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Nanotube Walls (nanotube + wall)

Distribution by Scientific Domains

Polymers and Materials Science	50%

Selected Abstracts

Copper Azide Confined Inside Templated Carbon Nanotubes

ADVANCED FUNCTIONAL MATERIALS, Issue 18 2010
Valarie Pelletier
Abstract The currently used primary explosives, such as lead azide and lead styphnate, present serious health hazards due to the toxicity of lead. There is a need to replace them with equally energetic but safer-to-handle and more environmentally friendly materials. Copper azide is more environmentally acceptable, but very sensitive and detonates easily from electrostatic charges during handling. If the highly sensitive copper azide is encapsulated within conducting containers, such as anodic aluminum oxide (AAO)-templated carbon nanotubes (CNTs), its sensitivity can be tamed. This work describes a technique for confining energetic copper azide within CNTs. ,5 nm colloidal copper oxide nanoparticles are synthesized and filled into the 200 nm diameter CNTs, produced by template synthesis. The Cu-O inside the CNTs is reduced in hydrogen to copper, and reacted with hydrazoic acid gas to produce copper azide. Upon initiation, the 60 ,m long straight, open-ended CNTs guide decomposition gases along the tube channel without fracturing the nanotube walls. These novel materials have potential for applications as nano-detonators and green primary explosives; they also offer new opportunities for understanding the physics of detonation at the nanoscale. [source]

Template-Directed Liquid ALD Growth of TiO2 Nanotube Arrays: Properties and Potential in Photovoltaic Devices

ADVANCED FUNCTIONAL MATERIALS, Issue 9 2010
Thelese R. B. Foong
Abstract Dense and well-aligned arrays of TiO2 nanotubes extending from various substrates are successfully fabricated via a new liquid-phase atomic layer deposition (LALD) in nanoporous anodic alumina (AAO) templates followed by alumina dissolution. The facile and versatile process circumvents the need for vacuum conditions critical in traditional gas-phase ALD and yet confers ALD-like deposition rates of 1.6,2.2,Å cycle,1, rendering smooth conformal nanotube walls that surpass those achievable by sol,gel and Ti-anodizing techniques. The nanotube dimensions can be tuned, with most robust structures being 150,400,nm tall, 60,70,nm in diameter with 5,20,nm thick walls. The viability of TiO2 nanotube arrays deposited on indium tin oxide (ITO),glass electrodes for application in model hybrid poly(3-hexylthiophene) (P3HT):TiO2 solar cells is studied. The results achieved provide platforms and research directions for further advancements. [source]

Strain Rate Effects in the Mechanical Response of Polymer-Anchored Carbon Nanotube Foams,

ADVANCED MATERIALS, Issue 3 2009
Abha Misra
Strain rate effects on the mechanical properties of carbon nanotube forests are studied, and several related interesting new phenomena are reported. Dense vertically aligned foam-like forests of carbon nanotubes are anchored on a thin, flexible polymer layer to provide structural stability, particularly at the higher strain rates. Permanent deformation and for the first time the delamination and crumbling of carbon nanotube walls is observed. [source]

Field emission from single-wall nanotubes obtained from carbon and boron nitride mixtures

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 10 2008
V. I. Kleshch
Abstract Heterophase BN:C single-wall nanotubes are prospective as a material with a predicted possibility to vary the bandgap via changing a relative content of BN and C fractions in the nanotube walls. The challenge is both to find the ways of synthesis of such nanotubes and, in case of success, to confirm BN embedding. In this work field emission studies have been performed for revealing the difference between arc-produced pure carbon nanotubes and nanotubes grown from BN:C mixtures. The relative BN content in the mixtures was varied from 0% up to 50% (by mass). The materials have been characterized by a high resolution transmission electron microscopy, Raman scattering and UV-VIS-NIR optical absorption techniques. The single-wall nanotubes have been revealed in all samples synthesized, but their composition remained questionable. The field emission properties of the samples have been examined in a vacuum diode configuration. It has been found that the threshold fields and slopes of the Fowler,Nordheim plot, evaluated from the measured current,voltage dependences, increased with an enrichment of the starting mixtures with h-BN. This increase could be attributed to the work function rise due to h-BN embedding into the carbon nanotube walls. This result opens a way to use the field-emission characterization for an indirect confirmation of the heterophase BN:C nanotube formation. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Characterisation of Nanohybrids of Porphyrins with Metallic and Semiconducting Carbon Nanotubes by EPR and Optical Spectroscopy

CHEMPHYSCHEM, Issue 13 2008
Sofie Cambré
Abstract Single-walled carbon nanotubes (SWCNTs) are noncovalently functionalised with octaethylporphyrins (OEPs) and the resulting nanohybrids are isolated from the free OEPs. Electron paramagnetic resonance (EPR) spectroscopy of cobalt(II)OEP, adsorbed on the nanotube walls by ,,,-stacking, demonstrates that the CNTs act as electron acceptors. EPR is shown to be very effective in resolving the different interactions for metallic and semiconducting tubes. Moreover, molecular oxygen is shown to bind selectively to nanohybrids with semiconducting tubes. Water solubilisation of the porphyrin/CNT nanohybrids using bile salts, after applying a thorough washing procedure, yields solutions in which at least 99,% of the porphyrins are interacting with the CNTs. Due to this purification, we observe, for the first time, the isolated absorption spectrum of the interacting porphyrins, which is strongly red-shifted compared to the free porphyrin absorption. In addition a quasi-complete quenching of the porphyrin fluorescence is also observed. [source]