in metal nanoparticles. PMID:21842103

  20. Using multi-walled carbon nanotubes (MWNTs) for oilfield produced water treatment with environmentally acceptable endpoints.

    PubMed

    Zaib, Qammer; Aina, Oluwajinmi Daniel; Ahmad, Farrukh

    2014-08-01

    In this study, multi-walled carbon nanotubes (MWNTs) were employed to remove benzene, toluene, ethylbenzene, and xylenes (BTEX) from low and high salinity water pre-equilibrated with crude oil. The treatment endpoint of crude oil-contaminated water is often controlled by BTEX compounds owing to their higher aqueous solubility and human-health toxicity compared to other hydrocarbons. The MWNT sorbent was extensively characterized and the depletion of the organic sorbate from the produced water was monitored by gas chromatography-mass spectrometry (GC-MS) and total organic carbon (TOC) analyses. The equilibrium sorptive removal of BTEX followed the order: ethylbenzene/o-xylene > m-xylene > toluene > benzene in the presence of other competing organics in produced water. Sorption mechanisms were explored through the application of a variety of kinetics and equilibrium models. Pseudo 2(nd) order kinetics and Freundlich equilibrium models were the best at describing BTEX removal from produced water. Hydrophobic interactions between the MWNTs and BTEX, as well as the physical characteristics of the sorbate molecules, were regarded as primary factors responsible for regulating competitive adsorption. Salinity played a critical role in limiting sorptive removal, with BTEX and total organic carbon (TOC) removal falling by 27% and 25%, respectively, upon the introduction of saline conditions. Results suggest that MWNTs are effective in removing risk-driving BTEX compounds from low-salinity oilfield produced water. PMID:24975808

  1. Pre-treatment of multi-walled carbon nanotubes for polyetherimide mixed matrix hollow fiber membranes.

    PubMed

    Goh, P S; Ng, B C; Ismail, A F; Aziz, M; Hayashi, Y

    2012-11-15

    Mixed matrix hollow fibers composed of multi-walled carbon nanotubes (MWCNTs) and polyetherimide (PEI) were fabricated. Pre-treatment of MWCNTs was carried out prior to the incorporation into the polymer matrix using a simple and feasible two stages approach that involved dry air oxidation and surfactant dispersion. The characterizations of the surface treated MWCNTs using TEM and Raman spectroscopy have evidenced the effectiveness of dry air oxidation in eliminating undesired amorphous carbon and metal catalyst while surfactant dispersion using Triton X100 has suppressed the agglomeration of MWCNTs. The resultant mixed matrix hollow fibers were applied for O(2)/N(2) pure gas separation. Interestingly, it was found that removal of disordered amorphous carbons and metal particles has allowed the hollow structures to be more accessible for the fast and smooth transport of gas molecules, hence resulted in noticeable improvement in the gas separation properties. The composite hollow fibers embedded with the surface modified MWCNTs showed increase in permeability as much as 60% while maintaining the selectivity of the O(2)/N(2) gas pair. This study highlights the necessity to establish an appropriate pre-treatment approach for MWCNTs in order to fully utilize the beneficial transport properties of this material in mixed matrix polymer nanocomposite for gas separation.

  2. Morphology optimization of CCVD-synthesized multiwall carbon nanotubes, using statistical design of experiments

    NASA Astrophysics Data System (ADS)

    Nourbakhsh, Amirhasan; Ganjipour, Bahram; Zahedifar, Mostafa; Arzi, Ezatollah

    2007-03-01

    The possibility of optimization of morphological features of multiwall carbon nanotubes (MWCNTs) using the statistical design of experiments (DoE) is investigated. In this study, MWCNTs were synthesized using a catalytic chemical vapour deposition (CCVD) method in a horizontal reactor using acetylene as the carbon source. The effects of six synthesis parameters (synthesis time, synthesis temperature, catalyst mass, reduction time, acetylene flow rate and hydrogen flow rate) on the average diameter and mean rectilinear length (MRL) of carbon nanotubes were examined using fractional-factorial design (FFD) coupled with response surface methodology (RSM). Using a 2III6-3 FFD, the main effects of reaction temperature, hydrogen flow rate and chemical reduction time were concluded to be the key factors influencing the diameter and MRL of MWCNTs; then Box-Behnken design (BBD) was exploited to create a response surface from the main factors. The total number of required runs is 26: 8 runs are for FFD parameter screening, 17 runs are for the response surface obtained by the BBD, and the final run is used to confirm the predicted results.

  3. Transition from single to multi-walled carbon nanotubes grown by inductively coupled plasma enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Bissett, Mark A.; Barlow, Anders J.; Shapter, Joe G.; Quinton, Jamie S.

    2011-08-01

    In this work a simple and up-scalable technique for creating arrays of high purity carbon nanotubes via plasma enhanced chemical vapor deposition is demonstrated. Inductively coupled plasma enhanced chemical vapor deposition was used with methane and argon mixtures to grow arrays in a repeatable and controllable way. Changing the growth conditions such as temperature and growth time led to a transition between single and multi-walled carbon nanotubes and was investigated. This transition from single to multi-walled carbon nanotubes is attributed to a decrease in catalytic activity with time due to amorphous carbon deposition combined with a higher susceptibility of single-walled nanotubes to plasma etching. Patterning of these arrays was achieved by physical masking during the iron catalyst deposition process. The low growth pressure of 100 mTorr and lack of reducing gas such as ammonia or hydrogen or alumina supporting layer further show this to be a simple yet versatile procedure. These arrays were then characterized using scanning electron microscopy, Raman spectroscopy and x-ray photoelectron spectroscopy. It was also observed that at high temperature (550 °C) single-walled nanotube growth was preferential while lower temperatures (450 °C) produced mainly multi-walled arrays.

  4. Genotoxicity of multi-walled carbon nanotubes at occupationally relevant doses.

    PubMed

    Siegrist, Katelyn J; Reynolds, Steven H; Kashon, Michael L; Lowry, David T; Dong, Chenbo; Hubbs, Ann F; Young, Shih-Houng; Salisbury, Jeffrey L; Porter, Dale W; Benkovic, Stanley A; McCawley, Michael; Keane, Michael J; Mastovich, John T; Bunker, Kristin L; Cena, Lorenzo G; Sparrow, Mark C; Sturgeon, Jacqueline L; Dinu, Cerasela Zoica; Sargent, Linda M

    2014-01-01

    Carbon nanotubes are commercially-important products of nanotechnology; however, their low density and small size makes carbon nanotube respiratory exposures likely during their production or processing. We have previously shown mitotic spindle aberrations in cultured primary and immortalized human airway epithelial cells exposed to single-walled carbon nanotubes (SWCNT). In this study, we examined whether multi-walled carbon nanotubes (MWCNT) cause mitotic spindle damage in cultured cells at doses equivalent to 34 years of exposure at the NIOSH Recommended Exposure Limit (REL). MWCNT induced a dose responsive increase in disrupted centrosomes, abnormal mitotic spindles and aneuploid chromosome number 24 hours after exposure to 0.024, 0.24, 2.4 and 24 μg/cm² MWCNT. Monopolar mitotic spindles comprised 95% of disrupted mitoses. Three-dimensional reconstructions of 0.1 μm optical sections showed carbon nanotubes integrated with microtubules, DNA and within the centrosome structure. Cell cycle analysis demonstrated a greater number of cells in S-phase and fewer cells in the G2 phase in MWCNT-treated compared to diluent control, indicating a G1/S block in the cell cycle. The monopolar phenotype of the disrupted mitotic spindles and the G1/S block in the cell cycle is in sharp contrast to the multi-polar spindle and G2 block in the cell cycle previously observed following exposure to SWCNT. One month following exposure to MWCNT there was a dramatic increase in both size and number of colonies compared to diluent control cultures, indicating a potential to pass the genetic damage to daughter cells. Our results demonstrate significant disruption of the mitotic spindle by MWCNT at occupationally relevant exposure levels.

  5. In situ growth rate measurements during plasma-enhanced chemical vapour deposition of vertically aligned multiwall carbon nanotube films

    NASA Astrophysics Data System (ADS)

    Jönsson, M.; Nerushev, O. A.; Campbell, E. E. B.

    2007-08-01

    In situ laser reflectivity measurements are used to monitor the growth of multiwalled carbon nanotube (MWCNT) films grown by DC plasma-enhanced chemical vapour deposition (PECVD) from an iron catalyst film deposited on a silicon wafer. In contrast to thermal CVD growth, there is no initial increase in the growth rate; instead, the initial growth rate is high (as much as 10 µm min-1) and then drops off rapidly to reach a steady level (2 µm min-1) for times beyond 1 min. We show that a limiting factor for growing thick films of multiwalled nanotubes (MWNTs) using PECVD can be the formation of an amorphous carbon layer at the top of the growing nanotubes. In situ reflectivity measurements provide a convenient technique for detecting the onset of the growth of this layer.

  6. Growth of Multi-Walled Carbon Nanotubes by Injection CVD Using Cyclopentadienyliron Dicarbonyl Dimer and Cyclooctatetraene Iron Tricarbonyl

    NASA Technical Reports Server (NTRS)

    Harris, Jerry D.; Raffaelle, Ryne P.; Gennett, Thomas; Landi, Brian J.; Hepp, Aloysius F.

    2004-01-01

    Preferential oriented multiwalled carbon nanotubes were prepared by the injection chemical vapor deposition (CVD) method using either cyclopentadienyliron dicarbonyl dimer or cycloctatetraene iron tricarbonyl as the iron catalyst source. The catalyst precursors were dissolved in toluene as the carrier solvent for the injections. The concentration of the catalyst was found to influence both the growth of the nanotubes as well as the amount of iron in the deposited material. As deposited the multiwalled carbon nanotubes contained as little as 2.8% iron by weight. The material was deposited onto tantalum foil and fused silica substrates. The nanotubes were characterized by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy and thermogravimetric analysis. This synthetic route provides a simple and scalable method to deposit MWNTs with a low defect density, low metal content and preferred orientation.

  7. Molecular Dynamics Simulation of a Multi-Walled Carbon Nanotube Based Gear

    NASA Technical Reports Server (NTRS)

    Han, Jie; Globus, Al; Srivastava, Deepak; Chancellor, Marisa K. (Technical Monitor)

    1997-01-01

    We used molecular dynamics to investigate the properties of a multi-walled carbon nanotube based gear. Previous work computationally suggested that molecular gears fashioned from (14,0) single-walled carbon nanotubes operate well at 50-100 gigahertz. The gears were formed from nanotubes with teeth added via a benzyne reaction known to occur with C60. A modified, parallelized version of Brenner's potential was used to model interatomic forces within each molecule. A Leonard-Jones 6-12 potential was used for forces between molecules. The gear in this study was based on the smallest multi-walled nanotube supported by some experimental evidence. Each gear was a (52,0) nanotube surrounding a (37,10) nanotube with approximate 20.4 and 16,8 A radii respectively. These sizes were chosen to be consistent with inter-tube spacing observed by and were slightly larger than graphite inter-layer spacings. The benzyne teeth were attached via 2+4 cycloaddition to exterior of the (52,0) tube. 2+4 bonds were used rather than the 2+2 bonds observed by Hoke since 2+4 bonds are preferred by naphthalene and quantum calculations by Jaffe suggest that 2+4 bonds are preferred on carbon nanotubes of sufficient diameter. One gear was 'powered' by forcing the atoms near the end of the outside buckytube to rotate to simulate a motor. A second gear was allowed to rotate by keeping the atoms near the end of its outside buckytube on a cylinder. The ends of both gears were constrained to stay in an approximately constant position relative to each other, simulating a casing, to insure that the gear teeth meshed. The stiff meshing aromatic gear teeth transferred angular momentum from the powered gear to the driven gear. The simulation was performed in a vacuum and with a software thermostat. Preliminary results suggest that the powered gear had trouble turning the driven gear without slip. The larger radius and greater mass of these gears relative to the (14,0) gears previously studied requires a

  8. Kinetic characteristics of the synthesis of multiwall carbon nanotubes by aerosol pyrolysis of a ferrocene solution in benzene

    NASA Astrophysics Data System (ADS)

    Cherkasov, N. B.; Savilov, S. B.; Pryakhin, A. N.; Ivanov, A. S.; Lunin, V. V.

    2012-03-01

    Approximating the experimental data on the mass distribution of multiwall carbon nanotubes (MCNT) along a reactor, a three-step kinetic model of their synthesis in the aerosol pyrolysis of a ferrocene solution in benzene is proposed. The values of effective rate constants upon the introduction of a catalyst in situ for the reactions that are the basis for synthesizing MCNT via the pyrolysis of hydrocarbons are obtained for the first time.

  9. Electrochemical Impedance Studies on Single and Multi-Walled Carbon Nanotubes--Polymer Nanocomposites for Biosensors Development.

    PubMed

    Tertiş, Mihaela; Florea, Anca; Feier, Bogdan; Marian, Iuliu Ovidiu; Silaghi-Dumitrescu, Luminţa; Cristea, Alexandru; Săndulescu, Robert; Cristea, Cecilia

    2015-05-01

    Advances in nanoscience have allowed scientists to incorporate new nanomaterials in biosensing platforms. Carbon nanotubes are nanomaterials that facilitate the charge transfer between the bioelement and the transducer. Electrochemical impedance spectroscopy is a useful technique for the modified surface characterization. In the present approach electrochemical impedance spectroscopy was used to characterize the electrodes modified with different types of carbon nanotubes (single and multi-wall) according to their morphology and electrochemical behavior. By using Nyquist and Bode diagrams it was possible to assign the appropriate circuit considering all possible contributors. The charge transfer resistances as well as the time constants were calculated for all five types of investigated carbon nanotubes.

  10. Efficient and facile one pot carboxylation of multiwalled carbon nanotubes by using oxidation with ozone under mild conditions

    NASA Astrophysics Data System (ADS)

    Naeimi, Hossein; Mohajeri, Ali; Moradi, Leila; Rashidi, Ali Morad

    2009-11-01

    In this study, oxidation of carbon nanotubes with ozone in the presence of hydrogen peroxide was investigated. The reaction was performed under clean and mild conditions and oxidized products with high concentration of oxygenated groups were yielded. The reaction products were characterized with attenuated total reflectance (ATR), Raman spectroscopy, scanning electron microscopy (SEM), X-ray diffractometry (XRD), back titration, X-ray photoelectron spectroscopy (XPS) and the dispersion behavior of the oxidized multiwalled carbon nanotubes (MWCNTs) was also studied. The results confirmed the presence of high concentrations of oxidative groups on the carbon nanotubes (CNTs) treated by the method of the present work.

  11. Grafting of polystyrene on nitrogen-doped multi-walled carbon nanotubes.

    PubMed

    Dehonor, Mariamne; Masenelli-Varlot, Karine; González-Montiel, Alfonso; Gauthier, Catherine; Cavaillé, Jean-Yves; Terrones, Mauricio

    2007-10-01

    Polymer grafting of polystyrene (PS) on nitrogen-doped multiwall carbon nanotubes (CNx) was successfully obtained by a "grafting from" technique. The production method involves the immobilization of initiators, using wet chemistry, onto the nanotube surface, followed by an in situ surface-initiated polymerization. The polymer-grafting carbon nanotubes synthesis includes the free radical functionalization of CNx and the "controlled/living" Nitroxide Mediated Radical Polymerization (NMRP). The obtained products were studied using several microscopic techniques as scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and electron energy loss spectroscopy (EELS). The characterization also includes thermogravimetric analysis (TGA), Raman spectroscopy, infrared spectroscopy, and electron spin resonance (ESR), among others. The analyzed samples were also compared with solutions fabricated by physical blending of the polymer and CNx nanotubes. These results indicate that the nanotube radical functionalization, the chemical grafting, and the polymerization reaction were obtained over CNx when NMRP method was successfully used, giving rise to a uniform PS layer of several nanometers grafted on the outer surface of the CNx nanotubes. Several properties of the PS-grafted CNx nanotubes were also studied. It is shown that the production method leads to a narrower distribution of the external diameters. Moreover, their solubilization in organic solvents is greatly improved. Finally, the dispersion of PS-grafted CNx into a PS matrix is studied to determine the differences in filler dispersion and interfacial adhesion strength, in comparison with nanocomposites elaborated with as-produced CNx.

  12. Quantitative evaluation of multi-walled carbon nanotube uptake in wheat and rapeseed.

    PubMed

    Larue, Camille; Pinault, Mathieu; Czarny, Bertrand; Georgin, Dominique; Jaillard, Danielle; Bendiab, Nedjma; Mayne-L'Hermite, Martine; Taran, Frédéric; Dive, Vincent; Carrière, Marie

    2012-08-15

    Environmental contamination with carbon nanotubes would lead to plant exposure and particularly exposure of agricultural crops. The only quantitative exposure data available to date which can be used for risk assessment comes from computer modeling. The aim of this study was to provide quantitative data relative to multi-walled carbon nanotube (MWCNT) uptake and distribution in agricultural crops, and to correlate accumulation data with impact on plant development and physiology. Roots of wheat and rapeseed were exposed in hydroponics to uniformly (14)C-radiolabeled MWCNTs. Radioimaging, transmission electron microscopy and raman spectroscopy were used to identify CNT distribution. Radioactivity counting made it possible absolute quantification of CNT accumulation in plant leaves. Impact of CNTs on seed germination, root elongation, plant biomass, evapotranspiration, chlorophyll, thiobarbituric acid reactive species and H(2)O(2) contents was evaluated. We demonstrate that less than 0.005‰ of the applied MWCNT dose is taken up by plant roots and translocated to the leaves. This accumulation does not impact plant development and physiology. In addition, it does not induce any modifications in photosynthetic activity nor cause oxidative stress in plant leaves. Our results suggest that if environmental contamination occurs and MWCNTs are in the same physico-chemical state than the ones used in the present article, MWCNT transfer to the food chain via food crops would be very low.

  13. Improved Photoelectrochemical Cell Performance of Tin Oxide with Functionalized Multiwalled Carbon Nanotubes-Cadmium Selenide Sensitizer.

    PubMed

    Bhande, Sambhaji S; Ambade, Rohan B; Shinde, Dipak V; Ambade, Swapnil B; Patil, Supriya A; Naushad, Mu; Mane, Rajaram S; Alothman, Z A; Lee, Soo-Hyoung; Han, Sung-Hwan

    2015-11-18

    Here we report functionalized multiwalled carbon nanotubes (f-MWCNTs)-CdSe nanocrystals (NCs) as photosensitizer in photoelectrochemical cells, where f-MWCNTs were uniformly coated with CdSe NCs onto SnO2 upright standing nanosheets by using a simple electrodeposition method. The resultant blended photoanodes demonstrate extraordinary electrochemical properties including higher Stern-Volmer constant, higher absorbance, and positive quenching, etc., caused by more accessibility of CdSe NCs compared with pristine SnO2-CdSe photoanode. Atomic and weight percent changes of carbon with f-MWCNTs blending concentrations were confirmed from the energy dispersive X-ray analysis. The morphology images show a uniform coverage of CdSe NCs over f-MWCNTs forming a core-shell type structure as a blend. Compared to pristine CdSe, photoanode with f-MWCNTs demonstrated a 257% increase in overall power conversion efficiency. Obtained results were corroborated by the electrochemical impedance analysis. Higher scattering, more accessibility, and hierarchical structure of SnO2-f-MWCNTs-blend-CdSe NCs photoanode is responsible for higher (a) electron mobility (6.89 × 10(-4) to 10.89 × 10(-4) cm(2) V(-1) S(1-)), (b) diffusion length (27 × 10(-6)),

  14. Aggregation kinetics of multiwalled carbon nanotubes in aquatic systems: measurements and environmental implications.

    PubMed

    Saleh, Navid B; Pfefferle, Lisa D; Elimelech, Menachem

    2008-11-01

    The initial aggregation kinetics of multiwalled carbon nanotubes (MWNTs) were examined through time-resolved dynamic light scattering. Aggregation of MWNTs was evaluated by varying solution pH and the concentration of monovalent (NaCl) and divalent (CaCl2 and MgCl2) salts. Suwannee River humic acid (SRHA) was used to study the effect of background natural organic matter on MWNT aggregation kinetics, Increasing salt concentration and addition of divalent calcium and magnesium ions induced MWNT aggregation by suppressing electrostatic repulsion, similar to observations with aquatic colloidal particles. The critical coagulation concentration (CCC) values for MWNTs were estimated as 25 mM NaCI, 2.6 mM CaCl2, and 1.5 mM MgCl2. An increase in solution pH from acidic (pH 3) to basic (pH 11) conditions resulted in a substantial (over 2 orders of magnitude) decrease in MWNT aggregation kinetics, suggesting the presence of ionizable functional groups on the MWNT carbon scaffold. The presence of humic acid in solution markedly enhanced the colloidal stability of MWNTs, reducing the aggregation rate by nearly 2 orders of magnitude. The enhanced MWNT stability in the presence of humic acid is attributable to steric repulsion imparted by adsorbed humic acid macromolecules. Our results suggest that MWNTs are relatively stable at solution pH and electrolyte conditions typical of aquatic environments.

  15. Enhanced dispersion of multiwall carbon nanotubes in natural rubber latex nanocomposites by surfactants bearing phenyl groups.

    PubMed

    Mohamed, Azmi; Anas, Argo Khoirul; Bakar, Suriani Abu; Ardyani, Tretya; Zin, Wan Manshol W; Ibrahim, Sofian; Sagisaka, Masanobu; Brown, Paul; Eastoe, Julian

    2015-10-01

    Here is presented a systematic study of the dispersibility of multiwall carbon nanotubes (MWCNTs) in natural rubber latex (NR-latex) assisted by a series of single-, double-, and triple-sulfosuccinate anionic surfactants containing phenyl ring moieties. Optical polarising microscopy, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and Raman spectroscopy have been performed to obtain the dispersion-level profiles of the MWCNTs in the nanocomposites. Interestingly, a triple-chain, phenyl-containing surfactant, namely sodium 1,5-dioxo-1,5-bis(3-phenylpropoxy)-3-((3-phenylpropoxy)carbonyl) pentane-2-sulfonate (TCPh), has a greater capacity the stabilisation of MWCNTs than a commercially available single-chain sodium dodecylbenzenesulfonate (SDBS) surfactant. TCPh provides significant enhancements in the electrical conductivity of nanocomposites, up to ∼10(-2) S cm(-1), as measured by a four-point probe instrument. These results have allowed compilation of a road map for the design of surfactant architectures capable of providing the homogeneous dispersion of MWCNTs required for the next generation of polymer-carbon-nanotube materials, specifically those used in aerospace technology.

  16. Third Sound Generation in Superfluid 4He Films Adsorbed on Multiwall Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Iaia, Vito; Menachekanian, Emin; Williams, Gary

    2014-03-01

    A technique is developed for generating third sound in superfluid 4He films coating the surface of multiwall carbon nanotubes. Third sound is a thickness and temperature wave of the helium film, and in our case we detect the temperature oscillations with a carbon resistance bolometer. The nanotubes are packed in an annular resonator that is vibrated with a mechanical shaker assembly consisting of a permanent magnet mounted on springs, and surrounded by a superconducting coil. The coil is driven with an oscillating current, vibrating the cell at that frequency. Sweeping the drive frequency over the range 100-200 Hz excites the resonant third sound mode of the cell, seen as a high-Q signal in the FFT analysis of the bolometer signal. A problem with our original cell was that the mechanical drive would also shake the dilution refrigerator cooling the cell to low temperatures, and increasing the drive would start to heat up the refrigerator and the cell, which were rigidly coupled together. A new configuration now suspends the cell as a pendulum on a string, with thermal contact made by copper wires. Piezo sensor measurements show this reduces the vibration reaching the refrigerator by two orders of magnitude, which should allow measurements at lower temperatures.

  17. Dependence of the cytotoxicity of multi-walled carbon nanotubes on the culture medium

    NASA Astrophysics Data System (ADS)

    Zhu, Ying; Ran, Tiecheng; Li, Yuguo; Guo, Jinxue; Li, Wenxin

    2006-09-01

    This study examined the influence of multi-walled carbon nanotubes (MWNTs) on the growth of the unicellular protozoan Tetrahymena pyriformis. Contrary to the findings from most other investigations, our experiment indicated that MWNTs stimulated growth of the cells cultured in proteose peptone yeast extract medium (PPY). Atomic force microscopy images and thermogravimetric analysis showed the spontaneous formation of peptone-MWNT conjugates in the medium by noncovalent binding. Uptake of large amounts of the conjugates by Tetrahymena pyriformis was responsible for growth stimulation, evidenced by images with fluorescently labelled peptone. After the PPY medium was replaced by a filtrated pond water medium (FPW), however, inhibition of the growth of cells exposed to MWNTs occurred. Measurements of the level of malondialdehyde and superoxide dismutase activity demonstrated further that MWNTs might be either toxic or nontoxic, depending on the medium used to cultivate Tetrahymena pyriformis. The biological effects of the interaction of MWNTs with some composites in culture media would be helpful for understanding the mechanisms of the toxicity of carbon nanotubes to living systems.

  18. Individual and competitive adsorption of phenol and nickel onto multiwalled carbon nanotubes

    PubMed Central

    Abdel-Ghani, Nour T.; El-Chaghaby, Ghadir A.; Helal, Farag S.

    2014-01-01

    Individual and competitive adsorption studies were carried out to investigate the removal of phenol and nickel ions by adsorption onto multiwalled carbon nanotubes (MWCNTs). The carbon nanotubes were characterized by different techniques such as X-ray diffraction, scanning electron microscopy, thermal analysis and Fourier transformation infrared spectroscopy. The different experimental conditions affecting the adsorption process were investigated. Kinetics and equilibrium models were tested for fitting the adsorption experimental data. The characterization experimental results proved that the studied adsorbent possess different surface functional groups as well as typical morphological features. The batch experiments revealed that 300 min of contact time was enough to achieve equilibrium for the adsorption of both phenol and nickel at an initial adsorbate concentration of 25 mg/l, an adsorbent dosage of 5 g/l, and a solution pH of 7. The adsorption of phenol and nickel by MWCNTs followed the pseudo-second order kinetic model and the intraparticle diffusion model was quite good in describing the adsorption mechanism. The Langmuir equilibrium model fitted well the experimental data indicating the homogeneity of the adsorbent surface sites. The maximum Langmuir adsorption capacities were found to be 32.23 and 6.09 mg/g, for phenol and Ni ions, respectively. The removal efficiency of MWCNTs for nickel ions or phenol in real wastewater samples at the optimum conditions reached up to 60% and 70%, respectively. PMID:26257938

  19. Effects of functionalized and raw multi-walled carbon nanotubes on soil bacterial community composition.

    PubMed

    Kerfahi, Dorsaf; Tripathi, Binu M; Singh, Dharmesh; Kim, Hyoki; Lee, Sujin; Lee, Junghoon; Adams, Jonathan M

    2015-01-01

    Carbon nanotubes (CNTs) are widely used in industry, but their environmental impacts on soil microbial communities are poorly known. In this paper, we compare the effect of both raw and acid treated or functionalized (fCNTs) multi-walled carbon nanotubes (MWCNTs) on soil bacterial communities, applying different concentrations of MWCNTs (0 µg/g, 50 µg/g, 500 µg/g and 5000 µg/g) to a soil microcosm system. Soil DNA was extracted at 0, 2 and 8 weeks and the V3 region of the 16S rRNA gene was PCR-amplified and sequenced using paired-end Illumina bar-coded sequencing. The results show that bacterial diversity was not affected by either type of MWCNT. However, overall soil bacterial community composition, as illustrated by NMDS, was affected only by fMWCNT at high concentrations. This effect, detectable at 2 weeks, remained equally strong by 8 weeks. In the case of fMWCNTs, overall changes in relative abundance of the dominant phyla were also found. The stronger effect of fMWCNTs could be explained by their intrinsically acidic nature, as the soil pH was lower at higher concentrations of fMWCNTs. Overall, this study suggests that fMWCNTs may at least temporarily alter microbial community composition on the timescale of at least weeks to months. It appears, by contrast, that raw MWCNTs do not affect soil microbial community composition.

  20. Kinetics and thermodynamic study of aniline adsorption by multi-walled carbon nanotubes from aqueous solution.

    PubMed

    Al-Johani, Hind; Abdel Salam, Mohamed

    2011-08-15

    Multi-walled carbon nanotubes (MWCNTs) were used in the adsorptive removal of aniline, an organic pollutant, from an aqueous solution. It was found that carbon nanotubes with a higher specific surface area adsorbed and removed more aniline from an aqueous solution. The adsorption was dependent on factors, such as MWCNTs dosage, contact time, aniline concentration, solution pH and temperature. The adsorption study was analyzed kinetically, and the results revealed that the adsorption followed pseudo-second order kinetics with good correlation coefficients. In addition, it was found that the adsorption of aniline occurred in two consecutive steps, including the slow intra-particle diffusion of aniline molecules through the nanotubes. Various thermodynamic parameters, including the Gibbs free energy change (ΔG°), enthalpy change (ΔH°) and entropy change (ΔS°), were calculated. The results indicated that the spontaneity of the adsorption, exothermic nature of the adsorption and the decrease in the randomness reported as ΔG°, ΔH° and ΔS°, respectively, were all negative.

  1. Chronocoulometry of wine on multi-walled carbon nanotube modified electrode: Antioxidant capacity assay.

    PubMed

    Ziyatdinova, Guzel; Kozlova, Ekaterina; Budnikov, Herman

    2016-04-01

    Phenolic antioxidants of wine were electrochemically oxidized on multi-walled carbon nanotubes modified glassy carbon electrode (MWNT/GCE) in phosphate buffer solution. Three oxidation peaks were observed at 0.39, 0.61 and 0.83V for red dry wine and 0.39, 0.80 and 1.18 V for white dry wine, respectively, using differential pulse voltammetry at pH 4.0. The oxidation potentials for individual phenolic antioxidants confirmed the integral nature of the analytical signals for the wines examined. A one-step chronocoulometric method at 0.83 and 1.18 V for red and white wines, respectively, has been developed for the evaluation of wine antioxidant capacity (AOC). The AOC is expressed in gallic acid equivalents per 1L of wine. The AOC of white wine was significantly less than red wine (386 ± 112 vs. 1224 ± 184, p<0.0001), as might be expected. Positive correlations were observed between gallic acid equivalent AOC of wine and total antioxidant capacity, based on coulometric titration with electrogenerated bromine (r=0.8957 at n=5 and r=0.8986 at n=4 for red and white wines, respectively).

  2. Fostering hydroxyapatite bioactivity and mechanical strength by Si-doping and reinforcing with multiwall carbon nanotubes.

    PubMed

    Belmamouni, Younes; Bricha, Meriame; Essassi, El Mokhtar; Ferreira, José M F; El Mabrouk, Khalil

    2014-06-01

    The aim of the present study was to prepare resorbable hydroxyapatite (HA) based bone graft materials reinforced with carbon nanotubes as a way to cope with the inability of pure HA to resorb and its intrinsic brittleness and poor strength that restrict its clinical applications under load-bearing conditions. With this purpose, a Si-doped HA nanopowder (n-Si0.8HA) was prepared by chemical synthesis and used as composite matrix reinforced with different amounts of functionalized multiwall carbon nanotubes (MWCNTs). The effect of the added amounts of MWCNTs on the mechanical properties of nanocomposites and their in vitro biomineralization was assessed by bending strength measurements, immersing tests in simulated body fluid solution (SBF), scanning electron microscopy (SEM), and inductively coupled plasma atomic emission spectroscopy analysis (ICP-AES). The bioactivity and bending strength were enhanced, reaching maximum balanced values for an optimum addition of 3 wt.% f-MWCNTs. These results might contribute to broaden the potential applications of HA-based bone grafts.

  3. Electrospinning fabrication of high strength and toughness polyimide nanofiber membranes containing multiwalled carbon nanotubes.

    PubMed

    Chen, Dan; Liu, Tianxi; Zhou, Xiaoping; Tjiu, Wuiwui Chauhari; Hou, Haoqing

    2009-07-23

    Polyimide (PI) and PI nanocomposite fibers containing different amounts of multiwalled carbon nanotubes (MWNTs) were produced for the first time by electrospinning. The membranes prepared were composed of highly aligned nanofibers and showed significant enhancement in mechanical properties, compared with the membranes prepared by conventional solution-casting method. Surface-functionalized MWNTs were homogeneously dispersed and highly aligned along the fiber axis, whereas most of the pristine MWNTs formed aggregates or bundles and even protruded out of the electrospun nanofibers. The thermal and mechanical properties of polyimide matrix were significantly improved with the incorporation of MWNTs. And the elongation at break of the nanofiber membranes can reach 100% for the nanotube loading level of 3.5 wt %. It was found that electrospinning the in situ prepared MWNT/poly(amic acid) solution can achieve better polymer chain orientation and thus better mechanical properties of the as-prepared membranes. Our study demonstrates a good example for the preparation of high-performance polymer/carbon nanotube nanocomposites by using electrospinning.

  4. Measurements of near-ultimate strength for multiwalled carbon nanotubes and irradiation-induced crosslinking improvements.

    PubMed

    Peng, Bei; Locascio, Mark; Zapol, Peter; Li, Shuyou; Mielke, Steven L; Schatz, George C; Espinosa, Horacio D

    2008-10-01

    The excellent mechanical properties of carbon nanotubes are being exploited in a growing number of applications from ballistic armour to nanoelectronics. However, measurements of these properties have not achieved the values predicted by theory due to a combination of artifacts introduced during sample preparation and inadequate measurements. Here we report multiwalled carbon nanotubes with a mean fracture strength >100 GPa, which exceeds earlier observations by a factor of approximately three. These results are in excellent agreement with quantum-mechanical estimates for nanotubes containing only an occasional vacancy defect, and are approximately 80% of the values expected for defect-free tubes. This performance is made possible by omitting chemical treatments from the sample preparation process, thus avoiding the formation of defects. High-resolution imaging was used to directly determine the number of fractured shells and the chirality of the outer shell. Electron irradiation at 200 keV for 10, 100 and 1,800 s led to improvements in the maximum sustainable loads by factors of 2.4, 7.9 and 11.6 compared with non-irradiated samples of similar diameter. This effect is attributed to crosslinking between the shells. Computer simulations also illustrate the effects of various irradiation-induced crosslinking defects on load sharing between the shells.

  5. Measurements of near-ultimate strength for multiwalled carbon nanotubes and irradiation-induced crosslinking improvements.

    SciTech Connect

    Peng, B.; Locascio, M.; Zapol, P.; Li, S.; Mielke, S. L.; Schatz, G. C.; Espinosa, H. D.; Northwestern Univ.

    2008-01-01

    The excellent mechanical properties of carbon nanotubes are being exploited in a growing number of applications from ballistic armour to nanoelectronics. However, measurements of these properties have not achieved the values predicted by theory due to a combination of artifacts introduced during sample preparation and inadequate measurements. Here we report multiwalled carbon nanotubes with a mean fracture strength >100 GPa, which exceeds earlier observations by a factor of approximately three. These results are in excellent agreement with quantum-mechanical estimates for nanotubes containing only an occasional vacancy defect, and are {approx}80% of the values expected for defect-free tubes. This performance is made possible by omitting chemical treatments from the sample preparation process, thus avoiding the formation of defects. High-resolution imaging was used to directly determine the number of fractured shells and the chirality of the outer shell. Electron irradiation at 200 keV for 10, 100 and 1,800 s led to improvements in the maximum sustainable loads by factors of 2.4, 7.9 and 11.6 compared with non-irradiated samples of similar diameter. This effect is attributed to crosslinking between the shells. Computer simulations also illustrate the effects of various irradiation-induced crosslinking defects on load sharing between the shells.

  6. Wet adhesion of buckypaper produced from oxidized multiwalled carbon nanotubes on soft animal tissue.

    PubMed

    Martinelli, Andrea; Carru, Giovanna A; D'Ilario, Lucio; Caprioli, Fabrizio; Chiaretti, Massimo; Crisante, Fernanda; Francolini, Iolanda; Piozzi, Antonella

    2013-05-22

    Buckypaper (BP) is the general definition of a macroscopic assembly of entangled carbon nanotubes. In this paper, a new property of a BP film produced from oxidized multiwalled carbon nanotubes was investigated. In particular, BP shows to be able to promptly and strongly adhere to animal internal soft and wet tissues, as evaluated by peeling and shear tests. BP adhesion strength is higher than that recorded for a commercial prosthetic fabric (sealed to the tissue by fibrin glue) and comparable with that of other reported optimized nanopatterned surfaces. In order to give an interpretation of the observed behavior, the BP composition, morphology, porosity, water wettability, and mechanical properties were analyzed by AFM, X-ray photoelectron spectroscopy, wicking tests, contact angle, and stress-strain measurements. Although further investigations are needed to assess the biocompatibility and safety of the BP film used in this work, the obtained results pave the way for a possible future use of buckypaper as adhesive tape in abdominal prosthetic surgery. This would allow the substitution of conventional sealants or the reduction in the use of perforating fixation.

  7. Electrical and dielectric properties of foam injection-molded polypropylene/multiwalled carbon nanotube composites

    NASA Astrophysics Data System (ADS)

    Ameli, A.; Nofar, M.; Saniei, M.; Hossieny, N.; Park, C. B.; Pötschke, P.

    2015-05-01

    A combination of high dielectric permittivity (ɛ') and low dielectric loss (tan δ) is required for charge storage applications. In percolative systems such as conductive polymer composites, however, obtaining high ɛ' and low tan δ is very challenging due to the sharp insulation-conduction transition near the threshold region. Due to the particular arrangement of conductive fillers induced by both foaming and injection molding processes, they may address this issue. Therefore, this work evaluates the application of foam injection molding process in fabricating polymer nanocomposites for energy storage. Polypropylene-multiwalled carbon nanotubes (PP-MWCNT) composites were prepared by melt mixing and foamed in an injection molding process. Electrical conductivity (σ), ɛ' and tan δ were then characterized. Also, scanning and transmission electron microscopy (SEM and TEM) was used to investigate the carbon nanotube's arrangement as well as cellular morphology. The results showed that foam injection-molded composites exhibited highly superior dielectric properties to those of solid counterparts. For instance, foamed samples had ɛ'=68.3 and tan δ =0.05 (at 1.25 vol.% MWCNT), as opposed to ɛ'=17.8 and tan δ=0.04 in solid samples (at 2.56 vol.% MWCNT). The results of this work reveal that high performance dielectric nanocomposites can be developed using foam injection molding technologies for charge storage applications.

  8. Electrical and dielectric properties of foam injection-molded polypropylene/multiwalled carbon nanotube composites

    SciTech Connect

    Ameli, A.; Nofar, M.; Saniei, M.; Hossieny, N.; Park, C. B.; Pötschke, P.

    2015-05-22

    A combination of high dielectric permittivity (ε′) and low dielectric loss (tan δ) is required for charge storage applications. In percolative systems such as conductive polymer composites, however, obtaining high ε′ and low tan δ is very challenging due to the sharp insulation-conduction transition near the threshold region. Due to the particular arrangement of conductive fillers induced by both foaming and injection molding processes, they may address this issue. Therefore, this work evaluates the application of foam injection molding process in fabricating polymer nanocomposites for energy storage. Polypropylene-multiwalled carbon nanotubes (PP-MWCNT) composites were prepared by melt mixing and foamed in an injection molding process. Electrical conductivity (σ), ε′ and tan δ were then characterized. Also, scanning and transmission electron microscopy (SEM and TEM) was used to investigate the carbon nanotube’s arrangement as well as cellular morphology. The results showed that foam injection-molded composites exhibited highly superior dielectric properties to those of solid counterparts. For instance, foamed samples had ε′=68.3 and tan δ =0.05 (at 1.25 vol.% MWCNT), as opposed to ε′=17.8 and tan δ=0.04 in solid samples (at 2.56 vol.% MWCNT). The results of this work reveal that high performance dielectric nanocomposites can be developed using foam injection molding technologies for charge storage applications.

  9. Ecotoxicity of multiwalled carbon nanotubes: standardization of the dispersion methods and concentration measurements.

    PubMed

    Cerrillo, Cristina; Barandika, Gotzone; Igartua, Amaya; Areitioaurtena, Olatz; Marcaide, Arrate; Mendoza, Gemma

    2015-08-01

    There are currently a variety of applications for multiwalled carbon nanotubes (MWCNTs), but considerable concerns exist regarding their release into the environment. Their potential accumulation by aquatic organisms could lead to transfer throughout food chains. Considering the divergences in experimental data published on the ecotoxicity of carbon nanotubes, further research is required. The dispersion of MWCNTs in aqueous culturing media of organisms as well as the determination of concentrations are relevant aspects to obtain accurate ecotoxicity results. Ultraviolet-visible spectroscopy is one of the most reported techniques to analyze concentration quickly and economically, but the methodologies to prepare dispersions and selecting the wavelengths for ultraviolet-visible measurements have not yet been clearly defined. The present study demonstrates that dispersion procedures influence absorbance, and an approach to determine the most appropriate measurement wavelength is proposed. Ecotoxicity tests with MWCNTs were performed on Vibrio fischeri bacteria, and divergences in the results were observed with respect to those previously reported. The present study contributes to the attempt to overcome the lack of standardization in the environmental assessment of MWCNTs.

  10. Colloidal stability and ecotoxicity of multiwalled carbon nanotubes: Influence of select organic matters.

    PubMed

    Cerrillo, Cristina; Barandika, Gotzone; Igartua, Amaya; Areitioaurtena, Olatz; Uranga, Nerea; Mendoza, Gemma

    2016-01-01

    In the last few years, the release of multiwalled carbon nanotubes (MWCNTs) into the environment has raised serious concerns regarding their fate and potential impacts. Aquatic organisms constitute an important pathway for their entrance and transfer throughout the food web, and the current demand for standardization of methodologies to analyze the interactions of MWCNTs with them requires aquatic media that represent natural systems. However, the inherent hydrophobicity of MWCNTs and the substances present in natural waters may greatly affect their stability and bioavailability. The present study analyzes the influence of the most referenced synthetic and natural organic matters (Sigma-Aldrich humic acid and Suwannee River natural organic matter) in the agglomeration kinetics and ecotoxicity of MWCNTs, with the aim of determining their suitability to fulfill the current standardization requirements. Natural organic matter provides increased colloidal stability to the MWCNTs' dispersions, which results in higher adverse effects on the key invertebrate organism Daphnia magna. Furthermore, the results obtained with this type of organic matter allow for observation of the important role of the outer diameter and content impurities of MWCNTs in their stability and ecotoxicity on daphnids. Sigma-Aldrich humic acid appeared to alter the response of the organisms to carbon nanotubes compared with that observed in the presence of natural organic matter.

  11. Spatial frequency heterodyne imaging of aqueous phase transitions inside multi-walled carbon nanotubes.

    PubMed

    Schunk, F M; Rand, D; Rose-Petruck, C

    2015-12-14

    The evaporation and condensation of water on multi-walled carbon nanotube (MWCNT) surfaces was studied as a function of temperature and time using X-ray spatial frequency heterodyne imaging (SFHI). SFHI is an imaging modality that produces an absorption and scatter image in a single exposure, and has increased sensitivity to variations in electron density relative to more common place X-ray imaging techniques. Differing features exhibited in the temporal scatter intensity profiles recorded during evaporation and condensation revealed the existence of an absorption-desorption hysteresis. Effects on the aforementioned phenomena due to chemical functionalization of the carbon nanotube surfaces were also monitored. The increased interaction potential between the functionalized MWCNT walls and water molecules altered the evaporation event time scale and increased the temperature at which condensation could take place. Theoretical calculations were used to correlate the shape of the observed scatter profiles during condensation to changes in the MWCNT cross section geometry and configuration of the contained water volume. Changes in evaporation time scales with temperature coincided with the boiling point for confined water predicted by the Kelvin equation, indicating that a thermodynamic description of mesoscopic confined water is permissible in some instances. PMID:26549826

  12. Enhanced dispersion of multiwall carbon nanotubes in natural rubber latex nanocomposites by surfactants bearing phenyl groups.

    PubMed

    Mohamed, Azmi; Anas, Argo Khoirul; Bakar, Suriani Abu; Ardyani, Tretya; Zin, Wan Manshol W; Ibrahim, Sofian; Sagisaka, Masanobu; Brown, Paul; Eastoe, Julian

    2015-10-01

    Here is presented a systematic study of the dispersibility of multiwall carbon nanotubes (MWCNTs) in natural rubber latex (NR-latex) assisted by a series of single-, double-, and triple-sulfosuccinate anionic surfactants containing phenyl ring moieties. Optical polarising microscopy, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and Raman spectroscopy have been performed to obtain the dispersion-level profiles of the MWCNTs in the nanocomposites. Interestingly, a triple-chain, phenyl-containing surfactant, namely sodium 1,5-dioxo-1,5-bis(3-phenylpropoxy)-3-((3-phenylpropoxy)carbonyl) pentane-2-sulfonate (TCPh), has a greater capacity the stabilisation of MWCNTs than a commercially available single-chain sodium dodecylbenzenesulfonate (SDBS) surfactant. TCPh provides significant enhancements in the electrical conductivity of nanocomposites, up to ∼10(-2) S cm(-1), as measured by a four-point probe instrument. These results have allowed compilation of a road map for the design of surfactant architectures capable of providing the homogeneous dispersion of MWCNTs required for the next generation of polymer-carbon-nanotube materials, specifically those used in aerospace technology. PMID:26070188

  13. Electrochemistry of metoclopramide at multi-walled carbon nanotube modified electrode and its voltammetric detection.

    PubMed

    Guo, Wei; Geng, Mingjiang; Zhou, Lingyun

    2012-01-01

    A simple, sensitive and inexpensive electrochemical method was developed for the determination of metoclopramide (MCP) with a multi-wall carbon nanotube (MWNT) modified glassy carbon electrode (GCE). MWNT was dispersed into polyacrylic acid (PAA); the aqueous suspension was then cast on GCE electrodes, forming MWNT-PAA films after evaporation of the solvent. The electrochemical behavior of MCP at the MWNT-modified electrode was investigated in detail. Compared with the bare GCE, the MWNT-modified electrode exhibits electrocatalytic activity to the oxidation of MCP because of the significant oxidation peak-current enhancement. Furthermore, various experimental parameters, such as the solution pH value, the amount of MWNT-PAA suspension and accumulation conditions were optimized for the determination of MCP. Based on the electrocatalytic effect of the MWNT-modified electrode, linear sweep voltammetry (LSV) was developed for the determination of MCP with the linear response in the range from 1.0 × 10(-7) to 1.0 × 10(-5) mol L(-1) and a detection limit of 5.0 × 10(-8) mol L(-1). The method has been successfully applied to the determination of MCP in commercial MCP tablets.

  14. Characterization of multi-walled carbon nanotube-polymer nanocomposites by scanning spreading resistance microscopy.

    PubMed

    Souier, Tewfik; Stefancich, Marco; Chiesa, Matteo

    2012-10-12

    Nanocomposites of aligned multi-walled carbon nanotubes (CNTs) embedded in a polymer matrix yield a unique combination of thermal and electrical properties and mechanical strength. These properties are intimately related to the composite nanostructure and to the growth and processing conditions. The alignment of the tubes, the filling fraction and the contact junction between the nanotubes are key parameters controlling the composite electrical conductivity. For this purpose, a full description of the composite nanostructure is required. Among the non-destructive scanning probe techniques, scanning spreading resistance microscopy is found to be a powerful technique in identifying the carbon nanotubes with true nanometer resolution, thus competing with SEM and TEM imaging. Additionally, the technique provides valuable information about the electrical conduction mechanism within the composite structure. Indeed, by using a controlled contact force and an appropriate model of conduction at the nanoscale, the tip-CNT contact resistance, the CNT intrinsic resistance and the CNT-epoxy-CNT resistance junction are evaluated. This latter is found to be the factor controlling the overall electrical conductivity of the composite. PMID:22995850

  15. Hydrothermally mixed hydroxyapatite-multiwall carbon nanotubes composite coatings on biomedical alloys by electrophoretic deposition.

    PubMed

    Ustundag, C B; Avciata, O; Kaya, F; Kaya, C

    2013-02-14

    Hydroxyapatite (HA) coatings have been used to improve biological and mechanical fixation of metallic prosthesis. Because of extraordinary features of carbon nanotubes (CNTs), they have a lot of facilities, such as extremely strong nanoreinforcement materials for composites. HA powders were synthesized and mixed with multiwalled carbon nanotubes (MWCNTs) by a hydrothermal process. Calcium acetate (Ca (CH(3)COO)(2)) and phosphoric acid (H(3)PO(4)) were used as starting materials for synthesizing nano-HA powders. HA-MWCNTs were treated together hydrothermally at 200 °C for 2 h to synthesize nano-HA powders mixed homogeneously with MWCNTs. Cathodic deposits were obtained on Ti-based alloys using suspensions containing nano-HA and MWCNTs dispersed in n-butanol solvent. It was shown that MWCNTs interacted with HA powders during hydrothermal processing, and therefore, they can easily be dispersed within aqueous-based suspensions. It was also shown that hydrothermal surface modification of MWCNTs with functional groups was achievable, which was a significant step toward eliminating nonwetting surface behavior of MWCNTs, resulting in obtaining homogeneous dispersion of them in liquids.

  16. Characterization of functionalized multiwalled carbon nanotubes for use in an enzymatic sensor.

    PubMed

    Guadarrama-Fernández, Leonor; Chanona-Pérez, Jorge; Manzo-Robledo, Arturo; Calderón-Domínguez, Georgina; Martínez-Rivas, Adrián; Ortiz-López, Jaime; Vargas-García, Jorge Roberto

    2014-10-01

    Carbon nanotubes (CNT) have proven to be materials with great potential for the construction of biosensors. Development of fast, simple, and low cost biosensors to follow reactions in bioprocesses, or to detect food contaminants such as toxins, chemical compounds, and microorganisms, is presently an important research topic. This report includes microscopy and spectroscopy to characterize raw and chemically modified multiwall carbon nanotubes (MWCNTs) synthesized by chemical vapor deposition with the intention of using them as the active transducer in bioprocessing sensors. MWCNT were simultaneously purified and functionalized by an acid mixture involving HNO3-H2SO4 and amyloglucosidase attached onto the chemically modified MWCNT surface. A 49.0% decrease in its enzymatic activity was observed. Raw, purified, and enzyme-modified MWCNTs were analyzed by scanning and transmission electron microscopy and Raman and X-ray photoelectron spectroscopy. These studies confirmed purification and functionalization of the CNTs. Finally, cyclic voltammetry electrochemistry was used for electrical characterization of CNTs, which showed promising results that can be useful for construction of electrochemical biosensors applied to biological areas. PMID:25156941

  17. Decoration of gold nanoparticles on thin multiwall carbon nanotubes and their use as a glucose sensor

    NASA Astrophysics Data System (ADS)

    Gangwar, Rajesh K.; Dhumale, Vinayak A.; Date, Kalyani S.; Alegaonkar, Prashant; Sharma, Rishi B.; Datar, Suwarna

    2016-03-01

    Thin multiwall carbon nanotubes (MWCNTs) have been decorated with gold nanoparticles (Au NPs) with polyaniline (PANI) as an inter-linker by a simple wet chemical method. The synthesized AuNPs:MWCNT:PANI composite was studied with UV-vis, FTIR, Raman spectroscopy, x-ray diffractometer, transmission electron microscopy (TEM) and atomic force microscopy (AFM). Conducting AFM (C-AFM) images of the composite reveal the role played by the two components in electrochemical reactions. The size of the Au NPs was found to be 13 ± 2 nm in the composite as observed from TEM. The synthesized AuNPs:MWCNT:PANI composite was further drop casted onto a glassy carbon electrode (GCE) for electrocatalytic study. The resulting composite exhibits good electrocatalytic activity towards reduction of H2O2 and O2. A glucose biosensor was developed by immobilizing glucose oxidase into AuNPs:MWCNT:PANI composite film on GCE. The fabricated sensor demonstrates good linear response to glucose (i.e. R = 0.9975) in the range of 2 to 12 mM.

  18. Colloidal stability and ecotoxicity of multiwalled carbon nanotubes: Influence of select organic matters.

    PubMed

    Cerrillo, Cristina; Barandika, Gotzone; Igartua, Amaya; Areitioaurtena, Olatz; Uranga, Nerea; Mendoza, Gemma

    2016-01-01

    In the last few years, the release of multiwalled carbon nanotubes (MWCNTs) into the environment has raised serious concerns regarding their fate and potential impacts. Aquatic organisms constitute an important pathway for their entrance and transfer throughout the food web, and the current demand for standardization of methodologies to analyze the interactions of MWCNTs with them requires aquatic media that represent natural systems. However, the inherent hydrophobicity of MWCNTs and the substances present in natural waters may greatly affect their stability and bioavailability. The present study analyzes the influence of the most referenced synthetic and natural organic matters (Sigma-Aldrich humic acid and Suwannee River natural organic matter) in the agglomeration kinetics and ecotoxicity of MWCNTs, with the aim of determining their suitability to fulfill the current standardization requirements. Natural organic matter provides increased colloidal stability to the MWCNTs' dispersions, which results in higher adverse effects on the key invertebrate organism Daphnia magna. Furthermore, the results obtained with this type of organic matter allow for observation of the important role of the outer diameter and content impurities of MWCNTs in their stability and ecotoxicity on daphnids. Sigma-Aldrich humic acid appeared to alter the response of the organisms to carbon nanotubes compared with that observed in the presence of natural organic matter. PMID:26189503

  19. Fostering hydroxyapatite bioactivity and mechanical strength by Si-doping and reinforcing with multiwall carbon nanotubes.

    PubMed

    Belmamouni, Younes; Bricha, Meriame; Essassi, El Mokhtar; Ferreira, José M F; El Mabrouk, Khalil

    2014-06-01

    The aim of the present study was to prepare resorbable hydroxyapatite (HA) based bone graft materials reinforced with carbon nanotubes as a way to cope with the inability of pure HA to resorb and its intrinsic brittleness and poor strength that restrict its clinical applications under load-bearing conditions. With this purpose, a Si-doped HA nanopowder (n-Si0.8HA) was prepared by chemical synthesis and used as composite matrix reinforced with different amounts of functionalized multiwall carbon nanotubes (MWCNTs). The effect of the added amounts of MWCNTs on the mechanical properties of nanocomposites and their in vitro biomineralization was assessed by bending strength measurements, immersing tests in simulated body fluid solution (SBF), scanning electron microscopy (SEM), and inductively coupled plasma atomic emission spectroscopy analysis (ICP-AES). The bioactivity and bending strength were enhanced, reaching maximum balanced values for an optimum addition of 3 wt.% f-MWCNTs. These results might contribute to broaden the potential applications of HA-based bone grafts. PMID:24738405

  20. An evaluation of the impact of multiwalled carbon nanotubes on soil microbial community structure and functioning.

    PubMed

    Shrestha, Babina; Acosta-Martinez, Veronica; Cox, Stephen B; Green, Micah J; Li, Shibin; Cañas-Carrell, Jaclyn E

    2013-10-15

    This study evaluated the impacts of multiwalled carbon nanotubes (MWNTs) on microbial community composition and functioning in a sandy loam soil over 90 d. We used test concentrations in the range of lower MWNT concentrations (10mg/kg) to extremely high MWNT concentrations (10,000 mg/kg) as a worst case scenario. We observed no effects of MWNTs on soil respiration, enzymatic activities, and microbial community composition at 10, 100 and 1,000 mg/kg. However, increases in fungal fatty acid methyl ester markers were observed at the highest treatment. In addition, pyrosequencing demonstrated a decreased abundance of some bacterial genera like Derxia, Holophaga, Opitutus and Waddlia at the highest treatment while bacterial genera that are considered potential degraders of recalcitrant contaminants (such as polycyclic aromatic hydrocarbons) like Rhodococcus, Cellulomonas, Nocardioides and Pseudomonas increased. These results suggest a shift in soil microbial community composition to more tolerant microbial populations in the presence of extremely high MWNT concentrations. It is unlikely that the change observed at 10,000 mg/kg is due to metal or carbon impurities as the MWNTs used in this study were of high purity. Given the need for wide-ranging data for regulation and risk assessment of nanomaterials, this study provides valuable data. PMID:23921182

  1. Effects of functionalized and raw multi-walled carbon nanotubes on soil bacterial community composition.

    PubMed

    Kerfahi, Dorsaf; Tripathi, Binu M; Singh, Dharmesh; Kim, Hyoki; Lee, Sujin; Lee, Junghoon; Adams, Jonathan M

    2015-01-01

    Carbon nanotubes (CNTs) are widely used in industry, but their environmental impacts on soil microbial communities are poorly known. In this paper, we compare the effect of both raw and acid treated or functionalized (fCNTs) multi-walled carbon nanotubes (MWCNTs) on soil bacterial communities, applying different concentrations of MWCNTs (0 µg/g, 50 µg/g, 500 µg/g and 5000 µg/g) to a soil microcosm system. Soil DNA was extracted at 0, 2 and 8 weeks and the V3 region of the 16S rRNA gene was PCR-amplified and sequenced using paired-end Illumina bar-coded sequencing. The results show that bacterial diversity was not affected by either type of MWCNT. However, overall soil bacterial community composition, as illustrated by NMDS, was affected only by fMWCNT at high concentrations. This effect, detectable at 2 weeks, remained equally strong by 8 weeks. In the case of fMWCNTs, overall changes in relative abundance of the dominant phyla were also found. The stronger effect of fMWCNTs could be explained by their intrinsically acidic nature, as the soil pH was lower at higher concentrations of fMWCNTs. Overall, this study suggests that fMWCNTs may at least temporarily alter microbial community composition on the timescale of at least weeks to months. It appears, by contrast, that raw MWCNTs do not affect soil microbial community composition. PMID:25825905

  2. Effect of Addition of Multiwalled Carbon Nanotubes on the Piezoelectric Properties of Polypropylene Filaments.

    PubMed

    Bayramol, D Vatansever; Soin, N; Hadimani, R L; Shah, T H; Siores, E

    2015-09-01

    The effect of addition of multiwalled carbon nanotubes (CNTs) on the piezoelectric properties of polypropylene (PP) monofilaments has been investigated. Various amounts of CNTs (0%, 0.01%, 0.1% and 1% weight ratios) were melt-blended with PP and the resulting nanocomposites were extruded in a continuous process with simultaneous on-line poling to produce monofilaments. Concurrent stretching at a draw ratio of 5:1 and polarisation at applied electric fields of 15 kV of PP/CNT filaments was observed to enhance the piezoelectric properties. The microstructure and crystallinity of the filaments was analysed using scanning electron microscopy (SEM), differential scanning calorimetric (DSC) and Fourier transform infrared spectroscopy (FTIR) techniques. Voltage generation by the CNT-modified PP filaments was determined by the application of predetermined load impact. The results show that the incorporation of CNTs in the PP fibre structure has a considerable impact on the enhancement of piezoelectric properties of the PP filament obtained that the peak voltage generation was almost four fold (from 0.76 V to 2.92 V) when 0.1 wt% of CNTs added into the polymer. This is owing to the fact that carbon nanotubes act as nucleating agent for enhancing the crystallisation during the melt extrusion process.

  3. Development of iron-containing multiwalled carbon nanotubes for MR-guided laser-induced thermotherapy

    PubMed Central

    Ding, Xuanfeng; Singh, Ravi; Burke, Andrew; Hatcher, Heather; Olson, John; Kraft, Robert A; Schmid, Michael; Carroll, David; Bourland, J Daniel; Akman, Steven; Torti, Frank M; Torti, Suzy V

    2011-01-01

    Aims To test iron-containing multiwalled carbon nanotubes (MWCNTs) as bifunctional nanomaterials for imaging and thermal ablation of tumors. Materials & Methods MWCNTs entrapping iron were synthesized by chemical vapor deposition. The T2-weighted contrast enhancement properties of MWCNTs containing increasing amounts of iron were determined in vitro. Suspensions of these particles were injected into tumor-bearing mice and tracked longitudinally over 7 days by MRI. Heat-generating abilities of these nanomaterials following exposure to near infrared (NIR) laser irradiation was determined in vitro and in vivo. Results The magnetic resonance contrast properties of carbon nanotubes were directly related to their iron content. Iron-containing nanotubes were functional T2-weighted contrast agents in vitro and could be imaged in vivo long-term following injection. Iron content of nanotubes did not affect their ability to generate thermoablative temperatures following exposure to NIR and significant tumor regression was observed in mice treated with MWCNTs and NIR laser irradiation. Conclusion These data demonstrate that iron-containing MWCNTs are functional T2-weighted contrast agents and efficient mediators of tumor-specific thermal ablation in vivo. PMID:21506687

  4. Structural, electronic and photovoltaic characterization of multiwalled carbon nanotubes grown directly on stainless steel.

    PubMed

    Camilli, Luca; Scarselli, Manuela; Gobbo, Silvano Del; Castrucci, Paola; Gautron, Eric; De Crescenzi, Maurizio

    2012-01-01

    We have taken advantage of the native surface roughness and the iron content of AISI-316 stainless steel to grow multiwalled carbon nanotubes (MWCNTs) by chemical vapour deposition without the addition of an external catalyst. The structural and electronic properties of the synthesized carbon nanostructures have been investigated by a range of electron microscopy and spectroscopy techniques. The results show the good quality and the high graphitization degree of the synthesized MWCNTs. Through energy-loss spectroscopy we found that the electronic properties of these nanostructures are markedly different from those of highly oriented pyrolytic graphite (HOPG). Notably, a broadening of the π-plasmon peak in the case of MWCNTs is evident. In addition, a photocurrent was measured when MWCNTs were airbrushed onto a silicon substrate. External quantum efficiency (EQE) and photocurrent values were reported both in planar and in top-down geometry of the device. Marked differences in the line shapes and intensities were found for the two configurations, suggesting that two different mechanisms of photocurrent generation and charge collection are in operation. From this comparison, we are able to conclude that the silicon substrate plays an important role in the production of electron-hole pairs. PMID:23016140

  5. Decorating multi-walled carbon nanotubes with nickel nanoparticles for selective hydrogenation of citral

    NASA Astrophysics Data System (ADS)

    Tang, Yuechao; Yang, Dong; Qin, Feng; Hu, Jianhua; Wang, Changchun; Xu, Hualong

    2009-08-01

    The nanocomposites of multi-walled carbon nanotubes (MWNTs) decorated with nickel nanoparticles were conveniently prepared by a chemical reduction of nickel salt in the present of poly(acrylic acid) grafted MWNTs (PAA- g-MWNTs). Due to the strong interaction between Ni 2+ and -COOH, PAA- g-MWNTs became an excellent supporting material for Ni nanoparticles. The morphology and distribution of Ni nanoparticles on the surface of MWNTs were greatly influenced by the reduction temperatures, the experimental results also showed that the distribution of Ni nanoparticles was greatly improved while the MWNTs were modified by poly(acrylic acid) (PAA). The hydrogenation activity and selectivity of MWNTs decorated with Ni nanoparticles (Ni-MWNTs) for α, β-unsaturated aldehyde (citral) were also studied, and the experimental results showed that the citronellal, an important raw material for flavoring and perfumery industries, is the favorable product with a percentage as high as 86.9%, which is 7 times higher than that of catalyst by Ni-supported active carbon (Ni-AC).

  6. Effect of Addition of Multiwalled Carbon Nanotubes on the Piezoelectric Properties of Polypropylene Filaments.

    PubMed

    Bayramol, D Vatansever; Soin, N; Hadimani, R L; Shah, T H; Siores, E

    2015-09-01

    The effect of addition of multiwalled carbon nanotubes (CNTs) on the piezoelectric properties of polypropylene (PP) monofilaments has been investigated. Various amounts of CNTs (0%, 0.01%, 0.1% and 1% weight ratios) were melt-blended with PP and the resulting nanocomposites were extruded in a continuous process with simultaneous on-line poling to produce monofilaments. Concurrent stretching at a draw ratio of 5:1 and polarisation at applied electric fields of 15 kV of PP/CNT filaments was observed to enhance the piezoelectric properties. The microstructure and crystallinity of the filaments was analysed using scanning electron microscopy (SEM), differential scanning calorimetric (DSC) and Fourier transform infrared spectroscopy (FTIR) techniques. Voltage generation by the CNT-modified PP filaments was determined by the application of predetermined load impact. The results show that the incorporation of CNTs in the PP fibre structure has a considerable impact on the enhancement of piezoelectric properties of the PP filament obtained that the peak voltage generation was almost four fold (from 0.76 V to 2.92 V) when 0.1 wt% of CNTs added into the polymer. This is owing to the fact that carbon nanotubes act as nucleating agent for enhancing the crystallisation during the melt extrusion process. PMID:26716297

  7. Interrelationship between single- and multi-wall carbon nanotube growth rates for CVD process

    SciTech Connect

    Wood, Richard F; Pannala, Sreekanth; Wells, Jack C; Puretzky, Alexander A; Geohegan, David B

    2007-01-01

    Recent time-resolved measurements of carbon nanotube (CNT) growth on Fe and Fe/Mo catalysts have identified a maximum growth rate and temperature corresponding to the onset of small-diameter, single-wall CNT (SWNT) formation. A simple model described here emphasizes the essential role of the SWNTs in the growth process of CNTs. Remarkably, it shows that the growth rate (i.e. the time derivative of the length) of a multi-walled CNT (MWNT) is the same as that of a SWNT at the carbon flux and diffusion coefficient corresponding to a given temperature. Moreover, below ~700C, the temperature above which SWNT growth is observed for a 6 sccm C2H2 flow rate, the number of walls as a function of temperature is uniquely determined by the interplay of the incident flux of atomic C and diffusion rates consistent with bulk diffusion. Even partial melting of the catalytic particle is unnecessary to explain the experimental results on growth rate and number of walls. Above 700C, where severe catalyst poisoning ordinarily begins, the growth rate without poisoning is consistent with recent results of Hata and co-workers for "supergrowth".

  8. Characterization of functionalized multiwalled carbon nanotubes for use in an enzymatic sensor.

    PubMed

    Guadarrama-Fernández, Leonor; Chanona-Pérez, Jorge; Manzo-Robledo, Arturo; Calderón-Domínguez, Georgina; Martínez-Rivas, Adrián; Ortiz-López, Jaime; Vargas-García, Jorge Roberto

    2014-10-01

    Carbon nanotubes (CNT) have proven to be materials with great potential for the construction of biosensors. Development of fast, simple, and low cost biosensors to follow reactions in bioprocesses, or to detect food contaminants such as toxins, chemical compounds, and microorganisms, is presently an important research topic. This report includes microscopy and spectroscopy to characterize raw and chemically modified multiwall carbon nanotubes (MWCNTs) synthesized by chemical vapor deposition with the intention of using them as the active transducer in bioprocessing sensors. MWCNT were simultaneously purified and functionalized by an acid mixture involving HNO3-H2SO4 and amyloglucosidase attached onto the chemically modified MWCNT surface. A 49.0% decrease in its enzymatic activity was observed. Raw, purified, and enzyme-modified MWCNTs were analyzed by scanning and transmission electron microscopy and Raman and X-ray photoelectron spectroscopy. These studies confirmed purification and functionalization of the CNTs. Finally, cyclic voltammetry electrochemistry was used for electrical characterization of CNTs, which showed promising results that can be useful for construction of electrochemical biosensors applied to biological areas.

  9. Enhanced water vapor separation by temperature-controlled aligned-multiwalled carbon nanotube membranes

    NASA Astrophysics Data System (ADS)

    Jeon, Wonjae; Yun, Jongju; Khan, Fakhre Alam; Baik, Seunghyun

    2015-08-01

    Here we present a new strategy of selectively rejecting water vapor while allowing fast transport of dry gases using temperature-controlled aligned-multiwalled carbon nanotubes (aligned-MWNTs). The mechanism is based on the water vapor condensation at the entry region of nanotubes followed by removing aggregated water droplets at the tip of the superhydrophobic aligned-MWNTs. The first condensation step could be dramatically enhanced by decreasing the nanotube temperature. The permeate-side relative humidity was as low as ~17% and the helium-water vapor separation factor was as high as 4.62 when a helium-water vapor mixture with a relative humidity of 100% was supplied to the aligned-MWNTs. The flow through the interstitial space of the aligned-MWNTs allowed the permeability of single dry gases an order of magnitude higher than the Knudsen prediction regardless of membrane temperature. The water vapor separation performance of hydrophobic polytetrafluoroethylene membranes could also be significantly enhanced at low temperatures. This work combines the membrane-based separation technology with temperature control to enhance water vapor separation performance.Here we present a new strategy of selectively rejecting water vapor while allowing fast transport of dry gases using temperature-controlled aligned-multiwalled carbon nanotubes (aligned-MWNTs). The mechanism is based on the water vapor condensation at the entry region of nanotubes followed by removing aggregated water droplets at the tip of the superhydrophobic aligned-MWNTs. The first condensation step could be dramatically enhanced by decreasing the nanotube temperature. The permeate-side relative humidity was as low as ~17% and the helium-water vapor separation factor was as high as 4.62 when a helium-water vapor mixture with a relative humidity of 100% was supplied to the aligned-MWNTs. The flow through the interstitial space of the aligned-MWNTs allowed the permeability of single dry gases an order of

  10. Enhanced microwave shielding and mechanical properties of multiwall carbon nanotubes anchored carbon fiber felt reinforced epoxy multiscale composites

    NASA Astrophysics Data System (ADS)

    Singh, B. P.; Bharadwaj, Preetam; Choudhary, Veena; Mathur, R. B.

    2014-04-01

    Multi-walled carbon nanotubes (MWCNTs) were grown on carbon fiber (CF) felt by chemical vapor deposition that resulted into strongly anchored carbon nanotubes (CNTs) on the CF surface. These multiscale preforms were used as the reinforcement in epoxy resin to develop multi scale CF felt-MWCNT/epoxy composites. The flexural strength (FS) and the flexural modulus (FM) of the composites were found to increase with increasing amount of CNTs grown on CF felt surface. FS improved by 37 %, i.e. 119 MPa compared to 87 MPa for CF felt/epoxy composites prepared under identical conditions. The FM also improved by 153 %, i.e. 15.7 GPa compared to 6.2 GPa for the CF/epoxy composites. The incorporation of MWCNTs on the CF felt produced a significant change in the electromagnetic interference shielding of these composites which improved from -21 to -27 dB for CF felt-MWCNT/epoxy multiscale composites in the Ku band (12.4-18 GHz) and indicates the usefulness of these strong composites for microwave shielding.

  11. Optical properties of carbon nanostructures produced by laser irradiation on chemically modified multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Santiago, Enrique Vigueras; López, Susana Hernández; Camacho López, Marco A.; Contreras, Delfino Reyes; Farías-Mancilla, Rurik; Flores-Gallardo, Sergio G.; Hernández-Escobar, Claudia A.; Zaragoza-Contreras, E. Armando

    2016-10-01

    This research focused on the nanosecond (Nd: YAG-1064 nm) laser pulse effect on the optical and morphological properties of chemically modified multi-walled carbon nanotubes (MWCNT). Two suspensions of MWCNT in tetrahydrofuran (THF) were prepared, one was submitted to laser pulses for 10 min while the other (blank) was only mechanically homogenized during the same time. Following the laser irradiation, the suspension acquired a yellow-amber color, in contrast to the black translucent appearance of the blank. UV-vis spectroscopy confirmed this observation, showing the blank a higher absorption. Additionally, photoluminescence measurements exhibited a broad blue-green emission band both in the blank and irradiated suspension when excited at 369 nm, showing the blank a lower intensity. However, a modification in the excitation wavelength produced a violet to green tuning in the irradiated suspension, which did not occur in the blank. Lastly, the electron microscopy analysis of the treated nanotubes showed the abundant formation of amorphous carbon, nanocages, and nanotube unzipping, exhibiting the intense surface modification produced by the laser pulse. Nanotube surface modification and the coexistence with the new carbon nanostructures were considered as the conductive conditions for optical properties modification.

  12. Polyurea-functionalized multiwalled carbon nanotubes: synthesis, morphology, and Raman spectroscopy.

    PubMed

    Gao, Chao; Jin, Yi Zheng; Kong, Hao; Whitby, Raymond L D; Acquah, Steve F A; Chen, G Y; Qian, Huihong; Hartschuh, Achim; Silva, S R P; Henley, Simon; Fearon, Peter; Kroto, Harold W; Walton, David R M

    2005-06-23

    An in situ polycondensation approach was applied to functionalize multiwalled carbon nanotubes (MWNTs), resulting in various linear or hyperbranched polycondensed polymers [e.g., polyureas, polyurethanes, and poly(urea-urethane)-bonded carbon nanotubes]. The quantity of the grafted polymer can be easily controlled by the feed ratio of monomers. As a typical example, the polyurea-functionalized MWNTs were measured and characterized in detail. The oxidized MWNTs (MWNT-COOH) were converted into acyl chloride-functionalized MWNTs (MWNT-COCl) by reaction with neat thionyl chloride (SOCl2). MWNT-COCl was reacted with excess 1,6-diaminohexane, affording amino-functionalized MWNTs (MWNT-NH2). In the presence of MWNT-NH2, the polyurea was covalently coated onto the surfaces of the nanotube by in situ polycondensation of diisocyanate [e.g., 4,4'-methylenebis(phenylisocyanate)] and 1,6-diaminohexane, followed by the removal of free polymer via repeated filtering and solvent washing. The coated polyurea content can be controlled to some extent by adjusting the feed ratio of the isocyanato and amino groups. The structure and morphology of the resulting nanocomposites were characterized by FTIR, NMR, Raman, confocal Raman, TEM, EDS, and SEM measurements. The polyurea-coated MWNTs showed interesting self-assembled flat- or flowerlike morphologies in the solid state. The signals corresponding to that of the D and G bands of the carbon nanotubes were strongly attenuated after polyurea was chemically tethered to the MWNT surfaces. Comparative experiments showed that the grafted polymer species and structures have a strong effect on the Raman signals of polymer-functionalized MWNTs. PMID:16852469

  13. Influence of multi-walled carbon nanotubes on the cognitive abilities of Wistar rats

    PubMed Central

    Sayapina, Nina V.; Sergievich, Alexander A.; Kuznetsov, Vladimir L.; Chaika, Vladimir V.; Lisitskaya, Irina G.; Khoroshikh, Pavel P.; Batalova, Tatyana A.; Tsarouhas, Kostas; Spandidos, Demetrios; Tsatsakis, Aristidis M.; Fenga, Concettina; Golokhvast, Kirill S.

    2016-01-01

    Studies of the neurobehavioral effects of carbon nanomaterials, particularly those of multi-walled carbon nanotubes (MWCNTs), have concentrated on cognitive effects, but data are scarce. The aim of this study was to assess the influence of MWCNTs on a number of higher nervous system functions of Wistar rats. For a period of 10 days, two experimental groups were fed with MWCNTs of different diameters (MWCNT-1 group, 8–10 nm; MWCNT-2 group, 18–20 nm) once a day at a dosage of 500 mg/kg. In the open-field test, reductions of integral indications of researching activity were observed for the two MWCNT-treated groups, with a parallel significant (P<0.01) increase in stress levels for these groups compared with the untreated control group. In the elevated plus-maze test, integral indices of researching activity in the MWCNT-1 and MWCNT-2 groups reduced by day 10 by 51 and 62%, respectively, while rat stress levels remained relatively unchanged. In the universal problem solving box test, reductions in motivation and energy indices of researching activity were observed in the two experimental groups. Searching activity in the MWCNT-1 group by day 3 was reduced by 50% (P<0.01) and in the MWCNT-2 group the relevant reduction reached 11.2%. By day 10, the reduction compared with controls, was 64% (P<0.01) and 58% (P<0.01) for the MWCNT-1 and MWCNT-2 groups, respectively. In conclusion, a series of specific tests demonstrated that MWCNT-treated rats experienced a significant reduction of some of their cognitive abilities, a disturbing and worrying finding, taking into consideration the continuing and accelerating use of carbon nanotubes in medicine and science. PMID:27588053

  14. Functionalization of multi-walled carbon nanotubes using water-assisted chemical vapor deposition

    SciTech Connect

    Ran Maofei; Sun Wenjing; Liu Yan; Chu Wei; Jiang Chengfa

    2013-01-15

    A simple and novel method, water-assisted chemical vapor deposition (CVD) was developed to functionalize multi-walled carbon nanotubes (MWCNTs) during the synthesis process. The functionalized MWCNTs were characterized using Raman spectroscopy, XPS, TGA, NH{sub 3}-TPD, SEM and HR-TEM. It was found that new defects are introduced and the amount of acidic groups is increased on the MWCNT surface during the water-assisted CVD process. The amount of C-OH and C-O group on the MWCNT surface is found to be increased from 21.1% to 42% with water vapor assistance. Density functional theory (DFT) was employed to study the chemical behavior of water vapor molecule on the catalyst particle surface of Ni(1 1 1) cluster. Based on the experimental and DFT simulation results, a mechanism for functionalization of MWCNTs by water-assisted CVD is proposed. - Graphical abstract: Water is adsorbed and activated on Ni surface, then dissociated into OH and O species, followed by part of OH and O species desorbed from the surface. Finally, the desorbed OH and O species oxidize the unsaturated carbon atoms of carbon nanotubes, form defects and oxygen-containing groups. Highlights: Black-Right-Pointing-Pointer MWCNTs were functionalized by water-assisted CVD method. Black-Right-Pointing-Pointer Defects and weak-medium acidic sites were created on the MWCNT sidewalls. Black-Right-Pointing-Pointer Oxygen-containing groups in functionalized MWCNT were increased from 21.1% to 42%. Black-Right-Pointing-Pointer A mechanism for the influence of water vapor on MWCNTs was proposed.

  15. Toxicogenomic comparison of multi-wall carbon nanotubes (MWCNTs) and asbestos.

    PubMed

    Kim, Jin Sik; Song, Kyung Seuk; Lee, Jin Kyu; Choi, Young C; Bang, In Seok; Kang, Chang Soo; Yu, Il Je

    2012-04-01

    Carbon nanotubes (CNTs) have specific properties, including electrical and thermal conductivity, great strength, and rigidity, that allow them to be used in many fields. However, this increasing contact with humans and the environment is also raising health and safety concerns. Thus, research on the safety of CNTs has attracted much interest, including a comparison of the toxic effects of asbestos and carbon nanotubes, due to their physical similarity of a high aspect ratio (length/diameter). Nonetheless, there has not yet been a toxicogenomic comparison. Therefore, to examine toxicogenomic effects, the 50% growth inhibition (GI(50)) concentration was determined for multi-wall carbon nanotubes (MWCNTs) and asbestos (crocidolite) and found to be approximately 0.0135 and 0.066%, respectively, in the case of 24-h treatment of normal human bronchial epithelia (NHBE) cells. Using these GI(50) concentrations, NHBE cells were then treated with MWCNTs and asbestos for 6 and 24 h, followed by a DNA microarray analysis. Among 31,647 genes, 1,201 and 1,252 were up-regulated by both asbestos and MWCNTs after 6 and 24 h of exposure, respectively. Meanwhile, 1,977 and 1,542 genes were down-regulated by both asbestos and MWNCTs after 6 and 24 h of exposure, respectively. In particular, the asbestos and MWCNTs both induced an over twofold up- and down-regulated expression of 12 mesothelioma-related genes and 22 lung cancer-related genes when compared with the negative control. Plus, the genes induced by the MWCNT exposure were expressed in the brain, lungs, epithelium, liver, and colon.

  16. Magnesia tuned multi-walled carbon nanotubes–reinforced alumina nanocomposites

    SciTech Connect

    Ahmad, Iftikhar; Islam, Mohammad; Dar, Mushtaq Ahmad; Xu, Fang; Shah, Syed Ismat; Zhu, Yanqiu

    2015-01-15

    Magnesia tuned alumina ceramic nanocomposites, reinforced with multi-walled carbon nanotubes, were condensed using pressureless and hot-press sintering processes. Densification, microstructure and mechanical properties of the produced nanocomposites were meticulously investigated. Electron microscopy studies revealed the homogenous carbon nanotube dispersion within the alumina matrix and confirmed the retention of carbon nanotubes' distinctive tubular morphology and nanoscale features during the extreme mixing/sintering processes. Pressureless sintered nanocomposites showed meagre mechanical responses due to the poorly-integrated microstructures with a slight improvement upon magnesia addition. Conversely, both the magnesia addition and application of hot-press sintering technique resulted in the nanocomposite formation with near-theoretical densities (~ 99%), well-integrated microstructures and superior mechanical properties. Hot-press sintered nanocomposites incorporating 300 and 600 ppm magnesia exhibited an increase in hardness (10 and 11%), flexural strength (5 and 10%) and fracture toughness (15 and 20%) with respect to similar magnesia-free samples. Compared to monolithic alumina, a decent rise in fracture toughness (37%), flexural strength (22%) and hardness (20%) was observed in the hot-press sintered nanocomposites tuned with merely 600 ppm magnesia. Mechanically superior hot-press sintered magnesia tailored nanocomposites are attractive for several load-bearing structural applications. - Highlights: • MgO tailored Al{sub 2}O{sub 3}–2 wt.% CNT nanocomposites are presented. • The role of MgO and sintering on nanocomposite structures and properties was studied. • Well-dispersed CNTs maintained their morphology/structure after harsh sintering. • Hot-pressing and MgO led nanocomposites to higher properties/unified structures. • MgO tuned composites showed higher toughness (37%) and strength (22%) than Al{sub 2}O{sub 3}.

  17. Experimental Study of Magnetic Multi-Walled Carbon Nanotube-Doxorubicin Conjugate in a Lymph Node Metastatic Model of Breast Cancer

    PubMed Central

    Ji, Jian; Liu, Minfeng; Meng, Yue; Liu, Runqi; Yan, Yan; Dong, Jianyu; Guo, Zhaoze; Ye, Changsheng

    2016-01-01

    Background The lymphatic system plays a significant role in the defense of a subject against breast cancer and is one of the major pathways for the metastasis of breast cancer. To improve the prognosis, many means, including surgery, radiotherapy, and chemotherapy, have been used. However, the combination of all these modalities has limited efficacy. Lymph nodes, therefore, have become an exceptionally potential target organ in cancer chemotherapy. Material/Methods A lymph node metastatic model of breast cancer was established in BALB/c mice. Magnetic multi-walled carbon nanotube carrier with good adsorption and lymph node-targeting capacity was prepared and conjugated with doxorubicin to make the magnetic multi-walled carbon nanotube-doxorubicin suspension. Dispersions of doxorubicin, magnetic multi-walled carbon nanotube-doxorubicin, and magnetic multi-walled carbon nanotube were injected into lymph node metastatic mice to compare their inhibitory effects on tumor cells in vivo. Inhibition of these dispersions on EMT-6 breast cancer cells was detected via MTT assay in vitro. Results Although no significant difference was found between the effects of doxorubicin and magnetic multi-walled carbon nanotube-doxorubicin with the same concentration of doxorubicin on EMT-6 breast cancer cells in vitro, in terms of sizes of metastatic lymph nodes and xenograft tumors, apoptosis in metastatic lymph nodes, and adverse reactions, the magnetic multi-walled carbon nanotube-doxorubicin group differed significantly from the other groups. Conclusions The magnetic multi-walled carbon nanotube-doxorubicin clearly played an inhibitory role in lymph node metastases to EMT-6 breast cancer cells. PMID:27385226

  18. Experimental Study of Magnetic Multi-Walled Carbon Nanotube-Doxorubicin Conjugate in a Lymph Node Metastatic Model of Breast Cancer.

    PubMed

    Ji, Jian; Liu, Minfeng; Meng, Yue; Liu, Runqi; Yan, Yan; Dong, Jianyu; Guo, Zhaoze; Ye, Changsheng

    2016-01-01

    BACKGROUND The lymphatic system plays a significant role in the defense of a subject against breast cancer and is one of the major pathways for the metastasis of breast cancer. To improve the prognosis, many means, including surgery, radiotherapy, and chemotherapy, have been used. However, the combination of all these modalities has limited efficacy. Lymph nodes, therefore, have become an exceptionally potential target organ in cancer chemotherapy. MATERIAL AND METHODS A lymph node metastatic model of breast cancer was established in BALB/c mice. Magnetic multi-walled carbon nanotube carrier with good adsorption and lymph node-targeting capacity was prepared and conjugated with doxorubicin to make the magnetic multi-walled carbon nanotube-doxorubicin suspension. Dispersions of doxorubicin, magnetic multi-walled carbon nanotube-doxorubicin, and magnetic multi-walled carbon nanotube were injected into lymph node metastatic mice to compare their inhibitory effects on tumor cells in vivo. Inhibition of these dispersions on EMT-6 breast cancer cells was detected via MTT assay in vitro. RESULTS Although no significant difference was found between the effects of doxorubicin and magnetic multi-walled carbon nanotube-doxorubicin with the same concentration of doxorubicin on EMT-6 breast cancer cells in vitro, in terms of sizes of metastatic lymph nodes and xenograft tumors, apoptosis in metastatic lymph nodes, and adverse reactions, the magnetic multi-walled carbon nanotube-doxorubicin group differed significantly from the other groups. CONCLUSIONS The magnetic multi-walled carbon nanotube-doxorubicin clearly played an inhibitory role in lymph node metastases to EMT-6 breast cancer cells. PMID:27385226

  19. Experimental Study of Magnetic Multi-Walled Carbon Nanotube-Doxorubicin Conjugate in a Lymph Node Metastatic Model of Breast Cancer.

    PubMed

    Ji, Jian; Liu, Minfeng; Meng, Yue; Liu, Runqi; Yan, Yan; Dong, Jianyu; Guo, Zhaoze; Ye, Changsheng

    2016-07-07

    BACKGROUND The lymphatic system plays a significant role in the defense of a subject against breast cancer and is one of the major pathways for the metastasis of breast cancer. To improve the prognosis, many means, including surgery, radiotherapy, and chemotherapy, have been used. However, the combination of all these modalities has limited efficacy. Lymph nodes, therefore, have become an exceptionally potential target organ in cancer chemotherapy. MATERIAL AND METHODS A lymph node metastatic model of breast cancer was established in BALB/c mice. Magnetic multi-walled carbon nanotube carrier with good adsorption and lymph node-targeting capacity was prepared and conjugated with doxorubicin to make the magnetic multi-walled carbon nanotube-doxorubicin suspension. Dispersions of doxorubicin, magnetic multi-walled carbon nanotube-doxorubicin, and magnetic multi-walled carbon nanotube were injected into lymph node metastatic mice to compare their inhibitory effects on tumor cells in vivo. Inhibition of these dispersions on EMT-6 breast cancer cells was detected via MTT assay in vitro. RESULTS Although no significant difference was found between the effects of doxorubicin and magnetic multi-walled carbon nanotube-doxorubicin with the same concentration of doxorubicin on EMT-6 breast cancer cells in vitro, in terms of sizes of metastatic lymph nodes and xenograft tumors, apoptosis in metastatic lymph nodes, and adverse reactions, the magnetic multi-walled carbon nanotube-doxorubicin group differed significantly from the other groups. CONCLUSIONS The magnetic multi-walled carbon nanotube-doxorubicin clearly played an inhibitory role in lymph node metastases to EMT-6 breast cancer cells.

  20. Electrical and optical properties of reduced graphene oxide and multi-walled carbon nanotubes based nanocomposites: A comparative study

    NASA Astrophysics Data System (ADS)

    Goumri, Meryem; Lucas, Bruno; Ratier, Bernard; Baitoul, Mimouna

    2016-10-01

    Graphene and multi-walled carbon nanotubes have attracted interest for a number of potential applications. One of the most actively pursued applications uses graphene and carbon nanotubes as a transparent conducting electrode in solar cells, displays or touch screens. In this work, in situ reduced graphene oxide/Poly (vinyl alcohol) and multi-walled carbon nanotubes/Sodium Dodecyl Sulfate/Poly (vinyl alcohol) composites were prepared by water dispersion and different reduction treatments. Comparative studies were conducted to explore the electrical and optical properties of nanocomposites based on graphene and multi-walled carbon nanotubes. A thermal reduction of graphene oxide was more effective, producing films with sheet resistances as low as 102-103 Ω/square with 80% transmittance for 550 nm light. The percolation threshold of the thermally reduced graphene oxide composites (0.35 vol%) was much lower than that of the chemically reduced graphene oxide composites (0.57 vol%), and than that of the carbon nanotubes composites (0.47 vol%). The Seebeck coefficient of graphene oxide films changes from about 40 μV/K to -30 μV/K after an annealing of three hours at 200 °C. The optical absorption of the nanocomposites showed a high absorbance in near UV regions and the photoluminescence enhancement was achieved at 1 wt% graphene loading, while the carbon nanotubes based composite presents a significant emission at 0.7 wt% followed with a photoluminescence quenching at higher fraction of the nanofillers 1.6 wt% TRGO and 1 wt% MWCNTs.

  1. Multi-walled carbon nanotube-induced gene expression in vitro: concordance with in vivo studies

    PubMed Central

    Snyder-Talkington, Brandi N.; Dong, Chunlin; Zhao, Xiangyi; Dymacek, Julian; Porter, Dale W.; Wolfarth, Michael G.; Castranova, Vincent; Qian, Yong; Guo, Nancy L.

    2014-01-01

    There is a current interest in reducing the in vivo toxicity testing of nanomaterials in animals by increasing toxicity testing using in vitro cellular assays; however, toxicological results are seldom concordant between in vivo and in vitro models. This study compared global multi-walled carbon nanotube (MWCNT)-induced gene expression from human lung epithelial and microvascular endothelial cells in monoculture and coculture with gene expression from mouse lungs exposed to MWCNT. Using a cutoff of 10% false discovery rate and 1.5 fold change, we determined that there were more concordant genes (gene expression both up- or downregulated in vivo and in vitro) expressed in both cell types in coculture than in monoculture. When reduced to only those genes involved in inflammation and fibrosis, known outcomes of in vivo MWCNT exposure, there were more disease-related concordant genes expressed in coculture than monoculture. Additionally, different cellular signaling pathways are activated in response to MWCNT dependent upon culturing conditions. As coculture gene expression better correlated with in vivo gene expression, we suggest that cellular cocultures may offer enhanced in vitro models for nanoparticle risk assessment and the reduction of in vivo toxicological testing. PMID:25511174

  2. Functionalizing multi-walled carbon nanotubes using ECR plasma and a mild nitric acid treatment.

    PubMed

    Tseng, Wen-Shou; Tseng, Chyuan-Yow; Kuo, Cheng-Tzu

    2009-12-01

    In the present work, a two-step process combining electron cyclotron resonance (ECR) plasma and 0.25 M nitric acid treatments is utilized to functionalize multi-walled carbon nanotubes (MWCNTs). In the process, high density and high incident energy hydrogen and oxygen cations generated by using ECR plasma system are used to bombard the MWCNTs for 5 min to break C-C bonds, creating free radical defects on the nanotube surface; the treated nanotubes are subsequently sonicated in the mild acid for 2 h, forming functional groups at the defects. Several characterization techniques, including X-ray photoelectron spectroscopy, scanning electron microscopy, Raman spectroscopy, and thermogravimetric analysis, are utilized to systematically evaluate the effect of the method. The results show that the MWCNTs treated by the presented method can contain a high concentration of oxygen-containing functional groups on the nanotube surface with the added advantage of high thermal stability and minimal destructive effects to the material structure. PMID:19908694

  3. A shape-controlled method to functionalize multiwalled carbon nanotubes with Ni3S2.

    PubMed

    Du, Ji Min; Kang, Dae Joon

    2007-11-26

    In this paper, we report the funtionalization of multiwalled carbon nanotubes (MWCNTs) with Ni3S2 using a solvent-thermal approach. The nanocomposites synthesized without ammonia show that the MWCNTs' outer surface was uniformly coated with a Ni3S2 film appearing like centipede-shaped objects when characterized by scanning transmission electron microscopy and transmission electron microscopy images. Meanwhile, the Ni3S2 layer thickness can be changed by simply altering the concentration of reaction precursors and keeping the other reaction conditions constant. Interestingly, clustered Ni3S2 nanoparticles were formed along the outside surfaces of the MWCNTs when ammonia was added to the reaction solution while keeping all other conditions unchanged. Also, the sizes of Ni3S2 nanoparticles can be varied through varying the amount of ammonia in our reaction system. On the basis of our experimental results, we propose a dynamic-controlled Oswald ripening mechanism to elucidate the formation of the MWCNTs composites with centipede-shaped and clustered Ni3S2 morphologies. PMID:17973477

  4. Multi-walled carbon nanotubes (MWCNT): induction of DNA damage in plant and mammalian cells.

    PubMed

    Ghosh, Manosij; Chakraborty, Anirban; Bandyopadhyay, Maumita; Mukherjee, Anita

    2011-12-15

    Increasing use of multiwalled carbon nanotubes (MWCNT) necessitates an improved understanding of their potential impact on environment health. In the present study we evaluated the genotoxicity of MWCNT on plant and mammalian test systems. Genotoxic responses such as chromosomal aberrations and DNA strand breakages were studied in Allium cepa, human lymphocytes, mouse bone marrow cells and pBR322 plasmid DNA. Results showed that MWCNT could cause chromosomal aberrations, DNA fragmentation and apoptosis in Allium root cells that could be correlated with the internalization of MWCNT in the plant cells. In human lymphocytes significant genotoxic response was observed at the concentration 2 μg/ml. Higher concentrations led to a decrease in values of the tail DNA percent that may be due to the formation of crosslinks. Annexin V-FITC-PI staining indicated only a small percentage of cells were undergoing apoptosis. Genotoxic effects were shown by micronuclei (MN) frequencies in experiments on mouse bone marrow cells. In the cell free DNA system (plasmid pBR322), a strong correlation between DNA strand break and concentration was observed. Based on the findings of the present study MWCNT may have significant impact on genomic activities.

  5. Bioaccumulation of Multiwall Carbon Nanotubes in Tetrahymena thermophila by Direct Feeding or Trophic Transfer.

    PubMed

    Mortimer, Monika; Petersen, Elijah J; Buchholz, Bruce A; Orias, Eduardo; Holden, Patricia A

    2016-08-16

    Consumer goods contain multiwall carbon nanotubes (MWCNTs) that could be released during product life cycles into the environment, where their effects are uncertain. Here, we assessed MWCNT bioaccumulation in the protozoan Tetrahymena thermophila via trophic transfer from bacterial prey (Pseudomonas aeruginosa) versus direct uptake from growth media. The experiments were conducted using (14)C-labeled MWCNT ((14)C-MWCNT) doses at or below 1 mg/L, which proved subtoxic since there were no adverse effects on the growth of the test organisms. A novel contribution of this study was the demonstration of the ability to quantify MWCNT bioaccumulation at low (sub μg/kg) concentrations accomplished by employing accelerator mass spectrometry (AMS). After the treatments with MWCNTs at nominal concentrations of 0.01 mg/L and 1 mg/L, P. aeruginosa adsorbed considerable amounts of MWCNTs: (0.18 ± 0.04) μg/mg and (21.9 ± 4.2) μg/mg bacterial dry mass, respectively. At the administered MWCNT dose of 0.3 mg/L, T. thermophila accumulated up to (0.86 ± 0.3) μg/mg and (3.4 ± 1.1) μg/mg dry mass by trophic transfer and direct uptake, respectively. Although MWCNTs did not biomagnify in the microbial food chain, MWCNTs bioaccumulated in the protozoan populations regardless of the feeding regime, which could make MWCNTs bioavailable for organisms at higher trophic levels. PMID:27398725

  6. A comparative study of enzyme immobilization strategies for multi-walled carbon nanotube glucose biosensors

    NASA Astrophysics Data System (ADS)

    Shi, Jin; Claussen, Jonathan C.; McLamore, Eric S.; Haque, Aeraj ul; Jaroch, David; Diggs, Alfred R.; Calvo-Marzal, Percy; Rickus, Jenna L.; Porterfield, D. Marshall

    2011-09-01

    This work addresses the comparison of different strategies for improving biosensor performance using nanomaterials. Glucose biosensors based on commonly applied enzyme immobilization approaches, including sol-gel encapsulation approaches and glutaraldehyde cross-linking strategies, were studied in the presence and absence of multi-walled carbon nanotubes (MWNTs). Although direct comparison of design parameters such as linear range and sensitivity is intuitive, this comparison alone is not an accurate indicator of biosensor efficacy, due to the wide range of electrodes and nanomaterials available for use in current biosensor designs. We proposed a comparative protocol which considers both the active area available for transduction following nanomaterial deposition and the sensitivity. Based on the protocol, when no nanomaterials were involved, TEOS/GOx biosensors exhibited the highest efficacy, followed by BSA/GA/GOx and TMOS/GOx biosensors. A novel biosensor containing carboxylated MWNTs modified with glucose oxidase and an overlying TMOS layer demonstrated optimum efficacy in terms of enhanced current density (18.3 ± 0.5 µA mM - 1 cm - 2), linear range (0.0037-12 mM), detection limit (3.7 µM), coefficient of variation (2%), response time (less than 8 s), and stability/selectivity/reproducibility. H2O2 response tests demonstrated that the most possible reason for the performance enhancement was an increased enzyme loading. This design is an excellent platform for versatile biosensing applications.

  7. Electrochemical sensor for rapid detection of triclosan using a multiwall carbon nanotube film.

    PubMed

    Yang, Jinquan; Wang, Peng; Zhang, Xiaojun; Wu, Kangbing

    2009-10-28

    It is of great importance to develop a rapid analytical method for triclosan because it has been widely added in household products and can form highly toxic dioxin-type derivatives. Herein, an electrochemical sensor based on a multiwall carbon nanotube (MWCNT) film was developed for the rapid detection of triclosan. The electrochemical responses of triclosan were examined, given that its oxidation is irreversible and involves one electron. At the MWCNT film, the oxidation signals of triclosan remarkably increase, suggesting that the MWCNT film exhibits a considerable enhancement effect with triclosan. The analytical parameters, such as pH value, amount of MWCNT suspension, and accumulation time, were optimized. The linear range is from 50 microg L(-1) to 1.75 mg L(-1), and the limit of detection is 16.5 microg L(-1) (about 57 nM). Finally, the new method was successfully employed to detect triclosan in different toothpaste samples, which was testified using high-performance liquid chromatography (HPLC).

  8. Electrical response of liquid crystal cells doped with multi-walled carbon nanotubes

    PubMed Central

    García-García, Amanda; Vergaz, Ricardo; Algorri, José Francisco; Quintana, Xabier

    2015-01-01

    Summary The inclusion of nanoparticles modifies a number of fundamental properties of many materials. Doping of nanoparticles in self-organized materials such as liquid crystals may be of interest for the reciprocal interaction between the matrix and the nanoparticles. Elongated nanoparticles and nanotubes can be aligned and reoriented by the liquid crystal, inducing noticeable changes in their optical and electrical properties. In this work, cells of liquid crystal doped with high aspect ratio multi-walled carbon nanotubes have been prepared, and their characteristic impedance has been studied at different frequencies and excitation voltages. The results demonstrate alterations in the anisotropic conductivity of the samples with the applied electric field, which can be followed by monitoring the impedance evolution with the excitation voltage. Results are consistent with a possible electric contact between the coated substrates of the LC cell caused by the reorientation of the nanotubes. The reversibility of the doped system upon removal of the electric field is quite low. PMID:25821679

  9. Chelerythrine and Fe3O4 Loaded Multi-Walled Carbon Nanotubes for Targeted Cancer Therapy.

    PubMed

    Cao, Liangli; Liang, Yongbo; Zhao, Feijun; Zhao, Xiongjie; Chen, Zhencheng

    2016-06-01

    The work focused on manufacturing improved drug loaded multifunctional magnetic nanoparticles that can overcome the relative non-specificity and potential side-effects of some chemotherapeutic drugs to healthy tissues. A new drug delivery system, Chelerythrine (CHE) and Fe3O4 loaded multi-walled carbon nanotubes (Fe3O4/MWNTs-CHE nanocomposites) that can target hepatocytes when treating malignant tumors, was prepared through a simple adsorption method. The formulation and structure of the Fe3O4/MWNTs-CHE nanocomposites were characterized by vibrating sample magnetometer (VSM), Fourier Transform infrared spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). The cytotoxicity and anti-proliferation effect from the prepared nanocomposites were in vitro tested on human hepatocarcinoma HepG2 and normal liver LO2 cell lines. The results showed the saturated magnetization of Fe3O4/MWNTs-CHE nanocomposites could reach to 45.4O3 emu/g, and the in vitro CHE release behavior exhibited a biphasic release pattern. Moreover, the in vitro cytotoxicity studies revealed that the Fe3O4/MWNTs-CHE nanocomposites showed an efficient inhibition rate to HepG2 cell line and exhibited a lower cytotoxicity to LO2 cell line in comparison to the native CHE. Therefore, the multifunctional Fe3O4/MWNTs-CHE nanocomposites should be a useful and promising candidate for treatment of malignant tumors. PMID:27319224

  10. The decoration of multi-walled carbon nanotubes with nickel oxide nanoparticles using chemical method

    NASA Astrophysics Data System (ADS)

    Sahebian, S.; Zebarjad, S. M.; Vahdati Khaki, J.; Lazzeri, A.

    2016-07-01

    In this paper, nickel oxide (NiO) nanoparticles have been fabricated using wet method and deposited on the surface of multi-walled carbon nanotube (MWCNT). To do so, functional groups were introduced on the surface of MWCNTs by treating with concentrated nitric acid. Nickel oxide nanoparticles were formed on the surface of functionalized MWCNTs by incipient wetness impregnation of nickel nitrate, and the resultant product was calcinated in air atmosphere. Characteristics of the NiO/MWCNT were examined by various techniques, for example, Fourier transform spectroscopy (FTIR), X-ray diffraction analysis (XRD), transmission electron microscopy (TEM), thermogravimetric analyzer (TGA), and nitrogen adsorption-desorption isothermal as well as vibrating sample magnetometer (VSM). The FTIR spectra showed that carboxyl and hydroxyl functional groups existed on the surface of MWNTs after modification by concentrated nitric acid. The pattern of XRD indicated that MWNTs and nickel oxide nanoparticles coexisted in the NiO/MWCNT sample. The TEM images revealed that the NiO nanoparticles were distributed on the surface of the MWNTs, with the size ranging from 5 to 60 nm. Thermogravimetric analysis proved that NiO content decorated on MWCNTs was 80 and 15 wt%. The results of the Brunauer-Emmett-Teller (BET) data showed that the slight increment in the specific surface areas and porosities in the presence of the NiO nanoparticles on the surface of CNT.

  11. Photochemical transformation of carboxylated multiwalled carbon nanotubes: role of reactive oxygen species.

    PubMed

    Qu, Xiaolei; Alvarez, Pedro J J; Li, Qilin

    2013-12-17

    The study investigated the photochemical transformation of carboxylated multiwalled carbon nanotubes (COOH-MWCNTs), an important environmental process affecting their physicochemical characteristics and hence fate and transport. UVA irradiation removed carboxyl groups from COOH-MWCNT surface while creating other oxygen-containing functional groups with an overall decrease in total surface oxygen content. This was attributed to reactions with photogenerated reactive oxygen species (ROS). COOH-MWCNTs generated singlet oxygen ((1)O2) and hydroxyl radical ((•)OH) under UVA light, which exhibited different reactivity toward the COOH-MWCNT surface. Inhibition experiments that isolate the effects of (•)OH and (1)O2 as well as experiments using externally generated (•)OH and (1)O2 separately revealed that (•)OH played an important role in the photochemical transformation of COOH-MWCNTs under UVA irradiation. The Raman spectroscopy and surface functional group analysis results suggested that (•)OH initially reacted with the surface carboxylated carbonaceous fragments, resulting in their degradation or exfoliation. Further reaction between (•)OH and the graphitic sidewall led to formation of defects including functional groups and vacancies. These reactions reduced the surface potential and colloidal stability of COOH-MWCNTs, and are expected to reduce their mobility in aquatic systems. PMID:24255932

  12. Spectroscopic studies on sidewall carboxylic acid functionalization of multi-walled carbon nanotubes with valine.

    PubMed

    Deborah, M; Jawahar, A; Mathavan, T; Dhas, M Kumara; Benial, A Milton Franklin

    2015-03-15

    The valine functionalized multi-walled carbon nanotubes (MWCNTS) were prepared and characterized by using XRD, UV-Vis, FT-IR, EPR, SEM, and EDX, spectroscopic techniques. The enhanced XRD peak (002) intensity was observed for valine functionalized MWCNTs compared with oxidized MWCNTs, which is likely due to sample purification by acid washing. UV-Vis study shows the formation of valine functionalized MWCNTs. FT-IR study confirms the presence of functional groups of oxidized MWCNTs and valine functionalized MWCNTs. The ESR line shape analysis indicates that the observed EPR line shape is a Gaussian line shape. The g-values indicate that the systems are isotropic in nature. The morphology study was carried out for oxidized MWCNTs and valine functionalized MWCNTs by using SEM. The EDX spectra revealed that the high purity of oxidized MWCNTs and valine functionalized MWCNTs. The functionalization has been chosen because, functionalization of CNTs with amino acids makes them soluble and biocompatible. Thus, they have potential applications in the field of biosensors and targeted drug delivery.

  13. Highly selective capture of phosphopeptides using a nano titanium dioxide-multiwalled carbon nanotube nanocomposite.

    PubMed

    Fang, Guozhen; Gao, Wei; Deng, Qiliang; Qian, Kun; Han, Haitao; Wang, Shuo

    2012-04-15

    In this study, a titanium dioxide-multiwalled carbon nanotube (TiO2-MWNT) nanocomposite was first used to enrich phosphopeptides as a binding agent. The TiO2-MWNT nanocomposite was synthesized by the hydrothermal reaction process and characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR), and X-ray powder diffraction (XRD). The results demonstrated that the anatase phase TiO2 nanoparticles had been successfully linked by MWNTs. The TiO2-MWNT nanocomposite was applied as a sorbent to enrich phosphopeptides, and the results showed that the performance of the TiO2-MWNT nanocomposite was better than 5 μm TiO2, as confirmed by the analysis of phosphopeptides from a tryptic digest of a standard protein (β-casein and bovine serum albumin) using high-performance liquid chromatography-electrospray ionization-mass spectrometry (HPLC-ESI-MS). The use of lactic acid in the loading buffer significantly enhances the selectivity of the TiO2-MWNT nanocomposite. This nanocomposite material was further applied to enrich the phosphopeptides in a protein digest obtained from nonfat milk successfully. PMID:22369891

  14. Proteomics-based safety evaluation of multi-walled carbon nanotubes

    SciTech Connect

    Haniu, Hisao; Matsuda, Yoshikazu; Takeuchi, Kenji; Kim, Yoong Ahm; Hayashi, Takuya; Endo, Morinobu

    2010-02-01

    This study evaluated the biological responses to multi-walled carbon nanotubes (MWCNTs). Human monoblastic leukemia cells (U937) were exposed to As-grown MWCNTs and MWCNTs that were thermally treated at 1800 deg. C (HTT1800) and 2800 deg. C (HTT2800). Cell proliferation was highly inhibited by As-grown but not HTT2800. However, both As-grown and HTT1800, which include some impurities, were cytotoxic. Proteomics analysis of MWCNT-exposed cells revealed 37 protein spots on 2-dimensional electrophoresis gels that significantly changed (p < 0.05) after exposure to HTT1800 with a little iron and 20 spots that changed after exposure to HTT2800. Peptide mass fingerprinting identified 45 proteins that included heat shock protein beta-1, neutral alpha-glucosidase AB, and DNA mismatch repair protein Msh2. These altered proteins play roles in metabolism, biosynthesis, response to stress, and cell differentiation. Although HTT2800 did not inhibit cell proliferation or cause cytotoxicity in vitro, some proteins related to the response to stress were changed. Moreover, DJ-1 protein, which is a biomarker of Parkinson's disease and is related to cancer, was identified after exposure to both MWCNTs. These results show that the cytotoxicity of MWCNTs depends on their impurities, such as iron, while MWCNTs themselves cause some biological responses directly and/or indirectly in vitro. Our proteomics-based approach for detecting biological responses to nanomaterials is a promising new method for detailed safety evaluations.

  15. Nanogenerators consisting of direct-grown piezoelectrics on multi-walled carbon nanotubes using flexoelectric effects

    PubMed Central

    Han, Jin Kyu; Jeon, Do Hyun; Cho, Sam Yeon; Kang, Sin Wook; Yang, Sun A.; Bu, Sang Don; Myung, Sung; Lim, Jongsun; Choi, Moonkang; Lee, Minbaek; Lee, Min Ku

    2016-01-01

    We report the first attempt to prepare a flexoelectric nanogenerator consisting of direct-grown piezoelectrics on multi-walled carbon nanotubes (mwCNT). Direct-grown piezoelectrics on mwCNTs are formed by a stirring and heating method using a Pb(Zr0.52Ti0.48)O3 (PZT)-mwCNT precursor solution. We studied the unit cell mismatch and strain distribution of epitaxial PZT nanoparticles, and found that lattice strain is relaxed along the growth direction. A PZT-mwCNT nanogenerator was found to produce a peak output voltage of 8.6 V and an output current of 47 nA when a force of 20 N is applied. Direct-grown piezoelectric nanogenerators generate a higher voltage and current than simple mixtures of PZT and CNTs resulting from the stronger connection between PZT crystals and mwCNTs and an enhanced flexoelectric effect caused by the strain gradient. These experiments represent a significant step toward the application of nanogenerators using piezoelectric nanocomposite materials. PMID:27406631

  16. Magneto-resistance of multiwall carbon nanotube Fermat yarn and coil yarn

    NASA Astrophysics Data System (ADS)

    Truong, Kieu; Kang, Haeyong; Lee, Yourack; Kim, Joong-Gyu; Lee, Young Hee; Suh, Dongseok; IBS CenterIntegrated Nanostructure Physics, InstituteBasic Science (IBS), SKKU, Korea Collaboration; Department of Energy Science, Sungkyunkwan University, Suwon 440-746, Korea Collaboration; Department of Physics, Sungkyunkwan University, Suwon 440-746, Korea Collaboration

    2015-03-01

    Multiwall carbon nanotube (MWCNT) based yarn has attracted a great attention for the development of multifunctional super-fiber due to its light weight, high flexibility, high conductivity, and strong mechanical properties (Lima et al. 2011, Science). Recently the importance of coiled yarn structure was demonstrated for practical applications (Haines et al. 2014, Science). In this study, we measured the electrical resistance of neat yarns and coiled yarns at different temperatures and magnetic fields. The coiled yarn was formed by twist-insertion into the neat yarn, and the transverse and longitudinal magnetoresistance (MR) measurements were carried out. The logarithmic temperature dependence of normalized resistance and the negative MR can be explained by the combined contribution of weak-localization effect and the tunneling transport at different temperature ranges. The magnitude difference of MR between two configurations and the survival of such difference even at room temperature indicate that one-dimensional transport features are quite significant in this system. Developing Route for sub-micrometer-scale coil is discussed. This work was supported by Project code (IBS - R011-D1).

  17. Heteroaggregation of Multiwalled Carbon Nanotubes and Hematite Nanoparticles: Rates and Mechanisms

    PubMed Central

    Huynh, Khanh An; McCaffery, J. Michael; Chen, Kai Loon

    2012-01-01

    The heteroaggregation rates of negatively charged multiwalled carbon nanotubes (CNTs) and positively charged hematite nanoparticles (HemNPs) were obtained over a broad range of nanoparticle distributions using time-resolved dynamic light scattering (DLS). Binary systems comprising CNTs and HemNPs were prepared using low ionic strength solutions to minimize the concurrent occurrence of homoaggregation. In order to elucidate the mechanisms of heteroaggregation, the structures of CNT–HemNP aggregates were observed using cryogenic transmission electron microscopy (cryo-TEM). An initial increase in the CNT concentration, while keeping the HemNP concentration constant, resulted in a corresponding increase in the rate of heteroaggregation which occurred through the bridging of HemNPs by CNT strands. At the optimal CNT/HemNP mass concentration ratio of 0.0316, the heteroaggregation rate reached 3.3 times of the HemNP homoaggregation rate in the diffusion-limited regime. Increasing the CNT/HemNP ratio above the optimal value, however, led to a dramatic decrease in the growth rate of heteroaggregates, likely through a blocking mechanism. In the presence of humic acid, the trends in the variation of the heteroaggregation rate with CNT/HemNP ratio were similar to that in the absence of humic acid. However, as the humic acid concentration was increased, the maximum aggregate growth rate decreased due to the lessening in the available surface of the HemNPs that CNTs can attach to through favorable electrostatic interaction. PMID:22545989

  18. Fluorescence Spectrometry of the Interaction of Multi-Walled Carbon Nanotubes with Catalase

    NASA Astrophysics Data System (ADS)

    Fan, Y.; Li, Y.; Cai, H.; Li, J.; Miao, J.; Fu, D.; Yang, Q.

    2014-11-01

    The interaction of multi-walled carbon nanotubes (MWCNTs) with catalase is investigated using fluorescence and circular dichroism spectroscopic techniques. The results of the fluorescence experiments suggest that MWCNTs quench the intrinsic fluorescence of catalase via a static quenching mechanism. The circular dichroism spectral results reveal the unfolding of catalase with a significant decrease in the α-helix content in the presence of MWCNTs, which indicates that the conformation of catalase is changed in the binding process, thereby remarkably decreasing its activity. The binding constants and the number of binding sites of the MWCNT to the catalase are calculated at different temperatures. The thermodynamic parameters, such as the changes in free energy (ΔG), enthalpy (ΔH), and entropy (ΔS), are calculated using thermodynamic equations. The fact that all negative values of ΔG, ΔH, and ΔS are obtained suggests that the interaction of the MWCNTs with catalase is spontaneous, and that hydrogen bonding and van der Waals interactions play an important role in the binding process.

  19. Structural and magnetic characterization of batch-fabricated nickel encapsulated multi-walled carbon nanotubes.

    PubMed

    Zeeshan, M A; Shou, K; Pané, S; Pellicer, E; Sort, J; Sivaraman, K M; Baró, M D; Nelson, B J

    2011-07-01

    We report on the growth and fabrication of Ni-filled multi-walled carbon nanotubes (Ni-MWNTs) with an average diameter of 115 nm and variable length of 400 nm-1 µm. The Ni-MWNTs were grown using template-assisted electrodeposition and low pressure chemical vapor deposition (LPCVD) techniques. Anodized alumina oxide (AAO) templates were fabricated on Si using a current controlled process. This was followed by the electrodeposition of Ni nanowires (NWs) using galvanostatic pulsed current (PC) electrodeposition. Ni NWs served as the catalyst to grow Ni-MWNTs in an atmosphere of H2/C2H2 at a temperature of 700 °C. Time dependent depositions were carried out to understand the diffusion and growth mechanism of Ni-MWNTs. Characterization was carried out using scanning electron microscopy (SEM), focused ion beam (FIB) milling, transmission electron microscopy (TEM), Raman spectroscopy and energy dispersive x-ray spectroscopy (EDX). TEM analysis revealed that the Ni nanowires possess a fcc structure. To understand the effects of the electrodeposition parameters, and also the effects of the high temperatures encountered during MWNT growth on the magnetic properties of the Ni-MWNTs, vibrating sample magnetometer (VSM) measurements were performed. The template-based fabrication method is repeatable, efficient, enables batch fabrication and provides good control on the dimensions of the Ni-MWNTs. PMID:21606563

  20. Multi-Wall Carbon Nanotubes as Lithium Nanopipettes and SPM Probes

    NASA Astrophysics Data System (ADS)

    Larson, Jonathan; Bharath, Satyaveda; Cullen, William; Reutt-Robey, Janice

    2014-03-01

    A multi-walled carbon nanotube (MWCNT) - terminated SPM cantilever, was utilized to perform nanolithography and surface diffusion measurements on a thin film of vapor-deposited lithium atop a silicon (111) substrate under ultra-high vacuum conditions. In these investigations the MWCNT tip was shown to act as both a lithium nanopipette and a probe for non-contact atomic force microscopy (NC-AFM) measurements. With the application of appropriate bias conditions, the MWCNT could site-selectively extract (expel) nano-scale amounts of lithium from (to) the sample surface. Depressions, mounds, and spikes were generated on the surface in this way and were azimuthally symmetric about the selected point of pipetting. Following lithium transfer to/from the substrate, the MWCNT pipette-induced features were sequentially imaged with NC-AFM using the MWCNT as the probe. Vacancy pits of ca. 300 nm diameter and 1.5 nm depth were observed to decay on a timescale of hours at room temperature, through diffusion-limited decay processes. A continuum model was utilized to simulate the island decay rates, and the lithium surface diffusion coefficient of D =7.5 (+/-1.3)*10-15 cm2/s was extracted. U.S. Department of Energy Award Number DESC0001160.

  1. Nanogenerators consisting of direct-grown piezoelectrics on multi-walled carbon nanotubes using flexoelectric effects

    NASA Astrophysics Data System (ADS)

    Han, Jin Kyu; Jeon, Do Hyun; Cho, Sam Yeon; Kang, Sin Wook; Yang, Sun A.; Bu, Sang Don; Myung, Sung; Lim, Jongsun; Choi, Moonkang; Lee, Minbaek; Lee, Min Ku

    2016-07-01

    We report the first attempt to prepare a flexoelectric nanogenerator consisting of direct-grown piezoelectrics on multi-walled carbon nanotubes (mwCNT). Direct-grown piezoelectrics on mwCNTs are formed by a stirring and heating method using a Pb(Zr0.52Ti0.48)O3 (PZT)-mwCNT precursor solution. We studied the unit cell mismatch and strain distribution of epitaxial PZT nanoparticles, and found that lattice strain is relaxed along the growth direction. A PZT-mwCNT nanogenerator was found to produce a peak output voltage of 8.6 V and an output current of 47 nA when a force of 20 N is applied. Direct-grown piezoelectric nanogenerators generate a higher voltage and current than simple mixtures of PZT and CNTs resulting from the stronger connection between PZT crystals and mwCNTs and an enhanced flexoelectric effect caused by the strain gradient. These experiments represent a significant step toward the application of nanogenerators using piezoelectric nanocomposite materials.

  2. Enhanced reaction kinetics and impact strength of cyanate ester reinforced with multiwalled carbon nanotubes.

    PubMed

    Badrinarayanan, Prashanth; Leonard, Josh; Kessler, Michael R

    2011-05-01

    In this work, the effect of multiwalled carbon nanotubes on the properties of a unique, low viscosity bisphenol E cyanate ester (BECy) resin is characterized during various stages of nanocomposite preparation. The effect of surface functionalization, with nanotubes containing hydroxyl groups (OH CNTs) and carboxylic acid groups (COOH CNTs), on the rheological, cure, thermal, and impact properties of the nanocomposite properties are also examined. Based on rheology measurements prior to cure, the unfunctionalized nanotube suspensions are found to exhibit the highest viscosity and the most dramatic shear thinning behavior. Cure characterization using differential scanning calorimetry (DSC) reveals that the nanotubes catalyze the cure of BECy and the OH CNTs exhibiting the most dramatic catalytic effect. The DSC data is well described by an nth order autocatalytic model. The impact strength of fully cured BECy is found to increase by 91% and 63% upon incorporation of 1 wt% COOH and OH CNTs, respectively. While incorporation of 1 wt% unfunctionalized nanotubes results in an 8 degrees C decrease in the glass transition temperature (T(g)) of BECy, chemical functionalization greatly mitigates the magnitude of the reduction. PMID:21780394

  3. Adsorption of tetracycline from aqueous solutions onto multi-walled carbon nanotubes with different oxygen contents

    PubMed Central

    Yu, Fei; Ma, Jie; Han, Sheng

    2014-01-01

    Oxidized multi-walled carbon nanotubes (MWCNTs) with different oxygen contents were investigated for the adsorption of tetracycline (TC) from aqueous solutions. As the surface oxygen content of the MWCNTs increased, the maximum adsorption capacity and adsorption coefficient of TC increased to the largest values and then decreased. The relation can be attributed to the interplay between the nanotubes' dispersibility and the water cluster formation upon TC adsorption. The overall adsorption kinetics of TC onto CNTs-3.2%O might be dependent on both intra-particle diffusion and boundary layer diffusion. The maximum adsorption capacity of TC on CNTs-3.2%O was achieved in the pH range of 3.3–8.0 due to formation of water clusters or H-bonds. Furthermore, the presence of Cu2+ could significantly enhanced TC adsorption at pH of 5.0. However, the solution ionic strength did not exhibit remarkable effect on TC adsorption. In addition, when pH is beyond the range (3.3–8.0), the electrostatic interactions caused the decrease of TC adsorption capacity. Our results indicate that surface properties and aqueous solution chemistry play important roles in TC adsorption on MWCNTs. PMID:24937315

  4. Strengthening behavior of chopped multi-walled carbon nanotube reinforced aluminum matrix composites

    SciTech Connect

    Shin, S.E.; Bae, D.H.

    2013-09-15

    Strengthening behavior of the aluminum composites reinforced with chopped multi-walled carbon nanotubes (MWCNTs) or aluminum carbide formed during annealing at 500 °C has been investigated. The composites were fabricated by hot-rolling the powders which were ball-milled under various conditions. During the early annealing process, aluminum atoms can cluster inside the tube due to the diffusional flow of aluminum atoms into the tube, providing an increase of the strength of the composite. Further annealing induces the formation of the aluminum carbide phase, leading to an overall drop in the strength of the composites. While the strength of the composites can be evaluated according to the rule of mixture, a particle spacing effect can be additionally imparted on the strength of the composites reinforced with the chopped MWCNTs or the corresponding carbides since the reinforcing agents are smaller than the submicron matrix grains. - Highlights: • Strengthening behavior of chopped CNT reinforced Al-based composites is investigated. • Chopped CNTs have influenced the strength and microstructures of the composites. • Chopped CNTs are created under Ar- 3% H2 atmosphere during mechanical milling. • Strength can be evaluated by the rule of the mixture and a particle spacing effect.

  5. Polypiperazine-amide Nanofiltration Membrane Modified by Different Functionalized Multiwalled Carbon Nanotubes (MWCNTs).

    PubMed

    Xue, Shuang-Mei; Xu, Zhen-Liang; Tang, Yong-Jian; Ji, Chen-Hao

    2016-07-27

    In this work, three modified multiwalled carbon nanotubes (MWCNTs) with carboxyl (MWCNT-COOH), hydroxyl (MWCNT-OH) and amino groups (MWCNT-NH), respectively, were added into the aqueous phase containing piperazine (PIP) to fabricate the nanocomposite nanofiltration (NF) membranes via interfacial polymerization. The influences of functional groups of MWCNTs on the performance of modified NF membrane were investigated. The MWCNTs were characterized by TEM, FT-IR and TGA; meanwhile, the properties of the membranes were evaluated by XPS, TEM, AFM and contact angle. The XPS results proved the successful incorporation of MWCNT in the active layer of modified NF membrane. When the MWCNT concentration is 0.01% (w/v), all the nanocomposite membranes possessed the optimal separation properties, among which the membrane incorporated with MWCNT-OH demonstrated the highest water flux of 41.4 L·m(-2)·h(-1) and the Na2SO4 rejection of 97.6% whereas the one with MWCNT-COOH had the relative lowest rejection of 96.6%. Furthermore, the increased hydrophilicity of functional groups in modified MWCNTs resulted in different nodular surface morphologies, thicknesses and hydrophilicities of the nanocomposite membranes. All the membranes possessed a molecular weight cutoff (MWCO) within 300 Da and good operation stability. PMID:27387192

  6. "Green" functionalization of pristine multi-walled carbon nanotubes with long-chain aliphatic amines.

    PubMed

    Basiuk, Elena V; Ochoa-Olmos, Omar; Contreras-Torres, Flavio F; Meza-Laguna, Víctor; Alvarez-Zauco, Edgar; Puente-Lee, Iván; Basiuk, Vladimir A

    2011-06-01

    Short pristine multi-walled carbon nanotubes (MWNTs) were functionalized with a series of long-chain (including polymeric) aliphatic amines, namely octadecylamine (ODA), 1,8-diaminooctane (DO), polyethylene glycol diamine (PEGDA) and polyethylenimine (PEI), via two "green" approaches: (1) gas-phase functionalization (for volatile ODA and DO) and (2) direct heating in the melt (for polymeric PEGDA and PEI). Both of them consist in one-step reaction between MWNTs and amine without the use of organic solvents. The nanostructures obtained were characterized by using infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, atomic force microscopy, and transmission electron microscopy. It was observed that both solvent-free methods were efficient in the nanotube functionalization, and the nanostructures of variable solubility and morphology were obtained depending on the amines attached. ODA, PEGDA and PEI-functionalized MWNTs were found to be soluble in propanol, meanwhile the MWNTs-PEGDA and MWNTs-PEI were soluble in water as well. The attachment of 1,8-diaminooctane onto MWNTs resulted in cross-linked stable nanostructure. PMID:21770217

  7. Laccase immobilization over multi-walled carbon nanotubes: Kinetic, thermodynamic and stability studies.

    PubMed

    Tavares, Ana P M; Silva, Cláudia G; Dražić, Goran; Silva, Adrián M T; Loureiro, José M; Faria, Joaquim L

    2015-09-15

    The biocatalytic performance of immobilized enzyme systems depends mostly on the intrinsic properties of both biomolecule and support, immobilization technique and immobilization conditions. Multi-walled carbon nanotubes (MWCNTs) possess unique features for enzyme immobilization by adsorption. Enhanced catalytic activity and stability can be achieved by optimization of the immobilization conditions and by investigating the effect of operational parameters. Laccase was immobilized over MWCNTs by adsorption. The hybrid material was characterized by Fourier transformed infrared (FTIR) spectroscopy, scanning and transmission electron microscopy (SEM and TEM, respectively). The effect of different operational conditions (contact time, enzyme concentration and pH) on laccase immobilization was investigated. Optimized conditions were used for thermal stability, kinetic, and storage and operational stability studies. The optimal immobilization conditions for a laccase concentration of 3.75μL/mL were a pH of 9.0 and a contact time of 30min (522 Ulac/gcarrier). A decrease in the thermal stability of laccase was observed after immobilization. Changes in ΔS and ΔH of deactivation were found for the immobilized enzyme. The Michaelis-Menten kinetic constant was higher for laccase/MWCNT system than for free laccase. Immobilized laccase maintained (or even increased) its catalytic performance up to nine cycles of utilization and revealed long-term storage stability.

  8. Highly Conductive Aromatic Functionalized Multi-Walled Carbon Nanotube for Inkjet Printable High Performance Supercapacitor Electrodes

    PubMed Central

    Attri, Pankaj

    2015-01-01

    We report the functionalization of multiwalled carbon nanotubes (MWCNT) via the 1,3-dipolar [3+2] cycloaddition of aromatic azides, which resulted in a detangled CNT as shown by transmission electron microscopy (TEM). Carboxylic moieties (-COOH) on aromatic azide result in highly stable aqueous dispersion (max. conc. ~ 10 mg/mL H2O), making the suitable for inkjet printing. Printed patterns on polyethylene terephthalate (PET) flexible substrate exhibit low sheet resistivity ~65 Ω. cm, which is attributed to enhanced conductivity. Fabricated Supercapacitors (SC) assembled using these printed substrates exhibit good electrochemical performance in organic as well as aqueous electrolytes. High energy and power density (57.8 Wh/kg and 0.85 kW/kg) in 1M H2SO4 aqueous electrolyte demonstrate the excellent performance of the proposed supercapacitor. Capacitive retention varies from ~85–94% with columbic efficiency ~95% after 1000 charge/discharge cycles in different electrolytes, demonstrating the excellent potential of the device for futuristic power applications. PMID:26153688

  9. Hydrophilic modification of neural microelectrode arrays based on multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Chen, Chang-Hsiao; Su, Huan-Chieh; Chuang, Shih-Chang; Yen, Shiang-Jie; Chen, Yung-Chan; Lee, Yu-Tao; Chen, Hsin; Yew, Tri-Rung; Chang, Yen-Chung; Yeh, Shih-Rung; Yao, Da-Jeng

    2010-12-01

    To decrease the impedance of microelectrode arrays, for neuroscience applications we have fabricated and tested MEA based on multi-walled carbon nanotubes. With decreasing physical size of a microelectrode, its impedance increases and charge-transfer capability decreases. To decrease the impedance, the effective surface area of the electrode must generally be increased. We explored the effect of plasma treatment on the surface wettability of MWCNT. With a steam-plasma treatment the surface of MWCNT becomes converted from superhydrophobic to superhydrophilic; this hydrophilic property is attributed to -OH bonding on the surface of MWCNT. We reported the synthesis at 400 °C of MWCNT on nickel-titanium multilayered metal catalysts by thermal chemical vapor deposition. Applying plasma with a power less than 25 W for 10 s improved the electrochemical and biological properties, and circumvented the limitation of the surface reverting to a hydrophobic condition; a hydrophilic state is maintained for at least one month. The MEA was used to record neural signals of a lateral giant cell from an American crayfish. The response amplitude of the action potential was about 275 µV with 1 ms period; the recorded data had a ratio of signal to noise up to 40.12 dB. The improved performance of the electrode makes feasible the separation of neural signals and the recognition of their distinct shapes. With further development the rapid treatment will be useful for long-term recording applications.

  10. Anomalous electrical transport properties of polyvinyl alcohol-multiwall carbon nanotubes composites below room temperature

    NASA Astrophysics Data System (ADS)

    Chakraborty, G.; Gupta, K.; Meikap, A. K.; Babu, R.; Blau, W. J.

    2011-02-01

    The dc and ac electrical transport property of polyvinyl alcohol-multiwall carbon nanotubes composites has been investigated within a temperature range 77≤T≤300 K and in the frequency range 20 Hz-1 MHz in presence as well as in absence of a transverse magnetic field up to 1 T. The dc conductivity follows variable range hopping model. The magnetoconductivity of the samples changes a sign from positive to negative with an increase in temperature which can be interpreted by the dominancy of the quantum interference effect over the wave function shrinkage effect. The ac conductivity follows a power law whereas the temperature dependence of frequency exponent s can be explained by correlated barrier hopping model. The dielectric behavior of the samples has been governed by the grain and grain boundary resistance and capacitance. The ac conductivity reduces with the application of magnetic field. Although the theoretical model to explain it, is still lacking, we may conclude that this is due to the increase in grain and grain boundary resistance by the application of magnetic field.

  11. Development of functionalized multi-walled carbon-nanotube-based alginate hydrogels for enabling biomimetic technologies

    NASA Astrophysics Data System (ADS)

    Joddar, Binata; Garcia, Eduardo; Casas, Atzimba; Stewart, Calvin M.

    2016-08-01

    Alginate is a hydrogel commonly used for cell culture by ionically crosslinking in the presence of divalent Ca2+ ions. However these alginate gels are mechanically unstable, not permitting their use as scaffolds to engineer robust biological bone, breast, cardiac or tumor tissues. This issue can be addressed via encapsulation of multi-walled carbon nanotubes (MWCNT) serving as a reinforcing phase while being dispersed in a continuous phase of alginate. We hypothesized that adding functionalized MWCNT to alginate, would yield composite gels with distinctively different mechanical, physical and biological characteristics in comparison to alginate alone. Resultant MWCNT-alginate gels were porous, and showed significantly less degradation after 14 days compared to alginate alone. In vitro cell-studies showed enhanced HeLa cell adhesion and proliferation on the MWCNT-alginate compared to alginate. The extent of cell proliferation was greater when cultured atop 1 and 3 mg/ml MWCNT-alginate; although all MWCNT-alginates lead to enhanced cell cluster formation compared to alginate alone. Among all the MWCNT-alginates, the 1 mg/ml gels showed significantly greater stiffness compared to all other cases. These results provide an important basis for the development of the MWCNT-alginates as novel substrates for cell culture applications, cell therapy and tissue engineering.

  12. Characterization of multiwalled carbon nanotube-reinforced hydroxyapatite composites consolidated by spark plasma sintering.

    PubMed

    Kim, Duk-Yeon; Han, Young-Hwan; Lee, Jun Hee; Kang, Inn-Kyu; Jang, Byung-Koog; Kim, Sukyoung

    2014-01-01

    Pure HA and 1, 3, 5, and 10 vol% multiwalled carbon nanotube- (MWNT-) reinforced hydroxyapatite (HA) were consolidated using a spark plasma sintering (SPS) technique. The relative density of pure HA increased with increasing sintering temperature, but that of the MWNT/HA composite reached almost full density at 900°C, and then decreased with further increases in sintering temperature. The relative density of the MWNT/HA composites increased with increasing MWNT content due to the excellent thermal conductivity of MWNTs. The grain size of MWNT/HA composites decreased with increasing MWNT content and increased with increasing sintering temperature. Pull-out toughening of the MWNTs of the MWNT/HA composites was observed in the fractured surface, which can be used to predict the improvement of the mechanical properties. On the other hand, the existence of undispersed or agglomerate MWNTs in the MWNT/HA composites accompanied large pores. The formation of large pores increased with increasing sintering temperature and MWNT content. The addition of MWNT in HA increased the hardness and fracture toughness by approximately 3~4 times, despite the presence of large pores produced by un-dispersed MWNTs. This provides strong evidence as to why the MWNTs are good candidates as reinforcements for strengthening the ceramic matrix. The MWNT/HA composites did not decompose during SPS sintering. The MWNT-reinforced HA composites were non-toxic and showed a good cell affinity and morphology in vitro for 1 day.

  13. Temperature-Compensated Force/Pressure Sensor Based on Multi-Walled Carbon Nanotube Epoxy Composites

    PubMed Central

    Dinh, Nghia Trong; Kanoun, Olfa

    2015-01-01

    In this study, we propose a multi-walled carbon nanotube epoxy composite sensor for force and pressure sensing in the range of 50 N–2 kN. A manufacturing procedure, including material preparation and deposition techniques, is proposed. The electrode dimensions and the layer thickness were optimized by the finite element method. Temperature compensation is realized by four nanocomposites elements, where only two elements are exposed to the measurand. In order to investigate the influence of the filler contents, samples with different compositions were prepared and investigated. Additionally, the specimens are characterized by cyclical and stepped force/pressure loads or at defined temperatures. The results show that the choice of the filler content should meet a compromise between sensitivity, temperature influence and noise behavior. At constant temperature, a force of at least 50 N can be resolved. The measurement error due to the temperature influence is 150 N in a temperature range of −20°C−50°C. PMID:25985160

  14. Effects of multiwall carbon nanotubes on viscoelastic properties of magnetorheological elastomers

    NASA Astrophysics Data System (ADS)

    Aziz, Siti Aishah Abdul; Amri Mazlan, Saiful; Intan Nik Ismail, Nik; Ubaidillah, U.; Choi, Seung-Bok; Khairi, Muntaz Hana Ahmad; Azhani Yunus, Nurul

    2016-07-01

    The effect of different types of multiwall carbon nanotubes (MWCNTs) on the morphological, magnetic and viscoelastic properties of magnetorheological elastomers (MREs) are studied in this work. A series of natural rubber MRE are prepared by adding MWCNTs as a new additive in MRE. Effects of functionalized MWCNT namely carboxylated MWCNT (COOH-MWCNT) and hydroxylated MWCNT (OH-MWCNT) on the rheological properties of MREs are investigated and the pristine MWCNTs is referred as a control. Epoxidised palm oil (EPO) is used as a medium to disperse carbonyl iron particle (CIP) and sonicate the MWCNTs. Morphological and magnetic properties of MREs are characterized by field emission scanning electron microscopy (FESEM) and vibrating sample magnetometer (VSM), respectively. Rheological properties under different magnetic field are evaluated by using parallel plate rheometer. From the results obtained, FESEM images indicate that COOH-MWCNT and CIP have better compatibility which leads to the formation of interconnected network in the matrix. In addition, by adding functionalized COOH-MWCNT, it is shown that the saturation magnetization is 5% higher than the pristine MWCNTs. It is also found that with the addition of COOH-MWCNT, the magnetic properties are improved parallel with enhancement of MR effect particularly at low strain amplitude. It is finally shown that the use of EPO also can contribute to the enhancement of MR performance.

  15. A facile approach for imprinting protein on the surface of multi-walled carbon nanotubes.

    PubMed

    Liu, Ren; Sha, Mo; Jiang, Sisi; Luo, Jing; Liu, Xiaoya

    2014-03-01

    This study describes a green, facile and low cost approach for imprinting protein on the surface of multi-walled carbon nanotubes (MWNTs) using papain as the template, dopamine as the functional monomer. By simply mixing MWNTs, dopamine, template protein in weak alkaline aqueous solution, a thin adherent polydopamine (PDA) film imprinted with protein was spontaneously obtained on the surface of MWNTs to produce the imprinted nanomaterials (MWNTs@MIPs). The obtained MWNTs@MIPs were characterized with Fourier transform infrared spectrometer (FT-IR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The adsorption process of the MWNTs@MIPs towards template protein was investigated in detail. The effects of the concentration of the monomer and template, polymerization time, extraction process were optimized. The prepared MWNTs@MIPs show fast binding kinetics, high binding capacity and acceptable specific recognition behavior towards template proteins. Furthermore, the stability and regeneration were also investigated, which indicated that the MWNTs@MIPs had good reusability. The good recognizing behavior coupled to the low cost and facile one-step preparation make the MWNTs@MIPs attractive for separation and specific protein recognition.

  16. Multi-Walled Carbon Nanotube-Doped Tungsten Oxide Thin Films for Hydrogen Gas Sensing

    PubMed Central

    Wongchoosuk, Chatchawal; Wisitsoraat, Anurat; Phokharatkul, Ditsayut; Tuantranont, Adisorn; Kerdcharoen, Teerakiat

    2010-01-01

    In this work we have fabricated hydrogen gas sensors based on undoped and 1 wt% multi-walled carbon nanotube (MWCNT)-doped tungsten oxide (WO3) thin films by means of the powder mixing and electron beam (E-beam) evaporation technique. Hydrogen sensing properties of the thin films have been investigated at different operating temperatures and gas concentrations ranging from 100 ppm to 50,000 ppm. The results indicate that the MWCNT-doped WO3 thin film exhibits high sensitivity and selectivity to hydrogen. Thus, MWCNT doping based on E-beam co-evaporation was shown to be an effective means of preparing hydrogen gas sensors with enhanced sensing and reduced operating temperatures. Creation of nanochannels and formation of p-n heterojunctions were proposed as the sensing mechanism underlying the enhanced hydrogen sensitivity of this hybridized gas sensor. To our best knowledge, this is the first report on a MWCNT-doped WO3 hydrogen sensor prepared by the E-beam method. PMID:22163623

  17. Suspending multi-walled carbon nanotubes by humic acids from a peat soil.

    PubMed

    Zhou, Xinzhe; Shu, Liang; Zhao, Huibin; Guo, Xiaoying; Wang, Xilong; Tao, Shu; Xing, Baoshan

    2012-04-01

    Suspension of the pristine and COOH-substituted multi-walled carbon nanotubes (P- and C-MWCNTs) with different outer diameters (ODs) by humic acids (HAs) from a peat soil was examined. Under shaking condition, MWCNTs were not suspended within 5 d. Without HAs, C-MWCNTs were slightly suspended by sonication within 16 h, but no suspension was observed for the pristine ones (P-MWCNTs). HAs greatly enhanced suspension of both P- and C-MWCNTs. The suspension enhancement was attributed to HA sorption, which increased electrostatic repulsion and steric hindrance between individual MWCNTs. Introduction of O-containing hydrophilic moieties to MWCNTs via HA sorption enhanced the interactions of their surfaces with water through H-bonding. Suspending capability of various MWCNTs on suspended mass concentration basis by four HAs showed inconsistent orders with the increasing or decreasing trend of their ODs. However, the suspended surface area concentrations of both P- and C-MWCNTs by individual HAs consistently followed an order of P8 > P30 > P50, and C8 > C30 > C50 (P and C, respectively, refer to P- and C-MWCNTs, and the numbers represent their ODs). These data implied that MWCNTs with smaller OD could be more strongly suspended by a given HA relative to those with larger OD under sonication condition.

  18. Preparation and characterization of bagasse/HDPE composites using multi-walled carbon nanotubes.

    PubMed

    Ashori, Alireza; Sheshmani, Shabnam; Farhani, Foad

    2013-01-30

    This article presents the preparation and characterization of bagasse/high density polyethylene (HDPE) composites. The effects of multi-walled carbon nanotubes (MWCNTs), as reinforcing agent, on the mechanical and physical properties were also investigated. In order to increase the interphase adhesion, maleic anhydride grafted polyethylene (MAPE) was added as a coupling agent to all the composites studied. In the sample preparation, MWCNTs and MAPE contents were used as variable factors. The morphology of the specimens was characterized using scanning electron microscopy (SEM) technique. The results of strength measurement indicated that when 1.5 wt% MWCNTs were added, tensile and flexural properties reached their maximum values. At high level of MWCNTs loading (3 or 4 wt%), increased population of MWCNTs lead to agglomeration and stress transfer gets blocked. The addition of MWCNTs filler slightly decreased the impact strength of composites. Both mechanical and physical properties were improved when 4 wt% MAPE was applied. SEM micrographs also showed that the surface roughness improved with increasing MAPE loading from 0 to 4 wt%. The improvement of physicomechanical properties of composites confirmed that MWCNTs have good reinforcement and the optimum synergistic effect of MWCNTs and MAPE was achieved at the combination of 1.5 and 4 wt%, respectively.

  19. Poly(N-isopropylacrylamide) hydrogels with interpenetrating multiwalled carbon nanotubes for cell sheet engineering.

    PubMed

    Chen, Yu-Shuan; Tsou, Pei-Chun; Lo, Jem-Mau; Tsai, Hsieh-Chih; Wang, Yan-Zhen; Hsiue, Ging-Ho

    2013-10-01

    Hydrogels have been developed as artificial extracellular matrixes (ECMs) to mimic native tissue microenvironments for various applications. Unfortunately, poly(N-isopropylacrylamide) (PNIPAAM)-based hydrogels are not suitable for cell culturing and cell sheet preparation. Carbon nanotubes (CNTs), with their mechanical strength and electrical conductivity, have been considered as additives to increase the applicability of hydrogels to cell encapsulation and advance cardiac electrophysiological functions. A simple method for fabrication of PNIPAAM hydrogels interpenetrated with multiwalled CNTs (MWCNTs) as substrates for cell sheet preparation is reported. The results demonstrate that PNIPAAM hydrogels with interpenetrating MWCNTs still exhibit thermosensitive behavior. It is also found that epithelial Madin-Darby canine kidney (MDCK) cells can only attach and proliferate on MWCNT-interpenetrated PNIPAAM hydrogels. Furthermore, the PNIPAAM hydrogels with MWCNTs possess higher elastic moduli and hydrophobicities than those without MWCNTs, suggesting these two characteristics are necessary for the cells to attach to the hydrogel surfaces. Moreover, cell sheets can only be harvested from PNIPAAM hydrogels with MWCNTs because of their high ratio of cell attachment. Thus, this simple method provides sufficient mechanical strength to PNIPAAM hydrogels so that anchorage-dependent cells can be cultivated and provides a superior system for preparing cell sheets.

  20. Detection of organophosphorous pesticides in soil samples with multiwalled carbon nanotubes coating SPME fiber.

    PubMed

    Feng, Xilan; Li, Ying; Jing, Ruijun; Jiang, Xiaoying; Tian, Mengkui

    2014-12-01

    A headspace solid phase microextraction (HS-SPME) technique using stainless steel fiber coated with 20 μm multi-walled carbon nanotubes (MWCNTs) and gas chromatography with thermionic specific detector (GC-TSD) was developed to determine organophosphorous pesticides (OPPs) in soil. Parameters affecting the extraction efficiency such as extraction time and temperature, ionic strength, the volume of water added to the soil, sample solution volume to headspace volume ratio, desorption time, and desorption temperature were investigated and optimized. Compared to commercial polydimethylsiloxane (PDMS, 7 μm) fiber, the PDMS fiber was better to be corrected as phorate, whereas the MWCNTs fiber gave slightly better results for methyl parathion, chlorpyrifos and parathion. The optimized SPME method was applied to analyze OPPs in spiked soil samples. The limits of detection (LODs, S/N = 3) for the four pesticides were <0.216 ng g(-1), and their calibration curves were all linear (r (2) ≥ 0.9908) in the range from 1 to 200 ng g(-1). The precision (RSD, n = 6) for peak areas was 6.5 %-8.8 %. The recovery of the OPPs spiked real soil samples at 50 and 150 ng g(-1) ranged from 89.7 % to 102.9 % and 94.3 % to 118.1 %, respectively.

  1. Oxidized multiwalled carbon nanotubes as adsorbent for the removal of manganese from aqueous solution.

    PubMed

    Ganesan, Pandian; Kamaraj, Ramakrishnan; Sozhan, Ganapathy; Vasudevan, Subramanyan

    2013-02-01

    A batch adsorption process was applied to investigate the removal of manganese from aqueous solution by oxidized multiwalled carbon nanotubes (MWCNTs). In doing so, the thermodynamic, adsorption isotherm, and kinetic studies were also carried out. MWCNT with 5-10-nm outer diameter, surface area of 40-600 m(2)/g, and purity above 95 % was used as an adsorbent. A systematic study of the adsorption process was performed by varying pH, ionic strength, and temperature. Manganese-adsorbed MWCNT was characterized by Raman, FTIR, X-ray diffraction, XPS, SEM, and TEM. The adsorption efficiency could reach 96.82 %, suggesting that MWCNT is an excellent adsorbent for manganese removal from water. The results indicate that second-order kinetics model was well suitable to model the kinetic adsorption of manganese. Equilibrium data were well described by the typical Langmuir adsorption isotherm. Thermodynamic studies revealed that the adsorption reaction was spontaneous and endothermic process. The experimental results showed that MWCNT is an excellent manganese adsorbent. The MWCNTs removed the manganese present in the water and reduced it to a permissible level making it drinkable.

  2. Reinforcing Effects of Poly(D-Lactide)-g-Multiwall Carbon Nanotubes on Polylactide Nanocomposites.

    PubMed

    Yang, Jeong Hee; Lee, Jae Yun; Chin, In-Joo

    2015-10-01

    Polylactide (PLA) nanocomposites with multi-walled carbon nanotubes (MWNTs) grafted with poly(L-lactide) or poly(D-lactide) were prepared by solution casting, and their thermal and mechanical properties were evaluated. MWNTs containing hydroxyl groups were treated by ring-opening polymerization of either L-lactide or D-lactide. Fourier transform infrared spectroscopy confirmed that the MWNT surfaces had been modified by the PLLA or PDLA chains. The thermal properties were measured by differential scanning calorimetry and thermogravimetric analysis. The mechanical properties were examined using a universal testing machine. The morphology of the fractured surfaces of the PLA nanocomposites was observed by scanning electron microscopy and transmission electron microscopy. PDLA-g-MWNTs were dispersed more uniformly compared to PLLA-g-MWNTs in the PLA matrix. The incorporation of PDLA-g-MWNTs greatly improved the tensile strength of the nanocomposites regardless of the contents. Thermal analysis revealed different characteristics at specific composites depending on the type of modification.

  3. Electromechanical Behavior of Chemically Reduced Graphene Oxide and Multi-walled Carbon Nanotube Hybrid Material

    NASA Astrophysics Data System (ADS)

    Benchirouf, Abderrahmane; Müller, Christian; Kanoun, Olfa

    2016-01-01

    In this paper, we propose strain-sensitive thin films based on chemically reduced graphene oxide (GO) and multi-walled carbon nanotubes (MWCNTs) without adding any further surfactants. In spite of the insulating properties of the thin-film-based GO due to the presence functional groups such as hydroxyl, epoxy, and carbonyl groups in its atomic structure, a significant enhancement of the film conductivity was reached by chemical reduction with hydro-iodic acid. By optimizing the MWCNT content, a significant improvement of electrical and mechanical thin film sensitivity is realized. The optical properties and the morphology of the prepared thin films were studied using ultraviolet-visible spectroscopy (UV-Vis) and scanning electron microscope (SEM). The UV-Vis spectra showed the ability to tune the band gap of the GO by changing the MWCNT content, whereas the SEM indicated that the MWCNTs were well dissolved and coated by the GO. Investigations of the piezoresistive properties of the hybrid nanocomposite material under mechanical load show a linear trend between the electrical resistance and the applied strain. A relatively high gauge factor of 8.5 is reached compared to the commercial metallic strain gauges. The self-assembled hybrid films exhibit outstanding properties in electric conductivity, mechanical strength, and strain sensitivity, which provide a high potential for use in strain-sensing applications.

  4. Development of functionalized multi-walled carbon-nanotube-based alginate hydrogels for enabling biomimetic technologies

    PubMed Central

    Joddar, Binata; Garcia, Eduardo; Casas, Atzimba; Stewart, Calvin M.

    2016-01-01

    Alginate is a hydrogel commonly used for cell culture by ionically crosslinking in the presence of divalent Ca2+ ions. However these alginate gels are mechanically unstable, not permitting their use as scaffolds to engineer robust biological bone, breast, cardiac or tumor tissues. This issue can be addressed via encapsulation of multi-walled carbon nanotubes (MWCNT) serving as a reinforcing phase while being dispersed in a continuous phase of alginate. We hypothesized that adding functionalized MWCNT to alginate, would yield composite gels with distinctively different mechanical, physical and biological characteristics in comparison to alginate alone. Resultant MWCNT-alginate gels were porous, and showed significantly less degradation after 14 days compared to alginate alone. In vitro cell-studies showed enhanced HeLa cell adhesion and proliferation on the MWCNT-alginate compared to alginate. The extent of cell proliferation was greater when cultured atop 1 and 3 mg/ml MWCNT-alginate; although all MWCNT-alginates lead to enhanced cell cluster formation compared to alginate alone. Among all the MWCNT-alginates, the 1 mg/ml gels showed significantly greater stiffness compared to all other cases. These results provide an important basis for the development of the MWCNT-alginates as novel substrates for cell culture applications, cell therapy and tissue engineering. PMID:27578567

  5. Polybenzimidazole-multiwall carbon nanotubes composite membranes for polymer electrolyte membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Guerrero Moreno, Nayibe; Gervasio, Dominic; Godínez García, Andrés; Pérez Robles, Juan Francisco

    2015-12-01

    Polymer membranes are prepared as a composite of polybenzimidazole and non-functionalized multiwall carbon nanotubes (PBI-CNT) and polybenzimidazole (PBI) only. Each is doped with H3PO4 (PA) and used as a proton exchange membrane (PEM) as the electrolyte in a fuel cell. The proton conductivities at 180 °C for the doped PBI membrane (PBIPA) and the doped PBI-CNT membrane (PBICNTPA) are 6.3 × 10-2 and 7.4 × 10-2 Scm-1 respectively. A single fuel cell having these membranes as electrolyte has a Pt catalyzed hydrogen gas fed anode and a similar oxygen cathode without humidification of feed gases; the cell with the PBICNTPA membrane has higher open circuit voltage (0.96 V) than that with a PBIPA membrane (0.8 V) at 180 °C. The mechanical stability of the membrane improves with CNTs addition. The tensile strength of the composite PBI-CNT membrane with 1 wt.% CNTs loading is 32% higher and the Young's Modulus is 147% higher than the values for a membrane of PBI alone. The improvement in conductivity and mechanical properties in the composite membrane due to the CNT addition indicates that a PBI-CNT membrane is a good alternative as a membrane electrolyte in a PEMFC.

  6. Fabrication of free-standing aligned multiwalled carbon nanotube array for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Bulusheva, L. G.; Arkhipov, V. E.; Fedorovskaya, E. O.; Zhang, Su; Kurenya, A. G.; Kanygin, M. A.; Asanov, I. P.; Tsygankova, A. R.; Chen, Xiaohong; Song, Huaihe; Okotrub, A. V.

    2016-04-01

    We show that a high-temperature CCl4 vapor treatment of vertically aligned multiwalled carbon nanotubes (VA-MWCNTs) grown on silicon substrate allows carefully detach the array from the substrate. Moreover, this procedure partially purifies the VA-MWCNTs from the residual iron catalyst. To improve electrical connectivity of free-standing VA-MWCNTs in an electrochemical cell, the array was placed between the layers of Ni foam. Such assembly demonstrated the better performance in Li-battery as compared to the disordered MWCNTs. After 50 cycles, the specific capacity of VA-MWCNT array synthesized from 0.5 wt% ferrocene solution in toluene was 350 mAh g-1 at a current density of 0.1 A g-1, while the battery with the disordered MWCNTs achieved 197 mAh g-1 only. By the results of electrochemical impedance spectroscopy, the higher capacity of VA-MWCNTs was attributed to larger surface area available for electrolyte and Li ions due to the absence of binder coating.

  7. Enhanced field emission from lanthanum hexaboride coated multiwalled carbon nanotubes: Correlation with physical properties

    NASA Astrophysics Data System (ADS)

    Patra, Rajkumar; Ghosh, S.; Sheremet, E.; Jha, Menaka; Rodriguez, R. D.; Lehmann, D.; Ganguli, A. K.; Schmidt, H.; Schulze, S.; Hietschold, M.; Zahn, D. R. T.; Schmidt, O. G.

    2014-10-01

    Detailed results from field emission studies of lanthanum hexaboride (LaB6) coated multiwalled carbon nanotube (MWCNT) films, pristine LaB6 films, and pristine MWCNT films are reported. The films have been synthesized by a combination of chemical and physical deposition processes. An impressive increase in field enhancement factor and temporal stability as well as a reduction in turn-on field and threshold field are observed in LaB6-coated MWCNTs compared to pristine MWCNT and pristine LaB6 films. Surface morphology of the films has been examined by scanning electron microscopy. Introduction of LaB6 nanoparticles on the outer walls of CNTs LaB6-coated MWCNTs films is confirmed by transmission electron microscopy. The presence of LaB6 was confirmed by X-ray photoelectron spectroscopy results and further validated by the Raman spectra. Raman spectroscopy also shows 67% increase in defect concentration in MWCNTs upon coating with LaB6 and an upshift in the 2D band that could be attributed to p-type doping. Ultraviolet photoelectron spectroscopy studies reveal a reduction in the work function of LaB6-coated MWCNT with respect to its pristine counterpart. The enhanced field emission properties in LaB6-coated MWCNT films are correlated with a change in microstructure and work function.

  8. Vascular effects of multiwalled carbon nanotubes in dyslipidemic ApoE-/- mice and cultured endothelial cells.

    PubMed

    Cao, Yi; Jacobsen, Nicklas Raun; Danielsen, Pernille Høgh; Lenz, Anke G; Stoeger, Tobias; Loft, Steffen; Wallin, Håkan; Roursgaard, Martin; Mikkelsen, Lone; Møller, Peter

    2014-03-01

    Accumulating evidences indicate that pulmonary exposure to carbon nanotubes (CNTs) is associated with increased risk of lung diseases, whereas the effect on the vascular system is less studied. We investigated vascular effects of 2 types of multiwalled CNTs (MWCNTs) in apolipoprotein E(-/-) mice, wild-type mice, and cultured cells. The ApoE(-/-) mice had accelerated plaque progression in aorta after 5 intracheal instillations of MWCNT (25.6 μg/mouse weekly for 5 weeks). The exposure was associated with pulmonary inflammation, lipid peroxidation, and increased expression of inflammatory, oxidative stress, DNA repair, and vascular activation response genes. The level of oxidatively damaged DNA in lung tissue was unaltered, probably due to increased DNA repair capacities. Despite upregulation of inflammatory genes in the liver, effects on systemic cytokines and lipid peroxidation were minimal. The exposure to MWCNTs in cultured human endothelial cells increased the expression of cell adhesion molecules (ICAM1 and VCAM1). In cocultures, there was increased adhesion of monocytes to endothelial cells after exposure to MWCNT. The exposure to both types of MWCNT was also associated with increased lipid accumulation in monocytic-derived foam cells, which was dependent on concomitant oxidative stress because the antioxidant N-acetylcysteine inhibited the lipid accumulation. Collectively, our results indicate that exposure to MWCNT is associated with accelerated progression of atherosclerosis, which could be related to both increased adherence of monocytes onto the endothelium and oxidative stress-mediated transformation of monocytes to foam cells.

  9. Multiwalled Carbon Nanotube/nanofiber Arrays as Conductive and Dry Adhesive Interface Materials

    NASA Technical Reports Server (NTRS)

    Tong, Tao; Zhao, Yang; Delzeit, Lance; Majumdar, Arun; Kashani, Ali

    2004-01-01

    We demonstrate the possibility of making conductive and dry adhesive interfaces between multiwalled carbon nanotube (MWNT) and nanofiber (MWNF) arrays grown by chemical vapor deposition with transition-metal as catalyst on highly Boron doped silicon substrates. The maximum observed adhesion force between MWNT and MWNF surfaces is 3.5 mN for an apparent contact area of 2 mm by 4 mm. The minimum contact resistance measured at the same time is approx.20 Omega. Contact resistances of MWNT-MWNT and MWNT-gold interfaces were also measured as pressure forces around several mN were applied at the interface. The resulting minimum contact resistances are on the same order but with considerable variation from sample to sample. For MWNT-MWNT contacts, a minimum contact resistance of approx.1 Omega is observed for a contact area of 2 mm by 1 mm. The relatively high contact resistances, considering the area density of the nanotubes, might be explained by the high cross-tube resistances at the contact interfaces.

  10. Enhanced field emission from lanthanum hexaboride coated multiwalled carbon nanotubes: Correlation with physical properties

    SciTech Connect

    Patra, Rajkumar; Ghosh, S.; Sheremet, E.; Rodriguez, R. D.; Lehmann, D.; Zahn, D. R. T.; Jha, Menaka; Ganguli, A. K.; Schmidt, H.; Schulze, S.; Hietschold, M.; Schmidt, O. G.

    2014-10-28

    Detailed results from field emission studies of lanthanum hexaboride (LaB{sub 6}) coated multiwalled carbon nanotube (MWCNT) films, pristine LaB{sub 6} films, and pristine MWCNT films are reported. The films have been synthesized by a combination of chemical and physical deposition processes. An impressive increase in field enhancement factor and temporal stability as well as a reduction in turn-on field and threshold field are observed in LaB{sub 6}-coated MWCNTs compared to pristine MWCNT and pristine LaB{sub 6} films. Surface morphology of the films has been examined by scanning electron microscopy. Introduction of LaB{sub 6} nanoparticles on the outer walls of CNTs LaB{sub 6}-coated MWCNTs films is confirmed by transmission electron microscopy. The presence of LaB{sub 6} was confirmed by X-ray photoelectron spectroscopy results and further validated by the Raman spectra. Raman spectroscopy also shows 67% increase in defect concentration in MWCNTs upon coating with LaB{sub 6} and an upshift in the 2D band that could be attributed to p-type doping. Ultraviolet photoelectron spectroscopy studies reveal a reduction in the work function of LaB{sub 6}-coated MWCNT with respect to its pristine counterpart. The enhanced field emission properties in LaB{sub 6}-coated MWCNT films are correlated with a change in microstructure and work function.

  11. Mode I Fracture Toughness Prediction for Multiwalled-Carbon-Nanotube Reinforced Ceramics

    SciTech Connect

    Nguyen, Ba Nghiep; Henager, Charles H.

    2015-08-27

    This article develops a multiscale model to predict fracture toughness of multiwalled-carbon-nanotube (MWCNT) reinforced ceramics. The model bridges different scales from the scale of a MWCNT to that of a composite domain containing a macroscopic crack. From the nano, micro to meso scales, Eshelby-Mori-Tanaka models combined with a continuum damage mechanics approach are explored to predict the elastic damage behavior of the composite as a function of MWCNT volume fraction. MWCNTs are assumed to be randomly dispersed in a ceramic matrix subject to cracking under loading. A damage variable is used to describe matrix cracking that causes reduction of the elastic modulus of the matrix. This damage model is introduced in a modified boundary layer modeling approach to capture damage initiation and development at a tip of a pre-existing crack. Damage and fracture are captured only in a process window containing the crack tip under plane strain Mode I loading. The model is validated against the published experimental fracture toughness data for a MWCNT 3 mol% yttria stabilized zirconia composite system. In addition, crack resistance curves as a function of MWCNT content are predicted and fitted by a power law as observed in the experiments on zirconia.

  12. Hyaluronic acid-modified multiwalled carbon nanotubes for targeted delivery of doxorubicin into cancer cells.

    PubMed

    Cao, Xueyan; Tao, Lei; Wen, Shihui; Hou, Wenxiu; Shi, Xiangyang

    2015-03-20

    Development of novel drug carriers for targeted cancer therapy with high efficiency and specificity is of paramount importance and has been one of the major topics in current nanomedicine. Here we report a general approach to using multifunctional multiwalled carbon nanotubes (MWCNTs) as a platform to encapsulate an anticancer drug doxorubicin (DOX) for targeted cancer therapy. In this approach, polyethyleneimine (PEI)-modified MWCNTs were covalently conjugated with fluorescein isothiocyanate (FI) and hyaluronic acid (HA). The formed MWCNT/PEI-FI-HA conjugates were characterized via different techniques and were used as a new carrier system to encapsulate the anticancer drug doxorubicin for targeted delivery to cancer cells overexpressing CD44 receptors. We show that the formed MWCNT/PEI-FI-HA/DOX complexes with a drug loading percentage of 72% are water soluble and stable. In vitro release studies show that the drug release rate under an acidic condition (pH 5.8, tumor cell microenvironment) is higher than that under physiological condition (pH 7.4). Cell viability assay demonstrates that the carrier material has good biocompatibility in the tested concentration range, and the MWCNT/PEI-FI-HA/DOX complexes can specifically target cancer cells overexpressing CD44 receptors and exert growth inhibition effect to the cancer cells. The developed HA-modified MWCNTs hold a great promise to be used as an efficient anticancer drug carrier for tumor-targeted chemotherapy.

  13. Ultrasensitive, Label Free, Chemiresistive Nanobiosensor Using Multiwalled Carbon Nanotubes Embedded Electrospun SU-8 Nanofibers

    PubMed Central

    Durga Prakash, Matta; Vanjari, Siva Rama Krishna; Sharma, Chandra Shekhar; Singh, Shiv Govind

    2016-01-01

    This paper reports the synthesis and fabrication of aligned electrospun nanofibers derived out of multiwalled carbon nanotubes (MWCNTs) embedded SU-8 photoresist, which are targeted towards ultrasensitive biosensor applications. The ultrasensitivity (detection in the range of fg/mL) and the specificity of these biosensors were achieved by complementing the inherent advantages of MWCNTs such as high surface to volume ratio and excellent electrical and transduction properties with the ease of surface functionalization of SU-8. The electrospinning process was optimized to precisely align nanofibers in between two electrodes of a copper microelectrode array. MWCNTs not only enhance the conductivity of SU-8 nanofibers but also act as transduction elements. In this paper, MWCNTs were embedded way beyond the percolation threshold and the optimum percentage loading of MWCNTs for maximizing the conductivity of nanofibers was figured out experimentally. As a proof of concept, the detection of myoglobin, an important biomarker for on-set of Acute Myocardial Infection (AMI) has been demonstrated by functionalizing the nanofibers with anti-myoglobin antibodies and carrying out detection using a chemiresistive method. This simple and robust device yielded a detection limit of 6 fg/mL. PMID:27563905

  14. Multiwalled carbon nanotube dispersion methods affect their aggregation, deposition, and biomarker response.

    PubMed

    Chang, Xiaojun; Henderson, W Matthew; Bouchard, Dermont C

    2015-06-01

    To systematically evaluate how dispersion methods affect the environmental behaviors of multiwalled carbon nanotubes (MWNTs), MWNTs were dispersed in various solutions (e.g., surfactants, natural organic matter (NOM), and etc.) via ultrasonication (SON) and long-term stirring (LT). The two tested surfactants [anionic sodium dodecyl sulfate (SDS) and nonionic poly(ethylene glycol)-poly(propylene glycol)-poly(ethylene glycol) (PEO-PPO-PEO) triblock copolymers (Pluronic)] could only disperse MWNTs via ultrasonication; while stable aqueous SON/MWNT and LT/MWNT suspensions were formed in the presence of the two model NOMs (Suwannee river humic acid and fulvic acid). Due to the inherent stochastic nature for both methods, the formed MWNT suspensions were highly heterogeneous. Their physicochemical properties, including surface charge, size, and morphology, greatly depended upon the dispersant type and concentration but were not very sensitive to the preparation methods. Aggregation and deposition behaviors of the dispersed MWNTs were controlled by van der Waal and electrostatic forces, as well as other non-DLVO forces (e.g., steric, hydrophobic forces, etc.). Unlike the preparation method-independent physicochemical properties, LT/NOM-MWNTs and SON/NOM-MWNTs differed in their fathead minnow epithelial cell metabolomics profiles.

  15. Pressureless sintering and mechanical properties of hydroxyapatite/functionalized multi-walled carbon nanotube composite.

    PubMed

    Abden, M J; Afroze, J D; Alam, M S; Bahadur, N M

    2016-10-01

    This work aims to study the optimum sintering conditions of hydroxyapatite/functionalized multi-walled carbon nanotube (HA/f-MWCNT) composite with improved mechanical properties for bone implant applications using a pressureless sintering technique. The carboxyl functional group (COOH) introduced by the acid treatment on the MWCNT surface by which HA molecules are grafted onto the surface of functionalized MWCNT with strong interfacial bonding. The composite exhibits a lower hemolytic rate of 1.27%. The flexible nature of f-MWCNT makes them bend and attached to the HA grains, indicates that f-MWCNT bear significant stress by sharing a portion of the load and it leads to improve their mechanical properties. The maximum Vickers hardness of 3.6GPa is obtained for the HA/f-MWCNT composite sintered at 1100°C, whereas the highest compressive strength of 481.7MPa and fracture toughness of 2.38MPa.m(1/2) achieved after sintering at 1150°C. This study demonstrated that HA/f-MWCNT composite create suitable structures by vacuum pressureless sintering technique to satisfy the mechanical requirements for bone tissues.

  16. Development of functionalized multi-walled carbon-nanotube-based alginate hydrogels for enabling biomimetic technologies.

    PubMed

    Joddar, Binata; Garcia, Eduardo; Casas, Atzimba; Stewart, Calvin M

    2016-01-01

    Alginate is a hydrogel commonly used for cell culture by ionically crosslinking in the presence of divalent Ca(2+) ions. However these alginate gels are mechanically unstable, not permitting their use as scaffolds to engineer robust biological bone, breast, cardiac or tumor tissues. This issue can be addressed via encapsulation of multi-walled carbon nanotubes (MWCNT) serving as a reinforcing phase while being dispersed in a continuous phase of alginate. We hypothesized that adding functionalized MWCNT to alginate, would yield composite gels with distinctively different mechanical, physical and biological characteristics in comparison to alginate alone. Resultant MWCNT-alginate gels were porous, and showed significantly less degradation after 14 days compared to alginate alone. In vitro cell-studies showed enhanced HeLa cell adhesion and proliferation on the MWCNT-alginate compared to alginate. The extent of cell proliferation was greater when cultured atop 1 and 3 mg/ml MWCNT-alginate; although all MWCNT-alginates lead to enhanced cell cluster formation compared to alginate alone. Among all the MWCNT-alginates, the 1 mg/ml gels showed significantly greater stiffness compared to all other cases. These results provide an important basis for the development of the MWCNT-alginates as novel substrates for cell culture applications, cell therapy and tissue engineering. PMID:27578567

  17. Transport and remobilization of multi-walled carbon nanotubes in porous media during dynamic saturation change

    NASA Astrophysics Data System (ADS)

    Sharma, P.

    2012-04-01

    Nanotechnology is one of the most important technologies in this century and it is evoking a new industrial revolution. Carbon nanotubes (CNTs) are important engineered nanoparticles with unique and beneficial properties. As a result, CNT has been used in a wide range of commercial products including electronics, optical devices and drug delivery leading to their disposal in the natural environment. Literature studies have investigated the mobility of CNTs in saturated porous media under differing physical and chemical conditions. However CNT transport in temporarily changing porous media water content has not been investigated thus far (a common scenario with rainfall/infiltration events in the vadose zone). This study investigated the mobilization of multi-walled CNTs (MCNTs) in repeated wetting and drying cycles with varying flow rates and ionic strength of the inflow solution. Imbibition-drainage-imbibition cycle experiments suggest that MCNTs mobilization increased with increase in flow rates. MCNTs mobilization occurred only with first imbibition events at low ionic strengths however less mobilization happened for higher ionic strength inflow solution in the first imbibition cycle and additional MCNTs were found in the outflow solution in second imbibition cycle, using low ionic strength solution. This observation was likely due to the attachment force between MCNTs and sand surface. Most of the MCNT mobilization occurred during liquid-gas interface movement with less chance of MCNTs to jump the energy barrier at higher ionic strength solution. As a result, less detachment of MCNTs occurred from the sand surface during drainage.

  18. Disaggregation of heteroaggregates composed of multiwalled carbon nanotubes and hematite nanoparticles.

    PubMed

    Huynh, Khanh An; Chen, Kai Loon

    2014-05-01

    In this study, the disaggregation behavior and the strength of heteroaggregates composed of multiwalled carbon nanotubes (CNTs) and hematite nanoparticles (HemNPs) were investigated in different solution chemistries. Negatively charged CNTs and positively charged HemNPs were first allowed to undergo favorable heteroaggregation at pH 5.5 and 0.1 mM NaCl before the CNT-HemNP heteroaggregates were disaggregated through the use of an ultrasonication bath. The heteroaggregate sizes before and after ultrasonication were measured by dynamic light scattering (DLS) in order to determine the degree of disaggregation. When the solution chemistry was unchanged, the heteroaggregates underwent partial disaggregation and heteroaggregate re-growth was observed after ultrasonication. Conversely, when the pH was raised to 11.0 immediately before ultrasonication, the heteroaggregates were almost completely disaggregated and no aggregation took place after disaggregation. Similarly, the introduction of humic acid led to a near complete disaggregation of the CNT-HemNP heteroaggregates. The elevated pH, as well as the adsorption of humic acid on the nanoparticles, was likely to weaken the particle-particle bonds within the heteroaggregates and hence increase the propensities of the heteroaggregates to undergo disaggregation.

  19. Oxygen diffusion into multiwalled carbon nanotube doped polystrene latex films using fluorescence technique.

    PubMed

    Yargı, Onder; Uğur, Saziye; Pekcan, Onder

    2013-05-01

    This study examines the oxygen diffusion into polystyrene (PS) latex/multiwalled carbon nanotube (MWNT) nanocomposite films (PS/MWNT) consisting of various amounts of MWNT via steady state fluorescence technique (SSF). PS/MWNT films were prepared from the mixture of MWNT and pyrene (P)-labeled PS latexes at various compositions at room temperature. These films were then annealed at 170 °C above glass transition (Tg) temperature of PS. Fluorescence quenching measurements were performed for each film separately to evaluate the effect of MWNT content on oxygen diffusion. The Stern-Volmer equation for fluorescence quenching is combined with Fick's law for diffusion to derive the mathematical expressions. Diffusion coefficients (D) were produced and found to be increased from 1.1 × 10(-12) to 41 × 10(-12) cm(2)s(-1) with increasing MWNT content. This increase was explained via the existence of large amounts of pores in composite films which facilitate oxygen penetration into the structure. PMID:23334487

  20. Bioaccumulation of Multiwall Carbon Nanotubes in Tetrahymena thermophila by Direct Feeding or Trophic Transfer.

    PubMed

    Mortimer, Monika; Petersen, Elijah J; Buchholz, Bruce A; Orias, Eduardo; Holden, Patricia A

    2016-08-16

    Consumer goods contain multiwall carbon nanotubes (MWCNTs) that could be released during product life cycles into the environment, where their effects are uncertain. Here, we assessed MWCNT bioaccumulation in the protozoan Tetrahymena thermophila via trophic transfer from bacterial prey (Pseudomonas aeruginosa) versus direct uptake from growth media. The experiments were conducted using (14)C-labeled MWCNT ((14)C-MWCNT) doses at or below 1 mg/L, which proved subtoxic since there were no adverse effects on the growth of the test organisms. A novel contribution of this study was the demonstration of the ability to quantify MWCNT bioaccumulation at low (sub μg/kg) concentrations accomplished by employing accelerator mass spectrometry (AMS). After the treatments with MWCNTs at nominal concentrations of 0.01 mg/L and 1 mg/L, P. aeruginosa adsorbed considerable amounts of MWCNTs: (0.18 ± 0.04) μg/mg and (21.9 ± 4.2) μg/mg bacterial dry mass, respectively. At the administered MWCNT dose of 0.3 mg/L, T. thermophila accumulated up to (0.86 ± 0.3) μg/mg and (3.4 ± 1.1) μg/mg dry mass by trophic transfer and direct uptake, respectively. Although MWCNTs did not biomagnify in the microbial food chain, MWCNTs bioaccumulated in the protozoan populations regardless of the feeding regime, which could make MWCNTs bioavailable for organisms at higher trophic levels.