A size-adjustable carbon nanotube hollow fiber and a continuous preparation method thereof

Abstract

The present invention discloses a size-adjustable carbon nanotube hollow fiber and a continuous preparation method thereof, comprising the following steps: using vinylon filaments as a baseline, coating carbon nanotubes on the surface of the baseline by a physical coating method to obtain a composite fiber; removing the baseline from the composite fiber by a water-soluble method to obtain the size-adjustable carbon nanotube hollow fiber. The present invention uses water-soluble vinylon filaments as a baseline, coating carbon nanotubes on the surface of the baseline, and then removing the baseline by a water-soluble method to obtain the carbon nanotube hollow fiber. The preparation method is simple and can be carried out continuously; the carbon nanotube hollow fiber of the present invention is completely composed of pure carbon nanotubes and has good electrical and mechanical properties; the inner diameter and wall thickness of the carbon nanotube hollow fiber can be adjusted by adjusting the number of baselines and the number of repeated coatings, and removing the baseline by the water-soluble method will not damage the carbon nanotubes.

Description

Technical Field

[0001] The present invention relates to the technical field of hollow fibers, and in particular to a size-adjustable carbon nanotube hollow fiber and a continuous preparation method thereof. Background Art

[0002] Carbon nanotube fibers are macroscopic fibers assembled from highly stacked microscopic carbon nanotubes oriented along the fiber axis. They possess a unique one-dimensional nanostructure and, to a certain extent, retain the excellent electrical, mechanical, and thermal properties inherent to microscopic carbon nanotubes. Recently developed hollow carbon nanotube fibers, with their high porosity, large surface area, and high permeability, hold broad application prospects in catalysis, the environment, and energy sectors.

[0003] Both the literature (J.Mater.Chem.A, 2021, 9, 390) and the patent (CN111058276A) report a method for preparing carbon nanotube composite hollow fibers by coating carbon nanotubes on the surface of existing hollow fibers. Although this method can quickly prepare hollow fibers, the prepared hollow fibers are not entirely composed of carbon nanotubes, have poor electrical conductivity, and cannot regulate the radial size of the hollow fibers. In addition, the preparation of carbon nanotube hollow fibers can be achieved by wet spinning. For example, the patent (CN115787143A) discloses a continuous preparation method of carbon nanotube hollow fibers and their carbon nanotube hollow fibers and supercapacitors. For example, the literature (ChemElectroChem, 2021, 8, 1665) uses a coaxial wet spinning method to prepare polymer / carbon nanotube composite hollow fibers. Due to the special chemical inertness of carbon nanotubes, they are very easy to agglomerate when dispersed, and it is usually necessary to add a dispersant to prepare a high-concentration carbon nanotube spinning solution. Therefore, the existing wet spinning technology is still difficult to achieve the continuous preparation of pure carbon nanotube hollow fibers, and the inner diameter and wall thickness of the hollow fibers cannot be controlled. In addition, the prior art reports another method for preparing carbon nanotube hollow fibers, namely the template method. For example, the literature (Nano-Micro Lett., 2020, 12, 64; Appl. Surf. Sci., 2024, 649, 159188) uses a metal wire as a template, first chemically deposits graphene and carbon nanotube materials on its surface, and then removes the metal wire by etching with an acidic solution to obtain a hollow fiber. Although this method can regulate the inner diameter and wall thickness of the hollow fiber, it is difficult to continuously prepare carbon nanotube hollow fibers, and the mechanical strength of the fiber after etching is low, which is difficult to meet application requirements.

[0004] Existing carbon nanotube hollow fibers are not composed of pure carbon nanotubes, their electrical and mechanical properties are limited, and the radial size of the hollow fibers cannot be simultaneously controlled, making continuous production difficult. Therefore, new strategies are urgently needed to achieve the continuous production of carbon nanotube hollow fibers with excellent performance and adjustable size. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a size-adjustable carbon nanotube hollow fiber and a continuous preparation method thereof. First, carbon nanotubes are coated on the surface of a water-soluble baseline, and then the baseline is removed by a water-soluble method to obtain pure carbon nanotube hollow fibers, avoiding the doping of other components and avoiding damage to the carbon nanotubes during the baseline removal process.

[0006] In order to solve the above technical problems, the present invention provides a continuous preparation method of size-adjustable carbon nanotube hollow fibers, comprising the following steps:

[0007] S1, using vinylon filament as the base, carbon nanotubes are coated on the base surface by physical coating method to obtain composite fibers;

[0008] S2. Removing the baseline of the composite fiber through a water-soluble method to obtain the size-adjustable carbon nanotube hollow fiber.

[0009] The present invention uses water-soluble vinylon filaments as the baseline, coats carbon nanotubes on the surface of the baseline, and then removes the baseline through a water-soluble method to obtain a carbon nanotube hollow fiber. The size of the carbon nanotube hollow fiber can be adjusted by adjusting the baseline size and the number of coatings. The water-soluble method for removing the baseline will not damage the carbon nanotubes. At the same time, the preparation method is simple and can be carried out continuously.

[0010] Furthermore, the carbon nanotube hollow fiber is a macroscopic hollow fiber composed of microscopic carbon nanotubes.

[0011] Furthermore, the count of the vinylon filaments is 10-130, and the inner diameter of the carbon nanotube hollow fiber can be adjusted by adjusting the count of the vinylon filaments. The larger the count, the thinner the corresponding vinylon filaments, and the smaller the inner diameter of the corresponding hollow fiber.

[0012] Furthermore, the carbon nanotubes are prepared by a floating catalyst chemical vapor deposition method.

[0013] Furthermore, the steps of preparing carbon nanotubes by the floating catalyst chemical vapor deposition method are as follows: a mixture of catalyst precursor, growth promoter and carbon source is carried into a reactor by a carrier gas and reacted at 1200-1400° C. to obtain single-walled or multi-walled carbon nanotube cylinders.

[0014] Furthermore, the catalyst precursor is one or more of organic compounds and inorganic salts of iron, nickel, and cobalt.

[0015] Furthermore, the growth promoter is a sulfur-containing organic matter.

[0016] Furthermore, the carbon source is hydrocarbon.

[0017] Furthermore, the coating is specifically performed by wetting the baseline with a solvent, and then contacting the wetted baseline with carbon nanotubes to coat the surface of the baseline with carbon nanotubes.

[0018] Furthermore, the coating is repeated 0-19 times, and the coating repetition number can be selected according to needs to adjust the wall thickness of the hollow fiber.

[0019] Furthermore, the solvent is one or more of water, ethanol, and acetone.

[0020] Furthermore, the liquid carrying rate of the wetted baseline surface is 10 wt%-30 wt%.

[0021] Furthermore, before step S2, the process further includes: continuously collecting and drying the composite fibers after water bathing to achieve subsequent hollow fiber shaping, wherein the drying temperature is 50-60° C. and the drying time is 2-4 hours.

[0022] Furthermore, the water bath method for removing the baseline is specifically as follows: placing the composite fiber in water at 90-100° C. for 1-2 hours.

[0023] The second aspect of the present invention provides a size-adjustable carbon nanotube hollow fiber prepared by the preparation method described in the first aspect.

[0024] Furthermore, the carbon nanotube hollow fiber has a self-supporting hollow fiber tubular structure.

[0025] Furthermore, the inner diameter of the carbon nanotube hollow fiber is 100-500 μm, and the wall thickness is 2-50 μm.

[0026] Beneficial effects of the present invention:

[0027] The present invention uses water-soluble vinylon filaments as the base, coats the carbon nanotubes on the surface of the base, and then removes the base by a water-soluble method to obtain the carbon nanotube hollow fiber. The preparation method is simple and can be carried out continuously.

[0028] The carbon nanotube hollow fiber prepared by the present invention is completely composed of pure carbon nanotubes and has good electrical and mechanical properties.

[0029] The present invention can adjust the inner diameter and wall thickness of the carbon nanotube hollow fiber by adjusting the number of base lines and the number of repeated coatings, and removing the base lines by a water-soluble method will not damage the carbon nanotubes. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a scanning electron microscope image of the carbon nanotube hollow fiber prepared in Example 1 of the present invention. Figure 1 ;

[0031] Figure 2 This is a scanning electron microscope image of the carbon nanotube hollow fiber prepared in Example 1 of the present invention. Figure 2 ;

[0032] Figure 3 is a scanning electron microscope image of the carbon nanotube hollow fiber prepared in Example 2 of the present invention;

[0033] Figure 4 This is a scanning electron microscope image of the carbon nanotube hollow fiber prepared in Example 3 of the present invention. DETAILED DESCRIPTION

[0034] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0035] Example 1

[0036] This embodiment relates to a continuous preparation method of size-adjustable carbon nanotube hollow fibers, comprising the following steps:

[0037] (1) Prepare baseline: 20-count water-soluble vinylon filaments;

[0038] (2) Preparation of carbon nanotube cylinders using floating catalyst chemical vapor deposition method:

[0039] A mixture of a catalyst precursor, a growth promoter, and a carbon source is fed through a peristaltic pump and carried into a reactor by a carrier gas for reaction to obtain a multi-walled carbon nanotube cylinder. The catalyst precursor is ferrocene, the growth promoter is thiophene, and the carbon source is ethanol. The mass ratio of the three is 98.8:0.6:0.6. The reaction temperature is 1300°C, and the carrier gas is high-purity nitrogen.

[0040] (3) The prepared carbon nanotube cylindrical object is coated on the surface of the baseline to obtain a composite fiber:

[0041] The base line is wetted with a solvent, and then the wetted base line is brought into contact with a carbon nanotube cylinder, thereby coating the base line surface with the carbon nanotube cylinder. The coating process is repeated four times to obtain a composite fiber, and then the composite fiber is continuously collected after being placed in a water bath and dried at 50° C. for 2 hours; wherein the solvent is ethanol, and the liquid content of the wetted base line surface is 20 wt%;

[0042] (4) Removing the baseline by water-soluble method to obtain carbon nanotube hollow fibers:

[0043] The composite fiber was placed in 95°C hot water for 1 h;

[0044] The final carbon nanotube hollow fiber is shown in the scanning electron microscope image. Figure 1 As shown, the inner diameter of the hollow fiber is 400±5μm and the wall thickness is 6.9±0.5μm. Figure 2 Through a larger magnification scanning electron microscope image, it was found that dense and uniform carbon nanotubes were accumulated on the surface of the hollow fiber.

[0045] Example 2

[0046] This embodiment relates to a continuous preparation method of size-adjustable carbon nanotube hollow fibers, comprising the following steps:

[0047] (1) Prepare baseline: 40-count water-soluble vinylon filament;

[0048] (2) Preparation of carbon nanotube cylinders using floating catalyst chemical vapor deposition method:

[0049] A mixture of a catalyst precursor, a growth promoter, and a carbon source is fed through a peristaltic pump and carried into a reactor by a carrier gas for reaction to obtain a multi-walled carbon nanotube cylinder. The catalyst precursor is ferrocene, the growth promoter is thiophene, and the carbon source is ethanol. The mass ratio of the three is 98.8:0.6:0.6. The reaction temperature is 1300°C, and the carrier gas is high-purity nitrogen.

[0050] (3) The prepared carbon nanotube cylindrical object is coated on the surface of the baseline to obtain a composite fiber:

[0051] The base line is wetted with a solvent, and then the wetted base line is brought into contact with a carbon nanotube cylinder, thereby coating the base line surface with the carbon nanotube cylinder. The coating process is repeated four times to obtain a composite fiber, and then the composite fiber is continuously collected after being placed in a water bath and dried at 50° C. for 2 hours; wherein the solvent is ethanol, and the liquid content of the wetted base line surface is 20 wt%;

[0052] (4) Removing the baseline by water-soluble method to obtain carbon nanotube hollow fibers:

[0053] The composite fiber was placed in 95°C hot water for 1 h;

[0054] The final carbon nanotube hollow fiber is shown in the scanning electron microscope image. Figure 3 As shown, the inner diameter of the hollow fiber is 305±5 μm and the wall thickness is 8.0±0.5 μm.

[0055] Example 3

[0056] This embodiment relates to a continuous preparation method of size-adjustable carbon nanotube hollow fibers, comprising the following steps:

[0057] (1) Prepare baseline: 60-count water-soluble vinylon filament;

[0058] (2) Preparation of carbon nanotube cylinders using floating catalyst chemical vapor deposition method:

[0059] A mixture of a catalyst precursor, a growth promoter, and a carbon source is fed through a peristaltic pump and carried into a reactor by a carrier gas for reaction to obtain a multi-walled carbon nanotube cylinder. The catalyst precursor is ferrocene, the growth promoter is thiophene, and the carbon source is ethanol. The mass ratio of the three is 98.8:0.6:0.6. The reaction temperature is 1300°C, and the carrier gas is high-purity nitrogen.

[0060] (3) The prepared carbon nanotube cylindrical object is coated on the surface of the baseline to obtain a composite fiber:

[0061] The base line is wetted with a solvent, and then the wetted base line is brought into contact with a carbon nanotube cylinder, thereby coating the base line surface with the carbon nanotube cylinder. The coating process is repeated four times to obtain a composite fiber, and then the composite fiber is continuously collected after being placed in a water bath and dried at 50° C. for 2 hours; wherein the solvent is ethanol, and the liquid content of the wetted base line surface is 20 wt%;

[0062] (4) Removing the baseline by water-soluble method to obtain carbon nanotube hollow fibers:

[0063] The composite fiber was placed in 95°C hot water for 1 h;

[0064] The final carbon nanotube hollow fiber is shown in the scanning electron microscope image. Figure 4 As shown, the inner diameter of the hollow fiber is 200±5 μm and the wall thickness is 11.0±0.5 μm.

[0065] Example 4

[0066] This embodiment relates to a continuous preparation method of size-adjustable carbon nanotube hollow fibers, comprising the following steps:

[0067] (1) Prepare baseline: 80-count water-soluble vinylon filament;

[0068] (2) Preparation of carbon nanotube cylinders using floating catalyst chemical vapor deposition method:

[0069] A mixture of a catalyst precursor, a growth promoter, and a carbon source is fed through a peristaltic pump and carried into a reactor by a carrier gas for reaction to obtain a multi-walled carbon nanotube cylinder. The catalyst precursor is ferrocene, the growth promoter is thiophene, and the carbon source is ethanol. The mass ratio of the three is 98.8:0.6:0.6. The reaction temperature is 1300°C, and the carrier gas is high-purity nitrogen.

[0070] (3) The prepared carbon nanotube cylindrical object is coated on the surface of the baseline to obtain a composite fiber:

[0071] The base line is wetted with a solvent, and then the wetted base line is brought into contact with a carbon nanotube cylinder, thereby coating the base line surface with the carbon nanotube cylinder. The coating process is repeated twice to obtain a composite fiber, and then the composite fiber is continuously collected after being placed in a water bath and dried at 50° C. for 2 hours; wherein the solvent is ethanol, and the liquid content of the wetted base line surface is 20 wt%;

[0072] (4) Removing the baseline by water-soluble method to obtain carbon nanotube hollow fibers:

[0073] The composite fiber was placed in 95°C hot water for 1 h;

[0074] The finally obtained carbon nanotube hollow fiber has an inner diameter of 135±5 μm and a wall thickness of 8.0±0.5 μm.

[0075] Example 5

[0076] This embodiment relates to a continuous preparation method of size-adjustable carbon nanotube hollow fibers, comprising the following steps:

[0077] (1) Prepare baseline: 100-count water-soluble vinylon filament;

[0078] (2) Preparation of carbon nanotube cylinders using floating catalyst chemical vapor deposition method:

[0079] A mixture of a catalyst precursor, a growth promoter, and a carbon source is fed through a peristaltic pump and carried into a reactor by a carrier gas for reaction to obtain a multi-walled carbon nanotube cylinder. The catalyst precursor is ferrocene, the growth promoter is thiophene, and the carbon source is ethanol. The mass ratio of the three is 98.8:0.6:0.6. The reaction temperature is 1300°C, and the carrier gas is high-purity nitrogen.

[0080] (3) The prepared carbon nanotube cylindrical object is coated on the surface of the baseline to obtain a composite fiber:

[0081] The base line is wetted with a solvent, and then the wetted base line is brought into contact with a carbon nanotube cylinder, thereby coating the base line surface with the carbon nanotube cylinder. The coating process is repeated twice to obtain a composite fiber, and then the composite fiber is continuously collected after being placed in a water bath and dried at 50° C. for 2 hours; wherein the solvent is ethanol, and the liquid content of the wetted base line surface is 20 wt%;

[0082] (4) Removing the baseline by water-soluble method to obtain carbon nanotube hollow fibers:

[0083] The composite fiber was placed in 100°C hot water for 1 h;

[0084] The finally obtained carbon nanotube hollow fiber has an inner diameter of 125±5 μm and a wall thickness of 8.3±0.5 μm.

[0085] In summary, the present invention uses water-soluble vinyl filaments as the baseline, coats carbon nanotubes on the surface of the baseline, and then removes the baseline through a water-soluble method to obtain a carbon nanotube hollow fiber with a dense and uniform surface. The inner diameter and wall thickness of the carbon nanotube hollow fiber can be controlled by adjusting the number of vinyl filaments and the number of coating repetitions.

[0086] The above embodiments are merely preferred embodiments for the purpose of fully illustrating the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are within the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

Claims

1. A method for continuously preparing size-adjustable carbon nanotube hollow fibers, characterized in that: The steps include: S1, using vinylon filament as the base, carbon nanotubes are coated on the base surface by physical coating method to obtain composite fibers; S2, removing the baseline of the composite fiber by a water-soluble method to obtain the size-adjustable carbon nanotube hollow fiber; The number of the vinylon filaments is 10-130, the inner diameter of the carbon nanotube hollow fiber is 100-500 μm, and the wall thickness is 2-50 μm; Before step S2, the method further includes: continuously collecting and drying the composite fibers after water bathing to achieve subsequent hollow fiber shaping, wherein the drying temperature is 50° C. and the drying time is 2 hours; The water-soluble method for removing the baseline specifically comprises placing the composite fiber in water at 90-100° C. for 1 hour.

2. The method for continuously preparing size-adjustable carbon nanotube hollow fibers according to claim 1, wherein: The carbon nanotubes are prepared by a floating catalyst chemical vapor deposition method.

3. The method for continuously preparing size-adjustable carbon nanotube hollow fibers according to claim 1, wherein: The coating specifically comprises: wetting the baseline with a solvent, then contacting the wetted baseline with carbon nanotubes, and coating the surface of the baseline with carbon nanotubes.

4. The method for continuously preparing size-adjustable carbon nanotube hollow fibers according to claim 3, wherein: The coating is repeated 0-19 times.

5. The method for continuously preparing size-adjustable carbon nanotube hollow fibers according to claim 3, wherein: The solvent is one or more of water, ethanol and acetone. 6 . A size-adjustable carbon nanotube hollow fiber prepared by the preparation method according to claim 1 .

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