Preparation method of modified single-walled carbon nanotube

Abstract

The invention relates to a preparation method of a modified single-walled carbon nanotube. The preparation method comprises the following steps: preparation of a catalyst precursor, pretreatment of a substrate, loading of the catalyst precursor, preparation of a single-walled carbon nanotube, plasma surface modification, coupling agent modification, preparation of a spinning solution and preparation of fibers. The preparation method creatively combines plasma synergistic modification, a coupling agent modification method and a chemical vapor deposition method to prepare the modified single-walled carbon nanotube; the prepared material has the advantages of being controllable in morphology and good in hydrophobicity and conductivity.

Description

TECHNICAL FIELD

[0001] The application relates to a preparation method of modified single-wall carbon nanotubes and belongs to the technical field of carbon nanotube preparation. BACKGROUND

[0002] Carbon nanotubes bring people endless surprises due to their unique structure and excellent performance, and people imagine that high-strength and high-toughness materials can be obtained with the participation of carbon nanotubes and applied to space elevators; wearable devices can be prepared by utilizing the easy bending property; and more extreme integrated circuit processes can be realized by replacing silicon-based materials with excellent nanoelectronic performance. Density, orientation and tube diameter are three important indicators for measuring carbon nanotube arrays, and the density and orientation mainly represent the morphology of the array and affect the processing of the sample; the tube diameter affects the performance of the device, and different tube diameters of carbon nanotubes have different band gaps, so the tube diameter needs to be controlled to realize specific purposes. Preparation determines the future, and a good material basis is a necessary step to realize application, and how to effectively control the structure and morphology of carbon nanotube growth is a great challenge at present. SUMMARY

[0003] In view of the above problems, the application provides a preparation method of modified single-wall carbon nanotubes.

[0004] The application relates to a preparation method of modified single-wall carbon nanotubes, which comprises the following steps: preparation of a catalyst precursor, pretreatment of a substrate, loading of the catalyst precursor, preparation of single-wall carbon nanotubes, plasma surface modification, coupling agent modification, preparation of a spinning solution and fiber preparation.

[0005] As preferred, step (1) preparation of the catalyst precursor

[0006] FeCl3 solid powder is weighed and dissolved in deionized water to prepare an FeCl3 solution; the FeCl3 solution is extracted by using a pipette, and deionized water is used for further dilution to obtain the required catalyst precursor;

[0007] Step (2) pretreatment of the substrate

[0008] Pretreatment: the single-crystal quartz sheet is sequentially ultrasonically cleaned in deionized water, acetone, ethanol and deionized water, dried by blowing high-purity nitrogen, and then placed in a muffle furnace for high-temperature annealing in an air atmosphere; constant temperature is maintained, then the temperature is lowered to a certain temperature by temperature control, and finally naturally cooled to room temperature; the silicon wafer is directly purchased;

[0009] Step (3) loading of the catalyst precursor

[0010] A small amount of the catalyst precursor solution in step (1) is dipped with a sewing needle, air-dried, and then quickly drawn on the surface of the substrate in step (2) to form a catalyst strip on the surface of the substrate;

[0011] Step (4) Single-walled carbon nanotube preparation

[0012] Put the catalyst-loaded substrate of step (3) into a quartz boat and push it into the constant temperature zone of the tube furnace. Raise the temperature in an air atmosphere, then introduce argon as a protective gas to remove the air in the quartz tube. When the predetermined growth temperature is reached, introduce hydrogen, then introduce methane as a carbon source using argon. Continue the growth, then shut off the carbon source and hydrogen. After waiting for the sample to cool to room temperature naturally, shut off the protective argon gas and take out the sample.

[0013] Step (5) Plasma surface modification

[0014] (1) Put the untreated carbon nanotube powder of step (4) into a clean and dry beaker and add an appropriate amount of deionized water for ultrasonic dispersion;

[0015] (2) Use a microporous filter membrane to suction filter the dispersed raw carbon nanotube solution and dry it to obtain a cylindrical single-walled carbon nanotube film to ensure uniformity of the modification;

[0016] (3) Before modification, use a mechanical vacuum pump to vacuumize the reaction kettle. Vacuumize it again and repeat the process 3-4 times to minimize the impact of residual waste gas on the modification process;

[0017] (4) Apply a voltage to the electrodes of the reaction kettle to trigger the discharge process. After the reaction is complete, store the treated single-walled carbon nanotubes in a sealed box for later use;

[0018] Step (6) Coupling agent modification

[0019] (1) Put the carbon nanotube powder treated by plasma in step (5) into an oven for drying;

[0020] (2) After the powder is dried, pour it into a clean and dry beaker A, add anhydrous ethanol, and use a glass rod to stir to achieve sufficient dilution. Then use a mechanical stirrer to stir the mixed solution while assisting with ultrasonic treatment and water bath heating to ensure uniform mixing;

[0021] (3) Prepare a coupling agent solution: Add KH560 to a clean and dry beaker B using a dropper, then add deionized water and anhydrous ethanol to the solution. Stir thoroughly until the solution changes from turbid to transparent. The carbon nanotube powder, coupling agent, deionized water, and anhydrous ethanol are added in a mass ratio;

[0022] (4) Pour the prepared KH560 solution (beaker B) into beaker A which has been stirred, and mechanically stir while using ultrasonic treatment and water bath heating. Continue stirring to ensure that the coupling agent and carbon nanotubes undergo sufficient chemical reaction;

[0023] (5) After the reaction is complete, filter the mixture and wash it several times to remove the silane coupling agent that did not participate in the reaction. Finally, dry the filtered solution, grind it into powder and store it in a sealed bag for later use.

[0024] Step (7) Preparation of spinning solution

[0025] First, the modified single-walled carbon nanotubes obtained in step (6) are pre-dispersed: SWCNTs (single-walled carbon nanotubes) collected from the tube furnace are mixed with H2O2 and stirred. Then, H2O2 is filtered out, and SWCNTs are washed with deionized water. The washed SWCNTs are mixed evenly with water, and the suspension is placed in a freeze dryer to dry completely to remove water and obtain loose and porous sponge-like SWCNTs. An appropriate amount of pre-dispersed SWCNTs is transferred to a glove box and mixed with chlorosulfonic acid under the protection of Ar atmosphere. The bottle mouth is sealed with sealing film to prevent chlorosulfonic acid from leaking and fuming in the air. The Ar atmosphere in the bottle is maintained. The chlorosulfonic acid / SWCNT mixture is planetarily stirred to make it evenly mixed and obtain SWCNT liquid crystal spinning solution.

[0026] Step (8) Fiber preparation

[0027] The SWCNT liquid crystal spinning solution obtained in step (7) is transferred to a stainless steel injection needle in a glove box under Ar atmosphere protection and fixed on the injection pump. The SWCNT liquid crystal spinning solution is injected into the acetone coagulation bath, and the tip of the syringe needle is immersed below the surface of the acetone coagulation bath. The fiber is taken out from the coagulation bath and wound onto the polytetrafluoroethylene roll of the winding device. After the liquid crystal spinning solution is injected, the fiber on the polytetrafluoroethylene roll is washed and dried to obtain dry SWCNT fiber.

[0028] Preferably, the method for preparing a modified single-walled carbon nanotube includes:

[0029] Step (1) Preparation of catalyst precursor

[0030] FeCl3 solid powder was weighed and dissolved in deionized water to prepare FeCl3 solution. The FeCl3 solution was then extracted using a pipette and diluted again with deionized water to obtain the desired catalyst precursor.

[0031] Step (2) Substrate pretreatment

[0032] Pretreatment: The single-crystal quartz wafers are ultrasonically cleaned sequentially in deionized water, acetone, ethanol, and deionized water. After being dried with high-purity nitrogen, they are placed in a muffle furnace and annealed at high temperature in an air atmosphere. The temperature is kept constant, then the temperature is controlled to drop to a certain temperature, and finally cooled naturally to room temperature. The silicon wafers are purchased directly.

[0033] Step (3) Loading of catalyst precursor

[0034] Dip a sewing needle into a small amount of the catalyst precursor solution from step (1), let it air dry, and then quickly swipe it across the substrate surface from step (2) to form a catalyst strip on the substrate surface.

[0035] Step (4) Preparation of single-walled carbon nanotubes

[0036] Place the substrate loaded with catalyst in step (3) on a quartz boat, push it into the constant temperature zone of the tube furnace, heat it in an air atmosphere, then introduce argon as a protective gas to expel the air in the quartz tube, after reaching the predetermined growth temperature, introduce hydrogen, then use argon to introduce methane to blow in the carbon source, continue growth, then turn off the carbon source and hydrogen, wait for natural cooling to room temperature, then turn off the protective argon gas and take out the sample;

[0037] Step (5) Plasma surface modification

[0038] (1) Weigh the untreated carbon nanotube powder from step (4) into a clean and dry beaker and add an appropriate amount of deionized water for ultrasonic dispersion;

[0039] (2) The dispersed original carbon nanotube solution was filtered by microporous filter membrane and dried to obtain a cylindrical single-walled carbon nanotube film to ensure the uniformity of modification.

[0040] (3) Before modification, the reactor is evacuated by a mechanical vacuum pump and then evacuated again. This process is repeated 3-4 times to minimize the impact of residual waste gas on the modification process.

[0041] (4) Apply voltage to the electrodes of the reactor to trigger the discharge process. After the reaction is completed, store the treated single-walled carbon nanotubes in a sealed box for later use.

[0042] Step (6) Coupling agent modification

[0043] (1) Weigh the carbon nanotube powder that has been plasma-treated in step (5) and put it into an oven to dry for later use;

[0044] (2) After the powder is dried, pour the powder into a clean and dry beaker A, add anhydrous ethanol, and stir with a glass rod to achieve full dilution; then use a mechanical stirrer to stir the mixed solution, while supplementing with ultrasonic treatment and water bath heating to ensure uniform mixing.

[0045] (3) Preparation of coupling agent solution: KH560 is added to a clean and dry beaker B through a dropper. Then, deionized water and anhydrous ethanol are added to the solution and stirred thoroughly until the solution changes from turbid to transparent. The carbon nanotube powder, coupling agent, deionized water and anhydrous ethanol are added in the mass ratio.

[0046] (4) Pour the prepared KH560 solution (beaker B) into the stirred beaker A, stir mechanically, and simultaneously use ultrasound and water bath heating to continuously stir to ensure that the coupling agent and carbon nanotubes undergo a full chemical reaction.

[0047] (5) After the reaction is complete, filter the mixture and wash it several times to remove the silane coupling agent that did not participate in the reaction. Finally, dry the filtered solution, grind it into powder and store it in a sealed bag for later use.

[0048] Step (7) Preparation of spinning solution

[0049] First, the modified single-walled carbon nanotubes obtained in step (6) are pre-dispersed: SWCNTs (single-walled carbon nanotubes) collected from the tube furnace are mixed with H2O2 and stirred. Then, H2O2 is filtered out, and SWCNTs are washed with deionized water. The washed SWCNTs are mixed evenly with water, and the suspension is placed in a freeze dryer to dry completely to remove water and obtain loose and porous sponge-like SWCNTs. An appropriate amount of pre-dispersed SWCNTs is transferred to a glove box and mixed with chlorosulfonic acid under the protection of Ar atmosphere. The bottle mouth is sealed with sealing film to prevent chlorosulfonic acid from leaking and fuming in the air. The Ar atmosphere in the bottle is maintained. The chlorosulfonic acid / SWCNT mixture is planetarily stirred to make it evenly mixed and obtain SWCNT liquid crystal spinning solution.

[0050] Step (8) Fiber preparation

[0051] The SWCNT liquid crystal spinning solution obtained in step (7) is transferred to a stainless steel injection needle in a glove box under Ar atmosphere protection and fixed on the injection pump. The SWCNT liquid crystal spinning solution is injected into the acetone coagulation bath, and the tip of the syringe needle is immersed below the surface of the acetone coagulation bath. The fiber is taken out from the coagulation bath and wound onto the polytetrafluoroethylene roll of the winding device. After the liquid crystal spinning solution is injected, the fiber on the polytetrafluoroethylene roll is washed and dried to obtain dry SWCNT fiber.

[0052] Preferably, step (1) involves the preparation of the catalyst precursor.

[0053] Weigh 2-3g of FeCl3 solid powder and dissolve it in 30-50 mL of deionized water to prepare a 0.3-0.6 mol / L FeCl3 solution. Use a pipette to extract 100-200 μL of the FeCl3 solution and dilute it again with 2-5 mL of deionized water to a 0.05-0.1 mol / L FeCl3 solution to obtain the desired catalyst precursor.

[0054] Preferably, step (2) involves substrate pretreatment.

[0055] Pretreatment: The single-crystal quartz wafer is ultrasonically cleaned sequentially in deionized water, acetone, ethanol, and deionized water for 10-15 minutes. After drying with high-purity nitrogen, it is placed in a muffle furnace and annealed at high temperature in air atmosphere at 800-900℃ for 6-10 hours. Subsequently, the temperature is reduced to 300-400℃ over 8-10 hours by a temperature control program, and finally cooled naturally to room temperature. The silicon wafer is a 1*1-2*2 cm silicon wafer with an 80-90 nm thick oxide layer and photolithographic markings. It is ultrasonically cleaned sequentially in deionized water, acetone, ethanol, and deionized water for 10-15 minutes and then dried with high-purity nitrogen before use.

[0056] Preferably, step (3) involves loading the catalyst precursor.

[0057] Dip a sewing needle into a small amount of the catalyst precursor solution from step (1), let it air dry, and then quickly swipe it across the substrate surface from step (2) to form catalyst strips on the substrate surface.

[0058] The advantage of this invention is that it forms a [missing information - likely a type of surface treatment] on the quartz surface using a mechanical scribing method.

[0059] Confining the catalyst to a specific area by using catalyst strips reduces collisions between carbon nanotubes and the catalyst, thus minimizing the appearance of disordered carbon nanotubes. Since the catalyst strips are perpendicular to the crystal lattice, only lattice-oriented carbon nanotubes can grow from within the strips, resulting in a well-aligned array.

[0060] As a preferred option, step (4) involves the preparation of single-walled carbon nanotubes.

[0061] Place the substrate loaded with catalyst in step (3) on a quartz boat and push it into the constant temperature zone of the tube furnace. Heat it in an air atmosphere for 20-30 min, then introduce argon gas as a protective gas to purge the air from the quartz tube for about 10-20 min. After reaching the predetermined growth temperature, introduce hydrogen gas for 15-20 min to reduce the catalyst precursor to Fe nanoparticles. Then, use argon gas to introduce methane (with a small amount of water added; some studies suggest that water helps enrich semiconductor nanotubes) to swell the carbon source. Continue growth for 15-20 min, then turn off the carbon source and hydrogen gas. After waiting for it to cool naturally to room temperature, turn off the protective argon gas and remove the sample.

[0062] The advantages of this invention are that three gases are introduced during the growth process. Argon acts as a protective gas with minimal impact on growth, while hydrogen has a reducing effect on the catalyst and can prevent the formation of some amorphous carbon. The carbon source gas provides the carbon atoms required for carbon nanotube growth. If the amount of carbon source is too small, the number of carbon atoms that can be broken down on the catalyst surface will decrease accordingly, thus inhibiting the nucleation and growth of carbon nanotubes. Conversely, if the amount of carbon source is too large, the excessive carbon atoms may form amorphous carbon, leading to catalyst deactivation.

[0063] Preferably, step (5) involves plasma surface modification.

[0064] (1) Weigh 5-10g of the untreated carbon nanotube powder from step (4) into a clean and dry beaker and add 50-100mL of deionized water. Disperse the powder by ultrasonication for 20-40 min.

[0065] (2) The dispersed original carbon nanotube solution was filtered by microporous filter membrane and dried at 60-80℃ for 8-10h to obtain a cylindrical single-walled carbon nanotube film with a thickness of 0.3-0.5 mm and a diameter of 30-40 mm to ensure the uniformity of modification.

[0066] (3) Before modification, the reactor should be evacuated using a mechanical vacuum pump to ensure that the internal pressure of the reactor is less than 2×10⁻⁶. -3 -2.8×10 -3 After vacuuming again, CO2 gas is introduced to bring the pressure in the reactor to 8-10 kPa. CO2 gas is added again until the pressure inside the reactor reaches 10-15 kPa. Vacuuming is repeated 3-4 times to minimize the impact of residual waste gas on the modification process.

[0067] (4) Apply a voltage of 20-28kV to the electrodes of the reactor and output a frequency of 6-9kHz to trigger the discharge process. The discharge time is 0-20min. After the reaction is completed, store the treated single-walled carbon nanotubes in a sealed box for later use.

[0068] Preferably, step (6) involves modification of the coupling agent.

[0069] (1) Weigh 5-10g of the carbon nanotube powder that has been plasma-treated in step (5) and put it into an oven to dry for later use;

[0070] (2) After the powder is dried, pour the powder into a clean and dry beaker A, add 40-50 mL of anhydrous ethanol, and stir with a glass rod to achieve full dilution; then use a mechanical stirrer to stir the mixed solution at a speed of about 5000-8000 r / min for 20-30 min, while supplementing with ultrasonic treatment and water bath heating at 40-50℃ to ensure uniform mixing;

[0071] (3) Preparation of coupling agent solution: Add 5-10g KH560 to a clean and dry beaker B through a dropper, then add 50-100mL of deionized water and anhydrous ethanol to the solution, and stir thoroughly until the solution changes from turbid to transparent. The mass ratio of carbon nanotube powder, coupling agent, deionized water and anhydrous ethanol used is 10:3:2:1-20:2:1:7.

[0072] (4) Pour the prepared KH560 solution (beaker B) into the stirred beaker A, and continue to mechanically stir at a speed of about 5000-6000 r / min. At the same time, use ultrasound and a water bath at 40-50℃ to heat the mixture for more than 40-60 min to ensure that the coupling agent and carbon nanotubes undergo a full chemical reaction.

[0073] (5) After the reaction is complete, filter the mixture and wash it several times to remove the silane coupling agent that did not participate in the reaction. Finally, place the filtered solution in an oven at 60-80°C for drying, then grind it into powder and store it in a sealed bag for later use.

[0074] The advantage of this invention is that the morphology of the carbon nanotube surface does not change under different treatment methods, which indicates that the two modification methods are relatively mild and will not damage the microstructure of CNTs. The CNTs treated with plasma and KH560 coupling agent have a looser structure, distinct ends, and significantly reduced entanglement and aggregation, which has a positive effect on improving the dispersibility of CNTs.

[0075] The advantages of this invention are that plasma treatment successfully introduces abundant -COOH and -OH polar functional groups onto the surface of CNTs. These functional groups significantly enhance the dispersibility of CNTs in polar solvents and effectively prevent aggregation between CNTs. After coupling agent treatment, the KH560 modified layer of the CNTs can act as a physical barrier, preventing excessive proximity and re-aggregation between CNTs, thereby maintaining the stability of the dispersion system.

[0076] Preferably, step (7) involves the preparation of the spinning solution.

[0077] First, the modified single-walled carbon nanotubes obtained in step (6) are pre-dispersed: the SWCNTs (single-walled carbon nanotubes) collected from the tube furnace are mixed with 20-30% H2O2 at a ratio of 1-4 mg SWCNT: 2-6 mL H2O2, and stirred magnetically at a rate of 400-500 rpm for 10-20 min. Then, the H2O2 is filtered out, and the SWCNTs are washed with deionized water. The washed SWCNTs are then mixed with 1-3 mg H2O2. SWCNTs were uniformly mixed with 1-3 mL of water, and the suspension was placed in a freeze dryer and dried for 30-36 hours to completely remove water, resulting in loose and porous sponge-like SWCNTs. 2-4 g of pre-dispersed SWCNTs were transferred to a glove box and mixed with 3-6 mL of chlorosulfonic acid under an Ar atmosphere. The bottle mouth was sealed with sealing film to prevent chlorosulfonic acid from leaking and fuming in the air. The Ar atmosphere inside the bottle was maintained. The chlorosulfonic acid / SWCNT mixture was planetarily stirred at 2000-3000 rpm to ensure uniform mixing, thus obtaining the SWCNT liquid crystal spinning solution.

[0078] Preferably, step (8) fiber preparation

[0079] The SWCNT liquid crystal spinning solution obtained in step (7) was transferred to a stainless steel injection needle in a glove box under Ar atmosphere protection, and fixed on the injection pump. The SWCNT liquid crystal spinning solution was then injected at a rate of 0.03-0.07 mL / min. -1 The liquid crystal spinning solution is injected into the acetone coagulation bath at a certain speed, with the syringe needle tip immersed 1-2 cm below the surface of the acetone coagulation bath. The fiber is then removed from the coagulation bath and wound onto the polytetrafluoroethylene (PTFE) roll of the winding equipment. After the liquid crystal spinning solution is injected, the fiber on the PTFE roll is washed with water and dried at 100-110°C to obtain dry SWCNT fiber.

[0080] In summary, the beneficial effects of this invention are as follows:

[0081] 1. The advantage of using this invention is that it forms a [missing information - likely a type of surface treatment] on the quartz surface using a mechanical scratching method.

[0082] Confining the catalyst to a specific area by using catalyst strips reduces collisions between carbon nanotubes and the catalyst, thus minimizing the appearance of disordered carbon nanotubes. Since the catalyst strips are perpendicular to the crystal lattice, only lattice-oriented carbon nanotubes can grow from within the strips, resulting in a well-aligned array.

[0083] 2. The advantages of this invention are that three gases are introduced during the growth process. Argon acts as a protective gas with minimal impact on growth, while hydrogen has a reducing effect on the catalyst and can prevent the formation of some amorphous carbon. The carbon source gas provides the carbon atoms required for carbon nanotube growth. If the amount of carbon source is too small, the number of carbon atoms that can be broken down on the catalyst surface will decrease accordingly, thus inhibiting the nucleation and growth of carbon nanotubes. Conversely, if the amount of carbon source is too large, the excessive carbon atoms may form amorphous carbon, leading to catalyst deactivation.

[0084] 3. The advantage of using this invention is that the morphology of the carbon nanotube surface does not change under different treatment methods, which indicates that the two modification methods are relatively mild and will not damage the microstructure of CNTs. The CNTs treated with plasma and KH560 coupling agent have a looser structure, distinct ends, and significantly reduced entanglement and aggregation, which has a positive effect on improving the dispersibility of CNTs.

[0085] 4. The advantages of this invention are that plasma treatment successfully introduces abundant -COOH and -OH polar functional groups onto the surface of CNTs. These functional groups significantly enhance the dispersibility of CNTs in polar solvents and effectively prevent aggregation between CNTs. After treatment with the coupling agent, the KH560 modified layer of the CNTs can act as a physical barrier to prevent excessive proximity and re-aggregation between CNTs, thereby maintaining the stability of the dispersion system. Attached Figure Description

[0086] Figure 1 This is a flowchart of a method for preparing modified single-walled carbon nanotubes. Detailed Implementation

[0087] Example 1

[0088] like Figure 1 As shown, the preparation method of modified single-walled carbon nanotubes includes:

[0089] Step (1) Preparation of catalyst precursor

[0090] Weigh 2g of FeCl3 solid powder and dissolve it in 30 mL of deionized water to prepare a 0.3mol / L FeCl3 solution. Use a pipette to draw 100μL of the FeCl3 solution and dilute it again with 2mL of deionized water to a 0.05mol / L FeCl3 solution to obtain the desired catalyst precursor.

[0091] Step (2) Substrate pretreatment

[0092] Pretreatment: The single crystal quartz wafer was ultrasonically cleaned in deionized water, acetone, ethanol and deionized water for 10 min in sequence. After being dried with high-purity nitrogen, it was placed in a muffle furnace and annealed at high temperature in air atmosphere at 800℃ for 6 hours. Then, the temperature was reduced to 300℃ within 8 hours by a temperature control program. Finally, it was allowed to cool naturally to room temperature.

[0093] Step (3) Loading of catalyst precursor

[0094] Dip a sewing needle into a small amount of the catalyst precursor solution from step (1), let it air dry, and then quickly swipe it across the substrate surface from step (2) to form catalyst strips on the substrate surface.

[0095] Step (4) Preparation of single-walled carbon nanotubes

[0096] Place the substrate loaded with catalyst in step (3) on a quartz boat and push it into the constant temperature zone of the tube furnace. Heat it in an air atmosphere for 20 min, then introduce argon as a protective gas to purge the air from the quartz tube for about 10 min. After reaching the predetermined growth temperature, introduce hydrogen for 15 min to reduce the catalyst precursor to Fe nanoparticles. Then, use argon to introduce methane (with a small amount of water added; some studies suggest that water helps enrich semiconductor nanotubes) to swell the carbon source. Continue growth for 15 min, then turn off the carbon source and hydrogen. After waiting for it to cool naturally to room temperature, turn off the protective argon gas and remove the sample.

[0097] Step (5) Plasma surface modification

[0098] (1) Weigh 5g of the untreated carbon nanotube powder from step (4) into a clean and dry beaker and add 50mL of deionized water, and then ultrasonically disperse for 20 min.

[0099] (2) The dispersed original carbon nanotube solution was filtered by microporous filter membrane and dried at 60°C for 8 h to obtain a cylindrical single-walled carbon nanotube film with a thickness of 0.3 mm and a diameter of 30 mm to ensure the uniformity of modification.

[0100] (3) Before modification, the reactor should be evacuated using a mechanical vacuum pump to ensure that the internal pressure of the reactor is less than 2×10⁻⁶. -3 After vacuuming again, CO2 gas is introduced to bring the pressure in the reactor to 8 kPa. CO2 gas is added again until the pressure inside the reactor reaches 10 kPa. Vacuuming is repeated 3-4 times to minimize the impact of residual waste gas on the modification process.

[0101] (4) Apply a voltage of 20kV to the electrodes of the reactor and output a frequency of 6kHz to trigger the discharge process. The discharge time is 0min. After the reaction is completed, store the treated single-walled carbon nanotubes in a sealed box for later use.

[0102] Step (6) Coupling agent modification

[0103] (1) Weigh 5g of the carbon nanotube powder that has been plasma-treated in step (5) and put it into an oven to dry for later use;

[0104] (2) After the powder is dried, pour the powder into a clean and dry beaker A, add 40 mL of anhydrous ethanol, and stir with a glass rod to achieve full dilution; then use a mechanical stirrer to stir the mixed solution at a speed of about 5000 r / min for 20 min, while supplementing with ultrasonic treatment and water bath heating at 40°C to ensure uniform mixing.

[0105] (3) Preparation of coupling agent solution: Add 5g KH560 to a clean and dry beaker B through a dropper, then add 50mL of deionized water and anhydrous ethanol to the solution, and stir thoroughly until the solution changes from turbid to transparent. The mass ratio of carbon nanotube powder, coupling agent, deionized water and anhydrous ethanol used is 10:3:2:1.

[0106] (4) Pour the prepared KH560 solution (beaker B) into the stirred beaker A, continue to mechanically stir at a speed of about 5000 r / min, and use ultrasound and a 40°C water bath for heating. Continue stirring for more than 40 min to ensure that the coupling agent and carbon nanotubes undergo a full chemical reaction.

[0107] (5) After the reaction is complete, filter the mixture and wash it several times to remove the unreacted silane coupling agent. Finally, place the filtered solution in an oven at 60°C to dry it, then grind it into powder and store it in a sealed bag for later use.

[0108] Step (7) Preparation of spinning solution

[0109] First, the modified single-walled carbon nanotubes obtained in step (6) are pre-dispersed: SWCNTs (single-walled carbon nanotubes) collected from the tube furnace are mixed with 20% H2O2 at a ratio of 1 mg SWCNT: 2 mL H2O2, and stirred magnetically at a speed of 400 rpm for 10 min. Then, the H2O2 is filtered out, and the SWCNTs are washed with deionized water. The washed SWCNTs are mixed evenly at a ratio of 1 mg SWCNT: 1 mL water. The suspension is placed in a freeze dryer and dried for 30 h to completely remove water, resulting in loose and porous sponge-like SWCNTs. 2 g of pre-dispersed SWCNTs are transferred to a glove box and mixed with 3 mL of chlorosulfonic acid under the protection of Ar atmosphere. The bottle mouth is sealed with sealing film to prevent chlorosulfonic acid from leaking and fuming in the air. The Ar atmosphere inside the bottle is maintained. The chlorosulfonic acid / SWCNT mixture is planetarily stirred at a speed of 2000 rpm to make it evenly mixed, resulting in SWCNT liquid crystal spinning solution.

[0110] Step (8) Fiber preparation

[0111] The SWCNT liquid crystal spinning solution obtained in step (7) was transferred to a stainless steel injection needle in a glove box under Ar atmosphere protection, and fixed on the injection pump. The SWCNT liquid crystal spinning solution was then injected at a rate of 0.03 mL / min. -1 The liquid crystal spinning solution is injected into the acetone coagulation bath at a certain speed, with the syringe needle tip immersed 1 cm below the surface of the acetone coagulation bath. The fiber is then removed from the coagulation bath and wound onto the polytetrafluoroethylene (PTFE) roll of the winding equipment. After the liquid crystal spinning solution is injected, the fiber on the PTFE roll is washed with water and dried at 100°C to obtain dry SWCNT fiber.

[0112] Example 2

[0113] Step (1) Preparation of catalyst precursor

[0114] Weigh 2g of FeCl3 solid powder and dissolve it in 40 mL of deionized water to prepare a 0.4mol / L FeCl3 solution. Use a pipette to extract 100-200μL of the FeCl3 solution and dilute it again with 4mL of deionized water to a 0.07mol / L FeCl3 solution to obtain the desired catalyst precursor.

[0115] Step (2) Substrate pretreatment

[0116] Pretreatment: The single crystal quartz wafer was ultrasonically cleaned in deionized water, acetone, ethanol and deionized water for 13 min in sequence. After being dried with high-purity nitrogen, it was placed in a muffle furnace and annealed at high temperature in air atmosphere at 830℃ for 7 hours. Then, the temperature was reduced to 320℃ within 8 hours by a temperature control program. Finally, it was allowed to cool naturally to room temperature.

[0117] Step (3) Loading of catalyst precursor

[0118] Dip a sewing needle into a small amount of the catalyst precursor solution from step (1), let it air dry, and then quickly swipe it across the substrate surface from step (2) to form catalyst strips on the substrate surface.

[0119] Step (4) Preparation of single-walled carbon nanotubes

[0120] Place the substrate loaded with catalyst in step (3) on a quartz boat and push it into the constant temperature zone of the tube furnace. Heat it in an air atmosphere for 25 min, then introduce argon as a protective gas to purge the air from the quartz tube for about 15 min. After reaching the predetermined growth temperature, introduce hydrogen for 16 min to reduce the catalyst precursor to Fe nanoparticles. Then, use argon to introduce methane (with a small amount of water added; some studies suggest that water helps enrich semiconductor nanotubes) to swell the carbon source. Continue growth for 18 min, then turn off the carbon source and hydrogen. After waiting for it to cool naturally to room temperature, turn off the protective argon gas and remove the sample.

[0121] Step (5) Plasma surface modification

[0122] (1) Weigh 7g of the untreated carbon nanotube powder from step (4) into a clean and dry beaker and add 60mL of deionized water. Disperse the powder by ultrasonication for 25 min.

[0123] (2) The dispersed original carbon nanotube solution was filtered by microporous filter membrane and dried at 70°C for 8 hours to obtain a cylindrical single-walled carbon nanotube film with a thickness of 0.4 mm and a diameter of 35 mm, so as to ensure the uniformity of modification.

[0124] (3) Before modification, the reactor should be evacuated using a mechanical vacuum pump to ensure that the internal pressure of the reactor is less than 2.4 × 10⁻⁶. -3 After vacuuming again, CO2 gas is introduced to bring the pressure in the reactor to 9 kPa. CO2 gas is added again until the pressure inside the reactor reaches 12 kPa. Vacuuming is repeated, and the cycle is repeated 3 times to minimize the impact of residual waste gas on the modification process.

[0125] (4) Apply a voltage of 24kV to the electrodes of the reactor and output a frequency of 7kHz to trigger the discharge process. The discharge time is 10min. After the reaction is completed, store the treated single-walled carbon nanotubes in a sealed box for later use.

[0126] Step (6) Coupling agent modification

[0127] (1) Weigh 6g of the carbon nanotube powder that has been plasma-treated in step (5) and put it into an oven to dry for later use;

[0128] (2) After the powder is dried, pour the powder into a clean and dry beaker A, add 45 mL of anhydrous ethanol, and stir with a glass rod to achieve full dilution; then use a mechanical stirrer to stir the mixed solution at a speed of about 6000 r / min for 25 min, while supplementing with ultrasonic treatment and water bath heating at 44℃ to ensure uniform mixing.

[0129] (3) Preparation of coupling agent solution: Add 6g KH560 to a clean and dry beaker B through a dropper, then add 60mL of deionized water and anhydrous ethanol to the solution, and stir thoroughly until the solution changes from turbid to transparent. The mass ratio of carbon nanotube powder, coupling agent, deionized water and anhydrous ethanol used is 10:3:2:1.

[0130] (4) Pour the prepared KH560 solution (beaker B) into the stirred beaker A, continue to mechanically stir at a speed of about 5500 r / min, and simultaneously use ultrasound and a 45°C water bath for heating, and continue stirring for more than 50 min to ensure that the coupling agent and carbon nanotubes undergo a full chemical reaction.

[0131] (5) After the reaction is complete, filter the mixture and wash it several times to remove the silane coupling agent that did not participate in the reaction. Finally, place the filtered solution in an oven at 65°C for drying, then grind it into powder and store it in a sealed bag for later use.

[0132] Step (7) Preparation of spinning solution

[0133] First, the modified single-walled carbon nanotubes obtained in step (6) are pre-dispersed: SWCNTs (single-walled carbon nanotubes) collected from the tube furnace are mixed with 25% H2O2 at a ratio of 2mg SWCNT:4mL H2O2, and stirred magnetically at a speed of 440rpm for 15min. Then, the H2O2 is filtered out, and the SWCNTs are washed with deionized water. The washed SWCNTs are mixed evenly at a ratio of 3mg SWCNT:2mL water. The suspension is placed in a freeze dryer and dried for 33h to completely remove water, resulting in loose and porous sponge-like SWCNTs. 3g of pre-dispersed SWCNTs are transferred to a glove box and mixed with 4mL of chlorosulfonic acid under the protection of Ar atmosphere. The bottle mouth is sealed with sealing film to prevent chlorosulfonic acid from leaking and fuming in the air. The Ar atmosphere inside the bottle is maintained. The chlorosulfonic acid / SWCNT mixture is planetarily stirred at a speed of 2500rpm to make it evenly mixed, resulting in SWCNT liquid crystal spinning solution.

[0134] Step (8) Fiber preparation

[0135] The SWCNT liquid crystal spinning solution obtained in step (7) was transferred to a stainless steel injection needle in a glove box under Ar atmosphere protection, and fixed on the injection pump. The SWCNT liquid crystal spinning solution was then injected at a rate of 0.04 mL / min. -1 The liquid crystal spinning solution is injected into the acetone coagulation bath at a certain speed, with the syringe needle tip immersed less than 1 cm below the surface of the acetone coagulation bath. The fiber is then removed from the coagulation bath and wound onto the polytetrafluoroethylene (PTFE) roll of the winding equipment. After the liquid crystal spinning solution is injected, the fiber on the PTFE roll is washed with water and dried at 105°C to obtain dry SWCNT fiber.

[0136] Example 3

[0137] Step (1) Preparation of catalyst precursor

[0138] Weigh 3g of FeCl3 solid powder and dissolve it in 46 mL of deionized water to prepare a 0.5mol / L FeCl3 solution. Use a pipette to draw 180μL of the FeCl3 solution and dilute it again with 4mL of deionized water to a 0.08mol / L FeCl3 solution to obtain the desired catalyst precursor.

[0139] Step (2) Substrate pretreatment

[0140] Pretreatment: The single crystal quartz wafer was ultrasonically cleaned in deionized water, acetone, ethanol and deionized water for 15 min in sequence. After being dried with high-purity nitrogen, it was placed in a muffle furnace and annealed at high temperature in air atmosphere at 880℃ for 9 hours. Then, the temperature was reduced to 380℃ over 10 hours by a temperature control program. Finally, it was allowed to cool naturally to room temperature.

[0141] Step (3) Loading of catalyst precursor

[0142] Dip a sewing needle into a small amount of the catalyst precursor solution from step (1), let it air dry, and then quickly swipe it across the substrate surface from step (2) to form catalyst strips on the substrate surface.

[0143] Step (4) Preparation of single-walled carbon nanotubes

[0144] Place the substrate loaded with catalyst in step (3) on a quartz boat and push it into the constant temperature zone of the tube furnace. Heat it in an air atmosphere for 28 min, then introduce argon gas as a protective gas to purge the air from the quartz tube for about 18 min. After reaching the predetermined growth temperature, introduce hydrogen gas for 18 min to reduce the catalyst precursor to Fe nanoparticles. Then, use argon gas to introduce methane (with a small amount of water added; some studies suggest that water helps enrich semiconductor nanotubes) to swell the carbon source. Continue growth for 18 min, then turn off the carbon source and hydrogen gas. After waiting for it to cool naturally to room temperature, turn off the protective argon gas and take out the sample.

[0145] Step (5) Plasma surface modification

[0146] (1) Weigh 8g of the untreated carbon nanotube powder from step (4) into a clean and dry beaker and add 80mL of deionized water, and then ultrasonically disperse for 35 min.

[0147] (2) The dispersed original carbon nanotube solution was filtered by microporous filter membrane and dried at 75°C for 9 hours to obtain a cylindrical single-walled carbon nanotube film with a thickness of 0.5 mm and a diameter of 38 mm, so as to ensure the uniformity of modification.

[0148] (3) Before modification, the reactor should be evacuated using a mechanical vacuum pump to ensure that the internal pressure of the reactor is less than 2.6 × 10⁻⁶. -3 After vacuuming again, CO2 gas is introduced to bring the pressure in the reactor to 9 kPa. CO2 gas is added again until the pressure inside the reactor reaches 14 kPa. Vacuuming is repeated, and this cycle is repeated 4 times to minimize the impact of residual waste gas on the modification process.

[0149] (4) Apply a voltage of 25kV to the electrodes of the reactor and output a frequency of 8kHz to trigger the discharge process. The discharge time is 15min. After the reaction is completed, store the treated single-walled carbon nanotubes in a sealed box for later use.

[0150] Step (6) Coupling agent modification

[0151] (1) Weigh 8g of the carbon nanotube powder that has been plasma-treated in step (5) and put it into an oven to dry for later use;

[0152] (2) After the powder is dried, pour the powder into a clean and dry beaker A, add 48 mL of anhydrous ethanol, and stir with a glass rod to achieve full dilution; then use a mechanical stirrer to stir the mixed solution at a speed of about 7000 r / min for 28 min, while supplementing with ultrasonic treatment and water bath heating at 48°C to ensure uniform mixing.

[0153] (3) Preparation of coupling agent solution: Add 8g KH560 to a clean and dry beaker B through a dropper, then add 58mL of deionized water and anhydrous ethanol to the solution, and stir thoroughly until the solution changes from turbid to transparent. The mass ratio of carbon nanotube powder, coupling agent, deionized water and anhydrous ethanol used is 20:2:1:7.

[0154] (4) Pour the prepared KH560 solution (beaker B) into the stirred beaker A, continue to mechanically stir at a speed of about 5800 r / min, and simultaneously use ultrasound and a 46°C water bath for heating, and continue stirring for more than 55 min to ensure that the coupling agent and carbon nanotubes undergo a full chemical reaction.

[0155] (5) After the reaction is complete, filter the mixture and wash it several times to remove the silane coupling agent that did not participate in the reaction. Finally, place the filtered solution in an oven at 75°C for drying, then grind it into powder and store it in a sealed bag for later use.

[0156] Step (7) Preparation of spinning solution

[0157] First, the modified single-walled carbon nanotubes obtained in step (6) are pre-dispersed: SWCNTs (single-walled carbon nanotubes) collected from the tube furnace are mixed with 28% H2O2 at a ratio of 3 mg SWCNT: 5 mL H2O2. The mixture is magnetically stirred at a speed of 480 rpm for 18 min. Then, the H2O2 is filtered out, and the SWCNTs are washed with deionized water. The washed SWCNTs are uniformly mixed at a ratio of 2 mg SWCNT: 2 mL water. The suspension is placed in a freeze dryer and dried for 34 h to completely remove the water, resulting in loose and porous sponge-like SWCNTs. 4 g of the pre-dispersed SWCNTs are transferred to a glove box and mixed with 5 mL of chlorosulfonic acid under an Ar atmosphere. The bottle mouth is sealed with a sealing film to prevent chlorosulfonic acid from leaking and fuming in the air. The Ar atmosphere inside the bottle is maintained. The chlorosulfonic acid / SWCNT mixture is planetarily stirred at a speed of 2800 rpm to make it uniformly mixed, resulting in SWCNT liquid crystal spinning solution.

[0158] Step (8) Fiber preparation

[0159] The SWCNT liquid crystal spinning solution obtained in step (7) was transferred to a stainless steel injection needle in a glove box under Ar atmosphere protection, and fixed on the injection pump. The SWCNT liquid crystal spinning solution was then injected at a rate of 0.05 mL / min. -1 The liquid crystal spinning solution is injected into the acetone coagulation bath at a certain speed, with the syringe needle tip immersed less than 1 cm below the surface of the acetone coagulation bath. The fiber is then removed from the coagulation bath and wound onto the polytetrafluoroethylene (PTFE) roll of the winding equipment. After the liquid crystal spinning solution is injected, the fiber on the PTFE roll is washed with water and dried at 108°C to obtain dry SWCNT fiber.

[0160] Example 4

[0161] Step (1) Preparation of catalyst precursor

[0162] Weigh 3g of FeCl3 solid powder and dissolve it in 50 mL of deionized water to prepare a 0.6 mol / L FeCl3 solution. Use a pipette to draw 200 μL of the FeCl3 solution and dilute it again with 5 mL of deionized water to a 0.1 mol / L FeCl3 solution to obtain the desired catalyst precursor.

[0163] Step (2) Substrate pretreatment

[0164] Pretreatment: The single crystal quartz wafer was ultrasonically cleaned in deionized water, acetone, ethanol and deionized water for 15 min in sequence. After being dried with high-purity nitrogen, it was placed in a muffle furnace and annealed at high temperature in air atmosphere at 900℃ for 10 hours. Then, the temperature was reduced to 400℃ within 10 hours by a temperature control program. Finally, it was allowed to cool naturally to room temperature.

[0165] Step (3) Loading of catalyst precursor

[0166] Dip a sewing needle into a small amount of the catalyst precursor solution from step (1), let it air dry, and then quickly swipe it across the substrate surface from step (2) to form catalyst strips on the substrate surface.

[0167] Step (4) Preparation of single-walled carbon nanotubes

[0168] Place the substrate loaded with catalyst in step (3) on a quartz boat and push it into the constant temperature zone of the tube furnace. Heat it in an air atmosphere for 30 min, then introduce argon gas as a protective gas to purge the air from the quartz tube for about 20 min. After reaching the predetermined growth temperature, introduce hydrogen gas for 20 min to reduce the catalyst precursor to Fe nanoparticles. Then, use argon gas to introduce methane (with a small amount of water added; some studies suggest that water helps enrich semiconductor nanotubes) to swell the carbon source. Continue growth for 20 min, then turn off the carbon source and hydrogen gas. After waiting for it to cool naturally to room temperature, turn off the protective argon gas and take out the sample.

[0169] Step (5) Plasma surface modification

[0170] (1) Weigh 10g of the untreated carbon nanotube powder from step (4) into a clean and dry beaker and add 100mL of deionized water. Disperse the powder by ultrasonication for 40 min.

[0171] (2) The dispersed original carbon nanotube solution was filtered by microporous filter membrane and dried at 80°C for 10 h to obtain a cylindrical single-walled carbon nanotube film with a thickness of 0.5 mm and a diameter of 40 mm, so as to ensure the uniformity of modification.

[0172] (3) Before modification, the reactor should be evacuated using a mechanical vacuum pump to ensure that the internal pressure of the reactor is less than 2.8 × 10⁻⁶. -3After vacuuming again, CO2 gas is introduced to bring the pressure in the reactor to 10 kPa. CO2 gas is added again until the pressure inside the reactor reaches 15 kPa. Vacuuming is repeated, and this cycle is repeated 4 times to minimize the impact of residual waste gas on the modification process.

[0173] (4) Apply a voltage of 28kV to the electrodes of the reactor and output a frequency of 9kHz to trigger the discharge process. The discharge time is 20min. After the reaction is completed, store the treated single-walled carbon nanotubes in a sealed box for later use.

[0174] Step (6) Coupling agent modification

[0175] (1) Weigh 10g of the carbon nanotube powder that has been plasma-treated in step (5) and put it into an oven to dry for later use;

[0176] (2) After the powder is dried, pour the powder into a clean and dry beaker A, add 50 mL of anhydrous ethanol, and stir with a glass rod to achieve full dilution; then use a mechanical stirrer to stir the mixed solution at a speed of about 8000 r / min for 30 min, while supplementing with ultrasonic treatment and water bath heating at 50°C to ensure uniform mixing.

[0177] (3) Preparation of coupling agent solution: 10g KH560 was added to a clean and dry beaker B through a dropper. Then, 100mL of deionized water and anhydrous ethanol were added to the solution. The solution was stirred thoroughly until it changed from turbid to transparent. The mass ratio of carbon nanotube powder, coupling agent, deionized water and anhydrous ethanol used was 20:2:1:7.

[0178] (4) Pour the prepared KH560 solution (beaker B) into the stirred beaker A, continue to mechanically stir at a speed of about 6000 r / min, and simultaneously use ultrasound and a 50°C water bath for heating, and continue stirring for more than 60 min to ensure that the coupling agent and carbon nanotubes undergo a full chemical reaction.

[0179] (5) After the reaction is complete, filter the mixture and wash it several times to remove the silane coupling agent that did not participate in the reaction. Finally, place the filtered solution in an oven at 80°C for drying, then grind it into powder and store it in a sealed bag for later use.

[0180] Step (7) Preparation of spinning solution

[0181] First, the modified single-walled carbon nanotubes obtained in step (6) are pre-dispersed: SWCNTs (single-walled carbon nanotubes) collected from the tube furnace are mixed with 30% H2O2 at a ratio of 4 mg SWCNT: 6 mL H2O2. The mixture is magnetically stirred at 500 rpm for 20 min. Then, the H2O2 is filtered out, and the SWCNTs are washed with deionized water. The washed SWCNTs are uniformly mixed at a ratio of 3 mg SWCNT: 3 mL water. The suspension is placed in a freeze dryer and dried for 36 h to completely remove the water, resulting in loose and porous sponge-like SWCNTs. 4 g of the pre-dispersed SWCNTs are transferred to a glove box and mixed with 6 mL of chlorosulfonic acid under an Ar atmosphere. The bottle mouth is sealed with a sealing film to prevent chlorosulfonic acid from leaking and fuming in the air. The Ar atmosphere inside the bottle is maintained. The chlorosulfonic acid / SWCNT mixture is planetarily stirred at a speed of 2000-3000 rpm to make it uniformly mixed, resulting in SWCNT liquid crystal spinning solution.

[0182] Step (8) Fiber preparation

[0183] The SWCNT liquid crystal spinning solution obtained in step (7) was transferred to a stainless steel injection needle in a glove box under Ar atmosphere protection, and fixed on the injection pump. The SWCNT liquid crystal spinning solution was then injected at a rate of 0.07 mL / min. -1 The liquid crystal spinning solution is injected into the acetone coagulation bath at a certain speed, with the syringe needle tip immersed 2 cm below the surface of the acetone coagulation bath. The fiber is then removed from the coagulation bath and wound onto the polytetrafluoroethylene (PTFE) roll of the winding equipment. After the liquid crystal spinning solution is injected, the fiber on the PTFE roll is washed with water and dried at 110°C to obtain dry SWCNT fiber.

[0184] Comparative Example 1

[0185] Step (1) Preparation of catalyst precursor

[0186] Weigh 2g of FeCl3 solid powder and dissolve it in 30 mL of deionized water to prepare a 0.3mol / L FeCl3 solution. Use a pipette to draw 100μL of the FeCl3 solution and dilute it again with 2mL of deionized water to a 0.05mol / L FeCl3 solution to obtain the desired catalyst precursor.

[0187] Step (2) Substrate pretreatment

[0188] Pretreatment: The single crystal quartz wafer was ultrasonically cleaned in deionized water, acetone, ethanol and deionized water for 10 min in sequence. After being dried with high-purity nitrogen, it was placed in a muffle furnace and annealed at high temperature in air atmosphere at 800℃ for 6 hours. Then, the temperature was reduced to 300℃ within 8 hours by a temperature control program. Finally, it was allowed to cool naturally to room temperature.

[0189] Step (3) Loading of catalyst precursor

[0190] Dip a sewing needle into a small amount of the catalyst precursor solution from step (1), let it air dry, and then quickly swipe it across the substrate surface from step (2) to form catalyst strips on the substrate surface.

[0191] Step (4) Preparation of single-walled carbon nanotubes

[0192] Place the substrate loaded with catalyst in step (3) on a quartz boat and push it into the constant temperature zone of the tube furnace. Heat it in an air atmosphere for 20 min, then introduce argon as a protective gas to purge the air from the quartz tube for about 10 min. After reaching the predetermined growth temperature, introduce hydrogen for 15 min to reduce the catalyst precursor to Fe nanoparticles. Then, use argon to introduce methane (with a small amount of water added; some studies suggest that water helps enrich semiconductor nanotubes) to swell the carbon source. Continue growth for 15 min, then turn off the carbon source and hydrogen. After waiting for it to cool naturally to room temperature, turn off the protective argon gas and remove the sample.

[0193] Step (5) Preparation of spinning solution

[0194] First, the single-walled carbon nanotubes obtained in step (4) are pre-dispersed: the SWCNTs (single-walled carbon nanotubes) collected from the tube furnace are mixed with 20% H2O2 at a ratio of 1 mg SWCNT: 2 mL H2O2, and stirred magnetically at a speed of 400 rpm for 10 min. Then, the H2O2 is filtered out, and the SWCNTs are washed with deionized water. The washed SWCNTs are mixed evenly at a ratio of 1 mg SWCNT: 1 mL water. The suspension is placed in a freeze dryer and dried for 30 h to completely remove water, resulting in loose and porous sponge-like SWCNTs. 2 g of the pre-dispersed SWCNTs are transferred to a glove box and mixed with 3 mL of chlorosulfonic acid under the protection of Ar atmosphere. The bottle mouth is sealed with sealing film to prevent chlorosulfonic acid from leaking and fuming in the air. The Ar atmosphere inside the bottle is maintained. The chlorosulfonic acid / SWCNT mixture is planetarily stirred at a speed of 2000 rpm to make it evenly mixed, resulting in SWCNT liquid crystal spinning solution.

[0195] Step (6) Fiber preparation

[0196] The SWCNT liquid crystal spinning solution obtained in step (5) was transferred to a stainless steel injection needle in a glove box under Ar atmosphere protection, and fixed on the injection pump. The SWCNT liquid crystal spinning solution was then injected at a rate of 0.03 mL / min. -1The liquid crystal spinning solution is injected into the acetone coagulation bath at a certain speed, with the syringe needle tip immersed 1 cm below the surface of the acetone coagulation bath. The fiber is then removed from the coagulation bath and wound onto the polytetrafluoroethylene (PTFE) roll of the winding equipment. After the liquid crystal spinning solution is injected, the fiber on the PTFE roll is washed with water and dried at 100°C to obtain dry SWCNT fiber.

[0197] Comparative Example 2

[0198] Step (1) Preparation of catalyst precursor

[0199] Weigh 2g of FeCl3 solid powder and dissolve it in 30 mL of deionized water to prepare a 0.3mol / L FeCl3 solution. Use a pipette to draw 100μL of the FeCl3 solution and dilute it again with 2mL of deionized water to a 0.05mol / L FeCl3 solution to obtain the desired catalyst precursor.

[0200] Step (2) Substrate pretreatment

[0201] Pretreatment: The single crystal quartz wafer was ultrasonically cleaned in deionized water, acetone, ethanol and deionized water for 10 min in sequence. After being dried with high-purity nitrogen, it was placed in a muffle furnace and annealed at high temperature in air atmosphere at 800℃ for 6 hours. Then, the temperature was reduced to 300℃ within 8 hours by a temperature control program. Finally, it was allowed to cool naturally to room temperature.

[0202] Step (3) Loading of catalyst precursor

[0203] Dip a sewing needle into a small amount of the catalyst precursor solution from step (1), let it air dry, and then quickly swipe it across the substrate surface from step (2) to form catalyst strips on the substrate surface.

[0204] Step (4) Preparation of single-walled carbon nanotubes

[0205] Place the substrate loaded with catalyst in step (3) on a quartz boat and push it into the constant temperature zone of the tube furnace. Heat it in an air atmosphere for 20 min, then introduce argon as a protective gas to purge the air from the quartz tube for about 10 min. After reaching the predetermined growth temperature, introduce hydrogen for 15 min to reduce the catalyst precursor to Fe nanoparticles. Then, use argon to introduce methane (with a small amount of water added; some studies suggest that water helps enrich semiconductor nanotubes) to swell the carbon source. Continue growth for 15 min, then turn off the carbon source and hydrogen. After waiting for it to cool naturally to room temperature, turn off the protective argon gas and remove the sample.

[0206] Step (5) Plasma surface modification

[0207] (1) Weigh 5g of the untreated carbon nanotube powder from step (4) into a clean and dry beaker and add 50mL of deionized water, and then ultrasonically disperse for 20 min.

[0208] (2) The dispersed original carbon nanotube solution was filtered by microporous filter membrane and dried at 60°C for 8 h to obtain a cylindrical single-walled carbon nanotube film with a thickness of 0.3 mm and a diameter of 30 mm to ensure the uniformity of modification.

[0209] (3) Before modification, the reactor should be evacuated using a mechanical vacuum pump to ensure that the internal pressure of the reactor is less than 2×10⁻⁶. -3 After vacuuming again, CO2 gas is introduced to bring the pressure in the reactor to 8 kPa. CO2 gas is added again until the pressure inside the reactor reaches 10 kPa. Vacuuming is repeated 3-4 times to minimize the impact of residual waste gas on the modification process.

[0210] (4) Apply a voltage of 20kV to the electrodes of the reactor and output a frequency of 6kHz to trigger the discharge process. The discharge time is 0min. After the reaction is completed, store the treated single-walled carbon nanotubes in a sealed box for later use.

[0211] Step (6) Preparation of spinning solution

[0212] First, the modified single-walled carbon nanotubes obtained in step (5) are pre-dispersed: SWCNTs (single-walled carbon nanotubes) collected from the tube furnace are mixed with 20% H2O2 at a ratio of 1 mg SWCNT: 2 mL H2O2, and stirred magnetically at a speed of 400 rpm for 10 min. Then, the H2O2 is filtered out, and the SWCNTs are washed with deionized water. The washed SWCNTs are mixed evenly at a ratio of 1 mg SWCNT: 1 mL water. The suspension is placed in a freeze dryer and dried for 30 h to completely remove water, resulting in loose and porous sponge-like SWCNTs. 2 g of pre-dispersed SWCNTs are transferred to a glove box and mixed with 3 mL of chlorosulfonic acid under the protection of Ar atmosphere. The bottle mouth is sealed with sealing film to prevent chlorosulfonic acid from leaking and fuming in the air. The Ar atmosphere inside the bottle is maintained. The chlorosulfonic acid / SWCNT mixture is planetarily stirred at a speed of 2000 rpm to make it evenly mixed, resulting in SWCNT liquid crystal spinning solution.

[0213] Step (7) Fiber preparation

[0214] The SWCNT liquid crystal spinning solution obtained in step (6) was transferred to a stainless steel injection needle in a glove box under Ar atmosphere protection, and fixed on the injection pump. The SWCNT liquid crystal spinning solution was then injected at a rate of 0.03 mL / min. -1The liquid crystal spinning solution is injected into the acetone coagulation bath at a certain speed, with the syringe needle tip immersed 1 cm below the surface of the acetone coagulation bath. The fiber is then removed from the coagulation bath and wound onto the polytetrafluoroethylene (PTFE) roll of the winding equipment. After the liquid crystal spinning solution is injected, the fiber on the PTFE roll is washed with water and dried at 100°C to obtain dry SWCNT fiber.

[0215] Comparative Example 3

[0216] Step (1) Preparation of catalyst precursor

[0217] Weigh 2g of FeCl3 solid powder and dissolve it in 30 mL of deionized water to prepare a 0.3mol / L FeCl3 solution. Use a pipette to draw 100μL of the FeCl3 solution and dilute it again with 2mL of deionized water to a 0.05mol / L FeCl3 solution to obtain the desired catalyst precursor.

[0218] Step (2) Substrate pretreatment

[0219] Pretreatment: The single crystal quartz wafer was ultrasonically cleaned in deionized water, acetone, ethanol and deionized water for 10 min in sequence. After being dried with high-purity nitrogen, it was placed in a muffle furnace and annealed at high temperature in air atmosphere at 800℃ for 6 hours. Then, the temperature was reduced to 300℃ within 8 hours by a temperature control program. Finally, it was allowed to cool naturally to room temperature.

[0220] Step (3) Loading of catalyst precursor

[0221] Micro-contact printing method: Cut a sharp edge out of the solidified PDMS with a knife, dip a small amount of catalyst precursor solution from step (1), and after air drying, gently press it onto the substrate from step (2). This can also form catalyst strips on the substrate surface.

[0222] Step (4) Preparation of single-walled carbon nanotubes

[0223] Place the substrate loaded with catalyst in step (3) on a quartz boat and push it into the constant temperature zone of the tube furnace. Heat it in an air atmosphere for 20 min, then introduce argon as a protective gas to purge the air from the quartz tube for about 10 min. After reaching the predetermined growth temperature, introduce hydrogen for 15 min to reduce the catalyst precursor to Fe nanoparticles. Then, use argon to introduce methane (with a small amount of water added; some studies suggest that water helps enrich semiconductor nanotubes) to swell the carbon source. Continue growth for 15 min, then turn off the carbon source and hydrogen. After waiting for it to cool naturally to room temperature, turn off the protective argon gas and remove the sample.

[0224] Step (5) Plasma surface modification

[0225] (1) Weigh 5g of the untreated carbon nanotube powder from step (4) into a clean and dry beaker and add 50mL of deionized water, and then ultrasonically disperse for 20 min.

[0226] (2) The dispersed original carbon nanotube solution was filtered by microporous filter membrane and dried at 60°C for 8 h to obtain a cylindrical single-walled carbon nanotube film with a thickness of 0.3 mm and a diameter of 30 mm to ensure the uniformity of modification.

[0227] (3) Before modification, the reactor should be evacuated using a mechanical vacuum pump to ensure that the internal pressure of the reactor is less than 2×10⁻⁶. -3 After vacuuming again, CO2 gas is introduced to bring the pressure in the reactor to 8 kPa. CO2 gas is added again until the pressure inside the reactor reaches 10 kPa. Vacuuming is repeated 3-4 times to minimize the impact of residual waste gas on the modification process.

[0228] (4) Apply a voltage of 20kV to the electrodes of the reactor and output a frequency of 6kHz to trigger the discharge process. The discharge time is 0min. After the reaction is completed, store the treated single-walled carbon nanotubes in a sealed box for later use.

[0229] Step (6) Coupling agent modification

[0230] (1) Weigh 5g of the carbon nanotube powder that has been plasma-treated in step (5) and put it into an oven to dry for later use;

[0231] (2) After the powder is dried, pour the powder into a clean and dry beaker A, add 40 mL of anhydrous ethanol, and stir with a glass rod to achieve full dilution; then use a mechanical stirrer to stir the mixed solution at a speed of about 5000 r / min for 20 min, while supplementing with ultrasonic treatment and water bath heating at 40°C to ensure uniform mixing.

[0232] (3) Preparation of coupling agent solution: Add 5g KH560 to a clean and dry beaker B through a dropper, then add 50mL of deionized water and anhydrous ethanol to the solution, and stir thoroughly until the solution changes from turbid to transparent. The mass ratio of carbon nanotube powder, coupling agent, deionized water and anhydrous ethanol used is 10:3:2:1.

[0233] (4) Pour the prepared KH560 solution (beaker B) into the stirred beaker A, continue to mechanically stir at a speed of about 5000 r / min, and use ultrasound and a 40°C water bath for heating. Continue stirring for more than 40 min to ensure that the coupling agent and carbon nanotubes undergo a full chemical reaction.

[0234] (5) After the reaction is complete, filter the mixture and wash it several times to remove the unreacted silane coupling agent. Finally, place the filtered solution in an oven at 60°C to dry it, then grind it into powder and store it in a sealed bag for later use.

[0235] Step (7) Preparation of spinning solution

[0236] First, the modified single-walled carbon nanotubes obtained in step (6) are pre-dispersed: SWCNTs (single-walled carbon nanotubes) collected from the tube furnace are mixed with 20% H2O2 at a ratio of 1 mg SWCNT: 2 mL H2O2, and stirred magnetically at a speed of 400 rpm for 10 min. Then, the H2O2 is filtered out, and the SWCNTs are washed with deionized water. The washed SWCNTs are mixed evenly at a ratio of 1 mg SWCNT: 1 mL water. The suspension is placed in a freeze dryer and dried for 30 h to completely remove water, resulting in loose and porous sponge-like SWCNTs. 2 g of pre-dispersed SWCNTs are transferred to a glove box and mixed with 3 mL of chlorosulfonic acid under the protection of Ar atmosphere. The bottle mouth is sealed with sealing film to prevent chlorosulfonic acid from leaking and fuming in the air. The Ar atmosphere inside the bottle is maintained. The chlorosulfonic acid / SWCNT mixture is planetarily stirred at a speed of 2000 rpm to make it evenly mixed, resulting in SWCNT liquid crystal spinning solution.

[0237] Step (8) Fiber preparation

[0238] The SWCNT liquid crystal spinning solution obtained in step (7) was transferred to a stainless steel injection needle in a glove box under Ar atmosphere protection, and fixed on the injection pump. The SWCNT liquid crystal spinning solution was then injected at a rate of 0.03 mL / min. -1 The liquid crystal spinning solution is injected into the acetone coagulation bath at a certain speed, with the syringe needle tip immersed 1 cm below the surface of the acetone coagulation bath. The fiber is then removed from the coagulation bath and wound onto the polytetrafluoroethylene (PTFE) roll of the winding equipment. After the liquid crystal spinning solution is injected, the fiber on the PTFE roll is washed with water and dried at 100°C to obtain dry SWCNT fiber.

[0239] Comparative Example 4

[0240] Step (1) Preparation of catalyst precursor

[0241] Weigh 2g of FeCl3 solid powder and dissolve it in 30 mL of deionized water to prepare a 0.3mol / L FeCl3 solution. Use a pipette to draw 100μL of the FeCl3 solution and dilute it again with 2mL of deionized water to a 0.05mol / L FeCl3 solution to obtain the desired catalyst precursor.

[0242] Step (2) Substrate pretreatment

[0243] Pretreatment: The single crystal quartz wafer was ultrasonically cleaned in deionized water, acetone, ethanol and deionized water for 10 min in sequence. After being dried with high-purity nitrogen, it was placed in a muffle furnace and annealed at high temperature in air atmosphere at 800℃ for 6 hours. Then, the temperature was reduced to 300℃ within 8 hours by a temperature control program. Finally, it was allowed to cool naturally to room temperature.

[0244] Step (3) Loading of catalyst precursor

[0245] Dip a sewing needle into a small amount of the catalyst precursor solution from step (1), let it air dry, and then quickly swipe it across the substrate surface from step (2) to form catalyst strips on the substrate surface.

[0246] Step (4) Preparation of single-walled carbon nanotubes

[0247] Place the substrate loaded with catalyst in step (3) on a quartz boat and push it into the constant temperature zone of the tube furnace. Heat it in an air atmosphere for 20 min, then introduce argon as a protective gas to purge the air from the quartz tube for about 10 min. After reaching the predetermined growth temperature, introduce hydrogen for 15 min to reduce the catalyst precursor to Fe nanoparticles. Then, use argon to introduce methane (with a small amount of water added; some studies suggest that water helps enrich semiconductor nanotubes) to swell the carbon source. Continue growth for 15 min, then turn off the carbon source and hydrogen. After waiting for it to cool naturally to room temperature, turn off the protective argon gas and remove the sample.

[0248] Step (5) Plasma surface modification

[0249] (1) Weigh 5g of the untreated carbon nanotube powder from step (4) into a clean and dry beaker and add 50mL of deionized water, and then ultrasonically disperse for 20 min.

[0250] (2) The dispersed original carbon nanotube solution was filtered by microporous filter membrane and dried at 60°C for 8 h to obtain a cylindrical single-walled carbon nanotube film with a thickness of 0.3 mm and a diameter of 30 mm to ensure the uniformity of modification.

[0251] (3) Before modification, the reactor should be evacuated using a mechanical vacuum pump to ensure that the internal pressure of the reactor is less than 2×10⁻⁶. -3 After vacuuming again, CO2 gas is introduced to bring the pressure in the reactor to 8 kPa. CO2 gas is added again until the pressure inside the reactor reaches 10 kPa. Vacuuming is repeated 3-4 times to minimize the impact of residual waste gas on the modification process.

[0252] (4) Apply a voltage of 20kV to the electrodes of the reactor and output a frequency of 6kHz to trigger the discharge process. The discharge time is 0min. After the reaction is completed, store the treated single-walled carbon nanotubes in a sealed box for later use.

[0253] Step (6) Coupling agent modification

[0254] (1) Weigh 5g of the carbon nanotube powder that has been plasma-treated in step (5) and put it into an oven to dry for later use;

[0255] (2) After the powder is dried, pour the powder into a clean and dry beaker A, add 40 mL of anhydrous ethanol, and stir with a glass rod to achieve full dilution; then use a mechanical stirrer to stir the mixed solution at a speed of about 5000 r / min for 20 min, while supplementing with ultrasonic treatment and water bath heating at 40°C to ensure uniform mixing.

[0256] (3) Preparation of coupling agent solution: Add 5g KH560 to a clean and dry beaker B through a dropper, then add 50mL of deionized water and anhydrous ethanol to the solution, and stir thoroughly until the solution changes from turbid to transparent. The mass ratio of carbon nanotube powder, coupling agent, deionized water and anhydrous ethanol used is 10:3:2:1.

[0257] (4) Pour the prepared KH560 solution (beaker B) into the stirred beaker A, continue to mechanically stir at a speed of about 5000 r / min, and use ultrasound and a 40°C water bath for heating. Continue stirring for more than 40 min to ensure that the coupling agent and carbon nanotubes undergo a full chemical reaction.

[0258] (5) After the reaction is complete, filter the mixture and wash it several times to remove the unreacted silane coupling agent. Finally, place the filtered solution in an oven at 60°C to dry it, then grind it into powder and store it in a sealed bag for later use.

[0259] Step (7) Preparation of spinning solution

[0260] First, the modified single-walled carbon nanotubes obtained in step (6) were pre-dispersed: Since the single-walled carbon nanotubes prepared had high crystallinity and were difficult to disperse directly, the single-walled carbon nanotubes were first soaked in 25% hydrogen peroxide solution at a ratio of 2 mg / mL, pre-dispersed at a speed of 400 rpm for 46 h, and then filtered. The filtered single-walled carbon nanotubes were dispersed in deionized water and freeze-dried. The dried single-walled carbon nanotubes were weighed using an analytical balance and added to chlorosulfonic acid solution at a weight ratio of 1.4 wt% in an argon-protected glove box. The prepared mixture was placed in a planetary stirrer and mixed at a speed of 2500 rpm for 10 min to obtain a uniform and stable liquid crystal phase spinning solution.

[0261] Step (8) Fiber preparation

[0262] The SWCNT liquid crystal spinning solution obtained in step (7) was transferred to a stainless steel injection needle in a glove box under Ar atmosphere protection, and fixed on the injection pump. The SWCNT liquid crystal spinning solution was then injected at a rate of 0.03 mL / min. -1 The liquid crystal spinning solution is injected into the acetone coagulation bath at a certain speed, with the syringe needle tip immersed 1 cm below the surface of the acetone coagulation bath. The fiber is then removed from the coagulation bath and wound onto the polytetrafluoroethylene (PTFE) roll of the winding equipment. After the liquid crystal spinning solution is injected, the fiber on the PTFE roll is washed with water and dried at 100°C to obtain dry SWCNT fiber.

[0263] Comparison of detection experiments:

[0264] The single-walled carbon nanotubes obtained in Examples 1 to 4 and comparative products 1 to 4 were tested using the following specific testing methods:

[0265] Contact angle test

[0266] A conductive TPU / graphite / carbon nanotube composite material was prepared by combining single-walled carbon nanotubes with graphite for testing. The testing method involved placing composite samples with different parameters on a glass plate and slowly adding deionized water droplets onto the sample surface using a 10 μL flat-tipped microsyringe. An image of the droplets was captured using a camera at a suitable viewing angle. The image was then processed using ImageJ software to calculate the contact angle at each test point. To improve measurement accuracy and reduce error, four different test points were randomly selected on each sample surface for contact angle measurement. After eliminating outliers, the arithmetic mean of the static contact angles was calculated.

[0267] Electrical performance testing

[0268] A conductive TPU / graphite / carbon nanotube composite material was prepared by combining single-walled carbon nanotubes with graphite for testing. The testing method was as follows: first, conductive silver paste was applied to the upper and lower surfaces of the composite material to reduce contact resistance and obtain a stable resistance signal. Then, conductive copper foil was adhered to the upper and lower surfaces of the sample, and the sample with electrodes was placed in a 60℃ drying oven for 3 hours. After the sample was completely dry, the volume resistivity of the material was measured using an impedance meter. The sample dimensions were cuboids of 20mm, 20mm, and 2mm, and the average of five measurements was taken as the result.

[0269] Table 1 Contact Angle Test Results

[0270] Examples Contact angle 1 103° 2 112° 3 126° 4 135° Comparative Example 1 75° Comparative Example 2 88° Comparative Example 3 80° Comparative Example 4 72°

[0271] As shown in Table 1, Example 4 is the best, while the comparative examples are worse. The hydrophobic angles of the untreated composite material in Comparative Example 1 and the composite material in Comparative Example 2 after single plasma treatment are lower than those of the composite material after synergistic treatment in the examples, but they still possess a certain degree of hydrophobicity. This is because the coupling agent KH560, in addition to the epoxy group, also has an organic group composed of three methoxy groups (-OCH3) and one propyl group (-C3H7). The methoxy and propyl groups provide the hydrophobic properties of KH560. Through chemical reaction with the -OH groups on the surface of CNTs, the surface energy of CNTs is reduced, enhancing the compatibility and dispersibility of CNTs in the TPU matrix.

[0272] Table 2 Resistivity Test Results

[0273] Examples Resistivity Ω-cm 1 7.2 x 10 -6 ]] 2 6.4 x 10 -6 ]]> 3 5.5 x 10 -7 ]]> 4 4.1 x 10 -7 ]]> Comparative Example 1 2.7 x 10 -5 ]]> Comparative Example 2 3.9 x 10 -5 ]] Comparative Example 3 8.4 x 10 -5 ]] Comparative Example 4 6.6 x 10 -5 ]]>

[0274] As shown in Table 2, Example 4 is the best, while the comparative examples are relatively poor. The resistivity of the composite material after synergistic treatment with plasma and coupling agent is lower than that of the unmodified material in Comparative Example 1 and the plasma-modified material in Comparative Example 2. It is also lower than the resistivity of the material obtained by different pre-dispersion processes in Comparative Example 3 and Comparative Example 4, exhibiting the best conductivity. This is because the synergistic treatment with plasma and coupling agent increases the number of active groups on the surface of CNTs. At the same time, the coupling agent enhances the wetting properties of the TPU matrix, improves the compatibility between CNTs and the TPU matrix, and allows CNTs to be better dispersed in the flexible matrix, increasing the conductive pathways inside the composite material and improving its conductivity.

[0275] This specific embodiment is merely an explanation of the present invention and is not intended to limit the present invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but as long as they are within the scope of the claims of the present invention, they are protected by patent law.

Claims

1. A method for preparing modified single-walled carbon nanotubes, characterized in that: Preparation of catalyst precursors, substrate pretreatment, loading of catalyst precursors, preparation of single-walled carbon nanotubes, plasma surface modification, coupling agent modification, preparation of spinning solution, and fiber preparation.

2. The method for preparing modified single-walled carbon nanotubes according to claim 1, characterized in that: Step (1) Preparation of catalyst precursor FeCl3 solid powder was weighed and dissolved in deionized water to prepare FeCl3 solution. The FeCl3 solution was then extracted using a pipette and diluted again with deionized water to obtain the desired catalyst precursor. Step (2) Substrate pretreatment Pretreatment: The single-crystal quartz wafers are ultrasonically cleaned sequentially in deionized water, acetone, ethanol, and deionized water. After being dried with high-purity nitrogen, they are placed in a muffle furnace and annealed at high temperature in an air atmosphere. The temperature is kept constant, then the temperature is controlled to drop to a certain temperature, and finally cooled naturally to room temperature. The silicon wafers are purchased directly. Step (3) Loading of catalyst precursor Dip a sewing needle into a small amount of the catalyst precursor solution from step (1), let it air dry, and then quickly swipe it across the substrate surface from step (2) to form a catalyst strip on the substrate surface. Step (4) Preparation of single-walled carbon nanotubes Place the substrate loaded with catalyst in step (3) on a quartz boat, push it into the constant temperature zone of the tube furnace, heat it in an air atmosphere, then introduce argon as a protective gas to expel the air in the quartz tube, after reaching the predetermined growth temperature, introduce hydrogen, then use argon to introduce methane to blow in the carbon source, continue growth, then turn off the carbon source and hydrogen, wait for natural cooling to room temperature, then turn off the protective argon gas and take out the sample; Step (5) Plasma surface modification (1) Weigh the untreated carbon nanotube powder from step (4) into a clean and dry beaker and add an appropriate amount of deionized water for ultrasonic dispersion; (2) The dispersed original carbon nanotube solution was filtered by microporous filter membrane and dried to obtain a cylindrical single-walled carbon nanotube film to ensure the uniformity of modification. (3) Before modification, the reactor is evacuated by a mechanical vacuum pump and then evacuated again. This process is repeated 3-4 times to minimize the impact of residual waste gas on the modification process. (4) Apply voltage to the electrodes of the reactor to trigger the discharge process. After the reaction is completed, store the treated single-walled carbon nanotubes in a sealed box for later use. Step (6) Coupling agent modification (1) Weigh the carbon nanotube powder that has been plasma-treated in step (5) and put it into an oven to dry for later use; (2) After the powder is dried, pour the powder into a clean and dry beaker A, add anhydrous ethanol, and stir with a glass rod to achieve full dilution; then use a mechanical stirrer to stir the mixed solution, while supplementing with ultrasonic treatment and water bath heating to ensure uniform mixing. (3) Preparation of coupling agent solution: KH560 is added to a clean and dry beaker B through a dropper. Then, deionized water and anhydrous ethanol are added to the solution and stirred thoroughly until the solution changes from turbid to transparent. The carbon nanotube powder, coupling agent, deionized water and anhydrous ethanol are added in the mass ratio. (4) Pour the prepared KH560 solution (beaker B) into the stirred beaker A, stir mechanically, and simultaneously use ultrasound and water bath heating to continuously stir to ensure that the coupling agent and carbon nanotubes undergo a full chemical reaction. (5) After the reaction is complete, filter the mixture and wash it several times to remove the silane coupling agent that did not participate in the reaction. Finally, dry the filtered solution, grind it into powder and store it in a sealed bag for later use. Step (7) Preparation of spinning solution First, the modified single-walled carbon nanotubes obtained in step (6) are pre-dispersed: SWCNTs (single-walled carbon nanotubes) collected from the tube furnace are mixed with H2O2 and stirred. Then, H2O2 is filtered out, and SWCNTs are washed with deionized water. The washed SWCNTs are mixed evenly with water, and the suspension is placed in a freeze dryer to dry completely to remove water and obtain loose and porous sponge-like SWCNTs. An appropriate amount of pre-dispersed SWCNTs is transferred to a glove box and mixed with chlorosulfonic acid under the protection of Ar atmosphere. The bottle mouth is sealed with sealing film to prevent chlorosulfonic acid from leaking and fuming in the air. The Ar atmosphere in the bottle is maintained. The chlorosulfonic acid / SWCNT mixture is planetarily stirred to make it evenly mixed and obtain SWCNT liquid crystal spinning solution. Step (8) Fiber preparation The SWCNT liquid crystal spinning solution obtained in step (7) is transferred to a stainless steel injection needle in a glove box under Ar atmosphere protection and fixed on the injection pump. The SWCNT liquid crystal spinning solution is injected into the acetone coagulation bath, and the tip of the syringe needle is immersed below the surface of the acetone coagulation bath. The fiber is taken out from the coagulation bath and wound onto the polytetrafluoroethylene roll of the winding device. After the liquid crystal spinning solution is injected, the fiber on the polytetrafluoroethylene roll is washed and dried to obtain dry SWCNT fiber.

3. The method for preparing modified single-walled carbon nanotubes according to claim 2, characterized in that: Step (1) Preparation of catalyst precursor Weigh 2-3g of FeCl3 solid powder and dissolve it in 30-50 mL of deionized water to prepare a 0.3-0.6 mol / L FeCl3 solution. Use a pipette to extract 100-200 μL of the FeCl3 solution and dilute it again with 2-5 mL of deionized water to a 0.05-0.1 mol / L FeCl3 solution to obtain the desired catalyst precursor.

4. The method for preparing modified single-walled carbon nanotubes according to claim 2, characterized in that: Step (2) Substrate pretreatment Pretreatment: The single-crystal quartz wafer is ultrasonically cleaned sequentially in deionized water, acetone, ethanol, and deionized water for 10-15 minutes. After drying with high-purity nitrogen, it is placed in a muffle furnace and annealed at high temperature in air atmosphere at 800-900℃ for 6-10 hours. Subsequently, the temperature is reduced to 300-400℃ over 8-10 hours by a temperature control program, and finally cooled naturally to room temperature. The silicon wafer is a 1*1-2*2 cm silicon wafer with an 80-90 nm thick oxide layer and photolithographic markings. It is ultrasonically cleaned sequentially in deionized water, acetone, ethanol, and deionized water for 10-15 minutes and then dried with high-purity nitrogen before use.

5. The method for preparing modified single-walled carbon nanotubes according to claim 3, characterized in that: Step (3) Loading of catalyst precursor Dip a sewing needle into a small amount of the catalyst precursor solution from step (1), let it air dry, and then quickly swipe it across the substrate surface from step (2) to form catalyst strips on the substrate surface.

6. The method for preparing modified single-walled carbon nanotubes according to claim 5, characterized in that: Step (4) Preparation of single-walled carbon nanotubes Place the substrate loaded with catalyst in step (3) on a quartz boat and push it into the constant temperature zone of the tube furnace. Heat it in an air atmosphere for 20-30 min, then introduce argon gas as a protective gas to purge the air from the quartz tube for about 10-20 min. After reaching the predetermined growth temperature, introduce hydrogen gas for 15-20 min to reduce the catalyst precursor to Fe nanoparticles. Then, use argon gas to introduce methane (with a small amount of water added; some studies suggest that water helps enrich semiconductor nanotubes) to swell the carbon source. Continue growth for 15-20 min, then turn off the carbon source and hydrogen gas. After waiting for it to cool naturally to room temperature, turn off the protective argon gas and remove the sample.

7. The method for preparing modified single-walled carbon nanotubes according to claim 6, characterized in that: Step (5) Plasma surface modification (1) Weigh 5-10g of the untreated carbon nanotube powder from step (4) into a clean and dry beaker and add 50-100mL of deionized water. Disperse the powder by ultrasonication for 20-40 min. (2) The dispersed original carbon nanotube solution was filtered by microporous filter membrane and dried at 60-80℃ for 8-10 h to obtain a cylindrical single-walled carbon nanotube film with a thickness of 0.3-0.5 mm and a diameter of 30-40 mm to ensure the uniformity of modification. (3) Before modification, the reactor should be evacuated using a mechanical vacuum pump to ensure that the internal pressure of the reactor is less than 2×10⁻⁶. -3 -2.8×10 -3 After vacuuming again, CO2 gas is introduced to bring the pressure in the reactor to 8-10 kPa. CO2 gas is added again until the pressure inside the reactor reaches 10-15 kPa. Vacuuming is repeated 3-4 times to minimize the impact of residual waste gas on the modification process. (4) Apply a voltage of 20-28kV to the electrodes of the reactor and output a frequency of 6-9kHz to trigger the discharge process. The discharge time is 0-20min. After the reaction is completed, store the treated single-walled carbon nanotubes in a sealed box for later use.

8. The method for preparing modified single-walled carbon nanotubes according to claim 7, characterized in that: Step (6) Coupling agent modification (1) Weigh 5-10g of the carbon nanotube powder that has been plasma-treated in step (5) and put it into an oven to dry for later use; (2) After the powder is dried, pour the powder into a clean and dry beaker A, add 40-50 mL of anhydrous ethanol, and stir with a glass rod to achieve full dilution; then use a mechanical stirrer to stir the mixed solution at a speed of about 5000-8000 r / min for 20-30 min, while supplementing with ultrasonic treatment and water bath heating at 40-50℃ to ensure uniform mixing; (3) Preparation of coupling agent solution: Add 5-10g KH560 to a clean and dry beaker B through a dropper, then add 50-100mL of deionized water and anhydrous ethanol to the solution, and stir thoroughly until the solution changes from turbid to transparent. The mass ratio of carbon nanotube powder, coupling agent, deionized water and anhydrous ethanol used is 10:3:2:1-20:2:1:

7. (4) Pour the prepared KH560 solution (beaker B) into the stirred beaker A, and continue to mechanically stir at a speed of about 5000-6000 r / min. At the same time, use ultrasound and a water bath at 40-50℃ to heat the mixture for more than 40-60 min to ensure that the coupling agent and carbon nanotubes undergo a full chemical reaction. (5) After the reaction is complete, filter the mixture and wash it several times to remove the silane coupling agent that did not participate in the reaction. Finally, place the filtered solution in an oven at 60-80°C for drying, then grind it into powder and store it in a sealed bag for later use.

9. The method for preparing modified single-walled carbon nanotubes according to claim 8, characterized in that: Step (7) Preparation of spinning solution First, the modified single-walled carbon nanotubes obtained in step (6) are pre-dispersed: the SWCNTs (single-walled carbon nanotubes) collected from the tube furnace are mixed with 20-30% H2O2 at a ratio of 1-4 mg SWCNT: 2-6 mL H2O2, and stirred magnetically at a rate of 400-500 rpm for 10-20 min. Then, the H2O2 is filtered out, and the SWCNTs are washed with deionized water. The washed SWCNTs are then mixed with 1-3 mg H2O2. SWCNTs were uniformly mixed with 1-3 mL of water, and the suspension was placed in a freeze dryer and dried for 30-36 hours to completely remove water, resulting in loose and porous sponge-like SWCNTs. 2-4 g of pre-dispersed SWCNTs were transferred to a glove box and mixed with 3-6 mL of chlorosulfonic acid under an Ar atmosphere. The bottle mouth was sealed with sealing film to prevent chlorosulfonic acid from leaking and fuming in the air. The Ar atmosphere inside the bottle was maintained. The chlorosulfonic acid / SWCNT mixture was planetarily stirred at 2000-3000 rpm to ensure uniform mixing, thus obtaining the SWCNT liquid crystal spinning solution.

10. The method for preparing modified single-walled carbon nanotubes according to claim 9, characterized in that: Step (8) Fiber preparation The SWCNT liquid crystal spinning solution obtained in step (7) was transferred to a stainless steel injection needle in a glove box under Ar atmosphere protection, and fixed on the injection pump. The SWCNT liquid crystal spinning solution was then injected at a rate of 0.03-0.07 mL / min. -1 The liquid crystal spinning solution is injected into the acetone coagulation bath at a certain speed, with the syringe needle tip immersed 1-2 cm below the surface of the acetone coagulation bath. The fiber is then removed from the coagulation bath and wound onto the polytetrafluoroethylene (PTFE) roll of the winding equipment. After the liquid crystal spinning solution is injected, the fiber on the PTFE roll is washed with water and dried at 100-110°C to obtain dry SWCNT fiber.

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