Fabrication of a multifunctional carbon nanotube “cotton” yarn by the direct chemical vapor deposition spinning process

Abstract

A continuous cotton-like carbon nanotube fiber yarn, consisting of multiple threads of high purity double walled carbon nanotubes, was fabricated in a horizontal CVD gas flow reactor with water vapor densification by the direct chemical vapor deposition spinning process. The water vapor interaction leads to homogeneous shrinking of the CNT sock-like assembly in the gas flow. This allows well controlled continuous winding of the dense thread inside the reactor. The CNT yarn is quite thick (1-3 mm), has a highly porous structure (99%) while being mechanically strong and electrically conductive. The water vapor interaction leads to homogeneous oxidation of the CNTs, offering the yarn oxygen-functionalized surfaces. The unique structure and surface of the CNT yarn provide it multiple processing advantages and properties. It can be mechanically engineered into a dense yarn, infiltrated with polymers to form a composite and mixed with other yarns to form a blend, as demonstrated in this research. Therefore, this CNT yarn can be used as a "basic yarn" for various CNT based structural and functional applications.

A Review of Double-Walled and Triple-Walled Carbon Nanotube Synthesis and Applications

“…Using this method, Li et al [129] firstly reported the continuous production of SWNTs. Soon thereafter, the continuous production of DWNTs was also reported by optimizing the temperature, precursor composition (both of the metal catalyst precursor and the sulfur/sulfur-containing molecule), as well as the aerosol generation conditions and reaction conditions [121][122][123].…”

Double‐Twisted Conductive Smart Threads Comprising a Homogeneously and a Gradient‐Coated Thread for Multidimensional Flexible Pressure‐Sensing Devices

“…According to previous reports, thread fibers normally present 6-8 % strain under stress before failure. [38,39] This strain will cause the SWCNT conductive network on the surface of thread fibers to generate a piezoresistive effect, which can be confirmed via micromorphological variation in the SWCNTs on them, as shown in Figure 2d. [40,41] Note that the SWCNTs used here were modified with a 2-4 nm coating of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT/PSS).…”

The effect of a convection vortex on sock formation in the floating catalyst method for carbon nanotube synthesis

“…The thermophoretic force is a result of temperature gradients and responsible for keeping CNTs from bonding on the reactor tube. Also (ii) Zhong et al [7,28] speculated that the van der Waals attraction leads to the sock formation. And (iii) Chaffee et al [29] mentioned that the nanotubes could form bundles due to electrostatic attraction.…”

“…Motta et al [16] studied the effect of carrier gas and feedstock injection rate on the sock "spinnability" in a vertical furnace. Some mechanisms have been proposed for the sock formation, including thermophoresis or inertial migration [22], van der Waals attraction [7,28] and electrostatic attraction [29]. However, there is still significant ambiguity surrounding the understanding of how transport issues affecting the sock formation process.…”