Science.gov

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

  1. Magnetoresistance of multiwall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Lu, Li; Kang, N.; Kong, W. J.; Hu, J. S.; Pan, Z. W.; Xie, S. S.

    2002-03-01

    We have investigated the magnetoresistance of multiwall carbon nanotubes bundles. At temperatures above 15 K, the magnetoresistance was found to follow exactly a scaling law as predicted by the theory of two-dimensional (2D) weak localization. Below 15 K, the 2D weak localization behavior is modified due to the formation of a Coulomb gap. This modification does not fit to those theories which treat electron-electron interaction as a perturbation. Altshular-Aronov-Spivak (AAS) resistance oscillation was observed in milli-Kelvin temperature range. The results will be discussed in terms of the interplay between electron-electron interaction and disorder scattering in multiwall carbon nanotube.

  2. High Performance Multiwall Carbon Nanotube Bolometers

    DTIC Science & Technology

    2010-10-21

    REPORT High performance multiwall carbon nanotube bolometers 14. ABSTRACT 16. SECURITY CLASSIFICATION OF: High infrared bolometric photoresponse has...been observed in multiwall carbon nanotube MWCNT films at room temperature. The observed detectivity D in exceeding 3.3 106 cm Hz1/2 /W on MWCNT film...U.S. Army Research Office P.O. Box 12211 Research Triangle Park, NC 27709-2211 15. SUBJECT TERMS carbon nanotube, infrared detector, bolometer

  3. Multiwall carbon nanotube microcavity arrays

    SciTech Connect

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

    2016-03-21

    Periodic highly dense multi-wall carbon nanotube (MWCNT) arrays can act as photonic materials exhibiting band gaps in the visible regime and beyond terahertz range. MWCNT arrays in square arrangement for nanoscale lattice constants can be configured as a microcavity with predictable resonance frequencies. Here, computational analyses of compact square microcavities (≈0.8 × 0.8 μm{sup 2}) in MWCNT arrays were demonstrated to obtain enhanced quality factors (≈170–180) and narrow-band resonance peaks. Cavity resonances were rationally designed and optimized (nanotube geometry and cavity size) with finite element method. Series (1 × 2 and 1 × 3) and parallel (2 × 1 and 3 × 1) combinations of microcavities were modeled and resonance modes were analyzed. Higher order MWCNT microcavities showed enhanced resonance modes, which were red shifted with increasing Q-factors. Parallel microcavity geometries were also optimized to obtain narrow-band tunable filtering in low-loss communication windows (810, 1336, and 1558 nm). Compact series and parallel MWCNT microcavity arrays may have applications in optical filters and miniaturized optical communication devices.

  4. Enzymatic degradation of multiwalled carbon nanotubes.

    PubMed

    Zhao, Yong; Allen, Brett L; Star, Alexander

    2011-09-01

    Because of their unique properties, carbon nanotubes and, in particular, multiwalled carbon nanotubes (MWNTs) have been used for the development of advanced composite and catalyst materials. Despite their growing commercial applications and increased production, the potential environmental and toxicological impacts of MWNTs are not fully understood; however, many reports suggest that they may be toxic. Therefore, a need exists to develop protocols for effective and safe degradation of MWNTs. In this article, we investigated the effect of chemical functionalization of MWNTs on their enzymatic degradation with horseradish peroxidase (HRP) and hydrogen peroxide (H(2)O(2)). We investigated HRP/H(2)O(2) degradation of purified, oxidized, and nitrogen-doped MWNTs and proposed a layer-by-layer degradation mechanism of nanotubes facilitated by side wall defects. These results provide a better understanding of the interaction between HRP and carbon nanotubes and suggest an eco-friendly way of mitigating the environmental impact of nanotubes.

  5. 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.

  6. 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.

  7. 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...

  8. 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...

  9. Oxidative biodegradation of single- and multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Russier, Julie; Ménard-Moyon, Cécilia; Venturelli, Enrica; Gravel, Edmond; Marcolongo, Gabriele; Meneghetti, Moreno; Doris, Eric; Bianco, Alberto

    2011-03-01

    In this study we compare the biodegradation of both single-walled (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) using two different oxidative conditions. In particular, we demonstrate that oxidized multi-walled carbon nanotubes are highly degraded, although not to completeness when treated with horseradish peroxidase (HRP) in the presence of hydrogen peroxide.In this study we compare the biodegradation of both single-walled (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) using two different oxidative conditions. In particular, we demonstrate that oxidized multi-walled carbon nanotubes are highly degraded, although not to completeness when treated with horseradish peroxidase (HRP) in the presence of hydrogen peroxide. Electronic supplementary information (ESI) available: Experimental details, additional TEM images and DLS diagrams. See DOI: 10.1039/c0nr00779j

  10. Quantum Interference in Multiwall Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Strunk, Christoph

    2006-03-01

    Recent low temperature conductance measurements on multiwall carbon nanotubes in perpendicular and parallel magnetic field are reported. An efficient gating technique allows for a considerable tuning of the nanotube doping level. This enables us to study extensively the signature of nanotube bandstructure in electron quantum interference effects like weak localization, universal conductance fluctuations and the Aharonov-Bohm effect. We show that the weak localization is strongly suppressed at peaks at certain gate voltages which can be linked with the bottoms of one-dimensional electronic subbands. This assignment allows a detailed comparison of theoretical calculations with the experimental data. In agreement with the theory, we find clear indications for a pronounced energy dependence of the elastic mean free with a strong enhancement close to the charge neutrality point. In large parallel magnetic field, we observe a superposition of h/2e-periodic Altshuler-Aronov-Spivak oscillations and an additional h/e-periodic contribution. The latter contribution shows a diamond-like pattern in the B/Vgate-plane, which reflects the magnetic field dependence of the density of states of the outermost shell of the nanotube.

  11. Quantum interference in multiwall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Strunk, C.; Stojetz, B.; Roche, S.

    2006-11-01

    Recent low temperature conductance measurements on multiwall carbon nanotubes in perpendicular and parallel magnetic fields are reported. An efficient gating technique allows for considerable tuning of the nanotube doping level. This enables us to study extensively the effect of the nanotube bandstructure on electron quantum interference effects such as weak localization, universal conductance fluctuations and the Aharonov-Bohm effect. We show that the magnetoresistance in the perpendicular magnetic field is strongly suppressed at certain gate voltages Ugate which can be linked with the bottoms of one-dimensional electronic subbands. This assignment allows a detailed comparison of theoretical calculations with the experimental data. In agreement with the theory, a pronounced energy dependence of the elastic mean free path with a strong enhancement close to the charge neutrality point is observed. In the large parallel magnetic field, we observe a superposition of h/2e-periodic Altshuler-Aronov-Spivak oscillations and an additional h/e-periodic contribution to the conductivity. The latter contribution shows a diamond-like pattern in the B - Ugate-plane, which reflects the magnetic field dependence of the density of states of the nanotube's outermost shell.

  12. 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.

  13. 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 the...

  14. 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 the...

  15. 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...

  16. 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...

  17. 40 CFR 721.10663 - Functionalized 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 Functionalized multi-walled carbon... 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...

  18. 40 CFR 721.10155 - 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 § 721.10155 Multi-walled carbon nanotubes (generic). (a) Chemical substance... multi-walled carbon nanotubes (PMN P-08-177) is subject to reporting under this section for...

  19. 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...

  20. 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...

  1. 40 CFR 721.10703 - 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 § 721.10703 Multi-walled carbon nanotubes (generic). (a) Chemical substances... multi-walled carbon nanotubes (PMNs P-12-416, P-12-417, P-12-418, and P-12-419) are subject to...

  2. 40 CFR 721.10663 - Functionalized 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 Functionalized multi-walled carbon... 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...

  3. 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...

  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 the...

  5. 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 the...

  6. Free vibration of multiwall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Wang, C. Y.; Ru, C. Q.; Mioduchowski, A.

    2005-06-01

    A multiple-elastic shell model is applied to systematically study free vibration of multiwall carbon nanotubes (MWNTs). Using Flugge [Stresses in Shells (Springer, Berlin, 1960)] equations of elastic shells, vibrational frequencies and associated modes are calculated for MWNTs of innermost radii 5 and 0.65 nm, respectively. The emphasis is placed on the effect of interlayer van der Waals (vdW) interaction on free vibration of MWNTs. Our results show that the interlayer vdW interaction has a crucial effect on radial (R) modes of large-radius MWNTs (e.g., of the innermost radius 5 nm), but is less pronounced for R modes of small-radius MWNTs (e.g., of the innermost radius 0.65 nm), and usually negligible for torsional (T) and longitudinal (L) modes of MWNTs. This is attributed to the fact that the interlayer vdW interaction, characterized by a radius-independent vdW interaction coefficient, depends on radial deflections only, and is dominant only for large-radius MWNTs of lower radial rigidity but less pronounced for small-radius MWNTs of much higher radial rigidity. As a result, the R modes of large-radius MWNTs are typically collective motions of almost all nested tubes, and the R modes of small-radius MWNTs, as well as the T and L modes of MWNTs, are basically vibrations of individual tubes. In particular, an approximate single-shell model is suggested to replace the multiple-shell model in calculating the lowest frequency of R mode of thin MWNTs (defined by the innermost radius-to-thickness ratio not less than 4) with relative errors less than 10%. In addition, the simplified Flugge single equation is adopted to substitute the exact Flugge equations in determining the R-mode frequencies of MWNTs with relative errors less than 10%.

  7. Field emission from a selected multiwall carbon nanotube.

    PubMed

    Passacantando, M; Bussolotti, F; Santucci, S; Di Bartolomeo, A; Giubileo, F; Iemmo, L; Cucolo, A M

    2008-10-01

    The electron field emission characteristics of individual multiwalled carbon nanotubes were investigated by a piezoelectric nanomanipulation system operating inside a scanning electron microscopy chamber. The experimental set-up ensures a precise evaluation of the geometric parameters (multiwalled carbon nanotube length and diameter and anode-cathode separation) of the field emission system. For several multiwalled carbon nanotubes, reproducible and quite stable emission current behaviour was obtained, with a dependence on the applied voltage well described by a series resistance modified Fowler-Nordheim model. A turn-on field of ∼30 V µm(-1) and a field enhancement factor of around 100 at a cathode-anode distance of the order of 1 µm were evaluated. Finally, the effect of selective electron beam irradiation on the nanotube field emission capabilities was extensively investigated.

  8. 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.

  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. 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.

  11. Interesting behavior of polymers containing multiwall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Adamne Major, A.

    2017-02-01

    Mixing is a very important polymer process. Nanocomposites were made by a new type of shear mixer, IDMX. The nanocompostes contained different amount of multiwall carbon nanotubes. Test pieces were prepared by injection moulding method. Thermal, flowing and mechanical properties were measured.

  12. Tungsten disulphide coated multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Whitby, R. L. D.; Hsu, W. K.; Boothroyd, C. B.; Kroto, H. W.; Walton, D. R. M.

    2002-06-01

    Multi-walled carbon nanotubes (MWCNs), coated with ordered WS 2 mono- or multi-layers, are generated by pyrolysing H 2S/N 2 over MWCNs thinly coated with WO 3. High-resolution transmission electron microscopy (HRTEM) reveals the presence of hexagonal WS 2 arrays in the tube surface, consistent with the WS 2 simulated structure.

  13. Silver decorated multiwalled carbon nanotubes and their characterization

    NASA Astrophysics Data System (ADS)

    Gahlot, Swati; Kulshrestha, Vaibhav; Shahi, V. K.

    2014-04-01

    Deposition of silver nanoparticles on functionalized multiwalled carbon nanotubes is done in the present study. To decorate silver nanoparticles on CNT walls silver nitrate (AgNO3) was used as precursor. Finally prepared nanotubes (Ag-CNT) were analyzed by TEM, XRD and FTIR for the structural and chemical characterization.

  14. Carbon nanoparticle-modified multi-wall carbon nanotubes with fast adsorption kinetics for water treatment

    NASA Astrophysics Data System (ADS)

    Wang, Guan; Ren, Wei; Tan, Hui Ru; Liu, Ye

    2017-02-01

    Carbon nanoparticle-modified multi-wall carbon nanotubes were prepared using a dehydration of carbohydrate compound method. The structural change was characterized by transmission electron microscopy, Raman spectroscopy, and Brunauer, Emmett and Teller measurement. Fast adsorption kinetics was observed for multi-wall carbon nanotubes with modification, as demonstrated by the adsorption of the model compound methylene blue. This work provides a novel facile engineering strategy to equip multi-wall carbon nanotubes with fast adsorption kinetics, which is promising for efficient water purification.

  15. Carbon nanoparticle-modified multi-wall carbon nanotubes with fast adsorption kinetics for water treatment.

    PubMed

    Wang, Guan; Ren, Wei; Tan, Hui Ru; Liu, Ye

    2017-02-24

    Carbon nanoparticle-modified multi-wall carbon nanotubes were prepared using a dehydration of carbohydrate compound method. The structural change was characterized by transmission electron microscopy, Raman spectroscopy, and Brunauer, Emmett and Teller measurement. Fast adsorption kinetics was observed for multi-wall carbon nanotubes with modification, as demonstrated by the adsorption of the model compound methylene blue. This work provides a novel facile engineering strategy to equip multi-wall carbon nanotubes with fast adsorption kinetics, which is promising for efficient water purification.

  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. Laser-induced exfoliation of amorphous carbon layer on an individual multiwall carbon nanotube

    NASA Astrophysics Data System (ADS)

    Singh, G.; Rice, P.; Hurst, K. E.; Lehman, J. H.; Mahajan, R. L.

    2007-07-01

    Pulsed laser treatment of an individual multiwall carbon nanotube induced selective exfoliation of the amorphous carbon contamination layer. The multiwall carbon nanotube (MWCNT) was exposed to a 248nm excimer laser. After the treatment, transmission electron microscopy images show that the amorphous layer has expanded and separated from the crystalline MWCNT walls. This interesting observation has implications for laser cleaning and possible thinning of MWCNTs to reduce the radial dimensions.

  18. Impact of multi-walled carbon nanotubes on aquatic species.

    PubMed

    Asharani, P V; Serina, N G B; Nurmawati, M H; Wu, Y L; Gong, Z; Valiyaveettil, S

    2008-07-01

    To understand the environmental impacts of carbon nanotubes (CNTs), the toxicity study was carried out with water-soluble multi-walled carbon nanotubes (MWCNTs) using zebrafish (Danio rerio) as a model system. Zebrafish embryos were treated with different concentrations of MWCNTs. Teratogenic effects were evaluated through changes in embryonic development after 24 hours post-fertilization (hpf), 48 hpf and 72 hpf. No observable effect concentration (NOEC) was at 40 microg/mL. Lowest effect concentration (LOEC) of MWCNTs which caused significant phenotypic defects in zebrafish embryo was 60 microg/mL. At concentration above 60 microg/mL, slimy mucus like coating was observed around the embryo. At high concentrations, MWCNTs was found to be involved in the apoptosis, delayed hatching and formation of abnormal spinal chords. Thus, the toxicity of multi-walled carbon nanotubes is concentration dependent.

  19. Thermal Analysis of Copper-Titanium-Multiwall Carbon Nanotube Composites.

    PubMed

    Hamamda, Smail; Jari, Ahmed; Revo, S; Ivanenko, K; Jari, Youcef; Avramenko, T

    2017-12-01

    The aim of this research is the thermostructural study of Cu-Ti, Cu-Ti 1 vol% multiwall carbon nanotubes (MWCNTs) and Cu-Ti 3 vol% MWCNTs. Several investigation techniques were used to achieve this objective. Dilatometric data show that the coefficient of thermal expansion of the nanocomposite containing less multiwall carbon nanotubes is linear and small. The same nanocomposite exhibits regular heat transfer and weak mass exchange with the environment. Raman spectroscopy shows that the nanocomposite with more MWCNTs contains more defects. This implies that the carbon nanotubes have better dispersion in Cu-Ti 1 vol% MWCNTs. Infrared spectroscopy reveals that Cu-Ti 1 vol% MWCNTs has better crystallinity than Cu-Ti 3 vol% MWCNTs.

  20. Assessment of Human Lung Macrophages After Exposure to Multi-Walled Carbon Nanotubes. Part 1. Cytotoxicity

    DTIC Science & Technology

    2011-01-01

    Macrophages After Exposure to Multi-Walled Carbon Nanotubes Part I. Cytotoxicity Lin Zhu13, Amanda M. Schrand1, Andrey A. Voevodin4, Dong Wook Chang3...RXBT, Wright-Patterson AFB, OH 45433-5707, USA Due to the widespread production and use of carbon nanotubes in almost every area of science (i.e...cells after exposure to unpurified or acid- purified multi-walled carbon nanotubes . Cells were incubated with multi-walled carbon nanotubes and

  1. 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.

  2. Azopolymer film as an actuator for organizing multiwall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Capeluto, Maria Gabriela; Fernández Salvador, Raquel; Eceiza, Aranxa; Goyanes, Silvia; Ledesma, Silvia Adriana

    2017-04-01

    In this work we show the feasibility of using an azopolymer as an actuator to induce nano- and microscale movements controlled with light from the far field. We study azopolymers and their interaction with multi-walled carbon nanotubes (MWCNTs) by inducing surface relief gratings (SRG) through optical illumination. Upon different optical treatments, the MWCNTs are organized in the troughs or the crests of a surface relief grating. Large scale organization of MWCNTs has potential in applications such as transparent electronics.

  3. A multi-wall carbon nanotube tower electrochemical actuator.

    PubMed

    Yun, YeoHeung; Shanov, Vesselin; Tu, Yi; Schulz, Mark J; Yarmolenko, Sergey; Neralla, Sudhir; Sankar, Jag; Subramaniam, Srinivas

    2006-04-01

    Patterned multiwall carbon nanotube arrays up to four millimeters long were synthesized using chemical vapor deposition. Electrochemical actuation of a nanotube array tower was demonstrated in a 2 M NaCl solution at frequencies up to 10 Hz with 0.15% strain using a 2 V square wave excitation. The synthesis and electrochemical modeling approach outlined in the paper provide a foundation for the design of nanotube smart materials that actuate and are load bearing.

  4. Multiwalled Carbon Nanotubules Induce Pathological Changes in the Digestive Organs of Mice.

    PubMed

    Masyutin, A G; Erokhina, M V; Sychevskaya, K A; Gusev, A A; Vasyukova, I A; Tkachev, A G; Smirnova, E A; Onishchenko, G E

    2016-05-01

    We studied the effects of regular long-term exposure to industrial nanomaterial based on multiwalled carbon nanotubules on the digestive system of mice. Nanomaterial in a concentration of 30 mg/kg was administered with drinking water over 30 days. Tissue specimens from the small intestine and liver were studied by light and electron microscopy. Multiwalled carbon nanotubules caused multiple necrotic foci in the small intestine and mixed parenchymatous degeneration in the liver. These findings suggested that multiwalled carbon nanotubules entering the digestive tract damaged intestinal villi, presumably via mechanical damage to enterocytes. It seems that multiwalled carbon nanotubules could cause degeneration indirectly, by triggering inflammatory reactions and ROS generation.

  5. Adsorption of selected volatile organic vapors on multiwall carbon nanotubes.

    PubMed

    Shih, Yang-hsin; Li, Mei-syue

    2008-06-15

    Carbon nanotubes are expected to play an important role in sensing, pollution treatment and separation techniques. This study examines the adsorption behaviors of volatile organic compounds (VOCs), n-hexane, benzene, trichloroethylene and acetone on two multiwall carbon nanotubes (MWCNTs), CNT1 and CNT2. Among these VOCs, acetone exhibits the highest adsorption capacity. The highest adsorption enthalpies and desorption energies of acetone were also observed. The strong chemical interactions between acetone and both MWCNTs may be the result from chemisorption on the topological defects. The adsorption heats of trichloroethylene, benzene, and n-hexane are indicative of physisorption on the surfaces of both MWCNTs. CNT2 presents a higher adsorption capacity than CNT1 due to the existence of an exterior amorphous carbon layer on CNT2. The amorphous carbon enhances the adsorption capacity of organic chemicals on carbon nanotubes. The morphological and structure order of carbon nanotubes are the primary affects on the adsorption process of organic chemicals.

  6. Multi-walled carbon nanotubes plastic NH3 gas sensor

    NASA Astrophysics Data System (ADS)

    Isa, Siti S. Mat; Ramli, Muhammad M.; Jamlos, M. F.; Hambali, N. A. M. Ahmad; Isa, M. Mohamad; Kasjoo, S. R.; Ahmad, N.; Nor, N. I. M.; Khalid, N.

    2017-03-01

    Multi-walled Carbon Nanotubes (MWCNTs) functionalized -COOH was used as the sensing material. The MWCNTs suspension was then deposited on the plastic substrate using vacuum filtration method, hence created uniform thin film carbon nanotubes network. Plastic membrane was chosen as the substrate in order to produce flexible, lightweight, wearable and low cost sensor. This device was exposed to ammonia gas (NH3) at two different concentrations; 19.2 and 231.4 ppm. The device shows high sensitivity at 23.4 % when exposed to 231.4 ppm NH3 and less sensitivity at 4.39 % for 19.2 ppm NH3 exposure.

  7. Quantum conductance steps in solutions of multiwalled carbon nanotubes.

    PubMed

    Urbina, A; Echeverría, I; Pérez-Garrido, A; Díaz-Sánchez, A; Abellán, J

    2003-03-14

    We have prepared solutions of multiwalled carbon nanotubes in Aroclor 1254, a mixture of polychlorinated biphenyls. The solutions are stable at room temperature. Transport measurements were performed using a scanning-tunneling probe on a sample prepared by spin coating the solution on gold substrates. Conductance steps were clearly seen. A histogram of a high number of traces shows maximum peaks at integer values of the conductance quantum G(0)=2e(2)/h, demonstrating ballistic transport at room temperature along the carbon nanotube over distances longer than 1.4 microm.

  8. Thin micropatterned multi-walled carbon nanotube films for electrodes

    NASA Astrophysics Data System (ADS)

    Halonen, Niina; Mäklin, Jani; Rautio, Anne-Riikka; Kukkola, Jarmo; Uusimäki, Antti; Toth, Geza; Reddy, Leela Mohana; Vajtai, Robert; Ajayan, Pulickel M.; Kordas, Krisztian

    2013-09-01

    Micropatterned electrodes based on thin multi-walled carbon nanotube films are grown by catalytic chemical vapour deposition on lithographically defined quartz and Inconel alloy substrates. The electrical contact at the interface between the root of the nanotube arrays and the thin Ti hardmask layer on the quartz surface is found to be poor disabling proper capacitive characteristics. On the other hand, nanotube-Inconel electrodes show low series resistance and good electric double layer capacitor operation close to that of ideal devices. Patterning of the electrodes enhances both specific capacitance and power in reference to non-patterned bulk carbon nanotube film electrodes.

  9. Covalent functionalization of multi-walled carbon nanotubes by lipase

    NASA Astrophysics Data System (ADS)

    Shi, Qing; Yang, Dong; Su, Yanlei; Li, Jian; Jiang, Zhongyi; Jiang, Yanjun; Yuan, Weikang

    2007-12-01

    Lipase from Candida rugosa was covalently anchored onto acid-treated multi-walled carbon nanotubes (MWNTs) through a self-catalytic mechanism. A variety of characterization techniques including FTIR, Raman spectroscopy, and XPS were employed to demonstrate the formation of the ester linkage between lipase and MWNTs. The MWNTs-lipase biocomposites showed significantly increased solubility in some common-used organic solvents, such as THF, DMF and chloroform. This study may offer a novel and facile route for covalent modification of carbon nanotubes, and expand the potential utilization of both lipases and MWNTs in the fields of biocatalyst and biosensor.

  10. Electron magnetic resonance study of multiwalled carbon nanotubes and carbon nanohorns

    NASA Astrophysics Data System (ADS)

    Stefaniuk, Ireneusz; Cieniek, Bogumil; Rogalska, Iwona

    2016-12-01

    Temperature Electron Magnetic Resonance (EMR) measurements of multiwalled carbon nanotubes (CNT) and carbon nanohorns (CNH) were performed in the temperature range 5.2 - 300 K. The asymmetric resonance lines with Dyson shape were observed. The g-value of multiwalled carbon nanotubes (CNT) and carbon nanohorns (CNH) was calculated. Analysis of the temperature dependences of the integral intensity of EMR spectra was carried out using the Curie-Weiss law and Curie temperature θ(CNT) = 46,6 K and θ(CNT) = 8.6 K were obtained. We showed that the localization processes observed in nanocarbon materials lead to local quantum transport of spins or carriers.

  11. Electronic structure of multi-walled carbon fullerenes

    NASA Astrophysics Data System (ADS)

    Doore, Keith; Cook, Matthew; Clausen, Eric; Lukashev, Pavel V.; Kidd, Tim E.; Stollenwerk, Andrew J.

    2017-02-01

    Despite an enormous amount of research on carbon based nanostructures, relatively little is known about the electronic structure of multi-walled carbon fullerenes, also known as carbon onions. In part, this is due to the very high computational expense involved in estimating electronic structure of large molecules. At the same time, experimentally, the exact crystal structure of the carbon onion is usually unknown, and therefore one relies on qualitative arguments only. In this work we present the results of a computational study on a series of multi-walled fullerenes and compare their electronic structures to experimental data. Experimentally, the carbon onions were fabricated using ultrasonic agitation of isopropanol alcohol and deposited onto the surface of highly ordered pyrolytic graphite using a drop cast method. Scanning tunneling microscopy images indicate that the carbon onions produced using this technique are ellipsoidal with dimensions on the order of 10 nm. The majority of differential tunneling spectra acquired on individual carbon onions are similar to that of graphite with the addition of molecular-like peaks, indicating that these particles span the transition between molecules and bulk crystals. A smaller, yet sizable number exhibited a semiconducting gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) levels. These results are compared with the electronic structure of different carbon onion configurations calculated using first-principles. Similar to the experimental results, the majority of these configurations are metallic with a minority behaving as semiconductors. Analysis of the configurations investigated here reveals that each carbon onion exhibiting an energy band gap consisted only of non-metallic fullerene layers, indicating that the interlayer interaction is not significant enough to affect the total density of states in these structures.

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

    PubMed

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

    2015-03-04

    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.

  13. 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... nanotubes (MWCNT); rather, it aims to identify what is known and unknown about MWCNT to support future...

  14. 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 P-08-734...

  15. 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.

  16. 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.

  17. Applications of multi-walled carbon nanotube in electronic packaging

    PubMed Central

    2012-01-01

    Thermal management of integrated circuit chip is an increasing important challenge faced today. Heat dissipation of the chip is generally achieved through the die attach material and solders. With the temperature gradients in these materials, high thermo-mechanical stress will be developed in them, and thus they must also be mechanically strong so as to provide a good mechanical support to the chip. The use of multi-walled carbon nanotube to enhance the thermal conductivity, and the mechanical strength of die attach epoxy and Pb-free solder is demonstrated in this work. PMID:22405035

  18. 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.

  19. Lateral force microscopy of multiwalled carbon nanotubes.

    PubMed

    Lievonen, J; Ahlskog, M

    2009-06-01

    Carbon nanotubes are usually imaged with the atomic force microscope (AFM) in non-contact mode. However, in many applications, such as mechanical manipulation or elasticity measurements, contact mode is used. The forces affecting the nanotube are then considerable and not fully understood. In this work lateral forces were measured during contact mode imaging with an AFM across a carbon nanotube. We found that, qualitatively, both magnitude and sign of the lateral forces to the AFM tip were independent of scan direction and can be concluded to arise from the tip slipping on the round edges of the nanotube. The dependence on the normal force applied to the tip and on the ratio between nanotube diameter and tip radius was studied. We show that for small values of this ratio, the lateral force signal can be explained with a simple geometrical model.

  20. Superconducting Mechanism in multi-walled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Kim, Yong-Jihn

    2008-03-01

    Recently Japanese group led by Haruyama [1] reported the significant enhancement of superconductivity, i.e., Tc=12K, in end-bonded Multi-walled Carbon Nanotubes. We can explain the enhancement by the electron confinement in the lateral direction, i.e., between the inner and outer cylinders, because electron density correlation enhances the phonon-mediated superconductivity. In other words, superconductivity in the (multi-walled) Carbon Nanotubes is due to the electron-phonon interaction and Tc is enhanced due to the density correlation caused by the confinement. First, we use simple concentric rings to estimate the Tc enhancement using the BCS theory. Next, we use the tight-binding model to calculate the Tc increase more accurately. In this context, this experimental result is very similar to the enhancement of Tc=15K in 4 angstrom single-walled Carbon Nanotubes by Tang et al. [2]. [1] I. Takesue et al., Phys. Rev. Lett., Vol. 96, 057001 (2006). [2] Z. K. Tang et al., Science, Vol. 292, 2462 (2001).

  1. 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).

  2. Concept of nonvolatile memory based on multiwall carbon nanotubes.

    PubMed

    Maslov, Leonid

    2006-05-28

    In this study, a novel concept is proposed for molecular electronics that uses vertically aligned multiwall carbon nanotubes as nonvolatile memory elements. Nanotubes grown on a patterned substrate may be opened by partially deleting the outer molecular layer or layers, so that the inner core is able to move along the vertical tube axis. Mounting another dielectric plate above the nanotube forest at a specific distance from the tube caps can provide two stable van der Waals states of the inner core, providing for nonvolatile data storage. A device built using this architecture can function as a two-dimensional memory array. At each cross point in the array, a multiwall carbon nanotube exists in either the separated off-state or in the contact on-state, and can be switched between these states by applying voltage pulses at the corresponding electrodes. A theoretical memory density as high as 10(13) memory elements per square centimetre is possible, with an operation frequency exceeding 100 GHz. Significant physical characteristics of such a device are bi-stability and reversibility. Such a device can function both as nonvolatile random access memory and as terabit solid-state storage.

  3. Concept of nonvolatile memory based on multiwall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Maslov, Leonid

    2006-05-01

    In this study, a novel concept is proposed for molecular electronics that uses vertically aligned multiwall carbon nanotubes as nonvolatile memory elements. Nanotubes grown on a patterned substrate may be opened by partially deleting the outer molecular layer or layers, so that the inner core is able to move along the vertical tube axis. Mounting another dielectric plate above the nanotube forest at a specific distance from the tube caps can provide two stable van der Waals states of the inner core, providing for nonvolatile data storage. A device built using this architecture can function as a two-dimensional memory array. At each cross point in the array, a multiwall carbon nanotube exists in either the separated off-state or in the contact on-state, and can be switched between these states by applying voltage pulses at the corresponding electrodes. A theoretical memory density as high as 1013 memory elements per square centimetre is possible, with an operation frequency exceeding 100 GHz. Significant physical characteristics of such a device are bi-stability and reversibility. Such a device can function both as nonvolatile random access memory and as terabit solid-state storage.

  4. 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.

  5. Ultralong aligned multi-walled carbon nanotube for electrochemical sensing.

    PubMed

    Punbusayakul, Niramol; Ci, Lijie; Talapatra, Saikat; Surareungchai, Werasak; Ajayan, Pulickel M

    2008-04-01

    We have investigated electrochemical sensing properties of electrodes fabricated with ultralong aligned multi-walled carbon nanotube (MWNT) bundles synthesized using water-assisted chemical vapor deposition on aluminum (Al) and iron (Fe) coated silicon wafer with ethylene and argon/hydrogen gas as carbon source and buffer gas respectively. Cyclic voltammograms performed on these electrodes show diffusion-controlled-reversible reaction. The dominance of radial diffusion mass transport at these electrodes was also indicated by sigmoidal-shaped voltammograms obtained at various scan rates. These electrodes were able to sense very low concentration of ascorbic acid (approximately 0.7 microM) and dopamine (approximately 1.87 microM), two model species often used in electro-analysis. The excellent electrochemical properties along with good single species detection ability suggest that these MWNTs are promising electrode materials for developing very sensitive chemical and/or biological sensors.

  6. Single-color pyrometry of individual incandescent multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Singer, S. B.; Mecklenburg, Matthew; White, E. R.; Regan, B. C.

    2011-11-01

    Objects that are small compared to their thermal photon wavelengths violate the assumptions underlying optical pyrometry and can show unusual coherence effects. To investigate this regime, we measure the absolute light intensity from individual, incandescent multiwalled carbon nanotubes. The nanotube filaments’ physical dimensions and composition are determined using transmission electron microscopy and their emissivities are calculated in terms of bulk conductivities. A single-color pyrometric analysis then returns a temperature value for each wavelength, polarization, and applied bias measured. Compared to the more common multiwavelength analysis, single-color pyrometry supports a more consistent and complete picture of the carbon nanotube lamps, one that describes their emissivity, optical conductivity, and thermal conductivity in the range 1600-2400 K.

  7. 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.

  8. Facile approach to prepare multi-walled carbon nanotubes/graphene nanoplatelets hybrid materials

    PubMed Central

    2013-01-01

    A facile approach was developed to prepare multi-walled carbon nanotubes/graphene nanoplatelets hybrid materials through covalent bond formation. First, poly(acryloyl chloride) was grafted onto oxidized multi-walled carbon nanotubes through the reaction between the acyl chloride groups of poly and the hydroxyl groups of oxidized multi-walled carbon nanotubes. Second, the remaining acyl chloride groups of poly were allowed to react with the hydroxyl groups of hydroxylated graphene nanoplatelets. Scanning electron microscopy and transmission electron microscopy data showed that the multi-walled carbon nanotubes and graphene nanoplatelets were effectively connected with each other. And Fourier transform infrared spectroscopy data indicated the formation of covalent bonds between carbon nanotubes and graphene nanoplatelets. Conformational changes were monitored by Raman spectroscopy. This novel kind of carbon hybrid materials may have the potential application in a wide field, especially in increasing the toughness and strength of the matrix resin. PMID:23680189

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

    PubMed

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

    2012-12-07

    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 Fe(3)O(4)-functionalized CNTs were prepared and studied using energy-filter mapping of Fe(3)O(4). CNTs bearing Fe(3)O(4) 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.

  10. 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.

  11. Bending of multiwalled carbon nanotubes over gold lines

    NASA Astrophysics Data System (ADS)

    Walkeajärvi, T.; Lievonen, J.; Ahlskog, M.; Åström, J.; Koshio, A.; Yudasaka, M.; Iijima, S.

    2005-11-01

    We have investigated an experimentally moderate bending of multiwalled carbon nanotubes (MWNTs) in the perpendicular direction from flat substrates. The tubes were in the diameter range of 3-13nm and deposited over lithographically fabricated gold lines whose height determined the total bending. In our model for the bending profile we take into account the van der Waals attraction between the substrate and the MWNT and the opposing elastic bending force. With reasonable parameters for the competing forces we obtain an agreement between the model and the experimental data for the critical distance between two adjacent lines when the van der Waals attraction can no longer prevent elastic forces from straightening the tube to a suspended position between the lines. However, for the smallest nanotubes a simple classical model is clearly insufficient.

  12. 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.

  13. Buckling and kinking force measurements on individual multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

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

    2007-11-01

    Using an atomic force microscope operated inside a transmission electron microscope, we have studied the forces involved in buckling and kinking an individual multiwalled carbon nanotube while observing its structure. In particular, we have measured an individual nanotube’s asymptotic critical buckling load and critical kinking load. The buckling results are well described by classical elastic theory, while the observed kinking behavior requires a more involved analysis. Repeated buckling measurements on the same nanotube indicate an extremely high degree of elasticity and set a lower bound on the nanotube’s yield strength of 1.7GPa , higher than the yield strength of steel. Plastic deformation of the nanotube was eventually observed following kinking.

  14. Microwave conductance of aligned multiwall carbon nanotube textile sheets

    NASA Astrophysics Data System (ADS)

    Brown, Brian L.; Bykova, Julia S.; Howard, Austin R.; Zakhidov, Anvar A.; Shaner, Eric A.; Lee, Mark

    2014-12-01

    Multiwall carbon nanotube (MWNT) sheets are a class of nanomaterial-based multifunctional textile with potentially useful microwave properties. To understand better the microwave electrodynamics, complex AC conductance measurements from 0.01 to 50 GHz were made on sheets of highly aligned MWNTs with the alignment texture both parallel and perpendicular to the microwave electric field polarization. In both orientations, the AC conductance is modeled to first order by a parallel frequency-independent conductance and capacitance with no inductive contribution. This is consistent with low-frequency diffusive Drude AC conduction up to 50 GHz, in contrast to the "universal disorder" AC conduction reported in many types of single-wall nanotube materials.

  15. Field Emission from Lateral Multiwalled Carbon Nanotube Yarn Emitters

    NASA Astrophysics Data System (ADS)

    Chen, Guohai; Song, Yenan

    2016-10-01

    A field emission from a lateral emitter made by a multiwalled carbon nanotube (MWCNT) yarn was investigated. The lateral emitter showed an excellent field emission performance with a low turn-on electric field of 1.13 V/um at an emission current of 1 uA, high emission current of 0.2 mA at an applied voltage of 700 V, and long-time emission stability for over 20 h without any significant current decay under an initial emission current of about 0.10 mA. The lateral emitter also demonstrated a uniform line emission pattern. It is suggested that the field emission occurs from the outmost MWCNTs which are protruding out from the yarn surface.

  16. Extremely Long Multiwall Carbon Nanotube Arrays for Spinning Yarn

    NASA Astrophysics Data System (ADS)

    Jayasinghe, Chaminda; Salunke, Pravahan; Lee, Lucy; Head, Emily; Mallik, Nilanjan; Yun, Yeoheung; Pendyala, Chandrashekhar; Schulz, Mark J.; Shanov, Vesselin N.

    2008-03-01

    Centimeter long Multiwall Carbon Nanotube (MWCNT) arrays have been grown by CVD from H2-C2H4-H20-Ar gas mixture at 750 C in an Easy Tube furnace from First Nano Inc. The arrays were characterized by AFM, SEM, TEM and Raman spectroscopy. The diameter of the CNT was found to be affected by the substrate design. The substrate preparation had great impact on the nanotube diameter. The CVD growth has been optimized with respect to the length and the purity of the CNT. It was found that the CVD growth conditions affect dramatically the quality of the arrays. Base on the optimized process 15 mm long CNT arrays were synthesized and preliminary data were obtained on spinning them into yarns.

  17. Core-Tube Morphology of Multiwall Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Sato, Motohiro; Shima, Hiroyuki; Iiboshi, Kohtaroh

    The present paper investigates the cross-sectional morphology of Multiwalled Carbon Nanotubes (MWNTs) restrained radially and circumferentially by an infinite surrounding elastic medium, subjected to uniform external hydrostatic pressure. In this study, a two-dimensional plane strain model is developed, assuming no variation of load and deformation along the tube axis. We find some characteristic cross-sectional shapes from the elastic buckling analysis. The effect of the surrounded elastic medium on the cross-sectional shape which occurs due to pressure buckling is focused on by the comparison with the shape for no elastic medium case in our discussion. It is suggested that in no embedded elastic medium cases, the cross-sectional shapes of inner tubes maintain circle or oval; on the other hand, an embedded medium may cause inner tube corrugation modes especially when the number of shells for MWNTs is small.

  18. He ion irradiation effects on multiwalled carbon nanotubes structure

    NASA Astrophysics Data System (ADS)

    Elsehly, Emad M.; Chechenin, Nikolay G.; Makunin, Alexey V.; Shemukhin, Andrey A.; Motaweh, Hussien A.

    2017-03-01

    Samples of multi-walled carbon nanotubes (MWNTs) were irradiated with 80 keV He ions. Scanning electron microscopy (SEM) inspection showed that the average outer diameters of the tube decreased as a result of ion irradiation. The samples were also characterized using Raman spectrometry by analysis of the intensity of main bands in the spectra of virgin and irradiated MWNT samples. Modifications of the disorder mode (D-band) and the tangential mode (G-band) were studied as a function of irradiation fluences. Raman spectra showed that as the fluence increases, the MWNTs first show disorder due to the produced defects, and then amorphization under still higher fluence of ion irradiation. Thermal and athermal mechanisms of the radiation induced MWNTs modifications are discussed. Contribution to the Topical Issue "Many Particle Spectroscopy of Atoms, Molecules, Clusters and Surfaces", edited by A.N. Grum-Grzhimailo, E.V. Gryzlova, Yu V. Popov, and A.V. Solov'yov.

  19. 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.

  20. Electric current distribution of a multiwall carbon nanotube

    SciTech Connect

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

    2016-07-15

    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.

  1. Lower-defect graphene oxide nanoribbons from multiwalled carbon nanotubes.

    PubMed

    Higginbotham, Amanda L; Kosynkin, Dmitry V; Sinitskii, Alexander; Sun, Zhengzong; Tour, James M

    2010-04-27

    An improved method is described for the production of graphene oxide nanoribbons (GONRs) via longitudinal unzipping of multiwalled carbon nanotubes. The method produces GONRs with fewer defects and/or holes on the basal plane, maintains narrow ribbons <100 nm wide, and maximizes the high aspect ratio. Changes in the reaction conditions such as acid content, time, and temperature were investigated. The new, optimized method which introduces a second, weaker acid into the system, improves the selectivity of the oxidative unzipping presumably by in situ protection of the vicinal diols formed on the basal plane of graphene during the oxidation, and thereby prevents their overoxidation and subsequent hole generation. The optimized GONRs exhibit increased electrical conductivity over those chemically reduced nanoribbons produced by previously reported procedures.

  2. 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.

  3. Computer controlled multi-walled carbon nanotube inhalation exposure system.

    PubMed

    McKinney, Walter; Chen, Bean; Frazer, Dave

    2009-10-01

    Inhalation exposure systems are necessary tools for determining the dose-response relationship of inhaled toxicants under a variety of exposure conditions. The objective of this project was to develop an automated computer controlled system to expose small laboratory animals to precise concentrations of airborne multi-walled carbon nanotubes (MWCNT). An aerosol generator was developed which was capable of suspending a respirable fraction of multi-walled carbon nanotubes from bulk material. The output of the generator was used to expose small laboratory animals to constant aerosol concentrations up to 12 mg/m(3). Particle distribution and morphology of the MWCNT aerosol delivered to the exposure chamber were measured and compared to samples previously taken from air inside a facility that produces MWCNT. The comparison showed the MWCNT generator was producing particles similar in size and shape to those found in a work environment. The inhalation exposure system combined air flow controllers, particle monitors, data acquisition devices, and custom software with automatic feedback control to achieve constant and repeatable exposure chamber temperature, relative humidity, pressure, aerosol concentration, and particle size distribution. The automatic control algorithm was capable of maintaining the mean aerosol concentration to within 0.1 mg/m(3) of the selected target value, and it could reach 95% of the target value in less than 10 minutes during the start-up of an inhalation exposure. One of the major advantages of this system was that once the exposure parameters were selected, a minimum amount of operator intervention was required over the exposure period.

  4. Mechanical and Electrical Properties of Organogels with Multiwall Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Moniruzzaman, Mohammad; Winey, Karen

    2008-03-01

    Organogels are fascinating thermally reversible viscoelastic materials that are comprised of an organic liquid and low concentrations (typically <2 wt %) of low molecular mass organic gelators. We have fabricated the first organogel/carbon nanotube composites using 12-hydroxystearic acid (HSA) as the gelator molecule and pristine and carboxylated multi-wall carbon nanotubes as the nanofillers and 1,2-dichlorobenzene as the organic solvent. We have achieved significant improvements in the mechanical and electrical properties of organogels by incorporating these carbon nanotubes. For example, the linear viscoelastic regime of the HSA organogel, an indicator of the strength of the gel, extends by a factor of 4 with the incorporation of 0.2 wt% of the carboxylated nanotubes. Also, the carbon nanotubes (specially the pristine tubes) improve the electrical conductivity of the organogels, e.g. six orders of magnitude enhancement in electrical conductivity with 0.2 wt% of pristine tubes. Differential scanning calorimetry experiments indicate that the nanotubes do not affect the thermoreversibility of the organogels.

  5. Aerosol generation and measurement of multi-wall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Myojo, Toshihiko; Oyabu, Takako; Nishi, Kenichiro; Kadoya, Chikara; Tanaka, Isamu; Ono-Ogasawara, Mariko; Sakae, Hirokazu; Shirai, Tadashi

    2009-01-01

    Mass production of some kinds of carbon nanotubes (CNT) is now imminent, but little is known about the risk associated with their exposure. It is important to assess the propensity of the CNT to release particles into air for its risk assessment. In this study, we conducted aerosolization of a multi-walled CNT (MWCNT) to assess several aerosol measuring instruments. A Palas RBG-1000 aerosol generator applied mechanical stress to the MWCNT by a rotating brush at feed rates ranging from 2 to 20 mm/h, which the MWCNT was fed to a two-component fluidized bed. The fluidized bed aerosol generator was used to disperse the MWCNT aerosol once more. We monitored the generated MWCNT aerosol concentrations based on number, area, and mass using a condensation particle counter and nanoparticle surface area monitor. Also we quantified carbon mass in MWCNT aerosol samples by a carbon monitor. The shape of aerosolized MWCNT fibers was observed by a scanning electron microscope (SEM). The MWCNT was well dispersed by our system. We found isolated MWCNT fibers in the aerosols by SEM and the count median lengths of MWCNT fibers were 4-6 μm. The MWCNT was quantified by the carbon monitor with a modified condition based on the NIOSH analytical manual. The MWCNT aerosol concentration (EC mass base) was 4 mg/m3 at 2 mm/h in this study.

  6. 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

    2015-12-08

    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.

  7. 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.

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

    SciTech Connect

    Arora, Neha; Sharma, N. N.

    2016-04-13

    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.

  9. Oriented graphene nanoribbon yarn and sheet from aligned multi-walled carbon nanotube sheets.

    PubMed

    Carretero-González, Javier; Castillo-Martínez, Elizabeth; Dias-Lima, Marcio; Acik, Muge; Rogers, Duncan M; Sovich, Justin; Haines, Carter S; Lepró, Xavier; Kozlov, Mikhail; Zhakidov, Anvar; Chabal, Yves; Baughman, Ray H

    2012-11-08

    Highly oriented graphene nanoribbons sheets and yarns are produced by chemical unzipping of self-standing multiwalled carbon nanotube (MWNT) sheets. The as-produced yarns - after being chemically and thermally reduced - exhibit a good mechanical, electrical, and electrochemical performance.

  10. 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...

  11. 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...

  12. 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...

  13. 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...

  14. Assessment of Human Lung Macrophages After Exposure to Multi-Walled Carbon Nanotubes. Part 2. DNA Damage

    DTIC Science & Technology

    2011-01-01

    to Multi-Walled Carbon Nanotubes Part II. DNA Damage Lin Zhu13, Amanda M. Schrand1, Andrey A. Voevodin4, Dong Wook Chang3, Liming Dai2∗, and Saber M...5707 Due to the widespread production and use of carbon nanotubes in almost every area of science (i.e., drug delivery, biosensors, fuel cells and...purified multi-walled carbon nanotubes . Cells were incubated with multi-walled carbon nanotubes and assessed for DNA damage response via fluorescent

  15. Multiwalled carbon nanotubes for flow-induced voltage generation

    NASA Astrophysics Data System (ADS)

    Liu, Jianwei; Dai, Liming; Baur, Jeff W.

    2007-03-01

    Recently it has been reported that voltage can be generated by passing fluids over single-walled carbon nanotube (SWCNT) arrays with potential application to flow sensors with a large dynamic range. The present work investigates voltage generation properties of multiwalled carbon nanotubes (MWCNTs) as a function of the relative orientation of the nanotube array with respect to the flow direction, flow velocity, and solution ionic strength. It was found that the flow-induced voltage can be significantly enhanced by aligning the nanotubes along the flow direction, increasing the flow velocity and/or the ionic strength of the flowing liquid. A flow-induced voltage of ˜30mV has been generated from our perpendicularly-aligned MWCNT in an aqueous solution of 1M NaCl at a relatively low flow velocity of 0.0005m/s, which is 15 times higher than the highest voltage reported for single-walled carbon nanotubes. The results are generally consistent with the pulsating asymmetric ratcheting mechanism proposed for SWCNT arrays, in which an asymmetrical spatial distributed strain forms from interactions with the polar and ionic species at the tube surface and is driven along the tube by the fluid flow.

  16. 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.

  17. Photothermal therapy of melanoma tumor using multiwalled carbon nanotubes.

    PubMed

    Sobhani, Zahra; Behnam, Mohammad Ali; Emami, Farzin; Dehghanian, Amirreza; Jamhiri, Iman

    2017-01-01

    Photothermal therapy (PTT) is a therapeutic method in which photon energy is transformed into heat rapidly via different operations to extirpate cancer. Nanoparticles, such as carbon nanotubes (CNTs) have exceptional optical absorbance in visible and near infrared spectra. Therefore, they could be a good converter to induce hyperthermia in PTT technique. In our study, for improving the dispersibility of multiwalled CNTs in water, the CNTs were oxidized (O-CNTs) and then polyethylene glycol (PEG) was used for wrapping the surface of nanotubes. The formation of a thin layer of PEG around the nanotubes was confirmed through Fourier transform infrared, thermogravimetric analysis, and field emission scanning electron microscopy techniques. Results of thermogravimetric analysis showed that the amount of PEG component in the O-CNT-PEG was approximately 80% (w/w). Cell cytotoxicity study showed that O-CNT was less cytotoxic than pristine multiwalled nanotubes, and O-CNT-PEG had the lowest toxicity against HeLa and HepG2 cell lines. The effect of O-CNT-PEG in reduction of melanoma tumor size after PTT was evaluated. Cancerous mice were exposed to a continuous-wave near infrared laser diode (λ=808 nm, P=2 W and I=8 W/cm(2)) for 10 minutes once in the period of the treatment. The average size of tumor in mice receiving O-CNT-PEG decreased sharply in comparison with those that received laser therapy alone. Results of animal studies indicate that O-CNT-PEG is a powerful candidate for eradicating solid tumors in PTT technique.

  18. 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.

  19. Giant magnetic moment at open ends of multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Wang, Gang; Chen, Min-Jiang; Yu, Fang; Xue, Lei-Jiang; Deng, Ya; Zhang, Jian; Qi, Xiao-Ying; Gao, Yan; Chu, Wei-Guo; Liu, Guang-Tong; Yang, Hai-Fang; Gu, Chang-Zhi; Sun, Lian-Feng

    2015-01-01

    The attractions of cantilevers made of multiwalled carbon nanotubes (MWNTs) and secured on one end are studied in the non-uniform magnetic field of a permanent magnet. Under an optical microscope, the positions and the corresponding deflections of the original cantilevers (with iron catalytic nanoparticles at the free end) and corresponding cut-off cantilevers (the free ends consisting of open ends of MWNTs) are studied. Both kinds of CNT cantilevers are found to be attracted by the magnet, and the point of application of force is proven to be at the tip of the cantilever. By measuring and comparing deflections between these two kinds of cantilevers, the magnetic moment at the open ends of the CNTs can be quantified. Due to the unexpectedly high value of the magnetic moment at the open ends of carbon nanotubes, it is called giant magnetic moment, and its possible mechanisms are proposed and discussed. Project supported by the National Natural Science Foundation of China (Grant Nos. 10774032 and 51472057) and the Instrument Developing Project of the Chinese Academy of Sciences (Grant No. Y2010031).

  20. 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.

  1. Functionalized multi-walled carbon nanotubes as affinity ligands

    NASA Astrophysics Data System (ADS)

    Yu, L.; Li, C. M.; Zhou, Q.; Gan, Y.; Bao, Q. L.

    2007-03-01

    Functionalization of carbon nanotubes is very challenging for their applications. The paper here describes a new method to functionalize multi-walled carbon nanotubes (MWCNTs) as specific affinity adsorbents. MWCNTs were acid purified and pretreated with (3-aminopropyl)-triethoxysilane (APTES) in order to introduce abundant amino groups on the surface of MWCNTs. After the conversion of amino groups to carboxyl groups by succinic acid anhydride, MWCNTs were attached to protein A or aminodextran using 1-ethyl-3,3' (dimethylamion)-propylcarbodiimide as a biofunctional crosslinker. The incorporation of aminodextran as a spacer arm noticeably increased the binding capacity of the APTES-modified MWCNTs for protein A. The application of affinity MWCNTs for purification of immunoglobulin G was then evaluated. The affinity of MWCNTs with AMD spacer exhibited a high adsorption capacity of ~361 µg IgG/mg MWCNT (wet basis). About 75% of bound IgG was eluted from affinity MWCNTs (ANT-I and ANT-II) and ELISA confirmed that the biological activity of IgG was well preserved during the course of affinity separation. The functionalized MWCNTs could be potentially used in affinity chromatography.

  2. Molecular Dynamics Studies on Thermal Transport Through Multiwalled Carbon Nanotubes.

    PubMed

    Hu, Guo-Jie; Cao, Bing-Yang; Guo, Zeng-Yuan

    2015-04-01

    The influence of the temperature and strength of the inter-wall interaction on the thermal conductivities of the (5,5) and (10, 10) double-walled carbon nanotubes (DWNTs) is studied by using molecular dynamics (MD) simulations with two different temperature control methods. One method is imposing heat baths (HBs) only on the outer wall, while the other is imposing HBs on both the two walls. The results show that the thermal conductivities of the DWNTs with the first method are about two-third of those with the second method. The relationship is the same even if the temperature and strength of the inter-wall interaction vary. Besides, the thermal conductivities of the DWNTs with the two different temperature control methods both slightly increase with the increasing energy parameters of Lennard-Jones (LJ) potential describing the inter-wall interaction and decrease with increasing temperature. Based on the analyses of the temperature profiles and phonon density of states (PDOS) spectra of the DWNTs with the two different temperature control methods, the results are well explained and the thermal transport mechanisms of multiwalled carbon nanotubes (MWNTs) under different conditions are explored.

  3. Mechanical behavior of ultralong multiwalled carbon nanotube mats

    NASA Astrophysics Data System (ADS)

    Deck, Christian P.; Flowers, Jason; McKee, Gregg S. B.; Vecchio, Kenneth

    2007-01-01

    Carbon nanotubes (CNTs) have been a subject of great interest partially due to their potential for exceptional material properties. Improvements in synthesis methods have facilitated the production of ultralong CNT mats, with lengths in the millimeter range. The increased length of these ultralong mats has, in return, opened the way to greater flexibility to probe their mechanical response. In this work, mats of dense, well-aligned, multiwalled carbon nanotubes were grown with a vapor-phase chemical vapor deposition technique using ferrocene and benzene as reactants, and subsequently tested in both tension and compression using two methods, in a thermomechanical analyzer and in situ inside a scanning electron microscope. In compression, measured stiffness was very low, due to buckling of the nanotubes. In tension, the nanotube mats behaved considerably stiffer; however, they were still more compliant than expected for nanotubes (˜1TPa). Analysis of both the growth method used and the nanotube mat fracture surface suggests that the mats grown in this method are not composed of continuous nanotubes and their strengths actually closely match those of woven nanotube yarns and ropes.

  4. 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.

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

    PubMed

    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.

  6. Light-scattering and dispersion behavior of multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Saltiel, Craig; Manickavasagam, Siva; Pinar Mengüc, M.; Andrews, Rodney

    2005-08-01

    Elliptically polarized light-scattering measurements were performed to investigate the dispersion behavior of multiwalled carbon nanotubes (MWNT). Xylene- and pyridine-derived MWNT powders were dispersed in water and ethanol in separate optic cells and allowed to sit undisturbed over a two-week time period after probe sonication. Continuous light-scattering measurements taken between scattering angles of 10-170 deg and repeated over several days showed that the nanotubes formed fractal-like networks. The pyridine-derived MWNTs showed greater dispersion variation over time, tending to aggregate and clump much faster than the xylene-derived tubes. The water suspensions appeared much more stable than the ethanol suspensions, which transformed into nonfractal morphology after a few hours. We relate the dispersion stability to size and fringe patterns on the outer surface of the nanotubes. Measured values of fractal dimension were distinctly lower than those in previous studies of single-walled carbon nanotubes. Profiles of both diagonal and off-diagonal scattering matrix elements are presented.

  7. 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.

  8. 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

  9. 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.

  10. Preparation and Characterization of Poly(methyl methacrylate)-functionalized Carboxyl Multi-walled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Meng, Qing-jie; Zhang, Xing-xiang; Bai, Shi-he; Wang, Xue-chen

    2007-12-01

    An in situ polymerization process was used to prepare poly (methyl methacrylate) (PMMA)-functionalized carboxyl multi-walled carbon nanotubes using carboxylate carbon nanotubes and methyl methacrylate as reactants and benzoyl peroxide as an initiator agent. The functionalized multi-walled carbon nanotubes were characterized using transmission electron microscope, scanning electron microscope, nuclear magnetic resonance, Fourier transform infrared spectroscopy, thermogravimetric analysis and Raman. The results indicate that the PMMA chains are covalently linked with the surface of carboxylate carbon nanotubes. The surface morphology is controlled by the content of carboxylate carbon nanotubes in the reactants. The PMMA functionalized multi-walled carbon nanotubes are soluble in deuterated chloroform. The storage modulus and tanδ magnitude increase as the content of CCNTs increases up to 0.3%.

  11. Effects of Gases on Field Emission from Single and Multi-Wall Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Wadhawan, A.; Stephens, K.; Stallcup, R., II; Perez, J.; Physics Department Collaboration

    2001-03-01

    We report the effects of O_2, H_2, and Ar exposure on the field emission properties of single and multi-wall carbon nanotubes. The field emission current vs. voltage curves and field emission current vs. time were measured as a function of gas exposure at 10-8 Torr over a period of approximately 8 hours. The data were collected using an automated system running under Labview. We find that H2 and Ar exposure do not significantly affect the field emission properties of either single or multi-walled carbon nanotubes. However, O2 exposure degrades the field emission properties of multi-wall tubes more than those of single-wall tubes. After O2 exposure, the turn-on voltage for multi-wall tubes increased fromm 300 to 500 volts, while the turn-on voltage for single-wall tubes increased from 200 to 250 volts. An explanation of these results will be discussed.

  12. 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.

  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

    ... 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 information...-walled carbon nanotubes as identified in Premanufacture Notice (PMN) P-08-199. EPA received several...

  14. Variational principles for transversely vibrating multiwalled carbon nanotubes based on nonlocal Euler-Bernoulli beam model.

    PubMed

    Adali, Sarp

    2009-05-01

    Variational principles are derived for multiwalled carbon nanotubes undergoing vibrations. Derivations are based on the continuum modeling with the Euler-Bernoulli beam representing the nanotubes and small scale effects taken into account via the nonlocal elastic theory. Hamilton's principle for multiwalled nanotubes is given and Rayleigh's quotient for the frequencies is derived for nanotubes undergoing free vibrations. Natural and geometric boundary conditions are derived which lead to a set of coupled boundary conditions due to nonlocal effects.

  15. 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

  16. 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,

  17. Spectroscopic investigations on oxidized multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Anandhi, C. M. S.; Premkumar, S.; Asath, R. Mohamed; Mathavan, T.; Benial, A. Milton Franklin

    2016-05-01

    The pristine multi-walled carbon nanotubes (MWCNTs) were oxidized by the ultrasonication process. The oxidized MWCNTs were characterized by the X-ray diffraction (XRD), ultraviolet-visible (UV-Vis) and Fourier transform -Raman (FT-Raman) spectroscopic techniques. The XRD analysis confirms that the oxidized MWCNTs exist in a hexagonal structure and the sharp XRD peak corresponds to the (002) Bragg's reflection plane, which indicates that the MWCNTs have higher crystalline nature. The UV-Vis analysis confirms that the MWCNTs functionalized with the carboxylic acid. The red shift was observed corresponds to the D band in the Raman spectrum, which reveals that the reduced disordered graphitic structure of oxidized MWCNTs. The strong Raman peak was observed at 2563 cm-1 corresponds to the overtone of the D band, which is the characteristic vibrational mode of oxidized MWCNTs. The carboxylic acid functionalization of MWCNTs enhances the dispersibility, which paves the way for potential applications in the field of biosensors and targeted drug delivery.

  18. 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.

  19. Microwave conductance properties of aligned multiwall carbon nanotube textile sheets

    NASA Astrophysics Data System (ADS)

    Brown, Brian L.; Martinez, Patricia; Zakhidov, Anvar A.; Shaner, Eric A.; Lee, Mark

    2015-07-01

    Understanding the conductance properties of multi-walled carbon nanotube (MWNT) textile sheets in the microwave regime is essential for their potential use in high-speed and high-frequency applications. To expand current knowledge, complex high-frequency conductance measurements from 0.01 to 50 GHz and across temperatures from 4.2 K to 300 K and magnetic fields up to 2 T were made on textile sheets of highly aligned MWNTs with strand alignment oriented both parallel and perpendicular to the microwave electric field polarization. Sheets were drawn from 329 and 520 μm high MWNT forests that resulted in different DC resistance anisotropy. For all samples, the microwave conductance can be modeled approximately by a shunt capacitance in parallel with a frequency-independent conductance, but with no inductive contribution. This is consistent with diffusive Drude conduction as the primary transport mechanism up to 50 GHz. Further, it is found that the microwave conductance is essentially independent of both temperature and magnetic field.

  20. Electrical properties of multiwalled carbon nanotube reinforced fused silica composites.

    PubMed

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

    2006-12-01

    Multiwalled carbon nanotube (MWCNT)-fused silica composite powders were synthesized by solgel method and dense bulk composites were successfully fabricated via hot-pressing. This composite was characterized by XRD, HRTEM, and FESEM. MWCNTs in the hot-pressed composites are in their integrity observed by HRTEM. The electrical properties of MWCNT-fused silica composites were measured and analyzed. The electrical resistivity was found to decrease with the increase in the amount of the MWCNT loading in the composite. When the volume percentage of the MWCNTs increased to 5 vol%, the electrical resistivity of the composite is 24.99 omega cm, which is a decrease of twelve orders of value over that of pure fused silica matrix. The electrical resistivity further decreases to 1.742 omega. cm as the concentration of the MWCNTs increased to 10 vol%. The dielectric properties of the composites were also measured at the frequency ranging from 12.4 to 17.8 GHz (Ku band) at room temperature. The experimental results reveal that the dielectric properties are extremely sensitive to the volume percentage of the MWCNTs, and the permittivities, especially the imaginary permittivities, increase dramatically with the increase in the concentration of the MWCNTs. The improvement of dielectric properties in high frequency region mainly originates from the greatly increasing electrical properties of the composite.

  1. Oxidation behavior of multiwalled carbon nanotubes fluidized with ozone.

    PubMed

    Vennerberg, Danny C; Quirino, Rafael L; Jang, Youngchan; Kessler, Michael R

    2014-02-12

    Multiwalled carbon nanotubes (MWCNTs) were simultaneously fluidized and oxidized with gaseous ozone in a vertical reactor. Two different varieties of MWCNTs were compared to determine the versatility of the treatment and to elucidate the effect of defects on the oxidation behavior of MWCNTs. The extent of oxidation and nature of functional groups introduced on the nanotube surfaces were determined using Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and Boehm titration, and structural changes were monitored with Raman spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). After only a few minutes of treatment, nongraphitic impurities were removed from the MWCNTs, and significant levels of oxidation (∼8 atom % O) were achieved with very little damage to the nanotube sidewalls. Short O3 exposure resulted in primarily hydroxyl functionalities, whereas longer exposure led to the formation of mainly carboxylic acid groups. Aliphatic defects present in the commercially produced MWCNTs were found to play an important role in the oxidation mechanism. Because of its ability to remove impurities and to evenly oxidize the sidewalls of nanotubes without the use of any solvents, the fluidized O3 reaction developed in this study was found to be an attractive option for industrial-scale MWCNT functionalization.

  2. Combined torsional buckling of multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Lu, Y. J.; Wang, X.

    2006-08-01

    This paper reports the results of an investigation on combined torsional buckling of an individual multi-walled carbon nanotube (MWNT) under combined torque and axial loading. Here, a multiple shell model is adopted and the effect of van der Waals forces between two adjacent tubes is taken into account. According to the ratio of radius to thickness, MWNTs discussed in this paper are classified into three types: thin, thick and nearly solid. The critical shear stress and the combined buckling mode are calculated for three types of MWNTs under combined torque and axial loading. Results carried out show that the buckling mode (m, n) corresponding to the critical shear stress is unique, which is obviously different from the purely axial compression buckling of an individual MWNT. Numerical results also show that the critical shear stresses and the corresponding buckling modes of MWNTs under combined torque and axial loading are dependent on the axial loading form and the types of MWNTs. The new features and meaningful numerical results in the present work on combined buckling of MWNTs under combined torque and axial loading may be used as a useful reference for the designs of nano-drive devices and rotational actuators in which MWNTs act as basic elements.

  3. Functionalized multiwalled carbon nanotubes as ultrasound contrast agents

    PubMed Central

    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

    2012-01-01

    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. PMID:23012426

  4. Radical scavenging reaction kinetics with multiwalled carbon nanotubes

    PubMed Central

    Tsuruoka, Shuji; Matsumoto, Hidetoshi; Koyama, Kenichi; Akiba, Eiji; Yanagisawa, Takashi; Cassee, Flemming R.; Saito, Naoto; Usui, Yuki; Kobayashi, Shinsuke; Porter, Dale W.; Castranova, Vincent; Endo, Morinobu

    2016-01-01

    Progress in the development of carbon nanotubes (CNTs) has stimulated great interest among industries providing new applications. Meanwhile, toxicological evaluations on nanomaterials are advancing leading to a predictive exposure limit for CNTs, which implies the possibility of designing safer CNTs. To pursue safety by design, the redox potential in reactions with CNTs has been contemplated recently. However, the chemical reactivity of CNTs has not been explored kinetically, so that there is no scheme to express a redox reaction with CNTs, though it has been investigated and reported. In addition, the reactivity of CNTs is discussed with regard to impurities that consist of transition metals in CNTs, which obfuscates the contribution of CNTs to the reaction. The present work aimed at modeling CNT scavenging in aqueous solution using a kinetic approach and a simple first-order reaction scheme. The results show that CNTs follow the redox reaction assumption in a simple chemical system. As a result, the reaction with multiwalled CNTs is semi-quantitatively denoted as redox potential, which suggests that their biological reactions may also be evaluated using a redox potential scheme. PMID:27030782

  5. Field Emission Stability of Individual Multi-Walled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Fujieda, Tadashi; Okai, Makoto; Tokumoto, Hiroshi

    2009-02-01

    We investigated the emission stability of individual multi-walled carbon nanotubes (MWNTs) and clarified the mechanism of emission current instability. An initial decrease in the emission current, which is generally seen in the case of metal emitters, was hardly observed. Furthermore, the current fluctuation was much lower than that for a metal emitter, and the peak-to-peak fluctuation was less than 2% when the emission pattern was pentagonal. However, spikelike and steplike noises occurred, with a frequency approximately proportional to the product of the emission current and the background pressure. These noises may be caused by physical adsorption and ion impact desorption of residual gas molecules. The number of these noise events depended on the emission pattern: it was much greater in the case of a nonpentagonal emission pattern than in the case of a pentagonal emission pattern. This type of current noise is considered to be due to ionic-collision-induced damage at the surface of the tip when the emission pattern is nonpentagonal.

  6. 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.

  7. Multi-Walled Carbon Nanotubes Inhibit Breast Cancer Cell Migration.

    PubMed

    Graham, Elizabeth G; Wailes, Elizabeth M; Levi-Polyachenko, Nicole H

    2016-02-01

    According to the American Cancer Society, breast cancer is the second leading cause of cancer death in the US. Cancerous cells may have inadequate adhesions to the extracellular matrix and adjacent cells. Previous work has suggested that restoring these contacts may negate the cancer phenotype. This work aims to restore those contacts using multi-walled carbon nanotubes (MWNTs). Varying concentrations of carboxylated MWNTs in water, with or without type I collagen, were dried to create a thin film upon which one of three breast cell lines were seeded: cancerous and metastatic MDA- MB-231 cells, cancerous but non-metastatic MCF7 cells, or non-cancerous MCF10A cells. Proliferation, adhesion, scratch and autophagy assays, western blots, and immunochemical staining were used to assess adhesion and E-cadherin expression. Breast cancer cells grown on a MWNT-collagen coated surface displayed increased adhesion and decreased migration which correlated with an increase in E-cadherin. This work suggests an alternative approach to cancer treatment by physically mediating the cells' microenvironment.

  8. Multi-walled carbon nanotube-based RF antennas

    NASA Astrophysics Data System (ADS)

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

    2010-01-01

    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.

  9. 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.

  10. Multiwalled carbon nanotube (MWCNT) reinforced cellulose fibers by electrospinning.

    PubMed

    Lu, Ping; Hsieh, You-Lo

    2010-08-01

    Multiwalled carbon nanotubes (MWCNTs) were successfully incorporated in ultrafine cellulose fibers by electrospinning MWCNT-loaded cellulose acetate (CA) solutions, followed by deacetylation of CA to cellulose (cell). The mean fiber diameter reduced from 321 nm of the as-spun fibers to 257 and 228 nm of those with 0.11 and 0.55 wt % MWCNTs, respectively, and became more uniform. Hydrolysis of CA to cell further reduced the mean fiber sizes by another 8-16%. The MWCNTs were observed to be well-aligned along the fiber axes. The MWCNT/cell composite fibers had increased specific surface, from 4.27 m(2)/g to 5.07 and 7.69 m(2)/g at 0.11 and 0.55 wt % MWCNTs, respectively, and much improved water wettability. The mechanical properties of the fibers were also greatly enhanced with increased MWCNT loading levels. The fact that MWCNTs were observed in only about a third of the fibers at a very low 0.55 wt % loading suggests significantly higher tensile strength may be achieved by a further increase in MWCNT loadings.

  11. Spectroscopic investigations on oxidized multi-walled carbon nanotubes

    SciTech Connect

    Anandhi, C. M. S.; Premkumar, S.; Asath, R. Mohamed; Mathavan, T.; Benial, A. Milton Franklin

    2016-05-06

    The pristine multi-walled carbon nanotubes (MWCNTs) were oxidized by the ultrasonication process. The oxidized MWCNTs were characterized by the X-ray diffraction (XRD), ultraviolet–visible (UV-Vis) and Fourier transform -Raman (FT-Raman) spectroscopic techniques. The XRD analysis confirms that the oxidized MWCNTs exist in a hexagonal structure and the sharp XRD peak corresponds to the (002) Bragg’s reflection plane, which indicates that the MWCNTs have higher crystalline nature. The UV-Vis analysis confirms that the MWCNTs functionalized with the carboxylic acid. The red shift was observed corresponds to the D band in the Raman spectrum, which reveals that the reduced disordered graphitic structure of oxidized MWCNTs. The strong Raman peak was observed at 2563 cm{sup -1} corresponds to the overtone of the D band, which is the characteristic vibrational mode of oxidized MWCNTs. The carboxylic acid functionalization of MWCNTs enhances the dispersibility, which paves the way for potential applications in the field of biosensors and targeted drug delivery.

  12. 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

  13. 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

  14. 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

  15. 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.

  16. Axisymmetric and beamlike vibrations of multiwall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Wang, C. Y.; Ru, C. Q.; Mioduchowski, A.

    2005-08-01

    Several vibration problems of multiwall carbon nanotubes (MWNTs) are studied in detail based on a multiple-elastic shell model. According to recent data available in the literature, an updated value of bending stiffness for single-wall carbon nanotubes (SWNTs) is suggested, which is in a much better agreement with atomistic model for phonon-dispersion relation of SWNTs. For axisymmetric vibrations (with circumferential wave number n=0 ), it is found that longitudinal (L) modes of individual tubes of a MWNT have almost identical frequencies and are usually coupled with each other through Poisson-ratio effect-induced radial (R) vibrations and interlayer van der Waals interaction. Especially in the transition zone of R - and L modes, the significant Poisson-ratio effect leads to mixed R-L modes with comparable longitudinal and radial displacements. On the other hand, for beamlike vibrations (with n=1 ), the present multiple-shell model is found to be in good agreement with the multiple-beam model for almost coaxial bending (B) modes of large- and small-radius MWNTs and noncoaxial B modes of small-radius MWNTs (e.g., of the outermost radius less than 2nm ), with relative errors less than 10%. However, for high-order noncoaxial modes of large-radius MWNTs, the relative errors between the two models increase up to 50% in extreme cases due to larger non-beamlike deformation of the cross section while both models give similar overall vibration modes through the entire length of MWNTs. In particular, for lower circumferential wave numbers (n=0-10) , the lowest frequency always corresponds to the minimum half-axial wave number m=1 for simply supported end conditions. When the wave vector decreases, the lowest frequency decreases and the associated mode shifts from an R mode with larger n to a coaxial B mode with n=1 .

  17. 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.

  18. The Electrical Properties of Hybrid Composites Based on Multiwall Carbon Nanotubes with Graphite Nanoplatelets

    NASA Astrophysics Data System (ADS)

    Perets, Yulia; Aleksandrovych, Lyudmila; Melnychenko, Mykola; Lazarenko, Oleksandra; Vovchenko, Lyudmila; Matzui, Lyudmila

    2017-06-01

    In the present work, we have investigated the concentration dependences of electrical conductivity of monopolymer composites with graphite nanoplatelets or multiwall carbon nanotubes and hybrid composites with both multiwall carbon nanotubes and graphite nanoplatelets. The latter filler was added to given systems in content of 0.24 vol%. The content of multiwall carbon nanotubes is varied from 0.03 to 4 vol%. Before incorporation into the epoxy resin, the graphite nanoplatelets were subjected to ultraviolet ozone treatment for 20 min. It was found that the addition of nanocarbon to the low-viscosity suspension (polymer, acetone, hardener) results in formation of two percolation transitions. The percolation transition of the composites based on carbon nanotubes is the lowest (0.13 vol%).

  19. 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.

  20. Self-assembly of single-walled carbon nanotubes into multiwalled carbon nanotubes in water: molecular dynamics simulations.

    PubMed

    Zou, Jian; Ji, Baohua; Feng, Xi-Qiao; Gao, Huajian

    2006-03-01

    We report discoveries from a series of molecular dynamics simulations that single-walled carbon nanotubes, with different diameters, lengths, and chiralities, can coaxially self-assemble into multiwalled carbon nanotubes in water via spontaneous insertion of smaller tubes into larger ones. The assembly process is tube-size-dependent, and the driving force is primarily the intertube van der Waals interactions. The simulations also suggest that a multiwalled carbon nanotube may be separated into single-walled carbon nanotubes under appropriate solvent conditions. This study suggests possible bottom-up self-assembly routes for the fabrication of novel nanodevices and systems.

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

    USDA-ARS?s Scientific Manuscript database

    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...

  2. 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 ENVIRONMENTAL...

  3. 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

  4. Multiwalled carbon nanotube filter: improving viral removal at low pressure.

    PubMed

    Brady-Estévez, Anna S; Schnoor, Mary H; Vecitis, Chad D; Saleh, Navid B; Elimelech, Menachem

    2010-09-21

    The effective removal of viruses by a multiwalled carbon nanotube (MWNT) filter is demonstrated over a range of solution chemistries. MS2 bacteriophage viral removal by the MWNT filter was between 1.5 and 3 log higher than that observed with a recently reported single-walled carbon nanotube (SWNT) filter when examined under similar loadings (0.3 mg/cm(2)) of carbon nanotubes (CNTs). The greater removal of viruses by the MWNT filter is attributed to a more uniform CNT-filter matrix that allows effective removal of viruses by physicochemical (depth) filtration. Viral removal by the MWNT filter was examined under a broad range of water compositions (ionic strength, monovalent and divalent salts, solution pH, natural organic matter, alginate, phosphate, and bicarbonate) and filter approach velocities (0.0016, 0.0044, and 0.0072 cm/s). Log viral removal increased as the fluid approach velocity decreased, exhibiting a dependence on approach velocity in agreement with colloid filtration theory for Brownian particles. Viral removal improved with increasing ionic strength (NaCl), from 5.06 log removal at 1 mM NaCl to greater than 6.56 log removal at 100 mM NaCl. Addition of calcium ions also enhanced viral removal, but the presence of magnesium ions resulted in a decrease in viral removal. Solution pH also played an important role in viral removal, with log removals of 8.13, 5.38, and 4.00 being documented at solution pH values of 3.0, 5.5, and 9.0, respectively. Dissolved natural organic matter (NOM) had a negligible effect on viral removal at low concentration (1 mg/L), but higher concentrations of NOM significantly reduced the viral removal by the MWNT filter, likely due to steric repulsion. Addition of alginate (model polysaccharide) also caused a marked decrease in viral removal by the MWNT filter. This highly scalable MWNT-filter technology at gravity-driven pressures presents new, cost-effective options for point-of-use filters for viral removal.

  5. Wetting behavior of multi-walled carbon nanotube nanofluids.

    PubMed

    Karthikeyan, A; Coulombe, S; Kietzig, A M

    2017-03-10

    Nanofluids-engineered colloidal suspensions in base liquids-have captivated the interest of researchers over the last two decades for various existing as well as emerging technological applications. The main impetus for the synthesis of such novel nanocomposite liquids is the potential to alter properties of the base liquid, such as its viscosity, thermal conductivity, and surface tension, and to introduce specific optical and magnetic properties. Numerous studies suggest trends and explanations for the effects associated with the addition of nanoparticles, and that deviation from the base liquid properties are dependent on nanoparticle concentration. However, there remains a certain ambiguity in the available literature. The wetting behavior and surface tension of nanofluids are particular examples where highly conflicting results exist. In this study, we used multi-walled carbon nanotubes (MWCNTs) functionalized by plasma treatment and dispersed in reverse osmosis water and 99% anhydrous ethanol. Our observations reveal that the surface tension and wetting behavior of the stable aqueous and ethanol-based nanofluids containing plasma functionalized MWCNTs are unaffected by the MWCNT loading up to 120 (0.012) and ∼210 (0.021) ppm (vol%), respectively. The ethanol-based MWCNT nanofluids allowed us to extend the study to higher loadings, and a linear increase of the surface tension past ∼200 ppm was observed. Conversely, nanofluids containing non-functionalized or surfactant-stabilized MWCNTs show drastically different contact angle values when compared to the base liquids even at very low concentrations (less than 100 ppm). We demonstrate that the stability of nanofluid and method of stabilization are crucial parameters in determining the wetting behavior of nanofluids.

  6. Wetting behavior of multi-walled carbon nanotube nanofluids

    NASA Astrophysics Data System (ADS)

    Karthikeyan, A.; Coulombe, S.; Kietzig, A. M.

    2017-03-01

    Nanofluids—engineered colloidal suspensions in base liquids—have captivated the interest of researchers over the last two decades for various existing as well as emerging technological applications. The main impetus for the synthesis of such novel nanocomposite liquids is the potential to alter properties of the base liquid, such as its viscosity, thermal conductivity, and surface tension, and to introduce specific optical and magnetic properties. Numerous studies suggest trends and explanations for the effects associated with the addition of nanoparticles, and that deviation from the base liquid properties are dependent on nanoparticle concentration. However, there remains a certain ambiguity in the available literature. The wetting behavior and surface tension of nanofluids are particular examples where highly conflicting results exist. In this study, we used multi-walled carbon nanotubes (MWCNTs) functionalized by plasma treatment and dispersed in reverse osmosis water and 99% anhydrous ethanol. Our observations reveal that the surface tension and wetting behavior of the stable aqueous and ethanol-based nanofluids containing plasma functionalized MWCNTs are unaffected by the MWCNT loading up to 120 (0.012) and ∼210 (0.021) ppm (vol%), respectively. The ethanol-based MWCNT nanofluids allowed us to extend the study to higher loadings, and a linear increase of the surface tension past ∼200 ppm was observed. Conversely, nanofluids containing non-functionalized or surfactant-stabilized MWCNTs show drastically different contact angle values when compared to the base liquids even at very low concentrations (less than 100 ppm). We demonstrate that the stability of nanofluid and method of stabilization are crucial parameters in determining the wetting behavior of nanofluids.

  7. 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.

  8. 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.

  9. 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.

  10. CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: Magnetoresistance of Multiwalled Carbon Nanotube Yarns

    NASA Astrophysics Data System (ADS)

    Sheng, Lei-Mei; Gao, Wei; Cao, Shi-Xun; Zhang, Jin-Cang

    2008-09-01

    We measure zero-Geld resistivity and magnetoresistance of multiwalled carbon nanotube yarns (CNTYs). The CNTYs are drawn from superaligned multiwalled carbon nanotube arrays synthesized by the low-pressure chemical vapour deposition method. The zero-Geld resistivity shows a logarithmic decrease from 2K to 300 K. In the presence of a magnetic Geld applied perpendicular to the yarn axis, a pronounced negative magnetoresistance is observed. A magnetoresistance ratio of 22% is obtained. These behaviours can be explained by the weak localization effect.

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

    SciTech Connect

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

    2016-05-23

    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.

  12. 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...

  13. 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...

  14. 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.

  15. A comparative study of EMI shielding properties of carbon nanofiber and multi-walled carbon nanotube filled polymer composites.

    PubMed

    Yang, Yonglai; Gupta, Mool C; Dudley, Kenneth L; Lawrence, Roland W

    2005-06-01

    Electromagnetic interference shielding properties of carbon nanofiber- and multi-walled carbon nanotube-filled polystyrene composites were investigated in the frequency range of 8.2-12.4 GHz (X-band). It was observed that the shielding effectiveness of composites was frequency independent, and increased with the increase of carbon nanofiber or nanotube loading. At the same filler loading, multi-walled carbon nanotube-filled polystyrene composites exhibited higher shielding effectiveness compared to those filled with carbon nanofibers. In particular, carbon nanotubes were more effective than nanofibers in providing high EMI shielding at low filler loadings. The experimental data showed that the shielding effectiveness of the composite containing 7 wt% carbon nanotubes could reach more than 26 dB, implying that such a composite can be used as a potential electromagnetic interference shielding material. The dominant shielding mechanism of carbon nanotube-filled polystyrene composites was also discussed.

  16. 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

  17. 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...

  18. 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.

  19. 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

    2010-12-07

    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.

  20. 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.

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

    USDA-ARS?s Scientific Manuscript database

    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...

  2. Highly water-soluble multi-walled carbon nanotubes amine-functionalized by supercritical water oxidation.

    PubMed

    Chun, Kyoung-Yong; Moon, In-Kyu; Han, Joo-Hee; Do, Seung-Hoe; Lee, Jin-Seo; Jeon, Seong-Yun

    2013-11-07

    Multi-walled carbon nanotubes (MWNTs) have been amine-functionalized by eco-friendly supercritical water oxidation. The facilely functionalized MWNTs have high solubility (~84 mg L(-1)) in water and 78% transmittance at 30-fold dilution. The Tyndall effect is also shown for several liquids.

  3. 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...

  4. 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...

  5. 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.

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

    PubMed

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

    2011-10-28

    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.

  7. 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.

  8. 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.

  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. The sensor based on oxidized multi-walled carbon nanotubes prepared by electrochemical method and its application

    NASA Astrophysics Data System (ADS)

    Song, Y. Z.; Yang, L.; Jiang, Q. Y.

    2015-07-01

    The sensor based on oxidized multi-walled carbon nanotubes was prepared by electrochemical method. The behavior of norepinephrine tartrate at the modified electrode was studied. It was demonstrated that modified sensor is a good electrocatalyst for norepinephrine tartrate.

  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. 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.

  13. Fabrication of one-dimensional Ag/multiwalled carbon nanotube nano-composite

    PubMed Central

    2012-01-01

    Composite made of multiwalled carbon nanotubes coated with silver was fabricated by an electroless deposition process. The thickness of silver layer is about 40 to 60 nm, characterized as nano-crystalline with (111) crystal orientation along the nanotube's axial direction. The characterization of silver/carbon nanotube [Ag/CNT] nanowire has shown the large current carrying capability, and the electric conductivity is similar to the pure silver nanowires that Ag/CNT would be promising as building blocks for integrated circuits. PACS: 81.05.uj, carbon nanotubes, carbon-based materials, diamond/nanocarbon composites. PMID:22444640

  14. 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

  15. 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.

  16. Intercalation of WF 6 in the interlayer space of multiwall carbon nanotubes—structural and morphological aspects

    NASA Astrophysics Data System (ADS)

    Claves, D.; Giraudet, J.; Schouler, M. C.; Gadelle, P.; Hamwi, A.

    2004-04-01

    The reactivity of multiwall carbon nanotubes toward WF 6, a strong Lewis acid, has been studied. A material of nominal composition C 36WF 6 has been obtained and characterized by X-ray diffraction. Intercalation between pseudo-graphitic layers has been evidenced, leading to a staging phenomenon at the nanometer scale. A structural model is proposed and the intercalation chemistry of multiwalled carbon nanotubes is discussed.

  17. 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.

  18. 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.

  19. Low temperature growth of carbon nanotubes with aligned multiwalls by microwave plasma-CVD

    NASA Astrophysics Data System (ADS)

    Roy, Ajay; Das, Debajyoti

    2017-05-01

    Multiwall carbon nanotubes (MW-CNTs) have been prepared in a microwave-plasma enhanced CVD (MW-PECVD) tubular system at a low temperature ˜300 °C from CH4-H2 plasma with the addition of CO2 using as a week oxidant to selectively remove the amorphous carbon component and promote the CNT growth. CNTs are typically with outer diameter ˜20 nm, inner diameter ˜10 nm of several μm in length and are grown via the tip growth process, bearing Fe catalyst nano-particles at the tip. The presence of CO2 as a weak oxidant in the plasma may influence in reducing the size of the support catalyst nano-particles and narrowing the CNTs with aligned multiwalls.

  20. Immobilization of Bovine Serum Albumin Upon Multiwall Carbon Nanotube for High Speed Humidity Sensing Application.

    PubMed

    Bhattacharya, Sankhya; Sasmal, Milan

    2016-01-01

    We present a high-speed humidity sensor based on immobilization of bovine serum albumin upon multiwall carbon nanotube (IBC). A simple and versatile drop casting technique was employed to make the humidity sensor using novel material IBC at room temperature. IBC was synthesized using easy solution process technique. The working principle of the IBC humidity sensor depends upon the variation of output current or conductance with the exposure of different humidity level. Humidity sensing properties of our device is explained on the basis of charge transfer from water molecules to IBC and bovine serum albumin to multiwall carbon nanotube (MWCNT). Our sensor exhibits faster response time around 1.2 s and recovery time 1.5 s respectively.

  1. Electrochemical reduction of nalidixic acid at glassy carbon electrode modified with multi-walled carbon nanotubes.

    PubMed

    Patiño, Yolanda; Pilehvar, Sanaz; Díaz, Eva; Ordóñez, Salvador; De Wael, Karolien

    2017-02-05

    The aqueous phase electrochemical degradation of nalidixic acid (NAL) is studied in this work, using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) as instrumental techniques. The promotional effect of multi-walled carbon nanotubes (MWCNT) on the performance of glassy carbon electrodes is demonstrated, being observed that these materials catalyze the NAL reduction. The effect of surface functional groups on MWCNT -MWCNT-COOH and MWCNT-NH2-was also studied. The modification of glassy carbon electrode (GCE) with MWCNT leads to an improved performance for NAL reduction following the order of MWCNT>MWCNT-NH2>MWCNT-COOH. The best behavior at MWCNT-GCE is mainly due to both the increased electrode active area and the enhanced MWCNT adsorption properties. The NAL degradation was carried out under optimal conditions (pH=5.0, deposition time=20s and volume of MWCNT=10μL) using MWCNT-GCE obtaining an irreversible reduction of NAL to less toxic products. Paramaters as the number of DPV cycles and the volume/area (V/A) ratio were optimized for maximize pollutant degradation. It was observed that after 15 DPV scans and V/A=8, a complete reduction was obtained, obtaining two sub-products identified by liquid chromatography-mass spectrometry (LC-MS).

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

    DOE PAGES

    Yue, Yanfeng; Guo, Bingkun; Qiao, Zhenan; ...

    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.

  3. Mechanical instabilities of individual multiwalled carbon nanotubes under cyclic axial compression.

    PubMed

    Yap, Hsao W; Lakes, Roderic S; Carpick, Robert W

    2007-05-01

    Individual multiwalled carbon nanotubes with a range of aspect ratios are subjected to cyclic axial compression to large strains using atomic force microscopy. Distinct elastic buckling and post-buckling phenomena are observed reproducibly and are ascribed to Euler, asymmetric shell buckling (i.e., kinking), and symmetric shell buckling. These show agreement with continuum theories that range from approximate to remarkable. Shell buckling yields reproducible incremental negative stiffness in the initial post-buckled regime.

  4. 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.

  5. 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.

  6. Influence of melt annealing on rheological and electrical properties of compatibilized multiwalled carbon nanotubes in polypropylene

    NASA Astrophysics Data System (ADS)

    Nasti, Giuseppe; Ambrogi, Veronica; Cerruti, Pierfrancesco; Gentile, Gennaro; Di Maio, Rosa; Carfagna, Cosimo

    2014-05-01

    Pristine and surface functionalized multiwalled carbon nanotubes (MWCNT) were melt mixed with a polypropylene (PP) polymer matrix. Rheology, morphology, electrical conductivity and mechanical properties of the nanocomposites were evaluated for different MWCNT loadings. Melt annealing effect on properties was also investigated. It was found that both surface functionalization of MWCNT and thermal annealing were able to favor a better dispersion of the particles, inducing the formation of a percolative network.

  7. High Yield Magnetic Nanoparticles Filled Multiwalled Carbon Nanotubes Using Pulsed Laser Deposition

    DTIC Science & Technology

    2008-08-01

    step procedure to fill vertically aligned multiwalled carbon nanotubes (MWNTs) with cobalt - ferrite using pulsed laser deposition (PLD). There has...been a previous attempt to fill MWNTs in aqueous suspension with cobalt ferrite [3]. Recently, we reported successful chemical filling of CNTs with...majority of the tubes are aligned vertically, a few are misaligned. In Fig. 2, SEM of vertical tubes after being filled with cobalt ferrite is shown

  8. 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.

  9. Interaction of multi-walled carbon nanotubes with water-soluble proteins: effect of sidewall carboxylation.

    PubMed

    Takada, Tomoya; Kurosaki, Rei; Konno, Yuji; Abe, Shigeaki

    2014-04-01

    Effect of sidewall carboxylation on protein adsorption behavior of multi-walled carbon nanotubes (MWCNTs) was studied. Two water-soluble proteins, bovine serum albumin (BSA) and egg white lysozyme (LYS), were employed in this work. Carboxylation of MWCNTs suppressed adsorption of BSA, whereas adsorption of LYS was enhanced by the carboxylation. These behaviors are explained by the difference in the dominance of hydrophobic interaction and ionic interaction between MWCNTs and the proteins.

  10. 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.

  11. 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.

  12. Supramolecular modification of multi-walled carbon nanotubes with β-cyclodextrin for better dispersibility

    NASA Astrophysics Data System (ADS)

    He, Yi; Xu, Zhonghao; Yang, Qiangbin; Wu, Feng; Liang, Lv

    2015-01-01

    A novel hybrid material based on multi-walled carbon nanotubes was synthesized using organic synthesis, and the structures of multi-walled carbon nanotube derivatives were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, 1H NMR spectroscopy, transmission electron microscopy, and scanning electron microscope. The analytical results indicated that β-cyclodextrin (β-CD) was anchored to the surface of Multi-walled carbon nanotubes (MWCNTs, OD: 10-20 nm, length: 10-30 μm) and dispersion experiments exhibited that the introduction of β-CD onto the MWCNTs would dramatically enhance the dispersion of MWCNTs in both ethanol and water media; the suspensions were found to be very stable for 2 months, and the results of this technique confirmed the experimental results. This novel technique would provide a new, simple, and facile route to prepare the modified nanomaterials based on silane-coupling agent and β-CD, and the obtained modified nanomaterials have great potential practical significance and theoretical value to develop the novel organic-inorganic hybrid material, which was very useful for water treatment and biological medicine.

  13. 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.

  14. Fabrication and mechanical properties of multiwalled carbon nanotube/nanonickel reinforced epoxy resin composites

    NASA Astrophysics Data System (ADS)

    Zhang, Xiwen; Zhao, Dongyu; Luan, Dongxue; Bi, Changlong

    2016-12-01

    Nanonickel is supported on the surface of the multiwalled carbon nanotubes (MWCNTs), forming the multiwalled carbon nanotubes/nanonickel composites (MWCNTs/Ni). By using the emulsifying machine dispersing MWCNTs/Ni evenly among epoxy resin, which is prepared into epoxy resin/multiwalled carbon nanotubes/nanonickel (EP/MWCNTs/Ni) composite materials. Additionally, the observed strong interfacial interaction between MWCNTs and the epoxy resin matrix is responsible for the enhanced mechanical properties based on the analysis from scanning electron microscope. Experimental results based on the analysis from dynamic mechanical analysis (DMA) indicate a significant improvement in the glass transition temperature (Tg) by around 20 °C upon the addition of 1.5 wt% MWCNTs/Ni to the epoxy matrix. The tensile strength and the impact strength of the composites can improve around 64.8 and 176.7% compared with that of cured pure epoxy and improve with increasing MWCNTs/Ni content up to 1.3 wt%. Finally, the excellent mechanics capability of EP/MWCNTs/Ni nanocomposites will provide enormous opportunities for aerospace applications where conductive adhesive or high-performance polymer materials are necessary.

  15. Catalyst-free fabrication of graphene nanosheets without substrates using multiwalled carbon nanotubes and a spark plasma sintering process.

    PubMed

    Ham, Heon; Park, No-Hyung; Kang, Inpil; Kim, Hyoun Woo; Shim, Kwang Bo

    2012-07-07

    Catalyst-free graphene nanosheets without substrates were synthesized using pure solid carbon sources of multiwalled carbon nanotubes (MWCNTs) and a spark plasma sintering (SPS) process. Single and few-hundred-nanometer graphene nanosheets were formed from gas-phase carbon atoms which were directly evaporated from MWCNTs at a local high temperature.

  16. Nanocomposite Prepared from In Situ Grafting of Polypyrrole to Aminobenzoyl-Functionalized Multiwalled Carbon Nanotube and Its Electrochemical Properties

    DTIC Science & Technology

    2011-01-01

    the functionalization of multiwalled car- bon nanotube (MWCNT) with 4-aminobenzoic acid by a ‘‘direct’’ Friedel – Crafts acylation reaction in a mild...functionalization of multiwalled carbon nanotube (MWCNT) with 4-aminobenzoic acid by a ??direct?? Friedel ? Crafts acylation reaction in a mild polyphosphoric...chemical modification of various CNMs by ‘‘direct’’ Friedel – Crafts acylation reaction in a mild polyphosphoric acid (PPA)/ phosphorous pentoxide (P2O5

  17. Electrical Conduction Mechanism in Chemical Vapour Deposition Grown Multi-Wall Carbon Nanotubes Film.

    PubMed

    Al-Hazmi, F S

    2015-07-01

    Multi-walled carbon nanotubes are interesting systems where different aspects of conduction are observed, mostly due to their low dimensionalities and small dimensions. Electrical conduction mechanism in multi wall carbon nanotubes film is studied. The studied multi-walled nanotubes are grown by a low pressure chemical vapour deposition system. To understand the conduction mechanism in these nanotubes, temperature dependence of conductivity of the multi wall nanotubes film over a temperature range of (400-200 K) is studied. On the basis of the results, one may suggest the thermally activated conduction mechanism for the temperature range (400-300 K). The low temperature data is fitted with the hopping conduction for the transport of charge carriers in the temperature range of 300-200 K. This hopping conduction mechanism is characterized by variable range hopping (VRH), which shows complete agreement with the Mott's type of VRH mechanism. Applying this model, a number of Mott's parameters such as density of states, hopping distance, hopping energy are calculated. The calculated values of all the studied parameters matches well the reported results on other multi-wall nanotubes film.

  18. 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}.

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

    NASA Astrophysics Data System (ADS)

    Zhao, Junhua; Lu, Lixin; Rabczuk, Timon

    2014-05-01

    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.

  20. 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.

  1. Effects of strain rates and temperatures on the mechanical properties of multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Chen, X.; Wang, X.; Sheng, G. G.

    2007-04-01

    This paper reports the results of an investigation of the dynamic mechanical properties of multi-walled armchair and zigzag nanotubes under different strain rates and environmental temperatures. Based on a molecular structural mechanics model, the covalent bonds are treated as a two dimensional beam element and van der Waals forces between two adjacent tubes are firstly simulated by a nonlinear spring. The corresponding force constants of bond stretching, bond angle bending and torsional resistance in different environmental temperatures can be, respectively, obtained by computing the variation of chemical bond lengths. The result obtained reveals that the dynamic Young's modulus of the effective nanotube material increases as the strain rate increases, and decreases as the environmental temperature increases; the effect of layer numbers of multi-walled carbon nanotubes (MWCNTs) on the dynamic Young's modulus of the effective nanotube material is dependent on strain rates and environmental temperatures.

  2. Methane preconcentration in a microtrap using multiwalled carbon nanotubes as sorbents.

    PubMed

    Saridara, Chutarat; Ragunath, Smruti; Pu, Yong; Mitra, Somenath

    2010-09-10

    The GC monitoring of green house gases is a challenging task because the concentration of organic species such as methane are relatively low (ppm to ppb) and their analysis requires some level of preconcentration. Since methane is highly volatile, it is not easily retained on conventional sorbents. In this paper we present multiwalled carbon nanotubes (MWNTs) as an effective sorbent for a microtrap designed for methane preconcentration. Its performance was compared to other commercially available carbon based sorbents, and it was found to be the most effective sorbent in terms of breakthrough volume and enthalpy of adsorption.

  3. 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.

  4. Nanomechanical Behavior of Multi-Walled Carbon Nanotubes Particulate Reinforced Aluminum Nanocomposites Prepared by Ball Milling

    PubMed Central

    Ostovan, Farhad; Matori, Khamirul Amin; Toozandehjani, Meysam; Oskoueian, Arshin; Yusoff, Hamdan Mohamed; Yunus, Robiah; Mohamed Ariff, Azmah Hanim

    2016-01-01

    The nanomechanical properties of carbon nanotubes particulate-reinforced aluminum matrix nanocomposites (Al-CNTs) have been characterized using nanoindentation. Bulk nanocomposite specimens containing 2 wt % multiwalled CNTs (MWCNTs) were synthesized by a combination of ball milling and powder metallurgy route. It has been tried to understand the correlation between microstructural evolution particularly carbon nanotubes (CNTs) dispersion during milling and mechanical properties of Al-2 wt % nanocomposites. Maximum enhancement of +23% and +44% has been found in Young’s modulus and hardness respectively, owing to well homogenous dispersion of CNTs within the aluminum matrix at longer milling time. PMID:28773261

  5. Optical and electrical characterizations of nanocomposite film of titania adsorbed onto oxidized multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Feng, Wei; Feng, Yiyu; Wu, Zigang; Fujii, Akihiko; Ozaki, Masanori; Yoshino, Katsumi

    2005-07-01

    Composite film containing titania electrostatically linked to oxidized multiwalled carbon nanotubes (TiO2-s-MWNTs) was prepared from a suspension of TiO2 nanoparticles in soluble carbon nanotubes. The structure of the film was analysed principally by Fourier transform infrared spectroscopy, scanning electron micrography and x-ray diffraction. The optical and electrical characterizations of the film were investigated by UV-vis spectrum, photoluminescence and photoconductivity. The enhancement of photocurrent in the TiO2-s-MWNT film is discussed by taking the photoinduced charge transfer between the MWNT and TiO2 into consideration.

  6. Time and temperature dependence of multi-walled carbon nanotube growth on Inconel 600.

    PubMed

    Pal, S K; Talapatra, S; Kar, S; Ci, L; Vajtai, R; Borca-Tasciuc, T; Schadler, L S; Ajayan, P M

    2008-01-30

    The growth kinetics of vertically aligned multi-walled carbon nanotubes (MWNTs) on conductive substrates is investigated by synthesizing MWNTs at different growth temperatures and measuring ex situ the length of the nanotubes as a function of growth duration. A typical 'root growth' mechanism (saturation of MWNT lengths with increasing growth duration) was observed. The value of the activation energy (E(a)≈136 ± 5 kJ mol(-1)) of the MWNT growth reaction is suggestive of carbon diffusion through the bulk of the iron catalyst particle versus diffusion on its surface. These findings will help in optimizing MWNT growth on conductive substrates for various applications.

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

    PubMed

    Sawaya, Shintaro; Arie, Takayuki; Akita, Seiji

    2011-04-22

    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 sp(2) 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.

  8. Prediction of the critical buckling load of multi-walled carbon nanotubes under axial compression

    NASA Astrophysics Data System (ADS)

    Timesli, Abdelaziz; Braikat, Bouazza; Jamal, Mohammad; Damil, Noureddine

    2017-02-01

    In this paper, we propose a new explicit analytical formula of the critical buckling load of double-walled carbon nanotubes (DWCNT) under axial compression. This formula takes into account van der Waals interactions between adjacent tubes and the effect of terms involving tube radii differences generally neglected in the derived expressions of the critical buckling load published in the literature. The elastic multiple Donnell shells continuum approach is employed for modelling the multi-walled carbon nanotubes. The validation of the proposed formula is made by comparison with a numerical solution. The influence of the neglected terms is also studied.

  9. 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.

  10. 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...

  11. Catalytic systems of cumene oxidation based on multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Kobotaeva, N. S.; Skorokhodova, T. S.; Ryabova, N. V.

    2015-03-01

    Catalytic systems for cumene oxidation were prepared on the basis of silver-activated carbon nanotubes. Silver lies on the surface of the carbon nanotubes in the nanocrystalline state and has a size of 15-20 nm. The use of the obtained catalytic systems in cumene oxidation with molecular oxygen allowed a considerable decrease in the oxidation temperature and an increase in selectivity.

  12. 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...

  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. 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

    2015-07-03

    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.

  15. Nickel oxide nanotube synthesis using multiwalled carbon nanotubes as sacrificial templates for supercapacitor application

    NASA Astrophysics Data System (ADS)

    Abdalla, Ahmed M.; Sahu, Rakesh P.; Wallar, Cameron J.; Chen, Ri; Zhitomirsky, Igor; Puri, Ishwar K.

    2017-02-01

    A novel approach for the fabrication of nickel oxide nanotubes based on multiwalled carbon nanotubes as a sacrificial template is described. Electroless deposition is employed to deposit nickel onto carbon nanotubes. The subsequent annealing of the product in the presence of air oxidizes nickel to nickel oxide, and carbon is released as gaseous carbon dioxide, leaving behind nickel oxide nanotubes. Electron microscopy and elemental mapping confirm the formation of nickel oxide nanotubes. New chelating polyelectrolytes are used as dispersing agents to achieve high colloidal stability for both the nickel-coated carbon nanotubes and the nickel oxide nanotubes. A gravimetric specific capacitance of 245.3 F g-1 and an areal capacitance of 3.28 F cm-2 at a scan rate of 2 mV s-1 is achieved, with an electrode fabricated using nickel oxide nanotubes as the active element with a mass loading of 24.1 mg cm-2.

  16. Nickel oxide nanotube synthesis using multiwalled carbon nanotubes as sacrificial templates for supercapacitor application.

    PubMed

    Abdalla, Ahmed M; Sahu, Rakesh P; Wallar, Cameron J; Chen, Ri; Zhitomirsky, Igor; Puri, Ishwar K

    2017-02-17

    A novel approach for the fabrication of nickel oxide nanotubes based on multiwalled carbon nanotubes as a sacrificial template is described. Electroless deposition is employed to deposit nickel onto carbon nanotubes. The subsequent annealing of the product in the presence of air oxidizes nickel to nickel oxide, and carbon is released as gaseous carbon dioxide, leaving behind nickel oxide nanotubes. Electron microscopy and elemental mapping confirm the formation of nickel oxide nanotubes. New chelating polyelectrolytes are used as dispersing agents to achieve high colloidal stability for both the nickel-coated carbon nanotubes and the nickel oxide nanotubes. A gravimetric specific capacitance of 245.3 F g(-1) and  an areal capacitance of 3.28 F cm(-2) at a scan rate of 2 mV s(-1) is achieved, with an electrode fabricated using nickel oxide nanotubes as the active element with a mass loading of 24.1 mg cm(-2).

  17. 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.

  18. Dielectric characterization of multi-walled carbon nanotube nanocomposites as a function of ultraviolet exposure at microwave frequency

    NASA Astrophysics Data System (ADS)

    Orloff, Nathan; Long, Christian J.; Twedt, Kevin; Lam, Thomas; McClelland, Jabez; Obrzut, Jan; Liddle, J. Alexander

    2014-03-01

    We investigate multi-walled carbon nanotube epoxy composites as a function of ultraviolet exposure. As the epoxy is etched away from the composite, we found that the multi-walled carbon nanotubes form a thin conducting layer on the surface. We then characterize the multi-walled carbon nanotube composites by atomic force microscopy, lithium ion microscopy, and microwave cavity perturbation at each value of ultraviolet exposure. We perform our measurements on a set of neat samples made from a stoichiometric mixture bisphenol A epoxy resin and another set that contains a mass fraction of 3.5% multi-walled carbon nanotubes. The samples were then exposed to ultraviolet radiation to etch the surface for different durations of time. At the 7.31 GHz, we measured the permittivity and loss tangent of the unexposed epoxy to be ɛ = 2.93 +/-0.11 and tan δ = 0.029 +/-0.002, respectively. The unexposed epoxy with a mass fraction of 3.5% multi-walled carbon nanotubes had a permittivity of ɛ = 8.01 +/-0.48 and loss tangent of tan δ = 0.144 +/-0.011.

  19. Vibrational behaviors of multiwalled-carbon-nanotube-based nanomechanical resonators

    NASA Astrophysics Data System (ADS)

    Li, Chunyu; Chou, Tsu-Wei

    2004-01-01

    This letter studies the promising application of carbon nanotubes as nanoresonators. Both single- and double-walled carbon nanotubes are considered and the significant difference in the vibration behavior between them has been identified. The individual tube wall is treated as frame-like structures and simulated by the molecular-structural-mechanics method. The interlayer van der Waals interactions are represented by Lennard-Jones potential and simulated by a nonlinear truss rod model. The results show that fundamental frequencies of double-walled carbon nanotubes are about 10% lower than those of single-walled carbon nanotubes of the same outer diameter. The noncoaxial vibration of double-walled nanotubes begins at the third resonant frequency and does not significantly diminish the value of double-walled nanotubes as high-frequency nanoresonators.

  20. Eradicating group A streptococcus bacteria and biofilms using functionalised multi-wall carbon nanotubes.

    PubMed

    Levi-Polyachenko, Nicole; Young, Christie; MacNeill, Christopher; Braden, Amy; Argenta, Louis; Reid, Sean

    2014-11-01

    The aim of this study was to demonstrate that multi-wall carbon nanotubes can be functionalised with antibodies to group A streptoccocus (GAS) for targeted photothermal ablation of planktonic and biofilm residing bacteria. Antibodies for GAS were covalently attached to carboxylated multi-wall carbon nanotubes and incubated with either planktonic or biofilm GAS. Bacterium was then exposed to 1.3 W/cm(2) of 800 nm light for 10-120 s, and then serially diluted onto agar plates from which the number of colony forming units was determined. Photothermal ablation of GAS on the surface of full thickness ex vivo porcine skin and histological sectioning were done to examine damage in adjacent tissue. Approximately 14% of the GAS antibody-functionalised nanotubes attached to the bacterium, and this amount was found to be capable of inducing photothermal ablation of GAS upon exposure to 1.3 W/cm(2) of 800 nm light. Cell viability was not decreased upon exposure to nanotubes or infrared light alone. Compared to carboxylated multi-wall carbon nanotubes, antibody-labelled nanotubes enhanced killing in both planktonic and biofilm GAS in conjunction with infrared light. Analysis of GAS photothermally ablated in direct contact with ex vivo porcine skin shows that heat sufficient for killing GAS remains localised and does not cause collateral damage in tissue adjacent to the treated area. The results of this study support the premise that carbon nanotubes may be effectively utilised as highly localised photothermal agents with the potential for translation into the clinical treatment of bacterial infections of soft tissue.

  1. 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.

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

    USDA-ARS?s Scientific Manuscript database

    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...

  3. 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.

  4. Multiwall carbon nanotubes doped ferroelectric liquid crystal composites: A study of modified electrical behavior

    NASA Astrophysics Data System (ADS)

    Neeraj; Raina, K. K.

    2014-02-01

    We systematically investigated the role of carbon nanotubes and their nature of interaction with the high polarization ferroelectric liquid crystal molecules that causes a change in the dynamic behavior of the liquid crystals. The carbon nanotubes were functionalized with carboxyl group (-COOH) before dispersion in order to enhance their stability in the liquid crystal medium. For the systematic investigation of a non linear behavior of dispersed composite systems, results for various physical properties were determined by thermal, morphological and dielectric studies in the planer aligned 5 μm thickness cells. An effort has also gone into detail to investigate these properties with varying concentration (0.02 wt%, 0.05 wt% and 0.1 wt%) of multiwall carbon nanotubes. The various carbon nanotubes doped ferroelectric liquid crystal thin film composites have shown enhanced dielectric strength and dielectric permittivity values as compared to the undoped sample.

  5. WS2 layer formation on multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Whitby, R. L. D.; Hsu, W. K.; Boothroyd, C. B.; Brigatti, K. S.; Kroto, H. W.; Walton, D. R. M.

    Time-dependent powder X-ray-diffraction analyses reveal that the conversion of WO3 into WS2 on carbon nanotube surfaces in the presence of H2S is a one-step process. The WS2 layers grow simultaneously along the tube in the radial and axial directions.

  6. Comparison of multiwalled carbon nanotubes and a conventional absorbent on the enrichment of sulfonylurea herbicides in water samples.

    PubMed

    Zhou, Qingxiang; Xiao, Junping; Wang, Weidong

    2007-02-01

    Recently, multiwalled carbon nanotubes (MWCNTs) have been at the center of attention because of their applications in many fields. Efforts to investigate the possibility of MWCNTs as SPE absorbents for the enrichment of environmental pollutants yielded positive results. The goal of the present work was to compare the enrichment power of MWCNTs with that of regular adsorbents, such as C18 silica for SPE of five sulfonylurea herbicides. The results indicated that multiwalled carbon nanotubes were very suitable for the preconcentration of sulfonylurea herbicides in complex water samples, yielding better recoveries. C18 gave a lightly lower enrichment performance, and could not enrich nicosulfuron in complex samples. All of these experimental results indicated that multiwalled carbon nanotubes could be used as a valuable alternative adsorbent for the SPE of sulfonylurea herbicides in many real water samples.

  7. Melt dispersion and electrospinning of non-functionalized multiwalled carbon nanotubes in thermoplastic polyurethane.

    PubMed

    Hunley, Matthew T; Pötschke, Petra; Long, Timothy E

    2009-12-16

    Nanoscale fibers with embedded, aligned, and percolated non-functionalized multiwalled carbon nanotubes (MWCNTs) were fabricated through electrospinning dispersions based on melt-compounded thermoplastic polyurethane/MWCNT nanocomposite, with up to 10 wt.-% MWCNTs. Transmission electron microscopy indicated that the nanotubes were highly oriented and percolated throughout the fibers, even at high MWCNT concentrations. The coupling of efficient melt compounding with electrospinning eliminated the need for intensive surface functionalization or sonication of the MWCNTs, and the high aspect ratio as well as the electrical and mechanical properties of the nanotubes were retained. This method provides a more efficient technique to generate one-dimensional nanofibers with aligned MWCNTs.

  8. Adsorption kinetics, isotherms and thermodynamics of atrazine on surface oxidized multiwalled carbon nanotubes.

    PubMed

    Chen, Guang-Cai; Shan, Xiao-Quan; Zhou, Yi-Quan; Shen, Xiu-e; Huang, Hong-Lin; Khan, Shahamat U

    2009-09-30

    The adsorption kinetics, isotherms and thermodynamic of atrazine on multiwalled carbon nanotubes (MWCNTs) containing 0.85%, 2.16%, and 7.07% oxygen was studied. Kinetic analyses were performed using pseudo-first-order, pseudo-second-order and intraparticle diffusion models. The regression results showed that the pseudo-second-order law fit the adsorption kinetics. The calculated thermodynamic parameters indicated that adsorption of atrazine on MWCNTs was spontaneous and exothermic. Standard free energy (DeltaG(0)) became less negative when the oxygen content of MWCNTs increased from 0.85% to 7.07% which is consistent with the low adsorption affinity of MWCNTs for atrazine.

  9. 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.

  10. 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.

  11. Multiwalled carbon nanotubes for drug delivery: Efficiency related to length and incubation time.

    PubMed

    Sciortino, Niccolò; Fedeli, Stefano; Paoli, Paolo; Brandi, Alberto; Chiarugi, Paola; Severi, Mirko; Cicchi, Stefano

    2017-04-15

    Batches of oxidized multiwalled carbon nanotubes differing in length were adopted to prepare two drug delivery systems (DDS) loaded with doxorubicin. The different internalization of the two batches, verified by atomic emission spectroscopy onto cell lysates, was also confirmed by the different toxicity of the same DDS loaded with doxorubicin. In vitro experiments evidenced, after 48h of incubation, the superior efficacy of the shortest nanotubes. However, upon prolonging the incubation time up to 72h the difference in efficiency was minimized due to the spontaneous release of doxorubicin by the non-internalized long nanotubes. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. 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.

  13. Reinforcement of hydrogenated carboxylated nitrile-butadiene rubber by multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Lu, Lan; Zhai, Yinghao; Zhang, Yong; Ong, Christopher; Guo, Sharon

    2008-12-01

    Hydrogenated carboxylated acrylonitrile-butadiene rubber (HXNBR) and multi-walled carbon nanotubes (MWCNT) composites were prepared. The dispersion of MWCNT in HXNBR matrix was evaluated by field emission scanning electron microscopy. HXNBR/MWCNT composite had shorter scorch time and optimum curing time compared with that of unfilled HXNBR. The tensile strength and modulus of HXNBR/MWCNT composites increased with increasing MWCNT content. Mooney-Rivlin equation was used to describe the stress-strain behavior of unfilled HXNBR and the strain amplification factor was taken into account for HXNBR/MWCNT composites. The Mullins effect and dynamic mechanical properties of HXNBR/MWCNT composite were also investigated.

  14. 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.

  15. High performance dye-sensitized solar cell based on hydrothermally deposited multiwall carbon nanotube counter electrode

    NASA Astrophysics Data System (ADS)

    Siriroj, Sumeth; Pimanpang, Samuk; Towannang, Madsakorn; Maiaugree, Wasan; Phumying, Santi; Jarernboon, Wirat; Amornkitbamrung, Vittaya

    2012-06-01

    Conductive glass was coated with multiwall carbon nanotubes (MWCNTs) by a hydrothermal method. MWCNTs films were subsequently used as dye-sensitized solar cell (DSSC) counter electrodes. The performance of hydrothermal MWCNT DSSC was ˜2.37%. After film annealing in an Ar atmosphere, annealed-hydrothermal MWCNT (AHT-CNT) DSSC efficiency was significantly increased to ˜7.66%, in comparison to ˜8.01% for sputtered-Pt DSSC. Improvement of AHT-CNT DSSC performance is attributed to a decrease in charge-transfer resistance from 1500 Ω to 30 Ω as observed by electrochemical impedance spectroscopy.

  16. 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.

  17. Synthesis of Ru/multiwalled carbon nanotubes by microemulsion for electrochemical supercapacitor

    SciTech Connect

    Yan Shancheng; Qu Peng; Wang Haitao; Tian Tian; Xiao Zhongdang

    2008-10-02

    An efficient way to decorate multiwalled carbon nanotubes with Ru had been developed. In this method, Ru nanoparticles were prepared by water-in-oil reverse microemulsion, and the produced Ru anchored on MWCNTs. Transmission electron microscopy (TEM) result showed that RuO{sub 2} nanoparticles had the uniform size distribution after electrochemical oxidation. Energy dispersive X-rays (EDX) spectra elucidated the presence of ruthenium oxide in the as-prepared composites after electrochemical oxidation. Cyclic voltammetry result demonstrated that a specific capacitance of deposited ruthenium oxide electrode was significantly greater than that of the pristine MWCNTs electrode in the same medium.

  18. Transmission electron microscopic observation of cells cultured on multiwalled carbon nanotube-coated sponges.

    PubMed

    Hirata, Eri; Sakaguchi, Norihito; Uo, Motohiro; Ushijima, Natsumi; Nodasaka, Yoshinobu; Watari, Fumio; Ichinose, Hideki; Yokoyama, Atsuro

    2010-01-01

    The cell structure and interface between cultured cells and a multiwalled carbon nanotube (MWCNT)-coated sponge (MWCNT-coated sponge) were observed by transmission electron microscopy (TEM). Moreover, the atomic structure of MWCNTs that entered the cells was also examined by means of high-resolution TEM (HRTEM). MWCNTs were observed in the cytoplasm, and a few MWCNTs were recognized in the cell nuclei. Those MWCNTs maintained their structure there. Subcellular organelles did not appear to be different from those on the collagen sponge despite the cellular uptake of MWCNTs.

  19. 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.

  20. 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.

  1. Evaluation of a cesium iodide photocathode assisted with MgO-coated multiwall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Lee, Jungwoo; Park, Taehee; Lee, Wonjoo; Park, Eunkyung; Lee, Donghwan; Han, Bongwoo; Han, Sung-Hwan; Yi, Whikun

    2010-04-01

    This paper reports the enhanced photocurrent and relative quantum efficiency of cesium iodide (CsI) films on magnesium oxide (MgO)-coated multiwall carbon nanotubes (MWCNTs) on a silica substrate, i.e., CsI/MgO/MWCNTs/Si, when illuminating with 147 nm photons under an external electric field. The incorporation of MWCNTs resulted in significant enhancement of the photocurrent by several orders of magnitude compared to that of a conventional CsI. An analysis of the photoelectron energy spectrum attributed the phenomena to the creation of a very high electric field through the MgO/CsI film with the subsequent generation of avalanche secondary electrons.

  2. Size of the localized electron emission sites on a closed multiwalled carbon nanotube.

    PubMed

    Heeres, Erwin C; Oosterkamp, Tjerk H; de Jonge, Niels

    2012-01-20

    We have measured the size of the localized electron emission sites on multiwalled carbon nanotubes (MWNTs) with caps closed by a fullerenelike structure. MWNTs were individually mounted on tungsten support tips and imaged with a field emission microscope (FEM). The magnification of the FEM was calibrated using electron ray tracing and verified by comparing transmission electron microscope images. The FEM image was also tested for effects of the lateral energy spread. We found ring-shaped emission areas with three flattened sides, of a radius of 1.7±0.3 nm, and separated by 5±1 nm. © 2012 American Physical Society

  3. Effect of purification of the electrical conductivity and complex permittivity of multiwall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Grimes, C. A.; Dickey, E. C.; Mungle, C.; Ong, K. G.; Qian, D.

    2001-10-01

    In this work we report on the complex permittivity spectra and electrical conductivity of both as-fabricated and graphitized multiwall carbon nanotubes (MWNTs). The high-temperature annealing removes the Fe3C catalyst particles present in the as-fabricated material, enabling the intrinsic MWNT properties to be measured. The permittivity spectra of 1 wt % MWNT-polystyrene composite films are measured from 75 to 1875 MHz. Comparison of measurements with an appropriate effective medium model shows that the residual catalyst inclusions in the core of the nanotube increase the average electrical conductivity by approximately a factor of 3.5.

  4. 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.

  5. 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.

  6. 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.

  7. Controlling the site density of multiwall carbon nanotubes via growth conditions

    NASA Astrophysics Data System (ADS)

    Siegal, M. P.; Overmyer, D. L.; Kaatz, F. H.

    2004-06-01

    We present two complementary methods for controlling the site density of multiwall carbon nanotubes (CNTs) directly as a function of growth conditions from 1011to107CNTs/cm2. Several potential applications require significant spacing between individual CNTs. The first method shows that the site density varies with the heat of formation of the hydrocarbon gas used during CNT growth by thermal chemical vapor deposition. The second method demonstrates that the site density decreases with increasing residual stress of the metal catalyst/diffusion barrier layers. These methods are combined for wide-range control of CNT site density.

  8. 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.%.

  9. Electron scattering in a multiwall carbon nanotube bend junction studied by scanning tunneling microscopy

    NASA Astrophysics Data System (ADS)

    Tapasztó, L.; Nemes-Incze, P.; Osváth, Z.; Darabont, Al.; Lambin, Ph.; Biró, L. P.

    2006-12-01

    The atomic resolution scanning tunneling microscopy investigation of a multiwall carbon nanotube bend junction is reported. Atomic resolution images taken at the junction region revealed position-dependent modulation of the electronic density of states, with a period larger than but commensurate to the underlying atomic lattice, attributed to the scattering of electrons on defect sites present in the junction region. We propose an interference model, suitable to interpret the experimentally observed electron density patterns by considering electronic states near the bands crossing points involved in the scattering processes. The model predicts that complex charge density oscillations present near defects are tunable by varying the applied bias potential.

  10. Experimental determination of the spring constant of an individual multiwalled carbon nanotube cantilever using fluorescence measurement

    NASA Astrophysics Data System (ADS)

    Kwon, Soongeun; Park, Hyojun; Shim, Hyung Cheoul; Lee, Hyung Woo; Kwak, Yoon Keun; Kim, Soohyun

    2009-07-01

    We report an experimental method to determine the spring constant of a multiwalled carbon nanotube (MWNT) cantilever as a mechanical piconewton force transducer. Electrostatic actuation was employed to investigate the mechanical properties of a MWNT cantilever. In order to measure nanotube's deflection during actuation, fluorescent dyes were noncovalently attached to the end of the nanotubes. Also, the length dependence of the spring constant is studied by adjusting the length of MWNT via electrochemical etching. The results show that the spring constant of a MWNT cantilever is as small as 0.001 N/m and tunable in the range of 0.001-0.05 N/m.

  11. Dielectric properties of WS2-coated multiwalled carbon nanotubes studied by energy-loss spectroscopic profiling

    NASA Astrophysics Data System (ADS)

    Stolojan, Vlad; Silva, S. R. P.; Goringe, Michael J.; Whitby, R. L. D.; Hsu, Wang K.; Walton, D. R. M.; Kroto, Harold W.

    2005-02-01

    We investigate experimentally the electronic properties of the coating for multiwalled carbon nanotubes covered in tungsten disulfide (WS2) of various thicknesses. Coatings of thicknesses between 2 and 8 monolayers (ML) are analyzed using energy-loss spectroscopic profiling (ELSP), by studying the variations in the plasmon excitations across the coated nanotube, as a function of the coating thickness. We find a change in the ELSP for coatings above 5 ML thickness, which we interpret in terms of a change in its dielectric properties.

  12. Control of tunnel barriers in multi-wall carbon nanotubes using focused ion beam irradiation.

    PubMed

    Tomizawa, H; Suzuki, K; Yamaguchi, T; Akita, S; Ishibashi, K

    2017-04-21

    We have formed tunnel barriers in individual multi-wall carbon nanotubes using the Ga focused ion beam irradiation. The barrier height was estimated by the temperature dependence of the current (Arrhenius plot) and the current-voltage curves (Fowler-Nordheim plot). It is shown that the barrier height has a strong correlation with the barrier resistance that is controlled by the dose. Possible origins for the variation in observed barrier characteristics are discussed. Finally, the single electron transistor with two barriers is demonstrated.

  13. Competition between magnetic field dependent band structure and coherent backscattering in multiwall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Stojetz, B.; Roche, S.; Miko, C.; Triozon, F.; Forró, L.; Strunk, C.

    2007-03-01

    Magnetotransport measurements in large diameter multiwall carbon nanotubes (20 40 nm) demonstrate the competition of a magnetic-field dependent bandstructure and Altshuler Aronov Spivak oscillations. By means of an efficient capacitive coupling to a backgate electrode, the magnetoconductance oscillations are explored as a function of Fermi level shift. Changing the magnetic field orientation with respect to the tube axis and by ensemble averaging, allows the contributions of different Aharonov Bohm phases to be identified. The results are in qualitative agreement with numerical calculations of the band structure and the conductance.

  14. 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.

  15. Plasma treatment of multiwall carbon nanotubes for dispersion improvement in water

    SciTech Connect

    Chen Changlun; Ogino, Akihisa; Nagatsu, Masaaki; Wang Xiangke

    2010-03-29

    Microwave excited Ar/H{sub 2}O surface-wave plasma was used to treat multiwall carbon nanotubes (MWCNTs) to modify their surface characteristics and thus improve their dispersion capability in water. Changes in the atom composition and structure properties of MWCNTs were analyzed using x-ray photoelectron spectroscopy and Raman spectroscopy, and the surface morphology of MWCNTs was observed by field emission scanning electron microscopy and scanning transmission electron microscopy. The results indicated that Ar/H{sub 2}O plasma treatment greatly enhanced the content of oxygen, and modified surface microstructure properties. The integrity of nanotube patterns, however, was not damaged.

  16. 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.

  17. Self-assembly formation of multi-walled carbon nanotubes on gold surfaces.

    PubMed

    Lin, Jarrn-Horng; Chen, Ching-Shiun; Rümmeli, Mark H; Zeng, Zhi-Yan

    2010-12-01

    We report on the observation of self-assembled carbon nanostructures on a standard transmission electron microscopy (TEM) Au substrate formed via thermal chemical vapor deposition. Multi-walled carbon nanotubes (MWNTs) and other carbon nanostructures (CNs), such as carbon nanofibers and carbon nanoparticles (NPs), could be fabricated through structural transformation of metastable carbon layers on the Au surface during 800-850 °C with the thermal decomposition of ethylene. At these temperatures, we found that Au NPs will form immediately through the structural transformation of the Au grid surface in helium atmosphere. The Au NPs work as active centers to trigger the decomposition of ethylene into carbon atoms, which form metastable carbon layers or amorphous carbon nanobugs, and then form CNs via self-assembling. The growth of CNs was characterized by field-emission scanning electron microscopy (SEM), high-resolution TEM and RAMAN spectroscopy. The transformation of amorphous carbon nanobugs by electron beam irradiation is also recorded by in situ monitoring of TEM.

  18. 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%.

  19. Highly electroconductive multiwalled carbon nanotubes as potentially useful tools for modulating calcium balancing in biological environments.

    PubMed

    Serafino, Annalucia; Togna, Anna Rita; Togna, Giuseppina I; Lisi, Antonella; Ledda, Mario; Grimaldi, Settimio; Russier, Julie; Andreola, Federica; Monthioux, Marc; Béguin, Francois; Marcaccio, Massimo; Rapino, Stefania; Paolucci, Francesco; Fiorito, Silvana

    2012-04-01

    Aiming to explore the mechanisms modulating cell-carbon nanotube interactions, we investigated whether Ca(2+) ion balancing between intra- and extracellular environments could be affected by multiwalled carbon nanotubes (MWCNTs). We analyzed the effects induced by two different kinds of MWCNTs (as prepared and annealed at 2400°C) on the intracellular Ca(2+) ion levels in rat electrically sensitive cells and on the intercellular junction integrity of rat adenocarcinoma colon cells and platelet aggregation ability, which depend on the Ca(2+) concentration in the medium. MWCNTs, purified by annealing and more electroconductive as compared to nonannealed MWCNTs, affected Ca(2+) ion balancing between extra- and intracellular environments and induced changes on Ca(2+) ion-dependent cellular junctions and platelet aggregation, behaving as the calcium chelator ethylene glycol tetraacetic acid. This could be due to the sorption of cationic Ca(2+) ions on CNTs surface because of the excess of negatively charged electrons on the aromatic units formed on MWCNTs after annealing. From the ClinicAL Editor: The authors investigated whether Ca(2+) ion balance between intra- and extracellular space can be modulated by multiwalled carbon nanotubes (MWCNTs). Annealed nanotubes induced changes on Ca(2+) dependent cellular junctions and platelet aggregation, behaving similary to ethylene glycol tetraacetic acid, an established calcium chelator.

  20. 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.

  1. On finite element modeling of single- and multi-walled carbon nanotubes.

    PubMed

    Rahmandoust, Moones; Ochsner, Andreas

    2012-10-01

    In this study, Single-Walled and Multi-Walled Carbon Nanotubes in their perfect forms were investigated by the Finite Element Method. Details on the modeling of the structure are provided in this paper, including the appropriate elements, the element properties that should be defined based on the atomic structure of Carbon Nanotubes and the corresponding chemical bonds. Non-covalent van der Waals interactions between two neighbor atoms as well as the required approximations for the modeling of the structures with this kind of interaction are also presented. Specific attention was dedicated to the necessity of using some time- and energy-consuming steps in the simulation process. First, the effect of simulating only a single ring of the whole structure is studied to find out if it would represent the same mechanical behavior as the long structure. Results show that by applying an appropriate set of boundary conditions, the stiffness of the shortened structure is practically equal to the long perfect structure. Furthermore, Multi-Walled Carbon Nanotube structures with and without defining the van der Waals force are studied. Based on the observations, applying the van der Waals force does not significantly influence the obtained Young's modulus of the structure in the case of a uniaxial tensile test.

  2. 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.

  3. Structure-property relationship in polyethylene reinforced by polyethylene-grafted multi-walled carbon nanotubes.

    PubMed

    Causin, Valerio; Yang, Bing-Xing; Marega, Carla; Goh, Suat Hong; Marigo, Antonio

    2008-04-01

    Polyethylene-grafted multiwalled carbon nanotubes (PE-g-MWNT) were used to reinforce polyethylene (PE). The nanocomposites possessed not only improved stiffness and strength, but also increased ductility and toughness. The effects on the structure and morphology of composites due to pristine multiwalled carbon nanotubes (MWNT) and PE-g-MWNT were studied and compared using small angle X-ray scattering (SAXS), wide angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC). The SAXS long period, crystalline layer thickness and crystallinity of polymer lamellar stacks were found to decrease significantly in MWNT composites, while the decreases were much smaller in PE-g-MWNT composites. PE-g-MWNT allowed a more efficient and unhindered crystallization at a lamellar level, while MWNT disrupted the order of lamellar stacks, probably because of their tendency to aggregate. The SAXS crystallinity and the mechanical properties of the composites showed similar trends as a function of MWNT content. This suggested that the improvement of the interfacial strength between polymer and carbon nanotubes was a result of synergistic effects of better dispersion of the filler, better stress transfer, due to the grafting of polymer and MWNT, and the nucleation of a crystalline phase around MWNT. The latter effect was confirmed by measurements of kinetics of non-isothermal crystallization.

  4. 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.

  5. Electronic structure of fluorinated multiwalled carbon nanotubes studied using x-ray absorption and photoelectron spectroscopy

    NASA Astrophysics Data System (ADS)

    Brzhezinskaya, M. M.; Muradyan, V. E.; Vinogradov, N. A.; Preobrajenski, A. B.; Gudat, W.; Vinogradov, A. S.

    2009-04-01

    This paper presents the results of combined investigation of the chemical bond formation in fluorinated multiwalled carbon nanotubes (MWCNTs) with different fluorine contents (10-55wt%) and reference compounds (highly oriented pyrolytic graphite crystals and “white” graphite fluoride) using x-ray absorption and photoelectron spectroscopy at C1s and F1s thresholds. Measurements were performed at BESSY II (Berlin, Germany) and MAX-laboratory (Lund, Sweden). The analysis of the soft x-ray absorption and photoelectron spectra points to the formation of covalent chemical bonding between fluorine and carbon atoms in the fluorinated nanotubes. It was established that within the probing depth (˜15nm) of carbon nanotubes, the process of fluorination runs uniformly and does not depend on the fluorine concentration. In this case, fluorine atoms interact with MWCNTs through the covalent attachment of fluorine atoms to graphene layers of the graphite skeleton (phase 1) and this bonding is accompanied by a change in the hybridization of the 2s and 2p valence electron states of the carbon atom from the trigonal (sp2) to tetrahedral (sp3) hybridization and by a large electron transfer between carbon an fluorine atoms. In the MWCNT near-surface region the second fluorine-carbon phase with weak electron transfer is formed; it is located mainly within two or three upper graphene monolayers, and its contribution becomes much poorer as the probing depth of fluorinated multiwalled carbon nanotubes (F-MWCNTs) increases. The defluorination process of F-MWCNTs on thermal annealing has been investigated. The conclusion has been made that F-MWCNT defluorination without destruction of graphene layers is possible.

  6. Comparative inhalation toxicity of multi-wall carbon nanotubes, graphene, graphite nanoplatelets and low surface carbon black

    PubMed Central

    2013-01-01

    Background Carbon nanotubes, graphene, graphite nanoplatelets and carbon black are seemingly chemically identical carbon-based nano-materials with broad technological applications. Carbon nanotubes and carbon black possess different inhalation toxicities, whereas little is known about graphene and graphite nanoplatelets. Methods In order to compare the inhalation toxicity of the mentioned carbon-based nanomaterials, male Wistar rats were exposed head-nose to atmospheres of the respective materials for 6 hours per day on 5 consecutive days. Target concentrations were 0.1, 0.5, or 2.5 mg/m3 for multi-wall carbon nanotubes and 0.5, 2.5, or 10 mg/m3 for graphene, graphite nanoplatelets and low-surface carbon black. Toxicity was determined after end of exposure and after three-week recovery using broncho-alveolar lavage fluid and microscopic examinations of the entire respiratory tract. Results No adverse effects were observed after inhalation exposure to 10 mg/m3 graphite nanoplatelets or relatively low specific surface area carbon black. Increases of lavage markers indicative for inflammatory processes started at exposure concentration of 0.5 mg/m3 for multi-wall carbon nanotubes and 10 mg/m3 for graphene. Consistent with the changes in lavage fluid, microgranulomas were observed at 2.5 mg/m3 multi-wall carbon nanotubes and 10 mg/m3 graphene. In order to evaluate volumetric loading of the lung as the key parameter driving the toxicity, deposited particle volume was calculated, taking into account different methods to determine the agglomerate density. However, the calculated volumetric load did not correlate to the toxicity, nor did the particle surface burden of the lung. Conclusions The inhalation toxicity of the investigated carbon-based materials is likely to be a complex interaction of several parameters. Until the properties which govern the toxicity are identified, testing by short-term inhalation is the best option to identify hazardous properties in

  7. Comparative inhalation toxicity of multi-wall carbon nanotubes, graphene, graphite nanoplatelets and low surface carbon black.

    PubMed

    Ma-Hock, Lan; Strauss, Volker; Treumann, Silke; Küttler, Karin; Wohlleben, Wendel; Hofmann, Thomas; Gröters, Sibylle; Wiench, Karin; van Ravenzwaay, Bennard; Landsiedel, Robert

    2013-06-17

    Carbon nanotubes, graphene, graphite nanoplatelets and carbon black are seemingly chemically identical carbon-based nano-materials with broad technological applications. Carbon nanotubes and carbon black possess different inhalation toxicities, whereas little is known about graphene and graphite nanoplatelets. In order to compare the inhalation toxicity of the mentioned carbon-based nanomaterials, male Wistar rats were exposed head-nose to atmospheres of the respective materials for 6 hours per day on 5 consecutive days. Target concentrations were 0.1, 0.5, or 2.5 mg/m3 for multi-wall carbon nanotubes and 0.5, 2.5, or 10 mg/m3 for graphene, graphite nanoplatelets and low-surface carbon black. Toxicity was determined after end of exposure and after three-week recovery using broncho-alveolar lavage fluid and microscopic examinations of the entire respiratory tract. No adverse effects were observed after inhalation exposure to 10 mg/m3 graphite nanoplatelets or relatively low specific surface area carbon black. Increases of lavage markers indicative for inflammatory processes started at exposure concentration of 0.5 mg/m3 for multi-wall carbon nanotubes and 10 mg/m3 for graphene. Consistent with the changes in lavage fluid, microgranulomas were observed at 2.5 mg/m3 multi-wall carbon nanotubes and 10 mg/m3 graphene. In order to evaluate volumetric loading of the lung as the key parameter driving the toxicity, deposited particle volume was calculated, taking into account different methods to determine the agglomerate density. However, the calculated volumetric load did not correlate to the toxicity, nor did the particle surface burden of the lung. The inhalation toxicity of the investigated carbon-based materials is likely to be a complex interaction of several parameters. Until the properties which govern the toxicity are identified, testing by short-term inhalation is the best option to identify hazardous properties in order to avoid unsafe applications or select

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

    DOE PAGES

    Han, Catherine Y.; Xiao, Zhi-Li; Wang, H. Hau; ...

    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

  9. Characterization of functionalized multi-walled carbon nanotubes in pre-vulcanized natural rubber latex

    NASA Astrophysics Data System (ADS)

    Aziz, Azira Abd; Ismail, Nik Intan Nik; Che Su, M. S.; Rusop, M.

    2012-06-01

    A novel natural rubber/multi-walled carbon nanotubes (NR/MWCNTs) nanocomposite is developed by combining self-assembly technique. Natural rubber composites containing carboxylated multiwalled carbon nanotubes dispersed with sodium dodecyl sulfate generated in situ by the sol-gel process are investigated. The functionalization of CNTs was carried out by diazonium salt methodology in acid medium. The sol-gel processing is conducted in order to obtain a good dispersion of the inorganic particles. In each case, the different content of functionalized carbon nanotubes was mixed with natural rubber latex. Results from FESEM, FTIR and Raman analyses indicated that homogeneous dispersion of CNT throughout NR matrix with strong interfacial adhesion between oxidized CNT and the matrix are responsible for the considerable enhancement on the properties of the composite. The NR/MWCNTs have great potential to manufacture products with high mechanical performances.

  10. A new material with atomized cobalt-multiwalled carbon nanotubes: a possible substitute for human implants.

    PubMed

    Joshi, Bharat; Gupta, Sachin; Kalra, Nitin; Gudyka, Russell; Santhanam, K S V

    2010-06-01

    A new material composed of atomized cobalt-multiwalled carbon nanotube has been produced and characterized by thermogravimetric analysis and polarization studies to estimate its lifetime. This does not show cobalt thermal oxidation suggesting that it is confined inside the carbon nanotube matrix. The density functional calculations in the literature predict a strong interaction leading to higher hybridization of cobalt atom and carbon nanotubes. A detailed investigation of the corrosion measurements shows that the new material of thickness 0.8 mm, 1 mm, 1.5 mm and 2 mm would last for 31, 39, 60 and 79 years and it would substitute with cobalt-chromium alloy that is used as a load bearing implant for patients with knee pain or partial denture implant.

  11. Physiological Effects of Single- and Multi-Walled Carbon Nanotubes on Rice Seedlings.

    PubMed

    Zhang, Hao; Yue, Mengxia; Zheng, Xueke; Xie, Chengshen; Zhou, Hong; Li, Lijia

    2017-10-01

    In this paper, single-walled carbon nano- tubes (SWCNTs) and multi-walled carbon nano- tubes (MWCNTs) were found to accelerate leaf growth and development of rice seedlings at a low concentration (20 mg/L), accompanied with the increased chlorophyll content and net photosynthetic rate (PN). Quantitative real-time polymerase chain reaction results indicated that both SWCNTs and MWCNTs significantly increased expression of genes associated with chloroplast development and cell sizes. Further analysis revealed that the abscisic acid content decreased and the gibberellin content increased while the content of [Formula: see text] and H2O2 was slightly elevated and the activities of antioxidative enzymes (SOD, EC 1.15.1.1, and POD, EC 1.11.1.7) were differently modulated after treatment with the carbon nanotube (CNT). These results suggest a possible link between reactive oxygen species and plant hormones under CNTs treatment to promote rice seedlings growth.

  12. 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.

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

    USDA-ARS?s Scientific Manuscript database

    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...

  14. 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

  15. Quantitative stability analyses of multiwall carbon nanotube nanofluids following water/ice phase change cycling.

    PubMed

    Ivall, Jason; Langlois-Rahme, Gabriel; Coulombe, Sylvain; Servio, Phillip

    2017-02-03

    Multiwall carbon nanotube nanofluids are regularly investigated for phase change enhancement between liquid and solid states owing to their improved heat transfer properties. The potential applications are numerous, the most notable being latent heat thermal energy storage, but the success of all nanofluid-assisted technologies hinges greatly on the ability of nanoparticles to remain stably dispersed after repeated phase change cycles. In this report, the stability of aqueous nanofluids made from oxygen-functionalized multiwall carbon nanotubes (f-MWCNTs) was profiled over the course of 20 freeze/thaw cycles. Sonication was used after each cycle to re-disperse clusters formed from the crystallization process. This study offers a quantitative evaluation of f-MWCNT-nanofluid stability as a result of phase change through optical characterization of concentration and particle size. It also provides insight into the integrity of the surface functionalities through zeta potential and XPS analyses. Concentration and particle size measurements showed moderate and consistent recoverability of f-MWCNT dispersion following ultrasonication. XPS measurements of solid-state MWCNTs exposed to freeze/thaw cycling in water, and zeta potential analyses of the nanofluids indicate that the surface oxygen content is preserved throughout phase change and over repeated cycles. These results suggest a resilience of oxygen-functionalized MWCNTs to the freezing and thawing of water, which is ideal for their utilization as phase change enhancers.

  16. Quantitative stability analyses of multiwall carbon nanotube nanofluids following water/ice phase change cycling

    NASA Astrophysics Data System (ADS)

    Ivall, Jason; Langlois-Rahme, Gabriel; Coulombe, Sylvain; Servio, Phillip

    2017-02-01

    Multiwall carbon nanotube nanofluids are regularly investigated for phase change enhancement between liquid and solid states owing to their improved heat transfer properties. The potential applications are numerous, the most notable being latent heat thermal energy storage, but the success of all nanofluid-assisted technologies hinges greatly on the ability of nanoparticles to remain stably dispersed after repeated phase change cycles. In this report, the stability of aqueous nanofluids made from oxygen-functionalized multiwall carbon nanotubes (f-MWCNTs) was profiled over the course of 20 freeze/thaw cycles. Sonication was used after each cycle to re-disperse clusters formed from the crystallization process. This study offers a quantitative evaluation of f-MWCNT-nanofluid stability as a result of phase change through optical characterization of concentration and particle size. It also provides insight into the integrity of the surface functionalities through zeta potential and XPS analyses. Concentration and particle size measurements showed moderate and consistent recoverability of f-MWCNT dispersion following ultrasonication. XPS measurements of solid-state MWCNTs exposed to freeze/thaw cycling in water, and zeta potential analyses of the nanofluids indicate that the surface oxygen content is preserved throughout phase change and over repeated cycles. These results suggest a resilience of oxygen-functionalized MWCNTs to the freezing and thawing of water, which is ideal for their utilization as phase change enhancers.

  17. The effect of calcination on multi-walled carbon nanotubes produced by dc-arc discharge.

    PubMed

    Pillai, Sreejarani K; Augustyn, Willem G; Rossouw, Margaretha H; McCrindle, Robert I

    2008-07-01

    Multi-walled carbon nanotubes were synthesized by dc-arc discharge in helium atmosphere and the effect of calcination at different temperatures ranging from 300-600 degrees C was studied in detail. The degree of degradation to the structural integrity of the multi-walled carbon nanotubes during the thermal process was studied by Raman spectroscopy, Scanning electron microscopy and High resolution transmission electron microscopy. The thermal behaviour of the as prepared and calcined samples was investigated by thermogravimetric analysis. Calcination in air at 400 degrees C for 2 hours was found to be an efficient and simple method to eliminate carbonaceous impurities from the nanotube bundles with minimal damage to the tube walls and length. The impurities were oxidized at a faster rate when compared to the nanotubes and gave good yield of about 50%. The nanotubes were observed to be damaged at temperature higher than 450 degrees C. The results show that this method is less destructive when compared liquid phase oxidation with 5 M HNO3.

  18. 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.

  19. 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.

  20. Radial Heat Transfer Dynamics in Multiwall Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Osman, Mohamed; Kim, Taejin

    2006-05-01

    The dynamics of radial heat transfer in zigzag and armchair double wall carbon nanotubes (DWCNT) have been examined using molecular dynamic (MD) simulations with the goal of understanding the role of radial phonon modes in heat transfer. The MD model uses Tersof-Brenner potential for bonded C-C interactions within each shell and non-bended van der Wall interaction between inner and outer shells. The simulation procedure involves, (1) quenching the DWNT to 0 K, (2) minimization of the potential energy and (3) raising the temperature of the outer shell to the desired steady state temperature while maintaining the inner tube at 0.1 K. The heat baths are removed from the outer and inner shell and their energies are examined. The energies of inner and outer exhibit an out of phase oscillatory behavior due the exchange of the energies between the two shells. The energy of the inner tube shows a weak gradual increase due to the temperature gradient. The beat frequencies determined from the Fourier transform of the energy oscillations of the inner and outer nanotubes were found to be in the tera Herz range. We will also discuss the temperature and length dependence of oscillatory energy exchange between the nanotube shells.

  1. Electrochemical synthesis of gold nanoparticles on the surface of multi-walled carbon nanotubes with glassy carbon electrode and their application

    NASA Astrophysics Data System (ADS)

    Song, Y. Z.; Li, X.; Song, Y.; Cheng, Z. P.; Zhong, H.; Xu, J. M.; Lu, J. S.; Wei, C. G.; Zhu, A. F.; Wu, F. Y.; Xu, J.

    2013-01-01

    Gold nanoparticles on the surface of multi-walled carbon nanotubes with glassy carbon electrode were prepared using electrochemical synthesis method. The thin films of gold Nanoparticles/multi-walled carbon nanotubes were characterized by scanning electron microscopy, powder X-ray diffraction, and cyclic voltammetry. Electrochemical behavior of adrenaline hydrochloride at gold nanoparticles/multi-walled carbon nanotube modified glassy carbon electrode was investigated. A simple, sensitive, and inexpensive method for determination of adrenaline hydrochloride was proposed.

  2. 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.

  3. Adsorption kinetics, thermodynamics and desorption of natural dissolved organic matter by multiwalled carbon nanotubes.

    PubMed

    Su, Fengsheng; Lu, Chungsying

    2007-09-01

    Multiwalled carbon nanotubes (CNTs) were thermally treated and were employed as adsorbents to study their adsorption kinetics and thermodynamics of natural dissolved organic matter (NDOM) from aqueous solutions. The adsorption kinetics follows the first-order rate law while the adsorption thermodynamics indicates the exothermic and spontaneous nature. A comparative study on the adsorption/desorption properties of NDOM between CNTs and granular activated carbon (GAC) was also conducted and revealed that the CNTs possess more NDOM adsorption capacities and show less weight loss through 10 cycles of water treatment and reactivation than the GAC. This suggests that the CNTs are promising NDOM adsorbents for preventing the microbiological degradation of drinking water quality as well as the formation of disinfection by products in water treatment.

  4. Effect of electrode gap on the sensing properties of multiwalled carbon nanotubes based gas sensor

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

    Vertically aligned multiwalled carbon nanotubes (MWCNT) were grown on Si substrate coated with alumina and iron using chemical vapor deposition. Electrode gap of 10, 25 and 50 µm were adopted to determine the effect of varying gap spacing on the sensing properties such as voltage breakdown, sensitivity and selectivity for three gases namely argon, carbon dioxide and ammonia. Argon has the lowest voltage breakdown for every electrode gap. The fabricated MWCNT based gas sensor drastically reduced the voltage breakdown by 89.5% when the electrode spacing is reduced from 50 µm to 10 µm. The reduction is attributed to the high non-uniform electric field between the electrodes caused by the protrusion of nanotips. The sensor shows good sensitivity and selectivity with the ability to detect the gas in the mixture with air provided that the concentration is ≥ 20% where the voltage breakdown will be close to the pure gas.

  5. 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.

  6. Application of multiwalled carbon nanotubes/ionic liquid modified electrode for amperometric determination of sulfadiazine.

    PubMed

    Hong, Xiaoping; Zhu, Yan; Ma, Jingying

    2012-12-01

    A highly sensitive amperometric sulfadiazine sensor based on coating multiwalled carbon nanotubes (MWCNTs) and N-octyl-pyridinium-hexafluorophosphate (OPPF(6)) ionic liquid composite on a glassy carbon (GC) electrode is described. The MWCNTs/OPPF(6) composite contributed new properties to electrochemical sensors by combining the advantages of both ionic liquids and MWCNTs. Compared with bare GC electrode, the electrocatalytic activity of MWCNTs/OPPF(6) generated a greatly improved electrochemical detection of sulfadiazine including low oxidation potential, high current responses, and good anti-fouling performance. The oxidation peak currents of sulfadiazine obtained on the MWCNTs/OPPF(6) coated GC electrode were proportional to the concentration of sulfadiazine within the range of 3.3-35.4 μM with a detection limit of 0.21 μM.

  7. Seed-mediated growth of ZnO nanorods on multiwalled carbon nanotubes.

    PubMed

    Li, Changqing; Jin, Zhong; Chu, Haibin; Li, Yan

    2008-09-01

    The heterostructures of ZnO nanorods on multiwalled carbon nanotubes (MWNTs) were fabricated by a seed-mediated growth method. First, the surfaces of the carbon nanotubes (CNTs) were coated in situ with mono-dispersed ZnO nanocrystals of about 7 nm by the reaction of zinc acetate and sodium hydroxide. These nanocrystals were then served as the seeds for further growth of ZnO nanorods. In the second step, ZnO nanorods were grown on MWNTs coated with ZnO nanocrystals in an aqueous solution of zinc nitrate and equimolar hexamethylenetetramine at 85 degrees C. Typically, the ZnO nanorods had the length of 300-600 nm and the diameter of 40-140 nm and took a random direction on the outside walls of MWNTs. The morphology of the ZnO nanorods was dependent on pH, reactant concentration, and growing time.

  8. 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.

  9. Voltammetric Determination of Ferulic Acid Using Polypyrrole-Multiwalled Carbon Nanotubes Modified Electrode with Sample Application

    PubMed Central

    Abdel-Hamid, Refat; Newair, Emad F.

    2015-01-01

    A polypyrrole-multiwalled carbon nanotubes modified glassy carbon electrode-based sensor was devised for determination of ferulic acid (FA). The fabricated sensor was prepared electrochemically using cyclic voltammetry (CV) and characterized using CV and scanning electron microscope (SEM). The electrode shows an excellent electrochemical catalytic activity towards FA oxidation. Under optimal conditions, the anodic peak current correlates linearly to the FA concentration throughout the range of 3.32 × 10−6 to 2.59 × 10−5 M with a detection limit of 1.17 × 10−6 M (S/N = 3). The prepared sensor is highly selective towards ferulic acid without the interference of ascorbic acid. The sensor applicability was tested for total content determination of FA in a commercial popcorn sample and showed a robust functionality.

  10. 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

  11. 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.

  12. 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.

  13. Laser sintering of separated and uniformly distributed multiwall carbon nanotubes integrated iron nanocomposites

    NASA Astrophysics Data System (ADS)

    Lin, Dong; Richard Liu, C.; Cheng, Gary J.

    2014-03-01

    Uniform distribution of carbon nanotubes (CNTs) in metal matrix during additive manufacturing of nanocomposites is always a challenge since the CNTs tend to aggregate in the molten pool. In this study, Multiwall carbon nanotubes (MWNTs) were separated and distributed uniformly into iron matrix by laser sintering process. MWNTs and iron powders were mixed together by magnetic stir, coated on steel 4140 surface, followed by laser sintering. Due to the fast heating and cooling rate, the CNTs are evenly distributed in the metal matrix. The temperature field was calculated by multiphysics simulation considering size effects, including size dependent melting temperature, thermal conductivity, and heat capacity. The SEM, TEM, and XRD were used to understand the laser sintering of CNT integrated nanocomposites. The results proved the feasibility of this technique to synthesize MWNTS integrated metal matrix nanocomposites.

  14. Elucidation mechanism of different biological responses to multi-walled carbon nanotubes using four cell lines

    PubMed Central

    Haniu, Hisao; Saito, Naoto; Matsuda, Yoshikazu; Kim, Yoong-Ahm; Park, Ki Chul; Tsukahara, Tamotsu; Usui, Yuki; Aoki, Kaoru; Shimizu, Masayuki; Ogihara, Nobuhide; Hara, Kazuo; Takanashi, Seiji; Okamoto, Masanori; Ishigaki, Norio; Nakamura, Koichi; Kato, Hiroyuki

    2011-01-01

    We examined differences in cellular responses to multi-walled carbon nanotubes (MWCNTs) using malignant pleural mesothelioma cells (MESO-1), bronchial epithelial cells (BEAS-2B), neuroblastoma cells (IMR-32), and monoblastic cells (THP-1), before and after differentiation. MESO-1, BEAS-2B and differentiated THP-1 cells actively endocytosed MWCNTs, resulting in cytotoxicity with lysosomal injury. However, cytotoxicity did not occur in IMR-32 or undifferentiated THP-1 cells. Both differentiated and undifferentiated THP-1 cells exhibited an inflammatory response. Carbon blacks were endocytosed by the same cell types without lysosomal damage and caused cytokine secretion, but they did not cause cytotoxicity. These results indicate that the cytotoxicity of MWCNTs requires not only cellular uptake but also lysosomal injury. Furthermore, it seems that membrane permeability or cytokine secretion without cytotoxicity results from several active mechanisms. Clarification of the cellular recognition mechanism for MWCNTs is important for developing safer MWCNTs. PMID:22267932

  15. Finite element investigation of multi-walled carbon nanotubes as mass sensors

    NASA Astrophysics Data System (ADS)

    Rouhi, Saeed; Ansari, Reza; Nikkar, Abed

    2017-03-01

    Using the finite element method, multi-walled carbon nanotubes-based mass sensors are studied. The effects of different parameters such as number of walls of nanotube, nanotube diameter and nanotube length on the mass sensibility are explored. It is shown that the maximum sensitivity of nanotubes under clamped-free boundary conditions occurs when the mass is located at the farthest location from the clamped edge. Comparing the results of nanotubes with different walls, it is observed that single-walled carbon nanotubes are the best mass sensors. Moreover, it is represented that for large masses connected to the nanotubes, the mass sensor can only identify that an external mass added to it and the mass value is not identifiable.

  16. Surface modification of multiwalled carbon nanotubes via esterification using a biodegradable polyol.

    PubMed

    Fernandez d'Arlas, B; Goyanes, S; Rubiolo, G H; Mondragon, I; Corcuera, M A; Eceiza, A

    2009-10-01

    Multiwalled carbon nanotubes (MWCNT) were surface modified firstly oxidizing them with a H2SO4/HNO3 mixture to obtain more reactive carboxylic groups on their surface and then higher functionality. Secondly the oxidized nanotubes (MWCNT-COOH) were dispersed in tetrahydrofuran (THF) and made react via esterification with a poly(hexamethylene carbonate-co-caprolactone)diol, a potentially biodegradable polyol with hydroxyl groups at its ends. Modification process steps were characterized using Fourier transform infrared spectroscopy, FT-IR, ultraviolet spectroscopy, UV, solubility in different solvents, thermo-gravimetric analysis, TGA, as well as atomic force microscopy, AFM. Results suggest that surface carboxylic groups are reactive enough to graft polymer chains onto their surface.

  17. One-pot, efficient functionalization of multi-walled carbon nanotubes with diamines by microwave method

    NASA Astrophysics Data System (ADS)

    Amiri, A.; Maghrebi, M.; Baniadam, M.; Zeinali Heris, S.

    2011-09-01

    Diamines are known to act as a medium to bind miscellaneous compounds to carbon nanotubes (CNT). However, they are commonly applied in a tedious manner. Here, multi-walled carbon nanotubes (MWCNTs) were functionalized by a series of diamine molecules (ethylenediamine, 1,6-hexamethylenediamine and 1,4-diaminobenzen) in a one-pot, rapid microwave-assisted method. Surface functionality groups and morphology of MWCNTs were analyzed by infrared spectroscopy, thermogravimetric analysis, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy. The results consistently confirmed the formation of diamines functionalities on MWCNTs, while the structure of MWCNT has remained relatively intact. This simple and efficient process may play an important role for realizing miscellaneous functionalization of CNTs.

  18. Superconductivity of MgB 2 with embedded multiwall carbon nanotube

    NASA Astrophysics Data System (ADS)

    Kim, J. H.; Yeoh, W. K.; Xu, X.; Dou, S. X.; Munroe, P.; Rindfleisch, M.; Tomsic, M.

    2006-11-01

    We studied the effects of MgB2 with embedded multiwall carbon nanotubes (MWCNTs) on the crystallinity, lattice parameters, critical current density (Jc), upper critical field (Hc2), irreversibility field (Hirr), and microstructure of MgB2. Fe sheathed un-doped and MWCNT doped MgB2 wires were fabricated by the powder-in-tube (PIT) method and sintered at the high sintering temperatures of 900 °C. We observed that for the MWCNT doped sample high temperature sintering resulted in depressed crystallinity, shrinkage of the a-lattice parameter, higher Jc up to 12 T, and lower critical temperature (Tc) values. Specifically, MWCNT doped samples sintered at 900 °C exhibited excellent Jc, ∼104 A cm-2 up to 9 T at 4.2 K. This can be explained by lattice distortion and poor crystallinity due to carbon (C) substitution from the MWCNT.

  19. Synthesis and enhanced photocatalytic activity of tin oxide nanoparticles coated on multi-walled carbon nanotube

    SciTech Connect

    Wang, Ning; Xu, Jiaoxing; Guan, Lunhui

    2011-09-15

    Highlights: {yields} SnO{sub 2} nanoparticles were uniformly deposited on carbon nanotubes. {yields} MWNT@SnO{sub 2} showed excellent photocatalytic activity. {yields} The quenched PL proved the existence of electron transfer between SnO{sub 2} and MWNT. -- Abstract: A nanocomposite of SnO{sub 2} nanoparticles coated on multi-walled carbon nanotube (MWNT@SnO{sub 2}) was synthesized and characterized by thermogravimetric analysis, X-ray diffraction, transmission electron microscopy, nitrogen physisorption measurements, photoluminescence. The results show that the SnO{sub 2} nanoparticles with a narrow size of 4 nm are uniformly deposited on MWNT. The photocatalytic activity of the nanocomposite was studied using methyl orange as a model organic pollutant. MWNT@SnO{sub 2} exhibits much higher photocatalytic activity than that of commercial TiO{sub 2} (P-25). The promotion is mainly contributed from electron transfer between SnO{sub 2} and MWNT.

  20. Enhancement of polymer luminescence by excitation-energy transfer from multi-walled carbon nanotubes.

    PubMed

    Henley, Simon J; Hatton, Ross A; Chen, Guan Y; Gao, Chao; Zeng, Hailin; Kroto, Harold W; Silva, S Ravi P

    2007-11-01

    Carbon nanotubes have been shown to efficiently quench luminescence from conjugated polymers when incorporated in a composite. However, shown here is an up to 100-fold increase in the visible photoluminescence signal from fluorescent chromophores in nylon 10,10 by incorporating multi-walled carbon nanotubes (MWCNTs). Using 325- and 488-nm excitation the optical absorption by MWCNTs embedded within the polymer matrix is demonstrated, followed by efficient excitation-energy transfer to emissive chromophores intrinsic to the polymer but only when the MWCNTs are acid functionalized. Furthermore, the MWCNTs are shown to significantly retard photobleaching of fluorescent centers in the nylon composites. These remarkable properties greatly advance the prospects of utilizing MWCNTs in organic solar cells and electroluminecent devices to improve performance.

  1. 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

  2. Vertical self-assembly of modified multiwalled carbon nanotubes on gold surfaces induced by chitosan and Tween.

    PubMed

    Zuaznabar-Gardona, Julio C; Cao, Roberto; Cao, Roberto; Suarez, Margarita

    2012-02-11

    Multiwalled carbon nanotubes modified with 2-aminoethanethiol (MWNT-AET) were vertically self-assembled on gold electrodes with the assistance of chitosan and Tween. According to AFM and cyclic voltammetric determinations the best results were achieved using chitosan. This journal is © The Royal Society of Chemistry 2012

  3. 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...

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

    USDA-ARS?s Scientific Manuscript database

    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...

  6. Do goethite surfaces really control the transport and retention of multi-walled carbon nanotubes in chemically heterogeneous porous media?

    USDA-ARS?s Scientific Manuscript database

    Transport and retention behavior of multiwalled carbon nanotubes (MWCNTs) was studied in mixtures of negatively charged quartz sand (QS) and positively charged goethite-coated sand (GQS) to assess the role of chemical heterogeneity. The linear equilibrium sorption model provided a good description o...

  7. Co-transport of chlordecone and sulfadiazine in the presence of functionalized multi-walled carbon nanotubes in soils

    USDA-ARS?s Scientific Manuscript database

    Batch and saturated soil column experiments were conducted to investigate sorption and mobility of two 14C-labeled contaminants, the hydrophobic chlordecone (CLD) and the readily water-soluble sulfadiazine (SDZ), in the absence or presence of functionalized multi-walled carbon nanotubes (MWCNTs). Th...

  8. Excellent catalytic effects of multi-walled carbon nanotube supported titania on hydrogen storage of a Mg-Ni alloy.

    PubMed

    Tan, Yajun; Zhu, Yunfeng; Li, Liquan

    2015-02-11

    Superior catalytic effects of multi-walled carbon nanotube supported titania synthesized by the sol-gel method on hydrogen storage of a Mg-Ni alloy were investigated. The excellent hydrogen storage properties were obtained: absorbed 5.60 wt% H2 within 60 s at 373 K and released 6.08 wt% H2 within 600 s at 553 K.

  9. 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...

  10. 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...

  11. 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

  12. 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...

  13. 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...

  14. 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.

  15. 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. Copyright © 2011 Elsevier B.V. All rights reserved.

  16. 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.

  17. Comparison of cellular toxicity between multi-walled carbon nanotubes and onion-like shell-shaped carbon nanoparticles

    NASA Astrophysics Data System (ADS)

    Kang, Seunghyon; Kim, Ji-Eun; Kim, Daegyu; Woo, Chang Gyu; Pikhitsa, Peter V.; Cho, Myung-Haing; Choi, Mansoo

    2015-09-01

    The cellular toxicity of multi-walled carbon nanotubes (MWCNTs) and onion-like shell-shaped carbon nanoparticles (SCNPs) was investigated by analyzing the comparative cell viability. For the reasonable comparison, physicochemical characteristics were controlled thoroughly such as crystallinity, carbon bonding characteristic, hydrodynamic diameter, and metal contents of the particles. To understand relation between cellular toxicity of the particles and generation of reactive oxygen species (ROS), we measured unpaired singlet electrons of the particles and intracellular ROS, and analyzed cellular toxicity with/without the antioxidant N-acetylcysteine (NAC). Regardless of the presence of NAC, the cellular toxicity of SCNPs was found to be lower than that of MWCNTs. Since both particles show similar crystallinity, hydrodynamic size, and Raman signal with negligible contribution of remnant metal particles, the difference in cell viability would be ascribed to the difference in morphology, i.e., spherical shape (aspect ratio of one) for SCNP and elongated shape (high aspect ratio) for MWCNT.

  18. 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.

  19. 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

  20. Sustained arc temperature: better marker for phase transformation of carbon black to multiwalled carbon nanotubes in arc discharge method

    NASA Astrophysics Data System (ADS)

    Arora, Neha; Sharma, N. N.

    2016-10-01

    The present study investigates the role of temperature in the formation of multiwalled carbon nanotubes from carbon black using arc discharge technique. Carbon black has been used as precursor to synthesize carbon nanotubes in argon atmosphere. The arc current has been varied from 25 to 40 A in order to study the morphological changes in carbon black as it gets converted to multi walled carbon nanotubes (MWCNTs). We observed formation of MWCNTs at an arc current of 25 A; however the recorded temperature data suggested correlation of sustained arc temperature with the nanotube formation rather than the magnitude of current in its absoluteness. Interesting to note is that reported current magnitude in published literature are very high (>40 A) for conversion of carbon black but the present investigation shows that it is possible to convert the carbon black to MWCNTs even at lower current values in case the arc temperature is stabilized and sustained for longer period. Detailed investigations suggested that a sustained stable critical temperature of 1400 °C-1600 °C is essential for the growth of nanotubes and an unstable arc causing temperature fluctuation from critical temperature value yields very low or no MWCNTs.

  1. Immune responses of BALB/c mice to subcutaneously injected multi-walled carbon nanotubes.

    PubMed

    Meng, Jie; Yang, Man; Jia, Fumin; Xu, Zhen; Kong, Hua; Xu, Haiyan

    2011-12-01

    Carbon nanotubes have been shown to have the ability to transport therapeutic and detective reagents into cells. However, the rapid advances in new carbon nanotube-based materials and technologies have raised concerns about their safety. Such concerns require a fundamental understanding of the toxicological properties of carbon nanotubes. In particular, the use of carbon nanotubes as drug or probe delivery platforms may depend on the prevention of stimulatory side-effects to the immune system. In this study, we investigated the immunological properties of oxidized water dispersible multi-walled carbon nanotubes (MWCNTs) in healthy BALB/c mice. We injected the MWCNTs subcutaneously, and the immune responses of the mice were monitored over time. We show that the MWCNTs induce complement activation and the production of pro-inflammatory cytokines early after injection of the mice, and that the levels of complement and cytokines return to normal levels over time. With the exception of the lymph nodes, there was no obvious accumulation of MWCNTs observed in the liver, spleen, kidney, or heart. In addition, we did not observe injury in the organs or lymph nodes. Our results indicate that local, subcutaneous administration of MWCNTs induces obvious short-term immunological reactions, which can be eliminated over time.

  2. Dispersion of multi-wall carbon nanotubes in polyhistidine: characterization and analytical applications.

    PubMed

    Dalmasso, Pablo R; Pedano, María L; Rivas, Gustavo A

    2012-01-13

    We report for the first time the use of polyhistidine (Polyhis) to efficiently disperse multiwall carbon nanotubes (MWCNTs). The optimum dispersion MWCNT-Polyhis was obtained by sonicating for 30 min 1.0 mg mL(-1) MWCNTs in 0.25 mg mL(-1) Polyhis solution prepared in 75:25 (v/v) ethanol/0.200 M acetate buffer solution pH 5.00. The dispersion was characterized by scanning electron microscopy, and by cyclic voltammetry and amperometry using ascorbic acid as redox marker. The modification of glassy carbon electrodes with MWCNT-Polyhis produces a drastic decrease in the overvoltage for the oxidation of ascorbic acid (580 mV) at variance with the response observed at glassy carbon electrodes modified just with Polyhis, where the charge transfer is more difficult due to the blocking effect of the polymer. The reproducibility for the sensitivities obtained after 10 successive calibration plots using the same surface was 6.3%. The MWCNT-modified glassy carbon electrode demonstrated to be highly stable since after 45 days storage at room temperature the response was 94.0% of the original. The glassy carbon electrode modified with MWCNT-Polyhis dispersion was successfully used to quantify dopamine or uric acid at nanomolar levels, even in the presence of large excess of ascorbic acid. Determinations of uric acid in human blood serum samples demonstrated a very good correlation with the value reported by Wienner laboratory.

  3. 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.

  4. 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.

  5. Electrical conductivity and electromagnetic interference shielding characteristics of multiwalled carbon nanotube filled polyurethane composite films

    NASA Astrophysics Data System (ADS)

    Son Hoang, Anh

    2011-06-01

    Multiwalled carbon nanotubes (MWCNTs) were homogeneously dispersed in a pure polyurethane resin by grinding in a planetary ball mill. The structure and surface morphology of the MWCNTs and MWCNT/polyurethane composites were studied by filed emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) methods. The electrical conductivity at room temperature and electromagnetic interference (EMI) shielding effectiveness (SE) of the composite films with different MWCNT loadings were investigated and the measurement of EMI SE was carried out in a frequency range of 8-12 GHz (X-band). The experimental results show that with a low MWCNT concentration the composite films could achieve a high conductivity and their EMI SE has a strong dependence on MWCNT content. For the composite films with 22 wt% of MWCNTs, the EMI SE attained an average value of 20 dB, so that the shielding effect reduced the penetrating power to 1%.

  6. 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.

  7. 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.

  8. 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.

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

    DOE PAGES

    Rodríguez-Pulido, A.; Martínez-Gutiérrez, H.; Calderon-Polania, G. A.; ...

    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.

  10. 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.

  11. Synthesis and characterization of "mulberry"-like Fe3O4/multiwalled carbon nanotube nanocomposites

    NASA Astrophysics Data System (ADS)

    Song, Hao-Jie; Li, Na; Jing, Xiaojing; Yang, Xiaofei; Tang, Hua

    2011-10-01

    Nanocomposites composed of multi-wall carbon nanotubes (MWNTs) and Fe3O4 nanoparticles were fabricated using solvothermal method. Transmission and scanning electron microscopy, energy dispersive spectroscopy, and X-ray powder diffraction measurements confirmed that these mulberry-like Fe3O4 microparticles which were combined with the MWNTs in a random pattern are constructed with tiny nanocrystallites (12 nm in average diameter). The magnetic properties of the Fe3O4/MWNTs nanocomposites were measured using a vibrating sample magnetometer. Results showed that the Fe3O4/MWNTs nanocomposites exhibited superparamagnetism at room temperature and possessed a lower saturation magnetization (around 27.6 emu/g) than that of the pure Fe3O4 nanoparticles (around 33.7 emu/g). The Fe3O4/MWNTs nanocomposites have potential applications in engineering and medicine.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. A Multiwalled Carbon Nanotube/Dihydropyran Composite Film Electrode for Insulin Detection in a Microphysiometer Chamber

    PubMed Central

    Snider, Rachel M.; Ciobanu, Madalina; Rue, Amy E.; Cliffel, David E.

    2008-01-01

    We have developed a multiwalled carbon nanotube/dihydropyran (MWCNT/DHP) composite sensor for the electrochemical detection of insulin in a microfluidic device. This sensor has been employed for physiological measurements of secreted insulin from pancreatic islets in a Cytosensor® previously modified to be a multianalyte microphysiometer (MAMP). When compared with other established electrochemical insulin sensors, the MWCNT/DHP composite film sensor presented improved resistance to fluidic shear forces, while achieving enhanced electrode kinetics. In addition, the preparation of the composite film is straightforward and facile with a self-polymerizing monomer, DHP, used to add mechanical stability to the film. The sensor film was able to detect insulin concentrations as low as 1 µM in the MAMP during calibration experiments. The MWCNT/DHP composite sensor has been successfully used for the direct detection of insulin secreted by islets in the microphysiometer. PMID:18243872

  19. 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.

  20. Effect of Multiwall Carbon Nanotube Reinforcement on Coaxially Extruded Cellular Vascular Conduits

    PubMed Central

    Zhang, Yahui; Yu, Yin; Dolati, Farzaneh; Ozbolat, Ibrahim T

    2014-01-01

    Due to its abundant source, good biocompatibility, low price and mild crosslinking process, alginate is an ideal selection for tissue engineering applications. In this work, alginate vascular conduits were fabricated through a coaxial extrusion-based system. However, due to the inherent weak mechanical properties of alginate, the vascular conduits are not capable of biomimicking natural vascular system. In this paper, multiwall carbon nanotubes (MWCNT) were used to reinforce vascular conduits. Mechanical, dehydration, swelling and degradation tests were performed to understand influences of MWCNT reinforcement. The unique mechanical properties together with perfusion and diffusional capability are two important factors to mimic the nature. Thus, perfusion experiments were also conducted to explore the MWCNT reinforcement effect. In addition, cell viability and tissue histology were conducted to evaluate the biological performance of conduits both in short and long term for MWCNT reinforcement. PMID:24863208

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

    DOE PAGES

    Rochford, C.; Limmer, S. J.; Howell, S. W.; ...

    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

  2. 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

  3. Synthesis of ZnO coated multi-walled carbon nanotubes and their antibacterial activities.

    PubMed

    Sui, Minghao; Zhang, Lingdian; Sheng, Li; Huang, Shuhang; She, Lei

    2013-05-01

    ZnO coated multi-walled carbon nanotubes (ZnO/MWCNTs) were prepared and evaluated for their application potentials as an antimicrobial material for simultaneous concentrating and inactivating pathogenic bacteria. X-ray energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), and X-ray photoelectron spectra (XPS) were used to characterize the ZnO/MWCNTs. Escherichia coli (E. coli) was employed as the target bacterium. Comparing with the raw and the purified MWCNTs (r-MWCNTs and p-MWCNTs), which have been reported to possess antibacterial activity towards E. coli, ZnO/MWCNTs exhibited stronger antibacterial ability. The deposited ZnO was suggested to play an important role in the bactericidal action of ZnO/MWCNTs, while, the r-MWCNTs and p-MWCNTs served as more like adsorbing materials for E. coli.

  4. 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.

  5. Effect of multiwalled carbon nanotubes on the thermoelectric properties of Mn-Zn ferrites

    NASA Astrophysics Data System (ADS)

    Zhang, Shupin; Li, Aimin; Sun, Kangning; Sun, Xiaoning; Wang, Yaping; Wang, Song

    2017-10-01

    In this study, Mn-Zn ferrites with three different multiwalled carbon nanotubes (MWNTs) concentration, 1,2,3 wt%, were used to compare the effect of MWNTs on thermoelectric properties of the composites. The dimensionless figure of merit (ZT) of the composites at the low contents (1 and 2 wt%) of MWNTs have shown significantly increased values compared to those of composites at the high contents (3 wt%) in the temperature range of 323-973 K. The maximum ZT of 0.038 was obtained at 2 wt%. It is considered that the improved thermoelectric performance of the composite mainly originated from electrical conductivity that is attributed to the increased carrier concentration or carrier mobility.

  6. Influence of nanotube physicochemical properties on the decoration of multiwall carbon nanotubes with magnetic particles

    NASA Astrophysics Data System (ADS)

    Uc-Cayetano, E. G.; Avilés, F.; Cauich-Rodríguez, J. V.; Schönfelder, R.; Bachmatiuk, A.; Rümmeli, M. H.; Rubio, F.; Gutiérrez-Amador, M. P.; Cruz, G. J.

    2014-01-01

    Two types of commercial multiwall carbon nanotubes (MWCNTs) with different diameters and physicochemical properties were decorated with iron oxide nanoparticles obtained by hydrolysis at high temperature in the presence of triethylene glycol and iron(III) chloride as metal precursor. A homogeneous distribution of 2-9 nm diameter particles decorating the MWCNTs was achieved using a weight concentration of 1:1 or 1:2 of the nanotube with respect to the metal precursor for 30 min of reflux. Detailed characterization of the as-received MWCNTs allowed to correlate the influence of the initial nanotube physicochemical properties to their decoration. The results indicate that a more homogeneous decoration and larger magnetization are achieved for MWCNTs with larger density of defective/reactive sites and larger surface area.

  7. Radial Corrugations of Multi-Walled Carbon Nanotubes Driven by Inter-Wall Nonbonding Interactions.

    PubMed

    Huang, Xu; Liang, Wentao; Zhang, Sulin

    2011-12-01

    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.

  8. 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.

  9. 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.

  10. Growth of small diameter multi-walled carbon nanotubes by arc discharge process

    NASA Astrophysics Data System (ADS)

    T. Chaudhary, K.; J., Ali; P. Yupapin, P.

    2014-03-01

    Multi-walled carbon nanotubes (MWCNTs) are grown by arc discharge method in a controlled methane environment. The arc discharge is produced between two graphite electrodes at the ambient pressures of 100 torr, 300 torr, and 500 torr. Arc plasma parameters such as temperature and density are estimated to investigate the influences of the ambient pressure and the contributions of the ambient pressure to the growth and the structure of the nanotubes. The plasma temperature and density are observed to increase with the increase in the methane ambient pressure. The samples of MWCNT synthesized at different ambient pressures are analyzed using transmission electron microscopy, scanning electron microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffraction. An increase in the growth of MWCNT and a decrease in the inner tube diameter are observed with the increase in the methane ambient pressure.

  11. Electrical and morphological characterization of multiwalled carbon nanotubes functionalized via the Bingel reaction

    NASA Astrophysics Data System (ADS)

    Brković, Danijela V.; Ivić, Milka L. Avramov; Rakić, Vesna M.; Valentini, Luca; Uskoković, Petar S.; Marinković, Aleksandar D.

    2015-08-01

    Covalent sidewall functionalization of multiwalled carbon nanotubes (MWCNTs) has been performed using two approaches, direct and indirect cycloaddition through diethyl malonate, based on the Bingel reaction. The results revealed that functionalized MWCNTs demonstrated enhanced electrical properties and significantly lower sheet resistance, especially after electric field thermal assisted annealing at 80 °C was performed. The presence of 1,3-dicarbonyl compounds caused the surface of MWCNTs to be more hydrophilic, approachable for the electrolyte and improved the capacitance performance of Au/MWCNTs electrodes. The modified MWCNTs have been incorporated into nanocomposites by using solution mixing method with polyaniline and drop-casting resulting mixture on the paper substrate. The reduction in the sheet resistance with increasing the content of MWCNTs in the prepared nanocomposite films has been achieved.

  12. Thermoelectric Enhancement in Polyaniline Composites with Polypyrrole-Functionalized Multiwall Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Liu, Jie; Yu, Hui-Qun

    2014-04-01

    This work suggests a facile method to improve the thermoelectric properties of polyaniline (PANi) composites. Carbon multiwall nanotubes (MWNTs) were noncovalently functionalized with polypyrrole (PPy-MWNTs) based on in situ polymerization, and these PPy-MWNTs were used to synthesize PPy-MWNT/PANi composites. The surface-functionalized PPy nanolayer on the MWNTs was found to yield a homogeneous dispersion of MWNTs and strong interfacial adhesion. The resulting composites demonstrated a remarkable enhancement in both electrical conductivity and Seebeck coefficient, and exhibited a high power factor of 3.1 μW/m K2 compared with the values of 0.006 μW/m K2 for PANi and 0.1 μW/m K2 for MWNT/PANi composite at 28.6 wt.% MWNT loading. The obtained results indicate that this method is useful for synthesizing conductive polymer composites with improved thermoelectric performance.

  13. Adsorption thermodynamic and kinetic studies of trihalomethanes on multiwalled carbon nanotubes.

    PubMed

    Lu, Chungsying; Chung, Yao-Lei; Chang, Kuan-Foo

    2006-11-16

    Multiwalled carbon nanotubes (MWCNTs) were purified by mixed HNO3/H2SO4 solution and were employed as adsorbents to study adsorption kinetics and thermodynamics of trihalomethanes (THMs) from chlorinated drinking water. The amount of THMs adsorbed onto CNTs decreased with a rise in temperature and high adsorption capacities were found at 5 and 15 degrees C. Under the same conditions, the purified CNTs possess two to three times more adsorption capacities of CHCl3, which accounts for a major portion of THMs in the chlorinated drinking water, than the commercially available PAC suggesting that CNTs are efficient adsorbents. The thermodynamic analysis revealed that the adsorption of THMs onto CNTs is exothermic and spontaneous.

  14. 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

  15. 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.

  16. 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.

  17. Model analysis of temperature dependence of abnormal resistivity of a multiwalled carbon nanotube interconnection.

    PubMed

    Yeh, Yi-Chen; Chang, Lun-Wei; Miao, Hsin-Yuan; Chen, Szu-Po; Lue, Jhu-Tzang

    2010-01-01

    A homemade microwave plasma-enhanced chemical vapor deposition method was used to grow a multiwalled carbon nanotube between two nickel catalyst electrodes. To investigate the transport properties and electron scattering mechanism of this interconnection (of approximately fixed length and fixed diameter), we carried out a model analysis of temperature dependence of resistivity. To explain the abnormal behavior of the negative temperature coefficient of resistivity in our experimental results, we then employed theories, such as hopping conductivity theory and variable range hopping conductivity theory, to describe resistivity in the high- and low-temperature ranges, respectively. Further, the grain boundary scattering model is also provided to fit the entire measured curve of temperature dependence of resistivity.

  18. Functionalization of multi-walled carbon nanotubes via surface unpaired electrons.

    PubMed

    Zhang, Haijiao; Guo, Huijiao; Deng, Xiaoyong; Gu, Ping; Chen, Zhiwen; Jiao, Zheng

    2010-02-26

    The unpaired electrons on multi-walled carbon nanotubes (MWNTs) treated by nitric-sulfuric mixed acid were detected and characterized by electron spin resonance (ESR). Through reacting with these unpaired electrons, highly soluble acrylamide-grafted MWNTs were successfully prepared and characterized by ESR, FT-IR, UV-vis and atomic force microscopy (AFM), etc. The results indicate that MWNTs could generate more unpaired electrons with longer mixed-acid treatment time and could be well functionalized by acrylamide. By AFM analysis, a 'net' structure was formed on MWNTs after grafting with acrylamide. This new method has some obvious advantages of mild reaction conditions and convenient operation, etc. Furthermore, the grafting of MWNTs may have great potential for biomedical applications in drug delivery and regenerative medicine owing to their excellent networks.

  19. Functionalization of multi-walled carbon nanotubes via surface unpaired electrons

    NASA Astrophysics Data System (ADS)

    Zhang, Haijiao; Guo, Huijiao; Deng, Xiaoyong; Gu, Ping; Chen, Zhiwen; Jiao, Zheng

    2010-02-01

    The unpaired electrons on multi-walled carbon nanotubes (MWNTs) treated by nitric-sulfuric mixed acid were detected and characterized by electron spin resonance (ESR). Through reacting with these unpaired electrons, highly soluble acrylamide-grafted MWNTs were successfully prepared and characterized by ESR, FT-IR, UV-vis and atomic force microscopy (AFM), etc. The results indicate that MWNTs could generate more unpaired electrons with longer mixed-acid treatment time and could be well functionalized by acrylamide. By AFM analysis, a 'net' structure was formed on MWNTs after grafting with acrylamide. This new method has some obvious advantages of mild reaction conditions and convenient operation, etc. Furthermore, the grafting of MWNTs may have great potential for biomedical applications in drug delivery and regenerative medicine owing to their excellent networks.

  20. 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.

  1. 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.

  2. Investigation of activity and stability of papain by adsorption on multi-wall carbon nanotubes.

    PubMed

    Homaei, Ahmad; Samari, Fayezeh

    2017-02-14

    Papain was non-covalently immobilized on multi-walled carbon nanotubes (MWCNTs). Its stabilities and catalytic activity for casein degradation were comprehensively investigated. Compared to free papain, the nano-enzyme exhibited significantly improved thermal, pH and recycling stability. Comparisons of the kinetic parameters between free papain and the heterogeneous enzyme revealed that the Km value of the immobilized papain experienced a slight increase, which suggested that the MWCNTs did not significantly hinder papain's access to substrate or release of product. This feature is beneficial to the industrial applications because of its potential to be easily separated from the end product at the end of the reaction, reuse for multiple times and allow the development of multiple enzyme reaction system.

  3. 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.

  4. Oxidative treatment, dispersion effect, and simulation of multi-walled carbon nanotubes in aqueous solution

    NASA Astrophysics Data System (ADS)

    Song, Kai; Guo, Li-Quan; Chen, Hui

    2017-01-01

    In the present work, the multi-walled carbon nanotubes (MWCNTs) were modified by the treatment with concentrated nitric and sulfuric acid mixture (3: 1 vol/vol). The obtained material was characterized by X-ray diffraction (XRD). The effect of two surfactants, methylcellulose (MC) and cetyltrimethylammonium bromide (CTAB) on dispersing of MWCNTs in aqueous solution was monitored by UV-Vis spectroscopy and transmission electron microscopy (TEM). Also, the dispersing effect of the surfactants was simulated by three-dimensional Monte Carlo method. The results showed that the oxidative treatment leads to purification of the neat MWCNTs, and directly improved their dispersing. The mixture containing both MC and CTAB surfactants has better dispersing effect than individual surfactants. The optimum concentration ratio of MC, CTAB, and MWCNTs was 2: 3: 1. In the simulation model, MWCNTs were dispersed randomly. The simulation results may be helpful for the further research on mechanical and electrical properties of composites reinforced with MWCNTs.

  5. Phonon-glass electron-crystals in ZnO-multiwalled carbon nanotube nanocomposites.

    PubMed

    Nam, Woo Hyun; Kim, Bo Bae; Lim, Young Soo; Dae, Kyun Seong; Seo, Won-Seon; Park, Hyung-Ho; Lee, Jeong Yong

    2017-09-14

    We propose a strategy for enhancing thermoelectric performance through the realization of a 'phonon-glass electron-crystal' (PGEC) by interface control using multiwalled carbon nanotubes (MWCNTs). By the consolidation of undoped ZnO nanoparticles with MWCNTs (0.5, 1, and 2 wt%) using spark plasma sintering, we fabricated the interface-controlled ZnO-MWCNT nanocomposites, in which ZnO grains were surrounded with a MWCNT network. Both single crystal-like charge transport (electron-crystal) and considerably reduced thermal conductivity (phonon-glass) were achieved simultaneously thanks to the beneficial effects of the MWCNT network, and this led to the enhancement of the thermoelectric figure of merit. We discussed these findings on PGECs in the ZnO-MWCNT nanocomposites from the viewpoint of interface control in detail, and our strategy may provide a promising way to the realization of PGEC in other hybrid thermoelectric materials.

  6. 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.

  7. Fast functionalization of multi-walled carbon nanotubes by an atmospheric pressure plasma jet.

    PubMed

    Kolacyak, Daniel; Ihde, Jörg; Merten, Christian; Hartwig, Andreas; Lommatzsch, Uwe

    2011-07-01

    The afterglow of an atmospheric pressure plasma has been used for the fast oxidative functionalization of multi-walled carbon nanotubes (MWCNTs). Scanning electron microscopy and Raman spectroscopy demonstrate that the MWCNT morphology is mostly preserved when the MWCNTs are dispersed in a solvent and injected as a spray into the plasma. Contact angle measurements show that this approach enhances the wettability of MWCNTs and reduces their sedimentation in an aqueous dispersion. X-ray photoelectron spectroscopy, IR spectroscopy, and electrokinetic measurements show that oxygen plasma incorporates about 6.6 at.% of oxygen and creates mainly hydroxyl and carboxyl functional groups on the MWCNT surface. The typical effective treatment time is estimated to be in the range of milliseconds. The approach is ideally suited for combination with the industrial gas phase CVD synthesis of MWCNTs.

  8. DNA methylation changes in human lung epithelia cells exposed to multi-walled carbon nanotubes.

    PubMed

    Sierra, Marta I; Rubio, Laura; Bayón, Gustavo F; Cobo, Isabel; Menendez, Pablo; Morales, Paula; Mangas, Cristina; Urdinguio, Rocio G; Lopez, Virginia; Valdes, Adolfo; Vales, Gerard; Marcos, Ricard; Torrecillas, Ramon; Fernández, Agustin F; Fraga, Mario F

    2017-09-13

    Humans are increasingly exposed to nanoparticles and, although many of their physiological effects have been described, the molecular mechanisms underlying them are still largely unknown. The present study aimed to determine the possible role of certain epigenetic mechanisms in the cellular response of human lung epithelial cells that are triggered by long-term exposure to titanium dioxide nanoparticles (TiO2NPs) and multi-walled carbon nanotubes (MWCNTs). The results showed that exposure to TiO2NPs had only minor effects on genome-wide DNA methylation. However, we identified 755 CpG sites showing consistent DNA hypomethylation in cells exposed to MWCNTs. These sites were mainly located at low density CpG regions and enhancers, and very frequently on the X chromosome. Our results thus suggest that long-term MWCNT exposure may have important effects on the epigenome.

  9. Energy Spread of Field Emission Electrons from Single Pentagons in Individual Multi-Walled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Fujieda, Tadashi; Okai, Makoto; Tokumoto, Hiroshi

    2008-04-01

    We investigated the dependence of tip radius on the field emission energy spread of electrons emitted from clean single pentagons in individual multi-walled carbon nanotubes (MWNTs) in a wide range of total emission currents (10-2000 nA). We found that the full width at half maximum of the field emission energy distribution decreases in inverse proportion to the involution of the radius of curvature at a constant total emission current. This is because as the radius of curvature increases, the space between adjoining pentagons becomes wider, and therefore the stochastic Coulomb interactions between electrons emitted from adjoining pentagons become weaker. The full widths at half maximum of the field emission energy distributions of MWNTs with tip radii of 1.8-45.0 nm were 0.38-0.60 eV at a total emission current of 2000 nA.

  10. 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.

  11. 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.

  12. An electrochemiluminescent sensor for methamphetamine hydrochloride based on multiwall carbon nanotube/ionic liquid composite electrode.

    PubMed

    Dai, Hong; Wang, Youmei; Wu, Xiaoping; Zhang, Lan; Chen, Guonan

    2009-01-01

    In this article, a composite paste electrode consisted of multiwall carbon nanotube (MWCNT) and room temperature ionic liquids (RTILs) was developed for fabrication of electrochemiluminescence (ECL) sensor. The electrochemical and ECL behaviors of this sensor were investigated in detail. This ECL sensor exhibited extraordinary stability during long-term potential cycling. It was found that the light emission of this ECL sensor could be enhanced by methamphetamine hydrochloride (MA.HCl) dramatically. Based on which, a new method based on this ECL sensor has been developed for determination of MA.HCl. The method exhibited a good reproducibility, wide-range linearity, high sensitivity and stability with a detection limit (signal-to-noise ratio=3) of 8.0 x 10(-9)mol/L, and the relative standard deviation was 3.1% for 1 x 10(-5)mol/L MA.HCl (n=10).

  13. 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.

  14. Scribable multi-walled carbon nanotube-silicon nanocomposites: a viable lithium-ion battery system.

    PubMed

    Epur, Rigved; Ramanathan, Madhumati; Datta, Moni K; Hong, Dae Ho; Jampani, Prashanth H; Gattu, Bharat; Kumta, Prashant N

    2015-02-28

    A novel electrode fabrication technique involving a manual scribing action of vertically aligned silicon coated multiwall carbon nanotubes (VASCNTs) on a copper foil have been developed as a viable approach to Li-ion battery electrodes. The scribed electrodes were prepared without the use of any conductive additives and binders, and they were directly assembled in a coin cell. These 'binder-less' scribed Si-CNT electrodes exhibited a very high discharge capacity in excess of 3000 mA h g(-1) and a low first cycle irreversible loss (FIR) (19%). In addition, the electrodes also showed good cyclability with capacity retention of 76% at the end of 50 cycles corresponding to a fade rate of 0.48% loss per cycle rendering the technique attractive for suitable Li-ion applications.

  15. Biomimetic Synthesis of FePt Nanoparticles on Multi-Walled Carbon Nanotubes for Functional Nanomaterials

    NASA Astrophysics Data System (ADS)

    Wang, Li; Wang, Jiku; Li, Zhuang

    2013-02-01

    We present a facile green biomimetic synthesis of FePt nanoparticles (NPs) on the sidewalls of multi-walled carbon nanotubes (CNTs). A core-shell globular protein, ferritin (Fr), was bound onto Z-glycine N-succinimidyl ester (Z-Gly-OSu) modified CNTs and served as precursor to create FePt NPs at the core part of Fr. Biomimetic synthesis of FePt NPs was carried out by chemical reducing of Fe2+ and PtCl_{6}^{2-} ions that transferred into the core part of Fr molecules. The created one-dimensional CNT-FePt nanohybrids were characterized by transmission electron microscopy and X-ray photoelectron spectroscopy. The synthesized CNT-FePt nanohybrids show multi-properties of high water-solubility, ferromagnetism, and electrocatalytic activity.

  16. Preparation of PVA/amino multi-walled carbon nanotubes nanocomposite microspheres for endotoxin adsorption.

    PubMed

    Zong, Wenhui; Chen, Jian; Han, Wenyan; Cheng, Guanghui; Chen, Jie; Wang, Yue; Wang, Weichao; Ou, Lailiang; Yu, Yaoting; Shen, Jie

    2017-03-23

    A novel polyvinyl alcohol-amino multi-walled carbon nanotube (PVA-AMWCNT) nanocomposite microsphere was prepared successfully for the first time and used for endotoxin removal. The resulting AMWCNT modified PVA microsphere was characterized by SEM, Raman spectrum and fluorescence image, which indicated AMWCNT was dispersed into the macropores of PVA microsphere uniformly. The PVA-AMWCNT microspheres showed better adsorption capability and faster adsorption equilibrium for endotoxin in aqueous solution when compared to the PVA microsphere with polymyxin B (PMB) as ligand. More noteworthy, the PVA based microspheres had little nonspecific adsorption in simulated serum. Therefore, PVA-AMWCNT nanocomposite microsphere with an excellent haemocompatibility has a great potential application in clinical blood purification.

  17. Chlorophenol sorption on multi-walled carbon nanotubes: DFT modeling and structure-property relationship analysis.

    PubMed

    Watkins, Marquita; Sizochenko, Natalia; Moore, Quentarius; Golebiowski, Marek; Leszczynska, Danuta; Leszczynski, Jerzy

    2017-02-01

    The presence of chlorophenols in drinking water can be hazardous to human health. Understanding the mechanisms of adsorption under specific experimental conditions would be beneficial when developing methods to remove toxic substances from drinking water during water treatment in order to limit human exposure to these contaminants. In this study, we investigated the sorption of chlorophenols on multi-walled carbon nanotubes using a density functional theory (DFT) approach. This was applied to study selected interactions between six solvents, five types of nanotubes, and six chlorophenols. Experimental data were used to construct structure-adsorption relationship (SAR) models that describe the recovery process. Specific interactions between solvents and chlorophenols were taken into account in the calculations by using novel specific mixture descriptors.

  18. Rheology, Morphology and Temperature Dependency of Nanotube Networks in Polycarbonate/Multiwalled Carbon Nanotube Composites

    NASA Astrophysics Data System (ADS)

    Abbasi, Samaneh; Derdouri, Abdessalem; Carreau, Pierre J.

    2008-07-01

    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.

  19. Gold nanoparticle decorated multi-walled carbon nanotubes as counter electrode for dye sensitized solar cells.

    PubMed

    Kaniyoor, Adarsh; Ramaprabhu, Sundara

    2012-11-01

    A novel counter electrode material for dye sensitized solar cells (DSSCs) composed of nanostructured Au particles decorated on functionalized multi-walled carbon nanotubes (f-MWNTs) is demonstrated for the first time. MWNTs synthesized by catalytic chemical vapor deposition technique are purified and functionalized by treating with concentrated acids. Au nanoparticles are decorated on f-MWNTs by a rapid and facile microwave assisted polyol reduction method. The materials are characterized by X-ray diffractometry, Fourier transform infra red spectroscopy and electron microscopy. The DSSC fabricated with Au/f-MWNTs based counter electrode shows enhanced power conversion efficiency (eta) of 4.9% under AM 1.5G simulated solar radiation. In comparison, the reference DSSCs fabricated with f-MWNTs and Pt counter electrodes show eta of 2.1% and 4.5%. This high performance of Au/f-MWNTs counter electrode is investigated using electrochemical impedance spectroscopy and cyclic voltammetry studies.

  20. Multiwalled carbon nanotubes produced by direct current arc discharge in hydrogen gas

    NASA Astrophysics Data System (ADS)

    Jinno, M.; Bandow, S.; Ando, Y.

    2004-11-01

    Multiwalled carbon nanotubes were produced by direct current (DC) arc discharge in the mixture gas of H 2-N 2. Raman scattering spectroscopy was used to characterize the MWNTs. Radial breathing mode vibration signals were observed at 272 and 388 cm -1. Tangential mode vibration signal was observed at ≈1582 cm -1, and other intense signals were also observed at ≈1860 cm -1for the MWNTs produced in the gas with the H 2 contents exceeding 90%. DC arc discharge in pure D 2 was also carried out, by which it was confirmed that the peak position and intensity of the Raman signal at ≈1860 cm -1 were independent of whether the gas was H 2 or D 2. This suggests that the ≈1860 cm -1 band is not associated with hydrogen-based vibrations.

  1. 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%.

  2. 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.

  3. 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.

  4. 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.

  5. 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

    2013-09-07

    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.

  6. Transport characteristics of a single multiwall carbon nanotube by bending in SEM and STM

    NASA Astrophysics Data System (ADS)

    Kim, Suenne; Kim, Jeehoon; Berg, Morgann; de Lozanne, Alex

    2007-03-01

    Multiwall carbon nanotubes(MWCNTs) were grown on a W wire by chemical vapor deposition(CVD). Two homebuilt xyz-walkers were employed to manipulate individual CNTs in our scanning electron microscope (SEM). To improve the electrical and mechanical contact to a second electrode, we welded the CNT by delivering gas to the welding point while focusing the SEM beam on the same spot. The bending dependent I-V characteristics were observed in situ in the SEM at room temperature. We will measure the transport properties by bending the same MWCNT (already measured in SEM) inside our ultrahigh vacuum low temperature scanning tunneling microscope (UHV-LTSTM). We will also compare the bending properties of MWCNTs at different temperatures.

  7. Improvement in characteristics of natural rubber nanocomposite by surface modification of multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Takeuchi, Kenji; Noguchi, Toru; Ueki, Hiroyuki; Niihara, Ken-ichi; Sugiura, Tomoyoshi; Inukai, Shigeki; Fujishige, Masatsugu

    2015-05-01

    We aim to develop high-level applications of NR through the innovative use of multi-walled carbon nanotubes (MWCNTs) to improve reinforcing performance and thermal resistance. In this study, we examined the structures and characteristics of composite materials in which NR was the matrix and MWCNTs were the fillers. We studied the properties of composites containing surface-activated MWCNTs with three different diameters. The results show that the reinforcing performance improves as MWCNT diameter decreases, while thermal resistance improves as we decrease the heat-treatment temperature. The latter occurs because adherence between MWCNTs and NR becomes stronger at lower heat-treatment temperatures. We also found that for practical applications, we need to control active sites on MWCNTs to balance adhesion against thermal resistance.

  8. Alternative mannosylation method for nanomaterials: application to oxidized debris-free multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    de Sousa, Marcelo; Martinez, Diego Stéfani Teodoro; Alves, Oswaldo Luiz

    2016-06-01

    Mannosylation is a method commonly used to deliver nanomaterials to specific organs and tissues via cellular macrophage uptake. In this work, for the first time, we proposed a method that involves the binding of d-mannose to ethylenediamine to form mannosylated ethylenediamine, which is then coupled to oxidized and purified multiwalled carbon nanotubes. The advantage of this approach is that mannosylated ethylenediamine precipitates in methanol, which greatly facilitates the separation of this product in the synthesis process. Carbon nanotubes were oxidized using concentrated H2SO4 and HNO3 by conventional reflux method. However, during this oxidation process, carbon nanotubes generated carboxylated carbonaceous fragments (oxidation debris). These by-products were removed from the oxidized carbon nanotubes to ensure that the functionalization would occur only on the carbon nanotube surface. The coupling of mannosylated ethylenediamine to debris-free carbon nanotubes was accomplished using n-(3-dimethylaminopropyl)-n-ethylcarbodiimide and n-hydroxysuccinimide. Deconvoluted N1s spectra obtained from X-ray photoelectron spectroscopy gave binding energies of 399.8 and 401.7 eV, which we attributed to the amide and amine groups, respectively, of carbon nanotubes functionalized with mannosylated ethylenediamine. Deconvoluted O1s spectra showed a binding energy of 532.4 eV, which we suggest is caused by an overlap in the binding energies of the aliphatic CO groups of d-mannose and the O=C group of the amide bond. The functionalization degree was approximately 3.4 %, according to the thermogravimetric analysis. Scanning electron microscopy demonstrated that an extended carbon nanotube morphology was preserved following the oxidation, purification, and functionalization steps.

  9. 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

  10. Lightning Damage of Carbon Fiber/Epoxy Laminates with Interlayers Modified by Nickel-Coated Multi-Walled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Dong, Qi; Wan, Guoshun; Xu, Yongzheng; Guo, Yunli; Du, Tianxiang; Yi, Xiaosu; Jia, Yuxi

    2017-02-01

    The numerical model of carbon fiber reinforced polymer (CFRP) laminates with electrically modified interlayers subjected to lightning strike is constructed through finite element simulation, in which both intra-laminar and inter-laminar lightning damages are considered by means of coupled electrical-thermal-pyrolytic analysis method. Then the lightning damage extents including the damage volume and maximum damage depth are investigated. The results reveal that the simulated lightning damages could be qualitatively compared to the experimental counterparts of CFRP laminates with interlayers modified by nickel-coated multi-walled carbon nanotubes (Ni-MWCNTs). With higher electrical conductivity of modified interlayer and more amount of modified interlayers, both damage volume and maximum damage depth are reduced. This work provides an effective guidance to the anti-lightning optimization of CFRP laminates.

  11. Application of multi-walled carbon nanotubes modified carbon ionic liquid electrode for electrocatalytic oxidation of dopamine.

    PubMed

    Li, Yonghong; Liu, Xinsheng; Liu, Xiaoying; Mai, Nannan; Li, Yuandong; Wei, Wanzhi; Cai, Qingyun

    2011-11-01

    A simple, sensitive, and reliable method based on a multi-walled carbon nanotubes (MWNTs) modified carbon ionic liquid electrode (CILE) has been successfully developed for determination of dopamine (DA) in the presence of ascorbic acid (AA). The acid-treated MWNTs with carboxylic acid functional groups could promote the electron-transfer reaction of DA and inhibit the voltammetric response of AA. Due to the good performance of the ionic liquid, the electrochemical response of DA on the MWNTs/CILE was better than that of other MWNTs modified electrodes. Under the optimum conditions a linear calibration plot was obtained in the range 5.0×10(-8) to 2.0×10(-4) mol L(-1) and the detection limit was 1.0×10(-8) mol L(-1).

  12. Adsorption of methyl green dye onto multi-walled carbon nanotubes decorated with Ni nanoferrite

    NASA Astrophysics Data System (ADS)

    Bahgat, Mohamed; Farghali, Ahmed Ali; El Rouby, Waleed; Khedr, Mohamed; Mohassab-Ahmed, Mohassab Y.

    2013-06-01

    This research was carried out to evaluate the capability of multi-walled carbon nanotubes (CNTs) and NiFe2O4-decorated multi-walled carbon nanotubes (NiFe2O4-CNTs) toward waste water treatment relevant to organic dyes. CNTs were prepared via chemical vapor deposition method. NiFe2O4-CNTs were prepared by in-situ chemical precipitation of metal hydroxides followed by hydrothermal processing. The samples were characterized using XRD and TEM. The adsorption efficiency of CNTs and NiFe2O4-CNTs of methyl green dye at various temperatures was examined. The adsorbed amount increased with the CNTs and NiFe2O4-CNTs dosage. The linear correlation coefficients and standard deviations of Langmuir and Freundlich isotherms were determined. It was found that Langmuir isotherm fitted the experimental results well in both adsorption cases n of methyl green onto CNTs and NiFe2O4-CNTs. Kinetics analyses were conducted using pseudo first-order, second-order and the intraparticle diffusion models. The results showed that the adsorption kinetics was controlled by a pseudo second-order model for adsorption of methyl green onto CNTs and best controlled by pseudo first-order in case of NiFe2O4-CNTs. Changes in the free energy of adsorption (Δ G°), enthalpy (Δ H°), entropy (Δ S°), and the activation energy ( E a) were determined. The Δ H°, Δ G° and E a values indicated that the adsorption of methyl green onto MWCNTs and NiFe2O4-MWCNTs was physisorption.

  13. Size- and shape-dependent pleural translocation, deposition, fibrogenesis, and mesothelial proliferation by multiwalled carbon nanotubes

    PubMed Central

    Xu, Jiegou; Alexander, David B; Futakuchi, Mitsuru; Numano, Takamasa; Fukamachi, Katsumi; Suzui, Masumi; Omori, Toyonori; Kanno, Jun; Hirose, Akihiko; Tsuda, Hiroyuki

    2014-01-01

    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. PMID:24815191

  14. 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.

  15. Adsorption of crystal violet onto functionalised multi-walled carbon nanotubes: Equilibrium and kinetic studies.

    PubMed

    Sabna, V; Thampi, Santosh G; Chandrakaran, S

    2016-12-01

    Synthetic dyes present in effluent from textile, paper and paint industries contain crystal violet (CV), a known carcinogenic agent. This study investigates the modification of multiwalled carbon nanotubes by acid reflux method and equilibrium and kinetic behaviour of adsorption of CV onto functionalized multi-walled carbon nanotubes (fMWNTs) in batch system. High stability of the fMWNTs suspension in water indicates the hydrophilicity of fMWNTs induced due to the formation of functional groups that make hydrogen bonds with water molecules. fMWNTs were characterized by Fourier Transform Infra Red (FTIR) spectroscopy and the functional groups present on the fMWNTs were confirmed. Characteristic variation was observed in the FTIR spectra of fMWNTs after adsorption of crystal violet onto it. Adsorption characteristics were evaluated as a function of system variables such as contact time, dosage of fMWNTs and initial concentration and pH of the crystal violet solution. Adsorption capacity of fMWNTs and percentage removal of the dye increased with increase in contact time, adsorbent dosage and pH but declined with increase in initial concentration of the dye. fMWNTs showed higher adsorption capacity compared to that of pristine MWNTs. Data showed good fit with the Langmuir and Freundlich isotherm models and the pseudo-second order kinetic model; the maximum adsorption capacity was 90.52mg/g. Kinetic parameters such as rate constants, equilibrium adsorption capacities and regression coefficients were estimated. Results indicate that fMWNTs are an effective adsorbent for the removal of crystal violet from aqueous solution.

  16. 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.

  17. Cs + sputtered clusters from multi-walled carbon nanotubes, graphite and the structural transformations

    NASA Astrophysics Data System (ADS)

    Ahmad, Shoaib; Javeed, Sumera; Zeeshan, Sumaira; Naeem, Athar; Saadat, Shahzad; Yousuf, Muhammad; Khaleel, Muhammad; Mushtaq, Ahsan; Shahnawaz, Muhammad

    2012-01-01

    Experiments with multi-walled carbon nanotubes (MWCNTs) and graphite as targets in a source of negative ions with cesium sputtering show that MWCNTs with nanometer radii and micrometer length can be compared with micrometer-size graphite grains. The comparative study helps to better understand the irradiation effects, including the formation, sputtering of carbon clusters and the resulting structural changes. The simultaneous adsorption of Cs 0 on the surface and bombardment by energetic Cs + ions is shown to play a role in cluster formation and sputtering of carbon atoms and clusters (C x; x ⩾ 1) and the cesium-substituted carbon clusters (CsC x) as anions. Qualitative and quantitative outputs of sputtered species are related to their respective structures. Structural changes are shown to occur in MWCNTs and seen in scanning electron micrographs. The individual identity of the heavily bombarded MWCNTs may have given way to the merged structures while effects on the structure of heavily irradiated graphite grains size needs to be further investigated.

  18. ABTS-modified multiwalled carbon nanotubes as an effective mediating system for bioelectrocatalytic reduction of oxygen.

    PubMed

    Karnicka, Katarzyna; Miecznikowski, Krzysztof; Kowalewska, Barbara; Skunik, Magdalena; Opallo, Marcin; Rogalski, Jerzy; Schuhmann, Wolfgang; Kulesza, Pawel J

    2008-10-01

    The ability of such a common redox mediator as 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) to undergo sorption on carbon surfaces is explored here to convert multiwalled carbon nanotubes (CNTs) into a stable colloidal solution of ABTS-modified carbon nanostructures, the diameters of which are approximately 10 nm (as determined by transmission electron microscopy). Subsequently, inks composed of fungal laccase (Cerrena unicolor) mixed with the dispersion of ABTS-modified CNTs and stabilized with Nafion, were deposited on glassy carbon and successfully employed to the reduction of oxygen in McIlvain buffer at pH 5.2. For comparison, the systems utilizing only ABTS-free CNTs and laccase as well as ABTS-modified CNTs did not show appreciable activity toward the oxygen reduction. The three-dimensionally distributed ABTS-modified CNTs are expected to improve the film's overall conductivity and to facilitate electrical connection between the electrode and the enzyme. The network film of ABTS-modified CNTs is rigid, and it is characterized by charge propagation capabilities comparable to the conventional redox polymers. The whole concept of utilization of CNTs modified with ultrathin films of redox mediators in the preparation of efficient bioelectrocatalytic films seems to be of general importance to electroanalytical chemistry and to the development of biosensors.

  19. Multi-walled Carbon Nanotubes Reduce Toxicity of Diphenhydramine to Ceriodaphnia dubia in Water and Sediment Exposures.

    PubMed

    Myer, Mark H; Black, Marsha C

    2017-08-09

    Multi-walled carbon nanotubes are adsorptive materials that have potential for remediation of organic contaminants in water. Sediment elutriate exposures were undertaken with Ceriodaphnia dubia to compare the toxic effects of diphenhydramine in the presence and absence of sediment and multi-walled carbon nanotubes. In both sediment and solution-only treatments, addition of 0.318 mg/g of carbon nanotubes significantly decreased 48-h mortality relative to control, with a 78.7%-90.1% reduction in treatments with nanotube-amended sediment and 40.7%-53.3% reduction in nanotube-amended water exposures. The greatest degree of relative mortality reduction occurred in sediments containing higher levels of natural organic matter, indicating a potential additive effect.

  20. 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.

  1. The effect of ultrasonic processing of multi-wall carbon nanotubes on properties of elastomeric compositions on the basis of synthetic isoprene rubber

    NASA Astrophysics Data System (ADS)

    Mitryaeva, N. S.; Myshlyavtsev, A. V.; Akimenko, S. S.

    2017-08-01

    The paper studies the effect of ultrasonic processing on the vulcanizing, physical, mechanical and electrophysical properties of elastomeric compositions based on synthetic isoprene rubber. Microscopic studies of multi-wall carbon nanotubes samples before and after ultrasonic processing are carried out. Due to the research, the applied ultrasonic processing method provides splitting of bundles formed from multi-wall carbon nanotubes. This results in elastomeric material with increased strength and high electrical conductivity with a low concentration of nanofiller.

  2. Adsorption of diuron, fluridone and norflurazon on single-walled and multi-walled carbon nanotubes.

    PubMed

    Sun, Ke; Zhang, Zheyun; Gao, Bo; Wang, Ziying; Xu, Dongyu; Jin, Jie; Liu, Xitao

    2012-11-15

    The sorption behaviors of diuron (DIU), fluridone (FLU) and norflurazon (NOR) by a single-walled carbon nanotube (SWCNT) and three multi-walled carbon nanotubes (MWCNT) samples including MWCNT10 (<10nm, outer diameter), MWCNT20 (10-20 nm), and MWCNT40 (20-40 nm) were investigated. All adsorption isotherms were nonlinear and were well fitted with the Freundlich model and Dubinin Ashtakhov (DA) model. The linear relationships between the organic carbon (OC)-normalized saturated adsorption capacity (Q(0)(OC)) and surface area (SA) suggest that SA is presumably responsible for the adsorption of DIU and NOR on CNTs. While FLU, DIU, and NOR OC-normalized distribution coefficients (logK(OC)) of CNTs increased with increasing their hydrophobicity (logK(OW)) and the positive relationships between the logK(OW)-normalized logK(OC) (i.e., logK(OC)/logK(OW)) of FLU, DIU, and NOR and their hydrogen bonding ability indicate that the adsorption of FLU, DIU and NOR was mainly controlled by the hydrophobic interaction and hydrogen bonding. The higher logK(OC) or Q(0)(OC) values of MWCNT10 and SWCNT relative to other large MWCNTs and carbonaceous adsorbents suggest that MWCNT10 has the potential to serve as an adsorbent used to reduce the mobility of herbicides in agricultural and environmental applications. Copyright © 2012 Elsevier B.V. All rights reserved.

  3. 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.

  4. 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.

  5. Nitrogen-doped multiwall carbon nanotubes for lithium storage with extremely high capacity.

    PubMed

    Shin, Weon Ho; Jeong, Hyung Mo; Kim, Byung Gon; Kang, Jeung Ku; Choi, Jang Wook

    2012-05-09

    The increasing demands on high performance energy storage systems have raised a new class of devices, so-called lithium ion capacitors (LICs). As its name says, LIC is an intermediate system between lithium ion batteries and supercapacitors, designed for taking advantages of both types of energy storage systems. Herein, as a quest to improve the Li storage capability compared to that of other existing carbon nanomaterials, we have developed extrinsically defective multiwall carbon nanotubes by nitrogen-doping. Nitrogen-doped carbon nanotubes contain wall defects through which lithium ions can diffuse so as to occupy a large portion of the interwall space as storage regions. Furthermore, when integrated with 3 nm nickel oxide nanoparticles for a further capacity boost, nitrogen doping enables unprecedented cell performance by engaging anomalous electrochemical phenomena such as nanoparticles division into even smaller ones, their agglomeration-free diffusion between nitrogen-doped sites as well as capacity rise with cycles. The final cells exhibit a capacity as high as 3500 mAh/g, a cycle life of greater than 10,000 times, and a discharge rate capability of 1.5 min while retaining a capacity of 350 mAh/g.

  6. 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. Copyright © 2015 Elsevier B.V. All rights reserved.

  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. Nitrogen-induced catalyst restructuring for epitaxial growth of multiwalled carbon nanotubes.

    PubMed

    Pattinson, Sebastian W; Ranganathan, Vinay; Murakami, Hajime K; Koziol, Krzysztof K K; Windle, Alan H

    2012-09-25

    The ability to simply and economically produce carbon nanotubes (CNTs) with a defined chiral angle is crucial for the exploitation of nanotubes for their electrical properties. We investigate a diverse range of nitrogen sources for their ability to control CNT chiral angle via epitaxial growth from highly ordered catalyst particles. Through the use of in situ mass and infrared spectrometry, we elucidate the mechanism by which these ordered catalyst particles are formed, showing that ammonia is a key intermediate in the process. Subsequently, the direct addition of a small amount of ammonia to an otherwise standard CNT synthesis is shown to be able to form catalyst particles that grow single chiral angle multiwalled carbon nanotubes. Variation in the ammonia concentration clarifies the catalyst restructuring necessary for the epitaxial growth of carbon nanotubes and subsequent chiral angle control. The simple addition of a nitrogen source is an attractive route for chiral angle control; however, the model also suggests further ways to optimize CNT chiral angle distributions as well as to improve CNT and graphene yield and crystallinity. This understanding also explains the action of ammonia in its widely used role in activating catalyst prior to CNT growth. Finally, this work highlights the uses of novel surface geometries that are achievable through multiphase catalysts.

  9. Purification and sidewall functionalization of multiwalled carbon nanotubes and resulting bioactivity in two macrophage models

    PubMed Central

    Hamilton, Raymond F.; Xiang, Chengcheng; Li, Ming; Ka, Ibrahima; Yang, Feng; Ma, Dongling; Porter, Dale W.; Wu, Nianqiang; Holian, Andrij

    2014-01-01

    This study examined the consequences of surface carboxylation of multiwalled carbon nanotubes (MWCNT) on bioactivity. Since commercial raw MWCNT contain impurities that may affect their bioactivity, HCl refluxing was exploited to purify raw “as-received” MWCNT by removing the amorphous carbon layer on the MWCNT surface and reducing the metal impurities (e.g. Ni). The removal of amorphous carbon layer was confirmed by Raman spectroscopy and thermogravimetric analysis. Furthermore, the HCl-purified MWCNT provided more available reaction sites, leading to enhanced sidewall functionalization. The sidewall of HCl-purified MWCNT was further functionalized with the −COOH moiety by HNO3 oxidation. This process resulted in four distinct MWCNT: raw, purified, −COOH-terminated raw MWCNT, and −COOH-terminated purified MWCNT. Freshly isolated alveolar macrophages from C57Bl/6 mice were exposed to these nanomaterials to determine the effects of the surface chemistry on the bioactivity in terms of cell viability and inflammasome activation. Inflammasome activation was confirmed using inhibitors of cathepsin B and Caspase-1. Purification reduced the cell toxicity and inflammasome activation slightly compared to raw MWCNT. In contrast, functionalization of MWCNT with the −COOH group dramatically reduced the cytotoxicity and inflammasome activation. Similar results were seen using THP-1 cells supporting their potential use for high-throughput screening. This study demonstrated that the toxicity and bioactivity of MWCNT were diminished by removal of the Ni contamination and/or addition of −COOH groups to the sidewalls. PMID:23480196

  10. Contact resistance of multi-walled carbon nanotube/natural rubber nanocomposites with metallic ball

    NASA Astrophysics Data System (ADS)

    Sugiura, Tomoyoshi; Fujishige, Masatsugu; Noguchi, Toru; Ueki, Hiroyuki; Niihara, Ken-ichi; Takeuchi, Kenji

    2016-12-01

    This paper reports on the contact resistance (Rc) between carbon filler/natural rubber (NR) nanocomposite and gold ball: three varieties of nanocomposites were prepared from carbon black (CB) and two kinds of multi-walled carbon nanotubes (MWCNTs) with different diameter. Rc of MWCNT/NR nanocomposite was remarkably less than that of CB/NR nanocomposites. The relationship between Rc of MWCNT/NR nanocomposites and applied load was expressed in the formula, Rc=C·P-n (P: load, C and n: constant): for the MWCNTs (diameters of 13 nm)/NR and MWCNTs (diameters of 67 nm)/ NR nanocomposites, they were expressed as Rc=1724·P-0.6 and Rc=344·P-0.37, respectively. The former (MWCNT, ϕ13 nm) showed higher Rc than the latter (MWCNT, ϕ67 nm) over whole region of applied load. The mechanical hardness of the former was higher (90 HsA) than that of the latter (82 HsA). Therefore, the smaller contact area between the nanocomposite and gold ball of the former resulted in higher Rc. The apparent specific contact resistivity was calculated from the observed values of Rc and contact area: 130 Ω mm2 and 127 Ω mm2 for the former (MWCNT, ϕ13 nm) and the latter (MWCNT, ϕ67 nm), respectively.

  11. DJ-1 as a potential biomarker for the development of biocompatible multiwalled carbon nanotubes

    PubMed Central

    Haniu, Hisao; Tsukahara, Tamotsu; Matsuda, Yoshikazu; Usui, Yuki; Aoki, Kaoru; Shimizu, Masayuki; Ogihara, Nobuhide; Hara, Kazuo; Takanashi, Seiji; Okamoto, Masanori; Ishigaki, Norio; Nakamura, Koichi; Kato, Hiroyuki; Saito, Naoto

    2011-01-01

    Background In the present study, we investigated whether DJ-1 could serve as a biomarker for assessing the biocompatibility of multiwalled carbon nanotubes (MWCNTs), using the highly purified carbon nanotube, HTT2800. Methods Using Western blot analysis, we determined DJ-1 protein levels in two different types of cells (one capable and the other incapable of HTT2800 endocytosis). Using quantitative real-time polymerase chain reaction, we also investigated the ability of purified nanotubes to alter DJ-1 mRNA levels. Results We demonstrated that the DJ-1 protein concentration was reduced, regardless of the cytotoxic activity of intracellular HTT2800. Furthermore, HTT2800 decreased the DJ-1 mRNA levels in a dose-dependent manner. This decrease in DJ-1 mRNA levels was not observed in the case of Sumi black or cup-stacked carbon nanotubes. Conclusion These data indicate that modification of DJ-1 expression is caused by the cell response to MWCNTs. We conclude that DJ-1 is a promising candidate biomarker for the development of biocompatible MWCNTs. PMID:22114499

  12. Purification and dispersibility of multi-walled carbon nanotubes in aqueous solution

    NASA Astrophysics Data System (ADS)

    Chen, Yuanzhao; Li, Zhenxia; Zhao, Yang

    2016-12-01

    In this paper, the pristine multi-walled carbon nanotubes (P-MWCNTs) were purified either by the high temperature treatment (HT-MWCNTs) or by concentrated acid treatment (CA-MWCNTs). The HT-MWCNTs were prepared by heating at 500°C, while the CA-MWCNTs were treated by the mixture of concentrated nitric and sulfuric acids taken in a volume ratio of 3: 1. Ultrasonic processing and surfactants were utilized to achieve homogenous MWCNTs suspensions. The HT-MWCNTs and CA-MWCNTs were characterized by thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FT-IR). Among these three MWCNTs, the prepared homogeneously dispersed MWCNTs suspensions were characterized by UV-Vis absorbency and transmission electron microscopy (TEM). Finally, the dispersion mechanism was discussed. The results showed that both high temperature treatment and concentrated acid treatment can be used for purification of the P-MWCNTs, removing the amorphous carbon and other impurities. In these suspensions, the purified MWCNTs showed a better dispersibility in aqueous solution. The high temperature treatment was a kind of physical purification treatment method and it just burned the amorphous carbon away and strengthened the structure of MWCNTs, while the concentrated acid treatment was a chemical purification treatment method and this chemical treatment method grafted more effective groups to improve the dispersibility of MWCNTs.

  13. Evaluation of a pyroelectric detector with a carbon multiwalled nanotube black coating in the infrared.

    PubMed

    Theocharous, E; Deshpande, R; Dillon, A C; Lehman, J

    2006-02-20

    The performance of a pyroelectric detector with a carbon multiwalled nanotube coating was evaluated in the 0.9-14 microm 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 microm 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.

  14. 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.

  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. Dispersion of Multi-Walled Carbon Nanotubes by Polymers with Carbazole Pendants.

    PubMed

    Liang, Caizhen; Wang, Bin; Chen, Jianjun; Yong, Qiwen; Huang, Yuewen; Liao, Bing

    2017-09-07

    For various applications, it is essential to enhance the colloidal stabilization of carbon nanotube (CNT) dispersions. Here, the polymers with carbazole pendants of poly(4-(N-carbazolyl)methylstyrene-bl-poly(ethylene glycol) methyl ether methacrylate) (PCMS5-b-PAPEG73 and PCMS16-b-PAPEG43) and PCMS30, synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization, were used for noncovalent functionalization of multiwalled carbon nanotubes (MWCNTs) in tetrahydrofuran (THF), offering efficient colloidal stabilization. Meanwhile, the adsorption of polymers onto MWCNTs was investigated. The results showed that the MWCNTs decorated with these three polymers in THF exhibited different colloidal stabilization and adsorption capacity. Moreover, the MWCNT dispersions could be stabilized for days and their colloidal stabilization elevated with the increase of polymer concentrations. The block copolymer PCMS16-b-PAPEG43 exhibited the optimal adsorption and dispersion capability for MWCNTs. These findings imply that PCMSm-b-PAPEGn will be a desirable dispersant for optimizing the stabilization of CNT dispersion, making carbon nanotubes (CNTs) achievable in different applications.

  17. The doping effect of multiwall carbon nanotube on MgB2/Fe superconductor wire

    NASA Astrophysics Data System (ADS)

    Kim, J. H.; Yeoh, W. K.; Qin, M. J.; Xu, X.; Dou, S. X.

    2006-07-01

    We evaluated the doping effect of two types of multiwall carbon nanotubes (CNTs) with different aspect ratios on MgB2/Fe monofilament wires. Relationships between microstructure, magnetic critical current density (Jc), critical temperature (Tc), upper critical field (Hc2), and irreversibility field (Hirr) for pure and CNT doped wires were systematically studied for sintering temperature from 650to1000°C. As the sintering temperature increased, Tc for short CNT doped sample slightly decreased, while Tc for long CNT doped sample increased. This indicates better reactivity between MgB2 and short CNT due to its small aspect ratio, and substitution of carbon (C) from short CNT for boron (B) occurs. In addition, short CNT doped samples sintered at high temperatures of 900 and 1000°C exhibited excellent Jc, and this value was approximately 104A /cm2 in fields up to 8T at 5K. This suggests that short CNT is a promising carbon source for MgB2 superconductor with excellent Jc. In particular, inclusion of nanosized MgO particles and substitution of C into the MgB2 lattice could result in strong flux pinning centers.

  18. Multi-walled carbon nanotubes affect drug transport across cell membrane in rat astrocytes

    NASA Astrophysics Data System (ADS)

    Chen, Xiao; Schluesener, Hermann J.

    2010-03-01

    The impact of carbon nanotubes on the cell membrane is an aspect of particular importance and interest in the study of carbon nanotubes' interactions with living systems. One of the many functions of the cell membrane is to execute substance transport into and out of the cell. We investigated the influence of multi-walled carbon nanotubes (MWCNTs) on the transport of several compounds across in the cell membrane of rat astrocytes using flow cytometry. These compounds are fluorescein diacetate, carboxyfluorescein diacetate, rhodamine 123 and doxorubicin, which are prosubstrate/substrates of multidrug transporter proteins. Results showed that MWCNTs significantly inhibited cellular uptake of doxorubicin but not the other drugs and the mode of loading made a significant difference in doxorubicin uptake. Retention of fluorescein, carboxyfluorescein and rhodamine 123 was remarkably higher in MWCNT-exposed cells after an efflux period. A kinetics study also demonstrated slower efflux of intracellular fluorescein and rhodamine 123. Data presented in this paper suggest that MWCNTs could affect drug transport across cell membranes. The implications of the findings are discussed.

  19. 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.

  20. Organic MEMS devices and MWCNT (multi-wall carbon nanotube) interconnects

    NASA Astrophysics Data System (ADS)

    Lempkowski, Robert B.; Qian, Zhengfang

    2010-04-01

    RF system front ends need to be mounted on a circuit board and interconnected to other devices such as antennas and surrounding circuitry functions. Providing suitable RF performing interconnects between or within devices on multi-layer construction has been done typically with doped semiconductors, copper, and occasionally other conductors. This paper discusses the use of organic printed circuit board MEMS switches and varactors, and the use of multi-wall carbon nanotubes as transmission lines and antennas. Carbon nanotube active transistors use single wall carbon nanotubes (SWCNT) with efforts to improve percentages of semiconducting structures. Interconnects are needed not only to connect CNT devices to each other, but to larger structures in order to be able to use subsystems that integrate CNT devices, large scale multifunction ICs, and RF devices used in RF front ends, including antennas. This paper addresses the use of organic substrates as the media for integration of MEMS, interconnects to devices on the substrate, and planar antennas. These methods will be required until complete assembly of all devices and interconnects can be done with processes at the nano-scale level, which is assumed to still need efficient radiative antenna structures at a larger scale for commonly used consumer wireless products.

  1. 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

    2016-04-05

    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.

  2. Diffusion of multiwall carbon nanotubes (MWCNTs) through a high density polyethylene (HDPE) geomembrane.

    PubMed

    Saheli, P T; Rowe, R K; Petersen, E J; O'Carroll, D M

    2017-05-01

    The new applications for carbon nanotubes (CNTs) in various fields and consequently their greater production volume have increased their potential release to the environment. Landfills are one of the major locations where carbon nanotubes are expected to be disposed and it is important to ensure that they can limit the release of CNTs. Diffusion of multiwall carbon nanotubes (MWCNTs) dispersed in an aqueous media through a high-density polyethylene (HDPE) geomembrane (as a part of the landfill barrier system) was examined. Based on the laboratory tests, the permeation coefficient was estimated to be less than 5.1×10(-15) m(2)/s. The potential performance of a HDPE geomembrane and geosynthetic clay liner (GCL) as parts of a composite liner in containing MWCNTs was modelled for six different scenarios. The results suggest that the low value of permeation coefficient of an HDPE geomembrane makes it an effective diffusive barrier for MWCNTs and by keeping the geomembrane defects to minimum during the construction (e.g., number of holes and length of wrinkles) a composite liner commonly used in municipal solid waste landfills will effectively contain MWCNTs.

  3. Genotoxicity of multi-walled carbon nanotubes at occupationally relevant doses

    PubMed Central

    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. PMID:24479647

  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

    2014-01-30

    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. 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.

  6. Removal of cationic dyes from aqueous solution using magnetic multi-wall carbon nanotube nanocomposite as adsorbent.

    PubMed

    Gong, Ji-Lai; Wang, Bin; Zeng, Guang-Ming; Yang, Chun-Ping; Niu, Cheng-Gang; Niu, Qiu-Ya; Zhou, Wen-Jin; Liang, Yi

    2009-05-30

    A magnetic multi-wall carbon nanotube (MMWCNT) nanocomposite was synthesized and was used as an adsorbent for removal of cationic dyes from aqueous solutions. The MMWCNT nanocomposite was composed of commercial multi-wall carbon nanotubes and iron oxide nanoparticles. The properties of this magnetic adsorbent were characterized by scanning electron microscopy, X-ray diffraction and BET surface area measurements. Adsorption characteristics of the MMWCNT nanocomposite adsorbent were examined using methylene blue, neutral red and brilliant cresyl blue as adsorbates. Experiments were carried out to investigate adsorption kinetics, adsorption capacity of the adsorbent and the effect of adsorption dosage and solution pH values on the removal of cationic dyes. Kinetic data were well fitted by a pseudo second-order model. Freundlich model was used to study the adsorption isotherms. The prepared MMWCNT adsorbent displayed the main advantage of separation convenience compared to the present adsorption treatment.

  7. Multiwalled carbon nanotubes@octavinyl polyhedral oligomeric silsesquioxanes nanocomposite preparation via cross-linking reaction in acidic media

    NASA Astrophysics Data System (ADS)

    Somasekharan, Lakshmipriya; Thomas, Sabu; Comoy, Corinne; Sivasankarapillai, Anilkumar; Kalarikkal, Nandakumar; Lamouroux, Emmanuel

    2016-11-01

    Multiwalled carbon nanotubes have unique properties allowing their use in a wide range of applications—from microelectronics to biomedical and polymer fields. Nevertheless, a crucial aspect for their use resides in the ease of handling them during the process. Here, we report a facile route to prepare multiwalled carbon nanotubes@octavinyl polyhedral oligomeric silsesquioxanes (MWCNT@POSS) nanocomposite. The method involves the formation of a covalent bond between carboxylated MWCNTs and OV-POSS using acid-catalyzed electrophilic addition reaction. The resulting nanocomposite have been characterized by Fourier transform infrared spectroscopy (FTIR), powder X-Ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). The results confirmed that the formation of MWCNT@POSS nanocomposite did not deteriorate MWCNT structure or morphology. Here, we used a 1:1 ratio of carboxylated MWCNTs and OV-POSS and the POSS content in the nanocomposite was 39.5 wt%.

  8. 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

  9. 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

  10. Single-walled and multi-walled carbon nanotubes based drug delivery system: Cancer therapy: A review.

    PubMed

    Dineshkumar, B; Krishnakumar, K; Bhatt, A R; Paul, D; Cherian, J; John, A; Suresh, S

    2015-01-01

    Carbon nanotubes (CNTs) are advanced nano-carrier for delivery of drugs especially anti-cancer drugs. In the field of CNT-based drug delivery system, both single-walled carbon nanotubes (SWCNTs) and multi-walled nanotubes (MWCNTs) can be used for targeting anticancer drugs in tissues and organs, where the high therapeutic effect is necessary. Benefits of the carbon nanotubes (CNTs) in drug delivery systems are; avoiding solvent usage and reducing the side effects. Therefore, the present review article described about achievement of SWCNTs and MWCNTs to deliver the anticancer drugs with different cancerous cell lines.

  11. Preparation and Electrocatalytic Activity of Gold Nanoparticles Immobilized on the Surface of 4-Mercaptobenzoyl-Functionalized Multiwalled Carbon Nanotubes

    DTIC Science & Technology

    2010-12-20

    Friedel - Crafts acylation reaction. 24-26 The reaction medium is both mild and nondestructive and plays two important roles for the effective dispersion...the functionalization of multiwalled carbon nano- tubes (MWCNTs) with 4-mercaptobenzoic acid by a “direct” Friedel - Crafts acylation reaction to afford...MWCNTs were prepared using a “direct” Friedel - Crafts acylation reaction in a PPA/P2O5 medium. The reaction between the MWCNTs and MBAc typi- cally

  12. High spatial resolution single multiwalled carbon nanotube electrode for stimulation, recording, and whole cell voltage clamping of electrically active cells

    NASA Astrophysics Data System (ADS)

    de Asis, Edward D.; Leung, Joseph; Wood, Sally; Nguyen, Cattien V.

    2009-10-01

    We report the stimulation, recording, and voltage clamp of muscle fibers using a 30 nm diameter single multiwalled carbon nanotube electrode (sMWNT electrode) tip. Because of the lower access resistance, the sMWNT electrode conducts extracellular and intracellular stimulation more efficiently compared to glass micropipettes. The sMWNT electrode records field potentials and action potentials and performs whole cell voltage clamping of single fibers.

  13. Immobilization of Platinum Nanoparticles on 3,4-diaminobenzoyl-Functionalized Multi-Walled Carbon Nanotube and its Electrocatalytic Activity

    DTIC Science & Technology

    2012-01-01

    Published online: 26 January 2012 Springer Science+Business Media B.V. 2012 Abstract Multi-walled carbon nanotubes (MWCNTs) are functionalized at the...electroless metal deposition process (Li et al. 1998), and assembly of CNT–metal nanoparticle hybrids using biointerfaces ( Kim et al. 2010). Among...Laboratory, Wright-Patterson AFB, Dayton, OH 45433, USA 123 J Nanopart Res ( 2012 ) 14:704 DOI 10.1007/s11051-011-0704-5 Report Documentation Page Form

  14. Extraction of ochratoxin A in red wine with dopamine-coated magnetic multi-walled carbon nanotubes.

    PubMed

    Wan, Hong; Zhang, Bo; Bai, Xiao-Lin; Zhao, Yan; Xiao, Meng-Wei; Liao, Xun

    2017-08-07

    A new, rapid, green, and cost-effective magnetic solid-phase extraction of ochratoxin A from red wine samples was developed using polydopamine-coated magnetic multi-walled carbon nanotubes as the absorbent. The polydopamine-coated magnetic multi-walled carbon nanotubes were fabricated with magnetic multi-walled carbon nanotubes and dopamine by an in situ oxidative self-polymerization approach. Transmission electron microscopy, dynamic light scattering, X-ray photoelectron spectroscopy and vibrating sample magnetometry were used to characterize the absorbents. Ochratoxin A was quantified with high-performance liquid chromatography coupled with fluorescence detection, with excitation and emission wavelengths of 338 and 455 nm, respectively. The conditions affecting the magnetic solid-phase extraction procedure, such as pH, extraction solution, extraction time, absorbent amount, desorption solution and desorption time were investigated to obtain the optimal extraction conditions. Under the optimized conditions, the extraction recovery was 91.8-104.5% for ochratoxin A. A linear calibration curve was obtained in the range of 0.1-2.0 ng/mL. The limit of detection was 0.07 ng/mL, and the limit of quantitation was 0.21 ng/mL. The recoveries of ochratoxin A for spiked red wine sample ranged from 95.65 to 100.65% with relative standard deviation less than 8%. The polydopamine-coated magnetic multi-walled carbon nanotubes showed a high affinity toward ochratoxin A, allowing selective extraction and quantification of ochratoxin A from complex sample matrixes. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Polyvinyl alcohol (PVA)-cellulose nanofibril (CNF)-multiwalled carbon nanotube (MWCNT) hybrid organic aerogels with superior mechanical properties

    Treesearch

    Qifeng Zheng; Alireza Javadi; Ronald Sabo; Zhiyong Cai; Shaoqin Gong

    2013-01-01

    Polyvinyl alcohol (PVA)–cellulose nanofibril (CNF)–multiwalled carbon nanotube (MWCNT) hybrid organic aerogels were prepared using an environmentally friendly freeze-drying process with renewable materials. The material properties of these “green” hybrid aerogels were characterized extensively using various techniques. It was found that adding a small amount of CNFs...

  16. In vivo detection of magnetic labeled oxidized multi-walled carbon nanotubes by magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Li, Ruibin; Wu, Ren'an; Zhao, Liang; Qin, Hongqiang; Wu, Jianlin; Zhang, Jingwen; Bao, Ruyi; Zou, Hanfa

    2014-12-01

    Functionalized carbon nanotubes (f-CNTs) have been widely used in bio-medicine as drug carriers, bio-sensors, imaging agents and tissue engineering additives, which demands better understanding of their in vivo behavior because of the increasing exposure potential to humans. However, there are limited studies to investigate the in vivo biodistribution and elimination of f-CNTs. In this study, superparamagnetic iron oxides (SPIOs) were used to label oxidized multiwalled carbon nanotubes (o-MWCNTs) for in vivo distribution study of o-MWCNTs by magnetic resonance imaging (MRI). SPIO labeled o-MWCNTs ((SPIO)o-MWCNTs) were prepared by a hydrothermal reaction process, and characterized by TEM, XRD and magnetometer. (SPIO)o-MWCNTs exhibited superparamagnetic property, excellent biocompatibility and stability. The intravenously injected (SPIO)o-MWCNTs were observed in liver, kidney and spleen, while the subcutaneously injected (SPIO)o-MWCNTs could be only detected in sub mucosa. Most of the intravenously injected (SPIO)o-MWCNTs could be eliminated from liver, spleen, kidney and sub mucosa on 4 d post injection (P.I.). However, the residual o-MWCNTs could induce 30-40% MRI signal-to-noise ratio changes in these tissues even on 30 d P.I. This in vivo biodistribution and elimination information of o-MWCNTs will greatly facilitate the application of f-CNT based nanoproducts in biomedicine. In addition, the magnetic labeling method provides an approach to investigate the in vivo biodistribution and clearance of other nanomaterials.

  17. A comparison of LLDPE-based nanocomposites containing multi-walled carbon nanotubes and graphene

    NASA Astrophysics Data System (ADS)

    Vasileiou, Alexandros; Docoslis, Aristides; Kontopoulou, Marianna

    2015-05-01

    Composites of linear-low density polyethylene (LLDPE) with multi-walled carbon nanotubes (MWCNT) and thermally reduced graphene (TRGO) were produced by melt compounding. The composites were compatibilized by grafting aromatic pyridine groups onto the LLDPE backbone. The aromatic moieties established non-covalent π-π interactions with the carbon nanostructures, thus allowing for efficient dispersion, without compromizing their electrical properties. By using identical matrices, it was possible to investigate the effects of filler geometry on the electrical, mechanical and rheological properties of the composites. The 1-D nature and smaller surface area of the MWCNT facilitated their dispersion within the polymer matrix, whereas the graphene agglomerates appeared to breakup through an erosion mechanism. The resulting mixture of aggregates and individual graphene platelets favored lower electrical and rheological percolation thresholds. However the maximum electrical conductivity achieved in the TRGO/LLDPE was lower by about an order of magnitude compared to the MWCNT/LLDPE composites, probably due to residual oxygen in the graphene's structure. TRGO based composites presented higher moduli at the same filler loadings, while elongations at break were comparable. All composites exhibited time-dependent rheological properties, indicative of their tendency to aggregate. A more pronounced increase in viscoelastic properties was noted in the composites containing TRGO, presumably due to the higher surface area of the graphene platelets, and the presence of larger aggregates.

  18. Mechanisms for how Inhaled Multiwalled Carbon Nanotubes Suppress Systemic Immune Function in Mice

    PubMed Central

    Mitchell, L. A.; Lauer, F. T.; Burchiel, S. W.; McDonald, J. D.

    2013-01-01

    The potential health effects of inhaling carbon nanotubes are important because of possible exposures in an occupational setting. Previously, we showed that mice inhaling multiwalled carbon nanotubes (MWCNT) showed suppressed systemic immune function. Here we show the mechanisms for this immune suppression. Mice were exposed to 0, 0.3, or 1 mg/m3 MWCNT for 6h/day for 14 consecutive days in whole-body inhalation chambers. Those exposed to 1 mg/m3 showed compromised systemic immune function. Spleen cells from exposed animals increased gene expression of prostaglandin synthase enzymes and were rescued from immunosuppression when treated with ibuprofen. Cyclooxygenase-2 knockout mice were resistant to MWCNT-induced suppression. Proteins isolated from the lungs of exposed mice contained transforming growth factor-beta, which suppressed immune function of wild-type splenocytes but not those from knockout mice in vitro. This suggests that signals from the lung can activate signals in the spleen to suppress the immune function of exposed mice. PMID:19581899

  19. Ligand-modified multi-walled carbon nanotubes for potentiometric detection of silver.

    PubMed

    Yang, Chunli; Chai, Yaqin; Yuan, Ruo; Guo, Junxiang; Jia, Feng

    2012-01-01

    Three novel hybrid materials have been synthesized by ligands: N-(2-vinylsulfanyl-ethylidene)-benzene-1,2-dimine (SBD), N-pyridin-2-ylmethylene-benzene-1,2-dimine (NBD) and N-furan-2-ylmethylene-benzene-1,2-dimine (OBD), covalently linking to multi-walled carbon nanotubes (MWCNTs). These MWCNT hybrid materials were used both as ionophores and as ion-to-electron transducers to construct Ag(+) carbon paste electrodes. The resulting electrodes show higher selectivity to Ag(+) than other cations tested. Among the three electrodes, the electrode based on SBD-g-MWCNTs with optimum composition shows the best performance to Ag(+). It exhibits an excellent Nernstian response to Ag(+) in the concentration range from 8.8 × 10(-8) to 1.0 × 10(-1) M with a detection limit of 6.3 × 10(-8) M, and it can also be used over a wide pH range of 3.0-8.0 with a quick response time of 5 s. The response mechanism of the proposed electrode was also investigated by using AC impedance and UV-vis spectroscopy techniques.

  20. 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

  1. Absorption behavior of poly(methyl methacrylate)-multiwalled carbon nanotube composites: effects of UV irradiation.

    PubMed

    Hsu, Je-Chuan; Cao, Wenxin; Yang, Fuqian; Yang, Tsong-Jen; Lee, Sanboh

    2017-03-08

    Understanding the effects of carbon nanotubes (CNTs) and ultraviolet (UV) irradiation on solvent transport in polymers is of practical importance for the applications of polymer-CNT composites in electronics and photonics. The transport behavior of methanol in poly(methyl methacrylate)-multiwalled carbon nanotube (PMMA-MWCNT) composites with and without UV light irradiation has been studied. The anomalous transport has been investigated as a function of the weight percentage of MWCNTs and UV dose in the temperature range of 30-50 °C. The anomalous transport consists of Case I (controlled by concentration gradient) and Case II (controlled by stress relaxation) transport; both UV irradiation and the addition of MWCNTs in PMMA enhance the transport of methanol. The activation energies for Case I and Case II transport decrease with the increase of UV dose for the PMMA-MWCNT plates with the same weight percentage of MWCNTs. Without UV irradiation, the activation energy for Case I transport of methanol decreases with the increase of the weight percentage of MWCNTs, and the activation energy for Case II transport increases with the increase of the weight percentage of MWCNTs.

  2. 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.

  3. 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.

  4. In vivo detection of magnetic labeled oxidized multi-walled carbon nanotubes by magnetic resonance imaging.

    PubMed

    Li, Ruibin; Wu, Ren'an; Zhao, Liang; Qin, Hongqiang; Wu, Jianlin; Zhang, Jingwen; Bao, Ruyi; Zou, Hanfa

    2014-12-12

    Functionalized carbon nanotubes (f-CNTs) have been widely used in bio-medicine as drug carriers, bio-sensors, imaging agents and tissue engineering additives, which demands better understanding of their in vivo behavior because of the increasing exposure potential to humans. However, there are limited studies to investigate the in vivo biodistribution and elimination of f-CNTs. In this study, superparamagnetic iron oxides (SPIOs) were used to label oxidized multiwalled carbon nanotubes (o-MWCNTs) for in vivo distribution study of o-MWCNTs by magnetic resonance imaging (MRI). SPIO labeled o-MWCNTs (((SPIO))o-MWCNTs) were prepared by a hydrothermal reaction process, and characterized by TEM, XRD and magnetometer. ((SPIO))o-MWCNTs exhibited superparamagnetic property, excellent biocompatibility and stability. The intravenously injected ((SPIO))o-MWCNTs were observed in liver, kidney and spleen, while the subcutaneously injected ((SPIO))o-MWCNTs could be only detected in sub mucosa. Most of the intravenously injected ((SPIO))o-MWCNTs could be eliminated from liver, spleen, kidney and sub mucosa on 4 d post injection (P.I.). However, the residual o-MWCNTs could induce 30-40% MRI signal-to-noise ratio changes in these tissues even on 30 d P.I. This in vivo biodistribution and elimination information of o-MWCNTs will greatly facilitate the application of f-CNT based nanoproducts in biomedicine. In addition, the magnetic labeling method provides an approach to investigate the in vivo biodistribution and clearance of other nanomaterials.

  5. 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. © 2015 SETAC.

  6. 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

  7. Effect of dispersants of multi-walled carbon nanotubes on cellular uptake and biological responses

    PubMed Central

    Haniu, Hisao; Saito, Naoto; Matsuda, Yoshikazu; Kim, Yoong-Ahm; Park, Ki Chul; Tsukahara, Tamotsu; Usui, Yuki; Aoki, Kaoru; Shimizu, Masayuki; Ogihara, Nobuhide; Hara, Kazuo; Takanashi, Seiji; Okamoto, Masanori; Ishigaki, Norio; Nakamura, Koichi; Kato, Hiroyuki

    2011-01-01

    Although there have been many reports about the cytotoxicity of multi-walled carbon nanotubes (MWCNTs), the results are still controversial. To investigate one possible reason, the authors investigated the influence of MWCNT dispersants on cellular uptake and cytotoxicity. Cytotoxicity was examined (measured by alamarBlue® assay), as well as intracellular MWCNT concentration and cytokine secretion (measured by flow cytometry) in human bronchial epithelial cells (BEAS-2B) exposed to a type of highly purified MWCNT vapor grown carbon fiber (VGCF®, Shōwa Denkō Kabushiki-gaisha, Tokyo, Japan) in three different dispersants (gelatin, carboxylmethyl cellulose, and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine). The authors also researched the relationship between the intracellular concentration of MWCNTs and cytotoxicity by using two cell lines, BEAS-2B and MESO-1 human malignant pleural mesothelioma cells. The intracellular concentration of VGCF was different for each of the three dispersants, and the levels of cytotoxicity and inflammatory response were correlated with the intracellular concentration of VGCF. A relationship between the intracellular concentration of VGCF and cytotoxic effects was observed in both cell lines. The results indicate that dispersants affect VGCF uptake into cells and that cytotoxicity depends on the intracellular concentration of VGCF, not on the exposed dosage. Thus, toxicity appears to depend on exposure time, even at low VGCF concentrations, because VGCF is biopersistent. PMID:22228997

  8. 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. Copyright © 2012 Elsevier B.V. All rights reserved.

  9. Design and development of multi-walled carbon nanotube-liposome drug delivery platforms.

    PubMed

    Pippa, Natassa; Chronopoulos, Demetrios D; Stellas, Dimitris; Fernández-Pacheco, Rodrigo; Arenal, Raul; Demetzos, Costas; Tagmatarchis, Nikos

    2017-08-07

    The aim of this study is to design and develop delivery platforms made of liposomes and multi-walled carbon nanotubes (MWCNTs). We used different lipids with different main transition temperature (Tm) and differently functionalized MWCNTs with organic addends possessing either positive or negative charge. The phospholipids used for the formulations were 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) (Tm=41°C) and L-α-phosphatidylcholine, hydrogenated Soy (HSPC) (Tm=53°C). By Differential Scanning Calorimetry (DSC), we studied the interaction between the DPPC and HSPC bilayers and MWCNTs. Liposome-MWCNTs delivery platforms prepared according to the protocol used in the literature. We used dynamic and electrophoretic light scattering in order to investigate the physicochemical characteristics of these mixed nanocarriers. The presence of MWCNTs causes alterations of the size of the conventional HSPC and DPPC liposomes. The ζ-potential values of mixed nanocarriers are near zero. This observation indicates the effective incorporation of MWCNTs into the lipid bilayer of liposomes. Fluorescence spectroscopy has been utilized to exact some qualitative information on the internal nanostructure and nanoenvironment of the lipid/carbon nanotube mixed structures. Finally, we conclude that we successfully prepare and completely characterize mixed nanocarriers composed of lipids and MWCNTs, with low toxicity as indicated by in vitro screening. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. 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.

  11. Tubular micro-scale multiwalled carbon nanotube-based scaffolds for tissue engineering.

    PubMed

    Edwards, Sharon L; Church, Jeffrey S; Werkmeister, Jerome A; Ramshaw, John A M

    2009-03-01

    In this study we have prepared a tubular knitted scaffold from a 9 ply multiwalled carbon nanotube (MWCNT) yarn and a composite scaffold, formed by electrospinning poly(lactic-co-glycolic acid) (PLGA) nanofibres onto the knitted scaffold. Both structures were assessed for in vitro biocompatibility with NR6 mouse fibroblast cells for up to 22 days and their suitability as tissue engineering scaffolds considered. The MWCNT yarn was found to support cell growth throughout the culture period, with fibroblasts attaching to, and proliferating on, the yarn surface. The knitted tubular scaffold contained large pores that inhibited cell spanning, leading to the formation of cell clusters on the yarn, and an uneven cell distribution on the scaffold surface. The smaller pores, created through electrospinning, were found to promote cell spanning, leading to a uniform distribution of cells on the composite scaffold surface. Evaluation of the electrical and mechanical properties of the knitted scaffold determined resistance levels of 0.9 kOmega/cm, with a breaking load and extension to break approaching 0.7N and 8%, respectively. The PLGA/MWCNT composite scaffold presented in this work not only supports cell growth, but also has the potential to utilize the full range of electrical and mechanical properties that carbon nanotubes have to offer.

  12. High-yield Synthesis of Multiwalled Carbon Nanotube by Mechanothermal Method

    NASA Astrophysics Data System (ADS)

    Manafi, S. A.; Amin, M. H.; Rahimipour, M. R.; Salahi, E.; Kazemzadeh, A.

    2009-04-01

    This study reports on the mechanothermal synthesis of multiwalled carbon nanotube (MWCNTs) from elemental graphite powder. Initially, high ultra-active graphite powder can be obtained by mechanical milling under argon atmosphere. Finally, the mechanical activation product is heat-treated at 1350°C for 2-4 h under argon gas flow. After heat-treatment, active graphite powders were successfully changed into MWCNTs with high purity. The XRD analyses showed that in the duration 150 h of milling, all the raw materials were changed to the desired materials. From the broadening of the diffraction lines in the XRD patterns, it was concluded that the graphite crystallites were nanosized, and raising the milling duration resulted in the fineness of the particles and the increase of the strain. The structure and morphology of MWCNTs were investigated using scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). The yield of MWCNTs was estimated through SEM and TEM observations of the as-prepared samples was to be about 90%. Indeed, mechanothermal method is of interest for fundamental understanding and improvement of commercial synthesis of carbon nanotubes (CNTs). As a matter of fact, the method of mechanothermal guarantees the production of MWCNTs suitable for different applications.

  13. High-yield Synthesis of Multiwalled Carbon Nanotube by Mechanothermal Method.

    PubMed

    Manafi, S A; Amin, M H; Rahimipour, M R; Salahi, E; Kazemzadeh, A

    2009-01-22

    This study reports on the mechanothermal synthesis of multiwalled carbon nanotube (MWCNTs) from elemental graphite powder. Initially, high ultra-active graphite powder can be obtained by mechanical milling under argon atmosphere. Finally, the mechanical activation product is heat-treated at 1350 degrees C for 2-4 h under argon gas flow. After heat-treatment, active graphite powders were successfully changed into MWCNTs with high purity. The XRD analyses showed that in the duration 150 h of milling, all the raw materials were changed to the desired materials. From the broadening of the diffraction lines in the XRD patterns, it was concluded that the graphite crystallites were nanosized, and raising the milling duration resulted in the fineness of the particles and the increase of the strain. The structure and morphology of MWCNTs were investigated using scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). The yield of MWCNTs was estimated through SEM and TEM observations of the as-prepared samples was to be about 90%. Indeed, mechanothermal method is of interest for fundamental understanding and improvement of commercial synthesis of carbon nanotubes (CNTs). As a matter of fact, the method of mechanothermal guarantees the production of MWCNTs suitable for different applications.

  14. Enhanced mechanical properties of polyacrylonitrile/multiwall carbon nanotube composite fibers.

    PubMed

    Weisenberger, M C; Grulke, E A; Jacques, D; Rantell, T; Andrews, R

    2003-12-01

    The use of multiwall carbon nanotubes (MWNTs) as a reinforcing phase in a polyacrylonitrile (PAN) fiber matrix was investigated with the goal of producing a PAN-derived carbon/MWNT composite fiber with enhanced physical properties. MWNTs were dispersed in a PAN/DMAc (dimethylacetamide) solution and spun into composite fibers containing up to 5 wt.% MWNTs, with the use of a lab-scale dry-jet wet spinline. The spinning process resulted in alignment of the MWNTs parallel with the fiber axis. Three types of chemical vapor deposition (CVD)-derived, high-purity MWNTs were used: as produced, graphitized (heat treated to 2800 degrees C), and NaCN-treated (chemically treated to attach CN groups to the nanotube surface). Tensile tests were performed to measure yield stress/strain, initial modulus, break stress/strain, and energy to yield and energy to break. Significant mechanical property increases were recorded for the composite fibers compared with the control samples with no MWNT reinforcement: break strength +31%, initial modulus +36%, yield strength +46%, energy to yield +80%, and energy to break +83%.

  15. 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.

  16. Structural, electronic and photovoltaic characterization of multiwalled carbon nanotubes grown directly on stainless steel

    PubMed Central

    Scarselli, Manuela; Gobbo, Silvano Del; Castrucci, Paola; Gautron, Eric; De Crescenzi, Maurizio

    2012-01-01

    Summary 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

  17. Drug-loading capacity and nuclear targeting of multiwalled carbon nanotubes grafted with anionic amphiphilic copolymers

    PubMed Central

    Tsai, Hsieh-Chih; Lin, Jeng-Yee; Maryani, Faiza; Huang, Chun-Chiang; Imae, Toyoko

    2013-01-01

    In this study, three types of hybrid nanotubes (NTs), ie, oxidized multiwalled carbon NTs (COOH MWCNTs), heparin (Hep)-conjugated MWCNTs (Hep MWCNTs), and diblock copolymer polyglycolic acid (PGA)-co-heparin conjugated to MWCNTs (PGA MWCNTs), were synthesized with improved biocompatibility and drug-loading capacity. Hydrophilic Hep substituents on MWCNTs improved biocompatibility and acted as nucleus-sensitive segments on the CNT carrier, whereas the addition of PGA enhanced drug-loading capacity. In the PGA MWCNT system, the amphiphilic copolymer (PGA-Hep) formed micelles on the side walls of CNTs, as confirmed by electron microscopy. The PGA system encapsulated the hydrophobic drug with high efficiency compared to the COOH MWCNT and Hep MWCNT systems. This is because the drug was loaded onto the PGA MWCNTs through hydrophobic forces and onto the CNTs by π–π stacking interactions. Additionally, most of the current drug-carrier designs that target cancer cells release the drug in the lysosome or cytoplasm. However, nuclear-targeted drug release is expected to kill cancer cells more directly and efficiently. In our study, PGA MWCNT carriers effectively delivered the active anticancer drug doxorubicin into targeted nuclei. This study may provide an effective strategy for the development of carbon-based drug carriers for nuclear-targeted drug delivery. PMID:24277987

  18. Surfactant dispersed multi-walled carbon nanotube/polyetherimide nanocomposite membrane

    NASA Astrophysics Data System (ADS)

    Goh, P. S.; Ng, B. C.; Ismail, A. F.; Aziz, M.; Sanip, S. M.

    2010-12-01

    Carbon nanotube based nanocomposite membranes have been fabricated through solution casting by embedding multi-walled carbon nanotubes (MWCNTs) within polyetherimide (PEI) polymer host matrix. In order to achieve fine dispersion of nanotubes and facilitate strong interfacial adhesion with the polymer matrix, the nanotubes were first treated with surfactants of different charges, namely anionic sodium dodecyl chloride, cationic cetyl trimethyl ammonium chloride and non-ionic Triton X100, prior to the dispersion in the PEI dope solution. Dispersion of MWCNTs in N-methyl-2-pyrrolidone solvent showed that the agglomeration and entanglement of the nanotubes were greatly reduced upon the addition of Triton X100. Scanning electron microscopy and atomic force microscopy examination has evidenced the compatibility of Triton X100 dispersed MWCNTs with the polymer matrix in which a promising dispersion and adhesion has been observed at the MWCNT-PEI interface. The increase in both thermal stability and mechanical strength of the resulting Triton X100 dispersed MWCNT/PEI nanocomposite indicated the improved interaction between MWCNTs and PEI. This study demonstrated the role of Triton X100 in facilitating the synergetic effects of MWCNTs and PEI where the resulting composite membrane is anticipated to have potential application in membrane based gas separation.

  19. 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.

  20. On the possibility of electrochemical unzipping of multiwalled carbon nanotubes to produce graphene nanoribbons

    SciTech Connect

    Zehtab Yazdi, Alireza; Roberts, Edward P.L.; Sundararaj, Uttandaraman

    2016-08-15

    Highlights: • MWCNTs synthesized and electrochemically oxidized to study the formation of GNR • HRTEM, Raman and XPS confirmed no successful unzipping occurred after oxidation • Electrochemical oxidation very unlikely facilitate formation of intercalated MWCNTs - Abstract: Multiwalled carbon nanotubes (MWCNTs) with different geometrical characteristics and chemical doping have been synthesized and electrochemically oxidized to study the possibility of unzipping, and creating graphene nanoribbon (GNR) nanostructures. Modified glassy carbon electrodes of the MWCNTs have been tested in an aqueous electrolyte via anodic scans in a wide range of potentials, followed by keeping at the maximum potential for different times. The microstructural features, structural defects, and functional groups and their elements have been then studied using high resolution transmission electron microscopy (HRTEM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS), respectively. All results have confirmed that no successful unzipping occurs in the MWCNTs after electrochemical oxidation, even for the nitrogen-doped MWCNTs (CN{sub x}-MWCNTs) with reactive nitrogen groups and defective bamboo structures. In contrast to the report by Shinde et al. (J. Am. Chem. Soc. 2011, 133, 4168–4171), it has been concluded that the electrochemical oxidation in aqueous electrolytes is very unlikely to facilitate sufficient incorporation of the intercalated molecules among the walls of the MWCNTs. These molecules are, however, responsible for unzipping of MWCNTs.

  1. Sensitive immunoassay of human chorionic gonadotrophin based on multi-walled carbon nanotube-chitosan matrix.

    PubMed

    Li, Na; Yuan, Ruo; Chai, Yaqin; Chen, Shihong; An, Haizhen

    2008-10-01

    A novel amperometric immunosensor for human chorionic gonadotropin (HCG) assay has been fabricated through incorporating toluidine blue (TB) and hemoglobin (Hb) on the multiwall carbon nanotube (MWNT)-chitosan (CS) modified glassy carbon electrode, followed by electrostatic adsorption of a conducting gold nanoparticles (nanogold) film as sensing interface. The MWNT-CS matrix provided a congenial microenvironment for the immobilization of biomolecules and promoted the electron transfer to enhance the sensitivity of the immunosensor. Due to the strong electrocatalytic properties of Hb and MWNT toward H(2)O(2), the Hb and MWNT significantly amplified the current signal of the antigen-antibody reaction. The immobilized toluidine blue as an electron transfer mediator exhibited excellent electrochemical redox property. After the immunosensor was incubated with HCG solution, the access of activity center of the Hb to toluidine blue was partly inhibited, which leaded to a linear decrease in the catalytic efficiency of the Hb to the oxidation of immobilized toluidine blue by H(2)O(2) over HCG concentration ranges from 0.8 to 500 mIU/mL. Under optimal condition, the detection limit for the HCG immunoassay was 0.3 mIU/mL estimated at a signal-to-noise ratio of 3. Moreover, the proposed immunosensor displayed a satisfactory stability and reproducibility.

  2. On the synthesis and magnetic properties of multiwall carbon nanotube-superparamagnetic iron oxide nanoparticle nanocomposites.

    PubMed

    Narayanan, T N; Mary, A P Reena; Shaijumon, M M; Ci, Lijie; Ajayan, P M; Anantharaman, M R

    2009-02-04

    Multiwall carbon nanotubes (MWCNTs) possessing an average inner diameter of 150 nm were synthesized by template assisted chemical vapor deposition over an alumina template. Aqueous ferrofluid based on superparamagnetic iron oxide nanoparticles (SPIONs) was prepared by a controlled co-precipitation technique, and this ferrofluid was used to fill the MWCNTs by nanocapillarity. The filling of nanotubes with iron oxide nanoparticles was confirmed by electron microscopy. Selected area electron diffraction indicated the presence of iron oxide and graphitic carbon from MWCNTs. The magnetic phase transition during cooling of the MWCNT-SPION composite was investigated by low temperature magnetization studies and zero field cooled (ZFC) and field cooled experiments. The ZFC curve exhibited a blocking at approximately 110 K. A peculiar ferromagnetic ordering exhibited by the MWCNT-SPION composite above room temperature is because of the ferromagnetic interaction emanating from the clustering of superparamagnetic particles in the constrained volume of an MWCNT. This kind of MWCNT-SPION composite can be envisaged as a good agent for various biomedical applications.

  3. Effects of Functionalized and Raw Multi-Walled Carbon Nanotubes on Soil Bacterial Community Composition

    PubMed Central

    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

  4. 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.

  5. Aqueous adsorption of aniline, phenol, and their substitutes by multi-walled carbon nanotubes.

    PubMed

    Yang, Kun; Wu, Wenhao; Jing, Qingfeng; Zhu, Lizhong

    2008-11-01

    Aqueous adsorption of a series of phenols and anilines by a multiwalled carbon nanotube material (MWCNT15), which depends strongly on the solution pH and the number and types of solute groups, was investigated in this study. The pH-dependent adsorption coefficients, Kd, could be predicted by the established models including solute pKa and solution pH values. Phenol or aniline substitution with more groups has higher adsorption affinity, and nitro, chloride, or methyl groups enhanced adsorption in the following order: nitro group > chloride group > methyl group. All adsorption isotherms of nondissociated phenols and anilines are nonlinear and fitted well bythe Polanyi-theory based Dubinin-Ashtakhov (DA) model. Linear quantitative relationships combining DA model parameters (E and b) with solute solvatochromic parameters were developed to evaluate the adsorptive behaviors of nondissociated species. For the saturated sorbed capacity, Q0, the logarithmic values of phenols and anilines were relatively constant with a mean value of 1.90. Besides the van der Waals force, H-bonding interactions from solutes as hydrogen-bonding donors, and followed by pi-electron polarizability, may play important roles on the adsorption of phenols and anilines by carbon nanotubes in the aqueous environment

  6. Third Sound Measurements of Superfluid 4He Films on Multiwall Carbon Nanotubes Below 1 K

    NASA Astrophysics Data System (ADS)

    Menachekanian, Emin; Iaia, Vito; Li, Andrew; Chen, Bob; Williams, Gary

    2014-03-01

    Third sound is studied for superfluid films of 4He adsorbed on multiwall carbon nanotubes of average diameter 12 Angstroms packed into an annular resonator. The third sound is generated with mechanical oscillation of the cell, and detected with carbon bolometers. A filling curve at temperatures near 250 mK shows oscillations in the third sound velocity, with maxima at the completion of the third and fourth atomic layers. The ``dead'' layer appears to be close to two atomic layers, about one layer thinner than previously found for flat graphite surfaces. We attribute this weaker binding to the effect of the cylindrical geometry on the van der Waals potential, the repulsive surface tension forces from the high curvature, and the lower density of the tubes compared to graphite. At the completion of the third layer there is a sudden reduction of the superfluid onset temperature, and then a recovery back to the Kosterlitz-Thouless linear dependence, forming re-entrant superfluidity. In a small region around 2.5 layers there is very anomalous behavior in the low-temperature variation of the third sound velocity, which is found to increase linearly with temperature. This could be related to changes in the gas-liquid coexistence at this intermediate fill. Work supported in part by the Nation Science Foundation, Grant DMR 0906467.

  7. Photopolymerization of Diacetylene on Aligned Multiwall Carbon Nanotube Microfibers for High-Performance Energy Devices.

    PubMed

    Ulaganathan, Mani; Hansen, Reinack Varghese; Drayton, Nateisha; Hingorani, Hardik; Kutty, R Govindan; Joshi, Hrishikesh; Sreejith, Sivaramapanicker; Liu, Zheng; Yang, Jinglei; Zhao, Yanli

    2016-12-07

    Linear two-dimensional materials have recently attracted an intense interest for supercapacitors because of their potential uses as electrodes in next-generation wearable electronics. However, enhancing the electrochemical properties of these materials without complicated structural modifications remains a challenge. Herein, we present the preparation of a hybrid electrode system via polydiacetylene (PDA) cloaking on the surface of aligned multiwall carbon nanotubes (MWCNTs) through self-assembly based in situ photopolymerization. This strategy eliminates the need for initiators and binders that hinder electrochemical performance in conventional conducting polymer based composite electrodes. As noncovalent PDA cloaking did not alter the chemical structure of MWCNTs, high inherent conductivity from sp(2) hybridized carbon was preserved. The resulting hybrid microfiber (MWCNT@PDA) exhibited a significant increase in specific capacitance (1111 F g(-1)) when compared to bare MWCNTs (500 F g(-1)) and PDA (666.7 F g(-1)) in a voltage window of 0-1.2 V at a current density of 3 A g(-1) in 0.5 M K2SO4 electrolyte. The specific capacitance was retained (ca. 95%) after 7000 charge/discharge cycles. The present results suggest that aligned MWCNTs cloaked with conjugated polymers could meet the demands for future flexible electronics.

  8. Selective ex-vivo photothermal ablation of human pancreatic cancer with albumin functionalized multiwalled carbon nanotubes

    PubMed Central

    Mocan, Lucian; Tabaran, Flaviu A; Mocan, Teodora; Bele, Constantin; Orza, Anamaria Ioana; Lucan, Ciprian; Stiufiuc, Rares; Manaila, Ioana; Iulia, Ferencz; Dana, Iancu; Zaharie, Florin; Osian, Gelu; Vlad, Liviu; Iancu, Cornel

    2011-01-01

    The process of laser-mediated ablation of cancer cells marked with biofunctionalized carbon nanotubes is frequently called “nanophotothermolysis”. We herein present a method of selective nanophotothermolisys of pancreatic cancer (PC) using multiwalled carbon nanotubes (MWCNTs) functionalized with human serum albumin (HSA). With the purpose of testing the therapeutic value of these nanobioconjugates, we have developed an ex-vivo experimental platform. Surgically resected specimens from patients with PC were preserved in a cold medium and kept alive via intra-arterial perfusion. Additionally, the HSA-MWCNTs have been intra-arterially administered in the greater pancreatic artery under ultrasound guidance. Confocal and transmission electron microscopy combined with immunohistochemical staining have confirmed the selective accumulation of HSA-MWCNTs inside the human PC tissue. The external laser irradiation of the specimen has significantly produced extensive necrosis of the malign tissue after the intra-arterial administration of HSA-MWCNTs, without any harmful effects on the surrounding healthy parenchyma. We have obtained a selective photothermal ablation of the malign tissue based on the selective internalization of MWCNTs with HSA cargo inside the pancreatic adenocarcinoma after the ex-vivo intra-arterial perfusion. PMID:21720504

  9. Multiwalled carbon nanotubes enter broccoli cells enhancing growth and water uptake of plants exposed to salinity.

    PubMed

    Martínez-Ballesta, M Carmen; Zapata, Lavinia; Chalbi, Najla; Carvajal, Micaela

    2016-06-08

    Carbon nanotubes have been shown to improve the germination and growth of some plant species, extending the applicability of the emerging nano-biotechnology field to crop science. In this work, exploitation of commercial multiwalled carbon nanotubes (MWCNTs) in control and 100 mM NaCl-treated broccoli was performed. Transmission electron microscopy demonstrated that MWCNTs can enter the cells in adult plants with higher accumulation under salt stress. Positive effect of MWCNTs on growth in NaCl-treated plants was consequence of increased water uptake, promoted by more-favourable energetic forces driving this process, and enhanced net assimilation of CO2. MWCNTs induced changes in the lipid composition, rigidity and permeability of the root plasma membranes relative to salt-stressed plants. Also, enhanced aquaporin transduction occurred, which improved water uptake and transport, alleviating the negative effects of salt stress. Our work provides new evidences about the effect of MWCNTs on plasma membrane properties of the plant cell. The positive response to MWCNTs in broccoli plants opens novel perspectives for their technological uses in new agricultural practices, especially when 1plants are exposed to saline environments.

  10. 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.

  11. 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). Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Adverse effects of industrial multiwalled carbon nanotubes on human pulmonary cells

    PubMed Central

    Tabet, Lyes; Bussy, Cyrill; Amara, Nadia; Setyan, Ari; Grodet, Alain; Rossi, Michel J.; Pairon, Jean-Claude; Boczkowski, Jorge; Lanone, Sophie

    2009-01-01

    The aim of this study was to evaluate adverse effects of multi-walled carbon nanotubes (MWCNT) produced for industrial purposes, on the human epithelial cell line A549. MWCNT were dispersed in dipalmitoyl lecithin (DPL), a component of pulmonary surfactant, and the effects of dispersion in DPL were compared to those in 2 other media: ethanol (EtOH) and phosphate buffer saline (PBS). Effects of MWCNT were also compared to those of 2 asbestos fibers (chrysotile and crocidolite) and carbon black (CB) nanoparticles, not only in A549 cells, but also on mesothelial cells (MeT5A human cell line), used as an asbestos-sensitive cell type. MWCNT formed agglomerates on top of both cell lines (surface area 15–35 μm2), that were significantly larger and more numerous in PBS than in EtOH and DPL. Whatever the dispersion media, incubation with 100 μg/ml MWCNT induced a similar decrease in metabolic activity without changing cell membrane permeability or apoptosis. Neither MWCNT cellular internalization nor oxidative stress were observed. In contrast, asbestos fibers penetrated into the cells, decreased metabolic activity but not cell membrane permeability and increased apoptosis, without decreasing cell number. CB was internalized without any adverse effects. In conclusion, this study demonstrates that MWCNT produced for industrial purposes exert adverse effects without being internalized by human epithelial and mesothelial pulmonary cell lines. PMID:19034795

  13. 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.

  14. 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.

  15. Laser-induced selective metallization of polypropylene doped with multiwall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Ratautas, Karolis; Gedvilas, Mindaugas; Stankevičiene, Ina; Jagminienė, Aldona; Norkus, Eugenijus; Pira, Nello Li; Sinopoli, Stefano; Račiukaitis, Gediminas

    2017-08-01

    Moulded interconnect devices (MID) offer the material, weight and cost saving by integration electronic circuits directly into polymeric components used in automotive and other consumer products. Lasers are used to write circuits directly by modifying the surface of polymers followed by an electroless metal plating. A new composite material - the polypropylene doped with multiwall carbon nanotubes was developed for the laser-induced selective metallization. Mechanism of surface activation by laser irradiation was investigated in details utilising pico- and nanoseconds lasers. Deposition of copper was performed in the autocatalytic electroless plating bath. The laser-activated polymer surfaces have been studied using the Raman spectroscopy and scanning electron microscope (SEM). Microscopic images revealed that surface becomes active only after its melting by a laser. Alterations in the Raman spectra of the D and G bands indicated the clustering of carbon additives in the composite material. Optimal laser parameters for the surface activation were found by measuring a sheet resistance of the finally metal-plated samples. A spatially selective copper plating was achieved with the smallest conductor line width of 22 μm at the laser scanning speed of 3 m/s and the pulse repetition rate of 100 kHz. Finally, the technique was validated by making functional electronic circuits by this MID approach.

  16. Plasma-modified graphene nanoplatelets and multiwalled carbon nanotubes as fillers for advanced rubber composites

    NASA Astrophysics Data System (ADS)

    Sicinski, M.; Gozdek, T.; Bielinski, D. M.; Szymanowski, H.; Kleczewska, J.; Piatkowska, A.

    2015-07-01

    In modern rubber industry, there still is a room for new fillers, which can improve the mechanical properties of the composites, or introduce a new function to the material. Modern fillers like carbon nanotubes or graphene nanoplatelets (GnP), are increasingly applied in advanced polymer composites technology. However, it might be hard to obtain a well dispersed system for such systems. The polymer matrix often exhibits higher surface free energy (SFE) level with the filler, which can cause problems with polymer-filler interphase adhesion. Filler particles are not wet properly by the polymer, and thus are easier to agglomerate. As a consequence, improvement in the mechanical properties is lower than expected. In this work, multi-walled carbon nanotubes (MWCNT) and GnP surface were modified with low-temperature plasma. Attempts were made to graft some functionalizing species on plasma-activated filler surface. The analysis of virgin and modified fillers’ SFE was carried out. MWCNT and GnP rubber composites were produced, and ultimately, their morphology and mechanical properties were studied.

  17. 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.

  18. Application of multiwall carbon nanotubes for thermal dissipation in a micro-processor

    NASA Astrophysics Data System (ADS)

    Thang, Bui Hung; Hong, Phan Ngoc; Khoi, Phan Hong; Minh, Phan Ngoc

    2009-09-01

    One of the most valuable properties of the carbon nanotubes materials is its high thermal conductivity with 2000 W/m.K (compared to thermal conductivity of Ag 419 W/m.K). It suggested an approach in applying the CNTs in thermal dissipation media to improve the performance of computer processors and other high power electronic devices. In this research, the multiwall carbon nanotubes (MWCNTs) made by thermal chemical vapour deposition (CVD) at our laboratory was employed as the heat dissipation media in a microprocessor a Personal Computer with configuration: Intel Pentium IV 3.066 GHz, 512Mb of RAM and Windows XP Service Pack 2 Operating System. We directly measured the temperature of the microprocessor during the operation of the computer in two modes: 100% usage CPU mode and over-clocking mode. The measured results showed that when using our thermal dissipation media (a mixture of the mentioned commercial thermal compound and 2 wt.%. MWCNTs), the temperature of the microprocessor decreased 5°C, and the time for increasing the temperature of the microprocessor was three times longer than that when using commercial thermal compound. In over-clocking mode, the processor speed reached 3.8 GHz with 165 MHz of system bus clock speed; it was 1.24 times higher than that in non over-clocking mode. The results confirmed a promising way of using MWCNTs as the thermal dissipation media for microprocessor and high power electronic devices.

  19. 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.

  20. Cytotoxicity evaluation of unfunctionalized multiwall carbon nanotubes-ultrahigh molecular weight polyethylene nanocomposites.

    PubMed

    Mamidi, Narsimha; Leija, Héctor Manuel; Diabb, Jose Manuel; Lopez Romo, Irasema; Hernandez, Diana; Castrejón, Javier Villela; Martinez Romero, Oscar; Barrera, Enrique V; Elias Zúñiga, Alex

    2017-11-01

    The carbon nanotubes were chosen for this study since long, small to medium diameter, and unfunctionalized nanotubes are considered less favorable for nontoxic applications. The intent of the study is to expand the use of CNTs beyond current understood nontoxic means. Multiwall carbon nanotube/ultrahigh molecular weight polyethylene (MWCNT/UHMWPE) nanocomposites were prepared by reinforcing long chain UHMWPE with MWCNTs. These nanocomposites were prepared to study their cytotoxicity assessments with human fibroblast cell lines. Cell adhesion, proliferation, and differentiation were studied with human fibroblast cell lines. In vitro studies revealed good cell viability on the surface of MWCNT/UHMWPE composites even after 72 h. The nanocomposites showed better cell attachment for fibroblasts than pristine UHMWPE. Overall, the results showed that MWCNT/UHMWPE composites displayed good cellular growth and biocompatibility indicating another way CNTs can be nontoxic. These nanocomposites offer nontoxic conditions that can be used in biomedical devices because the long chain UHMWPE is entangled with long MWCNTs. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 3042-3049, 2017. © 2017 Wiley Periodicals, Inc.

  1. Microbial Transformation of Multiwalled Carbon Nanotubes by Mycobacterium vanbaalenii PYR-1.

    PubMed

    You, Yaqi; Das, Kamol K; Guo, Huiyuan; Chang, Che-Wei; Navas-Moreno, Maria; Chan, James W; Verburg, Paul; Poulson, Simon R; Wang, Xilong; Xing, Baoshan; Yang, Yu

    2017-02-21

    Carbonaceous nanomaterials are widely used in industry and consumer products, but concerns have been raised regarding their release into the environment and subsequent impacts on ecosystems and human health. Although many efforts have been devoted to understanding the environmental fate of carbonaceous nanomaterials, information about their microbial transformation is still rare. In this study, we found that within 1 month a polycyclic aromatic hydrocarbon-degrading bacterium, Mycobacterium vanbaalenii PYR-1, was able to degrade both pristine and carboxyl-functionalized multiwalled carbon nanotubes (p-MWCNT and c-MWCNT), as demonstrated by consistent results from high resolution transmission electron microscopy, Raman spectroscopy, and confocal Raman microspectroscopy. Statistical analysis of Raman spectra identified a significant increase in the density of disordered or amorphous carbon in p-MWCNT and c-MWCNT after biodegradation. Microbial respiration further suggested potential mineralization of MWCNTs within about 1 month. All of our analyses consistently showed higher degradation or mineralization of c-MWCNT compared to p-MWCNT. These results highlight the potential of using bacteria in engineered systems to remove residual carbonaceous nanomaterials and reduce risk of human exposure and environmental impact. Meanwhile, our finding suggests possible transformation of carbonaceous nanomaterials by polycyclic aromatic hydrocarbon-degrading bacteria in the natural environment, which should be accounted for in predicting the environmental fate of these emerging contaminants and in nanotechnology risk regulation.

  2. Surface modification of multiwall carbon nanotubes determines the pro-inflammatory outcome in macrophage.

    PubMed

    Zhang, Ting; Tang, Meng; Kong, Lu; Li, Han; Zhang, Tao; Xue, Yuying; Pu, Yuepu

    2015-03-02

    Carbon nanotubes (CNTs) are widely used in industry and biomedicine. While several studies have focused on biological matters, attempts to systematically elucidate the toxicity mechanisms of CNTs are limited. The aim of the present study was to evaluate and compare the cytotoxicity of raw multi-walled carbon nanotubes (MWCNTs) and MWCNTs functionalized with carboxylation (MWCNTs-COOH) or polyethylene glycol (MWCNTs-PEG) in murine macrophages. Our results show that only MWCNTs-COOH and raw MWCNTs alter the oxidative potential of macrophages by increasing reactive oxygen species and the expression of pro-inflammatory factors in both a concentration- and surface coating-dependent manner. The data suggest that compare with raw MWCNTs and MWCNTs-PEG, the MWCNTs-COOH produces a significant increase in ROS generation, interruption of ATP synthesis, and activation of the MAPK and NF-κB signaling pathways, which in turn upregulates IL-1β, IL-6, TNF-α, and iNOS to trigger cell death. These findings suggest that contributory cellar uptake caused by physicochemical factors rather than residual metal catalysts plays a role in ROS-mediated pro-inflammatory responses in vitro.

  3. In situ scanning electron microscope peeling to quantify surface energy between multiwalled carbon nanotubes and graphene.

    PubMed

    Roenbeck, Michael R; Wei, Xiaoding; Beese, Allison M; Naraghi, Mohammad; Furmanchuk, Al'ona; Paci, Jeffrey T; Schatz, George C; Espinosa, Horacio D

    2014-01-28

    Understanding atomic interactions between constituents is critical to the design of high-performance nanocomposites. Here, we report an experimental-computational approach to investigate the adhesion energy between as-produced arc discharge multiwalled carbon nanotubes (MWCNTs) and graphene. An in situ scanning electron microscope (SEM) experiment is used to peel MWCNTs from graphene grown on copper foils. The force during peeling is obtained by monitoring the deflection of a cantilever. Finite element and molecular mechanics simulations are performed to assist the data analysis and interpretation of the results. A finite element analysis of the experimental configuration is employed to confirm the applicability of Kendall's peeling model to obtain the adhesion energy. Molecular mechanics simulations are used to estimate the effective contact width at the MWCNT-graphene interface. The measured surface energy is γ = 0.20 ± 0.09 J·m(-2) or γ = 0.36 ± 0.16 J·m(-2), depending on the assumed conformation of the tube cross section during peeling. The scatter in the data is believed to result from an amorphous carbon coating on the MWCNTs, observed using transmission electron microscopy (TEM), and the surface roughness of graphene as characterized by atomic force microscopy (AFM).

  4. 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.

  5. Heat transfer nanofluid based on curly ultra-long multi-wall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Boncel, Sławomir; Zniszczoł, Aurelia; Pawlyta, Mirosława; Labisz, Krzysztof; Dzido, Grzegorz

    2017-08-01

    The main challenge in the use of multi-wall carbon nanotube (MWCNT) as key components of nanofluids is to transfer excellent thermal properties from individual nanotubes into the bulk systems. We present studies on the performance of heat transfer nanofluids based on ultra-long ( 2 mm), curly MWCNTs - in the background of various other nanoC-sp2, i.e. oxidized MWCNTs, commercially available Nanocyl™ MWCNTs and spherical carbon nanoparticles (SCNs). The nanofluids prepared via ultrasonication from water and propylene glycol were studied in terms of heat conductivity and heat transfer in a scaled up thermal circuit containing a copper helical heat exchanger. Ultra-long curly MWCNT (1 wt.%) nanofluids (stabilized with Gum Arabic in water) emerged as the most thermally conducting ones with a 23-30%- and 39%-enhancement as compared to the base-fluids for water and propylene glycol, respectively. For turbulent flows (Re = 8000-11,000), the increase of heat transfer coefficient for the over-months stable 1 wt.% ultra-long MWCNT nanofluid was found as high as >100%. The findings allow to confirm that longer MWCNTs are promising solid components in nanofluids and hence to predict their broader application in heat transfer media.

  6. Optical signature of structural defects in single walled and multiwalled carbon nanotubes.

    PubMed

    Singh, Dilip K; Iyer, P K; Giri, P K

    2009-09-01

    Though defects are invariably present in as-grown and purified carbon nanotubes (NTs), spectroscopic properties of defects in NTs have not been established yet. In this work, single walled (SW) and multiwalled (MW) carbon nanotubes (NTs) grown by chemical vapor deposition have been studied by high resolution transmission electron microscopy (HRTEM), Raman scattering and photoluminescence (PL), electron spin resonance (ESR) and thermo gravometric (TGA) analysis. Raman spectra of both SWNT and MWNT show additional features in the frequency range intermediate between 600-1300 cm(-1) and 1700-2600 cm(-1), in addition to well-known radial breathing modes, D- and G-bands. Room temperature PL studies show two broad but distinct peaks centered at approximately 2.05 eV and approximately 2.33 eV, for both SWNT and MWNT samples. TGA analysis shows very low impurity content in MWNT sample as compared to the SWNT sample. HRTEM analysis reveals various kinds of structural defects in nanotube wall. With the help of HRTEM and ESR studies, we argue that the intermediate frequency Raman modes and the visible PL from the pristine NTs are definite signatures of structural defects in the nanotubes.

  7. 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)),

  8. Multiwalled carbon nanotube monoliths prepared by spark plasma sintering (SPS) and their mechanical properties.

    PubMed

    Uo, Motohiro; Hasegawa, Tomoka; Akasaka, Tsukasa; Tanaka, Isao; Munekane, Fuminori; Omori, Mamoru; Kimura, Hisamichi; Nakatomi, Reiko; Soga, Kohei; Kogo, Yasuo; Watari, Fumio

    2009-01-01

    Three types of multiwalled carbon nanotube (MWCNT) monoliths without any binders were obtained by spark plasma sintering (SPS) treatment at 2000 degrees C under 80 MPa sintering pressure. Three MWCNTs with different diameters: thin (slashed circle20-30 nm, CNT Co., Ltd., Korea), thick (slashed circle100 nm, Nano Carbon Technologies Co., Ltd., Japan) and spherical thin (slashed circle20-30 nm, granulated diameter = 1-3 microm, Shimizu Corporation, Japan) were employed for SPS. SEM observation confirmed that these materials maintained the nanosized tube microstructure of raw CNT powder after SPS treatment. The densest monolith was prepared with the spherical MWCNTs. The mechanical properties of this material were estimated by the dynamic hardness test. The elastic modulus of the monolith did not depend on the difference of MWCNTs, but the hardness of spherical MWCNTs was higher than that of thick MWCNTs. The high density and hardness of the spherical MWCNTs were caused by the high packing density during the SPS process because of its spherical granulation. Thus, the spherical MWCNTs were most useful for the MWCNT monolith preparation with the SPS process and its application as a bone substitute material and a bone tissue engineering scaffold material was suggested.

  9. Vitamin B(12) incorporated with multiwalled carbon nanotube composite film for the determination of hydrazine.

    PubMed

    Umasankar, Yogeswaran; Huang, Tzu-Yen; Chen, Shen-Ming

    2011-01-15

    Electrochemically active composite film containing multiwalled carbon nanotubes (MWCNTs) and vitamin B(12) was synthesized on glassy carbon, gold, and indium tin oxide electrodes by the potentiodynamic method. The presence of MWCNTs in the composite film (MWCNT-B(12)) modified electrode mediates vitamin B(12)'s redox reaction, whereas vitamin B(12)'s redox reaction does not occur at bare electrode. The electrochemical impedance spectroscopy studies reveal that MWCNTs present in MWCNT-B(12) film enhance electron shuttling between the reactant and electrode surface. The surface morphology of bare electrode, MWCNT film. and MWCNT-B(12) composite film was studied using atomic force microscopy, which reveals vitamin B(12) incorporated with MWCNTs. The MWCNT-B(12) composite film exhibits promising enhanced electrocatalysis toward hydrazine. The electrocatalysis response of hydrazine at MWCNT film and MWCNT-B(12) composite film was measured using cyclic voltammetry and amperometric current-time (i-t) curve techniques. The linear concentration range of hydrazine obtained at MWCNT-B(12) composite film using the i-t curve technique is 2.0 μM-1.95 mM. Similarly, the sensitivity of MWCNT-B(12) composite film for hydrazine determination using the i-t curve technique is 1.32 mA mM(-1)cm(-2), and the hydrazine's limit of detection at MWCNT-B(12) composite film is 0.7 μM.

  10. A novel method to encapsulate a Au nanorod array in 15 nm radius multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Liao, Gaomin; Pan, Yuanyuan; Wu, Qiang; Li, Shaoyun; Weng, Yuyan; Zhang, Xiaohua; Yang, Zhaohui; Guo, Jun; Chen, Muzi; Tang, Minghua; Tsui, Ophelia K. C.

    2014-11-01

    In this paper we demonstrate a novel complex array structure comprising well-aligned Au nanorods (10 nm in diameter) encapsulated inside 15 nm radius multiwalled carbon nanotubes (MWCNTs). A pre-aligned and open-ended nanoporous MWCNT membrane is used as the starting material. Au nanorods are precisely deposited and aligned inside the hollow channels of CNTs by inter-diffusing the HAuCl4 precursor and the reductant solution. Ultra-long Au nanowires and spherical Au nanoparticles are also observed in the CNT cavity with the same diameter in special cases. Using high-resolution TEM (HRTEM), scanning transmission electron microscopy (STEM), 3-dimensional TEM (3D-TEM) and energy dispersive X-ray spectroscopy (EDX), the precise location and composition of the encapsulated Au components with various structures are confirmed. This aligned Au@CNT endohedral material has important potential applications in nanocatalysis, waveguides, as well as in novel plasmonic devices.In this paper we demonstrate a novel complex array structure comprising well-aligned Au nanorods (10 nm in diameter) encapsulated inside 15 nm radius multiwalled carbon nanotubes (MWCNTs). A pre-aligned and open-ended nanoporous MWCNT membrane is used as the starting material. Au nanorods are precisely deposited and aligned inside the hollow channels of CNTs by inter-diffusing the HAuCl4 precursor and the reductant solution. Ultra-long Au nanowires and spherical Au nanoparticles are also observed in the CNT cavity with the same diameter in special cases. Using high-resolution TEM (HRTEM), scanning transmission electron microscopy (STEM), 3-dimensional TEM (3D-TEM) and energy dispersive X-ray spectroscopy (EDX), the precise location and composition of the encapsulated Au components with various structures are confirmed. This aligned Au@CNT endohedral material has important potential applications in nanocatalysis, waveguides, as well as in novel plasmonic devices. Electronic supplementary information (ESI

  11. Multi-walled carbon nanotube-graphene-polyaniline multiphase nanocomposite with superior electromagnetic shielding effectiveness

    NASA Astrophysics Data System (ADS)

    Gupta, Tejendra K.; Singh, Bhanu Pratap; Mathur, Rakesh B.; Dhakate, Sanjay R.

    2013-12-01

    The multiphase approach was adapted to enhance the electromagnetic interference (EMI) shielding effectiveness (SE) of polyaniline (PANI) based nanocomposites. The natural graphite flakes (NGF) incorporated modified PANI was used for the development of multi-walled carbon nanotubes (MWCNTs) based nanocomposites. In PANINGF-MWCNTs composites, multilayer graphene was synthesized in situ by ball milling. The resultant PANINGF-MWCNTs nanocomposites were characterized by different techniques. It was revealed from the transmission electron microscope (TEM) observation that in situ derived multilayer graphene acts as a bridge between PANI and MWCNTs, and plays a significant role for improving the properties of multiphase nanocomposites. It was observed that EMI-SE increases with increasing the MWCNTs content from 1 to 10 wt% in the multiphase nanocomposites. The maximum value of total EMI-SE was -98 dB of nanocomposite with 10 wt% of MWCNTs content. The high value of EMI-SE is dominated by the absorption phenomenon which is due to the collective effect of increase in space charge polarization and decrease in carrier mobility. The decrease in carrier mobility has a positive effect on the shore hardness value due to the strong interaction between the reinforcing constituent in multiphase nanocomposites. As a consequence, shore hardness increases from 56 to 91 at 10 wt% of MWCNTs.The multiphase approach was adapted to enhance the electromagnetic interference (EMI) shielding effectiveness (SE) of polyaniline (PANI) based nanocomposites. The natural graphite flakes (NGF) incorporated modified PANI was used for the development of multi-walled carbon nanotubes (MWCNTs) based nanocomposites. In PANINGF-MWCNTs composites, multilayer graphene was synthesized in situ by ball milling. The resultant PANINGF-MWCNTs nanocomposites were characterized by different techniques. It was revealed from the transmission electron microscope (TEM) observation that in situ derived multilayer

  12. Boron Doping of Multiwalled Carbon Nanotubes Significantly Enhances Hole Extraction in Carbon-Based Perovskite Solar Cells.

    PubMed

    Zheng, Xiaoli; Chen, Haining; Li, Qiang; Yang, Yinglong; Wei, Zhanhua; Bai, Yang; Qiu, Yongcai; Zhou, Dan; Wong, Kam Sing; Yang, Shihe

    2017-04-12

    Compared to the conventional perovskite solar cells (PSCs) containing hole-transport materials (HTM), carbon materials based HTM-free PSCs (C-PSCs) have often suffered from inferior power conversion efficiencies (PCEs) arising at least partially from the inefficient hole extraction at the perovskite-carbon interface. Here, we show that boron (B) doping of multiwalled carbon nanotubes (B-MWNTs) electrodes are superior in enabling enhanced hole extraction and transport by increasing work function, carrier concentration, and conductivity of MWNTs. The C-PSCs prepared using the B-MWNTs as the counter electrodes to extract and transport hole carriers have achieved remarkably higher performances than that with the undoped MWNTs, with the resulting PCE being considerably improved from 10.70% (average of 9.58%) to 14.60% (average of 13.70%). Significantly, these cells show negligible hysteretic behavior. Moreover, by coating a thin layer of insulating aluminum oxide (Al2O3) on the mesoporous TiO2 film as a physical barrier to substantially reduce the charge losses, the PCE has been further pushed to 15.23% (average 14.20%). Finally, the impressive durability and stability of the prepared C-PSCs were also testified under various conditions, including long-term air exposure, heat treatment, and high humidity.

  13. 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.

  14. 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.

  15. Modification of multiwall carbon nanotubes with ruthenium(II) terpyridine complex

    NASA Astrophysics Data System (ADS)

    Li, Huayang; Wu, Jie; Jeilani, Yassin A.; Ingram, Conrad W.; Harruna, Issifu I.

    2012-06-01

    Multiwall carbon nanotubes (MWCNTs, 1-3 μM in length and 20-25 nm in diameter) were initially functionalized with a 2,2':6'2″-terpyridine-chelated ruthenium(II) complex by covalent amidation. The resulting functionalized ruthenium MWCNTs (RuMWCNTs, 1-2 μM in length and 10-20 nm in diameter) were characterized by thermogravimetric analysis, X-ray photoelectronic spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and scanning electron microscopy (SEM). Thermogravimetric experiments of RuMWCNTs show that the functional group coverage of terpyridine-rutheniun-terpyridine (tpy-Ru-tpy) is 0.7036 mmol/1.0 g carbon. The XPS results show N1s and Ru3d5/5 signals, confirming the presence of tpy-Ru-tpy groups on the surface of MWCNTs. The FTIR spectra of the RuMWCNTs display the typical stretching mode of the carboxyl group (amide I) and a combination of amide N-H and C-N stretching mode (amide II). The Raman D- and G-line peak intensity ratio of RuMWCNTs (ID/IG 2.21) exceeds that of pristine MWCNTs (ID/IG 1.93), suggesting covalent bonding of tpy-Ru-tpy to MWCNTs and supporting the disruption of the graphitic integrity due to the proposed covalent functionalization. High-resolution SEM images confirm that tpy-Ru-tpy moieties are interconnected or attached as aggregated structures (100-200-nm range) on the surfaces of the carbon nanotubes after functionalization. The electrical property of RuMWCNTs depicts higher resistance (10.10 M Ω) than that of OX-MWCNTs (15.38 kΩ).

  16. Pseudocapacitive Desalination of Brackish Water and Seawater with Vanadium-Pentoxide-Decorated Multiwalled Carbon Nanotubes.

    PubMed

    Lee, Juhan; Srimuk, Pattarachai; Aristizabal, Katherine; Kim, Choonsoo; Choudhury, Soumyadip; Nah, Yoon-Chae; Mücklich, Frank; Presser, Volker

    2017-09-22

    A hybrid membrane pseudocapacitive deionization (MPDI) system consisting of a hydrated vanadium pentoxide (hV2 O5 )-decorated multi-walled carbon nanotube (MWCNT) electrode and one activated carbon electrode enables sodium ions to be removed by pseudocapacitive intercalation with the MWCNT-hV2 O5 electrode and chloride ion to be removed by non-faradaic electrosorption of the porous carbon electrode. The MWCNT-hV2 O5 electrode was synthesized by electrochemical deposition of hydrated vanadium pentoxide on the MWCNT paper. The stable electrochemical operating window for the MWCNT-hV2 O5 electrode was between -0.5 V and +0.4 V versus Ag/AgCl, which provided a specific capacity of 44 mAh g(-1) (corresponding with 244 F g(-1) ) in aqueous 1 m NaCl. The desalination performance of the MPDI system was investigated in aqueous 200 mm NaCl (brackish water) and 600 mm NaCl (seawater) solutions. With the aid of an anion and a cation exchange membrane, the MPDI hybrid cell was operated from -0.4 to +0.8 V cell voltage without crossing the reduction and oxidation potential limit of both electrodes. For the 600 mm NaCl solution, the NaCl salt adsorption capacity of the cell was 23.6±2.2 mg g(-1) , which is equivalent to 35.7±3.3 mg g(-1) normalized to the mass of the MWCNT-hV2 O5 electrode. Additionally, we propose a normalization method for the electrode material with faradaic reactions based on sodium uptake capacities. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Hybrid polymer-grafted multiwalled carbon nanotubes for in vitro gene delivery.

    PubMed

    Nunes, Antonio; Amsharov, Nadja; Guo, Chang; Van den Bossche, Jeroen; Santhosh, Padmanabhan; Karachalios, Theodoros K; Nitodas, Stephanos F; Burghard, Marko; Kostarelos, Kostas; Al-Jamal, Khuloud T

    2010-10-18

    Carbon nanotubes (CNTs) consist of carbon atoms arranged in sheets of graphene rolled up into cylindrical shapes. This class of nanomaterials has attracted attention because of their extraordinary properties, such as high electrical and thermal conductivity. In addition, development in CNT functionalization chemistry has led to an enhanced dispersibility in aqueous physiological media which indeed broadens the spectrum for their potential biological applications including gene delivery. The aim of this study is to determine the capability of different cationic polymer-grafted multiwalled carbon nanotubes (MWNTs) (polymer-g-MWNTs) to efficiently complex and transfer plasmid DNA (pCMV-βGal) in vitro without promoting cytotoxicity. Carboxylated MWNT is chemically conjugated to the cationic polymers polyethylenimine (PEI), polyallylamine (PAA), or a mixture of the two polymers. In order to explore the potential of these polymer-g-MWNTs as gene delivery systems, we first study their capacity to complex plasmid DNA (pDNA) using agarose gel electrophoresis. Gel migration studies confirm pDNA binding to polymer-g-MWNT with different affinities, highest for PEI-g-MWNT and PEI/PAA-g-CNT constructs. β-galactosidase expression is assessed in human lung epithelial (A549) cells, and the cytotoxicity is determined by modified LDH assay after 24 h incubation period. Additionally, PEI-g-MWNT and/or PEI/PAA-g-MWNT reveal an improvement in gene expression when compared to the naked pDNA or to the equivalent amounts of PEI polymer alone. Mechanistically, pDNA was delivered by the polymer-g-MWNT constructs via a different pathway compared to those used by polyplexes. In conclusion, polymer-g-MWNTs may be considered in the future as a versatile tool for efficient gene transfer in cancer cells in vitro, provided their toxicological profile is established.

  18. 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}.

  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. 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