Carbon‐Nanotube Cotton for Large‐Scale Fibers

Abstract

Carbon nanotubes (CNTs) are much stronger than any existing material. To fully utilize their extremely high strength, carbon-nanotubes must be spun into continuous fibers. [1][2][3] The most efficient way to produce commercial-scale CNT fibers is by the five-thousand-years-old cotton-based spinning technology.[4] Therefore, it is technologically attractive to produce CNT materials that have spinning properties similar to cotton. Here we report a new form of CNT material, CNT cotton, that is made of ultralong individual CNTs. This CNT cotton is analogous to conventional cotton in many aspects including the color and fluffiness, and is found favorable for spinning. It is found that the CNT cotton is hydrophobic, and is composed of low spatial density and ultra-long individual CNTs. Figure 1a is a photograph of fluffy and gray CNT cotton on a quartz support (15 mm × 35 mm). The CNT cotton has very low density with large space between individual CNTs, making it very similar to conventional cotton in terms of structural form. The gray color is surprising because all other CNT materials are black. This gray color is caused by the unique low spatial density of nanotubes in the CNT cotton, as well as a light-scattering effect. From the side view (Fig. 1b), we can see a 2 mm thick CNT cotton above the support, indicating that the CNT cotton is composed of long (at least millimeters) individual CNTs.The CNT cotton is also found to be hydrophobic. As shown in Figure 2a, a water droplet with a diameter of 2.5 mm was suspended on the CNT cotton. It sank into the CNT cotton because of its weight, but maintained a quasi-spherical shape. After the water-droplet was completely evaporated, the morphology of the CNT cotton was examined by scanning electron microscopy (SEM). The CNTs in the area that supported the water droplet were rearranged into a web-like mesh (see Fig. 2b), but the CNTs underneath the web still retained the cotton form (Fig. 2c), further confirming the hydrophobic behavior of CNT cotton.Catalytic chemical vapor deposition (CVD) [5] was used to synthesize the CNT cotton.

Electrochemical capacitive properties of CNT fibers spun from vertically aligned CNT arrays

“…Since we have not found obvious change in the composition of CNT fiber (structures), and the near-rectangular shape of CV curves (Fig. 3b) without any obvious redox peak [25], together with the hydrophobic nature of our CNT material [26], we believe that the enhanced specific capacitance after activation in our case could be attributed to the improvedwetting effect of CNTs by electrolyte (Na 2 SO 4 aqueous solution) during potential scanning in a large window, leading to a larger accessible area. This is supported by EIS results in Fig.…”

The electro-structural behaviour of yarn-like carbon nanotube fibres immersed in organic liquids

“…Those fibres, directly-spun from a chemical vapour deposition (CVD) reactor [3, 17], or spun from solid arrays of CNTs [4, 18], have highly porous yarn-like structures with accessible specific surface areas ranging from 70 to 200 m 2 g −1 [8, 17, 19]. These relatively high values of porosity mean that properties such as the electrical conductivity and mechanical strength of the fibres are highly dependent on the physical and chemical interactions with their environment.…”

High‐Strength Carbon Nanotube Fibers Fabricated by Infiltration and Curing of Mussel‐Inspired Catecholamine Polymer

“…An alternative strategy is solid-state spinning, [8][9][10][11][12][13][14][15][16][17] which allows avoidance of CNT dispersion in solvents and for various post-spinning processes to be applied with ease. Twisting, [10][11][12][13][14][15][16] densifi cation, [ 9 , 18 ] and infi ltration [ 8 , 19,20 ] are examples of post-spinning processes, and the main purpose of the spinning and post-spinning processes is to enhance the mechanical properties of CNT fi bers. Despite the effort that has been made, however, fabrication of strong CNT fi bers remains a great challenge.…”