排序方式: 共有53条查询结果,搜索用时 15 毫秒
1.
Geng J Singh C Shephard DS Shaffer MS Johnson BF Windle AH 《Chemical communications (Cambridge, England)》2002,(22):2666-2667
A simple method for the synthesis of high purity single wall carbon nanotubes has been developed by using nickel formate as a precursor for the formation of nearly mono-dispersed nickel seed-nanoparticles as catalysts in the CVD growth process. 相似文献
2.
D. Eder M.S. Motta I.A. Kinloch A.H. Windle 《Physica E: Low-dimensional Systems and Nanostructures》2007,37(1-2):245
Anatase nanotubes were successfully produced via the sol–gel process involving organic titanium precursors and multi-walled carbon nanotubes as template. Controlled heat treatments were carried out in order to remove any solvents and to crystallise the initial amorphous titania coating into anatase. In order to use these structures for catalyst support, platinum particles were formed by the impregnation with hexachloroplatinic acid and subsequent calcination and reduction to obtain a final loading of 4 wt% platinum. This impregnation step was carried out either with the carbon nanotube former still present with subsequent heat treatment to remove the carbonaceous template (sample A) or with the carbon nanotube former already removed (sample B). The materials were characterised by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. 相似文献
3.
One of the features of liquid crystalline polymers (LCPs) is their strong elastic anisotropy, which means they have unequal elastic constants. Elastic anisotropy plays a crucial role in the microstructure and macroscopic properties of LCPs. In this paper, the effect of unequal elastic constants on microstructure is investigated without an external field by using a deterministic tensorial approach. In this model, the evolution of the director field can be viewed as a process driven towards the state of zero elastic torque. A tensor expression of the elastic torque is used so that the nematic symmetry is automatically conserved. In simulations of bulk samples, disclination lines of strength half and escaped integer disclinations are observed. The distortion fields around the disclinations are found to depend on elastic anisotropy. If the twist constant is the lowest, as is the case for main chain liquid crystalline polymers, the disclination lines are predominantly of the twist type. 相似文献
4.
5.
6.
Geng J Zhou W Skelton P Yue W Kinloch IA Windle AH Johnson BF 《Journal of the American Chemical Society》2008,130(8):2527-2534
Exceptionally long C60 nanowires, with a length to width aspect ratio as large as 3000, are grown from a 1,2,4-trimethylbenzene solution of C60. They have been formed to possess a highly unusual morphology, with each nanowire being composed of two nanobelts joined along the growth direction to give a V-shaped cross section. The crystal structure of these nanowires is found to be orthorhombic, with the unit cell dimensions of a = 10.2 A, b = 20.5 A, and c = 25.6 A. Structural and compositional analyses enable us to explain the observed geometry with an anisotropic molecular packing mechanism that has not been observed previously in C60 crystal studies. The nanowires have been observed to be able to transform into carbon nanofibers following high-temperature treatment, but the original V-shaped morphology can be kept unchanged in the transition. A model for the nanowire morphology based upon the solvent-C60 interactions and preferential growth directions is proposed, and potentially it could be extended for use to grow different types of fullerene nanowires. 相似文献
7.
Chaobin He Athene M. Donald Anselm C. Griffin Tom Waigh Alan H. Windle 《Journal of Polymer Science.Polymer Physics》1998,36(10):1617-1624
A main chain hydrogen-bonded liquid crystalline polymer was formed by melt mixing two complementary components, A and B, which in their individual states do not exhibit liquid crystallinity. The structure of the polymer and the thermal stability of its mesophase were studied using synchrotron radiation SAXS/WAXS/DSC at Daresbury (UK) and by variable temperature Fourier transform infrared. The chain extension, or “polymerization” process, was accelerated at the point when the polymer formed a liquid crystalline phase upon cooling from the isotropic melt. The polymer has an aabb chain structure and forms a smectic layer with a length of the A-B repeating unit. The hydrogen-bonded main chain polymer studied here is a monotropic liquid crystal. Above 150°C, it exhibits kinetic stabilization of its monotropic smectic phase. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1617–1624, 1998 相似文献
8.
CD Windle MV Câmpian AK Duhme-Klair EA Gibson RN Perutz J Schneider 《Chemical communications (Cambridge, England)》2012,48(66):8189-8191
Photocatalytic CO(2) reduction has been studied for two dyads with porphyrin covalently attached to rhenium tricarbonyl bipyridine moieties, and on separate components consisting of [Re(CO)(3)(Picoline)Bpy](+) and either zinc porphyrin or zinc chlorin. TONs decrease in the order: zinc porphyrin + Re > long spacer dyad > zinc chlorin + Re > short spacer dyad. 相似文献
9.
Phase diagrams for the system nitrocellulose/tetrahydrofuran/ethanol have been mapped out at room temperature, for two different degrees of substitution of the polymer (2·32 and 2·72). The phases formed by particular compositions were identified by using polarized light microscopy. There is a range of compositions which separate into an isotropic phase and a liquid-crystalline phase; the concentrations involved are qualitatively in agreement with Flory's theory of phase separation in a solution of rigid rod-like molecules. Our plotted room temperature sections of the phase diagrams obey the Gibbs phase rule at all points. We report evidence for the formation of a crystallosolvate of nitrocellulose (degree of substitution 2·72) and ethanol. The crystallosolvate formation only appears to be kinetically possible if there is initially also sufficient tetrahydrofuran present to dissolve the polymer. 相似文献
10.
Marcelo Motta Ian Kinloch Anna Moisala Venugoplan Premnath Martin Pick Alan Windle 《Physica E: Low-dimensional Systems and Nanostructures》2007,37(1-2):40
We have recently introduced a method for the continuous spinning of carbon nanotube fibres and films directly from the gas phase of a chemical vapour deposition furnace [Y. Li, et al., Science 304 (2004) 276]. In this work the effect of the process parameters on the ability to spin continuously is studied, with particular focus on the carrier gas and feedstock flow rates. Catalyst dilution by high carrier gas flow rates led to smaller diameter nanotubes but these conditions are found the hardest to spin. 相似文献