Method for identifying left spiral mirror image body and right spiral mirror image body of carbon nano tube

Abstract

The invention provides a method for identifying a left spiral mirror image body and a right spiral mirror image body of a carbon nano tube, which comprises the following steps of: (I) measuring the length of wavelength when S11 of a (m, n) carbon nano tube left spiral mirror image body and a (n, m) carbon nano tube right spiral mirror image body generates red shift in a known sample; (II) measuring the S11 wavelength of the unknown sample; and (III) judging the left and right spiral mirror bodies of the unknown sample. The method provided by the invention is accurate, reliable, simple and effective, and can be used for identifying the carbon nanotube left spiral mirror image body and the carbon nanotube right spiral mirror image body with very low mass concentration.

Description

Technical Field

[0001] The present invention belongs to the field of materials. Specifically, the present invention relates to a method for identifying left-handed helical enantiomers and right-handed helical enantiomers of carbon nanotubes. Background Art

[0002] Carbon nanotubes can be regarded as one-dimensional tubular structures formed by the curling of graphene. Due to different curling methods, various atomic helical structures will inevitably be formed, thus exhibiting unique photophysical properties (such as metallicity, semi-metallicity, and semi-conductivity), and having broad application prospects in the fields of optoelectronics, biomedicine, etc. The atomic structure of carbon nanotubes can be defined by a pair of (n, m) indices. According to different values of n and m, carbon nanotubes can be divided into zigzag (m = 0), armchair (n = m), and chiral (n ≠ m, m ≠ 0). As the most abundant chiral carbon nanotubes, each chiral carbon nanotube contains different helical directions, namely left-handed helix and right-handed helix. As Figure 1 shown, when the values of n and m satisfy the condition of n > m, (m, n) and (n, m) are defined as left-handed helical and right-handed helical carbon nanotubes respectively. In currently grown and synthesized carbon nanotube materials, the contents of left-handed helical and right-handed helical carbon nanotubes are usually equal. In order to prepare single left-handed helical or right-handed helical carbon nanotube materials, in the past ten-odd years, researchers have developed a variety of separation methods, including gel chromatography, density gradient centrifugation, two-phase method, molecular encapsulation method, etc., providing a material basis for the application of carbon nanotubes in chiral detection, biomedicine, etc.

[0003] With the continuous development of microscopic techniques such as scanning tunneling microscopy, high-resolution transmission electron microscopy, and electron diffraction, these techniques have been widely used to identify and characterize the (n, m) indices of carbon nanotubes. However, these methods have limited spatial resolution for one-dimensional carbon nanotubes and are currently difficult to directly use for the identification of carbon nanotube enantiomers. Currently, the only commercially available instrument widely used to identify and characterize carbon nanotube enantiomers is a circular dichroism spectrometer, which can identify carbon nanotube enantiomers based on the positive and negative signals in the circular dichroism spectrum. Nevertheless, due to the extremely weak circular dichroism signal of carbon nanotubes compared to the excitation light, it seriously affects the signal-to-noise ratio and resolution of the circular dichroism spectrum, and further leads to the detection accuracy of the circular dichroism spectrum for carbon nanotubes being much lower than that of common spectroscopic methods such as absorption and fluorescence, and it is unable to characterize carbon nanotube samples with lower enantiomer concentration or purity.

[0004] Therefore, there is an urgent need to develop a general method with high detection accuracy to identify and characterize left-handed helical enantiomers and right-handed helical enantiomers of carbon nanotubes. Summary of the Invention

[0005] The object of the present invention is to provide a method for identifying the left-handed helical enantiomer and the right-handed helical enantiomer of carbon nanotubes. This method is accurate, reliable, simple and effective, and can identify the left-handed helical enantiomer and the right-handed helical enantiomer of carbon nanotubes with a very low mass concentration (as low as 2 ng / mL).

[0006] The above object of the present invention is achieved by the following technical solutions.

[0007] In the context of the present invention, both m and n in the term "(m, n)" are integers and there is the following relationship: m < n, n ≠ m, and m ≠ 0.

[0008] In the context of the present invention, the term "known sample" refers to a carbon nanotube sample for which it is already known or clearly known whether it belongs to the left-handed helical enantiomer of (m, n) carbon nanotubes or the right-handed helical enantiomer of (n, m) carbon nanotubes.

[0009] In the context of the present invention, the term "unknown sample" refers to a sample for which the values of m and n are already known, but it is not known whether the carbon nanotube sample belongs to the left-handed helical enantiomer of (m, n) carbon nanotubes or the right-handed helical enantiomer of (n, m) carbon nanotubes.

[0010] In the context of the present invention, the term "S 11 " refers to the transition from the first valence band to the first conduction band of a semiconducting carbon nanotube.

[0011] The present invention provides a method for identifying the left-handed helical enantiomer and the right-handed helical enantiomer of carbon nanotubes, which comprises the following steps:

[0012] (I) Measuring the lengths of the wavelengths at which a redshift occurs for the left-handed helical enantiomer of (m, n) carbon nanotubes and the right-handed helical enantiomer of (n, m) carbon nanotubes in a known sample 11 when S

[0013] (I-1) Separately dispersing the left-handed helical enantiomer of (m, n) carbon nanotubes and the right-handed helical enantiomer of (n, m) carbon nanotubes in a non-chiral dispersant solution to obtain several dispersions of the left-handed helical enantiomer of (m, n) carbon nanotubes and several dispersions of the right-handed helical enantiomer of (n, m) carbon nanotubes respectively;

[0014] (I-2) Add chiral dispersant solutions with different mass concentrations to the dispersions of several portions (m, n) of left-handed helical mirror images of carbon nanotubes and several portions (n, m) of right-handed helical mirror images of carbon nanotubes, while keeping the concentration of the achiral dispersant in each dispersion of several portions (m, n) of left-handed helical mirror images of carbon nanotubes and each dispersion of several portions (n, m) of right-handed helical mirror images of carbon nanotubes unchanged, so as to obtain several composite dispersions of several portions (m, n) of left-handed helical mirror images of carbon nanotubes and several composite dispersions of several portions (n, m) of right-handed helical mirror images of carbon nanotubes;

[0015] (I-3) Respectively perform absorption spectrum characterization and / or fluorescence spectrum characterization on the several composite dispersions of several portions (m, n) of left-handed helical mirror images of carbon nanotubes and the several composite dispersions of several portions (n, m) of right-handed helical mirror images of carbon nanotubes to determine the S of (m, n) left-handed helical mirror images of carbon nanotubes and (n, m) right-handed helical mirror images of carbon nanotubes 11 The length of the wavelength at which a redshift occurs, and at the same time, the S of (m, n) left-handed helical mirror images of carbon nanotubes and (n, m) right-handed helical mirror images of carbon nanotubes 11 Record the concentration of the chiral dispersant solution added when the redshift just begins as the representative concentration C;

[0016] (II) Measure the S of the unknown sample 11 Wavelength

[0017] (II-1) Denote the unknown sample as the first mirror image of carbon nanotubes and the second mirror image of carbon nanotubes; add the achiral dispersant solution to the first mirror image of carbon nanotubes and the second mirror image of carbon nanotubes to obtain the dispersion of the first mirror image of carbon nanotubes and the dispersion of the second mirror image of carbon nanotubes respectively;

[0018] (II-2) Add chiral dispersant solutions with a concentration greater than or equal to the representative concentration C to the dispersion of the first mirror image of carbon nanotubes and the dispersion of the second mirror image of carbon nanotubes respectively, while keeping the concentration of the achiral dispersant in the dispersion of the first mirror image of carbon nanotubes and the dispersion of the second mirror image of carbon nanotubes unchanged, so as to obtain the composite dispersion of the first mirror image of carbon nanotubes and the composite dispersion of the second mirror image of carbon nanotubes;

[0019] (II-3) Respectively perform absorption spectrum characterization and / or fluorescence spectrum characterization on the composite dispersion of the first mirror image of carbon nanotubes and the composite dispersion of the second mirror image of carbon nanotubes to determine the S of the first mirror image of carbon nanotubes and the second mirror image of carbon nanotubes 11 Wavelength, denoted as the first S 11 Wavelength and the second S 11 Wavelength;

[0020] (III) Determine the left- and right-handed helical mirror images of the unknown sample

[0021] Compare the first S 11 wavelength with the second S 11 wavelength in terms of relative length, so as to correspond to the S 11 wavelength when red shift occurs for the left-handed helical mirror image of (m, n) carbon nanotubes and the right-handed helical mirror image of (n, m) carbon nanotubes determined in step (I-3):

[0022] If the S 11 wavelength when red shift occurs for the left-handed helical mirror image of (m, n) carbon nanotubes determined in step (I-3) is a short wavelength, then the carbon nanotube mirror image corresponding to the relatively short wavelength among the first S 11 wavelength and the second S 11 wavelength is the left-handed helical mirror image of (m, n) carbon nanotubes, and the carbon nanotube mirror image corresponding to the relatively long wavelength among the first S 11 wavelength and the second S 11 wavelength is the right-handed helical mirror image of (n, m) carbon nanotubes;

[0023] If the S 11 wavelength when red shift occurs for the left-handed helical mirror image of (m, n) carbon nanotubes determined in step (I-3) is a long wavelength, then the carbon nanotube mirror image corresponding to the relatively long wavelength among the first S 11 wavelength and the second S 11 wavelength is the left-handed helical mirror image of (m, n) carbon nanotubes, and the carbon nanotube mirror image corresponding to the relatively short wavelength among the first S 11 wavelength and the second S 11 wavelength is the right-handed helical mirror image of (n, m) carbon nanotubes.

[0024] The inventors of the present invention unexpectedly found that under the regulation of a chiral dispersant (such as sodium hyodeoxycholate surfactant), the S 11 wavelength of the left-handed and right-handed helical mirror images of carbon nanotubes is closely related to its Type. For carbon nanotubes of Type I mod(2n + m, 3) = 1, the S 11 wavelength of the left-handed helical mirror image is greater than the S 11 wavelength of the right-handed helical mirror image; for carbon nanotubes of Type II mod(2n + m, 3) = 2, the S 11 wavelength of the left-handed helical mirror image is less than the S 11 wavelength of the right-handed helical mirror image. More specifically, for a specific (m, n) or (n, m) carbon nanotube, if the remainder of dividing the value of 2n + m by 3 is 1, the carbon nanotube is called a Type I carbon nanotube. The S 11 wavelength of the left-handed helical mirror image of Type I is greater than the S 11Wavelength; for Type II carbon nanotubes, the S of its left-handed helical mirror image is 11 less than the S of its right-handed helical mirror image in terms of wavelength. 11 The method of the present invention is based on the selective action of the left-handed and right-handed helical mirror images of carbon nanotubes on the mirror images of chiral dispersants, and realizes the recognition of the helical mirror images of carbon nanotubes by identifying the difference in S 11 wavelengths in common absorption and / or fluorescence spectra.

[0025] Preferably, in the method of the present invention, the number of portions is N portions, where 3 ≤ N ≤ 100.

[0026] Preferably, in the method of the present invention, the achiral dispersant is an achiral surfactant or polymer capable of dispersing carbon nanotubes.

[0027] Preferably, in the method of the present invention, the achiral dispersant is selected from sodium dodecylbenzenesulfonate and / or sodium dodecyl sulfate surfactants.

[0028] Preferably, in the method of the present invention, the chiral dispersant is a chiral surfactant or polymer capable of dispersing carbon nanotubes.

[0029] Preferably, in the method of the present invention, the chiral dispersant is sodium hyodeoxycholate surfactant.

[0030] Preferably, in the method of the present invention, in the chiral dispersant solutions with different mass concentrations in step (I-2), the mass concentration of each chiral dispersant solution is 0-10%; the chiral dispersant solutions with different mass concentrations are arranged in ascending order of concentration, the mass concentration of the chiral dispersant solution with the lowest mass concentration is 0-0.1% and the mass concentrations of two adjacent chiral dispersant solutions differ by 0.1%-0.5%.

[0031] In a preferred embodiment of the present invention, the concentrations of the chiral dispersant solutions with different mass concentrations do not necessarily form an arithmetic progression, and there may be cases where the concentration differences between every two chiral dispersant solutions are different.

[0032] In a preferred embodiment of the present invention, among the concentrations of a series of chiral dispersant solutions with different mass concentrations, the maximum mass concentration can be 0.2%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%.

[0033] Preferably, in the method of the present invention, the mass concentration of the achiral dispersant solution is 0.1%-5%, preferably 0.2%-2%.

[0034] Preferably, in the method of the present invention, in the composite dispersion of the (m, n) carbon nanotube left-handed helical mirror image in step (I-2), in the composite dispersion of the (n, m) carbon nanotube right-handed helical mirror image in step (I-2), in the composite dispersion of the first carbon nanotube mirror image in step (II-2), and in the composite dispersion of the second carbon nanotube mirror image in step (II-2), based on weight / volume, the concentration of the (m, n) carbon nanotube left-handed helical mirror image, the concentration of the (n, m) carbon nanotube right-handed helical mirror image, the concentration of the first carbon nanotube mirror image, and the concentration of the second carbon nanotube mirror image are each independently greater than or equal to 2 ng / mL.

[0035] In a specific embodiment of the present invention, before performing the step of "dispersing the known samples of the (m, n) carbon nanotube left-handed helical mirror image and the (n, m) carbon nanotube right-handed helical mirror image in a non-chiral dispersant solution" in step (I-1), the original dispersant molecules in the carbon nanotube left- and right-handed helical mirror image samples can be removed first.

[0036] In a specific embodiment of the present invention, the removal of the original dispersant molecules in the carbon nanotube left- and right-handed helical mirror image samples is carried out by a method including the following steps:

[0037] (a) Ultracentrifuge the original carbon nanotube left- and right-handed helical mirror image solution at 210,000×g for 1 to 4 hours;

[0038] (b) Remove the supernatant in step (a) to obtain a carbon nanotube precipitate, which is the sample after removing the original dispersant molecules.

[0039] In a specific embodiment of the present invention, the step of dispersing the known samples of the (m, n) carbon nanotube left-handed helical mirror image and the (n, m) carbon nanotube right-handed helical mirror image in a non-chiral dispersant solution in step (I-1) is carried out by a method including the following steps:

[0040] (a’) Add a solution of a non-chiral dispersant to the sample after removing the original dispersant molecules (i.e., the carbon nanotube precipitate), and ultrasonicate for 0.1 to 20 hours under the condition that the output power density is 2 to 40 W / cm 2 ;

[0041] (b’) Ultracentrifuge the sonicated carbon nanotube solution at 210,000×g for 1 to 60 minutes;

[0042] (c’) Take out the supernatant in step (b’) as the carbon nanotube sample dispersed in the non-chiral dispersant solution.

[0043] The present invention does not particularly limit the selection of solvents in the achiral dispersant solution and the chiral dispersant solution. Conventional solvents in the art can be used, such as water. Of course, common organic solvents or other inorganic solvents in the art can also be used.

[0044] The present invention has the following beneficial effects:

[0045] (1) Based on the difference in the binding energy between the chiral dispersant and the left-handed and right-handed helical mirror images of carbon nanotubes, the present invention causes a difference in the S 11 wavelength or energy of the left-handed and right-handed helical mirror images, thereby realizing the identification of carbon nanotube mirror images in the absorption and / or fluorescence spectra, without relying on the circular dichroism spectrometer that is currently widely used to characterize carbon nanotube mirror images.

[0046] (2) Compared with the traditional circular dichroism spectrum, the present invention has lower requirements for the concentration and purity of the carbon nanotube mirror image sample, and can achieve higher-precision mirror image identification.

[0047] (3) The method of the present invention is applicable to the identification of the left and right helical mirror images of different chiral carbon nanotubes, and has universality.

[0048] (4) The operation process of the method of the present invention is simple, provides a new option for the identification and characterization of carbon nanotube mirror images, and promotes the controllable preparation, property research and functional application of carbon nanotube mirror images. Description of the Drawings

[0049] Hereinafter, the embodiments of the present invention will be described in detail with reference to the drawings, wherein:

[0050] Figure 1 is a schematic structural diagram of the left-handed and right-handed helical mirror images of carbon nanotubes.

[0051] Figure 2 is the change of the S 11 absorption peak wavelength of the (5,6) carbon nanotube mirror image and the (6,5) carbon nanotube mirror image with the concentration of SHC.

[0052] Figure 3 is the change of the S 11 fluorescence peak wavelength of the (5,6) carbon nanotube mirror image and the (6,5) carbon nanotube mirror image with the concentration of SHC.

[0053] Figure 4 is the comparison of the S 11 、S 22 absorption peaks of the (5,6) carbon nanotube mirror image and the (6,5) carbon nanotube mirror image under the condition of 0.5% SDBS + 2% SHC.

[0054] Figure 5It is the absorption spectrum characterization of the first mirror image of carbon nanotubes and the second mirror image of carbon nanotubes of the unknown sample.

[0055] Figure 6 It is the circular dichroism spectrum characterization of the first mirror image of carbon nanotubes and the second mirror image of carbon nanotubes of the unknown sample.

[0056] Figure 7 It is the S of the (3,8) carbon nanotube mirror image and the (8,3) carbon nanotube mirror image 11 The change of the absorption peak wavelength with the SHC concentration.

[0057] Figure 8 It is the S of the (3,8) carbon nanotube mirror image and the (8,3) carbon nanotube mirror image 11 The change of the fluorescence peak wavelength with the SHC concentration.

[0058] Figure 9 It is the S of the (3,8) carbon nanotube mirror image and the (8,3) carbon nanotube mirror image under the condition of 0.5% SDBS + 2% SHC 11 、S 22 The comparison of the absorption peaks.

[0059] Figure 10 It is the absorption spectrum characterization of the first mirror image of carbon nanotubes and the second mirror image of carbon nanotubes of the unknown sample.

[0060] Figure 11 It is the circular dichroism spectrum characterization of the first mirror image of carbon nanotubes and the second mirror image of carbon nanotubes of the unknown sample.

[0061] Figure 12 It is the S of the (5,6) carbon nanotube mirror image and the (6,5) carbon nanotube mirror image dispersed in SDS 11 The change of the absorption peak wavelength with the SHC concentration.

[0062] Figure 13 It is the S of the (5,6) carbon nanotube mirror image and the (6,5) carbon nanotube mirror image under the condition of 0.5% SDS + 0.8% SHC 11 、S 22 The comparison of the absorption peaks.

[0063] Figure 14 It is the absorption and circular dichroism spectrum characterization of the (5,6) carbon nanotube mirror image and the (6,5) carbon nanotube mirror image at different concentrations (1 - 0.01 μg / mL), and the fluorescence spectrum characterization of the (5,6) carbon nanotube mirror image and the (6,5) carbon nanotube mirror image at an ultra-low concentration (2 ng / mL) under different integration time conditions. Detailed implementation mode

[0064] The present invention will be further described in detail below in conjunction with specific embodiments. The provided embodiments are only for clarifying the present invention and not for limiting the scope of the present invention.

[0065] Example 1

[0066] Determination of the left-handed helical enantiomers of (5,6) carbon nanotubes and the right-handed helical enantiomers of (6,5) carbon nanotubes in a known sample S 11 The length of the wavelength when redshift occurs

[0067] 1) Take 3 mL of the solutions of (5,6)-carbon nanotube left-handed helical enantiomers and (6,5)-carbon nanotube right-handed helical enantiomers separated by gel chromatography (where the concentrations of (5,6)-carbon nanotube left-handed helical enantiomers and (6,5)-carbon nanotube right-handed helical enantiomers are 5000 ng / mL respectively). Under the condition of a centrifugal force of 210000×g, ultracentrifuge for 60 minutes to precipitate the carbon nanotubes to the bottom of the centrifuge tube.

[0068] 2) Remove the surfactant solution in the supernatant, and then add an equal volume of 0.5% SDBS solution by mass concentration to the centrifuge tube, and use a water bath ultrasonic wave to redisperse the precipitated carbon nanotubes.

[0069] 3) Repeat steps 1) and 2).

[0070] 4) Use a cell disruptor at a power of 3 W / cm 2 Disperse the solutions of (5,6)-carbon nanotube left-handed helical enantiomers and (6,5)-carbon nanotube right-handed helical enantiomers in step 3) ultrasonically at a temperature of 15°C for 30 minutes respectively, so that the carbon nanotubes are fully dispersed in the 0.5% SDBS solution by mass concentration.

[0071] 5) Centrifuge the ultrasonically treated solutions of (5,6)-carbon nanotube left-handed helical enantiomers and (6,5)-carbon nanotube right-handed helical enantiomers in step 4) under the condition of a centrifugal force of 210000×g for 15 minutes, so that the undispersed carbon nanotubes agglomerate and the impurity particles precipitate to the bottom of the centrifuge tube.

[0072] 6) Take out 80% of the supernatant after centrifugation in step 5) as the solutions of (5,6)-carbon nanotube left-handed helical enantiomers and (6,5)-carbon nanotube right-handed helical enantiomers dispersed in the achiral SDBS surfactant.

[0073] 7) Divide the solutions of (5,6)-carbon nanotube left-handed helical enantiomers and (6,5)-carbon nanotube right-handed helical enantiomers in step 6) into six equal parts, each part being 0.5 mL, where the mass concentration of SDBS in each part of the solution is 0.5%.

[0074] 8) Add 0.5 mL of an aqueous solution containing an achiral SDBS and a chiral SHC surfactant to the solutions of the (5,6) carbon nanotube left-handed helical mirror image and the (6,5) carbon nanotube right-handed helical mirror image in step 7), respectively, wherein the mass concentration of SDBS is fixed at 0.5%, and the mass concentrations of the chiral SHC are 0%, 0.25%, 0.5%, 1%, 2%, and 4%, respectively, so that the concentrations of the surfactants in the solutions of the (5,6) carbon nanotube left-handed helical mirror image and the (6,5) carbon nanotube right-handed helical mirror image are 0.5% SDBS + 0% SHC, 0.5% SDBS + 0.125% SHC, 0.5% SDBS + 0.25% SHC, 0.5% SDBS + 0.5% SHC, 0.5% SDBS + 1% SHC, 0.5% SDBS + 2% SHC, the concentration of the left-handed helical mirror image of (5,6) carbon nanotubes is 2500ng / mL, and the concentration of the right-handed helical mirror image of (6,5) carbon nanotubes is 2500ng / mL.

[0075] 9) The absorption spectrum and fluorescence spectrum (excitation wavelength is 570nm) of the 6 portions of (5,6) carbon nanotube left-handed helical mirror image and 6 portions of (6,5) carbon nanotube right-handed helical mirror image solutions obtained in step 8) are characterized. The results are as follows Figure 2 and 3 As shown.

[0076] Figure 2 and Figure 3 It is shown that with the increase of SHC concentration, the S 11 The absorption peak and fluorescence peak wavelengths did not change significantly; (6,5) carbon nanotube right-hand helical mirror image S 11 The absorption peak and fluorescence peak wavelengths undergo an obvious red shift when the SHC concentration increases to 0.5%, and tend to stabilize as the SHC concentration continues to increase.

[0077] 10) S of the left-handed helical mirror image of (5, 6) carbon nanotubes and the right-handed helical mirror image of (6, 5) carbon nanotubes after SHC regulation (representative concentration is 0.5%) 11 Difference in wavelength, this embodiment can calibrate S 11 The short-wavelength sample is the left-handed helical mirror image of (5, 6) carbon nanotubes, and the long-wavelength sample is the right-handed helical mirror image of (6, 5) carbon nanotubes, such as Figure 4 As shown. Figure 4 It is also shown that the present invention adopts S 11 Wavelength compared to S 22 The wavelength will be more accurate.

[0078] Determine S of the unknown sample 11 Wavelength

[0079] ​11) Denote the unknown sample as the first mirror image of carbon nanotubes and the second mirror image of carbon nanotubes, where the concentrations of the first mirror image of carbon nanotubes and the second mirror image of carbon nanotubes are both 3400 ng / mL; add the achiral dispersant SDBS solution (mass concentration 0.5%) to the first mirror image of carbon nanotubes and the second mirror image of carbon nanotubes respectively to obtain the dispersion of the first mirror image of carbon nanotubes and the dispersion of the second mirror image of carbon nanotubes;

[0080] 12) Add equal volumes of an aqueous solution containing achiral SDBS and chiral SHC surfactants to the dispersion of the first mirror image of carbon nanotubes and the dispersion of the second mirror image of carbon nanotubes respectively, where the mass concentration of SDBS is 0.5% and the mass concentration of SHC is 1%, to obtain the composite dispersion of the first mirror image of carbon nanotubes and the composite dispersion of the second mirror image of carbon nanotubes; in the composite dispersion, the concentration of the surfactant is 0.5% SDBS + 0.5% SHC, the concentration of the left-handed helix (5,6) carbon nanotube mirror image is 1700 ng / mL, and the concentration of the right-handed helix (6,5) carbon nanotube mirror image is 1700 ng / mL;

[0081] 13) Perform absorption spectroscopy characterization on the composite dispersion of the first mirror image of carbon nanotubes and the composite dispersion of the second mirror image of carbon nanotubes respectively to determine the S 11 wavelengths of the first mirror image of carbon nanotubes and the second mirror image of carbon nanotubes, denoted as the first S 11 wavelength and the second S 11 wavelength respectively, as Figure 5 shown.

[0082] 14) Compare the relative lengths of the first S 11 wavelength and the second S 11 wavelength to correspond to the relative lengths of the wavelengths at which the S Figure 4 of the determined (m,n) left-handed helix carbon nanotube mirror image and the (n,m) right-handed helix carbon nanotube mirror image 11 undergo a red shift:

[0083] Figure 4 The wavelength at which the S 11 of the determined (5,6) left-handed helix carbon nanotube mirror image undergoes a red shift is a short wavelength, so Figure 5 the relatively short first S 11 wavelength (blue line) corresponds to the (5,6) left-handed helix carbon nanotube mirror image, and the relatively long second S 11 wavelength (red line) corresponds to the (6,5) right-handed helix carbon nanotube mirror image;

[0084] Determination of the left-handed helical enantiomers and right-handed helical enantiomers of carbon nanotubes in an unknown sample using circular dichroism spectroscopy

[0085] 15) Perform circular dichroism spectroscopy characterization on the composite dispersion liquid of the first mirror image of carbon nanotubes and the composite dispersion liquid of the second mirror image of carbon nanotubes described in step 13). Because the (5,6) or (6,5) mirror image belongs to Type II carbon nanotubes, the circular dichroism signal of its left-handed helical mirror image is negative at the S 22 wavelength, and the circular dichroism signal of its right-handed helical mirror image is positive at the S 22 wavelength. Therefore, based on the results of circular dichroism spectroscopy characterization, as Figure 6 shown, it can be determined that the first mirror image is the left-handed helical mirror image of (5,6) carbon nanotubes, and the second mirror image is the right-handed helical mirror image of (6,5) carbon nanotubes. The characterization results based on circular dichroism spectroscopy are consistent with the characterization results in 14) above.

[0086] Example 2

[0087] Determination of the left-handed helical enantiomers of (3,8) carbon nanotubes and the right-handed helical enantiomers of (8,3) carbon nanotubes in a known sample S 11 The wavelength when redshift occurs

[0088] 1) Take 3 mL of the solutions of the left-handed helical mirror image of (3,8) carbon nanotubes and the right-handed helical mirror image of (8,3) carbon nanotubes separated by gel chromatography (where the concentrations of the left-handed helical mirror image of (3,8) carbon nanotubes and the right-handed helical mirror image of (8,3) carbon nanotubes are 1000 ng / mL respectively), and under the condition of a centrifugal force of 210000×g, perform ultracentrifugation for 60 minutes to precipitate the carbon nanotubes to the bottom of the centrifuge tube.

[0089] 2) Remove the surfactant solution in the supernatant, and then add an equal volume of 0.5% SDBS solution by mass concentration to the centrifuge tube, and use a water bath ultrasonic wave to redisperse the precipitated carbon nanotubes.

[0090] 3) Repeat steps 1) and 2).

[0091] 4) Use a cell disruptor at a power of 3 W / cm 2 To ultrasonically disperse the solutions of the left-handed helical mirror image of (3,8) carbon nanotubes and the right-handed helical mirror image of (8,3) carbon nanotubes in step 3) at a temperature of 15 °C for 30 minutes respectively, so that the carbon nanotubes are fully dispersed in the 0.5% SDBS solution by mass concentration.

[0092] 5) Centrifuge the solutions of the left-handed helical mirror image of (3,8) carbon nanotubes and the right-handed helical mirror image of (8,3) carbon nanotubes after ultrasonic treatment in step 4) under the condition of a centrifugal force of 210000×g for 15 minutes to precipitate the undispersed carbon nanotubes and impurity particles to the bottom of the centrifuge tube.

[0093] 6) Take out the 80% supernatant after centrifugation in step 5) as the solution of (3,8) carbon nanotube left-handed helix mirror image and (8,3) carbon nanotube right-handed helix mirror image dispersed in the achiral SDBS surfactant.

[0094] 7) Divide the solutions of (3,8) carbon nanotube left-handed helix mirror image and (8,3) carbon nanotube right-handed helix mirror image in step 6) into six equal parts respectively, with each part of the solution being 0.5 mL, and the mass concentration of SDBS in each part of the solution being 0.5%.

[0095] 8) Add 0.5 mL of the aqueous solution containing achiral SDBS and chiral SHC surfactant to the solutions of (3,8) carbon nanotube left-handed helix mirror image and (8,3) carbon nanotube right-handed helix mirror image in step 7) respectively. The mass concentration of SDBS is fixed at 0.5%, and the mass concentrations of chiral SHC are 0%, 0.25%, 0.5%, 1%, 2%, and 4% respectively, so that the concentrations of surfactants in the solutions of (3,8) carbon nanotube left-handed helix mirror image and (8,3) carbon nanotube right-handed helix mirror image are 0.5% SDBS + 0% SHC, 0.5% SDBS + 0.125% SHC, 0.5% SDBS + 0.25% SHC, 0.5% SDBS + 0.5% SHC, 0.5% SDBS + 1% SHC, 0.5% SDBS + 2% SHC respectively. The concentration of (3,8) carbon nanotube left-handed helix mirror image is 500 ng / mL, and the concentration of (8,3) carbon nanotube right-handed helix mirror image is 500 ng / mL.

[0096] 9) Characterize the absorption spectra and fluorescence spectra (excitation wavelength is 667 nm) of the 6 parts of the solutions of (3,8) carbon nanotube left-handed helix mirror image and 6 parts of the solutions of (8,3) carbon nanotube right-handed helix mirror image obtained in step 8). The results are as Figure 7 and 8 shown.

[0097] Figure 7 and Figure 8 shown that as the concentration of SHC increases, the S 11 absorption peak and fluorescence peak wavelength of the (3,8) carbon nanotube left-handed helix mirror image show an obvious red shift when the concentration of SHC increases to 0.5%, and tend to be stable as the concentration of SHC continues to increase; the S 11 absorption peak and fluorescence peak wavelength of the (8,3) carbon nanotube right-handed helix mirror image show a weak red shift when the concentration of SHC increases to 0.5%, and tend to be stable as the concentration of SHC continues to increase.

[0098] 10) The S of the (3,8) carbon nanotube left-handed helix mirror image and (8,3) carbon nanotube right-handed helix mirror image after being regulated by SHC (representative concentration is 0.5%)11 Due to the difference in wavelength, in this embodiment, S can be calibrated. 11 The sample with a long wavelength is the left-handed helical mirror image of (3, 8) carbon nanotubes, and the sample with a short wavelength is the right-handed helical mirror image of (8, 3) carbon nanotubes, as Figure 9 shown. Figure 9 It is also shown that the S 11 wavelength adopted by the present invention is more accurate than that adopted by S 22 wavelength.

[0099] Determine S of the unknown sample 11 Wavelength

[0100] 11) Denote the unknown sample as the first carbon nanotube mirror image and the second carbon nanotube mirror image, where the concentrations of the first carbon nanotube mirror image and the second carbon nanotube mirror image are 900 ng / mL and 440 ng / mL respectively; add the achiral dispersant SDBS solution (mass concentration 0.5%) to the first carbon nanotube mirror image and the second carbon nanotube mirror image to obtain the dispersion of the first carbon nanotube mirror image and the dispersion of the second carbon nanotube mirror image respectively;

[0101] 12) Add equal volumes of an aqueous solution containing achiral SDBS and chiral SHC surfactants to the dispersion of the first carbon nanotube mirror image and the dispersion of the second carbon nanotube mirror image respectively, where the mass concentration of SDBS is 0.5% and the mass concentration of SHC is 1%, to obtain the composite dispersion of the first carbon nanotube mirror image and the composite dispersion of the second carbon nanotube mirror image; in the composite dispersion, the concentration of the surfactant is 0.5% SDBS + 0.5% SHC, the concentration of the left-handed helical (3, 8) carbon nanotube mirror image is 450 ng / mL, and the concentration of the right-handed helical (8, 3) carbon nanotube mirror image is 220 ng / mL;

[0102] 13) Perform absorption spectrum characterization on the composite dispersion of the first carbon nanotube mirror image and the composite dispersion of the second carbon nanotube mirror image respectively to determine the S 11 wavelengths of the first carbon nanotube mirror image and the second carbon nanotube mirror image, denoted as the first S 11 wavelength and the second S 11 wavelength respectively, as Figure 10 shown.

[0103] 14) Compare the relative lengths of the first S 11 wavelength and the second S 11 wavelength to correspond to the relative lengths of the wavelengths at which the (m, n) carbon nanotube left-handed helical mirror image and the (n, m) carbon nanotube right-handed helical mirror image determined by Figure 9 undergo a red shift: 11

[0104] ​Figure 9 The S of the determined (3,8) carbon nanotube left-handed helical mirror image 11 When a redshift occurs, the wavelength is a long wavelength, so Figure 10 The relatively long first S in 11 The carbon nanotube mirror image corresponding to the wavelength (blue line) is the (3,8) carbon nanotube left-handed helical mirror image, and the relatively short second S 11 The carbon nanotube mirror image corresponding to the wavelength (red line) is the (8,3) carbon nanotube right-handed helical mirror image;

[0105] Determination of the left-handed helical enantiomers and right-handed helical enantiomers of carbon nanotubes in an unknown sample using circular dichroism spectroscopy

[0106] 15) Perform circular dichroism spectroscopy characterization on the composite dispersion liquid of the first carbon nanotube mirror image and the composite dispersion liquid of the second carbon nanotube mirror image described in step 13). Because the (3,8) or (8,3) mirror image belongs to Type I carbon nanotubes, its left-handed helical mirror image has a positive circular dichroism signal at the S 22 wavelength, and its right-handed helical mirror image has a negative signal at the S 22 wavelength. Therefore, based on the results of circular dichroism spectroscopy characterization, as Figure 11 shown, it can be judged that the first mirror image is the (3,8) carbon nanotube left-handed helical mirror image, and the second mirror image is the (8,3) carbon nanotube right-handed helical mirror image. The characterization result based on circular dichroism spectroscopy is consistent with the characterization result in 14) above.

[0107] Example 3

[0108] Determination of the left-handed helical enantiomers of (5,6) carbon nanotubes and the right-handed helical enantiomers of (6,5) carbon nanotubes in a known sample S 11 The length of the wavelength when redshift occurs

[0109] 1) Take 3 mL of the solutions of the (5,6) carbon nanotube left-handed helical mirror image and the (6,5) carbon nanotube right-handed helical mirror image separated by gel chromatography (where the concentrations of the (5,6) carbon nanotube left-handed helical mirror image and the (6,5) carbon nanotube right-handed helical mirror image are 500 ng / mL respectively), and under the condition of a centrifugal force of 210000×g, perform ultracentrifugation for 60 minutes to precipitate the carbon nanotubes to the bottom of the centrifuge tube.

[0110] 2) Remove the surfactant solution in the supernatant, and then add an equal volume of 0.5% SDS solution by mass concentration to the centrifuge tube, and use a water bath ultrasonic wave to redisperse the precipitated carbon nanotubes.

[0111] 3) Repeat steps 1) and 2).

[0112] 4) Use a cell disruptor at a power of 3 W / cm 2The (5,6) carbon nanotube left-handed helical mirror image and (6,5) carbon nanotube right-handed helical mirror image solutions in step 3) were ultrasonically dispersed for 30 minutes at a temperature of 15 °C, respectively, so that the carbon nanotubes were fully dispersed in a SDS solution with a mass concentration of 0.5%.

[0113] 5) The (5,6) carbon nanotube left-handed helical mirror image and (6,5) carbon nanotube right-handed helical mirror image solutions after ultrasonic treatment in step 4) were ultracentrifuged for 15 minutes under a centrifugal force of 210000×g, so that the undispersed carbon nanotubes agglomerated and the impurity particles precipitated to the bottom of the centrifuge tube.

[0114] 6) 80% of the supernatant after centrifugation in step 5) was taken out as the (5,6) carbon nanotube left-handed helical mirror image and (6,5) carbon nanotube right-handed helical mirror image solutions dispersed in a non-chiral SDS surfactant.

[0115] 7) The (5,6) carbon nanotube left-handed helical mirror image and (6,5) carbon nanotube right-handed helical mirror image solutions in step 6) were each divided into six equal parts, with each part of the solution being 0.5 mL, and the mass concentration of SDS in each part of the solution being 0.5%.

[0116] 8) 0.5 mL of an aqueous solution containing non-chiral SDS and chiral SHC surfactants was added to the (5,6) carbon nanotube left-handed helical mirror image and (6,5) carbon nanotube right-handed helical mirror image solutions in step 7), respectively. The mass concentration of SDBS was fixed at 0.5%, and the mass concentrations of chiral SHC were 0%, 0.2%, 0.4%, 0.8%, 1.2%, and 1.8%, respectively, so that the concentrations of surfactants in the (5,6) carbon nanotube left-handed helical mirror image and (6,5) carbon nanotube right-handed helical mirror image solutions were 0.5% SDS + 0% SHC, 0.5% SDS + 0.1% SHC, 0.5% SDS + 0.2% SHC, 0.5% SDS + 0.4% SHC, 0.5% SDS + 0.6% SHC, 0.5% SDS + 0.8% SHC, the concentration of the (5,6) carbon nanotube left-handed helical mirror image was 250 ng / mL, and the concentration of the (6,5) carbon nanotube right-handed helical mirror image was 250 ng / mL.

[0117] 9) The absorption spectra of the 6 portions of (5,6) carbon nanotube left-handed helical mirror image and 6 portions of (6,5) carbon nanotube right-handed helical mirror image solutions obtained in step 8) were characterized, and the results are as Figure 12 shown.

[0118] Figure 12 shown. As the concentration of SHC increased, the S 11 absorption peak wavelength of the (5,6) carbon nanotube left-handed helical mirror image did not change significantly; the S11 The absorption peak wavelength undergoes a slight red shift when the SHC concentration increases to 0.2%, and tends to be stable as the SHC concentration continues to increase.

[0119] 10) The difference in S wavelengths between the left-handed helical mirror image of (5,6) carbon nanotubes and the right-handed helical mirror image of (6,5) carbon nanotubes after regulation by SHC (representative concentration is 0.2%) 11 In this embodiment, the S 11 The sample with a short wavelength is the left-handed helical mirror image of (5,6) carbon nanotubes, and the one with a long wavelength is the right-handed helical mirror image of (6,5) carbon nanotubes, as Figure 13 shown. Figure 13 It is also shown that the S 11 wavelength used in the present invention is more accurate than using the S 22 wavelength.

[0120] It can be seen from this embodiment that after replacing the non-chiral surfactant with SDS, it is also applicable to the identification of the left-handed helical mirror image and the right-handed helical mirror image of carbon nanotubes.

[0121] Example 4

[0122] Determination of the left-handed helical enantiomers of (5,6) carbon nanotubes and the right-handed helical enantiomers of (6,5) carbon nanotubes in known samples with different concentrations S of the image body 11 The length of the wavelength when redshift occurs

[0123] 1) Take 3 mL of the solutions of the left-handed helical mirror image of (5,6) carbon nanotubes and the right-handed helical mirror image of (6,5) carbon nanotubes separated by gel chromatography (where the concentrations of the left-handed helical mirror image of (5,6) carbon nanotubes and the right-handed helical mirror image of (6,5) carbon nanotubes are 2000 ng / mL respectively), and under the condition of a centrifugal force of 210000×g, ultracentrifuge for 60 minutes to precipitate the carbon nanotubes to the bottom of the centrifuge tube.

[0124] 2) Remove the surfactant solution in the supernatant, and then add an equal volume of 0.5% SDBS solution by mass concentration to the centrifuge tube, and use a water bath ultrasonic wave to redisperse the precipitated carbon nanotubes.

[0125] 3) Repeat steps 1) and 2).

[0126] 4) Use a cell disruptor at a power of 3 W / cm 2 Ultrasonically disperse the solutions of the left-handed helical mirror image of (5,6) carbon nanotubes and the right-handed helical mirror image of (6,5) carbon nanotubes in step 3) at a temperature of 15°C for 30 minutes respectively to fully disperse the carbon nanotubes in the 0.5% SDBS solution by mass concentration.

[0127] 5) Centrifuge the sonicated solution of (5,6) carbon nanotube left-handed helical mirror images and (6,5) carbon nanotube right-handed helical mirror images in step 4) at a centrifugal force of 210,000×g for 15 minutes to precipitate the undispersed carbon nanotube aggregates and impurity particles to the bottom of the centrifuge tube.

[0128] 6) Take out 80% of the supernatant after centrifugation in step 5) as the solution of (5,6) carbon nanotube left-handed helical mirror images and (6,5) carbon nanotube right-handed helical mirror images dispersed in the achiral SDBS surfactant.

[0129] 7) Dilute the solution of (5,6) carbon nanotube left-handed helical mirror images and (6,5) carbon nanotube right-handed helical mirror images in step 6) with 0.5% SDBS solution to different extents. After dilution, there are 3 portions of each of the (5,6) carbon nanotube left-handed helical mirror image solution and (6,5) carbon nanotube right-handed helical mirror image solution. The carbon nanotube concentrations in the solutions are 2 μg / mL, 0.2 μg / mL, and 0.02 μg / mL respectively, and each portion of the solution is 0.5 mL. The mass concentration of SDBS in each portion of the solution is 0.5%.

[0130] 8) Add 0.5 mL of an aqueous solution containing achiral SDBS and chiral SHC surfactants to the solutions of (5,6) carbon nanotube left-handed helical mirror images and (6,5) carbon nanotube right-handed helical mirror images with different concentrations in step 7). The mass concentration of SDBS is fixed at 0.5%, and the mass concentration of chiral SHC is fixed at 1%, so that the carbon nanotube concentrations in the (5,6) carbon nanotube left-handed helical mirror image solution and (6,5) carbon nanotube right-handed helical mirror image solution are 1 μg / mL, 0.1 μg / mL, and 0.01 μg / mL respectively, and the surfactant concentration is fixed at 0.5% SDBS + 1% SHC.

[0131] 9) Characterize the 3 portions of the solutions of (5,6) carbon nanotube left-handed helical mirror images and (6,5) carbon nanotube right-handed helical mirror images obtained in step 8) by absorption spectroscopy and circular dichroism spectroscopy. The results are as Figure 14 shown (specifically, please refer to Figure 14 a, b, and c in

[0132] ). It can be seen from the characterization results that when the carbon nanotube concentration is as low as 0.01 μg / mL, the traditional circular dichroism spectroscopy can no longer identify the (5,6) carbon nanotube left-handed helical mirror images and (6,5) carbon nanotube right-handed helical mirror images.

[0133] 10) Dilute the solutions of the (5,6) carbon nanotube left-handed helix enantiomer and the (6,5) carbon nanotube right-handed helix enantiomer at a concentration of 0.01 μg / mL in step 8) with 0.5% SDBS + 1% SHC solution to further dilute the carbon nanotube concentration to 0.002 μg / mL (i.e., 2 ng / mL).

[0134] 11) Perform fluorescence spectral characterization of the solutions of the (5,6) carbon nanotube left-handed helix enantiomer and the (6,5) carbon nanotube right-handed helix enantiomer with a carbon nanotube concentration of 2 ng / mL obtained in step 10) at different integration times (excitation wavelength is 570 nm), and the results are as Figure 14 shown (specifically, please refer to Figure 14 Figure d).

[0135] It can be seen from the characterization results that by increasing the integration time, the fluorescence spectrum can identify the (5,6) carbon nanotube left-handed helix enantiomer and the (6,5) carbon nanotube right-handed helix enantiomer with an ultra-low concentration (2 ng / mL).

Claims

1. A method for identifying left-handed and right-handed carbon nanotube mirror images, comprising the following steps: (I) Determination of the S of the left-handed helical mirror image of (m, n) carbon nanotubes and the right-handed helical mirror image of (n, m) carbon nanotubes in a known sample 11 The length of wavelength when redshift occurs (I-1) dispersing a known sample (m, n) carbon nanotube left-handed helical mirror image and a known sample (n, m) carbon nanotube right-handed helical mirror image in a non-chiral dispersant solution to obtain a plurality of dispersions of the (m, n) carbon nanotube left-handed helical mirror image and a plurality of dispersions of the (n, m) carbon nanotube right-handed helical mirror image; (I-2) adding chiral dispersant solutions of different mass concentrations to the dispersions of the plurality of (m, n) carbon nanotube left-handed mirror images and the dispersions of the plurality of (n, m) carbon nanotube right-handed mirror images, respectively, while maintaining the concentration of the achiral dispersant in each dispersion of the (m, n) carbon nanotube left-handed mirror image and each dispersion of the (n, m) carbon nanotube right-handed mirror image unchanged, so as to obtain composite dispersions of the plurality of (m, n) carbon nanotube left-handed mirror images and the plurality of (n, m) carbon nanotube right-handed mirror image; (I-3) performing absorption spectroscopy and / or fluorescence spectroscopy on the composite dispersions of the plurality of (m, n) carbon nanotube left-handed helical mirror images and the composite dispersions of the plurality of (n, m) carbon nanotube right-handed helical mirror images to determine the S 11 The length of the wavelength when the red shift occurs is the same as the S of the left-handed mirror image of the (m, n) carbon nanotube and the right-handed mirror image of the (n, m) carbon nanotube. 11 The concentration of the chiral dispersant solution added when the red shift just begins is recorded as the representative concentration C; (II) Determination of S of unknown samples 11 wavelength (II-1) recording the unknown samples as the first mirror image of the carbon nanotube and the second mirror image of the carbon nanotube; adding the non-chiral dispersant solution to the first mirror image of the carbon nanotube and the second mirror image of the carbon nanotube to obtain a dispersion of the first mirror image of the carbon nanotube and a dispersion of the second mirror image of the carbon nanotube, respectively; (II-2) adding a chiral dispersant solution having a concentration greater than or equal to the representative concentration C to the dispersion of the first mirror image form of the carbon nanotubes and the dispersion of the second mirror image form of the carbon nanotubes, respectively, while maintaining the concentration of the achiral dispersant in the dispersion of the first mirror image form of the carbon nanotubes and the dispersion of the second mirror image form of the carbon nanotubes unchanged, to obtain a composite dispersion of the first mirror image form of the carbon nanotubes and a composite dispersion of the second mirror image form of the carbon nanotubes; (II-3) performing absorption spectroscopy and / or fluorescence spectroscopy on the composite dispersion of the first mirror image of the carbon nanotubes and the composite dispersion of the second mirror image of the carbon nanotubes, respectively, to determine the S of the first mirror image of the carbon nanotubes and the second mirror image of the carbon nanotubes. 11 wavelength, respectively, denoted as the first S 11 Wavelength and second S 11 wavelength; (III) Determine the left and right helical mirror images of unknown samples Compare First S 11 Wavelength and second S 11 The relative length of the wavelength is determined by comparing the S of the left-handed mirror image of the (m, n) carbon nanotube and the right-handed mirror image of the (n, m) carbon nanotube in step (I-3). 11 The length of the wavelength when redshift occurs corresponds to: If the S of the left-handed helical mirror image of the (m, n) carbon nanotube determined in step (I-3) 11 The wavelength when red shift occurs is short wavelength, so the first S 11 Wavelength and second S 11 The mirror image of the carbon nanotube corresponding to the relatively short wavelength is the left-handed helical mirror image of the (m, n) carbon nanotube. 11 Wavelength and second S 11 The mirror image of the carbon nanotube corresponding to the relatively long wavelength is the right-handed helical mirror image of the (n, m) carbon nanotube; If the S of the left-handed helical mirror image of the (m, n) carbon nanotube determined in step (I-3) 11 The wavelength when red shift occurs is long wavelength, so the first S 11 Wavelength and second S 11 The mirror image of the carbon nanotube corresponding to the relatively long wavelength is the left-handed helical mirror image of the (m, n) carbon nanotube. 11 Wavelength and second S 11 The mirror image of the carbon nanotube corresponding to the relatively shorter wavelength is the right-handed helical mirror image of the (n, m) carbon nanotube.

2. The method according to claim 1, wherein: The number of portions is N portions, 3≤N≤100.

3. The method according to claim 1, wherein: The achiral dispersant is an achiral surfactant or polymer capable of dispersing carbon nanotubes.

4. The method according to claim 1, wherein: The achiral dispersant is selected from sodium dodecylbenzene sulfonate and / or sodium dodecyl sulfate surfactants.

5. The method according to claim 1, wherein: The chiral dispersant is a chiral surfactant or polymer capable of dispersing carbon nanotubes.

6. The method according to claim 1, wherein: The chiral dispersant is sodium hyodeoxycholate surfactant.

7. The method according to claim 1, wherein: In the chiral dispersant solutions of different mass concentrations in the step (I-2), the mass concentration of each chiral dispersant solution is 0-10%; the chiral dispersant solutions of different mass concentrations are arranged from small to large, the mass concentration of the chiral dispersant solution with the smallest mass concentration is 0-0.1% and the mass concentration difference between two adjacent chiral dispersant solutions is 0.1%-0.5%.

8. The method according to claim 1, wherein: The mass concentration of the non-chiral dispersant solution is 0.1%-5%.

9. The method according to claim 1, wherein: In the composite dispersion of the left-handed helical mirror image of (m, n) carbon nanotubes in step (I-2), the composite dispersion of the right-handed helical mirror image of (n, m) carbon nanotubes in step (I-2), the composite dispersion of the first mirror image of carbon nanotubes in step (II-2), and the composite dispersion of the second mirror image of carbon nanotubes in step (II-2), the concentrations of the left-handed helical mirror image of (m, n) carbon nanotubes, the concentration of the right-handed helical mirror image of (n, m) carbon nanotubes, the concentration of the first mirror image of carbon nanotubes, and the concentration of the second mirror image of carbon nanotubes are each independently greater than or equal to 2 ng / mL on a weight / volume basis.

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