Constitutive Modeling of Nanotube-Reinforced Polymer Composite Systems

NASA Technical Reports Server (NTRS)

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

2004-01-01

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

Constitutive Modeling of Nanotube-Reinforced Polymer Composite Systems

NASA Technical Reports Server (NTRS)

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

2001-01-01

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

Direct observation of hole transfer from semiconducting polymer to carbon nanotubes.

PubMed

Lan, Fei; Li, Guangyong

2013-05-08

Carbon nanotubes have been proven to play significant roles in polymer-based solar cells. However, there is intensive debate on whether carbon nanotube behaves as a donor or acceptor in the semiconducting polymer:carbon nanotube composite. In this paper, we report a direct observation via Kelvin probe force microscopy (KPFM) that single walled carbon nanotubes (SWNTs) behave as hole transporting channels in poly(3-hexylthiophene-2,5-diyl) (P3HT)/SWNT heterojunctions. By comparing the surface potential (SP) change of SWNT in dark and under illumination, we observed that electrons are blocked from SWNT while holes are transferred to SWNT. This observation can be well-explained by our proposed band alignment model of P3HT/SWNT heterojunction. The finding is further verified by hole mobility measurement using the space charge limited current (SCLC) method. SCLC results indicate that the existence of small amount of SWNT (wt 0.5%) promotes device hole mobility to around 15-fold, indicating SWNT act as hole transfer channel. Our finding of hole transporting behavior of SWNT in P3HT/SWNT blend will provide a useful guidance for enhancing the performance of polymer solar cells by carbon nanotubes.

Superionic conductor PbSnF4 in the inner channel of SWNT

NASA Astrophysics Data System (ADS)

Zakalyukin, Ruslan Mikhalovich; Levkevich, Ekaterina Alexandrovna; Kumskov, Andrey Sergeevich; Orekhov, Andrey Sergeevich

2018-04-01

The nanocomposite PbSnF4@SWNT was obtained by capillary technique for the first time. This nanocomposite was investigated using X-ray diffraction phase analysis (XRD), high-resolution transmission electron microscopy (HRTEM) and scanning transmission electron microscopy (STEM), energy-dispersive X-ray spectroscopy (EDX). SWNT diameter is ˜2 nm. Lead tetrafluorostannate (PbSnF4) monoclinic modification (space group P2/n) was identified by XRD analysis. The periodicity of the crystal plane (201) along the tube axis is ˜3.2Å. The distortion of plane is 11° with respect to the nanotube axis. The model of PbSnF4 single crystal contains ˜168 atoms. The structure of 1D PbSnF4@SWNT nanocomposite and HREM image were modelled.

Effect of Polymer Gate Dielectrics on Charge Transport in Carbon Nanotube Network Transistors: Low-k Insulator for Favorable Active Interface.

PubMed

Lee, Seung-Hoon; Xu, Yong; Khim, Dongyoon; Park, Won-Tae; Kim, Dong-Yu; Noh, Yong-Young

2016-11-30

Charge transport in carbon nanotube network transistors strongly depends on the properties of the gate dielectric that is in direct contact with the semiconducting carbon nanotubes. In this work, we investigate the dielectric effects on charge transport in polymer-sorted semiconducting single-walled carbon nanotube field-effect transistors (s-SWNT-FETs) by using three different polymer insulators: A low-permittivity (ε r ) fluoropolymer (CYTOP, ε r = 1.8), poly(methyl methacrylate) (PMMA, ε r = 3.3), and a high-ε r ferroelectric relaxor [P(VDF-TrFE-CTFE), ε r = 14.2]. The s-SWNT-FETs with polymer dielectrics show typical ambipolar charge transport with high ON/OFF ratios (up to ∼10 5 ) and mobilities (hole mobility up to 6.77 cm 2 V -1 s -1 for CYTOP). The s-SWNT-FET with the lowest-k dielectric, CYTOP, exhibits the highest mobility owing to formation of a favorable interface for charge transport, which is confirmed by the lowest activation energies, evaluated by the fluctuation-induced tunneling model (FIT) and the traditional Arrhenius model (E aFIT = 60.2 meV and E aArr = 10 meV). The operational stability of the devices showed a good agreement with the activation energies trend (drain current decay ∼14%, threshold voltage shift ∼0.26 V in p-type regime of CYTOP devices). The poor performance in high-ε r devices is accounted for by a large energetic disorder caused by the randomly oriented dipoles in high-k dielectrics. In conclusion, the low-k dielectric forms a favorable interface with s-SWNTs for efficient charge transport in s-SWNT-FETs.

Role of Defects in Single-Walled Carbon Nanotube Chemical Sensors

DTIC Science & Technology

2006-07-01

Role of Defects in Single-Walled Carbon Nanotube Chemical Sensors Joshua A . Robinson, Eric S. Snow,* Ştefan C. Bǎdescu, Thomas L. Reinecke, and F...of chemical vapors. We find adsorption at defect sites produces a large electronic response that dominates the SWNT capacitance and conductance...introduction of oxidation defects can be used to enhance sensitivity of a SWNT network sensor to a variety of chemical vapors. The use of single-walled

Ultrahigh density alignment of carbon nanotube arrays by dielectrophoresis.

PubMed

Shekhar, Shashank; Stokes, Paul; Khondaker, Saiful I

2011-03-22

We report ultrahigh density assembly of aligned single-walled carbon nanotube (SWNT) two-dimensional arrays via AC dielectrophoresis using high-quality surfactant-free and stable SWNT solutions. After optimization of frequency and trapping time, we can reproducibly control the linear density of the SWNT between prefabricated electrodes from 0.5 SWNT/μm to more than 30 SWNT/μm by tuning the concentration of the nanotubes in the solution. Our maximum density of 30 SWNT/μm is the highest for aligned arrays via any solution processing technique reported so far. Further increase of SWNT concentration results in a dense array with multiple layers. We discuss how the orientation and density of the nanotubes vary with concentrations and channel lengths. Electrical measurement data show that the densely packed aligned arrays have low sheet resistances. Selective removal of metallic SWNTs via controlled electrical breakdown produced field-effect transistors with high current on-off ratio. Ultrahigh density alignment reported here will have important implications in fabricating high-quality devices for digital and analog electronics.

Medium scale carbon nanotube thin film integrated circuits on flexible plastic substrates

DOEpatents

Rogers, John A; Cao, Qing; Alam, Muhammad; Pimparkar, Ninad

2015-02-03

The present invention provides device components geometries and fabrication strategies for enhancing the electronic performance of electronic devices based on thin films of randomly oriented or partially aligned semiconducting nanotubes. In certain aspects, devices and methods of the present invention incorporate a patterned layer of randomly oriented or partially aligned carbon nanotubes, such as one or more interconnected SWNT networks, providing a semiconductor channel exhibiting improved electronic properties relative to conventional nanotubes-based electronic systems.

Constitutive Modeling of Nanotube-Reinforced Polymer Composites

NASA Technical Reports Server (NTRS)

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

2002-01-01

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

Edge effects control helical wrapping of carbon nanotubes by polysaccharides

NASA Astrophysics Data System (ADS)

Liu, Yingzhe; Chipot, Christophe; Shao, Xueguang; Cai, Wensheng

2012-03-01

Carbon nanotubes (CNTs) wrapped by polysaccharide chains via noncovalent interactions have been shown to be soluble and dispersed in aqueous environments, and have several potential chemical and biomedical applications. The wrapping mechanism, in particular the role played by the end of the CNT, remains, however, unknown. In this work, a hybrid complex formed by an amylose (AMYL) chain and a single-walled carbon nanotube (SWNT) has been examined by means of atomistic molecular dynamics (MD) simulations to assess its propensity toward self-assembly, alongside its structural characteristics in water. To explore edge effects, the middle and end regions of the SWNT have been chosen as two initial wrapping sites, to which two relative orientations have been assigned, i.e. parallel and orthogonal. The present results prove that AMYL can wrap spontaneously around the tubular surface, starting from the end of the SWNT and driven by both favorable van der Waals attraction and hydrophobic interactions, and resulting in a perfectly compact, helical conformation stabilized by an interlaced hydrogen-bond network. Principal component analysis carried out over the MD trajectories reveals that stepwise burial of hydrophobic faces of pyranose rings controlled by hydrophobic interactions is a key step in the formation of the helix. Conversely, if wrapping proceeds from the middle of the SWNT, self-organization into a helical structure is not observed due to strong van der Waals attractions preventing the hydrophobic faces of the AMYL chain generating enough contacts with the tubular surface.Carbon nanotubes (CNTs) wrapped by polysaccharide chains via noncovalent interactions have been shown to be soluble and dispersed in aqueous environments, and have several potential chemical and biomedical applications. The wrapping mechanism, in particular the role played by the end of the CNT, remains, however, unknown. In this work, a hybrid complex formed by an amylose (AMYL) chain and a

Applications of Quantum Chemistry to the Study of Carbon Nanotubes

NASA Technical Reports Server (NTRS)

Jaffe, Richard L.

2005-01-01

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

Electroconductive PET/SWNT Films by Solution Casting

NASA Technical Reports Server (NTRS)

Steinert, Brian W.; Dean, Derrick R.

2008-01-01

The market for electrically conductive polymers is rapidly growing, and an emerging pathway for attaining these materials is via polymer-carbon nanotube (CNT) nanocomposites, because of the superior properties of CNTs. Due to their excellent electrical properties and anisotropic magnetic susceptibility, we expect CNTs could be easily aligned to maximize their effectiveness in imparting electrical conductivity to the polymer matrix. Single-walled carbon nanotubes (SWNT) were dispersed in a polyethylene terephthalate (PET) matrix by solution blending then cast onto a glass substrate to create thin, flexible films. Various SWNT loading concentrations were implemented (0.5, 1.0, and 3.0 wt.%) to study the effect of additive density. The processing method was repeated to produce films in the presence of magnetic fields (3 and 9.4 Tesla). The SWNTs showed a high susceptibility to the magnetic field and were effectively aligned in the PET matrix. The alignment was characterized with Raman spectroscopy. Impedance spectroscopy was utilized to study the electrical behavior of the films. Concentration and dispersion seemed to play very important roles in improving electrical conductivity, while alignment played a secondary and less significant role. The most interesting result proved to be the effect of a magnetic field during processing. It appears that a magnetic field may improve dispersion of unmodified SWNTs, which seems to be more important than alignment. It was concluded that SWNTs offer a good option as conductive, nucleating filler for electroconductive polymer applications, and the utilization of a magnetic field may prove to be a novel method for CNT dispersion that could lead to improved nanocomposite materials.

Constitutive Modeling of Nanotube-Reinforced Polymer Composites

NASA Technical Reports Server (NTRS)

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

2002-01-01

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

First step in developing SWNT nano-sensor for C17.2 neural stem cells

NASA Astrophysics Data System (ADS)

Ignatova, Tetyana; Pirbhai, Massooma; Chandrasekar, Swetha; Rotkin, Slava V.; Jedlicka, Sabrina

Nanomaterials are widely used for biomedical applications and diagnostics, including as drug and gene delivery agents, imaging objects, and biosensors. As single-wall carbon nanotubes (SWNTs) possess a size similar to intracellular components, including fibrillar proteins and some organelles, the potential for use in a wide variety of intracellular applications is significant. However, implementation of an SWNT based nano-sensor is difficult due to lack of understanding of SWNT-cell interaction on both the cellular and molecular level. In this study, C17.2 neural stem cells have been tested after uptake of SWNTs wrapped with ssDNA over a wide variety of time periods, allowing for broad localization of SWNTs inside of the cells over long time periods. The localization data is being used to develop a predictive model of how, upon uptake of SWNT, the cytoskeleton and other cellular structures of the adherent cells is perturbed.

Anti-tumor response with immunologically modified carbon nanotubes and phototherapy

NASA Astrophysics Data System (ADS)

Acquaviva, Joseph T.; Zhou, Feifan; Boarman, Ellen; Chen, Wei R.

2013-02-01

While successes of different cancer therapies have been achieved in various degrees a systemic immune response is needed to effectively treat late-stage, metastatic cancers, and to establish long-term tumor resistance in the patients. A novel method for combating metastatic cancers has been developed using immunologically modified carbon nanotubes in conjunction with phototherapy. Glycated chitosan (GC) is a potent immunological adjuvant capable of increasing host immune responses, including antigen presentation by activation of dendritic cells (DCs) and causing T cell proliferation. GC is also an effective surfactant for nanomaterials. By combining single-walled carbon nanotubes (SWNTs) and GC, immunologically modified carbon nanotubes (SWNT-GC) were constructed. The SWNT-GC suspension retains the enhanced light absorption properties in the near infrared (NIR) region and the ability to enter cells, which are characteristic of SWNTs. The SWNT-GC also retains the immunological properties of GC. Cellular SWNT-GC treatments increased macrophage activity, DC activation and T cell proliferation. When cellular SWNT-GC was irradiated with a laser of an appropriate wavelength, these immune activities could be enhanced. The combination of laser irradiation and SWNT-GC induced cellular toxicity in targeted tumor cells, leading to a systemic antitumor response. Immunologically modified carbon nanotubes in conjunction with phototherapy is a novel and promising method to produce a systemic immune response for the treatment of metastatic cancers.

A Biosynthetic Nerve Guide Conduit Based on Silk/SWNT/Fibronectin Nanocomposite for Peripheral Nerve Regeneration

PubMed Central

Mottaghitalab, Fatemeh; Farokhi, Mehdi; Zaminy, Arash; Kokabi, Mehrdad; Soleimani, Masoud; Mirahmadi, Fereshteh

2013-01-01

As a contribution to the functionality of nerve guide conduits (NGCs) in nerve tissue engineering, here we report a conduit processing technique through introduction and evaluation of topographical, physical and chemical cues. Porous structure of NGCs based on freeze-dried silk/single walled carbon nanotubes (SF/SWNTs) has shown a uniform chemical and physical structure with suitable electrical conductivity. Moreover, fibronectin (FN) containing nanofibers within the structure of SF/SWNT conduits produced through electrospinning process have shown aligned fashion with appropriate porosity and diameter. Moreover, fibronectin remained its bioactivity and influenced the adhesion and growth of U373 cell lines. The conduits were then implanted to 10 mm left sciatic nerve defects in rats. The histological assessment has shown that nerve regeneration has taken places in proximal region of implanted nerve after 5 weeks following surgery. Furthermore, nerve conduction velocities (NCV) and more myelinated axons were observed in SF/SWNT and SF/SWNT/FN groups after 5 weeks post implantation, indicating a functional recovery for the injured nerves. With immunohistochemistry, the higher S-100 expression of Schwann cells in SF/SWNT/FN conduits in comparison to other groups was confirmed. In conclusion, an oriented conduit of biocompatible SF/SWNT/FN has been fabricated with acceptable structure that is particularly applicable in nerve grafts. PMID:24098649

Carbon Nanotubes for Space Photovoltaic Applications

NASA Technical Reports Server (NTRS)

Efstathiadis, Harry; Haldar, Pradeep; Landi, Brian J.; Denno, Patrick L.; DiLeo, Roberta A.; VanDerveer, William; Raffaelle, Ryne P.

2007-01-01

Carbon nanotubes (CNTs) can be envisioned as an individual graphene sheet rolled into a seamless cylinder (single-walled, SWNT), or concentric sheets as in the case of a multi-walled carbon nanotube (MWNT) (1). The role-up vector will determine the hexagonal arrangement and "chirality" of the graphene sheet, which will establish the nanotube to be metallic or semiconducting. The optoelectronic properties will depend directly on this chiral angle and the diameter of the SWNT, with semiconductor types exhibiting a band gap energy (2). Characteristic of MWNTs are the concentric graphene layers spaced 0.34 nm apart, with diameters from 10-200 nm and lengths up to hundreds of microns (2). In the case of SWNTs, the diameters range from 0.4 - 2 nm and lengths have been reported up to 1.5 cm (3). SWNTs have the distinguishable property of "bundling" together due to van der Waal's attractions to form "ropes." A comparison of these different structural types is shown in Figure 1. The use of SWNTS in space photovoltaic (PV) applications is attractive for a variety of reasons. Carbon nanotubes as a class of materials exhibit unprecedented optical, electrical, mechanical properties, with the added benefit of being nanoscale in size which fosters ideal interaction in nanomaterial-based devices like polymeric solar cells. The optical bandgap of semiconducting SWNTs can be varied from approx. 0.4 - 1.5 eV, with this property being inversely proportional to the nanotube diameter. Recent work at GE Global Research has shown where a single nanotube device can behave as an "ideal" pn diode (5). The SWNT was bridged over a SiO2 channel between Mo contacts and exhibited an ideality factor of 1, based on a fit of the current-voltage data using the diode equation. The measured PV efficiency under a 0.8 eV monochromatic illumination showed a power conversion efficiency of 0.2 %. However, the projected efficiency of these junctions is estimated to be > 5 %, especially when one considers the

Carbon Nanotube Driver Circuit for 6 × 6 Organic Light Emitting Diode Display

NASA Astrophysics Data System (ADS)

Zou, Jianping; Zhang, Kang; Li, Jingqi; Zhao, Yongbiao; Wang, Yilei; Pillai, Suresh Kumar Raman; Volkan Demir, Hilmi; Sun, Xiaowei; Chan-Park, Mary B.; Zhang, Qing

2015-06-01

Single-walled carbon nanotube (SWNT) is expected to be a very promising material for flexible and transparent driver circuits for active matrix organic light emitting diode (AM OLED) displays due to its high field-effect mobility, excellent current carrying capacity, optical transparency and mechanical flexibility. Although there have been several publications about SWNT driver circuits, none of them have shown static and dynamic images with the AM OLED displays. Here we report on the first successful chemical vapor deposition (CVD)-grown SWNT network thin film transistor (TFT) driver circuits for static and dynamic AM OLED displays with 6 × 6 pixels. The high device mobility of ~45 cm2V-1s-1 and the high channel current on/off ratio of ~105 of the SWNT-TFTs fully guarantee the control capability to the OLED pixels. Our results suggest that SWNT-TFTs are promising backplane building blocks for future OLED displays.

Carbon Nanotube Driver Circuit for 6 × 6 Organic Light Emitting Diode Display

PubMed Central

Zou, Jianping; Zhang, Kang; Li, Jingqi; Zhao, Yongbiao; Wang, Yilei; Pillai, Suresh Kumar Raman; Volkan Demir, Hilmi; Sun, Xiaowei; Chan-Park, Mary B.; Zhang, Qing

2015-01-01

Single-walled carbon nanotube (SWNT) is expected to be a very promising material for flexible and transparent driver circuits for active matrix organic light emitting diode (AM OLED) displays due to its high field-effect mobility, excellent current carrying capacity, optical transparency and mechanical flexibility. Although there have been several publications about SWNT driver circuits, none of them have shown static and dynamic images with the AM OLED displays. Here we report on the first successful chemical vapor deposition (CVD)-grown SWNT network thin film transistor (TFT) driver circuits for static and dynamic AM OLED displays with 6 × 6 pixels. The high device mobility of ~45 cm2V−1s−1 and the high channel current on/off ratio of ~105 of the SWNT-TFTs fully guarantee the control capability to the OLED pixels. Our results suggest that SWNT-TFTs are promising backplane building blocks for future OLED displays. PMID:26119218

Carbon Nanotube Driver Circuit for 6 × 6 Organic Light Emitting Diode Display.

PubMed

Zou, Jianping; Zhang, Kang; Li, Jingqi; Zhao, Yongbiao; Wang, Yilei; Pillai, Suresh Kumar Raman; Volkan Demir, Hilmi; Sun, Xiaowei; Chan-Park, Mary B; Zhang, Qing

2015-06-29

Single-walled carbon nanotube (SWNT) is expected to be a very promising material for flexible and transparent driver circuits for active matrix organic light emitting diode (AM OLED) displays due to its high field-effect mobility, excellent current carrying capacity, optical transparency and mechanical flexibility. Although there have been several publications about SWNT driver circuits, none of them have shown static and dynamic images with the AM OLED displays. Here we report on the first successful chemical vapor deposition (CVD)-grown SWNT network thin film transistor (TFT) driver circuits for static and dynamic AM OLED displays with 6 × 6 pixels. The high device mobility of ~45 cm(2)V(-1)s(-1) and the high channel current on/off ratio of ~10(5) of the SWNT-TFTs fully guarantee the control capability to the OLED pixels. Our results suggest that SWNT-TFTs are promising backplane building blocks for future OLED displays.

Mechanically stiff, electrically conductive composites of polymers and carbon nanotubes

DOEpatents

Worsley, Marcus A.; Kucheyev, Sergei O.; Baumann, Theodore F.; Kuntz, Joshua D.; Satcher, Jr., Joe H.; Hamza, Alex V.

2015-07-21

Using SWNT-CA as scaffolds to fabricate stiff, highly conductive polymer (PDMS) composites. The SWNT-CA is immersing in a polymer resin to produce a SWNT-CA infiltrated with a polymer resin. The SWNT-CA infiltrated with a polymer resin is cured to produce the stiff and electrically conductive composite of carbon nanotube aerogel and polymer.

Mechanically stiff, electrically conductive composites of polymers and carbon nanotubes

DOEpatents

Worsley, Marcus A.; Kucheyev, Sergei O.; Baumann, Theodore F.; Kuntz, Joshua D.; Satcher, Jr., Joe H.; Hamza, Alex V.

2017-10-17

Using SWNT-CA as scaffolds to fabricate stiff, highly conductive polymer (PDMS) composites. The SWNT-CA is immersing in a polymer resin to produce a SWNT-CA infiltrated with a polymer resin. The SWNT-CA infiltrated with a polymer resin is cured to produce the stiff and electrically conductive composite of carbon nanotube aerogel and polymer.

Electronically type-sorted carbon nanotube-based electrochemical biosensors with glucose oxidase and dehydrogenase.

PubMed

Muguruma, Hitoshi; Hoshino, Tatsuya; Nowaki, Kohei

2015-01-14

An electrochemical enzyme biosensor with electronically type-sorted (metallic and semiconducting) single-walled carbon nanotubes (SWNTs) for use in aqueous media is presented. This research investigates how the electronic types of SWNTs influence the amperometric response of enzyme biosensors. To conduct a clear evaluation, a simple layer-by-layer process based on a plasma-polymerized nano thin film (PPF) was adopted because a PPF is an inactive matrix that can form a well-defined nanostructure composed of SWNTs and enzyme. For a biosensor with the glucose oxidase (GOx) enzyme in the presence of oxygen, the response of a metallic SWNT-GOx electrode was 2 times larger than that of a semiconducting SWNT-GOx electrode. In contrast, in the absence of oxygen, the response of the semiconducting SWNT-GOx electrode was retained, whereas that of the metallic SWNT-GOx electrode was significantly reduced. This indicates that direct electron transfer occurred with the semiconducting SWNT-GOx electrode, whereas the metallic SWNT-GOx electrode was dominated by a hydrogen peroxide pathway caused by an enzymatic reaction. For a biosensor with the glucose dehydrogenase (GDH; oxygen-independent catalysis) enzyme, the response of the semiconducting SWNT-GDH electrode was 4 times larger than that of the metallic SWNT-GDH electrode. Electrochemical impedance spectroscopy was used to show that the semiconducting SWNT network has less resistance for electron transfer than the metallic SWNT network. Therefore, it was concluded that semiconducting SWNTs are more suitable than metallic SWNTs for electrochemical enzyme biosensors in terms of direct electron transfer as a detection mechanism. This study makes a valuable contribution toward the development of electrochemical biosensors that employ sorted SWNTs and various enzymes.

Pyrene-based fluorescent ambidextrous gelators: scaffolds for mechanically robust SWNT-gel nanocomposites.

PubMed

Mandal, Deep; Kar, Tanmoy; Das, Prasanta Kumar

2014-01-27

With the rapid progress in the development of supramolecular soft materials, examples of low-molecular-weight gelators (LMWGs) with the ability to immobilise both water and organic solvents by the same structural scaffold are very limited. In this paper, we report the development of pyrene-containing peptide-based ambidextrous gelators (AGs) with the ability to efficiently gelate both organic and aqueous solvents. The organo- and hydrogelation efficiencies of these gelators are in the range 0.7-1.1% w/v in various organic solvents and 0.5-5% w/v in water at certain acidic pH values (pH 2.0-4.0). Moreover, for the first time, AGs have been utilised to prepare single-walled carbon-nanotube (SWNT)-included soft nanocomposites in both hydro- and organogel matrices. The influence of different non-covalent interactions such as hydrogen bonding, hydrophobic, π-π and van der Waals interactions in self-assembled gelation has been studied in detail by circular dichroism, FTIR, variable-temperature NMR, 2D NOESY and luminescence spectroscopy. Interestingly, the presence of the pyrene moiety in the structure rendered these AGs intrinsically fluorescent, which was quenched upon successful integration of the SWNTs within the gel. The prepared hydro- and organogels along with their SWNT-integrated nanocomposites are thermoreversible in nature. The supramolecular morphologies of the dried gels and SWNT-gel nanocomposites have been studied by transmission electron microscopy, fluorescence microscopy and polarising optical microscopy, which confirmed the presence of three-dimensional self-assembled fibrillar networks (SAFINs) as well as the integrated SWNTs. Importantly, rheological studies revealed that the inclusion of SWNTs within the ambidextrous gels improved the mechanical rigidity of the resulting soft nanocomposites up to 3.8-fold relative to the native gels. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Multiparameter structural optimization of single-walled carbon nanotube composites: toward record strength, stiffness, and toughness.

PubMed

Shim, Bong Sup; Zhu, Jian; Jan, Edward; Critchley, Kevin; Ho, Szushen; Podsiadlo, Paul; Sun, Kai; Kotov, Nicholas A

2009-07-28

Efficient coupling of mechanical properties of SWNTs with the matrix leading to the transfer of unique mechanical properties of SWNTs to the macroscopic composites is a tremendous challenge of today's materials science. The typical mechanical properties of known SWNT composites, such as strength, stiffness, and toughness, are assessed in an introductory survey where we focused on concrete numerical parameters characterizing mechanical properties. Obtaining ideal stress transfer will require fine optimization of nanotube-polymer interface. SWNT nanocomposites were made here by layer-by-layer (LBL) assembly with poly(vinyl alcohol) (PVA), and the first example of optimization in respect to key parameters determining the connectivity at the graphene-polymer interface, namely, degree of SWNT oxidation and cross-linking chemistry, was demonstrated. The resulting SWNT-PVA composites demonstrated tensile strength (σ(ult)) = 504.5 ± 67.3 MPa, stiffness (E) = 15.6 ± 3.8 GPa, and toughness (K) = 121.2 ± 19.2 J/g with maximum values recorded at σ(ult) = 600.1 MPa, E = 20.6 GPa, and K = 152.1 J/g. This represents the strongest and stiffest nonfibrous SWNT composites made to date outperforming other bulk composites by 2-10 times. Its high performance is attributed to both high nanotube content and efficient stress transfer. The resulting LBL composite is also one of the toughest in this category of materials and exceeding the toughness of Kevlar by 3-fold. Our observation suggests that the strengthening and toughening mechanism originates from the synergistic combination of high degree of SWNT exfoliation, efficient SWNT-PVA binding, crack surface roughening, and fairly efficient distribution of local stress over the SWNT network. The need for a multiscale approach in designing SWNT composites is advocated.

Dispersion of Single Wall Carbon Nanotubes by in situ Polymerization Under Sonication

NASA Technical Reports Server (NTRS)

Park, Cheol; Ounaies, Zoubeida; Watson, Kent A.; Crooks, Roy E.; Smith, Joseph, Jr.; Lowther, Sharon E.; Connell, John W.; Siochi, Emilie J.; Harrison, Joycelyn S.; St.Clair, Terry L.

2002-01-01

Single wall nanotube reinforced polyimide nanocomposites were synthesized by in situ polymerization of monomers of interest in the presence of sonication. This process enabled uniform dispersion of single wall carbon nanotube (SWNT) bundles in the polymer matrix. The resultant SWNT-polyimide nanocomposite films were electrically conductive (antistatic) and optically transparent with significant conductivity enhancement (10 orders of magnitude) at a very low loading (0.1 vol%). Mechanical properties as well as thermal stability were also improved with the incorporation of the SWNT.

Strain Sensitivity in Single Walled Carbon Nanotubes for Multifunctional Materials

NASA Technical Reports Server (NTRS)

Heath, D. M. (Technical Monitor); Smits, Jan M., VI

2005-01-01

Single walled carbon nanotubes represent the future of structural aerospace vehicle systems due to their unparalleled strength characteristics and demonstrated multifunctionality. This multifunctionality rises from the CNT's unique capabilities for both metallic and semiconducting electron transport, electron spin polarizability, and band gap modulation under strain. By incorporating the use of electric field alignment and various lithography techniques, a single wall carbon nanotube (SWNT) test bed for measurement of conductivity/strain relationships has been developed. Nanotubes are deposited at specified locations through dielectrophoresis. The circuit is designed such that the central, current carrying section of the nanotube is exposed to enable atomic force microscopy and manipulation in situ while the transport properties of the junction are monitored. By applying this methodology to sensor development a flexible single wall carbon nanotube (SWNT) based strain sensitive device has been developed. Studies of tensile testing of the flexible SWNT device vs conductivity are also presented, demonstrating the feasibility of using single walled HiPCO (high-pressure carbon monoxide) carbon nanotubes as strain sensing agents in a multi-functional materials system.

Carbon nanotube-polymer composite actuators

DOEpatents

Gennett, Thomas [Denver, CO; Raffaelle, Ryne P [Honeoye Falls, NY; Landi, Brian J [Rochester, NY; Heben, Michael J [Denver, CO

2008-04-22

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

Heat Pulse Propagation in Carbon Nanotube Peapods

NASA Astrophysics Data System (ADS)

Osman, Mohamed

2013-03-01

Earlier studies of heat pulse propagation in single and double wall nanotubes at very low temperatures have shown that the heat pulse generated wave packets that moved at the speed of sound corresponding to LA and TW phonon modes, second sound waves and diffusive components. The energy content of LA mode wave packets in SWNT was significantly smaller than the TW mode. The energy of the leading LA mode wavepacket in DWNT had a significant increase in the energy content compared to SWNT LA mode. Additionally, an increase simple strain within the LA mode was higher in DWNT compared to SWNT was also reported in. This has motivated us to examine heat pulse propagation in carbon nanopeapods and the coupling between the (10,10) SWNT nanotube and the C60 fullerenes enclosed. The major coupling frequency between the C60 and the (10,10) occurs at 4.88 THz which correspond to the radial breathing mode frequency. We will discuss these results and report on the major phonon modes involved in heat pulse propagation in the (10,10) SWNT-C60 nanopeapod.

Heterostructured semiconductor single-walled carbon nanotube films for solution-processed high-performance field-effect transistors

NASA Astrophysics Data System (ADS)

Park, Noh-Hwal; Lee, Seung-Hoon; Jeong, Seung-Hyeon; Khim, Dongyoon; Kim, Yun Ho; Yoo, Sungmi; Noh, Yong-Young; Kim, Jang-Joo

2018-03-01

In this paper, we report a simple and effective method to simultaneously achieve a high charge-carrier mobility and low off current in conjugated polymer-wrapped semiconducting single-walled carbon nanotube (s-SWNT) transistors by applying a SWNT bilayer. To achieve the high mobility and low off current, highly purified and less purified s-SWNTs are successively coated to form the semiconducting layer consisting of poly (3-dodecylthiophene-2,5-diyl) (P3DDT)-wrapped high-pressure carbon mono oxide (HiPCO) SWNT (P3DDT-HiPCO) and poly (9, 9-di-n-dodecylfluorene) (PFDD)-wrapped plasma discharge (PD) SWNT (PFDD-PD). The SWNT transistors with bilayer SWNT networked film showed highly improved hole field-effect mobility (6.18 ± 0.85 cm2V-1s-1 average), on/off current ratio (107), and off current (˜1 pA). Thus, the combination of less purified PFDD-PD (98%-99%) charge-injection layer and highly purified s-P3DDT-HiPCO (>99%) charge-transport layer as the bi-layered semiconducting film achieved high mobility and low off current simultaneously.

Single-walled carbon nanotubes/polymer composite electrodes patterned directly from solution.

PubMed

Chang, Jingbo; Najeeb, Choolakadavil Khalid; Lee, Jae-Hyeok; Kim, Jae-Ho

2011-06-07

This work describes a simple technique for direct patterning of single-walled carbon nanotube (SWNT)/poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) composite electrodes in a large area on a substrate based on the solution transfer process by microcontact printing using poly(dimethylsiloxane) (PDMS) stamps. Various shapes of SWNT/PEDOT-PSS composite patterns, such as line, circle, and square, can be easily fabricated with high pattern fidelity and structural integrity. The single parallel line pattern device exhibits high electrical conductivity (0.75 × 10(5) S/m) and electronic stability because of alignment of nanotubes and big-size SWNT bundles (∼5 nm). The electromechanical study reveals that the composite patterns show ∼1% resistance change along SWNT alignment direction and ∼5% resistance change along vertical alignment direction after 200 bend cycles. Our approach provides a facile, low-cost method to pattern transparent conductive SWNT/polymer composite electrodes and demonstrates a novel platform for future integration of conducting SWNT/polymer composite patterns for optoelectronic applications.

Nanotube Film Electrode and an Electroactive Device Fabricated with the Nanotube Film Electrode and Methods for Making Same

NASA Technical Reports Server (NTRS)

Kang, Jin Ho (Inventor); Harrison, Joycelyn S. (Inventor); Park, Cheol (Inventor)

2017-01-01

Disclosed is a single wall carbon nanotube (SWCNT) film electrode (FE), all-organic electroactive device systems fabricated with the SWNT-FE, and methods for making same. The SWCNT can be replaced by other types of nanotubes. The SWCNT film can be obtained by filtering SWCNT solution onto the surface of an anodized alumina membrane. A freestanding flexible SWCNT film can be collected by breaking up this brittle membrane. The conductivity of this SWCNT film can advantageously be higher than 280 S/cm. An electroactive polymer (EAP) actuator layered with the SWNT-FE shows a higher electric field-induced strain than an EAP layered with metal electrodes because the flexible SWNT-FE relieves the restraint of the displacement of the polymeric active layer as compared to the metal electrode. In addition, if thin enough, the SWNT-FE is transparent in the visible light range, thus making it suitable for use in actuators used in optical devices.

Carbon nanotube-polymer nanocomposite infrared sensor.

PubMed

Pradhan, Basudev; Setyowati, Kristina; Liu, Haiying; Waldeck, David H; Chen, Jian

2008-04-01

The infrared photoresponse in the electrical conductivity of single-walled carbon nanotubes (SWNTs) is dramatically enhanced by embedding SWNTs in an electrically and thermally insulating polymer matrix. The conductivity change in a 5 wt % SWNT-polycarbonate nanocomposite is significant (4.26%) and sharp upon infrared illumination in the air at room temperature. While the thermal effect predominates in the infrared photoresponse of a pure SWNT film, the photoeffect predominates in the infrared photoresponse of SWNT-polycarbonate nanocomposites.

CARBON NANOTUBES IN MICROWAVE ENVIRONMENT-IGNITION AND RECONSTRUCTION

EPA Science Inventory

The unusual property of single-walled carbon nanotubes (SWNT), multi-wall (MWNT) nanotubes and Buckminsterfullerene (C-60) is observed upon exposure to microwave-assisted ignition. Carbon nanotubes known for a range of mechanical and electronic properties because of their unique...

Charge Transfer from Carbon Nanotubes to Silicon in Flexible Carbon Nanotube/Silicon Solar Cells

DOE PAGES

Li, Xiaokai; Mariano, Marina; McMillon-Brown, Lyndsey; ...

2017-11-10

Mechanical fragility and insufficient light absorption are two major challenges for thin flexible crystalline Si-based solar cells. Flexible hybrid single-walled carbon nanotube (SWNT)/Si solar cells are demonstrated by applying scalable room-temperature processes for the fabrication of solar-cell components (e.g., preparation of SWNT thin films and SWNT/Si p–n junctions). The flexible SWNT/Si solar cells present an intrinsic efficiency ≈7.5% without any additional light-trapping structures. By using these solar cells as model systems, the charge transport mechanisms at the SWNT/Si interface are investigated using femtosecond transient absorption. Although primary photon absorption occurs in Si, transient absorption measurements show that SWNTs also generatemore » and inject excited charge carriers to Si. Such effects can be tuned by controlling the thickness of the SWNTs. Thus, findings from this study could open a new pathway for designing and improving the efficiency of photocarrier generation and absorption for high-performance ultrathin hybrid SWNT/Si solar cells.« less

Charge Transfer from Carbon Nanotubes to Silicon in Flexible Carbon Nanotube/Silicon Solar Cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Xiaokai; Mariano, Marina; McMillon-Brown, Lyndsey

Mechanical fragility and insufficient light absorption are two major challenges for thin flexible crystalline Si-based solar cells. Flexible hybrid single-walled carbon nanotube (SWNT)/Si solar cells are demonstrated by applying scalable room-temperature processes for the fabrication of solar-cell components (e.g., preparation of SWNT thin films and SWNT/Si p–n junctions). The flexible SWNT/Si solar cells present an intrinsic efficiency ≈7.5% without any additional light-trapping structures. By using these solar cells as model systems, the charge transport mechanisms at the SWNT/Si interface are investigated using femtosecond transient absorption. Although primary photon absorption occurs in Si, transient absorption measurements show that SWNTs also generatemore » and inject excited charge carriers to Si. Such effects can be tuned by controlling the thickness of the SWNTs. Thus, findings from this study could open a new pathway for designing and improving the efficiency of photocarrier generation and absorption for high-performance ultrathin hybrid SWNT/Si solar cells.« less

Nanoscale soldering of axially positioned single-walled carbon nanotubes: a molecular dynamics simulation study.

PubMed

Cui, Jianlei; Yang, Lijun; Zhou, Liang; Wang, Yang

2014-02-12

The miniaturization of electronics devices into the nanometer scale is indispensable for next-generation semi-conductor technology. Carbon nanotubes (CNTs) are considered to be the promising candidates for future interconnection wires. To study the carbon nanotubes interconnection during nanosoldering, the melting process of nanosolder and nanosoldering process between single-walled carbon nanotubes are simulated with molecular dynamics method. As the simulation results, the melting point of 2 nm silver solder is about 605 K because of high surface energy, which is below the melting temperature of Ag bulk material. In the nanosoldering process simulations, Ag atoms may be dragged into the nanotubes to form different connection configuration, which has no apparent relationship with chirality of SWNTs. The length of core filling nanowires structure has the relationship with the diameter, and it does not become longer with the increasing diameter of SWNT. Subsequently, the dominant mechanism of was analyzed. In addition, as the heating temperature and time, respectively, increases, more Ag atoms can enter the SWNTs with longer length of Ag nanowires. And because of the strong metal bonds, less Ag atoms can remain with the tight atomic structures in the gap between SWNT and SWNT. The preferred interconnection configurations can be achieved between SWNT and SWNT in this paper.

Economic assessment of single-walled carbon nanotube processes

NASA Astrophysics Data System (ADS)

Isaacs, J. A.; Tanwani, A.; Healy, M. L.; Dahlben, L. J.

2010-02-01

The carbon nanotube market is steadily growing and projected to reach 1.9 billion by 2010. This study examines the economics of manufacturing single-walled carbon nanotubes (SWNT) using process-based cost models developed for arc, CVD, and HiPco processes. Using assumed input parameters, manufacturing costs are calculated for 1 g SWNT for arc, CVD, and HiPco, totaling 1,906, 1,706, and 485, respectively. For each SWNT process, the synthesis and filtration steps showed the highest costs, with direct labor as a primary cost driver. Reductions in production costs are calculated for increased working hours per day and for increased synthesis reaction yield (SRY) in each process. The process-based cost models offer a means for exploring opportunities for cost reductions, and provide a structured system for comparisons among alternative SWNT manufacturing processes. Further, the models can be used to comprehensively evaluate additional scenarios on the economics of environmental, health, and safety best manufacturing practices.

Thermal conductivity of a film of single walled carbon nanotubes measured with infrared thermal imager

NASA Astrophysics Data System (ADS)

Feng, Ya; Inoue, Taiki; Xiang, Rong; Chiashi, Shohei; Maruyama, Shigeo

Heat dissipation has restricted the modern miniaturization trend with the development of electronic devices. Theoretically proven to be with high axial thermal conductivity, single walled carbon nanotubes (SWNT) have long been expected to cool down the nanoscale world. Even though the tube-tube contact resistance limits the capability of heat transfer of the bulk film, the high intrinsic thermal conductivity of SWNT still glorify the application of films of SWNT network as a thermal interface material. In this work, we proposed a new method to straightly measure the thermal conductivity of SWNT film. We bridged two cantilevered Si thin plate with SWNT film, and kept a steady state heat flow in between. With the infrared camera to record the temperature distribution, the Si plates with known thermal conductivity can work as a reference to calculate the heat flux going through the SWNT film. Further, the thermal conductivity of the SWNT film can be obtained through Fourier's law after deducting the effect of thermal radiation. The sizes of the structure, the heating temperature, the vacuum degree and other crucial impact factors are carefully considered and analyzed. The author Y. F. was supported through the Advanced Integration Science Innovation Education and Research Consortium Program by the Ministry of Education, Culture, Sport, Science and Technology.

Structural characteristics of liquid nitromethane at the nanoscale confinement in carbon nanotubes.

PubMed

Liu, Yingzhe; Lai, Weipeng; Yu, Tao; Ge, Zhongxue; Kang, Ying

2014-10-01

The stability of energetic materials confined in the carbon nanotubes can be improved at ambient pressure and room temperature, leading to potential energy storage and controlled energy release. However, the microscopic structure of confined energetic materials and the role played by the confinement size are still fragmentary. In this study, molecular dynamics simulations have been performed to explore the structural characteristics of liquid nitromethane (NM), one of the simplest energetic materials, confined in a series of armchair single-walled carbon nanotubes (SWNTs) changing from (5,5) to (16,16) at ambient conditions. The simulation results show that the size-dependent ordered structures of NM with preferred orientations are formed inside the tubular cavities driven by the van der Waals attractions between NM and SWNT together with the dipole-dipole interactions of NM, giving rise to a higher local mass density than that of bulk NM. The NM dipoles prefer to align parallel along the SWNT axis in an end-to-end fashion inside all the nanotubes except the (7,7) SWNT where a unique staggered orientation of NM dipoles perpendicular to the SWNT axis is observed. As the SWNT radius increases, the structural arrangements and dipole orientations of NM become disordered as a result of the weakening of van der Waals interactions between NM and SWNT.

Application of liquid-liquid interactions with single-walled carbon nanotubes

NASA Astrophysics Data System (ADS)

Wang, Randy Kai-Wei

This study covers three important research topics related to the application of liquid-liquid interaction with single-walled carbon nanotubes (SWNTs). The first topic describes the removal of SWNT bundles from liquid suspensions of nanotubes. The key to this work includes the use of liquid-liquid interfaces to trap the SWNT bundles due to the free energy change of the system during the process. SWNTs pack into crystalline ropes that form bundles due to strong van der Waals attraction. Bundling diminishes mechanical and electronic properties because it could interrupt the electronic structure of the nanotubes. Also, the electronic devices based on as-grown nanotubes, which contains a mixture of individual nanotubes and nanotube bundles, make the electrical response unpredictable. We developed a new simple process to remove bundles by liquid-liquid interaction. SWNTs bundles are trapped at the interface because bundles stabilize the emulsions. Eliminating the use of ultracentrifugation to remove SWNT bundles enables large-scale production with reduced production costs and time savings. The second topic presented the swelling effect of the surfactant layer surrounding SWNTs with nonpolar solvents. Solvatochromic shifts in the absorbance and fluorescence spectra are observed when surfactant-stabilized aqueous SWNT suspensions are mixed with immiscible organic solvents. When aqueous surfactant-suspended SWNTs are mixed with certain solvents, the spectra closely match the peaks for SWNTs dispersed in only that solvent. These spectral changes suggest the hydrophobic region of the micelle surrounding SWNTs swells with the organic solvent when mixed. The solvatochromic shifts of the aqueous SWNT suspensions are reversible once the solvent evaporates. However, some surfactant-solvent systems show permanent changes to the fluorescence emission intensity after exposure to the organic solvent. The intensity of some large diameter SWNT (n, m) types increase by more than 175

Electromechanical Actuator Performance of Carbon Nanotube Fibers

NASA Astrophysics Data System (ADS)

Munoz, Edgar; Kozlov, Mikhail; Collins, Steve; Dalton, Alan B.; Razal, Joselito; Zakhidov, Anvar A.; Baughman, Ray H.

2003-03-01

Single-walled carbon nanotube (SWNT) assemblies (sheets and fibers) have been investigated as electromechanical actuators. SWNT fibers provide maximum isometric actuator stress values of 20-26 MPa, which is about 5-10 times larger that those corresponding to SWNT sheets. This actuation performance is about 100 timer larger than the stress generation capability of natural muscle. The effect of employing different electrolytes as well as SWNTs produced by different routes, and the potential applications of these actuators will be also discussed.

Role of surfactants in carbon nanotubes density gradient separation.

PubMed

Carvalho, Elton J F; dos Santos, Maria Cristina

2010-02-23

Several strategies aimed at sorting single-walled carbon nanotubes (SWNT) by diameter and/or electronic structure have been developed in recent years. A nondestructive sorting method was recently proposed in which nanotube bundles are dispersed in water-surfactant solutions and submitted to ultracentrifugation in a density gradient. By this method, SWNTs of different diameters are distributed according to their densities along the centrifuge tube. A mixture of two anionic amphiphiles, namely sodium dodecylsulfate (SDS) and sodium cholate (SC), presented the best performance in discriminating nanotubes by diameter. We present molecular dynamics studies of the water-surfactant-SWNT system. The simulations revealed one aspect of the discriminating power of surfactants: they can actually be attracted toward the interior of the nanotube cage. The binding energies of SDS and SC on the outer nanotube surface are very similar and depend weakly on diameter. The binding inside the tubes, on the contrary, is strongly diameter dependent: SDS fits best inside tubes with diameters ranging from 8 to 9 A, while SC is best accommodated in larger tubes, with diameters in the range 10.5-12 A. The dynamics at room temperature showed that, as the amphiphile moves to the hollow cage, water molecules are dragged together, thereby promoting the nanotube filling. The resulting densities of filled SWNT are in agreement with measured densities.

Charge Transfer from Carbon Nanotubes to Silicon in Flexible Carbon Nanotube/Silicon Solar Cells.

PubMed

Li, Xiaokai; Mariano, Marina; McMillon-Brown, Lyndsey; Huang, Jing-Shun; Sfeir, Matthew Y; Reed, Mark A; Jung, Yeonwoong; Taylor, André D

2017-12-01

Mechanical fragility and insufficient light absorption are two major challenges for thin flexible crystalline Si-based solar cells. Flexible hybrid single-walled carbon nanotube (SWNT)/Si solar cells are demonstrated by applying scalable room-temperature processes for the fabrication of solar-cell components (e.g., preparation of SWNT thin films and SWNT/Si p-n junctions). The flexible SWNT/Si solar cells present an intrinsic efficiency ≈7.5% without any additional light-trapping structures. By using these solar cells as model systems, the charge transport mechanisms at the SWNT/Si interface are investigated using femtosecond transient absorption. Although primary photon absorption occurs in Si, transient absorption measurements show that SWNTs also generate and inject excited charge carriers to Si. Such effects can be tuned by controlling the thickness of the SWNTs. Findings from this study could open a new pathway for designing and improving the efficiency of photocarrier generation and absorption for high-performance ultrathin hybrid SWNT/Si solar cells. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Extracting the field-effect mobilities of random semiconducting single-walled carbon nanotube networks: A critical comparison of methods

NASA Astrophysics Data System (ADS)

Schießl, Stefan P.; Rother, Marcel; Lüttgens, Jan; Zaumseil, Jana

2017-11-01

The field-effect mobility is an important figure of merit for semiconductors such as random networks of single-walled carbon nanotubes (SWNTs). However, owing to their network properties and quantum capacitance, the standard models for field-effect transistors cannot be applied without modifications. Several different methods are used to determine the mobility with often very different results. We fabricated and characterized field-effect transistors with different polymer-sorted, semiconducting SWNT network densities ranging from low (≈6 μm-1) to densely packed quasi-monolayers (≈26 μm-1) with a maximum on-conductance of 0.24 μS μm-1 and compared four different techniques to evaluate the field-effect mobility. We demonstrate the limits and requirements for each method with regard to device layout and carrier accumulation. We find that techniques that take into account the measured capacitance on the active device give the most reliable mobility values. Finally, we compare our experimental results to a random-resistor-network model.

Identifying and counting point defects in carbon nanotubes.

PubMed

Fan, Yuwei; Goldsmith, Brett R; Collins, Philip G

2005-12-01

The prevailing conception of carbon nanotubes and particularly single-walled carbon nanotubes (SWNTs) continues to be one of perfectly crystalline wires. Here, we demonstrate a selective electrochemical method that labels point defects and makes them easily visible for quantitative analysis. High-quality SWNTs are confirmed to contain one defect per 4 microm on average, with a distribution weighted towards areas of SWNT curvature. Although this defect density compares favourably to high-quality, silicon single-crystals, the presence of a single defect can have tremendous electronic effects in one-dimensional conductors such as SWNTs. We demonstrate a one-to-one correspondence between chemically active point defects and sites of local electronic sensitivity in SWNT circuits, confirming the expectation that individual defects may be critical to understanding and controlling variability, noise and chemical sensitivity in SWNT electronic devices. By varying the SWNT synthesis technique, we further show that the defect spacing can be varied over orders of magnitude. The ability to detect and analyse point defects, especially at very low concentrations, indicates the promise of this technique for quantitative process analysis, especially in nanoelectronics development.

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...

Filling of single-walled carbon nanotubes by CuI nanocrystals via capillary technique

NASA Astrophysics Data System (ADS)

Chernysheva, M. V.; Eliseev, A. A.; Lukashin, A. V.; Tretyakov, Yu. D.; Savilov, S. V.; Kiselev, N. A.; Zhigalina, O. M.; Kumskov, A. S.; Krestinin, A. V.; Hutchison, J. L.

2007-03-01

The present study is focused on the synthesis and investigation of the nanocomposite CuI@SWNT obtained by the filling of metallic single-walled carbon nanotubes (SWNTs) (inner diameter 1-1.4 nm) by wide-gap semiconducting CuI nanocrystals using so-called capillary technique. The method is based on the impregnation of pre-opened SWNTs by molten CuI in vacuum with subsequent slow cooling to room temperature. SWNTs and CuI@SWNT nanocomposites were studied by nitrogen capillary adsorption method, EDX microanalysis, HRTEM microscopy and Raman spectroscopy. The changing of electronic properties of CuI@SWNT as compare to row nanotubes was observed.

Fluorescent single walled nanotube/silica composite materials

DOEpatents

Dattelbaum, Andrew M.; Gupta, Gautam; Duque, Juan G.; Doorn, Stephen K.; Hamilton, Christopher E.; DeFriend Obrey, Kimberly A.

2013-03-12

Fluorescent composites of surfactant-wrapped single-walled carbon nanotubes (SWNTs) were prepared by exposing suspensions of surfactant-wrapped carbon nanotubes to tetramethylorthosilicate (TMOS) vapor. Sodium deoxycholate (DOC) and sodium dodecylsulphate (SDS) were the surfactants. No loss in emission intensity was observed when the suspension of DOC-wrapped SWNTs were exposed to the TMOS vapors, but about a 50% decrease in the emission signal was observed from the SDS-wrapped SWNTs nanotubes. The decrease in emission was minimal by buffering the SDS/SWNT suspension prior to forming the composite. Fluorescent xerogels were prepared by adding glycerol to the SWNT suspensions prior to TMOS vapor exposure, followed by drying the gels. Fluorescent aerogels were prepared by replacing water in the gels with methanol and then exposing them to supercritical fluid drying conditions. The aerogels can be used for gas sensing.

Novel Materials Containing Single-Wall Carbon Nanotubes Wrapped in Polymer Molecules

NASA Technical Reports Server (NTRS)

Smalley, Richard E.; O'Connell, Michael J.; Smith, Kenneth; Colbert, Daniel T.

2009-01-01

In this design, single-wall carbon nanotubes (SWNTs) have been coated in polymer molecules to create a new type of material that has low electrical conductivity, but still contains individual nanotubes, and small ropes of individual nanotubes, which are themselves good electrical conductors and serve as small conducting rods immersed in an electrically insulating matrix. The polymer is attached through weak chemical forces that are primarily non-covalent in nature, caused primarily through polarization rather than the sharing of valence electrons. Therefore, the electronic structure of the SWNT involved is substantially the same as that of free, individual (and small ropes of) SWNT. Their high conductivity makes the individual nanotubes extremely electrically polarizable, and materials containing these individual, highly polarizable molecules exhibit novel electrical properties including a high dielectric constant.

Carbon nanotube materials for hydrogen storage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dillon, A.C.; Parilla, P.A.; Jones, K.M.

1998-08-01

Carbon single-wall nanotubes (SWNTs) are essentially elongated pores of molecular dimensions and are capable of adsorbing hydrogen at relatively high temperatures and low pressures. This behavior is unique to these materials and indicates that SWNTs are the ideal building block for constructing safe, efficient, and high energy density adsorbents for hydrogen storage applications. In past work the authors developed methods for preparing and opening SWNTs, discovered the unique adsorption properties of these new materials, confirmed that hydrogen is stabilized by physical rather than chemical interactions, measured the strength of interaction to be {approximately} 5 times higher than for adsorption onmore » planar graphite, and performed infrared absorption spectroscopy to determine the chemical nature of the surface terminations before, during, and after oxidation. This year the authors have made significant advances in synthesis and characterization of SWNT materials so that they can now prepare gram quantities of high-purity SWNT samples and measure and control the diameter distribution of the tubes by varying key parameters during synthesis. They have also developed methods which purify nanotubes and cut nanotubes into shorter segments. These capabilities provide a means for opening the tubes which were unreactive to the oxidation methods that successfully opened tubes, and offer a path towards organizing nanotube segments to enable high volumetric hydrogen storage densities. They also performed temperature programmed desorption spectroscopy on high purity carbon nanotube material obtained from collaborator Prof. Patrick Bernier and finished construction of a high precision Seivert`s apparatus which will allow the hydrogen pressure-temperature-composition phase diagrams to be evaluated for SWNT materials.« less

Single-Walled Carbon Nanotubes Modulate the B- to A-DNA Transition

PubMed Central

2015-01-01

We study the conformational equilibrium between B-to-A forms of ds-DNA adsorbed onto a single-walled carbon nanotube (SWNT) using free energy profile calculations based on all-atom molecular dynamics simulations. The potential of mean force (PMF) of the B-to-A transition of ds-DNA in the presence of an uncharged (10,0) carbon nanotube for two dodecamers with poly-AT or poly-GC sequences is calculated as a function of a root-mean-square-distance (ΔRMSD) difference metric for the B-to-A transition. The calculations reveal that in the presence of a SWNT DNA favors B-form DNA significantly in both poly-GC and poly-AT sequences. Furthermore, the poly-AT DNA:SWNT complex shows a higher energy penalty for adopting an A-like conformation than poly-GC DNA:SWNT by several kcal/mol. The presence of a SWNT on either poly-AT or poly-GC DNA affects the PMF of the transition such that the B form is favored by as much as 10 kcal/mol. In agreement with published data, we find a potential energy minimum between A and B-form DNA at ΔRMSD ≈ −1.5 Å and that the presence of the SWNT moves this minimum by as much as ΔRMSD = 3 Å. PMID:25553205

Multiscale Modeling of Carbon Nanotube-Epoxy Nanocomposites

NASA Astrophysics Data System (ADS)

Fasanella, Nicholas A.

Epoxy-composites are widely used in the aerospace industry. In order to improve upon stiffness and thermal conductivity; carbon nanotube additives to epoxies are being explored. This dissertation presents multiscale modeling techniques to study the engineering properties of single walled carbon nanotube (SWNT)-epoxy nanocomposites, consisting of pristine and covalently functionalized systems. Using Molecular Dynamics (MD), thermomechanical properties were calculated for a representative polymer unit cell. Finite Element (FE) and orientation distribution function (ODF) based methods were used in a multiscale framework to obtain macroscale properties. An epoxy network was built using the dendrimer growth approach. The epoxy model was verified by matching the experimental glass transition temperature, density, and dilatation. MD, via the constant valence force field (CVFF), was used to explore the mechanical and dilatometric effects of adding pristine and functionalized SWNTs to epoxy. Full stiffness matrices and linear coefficient of thermal expansion vectors were obtained. The Green-Kubo method was used to investigate the thermal conductivity as a function of temperature for the various nanocomposites. Inefficient phonon transport at the ends of nanotubes is an important factor in the thermal conductivity of the nanocomposites, and for this reason discontinuous nanotubes were modeled in addition to long nanotubes. To obtain continuum-scale elastic properties from the MD data, multiscale modeling was considered to give better control over the volume fraction of nanotubes, and investigate the effects of nanotube alignment. Two methods were considered; an FE based method, and an ODF based method. The FE method probabilistically assigned elastic properties of elements from the MD lattice results based on the desired volume fraction and alignment of the nanotubes. For the ODF method, a distribution function was generated based on the desired amount of nanotube alignment

Effects of single-walled carbon nanotubes on the bioavailability of PCBs in field-contaminated sediments

EPA Science Inventory

Adsorption of hydrophobic organic contaminants (HOCs) to black carbon is a well studied phenomenon. One emerging class of engineered black carbon materials are single-walled carbon nanotubes (SWNT). Little research has investigated the potential of SWNT to adsorb and sequester HO...

Surface tailored single walled carbon nanotubes as catalyst support for direct methanol fuel cell

NASA Astrophysics Data System (ADS)

Kireeti, Kota V. M. K.; Jha, Neetu

2017-10-01

A strategy for tuning the surface property of Single Walled Carbon Nanotubes (SWNTs) for enhanced methanol oxidation reaction (MOR) and oxygen reduction reaction (ORR) along with methanol tolerance is presented. The surface functionality is tailored using controlled acid and base treatment. Acid treatment leads to the attachment of carboxylic carbon (CC) fragments to SWNT making it hydrophilic (P3-SWNT). Base treatment of P3-SWNT with 0.05 M NaOH reduces the CCs and makes it hydrophobic (P33-SWNT). Pt catalyst supported on the P3-SWNT possesses enhanced MOR whereas that supported on P33-SWNT not only enhances ORR kinetics but also possess good tolerance towards methanol oxidation as verified by the electrochemical technique.

The performance of fast-moving low-voltage electromechanical actuators based on single-walled carbon nanotubes and ionic liquids

NASA Astrophysics Data System (ADS)

Mukai, Ken; Asaka, Kinji; Hata, Kenji; Oike, Hideaki

2011-12-01

In this paper, we study the details of the mechanical and electrical properties of polymer-free single-walled carbon nanotube (SWNT) sheets containing different contents of ionic liquids (ILs). The polymer-free SWNT sheets were prepared by a previously reported finding that millimeter-long 'super-growth' carbon nanotubes (SG-SWNTs), produced by a water-assisted modified chemical vapor deposition (CVD) method, associate together tightly with ILs, affording a free-standing sheet with a superb conductivity. The Young's modulus, breaking strength and the electrical conductivity of the SG-SWNT sheet with 67 wt% 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMITFSI) showed large values, 0.63 GPa, 20 MPa, and 147 S cm-1, respectively, although it has large amounts of ILs. We also measure the frequency dependence of the displacement of the actuator composed of SG-SWNT sheets sandwiching an ionic-gel electrolyte layer (SG-SWNT actuator). At more than 50 wt% of EMITFSI content, the frequency response of the actuation of the SG-SWNT actuator is flat up to around 100 Hz. The results of the displacement measurements are discussed in relation to the mechanical and electrical properties of the SG-SWNT actuators.

Assessment of chemically separated carbon nanotubes for nanoelectronics.

PubMed

Zhang, Li; Zaric, Sasa; Tu, Xiaomin; Wang, Xinran; Zhao, Wei; Dai, Hongjie

2008-02-27

It remains an elusive goal to obtain high performance single-walled carbon-nanotube (SWNT) electronics such as field effect transistors (FETs) composed of single- or few-chirality SWNTs, due to broad distributions in as-grown materials. Much progress has been made by various separation approaches to obtain materials enriched in metal or semiconducting nanotubes or even in single chiralties. However, research in validating SWNT separations by electrical transport measurements and building functional electronic devices has been scarce. Here, we performed length, diameter, and chirality separation of DNA functionalized HiPco SWNTs by chromatography methods, and we characterized the chiralities by photoluminescence excitation spectroscopy, optical absorption spectroscopy, and electrical transport measurements. The use of these combined methods provided deeper insight to the degree of separation than either technique alone. Separation of SWNTs by chirality and diameter occurred at varying degrees that decreased with increasing tube diameter. This calls for new separation methods capable of metallicity or chirality separation of large diameter SWNTs (in the approximately 1.5 nm range) needed for high performance nanoelectronics. With most of the separated fractions enriched in semiconducting SWNTs, nanotubes placed in parallel in short-channel (approximately 200 nm) electrical devices fail to produce FETs with high on/off switching, indicating incomplete elimination of metallic species. In rare cases with a certain separated SWNT fraction, we were able to fabricate FET devices composed of small-diameter, chemically separated SWNTs in parallel, with high on-/off-current (I(on)/I(off)) ratios up to 105 owing to semiconducting SWNTs with only a few (n,m) chiralities in the fraction. This was the first time that chemically separated SWNTs were used for short channel, all-semiconducting SWNT electronics dominant by just a few (n,m)'s. Nevertheless, the results suggest that

Fabrication of all-carbon nanotube electronic devices on flexible substrates through CVD and transfer methods.

PubMed

Zou, Yuan; Li, Qunqing; Liu, Junku; Jin, Yuanhao; Qian, Qingkai; Jiang, Kaili; Fan, Shoushan

2013-11-13

SWNT thin films with different nanotube densities are fabricated by CVD while controlling the concentration of catalyst and growth time. Three layers of SWNT films are transferred to flexible substrates serving as electrodes and channel materials, respectively. All-carbon nanotube TFTs with an on/off ratio as high as 10(5) are obtained. Inverters are fabricated on top of the flexible substrates with symmetric input/output behavior. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Arrays of horizontal carbon nanotubes of controlled chirality grown using designed catalysts

NASA Astrophysics Data System (ADS)

Zhang, Shuchen; Kang, Lixing; Wang, Xiao; Tong, Lianming; Yang, Liangwei; Wang, Zequn; Qi, Kuo; Deng, Shibin; Li, Qingwen; Bai, Xuedong; Ding, Feng; Zhang, Jin

2017-02-01

The semiconductor industry is increasingly of the view that Moore’s law—which predicts the biennial doubling of the number of transistors per microprocessor chip—is nearing its end. Consequently, the pursuit of alternative semiconducting materials for nanoelectronic devices, including single-walled carbon nanotubes (SWNTs), continues. Arrays of horizontal nanotubes are particularly appealing for technological applications because they optimize current output. However, the direct growth of horizontal SWNT arrays with controlled chirality, that would enable the arrays to be adapted for a wider range of applications and ensure the uniformity of the fabricated devices, has not yet been achieved. Here we show that horizontal SWNT arrays with predicted chirality can be grown from the surfaces of solid carbide catalysts by controlling the symmetries of the active catalyst surface. We obtained horizontally aligned metallic SWNT arrays with an average density of more than 20 tubes per micrometre in which 90 per cent of the tubes had chiral indices of (12, 6), and semiconducting SWNT arrays with an average density of more than 10 tubes per micrometre in which 80 per cent of the nanotubes had chiral indices of (8, 4). The nanotubes were grown using uniform size Mo2C and WC solid catalysts. Thermodynamically, the SWNT was selectively nucleated by matching its structural symmetry and diameter with those of the catalyst. We grew nanotubes with chiral indices of (2m, m) (where m is a positive integer), the yield of which could be increased by raising the concentration of carbon to maximize the kinetic growth rate in the chemical vapour deposition process. Compared to previously reported methods, such as cloning, seeding and specific-structure-matching growth, our strategy of controlling the thermodynamics and kinetics offers more degrees of freedom, enabling the chirality of as-grown SWNTs in an array to be tuned, and can also be used to predict the growth conditions

Noble Metal Decoration and Alignment of Carbon Nanotubes in Carboxymethyl Cellulose

EPA Science Inventory

A facile microwave (MW) method is described that accomplishes alignment and decoration of noble metals on carbon nanotubes wrapped with carboxymethyl cellulose (CMC). Carbon nanotubes (CNTs) such as single-wall (SWNT), multi-wall (MWNT) and Buckminsterfullerene (C-60) were well ...

Single walled carbon nanotube-based stochastic resonance device with molecular self-noise source

NASA Astrophysics Data System (ADS)

Fujii, Hayato; Setiadi, Agung; Kuwahara, Yuji; Akai-Kasaya, Megumi

2017-09-01

Stochastic resonance (SR) is an intrinsic noise usage system for small-signal sensing found in various living creatures. The noise-enhanced signal transmission and detection system, which is probabilistic but consumes low power, has not been used in modern electronics. We demonstrated SR in a summing network based on a single-walled carbon nanotube (SWNT) device that detects small subthreshold signals with very low current flow. The nonlinear current-voltage characteristics of this SWNT device, which incorporated Cr electrodes, were used as the threshold level of signal detection. The adsorption of redox-active polyoxometalate molecules on SWNTs generated additional noise, which was utilized as a self-noise source. To form a summing network SR device, a large number of SWNTs were aligned parallel to each other between the electrodes, which increased the signal detection ability. The functional capabilities of the present small-size summing network SR device, which rely on dense nanomaterials and exploit intrinsic spontaneous noise at room temperature, offer a glimpse of future bio-inspired electronic devices.

Imaging active topological defects in carbon nanotubes

NASA Astrophysics Data System (ADS)

Suenaga, Kazu; Wakabayashi, Hideaki; Koshino, Masanori; Sato, Yuta; Urita, Koki; Iijima, Sumio

2007-06-01

A single-walled carbon nanotube (SWNT) is a wrapped single graphene layer, and its plastic deformation should require active topological defects-non-hexagonal carbon rings that can migrate along the nanotube wall. Although in situ transmission electron microscopy (TEM) has been used to examine the deformation of SWNTs, these studies deal only with diameter changes and no atomistic mechanism has been elucidated experimentally. Theory predicts that some topological defects can form through the Stone-Wales transformation in SWNTs under tension at 2,000 K, and could act as a dislocation core. We demonstrate here, by means of high-resolution (HR)-TEM with atomic sensitivity, the first direct imaging of pentagon-heptagon pair defects found in an SWNT that was heated at 2,273 K. Moreover, our in situ HR-TEM observation reveals an accumulation of topological defects near the kink of a deformed nanotube. This result suggests that dislocation motions or active topological defects are indeed responsible for the plastic deformation of SWNTs.

Interaction of single-walled carbon nanotubes with poly(propyl ether imine) dendrimers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jayamurugan, G.; Rajesh, Y. B. R. D.; Jayaraman, N.

2011-03-14

We study the complexation of nontoxic, native poly(propyl ether imine) dendrimers with single-walled carbon nanotubes (SWNTs). The interaction was monitored by measuring the quenching of inherent fluorescence of the dendrimer. The dendrimer-nanotube binding also resulted in the increased electrical resistance of the hole doped SWNT, due to charge-transfer interaction between dendrimer and nanotube. This charge-transfer interaction was further corroborated by observing a shift in frequency of the tangential Raman modes of SWNT. We also report the effect of acidic and neutral pH conditions on the binding affinities. Experimental studies were supplemented by all atom molecular dynamics simulations to provide amore » microscopic picture of the dendrimer-nanotube complex. The complexation was achieved through charge transfer and hydrophobic interactions, aided by multitude of oxygen, nitrogen, and n-propyl moieties of the dendrimer.« less

Field Enhancement Properties of Nanotubes in a Field Emission Set-Up

NASA Technical Reports Server (NTRS)

Adessi, Ch.; Devel, M.

2001-01-01

This slide presentation reviews the mechanisms of emission of nanotubes. The field enhancement properties of carbon nanotubes, involved in the emission of electrons, is investigated theoretically for various single-wall (SWNT) and multi-wall nanotubes (MWNT). The presentation points out big differences between (n,0) and (n,n) nanotubes, and propose phenomenological laws for the variations of the enhancement factor with length and diameter

Graphene-carbon nanotube composite aerogel for selective detection of uric acid

NASA Astrophysics Data System (ADS)

Zhang, Feifei; Tang, Jie; Wang, Zonghua; Qin, Lu-Chang

2013-12-01

Graphene and single-walled carbon nanotube (SWNT) composite aerogel has been prepared by hydrothermal synthesis. The restacking of graphene is effectively reduced by SWNTs inserted in between graphene layers in order to make available more active sites and reactive surface area. Electrochemical experiments show that the graphene-SWNT composite electrode has superior catalytic performance in selective detection of uric acid (UA).

Tin-oxide-coated single-walled carbon nanotube bundles supporting platinum electrocatalysts for direct ethanol fuel cells.

PubMed

Hsu, Ryan S; Higgins, Drew; Chen, Zhongwei

2010-04-23

Novel tin-oxide (SnO(2))-coated single-walled carbon nanotube (SWNT) bundles supporting platinum (Pt) electrocatalysts for ethanol oxidation were developed for direct ethanol fuel cells. SnO(2)-coated SWNT (SnO(2)-SWNT) bundles were synthesized by a simple chemical-solution route. SnO(2)-SWNT bundles supporting Pt (Pt/SnO(2)-SWNTs) electrocatalysts and SWNT-supported Pt (Pt/SWNT) electrocatalysts were prepared by an ethylene glycol reduction method. The catalysts were physically characterized using TGA, XRD and TEM and electrochemically evaluated through cyclic voltammetry experiments. The Pt/SnO(2)-SWNTs showed greatly enhanced electrocatalytic activity for ethanol oxidation in acid medium, compared to the Pt/SWNT. The optimal SnO(2) loading of Pt/SnO(2)-SWNT catalysts with respect to specific catalytic activity for ethanol oxidation was also investigated.

Elastomer Filled With Single-Wall Carbon Nanotubes

NASA Technical Reports Server (NTRS)

Files, Bradley S.; Forest, Craig R.

2004-01-01

Experiments have shown that composites of a silicone elastomer with single-wall carbon nanotubes (SWNTs) are significantly stronger and stiffer than is the unfilled elastomer. The large strengthening and stiffening effect observed in these experiments stands in contrast to the much smaller strengthening effect observed in related prior efforts to reinforce epoxies with SWNTs and to reinforce a variety of polymers with multiple-wall carbon nanotubes (MWNTs). The relative largeness of the effect in the case of the silicone-elastomer/SWNT composites appears to be attributable to (1) a better match between the ductility of the fibers and the elasticity of the matrix and (2) the greater tensile strengths of SWNTs, relative to MWNTs. For the experiments, several composites were formulated by mixing various proportions of SWNTs and other filling materials into uncured RTV-560, which is a silicone adhesive commonly used in aerospace applications. Specimens of a standard "dog-bone" size and shape for tensile testing were made by casting the uncured elastomer/filler mixtures into molds, curing the elastomer, then pressing the specimens from a "cookie-cutter" die. The results of tensile tests of the specimens showed that small percentages of SWNT filler led to large increases in stiffness and tensile strength, and that these increases were greater than those afforded by other fillers. For example, the incorporation of SWNTs in a proportion of 1 percent increased the tensile strength by 44 percent and the modulus of elasticity (see figure) by 75 percent. However, the relative magnitudes of the increases decreased with increasing nanotube percentages because more nanotubes made the elastomer/nanotube composites more brittle. At an SWNT content of 10 percent, the tensile strength and modulus of elasticity were 125 percent and 562 percent, respectively, greater than the corresponding values for the unfilled elastomer.

Ultraclean individual suspended single-walled carbon nanotube field effect transistor

NASA Astrophysics Data System (ADS)

Liu, Siyu; Zhang, Jian; Nshimiyimana, Jean Pierre; Chi, Xiannian; Hu, Xiao; Wu, Pei; Liu, Jia; Wang, Gongtang; Sun, Lianfeng

2018-04-01

In this work, we report an effective technique of fabricating ultraclean individual suspended single-walled carbon nanotube (SWNT) transistors. The surface tension of molten silver is utilized to suspend an individual SWNT between a pair of Pd electrodes during annealing treatment. This approach avoids the usage and the residues of organic resist attached to SWNTs, resulting ultraclean SWNT devices. And the resistance per micrometer of suspended SWNTs is found to be smaller than that of non-suspended SWNTs, indicating the effect of the substrate on the electrical properties of SWNTs. The ON-state resistance (˜50 kΩ), mobility of 8600 cm2 V-1 s-1 and large on/off ratio (˜105) of semiconducting suspended SWNT devices indicate its advantages and potential applications.

Chirality Characterization of Dispersed Single Wall Carbon Nanotubes

NASA Technical Reports Server (NTRS)

Namkung, Min; Williams, Phillip A.; Mayweather, Candis D.; Wincheski, Buzz; Park, Cheol; Namkung, Juock S.

2005-01-01

Raman scattering and optical absorption spectroscopy are used for the chirality characterization of HiPco single wall carbon nanotubes (SWNTs) dispersed in aqueous solution with the surfactant sodium dodecylbenzene sulfonate. Radial breathing mode (RBM) Raman peaks for semiconducting and metallic SWNTs are identified by directly comparing the Raman spectra with the Kataura plot. The SWNT diameters are calculated from these resonant peak positions. Next, a list of (n, m) pairs, yielding the SWNT diameters within a few percent of that obtained from each resonant peak position, is established. The interband transition energies for the list of SWNT (n, m) pairs are calculated based on the tight binding energy expression for each list of the (n, m) pairs, and the pairs yielding the closest values to the corresponding experimental optical absorption peaks are selected. The results reveal that (1, 11), (4, 11), and (0, 11) as the most probable chiralities of the semiconducting nanotubes. The results also reveal that (4, 16), (6, 12) and (8, 8) are the most probable chiralities for the metallic nanotubes. Directly relating the Raman scattering data to the optical absorption spectra, the present method is considered the simplest technique currently available. Another advantage of this technique is the use of the E(sup 8)(sub 11) peaks in the optical absorption spectrum in the analysis to enhance the accuracy in the results.

Enhancement of ambipolar characteristics in single-walled carbon nanotubes using C{sub 60} and fabrication of logic gates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, Steve; Nam, Ji Hyun; Koo, Ja Hoon

2015-03-09

We demonstrate a technique to convert p-type single-walled carbon nanotube (SWNT) network transistor into ambipolar transistor by thermally evaporating C{sub 60} on top. The addition of C{sub 60} was observed to have two effects in enhancing ambipolar characteristics. First, C{sub 60} served as an encapsulating layer that enhanced the ambipolar characteristics of SWNTs. Second, C{sub 60} itself served as an electron transporting layer that contributed to the n-type conduction. Such a dual effect enables effective conversion of p-type into ambipolar characteristics. We have fabricated inverters using our SWNT/C{sub 60} ambipolar transistors with gain as high as 24, along with adaptivemore » NAND and NOR logic gates.« less

Production of vertical arrays of small diameter single-walled carbon nanotubes

DOEpatents

Hauge, Robert H; Xu, Ya-Qiong

2013-08-13

A hot filament chemical vapor deposition method has been developed to grow at least one vertical single-walled carbon nanotube (SWNT). In general, various embodiments of the present invention disclose novel processes for growing and/or producing enhanced nanotube carpets with decreased diameters as compared to the prior art.

Characterization of single-walled carbon nanotubes for environmental implications

USGS Publications Warehouse

Agnihotri, S.; Rostam-Abadi, M.; Rood, M.J.

2004-01-01

Adsorption capacities of N2 and various organic vapors (methyl-ethyl ketone (MEK), toluene, and cyclohexane) on select electric-arc and HiPco produced single walled carbon nanotubes (SWNT) were measured at 77 and 298 K, respectively. The amount of N2 adsorbed on a SWNT sample depended on the sample purity, methodology, and on the sample age. Adsorption capacities of organic vapors (100-1000 ppm vol) on SWNT in humid conditions were much higher than those for microporous activated carbons. These results established a foundation for additional studies related to potential environmental applications of SWNT. The MEK adsorption capacities of samples EA95 and CVD80 and mesoporous tire-derived activated carbon in humid conditions were lower than in dry conditions. This is an abstract of a paper presented at the AIChE Annual Meeting (Austin, TX 11/7-12/2004).

Fabrication of ultralong and electrically uniform single-walled carbon nanotubes on clean substrates.

PubMed

Wang, Xueshen; Li, Qunqing; Xie, Jing; Jin, Zhong; Wang, Jinyong; Li, Yan; Jiang, Kaili; Fan, Shoushan

2009-09-01

We report the controlled growth of ultralong single-wall carbon nanotube (SWNT) arrays using an improved chemical vapor deposition strategy. Using ethanol or methane as the feed gas, monodispersed Fe-Mo as the catalyst, and a superaligned carbon nanotube (CNT) film as the catalyst supporting frame, ultralong CNTs over 18.5 cm long were grown on Si substrates. The growth rate of the CNTs was more than 40 mum/s. No catalyst-related residual material was found on the substrates due to the use of a CNT film as the catalyst supporting frame, facilitating any subsequent fabrication of SWNT-based devices. Electrical transport measurements indicated that the electrical characteristics along a single ultralong SWNT were uniform. We also found that maintaining a spatially homogeneous temperature during the growth process was a critical factor for obtaining constant electrical characteristics along the length of the ultralong SWNTs.

Fabrication de structures tridimensionnelles de nanocomposites polymeres charges de nanotubes de carbone a simple paroi

NASA Astrophysics Data System (ADS)

Laberge Lebel, Louis

-covalent functionalization of the nanotubes by zinc protoporphyrin IX molecule and high shear mixing using a three-roll mill. The incorporation of the C-SWNTs into the resin led to an increase of the viscosity and the apparition of a shear thinning behaviour, characterized by capillary viscometry. The nanocomposite UV-curing behavior is characterized under differential scanning calorimetry coupled with a UV source. A further adjustment of the shear thinning behavior using fumed silica enabled the UV-DW fabrication of microbeams. Mechanical characterization reveals significant increase in both strength (by ˜64%) and modulus (by more than 15 times). These mechanical enhancements are attributed to both the covalent and the non-covalent functionalizations of the C-SWNTs. Nanocomposite spring networks composed of three micro-coils fabricated using the UV-DW technique are mechanically tested under compression and show a rigidity of ˜11.5 mN/mm. A micro-coil is also deposited between two uneven electrodes and a 10-6 S/cm electrical conductivity is measured. Nanocomposite scaffold structures are also deposited using the UV-DW technique. This thesis also reports the fabrication of 3D micro structured beams reinforced with the C-SWNT/polymer nanocomposite by using an approach based on the infiltration of 3D microfluidic networks. The 3D microfluidic network is first fabricated by the direct-write assembly method, which consists of the robotized deposition of fugitive ink filaments on an epoxy substrate, forming a 3D micro structured scaffold. After encapsulating the 3D micro-scaffold structure with an epoxy resin, the fugitive ink is liquefied and removed, resulting in a 3D network of interconnected microchannels. This microfluidic network is then infiltrated by the C-SWNT/polyurethane nanocomposite and subsequently cured. The final samples consist of rectangular beams having a complex 3D-skeleton structure of C-SWNT/polyrner nanocomposite fibers, adapted to offer better performance under flexural

Charge calculation studies done on a single walled carbon nanotube using MOPAC

NASA Astrophysics Data System (ADS)

Negi, S.; Bhartiya, Vivek Kumar; Chaturvedi, S.

2018-04-01

Dipole symmetry of induced charges on DWNTs are required for their application as a nanomotor. Earlier a molecular dynamics analysis was performed for a double-walled carbon-nanotube based motor driven by an externally applied sinusoidally varying electric field. One of the ways to get such a system is chemical or end functionalization, which promises to accomplish this specific and rare configuration of the induced charges on the surface of the carbon nanotube (CNT). CNTs are also a promising system for attaching biomolecules for bio-related applications. In an earlier work, ab initio calculations were done to study the electronic and structural properties of the groups -COOH, -OH, -NH2 and -CONH2 functionalized to an (8, 0) SWNT. The systems were shown to have a very stable interaction with the CNTs. The exterior surface of the SWNT is found to be reactive to NH2 (amidogen). In this work, charge calculations are done on a CNT using MOPAC, which is a semi empirical quantum chemistry software package. As a first step, we calculate the effect of NH2 functionalization to a (5,0) SWNT of infinite length. The symmetric charge distribution of the bare SWNT is observed to be disturbed on addition of a single NH2 in the close proximity of the SWNT. A net positive and opposite charge is observed to be induced on the opposite sides of the nanotube circumference, which is, in turn, imperative for the nanomotor applications. The minimum and maximum value of the charge on any atom is observed to increase from - 0.3 to 0.6 and from - 0.3 to - 1.8 electronic charge as compared to the bare SWNT. This fluctuation of the surface charge to larger values than bare CNT, can be attributed to the coulomb repulsion between NH2 and the rest of the charge on the surface which results into minimizing the total energy of the system. No such opposite polarity of charges are observed on adding NH2 to each ring of the SWNT implying addition of a single amidogen to be the most appropriate

Special antitumor immune effects of laser immunotherapy with SWNT-GC

NASA Astrophysics Data System (ADS)

Zhou, Feifan; Song, Sheng; Chen, Wei R.

2014-02-01

In our previous work, we constructed a multifunction nano system SWNT-GC, which can synergize photothermal and immunological effects. To further improve the application of this system, we study the cytotoxicity of SWNT-GC and investigate the effects on malignant tumor therapy. Here, we selected the optimal concentration of GC and SWNTs for the stable SWNT-GC construction. No cytotoxicity was observed under the dose used in the experiments. Using mouse melanoma tumor model, Laser+SWNT-GC treatment resulted in a significant mice survival rate, there were no long-term survivors under other treatment. It is providing a promising treatment modality for the malignancy.

Influence of gamma irradiation on carbon nanotube-reinforced polypropylene.

PubMed

Castell, P; Medel, F J; Martinez, M T; Puértolas, J A

2009-10-01

Single walled carbon nanotubes (SWNT) have been incorporated into a polypropylene (PP) matrix in different concentrations (range: 0.25-2.5 wt%). The nanotubes were blended with PP particles (approximately 500 microm in size) before mixing in an extruder. Finally, rectangular plates were obtained by compression moulding. PP-SWNT composites were gamma irradiated at different doses, 10 and 20 kGy, to promote crosslinking in the matrix and potentially enhance the interaction between nanotubes and PP. Extensive thermal, structural and mechanical characterization was conducted by means of DSC, X-ray diffraction, Raman spectroscopy, uniaxial tensile tests and dynamic mechanical thermal (DMTA) techniques. DSC thermograms reflected higher crystallinity with increasing nanotube concentration. XRD analysis confirmed the only presence of a monoclinic crystals and proved unambiguously that CNTs generated a preferred orientation. Raman spectroscopy confirmed that the intercalation of the polymer between bundles is favored at low CNTs contents. Elastic modulus results confirmed the reinforcement of the polypropylene matrix with increasing SWNT concentration, although stiffness saturation was observed at the highest concentration. Loss tangent DMTA curves showed three transitions for raw polypropylene. While gamma relaxation remained practically unchanged in all the samples, beta relaxation temperatures showed an increase with increasing CNT content due to the reduced mobility of the system. Gamma-irradiated PP exhibited an increase in the beta relaxation temperature, associated with changes in glass transition due to radiation-induced crosslinking. On the contrary, gamma-irradiated nanocomposites did not show this effect probably due to the reaction of radiative free radicals with CNTs.

Nanohelices from planar polymer self-assembled in carbon nanotubes

PubMed Central

Fu, Hongjin; Xu, Shuqiong; Li, Yunfang

2016-01-01

The polymer possessing with planar structure can be activated and guided to encapsulate the inner space of SWNT and form a helix through van der Waals interaction and the π-π stacking effect between the polymer and the inner surface of SWNT. The SWNT size, the nanostructure and flexibility of polymer chain are all determine the final structures. The basic interaction between the polymer and the nanotubes is investigated, and the condition and mechanism of the helix-forming are explained particularly. Hybrid polymers improve the ability of the helix formation. This study provides scientific basis for fabricating helical polymers encapsulated in SWNTs and eventually on their applications in various areas. PMID:27440493

A theoretical study for mechanical contact between carbon nanotubes

NASA Astrophysics Data System (ADS)

Takagi, Yoshiteru; Uda, Tsuyoshi; Ohno, Takahisa

2005-03-01

We have theoretically investigated motions of single-walled carbon nanotubes (SWNTs) which are mounted on a flat substrate layer of SWNTs by tight-binding molecular dynamics simulations. One of the most interesting motions is the conversion of force and torque, where the force and torque acting initially on the mounted tube finally results in the lateral motion and rolling of the supporting tubes in the substrate. This motion is well understood in terms of the total energy surface of the SWNT/SWNT system. It is suggested that an undulation of the total energy surface plays a role as an atomic-scale gear tooth in the field of nanomechanics, in spite of the atomically smooth surface of SWNT.

Working Toward Nanotube Composites

NASA Technical Reports Server (NTRS)

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

2001-01-01

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

Scaled up Fabrication of High-Throughout SWNT Nanoelectronics and Nanosensor Devices

DTIC Science & Technology

2007-04-20

copolymer, polystyrene-block-ferrocenylethylmethylsilane (PS-b- PFEMS ) as the polymer-based catalyst for optimized SWNT growth. Spin coating a dilute...solution of 1 wt % PS-b- PFEMS in toluene provides uniform ~ 100nm thick films of the catalyst. In order to get well-separated individual SWNT or SWNT rope

Enhancement of high-resolution photoacoustic imaging with indocyanine green-conjugated carbon nanotubes

NASA Astrophysics Data System (ADS)

Phuc Nguyen, Van; Oh, Yunok; Ha, Kanglyeol; Oh, Junghwan; Kang, Hyun Wook

2015-07-01

The current study indicates the feasibility of photoacoustic imaging (PAI) enhanced with contrast agents. A single-element ultrasound transducer (20 MHz) was used to detect PA signals for image reconstruction. To improve PA sensitivity, single-walled carbon nanotubes (SWNTs) conjugated with indocyanine green (ICG) were injected into samples at various concentrations. PA signal amplitudes linearly increased with SWNT-ICG concentration owing to strong light absorption. Compared with SWNTs, SWNT-ICG augmented the signal intensity by approximately 2-fold (concentration: 300 nM). The enhanced optical absorption can allow the application of SWNT-ICG to enable PAI for specifically identifying tumors with high sensitivity.

Considerably improved photovoltaic performance of carbon nanotube-based solar cells using metal oxide layers.

PubMed

Wang, Feijiu; Kozawa, Daichi; Miyauchi, Yuhei; Hiraoka, Kazushi; Mouri, Shinichiro; Ohno, Yutaka; Matsuda, Kazunari

2015-02-18

Carbon nanotube-based solar cells have been extensively studied from the perspective of potential application. Here we demonstrated a significant improvement of the carbon nanotube solar cells by the use of metal oxide layers for efficient carrier transport. The metal oxides also serve as an antireflection layer and an efficient carrier dopant, leading to a reduction in the loss of the incident solar light and an increase in the photocurrent, respectively. As a consequence, the photovoltaic performance of both p-single-walled carbon nanotube (SWNT)/n-Si and n-SWNT/p-Si heterojunction solar cells using MoOx and ZnO layers is improved, resulting in very high photovoltaic conversion efficiencies of 17.0 and 4.0%, respectively. These findings regarding the use of metal oxides as multifunctional layers suggest that metal oxide layers could improve the performance of various electronic devices based on carbon nanotubes.

Considerably improved photovoltaic performance of carbon nanotube-based solar cells using metal oxide layers

NASA Astrophysics Data System (ADS)

Wang, Feijiu; Kozawa, Daichi; Miyauchi, Yuhei; Hiraoka, Kazushi; Mouri, Shinichiro; Ohno, Yutaka; Matsuda, Kazunari

2015-02-01

Carbon nanotube-based solar cells have been extensively studied from the perspective of potential application. Here we demonstrated a significant improvement of the carbon nanotube solar cells by the use of metal oxide layers for efficient carrier transport. The metal oxides also serve as an antireflection layer and an efficient carrier dopant, leading to a reduction in the loss of the incident solar light and an increase in the photocurrent, respectively. As a consequence, the photovoltaic performance of both p-single-walled carbon nanotube (SWNT)/n-Si and n-SWNT/p-Si heterojunction solar cells using MoOx and ZnO layers is improved, resulting in very high photovoltaic conversion efficiencies of 17.0 and 4.0%, respectively. These findings regarding the use of metal oxides as multifunctional layers suggest that metal oxide layers could improve the performance of various electronic devices based on carbon nanotubes.

Fibers comprised of epitaxially grown single-wall carbon nanotubes, and a method for added catalyst and continuous growth at the tip

DOEpatents

Kittrell, W. Carter; Wang, Yuhuang; Kim, Myung Jong; Hauge, Robert H.; Smalley, Richard E.; Marek leg, Irene Morin

2010-06-01

The present invention is directed to fibers of epitaxially grown single-wall carbon nanotubes (SWNTs) and methods of making same. Such methods generally comprise the steps of: (a) providing a spun SWNT fiber; (b) cutting the fiber substantially perpendicular to the fiber axis to yield a cut fiber; (c) etching the cut fiber at its end with a plasma to yield an etched cut fiber; (d) depositing metal catalyst on the etched cut fiber end to form a continuous SWNT fiber precursor; and (e) introducing feedstock gases under SWNT growth conditions to grow the continuous SWNT fiber precursor into a continuous SWNT fiber.

Single Wall Carbon Nanotube-polymer Solar Cells

NASA Technical Reports Server (NTRS)

Bailey, Sheila G.; Castro, Stephanie L.; Landi, Brian J.; Gennett, Thomas; Raffaelle, Ryne P.

2005-01-01

Investigation of single wall carbon nanotube (SWNT)-polymer solar cells has been conducted towards developing alternative lightweight, flexible devices for space power applications. Photovoltaic devices were constructed with regioregular poly(3-octylthiophene)-(P3OT) and purified, >95% w/w, laser-generated SWNTs. The P3OT composites were deposited on ITO-coated polyethylene terapthalate (PET) and I-V characterization was performed under simulated AM0 illumination. Fabricated devices for the 1.0% w/w SWNT-P3OT composites showed a photoresponse with an open-circuit voltage (V(sub oc)) of 0.98 V and a short-circuit current density (I(sub sc)) of 0.12 mA/sq cm. Optimization of carrier transport within these novel photovoltaic systems is proposed, specifically development of nanostructure-SWNT complexes to enhance exciton dissociation.

Pulmonary Toxicity of Carbon Nanotubes: Ethical Implications and Human Risk Assessment

NASA Technical Reports Server (NTRS)

James, John T.

2006-01-01

Presentation viewgraphs review the health considerations of working with and manufacturing Carbon Nanotubes. The inherent toxicity of Single Walled Carbon Nanotubes (SWNT) are reviewed, and how the preparation of the SWNTs are reviewed. The experimental protocol that was used is reviewed, and the results in lungs of rodents are shown. The presentation ends with posing the ethical questions in reference to the manufacture and use of carbon nanotubes.

Direct electron transfer of glucose oxidase on carbon nanotubes

NASA Astrophysics Data System (ADS)

Guiseppi-Elie, Anthony; Lei, Chenghong; Baughman, Ray H.

2002-10-01

In this report, exploitation of the unique properties of single-walled carbon nanotubes (SWNT) leads to the achievement of direct electron transfer with the redox active centres of adsorbed oxidoreductase enzymes. Flavin adenine dinucleotide (FAD), the redox active prosthetic group of flavoenzymes that catalyses important biological redox reactions and the flavoenzyme glucose oxidase (GOx), were both found to spontaneously adsorb onto carbon nanotube bundles. Both FAD and GOx were found to spontaneously adsorb to unannealed carbon nanotubes that were cast onto glassy carbon electrodes and to display quasi-reversible one-electron transfer. Similarly, GOx was found to spontaneously adsorb to annealed, single-walled carbon nanotube paper and to display quasi-reversible one-electron transfer. In particular, GOx immobilized in this way was shown, in the presence of glucose, to maintain its substrate-specific enzyme activity. It is believed that the tubular fibrils become positioned within tunnelling distance of the cofactors with little consequence to denaturation. The combination of SWNT with redox active enzymes would appear to offer an excellent and convenient platform for a fundamental understanding of biological redox reactions as well as the development of reagentless biosensors and nanobiosensors.

Complications pertaining to the detection and characterization of individual and embedded single walled carbon nanotubes by scanning electron microscopy

NASA Astrophysics Data System (ADS)

Orbaek, Alvin W.; Barron, Andrew R.

2013-03-01

Comparison of AFM and SEM images of single walled carbon nanotubes (SWNTs) grown within a dielectric matrix reveal subterranean nanotubes that are present within the matrix, and as such can be charge screened by the dielectric. Under adequate imaging conditions for the SWNT/silica sample the intensity of isolated nanotubes is found to be inversely proportional to the instrument dwell time (i.e., shorter dwell times were found to make SWNT intensities brighter). The threshold dwell time required to enable isolated tubes to be visible was found to be 10 μs moreover, the degree change in intensity was found to be nanotube specific, i.e., different SWNTs respond in a different manner at different dwell times. The results indicate that care should be taken when attempting to quantify number density and length distributions of SWNTs on or within a dielectric matrix.Comparison of AFM and SEM images of single walled carbon nanotubes (SWNTs) grown within a dielectric matrix reveal subterranean nanotubes that are present within the matrix, and as such can be charge screened by the dielectric. Under adequate imaging conditions for the SWNT/silica sample the intensity of isolated nanotubes is found to be inversely proportional to the instrument dwell time (i.e., shorter dwell times were found to make SWNT intensities brighter). The threshold dwell time required to enable isolated tubes to be visible was found to be 10 μs moreover, the degree change in intensity was found to be nanotube specific, i.e., different SWNTs respond in a different manner at different dwell times. The results indicate that care should be taken when attempting to quantify number density and length distributions of SWNTs on or within a dielectric matrix. Electronic supplementary information (ESI) available: Plots of SEM for cross over points, raw SEM images used for Fig. 5, and Fig. 6, SEM image of scattering centre, and SEM images with various scan directions at 10 μs dwell time. See DOI: 10.1039/c3

Carbon nanotubes as multifunctional biological transporters and near-infrared agents for selective cancer cell destruction

NASA Astrophysics Data System (ADS)

Nadine Wong Shi Kam,; O'Connell, Michael; Wisdom, Jeffrey A.; Dai, Hongjie

2005-08-01

Biological systems are known to be highly transparent to 700- to 1,100-nm near-infrared (NIR) light. It is shown here that the strong optical absorbance of single-walled carbon nanotubes (SWNTs) in this special spectral window, an intrinsic property of SWNTs, can be used for optical stimulation of nanotubes inside living cells to afford multifunctional nanotube biological transporters. For oligonucleotides transported inside living cells by nanotubes, the oligos can translocate into cell nucleus upon endosomal rupture triggered by NIR laser pulses. Continuous NIR radiation can cause cell death because of excessive local heating of SWNT in vitro. Selective cancer cell destruction can be achieved by functionalization of SWNT with a folate moiety, selective internalization of SWNTs inside cells labeled with folate receptor tumor markers, and NIR-triggered cell death, without harming receptor-free normal cells. Thus, the transporting capabilities of carbon nanotubes combined with suitable functionalization chemistry and their intrinsic optical properties can lead to new classes of novel nanomaterials for drug delivery and cancer therapy. Author contributions: N.W.S.K., M.O., and H.D. designed research; N.W.S.K., M.O., and J.A.W. performed research; N.W.S.K., M.O., and H.D. analyzed data; and N.W.S.K. and H.D. wrote the paper.This paper was submitted directly (Track II) to the PNAS office.Abbreviations: NIR, near-infrared; SWNT, single-walled carbon nanotube; AFM, atomic force microscopy; PL, phospholipid; PEG, polyethylene glycol; FA, folic acid; FR, folate receptor.

Electrical device fabrication from nanotube formations

DOEpatents

Nicholas, Nolan Walker; Kittrell, W. Carter; Kim, Myung Jong; Schmidt, Howard K.

2013-03-12

A method for forming nanotube electrical devices, arrays of nanotube electrical devices, and device structures and arrays of device structures formed by the methods. Various methods of the present invention allow creation of semiconducting and/or conducting devices from readily grown SWNT carpets rather than requiring the preparation of a patterned growth channel and takes advantage of the self-controlling nature of these carpet heights to ensure a known and controlled channel length for reliable electronic properties as compared to the prior methods.

Encapsulation of S/SWNT with PANI Web for Enhanced Rate and Cycle Performance in Lithium Sulfur Batteries

PubMed Central

Kim, Joo Hyun; Fu, Kun; Choi, Junghyun; Kil, Kichun; Kim, Jeonghyun; Han, Xiaogang; Hu, Liangbing; Paik, Ungyu

2015-01-01

Lithium-sulfur batteries show great potential to compete with lithium-ion batteries due to the fact that sulfur can deliver a high theoretical capacity of 1672 mAh/g and a high theoretical energy density of 2500 Wh/kg. But it has several problems to be solved in order to achieve high sulfur utilization with high Coulombic efficiency and long cycle life of Li-S batteries. These problems are mainly caused by the dissoluble polysulfide species, which are a series of complex reduced sulfur products, associating with shuttle effect between electrodes as well as side reactions on lithium metal anode. To alleviate these challenges, we developed a sulfur-carbon nanotube (S/SWNT) composite coated with polyaniline (PANI) polymer as polysulfide block to achieve high sulfur utilization, high Coulombic efficiency, and long cycle life. The PANI coated S/SWNT composite showed a superior specific capacity of 1011 mAh/g over 100 cycles and a good rate retention, demonstrating the synergic contribution of porous carbon and conducting polymer protection to address challenges underlying sulfur cathode. PMID:25752298

Carbon nanotubes as in vivo bacterial probes.

PubMed

Bardhan, Neelkanth M; Ghosh, Debadyuti; Belcher, Angela M

2014-09-17

With the rise in antibiotic-resistant infections, non-invasive sensing of infectious diseases is increasingly important. Optical imaging, although safer and simpler, is less developed than other modalities such as radioimaging, due to low availability of target-specific molecular probes. Here we report carbon nanotubes (SWNTs) as bacterial probes for fluorescence imaging of pathogenic infections. We demonstrate that SWNTs functionalized using M13 bacteriophage (M13-SWNT) can distinguish between F'-positive and F'-negative bacterial strains. Moreover, through one-step modification, we attach an anti-bacterial antibody on M13-SWNT, making it easily tunable for sensing specific F'-negative bacteria. We illustrate detection of Staphylococcus aureus intramuscular infections, with ~3.4 × enhancement in fluorescence intensity over background. SWNT imaging presents lower signal spread ~0.08 × and higher signal amplification ~1.4 × , compared with conventional dyes. We show the probe offers greater ~5.7 × enhancement in imaging of S. aureus infective endocarditis. These biologically functionalized, aqueous-dispersed, actively targeted, modularly tunable SWNT probes offer new avenues for exploration of deeply buried infections.

Carbon nanotubes as in vivo bacterial probes

NASA Astrophysics Data System (ADS)

Bardhan, Neelkanth M.; Ghosh, Debadyuti; Belcher, Angela M.

2014-09-01

With the rise in antibiotic-resistant infections, non-invasive sensing of infectious diseases is increasingly important. Optical imaging, although safer and simpler, is less developed than other modalities such as radioimaging, due to low availability of target-specific molecular probes. Here we report carbon nanotubes (SWNTs) as bacterial probes for fluorescence imaging of pathogenic infections. We demonstrate that SWNTs functionalized using M13 bacteriophage (M13-SWNT) can distinguish between F‧-positive and F‧-negative bacterial strains. Moreover, through one-step modification, we attach an anti-bacterial antibody on M13-SWNT, making it easily tunable for sensing specific F‧-negative bacteria. We illustrate detection of Staphylococcus aureus intramuscular infections, with ~3.4 × enhancement in fluorescence intensity over background. SWNT imaging presents lower signal spread ~0.08 × and higher signal amplification ~1.4 × , compared with conventional dyes. We show the probe offers greater ~5.7 × enhancement in imaging of S. aureus infective endocarditis. These biologically functionalized, aqueous-dispersed, actively targeted, modularly tunable SWNT probes offer new avenues for exploration of deeply buried infections.

Carbon Nanotubes as in vivo Bacterial Probes

PubMed Central

Bardhan, Neelkanth M.; Ghosh, Debadyuti; Belcher, Angela M.

2014-01-01

With the rise in antibiotic-resistant infections, noninvasive sensing of infectious diseases is increasingly important. Optical imaging, while safer and simpler, is less developed than other modalities like radioimaging; due to low availability of target-specific molecular probes. Here, we report carbon nanotubes (SWNTs) as bacterial probes for fluorescence imaging of pathogenic infections. We demonstrate that SWNTs functionalized using M13 bacteriophage (M13-SWNT) can distinguish between F'-positive and F'-negative bacterial strains. Moreover, through one-step modification, we attach an anti-bacterial antibody on M13-SWNT, making it easily tunable for sensing specific F’-negative bacteria. We illustrate detection of Staphylococcus aureus intramuscular infections, with ~3.4× enhancement in fluorescence intensity over background. SWNT imaging presents lower signal spread ~0.08×, and higher signal amplification ~1.4×, compared to conventional dyes. We show the probe offers greater ~5.7× enhancement in imaging of S. aureus infective endocarditis. These biologically-functionalized, aqueous-dispersed, actively-targeted, modularly-tunable SWNT probes offer new avenues for exploration of deeply-buried infections. PMID:25230005

General synthesis of inorganic single-walled nanotubes

PubMed Central

Ni, Bing; Liu, Huiling; Wang, Peng-peng; He, Jie; Wang, Xun

2015-01-01

The single-walled nanotube (SWNT) is an interesting nanostructure for fundamental research and potential applications. However, very few inorganic SWNTs are available to date due to the lack of efficient fabrication methods. Here we synthesize four types of SWNT: sulfide; hydroxide; phosphate; and polyoxometalate. Each type of SWNT possesses essentially uniform diameters. Detailed studies illustrate that the formation of SWNTs is initiated by the self-coiling of the corresponding ultrathin nanostructure embryo/building blocks on the base of weak interactions between them, which is not limited to specific compounds or crystal structures. The interactions between building blocks can be modulated by varying the solvents used, thus multi-walled tubes can also be obtained. Our results reveal that the generalized synthesis of inorganic SWNTs can be achieved by the self-coiling of ultrathin building blocks under the proper weak interactions. PMID:26510862

Fabrication and flow characterization of vertically aligned carbon-nanotube/polymer membranes

NASA Astrophysics Data System (ADS)

Castellano, Richard; Meshot, Eric; Fornasiero, Francesco; Shan, Jerry

2017-11-01

Membranes with well-controlled nanopores are of interest for applications as diverse as chemical separations, water purification, and ``green'' power generation. In particular, membranes incorporating carbon nanotubes (CNTs) as through-pores have been shown to pass fluids at rates orders-of-magnitude faster than predicted by continuum theory. However, cost-effective and scalable solutions for fabricating such membranes are still an area of research. We describe a solution-based fabrication technique for creating polymer composite membranes from bulk nanotubes using electric-field alignment and electrophoretic concentration. We then focus on flow characterization of membranes with single-wall nanotube (SWNT) pores. We demonstrate membrane quality by size-exclusion testing and showing that the flowrate of different gasses scales as the square root of molecular weight. The gas flowrates and moisture-vapor-transmission rates are compared with theoretical predictions and with composite membranes -fabricated from CVD-grown SWNT arrays. Funded by DTRA Grant BA12PHM123.

Dissecting single-molecule signal transduction in carbon nanotube circuits with protein engineering

PubMed Central

Choi, Yongki; Olsen, Tivoli J.; Sims, Patrick C.; Moody, Issa S.; Corso, Brad L.; Dang, Mytrang N.; Weiss, Gregory A.; Collins, Philip G.

2013-01-01

Single molecule experimental methods have provided new insights into biomolecular function, dynamic disorder, and transient states that are all invisible to conventional measurements. A novel, non-fluorescent single molecule technique involves attaching single molecules to single-walled carbon nanotube field-effective transistors (SWNT FETs). These ultrasensitive electronic devices provide long-duration, label-free monitoring of biomolecules and their dynamic motions. However, generalization of the SWNT FET technique first requires design rules that can predict the success and applicability of these devices. Here, we report on the transduction mechanism linking enzymatic processivity to electrical signal generation by a SWNT FET. The interaction between SWNT FETs and the enzyme lysozyme was systematically dissected using eight different lysozyme variants synthesized by protein engineering. The data prove that effective signal generation can be accomplished using a single charged amino acid, when appropriately located, providing a foundation to widely apply SWNT FET sensitivity to other biomolecular systems. PMID:23323846

Photo-nano immunotherapy for metastatic breast cancer using synergistic single-walled carbon nanotubes and glycated chitosan

NASA Astrophysics Data System (ADS)

Zhou, Feifan; Hasanjee, Aamr; Doughty, Austin; West, Connor; Liu, Hong; Chen, Wei R.

2015-03-01

In our previous work, we constructed a multifunctional nano system, using single-walled carbon nanotube (SWNT) and glycated chitosan (GC), which can synergize photothermal and immunological effects. To further confirm the therapy efficacy, with a metastatic mouse mammary tumor model (4T1), we investigate the therapy effects and immune response induced by SWNT-GC, under laser irradiation. Laser+SWNT-GC treatment not only suppressed the prime tumor, but also induced antitumor immune response. It could be developed into a promising treatment modality for the metastatic breast cancer.

Single-Walled Carbon Nanotube-Based Near-Infrared Optical Glucose Sensors toward In Vivo Continuous Glucose Monitoring

PubMed Central

Yum, Kyungsuk; McNicholas, Thomas P.; Mu, Bin; Strano, Michael S.

2013-01-01

This article reviews research efforts on developing single-walled carbon nanotube (SWNT)-based near-infrared (NIR) optical glucose sensors toward long-term in vivo continuous glucose monitoring (CGM). We first discuss the unique optical properties of SWNTs and compare SWNTs with traditional organic and nanoparticle fluorophores regarding in vivo glucose-sensing applications. We then present our development of SWNT-based glucose sensors that use glucose-binding proteins and boronic acids as a high-affinity molecular receptor for glucose and transduce binding events on the receptors to modulate SWNT fluorescence. Finally, we discuss opportunities and challenges in translating the emerging technology of SWNT-based NIR optical glucose sensors into in vivo CGM for practical clinical use. PMID:23439162

Mechanisms of single-walled carbon nanotube nucleation, growth, and healing determined using QM/MD methods.

PubMed

Page, Alister J; Ohta, Yasuhito; Irle, Stephan; Morokuma, Keiji

2010-10-19

Since their discovery in the early 1990s, single-walled carbon nanotubes (SWNTs) have spawned previously unimaginable commercial and industrial technologies. Their versatility stems from their unique electronic, physical/chemical, and mechanical properties, which set them apart from traditional materials. Many researchers have investigated SWNT growth mechanisms in the years since their discovery. The most prevalent of these is the vapor-liquid-solid (VLS) mechanism, which is based on experimental observations. Within the VLS mechanism, researchers assume that the formation of a SWNT starts with co-condensation of carbon and metal atoms from vapor to form liquid metal carbide. Once the liquid reaches supersaturation, the solid phase nanotubes begin to grow. The growth process is partitioned into three distinct stages: nucleation of a carbon "cap-precursor," "cap-to-tube" transformation, and continued SWNT growth. In recent years, molecular dynamics (MD) simulations have come to the fore with respect to SWNT growth. MD simulations lead to spatial and temporal resolutions of these processes that are superior to those possible using current experimental techniques, and so provide valuable information regarding the growth process that researchers cannot obtain experimentally. In this Account, we review our own recent efforts to simulate SWNT nucleation, growth, and healing phenomena on transition-metal catalysts using quantum mechanical molecular dynamics (QM/MD) methods. In particular, we have validated each stage of the SWNT condensation mechanism using a self-consistent-charge density-functional tight-binding (SCC-DFTB) methodology. With respect to the nucleation of a SWNT cap-precursor (stage 1), we have shown that the presence of a transition-metal carbide particle is not a necessary prerequisite for SWNT nucleation, contrary to conventional experimental presumptions. The formation and coalescence of polyyne chains on the metal surface occur first, followed by the

Capture of unstable protein complex on the streptavidin-coated single-walled carbon nanotubes

NASA Astrophysics Data System (ADS)

Liu, Zunfeng; Voskamp, Patrick; Zhang, Yue; Chu, Fuqiang; Abrahams, Jan Pieter

2013-04-01

Purification of unstable protein complexes is a bottleneck for investigation of their 3D structure and in protein-protein interaction studies. In this paper, we demonstrate that streptavidin-coated single-walled carbon nanotubes (Strep•SWNT) can be used to capture the biotinylated DNA- EcoRI complexes on a 2D surface and in solution using atomic force microscopy and electrophoresis analysis, respectively. The restriction enzyme EcoRI forms unstable complexes with DNA in the absence of Mg2+. Capturing the EcoRI-DNA complexes on the Strep•SWNT succeeded in the absence of Mg2+, demonstrating that the Strep•SWNT can be used for purifying unstable protein complexes.

Phonon Dispersion in Chiral Single-Wall Carbon Nanotubes

NASA Astrophysics Data System (ADS)

Mu, Weihua; Vamivakas, Anthony Nickolas; Fang, Yan; Wang, Bolin

The method to obtain phonon dispersion of achiral single-wall carbon nanotubes (SWNTs) from 6×6 matrix proposed by Mahan and Jeon7 has been extended to chiral SWNTs. The number of calculated phonon modes of a chiral SWNT (10, 1) is much larger than that of a zigzag one (10, 0) because the number of atoms in the translational unit cell of chiral SWNT is larger than that of an achiral one even though they have relative similar radius. The possible application of our approach to other models with more phonon potential terms beyond Mahan and Jeon's model is discussed.

Dry contact transfer printing of aligned carbon nanotube patterns and characterization of their optical properties for diameter distribution and alignment.

PubMed

Pint, Cary L; Xu, Ya-Qiong; Moghazy, Sharief; Cherukuri, Tonya; Alvarez, Noe T; Haroz, Erik H; Mahzooni, Salma; Doorn, Stephen K; Kono, Junichiro; Pasquali, Matteo; Hauge, Robert H

2010-02-23

A scalable and facile approach is demonstrated where as-grown patterns of well-aligned structures composed of single-walled carbon nanotubes (SWNT) synthesized via water-assisted chemical vapor deposition (CVD) can be transferred, or printed, to any host surface in a single dry, room-temperature step using the growth substrate as a stamp. We demonstrate compatibility of this process with multiple transfers for large-scale device and specifically tailored pattern fabrication. Utilizing this transfer approach, anisotropic optical properties of the SWNT films are probed via polarized absorption, Raman, and photoluminescence spectroscopies. Using a simple model to describe optical transitions in the large SWNT species present in the aligned samples, polarized absorption data are demonstrated as an effective tool for accurate assignment of the diameter distribution from broad absorption features located in the infrared. This can be performed on either well-aligned samples or unaligned doped samples, allowing simple and rapid feedback of the SWNT diameter distribution that can be challenging and time-consuming to obtain in other optical methods. Furthermore, we discuss challenges in accurately characterizing alignment in structures of long versus short carbon nanotubes through optical techniques, where SWNT length makes a difference in the information obtained in such measurements. This work provides new insight to the efficient transfer and optical properties of an emerging class of long, large diameter SWNT species typically produced in the CVD process.

Exploring the Chemical Sensitivity of a Carbon Nanotube/Green Tea Composite

PubMed Central

Chen, Yanan; Lee, Yang Doo; Vedala, Harindra; Allen, Brett L.; Star, Alexander

2010-01-01

Single-walled carbon nanotubes (SWNTs) possess unique electronic and physical properties, which make them very attractive for a wide range of applications. In particular, SWNTs and their composites have shown a great potential for chemical and biological sensing. Green tea, or more specifically its main antioxidant component, epigallocatechin gallate (EGCG), has been found to disperse SWNTs in water. However, the chemical sensitivity of this SWNT/green tea (SWNT/EGCG) composite remained unexplored. With EGCG present, this SWNT composite should have strong antioxidant properties and thus respond to reactive oxygen species (ROS). Here we report on fabrication and characterization of SWNT/EGCG thin films and the measurement of their relative conductance as a function of H2O2 concentrations. We further investigated the sensing mechanism by Fourier-transform infrared (FTIR) spectroscopy and field-effect transistor measurements (FET). We propose here that the response to H2O2 arises from the oxidation of EGCG in the composite. These findings suggest that SWNT/green tea composite has a great potential for developing simple resistivity-based sensors. PMID:21043457

Selective positioning and integration of individual single-walled carbon nanotubes.

PubMed

Jiao, Liying; Xian, Xiaojun; Wu, Zhongyun; Zhang, Jin; Liu, Zhongfan

2009-01-01

We present a general selective positioning and integration technique for fabricating single-walled carbon nanotube (SWNT) circuits with preselected individual SWNTs as building blocks by utilizing poly(methyl methacrylate) (PMMA) thin film as a macroscopically handlable mediator. The transparency and marker-replicating capability of PMMA mediator allow the selective placement of chirality-specific nanotubes onto predesigned patterned surfaces with a resolution of ca. 1 mum. This technique is compatible with multiple operations and p-n conversion by chemical doping, which enables the construction of complex and logic circuits. As demonstrations of building SWNTs circuits, we fabricated a field effect inverter, a 2 x 2 all-SWNT crossbar field effect transistor (FET), and flexible FETs on plastic with this technique. This selective positioning approach can also be extended to construct purpose-directed architecture with various nanoscale building blocks.

Radio frequency analog electronics based on carbon nanotube transistors

PubMed Central

Kocabas, Coskun; Kim, Hoon-sik; Banks, Tony; Rogers, John A.; Pesetski, Aaron A.; Baumgardner, James E.; Krishnaswamy, S. V.; Zhang, Hong

2008-01-01

The potential to exploit single-walled carbon nanotubes (SWNTs) in advanced electronics represents a continuing, major source of interest in these materials. However, scalable integration of SWNTs into circuits is challenging because of difficulties in controlling the geometries, spatial positions, and electronic properties of individual tubes. We have implemented solutions to some of these challenges to yield radio frequency (RF) SWNT analog electronic devices, such as narrow band amplifiers operating in the VHF frequency band with power gains as high as 14 dB. As a demonstration, we fabricated nanotube transistor radios, in which SWNT devices provide all of the key functions, including resonant antennas, fixed RF amplifiers, RF mixers, and audio amplifiers. These results represent important first steps to practical implementation of SWNTs in high-speed analog circuits. Comparison studies indicate certain performance advantages over silicon and capabilities that complement those in existing compound semiconductor technologies. PMID:18227509

Adsorption in single-walled carbon nanotubes by experiments and molecular simulation II: Effect of morphology and temperature on organic adsorption

USGS Publications Warehouse

Agnihotri, S.; Rostam-Abadi, M.; Mota, J.P.B.; Rood, M.J.

2005-01-01

Hexane adsorption on single-walled carbon nanotube (SWNT) bundles was studied. Hexane adsorption capacities of two purified SWNT samples was gravimetrically determined at isothermal conditions of 25??, 37??, and 50??C for 10-4 < p/po < 0.9, where p/po is hexane vapor pressure relative to its saturation pressure. Simulation of hexane adsorption under similar temperature and pressure conditions were performed on the external and internal sites of nanotube bundles of diameters same as those in experimental samples. The simulations could predict isotherms for a hypothetical scenario where all nanotubes in a sample would be open. This is an abstract of a paper presented at the AIChE Annual Meeting and Fall Showcase (Cincinnati, OH 10/30/2005-11/4/2005).

Single Molecule Detection in Living Biological Cells using Carbon Nanotube Optical Probes

NASA Astrophysics Data System (ADS)

Strano, Michael

2009-03-01

Nanoscale sensing elements offer promise for single molecule analyte detection in physically or biologically constrained environments. Molecular adsorption can be amplified via modulation of sharp singularities in the electronic density of states that arise from 1D quantum confinement [1]. Single-walled carbon nanotubes (SWNT), as single molecule optical sensors [2-3], offer unique advantages such as photostable near-infrared (n-IR) emission for prolonged detection through biological media, single-molecule sensitivity and, nearly orthogonal optical modes for signal transduction that can be used to identify distinct classes of analytes. Selective binding to the SWNT surface is difficult to engineer [4]. In this lecture, we will briefly review the immerging field of fluorescent diagnostics using band gap emission from SWNT. In recent work, we demonstrate that even a single pair of SWNT provides at least four optical modes that can be modulated to uniquely fingerprint chemical agents by the degree to which they alter either the emission band intensity or wavelength. We validate this identification method in vitro by demonstrating detection and identification of six genotoxic analytes, including chemotherapeutic drugs and reactive oxygen species (ROS), which are spectroscopically differentiated into four distinct classes. We also demonstrate single-molecule sensitivity in detecting hydrogen peroxide, one of the most common genotoxins and an important cellular signal. Finally, we employ our sensing and fingerprinting method of these analytes in real time within live 3T3 cells, demonstrating the first multiplexed optical detection from a nanoscale biosensor and the first label-free tool to optically discriminate between genotoxins. We will also discuss our recent efforts to fabricate biomedical sensors for real time detection of glucose and other important physiologically relevant analytes in-vivo. The response of embedded SWNT in a swellable hydrogel construct to

Carbon Nanotube-Based Membrane for Light-Driven, Simultaneous Proton and Electron Transport

DOE PAGES

Pilgrim, Gregory A.; Amori, Amanda R.; Hou, Zhentao; ...

2016-12-07

Here we discuss the photon driven transport of protons and electrons over hundreds of microns through a membrane based on vertically aligned single walled carbon nanotubes (SWNTs). Electrons are photogenerated in colloidal CdSe quantum dots that have been noncovalently attached to the carbon nanotube membrane and can be delivered at potentials capable of reducing earth-abundant molecular catalysts that perform proton reduction. Proton transport is driven by the electron photocurrent and is shown to be faster through the SWNT based membrane than through the commercial polymer Nafion. Furthermore, the potential utility of SWNT membranes for solar water splitting applications is demonstratedmore » through their excellent proton and electron transport properties as well as their ability to interact with other components of water splitting systems, such as small molecule electron acceptors.« less

Adsorption of aromatic compounds by carbonaceous adsorbents: a comparative study on granular activated carbon, activated carbon fiber, and carbon nanotubes.

PubMed

Zhang, Shujuan; Shao, Ting; Kose, H Selcen; Karanfil, Tanju

2010-08-15

Adsorption of three aromatic organic compounds (AOCs) by four types of carbonaceous adsorbents [a granular activated carbon (HD4000), an activated carbon fiber (ACF10), two single-walled carbon nanotubes (SWNT, SWNT-HT), and a multiwalled carbon nanotube (MWNT)] with different structural characteristics but similar surface polarities was examined in aqueous solutions. Isotherm results demonstrated the importance of molecular sieving and micropore effects in the adsorption of AOCs by carbonaceous porous adsorbents. In the absence of the molecular sieving effect, a linear relationship was found between the adsorption capacities of AOCs and the surface areas of adsorbents, independent of the type of adsorbent. On the other hand, the pore volume occupancies of the adsorbents followed the order of ACF10 > HD4000 > SWNT > MWNT, indicating that the availability of adsorption site was related to the pore size distributions of the adsorbents. ACF10 and HD4000 with higher microporous volumes exhibited higher adsorption affinities to low molecular weight AOCs than SWNT and MWNT with higher mesopore and macropore volumes. Due to their larger pore sizes, SWNTs and MWNTs are expected to be more efficient in adsorption of large size molecules. Removal of surface oxygen-containing functional groups from the SWNT enhanced adsorption of AOCs.

Substrate-Wrapped, Single-Walled Carbon Nanotube Probes for Hydrolytic Enzyme Characterization.

PubMed

Kallmyer, Nathaniel E; Musielewicz, Joseph; Sutter, Joel; Reuel, Nigel F

2018-04-17

Hydrolytic enzymes are a topic of continual study and improvement due to their industrial impact and biological implications; however, the ability to measure the activity of these enzymes, especially in high-throughput assays, is limited to an established, few enzymes and often involves the measurement of secondary byproducts or the design of a complex degradation probe. Herein, a versatile single-walled carbon nanotube (SWNT)-based biosensor that is straightforward to produce and measure is described. The hydrolytic enzyme substrate is rendered as an amphiphilic polymer, which is then used to solubilize the hydrophobic nanotubes. When the target enzyme degrades the wrapping, the SWNT fluorescent signal is quenched due to increased solvent accessibility and aggregation, allowing quantitative measurement of hydrolytic enzyme activity. Using (6,5) chiral SWNT suspended with polypeptides and polysaccharides, turnover frequencies are estimated for cellulase, pectinase, and bacterial protease. Responses are recorded for concentrations as low as 5 fM using a well-characterized protease, Proteinase K. An established trypsin-based plate reader assay is used to compare this nanotube probe assay with standard techniques. Furthermore, the effect of freeze-thaw cycles and elevated temperature on enzyme activity is measured, suggesting freezing to have minimal impact even after 10 cycles and heating to be detrimental above 60 °C. Finally, rapid optimization of enzyme operating conditions is demonstrated by generating a response surface of cellulase activity with respect to temperature and pH to determine optimal conditions within 2 h of serial scans.

Fracture of Carbon Nanotube - Amorphous Carbon Composites: Molecular Modeling

NASA Technical Reports Server (NTRS)

Jensen, Benjamin D.; Wise, Kristopher E.; Odegard, Gregory M.

2015-01-01

Carbon nanotubes (CNTs) are promising candidates for use as reinforcements in next generation structural composite materials because of their extremely high specific stiffness and strength. They cannot, however, be viewed as simple replacements for carbon fibers because there are key differences between these materials in areas such as handling, processing, and matrix design. It is impossible to know for certain that CNT composites will represent a significant advance over carbon fiber composites before these various factors have been optimized, which is an extremely costly and time intensive process. This work attempts to place an upper bound on CNT composite mechanical properties by performing molecular dynamics simulations on idealized model systems with a reactive forcefield that permits modeling of both elastic deformations and fracture. Amorphous carbon (AC) was chosen for the matrix material in this work because of its structural simplicity and physical compatibility with the CNT fillers. It is also much stiffer and stronger than typical engineering polymer matrices. Three different arrangements of CNTs in the simulation cell have been investigated: a single-wall nanotube (SWNT) array, a multi-wall nanotube (MWNT) array, and a SWNT bundle system. The SWNT and MWNT array systems are clearly idealizations, but the SWNT bundle system is a step closer to real systems in which individual tubes aggregate into large assemblies. The effect of chemical crosslinking on composite properties is modeled by adding bonds between the CNTs and AC. The balance between weakening the CNTs and improving fiber-matrix load transfer is explored by systematically varying the extent of crosslinking. It is, of course, impossible to capture the full range of deformation and fracture processes that occur in real materials with even the largest atomistic molecular dynamics simulations. With this limitation in mind, the simulation results reported here provide a plausible upper limit on

On-Chip Sorting of Long Semiconducting Carbon Nanotubes for Multiple Transistors along an Identical Array.

PubMed

Otsuka, Keigo; Inoue, Taiki; Maeda, Etsuo; Kometani, Reo; Chiashi, Shohei; Maruyama, Shigeo

2017-11-28

Ballistic transport and sub-10 nm channel lengths have been achieved in transistors containing one single-walled carbon nanotube (SWNT). To fill the gap between single-tube transistors and high-performance logic circuits for the replacement of silicon, large-area, high-density, and purely semiconducting (s-) SWNT arrays are highly desired. Here we demonstrate the fabrication of multiple transistors along a purely semiconducting SWNT array via an on-chip purification method. Water- and polymer-assisted burning from site-controlled nanogaps is developed for the reliable full-length removal of metallic SWNTs with the damage to s-SWNTs minimized even in high-density arrays. All the transistors with various channel lengths show large on-state current and excellent switching behavior in the off-state. Since our method potentially provides pure s-SWNT arrays over a large area with negligible damage, numerous transistors with arbitrary dimensions could be fabricated using a conventional semiconductor process, leading to SWNT-based logic, high-speed communication, and other next-generation electronic devices.

Spontaneous hybrids of graphene and carbon nanotube arrays at the liquid-gas interface for Li-ion battery anodes.

PubMed

Kim, Hyeri; Kim, Jongsoon; Jeong, Hee-Sung; Kim, Hyungsub; Lee, Hoyeon; Ha, Jae-Min; Choi, Sung-Min; Kim, Tae-Ho; Nah, Yoon-Chae; Shin, Tae Joo; Bang, Joona; Satija, Sushil K; Koo, Jaseung

2018-05-17

We demonstrate that hybrid structures of graphene and single-walled carbon nanotubes (SWNTs) are precisely controlled at the liquid-gas interface. The functionalized SWNT Langmuir monolayers anchor single-layer graphene nanosheets (GNSs) suspended in water via Coulomb interaction at the interface. This GNS/SWNT hybrid multilayer electrode can be a promising anode material for Li-ion batteries, offering high specific capacity, outstanding power capability, and excellent cyclability.

Fluorescent single-walled carbon nanotube aerogels in surfactant-free environments.

PubMed

Duque, Juan G; Hamilton, Christopher E; Gupta, Gautam; Crooker, Scott A; Crochet, Jared J; Mohite, Aditya; Htoon, Han; Obrey, Kimberly A DeFriend; Dattelbaum, Andrew M; Doorn, Stephen K

2011-08-23

A general challenge in generating functional materials from nanoscale components is integrating them into useful composites that retain or enhance their properties of interest. Development of single walled carbon nanotube (SWNT) materials for optoelectronics and sensing has been especially challenging in that SWNT optical and electronic properties are highly sensitive to environmental interactions, which can be particularly severe in composite matrices. Percolation of SWNTs into aqueous silica gels shows promise as an important route for exploiting their properties, but retention of the aqueous and surfactant environment still impacts and limits optical response, while also limiting the range of conditions in which these materials may be applied. Here, we present for the first time an innovative approach to obtain highly fluorescent solution-free SWNT-silica aerogels, which provides access to novel photophysical properties. Strongly blue-shifted spectral features, revelation of new diameter-dependent gas-phase adsorption phenomena, and significant increase (approximately three times that at room temperature) in photoluminescence intensities at cryogenic temperatures all indicate greatly reduced SWNT-matrix interactions consistent with the SWNTs experiencing a surfactant-free environment. The results demonstrate that this solid-state nanomaterial will play an important role in further revealing the true intrinsic SWNT chemical and photophysical behaviors and represent for the first time a promising new solution- and surfactant-free material for advancing SWNT applications in sensing, photonics, and optoelectronics. © 2011 American Chemical Society

Integrated single-walled carbon nanotube/microfluidic devices for the study of the sensing mechanism of nanotube sensors.

PubMed

Fu, Qiang; Liu, Jie

2005-07-21

A method to fabricate integrated single-walled carbon nanotube/microfluidic devices was developed. This simple process could be used to directly prepare nanotube thin film transistors within the microfluidic channel and to register SWNT devices with the microfludic channel without the need of an additional alignment step. The microfluidic device was designed to have several inlets that deliver multiple liquid flows to a single main channel. The location and width of each flow in the main channel could be controlled by the relative flow rates. This capability enabled us to study the effect of the location and the coverage area of the liquid flow that contained charged molecules on the conduction of the nanotube devices, providing important information on the sensing mechanism of carbon nanotube sensors. The results showed that in a sensor based on a nanotube thin film field effect transistor, the sensing signal came from target molecules absorbed on or around the nanotubes. The effect from adsorption on metal electrodes was weak.

Space Durable Polyimide/Carbon Nanotube Composite Films for Electrostatic Charge Mitigation

NASA Technical Reports Server (NTRS)

Watson, Kent A.; Smith, Joseph G., Jr.; Connell, John W.

2003-01-01

Low color, space environmentally durable polymeric films with sufficient electrical conductivity to mitigate electrostatic charge (ESC) build-up have been under investigation as part of a materials development activity. These materials have potential applications on advanced spacecraft, particularly on large, deployable, ultra-light weight Gossamer spacecraft. The approach taken to impart sufficient electrical conductivity into the polymer film is based on the use of single walled carbon nanotubes (SWNT) as conductive additives. Earlier approaches investigated in our lab involved both an in-situ polymerization approach and addition of SWNT to an oligomer containing reactive end-groups as methods to improve SWNT dispersion. The work described herein is based on the spray coating of a SWNT/solvent dispersion onto the film surface. Two types of polyimides were investigated, one with reactive end groups that can lead to bond formation between the oligomer chain and the SWNT surface and those without reactive end-groups. Surface conductivities (measured as surface resistance) in the range sufficient for ESC mitigation were achieved with minimal effects on the mechanical, optical, thermo-optical properties of the film as compared to the other methods. The chemistry and physical properties of these nanocomposites will be discussed.

Molecular dynamics simulation on adsorption of pyrene-polyethylene onto ultrathin single-walled carbon nanotube

NASA Astrophysics Data System (ADS)

Cai, Lu; Lv, Wenzhen; Zhu, Hong; Xu, Qun

2016-07-01

The mechanism of the adsorption of pyrene-polyethylene (Py-PE) onto ultrathin single-walled carbon nanotube (SWNT) was studied by using all-atom molecular dynamics (MD) simulations. We found that solvent polarity and pyrene group are two critical factors in the Py-PE decoration on ultrathin SWNT. Combined MD simulations with free energy calculations, our results indicate that larger solvent polarity can decrease the contribution of conformation entropy, but contributes little to the interaction energy, moreover, larger SWNT diameter can decrease the contribution of conformation entropy but lead to the increasing of the interaction energy. In polar organic solvent (N, N-Dimethylacetamide), the pyrene group plays a key role in the adsorption of Py-PE onto ultrathin SWNT, not only facilitates the spontaneous adsorption of Py-PE onto ultrathin SWNT, but also helps to form compact structure between themselves in the final adsorption states. While in aqueous solution, pyrene group no longer works as an anchor, but still affects a lot to the final adsorption conformation. Our present work provides detailed theoretical clue to understand the noncovalent interaction between aromatic segment appended polymer and ultrathin SWNT, and helps to explore the potential application of ultrathin SWNT in the fields of hybrid material, biomedical and electronic materials.

Single-particle tracking of endocytosis and exocytosis of single-walled carbon nanotubes in NIH-3T3 cells.

PubMed

Jin, Hong; Heller, Daniel A; Strano, Michael S

2008-06-01

Over 10000 individual trajectories of nonphotobleaching single-walled carbon nanotubes (SWNT) were tracked as they are incorporated into and expelled from NIH-3T3 cells in real time on a perfusion microscope stage. An analysis of mean square displacement allows the complete construction of the mechanistic steps involved from single duration experiments. We observe the first conclusive evidence of SWNT exocytosis and show that the rate closely matches the endocytosis rate with negligible temporal offset. We identify and study the endocytosis and exocytosis pathway that leads to the previously observed aggregation and accumulation of SWNT within the cells.

Preparation and Characterization of Space Durable Polymer Nanocomposite Films from Functionalized Carbon Nanotubes

NASA Technical Reports Server (NTRS)

Delozier, D. M.; Connell, J. W.; Smith, J. G.; Watson, K. A.

2003-01-01

Low color, flexible, space durable polyimide films with inherent, robust electrical conductivity have been under investigation as part of a continuing materials development activity for future NASA space missions involving Gossamer structures. Electrical conductivity is needed in these films to dissipate electrostatic charge build-up that occurs due to the orbital environment. One method of imparting conductivity is through the use of single walled carbon nanotubes (SWNTs). However, the incompatibility and insolubility of the SWNTs severely hampers their dispersion in polymeric matrices. In an attempt to improve their dispersability, SWNTs were functionalized by the reaction with an alkyl hydrazone. After this functionalization, the SWNTs were soluble in select solvents and dispersed more readily in the polymer matrix. The functionalized SWNTs were characterized by Raman spectroscopy and thermogravimetric analysis (TGA). The functionalized nanotubes were dispersed in the bulk of the films using a solution technique. The functionalized nanotubes were also applied to the surface of polyimide films using a spray coating technique. The resultant polyimide nanocomposite films were evaluated for nanotube dispersion, electrical conductivity, mechanical, and optical properties and compared with previously prepared polyimide-SWNT samples to assess the effects of SWNT functionalization.

Imaging the distribution of individual platinum-based anticancer drug molecules attached to single-wall carbon nanotubes

PubMed Central

Bhirde, Ashwin A; Sousa, Alioscka A; Patel, Vyomesh; Azari, Afrouz A; Gutkind, J Silvio; Leapman, Richard D; Rusling, James F

2009-01-01

Aims To image the distribution of drug molecules attached to single-wall carbon nanotubes (SWNTs). Materials & methods Herein we report the use of scanning transmission electron microscopy (STEM) for atomic scale visualization and quantitation of single platinum-based drug molecules attached to SWNTs designed for targeted drug delivery. Fourier transform infrared spectroscopy and energy-dispersive x-ray spectroscopy were used for characterization of the SWNT drug conjugates. Results Z-contrast STEM imaging enabled visualization of the first-line anticancer drug cisplatin on the nanotubes at single molecule level. The identity and presence of cisplatin on the nanotubes was confirmed using energy-dispersive x-ray spectroscopy and Fourier transform infrared spectroscopy. STEM tomography was also used to provide additional insights concerning the nanotube conjugates. Finally, our observations provide a rationale for exploring the use of SWNT bioconjugates to selectively target and kill squamous cancer cells. Conclusion Z-contrast STEM imaging provides a means for direct visualization of heavy metal containing molecules (i.e., cisplatin) attached to surfaces of carbon SWNTs along with distribution and quantitation. PMID:19839812

Composite electronic materials based on poly(3,4-propylenedioxythiophene) and highly charged poly(aryleneethynylene)-wrapped carbon nanotubes for supercapacitors.

PubMed

Rosario-Canales, Mariem R; Deria, Pravas; Therien, Michael J; Santiago-Avilés, Jorge J

2012-01-01

Supercapacitor charge storage media were fabricated using the semiconducting polymer poly(3,4-propylenedioxythiophene) (PProDOT) and single-walled carbon nanotubes (SWNTs) that were helically wrapped with ionic, conjugated poly[2,6-{1,5-bis(3-propoxysulfonicacidsodiumsalt)}naphthylene]ethynylene (PNES). These PNES-wrapped SWNTs (PNES-SWNTs) enable efficient dispersion of individualized nanotubes in a wide range of organic solvents. PNES-SWNT film-modified Pt electrodes were prepared by drop casting PNES-SWNT suspensions in MeOH; high stability, first-generation PProDOT/PNES/SWNT composites were realized via electropolymerization of the ProDOT parent monomer (3,4-propylenedioxythiophene) in a 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide/propylene carbonate solution at the PNES-SWNT-modified electrode. The electrochemical properties of PProDOT and PProDOT/PNES/SWNT single electrodes and devices were examined using cyclic voltammetric methods. The hybrid composites were found to enhance key supercapacitor figures of merit (charge capacity and capacitance) by approximately a factor of 2 relative to those determined for benchmark Type I devices that exploited a classic PProDOT-based electrode material. The charge/discharge stability of the supercapacitors was probed by repeated rounds of cyclic voltammetric evaluation at a minimum depth of discharge of 73%; these experiments demonstrated that the hybrid PProDOT/PNES/SWNT composites retained ~90% of their initial charge capacity after 21,000 charge/discharge cycles, contrasting analogous data obtained for PProDOT-based devices, which showed only 84% retention of their initial charge capacity. © 2011 American Chemical Society

Noise characteristics of single-walled carbon nanotube network transistors.

PubMed

Kim, Un Jeong; Kim, Kang Hyun; Kim, Kyu Tae; Min, Yo-Sep; Park, Wanjun

2008-07-16

The noise characteristics of randomly networked single-walled carbon nanotubes grown directly by plasma enhanced chemical vapor deposition (PECVD) are studied with field effect transistors (FETs). Due to the geometrical complexity of nanotube networks in the channel area and the large number of tube-tube/tube-metal junctions, the inverse frequency, 1/f, dependence of the noise shows a similar level to that of a single single-walled carbon nanotube transistor. Detailed analysis is performed with the parameters of number of mobile carriers and mobility in the different environment. This shows that the change in the number of mobile carriers resulting in the mobility change due to adsorption and desorption of gas molecules (mostly oxygen molecules) to the tube surface is a key factor in the 1/f noise level for carbon nanotube network transistors.

Electron percolation in realistic models of carbon nanotube networks

NASA Astrophysics Data System (ADS)

Simoneau, Louis-Philippe; Villeneuve, Jérémie; Rochefort, Alain

2015-09-01

The influence of penetrable and curved carbon nanotubes (CNT) on the charge percolation in three-dimensional disordered CNT networks have been studied with Monte-Carlo simulations. By considering carbon nanotubes as solid objects but where the overlap between their electron cloud can be controlled, we observed that the structural characteristics of networks containing lower aspect ratio CNT are highly sensitive to the degree of penetration between crossed nanotubes. Following our efficient strategy to displace CNT to different positions to create more realistic statistical models, we conclude that the connectivity between objects increases with the hard-core/soft-shell radii ratio. In contrast, the presence of curved CNT in the random networks leads to an increasing percolation threshold and to a decreasing electrical conductivity at saturation. The waviness of CNT decreases the effective distance between the nanotube extremities, hence reducing their connectivity and degrading their electrical properties. We present the results of our simulation in terms of thickness of the CNT network from which simple structural parameters such as the volume fraction or the carbon nanotube density can be accurately evaluated with our more realistic models.

Study of the Mechanism of Irreversible Adsorption of Single-Walled Carbon Nanotubes to Sephacryl Hydrogel

NASA Astrophysics Data System (ADS)

Rolsma, Caleb

As a class of carbon-based nanomaterials, single-walled carbon nanotubes (SWNT) have many structural variations, called chiralities, each with different properties. Many potential applications of SWNT require the properties of a single chirality, but current synthesis methods can only produce single chiralities at prohibitive costs, or mixtures of chiralities at more affordable prices. Post-synthesis chirality separations provide a solution to this problem, and hydrogel separations are one such method. Despite much work in this field, the underlying interactions between SWNT and hydrogel are not fully understood. During separation, large quantities of SWNT are irretrievably lost due to irreversible adsorption to the hydrogel, posing a major problem to separation efficiency, while also offering an interesting scientific problem concerning the interaction of SWNT with hydrogels and surfactants. This thesis explores the problem of irreversible adsorption, offering an explanation for the process from a mechanistic viewpoint, opening new ways for improvement in separation. In brief, this work concludes adsorption follows three pathways, two of which lead to irreversible adsorption, both mediated by the presence of surfactants and limited by characteristics of the hydrogel surface. These findings stand to increase the general understanding of hydrogel SWNT separations, leading to improvements in separation, and bringing the research field closer to the many potential applications of single-chirality SWNT.

A Novel Catalyst Deposition Technique for the Growth of Carbon Nanotubes

NASA Technical Reports Server (NTRS)

Delzeit, Lance; Cassell, A.; Stevens, R.; Nguyen, C.; Meyyappan, M.; DeVincenzi, Donald L. (Technical Monitor)

2001-01-01

This viewgraph presentation provides information on the development of a technique at NASA's Ames Research Center by which carbon nanotubes (NT) can be grown. The project had several goals which included: 1) scaleability, 2) ability to control single wall nanotube (SWNT) and multiwall nanotube (MWNT) formation, 3) ability to control the density of nanotubes as they grow, 4) ability to apply standard masking techniques for NT patterning. Information regarding the growth technique includes its use of a catalyst deposition process. SWNTs of varying thicknesses can be grown by changing the catalyst composition. Demonstrations are given of various methods of masking including the use of transmission electron microscopic (TEM) grids.

A Demo opto-electronic power source based on single-walled carbon nanotube sheets.

PubMed

Hu, Chunhua; Liu, Changhong; Chen, Luzhuo; Meng, Chuizhou; Fan, Shoushan

2010-08-24

It is known that single-walled carbon nanotubes (SWNTs) strongly absorb light, especially in the near-infrared (NIR) region, and convert it into heat. In fact, SWNTs also have considerable ability to convert heat into electricity. In this work, we show that SWNT sheets made from as-grown SWNT arrays display a large positive thermoelectric coefficient (p-type). We designed a simple SWNT device to convert illuminating NIR light directly into a notable voltage output, which was verified by experimental tests. Furthermore, by a simple functionalization step, the p- to n-type transition was conveniently achieved for the SWNT sheets. By integrating p- and n-type elements in series, we constructed a novel NIR opto-electronic power source, which outputs a large voltage that sums over the output of every single element. Additionally, the output of the demo device has shown a good linear relationship with NIR light power density, favorable for IR sensors.

Functionalization of Carbon Nanotubes using Atomic Hydrogen

NASA Technical Reports Server (NTRS)

Khare, Bishun N.; Cassell, Alan M.; Nguyen, Cattien V.; Meyyappan, M.; Han, Jie; Arnold, Jim (Technical Monitor)

2001-01-01

We have investigated the irradiation of multi walled and single walled carbon nanotubes (SWNTs) with atomic hydrogen. After irradiating the SWNT sample, a band at 2940/cm (3.4 microns) that is characteristic of the C-H stretching mode is observed using Fourier transform infrared (FTIR) spectroscopy. Additional confirmation of SWNT functionalization is tested by irradiating with atomic deuterium. A weak band in the region 1940/cm (5.2 micron) to 2450/cm (4.1 micron) corresponding to C-D stretching mode is also observed in the FTIR spectrum. This technique provides a clean gas phase process for the functionalization of SWNTs, which could lead to further chemical manipulation and/or the tuning of the electronic properties of SWNTs for nanodevice applications.

Biological construction of single-walled carbon nanotube electron transfer pathways in dye-sensitized solar cells.

PubMed

Inoue, Ippei; Watanabe, Kiyoshi; Yamauchi, Hirofumi; Ishikawa, Yasuaki; Yasueda, Hisashi; Uraoka, Yukiharu; Yamashita, Ichiro

2014-10-01

We designed and mass-produced a versatile protein supramolecule that can be used to manufacture a highly efficient dye-sensitized solar cell (DSSC). Twelve single-walled carbon-nanotube (SWNT)-binding and titanium-mineralizing peptides were genetically integrated on a cage-shaped dodecamer protein (CDT1). A process involving simple mixing of highly conductive SWNTs with CDT1 followed by TiO2 biomineralization produces a high surface-area/weight TiO2 -(anatase)-coated intact SWNT nanocomposite under environmentally friendly conditions. A DSSC with a TiO2 photoelectrode containing 0.2 wt % of the SWNT-TiO2 nanocomposite shows a current density improvement by 80% and a doubling of the photoelectric conversion efficiency. The SWNT-TiO2 nanocomposite transfers photon-generated electrons from dye molecules adsorbed on the TiO2 to the anode electrode swiftly. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nanotube/Quantum Dot-Polymer Solar Cells

NASA Technical Reports Server (NTRS)

Bailey, Sheila G.; Raffaelle, Ryne P.; Landi, Brian J.; Castro, Stephanie L.

2005-01-01

Single wall carbon nanotubes used or this study were synthesized using the pulse laser vaporization technique. The as-produced SWNTs were collected from the condensed region on the quartz tube outside the furnace and purified by modification of the previously reported procedure. Preparation of the SWNT-P3OT composite solutions was performed using a series of mixing and sonication steps as previously demonstrated for other SWNT-polymer systems. Device fabrication involved the use of commercially-obtained, high quality (i.e., less than 10 W/sq.) ITO-coated polyethylene terapthalate (PET) substrates. Initially, an intrinsic layer of pristine P3OT is spray deposited (approx. 1-2 mL of the 15 mg/mL solution) onto the masked, 1 sq in. active area of the substrate. This is followed with spray deposition of the SWNT-P3OT composite solutions at similar volumes. As seen completion of the solar cell occurs when aluminum contacts (typical thicknesses of l000A) are applied to the IT0 and SWNT-P3OT composite film layers. The homogeneous distribution of SWNTs in a polymer matrix is dependent upon the ability of the polymer chain to associate with the SWNT superstructure. Stable composite dispersions of 0.1 % and 1.0% w/w SWNTs in P3OT were produced and analyzed in this study. Optical spectroscopy was conducted to observe the SWNT doping level effects on the absorption properties and infer potential electronic interactions between dopant and polymer. Shown is an overlay of these spectra where the pristine P3OT shows strong optical absorption at energies less than 2 eV. As expected, variation in absorption properties for the SWNT-P3OT composites is observed as the doping level increases. Through modification of the SWNT doping level in the polymer, it is possible to alter the absorption pattern of these composite materials. In fact, at these relatively low doping levels, the P3OT shows a significant enhancement in absorption through the near-IR and visible regions. The gray curve

Effects of Atomic-Scale Structure on the Fracture Properties of Amorphous Carbon - Carbon Nanotube Composites

NASA Technical Reports Server (NTRS)

Jensen, Benjamin D.; Wise, Kristopher E.; Odegard, Gregory M.

2015-01-01

The fracture of carbon materials is a complex process, the understanding of which is critical to the development of next generation high performance materials. While quantum mechanical (QM) calculations are the most accurate way to model fracture, the fracture behavior of many carbon-based composite engineering materials, such as carbon nanotube (CNT) composites, is a multi-scale process that occurs on time and length scales beyond the practical limitations of QM methods. The Reax Force Field (ReaxFF) is capable of predicting mechanical properties involving strong deformation, bond breaking and bond formation in the classical molecular dynamics framework. This has been achieved by adding to the potential energy function a bond-order term that varies continuously with distance. The use of an empirical bond order potential, such as ReaxFF, enables the simulation of failure in molecular systems that are several orders of magnitude larger than would be possible in QM techniques. In this work, the fracture behavior of an amorphous carbon (AC) matrix reinforced with CNTs was modeled using molecular dynamics with the ReaxFF reactive forcefield. Care was taken to select the appropriate simulation parameters, which can be different from those required when using traditional fixed-bond force fields. The effect of CNT arrangement was investigated with three systems: a single-wall nanotube (SWNT) array, a multi-wall nanotube (MWNT) array, and a SWNT bundle system. For each arrangement, covalent bonds are added between the CNTs and AC, with crosslink fractions ranging from 0-25% of the interfacial CNT atoms. The SWNT and MWNT array systems represent ideal cases with evenly spaced CNTs; the SWNT bundle system represents a more realistic case because, in practice, van der Waals interactions lead to the agglomeration of CNTs into bundles. The simulation results will serve as guidance in setting experimental processing conditions to optimize the mechanical properties of CNT

Industrially Feasible Approach to Transparent, Flexible, and Conductive Carbon Nanotube Films: Cellulose-Assisted Film Deposition Followed by Solution and Photonic Processing

NASA Astrophysics Data System (ADS)

Kim, Yeji; Chikamatsu, Masayuki; Azumi, Reiko; Saito, Takeshi; Minami, Nobutsugu

2013-02-01

We report that single-walled nanotube (SWNT) films with precisely controlled thicknesses and transmittances can be produced through the doctor-blade method using SWNT-polymer inks. The matrix polymer around SWNTs were successfully removed by either solution curing or photonic curing at room temperature, which are advantageous processes enabling direct film formation on plastic substrates. Sheet resistances as low as 68-240 Ω/sq at T=89-98% were obtained. Furthermore, the SWNT film on poly(ethylene naphthalate) exhibited superior flexibility and stability in a flexure endurance test. The method may open a wide range of opportunities for flexible electrical devices.

Seed crystals and catalyzed epitaxy of single-walled carbon nanotubes

NASA Astrophysics Data System (ADS)

Wang, Yuhuang

This thesis demonstrates the continued growth of single-walled carbon nanotubes (SWNTs) from seeded SWNTs in a way analogous to epitaxy or cloning; that is, the SWNTs grow as a seamless extension to the existing seeded SWNTs and have the same diameter and chirality as those of the SWNT seeds. The experiments were carried out in three key steps, including: (1) preparing a macroscopic array of open-ended SWNTs; (2) reductively docking transition metals as a catalyst to the nanometer-sized open ends; and then (3) heating the whole up to 700--850°C in the presence of a carbon feedstock such as ethanol or ethylene. The resulting SWNT ropes inherit the diameters and chirality from the seeded SWNTs, as indicated by the closely matched frequencies of Raman radial breathing modes before and after the growth. As a control, only sparse nanotubes grew from closed-ended SWNTs, ruling out spontaneous nucleation as a dominating mechanism in our experiments. This experiment proved for the first time the growth of SWNTs can be separated from the nucleation step. The ability to separate the typically inefficient nucleation step from the growth of SWNTs and to restart the growth opens the possibility of amplifying SWNTs with only the desired (n, m). The success in the continued growth was enabled with the creation of macroscopic arrays of open-ended SWNTs from a neat SWNT fiber. A variety of techniques including cryo-microtoming and surface etching chemistry have been developed to produce a macroscopic (˜1200mum2), aligned, and clean---largely free of amorphous carbon, oxides, and metal residuals---SWNT substrate with open-ended SWNTs aligned along the fiber axis. Alternatively, the fiber was milled perpendicular to the fiber axis with a gallium focused ion beam to produce a planar, free-standing, ultra-thin, "bed-of-nails" SWNT membrane---a single layer of parallel SWNTs densely packed and aligned along the normal of the membrane.

Electroluminescence from single-wall carbon nanotube network transistors.

PubMed

Adam, E; Aguirre, C M; Marty, L; St-Antoine, B C; Meunier, F; Desjardins, P; Ménard, D; Martel, R

2008-08-01

The electroluminescence (EL) properties from single-wall carbon nanotube network field-effect transistors (NNFETs) and small bundle carbon nanotube field effect transistors (CNFETs) are studied using spectroscopy and imaging in the near-infrared (NIR). At room temperature, NNFETs produce broad (approximately 180 meV) and structured NIR spectra, while they are narrower (approximately 80 meV) for CNFETs. EL emission from NNFETs is located in the vicinity of the minority carrier injecting contact (drain) and the spectrum of the emission is red shifted with respect to the corresponding absorption spectrum. A phenomenological model based on a Fermi-Dirac distribution of carriers in the nanotube network reproduces the spectral features observed. This work supports bipolar (electron-hole) current recombination as the main mechanism of emission and highlights the drastic influence of carrier distribution on the optoelectronic properties of carbon nanotube films.

Transparent Conductors from Carbon Nanotubes LBL-Assembled with Polymer Dopant with π-π Electron Transfer

PubMed Central

Zhu, Jian; Shim, Bong Sup; Di Prima, Matthew; Kotov, Nicholas A.

2011-01-01

Single-walled carbon nanotube (SWNT) and other carbon-based coatings are being considered as replacements for indium tin oxide (ITO). The problems of transparent conductors (TCs) coatings from SWNT and similar materials include poor mechanical properties, high roughness, low temperature resilience, and fast loss of conductivity. The simultaneous realization of these desirable characteristics can be achieved using high structural control of layer-by-layer (LBL) deposition, which is demonstrated by the assembly of hydroethyl cellulose (HOCS) and sulfonated polyetheretherketone (SPEEK)-SWNTs. A new type of SWNT doping based on electron transfer from valence bands of nanotubes to unoccupied levels of SPEEK through π-π interactions was identified for this system. It leads to a conductivity of 1.1×105 S/m at 66wt% loadings of SWNT. This is better than other polymer/SWNT composites and translates into surface conductivity of 920 ohms/sq and transmittance of 86.7% at 550nm. The prepared LBL films also revealed unusually high temperature resilience up to 500°C, and low roughness of 3.5 nm (ITO glass - 2.4 nm). Tensile modulus, ultimate strength, and toughness of such coatings are 13±2 GPa, 366±35 MPa and 8±3 kJ/m3, respectively, and exceed corresponding parameters of all similar TCs. The cumulative figure of merit, ΠTC, which included the critical failure strain relevant for flexible electronics, was ΠTC = 0.022 and should be compared to ΠTC = 0.006 for commercial ITO. Further optimization is possible using stratified nanoscale coatings and improved doping from the macromolecular LBL components. PMID:21524068

Dispersion of carbon nanotubes in vinyl ester polymer composites

NASA Astrophysics Data System (ADS)

Pena-Paras, Laura

This work focused on a parametric study of dispersions of different types of carbon nanotubes in a polymer resin. Single-walled (SWNTs), double-walled (DWNTs), multi-walled (MWNTs) and XD-grade carbon nanotubes (XD-CNTs) were dispersed in vinyl ester (VE) using an ultra-sonic probe at a fixed frequency. The power, amplitude, and mixing time parameters of sonication were correlated to the electrical and mechanical properties of the composite materials in order to optimize dispersion. The quality of dispersion was quantified by Raman spectroscopy and verified through optical and scanning electron microscopy. By Raman, the CNT distribution, unroping, and damage was monitored and correlated with the composite properties for dispersion optimization. Increasing the ultrasonication energy was found to improve the distribution of all CNT materials and to decrease the size of nanotube ropes, enhancing the electrical conductivity and storage modulus. However, excessive amounts of energy were found to damage CNTs, which negatively affected the properties of the composite. Based on these results the optimum dispersion energy inputs were determined for the different composite materials. The electrical resistivity was lowered by as much as 14, 13, 13, and 11 orders of magnitude for SWNT/VE, DWNT/VE, MWNT/VE, and XD-CNT/VE respectively, compared to the neat resin. The storage modulus was also increased compared to the neat resin by 77%, 82%, 45%, 40% and 85% in SWNT, SAP-f-SWNT, DWNT, MWNT and XD-CNT/VE composites, respectively. This study provides a detailed understanding of how the properties of, nanocomposites are determined by the composite mixing parameters and the distribution, concentration, shape and size of the CNTs. Importantly, it indicates the importance of the need for dispersion metrics to correlate and understand these properties.

Binding and condensation of plasmid DNA onto functionalized carbon nanotubes: toward the construction of nanotube-based gene delivery vectors.

PubMed

Singh, Ravi; Pantarotto, Davide; McCarthy, David; Chaloin, Olivier; Hoebeke, Johan; Partidos, Charalambos D; Briand, Jean-Paul; Prato, Maurizio; Bianco, Alberto; Kostarelos, Kostas

2005-03-30

Carbon nanotubes (CNTs) constitute a class of nanomaterials that possess characteristics suitable for a variety of possible applications. Their compatibility with aqueous environments has been made possible by the chemical functionalization of their surface, allowing for exploration of their interactions with biological components including mammalian cells. Functionalized CNTs (f-CNTs) are being intensively explored in advanced biotechnological applications ranging from molecular biosensors to cellular growth substrates. We have been exploring the potential of f-CNTs as delivery vehicles of biologically active molecules in view of possible biomedical applications, including vaccination and gene delivery. Recently we reported the capability of ammonium-functionalized single-walled CNTs to penetrate human and murine cells and facilitate the delivery of plasmid DNA leading to expression of marker genes. To optimize f-CNTs as gene delivery vehicles, it is essential to characterize their interactions with DNA. In the present report, we study the interactions of three types of f-CNTs, ammonium-functionalized single-walled and multiwalled carbon nanotubes (SWNT-NH3+; MWNT-NH3+), and lysine-functionalized single-walled carbon nanotubes (SWNT-Lys-NH3+), with plasmid DNA. Nanotube-DNA complexes were analyzed by scanning electron microscopy, surface plasmon resonance, PicoGreen dye exclusion, and agarose gel shift assay. The results indicate that all three types of cationic carbon nanotubes are able to condense DNA to varying degrees, indicating that both nanotube surface area and charge density are critical parameters that determine the interaction and electrostatic complex formation between f-CNTs with DNA. All three different f-CNT types in this study exhibited upregulation of marker gene expression over naked DNA using a mammalian (human) cell line. Differences in the levels of gene expression were correlated with the structural and biophysical data obtained for the f

Fabrication of air-stable n-type carbon nanotube thin-film transistors on flexible substrates using bilayer dielectrics.

PubMed

Li, Guanhong; Li, Qunqing; Jin, Yuanhao; Zhao, Yudan; Xiao, Xiaoyang; Jiang, Kaili; Wang, Jiaping; Fan, Shoushan

2015-11-14

Single-walled carbon nanotube (SWNT) thin-film transistors hold great potential for flexible electronics. However, fabrication of air-stable n-type devices by methods compatible with standard photolithography on flexible substrates is challenging. Here, we demonstrated that by using a bilayer dielectric structure of MgO and atomic layer deposited (ALD) Al2O3 or HfO2, air-stable n-type devices can be obtained. The mechanism for conduction type conversion was elucidated and attributed to the hole depletion in SWNT, the decrease of the trap state density by MgO assimilating adsorbed water molecules in the vicinity of SWNT, and the energy band bending because of the positive fixed charges in the ALD layer. The key advantage of the method is the relatively low temperature (120 or 90 °C) required here for the ALD process because we need not employ this step to totally remove the absorbates on the SWNTs. This advantage facilitates the integration of both p-type and n-type transistors through a simple lift off process and compact CMOS inverters were demonstrated. We also demonstrated that the doping of SWNTs in the channel plays a more important role than the Schottky barriers at the metal contacts in carbon nanotube thin-film transistors, unlike the situation in individual SWNT-based transistors.

Review of Electronics Based on Single-Walled Carbon Nanotubes.

PubMed

Cao, Yu; Cong, Sen; Cao, Xuan; Wu, Fanqi; Liu, Qingzhou; Amer, Moh R; Zhou, Chongwu

2017-08-14

Single-walled carbon nanotubes (SWNTs) are extremely promising materials for building next-generation electronics due to their unique physical and electronic properties. In this article, we will review the research efforts and achievements of SWNTs in three electronic fields, namely analog radio-frequency electronics, digital electronics, and macroelectronics. In each SWNT-based electronic field, we will present the major challenges, the evolutions of the methods to overcome these challenges, and the state-of-the-art of the achievements. At last, we will discuss future directions which could lead to the broad applications of SWNTs. We hope this review could inspire more research on SWNT-based electronics, and accelerate the applications of SWNTs.

Carbon Nanotube-Poly(vinylalcohol) Nanocomposite Film Devices: Applications for Femtosecond Fiber Laser Mode Lockers and Optical Amplifier Noise Suppressors

NASA Astrophysics Data System (ADS)

Sakakibara, Youichi; Rozhin, Aleksey G.; Kataura, Hiromichi; Achiba, Yohji; Tokumoto, Madoka

2005-04-01

We fabricated single-wall carbon nanotube (SWNT)/poly(vinylalcohol) (PVA) nanocomposite freestanding films and examined their application in devices in which the saturable absorption of SWNTs at near-infrared optical telecommunication wavelengths can be utilized. In a passively mode-locked fiber laser, we integrated a 30-μm-thick SWNT/PVA film into a fiber connection adaptor with the film sandwiched by a pair of fiber ferrules. A ring fiber laser with a SWNT/PVA saturable absorber was operated very easily in the mode-locked short-pulse mode with a pulse width of about 500 fs. Reproducible stable device performance was confirmed. In examining noise suppression for optical amplifiers, mixed light of semiconductor amplified spontaneous emission (ASE) source and 370 fs laser pulses was passed through a 100-μm-thick SWNT/PVA film. The transmission loss of the femtosecond pulse light was smaller than that of the ASE light. This proved that the SWNT/PVA film has the ability to suppress ASE noise.

A New Carbon Nanotube-Based Breast Cancer Drug Delivery System: Preparation and In Vitro Analysis Using Paclitaxel.

PubMed

Shao, Wei; Paul, Arghya; Rodes, Laetitia; Prakash, Satya

2015-04-01

Paclitaxel (PTX) is one of the most important drugs for breast cancer; however, the drug effects are limited by its systematic toxicity and poor water solubility. Nanoparticles have been applied for delivery of cancer drugs to overcome their limitations. Toward this goal, a novel single-walled carbon nanotube (SWNT)-based drug delivery system was developed by conjugation of human serum albumin (HSA) nanoparticles for loading of antitumor agent PTX. The nanosized macromolecular SWNT-drug carrier (SWNT-HSA) was characterized by TEM, UV-Vis-NIR spectrometry, and TGA. The SWNT-based drug carrier displayed high intracellular delivery efficiency (cell uptake rate of 80%) in breast cancer MCF-7 cells, as examined by fluorescence-labeled drug carriers, suggesting the needle-shaped SWNT-HSA drug carrier was able to transport drugs across cell membrane despite its macromolecular structure. The drug loading on SWNT-based drug carrier was through high binding affinity of PTX to HSA proteins. The PTX formulated with SWNT-HSA showed greater growth inhibition activity in MCF-7 breast cancer cells than PTX formulated with HSA nanoparticle only (cell viability of 63 vs 70% in 48 h and 53 vs 62% in 72 h). The increased drug efficacy could be driven by SWNT-mediated cell internalization. These data suggest that the developed SWNT-based antitumor agent is functional and effective. However, more studies for in vivo drug delivery efficacy and other properties are needed before this delivery system can be fully realized.

Synthesis, transfer printing, electrical and optical properties, and applications of materials composed of self-assembled, aligned single-walled carbon nanotubes

NASA Astrophysics Data System (ADS)

Pint, Cary L.

Super growth of single-walled carbon nanotubes (SWNTs) has emerged as a unique method for synthesizing self-assembled, pristine, aligned SWNT materials composed of ultra-long (millimeter-long) nanotubes. This thesis focuses on novel routes of synthesizing such self-assembled SWNTs and the challenges that arise in integrating this material into next-generation applications. First of all, this work provides unique insight into growth termination of aligned SWNTs, emphasizing the mechanism that inhibits the growth of infinitely long nanotubes. Exhaustive real-time growth studies, combined with ex-situ and in-situ TEM characterization emphasizes that Ostwald ripening and subsurface diffusion of catalyst particles play a key role in growth termination. As a result, rational steps to solving this problem can enhance growth, and may ultimately lead to the meter or kilometer-long SWNTs that are necessary for a number of applications. In addition, other novel synthesis routes are discussed, such as the ability to form macroscopic fibrils of SWNTs, called "flying carpets" from 40 nm thick substrates, and the ability to achieve supergrowth of SWNTs that are controllably doped with nitrogen. In the latter case, molecular heterojunctions of doped and undoped sections in a single strand of ultralong SWNTs are demonstrated Secondly, as supergrowth is conducted on alumina coated SiO2 substrates, any applications will require that one can transfer the SWNTs to host surfaces with minimal processing. This work demonstrates a unique contact transfer route by which both patterned arrays of SWNTs, or homogenous SWNT carpets, can be transferred to any host surface. In the first case, the SWNTs are grown vertically aligned, and transferred in patterns of horizontally aligned SWNT. This transfer process relies on simple water-vapor etching of amorphous carbons at the catalyst following growth, and strong van der Waals adhesion of the high surface-area SWNT to host surfaces (gecko effect

Functional single-wall carbon nanotube nanohybrids--associating SWNTs with water-soluble enzyme model systems.

PubMed

Guldi, Dirk M; Rahman, G M Aminur; Jux, Norbert; Balbinot, Domenico; Hartnagel, Uwe; Tagmatarchis, Nikos; Prato, Maurizio

2005-07-13

We succeeded in integrating single-wall carbon nanotubes (SWNTs), several water-soluble pyrene derivatives (pyrene(-)), which bear negatively charged ionic headgroups, and a series of water-soluble metalloporphyrins (MP(8+)) into functional nanohybrids through a combination of associative van der Waals and electrostatic interactions. The resulting SWNT/pyrene(-) and SWNT/pyrene(-)/MP(8+) were characterized by spectroscopic and microscopic means and were found to form stable nanohybrid structures in aqueous media. A crucial feature of our SWNT/pyrene(-) and SWNT/pyrene(-)/MP(8)(+) is that an efficient exfoliation of the initial bundles brings about isolated nanohybrid structures. When the nanohybrid systems are photoexcited with visible light, a rapid intrahybrid charge separation causes the reduction of the electron-accepting SWNT and, simultaneously, the oxidation of the electron-donating MP(8)(+). Transient absorption measurements confirm that the radical ion pairs are long-lived, with lifetimes in the microsecond range. Particularly beneficial are charge recombination dynamics that are located deep in the Marcus-inverted region. We include, for the first time, work devoted to exploring and testing FeP(8)(+) and CoP(8)(+) in donor-acceptor nanohybrids.

Dissociation of single-strand DNA: single-walled carbon nanotube hybrids by Watson-Crick base-pairing.

PubMed

Jung, Seungwon; Cha, Misun; Park, Jiyong; Jeong, Namjo; Kim, Gunn; Park, Changwon; Ihm, Jisoon; Lee, Junghoon

2010-08-18

It has been known that single-strand DNA wraps around a single-walled carbon nanotube (SWNT) by pi-stacking. In this paper it is demonstrated that such DNA is dissociated from the SWNT by Watson-Crick base-pairing with a complementary sequence. Measurement of field effect transistor characteristics indicates a shift of the electrical properties as a result of this "unwrapping" event. We further confirm the suggested process through Raman spectroscopy and gel electrophoresis. Experimental results are verified in view of atomistic mechanisms with molecular dynamics simulations and binding energy analyses.

Interactions of carbon nanotubes with the nitromethane-water mixture governing selective adsorption of energetic molecules from aqueous solution.

PubMed

Liu, Yingzhe; Lai, Weipeng; Yu, Tao; Kang, Ying; Ge, Zhongxue

2015-03-14

The structure and dynamics of the nitromethane-water (NM-WT) binary mixture surrounding single walled carbon nanotubes (SWNTs) have been investigated by molecular dynamics simulations. The simulation trajectories show that the NM molecules can be selectively adsorbed both outside the surface and inside the cavity of SWNTs mainly dominated by van der Waals attractions because SWNTs have a higher binding affinity for NM than WT. The binding energies of SWNTs with NM and WT obtained from electronic structure calculations at the M06-2X/6-31+G* level are 15.31 and 5.51 kcal mol(-1), respectively. Compared with the SWNT exterior, the selective adsorption of NM is preferentially occurred in the SWNT interior due to the hydrophobic interactions and the dipole-dipole interactions, which induces the decrease of the hydrogen-bond number of NM with WT and ordered structures of NM with preferred intermolecular orientation in the SWNT cavity. Furthermore, the selective adsorption dynamics of NM from the aqueous solution is regardless of the chirality and radius of SWNTs. The SWNT radius plays a negligible role in the mass density distributions of NM outside the SWNTs, while the mass density of NM in the SWNT interior decreases gradually as the SWNT radius increases. The structural arrangements and intermolecular orientations of NM in the SWNT cavity are greatly dependent on the SWNT radius due to the size effect.

Understanding the mechanism of nanotube synthesis for controlled production of specific (n,m) structures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Resasco, Daniel E.

2010-02-11

This report shows the extensive research on the mechanism responsible for the formation of single walled carbon nanotubes in order to get control over their structural parameters (diameter and chirality). Catalyst formulations, pre-treatment conditions, and reaction conditions are described in detail as well as mechanisms to produce nanotubes structures of specific arrays (vertical forest, nanotube pillars). Applications of SWNT in different fields are also described in this report. In relation to this project five students have graduated (3 PhD and 2 MS) and 35 papers have been published.

Fluence-dependent singlet exciton dynamics in length-sorted chirality-enriched single-walled carbon nanotubes.

PubMed

Park, Jaehong; Deria, Pravas; Olivier, Jean-Hubert; Therien, Michael J

2014-02-12

We utilize individualized, length-sorted (6,5)-chirality enriched single-walled carbon nanotubes (SWNTs) having dimensions of 200 and 800 nm, femtosecond transient absorption spectroscopy, and variable excitation fluences that modulate the exciton density per nanotube unit length, to interrogate nanotube exciton/biexciton dynamics. For pump fluences below 30 μJ/cm(2), transient absorption (TA) spectra of (6,5) SWNTs reveal the instantaneous emergence of the exciton to biexciton transition (E11 → E11,BX) at 1100 nm; in contrast, under excitation fluences exceeding 100 μJ/cm(2), this TA signal manifests a rise time (τ rise ∼ 250 fs), indicating that E11 state repopulation is required to produce this signal. Femtosecond transient absorption spectroscopic data acquired over the 900-1400 nm spectral region of the near-infrared (NIR) region for (6,5) SWNTs, as a function of nanotube length and exciton density, reveal that over time delays that exceed 200 fs exciton-exciton interactions do not occur over spatial domains larger than 200 nm. Furthermore, the excitation fluence dependence of the E11 → E11,BX transient absorption signal demonstrates that relaxation of the E11 biexciton state (E11,BX) gives rise to a substantial E11 state population, as increasing delay times result in a concomitant increase of E11 → E11,BX transition oscillator strength. Numerical simulations based on a three-state model are consistent with a mechanism whereby biexcitons are generated at high excitation fluences via sequential SWNT ground- and E11-state excitation that occurs within the 980 nm excitation pulse duration. These studies that investigate fluence-dependent TA spectral evolution show that SWNT ground → E11 and E11 → E11,BX excitations are coresonant and provide evidence that E11,BX → E11 relaxation constitutes a significant decay channel for the SWNT biexciton state over delay times that exceed 200 fs, a finding that runs counter to assumptions made in previous

The effects of single-walled carbon nanotubes on cancer cell migration using a pancreatic tumor model

NASA Astrophysics Data System (ADS)

Layton, Elivia; McNamar, Rachel; Hasanjee, Aamr M.; McNair, Cayman; Stevens, Brianna; Vaughan, Melville; Zhou, Feifan; Chen, Wei R.

2017-02-01

Non-invasive laser immunotherapy (NLIT) is a viable alternative to traditional cancer treatment because it combines the photothermal and immunological effects of non-invasive laser irradiation and single-walled carbon nanotubes (SWNT) with an immunoadjuvant, glycated chitosan (GC). This combination forms SWNT-GC, a photosensitive immunoadjuvant, which creates a tumor-specific immunity that targets both the primary tumor and any metastasis. It is known that NLIT induces anti-tumor as well as anti-metastatic immune responses, but its immunological mechanism is not clear. The objective of this study is to clarify the role of SWNT-GC in cancer cell migration. Panc02 (non-metastatic) and Panc02-H7 (metastatic) pancreatic cancer cells were used in two-dimensional elastomer plug assays to observe the restriction of cell migration induced by SWNT, GC, and SWNT-GC individually. To replicate a three-dimensional in vivo study, a similar assay was repeated using embedded collagen lattices. Both the 2D and the 3D studies confirmed previous results indicating that GC inhibits cancer cell motility. The 2D and 3D studies also showed that SWNT-GC inhibited the migration of cancer cells, but a discrepancy was observed regarding the effect of SWNT alone. The 2D model concluded that SWNT inhibited migration while the 3D model determined that SWNT promoted migration. The results of this study will guide future work to determine the mechanism behind NLIT, including how metastases are eradicated and how the tumor specific immunity is created.

Investigation on Single-walled Carbon Nanotubes-Liposomes Conjugate to Treatment Tumor with Dual-mechanism.

PubMed

Zhu, Xiali; Huang, Heqing; Zhang, Yingjie; Xie, Yingxia; Hou, Lin; Zhang, Huijuan; Zhang, Zhenzhong

2015-01-01

Single-walled carbon nanotubes (SWNT) have been widely explored as carriers for drug delivery because of their large surface area, high near-infrared absorption coefficient and facile transport through cellular membranes. In this study, Lysine (Lys) modified SWNT-liposomes conjugate loaded with doxorubicin (DOX) was designed to enhance the targeted drug delivery and antitumor effect. The conjugate (DOX-Lys/SWNT-Lip) was prepared with pH gradient methods, and the mean particle size and drug entrapment efficiency were 223±5.9 nm and 85.9 %, respectively. In vitro drug release study showed that DOX released much slowly from DOX-Lys/SWNT-Lip than from DOX solution, but faster than that of DOX-Lys/SWNT. DOX-Lys/SWNT-Lip could efficiently cross the cell membrane and afford higher anti-tumor efficacy on MCF-7 cells in vitro. For in vivo experiment, normal saline (N.S.), and DOX or DOX-Lys/SWNTLip were given to the S180 tumor bearing mice by i.v. administration, and followed by exposing the tumor site to nearinfrared laser (NIR) irradiation at 808 nm for 2 min. The relative tumor volumes in DOX-Lys/SWNT-Lip group and DOX group were obviously smaller than those of N.S. group. When combined with NIR laser irradiation, the suppression on tumor growth was much stronger. In conclusion, this study may provide potentially viable clinical strategies for tumor treatment with chemotherapy and photothermal therapy dual-mechanism.

High-resolution TEM Studies of Carbon Nanotubes and Catalyst Nanoparticles Produced During CVD from Metal Multilayer Films

NASA Astrophysics Data System (ADS)

Howe, Jane Y.; Puretzky, Alex A.; Geohegan, David B.; Cui, Hongtao; Eres, Varela; Maria, Alex A.; Lowndes, Douglas H.

2003-03-01

The structure of single-wall and multiwall carbon nanotubes and associated metal catalyst nanoparticles produced during chemical vapor deposition from multilayered metal films deposited on Si and Mo substrates were studied by high-resolution TEM and EDS. Electron beam-evaporated metal multilayer films (e.g. Al-Fe-Mo, typically 11-50 nm total thickness) roughen upon heat treatment to form a variety of catalyst particle sizes suitable for carbon nanotube growth by chemical vapor deposition using acetylene, hydrogen, and argon flow gases. This study investigates these nanoparticles, the type of nanotubes grown, their wall, tip, and basal structures, as well as the associated amounts of amorphous carbon deposited on their walls in different temperature and pressure ranges. Mixtures of SWNT and MWNT are found even for low growth temperatures (650-700 C), while rapid growth of vertically-aligned multiwall nanotubes (VA-MWNTs) predominate in a narrow temperature range at a given pressure. Arrested growth experiments were performed to determine the time periods for SWNT vs. MWNT growth. The nature of the catalyst nanoparticles, their support structure, and insights on the mechanisms of growth will be discussed.

Direct comparison of single- and multi-walled carbon nanotubes in fluorescence quenching phenomenon

NASA Astrophysics Data System (ADS)

Oura, Shusuke; Umemura, Kazuo

2018-03-01

Here, we report the fluorescence quenching ability of single-stranded DNA (ssDNA)-wrapped single- and multi-walled carbon nanotubes (ssDNA-SWNTs and ssDNA-MWNTs, respectively) using fluorescein dye-labeled ssDNA (Fluor-ssDNA). To compare the quenching abilities of SWNTs and MWNTs, we measured the quenching ratios of fluorescence emission from fluorescein when Fluor-ssDNA reacted with the hybrids of 30-mers of thymine (T30) and SWNTs or MWNTs (T30-SWNTs and T30-MWNTs, respectively). The fluorescence quenching ratios of Fluor-T30 in SWNT and MWNT samples were 28 ± 3.1 and 36 ± 2.0% relative to free fluorescein at the same concentration, respectively. On the other hand, those of Fluor-A30 with SWNT and MWNT hybrids were 11 ± 1.9 and 32 ± 1.9%, respectively. Our results suggest that although the fluorescence quenching ability of MWNT was greater than that of SWNT, SWNT quenching ratios were more sensitive to the base sequences of Fluor-ssDNA.

Separation of Semiconducting Carbon Nanotubes for Flexible and Stretchable Electronics Using Polymer Removable Method.

PubMed

Lei, Ting; Pochorovski, Igor; Bao, Zhenan

2017-04-18

Electronics that are soft, conformal, and stretchable are highly desirable for wearable electronics, prosthetics, and robotics. Among the various available electronic materials, single walled carbon nanotubes (SWNTs) and their network have exhibited high mechanical flexibility and stretchability, along with comparable electrical performance to traditional rigid materials, e.g. polysilicon and metal oxides. Unfortunately, SWNTs produced en masse contain a mixture of semiconducting (s-) and metallic (m-) SWNTs, rendering them unsuitable for electronic applications. Moreover, the poor solubility of SWNTs requires the introduction of insulating surfactants to properly disperse them into individual tubes for device fabrication. Compared to other SWNT dispersion and separation methods, e.g., DNA wrapping, density gradient ultracentrifugation, and gel chromatography, polymer wrapping can selectively disperse s-SWNTs with high selectivity (>99.7%), high concentration (>0.1 mg/mL), and high yield (>20%). In addition, this method only requires simple sonication and centrifuge equipment with short processing time down to 1 h. Despite these advantages, the polymer wrapping method still faces two major issues: (i) The purified s-SWNTs usually retain a substantial amount of polymers on their surface even after thorough rinsing. The low conductivity of the residual polymers impedes the charge transport in SWNT networks. (ii) Conjugated polymers used for SWNT wrapping are expensive. Their prices ($100-1000/g) are comparable or even higher than those of SWNTs ($10-300/g). These utilized conjugated polymers represent a large portion of the overall separation cost. In this Account, we summarize recent progresses in polymer design for selective dispersion and separation of SWNTs. We focus particularly on removable and/or recyclable polymers that enable low-cost and scalable separation methods. First, different separation methods are compared to show the advantages of the polymer

Realizing one-dimensional quantum and high-frequency transport features in aligned single-walled carbon nanotube ropes

NASA Astrophysics Data System (ADS)

Ncube, Siphephile; Chimowa, George; Chiguvare, Zivayi; Bhattacharyya, Somnath

2014-07-01

The superiority of the electronic transport properties of single-walled carbon nanotube (SWNT) ropes over SWNT mats is verified from low temperature and frequency-dependent transport. The overall change of resistance versus in nanotube mats shows that 3D variable range hopping is the dominant conduction mechanism within the 2-300 K range. The magneto-resistance (MR) is found to be predominantly negative with a parabolic nature, which can also be described by the hopping model. Although the positive upturn of the MR at low temperatures establishes the contribution from quantum interference, the inherent quantum transport in individual tubes is suppressed at elevated temperatures. Therefore, to minimize multi-channel effects from inter-tube interactions and other defects, two-terminal devices were fabricated from aligned SWNT (extracted from a mat) for low temperature transport as well as high-frequency measurements. In contrast to the mat, the aligned ropes exhibit step-like features in the differential conductance within the 80-300 K temperature range. The effects of plasmon propagation, unique to one dimension, were identified in electronic transport as a non-universal power-law dependence of the differential conductance on temperature and source-drain voltage. The complex impedance showed high power transmission capabilities up to 65 GHz as well as oscillations in the frequency range up to 30 GHz. The measurements suggest that aligned SWNT ropes have a realistic potential for high-speed device applications.

Thermodynamics on Soluble Carbon Nanotubes: How Do DNA Molecules Replace Surfactants on Carbon Nanotubes?

PubMed Central

Kato, Yuichi; Inoue, Ayaka; Niidome, Yasuro; Nakashima, Naotoshi

2012-01-01

Here we represent thermodynamics on soluble carbon nanotubes that enables deep understanding the interactions between single-walled carbon nanotubes (SWNTs) and molecules. We selected sodium cholate and single-stranded cytosine oligo-DNAs (dCn (n = 4, 5, 6, 7, 8, 10, 15, and 20)), both of which are typical SWNT solubilizers, and successfully determined thermodynamic properties (ΔG, ΔH and ΔS values) for the exchange reactions of sodium cholate on four different chiralities of SWNTs ((n,m) = (6,5), (7,5), (10,2), and (8,6)) for the DNAs. Typical results contain i) the dC5 exhibited an exothermic exchange, whereas the dC6, 8, 10, 15, and 20 materials exhibited endothermic exchanges, and ii) the energetics of the dC4 and dC7 exchanges depended on the associated chiral indices and could be endothermic or exothermic. The presented method is general and is applicable to any molecule that interacts with nanotubes. The study opens a way for science of carbon nanotube thermodynamics. PMID:23066502

Investigation of Aromatic/Aliphatic Polyimides as Dispersants for Single Wall Carbon Nanotubes

NASA Technical Reports Server (NTRS)

Delozier, Donavon M.; Watson, Kent A.; Smith, Joseph G., Jr.; Clancy, Thomas C.; Connell, John W.

2006-01-01

Novel aromatic/aliphatic polyimides were prepared from 2,7-diamino-9,9'- dioctylfluorene (AFDA) and aromatic dianhydrides. Upon investigating the effectiveness of these polyimides for dispersing single wall carbon nanotubes (SWNTs) in solution, three were discovered to disperse SWNTs in N,N-dimethylacetamide (DMAc). Two of these polyimides, one from 3,3',4,4'-oxydiphthalic anhydride (ODPA) and one from symmetric 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA), were used to prepare nanocomposites. Homogeneous polyimide/SWNT suspensions from both polymers were used in the preparation of films and fibers containing up to 1 wt% SWNTs. The samples were thermally treated to remove residual solvent and the films were characterized for SWNT dispersion by optical and high resolution scanning electron microscopy (HRSEM). Electrical and mechanical properties of the films were also determined. Electrospun fibers were examined by HRSEM to characterize SWNT alignment and orientation.

Highly Selective Photothermal Therapy by a Phenoxylated-Dextran-Functionalized Smart Carbon Nanotube Platform.

PubMed

Han, Seungmin; Kwon, Taeyun; Um, Jo-Eun; Haam, Seungjoo; Kim, Woo-Jae

2016-05-01

Near-infrared (NIR) photothermal therapy using biocompatible single-walled carbon nanotubes (SWNTs) is advantageous because as-produced SWNTs, without additional size control, both efficiently absorb NIR light and demonstrate high photothermal conversion efficiency. In addition, covalent attachment of receptor molecules to SWNTs can be used to specifically target infected cells. However, this technique interrupts SWNT optical properties and inevitably lowers photothermal conversion efficiency and thus remains major hurdle for SWNT applications. This paper presents a smart-targeting photothermal therapy platform for inflammatory disease using newly developed phenoxylated-dextran-functionalized SWNTs. Phenoxylated dextran is biocompatible and efficiently suspends SWNTs by noncovalent π-π stacking, thereby minimizing SWNT bundle formations and maintaining original SWNT optical properties. Furthermore, it selectively targets inflammatory macrophages by scavenger-receptor binding without any additional receptor molecules; therefore, its preparation is a simple one-step process. Herein, it is experimentally demonstrated that phenoxylated dextran-SWNTs (pD-SWNTs) are also biocompatible, selectively penetrate inflammatory macrophages over normal cells, and exhibit high photothermal conversion efficiency. Consequently, NIR laser-triggered macrophage treatment can be achieved with high accuracy by pD-SWNT without damaging receptor-free cells. These smart targeting materials can be a novel photothermal agent candidate for inflammatory disease. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fine Structure of the Low-Frequency Raman Phonon Bands of Single-Wall Carbon Nanotubes

NASA Technical Reports Server (NTRS)

Iliev, M. N.; Litvinchuk, A. P.; Arepalli, S.; Nikolaev, P.; Scott, C. D.

1999-01-01

The Raman spectra of singled-wall carbon nanotubes (SWNT) produced by laser and are process were studied between 5 and 500 kappa. The line width vs. temperature dependence of the low-frequency Raman bands between 150 and 200/ cm deviates from that expected for phonon decay through phonon-phonon scattering mechanism. The experimental results and their analysis provided convincing evidence that each of the low-frequency Raman lines is a superposition of several narrower Raman lines corresponding to tubes of nearly the same diameter. The application of Raman spectroscopy to probe the distribution of SWNT by both diameter and chirality is discussed.

THE EFFECTS OF FUNCTIONALIZED AND NON-FUNCTIONALIZED CARBON NANOTUBES ON ROOT ELONGATION OF SELECTED CROP SPECIES

EPA Science Inventory

Single-walled carbon nanotubes (SWNT) have many potential beneficial uses with additional applications constantly being investigated. However, these unique properties create a potential cause for concern of toxicity, not only in humans and animals, but also in plants. Root elong...

Fabrication of porous chitosan/poly(vinyl alcohol) reinforced single-walled carbon nanotube nanocomposites for neural tissue engineering.

PubMed

Shokrgozar, Mohammad Ali; Mottaghitalab, Fatemeh; Mottaghitalab, Vahid; Farokhi, Mehdi

2011-04-01

With the ability to form a nano-sized fibrous structure with large pore sizes mimicking the extracellular matrix (ECM), electrospinning was used to fabricate chitosan/poly(vinyl alcohol) nanofibers reinforced by single-walled carbon nanotube (SWNT-CS/PVA) for potential use in neural tissue engineering. Moreover, ultrasonication was performed to fabricate highly dispersed SWNT/CS solution with 7%, 12%, and 17% SWNT content prior to electrospinning process. In the present study, a number of properties of CS/PVA reinforced SWNTs nanocomposites were evaluated. The in vitro biocompatibility of the electrospun fiber mats was also assessed using human brain-derived cells and U373 cell lines. The results have shown that SWNTs as reinforcing phase can augment the morphology, porosity, and structural properties of CS/PVA nanofiber composites and thus benefit the proliferation rate of both cell types. In addition, the cells exhibit their normal morphology while integrating with surrounding fibers. The results confirmed the potential of SWNT-CS/PVA nanocomposites as scaffold for neural tissue engineering.

Encapsulate-and-peel: fabricating carbon nanotube CMOS integrated circuits in a flexible ultra-thin plastic film.

PubMed

Gao, Pingqi; Zhang, Qing

2014-02-14

Fabrication of single-walled carbon nanotube thin film (SWNT-TF) based integrated circuits (ICs) on soft substrates has been challenging due to several processing-related obstacles, such as printed/transferred SWNT-TF pattern and electrode alignment, electrical pad/channel material/dielectric layer flatness, adherence of the circuits onto the soft substrates etc. Here, we report a new approach that circumvents these challenges by encapsulating pre-formed SWNT-TF-ICs on hard substrates into polyimide (PI) and peeling them off to form flexible ICs on a large scale. The flexible SWNT-TF-ICs show promising performance comparable to those circuits formed on hard substrates. The flexible p- and n-type SWNT-TF transistors have an average mobility of around 60 cm(2) V(-1) s(-1), a subthreshold slope as low as 150 mV dec(-1), operating gate voltages less than 2 V, on/off ratios larger than 10(4) and a switching speed of several kilohertz. The post-transfer technique described here is not only a simple and cost-effective pathway to realize scalable flexible ICs, but also a feasible method to fabricate flexible displays, sensors and solar cells etc.

Polymer-Single Wall Carbon Nanotube Composites for Potential Spacecraft Applications

NASA Technical Reports Server (NTRS)

Park, C.; Ounaies, Z.; Watson, K. A.; Pawlowski, K.; Lowther, S. E.; Connell, J. W.; Siochi, E. J.; Harrison, J. S.; St.Clair, T. L.; Bushnell, Dennis M. (Technical Monitor)

2002-01-01

Polymer-single wall carbon nanotube (SWNT) composite films were prepared and characterized as part of an effort to develop polymeric materials with improved combinations of properties for potential use on future spacecraft. Next generation spacecraft will require ultra-lightweight materials that possess specific and unique combinations of properties such as radiation and atomic oxygen resistance, low solar absorptivity, high thermal emissitivity, electrical conductivity, tear resistance, ability to be folded and seamed, and good mechanical properties. The objective of this work is to incorporate sufficient electrical conductivity into space durable polyimides to mitigate static charge build-up. The challenge is to obtain this level of conductivity (10(exp -8) S/cm) without degrading other properties of importance, particularly optical transparency. Several different approaches were attempted to fully disperse the SWNTs into the polymer matrix. These included high shear mixing, sonication, and synthesizing the polymers in the presence of pre-dispersed SWNTs. Acceptable levels of conductivity were obtained at loading levels less than one tenth weight percent SWNT without significantly sacrificing optical properties. Characterization of the nanocomposite films and the effect of SWNT concentration and dispersion on the conductivity, solar absorptivity, thermal emissivity, mechanical and thermal properties were discussed. Fibers and non-woven porous mats of SWNT reinforced polymer nanocomposite were produced using electrospinning.

Adsorption studies of simple gases on As-produced single-walled carbon nanotubes

NASA Astrophysics Data System (ADS)

Talapatra, Saikat

Adsorption isotherms measurements were used to study films of Xenon (Xe), Argon (Ar), Methane (CH4), Hydrogen (H2) and Neon (Ne) adsorbed on bundles of as-produced Single Walled Carbon Nanotubes (SWNT). A comparison of the specific surface areas of the SWNT samples measured with these various gases, as well as a comparison of the binding energies measured for each of them on the SWNT bundles; allows us to infer which of the possible groups of adsorption sites on the SWNT bundles are actually occupied by the adsorbed gases. The presence of substeps in the first layer isotherm data establishes the existence of different phases within the first layer film. A detailed comparison of our experimental results to recent computer simulations for these systems is done. This allows us to determine the nature of the phases present in the first layer. Evidence of the formation of a one-dimensional phase in the second layer film (i.e. the film that forms after the entire surface of the bundles is covered by one layer of gas) is observed in these studies. The sharpness of this second layer feature varies as a function of the molecular diameter of the adsorbate.

Nanomechanics modeling of carbon nanotubes interacting with surfaces in various configurations

NASA Astrophysics Data System (ADS)

Wu, Yu-Chiao

Carbon nanotubes (CNTs) have been widely used as potential components in reported nanoelectromechanical (NEM) devices due to their excellent mechanical and electrical properties. This thesis models the experiments by the continuum mechanics in two distinct scenarios. In the first situation, measurements are made of CNT configurations after manipulations. Modeling is then used to determine the interfacial properties during the manipulation which led to the observed configuration. This technique is used to determine the shear stress between a SWNT bundle and other materials. During manipulation, a SWNT bundle slipped on two micro-cantilevers. According to the slack due to the slippage after testing and the device configuration, the shear stress between a SWNT bundle and other materials can be determined. In another model, the work of adhesion was determined on two accidentally fabricated devices. Through the configuration of two SWNT adhered bundles and the force-distance curves measured by an atomic force microscope (AFM), modeling was used to determine the work of adhesion between two bundles and the shear stress at the SWNT-substrate interface. In the second situation, modeling is used in a more traditional fashion to make theoretical predictions as to how a device will operate. Using this technique, the actuation mechanism of a single-trench SWNT-based switch was investigated. During the actuation, the deflection-induced tension causes the SWNT bundle to slip on both platforms and to be partially peeled from two side recessed electrodes. These effects produce a slack which reduces the threshold voltages subsequent to the first actuation. The result shows excellent agreement between the theory and the measurement. Furthermore, the operation of a double-trenched SWNT-based switch was investigated. A slack is produced in the 1st actuated trench region by the slip and peeling effects. This slack reduces the 2nd actuation voltage in the neighbor trench. Finally, the

Detection of α-fetoprotein in human serum using carbon nanotube transistor

NASA Astrophysics Data System (ADS)

So, Hye-Mi; Park, Dong-Won; Lee, Seong-Kyu; Kim, Beom Soo; Chang, Hyunju; Lee, Jeong-O.

2009-03-01

We have fabricated antibody-coated carbon nanotube field effect transistor (CNT-FET) sensor for the detection of α-fetoprotein (AFP), single chain glycoprotein of 70 kDa that is normally expressed in the fetal liver, in human serum. The AFP-specific antibodies were immobilized on CNT with linker molecule such as pyrenebutyric acid N-hydroxysuccinimide ester. To prevent nonspecific adsorption of antigen, we performed blocking procedure using bovine serum albumin (BSA). Antibody-antigen binding was determined by measuring electrical conductance change of FET and took an average of thereshold voltage change before and after binding. Also we checked concentration-dependent conductance change in human serum using both p-type SWNT-FETs and n-type SWNT-FETs.

Single molecule detection of nitric oxide enabled by d(AT)15 DNA adsorbed to near infrared fluorescent single-walled carbon nanotubes.

PubMed

Zhang, Jingqing; Boghossian, Ardemis A; Barone, Paul W; Rwei, Alina; Kim, Jong-Ho; Lin, Dahua; Heller, Daniel A; Hilmer, Andrew J; Nair, Nitish; Reuel, Nigel F; Strano, Michael S

2011-01-26

We report the selective detection of single nitric oxide (NO) molecules using a specific DNA sequence of d(AT)(15) oligonucleotides, adsorbed to an array of near-infrared fluorescent semiconducting single-walled carbon nanotubes (AT(15)-SWNT). While SWNT suspended with eight other variant DNA sequences show fluorescence quenching or enhancement from analytes such as dopamine, NADH, L-ascorbic acid, and riboflavin, d(AT)(15) imparts SWNT with a distinct selectivity toward NO. In contrast, the electrostatically neutral polyvinyl alcohol enables no response to nitric oxide, but exhibits fluorescent enhancement to other molecules in the tested library. For AT(15)-SWNT, a stepwise fluorescence decrease is observed when the nanotubes are exposed to NO, reporting the dynamics of single-molecule NO adsorption via SWNT exciton quenching. We describe these quenching traces using a birth-and-death Markov model, and the maximum likelihood estimator of adsorption and desorption rates of NO is derived. Applying the method to simulated traces indicates that the resulting error in the estimated rate constants is less than 5% under our experimental conditions, allowing for calibration using a series of NO concentrations. As expected, the adsorption rate is found to be linearly proportional to NO concentration, and the intrinsic single-site NO adsorption rate constant is 0.001 s(-1) μM NO(-1). The ability to detect nitric oxide quantitatively at the single-molecule level may find applications in new cellular assays for the study of nitric oxide carcinogenesis and chemical signaling, as well as medical diagnostics for inflammation.

Aligned Single Wall Carbon Nanotube Polymer Composites Using an Electric Field

NASA Technical Reports Server (NTRS)

Park, Cheol; Wiklinson, John; Banda, Sumanth; Ounaies, Zoubeida; Wise, Kristopher E.; Sauti, Godfrey; Lillehei, Peter T.; Harrison, Joycelyn S.

2005-01-01

While high shear alignment has been shown to improve the mechanical properties of single wall carbon nanotubes (SWNT)-polymer composites, it is difficult to control and often results in degradation of the electrical and dielectric properties of the composite. Here, we report a novel method to actively align SWNTs in a polymer matrix, which allows for control over the degree of alignment of SWNTs without the side effects of shear alignment. In this process, SWNTs are aligned via field-induced dipolar interactions among the nanotubes under an AC electric field in a liquid matrix followed by immobilization by photopolymerization while maintaining the electric field. Alignment of SWNTs was controlled as a function of magnitude, frequency, and application time of the applied electric field. The degree of SWNT alignment was assessed using optical microscopy and polarized Raman spectroscopy and the morphology of the aligned nanocomposites was investigated by high resolution scanning electron microscopy. The structure of the field induced aligned SWNTs is intrinsically different from that of shear aligned SWNTs. In the present work, SWNTs are not only aligned along the field, but also migrate laterally to form thick, aligned SWNT percolative columns between the electrodes. The actively aligned SWNTs amplify the electrical and dielectric properties in addition to improving the mechanical properties of the composite. All of these properties of the aligned nanocomposites exhibited anisotropic characteristics, which were controllable by tuning the applied field conditions.

Electrical behaviour of carbon nanotubes under low-energy proton irradiation

NASA Astrophysics Data System (ADS)

Abbe, Elisabeth; Schüler, Tilman; Klosz, Stefan; Starruß, Elisa; Pilz, Wolfgang; Böttger, Roman; Kluge, Oliver; Schmiel, Tino; Tajmar, Martin

2017-11-01

Several applications for carbon nanotubes (CNT) have been proposed for space applications in the last years. However, their behaviour in the harsh space environment is mostly unknown. Energetic particles such as protons can influence the material degradation in space. This material damage could result in a system failure of space systems. Therefore it is necessary to investigate the performance of new materials under proton irradiation. Screen and jet printed disordered single-walled carbon nanotubes (SWNT), multi-walled carbon nanotubes (MWNT) and multi-walled carbon nanotubes/resin composites (ME) were exposed to 1 keV, 15 keV and 100 keV protons. The electrical behaviour of the CNT conductor paths was measured during the experiment. After this exposure, the CNTs were analyzed using Raman scattering and a scanning electron microscope (SEM). Their is a clear evidence that proton radiation can destroy carbon nanotubes and influence their electrical performance.

A Facile Route to Metal Oxides/Single-Walled Carbon Nanotube Macrofilm Nanocomposites for Energy Storage

NASA Astrophysics Data System (ADS)

Cao, Zeyuan; Wei, Bingqing

2015-05-01

Nanocomposites consisting of transition-metal oxides and carbon nanomaterials with a desired size and structure are highly demanded for high performance energy storage devices. Here, a facile two-step and cost-efficient approach relying on directly thermal treatment of chemical-vapor-deposition products is developed as a general synthetic method to prepare a family of metal oxides (MxOy (M=Fe, Co, Ni))/single-walled carbon nanotube (SWNT) macrofilm nanocomposites. The MxOy nanoparticles obtained are of 3-17 nm in diameter and homogeneously anchor on the free-standing SWNT macrofilms. NiO/SWNT also exhibits a high specific capacitance of 400 F g-1 and fast charge-transfer Faradaic redox reactions to achieve asymmetric supercapacitors with a high power and energy density. All MxOy/SWNT nanocomposites could deliver a high capacity beyond 1000 mAh g-1 and show excellent cycling stability for lithium-ion batteries. The impressive results demonstrate the promise for energy storage devices and the general approach may pave the way to synthesize other functional nanocomposites.

Probing Biological Processes on Supported Lipid Bilayers with Single-Walled Carbon Nanotube Field-Effect Transistors

NASA Astrophysics Data System (ADS)

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

2006-03-01

We have formed supported lipid bilayers (SLBs) by small unilamellar vesicle fusion on substrates containing single-walled carbon nanotube field-effect transistors (SWNT-FETs). We are able to detect the self-assembly of SLBs electrically with SWNT-FETs since their threshold voltages are shifted by this event. The SLB fully covers the NT surface and lipid molecules can diffuse freely in the bilayer surface across the NT. To study the interactions of important biological entities with receptors imbedded within the membrane, we have also integrated a membrane protein, GT1b ganglioside, in the bilayer. While bare gangliosides can diffuse freely across the NT, interestingly the NT acts as a diffusion barrier for the gangliosides when they are bound with tetanus toxin. This experiment opens the possibility of using SWNT-FETs as biosensors for label-free detection.

Transparent and flexible electrodes and supercapacitors using polyaniline/single-walled carbon nanotube composite thin films

NASA Astrophysics Data System (ADS)

Ge, Jun; Cheng, Guanghui; Chen, Liwei

2011-08-01

Large-scale transparent and flexible electronic devices have been pursued for potential applications such as those in touch sensors and display technologies. These applications require that the power source of these devices must also comply with transparent and flexible features. Here we present transparent and flexible supercapacitors assembled from polyaniline (PANI)/single-walled carbon nanotube (SWNT) composite thin film electrodes. The ultrathin, optically homogeneous and transparent, electrically conducting films of the PANI/SWNT composite show a large specific capacitance due to combined double-layer capacitance and pseudo-capacitance mechanisms. A supercapacitor assembled using electrodes with a SWNT density of 10.0 µg cm-2 and 59 wt% PANI gives a specific capacitance of 55.0 F g-1 at a current density of 2.6 A g-1, showing its possibility for transparent and flexible energy storage.

Scalable Fabrication of High-Performance Transparent Conductors Using Graphene Oxide-Stabilized Single-Walled Carbon Nanotube Inks

PubMed Central

He, Linxiang; Liao, Chengzhu

2018-01-01

Recent development in liquid-phase processing of single-walled carbon nanotubes (SWNTs) has revealed rod-coating as a promising approach for large-scale production of SWNT-based transparent conductors. Of great importance in the ink formulation is the stabilizer having excellent dispersion stability, environmental friendly and tunable rheology in the liquid state, and also can be readily removed to enhance electrical conductivity and mechanical stability. Herein we demonstrate the promise of graphene oxide (GO) as a synergistic stabilizer for SWNTs in water. SWNTs dispersed in GO is formulated into inks with homogeneous nanotube distribution, good wetting and rheological properties, and compatible with industrial rod coating practice. Microwave treatment of rod-coated films can reduce GOs and enhance electro-optical performance. The resultant films offer a sheet resistance of ~80 Ω/sq at 86% transparency, along with good mechanical flexibility. Doping the films with nitric acid can further decrease the sheet resistance to ~25 Ω/sq. Comparing with the films fabricated from typical surfactant-based SWNT inks, our films offer superior adhesion as assessed by the Scotch tape test. This study provides new insight into the selection of suitable stabilizers for functional SWNT inks with strong potential for printed electronics. PMID:29642446

Conducting polymer functionalized single-walled carbon nanotube based chemiresistive biosensor for the detection of human cardiac myoglobin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Puri, Nidhi; Department of Physics, Faculty of Natural Sciences, Jamia Millia Islamia, New Delhi 110025; Niazi, Asad

2014-10-13

We report the fabrication of a single-walled carbon nanotube (SWNT) based ultrasensitive label-free chemiresistive biosensor for the detection of human cardiac biomarker, myoglobin (Ag-cMb). Poly(pyrrole-co-pyrrolepropylic acid) with pendant carboxyl groups was electrochemically deposited on electrophoretically aligned SWNT channel, as a conducting linker, for biomolecular immobilization of highly specific cardiac myoglobin antibody. The device was characterized by scanning electron microscopy, source-drain current-voltage (I-V), and charge-transfer characteristic studies. The device exhibited a linear response with a change in conductance in SWNT channel towards the target, Ag-cMb, over the concentration range of 1.0 to 1000 ng ml{sup −1} with a sensitivity of ∼118% per decademore » with high specificity.« less

Ultrasonic degradation of acetaminophen and naproxen in the presence of single-walled carbon nanotubes.

PubMed

Im, Jong-Kwon; Heo, Jiyong; Boateng, Linkel K; Her, Namguk; Flora, Joseph R V; Yoon, Jaekyung; Zoh, Kyung-Duk; Yoon, Yeomin

2013-06-15

Ultrasonic (US) and single-walled carbon nanotube (SWNT)-catalyzed ultrasonic (US/SWNT) degradation of a pharmaceutical (PhAC) mixture of acetaminophen (AAP) and naproxen (NPX) used as analgesics was carried out in water. In the absence of SWNTs, maximum degradations of AAP and NPX occurred at a high frequency (1000 kHz) and under acidic conditions (pH 3) and different solution temperatures (25 °C at 28 kHz and 35 °C at 1000 kHz) during US reactions. Rapid degradation of PhACs occurred within 10 min at 28 kHz (44.5% for AAP; 90.3% for NPX) and 1000 kHz (39.2% for AAP; 74.8% for NPX) at a SWNT concentration of 45 mgL(-1) under US/SWNT process, compared with 28 kHz (5.2% for AAP; 10.6% for NPX) and 1000 kHz (29.1% for AAP; 46.2% for NPX) under US process. Degradation was associated with the dispersion of SWNTs; small particles acted as nuclei during US reactions, enhancing the H2O2 production yield. NPX removal was greater than AAP removal under all US-induced reaction and SWNT adsorption conditions, which is governed by the chemical properties of PhACs. Based on the results, the optimal treatment performance was observed at 28 kHz with 45 mgL(-1) SWNTs (US/SWNT) within 10 min. Copyright © 2013 Elsevier B.V. All rights reserved.

High-Sensitivity, Broad-Range Vacuum Gauge Using Nanotubes for Micromachined Cavities

NASA Technical Reports Server (NTRS)

Manohara, Harish; Kaul, Anupama B.

2011-01-01

A broad-range vacuum gauge has been created by suspending a single-walled carbon nanotube (SWNT) (metallic or semiconducting) in a Schottky diode format or in a bridge conductor format, between two electrically charged mesas. SWNTs are highly sensitive to molecular collisions because of their extremely small diameters in the range of 1 to 3 nanometers. The measurement parameter will be the change in conductivity of SWNT due to decreasing rate of molecular collisions as the pressure inside a chamber decreases. The rate of heat removal approaches a saturation limit as the mean free path (m.f.p.) lengths of molecules increase due to decreasing pressure. Only those sensing elements that have a long relaxation time can produce a measureable response when m.f.p. of molecules increases (or time between two consecutive collisions increases). A suspended SWNT offers such a capability because of its one-dimensional nature and ultrasmall diameter. In the initial approach, similar architecture was used as that of a SWNT-Schottky diode that has been developed at JPL, and has its changing conductivity measured as the test chamber is pumped down from atmospheric pressure to high vacuum (10(exp -7) Torr). Continuous response of decreasing conductivity has been measured as a function of decreasing pressure (SWNT is a negative thermal coefficient material) from atmosphere to less than 10(exp -6) Torr. A measureable current change in the hundreds of nA range has been recorded in the 10(exp -6) Torr regime.

CARBON NANOTUBES: PROPERTIES AND APPLICATIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fischer, John, E.

2009-07-24

Carbon nanotubes were discovered in 1991 as a minority byproduct of fullerene synthesis. Remarkable progress has been made in the ensuing years, including the discovery of two basic types of nanotubes (single-wall and multi-wall), great strides in synthesis and purification, elucidation of many fundamental physical properties, and important steps towards practical applications. Both the underlying science and technological potential of SWNT can profitably be studied at the scale of individual tubes and on macroscopic assemblies such as fibers. Experiments on single tubes directly reveal many of the predicted quantum confinement and mechanical properties. Semiconductor nanowires have many features in commonmore » with nanotubes, and many of the same fundamental and practical issues are in play – quantum confinement and its effect on properties; possible device structures and circuit architectures; thermal management; optimal synthesis, defect morphology and control, etc. In 2000 we began a small effort in this direction, conducted entirely by undergraduates with minimal consumables support from this grant. With DOE-BES approval, this grew into a project in parallel with the carbon nanotube work, in which we studied of inorganic semiconductor nanowire growth, characterization and novel strategies for electronic and electromechanical device fabrication. From the beginnings of research on carbon nanotubes, one of the major applications envisioned was hydrogen storage for fuel-cell powered cars and trucks. Subsequent theoretical models gave mixed results, the most pessimistic indicating that the fundamental H2-SWNT interaction was similar to flat graphite (physisorption) with only modest binding energies implying cryogenic operation at best. New material families with encouraging measured properties have emerged, and materials modeling has gained enormously in predictive power, sophistication, and the ability to treat a realistically representative number of atoms

Dynamic assembly of polymer nanotube networks via kinesin powered microtubule filaments

DOE PAGES

Paxton, Walter F.; Bachand, George D.; Gomez, Andrew; ...

2015-04-24

In this study, we describe for the first time how biological nanomotors may be used to actively self-assemble mesoscale networks composed of diblock copolymer nanotubes. The collective force generated by multiple kinesin nanomotors acting on a microtubule filament is large enough to overcome the energy barrier required to extract nanotubes from polymer vesicles comprised of poly(ethylene oxide-b-butadiene) in spite of the higher force requirements relative to extracting nanotubes from lipid vesicles. Nevertheless, large-scale polymer networks were dynamically assembled by the motors. These networks displayed enhanced robustness, persisting more than 24 h post-assembly (compared to 4–5 h for corresponding lipid networks).more » The transport of materials in and on the polymer membranes differs substantially from the transport on analogous lipid networks. Specifically, our data suggest that polymer mobility in nanotubular structures is considerably different from planar or 3D structures, and is stunted by 1D confinement of the polymer subunits. Moreover, quantum dots adsorbed onto polymer nanotubes are completely immobile, which is related to this 1D confinement effect and is in stark contrast to the highly fluid transport observed on lipid tubules.« less

Synthesis of Single-walled Carbon Nanotubes Coated with Thiol-reactive Gel via Emulsion Polymerization.

PubMed

Nagai, Yukiko; Tsutsumi, Yusuke; Nakashima, Naotoshi; Fujigaya, Tsuyohiko

2018-06-15

Single-walled carbon nanotubes (SWNTs) have unique near-infrared absorption and photoemission properties that are attractive for in vivo biological applications such as photothermal cancer treatment and bioimaging. Therefore, a smart functionalization strategy for SWNTs to create biocompatible surfaces and introduce various ligands to target active cancer cells without losing the unique optical properties of the SWNTs is strongly desired. This paper reports the de-sign and synthesis of a SWNT/gel hybrid containing maleimide groups, which react with various thiol compounds through Michael addition reactions. In this hybrid, the method called carbon nanotube micelle polymerization was used to non-covalently modify the surface of SWNTs with a cross-linked polymer gel layer. This method can form an extremely stable gel layer on SWNTs; such stability is essential for in vivo biological applications. The monomer used to form the gel layer contained a maleimide group, which was protected with furan in endo-form. The resulting hybrid was treated in water to induce deprotection via retro Diels-Alder reaction and then functionalized with thiol com-pounds through Michael addition. The functionalization of the hybrid was explored using a thiol-containing fluores-cent dye as a model thiol and the formation of the SWNT-dye conjugate was confirmed by energy transfer from the dye to SWNTs. Our strategy offers a promising SWNT-based platform for biological functionalization for cancer targeting, imaging, and treatment.

Carbon nanotube network thin-film transistors on flexible/stretchable substrates

DOEpatents

Takei, Kuniharu; Takahashi, Toshitake; Javey, Ali

2016-03-29

This disclosure provides systems, methods, and apparatus for flexible thin-film transistors. In one aspect, a device includes a polymer substrate, a gate electrode disposed on the polymer substrate, a dielectric layer disposed on the gate electrode and on exposed portions of the polymer substrate, a carbon nanotube network disposed on the dielectric layer, and a source electrode and a drain electrode disposed on the carbon nanotube network.

Efficient room-temperature near-infrared detection with solution-processed networked single wall carbon nanotube field effect transistors.

PubMed

Hwang, Ihn; Jung, Hee June; Cho, Sung Hwan; Jo, Seong Soon; Choi, Yeon Sik; Sung, Ji Ho; Choi, Jae Ho; Jo, Moon Ho; Park, Cheolmin

2014-02-26

Efficient room temperature NIR detection with sufficient current gain is made with a solution-processed networked SWNT FET. The high performance NIR-FET with significantly enhanced photocurrent by more than two orders of magnitude compared to dark current in the depleted state is attributed to multiple Schottky barriers in the network, each of which absorb NIR and effectively separate photocarriers to corresponding electrodes. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Recycling Strategy for Fabricating Low-Cost and High-Performance Carbon Nanotube TFT Devices.

PubMed

Yu, Xiaoqin; Liu, Dan; Kang, Lixing; Yang, Yi; Zhang, Xiaopin; Lv, Qianjin; Qiu, Song; Jin, Hehua; Song, Qijun; Zhang, Jin; Li, Qingwen

2017-05-10

High-purity semiconducting single-walled carbon nanotubes (s-SWNTs) can be obtained by conjugated polymer wrapping. However, further purification of sorted s-SWNTs and high costs of raw materials are still challenges to practical applications. It is inevitable that a lot of polymers still cover the surface of s-SWNTs after separation, and the cost of the polymer is relatively higher than that of SWNTs. Here, we demonstrated a facile isolated process to improve the quality of s-SWNT solutions and films significantly. Compared with the untreated s-SWNTs, the contact resistance between the s-SWNT and the electrode is reduced by 20 times, and the thin-film transistors show 300% enhancement of current density. In this process, most of the polymers can be recycled and reused directly without any purification, which can greatly decrease the cost for s-SWNT separation. The results presented herein demonstrate a new scalable and low-cost approach for large-scale application of s-SWNTs in the electronics industry.

Transparent and flexible electrodes and supercapacitors using polyaniline/single-walled carbon nanotube composite thin films.

PubMed

Ge, Jun; Cheng, Guanghui; Chen, Liwei

2011-08-01

Large-scale transparent and flexible electronic devices have been pursued for potential applications such as those in touch sensors and display technologies. These applications require that the power source of these devices must also comply with transparent and flexible features. Here we present transparent and flexible supercapacitors assembled from polyaniline (PANI)/single-walled carbon nanotube (SWNT) composite thin film electrodes. The ultrathin, optically homogeneous and transparent, electrically conducting films of the PANI/SWNT composite show a large specific capacitance due to combined double-layer capacitance and pseudo-capacitance mechanisms. A supercapacitor assembled using electrodes with a SWNT density of 10.0 µg cm(-2) and 59 wt% PANI gives a specific capacitance of 55.0 F g(-1) at a current density of 2.6 A g(-1), showing its possibility for transparent and flexible energy storage. This journal is © The Royal Society of Chemistry 2011

Studying the Dependency of Interfacial Formation with Carbon Nanotube

DTIC Science & Technology

2014-08-27

PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND...duration of this project toward understanding the interfacial formation and dependency on SWNT and its relationship to the nanotube length. SECTION II...obtained from Kuraray America Inc. Dimethyl sulfoxide (DMSO) was purchased from Sigma -Aldrich Corporation (CAS# 67-68-5, lot# 472301). Methanol was

Preparation and properties of single-walled nanotubes filled with inorganic compounds

NASA Astrophysics Data System (ADS)

Eliseev, Andrei A.; Kharlamova, M. V.; Chernysheva, M. V.; Lukashin, Alexey V.; Tretyakov, Yuri D.; Kumskov, A. S.; Kiselev, N. A.

2009-09-01

The state-of-the-art methods for filling single-walled carbon nanotubes (SWNTs) are analyzed systematically. In situ and ex situ approaches for filling SWNTs are addressed. They are based on both intercalation of inorganic substances from the gas phase, solution or melts inside SWNTs and the formation of nanocrystals inside the channels as a result of chemical reactions. A comparative evaluation of these methods is performed, and major requirements for successful formation of '1D-crystal@SWNT' nanocomposites are formulated. The functional properties of the intercalated single-walled nanotubes and their possible applications in modern nanotechnologies are discussed.

Carbon Nanotube Microarrays Grown on Nanoflake Substrates

NASA Technical Reports Server (NTRS)

Schmidt, Howard K.; Hauge, Robert H.; Pint, Cary; Pheasant, Sean

2013-01-01

This innovation consists of a new composition of matter where single-walled carbon nanotubes (SWNTs) are grown in aligned arrays from nanostructured flakes that are coated in Fe catalyst. This method of growth of aligned SWNTs, which can yield well over 400 percent SWNT mass per unit substrate mass, exceeds current yields for entangled SWNT growth. In addition, processing can be performed with minimal wet etching treatments, leaving aligned SWNTs with superior properties over those that exist in entangled mats. The alignment of the nanotubes is similar to that achieved in vertically aligned nanotubes, which are called "carpets. " Because these flakes are grown in a state where they are airborne in a reactor, these flakes, after growing SWNTs, are termed "flying carpets. " These flakes are created in a roll-to-roll evaporator system, where three subsequent evaporations are performed on a 100-ft (approx. =30-m) roll of Mylar. The first layer is composed of a water-soluble "release layer, " which can be a material such as NaCl. After depositing NaCl, the second layer involves 40 nm of supporting layer material . either Al2O3 or MgO. The thickness of the layer can be tuned to synthesize flakes that are larger or smaller than those obtained with a 40-nm deposition. Finally, the third layer consists of a thin Fe catalyst layer with a thickness of 0.5 nm. The thickness of this layer ultimately determines the diameter of SWNT growth, and a layer that is too thick will result in the growth of multiwalled carbon nanotubes instead of single-wall nanotubes. However, between a thickness of 0.5 nm to 1 nm, single-walled carbon nanotubes are known to be the primary constituent. After this three-layer deposition process, the Mylar is rolled through a bath of water, which allows catalyst-coated flakes to detach from the Mylar. The flakes are then collected and dried. The method described here for making such flakes is analogous to that which is used to make birefringent ink that is

Tuning the threshold voltage of carbon nanotube transistors by n-type molecular doping for robust and flexible complementary circuits

PubMed Central

Wang, Huiliang; Wei, Peng; Li, Yaoxuan; Han, Jeff; Lee, Hye Ryoung; Naab, Benjamin D.; Liu, Nan; Wang, Chenggong; Adijanto, Eric; Tee, Benjamin C.-K.; Morishita, Satoshi; Li, Qiaochu; Gao, Yongli; Cui, Yi; Bao, Zhenan

2014-01-01

Tuning the threshold voltage of a transistor is crucial for realizing robust digital circuits. For silicon transistors, the threshold voltage can be accurately controlled by doping. However, it remains challenging to tune the threshold voltage of single-wall nanotube (SWNT) thin-film transistors. Here, we report a facile method to controllably n-dope SWNTs using 1H-benzoimidazole derivatives processed via either solution coating or vacuum deposition. The threshold voltages of our polythiophene-sorted SWNT thin-film transistors can be tuned accurately and continuously over a wide range. Photoelectron spectroscopy measurements confirmed that the SWNT Fermi level shifted to the conduction band edge with increasing doping concentration. Using this doping approach, we proceeded to fabricate SWNT complementary inverters by inkjet printing of the dopants. We observed an unprecedented noise margin of 28 V at VDD = 80 V (70% of 1/2VDD) and a gain of 85. Additionally, robust SWNT complementary metal−oxide−semiconductor inverter (noise margin 72% of 1/2VDD) and logic gates with rail-to-rail output voltage swing and subnanowatt power consumption were fabricated onto a highly flexible substrate. PMID:24639537

pH-controlled doxorubicin anticancer loading and release from carbon nanotube noncovalently modified by chitosan: MD simulations.

PubMed

Rungnim, Chompoonut; Rungrotmongkol, Thanyada; Poo-Arporn, Rungtiva P

2016-11-01

In the present study, we describe here the pH condition activating doxorubicin (DOX) anticancer drugs loading and release over single-wall carbon nanotube (SWNT) non-covalently wrapped with chitosan (CS). The possibility of drug displacement on DOX/CS/SWNT nanocarrier was investigated using molecular dynamics simulations. The drug loading and release were monitored via displacement analysis and binding energy calculations. The simulated results clearly showed that the drugs well interacted with the CS/SWNT at physiological pH (pH 7.4), where CS was in the deprotonated form. Contrastingly, in weakly acidic environments (pH 5.0-6.5) which is a pH characteristics of certain cancer environments, the protonated CS became loosen wrapped around the SWNT and triggered drugs release as a result of charge-charge repulsion between CS and drug molecules. The obtained data fulfil the understanding at atomic level of drug loading and release controlled by pH-sensitive polymer, which might be useful for further cancer therapy researches. Copyright © 2016 Elsevier Inc. All rights reserved.

New multifunctional porous materials based on inorganic-organic hybrid single-walled carbon nanotubes: gas storage and high-sensitive detection of pesticides.

PubMed

Wang, Feng; Zhao, Jinbo; Gong, Jingming; Wen, Lili; Zhou, Li; Li, Dongfeng

2012-09-10

Single-walled carbon nanotubes (SWNTs) that are covalently functionalized with benzoic acid (SWNT-PhCOOH) can be integrated with transition-metal ions to form 3D porous inorganic-organic hybrid frameworks (SWNT-Zn). In particular, N(2)-adsorption analysis shows that the BET surface area increases notably from 645.3 to 1209.9 m(2)  g(-1) for SWNTs and SWNT-Zn, respectively. This remarkable enhancement in the surface area of SWNT-Zn is presumably due to the microporous motifs from benzoates coordinated to intercalated zinc ions between the functionalized SWNTs; this assignment was also corroborated by NLDFT pore-size distributions. In addition, the excess-H(2)-uptake maximum of SWNT-Zn reaches about 3.1 wt. % (12 bar, 77 K), which is almost three times that of the original SWNTs (1.2 wt. % at 12 bar, 77 K). Owing to its inherent conductivity and pore structure, as well as good dispersibility, SWNT-Zn is an effective candidate as a sensitive electrochemical stripping voltammetric sensor for organophosphate pesticides (OPs): By using solid-phase extraction (SPE) with SWNT-Zn-modified glassy carbon electrode, the detection limit of methyl parathion (MP) is 2.3 ng mL(-1). Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Single-Walled Carbon Nanotubes in Solar Cells.

PubMed

Jeon, Il; Matsuo, Yutaka; Maruyama, Shigeo

2018-01-22

Photovoltaics, more generally known as solar cells, are made from semiconducting materials that convert light into electricity. Solar cells have received much attention in recent years due to their promise as clean and efficient light-harvesting devices. Single-walled carbon nanotubes (SWNTs) could play a crucial role in these devices and have been the subject of much research, which continues to this day. SWNTs are known to outperform multi-walled carbon nanotubes (MWNTs) at low densities, because of the difference in their optical transmittance for the same current density, which is the most important parameter in comparing SWNTs and MWNTs. SWNT films show semiconducting features, which make SWNTs function as active or charge-transporting materials. This chapter, consisting of two sections, focuses on the use of SWNTs in solar cells. In the first section, we discuss SWNTs as a light harvester and charge transporter in the photoactive layer, which are reviewed chronologically to show the history of the research progress. In the second section, we discuss SWNTs as a transparent conductive layer outside of the photoactive layer, which is relatively more actively researched. This section introduces SWNT applications in silicon solar cells, organic solar cells, and perovskite solar cells each, from their prototypes to recent results. As we go along, the science and prospects of the application of solar cells will be discussed.

Emergence of new red-shifted carbon nanotube photoluminescence based on proximal doped-site design

NASA Astrophysics Data System (ADS)

Shiraki, Tomohiro; Shiraishi, Tomonari; Juhász, Gergely; Nakashima, Naotoshi

2016-06-01

Single-walled carbon nanotubes (SWNTs) show unique photoluminescence (PL) in the near-infrared (NIR) region. Here we propose a concept based on the proximal modification in local covalent functionalization of SWNTs. Quantum mechanical simulations reveal that the SWNT band gap changes specifically based on the proximal doped-site design. Thus, we synthesize newly-designed bisdiazonium molecules and conduct local fucntionalisation of SWNTs. Consequently, new red-shifted PL (E112*) from the bisdiazonium-modified SWNTs with (6, 5) chirality is recognized around 1250 nm with over ~270 nm Stokes shift from the PL of the pristine SWNTs and the PL wavelengths are shifted depending on the methylene spacer lengths of the modifiers. The present study revealed that SWNT PL modulation is enable by close-proximity-local covalent modification, which is highly important for fundamental understanding of intrinsic SWNT PL properties as well as exciton engineering-based applications including photonic devices and (bio)imaging/sensing.

Emergence of new red-shifted carbon nanotube photoluminescence based on proximal doped-site design

PubMed Central

Shiraki, Tomohiro; Shiraishi, Tomonari; Juhász, Gergely; Nakashima, Naotoshi

2016-01-01

Single-walled carbon nanotubes (SWNTs) show unique photoluminescence (PL) in the near-infrared (NIR) region. Here we propose a concept based on the proximal modification in local covalent functionalization of SWNTs. Quantum mechanical simulations reveal that the SWNT band gap changes specifically based on the proximal doped-site design. Thus, we synthesize newly-designed bisdiazonium molecules and conduct local fucntionalisation of SWNTs. Consequently, new red-shifted PL (E112*) from the bisdiazonium-modified SWNTs with (6, 5) chirality is recognized around 1250 nm with over ~270 nm Stokes shift from the PL of the pristine SWNTs and the PL wavelengths are shifted depending on the methylene spacer lengths of the modifiers. The present study revealed that SWNT PL modulation is enable by close-proximity-local covalent modification, which is highly important for fundamental understanding of intrinsic SWNT PL properties as well as exciton engineering–based applications including photonic devices and (bio)imaging/sensing. PMID:27345862

A bioscaffolding strategy for hierarchical zeolites with a nanotube-trimodal network.

PubMed

Li, Guannan; Huang, Haibo; Yu, Bowen; Wang, Yun; Tao, Jiawei; Wei, Yingxu; Li, Shougui; Liu, Zhongmin; Xu, Yan; Xu, Ruren

2016-02-01

Hierarchical zeolite monoliths with multimodal porosity are of paramount importance as they open up new horizons for advanced applications. So far, hierarchical zeolites based on nanotube scaffolds have never been reported. Inspired by the organization of biominerals, we have developed a novel precursor scaffolding-solid phase crystallization strategy for hierarchical zeolites with a unique nanotube scaffolding architecture and nanotube-trimodal network, where biomolecular self-assembly (BSA) provides a scaffolding blueprint. By vapor-treating Sil-1 seeded precursor scaffolds, zeolite MFI nanotube scaffolds are self-generated, during which evolution phenomena such as segmented voids and solid bridges are observed, in agreement with the Kirkendall effect in a solid-phase crystallization system. The nanotube walls are made of intergrown single crystals rendering good mechanical stability. The inner diameter of the nanotube is tunable between 30 and 90 nm by varying the thickness of the precursor layers. Macropores enclosed by cross-linked nanotubes can be modulated by the choice of BSA. Narrow mesopores are formed by intergrown nanocrystals. Hierarchical ZSM-5 monoliths with nanotube (90 nm), micropore (0.55 nm), mesopore (2 nm) and macropore (700 nm) exhibit superior catalytic performance in the methanol-to-hydrocarbon (MTH) conversion compared to conventional ZSM-5. BSA remains intact after crystallization, allowing a higher level of organization and functionalization of the zeolite nanotube scaffolds. The current work may afford a versatile strategy for hierarchical zeolite monoliths with nanotube scaffolding architectures and a nanotube-multimodal network leading to self-supporting and active zeolite catalysts, and for applications beyond.

Revealing the nature of morphological changes in carbon nanotube-polymer saturable absorber under high-power laser irradiation.

PubMed

Chernysheva, Maria; Araimi, Mohammed Al; Rance, Graham A; Weston, Nicola J; Shi, Baogui; Saied, Sayah; Sullivan, John L; Marsh, Nicholas; Rozhin, Aleksey

2018-05-10

Composites of single-walled carbon nanotubes (SWNTs) and water-soluble polymers (WSP) are the focus of significant worldwide research due to a number of applications in biotechnology and photonics, particularly for ultrashort pulse generation. Despite the unique possibility of constructing non-linear optical SWNT-WSP composites with controlled optical properties, their thermal degradation threshold and limit of operational power remain unexplored. In this study, we discover the nature of the SWNT-polyvinyl alcohol (PVA) film thermal degradation and evaluate the modification of the composite properties under continuous high-power ultrashort pulse laser operation. Using high-precision optical microscopy and micro-Raman spectroscopy, we have examined SWNT-PVA films before and after continuous laser radiation exposure (up to 40 hours) with a maximum optical fluence of 2.3 mJ·cm -2 . We demonstrate that high-intensity laser radiation results in measurable changes in the composition and morphology of the SWNT-PVA film due to efficient heat transfer from SWNTs to the polymer matrix. The saturable absorber modification does not affect the laser operational performance. We anticipate our work to be a starting point for more sophisticated research aimed at the enhancement of SWNT-PVA films fabrication for their operation as reliable saturable absorbers in high-power ultrafast lasers.

Near-IR laser-triggered target cell collection using a carbon nanotube-based cell-cultured substrate.

PubMed

Sada, Takao; Fujigaya, Tsuyohiko; Niidome, Yasuro; Nakazawa, Kohji; Nakashima, Naotoshi

2011-06-28

Unique near-IR optical properties of single-walled carbon nanotube (SWNTs) are of interest in many biological applications. Here we describe the selective cell detachment and collection from an SWNT-coated cell-culture dish triggered by near-IR pulse laser irradiation. First, HeLa cells were cultured on an SWNT-coated dish prepared by a spraying of an aqueous SWNT dispersion on a glass dish. The SWNT-coated dish was found to show a good cell adhesion behavior as well as a cellular proliferation rate similar to a conventional glass dish. We discovered, by near-IR pulse laser irradiation (at the laser power over 25 mW) to the cell under optical microscopic observation, a quick single-cell detachment from the SWNT-coated surface. Shockwave generation from the irradiated SWNTs is expected to play an important role for the cell detachment. Moreover, we have succeeded in catapulting the target single cell from the cultured medium when the depth of the medium was below 150 μm and the laser power was stronger than 40 mW. The captured cell maintained its original shape. The retention of the genetic information of the cell was confirmed by the polymerase chain reaction (PCR) technique. A target single-cell collection from a culture medium under optical microscopic observation is significant in wide fields of single-cell studies in biological areas.

Gas-phase production of single-walled carbon nanotubes from carbon monoxide: a review of the hipco process

NASA Technical Reports Server (NTRS)

Nikolaev, Pavel

2004-01-01

The latest process for producing large quantities of single-walled carbon nanotubes (SWNTs) to emerge from the Rice University, dubbed HiPco, is living up to its promise. The current production rates approach 450 mg/h (or 10 g/day), and nanotubes typically have no more than 7 mol % of iron impurities. Second-generation HiPco apparatus can run continuously for 7-10 days at a time. In the HiPco process nanotubes grow in high-pressure, high-temperature flowing CO on catalytic clusters of iron. Catalyst is formed in situ by thermal decomposition of iron pentacarbonyl, which is delivered intact within a cold CO flow and then rapidly mixed with hot CO in the reaction zone. Upon heating, the Fe(CO)5 decomposes into atoms that condense into larger clusters. SWNTs nucleate and grow on these particles in the gas phase via CO disproportionation: CO + CO --> CO2 + C (SWNT), catalyzed by the Fe surface. The concentration of CO2 produced in this reaction is equal to that of carbon and can therefore serve as a useful real-time feedback parameter. It was used to study and optimize SWNT production as a function of temperature, pressure, and Fe(CO)5 concentration. The results of the parametric study are in agreement with current understanding of the nanotube formation mechanism.

Environmental biodegradability of [¹⁴C] single-walled carbon nanotubes by Trametes versicolor and natural microbial cultures found in New Bedford Harbor sediment and aerated wastewater treatment plant sludge.

PubMed

Parks, Ashley N; Chandler, G Thomas; Ho, Kay T; Burgess, Robert M; Ferguson, P Lee

2015-02-01

Little is known about environmental biodegradability or biotransformations of single-walled carbon nanotubes (SWNT). Because of their strong association with aquatic organic matter, detailed knowledge of the ultimate fate and persistence of SWNT requires investigation of possible biotransformations (i.e., biodegradation) in environmental media. In the present study, [(14)C]SWNT were utilized to track biodegradation over 6 mo by pure liquid culture of the fungus Trametes versicolor and mixed bacterial isolates from field-collected sediment or aerated wastewater treatment plant sludge. The mixed cultures were chosen as more environmentally relevant media where SWNT will likely be deposited under both aerobic and anaerobic conditions. Activity of [(14)C] was assessed in solid, aqueous, and (14)CO2 gaseous phases to determine amounts of intact SWNT, partially soluble SWNT degradation products, and mineralized SWNT, respectively, during the 6 mo of the experiment. Mass balances based on radiocarbon activity were approximately 100% over 6 mo, and no significant degradation of SWNT was observed. Approximately 99% of the [(14)C] activity remained in the solid phase, 0.8% in the aqueous phase, and less than 0.1% was mineralized to (14)CO2, regardless of culture type. These results suggest that SWNT are not readily biodegraded by pure fungal cultures or environmental microbial communities, and are likely persistent in environmental media. © 2014 SETAC.

Non-uniform binding of single-stranded DNA binding proteins to hybrids of single-stranded DNA and single-walled carbon nanotubes observed by atomic force microscopy in air and in liquid

NASA Astrophysics Data System (ADS)

Umemura, Kazuo; Ishizaka, Kei; Nii, Daisuke; Izumi, Katsuki

2016-12-01

Using atomic force spectroscopy (AFM), we observed hybrids of single-stranded DNA (ssDNA) and single-walled carbon nanotubes (SWNTs) with or without protein molecules in air and in an aqueous solution. This is the first report of ssDNA-SWNT hybrids with proteins in solution analyzed by AFM. In the absence of protein, the height of the ssDNA-SWNT hybrids was 1.1 ± 0.3 nm and 2.4 ± 0.6 nm in air and liquid, respectively, suggesting that the ssDNA molecules adopted a flexible structure on the SWNT surface. In the presence of single-stranded DNA binding (SSB) proteins, the heights of the hybrids in air and liquid increased to 6.4 ± 3.1 nm and 10.0 ± 4.5 nm, respectively. The AFM images clearly showed binding of the SSB proteins to the ssDNA-SWNT hybrids. The morphology of the SSB-ssDNA-SWNT hybrids was non-uniform, particularly in aqueous solution. The variance of hybrid height was quantitatively estimated by cross-section analysis along the long-axis of each hybrid. The SSB-ssDNA-SWNT hybrids showed much larger variance than the ssDNA-SWNT hybrids.

Molecular dynamics simulations of the orientation properties of cytochrome c on the surface of single-walled carbon nanotubes.

PubMed

Zhang, Bing; Xu, Jia; Mo, Shu-Fan; Yao, Jian-Xi; Dai, Song-Yuan

2016-12-01

Electron transfer between cytochrome c (Cytc) and electrodes can be influenced greatly by the orientation of protein on the surface of the electrodes. In the present study, different initial orientations of Cytc on the surface of five types of single-walled carbon nanotubes (SWNTs), with different diameters and chirality, were constructed. Properties of the orientations of proteins on the surface of these tubes were first investigated through molecular dynamics simulations. It was shown that variations in SWNT diameter do not significantly affect the orientation; however, the chirality of the SWNTs is crucial to the orientation of the heme embedded in Cytc, and the orientation of the protein can consequently be influenced by the heme orientation. A new electron pathway between Cytc and SWNT, which hopefully benefits electron transfer efficiency, has also been proposed. This study promises to provide theoretical guidance for the rational design of bio-sensors or bio-fuel cells by using Cytc-decorated carbon nanotube electrodes.

Functional single-walled carbon nanotubes based on an integrin αvβ3 monoclonal antibody for highly efficient cancer cell targeting

NASA Astrophysics Data System (ADS)

Ou, Zhongmin; Wu, Baoyan; Xing, Da; Zhou, Feifan; Wang, Huiying; Tang, Yonghong

2009-03-01

The application of single-walled carbon nanotubes (SWNTs) in the field of biomedicine is becoming an entirely new and exciting topic. In this study, a novel functional SWNT based on an integrin αvβ3 monoclonal antibody was developed and was used for cancer cell targeting in vitro. SWNTs were first modified by phospholipid-bearing polyethylene glycol (PL-PEG). The PL-PEG functionalized SWNTs were then conjugated with protein A. A SWNT-integrin αvβ3 monoclonal antibody system (SWNT-PEG-mAb) was thus constructed by conjugating protein A with the fluorescein labeled integrin αvβ3 monoclonal antibody. In vitro study revealed that SWNT-PEG-mAb presented a high targeting efficiency on integrin αvβ3-positive U87MG cells with low cellular toxicity, while for integrin αvβ3-negative MCF-7 cells, the system had a low targeting efficiency, indicating that the high targeting to U87MG cells was due to the specific integrin targeting of the monoclonal antibody. In conclusion, SWNT-PEG-mAb developed in this research is a potential candidate for cancer imaging and drug delivery in cancer targeting therapy.

Polyimide/Carbon Nanotube Composite Films for Electrostatic Charge Mitigation

NASA Technical Reports Server (NTRS)

Delozier, D. M.; Tigelaar, D. M.; Watson, K. A.; Smith, J. G., Jr.; Lillehei, P. T.; Connell, J. W.

2004-01-01

Low color, space environmentally durable polymeric films with sufficient electrical conductivity to mitigate electrostatic charge build-up have been under investigation as part of a materials development activity. In the work described herein, single-walled carbon nanotubes (SWNT) solutions were dispersed in solutions of a novel ionomer in N,N-dimethylacetamide resulting in homogenous suspensions or quasi-solutions. The ionomer was used to aid in the dispersal of SWNTs in to a soluble, low color space environmentally durable polyimide. The use of the ionomer as a dispersant enabled the nanotubes to be dispersed at loading levels up to 3 weight % in a polyimide solution without visual agglomeration. The films were further characterized for their electrical and mechanical properties.

Quantum chemical molecular dynamics simulation of single-walled carbon nanotube cap nucleation on an iron particle.

PubMed

Ohta, Yasuhito; Okamoto, Yoshiko; Page, Alister J; Irle, Stephan; Morokuma, Keiji

2009-11-24

The atomic scale details of single-walled carbon nanotube (SWNT) nucleation on metal catalyst particles are elusive to experimental observations. Computer simulation of metal-catalyzed SWNT nucleation is a challenging topic but potentially of great importance to understand the factors affecting SWNT diameters, chirality, and growth efficiency. In this work, we use nonequilibrium density functional tight-binding molecular dynamics simulations and report nucleation of sp(2)-carbon cap structures on an iron particle consisting of 38 atoms. One C(2) molecule was placed every 1.0 ps around an Fe(38) cluster for 30 ps, after which a further 410 ps of annealing simulation without carbon supply was performed. We find that sp(2)-carbon network nucleation and annealing processes occur in three sequential and repetitive stages: (A) polyyne chains on the metal surface react with each other to evolve into a Y-shaped polyyne junction, which preferentially form a five-membered ring as a nucleus; (B) polyyne chains on the first five-membered ring form an additional fused five- or six-membered ring; and (C) pentagon-to-hexagon self-healing rearrangement takes place with the help of short-lived polyyne chains, stabilized by the mobile metal atoms. The observed nucleation process resembles the formation of a fullerene cage. However, the metal particle plays a key role in differentiating the nucleation process from fullerene cage formation, most importantly by keeping the growing cap structure from closing into a fullerene cage and by keeping the carbon edge "alive" for the addition of new carbon material.

Selective Growth of Metallic and Semiconducting Single Walled Carbon Nanotubes on Textured Silicon.

PubMed

Jang, Mira; Lee, Jongtaek; Park, Teahee; Lee, Junyoung; Yang, Jonghee; Yi, Whikun

2016-03-01

We fabricated the etched Si substrate having the pyramidal pattern size from 0.5 to 4.2 μm by changing the texturing process parameters, i.e., KOH concentration, etching time, and temperature. Single walled carbon nanotubes (SWNTs) were then synthesized on the etched Si substrates with different pyramidal pattern by chemical vapor deposition. We investigated the optical and electronic properties of SWNT film grown on the etched Si substrates of different morphology by using scanning electron microscopy, Raman spectroscopy and conducting probe atomic force microscopy. We confirmed that the morphology of substrate strongly affected the selective growth of the SWNT film. Semiconducting SWNTs were formed on larger pyramidal sized Si wafer with higher ratio compared with SWNTs on smaller pyramidal sized Si.

One-step direct transfer of pristine single-walled carbon nanotubes for functional nanoelectronics.

PubMed

Wu, Chung Chiang; Liu, Chang Hua; Zhong, Zhaohui

2010-03-10

We report a one-step direct transfer technique for the fabrication of functional nanoelectronic devices using pristine single-walled carbon nanotubes (SWNTs). Suspended SWNTs grown by the chemical vapor deposition (CVD) method are aligned and directly transferred onto prepatterned device electrodes at ambient temperature. Using this technique, we successfully fabricated SWNT electromechanical resonators with gate-tunable resonance frequencies. A fully suspended SWNT p-n diode has also been demonstrated with the diode ideality factor equal to 1. Our method eliminates the organic residues on SWNTs resulting from conventional lithography and solution processing. The results open up opportunities for the fundamental study of electron transport physics in ultraclean SWNTs and for room temperature fabrication of novel functional devices based on pristine SWNTs.

Development of n-type cobaltocene-encapsulated carbon nanotubes with remarkable thermoelectric property

PubMed Central

Fukumaru, Takahiro; Fujigaya, Tsuyohiko; Nakashima, Naotoshi

2015-01-01

Direct conversion from heat to electricity is one of the important technologies for a sustainable society since large quantities of energy are wasted as heat. We report the development of a single-walled carbon nanotube (SWNT)-based high conversion efficiency, air-stable and flexible thermoelectric material. We prepared cobaltocene-encapsulated SWNTs (denoted CoCp2@SWNTs) and revealed that the material showed a negative-type (n-type) semiconducting behaviour (Seebeck coefficient: −41.8 μV K−1 at 320 K). The CoCp2@SWNT film was found to show a high electrical conductivity (43,200 S m−1 at 320 K) and large power factor (75.4 μW m−1 K−2) and the performance was remarkably stable under atmospheric conditions over a wide range of temperatures. The thermoelectric figure of merit (ZT) value of the CoCp2@SWNT film (0.157 at 320 K) was highest among the reported n-type organic thermoelectric materials due to the large power factor and low thermal conductivity (0.15 W m−1 K−1). These characteristics of the n-type CoCp2@SWNTs allowed us to fabricate a p-n type thermoelectric device by combination with an empty SWNT-based p-type film. The fabricated device exhibited a highly efficient power generation close to the calculated values even without any air-protective coating due to the high stability of the SWNT-based materials under atmospheric conditions. PMID:25608478

Industrial Scale Synthesis of Carbon Nanotubes Via Fluidized Bed Chemical Vapor Deposition: A Senior Design Project

ERIC Educational Resources Information Center

Smith, York R.; Fuchs, Alan; Meyyappan, M.

2010-01-01

Senior year chemical engineering students designed a process to produce 10 000 tonnes per annum of single wall carbon nanotubes (SWNT) and also conducted bench-top experiments to synthesize SWNTs via fluidized bed chemical vapor deposition techniques. This was an excellent pedagogical experience because it related to the type of real world design…

Intrinsic phonon properties of double-walled carbon nanotubes

NASA Astrophysics Data System (ADS)

Tran, H. N.; Levshov, D. I.; Nguyen, V. C.; Paillet, M.; Arenal, R.; Than, X. T.; Zahab, A. A.; Yuzyuk, Y. I.; Phan, N. M.; Sauvajol, J.-L.; Michel, T.

2017-03-01

Double-walled carbon nanotubes (DWNT) are made of two concentric and weakly van der Waals coupled single-walled carbon nanotubes (SWNT). DWNTs are the simplest systems for studying the mechanical and electronic interactions between concentric carbon layers. In this paper we review recent results concerning the intrinsic features of phonons of DWNTs obtained from Raman experiments performed on index-identified DWNTs. The effect of the interlayer distance on the strength of the mechanical and electronic coupling between the layers, and thus on the frequencies of the Raman-active modes, namely the radial breathing-like modes (RBLMs) and G-modes, are evidenced and discussed. Invited talk at 8th International Workshop on Advanced Materials Science and Nanotechnology (IWAMSN2016), 8-12 November 2016, Ha Long City, Vietnam.

Enhanced cell uptake via non-covalent decollation of a single-walled carbon nanotube-DNA hybrid with polyethylene glycol-grafted poly(l-lysine) labeled with an Alexa-dye and its efficient uptake in a cancer cell

NASA Astrophysics Data System (ADS)

Fujigaya, Tsuyohiko; Yamamoto, Yuki; Kano, Arihiro; Maruyama, Atsushi; Nakashima, Naotoshi

2011-10-01

The use of single-walled carbon nanotubes (SWNTs) for biomedical applications is a promising approach due to their unique outer optical stimuli response properties, such as a photothermal response triggered by near-IR laser irradiation. The challenging task in order to realize such applications is to render the SWNTs biocompatible. For this purpose, the stable and homogeneous functionalization of the SWNTs with a molecule carrying a biocompatible group is very important. Here, we describe the design and synthesis of a polyanionic SWNT/DNA hybrid combined with a cationic poly(l-lysine) grafted by polyethylene glycol (PLL-g-PEG) to provide a supramolecular SWNT assembly. A titration experiment revealed that the assembly undergoes an approximately 1 : 1 reaction of the SWNT/DNA with PLL-g-PEG. We also found that SWNT/DNA is coated with PLL-g-PEG very homogeneously that avoids the non-specific binding of proteins on the SWNT surface. The experiment using the obtained supramolecular hybrid was carried out in vitro and a dramatic enhancement in the cell uptake efficiency compared to that of the SWNT/DNA hybrid without PLL-g-PEG was found.The use of single-walled carbon nanotubes (SWNTs) for biomedical applications is a promising approach due to their unique outer optical stimuli response properties, such as a photothermal response triggered by near-IR laser irradiation. The challenging task in order to realize such applications is to render the SWNTs biocompatible. For this purpose, the stable and homogeneous functionalization of the SWNTs with a molecule carrying a biocompatible group is very important. Here, we describe the design and synthesis of a polyanionic SWNT/DNA hybrid combined with a cationic poly(l-lysine) grafted by polyethylene glycol (PLL-g-PEG) to provide a supramolecular SWNT assembly. A titration experiment revealed that the assembly undergoes an approximately 1 : 1 reaction of the SWNT/DNA with PLL-g-PEG. We also found that SWNT/DNA is coated with PLL

Functionalized single-walled carbon nanotubes: cellular uptake, biodistribution and applications in drug delivery.

PubMed

Li, Zixian; de Barros, Andre Luis Branco; Soares, Daniel Cristian Ferreira; Moss, Sara Nicole; Alisaraie, Laleh

2017-05-30

The unique properties of single-walled carbon nanotubes (SWNTs) enable them to play important roles in many fields. One of their functional roles is to transport cargo into cell. SWNTs are able to traverse amphipathic cell membranes due to their large surface area, flexible interactions with cargo, customizable dimensions, and surface chemistry. The cargoes delivered by SWNTs include peptides, proteins, nucleic acids, as well as drug molecules for therapeutic purpose. The drug delivery functions of SWNTs have been explored over the past decade. Many breakthrough studies have shown the high specificity and potency of functionalized SWNT-based drug delivery systems for the treatment of cancers and other diseases. In this review, we discuss different aspects of drug delivery by functionalized SWNT carriers, diving into the cellular uptake mechanisms, biodistribution of the delivery system, and safety concerns on degradation of the carriers. We emphasize the delivery of several common drugs to highlight the recent achievements of SWNT-based drug delivery. Copyright © 2017 Elsevier B.V. All rights reserved.

Synthesis Methods of Carbon Nanotubes and Related Materials

PubMed Central

Szabó, Andrea; Perri, Caterina; Csató, Anita; Giordano, Girolamo; Vuono, Danilo; Nagy, János B.

2010-01-01

The challenge on carbon nanotubes is still the subject of many research groups. While in the first years the focus was on the new synthesis methods, new carbon sources and support materials, recently, the application possibilities are the principal arguments of the studies. The three main synthesis methods discussed in this review are the arc discharge, the laser ablation and the chemical vapour deposition (CVD) with a special regard to the latter one. In the early stage of the nanotube production the first two methods were utilized mainly for the production of SWNTs while the third one produced mainly MWNTs. The principle of CVD is the decomposition of various hydrocarbons over transition metal supported catalyst. Single-walled (SWNT), multi-walled (MWNT) and coiled carbon nanotubes are produced. In some case, interesting carbonaceous materials are formed during the synthesis process, such as bamboo-like tubes, onions, horn-like structures. In this paper, we refer to the progresses made in the field of the synthesis techniques of carbon nanotubes in the last decade.

Biodistribution and toxicological study of PEGylated single-wall carbon nanotubes in the zebrafish (Danio rerio) nervous system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weber, Gisele E.B.; Dal Bosco, Lidiane; Programa de Pós-graduação em Ciências Fisiológicas–Fisiologia Animal Comparada, FURG, Rio Grande, RS, 96210-900

Nanotechnology has been proven to be increasingly compatible with pharmacological and biomedical applications. Therefore, we evaluated the biological interactions of single-wall carbon nanotubes functionalized with polyethylene glycol (SWNT-PEG). For this purpose, we analyzed biochemical, histological, behavioral and biodistribution parameters to understand how this material behaves in vitro and in vivo using the fish Danio rerio (zebrafish) as a biological model. The in vitro results for fish brain homogenates indicated that SWNT-PEG had an effect on lipid peroxidation and GSH (reduced glutathione) content. However, after intraperitoneal exposure, SWNT-PEG proved to be less biocompatible and formed aggregates, suggesting that the PEG usedmore » for the nanoparticle functionalization was of an inappropriate size for maintaining product stability in a biological environment. This problem with functionalization may have contributed to the low or practically absent biodistribution of SWNT-PEG in zebrafish tissues, as verified by Raman spectroscopy. There was an accumulation of material in the abdominal cavity that led to inflammation and behavioral disturbances, as evaluated by a histological analysis and an open field test, respectively. These results provide evidence of a lack of biocompatibility of SWNTs modified with short chain PEGs, which leads to the accumulation of the material, tissue damage and behavioral alterations in the tested subjects. - Highlights: • In vitro brain exposure diminished lipid peroxidation. • In vitro brain exposure depletes the GSH content. • SWNT-PEG was not biocompatible and formed aggregates after the exposure. • Practically absent biodistribution of SWNT-PEG was observed by Raman spectroscopy. • SWNT-PEG exposure lead to tissue damage and inflammatory responses.« less

Reduced Graphene Oxide/Single-Walled Carbon Nanotube Hybrid Film Using Various p-Type Dopants and Its Application to GaN-Based Light-Emitting Diodes.

PubMed

Lee, Byeong Ryong; Kim, Tae Geun

2016-06-01

This paper reports the electrical and optical properties of the reduced graphene oxide (RGO)/single-walled carbon nanotube (SWNT) films using various p-type dopants and its application to GaN-based light-emitting diodes. To enhance the current injection and spreading of the RGO/SWNT films on the light-emitting diodes (LEDs), we increased the work function (φ) of the films using chemical doping with AuCl3, poly(3,4-ethylenedioxythiophene) oxidized with poly(4-styrenesulfonate) ( PSS) and MoO3; thereby reduced the Schottky barrier height between the RGO/SWNT films and p-GaN. By comparison, LEDs fabricated with work-function-tuned RGO/SWNT film doped with MoO3 exhibited the decrease of the forward voltage from 5.3 V to 5.02 V at 20 mA and the increase of the output power up to 1.26 times. We also analyzed the current injection mechanism using ultraviolet photoelectron spectroscopy and X-ray photoelectron spectroscopy.

Tailored semiconducting carbon nanotube networks with enhanced thermoelectric properties

DOE PAGES

Avery, Azure D.; Zhou, Ben H.; Lee, Jounghee; ...

2016-04-04

Thermoelectric power generation, allowing recovery of part of the energy wasted as heat, is emerging as an important component of renewable energy and energy efficiency portfolios. Although inorganic semiconductors have traditionally been employed in thermoelectric applications, organic semiconductors garner increasing attention as versatile thermoelectric materials. Here we present a combined theoretical and experimental study suggesting that semiconducting single-walled carbon nanotubes with carefully controlled chirality distribution and carrier density are capable of large thermoelectric power factors, higher than 340 μW m -1 K -2, comparable to the best-performing conducting polymers and larger than previously observed for carbon nanotube films. Furthermore, wemore » demonstrate that phonons are the dominant source of thermal conductivity in the networks, and that our carrier doping process significantly reduces the thermal conductivity relative to undoped networks. As a result, these findings provide the scientific underpinning for improved functional organic thermoelectric composites with carbon nanotube inclusions.« less

Tailored semiconducting carbon nanotube networks with enhanced thermoelectric properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Avery, Azure D.; Zhou, Ben H.; Lee, Jounghee

Thermoelectric power generation, allowing recovery of part of the energy wasted as heat, is emerging as an important component of renewable energy and energy efficiency portfolios. Although inorganic semiconductors have traditionally been employed in thermoelectric applications, organic semiconductors garner increasing attention as versatile thermoelectric materials. Here we present a combined theoretical and experimental study suggesting that semiconducting single-walled carbon nanotubes with carefully controlled chirality distribution and carrier density are capable of large thermoelectric power factors, higher than 340 μW m -1 K -2, comparable to the best-performing conducting polymers and larger than previously observed for carbon nanotube films. Furthermore, wemore » demonstrate that phonons are the dominant source of thermal conductivity in the networks, and that our carrier doping process significantly reduces the thermal conductivity relative to undoped networks. As a result, these findings provide the scientific underpinning for improved functional organic thermoelectric composites with carbon nanotube inclusions.« less

A photovoltaic self-powered gas sensor based on a single-walled carbon nanotube/Si heterojunction.

PubMed

Liu, L; Li, G H; Wang, Y; Wang, Y Y; Li, T; Zhang, T; Qin, S J

2017-12-07

We present a novel photovoltaic self-powered gas sensor based on a p-type single-walled carbon nanotube (SWNT) and n-type silicon (n-Si) heterojunction. The energy from visible light suffices to drive the device owing to a built-in electric field (BEF) induced by the differences between the Fermi levels of SWNTs and n-Si.

Effect of semiconductor polymer backbone structures and side-chain parameters on the facile separation of semiconducting single-walled carbon nanotubes from as-synthesized mixtures

NASA Astrophysics Data System (ADS)

Lee, Dennis T.; Chung, Jong Won; Park, Geonhee; Kim, Yun-Tae; Lee, Chang Young; Cho, Yeonchoo; Yoo, Pil J.; Han, Jae-Hee; Shin, Hyeon-Jin; Kim, Woo-Jae

2018-01-01

Semiconducting single-walled carbon nanotubes (SWNTs) show promise as core materials for next-generation solar cells and nanoelectronic devices. However, most commercial SWNT production methods generate mixtures of metallic SWNTs (m-SWNTs) and semiconducting SWNT (sc-SWNTs). Therefore, sc-SWNTs must be separated from their original mixtures before use. In this study, we investigated a polymer-based, noncovalent sc-SWNT separation approach, which is simple to perform and does not disrupt the electrical properties of the SWNTs, thus improving the performance of the corresponding sc-SWNT-based applications. By systematically investigating the effect that different structural features of the semiconductor polymer have on the separation of sc-SWNTs, we discovered that the length and configuration of the alkyl side chains and the rigidity of the backbone structure exert significant effects on the efficiency of sc-SWNT separation. We also found that electron transfer between the semiconductor polymers and sc-SWNTs is strongly affected by their energy-level alignment, which can be tailored by controlling the donor-acceptor configuration in the polymer backbone structures. Among the polymers investigated, the highly planar P8T2Z-C12 semiconductor polymer showed the best sc-SWNT separation efficiency and unprecedentedly strong electronic interaction with the sc-SWNTs, which is important for improving their performance in applications.

Growth mechanism and internal structure of vertically aligned single-walled carbon nanotubes.

PubMed

Einarsson, Erik; Kadowaki, Masayuki; Ogura, Kazuaki; Okawa, Jun; Xiang, Rong; Zhang, Zhengyi; Yamamoto, Takahisa; Ikuhara, Yuichi; Maruyama, Shigeo

2008-11-01

An in situ optical absorbance technique was used to monitor the growth of vertically aligned single-walled carbon nanotubes (VA-SWNTs) at various temperatures and pressures. The effects of the growth temperature and ethanol pressure on the initial growth rate and catalyst lifetime were investigated. It was found that the ideal pressure for VA-SWNT synthesis changes with the growth temperature, shifting toward higher pressure as the growth temperature increases. It was also found that the growth reaction is first-order below this ideal pressure. Additionally, the internal structure of the VA-SWNT film was observed at different depths into the film by transmission electron microscopy. The absence of large bundles was confirmed, and little change in the structure was observed to a depth of approximately 1 microm.

Low-temperature synthesis of single-walled carbon nanotubes with a narrow diameter distribution using size-classified catalyst nanoparticles

NASA Astrophysics Data System (ADS)

Kondo, Daiyu; Sato, Shintaro; Awano, Yuji

2006-05-01

Single-walled carbon nanotubes (SWNTs) with a narrow diameter distribution have been synthesized by hot-filament chemical vapor deposition using acetylene at 590 °C. Iron nanoparticles with diameters of 1.6, 2.0, 2.5, 5.0 and 10 nm (standard deviation: ≈10%) obtained with a differential mobility analyzer were used as a catalyst without any supporting materials on a substrate. SWNTs were obtained from 2.0 nm or smaller particles. The ratio of G band to D band in Raman spectra was as high as 35 without purification, indicating that high-quality SWNTs were synthesized. The SWNT diameters correlated with the particle diameters, demonstrating diameter-controlled SWNT growth.

Contaminant Interactions and Biological Effects of Single-walled Carbon Nanotubes in a Benthic Estuarine System

NASA Astrophysics Data System (ADS)

Parks, Ashley Nicole

The fate, bioavailability, bioaccumulation and toxicity of single-walled carbon nanotubes (SWNT) have not been extensively studied to date. Pristine SWNT are highly hydrophobic and have been shown to strongly associate with natural particulate matter in aquatic environments. In light of this, I have focused my research to examine the influence of sediment and food exposure routes on bioavailability, bioaccumulation, and toxicity of structurally diverse SWNT in several ecologically-important marine invertebrate species. No significant mortality was observed in any organism at concentrations up to 1000 mg/kg. Evidence of biouptake after ingestion was observed for pristine semiconducting SWNT using NIRF spectroscopy and for oxidized 14C-SWNT using liquid scintillation counting. After a 24 hour depuration period, the pristine semiconducting SWNT were eliminated from organisms to below the method detection limit (5 microg/mL), and the 14C-SWNT body burden was decreased by an order of magnitude to a bioaccumulation factor (BAF) of <0.01. Neither pristine SWNT nor oxidized 14C-SWNT caused environmentally relevant toxicity or bioaccumulation in benthic invertebrates. Overall, the SWNT were not bioavailable and appear to associate with the sediment. In addition to investigating the toxicity and bioaccumulation of SWNT as an independent toxicant, it is important to consider how they will interact with other contaminants in the environment (i.e., increase or decrease toxicity and bioaccumulation of co-contaminants, alter the environmental transport of co-contaminants, induce degradation of co-contaminants, etc.). I wanted to investigate the effects of SWNT on a complex mixture of contaminants already present in a natural system. New Bedford Harbor (NBH) sediment, which is contaminated with polychlorinated biphenyls (PCBs), was amended with pristine SWNT to determine if the presence of SWNT would mitigate the toxicity and bioaccumulation of the PCBs in deposit

Quantitative study of bundle size effect on thermal conductivity of single-walled carbon nanotubes

NASA Astrophysics Data System (ADS)

Feng, Ya; Inoue, Taiki; An, Hua; Xiang, Rong; Chiashi, Shohei; Maruyama, Shigeo

2018-05-01

Compared with isolated single-walled carbon nanotubes (SWNTs), thermal conductivity is greatly impeded in SWNT bundles; however, the measurement of the bundle size effect is difficult. In this study, the number of SWNTs in a bundle was determined based on the transferred horizontally aligned SWNTs on a suspended micro-thermometer to quantitatively study the effect of the bundle size on thermal conductivity. Increasing the bundle size significantly degraded the thermal conductivity. For isolated SWNTs, thermal conductivity was approximately 5000 ± 1000 W m-1 K-1 at room temperature, three times larger than that of the four-SWNT bundle. The logarithmical deterioration of thermal conductivity resulting from the increased bundle size can be attributed to the increased scattering rate with neighboring SWNTs based on the kinetic theory.

Bulk purification and deposition methods for selective enrichment in high aspect ratio single-walled carbon nanotubes.

PubMed

Bhatt, Nidhi P; Vichchulada, Pornnipa; Lay, Marcus D

2012-06-06

Aqueous batch processing methods for the concurrent purification of single-walled carbon nanotube (SWNT) soot and enrichment in high aspect ratio nanotubes are essential to their use in a wide variety of electronic, structural, and mechanical applications. This manuscript presents a new route to the bulk purification and enrichment of unbundled SWNTs having average lengths in excess of 2 μm. Iterative centrifugation cycles at low centripetal force not only removed amorphous C and catalyst nanoparticles but also allowed the enhanced buoyancy of surfactant encapsulated, unbundled, high aspect ratio SWNTs to be used to isolate them in the supernatant. UV-vis-NIR and Raman spectroscopy were used to verify the removal of residual impurities from as-produced (AP-grade) arc discharge soot and the simultaneous enrichment in unbundled, undamaged, high aspect ratio SWNTs. The laminar flow deposition process (LFD) used to form two-dimensional networks of SWNTs prevented bundle formation during network growth. Additionally, it further enhanced the quality of deposits by taking advantage of the inverse relationship between the translational diffusion coefficient and length for suspended nanoparticles. This resulted in preferential deposition of pristine, unbundled, high aspect ratio SWNTs over residual impurities, as observed by Raman spectroscopy and atomic force microscopy (AFM).

Effect of UV irradiation on the dynamics of oxygen and water interaction with carbon nanotubes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nelson, Anthony J; Ivanov, Ilia N

2016-01-01

Carbon nanotube (CNT) films composed of semiconducting single wall nanotubes (s-SWNTs), metallic single wall nanotubes (m-SWNTs), and multiwall nanotubes (MWNTs) were exposed to O2 and H2O vapor in the dark and under UV irradiation. Changes in the film conductivity and mass were measured in situ. We find that UV irradiation increases the resistive response of CNT films to O2 and H2O by more than an order of magnitude. In m-SWNT and MWNT films, UV irradiation changes the sign of the resistive response to O2 and H2O by generating free charge carriers. S-SWNTs show the largest UV-induced resistive response and exhibitmore » weakening of van der Waals interactions with the QCM crystal when exposed to gas/vapor.« less

Origins of the helical wrapping of phenyleneethynylene polymers about single-walled carbon nanotubes.

PubMed

Von Bargen, Christopher D; MacDermaid, Christopher M; Lee, One-Sun; Deria, Pravas; Therien, Michael J; Saven, Jeffery G

2013-10-24

The highly charged, conjugated polymer poly[p-{2,5-bis(3-propoxysulfonicacidsodiumsalt)}phenylene]ethynylene (PPES) has been shown to wrap single-wall carbon nanotubes (SWNTs), adopting a robust helical superstructure. Surprisingly, PPES adopts a helical rather than a linear conformation when adhered to SWNTs. The complexes formed by PPES and related polymers upon helical wrapping of a SWNT are investigated using atomistic molecular dynamics (MD) simulations in the presence and absence of aqueous solvent. In simulations of the PPES/SWNT system in an aqueous environment, PPES spontaneously takes on a helical conformation. A potential of mean force, ΔA(ξ), is calculated as a function of ξ, the component of the end-to-end vector of the polymer chain projected on the SWNT axis; ξ is a monotonic function of the polymer's helical pitch. ΔA(ξ) provides a means to quantify the relative free energies of helical conformations of the polymer when wrapped about the SWNT. The aqueous system possesses a global minimum in ΔA(ξ) at the experimentally observed value of the helical pitch. The presence of this minimum is associated with preferred side chain conformations, where the side chains adopt conformations that provide van der Waals contact between the tubes and the aliphatic components of the side chains, while exposing the anionic sulfonates for aqueous solvation. The simulations provide a free energy estimate of a 0.2 kcal/mol/monomer preference for the helical over the linear conformation of the PPES/SWNT system in an aqueous environment.

Molecular dynamics study of a nanotube-binding amphiphilic helical peptide at different water/hydrophobic interfaces.

PubMed

Chiu, Chi-Cheng; Dieckmann, Gregg R; Nielsen, Steven O

2008-12-25

Many potential applications of single-walled carbon nanotubes (SWNTs) require that they be isolated from one another. This may be accomplished through covalent or noncovalent SWNT functionalization. The noncovalent approach preserves the intrinsic electrical, optical, and mechanical properties of SWNTs and can be achieved by dispersing SWNTs in aqueous solution using surfactants, polymers, or biomacromolecules like DNA or polypeptides. The designed amphiphilic helical peptide nano-1, which contains hydrophobic valine and aromatic phenylalanine residues for interaction with SWNTs and glutamic acid and lysine residues for water solubility, has been shown to debundle and disperse SWNTs, although the details of the peptide-SWNT interactions await elucidation. Here we use fully atomistic molecular dynamics simulations to investigate the nano-1 peptide at three different water/hydrophobic interfaces: water/oil, water/graphite, and water/SWNT. The amphiphilic nature of the peptide is characterized by its secondary structure, peptide-water hydrogen bonding, and peptide-hydrophobic surface van der Waals energy. We show that nano-1 has reduced amphiphilic character at the water/oil interface because the peptide helix penetrates into the hydrophobic phase. The peptide alpha-helix cannot match its hydrophobic face to the rigid planar graphite surface without partially unfolding. In contrast, nano-1 can curve on the SWNT surface in an alpha-helical conformation to simultaneously maximize its hydrophobic contacts with the SWNT and its hydrogen bonds with water. The molecular insight into the peptide conformation at the various hydrophobic surfaces provides guidelines for future peptide design.

Inter-allotropic transformations in the heterogeneous carbon nanotube networks.

PubMed

Jung, Hyun Young; Jung, Sung Mi; Kim, Dong Won; Jung, Yung Joon

2017-01-19

The allotropic transformations of carbon provide an immense technological interest for tailoring the desired molecular structures in the scalable nanoelectronic devices. Herein, we explore the effects of morphology and geometric alignment of the nanotubes for the re-engineering of carbon bonds in the heterogeneous carbon nanotube (CNT) networks. By applying alternating voltage pulses and electrical forces, the single-walled CNTs in networks were predominantly transformed into other predetermined sp 2 carbon structures (multi-walled CNTs and multi-layered graphitic nanoribbons), showing a larger intensity in a coalescence-induced mode of Raman spectra with the increasing channel width. Moreover, the transformed networks have a newly discovered sp 2 -sp 3 hybrid nanostructures in accordance with the alignment. The sp 3 carbon structures at the small channel are controlled, such that they contain up to about 29.4% networks. This study provides a controllable method for specific types of inter-allotropic transformations/hybridizations, which opens up the further possibility for the engineering of nanocarbon allotropes in the robust large-scale network-based devices.

Carbohydrate conjugation through microwave-assisted functionalization of single-walled carbon nanotubes using perfluorophenyl azides.

PubMed

Kong, Na; Shimpi, Manishkumar R; Ramström, Olof; Yan, Mingdi

2015-03-20

Carbohydrate-functionalized single-walled carbon nanotubes (SWNTs) were synthesized using microwave-assisted reaction of perfluorophenyl azide with the nanotubes. The results showed that microwave radiation provides a rapid and effective means to covalently attach carbohydrates to SWNTs, producing carbohydrate-SWNT conjugates for biorecognition. The carbohydrate-functionalized SWNTs were furthermore shown to interact specifically with cognate carbohydrate-specific proteins (lectins), resulting in predicted recognition patterns. The carbohydrate-presenting SWNTs constitute a new platform for sensitive protein- or cell recognition, which pave the way for glycoconjugated carbon nanomaterials in biorecognition applications. Copyright © 2014 Elsevier Ltd. All rights reserved.

Sensing Reversible Protein–Ligand Interactions with Single-Walled Carbon Nanotube Field-Effect Transistors

PubMed Central

2015-01-01

We report on the reversible detection of CaptAvidin, a tyrosine modified avidin, with single-walled carbon nanotube (SWNT) field-effect transistors (FETs) noncovalently functionalized with biotin moieties using 1-pyrenebutyric acid as a linker. Binding affinities at different pH values were quantified, and the sensor’s response at various ionic strengths was analyzed. Furthermore, protein “fingerprints” of NeutrAvidin and streptavidin were obtained by monitoring their adsorption at several pH values. Moreover, gold nanoparticle decorated SWNT FETs were functionalized with biotin using 1-pyrenebutyric acid as a linker for the CNT surface and (±)-α-lipoic acid linkers for the gold surface, and reversible CaptAvidin binding is shown, paving the way for potential dual mode measurements with the addition of surface enhanced Raman spectroscopy (SERS). PMID:25126155

Electrospinning of single wall carbon nanotube reinforced aligned fibrils and yarns

NASA Astrophysics Data System (ADS)

Lam, Hoa Le

Commercial carbon fibers produced from a polyacrylonitrile (PAN) precursor have reached their performance limit. The approach in this study involves the use of single carbon nanotubes (SWNT) with an ultra-high elastic modulus of approximately ˜1 TPa and tensile strength of ˜37 GPa at a breaking strain of ˜6% to reinforce PAN. In order to translate these extraordinary properties to a higher order structure, the need for a media to carry and assemble the SWNT into continuous fibers or yarns is necessary. Effective translation of properties can only be achieved through uniform distribution of SWNT and their alignment in the fiber axis. This has been one of the major challenges since SWNTs tend to agglomerate due to high van der Waals attraction between tubes. It is the goal of this study to develop dispersion technique(s) for the SWNT and process them into aligned fibers utilizing the electrospinning process. The electrospun nanofibers were then characterized by various techniques such as ESEM, Raman microspectroscopy, HRTEM, and tensile testing. Composite nanofibers containing various contents of SWNT up to 10 wt. % with diameter ranging from 40--300 nm were successfully electrospun through varying the polymer concentration and spinning parameters. The inclusion of SWNTs and their alignment in the fiber axis were confirmed by Raman microspectroscopy, polarized Raman and HRETEM. The failure mechanism of the nanofibers was investigated by HRTEM through fiber surface fracture. A two stage rupture mechanism was observed where crazing initiates at a surface defect followed by SWNTs pulling out of the PAN matrix. Such mechanisms consume energy therefore strengthening and toughening the fibers. Mechanical drawing of the fiber prior to heat treatment induced molecular orientation resulting in oriented graphite layers in the carbonized fibers. This study has established a processing base and characterization techniques to support the design and development of SWNT

Investigating interfacial contact configuration and behavior of single-walled carbon nanotube-based nanodevice with atomistic simulations

NASA Astrophysics Data System (ADS)

Cui, Jianlei; Zhang, Jianwei; He, Xiaoqiao; Mei, Xuesong; Wang, Wenjun; Yang, Xinju; Xie, Hui; Yang, Lijun; Wang, Yang

2017-03-01

Carbon nanotubes (CNTs), including single-walled carbon nanotubes (SWNTs) and multi-walled carbon nanotubes (MWNTs), are considered to be the promising candidates for next-generation interconnects with excellent physical and chemical properties ranging from ultrahigh mechanical strength, to electrical properties, to thermal conductivity, to optical properties, etc. To further study the interfacial contact configurations of SWNT-based nanodevice with a 13.56-Å diameter, the corresponding simulations are carried out with the molecular dynamic method. The nanotube collapses dramatically into the surface with the complete collapse on the Au/Ag/graphite electrode surface and slight distortion on the Si/SiO2 substrate surface, respectively. The related dominant mechanism is studied and explained. Meanwhile, the interfacial contact configuration and behavior, depended on other factors, are also analyzed in this article.

Functionalized Single-Walled Carbon Nanotube-Based Fuel Cell Benchmarked Against US DOE 2017 Technical Targets

PubMed Central

Jha, Neetu; Ramesh, Palanisamy; Bekyarova, Elena; Tian, Xiaojuan; Wang, Feihu; Itkis, Mikhail E.; Haddon, Robert C.

2013-01-01

Chemically modified single-walled carbon nanotubes (SWNTs) with varying degrees of functionalization were utilized for the fabrication of SWNT thin film catalyst support layers (CSLs) in polymer electrolyte membrane fuel cells (PEMFCs), which were suitable for benchmarking against the US DOE 2017 targets. Use of the optimum level of SWNT -COOH functionality allowed the construction of a prototype SWNT-based PEMFC with total Pt loading of 0.06 mgPt/cm2 - well below the value of 0.125 mgPt/cm2 set as the US DOE 2017 technical target for total Pt group metals (PGM) loading. This prototype PEMFC also approaches the technical target for the total Pt content per kW of power (<0.125 gPGM/kW) at cell potential 0.65 V: a value of 0.15 gPt/kW was achieved at 80°C/22 psig testing conditions, which was further reduced to 0.12 gPt/kW at 35 psig back pressure. PMID:23877112

Functionalized single-walled carbon nanotube-based fuel cell benchmarked against US DOE 2017 technical targets.

PubMed

Jha, Neetu; Ramesh, Palanisamy; Bekyarova, Elena; Tian, Xiaojuan; Wang, Feihu; Itkis, Mikhail E; Haddon, Robert C

2013-01-01

Chemically modified single-walled carbon nanotubes (SWNTs) with varying degrees of functionalization were utilized for the fabrication of SWNT thin film catalyst support layers (CSLs) in polymer electrolyte membrane fuel cells (PEMFCs), which were suitable for benchmarking against the US DOE 2017 targets. Use of the optimum level of SWNT -COOH functionality allowed the construction of a prototype SWNT-based PEMFC with total Pt loading of 0.06 mg(Pt)/cm²--well below the value of 0.125 mg(Pt)/cm² set as the US DOE 2017 technical target for total Pt group metals (PGM) loading. This prototype PEMFC also approaches the technical target for the total Pt content per kW of power (<0.125 g(PGM)/kW) at cell potential 0.65 V: a value of 0.15 g(Pt)/kW was achieved at 80°C/22 psig testing conditions, which was further reduced to 0.12 g(Pt)/kW at 35 psig back pressure.

Influence of Oxygen Adsorption on the Thermoelectric Power (tep) in Multiwalled Carbon Nanotubes

NASA Astrophysics Data System (ADS)

Savage, Traig; Bhattacharya, Sriparna; Sadanadan, Bindu; Gaillard, Jay; Tritt, Terry; Rao, Apparao; Sun, Ya-Ping

2002-03-01

The sign of the thermoelectric power (TEP) has been found to be extremely sensitive to oxygen adsorption in single walled carbon nanotube (SWNT) bundles [1-3]. A TEP value of ~ +54 μV/K has been reported in SWNT bundles that were exposed to room air, and upon desorbing the oxygen from the sample, the TEP switches reversibly to ~ -44 μV/K [2]. In this study we report TEP measurements in multiwalled carbon nanotubes (MWNTs) as functions of exposure time to room air (oxygen). The MWNTs were prepared on quartz substrates from a thermal decomposition of xylene-ferrocene mixtures at ~750^oC. Negative TEP values at all temperatures (10-300K) were obtained in freshly prepared MWNTs. Upon exposure of the MWNT film to room air and room light over a period of ~1 month, the TEP is found to change systematically to positive values. We also exposed another MWNT sample to ultraviolet (UV) radiation (λ=240 nm; ~1 W/m^2) in air for 10 days. The data indicates a photo-enhanced adsorption of oxygen as evidenced by a faster (factor of ~3) TEP sign reversal. The TEP in both the air- and UV-exposed films was shown to be completely reversible upon degassing the samples for ~12 hours. These findings are consistent with those reported in SWNT bundles, and a theoretical basis for the photo-induced oxygen adsorption will be presented. [1] P. G. Collins et al., Science, 287, 1804 (2000). [2] G. U. Sumanasekera et al., Phys. Rev. Lett., 85, 1096 (2000). [3] K. Bradley et al., Phys. Rev. Lett., 85, 4361 (2000).

Purification Procedures for Single-Wall Carbon Nanotubes

NASA Technical Reports Server (NTRS)

Gorelik, Olga P.; Nikolaev, Pavel; Arepalli, Sivaram

2001-01-01

This report summarizes the comparison of a variety of procedures used to purify carbon nanotubes. Carbon nanotube material is produced by the arc process and laser oven process. Most of the procedures are tested using laser-grown, single-wall nanotube (SWNT) material. The material is characterized at each step of the purification procedures by using different techniques including scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), Raman, X-ray diffractometry (XRD), thermogravimetric analysis (TGA), nuclear magnetic resonance (NMR), and high-performance liquid chromatography (HPLC). The identified impurities are amorphous and graphitic carbon, catalyst particle aggregates, fullerenes, and hydrocarbons. Solvent extraction and low-temperature annealing are used to reduce the amount of volatile hydrocarbons and dissolve fullerenes. Metal catalysts and amorphous as well as graphitic carbon are oxidized by reflux in acids including HCl, HNO3 and HF and other oxidizers such as H2O2. High-temperature annealing in vacuum and in inert atmosphere helps to improve the quality of SWNTs by increasing crystallinity and reducing intercalation.

Intense photoluminescence from dried double-stranded DNA and single-walled carbon nanotube hybrid

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ito, M.; Kobayashi, T.; Ito, Y.

2014-01-27

Semiconducting single-walled carbon nanotubes (SWNTs) show near-infrared photoluminescence (PL) when they are individually isolated. This was an obstacle to use photonic properties of SWNTs on a solid surface. We show that SWNTs wrapped with DNA maintain intense PL under the dry conditions. SWNTs are well isolated individually by DNA even when the DNA-SWNT hybrids are agglomerated. This finding opens up application of SWNTs to photonic devices.

Wireless and embedded carbon nanotube networks for damage detection in concrete structures

NASA Astrophysics Data System (ADS)

Saafi, Mohamed

2009-09-01

Concrete structures undergo an uncontrollable damage process manifesting in the form of cracks due to the coupling of fatigue loading and environmental effects. In order to achieve long-term durability and performance, continuous health monitoring systems are needed to make critical decisions regarding operation, maintenance and repairs. Recent advances in nanostructured materials such as carbon nanotubes have opened the door for new smart and advanced sensing materials that could effectively be used in health monitoring of structures where wireless and real time sensing could provide information on damage development. In this paper, carbon nanotube networks were embedded into a cement matrix to develop an in situ wireless and embedded sensor for damage detection in concrete structures. By wirelessly measuring the change in the electrical resistance of the carbon nanotube networks, the progress of damage can be detected and monitored. As a proof of concept, wireless cement-carbon nanotube sensors were embedded into concrete beams and subjected to monotonic and cyclic loading to evaluate the effect of damage on their response. Experimental results showed that the wireless response of the embedded nanotube sensors changes due to the formation of cracks during loading. In addition, the nanotube sensors were able to detect the initiation of damage at an early stage of loading.

Fullerene-Assisted Photoinduced Charge Transfer of Single-Walled Carbon Nanotubes through a Flavin Helix.

PubMed

Mollahosseini, Mehdi; Karunaratne, Erandika; Gibson, George N; Gascón, Jose A; Papadimitrakopoulos, Fotios

2016-05-11

One of the greatest challenges with single-walled carbon nanotube (SWNT) photovoltaics and nanostructured devices is maintaining the nanotubes in their pristine state (i.e., devoid of aggregation and inhomogeneous doping) so that their unique spectroscopic and transport characteristics are preserved. To this effect, we report on the synthesis and self-assembly of a C60-functionalized flavin (FC60), composed of PCBM and isoalloxazine moieties attached on either ends of a linear, C-12 aliphatic spacer. Small amounts of FC60 (up to 3 molar %) were shown to coassembly with an organic soluble derivative of flavin (FC12) around SWNTs and impart effective dispersion and individualization. A key annealing step was necessary to perfect the isoalloxazine helix and expel the C60 moiety away from the nanotubes. Steady-state and transient absorption spectroscopy illustrate that 1% or higher incorporation of FC60 allows for an effective photoinduced charge transfer quenching of the encased SWNTs through the seamless helical encase. This is enabled via the direct π-π overlap between the graphene sidewalls, isoalloxazine helix, and the C60 cage that facilitates SWNT exciton dissociation and electron transfer to the PCBM moiety. Atomistic molecular simulations indicate that the stability of the complex originates from enhanced van der Waals interactions of the flexible spacer wrapped around the fullerene that brings the C60 in π-π overlap with the isoalloxazine helix. The remarkable spectral purity (in terms of narrow E(S)ii line widths) for the resulting ground-state complex signals a new class of highly organized supramolecular nanotube architecture with profound importance for advanced nanostructured devices.

Pressure-sensing properties of single-walled carbon nanotubes covered with a corona-poled piezoelectric polymer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ikawa, Takeshi; Tabata, Hiroshi, E-mail: tabata@eei.eng.osaka-u.ac.jp; Yoshizawa, Takeshi

Single-walled carbon nanotubes (SWNTs) have been studied extensively as sensing elements for chemical and biochemical sensors because of their excellent electrical properties, their ultrahigh ratio of surface area to volume, and the consequent extremely high sensitivity of their surface to the surrounding environment. The extremely high sensitivity indicates that SWNTs can operate as excellent transducers when combined with piezoelectric materials. In this paper, we present a touch sensor based on SWNT thin-film transistors (SWNT-TFTs) covered with a thin film of the piezoelectric polymer poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)). Devices were fabricated by spin-coating a P(VDF-TrFE) layer on an SWNT-TFT, which was followedmore » by in situ corona poling to polarize the P(VDF-TrFE) layer. We studied the effect of the corona polarity on the device characteristics and revealed that poling with a negative corona discharge induced a large amount of hole doping in the SWNTs and improved the touch-sensing performance of the devices, while a positive discharge had a negligible effect. The poled devices exhibited regular, stable, and positive drain current modulation in response to intermittent pressing, and the response was proportional to the magnitude of the applied pressure, suggesting that it was caused by the piezoelectric effect of the polarized P(VDF-TrFE) layer. Furthermore, we also fabricated a device using horizontally aligned SWNTs with a lower SWNT density as an alternative transducer to an SWNT thin film, which demonstrated sensitivity as high as 70%/MPa.« less

Chlorinated paraffins wrapping of carbon nanotubes: A theoretical investigation

NASA Astrophysics Data System (ADS)

Ding, Qiuyue; Ding, Ning; Chen, Xiangfeng; Wu, Chi-Man Lawrence

2018-04-01

How nanomaterials interact with pollutants is the central for understanding their environmental behavior and practical application. In this work, molecular dynamics (MD) and density functional theoretical (DFT) methods were used to investigated the influence of carbon chain length, degree of chlorination, chain configuration, and chirality of chlorinated paraffin (CP) and diameter of single-walled carbon nanotubes (SWNTs) on the interaction between CPs and SWNTs. The simulation results demonstrated that CP chain length and chlorination degree played considerably important roles in determining interaction strength between SWNTs and CPs. The interaction energies increased with increasing chain length and chlorination degree. The chirality of SWNT exerted negligible influence on the interaction energy between SWNTs and CPs. On the contrary, interaction energy increased with increasing radius of SWNTs due to the surface curvatures. This result was rationalized by considering the decrease in SWNT curvature with increasing radius, which resulted in plane-like CNT wall. The negligible influence of CP chain configurations was attributed to relative flexibility of CP carbon chains, which can wrap on tubes through conformational changes with low-energy barriers. MD results indicated that CPs could adsorb on SWNT surface rapidly in aqueous environment. Charge transfer and electronic density results indicated that the interaction between CPs and SWNTs was physisorption in nature. This work provides fundamental information regarding SWNTs as sorbents for CPs extraction and adsorptive removal from environmental water system.

Computational characterization of DNA/peptide/nanotube self assembly for bioenergy applications

NASA Astrophysics Data System (ADS)

Ortiz, Vanessa; Araki, Ruriko; Collier, Galen

2012-02-01

Multi-enzyme pathways have become a subject of increasing interest for their role in the engineering of biomimetic systems for applications including biosensors, bioelectronics, and bioenergy. The efficiencies found in natural metabolic pathways partially arise from biomolecular self-assembly of the component enzymes in an effort to avoid transport limitations. The ultimate goal of this effort is to design and build biofuel cells with efficiencies similar to those of native systems by introducing biomimetic structures that immobilize multiple enzymes in specific orientations on a bioelectrode. To achieve site-specific immobilization, the specificity of DNA-binding domains is exploited with an approach that allows any redox enzyme to be modified to site-specifically bind to double stranded (ds) DNA while retaining activity. Because of its many desirable properties, the bioelectrode of choice is single-wall carbon nanotubes (SWNTs), but little is known about dsDNA/SWNT assembly and how this might affect the activity of the DNA-binding domains. Here we evaluate the feasibility of the proposed assembly by performing atomistic molecular dynamics simulations to look at the stability and conformations adopted by dsDNA when bound to a SWNT. We also evaluate the effects of the presence of a SWNT on the stability of the complex formed by a DNA-binding domain and DNA.

Facile Isolation of Adsorbent-Free Long and Highly-Pure Chirality-Selected Semiconducting Single-Walled Carbon Nanotubes Using A Hydrogen-bonding Supramolecular Polymer.

PubMed

Toshimitsu, Fumiyuki; Nakashima, Naotoshi

2015-12-14

The ideal form of semiconducting-single-walled carbon nanotubes (sem-SWNTs) for science and technology is long, defect-free, chirality pure and chemically pure isolated narrow diameter tubes. While various techniques to solubilize and purify sem-SWNTs have been developed, many of them targeted only the chiral- or chemically-purity while sacrificing the sem-SWNT intrinsic structural identities by applying strong ultra-sonication and/or chemical modifications. Toward the ultimate purification of the sem-SWNTs, here we report a mild-conditioned extraction of the sem-SWNTs using removable supramolecular hydrogen-bonding polymers (HBPs) that are composed of dicarboxylic- or diaminopyridyl-fluorenes with ~70%-(8,6)SWNT selective extraction. Replacing conventional strong sonication techniques by a simple shaking using HPBs was found to provide long sem-SWNTs (>2.0 μm) with a very high D/G ratio, which was determined by atomic force microscopy observations. The HBPs were readily removed from the nanotube surfaces by an outer stimulus, such as a change in the solvent polarities, to provide chemically pure (8,6)-enriched sem-SWNTs. We also describe molecular mechanics calculations to propose possible structures for the HBP-wrapped sem-SWNTs, furthermore, the mechanism of the chiral selectivity for the sorted sem-SWNTs is well explained by the relationship between the molecular surface area and mass of the HBP/SWNT composites.

A three-dimensional microelectrode array composed of vertically aligned ultra-dense carbon nanotube networks

NASA Astrophysics Data System (ADS)

Nick, C.; Yadav, S.; Joshi, R.; Schneider, J. J.; Thielemann, C.

2015-07-01

Electrodes based on carbon nanotubes are a promising approach to manufacture highly sensitive sensors with a low limit of signal detection and a high signal-to-noise ratio. This is achieved by dramatically increasing the electrochemical active surface area without increasing the overall geometrical dimensions. Typically, carbon nanotube electrodes are nearly planar and composed of randomly distributed carbon nanotube networks having a limited surface gain for a specific geometrical surface area. To overcome this limitation, we have introduced vertically aligned carbon nanotube (VACNT) networks as electrodes, which are arranged in a microelectrode pattern of 60 single electrodes. Each microelectrode features a very high aspect ratio of more than 300 and thus a dramatically increased surface area. These microelectrodes composed of VACNT networks display dramatically decreased impedance over the entire frequency range compared to planar microelectrodes caused by the enormous capacity increase. This is experimentally verified by electrochemical impedance spectroscopy and cyclic voltammetry.

Making Macroscopic Assemblies of Aligned Carbon Nanotubes

NASA Technical Reports Server (NTRS)

Smalley, Richard E.; Colbert, Daniel T.; Smith, Ken A.; Walters, Deron A.; Casavant, Michael J.; Qin, Xiaochuan; Yakobson, Boris; Hauge, Robert H.; Saini, Rajesh Kumar; Chiung, Wan-Ting;

Transparent conductive oxide films mixed with gallium oxide nanoparticle/single-walled carbon nanotube layer for deep ultraviolet light-emitting diodes

PubMed Central

2013-01-01

We propose a transparent conductive oxide electrode scheme of gallium oxide nanoparticle mixed with a single-walled carbon nanotube (Ga2O3 NP/SWNT) layer for deep ultraviolet light-emitting diodes using spin and dipping methods. We investigated the electrical, optical and morphological properties of the Ga2O3 NP/SWNT layers by increasing the thickness of SWNTs via multiple dipping processes. Compared with the undoped Ga2O3 films (current level 9.9 × 10-9 A @ 1 V, transmittance 68% @ 280 nm), the current level flowing in the Ga2O3 NP/SWNT increased by approximately 4 × 105 times and the transmittance improved by 9% after 15 times dip-coating (current level 4 × 10-4 A at 1 V; transmittance 77.0% at 280 nm). These improvements result from both native high transparency of Ga2O3 NPs and high conductivity and effective current spreading of SWNTs. PMID:24295342

In situ Raman study on single- and double-walled carbon nanotubes as a function of lithium insertion.

PubMed

Kim, Yoong Ahm; Kojima, Masahito; Muramatsu, Hiroyuki; Umemoto, Souichiro; Watanabe, Takaaki; Yoshida, Kazuto; Sato, Keigo; Ikeda, Takuya; Hayashi, Takuya; Endo, Morinobu; Terrones, Mauricio; Dresselhaus, Mildred S

2006-05-01

We investigated the electrochemical lithium ion (Li(+)) insertion/desertion behavior on highly pure and bundled single- and double-walled carbon nanotubes (SWNTs and DWNTs) using an in situ Raman technique. In general, two storage sites could host Li(+) in SWNT and DWNT bundles when varying an external potential: a) the outer surface sites, and b) the interstitial spaces within the bundles. The most sensitive changes in the tangential mode (TM) of the Raman spectra upon doping with Li(+) can be divided into two regions. The first region was found from 2.8 to 1.0 V (the coverage of Li(+) on the outer surface of a bundled nanotube) and was characterized by the loss of resonant conditions via partial charge transfer, where the G(+) line of the SWNT and the TM of the outer tube of DWNTs experienced a highly depressed intensity, but remained almost constant in frequency. The appearance of a Breit-Wigner-Fano (BWF) profile provided strong evidence of metallic inner tubes within DWNTs. The second region was observed when the applied potentials ranged from 0.9 to 0 V and was characterized by Li(+) diffusion into the interstitial sites of the bundled nanotube material. This phenomenon invoked a large downshift of the G(-) band in SWNTs, and a small downshift of the TM of the inner tube of DWNTs caused by expansion of the C--C bonds due to the charge transferred to the nanotubes, and the disappearance of the BWF profile through the screening effect of the interstitial Li(+) layers.

Effect of van der Waals forces on thermal conductance at the interface of a single-wall carbon nanotube array and silicon

NASA Astrophysics Data System (ADS)

Feng, Ya; Zhu, Jie; Tang, Dawei

2014-12-01

Molecular dynamics simulations are performed to evaluate the effect of van der Waals forces among single-wall carbon nanotubes (SWNTs) on the interfacial thermal conductance between a SWNT array and silicon substrate. First, samples of SWNTs vertically aligned on silicon substrate are simulated, where both the number and arrangement of SWNTs are varied. Results reveal that the interfacial thermal conductance of a SWNT array/Si with van der Waals forces present is higher than when they are absent. To better understand how van der Waals forces affect heat transfer through the interface between SWNTs and silicon, further constructs of one SWNT surrounded by different numbers of other ones are studied, and the results show that the interfacial thermal conductance of the central SWNT increases with increasing van der Waals forces. Through analysis of the covalent bonds and vibrational density of states at the interface, we find that heat transfer across the interface is enhanced with a greater number of chemical bonds and that improved vibrational coupling of the two sides of the interface results in higher interfacial thermal conductance. Van der Waals forces stimulate heat transfer at the interface.

Molecular discriminators using single wall carbon nanotubes

NASA Astrophysics Data System (ADS)

Bhattacharyya, Tamoghna; Dasgupta, Anjan Kr; Ranjan Ray, Nihar; Sarkar, Sabyasachi

2012-09-01

The interaction between single wall carbon nanotubes (SWNTs) and amphiphilic molecules has been studied in a solid phase. SWNTs are allowed to interact with different amphiphilic probes (e.g. lipids) in a narrow capillary interface. Contact between strong hydrophobic and amphiphilic interfaces leads to a molecular restructuring of the lipids at the interface. The geometry of the diffusion front and the rate and the extent of diffusion of the interface are dependent on the structure of the lipid at the interface. Lecithin having a linear tail showed greater mobility of the interface as compared to a branched tail lipid like dipalmitoyl phosphatidylcholine, indicating the hydrophobic interaction between single wall carbon nanotube core and the hydrophobic tail of the lipid. Solid phase interactions between SWNT and lipids can thus become a very simple but efficient means of discriminating amphiphilic molecules in general and lipids in particular.

Optically active single-walled carbon nanotubes

NASA Astrophysics Data System (ADS)

Peng, Xiaobin; Komatsu, Naoki; Bhattacharya, Sumanta; Shimawaki, Takanori; Aonuma, Shuji; Kimura, Takahide; Osuka, Atsuhiro

2007-06-01

The optical, electrical and mechanical properties of single-walled carbon nanotubes (SWNTs) are largely determined by their structures, and bulk availability of uniform materials is vital for extending their technological applications. Since they were first prepared, much effort has been directed toward selective synthesis and separation of SWNTs with specific structures. As-prepared samples of chiral SWNTs contain equal amounts of left- and right-handed helical structures, but little attention has been paid to the separation of these non-superimposable mirror image forms, known as optical isomers. Here, we show that optically active SWNT samples can be obtained by preferentially extracting either right- or left-handed SWNTs from a commercial sample. Chiral `gable-type' diporphyrin molecules bind with different affinities to the left- and right-handed helical nanotube isomers to form complexes with unequal stabilities that can be readily separated. Significantly, the diporphyrins can be liberated from the complexes afterwards, to provide optically enriched SWNTs.

Electronic Detection of Lectins Using Carbohydrate Functionalized Nanostructures: Graphene versus Carbon Nanotubes

PubMed Central

Chen, Yanan; Vedala, Harindra; Kotchey, Gregg P.; Audfray, Aymeric; Cecioni, Samy; Imberty, Anne; Vidal, Sébastien; Star, Alexander

2012-01-01

Here we investigated the interactions between lectins and carbohydrates using field-effect transistor (FET) devices comprised of chemically converted graphene (CCG) and single-walled carbon nanotubes (SWNTs). Pyrene- and porphyrin-based glycoconjugates were functionalized noncovalently on the surface of CCG-FET and SWNT-FET devices, which were then treated with 2 µM of nonspecific and specific lectins. In particular, three different lectins (PA-IL, PA-IIL and ConA) and three carbohydrate epitopes (galactose, fucose and mannose) were tested. The responses of 36 different devices were compared and rationalized using computer-aided models of carbon nanostructure/glycoconjugate interactions. Glycoconjugates surface coverage in addition to one-dimensional structures of SWNTs resulted in optimal lectin detection. Additionally, lectin titration data of SWNT- and CCG-based biosensors were used to calculate lectin dissociation constants (Kd) and compare them to the values obtained from the isothermal titration microcalorimetry (ITC) technique. PMID:22136380

Carbon-Nanotube-Based Chemical Gas Sensor

NASA Technical Reports Server (NTRS)

Kaul, Arunpama B.

2010-01-01

Conventional thermal conductivity gauges (e.g. Pirani gauges) lend themselves to applications such as leak detectors, or in gas chromatographs for identifying various gas species. However, these conventional gauges are physically large, operate at high power, and have a slow response time. A single-walled carbon-nanotube (SWNT)-based chemical sensing gauge relies on differences in thermal conductance of the respective gases surrounding the CNT as it is voltage-biased, as a means for chemical identification. Such a sensor provides benefits of significantly reduced size and compactness, fast response time, low-power operation, and inexpensive manufacturing since it can be batch-fabricated using Si integrated-circuit (IC) process technology.

Scalability of carbon-nanotube-based thin film transistors for flexible electronic devices manufactured using an all roll-to-roll gravure printing system

PubMed Central

Koo, Hyunmo; Lee, Wookyu; Choi, Younchang; Sun, Junfeng; Bak, Jina; Noh, Jinsoo; Subramanian, Vivek; Azuma, Yasuo; Majima, Yutaka; Cho, Gyoujin

2015-01-01

To demonstrate that roll-to-roll (R2R) gravure printing is a suitable advanced manufacturing method for flexible thin film transistor (TFT)-based electronic circuits, three different nanomaterial-based inks (silver nanoparticles, BaTiO3 nanoparticles and single-walled carbon nanotubes (SWNTs)) were selected and optimized to enable the realization of fully printed SWNT-based TFTs (SWNT-TFTs) on 150-m-long rolls of 0.25-m-wide poly(ethylene terephthalate) (PET). SWNT-TFTs with 5 different channel lengths, namely, 30, 80, 130, 180, and 230 μm, were fabricated using a printing speed of 8 m/min. These SWNT-TFTs were characterized, and the obtained electrical parameters were related to major mechanical factors such as web tension, registration accuracy, impression roll pressure and printing speed to determine whether these mechanical factors were the sources of the observed device-to-device variations. By utilizing the electrical parameters from the SWNT-TFTs, a Monte Carlo simulation for a 1-bit adder circuit, as a reference, was conducted to demonstrate that functional circuits with reasonable complexity can indeed be manufactured using R2R gravure printing. The simulation results suggest that circuits with complexity, similar to the full adder circuit, can be printed with a 76% circuit yield if threshold voltage (Vth) variations of less than 30% can be maintained. PMID:26411839

Anti-tumor response induced by immunologically modified carbon nanotubes and laser irradiation using rat mammary tumor model

NASA Astrophysics Data System (ADS)

Acquaviva, Joseph T.; Hasanjee, Aamr M.; Bahavar, Cody F.; Zhou, Fefian; Liu, Hong; Howard, Eric W.; Bullen, Liz C.; Silvy, Ricardo P.; Chen, Wei R.

2015-03-01

Laser immunotherapy (LIT) is being developed as a treatment modality for metastatic cancer which can destroy primary tumors and induce effective systemic anti-tumor responses by using a targeted treatment approach in conjunction with the use of a novel immunoadjuvant, glycated chitosan (GC). In this study, Non-invasive Laser Immunotherapy (NLIT) was used as the primary treatment mode. We incorporated single-walled carbon nanotubes (SWNTs) into the treatment regimen to boost the tumor-killing effect of LIT. SWNTs and GC were conjugated to create a completely novel, immunologically modified carbon nanotube (SWNT-GC). To determine the efficacy of different laser irradiation durations, 5 minutes or 10 minutes, a series of experiments were performed. Rats were inoculated with DMBA-4 cancer cells, a highly aggressive metastatic cancer cell line. Half of the treatment group of rats receiving laser irradiation for 10 minutes survived without primary or metastatic tumors. The treatment group of rats receiving laser irradiation for 5 minutes had no survivors. Thus, Laser+SWNT-GC treatment with 10 minutes of laser irradiation proved to be effective at reducing tumor size and inducing long-term anti-tumor immunity.

Deep, noninvasive imaging and surgical guidance of submillimeter tumors using targeted M13-stabilized single-walled carbon nanotubes

PubMed Central

Ghosh, Debadyuti; Bagley, Alexander F.; Na, Young Jeong; Birrer, Michael J.; Bhatia, Sangeeta N.; Belcher, Angela M.

2014-01-01

Highly sensitive detection of small, deep tumors for early diagnosis and surgical interventions remains a challenge for conventional imaging modalities. Second-window near-infrared light (NIR2, 950–1,400 nm) is promising for in vivo fluorescence imaging due to deep tissue penetration and low tissue autofluorescence. With their intrinsic fluorescence in the NIR2 regime and lack of photobleaching, single-walled carbon nanotubes (SWNTs) are potentially attractive contrast agents to detect tumors. Here, targeted M13 virus-stabilized SWNTs are used to visualize deep, disseminated tumors in vivo. This targeted nanoprobe, which uses M13 to stably display both tumor-targeting peptides and an SWNT imaging probe, demonstrates excellent tumor-to-background uptake and exhibits higher signal-to-noise performance compared with visible and near-infrared (NIR1) dyes for delineating tumor nodules. Detection and excision of tumors by a gynecological surgeon improved with SWNT image guidance and led to the identification of submillimeter tumors. Collectively, these findings demonstrate the promise of targeted SWNT nanoprobes for noninvasive disease monitoring and guided surgery. PMID:25214538

Deep, noninvasive imaging and surgical guidance of submillimeter tumors using targeted M13-stabilized single-walled carbon nanotubes.

PubMed

Ghosh, Debadyuti; Bagley, Alexander F; Na, Young Jeong; Birrer, Michael J; Bhatia, Sangeeta N; Belcher, Angela M

2014-09-23

Highly sensitive detection of small, deep tumors for early diagnosis and surgical interventions remains a challenge for conventional imaging modalities. Second-window near-infrared light (NIR2, 950-1,400 nm) is promising for in vivo fluorescence imaging due to deep tissue penetration and low tissue autofluorescence. With their intrinsic fluorescence in the NIR2 regime and lack of photobleaching, single-walled carbon nanotubes (SWNTs) are potentially attractive contrast agents to detect tumors. Here, targeted M13 virus-stabilized SWNTs are used to visualize deep, disseminated tumors in vivo. This targeted nanoprobe, which uses M13 to stably display both tumor-targeting peptides and an SWNT imaging probe, demonstrates excellent tumor-to-background uptake and exhibits higher signal-to-noise performance compared with visible and near-infrared (NIR1) dyes for delineating tumor nodules. Detection and excision of tumors by a gynecological surgeon improved with SWNT image guidance and led to the identification of submillimeter tumors. Collectively, these findings demonstrate the promise of targeted SWNT nanoprobes for noninvasive disease monitoring and guided surgery.

Electromechanics in MoS2 and WS2: nanotubes vs. monolayers

PubMed Central

Ghorbani-Asl, Mahdi; Zibouche, Nourdine; Wahiduzzaman, Mohammad; Oliveira, Augusto F.; Kuc, Agnieszka; Heine, Thomas

2013-01-01

The transition-metal dichalcogenides (TMD) MoS2 and WS2 show remarkable electromechanical properties. Strain modifies the direct band gap into an indirect one, and substantial strain even induces an semiconductor-metal transition. Providing strain through mechanical contacts is difficult for TMD monolayers, but state-of-the-art for TMD nanotubes. We show using density-functional theory that similar electromechanical properties as in monolayer and bulk TMDs are found for large diameter TMD single- (SWNT) and multi-walled nanotubes (MWNTs). The semiconductor-metal transition occurs at elongations of 16%. We show that Raman signals of the in-plane and out-of-plane lattice vibrations depend significantly and linearly on the strain, showing that Raman spectroscopy is an excellent tool to determine the strain of the individual nanotubes and hence monitor the progress of nanoelectromechanical experiments in situ. TMD MWNTs show twice the electric conductance compared to SWNTs, and each wall of the MWNTs contributes to the conductance proportional to its diameter. PMID:24129919

Fluorescent Polymer-Single-Walled Carbon Nanotube Complexes with Charged and Noncharged Dendronized Perylene Bisimides for Bioimaging Studies.

PubMed

Huth, Katharina; Glaeske, Mareen; Achazi, Katharina; Gordeev, Georgy; Kumar, Shiv; Arenal, Raúl; Sharma, Sunil K; Adeli, Mohsen; Setaro, Antonio; Reich, Stephanie; Haag, Rainer

2018-06-05

Fluorescent nanomaterials are expected to revolutionize medical diagnostic, imaging, and therapeutic tools due to their superior optical and structural properties. Their inefficient water solubility, cell permeability, biodistribution, and high toxicity, however, limit the full potential of their application. To overcome these obstacles, a water-soluble, fluorescent, cytocompatible polymer-single-walled carbon nanotube (SWNT) complex is introduced for bioimaging applications. The supramolecular complex consists of an alkylated polymer conjugated with neutral hydroxylated or charged sulfated dendronized perylene bisimides (PBIs) and SWNTs as a general immobilization platform. The polymer backbone solubilizes the SWNTs, decorates them with fluorescent PBIs, and strongly improves their cytocompatibility by wrapping around the SWNT scaffold. In photophysical measurements and biological in vitro studies, sulfated complexes exhibit superior optical properties, cellular uptake, and intracellular staining over their hydroxylated analogs. A toxicity assay confirms the highly improved cytocompatibility of the polymer-wrapped SWNTs toward surfactant-solubilized SWNTs. In microscopy studies the complexes allow for the direct imaging of the SWNTs' cellular uptake via the PBI and SWNT emission using the 1st and 2nd optical window for bioimaging. These findings render the polymer-SWNT complexes with nanometer size, dual fluorescence, multiple charges, and high cytocompatibility as valuable systems for a broad range of fluorescence bioimaging studies. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ultralow percolation threshold of single walled carbon nanotube-epoxy composites synthesized via an ionic liquid dispersant/initiator

NASA Astrophysics Data System (ADS)

Watters, Arianna L.; Palmese, Giuseppe R.

2014-09-01

Uniform dispersion of single walled carbon nanotubes (SWNTs) in an epoxy was achieved by a streamlined mechano-chemical processing method. SWNT-epoxy composites were synthesized using a room temperature ionic liquid (IL) with an imidazolium cation and dicyanamide anion. The novel approach of using ionic liquid that behaves as a dispersant for SWNTs and initiator for epoxy polymerization greatly simplifies nanocomposite synthesis. The material was processed using simple and scalable three roll milling. The SWNT dispersion of the resultant composite was evaluated by electron microscopy and electrical conductivity measurements in conjunction with percolation theory. Processing conditions were optimized to achieve the lowest possible percolation threshold, 4.29 × 10-5 volume fraction SWNTs. This percolation threshold is among the best reported in literature yet it was obtained using a streamlined method that greatly simplifies processing.

Effects of carbon nanotubes (CNTs) on the processing and in-vitro degradation of poly(DL-lactide-co-glycolide)/CNT films.

PubMed

Armentano, Ilaria; Dottori, Mariaserena; Puglia, Debora; Kenny, Josè M

2008-06-01

Nanocomposite films based on single wall carbon nanotubes (SWNTs) and poly(DL-lactide-co-glycolide) copolymer (50:50 PLGA) were processed and analyzed. The purpose of this study was to investigate the effect of different functionalization systems on the physical stability and morphology of PLGA films. Both covalent and non covalent functionalization of carbon nanotubes were considered in order to control the interactions between PLGA and SWNTs and to understand the role of the filler in the biodegradation properties. Using a solvent casting process, different PLGA/SWNT nanocomposites were prepared and incubated using organic solution under physiological conditions. In-vitro degradation studies were conducted by measurements of weight loss, infrared spectroscopy, glass transition temperature and SEM observations as a function of the incubation time, over a 9-week period. All PLGA films were degraded by hydrolitical degradation. However, a different degradation mechanism was observed in the case of functionalized SWNTs with respect to pristine material. It has been observed that system composition and SWNT functionalization may play a crucial role on the autocatalytic effect of the degradation process. These studies suggest that the degradation kinetics of the films can be engineered by varying carbon nanotube (CNT) content and functionalization. The combination of biodegradable polymers and CNTs opens a new perspective in the self-assembly of nanomaterials and nanodevices.

Aligned carbon nanotube based ultrasonic microtransducers for durability monitoring in civil engineering.

PubMed

Lebental, B; Chainais, P; Chenevier, P; Chevalier, N; Delevoye, E; Fabbri, J-M; Nicoletti, S; Renaux, P; Ghis, A

2011-09-30

Structural health monitoring of porous materials such as concrete is becoming a major component in our resource-limited economy, as it conditions durable exploitation of existing facilities. Durability in porous materials depends on nanoscale features which need to be monitored in situ with nanometric resolution. To address this problem, we put forward an approach based on the development of a new nanosensor, namely a capacitive micrometric ultrasonic transducer whose vibrating membrane is made of aligned single-walled carbon nanotubes (SWNT). Such sensors are meant to be embedded in large numbers within a porous material in order to provide information on its durability by monitoring in situ neighboring individual micropores. In the present paper, we report on the feasibility of the key building block of the proposed sensor: we have fabricated well-aligned, ultra-thin, dense SWNT membranes that show above-nanometer amplitudes of vibration over a large range of frequencies spanning from 100 kHz to 5 MHz.

Controllable synthesis of single-walled carbon nanotube framework membranes and capsules.

PubMed

Song, Changsik; Kwon, Taeyun; Han, Jae-Hee; Shandell, Mia; Strano, Michael S

2009-12-01

Controlling the morphology of membrane components at the nanometer scale is central to many next-generation technologies in water purification, gas separation, fuel cell, and nanofiltration applications. Toward this end, we report the covalent assembly of single-walled carbon nanotubes (SWNTs) into three-dimensional framework materials with intertube pores controllable by adjusting the size of organic linker molecules. The frameworks are fashioned into multilayer membranes possessing linker spacings from 1.7 to 3.0 nm, and the resulting framework films were characterized, including transport properties. Nanoindentation measurements by atomic force microscopy show that the spring constant of the SWNT framework film (22.6 +/- 1.2 N/m) increased by a factor of 2 from the control value (10.4 +/- 0.1 N/m). The flux ratio comparison in a membrane-permeation experiment showed that larger spacer sizes resulted in larger pore structures. This synthetic method was equally efficient on silica microspheres, which could then be etched to create all-SWNT framework, hollow capsules approximately 5 mum in diameter. These hollow capsules are permeable to organic and inorganic reagents, allowing one to form inorganic nanoparticles, for example, that become entrapped within the capsule. The ability to encapsulate functional nanomaterials inside perm-selective SWNT cages and membranes may find applications in new adsorbents, novel catalysts, and drug delivery vehicles.

The interaction of a gold atom with carbon nanohorn and carbon nanotube tips and their complexes with a CO molecule: A first principle calculation

NASA Astrophysics Data System (ADS)

Khongpracha, P.; Probst, M.; Limtrakul, J.

2008-07-01

The interactions of a gold atom with: (a) a single-wall carbon nanohorn (SWNH) conic tip; (b) with a single-wall carbon nanotube (SWNT) tip; and (c) their complexes with a CO molecule were studied using first-principle calculations based on density functional theory. The analysis of the pyramidalization angle (θp) as well as the π-orbital misalignment angles indicate that there should be many reactive carbon sites on the tips of SWNH and SWNT. It was found that SWNH provides reactive sites that can more selectively interact with the target atom. We identified five sites on both the SWNT tip and the nanohorn where attachment of a gold atom leads to a stable complex. This metal is found to be bi-coordinated with the tip of SWNH, while it is mono-coordinated with the SWNT tip. The largest interaction energies are -10.75 kcal/mol and -16.17 kcal/mol, respectively. The CO probe molecule binds to Au on the Au/SWNH or Au/SWNT tips with interaction energies of -22.34 and -18.29 kcal/mol, respectively. The main contributions of the interaction with both carbon nanostructures stems from σ-donation and π-backbonding. The results suggest that SWNHs could be one of the promising candidates for the development of high-specifity nanosensors.

Embedded Carbon Nanotube Networks for Damage Precursor Detection

DTIC Science & Technology

2014-01-01

3Thostenson, E. T.; Chou, T.-W. Carbon Nanotube Networks: Sensing of Distributed Strain and Damage for Life Prediction and Self - Healing . Advanced...3 Figure 2. Rubber dogbone mold...room temperature vulcanizing rubber to create the final mold. The rubber was mixed with Tin NW Catalyst at a 10:1 ratio. The viscous liquid rubber

Preparation and characterization of flexible asymmetric supercapacitors based on transition-metal-oxide nanowire/single-walled carbon nanotube hybrid thin-film electrodes.

PubMed

Chen, Po-Chiang; Shen, Guozhen; Shi, Yi; Chen, Haitian; Zhou, Chongwu

2010-08-24

In the work described in this paper, we have successfully fabricated flexible asymmetric supercapacitors (ASCs) based on transition-metal-oxide nanowire/single-walled carbon nanotube (SWNT) hybrid thin-film electrodes. These hybrid nanostructured films, with advantages of mechanical flexibility, uniform layered structures, and mesoporous surface morphology, were produced by using a filtration method. Here, manganese dioxide nanowire/SWNT hybrid films worked as the positive electrode, and indium oxide nanowire/SWNT hybrid films served as the negative electrode in a designed ASC. In our design, charges can be stored not only via electrochemical double-layer capacitance from SWNT films but also through a reversible faradic process from transition-metal-oxide nanowires. In addition, to obtain stable electrochemical behavior during charging/discharging cycles in a 2 V potential window, the mass balance between two electrodes has been optimized. Our optimized hybrid nanostructured ASCs exhibited a superior device performance with specific capacitance of 184 F/g, energy density of 25.5 Wh/kg, and columbic efficiency of approximately 90%. In addition, our ASCs exhibited a power density of 50.3 kW/kg, which is 10-fold higher than obtained in early reported ASC work. The high-performance hybrid nanostructured ASCs can find applications in conformal electrics, portable electronics, and electrical vehicles.

Extinction coefficients and purity of single-walled carbon nanotubes.

PubMed

Zhao, B; Itkis, M E; Niyogi, S; Hu, H; Perea, D E; Haddon, R C

2004-11-01

Single-walled carbon nanotubes (SWNTs) hold great promise for advanced applications in aerospace, electronics and medicine, yet these industries require materials with rigorous quality control. There are currently no accepted standards for quality assurance or quality control among the commercial suppliers of SWNTs. We briefly discuss the applicability of various techniques to measure SWNT purity and review, in detail, the advantages of near infrared (NIR) spectroscopy for the quantitative assessment of the bulk carbonaceous purity of SWNTs. We review the use of solution phase NIR spectroscopy for the analysis and characterization of a variety of carbon materials, emphasizing SWNTs produced by the electric arc (EA), laser oven (LO) and HiPco (HC) methods. We consider the applicability of Beer's law to carbon materials dispersed in dimethylformamide (DMF) and the effective extinction coefficients that are obtained from such dispersions. Analysis of the areal absorptivities of the second interband transition of semiconducting EA-produced SWNTs for a number of samples of differing purities has lead to an absolute molar extinction coefficient for the carbonaceous impurities in EA-produced SWNT samples. We conclude that NIR spectroscopy is the clear method of choice for the assessment of the bulk carbonaceous purity of EA-produced SWNTs, and we suggest that an absolute determination of the purity of SWNTs is within reach. Continued work in this area is expected to lead to a universal method for the assessment of the absolute bulk purity of SWNTs from all sources--such a development will be of great importance for nanotube science and for future customers for this product.

Pressure dependence of the radial mode frequency in carbon nanotubes

NASA Astrophysics Data System (ADS)

Venkateswaran, Uma; Masica, D.; Sumanasekara, G.; Eklund, P.

2003-03-01

Recently, an analytical expression for the radial breathing mode frequency, ω_R, was derived by considering the oscillations of a thin hollow cylinder.[1] Using this result and the experimental pressure-dependence of the elastic and lattice constants of graphite, we show that the pressure derivative of ωR depends inversely on the nanotube diameter, D. Since ωR also depends inversely on D, the above result implies that the logarithmic pressure derivative of ω_R, i.e., dlnω_R/dP should be independent of D. We have performed high-pressure Raman scattering experiments on HiPCO-SWNT bundles using different laser excitations, thereby probing the radial modes from different diameter tubes. These measurements show an increase in dlnω_R/dP with increasing D. This difference between the predictions and experiments suggests that the main contribution to ω_R's pressure dependence in SWNT bundles stems from the tube-tube interactions within the bundle and from pressure-induced distortions to the tube cross-section. [1] G.D. Mahan, Phys. Rev. B 65, 235402 (2002).

Targeting single-walled carbon nanotubes for the treatment of breast cancer using photothermal therapy

NASA Astrophysics Data System (ADS)

Neves, Luís F. F.; Krais, John J.; Van Rite, Brent D.; Ramesh, Rajagopal; Resasco, Daniel E.; Harrison, Roger G.

2013-09-01

This paper focuses on the targeting of single-walled carbon nanotubes (SWNTs) for the treatment of breast cancer with minimal side effects using photothermal therapy. The human protein annexin V (AV) binds specifically to anionic phospholipids expressed externally on the surface of tumour cells and endothelial cells that line the tumour vasculature. A 2 h incubation of the SWNT-AV conjugate with proliferating endothelial cells followed by washing and near-infrared (NIR) irradiation at a wavelength of 980 nm was enough to induce significant cell death; there was no significant cell death with irradiation or the conjugate alone. Administration of the same conjugate i.v. in BALB/c female mice with implanted 4T1 murine mammary at a dose of 0.8 mg SWNT kg-1 and followed one day later by NIR irradiation of the tumour at a wavelength of 980 nm led to complete disappearance of implanted 4T1 mouse mammary tumours for the majority of the animals by 11 days since the irradiation. The combination of the photothermal therapy with the immunoadjuvant cyclophosphamide resulted in increased survival. The in vivo results suggest the SWNT-AV/NIR treatment is a promising approach to treat breast cancer.

Polymer nanofiber-carbon nanotube network generating circuits

NASA Astrophysics Data System (ADS)

Mutlu, Mustafa Umut; Akın, Osman; Yildiz, Ümit Hakan

2018-02-01

The polymer nanofiber carbon nanotube (CNT) based devices attracts attention since they promise high performance for next generation devices such as wearable electronics, ultra-light weighted appliances and foldable devices. This abstract describes the utilization of polymer nanofibers and CNT as major component of low cost foldable photo-resistor. We use polymer nanofiber as template guiding CNTs to generate nanocircuits and conductive sensing network. The controlled combination of CNTs and polymer nanofibers provide opportunities for device miniaturization without loss of performance. The nanofiber-CNT network based photo-resistor exhibits broad band response 400 to 1600 nm that holding promises for ultra-thin devices and new sensing platforms.

Spin polarization measurements and sensor applications in thin films and carbon nanotube-based devices

NASA Astrophysics Data System (ADS)

Sanders, Jeff T.

The unique properties of carbon nanotubes (CNTs) show a great deal of potential for nanoelectronic devices, spintronic devices, biosensing and chemical sensing applications. Their applicability as interconnects for spintronic devices derives from their one-dimensionality and theoretically predicted preservation of spin current. In this work, we combine an investigation of spin polarization in materials such as half-metallic oxides in thin film and bulk form with studies on several aspects of CNTs for sensing and spin transport applications. These two areas of study are intimately related within the umbrella of spin-electronics and nanoscale sensors that are being pursued with great topical interest in recent times. A measurement system has been developed to perform Point-Contact Andreev Reflection (PCAR) in the presence of variable magnetic fields and temperatures. It was designed and built, accepted for patent by the USF, and submitted to the U.S. Patent Office. A study of spin polarization in superconductor-magnet junctions has been performed over a wide range in magnetic fields (0 to 3T) and temperature (2 to 300K) on several systems including Cu, SrRuO3, LaSrMnO3, and CrO2. Spin transport experiments have been extended to single walled carbon nanotube (SWNT) networks in order to explore spin transport in nanotube networks for potential sensor applications. Carbon nanotube networks have been used as the electronic material for chemical and biological sensing where capacitance and conductance response to the adsorbtion of a chemical or biological analyte are simultaneously measured and a very fast response and recovery is observed. Chemical specificity has been investigated through different means since a goal of the U.S. Navy is to have an array of these sensors, each chemically specific to a unique analyte. Finally, research is ongoing in the analysis of our PCAR spectra in the SrRuO3 series and the La1-x(Ca, Ba, Sr)xMnO 3 to investigate the square root

Flame Synthesis Of Single-Walled Carbon Nanotubes And Nanofibers

NASA Technical Reports Server (NTRS)

Wal, Randy L. Vander; Berger, Gordon M.; Ticich, Thomas M.

2003-01-01

Carbon nanotubes are widely sought for a variety of applications including gas storage, intercalation media, catalyst support and composite reinforcing material [1]. Each of these applications will require large scale quantities of CNTs. A second consideration is that some of these applications may require redispersal of the collected CNTs and attachment to a support structure. If the CNTs could be synthesized directly upon the support to be used in the end application, a tremendous savings in post-synthesis processing could be realized. Therein we have pursued both aerosol and supported catalyst synthesis of CNTs. Given space limitations, only the aerosol portion of the work is outlined here though results from both thrusts will be presented during the talk. Aerosol methods of SWNT, MWNT or nanofiber synthesis hold promise of large-scale production to supply the tonnage quantities these applications will require. Aerosol methods may potentially permit control of the catalyst particle size, offer continuous processing, provide highest product purity and most importantly, are scaleable. Only via economy of scale will the cost of CNTs be sufficient to realize the large-scale structural and power applications on both earth and in space. Present aerosol methods for SWNT synthesis include laser ablation of composite metalgraphite targets or thermal decomposition/pyrolysis of a sublimed or vaporized organometallic [2]. Both approaches, conducted within a high temperature furnace, have produced single-walled nanotubes (SWNTs). The former method requires sophisticated hardware and is inherently limited by the energy deposition that can be realized using pulsed laser light. The latter method, using expensive organometallics is difficult to control for SWNT synthesis given a range of gasparticle mixing conditions along variable temperature gradients; multi-walled nanotubes (MWNTs) are a far more likely end products. Both approaches require large energy expenditures and

Facile Synthesis of Novel Networked Ultralong Cobalt Sulfide Nanotubes and Its Application in Supercapacitors.

PubMed

Liu, Sangui; Mao, Cuiping; Niu, Yubin; Yi, Fenglian; Hou, Junke; Lu, Shiyu; Jiang, Jian; Xu, Maowen; Li, Changming

2015-11-25

Ultralong cobalt sulfide (CoS(1.097)) nanotube networks are synthesized by a simple one-step solvothermal method without any surfactant or template. A possible formation mechanism for the growth processes is proposed. Owing to the hollow structure and large specific area, the novel CoS(1.097) materials present outstanding electrochemical properties. Electrochemical measurements for supercapacitors show that the as-prepared ultralong CoS(1.097) nanotube networks exhibit high specific capacity, good capacity retention, and excellent Coulombic efficiency.

Structure of single-wall carbon nanotubes purified and cut using polymer

NASA Astrophysics Data System (ADS)

Zhang, M.; Yudasaka, M.; Koshio, A.; Jabs, C.; Ichihashi, T.; Iijima, S.

2002-01-01

Following on from our previous report that a monochlorobenzene solution of polymethylmethacrylate is useful for purifying and cutting single-wall carbon nanotubes (SWNTs) and thinning SWNT bundles, we show in this report that polymer and residual amorphous carbon can be removed by burning in oxygen gas. The SWNTs thus obtained had many holes (giving them a worm-eaten look) and were thermally unstable. Such severe damage caused by oxidation is unusual for SWNTs; we think that they were chemically damaged during ultrasonication in the monochlorobenzene solution of polymethylmethacrylate.

Electrical and optical properties of poly(3,4-ethylenedioxythiophene) oxidized with poly(4-styrenesulfonate) and AuCl3-doped reduced graphene oxide/single-walled carbon nanotube films for ultraviolet light-emitting diodes.

PubMed

Lee, Byeong Ryong; Lee, Jae Hoon; Kim, Kyeong Heon; Kim, Hee-Dong; Kim, Tae Geun

2014-12-01

We report the effects of poly(3,4-ethylenedioxythiophene) oxidized with poly(4-styrenesulfonate) ( PSS) and gold chloride (AuCl) co-doping on the electrical and optical properties of reduced graphene oxide (RGO)/single-walled carbon nanotube (SWNT) films fabricated by dipcoating methods. The RGO/SWNT films were doped with both AuCl3 dissolved in nitromethane and PSS hole injection layers by spin coating to improve their electrical properties by increasing the work function of the RGO/SWNT films, thereby reducing the Schottky barrier height between the RGO/SWNT and p-GaN films. As a result, we obtained a reduced sheet resistance of 851.9 Ω/Ω and a contact resistance of 1.97 x 10(-1) Ω x cm2, together with a high transmittance of 84.1% at 380 nm. The contact resistance of these films should be further reduced to fully utilize the feature of the electrode scheme proposed in this work, but the current result suggests its potential use as a transparent conductive electrode for ultraviolet light-emitting diodes.

Imaging mesenchymal stem cells containing single wall nanotube nanoprobes in a 3D scaffold using photo-thermal optical coherence tomography

NASA Astrophysics Data System (ADS)

Connolly, Emma; Subhash, Hrebesh M.; Leahy, Martin; Rooney, Niall; Barry, Frank; Murphy, Mary; Barron, Valerie

2014-02-01

Despite the fact, that a range of clinically viable imaging modalities, such as magnetic resonance imaging (MRI), computed tomography (CT), photo emission tomography (PET), ultrasound and bioluminescence imaging are being optimised to track cells in vivo, many of these techniques are subject to limitations such as the levels of contrast agent required, toxic effects of radiotracers, photo attenuation of tissue and backscatter. With the advent of nanotechnology, nanoprobes are leading the charge to overcome these limitations. In particular, single wall nanotubes (SWNT) have been shown to be taken up by cells and as such are effective nanoprobes for cell imaging. Consequently, the main aim of this research is to employ mesenchymal stem cells (MSC) containing SWNT nanoprobes to image cell distribution in a 3D scaffold for cartilage repair. To this end, MSC were cultured in the presence of 32μg/ml SWNT in cell culture medium (αMEM, 10% FBS, 1% penicillin/streptomycin) for 24 hours. Upon confirmation of cell viability, the MSC containing SWNT were encapsulated in hyaluronic acid gels and loaded on polylactic acid polycaprolactone scaffolds. After 28 days in complete chondrogenic medium, with medium changes every 2 days, chondrogenesis was confirmed by the presence of glycosaminoglycan. Moreover, using photothermal optical coherence tomography (PT-OCT), the cells were seen to be distributed through the scaffold with high resolution. In summary, these data reveal that MSC containing SWNT nanoprobes in combination with PT-OCT offer an exciting opportunity for stem cell tracking in vitro for assessing seeding scaffolds and in vivo for determining biodistribution.

Electromagnetic Characterization of Carbon Nanotube Films Subject to an Oxidative Treatment at Elevated Temperature (Preprint)

DTIC Science & Technology

2010-07-01

response to the tip causes a redistribution of charge on the tip in order to maintain the equipotential surface of the sphere, and also results in a shift...can be obtained. In some instances these treatments lead to uncapping of nanotubes. Geng et al. [25] have shown that the surfaces of SWNT bundles...20] discovered a new and catalyst-free method for the growth of CNTs: surface decomposition of silicon carbide (SiC). This thermal decomposition

Strain Dependence of Photoluminescense of Individual Carbon Nanotubes

NASA Technical Reports Server (NTRS)

Nikolaev, Pavel N.; Leeuw, Tonya K.; Tsyboulski, Dmitri A.; Bachilo, Sergei M.; Weisman, Bruce; Arepalli, Sivaram

2007-01-01

We have investigated strain dependence of photoluminescense (PL) spectra of single wall carbon nanotubes (SWNT). Nanotubes were sparsely dispersed in a thin PMMA film applied to acrylic bar, and strained in both compression and extension by bending this bar in either direction in a homebuilt four-point bending rig. The average surface strain was measured with high accuracy by a resistive strain gage applied on top of the film. The near infrared imaging and spectroscopy were performed on the inverted microscope equipped with high numerical aperture reflective objective lens and InGaAs CCD cameras. PL was excited with a diode laser at either 658, 730 or 785 nm, linearly polarized in the direction of the strain. We were able to measure (n,m) types and orientation of individual nanotubes with respect to strain direction and strain dependence of their PL maxima. It was found that PL peak shifts with respect to the values measured in SDS micelles are a sum of three components. First, a small environmental shift due to difference in the dielectric constant of the surrounding media, that is constant and independent of the nanotube type. Second, shift due to isotropic compression of the film during drying. Third, shifts produced by the uniaxial loading of the film in the experiment. Second and third shifts follow expression based on the first-order expansion of the TB hamiltonian. Their magnitude is proportional to the nanotube chiral angle and strain, and direction is determined by the nanotube quantum number. PL strain dependence measured for a number of various nanotube types allows to estimate TB carbon-carbon transfer integral.

Electrothermal actuation based on carbon nanotube network in silicone elastomer

NASA Astrophysics Data System (ADS)

Chen, L. Z.; Liu, C. H.; Hu, C. H.; Fan, S. S.

2008-06-01

The authors report an electrothermal actuator, which is fabricated by involving carbon nanotube network into the silicone elastomer. The actuators exhibit excellent performances as good as normal dielectric elastomer actuators while working under much lower voltages (e.g., 1.5Vmm-1). They are longitudinal actuators and there is no need for stacking or rolling sheets of materials. In addition, they can satisfy the demand of different voltage applications ranging from dozens of voltages to thousands of voltages by using different carbon nanotube loading composites. Visible maximal strain of 4.4% occurs at an electric power intensity around 0.03Wmm-3.

Immunostimulatory CpG on Carbon Nanotubes Selectively Inhibits Migration of Brain Tumor Cells.

PubMed

Alizadeh, Darya; White, Ethan E; Sanchez, Teresa C; Liu, Shunan; Zhang, Leying; Badie, Behnam; Berlin, Jacob M

2018-05-16

Even when treated with aggressive current therapies, patients with glioblastoma usually survive less than two years and exhibit a high rate of recurrence. CpG is an oligonucleotide that activates the innate immune system via Toll-like receptor 9 (TLR9) activation. Injection of CpG into glioblastoma tumors showed promise as an immunotherapy in mouse models but proved disappointing in human trials. One aspect of glioma that is not addressed by CpG therapy alone is the highly invasive nature of glioma cells, which is associated with resistance to radiation and chemotherapy. Here, we demonstrate that single-walled carbon nanotubes noncovalently functionalized with CpG (SWNT/CpG), which retain the immunostimulatory property of the CpG, selectively inhibit the migration of glioma cells and not macrophages without affecting cell viability or proliferation. SWNT/CpG also selectively decreased NF-κB activation in glioma cells, while activating macrophages by induction of the TLR9/NF-κB pathway, as we have previously reported. The migration inhibition of glioma cells was correlated with selective reduction of intracellular levels of reactive oxygen species (ROS), suggesting that an antioxidant-based mechanism mediates the observed effects. To the best of our knowledge, SWNT/CpG is the first nanomaterial that inhibits the migration of cancer cells while stimulating the immune system.

Physicochemical and biological characterization of single-walled and double-walled carbon nanotubes in biological media.

PubMed

Liu, Wen-Te; Bien, Mauo-Ying; Chuang, Kai-Jen; Chang, Ta-Yuan; Jones, Tim; BéruBé, Kelly; Lalev, Georgi; Tsai, Dai-Hua; Chuang, Hsiao-Chi; Cheng, Tsun-Jen

2014-09-15

To study the toxicity of nanoparticles under relevant conditions, it is important to reproducibly disperse nanoparticles in biological media in in vitro and in vivo studies. Here, single-walled nanotubes (SWNTs) and double-walled nanotubes (DWNTs) were physicochemically and biologically characterized when dispersed in phosphate-buffered saline (PBS) and bovine serum albumin (BSA). BSA-SWNT/DWNT interaction resulted in a reduction of aggregation and an increase in particle stabilization. Based on the protein sequence coverage and protein binding results, DWNTs exhibited higher protein binding than SWNTs. SWNT and DWNT suspensions in the presence of BSA increased interleukin-6 (IL-6) levels and reduced tumor necrosis factor-alpha (TNF-α) levels in A549 cells as compared to corresponding samples in the absence of BSA. We next determined the effects of SWNTs and DWNTs on pulmonary protein modification using bronchoalveolar lavage fluid (BALF) as a surrogate collected form BALB/c mice. The BALF proteins bound to SWNTs (13 proteins) and DWNTs (11 proteins), suggesting that these proteins were associated with blood coagulation pathways. Lastly, we demonstrated the importance of physicochemical and biological alterations of SWNTs and DWNTs when dispersed in biological media, since protein binding may result in the misinterpretation of in vitro results and the activation of protein-regulated biological responses. Crown Copyright © 2014. Published by Elsevier B.V. All rights reserved.

Comparison study of morphology and crystallization behavior of polyethylene and poly(ethylene oxide) on single-walled carbon nanotubes.

PubMed

Zheng, Xiaoli; Xu, Qun

2010-07-29

In this work, we provided a comparison study of morphology and crystallization behavior of polyethylene (PE) and poly(ethylene oxide) (PEO) on single-walled carbon nanotubes (SWNTs) with assistance of supercritical CO(2). The resulting polymer/SWNT nanohybrids were characterized by transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, Raman spectra, wide-angle X-ray diffraction, and differential scanning calorimetry. SWNT small bundles were decorated by PE lamellar crystals, forming nanohybrid "shish-kebab" (NHSK) structure, whereas SWNTs were only wrapped by a thin amorphous polymer coating in the case of PEO. The varying morphologies of the nanohybrids were found to depend on the molecular conformation and the interactions between polymer chains and SWNTs. Nonisothermal experiments showed that SWNTs provided heterogeneous nucleation sites for PE crystallization, while the NHSK structure hindered polymer chain diffusion and crystal growth. Also, SWNTs played antinucleation effect on PEO. In addition, the formation mechanism analysis indicated that PE chains preferred to form a homogeneous coating along the tube axis before proceeding to kebab crystal growth. The purpose of this work is to enlarge the area of theoretical understanding of introducing precisely hierarchical structures on carbon nanotubes, which are important for functional design in nanodevice applications.

A dioxaborine cyanine dye as a photoluminescence probe for sensing carbon nanotubes.

PubMed

Al Araimi, Mohammed; Lutsyk, Petro; Verbitsky, Anatoly; Piryatinski, Yuri; Shandura, Mykola; Rozhin, Aleksey

2016-01-01

The unique properties of carbon nanotubes have made them the material of choice for many current and future industrial applications. As a consequence of the increasing development of nanotechnology, carbon nanotubes show potential threat to health and environment. Therefore, development of efficient method for detection of carbon nanotubes is required. In this work, we have studied the interaction of indopentamethinedioxaborine dye (DOB-719) and single-walled carbon nanotubes (SWNTs) using absorption and photoluminescence (PL) spectroscopy. In the mixture of the dye and the SWNTs we have revealed new optical features in the spectral range of the intrinsic excitation of the dye due to resonance energy transfer from DOB-719 to SWNTs. Specifically, we have observed an emergence of new PL peaks at the excitation wavelength of 735 nm and a redshift of the intrinsic PL peaks of SWNT emission (up to 40 nm) in the near-infrared range. The possible mechanism of the interaction between DOB-719 and SWNTs has been proposed. Thus, it can be concluded that DOB-719 dye has promising applications for designing efficient and tailorable optical probes for the detection of SWNTs.

Transparent conductive carbon nanotubes coated flexible substrate and its application for electronic devices

NASA Astrophysics Data System (ADS)

Rahy, Abdelaziz

The primary goal of this project was to develop a flexible transparent conductor with 100 O/sq with 90% transmittance in the wavelength range of 400-700nm on a flexible substrate. A second objective was to simplify the coating process to be commercially viable. The best result achieved so far was 110 O/sq at 88% transmittance using purified single walled nanotubes (SWNTs) coated on a polyethylene naphthalate (PEN) substrate on both sides. The SWNT sample used was purchased from Carbon Nanotechnologies Inc (CNI). Proper sonication of the single walled nanotubes (SWNTs) with a proper solvent selection with no use of surfactant simplified the overall coating procedure from five steps (prior art method) to three steps utilizing a dip coating method. We also found that the use of metallic SWNTs can significantly improve the conductivity and transmittance compared with the use of mixed SWNTs, i.e., unseparated SWNTs We also studied a possible adhesion mechanism between SWNTs and the surface of PEN; we concluded that pi - pi stacking effect and hydrophobic-to-hydrophobic interaction are the major contributing factors to have CNTs adhere on the surface of the PEN substrate. Working devices of polymer light emitting diodes (PLEDs) and solar cell were successfully fabricated using SWNT coated substrates. A no optimized PLEDs device exhibited low turn-on voltage (˜5V), and the fabricated solar cell functioned. The devices have demonstrated the coated film can be used for potential electronic devices.

Synthesis of subnanometer-diameter vertically aligned single-walled carbon nanotubes with copper-anchored cobalt catalysts

NASA Astrophysics Data System (ADS)

Cui, Kehang; Kumamoto, Akihito; Xiang, Rong; An, Hua; Wang, Benjamin; Inoue, Taiki; Chiashi, Shohei; Ikuhara, Yuichi; Maruyama, Shigeo

2016-01-01

We synthesize vertically aligned single-walled carbon nanotubes (VA-SWNTs) with subnanometer diameters on quartz (and SiO2/Si) substrates by alcohol CVD using Cu-anchored Co catalysts. The uniform VA-SWNTs with a nanotube diameter of 1 nm are synthesized at a CVD temperature of 800 °C and have a thickness of several tens of μm. The diameter of SWNTs was reduced to 0.75 nm at 650 °C with the G/D ratio maintained above 24. Scanning transmission electron microscopy energy-dispersive X-ray spectroscopy (EDS-STEM) and high angle annular dark field (HAADF-STEM) imaging of the Co/Cu bimetallic catalyst system showed that Co catalysts were captured and anchored by adjacent Cu nanoparticles, and thus were prevented from coalescing into a larger size, which contributed to the small diameter of SWNTs. The correlation between the catalyst size and the SWNT diameter was experimentally clarified. The subnanometer-diameter and high-quality SWNTs are expected to pave the way to replace silicon for next-generation optoelectronic and photovoltaic devices.We synthesize vertically aligned single-walled carbon nanotubes (VA-SWNTs) with subnanometer diameters on quartz (and SiO2/Si) substrates by alcohol CVD using Cu-anchored Co catalysts. The uniform VA-SWNTs with a nanotube diameter of 1 nm are synthesized at a CVD temperature of 800 °C and have a thickness of several tens of μm. The diameter of SWNTs was reduced to 0.75 nm at 650 °C with the G/D ratio maintained above 24. Scanning transmission electron microscopy energy-dispersive X-ray spectroscopy (EDS-STEM) and high angle annular dark field (HAADF-STEM) imaging of the Co/Cu bimetallic catalyst system showed that Co catalysts were captured and anchored by adjacent Cu nanoparticles, and thus were prevented from coalescing into a larger size, which contributed to the small diameter of SWNTs. The correlation between the catalyst size and the SWNT diameter was experimentally clarified. The subnanometer-diameter and high

High performance dendrimer functionalized single-walled carbon nanotubes field effect transistor biosensor for protein detection

NASA Astrophysics Data System (ADS)

Rajesh, Sharma, Vikash; Puri, Nitin K.; Mulchandani, Ashok; Kotnala, Ravinder K.

2016-12-01

We report a single-walled carbon nanotube (SWNT) field-effect transistor (FET) functionalized with Polyamidoamine (PAMAM) dendrimer with 128 carboxyl groups as anchors for site specific biomolecular immobilization of protein antibody for C-reactive protein (CRP) detection. The FET device was characterized by scanning electron microscopy and current-gate voltage (I-Vg) characteristic studies. A concentration-dependent decrease in the source-drain current was observed in the regime of clinical significance, with a detection limit of ˜85 pM and a high sensitivity of 20% change in current (ΔI/I) per decade CRP concentration, showing SWNT being locally gated by the binding of CRP to antibody (anti-CRP) on the FET device. The low value of the dissociation constant (Kd = 0.31 ± 0.13 μg ml-1) indicated a high affinity of the device towards CRP analyte arising due to high anti-CRP loading with a better probe orientation on the 3-dimensional PAMAM structure.

Templated Synthesis of Single-Walled Carbon Nanotubes with Specific Structure.

PubMed

Yang, Feng; Wang, Xiao; Li, Meihui; Liu, Xiyan; Zhao, Xiulan; Zhang, Daqi; Zhang, Yan; Yang, Juan; Li, Yan

2016-04-19

Single-walled carbon nanotubes (SWNTs) have shown great potential in various applications attributed to their unique structure-dependent properties. Therefore, the controlled preparation of chemically and structurally pristine SWNTs is a crucial issue for their advanced applications (e.g., nanoelectronics) and has been a great challenge for two decades. Epitaxial growth from well-defined seeds has been shown to be a promising strategy to control the structure of SWNTs. Segments of carbon nanotubes, including short pipes from cutting of preformed nanotubes and caps from opening of fullerenes or cyclodehydrogenation of polycyclic hydrocarbon precursors, have been used as the seeds to grow SWNTs. Single-chirality SWNTs were obtained with both presorted chirality-pure SWNT segments and end caps obtained from polycyclic hydrocarbon molecules with designed structure. The main challenges of nanocarbon-segment-seeded processes are the stability of the seeds, yield, and efficiency. Catalyst-mediated SWNT growth is believed to be more efficient. The composition and morphology of the catalyst nanoparticles have been widely reported to affect the chirality distribution of SWNTs. However, chirality-specific SWNT growth is hard to achieve by alternating catalysts. The specificity of enzyme-catalyzed reactions brings us an awareness of the essentiality of a unique catalyst structure for the chirality-selective growth of SWNTs. Only catalysts with the desired atomic arrangements in their crystal planes can act as structural templates for chirality-specific growth of SWNTs. We have developed a new family of catalysts, tungsten-based intermetallic compounds, which have high melting points and very special crystal structures, to facilitate the growth of SWNTs with designed chirality. By the use of W6Co7 catalysts, (12,6) SWNTs were directly grown with purity higher than 92%. Both high-resolution transmission electron microscopy measurements and density functional theory simulations

Optical and Thermo-optical Properties of Polyimide-Single-Walled Carbon Nanotube Films: Experimental Results and Empirical Equations

NASA Technical Reports Server (NTRS)

Smith, Joseph G., Jr.; Connell, John W.; Watson, Kent A.; Danehy, Paul M.

2005-01-01

The incorporation of single-walled carbon nanotubes (SWNTs) into the bulk of space environmentally durable polymers at loading levels greater than or equal to 0.05 wt % has afforded thin films with surface and volume resistivities sufficient for electrostatic charge mitigation. However, the optical transparency at 500 nm decreased and the thermo-optical properties (solar absorptivity and thermal emissivity) increased with increaed SWNT loading. These properties were also dependent on film thickness. The absorbance characteristics of the films as a function of SWNT loading and film thickness were measured and determined to follow the classical Beer-Lambert law. Based on these results, an empirical relationship was derived and molar absorptivities determined for both the SWNTs and polymer matrix to provide a predictive approximation of these properties. The molar absorptivity determined for SWNTs dispersed in the polymer was comparable to reported solution determined values for HiPco SWNTs.

Life-cycle effects of single-walled carbon nanotubes (SWNTs) on an estuarine meiobenthic copepod.

PubMed

Templeton, Ryan C; Ferguson, P Lee; Washburn, Kate M; Scrivens, Wally A; Chandler, G Thomas

2006-12-01

Single-walled carbon nanotubes (SWNT) are finding increasing use in consumer electronics and structural composites. These nanomaterials and their manufacturing byproducts may eventually reach estuarine systems through wastewater discharge. The acute and chronic toxicity of SWNTs were evaluated using full life-cycle bioassays with the estuarine copepod Amphiascus tenuiremis (ASTM method E-2317-04). A synchronous cohort of naupliar larvae was assayed by culturing individual larvae to adulthood in individual 96-well microplate wells amended with SWNTs in seawater. Copepods were exposed to "as prepared" (AP) SWNTs, electrophoretically purified SWNTs, or a fluorescent fraction of nanocarbon synthetic byproducts. Copepods ingesting purified SWNTs showed no significant effects on mortality, development, and reproduction across exposures (p < 0.05). In contrast, exposure to the more complex AP-SWNT mixture significantly increased life-cycle mortality, reduced fertilization rates, and reduced molting success in the highest exposure (10 mg x L(-1)) (p < 0.05). Exposure to small fluorescent nanocarbon byproducts caused significantly increased life-cycle mortality at 10 mg x L(-1) (p < 0.05). The fluorescent nanocarbon fraction also caused significant reduction in life-cycle molting success for all exposures (p < 0.05). These results suggest size-dependent toxicity of SWNT-based nanomaterials, with the smallest synthetic byproduct fractions causing increased mortality and delayed copepod development over the concentration ranges tested.

Carbon nanotubes-bridged molybdenum trioxide nanosheets as high performance anode for lithium ion batteries

NASA Astrophysics Data System (ADS)

Sun, Haiyan; Hanlon, Damien; Dinh, Duc Anh; Boland, John B.; Esau Del Rio Castillo, Antonio; Di Giovanni, Carlo; Ansaldo, Alberto; Pellegrini, Vittorio; Coleman, Jonathan N.; Bonaccorso, Francesco

2018-01-01

The search for novel nanomaterials driving the development of high-performance electrodes in lithium ion batteries (LIBs) is at the cutting edge of research in the field of energy storage. Here, we report on the synthesis of single wall carbon nanotube (SWNT)-bridged molybdenum trioxide (MoO3) nanosheets as anode material for LIBs. We exploit liquid phase exfoliation of layered MoO3 crystallites to produce multilayer MoO3 nanosheets dispersed in isopropanol, which are then mixed with solution processed SWNTs in the same solvent. The addition of SWNTs to the MoO3 nanosheets provides the conductive framework for electron transport, as well as a bridge structure, which buffers the volume expansion upon lithiation/de-lithiation. We demonstrate that the hybrid SWNT-bridged MoO3 structure is beneficial for both the mechanical stability and the electrochemical characteristics of the anodes leading to a specific capacity of 865 mAh g-1 at 100 mA g-1 after 100 cycles, with a columbic efficiency approaching 100% and a capacity fading of 0.02% per cycle. The low-cost, non-toxic, binder-free hybrid MoO3/SWNT here developed represents a step forward for the applicability of exfoliated MoO3 in LIB anodes, delivering high energy and power densities as well as long lifetime.

Determination of uptake, accumulation, and stress effects in corn (Zea mays L.) grown in single-wall carbon nanotube contaminated soil.

PubMed

Cano, Amanda M; Kohl, Kristina; Deleon, Sabrina; Payton, Paxton; Irin, Fahmida; Saed, Mohammad; Shah, Smit Alkesh; Green, Micah J; Cañas-Carrell, Jaclyn E

2016-06-01

Single-wall carbon nanotubes (SWNTs) are projected to increase in usage across many industries. Two studies were conducted using Zea L. (corn) seeds exposed to SWNT spiked soil for 40 d. In Study 1, corn was exposed to various SWNT concentrations (0, 10, and 100 mg/kg) with different functionalities (non-functionalized, OH-functionalized, or surfactant stabilized). A microwave induced heating method was used to determine SWNTs accumulated mostly in roots (0-24 μg/g), with minimal accumulation in stems and leaves (2-10 μg/g) with a limit of detection at 0.1 μg/g. Uptake was not functional group dependent. In Study 2, corn was exposed to 10 mg/kg SWNTs (non-functionalized or COOH-functionalized) under optimally grown or water deficit conditions. Plant physiological stress was determined by the measurement of photosynthetic rate throughout Study 2. No significant differences were seen between control and SWNT treatments. Considering the amount of SWNTs accumulated in corn roots, further studies are needed to address the potential for SWNTs to enter root crop species (i.e., carrots), which could present a significant pathway for human dietary exposure. Copyright © 2016 Elsevier Ltd. All rights reserved.

Enrichment Mechanism of Semiconducting Single-walled Carbon Nanotubes by Surfactant Amines

PubMed Central

Ju, Sang-Yong; Utz, Marcel; Papadimitrakopoulos, Fotios

2009-01-01

Utilization of single-walled carbon nanotubes (SWNTs) in high-end applications hinges on separating metallic (met-) from semiconducting (sem-) SWNTs. Surfactant amines, like octadecylamine (ODA) have proven instrumental for the selective extraction of sem-SWNTs from tetrahydrofuran (THF) nanotube suspensions. The chemical shift differences along the tail of an asymmetric, diacetylenic surfactant amine were used to probe the molecular dynamics in the presence and absence of nanotubes via NMR. The results suggest that the surfactant amine head is firmly immobilized onto the nanotube surface together with acidic water, while the aliphatic tail progressively gains larger mobility as it gets farther from the SWNT. X-ray and high-resolution TEM studies indicate that the sem-enriched sample is populated mainly by small nanotube bundles containing ca. three SWNTs. Molecular simulations in conjunction with previously determined HNO3/H2SO4 oxidation depths for met- and sem-SWNTs indicate that the strong pinning of the amine surfactants on the sem-enriched SWNTs bundles is a result of a well-ordered arrangement of nitrate/amine salts separated with a monomolecular layer of H2O. Such continuous 2D arrangement of nitrate/amine salts shields the local environment adjacent to sem-enriched SWNTs bundles and maintains an acidic pH that preserves nanotube oxidation (i.e. SWNTn+). This, in turn, results in strong interactions with charge-balancing NO3- counter ions that through their association with neutralized surfactant amines provide effective THF dispersion and consequent sem-enrichment. PMID:19397291

Electrical transport properties of small diameter single-walled carbon nanotubes aligned on ST-cut quartz substrates

PubMed Central

2014-01-01

A method is introduced to isolate and measure the electrical transport properties of individual single-walled carbon nanotubes (SWNTs) aligned on an ST-cut quartz, from room temperature down to 2 K. The diameter and chirality of the measured SWNTs are accurately defined from Raman spectroscopy and atomic force microscopy (AFM). A significant up-shift in the G-band of the resonance Raman spectra of the SWNTs is observed, which increases with increasing SWNTs diameter, and indicates a strong interaction with the quartz substrate. A semiconducting SWNT, with diameter 0.84 nm, shows Tomonaga-Luttinger liquid and Coulomb blockade behaviors at low temperatures. Another semiconducting SWNT, with a thinner diameter of 0.68 nm, exhibits a transition from the semiconducting state to an insulating state at low temperatures. These results elucidate some of the electrical properties of SWNTs in this unique configuration and help pave the way towards prospective device applications. PMID:25170326

Single-walled carbon nanotubes based chemiresistive genosensor for label-free detection of human rheumatic heart disease

NASA Astrophysics Data System (ADS)

Singh, Swati; Kumar, Ashok; Khare, Shashi; Mulchandani, Ashok; Rajesh

2014-11-01

A specific and ultrasensitive, label free single-walled carbon nanotubes (SWNTs) based chemiresistive genosensor was fabricated for the early detection of Streptococcus pyogenes infection in human causing rheumatic heart disease. The mga gene of S. pyogenes specific 24 mer ssDNA probe was covalently immobilized on SWNT through a molecular bilinker, 1-pyrenemethylamine, using carbodiimide coupling reaction. The sensor was characterized by the current-voltage (I-V) characteristic curve and scanning electron microscopy. The sensing performance of the sensor was studied with respect to changes in conductance in SWNT channel based on hybridization of the target S. pyogenes single stranded genomic DNA (ssG-DNA) to its complementary 24 mer ssDNA probe. The sensor shows negligible response to non-complementary Staphylococcus aureus ssG-DNA, confirming the specificity of the sensor only with S. pyogenes. The genosensor exhibited a linear response to S. pyogenes G-DNA from 1 to1000 ng ml-1 with a limit of detection of 0.16 ng ml-1.

Selective dispersion of high-purity semiconducting carbon nanotubes using indacenodithiophene-based conjugated polymer

NASA Astrophysics Data System (ADS)

Ji, Dongseob; Lee, Seung-Hoon; Noh, Yong-Young

2018-01-01

The facile sorting of highly pure semiconducting single-walled carbon nanotubes (s-SWNTs) is still one of the challenging issues for the next-generation wearable electronic devices such as various opto-electric devices and field-effect transistors (FETs). Herein, we demonstrate the selective dispersion of high-purity s-SWNTs using indacenodithiophene-co-benzothiadiazole (IDT-BT), which is a state-of-the-art high-mobility conjugated polymer. By the selective wrapping of the IDT-BT copolymer, SWNTs of chiral indices (6, 5), (7, 5), (7, 6), (8, 4), (9, 4), (8, 6), (8, 7), (10, 5), (9, 7), (10, 6), (11, 1), and (13, 3) are sorted. Finally, the networked s-SWNT film formed by spin-coating is applied as an active layer of FETs that exhibited ambipolar characteristics with an average mobility of 2.28 cm2/V s in the p-channel and 2.10 cm2/V s in the n-channel. The ON/OFF ratios in both p- and n-channels are approximately 105, which supports the high purity separation of s-SWNTs wrapped by IDT-BT.

Adsorption of small hydrocarbon radicals on single walled carbon nanotubes of finite length

NASA Astrophysics Data System (ADS)

Wu, Jianhua; Hagelberg, Frank

2010-04-01

Adsorption of the hydrocarbon radicals CH, CH2 , and CH3 on finite single walled carbon nanotubes (SWNTs) of the (10,0) type is investigated by density-functional theory (DFT). Two classes of finite SWNTs are considered: truncated SWNTs, where admission is made for geometric reconstruction of the tube ends, and those capped with fullerene hemispheres. Both prototypes are characterized by ground states with nonvanishing magnetic moments, where antiferromagnetic coordination between nds is preferred over the ferromagnetic alternative. The focus of this study is on the influence exerted by the adsorbates on the magnetic structure of the system as a whole, as well as the relative impact of both, confinement due to the finite lengths of the considered SWNTs and their magnetic structure on the preferred positions of hydrocarbon adsorbates. In particular, it is shown that the confinement outweighs the magnetic effect in defining the adsorption energy variations among nonequivalent sites of attachment. The SWNT spin-density distributions turn out to affect the nature of the bonding between finite SWNT substrates and hydrocarbon radical adsorbates.

Biomolecular Doping of Single-Walled Carbon Nanotubes by Thyroid Hormone

NASA Astrophysics Data System (ADS)

Rojas, Enrique; Paulson, Scott; Stern, Mike; Staii, Cristian; Dratman, Mary; Johnson, Alan

2004-03-01

Electron doping of semiconducting single-walled carbon nanotubes (SWNTs) by the thyroid hormone triiodothyronine (T3) is observed. T3 is applied locally, in solution, to SWNT field effect transistors (FETs) and binds along the length of the nanotube. T3 acts as an electron donor, shifting the I-V gate characteristics towards negative values of gate voltage. Shifts in the characteristics are measured as a function of the concentration of the solution. The effect is nearly reversible by rinsing the FETs with the solvent. Several days after application of T3, with no solvent rinsing, the gate characteristics are also nearly reversed. Experiments with a similar molecule for which the phenol ring is brominated as well as experiments with the de-iodinated molecule (T0) are performed to inform the effect of the iodine. The interaction of T3 with SWNTs may suggest a electronic interaction of T3 with other one-dimensional systems such as DNA.

Dispersion of single-wall carbon nanotubes with supramolecular Congo red - properties of the complexes and mechanism of the interaction.

PubMed

Jagusiak, Anna; Piekarska, Barbara; Pańczyk, Tomasz; Jemioła-Rzemińska, Małgorzata; Bielańska, Elżbieta; Stopa, Barbara; Zemanek, Grzegorz; Rybarska, Janina; Roterman, Irena; Konieczny, Leszek

2017-01-01

A method of dispersion of single-wall carbon nanotubes (SWNTs) in aqueous media using Congo red (CR) is proposed. Nanotubes covered with CR constitute the high capacity system that provides the possibility of binding and targeted delivery of different drugs, which can intercalate into the supramolecular, ribbon-like CR structure. The study revealed the presence of strong interactions between CR and the surface of SWNTs. The aim of the study was to explain the mechanism of this interaction. The interaction of CR and carbon nanotubes was studied using spectral analysis of the SWNT-CR complex, dynamic light scattering (DLS), differential scanning calorimetry (DSC) and microscopic methods: atomic force microscopy (AFM), transmission (TEM), scanning (SEM) and optical microscopy. The results indicate that the binding of supramolecular CR structures to the surface of the nanotubes is based on the "face to face stacking". CR molecules attached directly to the surface of the nanotubes can bind further, parallel-oriented molecules and form supramolecular and protruding structures. This explains the high CR binding capacity of carbon nanotubes. The presented system - containing SWNTs covered with CR - offers a wide range of biomedical applications.

In vitro and in vivo comparative study of the phototherapy anticancer activity of hyaluronic acid-modified single-walled carbon nanotubes, graphene oxide, and fullerene

NASA Astrophysics Data System (ADS)

Hou, Lin; Yuan, Yujie; Ren, Junxiao; Zhang, Yinling; Wang, Yongchao; Shan, Xiaoning; Liu, Qi; Zhang, Zhenzhong

2017-08-01

In this work, carbon nanomaterials, single-walled carbon nanotubes (SWNT), graphene oxide (GO), and fullerene (C60) were modified by hyaluronic acid (HA) to obtain water-soluble and biocompatible nanomaterials with high tumor-targeting capacity and then the comparative study of these hyaluronic acid-modified carbon nanomaterials was made in vitro and in vivo. The conjugates of hyaluronic acid and carbon nanomaterials, namely, HA-SWNT, HA-GO, HA-C60, were confirmed by UV/Vis spectrum, Fourier transform infrared spectroscopy (FTIR), and a transmission electron microscope (TEM). After HA modification, the sizes of HA-SWNT, HA-GO, and HA-C60 were in a range of 70 to 300 nm, and all the three HA-modified materials were at negative potential, demonstrating that HA modification was in favor of extravasation of carbon materials into a tumor site due to enhanced permeability and retention effect of tumor. Photothermal conversion in vitro test demonstrated excellent photothermal sensitivity of HA-SWNT and HA-GO. But the reactive oxygen yield of HA-C60 was the highest compared with the others under visible light irradiation, which proved the good photodynamic therapy effect of HA-C60. In addition, cytotoxicity experiments exhibited that the inhibitory efficacy of HA-SWNT was the lowest, the second was HA-C60, and the highest was HA-GO, which was consistent with the uptake degree of them. While under the laser irradiation, the cell inhibition of the HA-SWNT was the highest, the second was HA-GO, and the last was HA-C60. In vivo evaluation of the three targeting carbon nanomaterials was consistent with the cytotoxicity assay results. Taken together, the results demonstrated that HA-SWNT and HA-GO were suited for photothermal therapy (PTT) agents for their good photothermal property, while HA-C60 was used as a kind of photodynamic therapy (PDT) agent for its photodynamic effect.

Alcohol-induced drying of carbon nanotubes and its implications for alcohol/water separation: a molecular dynamics study.

PubMed

Tian, Xingling; Yang, Zaixing; Zhou, Bo; Xiu, Peng; Tu, Yusong

2013-05-28

Alcohols are important products in chemical industry, but separating them from their aqueous solutions is very difficult due to the hydrophilic nature of alcohols. Based on molecular dynamics simulations, we observe a striking nanoscale drying phenomenon and suggest an energy-saving and efficient approach toward alcohol∕water separation by using single-walled carbon nanotubes (SWNTs). We use various common linear alcohols including C1-C6 1-alcohols and glycerol for demonstration (the phenol is also used as comparison). Our simulations show that when SWNTs are immersed in aqueous alcohols solutions, although the alcohols concentration is low (1 M), all kinds of alcohols can induce dehydration (drying) of nanotubes and accumulate inside wide [(13, 13)] and narrow [(6, 6) or (7, 7)] SWNTs. In particular, most kinds of alcohols inside the narrow SWNTs form nearly uniform 1D molecular wires. Detailed energetic analyses reveal that the preferential adsorption of alcohols over water inside nanotubes is attributed to the stronger dispersion interactions of alcohols with SWNTs than water. Interestingly, we find that for the wide SWNT, the selectivity for 1-alcohols increases with the number of alcohol's carbon atoms (Ncarbon) and exhibits an exponential law with respect to Ncarbon for C1-C5 1-alcohols; for narrow SWNTs, the selectivity for 1-alcohols is very high for methanol, ethanol, and propanol, and reaches a maximum when Ncarbon = 3. The underlying physical mechanisms and the implications of these observations for alcohol∕water separation are discussed. Our findings provide the possibility for efficient dehydration of aqueous alcohols (and other hydrophilic organic molecules) by using SWNT bundles∕membranes.

Alcohol-induced drying of carbon nanotubes and its implications for alcohol/water separation: A molecular dynamics study

NASA Astrophysics Data System (ADS)

Tian, Xingling; Yang, Zaixing; Zhou, Bo; Xiu, Peng; Tu, Yusong

2013-05-01

Alcohols are important products in chemical industry, but separating them from their aqueous solutions is very difficult due to the hydrophilic nature of alcohols. Based on molecular dynamics simulations, we observe a striking nanoscale drying phenomenon and suggest an energy-saving and efficient approach toward alcohol/water separation by using single-walled carbon nanotubes (SWNTs). We use various common linear alcohols including C1-C6 1-alcohols and glycerol for demonstration (the phenol is also used as comparison). Our simulations show that when SWNTs are immersed in aqueous alcohols solutions, although the alcohols concentration is low (1 M), all kinds of alcohols can induce dehydration (drying) of nanotubes and accumulate inside wide [(13, 13)] and narrow [(6, 6) or (7, 7)] SWNTs. In particular, most kinds of alcohols inside the narrow SWNTs form nearly uniform 1D molecular wires. Detailed energetic analyses reveal that the preferential adsorption of alcohols over water inside nanotubes is attributed to the stronger dispersion interactions of alcohols with SWNTs than water. Interestingly, we find that for the wide SWNT, the selectivity for 1-alcohols increases with the number of alcohol's carbon atoms (Ncarbon) and exhibits an exponential law with respect to Ncarbon for C1-C5 1-alcohols; for narrow SWNTs, the selectivity for 1-alcohols is very high for methanol, ethanol, and propanol, and reaches a maximum when Ncarbon = 3. The underlying physical mechanisms and the implications of these observations for alcohol/water separation are discussed. Our findings provide the possibility for efficient dehydration of aqueous alcohols (and other hydrophilic organic molecules) by using SWNT bundles/membranes.

Carbon nanotube-DNA nanoarchitectures and electronic functionality.

PubMed

Wang, Xu; Liu, Fei; Andavan, G T Senthil; Jing, Xiaoye; Singh, Krishna; Yazdanpanah, Vahid R; Bruque, Nicolas; Pandey, Rajeev R; Lake, Roger; Ozkan, Mihrimah; Wang, Kang L; Ozkan, Cengiz S

2006-11-01

Biological molecules such as deoxyribonucleic acid (DNA) possess inherent recognition and self-assembly capabilities, and are attractive templates for constructing functional hierarchical material structures as building blocks for nanoelectronics. Here we report the assembly and electronic functionality of nanoarchitectures based on conjugates of single-walled carbon nanotubes (SWNTs) functionalized with carboxylic groups and single-stranded DNA (ssDNA) sequences possessing terminal amino groups on both ends, hybridized together through amide linkages by adopting a straightforward synthetic route. Morphological and chemical-functional characterization of the nanoarchitectures are investigated using scanning electron microscopy, transmission electron microscopy, atomic force microscopy, energy-dispersive X-ray spectroscopy, Raman spectroscopy, and Fourier-transform infrared spectroscopy. Electrical measurements (I-V characterization) of the nanoarchitectures demonstrate negative differential resistance in the presence of SWNT/ssDNA interfaces, which indicates a biomimetic route to fabricating resonant tunneling diodes. I-V characterization on platinum-metallized SWNT-ssDNA nanoarchitectures via salt reduction indicates modulation of their electrical properties, with effects ranging from those of a resonant tunneling diode to a resistor, depending on the amount of metallization. Electron transport through the nanoarchitectures has been analyzed by density functional theory calculations. Our studies illustrate the great promise of biomimetic assembly of functional nanosystems based on biotemplated materials and present new avenues toward exciting future opportunities in nanoelectronics and nanobiotechnology.

From Broadband to Electrochromic Notch Filters with Printed Monochiral Carbon Nanotubes

PubMed Central

2018-01-01

Dense layers of semiconducting single-walled carbon nanotubes (SWNTs) serve as electrochromic (EC) materials in the near-infrared with high optical density and high conductivity. EC cells with tunable notch filter properties instead of broadband absorption are created via highly selective dispersion of specific semiconducting SWNTs through polymer-wrapping followed by deposition of thick films by aerosol-jet printing. A simple planar geometry with spray-coated mixed SWNTs as the counter electrode renders transparent metal oxides redundant and facilitates complete bleaching within a few seconds through iongel electrolytes with high ionic conductivities. Monochiral (6,5) SWNT films as working electrodes exhibit a narrow absorption band at 997 nm (full width at half-maximum of 55–73 nm) with voltage-dependent optical densities between 0.2 and 4.5 and a modulation depth of up to 43 dB. These (6,5) SWNT notch filters can retain more than 95% of maximum bleaching for several hours under open-circuit conditions. In addition, different levels of transmission can be set by applying constant low voltage (1.5 V) pulses with modulated width or by a given number of fixed short pulses. PMID:29521086

Delivery of small interfering RNAs in human cervical cancer cells by polyethylenimine-functionalized carbon nanotubes

PubMed Central

2013-01-01

Carbon nanotubes are capable of penetrating the cell membrane and are widely considered as potential carriers for gene or drug delivery. Because the C-C and C=C bonds in carbon nanotubes are nonpolar, functionalization is required for carbon nanotubes to interact with genes or drugs as well as to improve their biocompatibility. In this study, polyethylenimine (PEI)-functionalized single-wall (PEI-NH-SWNTs) and multiwall carbon nanotubes (PEI-NH-MWNTs) were produced by direct amination method. PEI functionalization increased the positive charge on the surface of SWNTs and MWNTs, allowing carbon nanotubes to interact electrostatically with the negatively charged small interfering RNAs (siRNAs) and to serve as nonviral gene delivery reagents. PEI-NH-MWNTs and PEI-NH-SWNTs had a better solubility in water than pristine carbon nanotubes, and further removal of large aggregates by centrifugation produced a stable suspension of reduced particle size and improved homogeneity and dispersity. The amount of grafted PEI estimated by thermogravimetric analysis was 5.08% (w/w) and 5.28% (w/w) for PEI-NH-SWNTs and PEI-NH-MWNTs, respectively. For the assessment of cytotoxicity, various concentrations of PEI-NH-SWNTs and PEI-NH-MWNTs were incubated with human cervical cancer cells, HeLa-S3, for 48 h. PEI-NH-SWNTs and PEI-NH-MWNTs induced cell deaths in a dose-dependent manner but were less cytotoxic compared to pure PEI. As determined by electrophoretic mobility shift assay, siRNAs directed against glyceraldehyde-3-phosphate dehydrogenase (siGAPDH) were completely associated with PEI-NH-SWNTs or PEI-NH-MWNTs at a PEI-NH-SWNT/siGAPDH or PEI-NH-MWNT/siGAPDH mass ratio of 80:1 or 160:1, respectively. Furthermore, PEI-NH-SWNTs and PEI-NH-MWNTs successfully delivered siGAPDH into HeLa-S3 cells at PEI-NH-SWNT/siGAPDH and PEI-NH-MWNT/siGAPDH mass ratios of 1:1 to 20:1, resulting in suppression of the mRNA level of GAPDH to an extent similar to that of DharmaFECT, a common transfection

Interlayer shear behaviors of graphene-carbon nanotube network

NASA Astrophysics Data System (ADS)

Qin, Huasong; Liu, Yilun

2017-09-01

The interlayer shear resistance plays an important role in graphene related applications, and different mechanisms have been proposed to enhance its interlayer load capacity. In this work, we performed molecular dynamics (MD) simulations and theoretical analysis to study interlayer shear behaviors of three dimensional graphene-carbon (3D-GC) nanotube networks. The shear mechanical properties of carbon nanotubes (CNTs) crosslink with different diameters are obtained which is one order of magnitude larger than that of other types of crosslinks. Under shear loading, 3D-GC exhibits two failure modes, i.e., fracture of graphene sheet and failure of CNT crosslink, determined by the diameter of CNT crosslink, crosslink density, and length of 3D-GC. A modified tension-shear chain model is proposed to predict the shear mechanical properties and failure mode of 3D-GC, which agrees well with MD simulation results. The results presented in this work may provide useful insights for future development of high-performance 3D-GC materials.

Visible-Blind UV Photodetector Based on Single-Walled Carbon Nanotube Thin Film/ZnO Vertical Heterostructures.

PubMed

Li, Guanghui; Suja, Mohammad; Chen, Mingguang; Bekyarova, Elena; Haddon, Robert C; Liu, Jianlin; Itkis, Mikhail E

2017-10-25

Ultraviolet (UV) photodetectors based on heterojunctions of conventional (Ge, Si, and GaAs) and wide bandgap semiconductors have been recently demonstrated, but achieving high UV sensitivity and visible-blind photodetection still remains a challenge. Here, we utilized a semitransparent film of p-type semiconducting single-walled carbon nanotubes (SC-SWNTs) with an energy gap of 0.68 ± 0.07 eV in combination with a molecular beam epitaxy grown n-ZnO layer to build a vertical p-SC-SWNT/n-ZnO heterojunction-based UV photodetector. The resulting device shows a current rectification ratio of 10 3 , a current photoresponsivity up to 400 A/W in the UV spectral range from 370 to 230 nm, and a low dark current. The detector is practically visible-blind with the UV-to-visible photoresponsivity ratio of 10 5 due to extremely short photocarrier lifetimes in the one-dimensional SWNTs because of strong electron-phonon interactions leading to exciton formation. In this vertical configuration, UV radiation penetrates the top semitransparent SC-SWNT layer with low losses (10-20%) and excites photocarriers within the n-ZnO layer in close proximity to the p-SC-SWNT/n-ZnO interface, where electron-hole pairs are efficiently separated by a high built-in electric field associated with the heterojunction.

Three Dimensionally Interlinked, Dense, Solid Form of Single-Walled CNT Ropes

NASA Technical Reports Server (NTRS)

Smalley, Richard E.

2012-01-01

A 3D networked, dense form of single-walled carbon nanotubes (SWNT) has been made through isotropic shrinking of a gel-like SWNT-water paste by very slow evaporation. Approximately 35 g of Raw HiPco nanotubes were cleaned by the method of soft baking (250 C for 15 hours in air saturated with water vapor) in a glass beaker followed by leaching with concentrated hydrochloric acid. Typically, one liter of concentrated hydrochloric acid was added to the soft-baked voluminous mass in the same large beaker, and allowed to digest at room temperature with stirring overnight. The acid-digested SWNT slurry was filtered through a large porcelain Buchner funnel under atmospheric pressure. The slurry was continuously flushed, while still in the funnel, with a very slow but steady stream of deionized water employing a peristaltic pump. This process, referred to as gwashing, h continued until the filtrate water dripping from the Buchner funnel was clear, colorless, and neutral to a pH paper. This took about 15 liters of water to flow through the slurry over a day. At this point, the water pump was stopped and the SWNT-water slurry was allowed to drain the excess water for about 10 hours. The resulting thick paste of SWNT-neutral water was transferred to a beaker. The beaker was covered with aluminum foil with few holes and allowed to dry very slowly in a hood at room temperature. In about eight weeks, the sample gradually dried isotropically to a cylindrical dense mass referred to as a carbon nanotube block (CNB). There was no carbonaceous matter sticking to any of the glass surface where the SWNT-water paste made contact. The approximate dimensions of the cylindrical SWNT block that weighed 28 g were 1.5 in. (.3.8 cm) in diameter and 1.25 in. (.3.2 cm) in height. The bottom portion of the cylinder that was in contact with the beaker surface was slightly wider, indicating some resistance to shrinking. The cylindrical mass also consisted of several pores. The cylindrical mass was

Nonlinear motion of cantilevered SWNT and Its Meaning to Phonon Dynamics

NASA Astrophysics Data System (ADS)

Koh, Heeyuen; Cannon, James; Chiashi, Shohei; Shiomi, Junichiro; Maruyama, Shigeo

2013-03-01

Based on the finding that the lowest frequency mode of cantilevered SWNT is described by the continuum beam theory in frequency domain, we considered its effect of the symmetric structure for the coupling of orthogonal transverse modes to explain the nonlinear motion of free thermal vibration. This nonlinear motion calculated by our molecular dynamics simulation, once regarded as noise, is observed to have the periodic order with duffing and beating, which is dependent on aspect ratio and temperature. It could be dictated by the governing equation from the Green Lagrangian strain tensor. The nonlinear beam equation from strain tensor described the motion well for various models which has different aspect ratio in molecular dynamics simulation. Since this motion is nothing but the interaction between 2nd mode of radial, tangential mode and 1st longitudinal mode, it was found that Green Lagrangian strain tensor is capable to deal such coupling. The free thermal motion of suspended SWNT is also considered without temperature gradient. The Q factor measured by this theoretical analysis will be discussed. Part of this work was financially supported by Grant-in-Aid for Scientific Research (19054003 and 22226006), and Global COE Program 'Global Center for Excellence for Mechanical Systems Innovation'

Interaction of a Ni(II) tetraazaannulene complex with elongated fullerenes as simple models for carbon nanotubes.

PubMed

Henao-Holguín, Laura Verónica; Basiuk, Vladimir A

2015-06-01

Nickel(II) complex of 5,14-dihydro-6,8,15,17-tetramethyldibenzo[b,i][1,4,8,11] tetraazacyclotetradecine (NiTMTAA), which can be employed for noncovalent functionalization of carbon nanotubes (CNTs), represents a more complex and interesting case in terms of structure of the resulting nanohybrids, as compared to the related materials functionalized with porphyrins and phthalocyanines. Due to its saddle shape, the NiTMTAA molecule adsorbed can adopt different, energetically non-equivalent orientations with respect to CNT, depending on whether CH3 or C6H4 groups contact the latter. The main goal of the present work was to provide information on the interactions of NiTMTAA with simple single-walled CNT (SWNT) models accessible for dispersion-corrected DFT calculations. For reasons of comparison, we employed three such functionals: M06-2X and LC-BLYP as implemented in Gaussian 09 package, and PBE-G as implemented in Materials Studio 6.0. In order to roughly estimate the effect of nanotube chirality on the interaction strenght, we considered two short closed-end SWNT models (also referred to as 'elongated fullerenes'), one armchair and one zigzag, derived from C60 and C80 hemispheres. In addition, we calculated similar complexes with C60, as well as I h and D 5h isomers of C80. The results were analyzed in terms of optimized geometries, formation energies, HOMO-LUMO gap energies, and intermolecular separations. Graphical Abstract Interaction of Ni(II) tetraazaannulene complex with elongated fullerenes.

Synthesis of carbon nanotube (CNT)-entangled CuO nanotube networks via CNT-catalytic growth and in situ thermal oxidation as additive-free anodes for lithium ion batteries

NASA Astrophysics Data System (ADS)

Cui, Xia; Song, Bo; Cheng, Shisu; Xie, Yun; Shao, Yijiang; Sun, Yueming

2018-01-01

We demonstrated the utility of carbon nanotubes (CNTs) as a catalyst and conductive agent to synthesize CNT-entangled copper nanowire (CuNW-CNT) networks within a melted mixture of hexadecylamine and cetyltrimethy ammounium bromide. The CuNW-CNT networks were further in situ thermally oxidized into CuO nanotube-CNT (CuONT-CNT) with the high retention of network structure. The binder- and conducting-additive-free anodes constructed using the CuONT-CNT networks exhibited high performance, such as high capability (557.7 mAh g-1 at 0.2 °C after 200 cycles), high Coulombic efficiency (near 100%), good rate performance (385.5 mAh g-1 at 5 °C and 310.3 mAh g-1 at 10 °C), and long cycling life.

ENVIRONMENTAL BIODEGRADABILITY OF [14C] SINGLE-WALLED CARBON NANOTUBESBY TRAMETES VERSICOLOR AND NATURAL MICROBIAL CULTURES FOUND IN NEWBEDFORD HARBOR SEDIMENT AND AERATED WASTEWATER TREATMENT PLANT SLUDGE

EPA Science Inventory

Little is known about environmental biodegradability or biotransformations of single-walled carbon nanotubes (SWNT). Because of their strong association with aquatic organic matter, detailed knowledge of the ultimate fate and persistence of SWNT requires investigation of possible...

Effect of localized surface-plasmon mode on exciton transport and radiation emission in carbon nanotubes.

PubMed

Roslyak, Oleksiy; Cherqui, Charles; Dunlap, David H; Piryatinski, Andrei

2014-07-17

We report on a general theoretical approach to study exciton transport and emission in a single-walled carbon nanotube (SWNT) in the presence of a localized surface-plasmon (SP) mode within a metal nanoparticle interacting via near-field coupling. We derive a set of quantum mechanical equations of motion and approximate rate equations that account for the exciton, SP, and the environmental degrees of freedom. The material equations are complemented by an expression for the radiated power that depends on the exciton and SP populations and coherences, allowing for an examination of the angular distribution of the emitted radiation that would be measured in experiment. Numerical simulations for a (6,5) SWNT and cone-shaped Ag metal tip (MT) have been performed using this methodology. Comparison with physical parameters shows that the near-field interaction between the exciton-SP occurs in a weak coupling regime, with the diffusion processes being much faster than the exciton-SP population exchange. In such a case, the effect of the exciton population transfer to the MT with its subsequent dissipation (i.e., the Förster energy transfer) is to modify the exciton steady state distribution while reducing the equilibration time for excitons to reach a steady sate distribution. We find that the radiation distribution is dominated by SP emission for a SWNT-MT separation of a few tens of nanometers due to the fast SP emission rate, whereas the exciton-SP coherences can cause its rotation.

Extremely Efficient Multiple Electron-hole Pair Generation in Carbon Nanotube Photodiodes

NASA Astrophysics Data System (ADS)

Gabor, Nathaniel

2010-03-01

The efficient generation of multiple electron-hole (e-h) pairs from a single photon could improve the efficiency of photovoltaic solar cells beyond standard thermodynamic limits [1] and has been the focus of much recent work in semiconductor nanomaterials [2,3]. In single walled carbon nanotubes (SWNTs), the small Fermi velocity and low dielectric constant suggests that electron-electron interactions are very strong and that high-energy carriers should efficiently generate e-h pairs. Here, I will discuss observations of highly efficient generation of e-h pairs due to impact excitation in SWNT p-n junction photodiodes [4]. To investigate optoelectronic transport properties of individual SWNT photodiodes, we focus a laser beam over the device while monitoring the electronic characteristics. Optical excitation into the second electronic subband E22 ˜ 2 EGAP leads to striking photocurrent steps in the device I-VSD characteristics that occur at voltage intervals of the band gap energy EGAP/ e. Spatially and spectrally resolved photocurrent combined with temperature-dependent studies suggest that these steps result from efficient generation of multiple e-h pairs from a single hot E22 carrier. We conclude that in the SWNT photodiode, a single photon with energy greater than 2EGAP is converted into multiple e-h pairs, leading to enhanced photocurrent and increased photo-conversion efficiency. [1] W. Shockley, and H. J. Queisser, Journal of Applied Physics 32, 510 (1961). [2] R. D. Schaller, and V. I. Klimov, Physical Review Letters 92 (18), 186601 (2004). [3] R. J. Ellingson, et al, Nano Letters, 5 (5), 865-871 (2005). [4] Nathaniel M. Gabor, Zhaohui Zhong, Ken Bosnick, Jiwoong Park, and Paul McEuen, Science, 325, 1367 (2009).

Photovoltaic devices based on high density boron-doped single-walled carbon nanotube/n-Si heterojunctions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saini, Viney; Li, Zhongrui; Bourdo, Shawn

2011-01-13

A simple and easily processible photovoltaic device has been developed based on borondoped single-walled carbon nanotubes (B-SWNTs) and n-type silicon (n-Si) heterojunctions. The single-walled carbon nanotubes (SWNTs) were substitutionally doped with boron atoms by thermal annealing, in the presence of B 2O 3. The samples used for these studies were characterized by Raman spectroscopy, thermal gravimetric analysis (TGA), transmission electron microscopy (TEM), and x-ray photoelectron spectroscopy (XPS). The fully functional solar cell devices were fabricated by airbrush deposition that generated uniform B-SWNT films on top of the n-Si substrates. The carbon nanotube films acted as exciton-generation sites, charge collection andmore » transportation, while the heterojunctions formed between B-SWNTs and n-Si acted as charge dissociation centers. The current-voltage characteristics in the absence of light and under illumination, as well as optical transmittance spectrum are reported here. It should be noted that the device fabrication process can be made amenable to scalability by depositing direct and uniform films using airbrushing, inkjet printing, or spin-coating techniques.« less

Coulomb explosion: a novel approach to separate single-walled carbon nanotubes from their bundle.

PubMed

Liu, Guangtong; Zhao, Yuanchun; Zheng, Kaihong; Liu, Zheng; Ma, Wenjun; Ren, Yan; Xie, Sishen; Sun, Lianfeng

2009-01-01

A novel approach based on Coulomb explosion has been developed to separate single-walled carbon nanotubes (SWNTs) from their bundle. With this technique, we can readily separate a bundle of SWNTs into smaller bundles with uniform diameter as well as some individual SWNTs. The separated SWNTs have a typical length of several microns and form a nanotree at one end of the original bundle. More importantly, this separating procedure involves no surfactant and includes only one-step physical process. The separation method offers great conveniences for the subsequent individual SWNT or multiterminal SWNTs device fabrication and their physical properties studies.

On-Chip Chemical Self-Assembly of Semiconducting Single-Walled Carbon Nanotubes (SWNTs): Toward Robust and Scale Invariant SWNTs Transistors.

PubMed

Derenskyi, Vladimir; Gomulya, Widianta; Talsma, Wytse; Salazar-Rios, Jorge Mario; Fritsch, Martin; Nirmalraj, Peter; Riel, Heike; Allard, Sybille; Scherf, Ullrich; Loi, Maria A

2017-06-01

In this paper, the fabrication of carbon nanotubes field effect transistors by chemical self-assembly of semiconducting single walled carbon nanotubes (s-SWNTs) on prepatterned substrates is demonstrated. Polyfluorenes derivatives have been demonstrated to be effective in selecting s-SWNTs from raw mixtures. In this work the authors functionalized the polymer with side chains containing thiols, to obtain chemical self-assembly of the selected s-SWNTs on substrates with prepatterned gold electrodes. The authors show that the full side functionalization of the conjugated polymer with thiol groups partially disrupts the s-SWNTs selection, with the presence of metallic tubes in the dispersion. However, the authors determine that the selectivity can be recovered either by tuning the number of thiol groups in the polymer, or by modulating the polymer/SWNTs proportions. As demonstrated by optical and electrical measurements, the polymer containing 2.5% of thiol groups gives the best s-SWNT purity. Field-effect transistors with various channel lengths, using networks of SWNTs and individual tubes, are fabricated by direct chemical self-assembly of the SWNTs/thiolated-polyfluorenes on substrates with lithographically defined electrodes. The network devices show superior performance (mobility up to 24 cm 2 V -1 s -1 ), while SWNTs devices based on individual tubes show an unprecedented (100%) yield for working devices. Importantly, the SWNTs assembled by mean of the thiol groups are stably anchored to the substrate and are resistant to external perturbation as sonication in organic solvents. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Pore structure of raw and purified HiPco single-walled carbon nanotubes

NASA Astrophysics Data System (ADS)

Cinke, Martin; Li, Jing; Chen, Bin; Cassell, Alan; Delzeit, Lance; Han, Jie; Meyyappan, M.

2002-10-01

Very high purity single-walled carbon nanotubes (SWNTs) were obtained from HiPco SWNT samples containing Fe particles by a two-step purification process. The raw and purified samples were characterized using high resolution transmission electron microscopy (HRTEM), Raman spectroscopy and thermogravimetric analysis (TGA). The purified sample consists of ˜0.4% Fe and the process does not seem to introduce any additional defects. The N 2 adsorption isotherm studies at 77 K reveal that the total surface area of the purified sample increases to 1587 m 2/g from 567 m 2/g for the raw material, which is the highest value reported for SWNTs.

Single-walled carbon nanotubes based chemiresistive genosensor for label-free detection of human rheumatic heart disease

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, Swati; Kumar, Ashok, E-mail: rajesh-csir@yahoo.com, E-mail: ashokigib@rediffmail.com; Academy of Scientific and Innovative Research

A specific and ultrasensitive, label free single-walled carbon nanotubes (SWNTs) based chemiresistive genosensor was fabricated for the early detection of Streptococcus pyogenes infection in human causing rheumatic heart disease. The mga gene of S. pyogenes specific 24 mer ssDNA probe was covalently immobilized on SWNT through a molecular bilinker, 1-pyrenemethylamine, using carbodiimide coupling reaction. The sensor was characterized by the current-voltage (I-V) characteristic curve and scanning electron microscopy. The sensing performance of the sensor was studied with respect to changes in conductance in SWNT channel based on hybridization of the target S. pyogenes single stranded genomic DNA (ssG-DNA) to itsmore » complementary 24 mer ssDNA probe. The sensor shows negligible response to non-complementary Staphylococcus aureus ssG-DNA, confirming the specificity of the sensor only with S. pyogenes. The genosensor exhibited a linear response to S. pyogenes G-DNA from 1 to1000 ng ml{sup −1} with a limit of detection of 0.16 ng ml{sup −1}.« less

Optical Spectroscopy and Photophysics of Single Wall Carbon Nanotubes

NASA Astrophysics Data System (ADS)

Brus, Louis

2006-03-01

We explore the fundamental nature and dynamics of excited electronic states in SWNT. Psec luminescence and photobleaching dynamics of SWNTs in micellar solution show that non-radiative Auger recombination is extremely fast. At low pH, nanotube surface endoperoxides protonate and introduce holes that quench the luminescence. At higher concentration these holes also bleach the band gap optical absorption. Near infrared two photon luminescence excitation spectra quantitatively reveal the importance of excitons. In order to characterize excited states in both metallic and semiconducting SWNTs at the single-tube level, we detect white-light Rayleigh scattering from individual tubes suspended over an open slit in a substrate. Diagnostic spectra with high signal to noise are obtained in just a few minutes.

Electron-phonon effects in graphene and an armchair (10,10) single-wall carbon nanotube

NASA Astrophysics Data System (ADS)

Woods, Lilia Milcheva Rapatinska

New effects due to the electron-phonon interaction in some low-dimensional tight-binding systems are discussed. A sheet of graphite (two-dimensional) and an armchair single wall carbon nanotube (SWNT) (quasi-one dimensional) are taken as examples. The geometrical structure and the linear dispersion of the energy with respect to the electron wave vector are expected to play a significant role. For the ordinary electron-phonon coupling which includes modulated hopping and linear electron-phonon interaction the matrix elements for both systems are derived in the context of a two parameter model for the phonon vibrational spectrum. It is found that they (for both structures) strongly depend on the geometry, display a deformation type of potential and are reduced by a factor of (1 - R), where R depends uniquely on the introduced phonon parameters. Next a new type of interaction is derived; it arises from the phonon modulation of the electron-electron interaction. After writing the matrix elements for the new Hamiltonian, the problem is considered in the context of many body physics. There are two contributions. One of them is the random phase approximation with one phonon line. The electron self-energy for it is calculated. It is shown that one might expect that this is not a large effect. Analytical expressions are obtained for the armchair single wall carbon nanotube. The exchange interaction in the one-phonon approximation is another term that arises and is also considered. One is able to write four new Feynman diagrams and derive an expression for -ImSk⃗ . The contribution from this type of coupling could be large and comparable to the one from the modulated hopping. These results are supported by numerical estimates of some characteristics of graphene and SWNT. The values of the electron-phonon coupling constant, lambda, and the electron lifetime, tau, are compared between the traditional electron-phonon interaction and the phonon modulated electron

Impact of helium pressure in arc plasma synthesis on crystallinity of single-walled carbon nanotubes

NASA Astrophysics Data System (ADS)

Ando, Atsushi; Takeda, Keigo; Ohta, Takayuki; Ito, Masafumi; Hiramatsu, Mineo; Ishikawa, Kenji; Kondo, Hiroki; Sekine, Makoto; Suzuki, Tomoko; Inoue, Sakae; Ando, Yoshinori; Hori, Masaru

2018-06-01

Single-walled carbon nanotubes (SWNTs) were synthesized with a high growth rate by an arc plasma method employing the electrodes made from a Ni–Y mixture catalyst. In a previous study, it was reported that the monitoring of high-crystallinity SWNT growth enabled the evaluation of the results of the optical emission spectroscopy (OES) of C2, Ni, and Y. Here, the impact of helium pressure of arc plasma on the high crystallinity of SWNTs was determined by considering the high intensity ratios of catalytic metals over C2 emissions at low helium pressures in the arc plasma.

Low mass MEMS/NEMS switch for a substitute of CMOS transistor using single-walled carbon nanotube thin film

NASA Astrophysics Data System (ADS)

Jang, Min-Woo

Power dissipation is a key factor for mobile devices and other low power applications. Complementary metal oxide semiconductor (CMOS) is the dominant integrated circuit (IC) technology responsible for a large part of this power dissipation. As the minimum feature size of CMOS devices enters into the sub 50 nanometer (nm) regime, power dissipation becomes much worse due to intrinsic physical limits. Many approaches have been studied to reduce power dissipation of deeply scaled CMOS ICs. One possible candidate is the electrostatic electromechanical switch, which could be fabricated with conventional CMOS processing techniques. They have critical advantages compared to CMOS devices such as almost zero standby leakage in the off-state due to the absence of a pn junction and a gate oxide, as well as excellent drive current in the on-state due to a metallic channel. Despite their excellent standby power dissipation, the electrostatic MEMS/NEMS switches have not been considered as a viable replacement for CMOS devices due to their large mechanical delay. Moreover, previous literature reveals that their pull-in voltage and switching speed are strongly proportional to each other. This reduces their potential advantage. However, in this work, we theoretically and experimentally demonstrated that the use of single-walled carbon nanotube (SWNT) with very low mass density and strong mechanical properties could provide a route to move off of the conventional trend with respect to the pull-in voltage / switching speed tradeoff observed in the literature. We fabricated 2-terminal fixed- beam switches with aligned composite SWNT thin films. In this work, layer-by-layer (LbL) self-assembly and dielectrophoresis were selected for aligned-composite SWNT thin film deposition. The dense membranes were successfully patterned to form submicron beams by e-beam lithography and oxygen plasma etching. Fixed-fixed beam switches using these membranes successfully operated with approximately 600

Chemical Vapor Detection using Single-walled Carbon Nanotubes

DTIC Science & Technology

2006-05-01

1 / f noise , and achieving chemical specificity. Recently, researchers have developed approaches to...nanoscale materials, exhibit a large component of 1 / f noise .11 Such 1 / f noise is a particular concern for chemical detection, because the sensors operate at...low frequencies. We discuss how SWNT networks can be designed to reduce the level of 1 / f noise to acceptable levels.12 Lastly, we discuss the issue

Tunable Encapsulation Structure of Block Copolymer Coated Single-Walled Carbon Nanotubes in Aqueous Solution

DOE PAGES

Han, Youngkyu; Ahn, Suk-Kyun; Zhang, Zhe; ...

2015-05-15

The nano-sized and shape-tunable molecular building blocks can provide great opportunities for the fabrication of precisely controlled nanostructures. In this work, we have fabricated a molecular building block of single-walled carbon nanotubes (SWNTs) coated by PPO-PEO-PPO block copolymers whose encapsulation structure can be controlled via temperature or addition of small molecules. The structure and optical properties of SWNT-block copolymers have been investigated by small angle neutron scattering (SANS), ultraviolet-visible (UV-vis) spectroscopy, atomic force microscopy (AFM), and molecular dynamics (MD) simulation. The structure of the hydrated block copolymer layer surrounding SWNT can be controlled reversibly by varying temperature as well asmore » by irreversibly adding 5-methylsalicylic acid (5MS). Increasing hydrophobicity of the polymers with temperature and strong tendency of 5MS to interact with both block copolymers and orbitals of the SWNTs are likely to be responsible for the significant structural change of the block copolymer encapsulation layer, from loose corona shell to tightly encapsulating compact shell. These result shows an efficient and simple way to fabricate and manipulate carbon-based nano building blocks in aqueous systems with tunable structure.« less

Density functional study of the 13C NMR chemical shifts in small-to-medium-diameter infinite single-walled carbon nanotubes.

PubMed

Zurek, Eva; Pickard, Chris J; Walczak, Brian; Autschbach, Jochen

2006-11-02

NMR chemical shifts were calculated for semiconducting (n,0) single-walled carbon nanotubes (SWNTs) with n ranging from 7 to 17. Infinite isolated SWNTs were calculated using a gauge-including projector-augmented plane-wave (GIPAW) approach with periodic boundary conditions and density functional theory (DFT). In order to minimize intertube interactions in the GIPAW computations, an intertube distance of 8 A was chosen. For the infinite tubes, we found a chemical shift range of over 20 ppm for the systems considered here. The SWNT family with lambda = mod(n, 3) = 0 has much smaller chemical shifts compared to the other two families with lambda = 1 and lambda = 2. For all three families, the chemical shifts decrease roughly inversely proportional to the tube's diameter. The results were compared to calculations of finite capped SWNT fragments using a gauge-including atomic orbital (GIAO) basis. Direct comparison of the two types of calculations could be made if benzene was used as the internal (computational) reference. The NMR chemical shifts of finite SWNTs were found to converge very slowly, if at all, to the infinite limit, indicating that capping has a strong effect (at least for the (9,0) tubes) on the calculated properties. Our results suggest that (13)C NMR has the potential for becoming a useful tool in characterizing SWNT samples.

Elastomer Reinforced with Carbon Nanotubes

NASA Technical Reports Server (NTRS)

Hudson, Jared L.; Krishnamoorti, Ramanan

2009-01-01

Elastomers are reinforced with functionalized, single-walled carbon nanotubes (SWNTs) giving them high-breaking strain levels and low densities. Cross-linked elastomers are prepared using amine-terminated, poly(dimethylsiloxane) (PDMS), with an average molecular weight of 5,000 daltons, and a functionalized SWNT. Cross-link densities, estimated on the basis of swelling data in toluene (a dispersing solvent) indicated that the polymer underwent cross-linking at the ends of the chains. This thermally initiated cross-linking was found to occur only in the presence of the aryl alcohol functionalized SWNTs. The cross-link could have been via a hydrogen-bonding mechanism between the amine and the free hydroxyl group, or via attack of the amine on the ester linage to form an amide. Tensile properties examined at room temperature indicate a three-fold increase in the tensile modulus of the elastomer, with rupture and failure of the elastomer occurring at a strain of 6.5.

Chemistry of carbon nanomaterials: Uses of lithium nanotube salts in organic syntheses and functionalization of graphite

NASA Astrophysics Data System (ADS)

Chattopadhyay, Jayanta

The effective utilization of carbon nanomaterials, such as single-walled carbon nanotubes (SWNTs) and graphite, has been hindered due to difficulties (poor solubility, poly-dispersity) in processing. Therefore, a high degree of sidewall functionalization, either covalent or non-covalent, is often required to overcome these difficulties as the functionalized nanomaterials exhibit better solubility (either in organic solvents or in water), dispersity, manipulation, and processibility. This thesis presents a series of convenient and efficient organic synthetic routes to functionalize carbon nanomaterials. Carbon nanotube salts, prepared by treating SWNTs with lithium in liquid ammonia, react readily with aryl halides to yield aryl-functionalized SWNTs. These arylated SWNTs are soluble in methanol and water upon treatment with oleum. Similarly, SWNTs can be covalently functionalized by different heteroatoms (nitrogen, oxygen, and sulfur). Using the reductive alkylation approach, a synthetic scheme is designed to prepare long chain carboxylic acid functionalized SWNTs [SWNTs-(RCOOH)] that can react with (1) amine-terminated polyethylene glycol (PEG) chains to yield water-soluble biocompatible PEGylated SWNTs that are likely to be useful in a variety of biomedical applications; (2) polyethyleneimine (PEI) to prepare a SWNTs-PEI based adsorbent material that shows a four-fold improvement in the adsorption capacity of carbon dioxide over commonly used materials, making it useful for regenerable carbon dioxide removal in spaceflight; (3) chemically modified SWNTs-(RCOOH) to permit covalent bonding to the nylon matrix, thus allowing the formation of nylon 6,10 and nylon 6,10/SWNTs-(RCOOH) nanocomposites. Furthermore, we find that the lithium salts of carbon nanotubes serve as a source of electrons to induce polymerization of simple alkenes and alkynes onto the surface of carbon nanotubes. In the presence of sulfide/disulfide bonds, SWNT salts can initiate the single electron

Single-wall carbon nanotubes and graphene oxide-based saturable absorbers for low phase noise mode-locked fiber lasers

PubMed Central

Li, Xiaohui; Wu, Kan; Sun, Zhipei; Meng, Bo; Wang, Yonggang; Wang, Yishan; Yu, Xuechao; Yu, Xia; Zhang, Ying; Shum, Perry Ping; Wang, Qi Jie

2016-01-01

Low phase noise mode-locked fiber laser finds important applications in telecommunication, ultrafast sciences, material science, and biology, etc. In this paper, two types of carbon nano-materials, i.e. single-wall carbon nanotube (SWNT) and graphene oxide (GO), are investigated as efficient saturable absorbers (SAs) to achieve low phase noise mode-locked fiber lasers. Various properties of these wall-paper SAs, such as saturable intensity, optical absorption and degree of purity, are found to be key factors determining the performance of the ultrafast pulses. Reduced-noise femtosecond fiber lasers based on such carbon-based SAs are experimentally demonstrated, for which the phase noise has been reduced by more than 10 dB for SWNT SAs and 8 dB for GO SAs at 10 kHz. To the best of our knowledge, this is the first investigation on the relationship between different carbon material based SAs and the phase noise of mode-locked lasers. This work paves the way to generate high-quality low phase noise ultrashort pulses in passively mode-locked fiber lasers. PMID:27126900

The role of the substrate surface morphology and water in growth of vertically aligned single-walled carbon nanotubes.

PubMed

Pint, Cary; Pheasant, Sean; Nicholas, Nolan; Horton, Charles; Hauge, Robert

2008-11-01

Growth of high quality, vertically aligned single-walled carbon nanotubes (carpets) is achieved using a rapid insertion hot filament chemical vapor deposition (HF-CVD) technique. The effect of the substrate morphology on growth is explored by comparing carpets grown on epitaxially polished MgO substrates to those grown on "as-cut", macroscopically rough MgO substrates. Depending on the substrate morphology, we observe differences in both the overall carpet morphology as well as the diameter distribution of nanotubes grown in the carpet based on optical measurements. In addition, we explore the role of water in the growth of carpets on MgO and the conventional Al2O3 coated Si substrates. We find that the addition of a small amount of water is beneficial to the growth rates of the SWNT carpets, enhancing the growth rates by up to eight times.

Structural and compositional changes in single wall carbon nanotube ensemble upon exposure to microwave plasma

NASA Astrophysics Data System (ADS)

Roy, Soumyendu; Bajpai, Reeti; Soin, Navneet; Sinha Roy, Susanta; McLaughlin, James A.; Misra, D. S.

2017-10-01

Microwave plasma treatment of single wall carbon nanotube (SWNT) films called bucky papers (BPs) resulted in changes in the relative proportion of different chiralities of SWNTs present in the BP and the production of vertical microstructures on the surface of BP. The plasma was created using H2 gas mixed with Ar or CH4, at a temperature of 900 °C and a pressure of 70 Torr. Radial breathing mode spectra of the BPs revealed that the preferential sputtering by plasma is not with respect to the diameter or the metallic nature of SWNTs. We propose that the lengths of SWNTs influence how they interact with plasma. Longer tubes will have higher dielectric constants and hence will be polarized more strongly by the electric field of the plasma sheath. This in turn results in greater ion bombardment and sputtering. Finite element method was used to find the strengths of the induced electric fields on model SWNT surfaces. Microscopy, Raman, and X-ray photoelectron spectroscopy were used to study the effect of plasma on the crystallinity of the surviving SWNTs. Structural integrity of SWNTs was preserved after the plasma treatment.

Understanding and controlling the rest potential of carbon nanotube-based supercapacitors for energy density enhancement

NASA Astrophysics Data System (ADS)

Yoo, Young-Eun; Park, Jinwoo; Kim, Woong

2018-03-01

We present a novel method for enhancing the energy density of an electrical double layer capacitor (EDLC). Surface modification of single-walled carbon nanotube (SWNT) electrodes significantly affects the rest potential (E0) of EDLCs; acid treatment and polyethyleneimine (PEI) coating of SWNTs shift E0 toward more positive and more negative values, respectively. Adjusting E0 towards the center of the electrolyte stability window can increase the cell voltage and hence the energy density. PEI coating on SWNTs increases the cell voltage from 0.8 V to 1.7 V in tetrabutylammonium perchlorate (TBAP)/tetrahydrofuran (THF) electrolyte, and from 2.5 V to 3.1 V in tetraethylammonium tetrafluoroborate (TEABF4)/3-cyanopropionic acid methyl ester (CPAME), respectively. Moreover, PEI-SWNT EDLCs exhibit excellent cycling stability (92% of capacitance retention over 10000 cycles). We attribute the shift in E0 to a change in the Fermi level of SWNTs owing to the surface charge modification. Injection of electrical charge into PEI-SWNTs consistently yielded similar trends and thus validated our hypothesis. Our results may help to push various electrolytes that have been overlooked so far to new frontiers for obtaining high energy-density supercapacitors.

Relative optical absorption of metallic and semiconducting single-walled carbon nanotubes.

PubMed

Huang, Houjin; Kajiura, Hisashi; Maruyama, Ryuichiro; Kadono, Koji; Noda, Kazuhiro

2006-03-16

While it is well-known that tube-tube interaction causes changes (peak red-shift and suppression) in the optical absorption of single-walled carbon nanotubes (SWNTs), we found in this work that, upon bundling, the optical absorption of metallic SWNTs (M11) is less affected compared to their semiconducting counterparts (S11 or S22), resulting in enhanced absorbance ratio of metallic and semiconducting SWNTs (A(M)/A(S)). Annealing of the SWNTs increases this ratio due to the intensified tube-tube interaction. We have also found that the interaction between SWNTs and the surfactant Triton X-405 has a similar effect. The evaluation of SWNT separation by types (metallic or semiconducting) based on the optical absorption should take these effects into account.

Effects of Carbonyl Bond and Metal Cluster Dissociation and Evaporation Rates on Predictions of Nanotube Production in HiPco

NASA Technical Reports Server (NTRS)

Scott, Carl D.; Smalley, Richard E.

2002-01-01

The high-pressure carbon monoxide (HiPco) process for producing single-wall carbon nanotubes (SWNT) uses iron pentacarbonyl as the source of iron for catalyzing the Boudouard reaction. Attempts using nickel tetracarbonyl led to no production of SWNTs. This paper discusses simulations at a constant condition of 1300 K and 30 atm in which the chemical rate equations are solved for different reaction schemes. A lumped cluster model is developed to limit the number of species in the models, yet it includes fairly large clusters. Reaction rate coefficients in these schemes are based on bond energies of iron and nickel species and on estimates of chemical rates for formation of SWNTs. SWNT growth is measured by the co-formation of CO2. It is shown that the production of CO2 is significantly greater for FeCO due to its lower bond energy as compared with that ofNiCO. It is also shown that the dissociation and evaporation rates of atoms from small metal clusters have a significant effect on CO2 production. A high rate of evaporation leads to a smaller number of metal clusters available to catalyze the Boudouard reaction. This suggests that if CO reacts with metal clusters and removes atoms from them by forming MeCO, this has the effect of enhancing the evaporation rate and reducing SWNT production. The study also investigates some other reactions in the model that have a less dramatic influence.

The Role of Percolation Theory in Developing Next Generation Smart Nanomaterials

NASA Astrophysics Data System (ADS)

Simien, Daneesh

2016-01-01

The incorporation of small volume fractions of nanoscale graphitic particles into varied base materials has been explored across fields ranging from automotive to aerospace to commercial plastics, with the goal of utilizing their enhanced thermal conductivity, electrical conductivity or mechanical strength. Percolation theory has emerged as a useful tool to aid in mapping and predicting the enhancement of properties based on the size and conductivity of incorporated single-walled carbon nanotubes relative to their less conductive base materials. These tools can aid researchers in the development of next generation smart nanomaterials. In this paper, we discuss the use of homogeneous fractions of length- or chirality-sorted single-walled carbon nanotubes (SWNTs) which are incorporated into thin film networks, and cement composites, and are evaluated in terms of their conductivity, mechanical properties and noise spectrum at critical percolation. We demonstrate that, near the percolation threshold, the conductivity of these highly characterized SWNT films exhibits a power law dependence on the network geometrical parameters. We also present our findings on the development of incorporated thin film SWNTs for the development of sensing technology for novel non-destructive failure diagnostic applications. SWNTs are able to be used as benign inclusions, capable of active sensing, when incorporated into cement-based composites for the purpose of detecting crack initiation. As such, we investigate the use of homogeneous length-sorted SWNTs that are randomly distributed in percolated networks capable of being an internal responsive net mechanism. Our findings demonstrate increased microstructure sensitivity of our networks for our shorter length nanotubes near their critical percolation threshold. This shows promise for the development of even more sensitive, embedded piezo-resistive SWNT-based sensors for preemptive failure detection technology.

Noncovalent functionalization of carbon nanotubes with porphyrins: meso-tetraphenylporphine and its transition metal complexes.

PubMed

Basiuk, Elena V; Basiuk, Vladimir A; Santiago, Patricia; Puente-Lee, Iván

2007-01-01

Noncovalent functionalization of carbon nanotubes with meso-tetraphenylporphine (H2TPP) and its metal(II) complexes NiTPP and CoTPP was studied by means of different experimental techniques and theoretical calculations. As follows from the experimental adsorption curves, free H2TPP ligand exhibits the strongest adsorption of three porphyrins tested, followed by CoTPP and NiTPP. At the highest porphyrin concentrations studied, the adsorption at multi-walled carbon nanotubes was about 2% (by weight) for H2TPP, 1% for CoTPP, and 0.5% for NiTPP. Transmission electron microscopy observations revealed carbon nanotubes with a variable degree of surface coverage with porphyrin molecules. According to scanning electron microscopy, the nanotubes glue together rather than debundle; apparently, a large porphyrin excess resulting in polymolecular adsorption is essential for exfoliation/debundling of the nanotube ropes. The nanotube/porphyrins hybrids were studied by infrared and Raman spectroscopy, as well as by scanning tunneling microscopy. Electronic structure calculations were performed at the B3LYP/LANL2MB theoretical level with the unsubstituted porphine (H2P) and its Co(II) complex, on one hand, and open-end armchair (5,5) (ANT) and zigzag (8,0) (ZNT) SWNT models, on the other hand. The interaction of H2P with ANT was found to be by 3.9 kcal mol(-1) stronger than that of CoP. At the same time, CoP+ZNT complex is more stable by 42.7 kcal mol(-1) as compared to H2P+ZNT According to these calculated results, the free porphyrins interact less selectively with zigzag and armchair (i.e., semiconducting and metallic) nanotubes, whereas the difference becomes very large for the metal porphyrins. HOMO-LUMO structure, electrostatic potential and spin density distribution for the paramagnetic cobalt(II) complexes were analyzed.

Ambipolar behavior and thermoelectric properties of WS2 nanotubes

NASA Astrophysics Data System (ADS)

Yomogida, Yohei; Kawai, Hideki; Sugahara, Mitsunari; Okada, Ryotaro; Yanagi, Kazuhiro

WS2 nanotubes are rolled multi-walled nanotubes made by a layered material, tungsten disulfides Since the discovery by Tenne et al in 1992, various physical properties have been revealed. Theoretical studies have suggested their distinct electronic properties from those of two dimensional sheet, such as one-dimensional electronic strucutures with sharp van Hove singularities and chiralitiy depended electronic structures. Their fibril structures enable us to make their random network films, however, the films are not conducting, and thus have not been used for electronic applications. Here we demonstrate that carrier injections on the WS2 networks by an electrolyte gating approach could make the networks as a semiconducting channel. We clarified the Raman characteristics of WS2 nanotubes networks under electrolyte gating, and confirmed capability of electron and hole injections. We revealed ambipolar behaviors of the WS2 nanotube networks in field effect transistor setups with electrolyte gating. In additio, we demosntrate N-type and P-type control of thermoelectric properties of WS2 nanotubes by electrolyte gating.The power factor of the WS2 nanotubes almost approached to that of the single crystalline WS2 flakes, suggesting good potential for thermoelectric applications..

Photothermal Desorption of Single-Walled Carbon Nanotubes and Coconut Shell-Activated Carbons Using a Continuous Light Source for Application in Air Sampling

PubMed Central

Floyd, Evan L.; Sapag, Karim; Oh, Jonghwa; Lungu, Claudiu T.

2014-01-01

Many techniques exist to measure airborne volatile organic compounds (VOCs), each with differing advantages; sorbent sampling is compact, versatile, has good sample stability, and is the preferred technique for collecting VOCs for hygienists. Development of a desorption technique that allows multiple analyses per sample (similar to chemical desorption) with enhanced sensitivity (similar to thermal desorption) would be helpful to field hygienists. In this study, activated carbon (AC) and single-walled carbon nanotubes (SWNT) were preloaded with toluene vapor and partially desorbed with light using a common 12-V DC, 50-W incandescent/halogen lamp. A series of experimental chamber configurations were explored starting with a 500-ml chamber under static conditions, then with low ventilation and high ventilation, finally a 75-ml high ventilation chamber was evaluated. When preloaded with toluene and irradiated at the highest lamp setting for 4min, AC desorbed 13.9, 18.5, 23.8, and 45.9% of the loaded VOC mass, in each chamber configuration, respectively; SWNT desorbed 25.2, 24.3, 37.4, and 70.5% of the loaded VOC mass, respectively. SWNT desorption was significantly greater than AC in all test conditions (P = 0.02–<0.0001) demonstrating a substantial difference in sorbent performance. When loaded with 0.435mg toluene and desorbed at the highest lamp setting for 4min in the final chamber design, the mean desorption for AC was 45.8% (39.7, 52.0) and SWNT was 72.6% (68.8, 76.4) (mean represented in terms of 95% confidence interval). All desorption measurements were obtained using a field grade photoionization detector; this demonstrates the potential of using this technique to perform infield prescreening of VOC samples for immediate exposure feedback and in the analytical lab to introduce sample to a gas chromatograph for detailed analysis of the sample. PMID:25016598

Hierarchical and Multifunctional Three-dimensional Network of Carbon Nanotubes for Supercapacitor and Strain Sensor Applications

DTIC Science & Technology

2016-05-19

cycles at 100 mV/s scan rate. 15. SUBJECT TERMS Carbon nano tubes, Nanotechnology , supercapacitor 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF...5. Lee, H., Hierarchical and Multifunctional Three-dimensional Network of Carbon Nanotubes of Sensor Applications, College of Engineering Forum on

Polyelectrolyte and carbon nanotube multilayers made from ionic liquid solutions

NASA Astrophysics Data System (ADS)

Nakashima, Takuya; Zhu, Jian; Qin, Ming; Ho, Szushen; Kotov, Nicholas A.

2010-10-01

The inevitable contact of substrates with water during the traditional practice of layer-by-layer assembly (LBL) creates problems for multiple potential applications of LBL films in electronics. To resolve this issue, we demonstrate here the possibility of a LBL process using ionic liquids (ILs), which potentially eliminates corrosion and hydration processes related to aqueous media and opens additional possibilities in structural control of LBL films. ILs are also considered to be one of the best ``green'' processing solvents, and hence, are advantageous in respect to traditional organic solvents. Poly(ethyleneimine) (PEI) and poly(sodium styrenesulfonate) (PSS) were dispersed in a hydrophilic IL and successfully deposited in the LBL fashion. To produce electroactive thin films with significance to electronics, a similar process was realized for PSS-modified single-walled carbon nanotubes (SWNT-PSS) and poly(vinyl alcohol) (PVA). Characterization of the coating using standard spectroscopy and microscopy techniques typical of the multilayer field indicated that there are both similarities and differences in the structure and properties of LBL films build from ILs and aqueous solutions. The films exhibited electrical conductivity of 102 S m-1 with transparency as high as 98% for visible light, which is comparable to similar parameters for many carbon nanotube and graphene films prepared by both aqueous LBL and other methods.The inevitable contact of substrates with water during the traditional practice of layer-by-layer assembly (LBL) creates problems for multiple potential applications of LBL films in electronics. To resolve this issue, we demonstrate here the possibility of a LBL process using ionic liquids (ILs), which potentially eliminates corrosion and hydration processes related to aqueous media and opens additional possibilities in structural control of LBL films. ILs are also considered to be one of the best ``green'' processing solvents, and hence, are

Unified equivalent circuit model for carbon nanotube-based nanocomposites.

PubMed

Zhao, Chaoyang; Yuan, Weifeng; Zhao, Yangzhou; Hu, Ning; Gu, Bin; Liu, Haidong; Alamusi

2018-07-27

Carbon nanotubes form a complex network in nanocomposites. In the network, the configuration of the nanotubes is various. A carbon nanotube may be curled or straight, and it may be parallel or crossed to another. As a result, carbon nanotube-based composites exhibit integrated characteristics of inductor, capacitor and resistor. In this work, it is hypothesised that carbon nanotube-based composites all adhere to a RLC interior circuit. To verify the hypothesis, three different composites, viz multi-walled carbon nanotube/polyvinylidene fluoride (MWCNT/PVDF), multi-walled carbon nanotube/epoxy (MWCNT/EP), multi-walled carbon nanotube/polydimethylsiloxane (MWCNT/PDMS) were fabricated and tested. The resistances and the dielectric loss tangent (tanδ) of the materials were measured in direct and alternating currents. The measurement shows that the value of tanδ is highly affected by the volume fraction of MWCNT in the composites. The experimental results prove that the proposed RLC equivalent circuit model can fully describe the electrical properties of the MWCNT network in nanocomposites. The RLC model provides a new route to detect the inductance and capacitance of carbon nanotubes. Moreover, the model also indicates that the carbon nanotube-based composite films may be used to develop wireless strain sensors.

Selective functionalization of carbon nanotube tips allowing fabrication of new classes of nanoscale sensing and manipulation tools

NASA Technical Reports Server (NTRS)

Wade, Lawrence A. (Inventor); Shapiro, Ian R. (Inventor); Bittner, Jr., Vern Garrett (Inventor); Collier, Charles Patrick (Inventor); Esplandiu, Maria J. (Inventor); Giapis, Konstantinos P. (Inventor)

2009-01-01

Embodiments in accordance with the present invention relate to techniques for the growth and attachment of single wall carbon nanotubes (SWNT), facilitating their use as robust and well-characterized tools for AFM imaging and other applications. In accordance with one embodiment, SWNTs attached to an AFM tip can function as a structural scaffold for nanoscale device fabrication on a scanning probe. Such a probe can trigger, with nanometer precision, specific biochemical reactions or conformational changes in biological systems. The consequences of such triggering can be observed in real time by single-molecule fluorescence, electrical, and/or AFM sensing. Specific embodiments in accordance with the present invention utilize sensing and manipulation of individual molecules with carbon nanotubes, coupled with single-molecule fluorescence imaging, to allow observation of spectroscopic signals in response to mechanically induced molecular changes. Biological macromolecules such as proteins or DNA can be attached to nanotubes to create highly specific single-molecule probes for investigations of intermolecular dynamics, for assembling hybrid biological and nanoscale materials, or for developing molecular electronics. In one example, electrical wiring of single redox enzymes to carbon nanotube scanning probes allows observation and electrochemical control over single enzymatic reactions by monitoring fluorescence from a redox-active cofactor or the formation of fluorescent products. Enzymes ''nanowired'' to the tips of carbon nanotubes in accordance with embodiments of the present invention, may enable extremely sensitive probing of biological stimulus-response with high spatial resolution, including product-induced signal transduction.

Carbon nanotube dispersed conductive network for microbial fuel cells

NASA Astrophysics Data System (ADS)

Matsumoto, S.; Yamanaka, K.; Ogikubo, H.; Akasaka, H.; Ohtake, N.

2014-08-01

Microbial fuel cells (MFCs) are promising devices for capturing biomass energy. Although they have recently attracted considerable attention, their power densities are too low for practical use. Increasing their electrode surface area is a key factor for improving the performance of MFC. Carbon nanotubes (CNTs), which have excellent electrical conductivity and extremely high specific surface area, are promising materials for electrodes. However, CNTs are insoluble in aqueous solution because of their strong intertube van der Waals interactions, which make practical use of CNTs difficult. In this study, we revealed that CNTs have a strong interaction with Saccharomyces cerevisiae cells. CNTs attach to the cells and are dispersed in a mixture of water and S. cerevisiae, forming a three-dimensional CNT conductive network. Compared with a conventional two-dimensional electrode, such as carbon paper, the three-dimensional conductive network has a much larger surface area. By applying this conductive network to MFCs as an anode electrode, power density is increased to 176 μW/cm2, which is approximately 25-fold higher than that in the case without CNTs addition. Maximum current density is also increased to approximately 8-fold higher. These results suggest that three-dimensional CNT conductive network contributes to improve the performance of MFC by increasing surface area.

Chemical sensors using coated or doped carbon nanotube networks

NASA Technical Reports Server (NTRS)

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

2010-01-01

Methods for using modified single wall carbon nanotubes ("SWCNTs") to detect presence and/or concentration of a gas component, such as a halogen (e.g., Cl.sub.2), hydrogen halides (e.g., HCl), a hydrocarbon (e.g., C.sub.nH.sub.2n+2), an alcohol, an aldehyde or a ketone, to which an unmodified SWCNT is substantially non-reactive. In a first embodiment, a connected network of SWCNTs is coated with a selected polymer, such as chlorosulfonated polyethylene, hydroxypropyl cellulose, polystyrene and/or polyvinylalcohol, and change in an electrical parameter or response value (e.g., conductance, current, voltage difference or resistance) of the coated versus uncoated SWCNT networks is analyzed. In a second embodiment, the network is doped with a transition element, such as Pd, Pt, Rh, Ir, Ru, Os and/or Au, and change in an electrical parameter value is again analyzed. The parameter change value depends monotonically, not necessarily linearly, upon concentration of the gas component. Two general algorithms are presented for estimating concentration value(s), or upper or lower concentration bounds on such values, from measured differences of response values.

Synthesis of subnanometer-diameter vertically aligned single-walled carbon nanotubes with copper-anchored cobalt catalysts.

PubMed

Cui, Kehang; Kumamoto, Akihito; Xiang, Rong; An, Hua; Wang, Benjamin; Inoue, Taiki; Chiashi, Shohei; Ikuhara, Yuichi; Maruyama, Shigeo

2016-01-21

We synthesize vertically aligned single-walled carbon nanotubes (VA-SWNTs) with subnanometer diameters on quartz (and SiO2/Si) substrates by alcohol CVD using Cu-anchored Co catalysts. The uniform VA-SWNTs with a nanotube diameter of 1 nm are synthesized at a CVD temperature of 800 °C and have a thickness of several tens of μm. The diameter of SWNTs was reduced to 0.75 nm at 650 °C with the G/D ratio maintained above 24. Scanning transmission electron microscopy energy-dispersive X-ray spectroscopy (EDS-STEM) and high angle annular dark field (HAADF-STEM) imaging of the Co/Cu bimetallic catalyst system showed that Co catalysts were captured and anchored by adjacent Cu nanoparticles, and thus were prevented from coalescing into a larger size, which contributed to the small diameter of SWNTs. The correlation between the catalyst size and the SWNT diameter was experimentally clarified. The subnanometer-diameter and high-quality SWNTs are expected to pave the way to replace silicon for next-generation optoelectronic and photovoltaic devices.

Wrinkling and folding of nanotube-polymer bilayers

NASA Astrophysics Data System (ADS)

Semler, Matthew R.; Harris, John M.; Hobbie, Erik K.

2014-07-01

The influence of a polymer capping layer on the deformation of purified single-wall carbon nanotube (SWCNT) networks is analyzed through the wrinkling of compressed SWCNT-polymer bilayers on polydimethylsiloxane. The films exhibit both wrinkling and folding under compression and we extract the elastoplastic response using conventional two-plate buckling schemes. The formation of a diffuse interpenetrating nanotube-polymer interface has a dramatic effect on the nanotube layer modulus for both metallic and semiconducting species. In contrast to the usual percolation exhibited by the pure SWCNT films, the capped films show a crossover from "composite" behavior (the modulus of the SWCNT film is enhanced by the polymer) to "plasticized" behavior (the modulus of the SWCNT film is reduced by the polymer) as the SWCNT film thickness increases. For almost all thicknesses, however, the polymer enhances the yield strain of the nanotube network. Conductivity measurements on identical films suggest that the polymer has a modest effect on charge transport, which we interpret as a strain-induced polymer penetration of interfacial nanotube contacts. We use scaling, Flory-Huggins theory, and independently determined nanotube-nanotube and nanotube-polymer Hamaker constants to model the response.

Chemical Reaction and Flow Modeling in Fullerene and Nanotube Production

NASA Technical Reports Server (NTRS)

Scott, Carl D.; Farhat, Samir; Greendyke, Robert B.

2004-01-01

addresses modeling of the arc process for fullerene and carbon nanotube production using O-D, 1-D and 2-D fluid flow models. The third part addresses simulations of the pulsed laser ablation process using time-dependent techniques in 2-D, and a steady state 2-D simulation of a continuous laser ablation process. The fourth part addresses steady state modeling in O-D and 2-D of the HiPco process. In each of the simulations, there is a variety of simplifications that are made that enable one to concentrate on one aspect or another of the process. There are simplifications that can be made to the chemical reaction models , e.g. reduction in number of species by lumping some of them together in a representative species. Other simulations are carried out by eliminating the chemistry altogether in order to concentrate on the fluid dynamics. When solving problems with a large number of species in more than one spatial dimension, it is almost imperative that the problem be decoupled by solving for the fluid dynamics to find the fluid motion and temperature history of "particles" of fluid moving through a reactor. Then one can solve the chemical rate equations with complex chemistry following the temperature and pressure history. One difficulty is that often mixing with an ambient gas is involved. Therefore, one needs to take dilution and mixing into account. This changes the ratio of carbon species to background gas. Commercially available codes may have no provision for including dilution as part of the input. One must the write special solvers for including dilution in decoupled problems. The article addresses both ful1erene production and single-walled carbon nanotube (SWNT) production. There are at least two schemes or concepts of SWNT growth. This article will only address growth in the gas phase by carbon and catalyst cluster growth and SW T formation by the addition of carbon. There are other models that conceive of SWNT growth as a phase separation process from clusters me

Cytotoxicity of doxrubicin loaded single-walled carbon nanotubes.

PubMed

Ünlü, Ayhan; Meran, Mehdi; Dinc, Bircan; Karatepe, Nilgün; Bektaş, Muhammet; Güner, F Seniha

2018-05-24

Carbon nanotube (CNTs) is a new alternative for efficient drug delivery and it has a great potential to change drug delivery system profile in pharmaceutical industry. One of the important advantage of CNTs is their needle-like, cylindrical shape. This shape provides a high surface area for multiple connections and adsorption onto for millions of therapeutic molecules. CNTs can be internalized by cells via endocytosis, passive diffusion and phagocytosis and release the drug with different effects like pH and temperature. The acidic nature of cancer cells and the susceptibility of CNTs to release the drug in the acidic environment have made it a promising area of research in cancer drug delivery. In this research, we investigated cell viability, cytotoxicity and drug delivery in breast cancer cell line by designing non-covalent single walled carbon nanotubes (SWNT)-doxorubicin (DOX) supramolecular complex that can be developed for cancer therapy. Applied high concentrations of DOX loaded SWNTs changed the actin structure of the cells and prevented the proliferation of the cells. It was showed that doxorubicin loaded SWNTs were more effective than free doxorubicin at relatively small concentrations. Once we applied same procedure for short and long (short: 1-1.3 µm; long: 2.5-4 µm) SWNTs and compared the results, more disrupted cell structure and reduction in cell proliferation were observed for long CNTs. DOX is bounded more to nanotubes in basic medium, less bound in acidic environment. Cancer cells were also examined for concentration at which they were effective by applying DOX and it was seen that 3.68 µM doxorubicin kills more than 55% of the cells.

Extraction of RBM frequency of a (10, 0) SWNT using MATLAB

NASA Astrophysics Data System (ADS)

Yadav, Monika; Negi, Sunita

2018-05-01

In the last few decades carbon nanotubes (CNT) have attracted great interest for future applications of these tubes in the field of electronics, composite material and drug delivery etc. The normal modes associated with a carbon nanotube are therefore important to be understood for a better understanding of their behavior. In this paper we report the frequency of the most important "Radial Breathing Mode (RBM)" associated with a single walled carbon nanotube. This is done with the help of a MATLAB program. We observe a RBM frequency associated with a (10, 0) single walled carbon nanotube at 340 cm-1. A very slow frequency component is also observed to be associated with the RBM of the carbon nanotube as reported earlier also. This method used for the extraction of RBM frequency is observed to be simple and fast as compared with the other methods.

Hydrogen adsorption and desorption with 3D silicon nanotube-network and film-network structures: Monte Carlo simulations

NASA Astrophysics Data System (ADS)

Li, Ming; Huang, Xiaobo; Kang, Zhan

2015-08-01

Hydrogen is clean, sustainable, and renewable, thus is viewed as promising energy carrier. However, its industrial utilization is greatly hampered by the lack of effective hydrogen storage and release method. Carbon nanotubes (CNTs) were viewed as one of the potential hydrogen containers, but it has been proved that pure CNTs cannot attain the desired target capacity of hydrogen storage. In this paper, we present a numerical study on the material-driven and structure-driven hydrogen adsorption of 3D silicon networks and propose a deformation-driven hydrogen desorption approach based on molecular simulations. Two types of 3D nanostructures, silicon nanotube-network (Si-NN) and silicon film-network (Si-FN), are first investigated in terms of hydrogen adsorption and desorption capacity with grand canonical Monte Carlo simulations. It is revealed that the hydrogen storage capacity is determined by the lithium doping ratio and geometrical parameters, and the maximum hydrogen uptake can be achieved by a 3D nanostructure with optimal configuration and doping ratio obtained through design optimization technique. For hydrogen desorption, a mechanical-deformation-driven-hydrogen-release approach is proposed. Compared with temperature/pressure change-induced hydrogen desorption method, the proposed approach is so effective that nearly complete hydrogen desorption can be achieved by Si-FN nanostructures under sufficient compression but without structural failure observed. The approach is also reversible since the mechanical deformation in Si-FN nanostructures can be elastically recovered, which suggests a good reusability. This study may shed light on the mechanism of hydrogen adsorption and desorption and thus provide useful guidance toward engineering design of microstructural hydrogen (or other gas) adsorption materials.

Carbon nanotubes might improve neuronal performance by favouring electrical shortcuts.

PubMed

Cellot, Giada; Cilia, Emanuele; Cipollone, Sara; Rancic, Vladimir; Sucapane, Antonella; Giordani, Silvia; Gambazzi, Luca; Markram, Henry; Grandolfo, Micaela; Scaini, Denis; Gelain, Fabrizio; Casalis, Loredana; Prato, Maurizio; Giugliano, Michele; Ballerini, Laura

2009-02-01

Carbon nanotubes have been applied in several areas of nerve tissue engineering to probe and augment cell behaviour, to label and track subcellular components, and to study the growth and organization of neural networks. Recent reports show that nanotubes can sustain and promote neuronal electrical activity in networks of cultured cells, but the ways in which they affect cellular function are still poorly understood. Here, we show, using single-cell electrophysiology techniques, electron microscopy analysis and theoretical modelling, that nanotubes improve the responsiveness of neurons by forming tight contacts with the cell membranes that might favour electrical shortcuts between the proximal and distal compartments of the neuron. We propose the 'electrotonic hypothesis' to explain the physical interactions between the cell and nanotube, and the mechanisms of how carbon nanotubes might affect the collective electrical activity of cultured neuronal networks. These considerations offer a perspective that would allow us to predict or engineer interactions between neurons and carbon nanotubes.

Importance of network density of nanotube: Effect on nitrogen dioxide gas sensing by solid state resistive sensor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mishra, Prabhash; Grachyova, D. V.; Moskalenko, A. S.

2016-04-13

Dispersion of single-walled carbon nanotubes (SWCNTs) is an established fact, however, its effect on toxic gas sensing for the development of solid state resistive sensor was not well reported. In this report, the dispersion quality of SWCNTs has been investigated and improved, and this well-dispersed SWCNTs network was used for sensor fabrication to monitor nitrogen dioxide gas. Ultraviolet (UV)-visible spectroscopic studies shows the strength of SWNTs dispersion and scanning electron microscopy (SEM) imaging provides the morphological properties of the sensor device. In this gas sensor device, two sets of resistive type sensors were fabricated that consisting of a pair ofmore » interdigitated electrodes (IDEs) using dielectrophoresis technique with different SWCNTs network density. With low-density SWCNTs networks, this fabricated sensor exhibits a high response for nitrogen dioxide sensing. The sensing of nitrogen dioxide is mainly due to charge transfer from absorbed molecules to sidewalls of nanotube and tube-tube screening acting a major role for the transport properties of charge carriers.« less

Thin and flexible all-solid supercapacitor prepared from novel single wall carbon nanotubes/polyaniline thin films obtained in liquid-liquid interfaces

NASA Astrophysics Data System (ADS)

de Souza, Victor Hugo Rodrigues; Oliveira, Marcela Mohallem; Zarbin, Aldo José Gorgatti

2014-08-01

The present work describes for the first time the synthesis and characterization of single wall carbon nanotubes/polyaniline (SWNTs/PAni) nanocomposite thin films in a liquid-liquid interface, as well as the subsequent construction of a flexible all-solid supercapacitor. Different SWNTs/PAni nanocomposites were prepared by varying the ratio of SWNT to aniline, and the samples were characterized by scanning and transmission electron microscopy, Raman and UV-Vis spectroscopy, cyclic voltammetry and electrochemical impedance spectroscopy. The pseudo-capacitive behavior of the nanocomposites was evaluated by charge/discharge galvanostatic measurements. The presence of the SWNTs affected the electronic and vibrational properties of the polyaniline and also improved the pseudo-capacitive behavior of the conducting polymer. A very thin and flexible all-solid device was manufactured using two electrodes (polyethylene terephthalate-PET covered with the SWNT/PAni nanocomposite separated by a H2SO4-PVA gel electrolyte). The pseudo-capacitive behavior was characterized by a volumetric specific capacitance of approximately 76.7 F cm-3, even under mechanical deformation, indicating that this nanocomposite has considerable potential for application in new-generation energy storage devices.

Label-free detection of cardiac troponin-I using gold nanoparticles functionalized single-walled carbon nanotubes based chemiresistive biosensor

NASA Astrophysics Data System (ADS)

Rajesh, Sharma, Vikash; Puri, Nitin K.; Singh, Rajiv K.; Biradar, Ashok M.; Mulchanadani, Ashok

2013-11-01

We report a specific and ultrasensitive, label-free chemiresistive biosensor based on mercaptopropionic acid capped gold nanoparticles (GNP) functionalized single walled carbon nanotube (SWNT) hybrid for the detection of cardiac specific biomarker troponin-I (cTnI). GNPs were attached to SWNTs through a molecular linker 1-pyrenemethylamine. The highly specific cTnI antibody was covalently immobilized on GNPs through capping agent using carbodiimide coupling reaction. The cTnI interaction to its corresponding antibody was studied with respect to changes in conductance in SWNTs channel, and a detailed field-effect transistor characteristic was delineated. The device exhibited a linear response to cTnI from 0.01 to 10 ng ml-1.

Charge transport kinetics in a robust radical-substituted polymer/nanocarbon composite electrode

NASA Astrophysics Data System (ADS)

Sato, Kan; Oyaizu, Kenichi; Nishide, Hiroyuki

We have reported a series of organic radical-substituted polymers as new-type charge storage and transport materials which could be used for energy related devices such as batteries and solar cells. Redox-active radical moieties introduced to the non-conjugated polymer backbones enable the rapid electron transfer among the adjacent radical sites, and thus large diffusive flux of electrical charge at a bulk scale. Here we present the elucidated charge transport kinetics in a radical polymer/single-walled carbon nanotube (SWNT) composite electrode. The synergetic effect of electrical conduction by a three-dimensional SWNT network and electron self-exchange reaction by radical polymers contributed to the 105-fold (per 1 g of added SWNT) boosting of electrochemical reactions and exceptionally large current density (greater than 1 A/cm2) as a rechargeable electrode. A totally organic-based secondary battery with a submicron thickness was fabricated to demonstrate the splendid electrochemical performances. Grants-in-Aid for Scientific Research (No. 24225003, 15J00888) and the Leading Graduate Program in Science and Engineering, from the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT).

Photothermal desorption of single-walled carbon nanotubes and coconut shell-activated carbons using a continuous light source for application in air sampling.

PubMed

Floyd, Evan L; Sapag, Karim; Oh, Jonghwa; Lungu, Claudiu T

2014-08-01

Many techniques exist to measure airborne volatile organic compounds (VOCs), each with differing advantages; sorbent sampling is compact, versatile, has good sample stability, and is the preferred technique for collecting VOCs for hygienists. Development of a desorption technique that allows multiple analyses per sample (similar to chemical desorption) with enhanced sensitivity (similar to thermal desorption) would be helpful to field hygienists. In this study, activated carbon (AC) and single-walled carbon nanotubes (SWNT) were preloaded with toluene vapor and partially desorbed with light using a common 12-V DC, 50-W incandescent/halogen lamp. A series of experimental chamber configurations were explored starting with a 500-ml chamber under static conditions, then with low ventilation and high ventilation, finally a 75-ml high ventilation chamber was evaluated. When preloaded with toluene and irradiated at the highest lamp setting for 4min, AC desorbed 13.9, 18.5, 23.8, and 45.9% of the loaded VOC mass, in each chamber configuration, respectively; SWNT desorbed 25.2, 24.3, 37.4, and 70.5% of the loaded VOC mass, respectively. SWNT desorption was significantly greater than AC in all test conditions (P = 0.02-<0.0001) demonstrating a substantial difference in sorbent performance. When loaded with 0.435mg toluene and desorbed at the highest lamp setting for 4min in the final chamber design, the mean desorption for AC was 45.8% (39.7, 52.0) and SWNT was 72.6% (68.8, 76.4) (mean represented in terms of 95% confidence interval). All desorption measurements were obtained using a field grade photoionization detector; this demonstrates the potential of using this technique to perform infield prescreening of VOC samples for immediate exposure feedback and in the analytical lab to introduce sample to a gas chromatograph for detailed analysis of the sample. © The Author 2014. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

Carbon nanotube network evolution during deformation of PVDF-MWNT nanocomposites

NASA Astrophysics Data System (ADS)

Rizvi, Reza; Naguib, Hani E.

2013-04-01

The emergence of novel electronic systems and their requirements have necessitated the evolution of new material classes. The traditional electronic semiconductors and components are shifting from silicon based substrates to polymers and other organic compounds. Sensor components are no exceptions, where compliant polymeric materials offer the possibility of flexible electronics. This paper examines the fabrication and characterization of piezoresistive nanocomposites for pressure sensing applications. The matrix material employed was Polyvinylidene Fluoride (PVDF). The PVDF phase was reinforced with conductive particles, in order to form a conductive filler network throughout the nanocomposite. Multiwall carbon nanotubes (MWNT) were selected as conductive particles to form the networks. The composites were prepared by melt mixing the PVDF and conductive particles in compositions ranging from 0.25 to 10 wt% conductive particle in PVDF. The dielectric permittivity and electrical conductivity of the composites was characterized and the electrical percolation behavior of PVDF nanocomposites fitted to the statistical percolation model. Scanning electron was employed to understand the morphology of the filler networks in the PVDF nanocomposites. Quasi-static piezoresistance of the nanocomposites was characterized using a custom-built force-resistance measurement setup under compressive loading conditions.

Preserving π-conjugation in covalently functionalized carbon nanotubes for optoelectronic applications.

PubMed

Setaro, Antonio; Adeli, Mohsen; Glaeske, Mareen; Przyrembel, Daniel; Bisswanger, Timo; Gordeev, Georgy; Maschietto, Federica; Faghani, Abbas; Paulus, Beate; Weinelt, Martin; Arenal, Raul; Haag, Rainer; Reich, Stephanie

2017-01-30

Covalent functionalization tailors carbon nanotubes for a wide range of applications in varying environments. Its strength and stability of attachment come at the price of degrading the carbon nanotubes sp 2 network and destroying the tubes electronic and optoelectronic features. Here we present a non-destructive, covalent, gram-scale functionalization of single-walled carbon nanotubes by a new [2+1] cycloaddition. The reaction rebuilds the extended π-network, thereby retaining the outstanding quantum optoelectronic properties of carbon nanotubes, including bright light emission at high degree of functionalization (1 group per 25 carbon atoms). The conjugation method described here opens the way for advanced tailoring nanotubes as demonstrated for light-triggered reversible doping through photochromic molecular switches and nanoplasmonic gold-nanotube hybrids with enhanced infrared light emission.

Capture of trace sulfur gases from binary mixtures by single-walled carbon nanotube arrays: a molecular simulation study.

PubMed

Wang, Wenjuan; Peng, Xuan; Cao, Dapeng

2011-06-01

Adsorption of H(2)S and SO(2) pure gases and their selective capture from the H(2)S-CH(4), H(2)S-CO(2), SO(2)-N(2), and SO(2)-CO(2) binary mixtures by the single-walled carbon nanotubes (SWNT) are investigated via using the grand canonical Monte Carlo (GCMC) method. It is found that the (20, 20) SWNT with larger diameter shows larger capacity for H(2)S and SO(2) pure gases at T = 303 K, in which the uptakes reach 16.31 and 16.03 mmol/g, respectively. However, the (6,6) SWNT with small diameter exhibits the largest selectivity for binary mixtures containing trace sulfur gases at T = 303 K and P = 100 kPa. By investigating the effect of pore size on the separation of gas mixtures, we found that the optimized pore size is 0.81 nm for separation of H(2)S-CH(4), H(2)S-CO(2), and SO(2)-N(2) binary mixtures, while it is 1.09 nm for the SO(2)-CO(2) mixture. The effects of concentration and temperature on the selectivity of sulfide are also studied at the optimal pore size. It is found that the concentration (ppm) of sulfur components has little effect on selectivity of SWNTs for these binary mixtures. However, the selectivity decreases obviously with the increase of temperature. To improve the adsorption capacities, we further modify the surface of SWNTs with the functional groups. The selectivities of H(2)S-CO(2) and SO(2)-CO(2) mixtures are basically uninfluenced by the site density, while the increase of site density can improve the selectivity of H(2)S-CH(4) mixture doubly. It is expected that this work could provide useful information for sulfur gas capture.

Growing Carbon Nanotubes

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

In situ transmission electron microscope (TEM) video (accelerated 10 times) of nucleation and self-organization of a high-density carbon nanotube network from catalytic iron nanoparticles, forming a vertically aligned forest.

Low percolation transitions in carbon nanotube networks dispersed in a polymer matrix: dielectric properties, simulations and experiments.

PubMed

Simoes, Ricardo; Silva, Jaime; Vaia, Richard; Sencadas, Vítor; Costa, Pedro; Gomes, João; Lanceros-Méndez, Senentxu

2009-01-21

The low concentration behaviour and the increase of the dielectric constant in carbon nanotubes/polymer nanocomposites near the percolation threshold are still not well understood. In this work, a numerical model has been developed which focuses on the effect of the inclusion of conductive fillers in a dielectric polymer matrix on the dielectric constant and the dielectric strength. Experiments have been carried out in carbon nanotubes/poly(vinylidene fluoride) nanocomposites in order to compare to the simulation results. This work shows how the critical concentration is related to the formation of capacitor networks and that these networks give rise to high variations in the electrical properties of the composites. Based on numerical studies, the dependence of the percolation transition on the preparation of the nanocomposite is discussed. Finally, based on numerical and experimental results, both ours and from other authors, the causes of anomalous percolation behaviour of the dielectric constant are identified.

Design considerations and emerging challenges for nanotube-, nanowire-, and negative capacitor-field effect transistors

NASA Astrophysics Data System (ADS)

Wahab, Md. Abdul

As the era of classical planar metal-oxide-semiconductor field-effect transistors (MOSFETs) comes to an end, the semiconductor industry is beginning to adopt 3D device architectures, such as FinFETs, starting at the 22 nm technology node. Since physical limits such as short channel effect (SCE) and self-heating may dominate, it may be difficult to scale Si FinFET below 10 nm. In this regard, transistors with different materials, geometries, or operating principles may help. For example, gate has excellent electrostatic control over 2D thin film channel with planar geometry, and 1D nanowire (NW) channel with gate-all-around (GAA) geometry to reduce SCE. High carrier mobility of single wall carbon nanotube (SWNT) or III-V channels may reduce VDD to reduce power consumption. Therefore, as channel of transistor, 2D thin film of array SWNTs and 1D III-V multi NWs are promising for sub 10 nm technology nodes. In this thesis, we analyze the potential of these transistors from process, performance, and reliability perspectives. For SWNT FETs, we discuss a set of challenges (such as how to (i) characterize diameter distribution, (ii) remove metallic (m)-SWNTs, and (iii) avoid electrostatic cross-talk among the neighboring SWNTs), and demonstrate solution strategies both theoretically and experimentally. Regarding self-heating in these new class of devices (SWNT FET and GAA NW FET including state-of-the-art FinFET), higher thermal resistance from poor thermal conducting oxides results significant temperature rise, and reduces the IC life-time. For GAA NW FETs, we discuss accurate self-heating evaluation with good spatial, temporal, and thermal resolutions. The introduction of negative capacitor (NC), as gate dielectric stack of transistor, allows sub 60 mV/dec operation to reduce power consumption significantly. Taken together, our work provides a comprehensive perspective regarding the challenges and opportunities of sub 10 nm technology nodes.

Simple, Rapid, Sensitive, and Versatile SWNT-Paper Sensor for Environmental Toxin Detection Competitive with ELISA

PubMed Central

Wang, Libing; Chen, Wei; Xu, Dinghua; Shim, Bong Sup; Zhu, Yingyue; Sun, Fengxia; Liu, Liqiang; Peng, Chifang; Jin, Zhengyu; Xu, Chuanlai; Kotov, Nicholas A.

2009-01-01

Safety of water was for a long time and still is one of the most pressing needs for many countries and different communities. Despite the fact that there are potentially many methods to evaluate water safety, finding a simple, rapid, versatile, and inexpensive method for detection of toxins in everyday items is still a great challenge. In this study, we extend the concept of composites obtained impregnation of porous fibrous materials, such as fabrics and papers, by single walled carbon-nanotubes (SWNTs) toward very simple but high-performance biosensors. They utilize the strong dependence of electrical conductivity through nanotubes percolation network on the width of nanotubes-nanotube tunneling gap and can potentially satisfy all the requirements outlined above for the routine toxin monitoring. An antibody to the microcystin-LR (MC-LR), one of the common culprits in mass poisonings, was dispersed together with SWNTs. This dispersion was used to dip-coat the paper rendering it conductive. The change in conductivity of the paper was used to sense the MC-LR in the water rapidly and accurately. The method has the linear detection range up to 10 nmol/L and non-linear detection up to 40 nmol/L. The limit of detection was found to be 0.6 nmol/L (0.6 ng/mL), which satisfies the strictest World Health Organization standard for MC-LR content in drinking water (1 ng/mL), and is comparable to the detection limit of traditional ELISA method of MC-LR detection, while drastically reducing the time of analysis by more than an order of magnitude, which is one of the major hurdles in practical applications. Similar technology of sensor preparation can also be used for a variety of other rapid environmental sensors. PMID:19928776

Detection of ionized gas molecules in air by graphene and carbon nanotube networks

NASA Astrophysics Data System (ADS)

Hao, Ji; Li, Bo; Yung, Hyun Young; Liu, Fangze; Hong, Sanghyung; Jung, Yung Joon; Kar, Swastik

The liquid phase ions sensing by graphene and carbon nanotube has been demonstrated in many publications due to the minimum gate voltage easily shift induced by ionic gating effect, but it is still unclear for vapor phase ions sensing. Here we want to report that the ionized gas molecules in air can be also very sensitively detected by graphene and carbon nanotube networks under very low applied voltage, which shows the very high charge to current amplification factor, the value can be up to 108 A/C, and the direction of current-change can be used to differentiate the positive and negative ions. In further, the field effect of graphene device induced by vapor phase ions was discussed. NSF ECCS 1202376, NSF ECCS CAREER 1351424 and NSF DMREF 1434824, a Northeastern University Provost's Tier-1 seed Grant for interdisciplinary research, Technology Innovation Program (10050481) from Ministry of Trade, Industry & Energy of Republic of Korea.

Dielectric monitoring of carbon nanotube network formation in curing thermosetting nanocomposites

NASA Astrophysics Data System (ADS)

Battisti, A.; Skordos, A. A.; Partridge, I. K.

2009-08-01

This paper focuses on monitoring of carbon nanotube (CNT) network development during the cure of unsaturated polyester nanocomposites by means of electrical impedance spectroscopy. A phenomenological model of the dielectric response is developed using equivalent circuit analysis. The model comprises two parallel RC elements connected in series, each of them giving rise to a semicircular arc in impedance complex plane plots. An established inverse modelling methodology is utilized for the estimation of the parameters of the corresponding equivalent circuit. This allows a quantification of the evolution of two separate processes corresponding to the two parallel RC elements. The high frequency process, which is attributed to CNT aggregates, shows a monotonic decrease in characteristic time during the cure. In contrast, the low frequency process, which corresponds to inter-aggregate phenomena, shows a more complex behaviour explained by the interplay between conductive network development and the cross-linking of the polymer.

Chemically interconnected light-weight 3D-carbon nanotube solid network

DOE PAGES

Ozden, Sehmus; Tsafack, Thierry; Owuor, Peter S.; ...

2017-03-31

Owing to the weak physical interactions such as van der Waals and π-π interactions, which hold nanotubes together in carbon nanotube (CNT) bulk structures, the tubes can easily slide on each other. In creating covalent interconnection between individual carbon nanotube (CNT) structures we saw remarkable improvements in the properties of their three-dimensional (3D) bulk structures. The creation of such nanoengineered 3D solid structures with improved properties and low-density remains one of the fundamental challenges in real-world applications. We also report the scalable synthesis of low-density 3D macroscopic structure made of covalently interconnected nanotubes using free-radical polymerization method after functionalized CNTsmore » with allylamine monomers. The resulted interconnected highly porous solid structure exhibits higher mechanical properties, larger surface area and greater porosity than non-crosslinked nanotube structures. To gain further insights into the deformation mechanisms of nanotubes, fully atomistic reactive molecular dynamics simulations are used. Here we demonstrate one such utility in CO 2 uptake, whose interconnected solid structure performed better than non-interconnected structures.« less

Quantum coherence and temperature dependence of the anomalous state of nanoconfined water in carbon nanotubes

DOE PAGES

Reiter, George F.; Deb, Aniruddha; Sakurai, Y.; ...

2016-10-17

X-ray Compton scattering measurements of the electron momentum distribution in water confined in both single-walled and double-walled carbon nanotubes (SWNT and DWNT), as a function of temperature and confinement size are presented here together with earlier measurements of the proton momentum distribution in the same systems using neutron Compton scattering. These studies provide a coherent picture of an anomalous state of water that exists because of nanoconfinement. This state cannot be described by the weakly interacting molecule picture. It has unique transport properties for both protons and water molecules. In conclusion, we suggest that knowledge of the excitation spectrum ofmore » this state is needed to understand the enhanced flow of water in cylinders with diameters on the order of 20 Å.« less

On the optical properties of carbon nanotubes. Part I. A general formula for the dynamical optical conductivity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rasmussen, Morten Grud, E-mail: morteng@math.aau.dk; Ricaud, Benjamin, E-mail: benjamin.ricaud@epfl.ch; Savoie, Baptiste, E-mail: baptiste.savoie@gmail.com

2016-02-15

This paper is the first one in a series of two articles in which we revisit the optical properties of single-walled carbon nanotubes (SWNTs). Produced by rolling up a graphene sheet, SWNTs owe their intriguing properties to their cylindrical quasi-one-dimensional (quasi-1D) structure (the ratio length/radius is experimentally of order of 10{sup 3}). We model SWNT by circular cylinders of small diameters on the surface of which the conduction electron gas is confined by the electric field generated by the fixed carbon ions. The pair-interaction potential considered is the 3D Coulomb potential restricted to the cylinder. To reflect the quasi-1D structure,more » we introduce a 1D effective many-body Hamiltonian which is the starting-point of our analysis. To investigate the optical properties, we consider a perturbation by a uniform time-dependent electric field modeling an incident light beam along the longitudinal direction. By using Kubo’s method, we derive within the linear response theory an asymptotic expansion in the low-temperature regime for the dynamical optical conductivity at fixed density of particles. The leading term only involves the eigenvalues and associated eigenfunctions of the (unperturbed) 1D effective many-body Hamiltonian and allows us to account for the sharp peaks observed in the optical absorption spectrum of SWNT.« less

Spectroscopic investigation confirms retaining the pristine nature of single-walled carbon nanotubes on dissolution in aniline

NASA Astrophysics Data System (ADS)

Singha, Somdutta; Ghosh, Swapankumar

2017-09-01

Carbon nanotubes in all forms are very much insoluble in both organic and inorganic solvents due to its high agglomeration and entangled morphology. General methods for dissolution of single-walled carbon nanotubes (SWNTs) are mostly associated with complexation or polymerization or addition of macromolecules which change the physical or chemical properties of SWNTs and the pristine nature of SWNTs is lost. Dissolution of SWNTs in a solvent like aniline is practiced here which is a very simple reaction method. Here aniline is capable to form a SWNT-aniline charge transfer complex without attachment of macromolecules or polymer which is also soluble in other organic solvents. Solvation of SWNTs by this method is also capable of maintaining the similarity between the structure of SWNTs before and after the dissolution, which means that the pristine nature of SWNTs is preserved. Formation of charge transfer complex in this reaction has been proven by UV-Vis/NIR absorption and photoluminescence spectroscopy. Raman spectroscopy and electron microscopy (FESEM and TEM) are the evidences for protection of the pristine nature of SWNTs even after high-temperature complexation reaction with aniline and also after solubilization in organic solvents.

Resonance energy transfer (RET)-Induced intermolecular pairing force: a tunable weak interaction and its application in SWNT separation.

PubMed

Pan, Xiaoyong; Chen, Hui; Wang, Wei Zhi; Ng, Siu Choon; Chan-Park, Mary B

2011-07-21

This paper explores evidence of an optically mediated interaction that is active in the separation mechanism of certain selective agents through consideration of the contrasting selective behaviors of two conjugated polymers with distinct optical properties. The involvement of a RET-induced intermolecular pairing force is implied by the different illumination response behaviors. The magnitude of this interaction scales with the external stimulus parameter, the illumination irradiance (I), and thus is tunable. This suggests a facile technique to modify the selectivity of polymers toward specific SWNT species by altering the polymer structure to adjust the corresponding intermolecular interaction. This is the first experimental verification and application of a RET-induced intermolecular pairing force to SWNT separation. With this kind of interaction taken into account, reasonable interpretation of some conflicting data, especially PLE maps, can be easily made. The above conclusion can be applied to other substances as long as they are electrically neutral and there is photon-induced RET between them. The significant magnitude of this interaction makes direct manipulation of molecules/particles possible and is expected to have applications in molecular engineering. © 2011 American Chemical Society

Electro-purification of carbon nanotube networks without damaging the assembly structure and crystallinity

NASA Astrophysics Data System (ADS)

Yang, Xueqin; Yang, Ming; Zhang, Huichao; Zhao, Jingna; Zhang, Xiaohua; Li, Qingwen

2018-06-01

Fe-containing nanoparticles are of a high mass fraction in the as-grown carbon nanotube (CNT) network. By controlling the S-to-Fe atom ratio in the growth feedstock and introducing water as a weak oxidant, highly crystalline few-walled CNT network can be obtained, with a mass fraction of over 20 wt% for the Fe-containing nanoparticles. We report here an electron-oxidation-based purification method to efficiently remove the Fe-containing nanoparticles without inducing clear damage to either the assembly structure or the tube crystallinity. The purification could increase the ratio between Raman D and G peak intensities slightly from 0.08 to 0.12, decrease the specific conductivity from 0.31 to 0.24 S m2/g and the Fe content from >20 wt% to ≈1 wt%, and modify the capacitance just by about 13 F/g. All these indicate that the CNT network was well maintained by such gentle electro-oxidation-based purification. In addition, the purified CNT network can exhibit advantages in mechanical and electrical applications.

Hydrogen adsorption and desorption with 3D silicon nanotube-network and film-network structures: Monte Carlo simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Ming; Kang, Zhan, E-mail: zhankang@dlut.edu.cn; Huang, Xiaobo

2015-08-28

Hydrogen is clean, sustainable, and renewable, thus is viewed as promising energy carrier. However, its industrial utilization is greatly hampered by the lack of effective hydrogen storage and release method. Carbon nanotubes (CNTs) were viewed as one of the potential hydrogen containers, but it has been proved that pure CNTs cannot attain the desired target capacity of hydrogen storage. In this paper, we present a numerical study on the material-driven and structure-driven hydrogen adsorption of 3D silicon networks and propose a deformation-driven hydrogen desorption approach based on molecular simulations. Two types of 3D nanostructures, silicon nanotube-network (Si-NN) and silicon film-networkmore » (Si-FN), are first investigated in terms of hydrogen adsorption and desorption capacity with grand canonical Monte Carlo simulations. It is revealed that the hydrogen storage capacity is determined by the lithium doping ratio and geometrical parameters, and the maximum hydrogen uptake can be achieved by a 3D nanostructure with optimal configuration and doping ratio obtained through design optimization technique. For hydrogen desorption, a mechanical-deformation-driven-hydrogen-release approach is proposed. Compared with temperature/pressure change-induced hydrogen desorption method, the proposed approach is so effective that nearly complete hydrogen desorption can be achieved by Si-FN nanostructures under sufficient compression but without structural failure observed. The approach is also reversible since the mechanical deformation in Si-FN nanostructures can be elastically recovered, which suggests a good reusability. This study may shed light on the mechanism of hydrogen adsorption and desorption and thus provide useful guidance toward engineering design of microstructural hydrogen (or other gas) adsorption materials.« less

Carbon nanotube-enzyme conjugates for the fabrication of diagnostic biosensors

NASA Astrophysics Data System (ADS)

Karunwi, Olukayode Adedamola

The fabrication of multi-analyte biotransducers continues to be a major technical challenge when the length scales of the individual transducer elements are on the order of microns Generation-3 (Gen-3) biosensors and advanced enzyme biofuel cells will benefit from direct electron transfer to oxidoreductases facilitated by single-walled carbon nanotubes (SWNTs). Direct electron transfer helps to mitigate errors from the instability in oxygen tension, eliminate use of a mediator and produce a device with low operating potential close to the redox potential of the enzymes. Supramolecular conjugates of SWNT-glucose oxidase (GOx-SWNT) may be produced via ultrasonic processing. Using a Plackett-Burman experimental design to investigate the process of tip ultrasonication, conjugate formation was investigated as a function of ultrasonication times and functionalized SWNTs of various tube lengths. Supramolecular conjugates formed from shorter, -OH functionalized SWNTs using longer sonication times gave the most favored combination for forming bioactive conjugates. There has also been growing interest in the fabrication of CNT-enzyme supramolecular constructs that control the placement of SWNTs within tunneling distance of co-factors for enhanced electron transfer efficiency in generation 3 biosensors and advanced biofuel cells. These conjugate systems raise a series of questions such as: Which peptide sequences within the enzymes have high affinity for the SWNTs? And, are these high affinity sequences likely to be in the vicinity of the redox-active co-factor to allow for direct electron transfer? Phage display has recently been used to identify specific peptide sequences that have high affinity for SWNTs. Molecular dynamics simulations were performed to study the interactions of five discrete peptides with (16,0) SWNT in explicit water as well as with graphene. The end residues appear to dominate the progression of adsorption regardless of character. Sequences identified

Controlling signal transport in a carbon nanotube opto-transistor

NASA Astrophysics Data System (ADS)

Li, Jinjin; Chu, Yanhui; Zhu, Ka-Di

2016-11-01

With the highly competitive development of communication technologies, modern information manufactures place high importance on the ability to control the transmitted signal using easy miniaturization materials. A controlled and miniaturized optical information device is, therefore, vital for researchers in information and communication fields. Here we propose a controlled signal transport in a doubly clamped carbon nanotube system, where the transmitted signal can be controlled by another pump beam. Pump off results in the transmitted signal off, while pump on results in the transmitted signal on. The more pump, the more amplified output signal transmission. Analogous with traditional cavity optomechanical system, the role of optical cavity is played by a localized exciton in carbon nanotube while the role of the mechanical element is played by the nanotube vibrations, which enables the realization of an opto-transistor based on carbon nanotube. Since the signal amplification and attenuation have been observed in traditional optomechanical system, and the nanotube optomechanical system has been realized in laboratory, the proposed carbon nanotube opto-transistor could be implemented in current experiments and open the door to potential applications in modern optical networks and future quantum networks.

Nano Sponges for Drug Delivery and Medicinal Applications

NASA Technical Reports Server (NTRS)

Tour, James M.; Lucente-Schultz, Rebecca; Leonard, Ashley; Kosynkin, Dimitry V.; Price, Brandi Katherine; Hudson, Jared L.; Conyers, Jodie L., Jr.; Moore, Valerie C.; Casscells, S. Ward; Myers, Jeffrey N.;

Boron nitride nanotubes and nanosheets.

PubMed

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

2010-06-22

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

Reticular synthesis of porous molecular 1D nanotubes and 3D networks.

PubMed

Slater, A G; Little, M A; Pulido, A; Chong, S Y; Holden, D; Chen, L; Morgan, C; Wu, X; Cheng, G; Clowes, R; Briggs, M E; Hasell, T; Jelfs, K E; Day, G M; Cooper, A I

2017-01-01

Synthetic control over pore size and pore connectivity is the crowning achievement for porous metal-organic frameworks (MOFs). The same level of control has not been achieved for molecular crystals, which are not defined by strong, directional intermolecular coordination bonds. Hence, molecular crystallization is inherently less controllable than framework crystallization, and there are fewer examples of 'reticular synthesis', in which multiple building blocks can be assembled according to a common assembly motif. Here we apply a chiral recognition strategy to a new family of tubular covalent cages to create both 1D porous nanotubes and 3D diamondoid pillared porous networks. The diamondoid networks are analogous to MOFs prepared from tetrahedral metal nodes and linear ditopic organic linkers. The crystal structures can be rationalized by computational lattice-energy searches, which provide an in silico screening method to evaluate candidate molecular building blocks. These results are a blueprint for applying the 'node and strut' principles of reticular synthesis to molecular crystals.

Reticular synthesis of porous molecular 1D nanotubes and 3D networks

NASA Astrophysics Data System (ADS)

Slater, A. G.; Little, M. A.; Pulido, A.; Chong, S. Y.; Holden, D.; Chen, L.; Morgan, C.; Wu, X.; Cheng, G.; Clowes, R.; Briggs, M. E.; Hasell, T.; Jelfs, K. E.; Day, G. M.; Cooper, A. I.

2017-01-01

Synthetic control over pore size and pore connectivity is the crowning achievement for porous metal-organic frameworks (MOFs). The same level of control has not been achieved for molecular crystals, which are not defined by strong, directional intermolecular coordination bonds. Hence, molecular crystallization is inherently less controllable than framework crystallization, and there are fewer examples of 'reticular synthesis', in which multiple building blocks can be assembled according to a common assembly motif. Here we apply a chiral recognition strategy to a new family of tubular covalent cages to create both 1D porous nanotubes and 3D diamondoid pillared porous networks. The diamondoid networks are analogous to MOFs prepared from tetrahedral metal nodes and linear ditopic organic linkers. The crystal structures can be rationalized by computational lattice-energy searches, which provide an in silico screening method to evaluate candidate molecular building blocks. These results are a blueprint for applying the 'node and strut' principles of reticular synthesis to molecular crystals.

Coated or doped carbon nanotube network sensors as affected by environmental parameters

NASA Technical Reports Server (NTRS)

Li, Jing (Inventor)

2011-01-01

Methods for using modified single wall carbon nanotubes ("SWCNTs") to detect presence and/or concentration of a gas component, such as a halogen (e.g., Cl.sub.2), hydrogen halides (e.g., HCl), a hydrocarbon (e.g., C.sub.nH.sub.2n+2), an alcohol, an aldehyde or a ketone, to which an unmodified SWCNT is substantially non-reactive. In a first embodiment, a connected network of SWCNTs is coated with a selected polymer, such as chlorosulfonated polyethylene, hydroxypropyl cellulose, polystyrene and/or polyvinylalcohol, and change in an electrical parameter or response value (e.g., conductance, current, voltage difference or resistance) of the coated versus uncoated SWCNT networks is analyzed. In a second embodiment, the network is doped with a transition element, such as Pd, Pt, Rh, Ir, Ru, Os and/or Au, and change in an electrical parameter value is again analyzed. The parameter change value depends monotonically, not necessarily linearly, upon concentration of the gas component. Two general algorithms are presented for estimating concentration value(s), or upper or lower concentration bounds on such values, from measured differences of response values.

Vertical Alignment of Single-Walled Carbon Nanotubes on Nanostructure Fabricated by Atomic Force Microscope

DTIC Science & Technology

2007-05-01

SWNTs by blending them with liquid crystal,7 assem- bling SWNT films by Langmuir - Blodgett methods,8 and chemical assembly of SWNTs on a large substrate...Ulman, A. An Introduction to Ultrathin Organic Films from Langmuir - Blodgett to Self-Assembly. Academic: New York, (1991). [10] Moon, J.H., Shin, J.W...Fang, J. Langmuir , 16, 2651, (2000). [8] FT-IR data (Bruker IFS48, KBr Pellet): 1720 cm-1 (νC=O, SWNT-COOH) and 1770 cm-1 (νC=O, SWNT- COCl). [9

Composition Based Strategies for Controlling Radii in Lipid Nanotubes

PubMed Central

Kurczy, Michael E.; Mellander, Lisa J.; Najafinobar, Neda; Cans, Ann-Sofie

2014-01-01

Nature routinely carries out small-scale chemistry within lipid bound cells and organelles. Liposome–lipid nanotube networks are being developed by many researchers in attempt to imitate these membrane enclosed environments, with the goal to perform small-scale chemical studies. These systems are well characterized in terms of the diameter of the giant unilamellar vesicles they are constructed from and the length of the nanotubes connecting them. Here we evaluate two methods based on intrinsic curvature for adjusting the diameter of the nanotube, an aspect of the network that has not previously been controllable. This was done by altering the lipid composition of the network membrane with two different approaches. In the first, the composition of the membrane was altered via lipid incubation of exogenous lipids; either with the addition of the low intrinsic curvature lipid soy phosphatidylcholine (soy-PC) or the high intrinsic curvature lipid soy phosphatidylethanolamine (soy-PE). In the second approach, exogenous lipids were added to the total lipid composition during liposome formation. Here we show that for both lipid augmentation methods, we observed a decrease in nanotube diameter following soy-PE additions but no significant change in size following the addition of soy-PC. Our results demonstrate that the effect of soy-PE on nanotube diameter is independent of the method of addition and suggests that high curvature soy-PE molecules facilitate tube membrane curvature. PMID:24392077

Polarized excitons and optical activity in single-wall carbon nanotubes

NASA Astrophysics Data System (ADS)

Chang, Yao-Wen; Jin, Bih-Yaw

2018-05-01

The polarized excitons and optical activity of single-wall carbon nanotubes (SWNTs) are studied theoretically by π -electron Hamiltonian and helical-rotational symmetry. By taking advantage of the symmetrization, the single-particle energy and properties of a SWNT are characterized with the corresponding helical band structure. The dipole-moment matrix elements, magnetic-moment matrix elements, and the selection rules can also be derived. Based on different selection rules, the optical transitions can be assigned as the parallel-polarized, left-handed circularly-polarized, and right-handed circularly-polarized transitions, where the combination of the last two gives the cross-polarized transition. The absorption and circular dichroism (CD) spectra are simulated by exciton calculation. The calculated results are well comparable with the reported measurements. Built on the foundation, magnetic-field effects on the polarized excitons and optical activity of SWNTs are studied. Dark-bright exciton splitting and interband Faraday effect in the CD spectrum of SWNTs under an axial magnetic field are predicted. The Faraday rotation dispersion can be analyzed according to the selection rules of circular polarizations and the helical band structure.

Thermodynamics for the Formation of Double-Stranded DNA-Single-Walled Carbon Nanotube Hybrids.

PubMed

Shiraki, Tomohiro; Tsuzuki, Akiko; Toshimitsu, Fumiyuki; Nakashima, Naotoshi

2016-03-24

For the first time, the thermodynamics are described for the formation of double-stranded DNA (ds-DNA)-single-walled carbon nanotube (SWNT) hybrids. This treatment is applied to the exchange reaction of sodium cholate (SC) molecules on SWNTs and the ds-DNAs d(A)20 -d(T)20 and nuclear factor (NF)-κB decoy. UV/Vis/near-IR spectroscopy with temperature variations was used for analyzing the exchange reaction on the SWNTs with four different chiralities: (n,m)=(8,3), (6,5), (7,5), and (8,6). Single-stranded DNAs (ss-DNAs), including d(A)20 and d(T)20, are also used for comparison. The d(A)20-d(T)20 shows a drastic change in its thermodynamic parameters around the melting temperature (Tm ) of the DNA oligomer. No such Tm dependency was measured, owing to high Tm in the NF-κB decoy DNA and no Tm in the ss-DNA. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Improving subthreshold swing to thermionic emission limit in carbon nanotube network film-based field-effect

NASA Astrophysics Data System (ADS)

Zhao, Chenyi; Zhong, Donglai; Qiu, Chenguang; Han, Jie; Zhang, Zhiyong; Peng, Lian-Mao

2018-01-01

In this letter, we explore the vertical scaling-down behavior of carbon nanotube (CNT) network film field-effect transistors (FETs) and show that by using a high-efficiency gate insulator, we can substantially improve the subthreshold swing (SS) and its uniformity. By using an HfO2 layer with a thickness of 7.3 nm as the gate insulator, we fabricated CNT network film FETs with a long channel (>2 μm) that exhibit an SS of approximately 60 mV/dec. The preferred thickness of HfO2 as the gate insulator in a CNT network FET is between 7 nm and 10 nm, simultaneously yielding an excellent SS (<80 mV/decade) and low gate leakage. However, because of the statistical fluctuations of the network CNT channel, the lateral scaling of CNT network film-based FETs is more difficult than that of conventional FETs. Experiments suggest that excellent SS is difficult to achieve statistically in CNT network film FETs with a small channel length (smaller than the mean length of the CNTs), which eventually limits the further scaling down of this kind of CNT FET to the sub-micrometer regime.

Anti-HER2 IgY antibody-functionalized single-walled carbon nanotubes for detection and selective destruction of breast cancer cells

PubMed Central

2009-01-01

Background Nanocarrier-based antibody targeting is a promising modality in therapeutic and diagnostic oncology. Single-walled carbon nanotubes (SWNTs) exhibit two unique optical properties that can be exploited for these applications, strong Raman signal for cancer cell detection and near-infrared (NIR) absorbance for selective photothermal ablation of tumors. In the present study, we constructed a HER2 IgY-SWNT complex and demonstrated its dual functionality for both detection and selective destruction of cancer cells in an in vitro model consisting of HER2-expressing SK-BR-3 cells and HER2-negative MCF-7 cells. Methods The complex was constructed by covalently conjugating carboxylated SWNTs with anti-HER2 chicken IgY antibody, which is more specific and sensitive than mammalian IgGs. Raman signals were recorded on Raman spectrometers with a laser excitation at 785 nm. NIR irradiation was performed using a diode laser system, and cells with or without nanotube treatment were irradiated by 808 nm laser at 5 W/cm2 for 2 min. Cell viability was examined by the calcein AM/ethidium homodimer-1 (EthD-1) staining. Results Using a Raman optical microscope, we found the Raman signal collected at single-cell level from the complex-treated SK-BR-3 cells was significantly greater than that from various control cells. NIR irradiation selectively destroyed the complex-targeted breast cancer cells without harming receptor-free cells. The cell death was effectuated without the need of internalization of SWNTs by the cancer cells, a finding that has not been reported previously. Conclusion We have demonstrated that the HER2 IgY-SWNT complex specifically targeted HER2-expressing SK-BR-3 cells but not receptor-negative MCF-7 cells. The complex can be potentially used for both detection and selective photothermal ablation of receptor-positive breast cancer cells without the need of internalization by the cells. Thus, the unique intrinsic properties of SWNTs combined with high

Anti-HER2 IgY antibody-functionalized single-walled carbon nanotubes for detection and selective destruction of breast cancer cells.

PubMed

Xiao, Yan; Gao, Xiugong; Taratula, Oleh; Treado, Stephen; Urbas, Aaron; Holbrook, R David; Cavicchi, Richard E; Avedisian, C Thomas; Mitra, Somenath; Savla, Ronak; Wagner, Paul D; Srivastava, Sudhir; He, Huixin

2009-10-02

Nanocarrier-based antibody targeting is a promising modality in therapeutic and diagnostic oncology. Single-walled carbon nanotubes (SWNTs) exhibit two unique optical properties that can be exploited for these applications, strong Raman signal for cancer cell detection and near-infrared (NIR) absorbance for selective photothermal ablation of tumors. In the present study, we constructed a HER2 IgY-SWNT complex and demonstrated its dual functionality for both detection and selective destruction of cancer cells in an in vitro model consisting of HER2-expressing SK-BR-3 cells and HER2-negative MCF-7 cells. The complex was constructed by covalently conjugating carboxylated SWNTs with anti-HER2 chicken IgY antibody, which is more specific and sensitive than mammalian IgGs. Raman signals were recorded on Raman spectrometers with a laser excitation at 785 nm. NIR irradiation was performed using a diode laser system, and cells with or without nanotube treatment were irradiated by 808 nm laser at 5 W/cm2 for 2 min. Cell viability was examined by the calcein AM/ethidium homodimer-1 (EthD-1) staining. Using a Raman optical microscope, we found the Raman signal collected at single-cell level from the complex-treated SK-BR-3 cells was significantly greater than that from various control cells. NIR irradiation selectively destroyed the complex-targeted breast cancer cells without harming receptor-free cells. The cell death was effectuated without the need of internalization of SWNTs by the cancer cells, a finding that has not been reported previously. We have demonstrated that the HER2 IgY-SWNT complex specifically targeted HER2-expressing SK-BR-3 cells but not receptor-negative MCF-7 cells. The complex can be potentially used for both detection and selective photothermal ablation of receptor-positive breast cancer cells without the need of internalization by the cells. Thus, the unique intrinsic properties of SWNTs combined with high specificity and sensitivity of IgY antibodies

Could Nano-Structured Materials Enable the Improved Pressure Vessels for Deep Atmospheric Probes?

NASA Technical Reports Server (NTRS)

Srivastava, D.; Fuentes, A.; Bienstock, B.; Arnold, J. O.

2005-01-01

A viewgraph presentation on the use of Nano-Structured Materials to enable pressure vessel structures for deep atmospheric probes is shown. The topics include: 1) High Temperature/Pressure in Key X-Environments; 2) The Case for Use of Nano-Structured Materials Pressure Vessel Design; 3) Carbon based Nanomaterials; 4) Nanotube production & purification; 5) Nanomechanics of Carbon Nanotubes; 6) CNT-composites: Example (Polymer); 7) Effect of Loading sequence on Composite with 8% by volume; 8) Models for Particulate Reinforced Composites; 9) Fullerene/Ti Composite for High Strength-Insulating Layer; 10) Fullerene/Epoxy Composite for High Strength-Insulating Layer; 11) Models for Continuous Fiber Reinforced Composites; 12) Tensile Strength for Discontinuous Fiber Composite; 13) Ti + SWNT Composites: Thermal/Mechanical; 14) Ti + SWNT Composites: Tensile Strength; and 15) Nano-structured Shell for Pressure Vessels.

Carbon Nanotubes: On the Origin of Helicity

NASA Astrophysics Data System (ADS)

Harutyunyan, Avetik

2015-03-01

The mechanism of helicity formation of carbon nanotubes still remains elusive that hinders their applications. Current explanations mainly rely on the planar interrelationship between the structure of nanotube and corresponding facet of catalyst in 2D geometry that could amend the structure of grown carbon layer, specifically due to the epitaxial interaction. Yet, the structure of carbon nanotube and circumference of the rims assume involvement of more than one facet i.e. it is 3D problem. By aiming this problem we find that the nanotube nucleation is initiated by cap formation via evolving of graphene embryo across the adjacent facets of catalyst particle. As a result the graphene embryos incorporate in their hexagonic network various polygons to accommodate the curved 3D geometry that initiates cap formation following by elongation of the circumferential rims. Based on these results, also on the census of nanotube caps and the fact that given cap fit only one nanotube wall, we consider carbon cap responsible for the helicity of carbon nanotube. This understanding could provide new avenues towards engineering particles to explicitly accommodate certain helicities via exploitation of the angular distribution of catalyst adjacent facets. Our recent progresses in production of carbon nanotubes, nanotube reinforced composites and their potential applications also will be presented.

Effects of single-walled carbon nanotubes on lysozyme gelation.

PubMed

Tardani, Franco; La Mesa, Camillo

2014-09-01

The possibility to disperse carbon nanotubes in biocompatible matrices has got substantial interest from the scientific community. Along this research line, the inclusion of single walled carbon nanotubes in lysozyme-based hydrogels was investigated. Experiments were performed at different nanotube/lysozyme weight ratios. Carbon nanotubes were dispersed in protein solutions, in conditions suitable for thermal gelation. The state of the dispersions was determined before and after thermal treatment. Rheology, dynamic light scattering and different microscopies investigated the effect that carbon nanotubes exert on gelation. The gelation kinetics and changes in gelation temperature were determined. The effect of carbon and lysozyme content on the gel properties was, therefore, determined. At fixed lysozyme content, moderate amounts of carbon nanotubes do not disturb the properties of hydrogel composites. At moderately high volume fractions in carbon nanotubes, the gels become continuous in both lysozyme and nanotubes. This is because percolating networks are presumably formed. Support to the above statements comes by rheology. Copyright © 2014 Elsevier B.V. All rights reserved.

Electromagnetically Tunable Fluids

DTIC Science & Technology

2011-11-29

Carbon Nanotube (SWNT)-Polyimide Nanocomposites as Electrostrictive Materials”, Sensors and Actuators A: Physical, 155, pp. 246-252, 2009. [6] G. H...12] S. L. Eichmann, B. Smith, G. Meric, D. H. Fairbrother, and M. A. Bevan, “Imaging carbon nanotube interactions, diffusion, and stability in...Toward the Preparation of Nanocomposites with Oriented Fillers: Electric Field-Manipulation of Cellulose Whisker in Silicone Oil’, Smart Materials

Integrated fast assembly of free-standing lithium titanate/carbon nanotube/cellulose nanofiber hybrid network film as flexible paper-electrode for lithium-ion batteries.

PubMed

Cao, Shaomei; Feng, Xin; Song, Yuanyuan; Xue, Xin; Liu, Hongjiang; Miao, Miao; Fang, Jianhui; Shi, Liyi

2015-05-27

A free-standing lithium titanate (Li4Ti5O12)/carbon nanotube/cellulose nanofiber hybrid network film is successfully assembled by using a pressure-controlled aqueous extrusion process, which is highly efficient and easily to scale up from the perspective of disposable and recyclable device production. This hybrid network film used as a lithium-ion battery (LIB) electrode has a dual-layer structure consisting of Li4Ti5O12/carbon nanotube/cellulose nanofiber composites (hereinafter referred to as LTO/CNT/CNF), and carbon nanotube/cellulose nanofiber composites (hereinafter referred to as CNT/CNF). In the heterogeneous fibrous network of the hybrid film, CNF serves simultaneously as building skeleton and a biosourced binder, which substitutes traditional toxic solvents and synthetic polymer binders. Of importance here is that the CNT/CNF layer is used as a lightweight current collector to replace traditional heavy metal foils, which therefore reduces the total mass of the electrode while keeping the same areal loading of active materials. The free-standing network film with high flexibility is easy to handle, and has extremely good conductivity, up to 15.0 S cm(-1). The flexible paper-electrode for LIBs shows very good high rate cycling performance, and the specific charge/discharge capacity values are up to 142 mAh g(-1) even at a current rate of 10 C. On the basis of the mild condition and fast assembly process, a CNF template fulfills multiple functions in the fabrication of paper-electrode for LIBs, which would offer an ever increasing potential for high energy density, low cost, and environmentally friendly flexible electronics.

Impregnation of Catalytic Metals in Single-Walled Carbon Nanotubes for Toxic Gas Conversion in Life Support System

NASA Technical Reports Server (NTRS)

Li, Jing; Wignarajah, Kanapathipillai; Cinke, Marty; Partridge, Harry; Fisher, John

2004-01-01

Carbon nanotubes (CNTs) possess extraordinary properties such as high surface area, ordered chemical structure that allows functionalization, larger pore volume, and very narrow pore size distribution that have attracted considerable research attention from around the world since their discovery in 1991. The development and characterization of an original and innovative approach for the control and elimination of gaseous toxins using single walled carbon nanotubes (SWNTs) promise superior performance over conventional approaches due to the ability to direct the selective uptake of gaseous species based on their controlled pore size, increased adsorptive capacity due to their increased surface area and the effectiveness of carbon nanotubes as catalyst supports for gaseous conversion. We present our recent investigation of using SWNTs as catalytic supporting materials to impregnate metals, such as rhodium (Rh), palladium (Pd) and other catalysts. A protocol has been developed to oxidize the SWNTs first and then impregnate the Rh in aqueous rhodium chloride solution, according to unique surface properties of SWNTs. The Rh has been successfully impregnated in SWNTs. The Rh-SWNTs have been characterized by various techniques, such as TGA, XPS, TEM, and FTIR. The project is funded by a NASA Research Announcement Grant to find applications of single walled nanocarbons in eliminating toxic gas Contaminant in life support system. This knowledge will be utilized in the development of a prototype SWNT KO, gas purification system that would represent a significant step in the development of high efficiency systems capable of selectively removing specific gaseous for use in regenerative life support system for human exploration missions.

Effects of carbonyl bond, metal cluster dissociation, and evaporation rates on predictions of nanotube production in high-pressure carbon monoxide

NASA Technical Reports Server (NTRS)

Scott, Carl D.; Smalley, Richard E.

2003-01-01

The high-pressure carbon monoxide (HiPco) process for producing single-wall carbon nanotubes (SWNTs) uses iron pentacarbonyl as the source of iron for catalyzing the Boudouard reaction. Attempts using nickel tetracarbonyl led to no production of SWNTs. This paper discusses simulations at a constant condition of 1300 K and 30 atm in which the chemical rate equations are solved for different reaction schemes. A lumped cluster model is developed to limit the number of species in the models, yet it includes fairly large clusters. Reaction rate coefficients in these schemes are based on bond energies of iron and nickel species and on estimates of chemical rates for formation of SWNTs. SWNT growth is measured by the conformation of CO2. It is shown that the production of CO2 is significantly greater for FeCO because of its lower bond energy as compared with that of NiCO. It is also shown that the dissociation and evaporation rates of atoms from small metal clusters have a significant effect on CO2 production. A high rate of evaporation leads to a smaller number of metal clusters available to catalyze the Boudouard reaction. This suggests that if CO reacts with metal clusters and removes atoms from them by forming MeCO, this has the effect of enhancing the evaporation rate and reducing SWNT production. The study also investigates some other reactions in the model that have a less dramatic influence.

Flexible symmetric supercapacitors based on vertical TiO2 and carbon nanotubes

NASA Astrophysics Data System (ADS)

Chien, C. J.; Chang, Pai-Chun; Lu, Jia G.

2010-03-01

Highly conducting and porous carbon nanotubes are widely used as electrodes in double-layer-effect supercapacitors. In this presentation, vertical TiO2 nanotube array is fabricated by anodization process and used as supercapacitor electrode utilizing its compact density, high surface area and porous structure. By spin coating carbon nanotube networks on vertical TiO2 nanotube array as electrodes with 1M H2SO4 electrolyte in between, the specific capacitance can be enhanced by 30% compared to using pure carbon nanotube network alone because of the combination of double layer effect and redox reaction from metal oxide materials. Based on cyclic voltammetry and galvanostatic charge-discharge measurements, this type of hybrid electrode has proven to be suitable for high performance supercapacitor application and maintain desirable cycling stability. The electrochemical impedance spectroscopy technique shows that the electrode has good electrical conductivity. Furthermore, we will discuss the prospect of extending this energy storage approach in flexible electronics.

Modeling Heterogeneous Carbon Nanotube Networks for Photovoltaic Applications Using Silvaco Atlas Software

DTIC Science & Technology

2012-06-01

Nanotube MWCNT Multi-Walled Carbon Nanotube PET Polyethylene Terephthalate 4H-SiC 4-H Silicon Carbide AlGaAs Aluminum Gallium Arsenide...nanotubes ( MWCNTs ). SWCNTs are structured with one layer of graphene rolled into a CNT. MWCNTs are contrastingly composed of 23 multiple layers...simulation 19 times to extract cell parameters at #varying widths set cellWidth=200 loop steps=19 go atlas #Constants which are used to set the

Carbon nanotube active-matrix backplanes for conformal electronics and sensors.

PubMed

Takahashi, Toshitake; Takei, Kuniharu; Gillies, Andrew G; Fearing, Ronald S; Javey, Ali

2011-12-14

In this paper, we report a promising approach for fabricating large-scale flexible and stretchable electronics using a semiconductor-enriched carbon nanotube solution. Uniform semiconducting nanotube networks with superb electrical properties (mobility of ∼20 cm2 V(-1) s(-1) and ION/IOFF of ∼10(4)) are obtained on polyimide substrates. The substrate is made stretchable by laser cutting a honeycomb mesh structure, which combined with nanotube-network transistors enables highly robust conformal electronic devices with minimal device-to-device stochastic variations. The utility of this device concept is demonstrated by fabricating an active-matrix backplane (12×8 pixels, physical size of 6×4 cm2) for pressure mapping using a pressure sensitive rubber as the sensor element.

Preferential destruction of metallic single-walled carbon nanotubes by laser irradiation.

PubMed

Huang, Houjin; Maruyama, Ryuichiro; Noda, Kazuhiro; Kajiura, Hisashi; Kadono, Koji

2006-04-13

Upon laser irradiation in air, metallic single-walled carbon nanotubes (SWNTs) in carbon nanotube thin film can be destroyed in preference to their semiconducting counterparts when the wavelength and power intensity of the irradiation are appropriate and the carbon nanotubes are not heavily bundled. Our method takes advantage of these two species' different rates of photolysis-assisted oxidation, creating the possibility of defining the semiconducting portions of carbon nanotube (CNT) networks using optical lithography, particularly when constructing all-CNT FETs (without metal electrodes) in the future.

Higher Order Chemistry Models in the CFD Simulation of Laser-Ablated Carbon Plumes

NASA Technical Reports Server (NTRS)

Greendyke, R. B.; Creel, J. R.; Payne, B. T.; Scott, C. D.

2005-01-01

Production of single-walled carbon nanotubes (SWNT) has taken place for a number of years and by a variety of methods such as laser ablation, chemical vapor deposition, and arc-jet ablation. Yet, little is actually understood about the exact chemical kinetics and processes that occur in SWNT formation. In recent time, NASA Johnson Space Center has devoted a considerable effort to the experimental evaluation of the laser ablation production process for SWNT originally developed at Rice University. To fully understand the nature of the laser ablation process it is necessary to understand the development of the carbon plume dynamics within the laser ablation oven. The present work is a continuation of previous studies into the efforts to model plume dynamics using computational fluid dynamics (CFD). The ultimate goal of the work is to improve understanding of the laser ablation process, and through that improved understanding, refine the laser ablation production of SWNT.

Growth of micro-crystals in solution by in-situ heating via continuous wave infrared laser light and an absorber

NASA Astrophysics Data System (ADS)

Pathak, Shashank; Dharmadhikari, Jayashree A.; Thamizhavel, A.; Mathur, Deepak; Dharmadhikari, Aditya K.

2016-01-01

We report on growth of micro-crystals such as sodium chloride (NaCl), copper sulphate (CuSO4), potassium di-hydrogen phosphate (KDP) and glycine (NH2CH2COOH) in solution by in-situ heating using continuous wave Nd:YVO4 laser light. Crystals are grown by adding single walled carbon nanotubes (SWNT). The SWNTs absorb 1064 nm light and act as an in-situ heat source that vaporizes the solvent producing microcrystals. The temporal dynamics of micro-crystal growth is investigated by varying experimental parameters such as SWNT bundle size and incident laser power. We also report crystal growth without SWNT in an absorbing medium: copper sulphate in water. Even though the growth dynamics with SWNT and copper sulphate are significantly different, our results indicate that bubble formation is necessary for nucleation. Our simple method may open up new vistas for rapid growth of seed crystals especially for examining the crystallizability of inorganic and organic materials.

Accelerated reliability testing of highly aligned single-walled carbon nanotube networks subjected to DC electrical stressing.

PubMed

Strus, Mark C; Chiaramonti, Ann N; Kim, Young Lae; Jung, Yung Joon; Keller, Robert R

2011-07-01

We investigate the electrical reliability of nanoscale lines of highly aligned, networked, metallic/semiconducting single-walled carbon nanotubes (SWCNTs) fabricated through a template-based fluidic assembly process. We find that these SWCNT networks can withstand DC current densities larger than 10 MA cm(-2) for several hours and, in some cases, several days. We develop test methods that show that the degradation rate, failure predictability and total device lifetime can be linked to the initial resistance. Scanning electron and transmission electron microscopy suggest that fabrication variability plays a critical role in the rate of degradation, and we offer an empirical method of quickly determining the long-term performance of a network. We find that well-fabricated lines subject to constant electrical stress show a linear accumulation of damage reminiscent of electromigration in metallic interconnects, and we explore the underlying physical mechanisms that could cause such behavior.

Synthesis of carbon nanotubes using green plant extract as catalyst: unconventional concept and its realization

NASA Astrophysics Data System (ADS)

Tripathi, Nishant; Pavelyev, Vladimir; Islam, S. S.

2017-11-01

Green catalyst derived from plants, a cheap and abundant natural source, is used for the synthesis of multi-walled carbon nanotubes (MWNTs). The concept is unconventional and practically realized into existence by simple CVD growth while keeping away the potential hazards caused by metal catalyst on environment and living organisms. The notable points to mention of such growth are: (1) grown CNTs are free from toxic metal catalyst, (2) low growth temperature (575 °C) required and produced high yield vis-à-vis any other catalyst used so far reported, and (3) no need of expensive and complex systems for its synthesis. Besides, growth of SWNT as well as carbon nano-belts with hollow rectangular cross-section is observed when growth temperature increased to 800 °C, specifically, for the wall-nut extract. The samples were characterized by microscopic and spectroscopic analysis and the results verified our study. The present work provides innovative technique and may open up new avenues for CNTs synthesis and its applications.

Ultrasensitive Detection of Single-Walled Carbon Nanotubes Using Surface Plasmon Resonance.

PubMed

Jang, Daeho; Na, Wonhwi; Kang, Minwook; Kim, Namjoon; Shin, Sehyun

2016-01-05

Because single-walled carbon nanotubes (SWNTs) are known to be a potentially dangerous material, inducing cancers and other diseases, any possible leakage of SWNTs through an aquatic medium such as drinking water will result in a major public threat. To solve this problem, for the present study, a highly sensitive, quantitative detection method of SWNTs in an aqueous solution was developed using surface plasmon resonance (SPR) spectroscopy. For a highly sensitive and specific detection, a strong affinity conjugation with biotin-streptavidin was adopted on an SPR sensing mechanism. During the pretreatment process, the SWNT surface was functionalized and hydrophilized using a thymine-chain based biotinylated single-strand DNA linker (B-ssDNA) and bovine serum albumin (BSA). The pretreated SWNTs were captured on a sensing film, the surface of which was immobilized with streptavidin on biotinylated gold film. The captured SWNTs were measured in real-time using SPR spectroscopy. Specific binding with SWNTs was verified through several validation experiments. The present method using an SPR sensor is capable of detecting SWNTs of as low as 100 fg/mL, which is the lowest level reported thus far for carbon-nanotube detection. In addition, the SPR sensor showed a linear characteristic within the range of 100 pg/mL to 200 ng/mL. These findings imply that the present SPR sensing method can detect an extremely low level of SWNTs in an aquatic environment with high sensitivity and high specificity, and thus any potential leakage of SWNTs into an aquatic environment can be precisely monitored within a couple of hours.

Impact of single walled carbon nanotubes (SWNTs) on wastewater microbial communities

NASA Astrophysics Data System (ADS)

Goyal, Deepankar

Aim: Carbon nanotubes (CNTs) hold great promise in advancing our future, with potential applications such as adsorbents, conductive composites, energy storage devices, and more. Despite of numerous potential applications of CNTs, almost nothing so far is known about how such carbon-based nanomaterials would in future impact environmental processes such as wastewater treatment. The objective of the current study was to evaluate the impact of single-walled carbon nanotubes (SWNTs) on microbial communities and wastewater treatment processes in activated sludge bioreactors. Method: Closed system batch-scale reactors were used to simulate the activated sludge process. Two sets of triplicate reactors were analyzed to determine the effects of SWNTs and associated impurities compared to control reactors that contained no CNTs. Sub-samples for microbial community analyses were aseptically removed periodically from the bioreactors every ˜1 hour 15 minutes and held at -80°C until analyzed. Genomic DNA was extracted from bioreactor samples, and molecular profiles of the bacterial communities were determined using automated ribosomal intergenic spacer analysis (ARISA). The clones for the ARISA profiles having distinct ARISA peaks were picked and sequenced. Result: ARISA profiles revealed adverse changes in CNT-exposed bacterial communities compared to control reactors associated with CNTs. The phylogenetic analysis of cloned insert containing Internal Transcribed Spacer (ITS) region plus the 16S rRNA genes identified them belonging to taxonomic groups of the families Sphingomonadaceae and Cytophagacaceae , and the genus Zoogloea. Changes in community structure were observed in both SWNT-exposed and control reactors over the experimental time period. Also the date on which activated sludge was obtained from a wastewater treatment plant facility seemed to play a critical role in changing the community structure altogether, indicating the importance of analyzing microbial

Intercellular nanotubes: insights from imaging studies and beyond

PubMed Central

Hurtig, Johan; Chiu, Daniel T.; Önfelt, Björn

2017-01-01

Cell-cell communication is critical to the development, maintenance, and function of multicellular organisms. Classical mechanisms for intercellular communication include secretion of molecules into the extracellular space and transport of small molecules through gap junctions. Recent reports suggest that cells also can communicate over long distances via a network of transient intercellular nanotubes. Such nanotubes have been shown to mediate intercellular transfer of organelles as well as membrane components and cytoplasmic molecules. Moreover, intercellular nanotubes have been observed in vivo and have been shown to enhance the transmission of pathogens such as human immunodeficiency virus (HIV)-1 and prions in vitro. These studies indicate that intercellular nanotubes may play a role both in normal physiology and in disease. PMID:20166114

3D reconstruction of carbon nanotube networks from neutron scattering experiments

DOE PAGES

Mahdavi, Mostafa; Baniassadi, Majid; Baghani, Mostafa; ...

2015-09-03

Structure reconstruction from statistical descriptors, such as scattering data obtained using x-rays or neutrons, is essential in understanding various properties of nanocomposites. Scattering based reconstruction can provide a realistic model, over various length scales, that can be used for numerical simulations. In this study, 3D reconstruction of a highly loaded carbon nanotube (CNT)-conducting polymer system based on small and ultra-small angle neutron scattering (SANS and USANS, respectively) data was performed. These light-weight and flexible materials have recently shown great promise for high-performance thermoelectric energy conversion, and their further improvement requires a thorough understanding of their structure-property relationships. The first stepmore » in achieving such understanding is to generate models that contain the hierarchy of CNT networks over nano and micron scales. The studied system is a single walled carbon nanotube (SWCNT)/poly (3,4-ethylenedioxythiophene): poly (styrene sulfonate) (PEDOT: PSS). SANS and USANS patterns of the different samples containing 10, 30, and 50 wt% SWCNTs were measured. These curves were then utilized to calculate statistical two-point correlation functions of the nanostructure. These functions along with the geometrical information extracted from SANS data and scanning electron microscopy images were used to reconstruct a representative volume element (RVE) nanostructure. Generated RVEs can be used for simulations of various mechanical and physical properties. This work, therefore, introduces a framework for the reconstruction of 3D RVEs of high volume faction nanocomposites containing high aspect ratio fillers from scattering experiments.« less

3D reconstruction of carbon nanotube networks from neutron scattering experiments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mahdavi, Mostafa; Baniassadi, Majid; Baghani, Mostafa

Structure reconstruction from statistical descriptors, such as scattering data obtained using x-rays or neutrons, is essential in understanding various properties of nanocomposites. Scattering based reconstruction can provide a realistic model, over various length scales, that can be used for numerical simulations. In this study, 3D reconstruction of a highly loaded carbon nanotube (CNT)-conducting polymer system based on small and ultra-small angle neutron scattering (SANS and USANS, respectively) data was performed. These light-weight and flexible materials have recently shown great promise for high-performance thermoelectric energy conversion, and their further improvement requires a thorough understanding of their structure-property relationships. The first stepmore » in achieving such understanding is to generate models that contain the hierarchy of CNT networks over nano and micron scales. The studied system is a single walled carbon nanotube (SWCNT)/poly (3,4-ethylenedioxythiophene): poly (styrene sulfonate) (PEDOT: PSS). SANS and USANS patterns of the different samples containing 10, 30, and 50 wt% SWCNTs were measured. These curves were then utilized to calculate statistical two-point correlation functions of the nanostructure. These functions along with the geometrical information extracted from SANS data and scanning electron microscopy images were used to reconstruct a representative volume element (RVE) nanostructure. Generated RVEs can be used for simulations of various mechanical and physical properties. This work, therefore, introduces a framework for the reconstruction of 3D RVEs of high volume faction nanocomposites containing high aspect ratio fillers from scattering experiments.« less

A Signature of Spatial Correlations between rare earth ions and single-wall nanotubes wrapped with DNA in their mixed solution

NASA Astrophysics Data System (ADS)

Ignatova, Tetyana; Rotkin, Slava V.

2012-02-01

We propose that the fluorescence resonance energy transfer (FRET) between the rare earth ions (REI) and single-wall nanotubes (SWNT) can be used to measure their Coulomb correlation in solution. As a calibration experiment the FRET between two different REIs, being the energy donor and the acceptor, in their mixed solution has been used. From the photoluminescence decay time we were able to extract the characteristic distance between unlike REIs. Our study revealed negative correlation (the repulsion) for Tb-Eu solution. In the case of the solution containing the REI and the SWNTs wrapped with DNA we observed a significant positive correlation (the attraction and the complex formation). The data is in a good agreement with the theoretical estimates and allows to propose REIs and their FRET as a sensitive tool for detecting kinetics of interaction of SWNTs in aqueous solutions.

M13 phage-functionalized single-walled carbon nanotubes as nanoprobes for second near-infrared window fluorescence imaging of targeted tumors.

PubMed

Yi, Hyunjung; Ghosh, Debadyuti; Ham, Moon-Ho; Qi, Jifa; Barone, Paul W; Strano, Michael S; Belcher, Angela M

2012-03-14

Second near-infrared (NIR) window light (950-1400 nm) is attractive for in vivo fluorescence imaging due to its deep penetration depth in tissues and low tissue autofluorescence. Here we show genetically engineered multifunctional M13 phage can assemble fluorescent single-walled carbon nanotubes (SWNTs) and ligands for targeted fluorescence imaging of tumors. M13-SWNT probe is detectable in deep tissues even at a low dosage of 2 μg/mL and up to 2.5 cm in tissue-like phantoms. Moreover, targeted probes show specific and up to 4-fold improved uptake in prostate specific membrane antigen positive prostate tumors compared to control nontargeted probes. This M13 phage-based second NIR window fluorescence imaging probe has great potential for specific detection and therapy monitoring of hard-to-detect areas. © 2012 American Chemical Society

M13 phage-functionalized single-walled carbon nanotubes as nanoprobes for second near-infrared window fluorescence imaging of targeted tumors

PubMed Central

HAM, MOON-HO; QI, JIFA; BARONE, PAUL W.; STRANO, MICHAEL S.; BELCHER, ANGELA M.

2014-01-01

Second near-infrared (NIR) window light (950-1,400 nm) is attractive for in vivo fluorescence imaging due to its deep penetration depth in tissues and low tissue autofluorescence. Here we show genetically engineered multifunctional M13 phage can assemble fluorescent single-walled carbon nanotubes (SWNTs) and ligands for targeted fluorescence imaging of tumors. M13-SWNT probe is detectable in deep tissues even at a low dosage of 2 μg/mL and up to 2.5 cm in tissue-like phantoms. Moreover, targeted probes show specific and up to four-fold improved uptake in prostate specific membrane antigen positive prostate tumors compared to control non-targeted probes. This M13 phage-based second NIR window fluorescence imaging probe has great potential for specific detection and therapy monitoring of hard-to-detect areas. PMID:22268625

Penicillin biosensor based on a capacitive field-effect structure functionalized with a dendrimer/carbon nanotube multilayer.

PubMed

Siqueira, José R; Abouzar, Maryam H; Poghossian, Arshak; Zucolotto, Valtencir; Oliveira, Osvaldo N; Schöning, Michael J

2009-10-15

Silicon-based sensors incorporating biomolecules are advantageous for processing and possible biological recognition in a small, reliable and rugged manufactured device. In this study, we report on the functionalization of field-effect (bio-)chemical sensors with layer-by-layer (LbL) films containing single-walled carbon nanotubes (SWNTs) and polyamidoamine (PAMAM) dendrimers. A capacitive electrolyte-insulator-semiconductor (EIS) structure modified with carbon nanotubes (EIS-NT) was built, which could be used as a penicillin biosensor. From atomic force microscopy (AFM) and field-emission scanning electron microscopy (FESEM) images, the LbL films were shown to be highly porous due to interpenetration of SWNTs into the dendrimer layers. Capacitance-voltage (C/V) measurements pointed to a high pH sensitivity of ca. 55 mV/pH for the EIS-NT structures. The biosensing ability towards penicillin of an EIS-NT-penicillinase biosensor was also observed as the flat-band voltage shifted to lower potentials at different penicillin concentrations. A dynamic response of penicillin concentrations, ranging from 5.0 microM to 25 mM, was evaluated for an EIS-NT with the penicillinase enzyme immobilized onto the surfaces, via constant-capacitance (ConCap) measurements, achieving a sensitivity of ca. 116 mV/decade. The presence of the nanostructured PAMAM/SWNT LbL film led to sensors with higher sensitivity and better performance.

Corona Phase Molecular Recognition (CoPhMoRe) to Enable New Nanosensor Interfaces

NASA Astrophysics Data System (ADS)

Strano, Michael

2015-03-01

Our lab at MIT has been interested in how the 1D and 2D electronic structures of carbon nanotubes and graphene respectively can be utilized to advance new concepts in molecular detection. We introduce CoPhMoRe or corona phase molecular recognition as a method of discovering synthetic antibodies, or nanotube-templated recognition sites from a heteropolymer library. We show that certain synthetic heteropolymers, once constrained onto a single-walled carbon nanotube by chemical adsorption, also form a new corona phase that exhibits highly selective recognition for specific molecules. To prove the generality of this phenomenon, we report three examples of heteropolymers-nanotube recognition complexes for riboflavin, L-thyroxine and estradiol. The platform opens new opportunities to create synthetic recognition sites for molecular detection. We have also extended this molecular recognition technique to neurotransmitters, producing the first fluorescent sensor for dopamine. Another area of advancement in biosensor development is the use of near infrared fluorescent carbon nanotube sensors for in-vivo detection. Here, we show that PEG-ligated d(AAAT)7 DNA wrapped SWNT are selective for nitric oxide, a vasodilator of blood vessels, and can be tail vein injected into mice and localized within the viable mouse liver. We use an SJL mouse model to study liver inflammation in vivo using the spatially and spectrally resolved nIR signature of the localized SWNT sensors.

Fully integrated carbon nanotube composite thin film strain sensors on flexible substrates for structural health monitoring

NASA Astrophysics Data System (ADS)

Burton, A. R.; Lynch, J. P.; Kurata, M.; Law, K. H.

2017-09-01

Multifunctional thin film materials have opened many opportunities for novel sensing strategies for structural health monitoring. While past work has established methods of optimizing multifunctional materials to exhibit sensing properties, comparatively less work has focused on their integration into fully functional sensing systems capable of being deployed in the field. This study focuses on the advancement of a scalable fabrication process for the integration of multifunctional thin films into a fully integrated sensing system. This is achieved through the development of an optimized fabrication process that can create a broad range of sensing systems using multifunctional materials. A layer-by-layer deposited multifunctional composite consisting of single walled carbon nanotubes (SWNT) in a polyvinyl alcohol and polysodium-4-styrene sulfonate matrix are incorporated with a lithography process to produce a fully integrated sensing system deposited on a flexible substrate. To illustrate the process, a strain sensing platform consisting of a patterned SWNT-composite thin film as a strain-sensitive element within an amplified Wheatstone bridge sensing circuit is presented. Strain sensing is selected because it presents many of the design and processing challenges that are core to patterning multifunctional thin film materials into sensing systems. Strain sensors fabricated on a flexible polyimide substrate are experimentally tested under cyclic loading using standard four-point bending coupons and a partial-scale steel frame assembly under lateral loading. The study reveals the material process is highly repeatable to produce fully integrated strain sensors with linearity and sensitivity exceeding 0.99 and 5 {{V}}/{ε }, respectively. The thin film strain sensors are robust and are capable of high strain measurements beyond 3000 μ {ε }.

Determining Methane Leak Locations and Rates with a Wireless Network Composed of Low-Cost, Printed Sensors

NASA Astrophysics Data System (ADS)

Smith, C. J.; Kim, B.; Zhang, Y.; Ng, T. N.; Beck, V.; Ganguli, A.; Saha, B.; Daniel, G.; Lee, J.; Whiting, G.; Meyyappan, M.; Schwartz, D. E.

2015-12-01

We will present our progress on the development of a wireless sensor network that will determine the source and rate of detected methane leaks. The targeted leak detection threshold is 2 g/min with a rate estimation error of 20% and localization error of 1 m within an outdoor area of 100 m2. The network itself is composed of low-cost, high-performance sensor nodes based on printed nanomaterials with expected sensitivity below 1 ppmv methane. High sensitivity to methane is achieved by modifying high surface-area-to-volume-ratio single-walled carbon nanotubes (SWNTs) with materials that adsorb methane molecules. Because the modified SWNTs are not perfectly selective to methane, the sensor nodes contain arrays of variously-modified SWNTs to build diversity of response towards gases with adsorption affinity. Methane selectivity is achieved through advanced pattern-matching algorithms of the array's ensemble response. The system is low power and designed to operate for a year on a single small battery. The SWNT sensing elements consume only microwatts. The largest power consumer is the wireless communication, which provides robust, real-time measurement data. Methane leak localization and rate estimation will be performed by machine-learning algorithms built with the aid of computational fluid dynamics simulations of gas plume formation. This sensor system can be broadly applied at gas wells, distribution systems, refineries, and other downstream facilities. It also can be utilized for industrial and residential safety applications, and adapted to other gases and gas combinations.

Graphene--nanotube--iron hierarchical nanostructure as lithium ion battery anode.

PubMed

Lee, Si-Hwa; Sridhar, Vadahanambi; Jung, Jung-Hwan; Karthikeyan, Kaliyappan; Lee, Yun-Sung; Mukherjee, Rahul; Koratkar, Nikhil; Oh, Il-Kwon

2013-05-28

In this study, we report a novel route via microwave irradiation to synthesize a bio-inspired hierarchical graphene--nanotube--iron three-dimensional nanostructure as an anode material in lithium-ion batteries. The nanostructure comprises vertically aligned carbon nanotubes grown directly on graphene sheets along with shorter branches of carbon nanotubes stemming out from both the graphene sheets and the vertically aligned carbon nanotubes. This bio-inspired hierarchical structure provides a three-dimensional conductive network for efficient charge-transfer and prevents the agglomeration and restacking of the graphene sheets enabling Li-ions to have greater access to the electrode material. In addition, functional iron-oxide nanoparticles decorated within the three-dimensional hierarchical structure provides outstanding lithium storage characteristics, resulting in very high specific capacities. The anode material delivers a reversible capacity of ~1024 mA · h · g(-1) even after prolonged cycling along with a Coulombic efficiency in excess of 99%, which reflects the ability of the hierarchical network to prevent agglomeration of the iron-oxide nanoparticles.

Carbon nanotubes in neuroregeneration and repair.

PubMed

Fabbro, Alessandra; Prato, Maurizio; Ballerini, Laura

2013-12-01

In the last decade, we have experienced an increasing interest and an improved understanding of the application of nanotechnology to the nervous system. The aim of such studies is that of developing future strategies for tissue repair to promote functional recovery after brain damage. In this framework, carbon nanotube based technologies are emerging as particularly innovative tools due to the outstanding physical properties of these nanomaterials together with their recently documented ability to interface neuronal circuits, synapses and membranes. This review will discuss the state of the art in carbon nanotube technology applied to the development of devices able to drive nerve tissue repair; we will highlight the most exciting findings addressing the impact of carbon nanotubes in nerve tissue engineering, focusing in particular on neuronal differentiation, growth and network reconstruction. © 2013.

A built-in sensor with carbon nanotubes coated by Ag clusters for deformation monitoring of glass fibre/epoxy composites

NASA Astrophysics Data System (ADS)

Slobodian, P.; Riha, P.; Matyas, J.; Olejnik, R.; Lloret Pertegás, S.; Schledjewski, R.; Kovar, M.

2018-03-01

A multiwalled carbon nanotube network embedded in a polyurethane membrane was integrated into a glass fibre reinforced epoxy composite by means of vacuum infusion to become a part of the composite and has been serving for a strain self-sensing functionality. Besides the pristine nanotubes also nanotubes with Ag nanoparticles attached to their surfaces were used to increase strain sensing. Moreover, the design of the carbon nanotube/polyurethane sensor allowed formation of network micro-sized cracks which increased its reversible electrical resistance resulted in an enhancement of strain sensing. The resistance sensitivity, quantified by a gauge factor, increased more than hundredfold in case of a pre-strained sensor with Ag decorated nanotubes in comparison with the sensor with pristine nanotubes.

Spray-coated single walled carbon nanotubes as source and drain electrodes in SnO thin-film transistors

NASA Astrophysics Data System (ADS)

Ryu, Jae Hyeon; Baek, Geun-Woo; Kim, Seung Yeob; Kwon, Hyuck-In; Jin, Sung Hun

2018-07-01

In this letter, spray-coated single walled carbon nanotubes (SWNTs) as one of alternative electrodes in SnO thin-film transistors are demonstrated for emerging electronic applications. Herein, the device architecture of SnO TFTs with a polymer etch stop layer (SU-8) enables the selective etching of SWNTs in a desired region without the detrimental effects of SnO channel layers. Moreover, SnO TFTs with SWNT electrodes as substitutes successfully demonstrate decent width normalized electrical contact properties (∼1.49 kΩ cm), field effect mobility (∼0.69 cm2 V‑1 s‑1), sub-threshold slope (∼0.4 V dec‑1), and current on–off ratio (I on/I off ∼ 3.5 × 103). Systematic temperature dependency measurements elucidate that SnO channel transports with an activation energy within several tens of meV, together with decent contact resistance as compared to that of conventional Ni electrodes.

Sensitive voltammetric determination of chloramphenicol by using single-wall carbon nanotube-gold nanoparticle-ionic liquid composite film modified glassy carbon electrodes.

PubMed

Xiao, Fei; Zhao, Faqiong; Li, Jiangwen; Yan, Rui; Yu, Jingjing; Zeng, Baizhao

2007-07-16

A novel composite film modified glassy carbon electrode has been fabricated and characterized by scanning electron microscope (SEM) and voltammetry. The composite film comprises of single-wall carbon nanotube (SWNT), gold nanoparticle (GNP) and ionic liquid (i.e. 1-octyl-3-methylimidazolium hexafluorophosphate), thus has the characteristics of them. The resulting electrode shows good stability, high accumulation efficiency and strong promotion to electron transfer. On it, chloramphenicol can produce a sensitive cathodic peak at -0.66 V (versus SCE) in pH 7.0 phosphate buffer solutions. Parameters influencing the voltammetric response of chloramphenicol are optimized, which include the composition of the film and the operation conditions. Under the optimized conditions, the peak current is linear to chloramphenicol concentration in the range of 1.0x10(-8)-6.0x10(-6) M, and the detection limit is estimated to be 5.0x10(-9) M after an accumulation for 150 s on open circuit. The electrode is applied to the determination of chloramphenicol in milk samples, and the recoveries for the standards added are 97.0% and 100.3%. In addition, the electrochemical reaction of chloramphenicol and the effect of single-wall carbon nanotube, gold nanoparticle and ionic liquid are discussed.

Carbon Nanotubes: Molecular Electronic Components

NASA Technical Reports Server (NTRS)

Srivastava, Deepak; Saini, Subhash; Menon, Madhu

1997-01-01

The carbon Nanotube junctions have recently emerged as excellent candidates for use as the building blocks in the formation of nanoscale molecular electronic networks. While the simple joint of two dissimilar tubes can be generated by the introduction of a pair of heptagon-pentagon defects in an otherwise perfect hexagonal graphene sheet, more complex joints require other mechanisms. In this work we explore structural characteristics of complex 3-point junctions of carbon nanotubes using a generalized tight-binding molecular-dynamics scheme. The study of pi-electron local densities of states (LDOS) of these junctions reveal many interesting features, most prominent among them being the defect-induced states in the gap.

Inkjet-Printed Lithium-Sulfur Microcathodes for All-Printed, Integrated Nanomanufacturing.

PubMed

Milroy, Craig A; Jang, Seonpil; Fujimori, Toshihiko; Dodabalapur, Ananth; Manthiram, Arumugam

2017-03-01

Improved thin-film microbatteries are needed to provide appropriate energy-storage options to power the multitude of devices that will bring the proposed "Internet of Things" network to fruition (e.g., active radio-frequency identification tags and microcontrollers for wearable and implantable devices). Although impressive efforts have been made to improve the energy density of 3D microbatteries, they have all used low energy-density lithium-ion chemistries, which present a fundamental barrier to miniaturization. In addition, they require complicated microfabrication processes that hinder cost-competitiveness. Here, inkjet-printed lithium-sulfur (Li-S) cathodes for integrated nanomanufacturing are reported. Single-wall carbon nanotubes infused with electronically conductive straight-chain sulfur (S@SWNT) are adopted as an integrated current-collector/active-material composite, and inkjet printing as a top-down approach to achieve thin-film shape control over printed electrode dimensions is used. The novel Li-S cathodes may be directly printed on traditional microelectronic semicoductor substrates (e.g., SiO 2 ) or on flexible aluminum foil. Profilometry indicates that these microelectrodes are less than 10 µm thick, while cyclic voltammetry analyses show that the S@SWNT possesses pseudocapacitive characteristics and corroborates a previous study suggesting the S@SWNT discharge via a purely solid-state mechanism. The printed electrodes produce ≈800 mAh g -1 S initially and ≈700 mAh g -1 after 100 charge/discharge cycles at C/2 rate. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Subsurface imaging of carbon nanotube networks in polymers with DC-biased multifrequency dynamic atomic force microscopy.

PubMed

Thompson, Hank T; Barroso-Bujans, Fabienne; Herrero, Julio Gomez; Reifenberger, Ron; Raman, Arvind

2013-04-05

The characterization of dispersion and connectivity of carbon nanotube (CNT) networks inside polymers is of great interest in polymer nanocomposites in new material systems, organic photovoltaics, and in electrodes for batteries and supercapacitors. We focus on a technique using amplitude modulation atomic force microscopy (AM-AFM) in the attractive regime of operation, using both single and dual mode excitation, which upon the application of a DC tip bias voltage allows, via the phase channel, the in situ, nanoscale, subsurface imaging of CNT networks dispersed in a polymer matrix at depths of 10-100 nm. We present an in-depth study of the origins of phase contrast in this technique and demonstrate that an electrical energy dissipation mechanism in the Coulomb attractive regime is key to the formation of the phase contrast which maps the spatial variations in the local capacitance and resistance due to the CNT network. We also note that dual frequency excitation can, under some conditions, improve the contrast for such samples. These methods open up the possibility for DC-biased amplitude modulation AFM to be used for mapping the variations in local capacitance and resistance in nanocomposites with conducting networks.

Novel electrode-elastomer combinations for improved performance and application of dielectric elastomers

NASA Astrophysics Data System (ADS)

Yuan, Wei

Dielectric elastomers are the most promising technology for mimicking human muscles in terms of strain, stress, and work density, etc. Actuators have been fabricated based on different design concepts and configurations for applications in robotics, prosthetic devices, medical implants, pumps, and valves. However, to date these actuators have experienced high rates of failure caused by electrical shorting of the compliant electrodes through the elastomer film during electrical breakdown, which has prevented their practical application. In this thesis, single walled carbon nanotube (SWNT) thin films were employed as compliant electrodes for dielectric elastomers to reduce the rate of failure. Thanks to the high aspect ratio of the SWNTs, the electrodes maintain substantial conductance at high biaxial strains. 3M VHB acrylics can be actuated up to 200% area strain with SWNT electrodes, this matches the performance of actuators with carbon grease electrodes. During uni-directional stretching, SWNT electrodes can maintain surface conductivity up to 700% linear strain. SWNT electrodes can experience a self-clearing process under high voltage discharging and electrically isolate the electrodes around the breakdown sites when breakdown events happen. With conventional dielectric elastomer electrode materials such as carbon grease and carbon black, a single breakdown event results in a permanent loss in the actuator's functionality. In contrast, for SWNT electrodes, the SWNTs around the breakdown site will be degraded and become non-conductive. The non-conductive area expands outward until the high voltage discharging stops. As such, the opposing electrodes are prevented from coming into contact with each other and forming an electrical short and the breakdown site is electrically isolated from the remainder of the active area. Despite the existence of the breakdown sites, the dielectric elastomer will resume its functionality and avoid permanent failure. Thus, dielectric

Bolometric-Effect-Based Wavelength-Selective Photodetectors Using Sorted Single Chirality Carbon Nanotubes

PubMed Central

Zhang, Suoming; Cai, Le; Wang, Tongyu; Shi, Rongmei; Miao, Jinshui; Wei, Li; Chen, Yuan; Sepúlveda, Nelson; Wang, Chuan

2015-01-01

This paper exploits the chirality-dependent optical properties of single-wall carbon nanotubes for applications in wavelength-selective photodetectors. We demonstrate that thin-film transistors made with networks of carbon nanotubes work effectively as light sensors under laser illumination. Such photoresponse was attributed to photothermal effect instead of photogenerated carriers and the conclusion is further supported by temperature measurements. Additionally, by using different types of carbon nanotubes, including a single chirality (9,8) nanotube, the devices exhibit wavelength-selective response, which coincides well with the absorption spectra of the corresponding carbon nanotubes. This is one of the first reports of controllable and wavelength-selective bolometric photoresponse in macroscale assemblies of chirality-sorted carbon nanotubes. The results presented here provide a viable route for achieving bolometric-effect-based photodetectors with programmable response spanning from visible to near-infrared by using carbon nanotubes with pre-selected chiralities. PMID:26643777

Low temperature hall effect investigation of conducting polymer-carbon nanotubes composite network.

PubMed

Bahrami, Afarin; Talib, Zainal Abidin; Yunus, Wan Mahmood Mat; Behzad, Kasra; M Abdi, Mahnaz; Din, Fasih Ud

2012-11-14

Polypyrrole (PPy) and polypyrrole-carboxylic functionalized multi wall carbon nanotube composites (PPy/f-MWCNT) were synthesized by in situ chemical oxidative polymerization of pyrrole on the carbon nanotubes (CNTs). The structure of the resulting complex nanotubes was characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The effects of f-MWCNT concentration on the electrical properties of the resulting composites were studied at temperatures between 100 K and 300 K. The Hall mobility and Hall coefficient of PPy and PPy/f-MWCNT composite samples with different concentrations of f-MWCNT were measured using the van der Pauw technique. The mobility decreased slightly with increasing temperature, while the conductivity was dominated by the gradually increasing carrier density.

Self-assembly of hierarchically ordered structures in DNA nanotube systems

NASA Astrophysics Data System (ADS)

Glaser, Martin; Schnauß, Jörg; Tschirner, Teresa; Schmidt, B. U. Sebastian; Moebius-Winkler, Maximilian; Käs, Josef A.; Smith, David M.

2016-05-01

The self-assembly of molecular and macromolecular building blocks into organized patterns is a complex process found in diverse systems over a wide range of size and time scales. The formation of star- or aster-like configurations, for example, is a common characteristic in solutions of polymers or other molecules containing multi-scaled, hierarchical assembly processes. This is a recurring phenomenon in numerous pattern-forming systems ranging from cellular constructs to solutions of ferromagnetic colloids or synthetic plastics. To date, however, it has not been possible to systematically parameterize structural properties of the constituent components in order to study their influence on assembled states. Here, we circumvent this limitation by using DNA nanotubes with programmable mechanical properties as our basic building blocks. A small set of DNA oligonucleotides can be chosen to hybridize into micron-length DNA nanotubes with a well-defined circumference and stiffness. The self-assembly of these nanotubes to hierarchically ordered structures is driven by depletion forces caused by the presence of polyethylene glycol. This trait allowed us to investigate self-assembly effects while maintaining a complete decoupling of density, self-association or bundling strength, and stiffness of the nanotubes. Our findings show diverse ranges of emerging structures including heterogeneous networks, aster-like structures, and densely bundled needle-like structures, which compare to configurations found in many other systems. These show a strong dependence not only on concentration and bundling strength, but also on the underlying mechanical properties of the nanotubes. Similar network architectures to those caused by depletion forces in the low-density regime are obtained when an alternative hybridization-based bundling mechanism is employed to induce self-assembly in an isotropic network of pre-formed DNA nanotubes. This emphasizes the universal effect inevitable

Ultrasensitive detection of lead (II) based on fluorescent aptamer-functionalized carbon nanotubes.

PubMed

Taghdisi, Seyed Mohammad; Emrani, Somayeh Sarreshtehdar; Tabrizian, Kaveh; Ramezani, Mohammad; Abnous, Khalil; Emrani, Ahmad Sarreshtehdar

2014-05-01

Lead contamination is a serious environmental problem with toxic effects in human. Here, we developed a simple and sensitive sensing method employing ATTO 647N/aptamer-SWNT ensemble for detection of Pb(2+). This method is based on the super quenching capability of single-walled carbon nanotubes (SWNTs), high affinity of the aptamer toward Pb(2+) and different propensities of ATTO 647N-aptamer and ATTO 647N-aptamer/Pb(2+) complex for adsorption on SWNTs. In the absence of Pb(2+), the fluorescence of ATTO 647N-aptamer is efficiently quenched by SWNTs. Upon addition of Pb(2+), the aptamer binds to its target, leading to the formation of a G-quadruplex/Pb(2+) complex and does not interact with SWNTs and ATTO 647N-aptamer starts fluorescing. This sensor exhibited a high selectivity toward Pb(2+) and a limit of detection (LOD) as low as 0.42 nM was obtained. Also this sensor could be applied for detection of Pb(2+) ions in tap water and biological sample like serum with high sensitivity. Copyright © 2014 Elsevier B.V. All rights reserved.

Chitosan-functionalised single-walled carbon nanotube-mediated drug delivery of SNX-2112 in cancer cells.

PubMed

Zheng, Lixia; Wu, Shao; Tan, Li; Tan, Huo; Yu, Baodan

2016-09-01

Delivery of amphiphobic drugs (insoluble in both water and oil) has been a great challenge in drug delivery. SNX-2112, a novel inhibitor of Hsp90, is a promising drug candidate for treating various types of cancers; however, the insolubility greatly limits its clinical application. This study aimed to build a new type of drug delivery system using single-walled carbon nanotubes (SWNTs) for controllable release of SNX-2112; chitosan (CHI) was non-covalently added to SWNTs to improve their biocompatibility. SWNTs-CHI demonstrated high drug-loading capability; the release of SNX-2112 was pH triggered and time related. The intracellular reactive oxygen species of SWNTs-CHI increased, compared with that of SWNTs, leading to higher mitogen-activated protein kinase and cell apoptosis. The results of western-blotting, lactate dehydrogenase (LDH) release assay, and cell viability assay analyses indicated that apoptosis-related proteins were abundantly expressed in K562 cells and that the drug delivery system significantly inhibited K562 cells. Thus, SWNT-CHI/SNX-2112 shows great potential as a drug delivery system for cancer therapy. © The Author(s) 2016.

Magnetic nanotubes

DOEpatents

Matsui, Hiroshi; Matsunaga, Tadashi

2010-11-16

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

Synthesis of SWNT/Pt nanocomposites for their effective role in hydrogen storage applications

NASA Astrophysics Data System (ADS)

Sharma, Anshu; Andreas, Rossos; Nehra, S. P.

2018-05-01

Single Wall Carbon Nanotubes (SWNTs) decorated with platinum were synthesized for hydrogen storage applications. Platinum was deposited on the nanotubes using hexachloroplatinic acid (H2PtCl6.6H2O) as a precursor. Commercial SWNTs were also used to compare the results. The obtained SWNTs/Pt nanocomposite was characterized by various techniques such as powder X-ray diffractrometry (XRD), Raman Spectroscopy and Scanning Electron Microscopy (SEM). Furthermore, in the case of SWNTs/Pt, Pt nanoparticles are found to be uniformly dispersed and bound to the SWNTs acting like a single atom catalyst.

Toward the Limits of Uniformity of Mixed Metallicity SWCNT TFT Arrays with Spark-Synthesized and Surface-Density-Controlled Nanotube Networks.

PubMed

Kaskela, Antti; Mustonen, Kimmo; Laiho, Patrik; Ohno, Yutaka; Kauppinen, Esko I

2015-12-30

We report the fabrication of thin film transistors (TFTs) from networks of nonbundled single-walled carbon nanotubes with controlled surface densities. Individual nanotubes were synthesized by using a spark generator-based floating catalyst CVD process. High uniformity and the control of SWCNT surface density were realized by mixing of the SWCNT aerosol in a turbulent flow mixer and monitoring the online number concentration with a condensation particle counter at the reactor outlet in real time. The networks consist of predominantly nonbundled SWCNTs with diameters of 1.0-1.3 nm, mean length of 3.97 μm, and metallic to semiconducting tube ratio of 1:2. The ON/OFF ratio and charge carrier mobility of SWCNT TFTs were simultaneously optimized through fabrication of devices with SWCNT surface densities ranging from 0.36 to 1.8 μm(-2) and channel lengths and widths from 5 to 100 μm and from 100 to 500 μm, respectively. The density optimized TFTs exhibited excellent performance figures with charge carrier mobilities up to 100 cm(2) V(-1) s(-1) and ON/OFF current ratios exceeding 1 × 10(6), combined with high uniformity and more than 99% of devices working as theoretically expected.

Highly sensitive piezo-resistive graphite nanoplatelet-carbon nanotube hybrids/polydimethylsilicone composites with improved conductive network construction.

PubMed

Zhao, Hang; Bai, Jinbo

2015-05-13

The constructions of internal conductive network are dependent on microstructures of conductive fillers, determining various electrical performances of composites. Here, we present the advanced graphite nanoplatelet-carbon nanotube hybrids/polydimethylsilicone (GCHs/PDMS) composites with high piezo-resistive performance. GCH particles were synthesized by the catalyst chemical vapor deposition approach. The synthesized GCHs can be well dispersed in the matrix through the mechanical blending process. Due to the exfoliated GNP and aligned CNTs coupling structure, the flexible composite shows an ultralow percolation threshold (0.64 vol %) and high piezo-resistive sensitivity (gauge factor ∼ 10(3) and pressure sensitivity ∼ 0.6 kPa(-1)). Slight motions of finger can be detected and distinguished accurately using the composite film as a typical wearable sensor. These results indicate that designing the internal conductive network could be a reasonable strategy to improve the piezo-resistive performance of composites.

A graphene oxide-carbon nanotube grid for high-resolution transmission electron microscopy of nanomaterials.

PubMed

Zhang, Lina; Zhang, Haoxu; Zhou, Ruifeng; Chen, Zhuo; Li, Qunqing; Fan, Shoushan; Ge, Guanglu; Liu, Renxiao; Jiang, Kaili

2011-09-23

A novel grid for use in transmission electron microscopy is developed. The supporting film of the grid is composed of thin graphene oxide films overlying a super-aligned carbon nanotube network. The composite film combines the advantages of graphene oxide and carbon nanotube networks and has the following properties: it is ultra-thin, it has a large flat and smooth effective supporting area with a homogeneous amorphous appearance, high stability, and good conductivity. The graphene oxide-carbon nanotube grid has a distinct advantage when characterizing the fine structure of a mass of nanomaterials over conventional amorphous carbon grids. Clear high-resolution transmission electron microscopy images of various nanomaterials are obtained easily using the new grids.

Interruption of Hydrogen Bonding Networks of Water in Carbon Nanotubes Due to Strong Hydration Shell Formation.

PubMed

Oya, Yoshifumi; Hata, Kenji; Ohba, Tomonori

2017-10-24

We present the structures of NaCl aqueous solution in carbon nanotubes with diameters of 1, 2, and 3 nm based on an analysis performed using X-ray diffraction and canonical ensemble Monte Carlo simulations. Anomalously longer nearest-neighbor distances were observed in the electrolyte for the 1-nm-diameter carbon nanotubes; in contrast, in the 2 and 3 nm carbon nanotubes, the nearest-neighbor distances were shorter than those in the bulk electrolyte. We also observed similar properties for water in carbon nanotubes, which was expected because the main component of the electrolyte was water. However, the nearest-neighbor distances of the electrolyte were longer than those of water in all of the carbon nanotubes; the difference was especially pronounced in the 2-nm-diameter carbon nanotubes. Thus, small numbers of ions affected the entire structure of the electrolyte in the nanopores of the carbon nanotubes. The formation of strong hydration shells between ions and water molecules considerably interrupted the hydrogen bonding between water molecules in the nanopores of the carbon nanotubes. The hydration shell had a diameter of approximately 1 nm, and hydration shells were thus adopted for the nanopores of the 2-nm-diameter carbon nanotubes, providing an explanation for the large difference in the nearest-neighbor distances between the electrolyte and water in these nanopores.

Iron Catalyst Chemistry in High Pressure Carbon Monoxide Nanotube Reactor

NASA Technical Reports Server (NTRS)

Scott, Carl D.; Povitsky, Alexander; Dateo, Christopher; Gokcen, Tahir; Smalley, Richard E.

2001-01-01

The high-pressure carbon monoxide (HiPco) technique for producing single wall carbon nanotubes (SWNT) is analyzed using a chemical reaction model coupled with properties calculated along streamlines. Streamline properties for mixing jets are calculated by the FLUENT code using the k-e turbulent model for pure carbon monixide. The HiPco process introduces cold iron pentacarbonyl diluted in CO, or alternatively nitrogen, at high pressure, ca. 30 atmospheres into a conical mixing zone. Hot CO is also introduced via three jets at angles with respect to the axis of the reactor. Hot CO decomposes the Fe(CO)5 to release atomic Fe. Cluster reaction rates are from Krestinin, et aI., based on shock tube measurements. Another model is from classical cluster theory given by Girshick's team. The calculations are performed on streamlines that assume that a cold mixture of Fe(CO)5 in CO is introduced along the reactor axis. Then iron forms clusters that catalyze the formation of SWNTs from the Boudouard reaction on Fe-containing clusters by reaction with CO. To simulate the chemical process along streamlines that were calculated by the fluid dynamics code FLUENT, a time history of temperature and dilution are determined along streamlines. Alternative catalyst injection schemes are also evaluated.

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.

STIR: Microwave Response of Carbon Nanotubes in Polymer Nanocomposite Welds

DTIC Science & Technology

2016-01-28

system, we choose polylactic acid ( PLA ) as a model polymer, given its common application in additive manufacturing. 1-3 For the nanofiller, we utilize...polylactic acid ( PLA ) with dispersed multi-walled carbon nanotubes (MWCNTs) made at Texas A&M will be characterized in the microwave lab at TTU. In...the heating effects associated with percolated network formation. Samples of polylactic acid ( PLA ) with dispersed multi-walled carbon nanotubes

A rational design for the separation of metallic and semiconducting single-walled carbon nanotubes using a magnetic field

NASA Astrophysics Data System (ADS)

Luo, Chengzhi; Wan, Da; Jia, Junji; Li, Delong; Pan, Chunxu; Liao, Lei

2016-06-01

The separation of metallic (m-) and semiconducting (s-) single-walled carbon nanotubes (SWNTs) without causing contamination and damage is a major challenge for SWNT-based devices. As a facile and nondestructive tool, the use of a magnetic field could be an ideal strategy to separate m-/s-SWNTs, based on the difference of magnetic susceptibilities. Here, we designed a novel magnetic field-assisted floating catalyst chemical vapor deposition system to separate m-/s-SWNTs. Briefly, m-SWNTs are attracted toward the magnetic pole, leaving s-SWNTs on the substrate. By using this strategy, s-SWNTs with a purity of 99% could be obtained, which is enough to construct high-performance transistors with a mobility of 230 cm2 V-1 s-1 and an on/off ratio of 106. We also established a model to quantitatively calculate the percentage of m-SWNTs on the substrate and this model shows a good match with the experimental data. Furthermore, our rational design also provides a new avenue for the growth of SWNTs with specific chirality and manipulated arrangement due to the difference of magnetic susceptibilities between different diameters, chiralities, and types.The separation of metallic (m-) and semiconducting (s-) single-walled carbon nanotubes (SWNTs) without causing contamination and damage is a major challenge for SWNT-based devices. As a facile and nondestructive tool, the use of a magnetic field could be an ideal strategy to separate m-/s-SWNTs, based on the difference of magnetic susceptibilities. Here, we designed a novel magnetic field-assisted floating catalyst chemical vapor deposition system to separate m-/s-SWNTs. Briefly, m-SWNTs are attracted toward the magnetic pole, leaving s-SWNTs on the substrate. By using this strategy, s-SWNTs with a purity of 99% could be obtained, which is enough to construct high-performance transistors with a mobility of 230 cm2 V-1 s-1 and an on/off ratio of 106. We also established a model to quantitatively calculate the percentage of m

Chirality specific and spatially uniform synthesis of single-walled carbon nanotubes from a sputtered Co-W bimetallic catalyst

NASA Astrophysics Data System (ADS)

An, Hua; Kumamoto, Akihito; Takezaki, Hiroki; Ohyama, Shinnosuke; Qian, Yang; Inoue, Taiki; Ikuhara, Yuichi; Chiashi, Shohei; Xiang, Rong; Maruyama, Shigeo

2016-07-01

Synthesis of single-walled carbon nanotubes (SWNTs) with well-defined atomic arrangements has been widely recognized in the past few decades as the biggest challenge in the SWNT community, and has become a bottleneck for the application of SWNTs in nano-electronics. Here, we report a selective synthesis of (12, 6) SWNTs with an enrichment of 50%-70% by chemical vapor deposition (CVD) using sputtered Co-W as a catalyst. This is achieved under much milder reduction and growth conditions than those in the previous report using transition-metal molecule clusters as catalyst precursors (Nature, 2014, 510, 522). Meanwhile, in-plane transmission electron microscopy unambiguously identified an intermediate structure of Co6W6C, which is strongly associated with selective growth. However, most of the W atoms disappear after a 5 min CVD growth, which implies that anchoring W may be important in this puzzling Co-W system.Synthesis of single-walled carbon nanotubes (SWNTs) with well-defined atomic arrangements has been widely recognized in the past few decades as the biggest challenge in the SWNT community, and has become a bottleneck for the application of SWNTs in nano-electronics. Here, we report a selective synthesis of (12, 6) SWNTs with an enrichment of 50%-70% by chemical vapor deposition (CVD) using sputtered Co-W as a catalyst. This is achieved under much milder reduction and growth conditions than those in the previous report using transition-metal molecule clusters as catalyst precursors (Nature, 2014, 510, 522). Meanwhile, in-plane transmission electron microscopy unambiguously identified an intermediate structure of Co6W6C, which is strongly associated with selective growth. However, most of the W atoms disappear after a 5 min CVD growth, which implies that anchoring W may be important in this puzzling Co-W system. Electronic supplementary information (ESI) available: Raman spectroscopy (G-band) of SWNTs grown from Co and Co-W catalyst; Kataura plot for chirality

Label-free detection of DNA hybridization using carbon nanotube network field-effect transistors

NASA Astrophysics Data System (ADS)

Star, Alexander; Tu, Eugene; Niemann, Joseph; Gabriel, Jean-Christophe P.; Joiner, C. Steve; Valcke, Christian

2006-01-01

We report carbon nanotube network field-effect transistors (NTNFETs) that function as selective detectors of DNA immobilization and hybridization. NTNFETs with immobilized synthetic oligonucleotides have been shown to specifically recognize target DNA sequences, including H63D single-nucleotide polymorphism (SNP) discrimination in the HFE gene, responsible for hereditary hemochromatosis. The electronic responses of NTNFETs upon single-stranded DNA immobilization and subsequent DNA hybridization events were confirmed by using fluorescence-labeled oligonucleotides and then were further explored for label-free DNA detection at picomolar to micromolar concentrations. We have also observed a strong effect of DNA counterions on the electronic response, thus suggesting a charge-based mechanism of DNA detection using NTNFET devices. Implementation of label-free electronic detection assays using NTNFETs constitutes an important step toward low-cost, low-complexity, highly sensitive and accurate molecular diagnostics. hemochromatosis | SNP | biosensor

Printing Highly Controlled Suspended Carbon Nanotube Network on Micro-patterned Superhydrophobic Flexible Surface

PubMed Central

Li, Bo; Wang, Xin; Jung, Hyun Young; Kim, Young Lae; Robinson, Jeremy T.; Zalalutdinov, Maxim; Hong, Sanghyun; Hao, Ji; Ajayan, Pulickel M.; Wan, Kai-Tak; Jung, Yung Joon

2015-01-01

Suspended single-walled carbon nanotubes (SWCNTs) offer unique functionalities for electronic and electromechanical systems. Due to their outstanding flexible nature, suspended SWCNT architectures have great potential for integration into flexible electronic systems. However, current techniques for integrating SWCNT architectures with flexible substrates are largely absent, especially in a manner that is both scalable and well controlled. Here, we present a new nanostructured transfer paradigm to print scalable and well-defined suspended nano/microscale SWCNT networks on 3D patterned flexible substrates with micro- to nanoscale precision. The underlying printing/transfer mechanism, as well as the mechanical, electromechanical, and mechanical resonance properties of the suspended SWCNTs are characterized, including identifying metrics relevant for reliable and sensitive device structures. Our approach represents a fast, scalable and general method for building suspended nano/micro SWCNT architectures suitable for flexible sensing and actuation systems. PMID:26511284

Printing Highly Controlled Suspended Carbon Nanotube Network on Micro-patterned Superhydrophobic Flexible Surface.

PubMed