Tailoring the Morphology of Carbon Nanotube Arrays: From Spinnable Forests to Undulating Foams

Zhang, Mingchao; Zou, Guifu; Doorn, Stephen K.; Htoon, Han; Stan, Liliana; Hawley, M. E.; Sheehan, Chris J.; Zhu, Yuntian; Jia, Q. X.

doi:10.1021/nn9003988

Cited by 98 publications

(65 citation statements)

References 32 publications

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“…Such a periodic rippling pattern can form spontaneously during growth. [2][3][4][5][6] Ripples can also be obtained by compressing a forest along the axis of the nanotubes, either during growth, 7 or postgrowth. [8][9][10] Iridescence from periodic arrangements of individual vertically aligned multiwalled nanotubes on a substrate [11][12][13] and periodic arrangements forests on a substrate 14 has previously been observed.…”

mentioning

confidence: 99%

“…1͑a͒, which appear similar to previous reports. [2][3][4][5][6][7][8][9][10] Here, ripples form spontaneously during growth, likely due to a growth rate difference between different nanotubes in the forest, 3,4 which in turn causes a compressive strain that bends the nanotubes. It is known that growing nanotubes exert a mechanical force, 7 which likely causes the compressive strain.…”

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Visible iridescence from self-assembled periodic rippling in vertically aligned carbon nanotube forests

Vinten

Jacques

Finnie

2010

Applied Physics Letters

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We observe iridescence in the form of spectrally dispersed white light reflected from the structured sidewalls of vertically aligned carbon nanotube forests. The iridescence is a result of diffraction from a self-assembled periodic rippling pattern on the forest sidewalls that acts as a reflection grating. We measure the grating spacing via white light and laser diffraction experiments and see good agreement with the spacing of the rippling pattern as measured via scanning electron microscopy. The periodic rippling pattern self-assembles during chemical vapor deposition growth of the forests.

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Visible iridescence from self-assembled periodic rippling in vertically aligned carbon nanotube forests

Vinten

Jacques

Finnie

2010

Applied Physics Letters

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“…乙烯作为反应气体, 同时也具有还原性. 因此, 生长过程中氢气与乙烯气体的通入顺序对于阵列的可纺性具有重大影响 [58] . 需要指出的是, 对于含有偶氮苯基元的侧链型液晶弹性体, 偶氮苯基元在紫外光照射下从反式转变为顺式结构, 停止紫外光照后, 在可见光照射下, 顺式又回复到反式结构.…”

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Preparation and Application of Aligned Carbon Nanotube/Polymer Composite Material

Qiu¹,

Sun²,

Yang³

et al. 2012

Acta Chim. Sinica

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Carbon nanotube (CNT)/polymer composite materials have been widely studied for two decades. However, there remains a common and critical challenge, i.e., random dispersion of CNTs in polymer matrices, which has largely lowered their properties and limited their applications. Herein, we have developed a general method to prepare highly aligned CNT/polymer composite materials in formats of array, film, and fiber. The key procedure is to synthesize spinnable CNT arrays with high quality by a chemical vapor deposition process. Fe/Al 2 O 3 was used as catalyst, ethylene was used as carbon source, a mixture gas of argon and hydrogen was used as carrying gas. The optimal growth conditions were summarized as below: thickness of 1.2 nm for Fe, thickness of 3 nm for Al 2 O 3 , flow rate of 400 standard cm 3 /min for argon, flow rate of 90 standard cm 3 /min for ethylene, flow rate of 30 standard cm 3 /min for hydrogen, growth temperature of 740 ℃, and growth time of 10 min. Here the catalyst system was coated on silicon substrate by electron beam evaporation with rates of 0.5 and 2 Å/s for Fe and Al 2 O 3 , respectively. To prepare CNT sheets or fibers, the spinnable array was first stabilized in a stage. A blade was then used to draw a ribbon out of the array. A CNT sheet would be obtained if the ribbon was directly pulled out without rotation, while a fiber should be produced if a rotary spinning was used. The spinning speed was about 15 cm/min. Monomer/polymer solutions or melts were directly coated onto the aligned CNT sheet or fiber to produce the aligned CNT/polymer film or fiber. Due to the high alignment of CNTs in polymer matrices, the resulting composite materials exhibited remarkable physical properties, e.g., the mechanical strength and electrical conductivity can be improved for one and three orders compared with the conventional solution blending method, respectively. These novel composite materials are promising for a wide variety of applications. The use of them as novel counter electrodes to fabricate dye-sensitized solar cells has been investigated as a demonstration. In a typical fabrication, an aligned CNT/polymer film (typical thickness of 5 μm) was first transferred onto fluorine doped tin oxide as counter electrode. A layer of TiO 2 was coated onto fluorine doped tin oxide as working electrode, followed by immersion into 0.5 mmol/L cis-diisothiocyanato-bis (2,2'-bipyridyl-4,4'-dicarboxylato) ruthenium(II) bis(tetrabutylammonium) (also called N719) solution in a mixture solvent of acetonitrile/tert-butanol (volume ratio of 1/1) for 16 h. After being further rinsed with acetonitrile and dried, the N719-incorporated TiO 2 electrode was assembled with the counter electrode. An electrolyte which consisted of LiI, I 2 , 2-2-3-with propyl methyl 5-membered imidazole iodine, GuSCN, and tri-butyl-phosphate in dehydrated acetonitrile was injected into the cell through a hole on the counter electrode. The hole was finally sealed with surlyn and a piece of glass.

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“…Figure 1 shows the schematic drawing of the processing steps to form the CNTNbC composites. The highly aligned CNT forests were grown on the silicon substrate by a chemical vapour deposition 11 . The CNT forests were then soaked by a homogeneous Nb precursor solution.…”

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“…After detaching the CNT forests from the silicon substrate (simply by peeling off the CNT forest from the Si substrate using a tweezer), we converted the Nb precursor to NbC by annealing the sample under an ethylene environment. Ethylene is also used as the carbon source for the growth of CNT forests 11 . The integrity of both CNT forests and NbC is maintained after the formation of CNT-NbC composite.…”

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Highly aligned carbon nanotube forests coated by superconducting NbC

et al. 2011

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The formation of carbon nanotube and superconductor composites makes it possible to produce new and/or improved functionalities that the individual material does not possess. Here we show that coating carbon nanotube forests with superconducting niobium carbide (nbC) does not destroy the microstructure of the nanotubes. nbC also shows much improved superconducting properties such as a higher irreversibility and upper critical field. An upper critical field value of ~5 T at 4.2 K is much greater than the 1.7 T reported in the literature for pure bulk nbC. Furthermore, the aligned carbon nanotubes induce anisotropy in the upper critical field, with a higher upper critical field occurring when the magnetic field is parallel to the carbon nanotube growth direction. These results suggest that highly oriented carbon nanotubes embedded in superconducting nbC matrix can function as defects and effectively enhance the superconducting properties of the nbC.

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Tailoring the Morphology of Carbon Nanotube Arrays: From Spinnable Forests to Undulating Foams

Cited by 98 publications

References 32 publications

Visible iridescence from self-assembled periodic rippling in vertically aligned carbon nanotube forests

Visible iridescence from self-assembled periodic rippling in vertically aligned carbon nanotube forests

Preparation and Application of Aligned Carbon Nanotube/Polymer Composite Material

Highly aligned carbon nanotube forests coated by superconducting NbC

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