A surface-modified carbon nanotube, its preparation method and application
By introducing active groups on the surface of carbon nanotubes and grafting an epoxy group GA-HMDA layer, the problem of difficult bonding between carbon nanotubes and matrix materials was solved, thereby improving their dispersibility and the mechanical properties of the composite material.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANDONG ANNENGTAI OIL & GAS STIMULATION TECH RES INST CO LTD
- Filing Date
- 2026-02-09
- Publication Date
- 2026-05-26
AI Technical Summary
Carbon nanotubes have high crystallinity and few surface defects, making them difficult to effectively combine with matrix materials. They are also difficult to disperse uniformly in organic solvents and polymer matrices, which limits their application in composite materials, catalysis, and biomedicine.
Active groups such as carboxyl groups are introduced onto the surface of carbon nanotubes by acid treatment, and the nanotubes are modified using silane coupling agent KH-590. An organic modification layer containing epoxy groups is constructed by grafting GA-HMDA layer through a mercapto-epoxy click reaction, which enhances the dispersibility of carbon nanotubes and their interfacial bonding ability with the polymer matrix.
It significantly improves the dispersibility and interfacial bonding ability of carbon nanotubes, enhances the mechanical properties of composite materials, effectively reduces the entanglement between carbon nanotubes, and promotes stress transfer and interfacial cross-linking.
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Figure CN122079142A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of carbon nanotube technology, specifically to a surface-modified carbon nanotube, its preparation method, and its application. Background Technology
[0002] Carbon nanotubes are a novel material with extremely high mechanical, thermal, electrical, and chemical properties. Due to their unique one-dimensional nanostructure, excellent mechanical properties, electrical properties, and chemical stability, carbon nanotubes have shown great application potential in many fields, such as composite materials and electronic information materials. However, carbon nanotubes exhibit high chemical inertness due to their high crystallinity and few surface defects, resulting in a lack of bonding activity with matrix materials and difficulty in achieving effective interfacial bonding. Furthermore, the chemical inertness of the carbon nanotube surface, coupled with entanglement, often makes them difficult to disperse in composite materials. They are also difficult to disperse uniformly in common organic solvents and polymer matrices, limiting their widespread application in composite materials, catalysis, and biomedicine. To address this issue, surface modification of carbon nanotubes is necessary to improve their dispersibility and compatibility with other materials. In the prior art, Yang et al. chemically grafted hyperbranched polyurethane with hydroxyl-terminated ends onto carbon nanotubes (see Yingkui Yang, Xiaolin Xie, JingaoWu, et al., Multiwalled Carbon Nanotubes Functionalized by Hyperbranched Poly(urea-urethane)s by a One-Pot Polycondensation. Macromol. Rapid Commun; 2006;27; 1695-1701.). The modified carbon nanotubes obtained have good dispersibility in polar solvents, but their thermal decomposition temperature is lower than that of the original carbon nanotubes. Summary of the Invention
[0003] To address the shortcomings of existing technologies, this invention proposes a surface-modified carbon nanotube, its preparation method, and its application.
[0004] This invention is achieved through the following technical solution: A surface-modified carbon nanotube, the preparation method of which includes the following steps: S1. Carbon nanotubes were added to a nitric acid / sulfuric acid mixed solution, ultrasonically dispersed at 100 kHz, stirred and refluxed at 60-70℃ for 4 h, added to a large amount of deionized water, cooled, filtered, washed with anhydrous ethanol and distilled water, and dried to obtain pretreated carbon nanotubes. S2. Mix anhydrous ethanol and distilled water, add the pretreated carbon nanotubes obtained in step S1, add silane coupling agent KH-590, adjust the pH value to 4, sonicate for 1 h, reflux at 70-80℃ for 6 h, filter, wash with deionized water and anhydrous ethanol, dry, and obtain mercapto-modified carbon nanotubes. S3. Gallic acid (GA), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDCI) and 1-hydroxybenzotriazole (HOBt) were dissolved in DMF and stirred in an ice-water bath at 0°C for 1 h. 4,4'-diaminodicyclohexylmethane (HMDA) and triethylamine dissolved in DMF were added dropwise. The reaction was carried out at 0°C for 30 min and continued at room temperature for 24 h. The mixture was washed with distilled water, the solvent was removed under reduced pressure, and the mixture was purified by chromatography to obtain GA-HMDA. S4. Add the GA-HMDA obtained in step S3 to epichlorohydrin, stir and heat to 90°C, add tetrabutylammonium iodide, react at 100°C for 6 h, cool to 50°C, add NaOH in four portions at 30 min intervals, react at 70°C for 1 h, cool to room temperature, wash with deionized water, distill under reduced pressure, and dry under vacuum to obtain epoxy GA-HMDA. S5. The epoxy-based GA-HMDA, mercapto-modified carbon nanotubes and triethylamine obtained in step S4 were added to a methanol / chloroform (v:v=5:1) mixture and stirred at 40℃ and 200-300 rpm for 24 h. The mixture was then filtered, washed with methanol and THF, and dried under vacuum to obtain surface-modified carbon nanotubes.
[0005] Further, in step S1, the nitric acid / sulfuric acid mixed solution is prepared by mixing 65wt% concentrated nitric acid solution and 96wt% concentrated sulfuric acid solution in a volume ratio of 1:3.
[0006] Further, in step S1, the mass concentration of the carbon nanotubes in the nitric acid / sulfuric acid mixed solution is 10 mg / mL.
[0007] Furthermore, in step S2, the volume ratio of anhydrous ethanol to distilled water is 4:1.
[0008] Furthermore, in step S2, the ratio of the pretreated carbon nanotubes to distilled water is 1 g: 20 mL.
[0009] Furthermore, in step S2, the volume ratio of KH-590 to distilled water is 1:5.
[0010] Further, in step S3, the ratio of 4,4'-diaminodicyclohexylmethane, gallic acid, EDCI, HOBt to triethylamine is 0.5 g:1 g:1.4 g:1 g:2.5 mL.
[0011] Further, in step S3, the mass concentration of gallic acid in DMF is 50 mg / mL.
[0012] Further, in step S3, the mass concentration of the 4,4'-diaminodicyclohexylmethane in DMF is 20 mg / mL.
[0013] Further, in step S4, the ratio of GA-HMDA, epichlorohydrin, tetrabutylammonium iodide and NaOH is 1 g:6 mL:2 mg:0.4 g.
[0014] Furthermore, in step S5, the ratio of the amount of epoxy-based GA-HMDA, mercapto-based carbon nanotubes, and triethylamine is 2 g: 2 g: 1 mL.
[0015] Further, in step S5, the mass concentration of the mercaptoized carbon nanotubes in the methanol / chloroform (v:v=5:1) mixture is 10 mg / mL.
[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a surface-modified carbon nanotube, its preparation method, and its application. The method involves introducing active groups such as carboxyl groups onto the surface of carbon nanotubes through acid treatment, followed by modification using the silane coupling agent KH-590 to covalently graft thiol groups onto the carbon nanotube surface, resulting in thiolized carbon nanotubes. Subsequently, a GA-HMDA layer containing epoxy groups is grafted onto the carbon nanotube surface, significantly improving the dispersibility of the carbon nanotubes and their interfacial bonding ability with the polymer matrix, effectively enhancing the mechanical properties of the composite material. In this invention, the carbon nanotubes, after acid pretreatment, introduce oxygen-containing functional groups such as carboxyl groups onto their surface, enhancing their hydrophilicity and reactivity. Subsequent modification with the silane coupling agent KH-590 introduces thiol groups, which further react with the epoxy group GA-HMDA in a thiol-epoxy click reaction, constructing an organic modification layer on the carbon nanotube surface and effectively reducing van der Waals entanglement between carbon nanotubes. This invention designs and synthesizes epoxy-based GA-HMDA. The GA-HMDA is obtained by forming an amide bond between the carboxyl group of gallic acid and the amino group of 4,4'-diaminodicyclohexylmethane under the action of EDCI and HOBt. Subsequently, epoxy-rich GA-HMDA is generated under the action of epichlorohydrin. Through a highly efficient "thiol-epoxy" click chemical reaction between its epoxy groups and the thiol groups on the surface of thiolized carbon nanotubes, it is firmly anchored to the carbon nanotube surface. Simultaneously, the introduction of the rigid benzene ring structure of gallic acid and the cyclohexane structure derived from 4,4'-diaminodicyclohexylmethane effectively reduces the aggregation between carbon nanotubes and improves their dispersibility. The surface-modified carbon nanotubes prepared by this invention have epoxy groups GA-HMDA on their surface containing multiple active groups. The modification layer not only improves dispersibility, but also forms covalent or hydrogen bonds with the polymer matrix (such as epoxy resin), generating strong chemical crosslinks at the interface. This facilitates the effective transfer of stress from the matrix to the carbon nanotubes, fully utilizes the high strength characteristics of carbon nanotubes, inhibits interfacial slippage, and thus improves the mechanical properties of the composite material. Attached Figure Description
[0017] Figure 1 This demonstrates the tensile strength enhancement effect of the surface-modified carbon nanotubes described in Examples 1-3 and Comparative Examples 1-3 of the present invention. Figure 2 The chemical structure diagram of the epoxy group GA-HMDA described in Example 1 of this invention is shown. Figure 3 The 1H NMR spectrum of the epoxy group GA-HMDA described in Example 1 of this invention; Figure 4 The images shown are scanning electron microscope (SEM) images of carbon nanotubes from embodiments of the present invention, where A represents untreated raw carbon nanotubes and B represents surface-modified carbon nanotubes from Example 1. Detailed Implementation
[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. However, this invention is not limited to the following embodiments. It should be noted that, unless otherwise specified, all chemical reagents involved in this invention are purchased through commercial channels.
[0020] Example 1: A surface-modified carbon nanotube, the preparation method of which includes the following steps: S1. Add 1 g of carbon nanotubes to 100 mL of a nitric acid / sulfuric acid mixed solution. The nitric acid / sulfuric acid mixed solution is a mixture of 65 wt% concentrated nitric acid solution and 96 wt% concentrated sulfuric acid solution in a volume ratio of 1:3. Disperse the mixture by ultrasonication at 100 kHz, stir and reflux at 70 °C for 4 h, add a large amount of deionized water, cool, filter, wash with anhydrous ethanol and distilled water, and dry to obtain pretreated carbon nanotubes. S2. Mix 80 mL of anhydrous ethanol and 20 mL of distilled water, add 1 g of the pretreated carbon nanotubes obtained in step S1, add 4 mL of silane coupling agent KH-590, adjust the pH value to 4, sonicate for 1 h, reflux at 80℃ for 6 h, filter, wash with deionized water and anhydrous ethanol, and dry to obtain thiolized carbon nanotubes. S3. Dissolve 1 g of gallic acid (GA), 1.4 g of EDCI and 1 g of HOBt in 20 mL of DMF, stir in an ice-water bath at 0 °C for 1 h, add dropwise 0.5 g of 4,4'-diaminodicyclohexylmethane (HMDA) dissolved in 25 mL of DMF and 2.5 mL of triethylamine, react at 0 °C for 30 min, continue the reaction at room temperature for 24 h, wash with distilled water, remove solvent under reduced pressure, and purify by chromatography to obtain GA-HMDA; S4. Add 1 g of GA-HMDA obtained in step S3 to 6 mL of epichlorohydrin, stir and heat to 90 °C, add 2 mg of tetrabutylammonium iodide, react at 100 °C for 6 h, cool to 50 °C, add 0.4 g of NaOH in four portions at 30 min intervals, react at 70 °C for 1 h, cool to room temperature, wash with deionized water, distill under reduced pressure, and dry under vacuum to obtain epoxy GA-HMDA; S5. Add 1 g of epoxy-based GA-HMDA, 1 g of mercapto-modified carbon nanotubes and 0.5 mL of triethylamine obtained in step S4 to 100 mL of methanol / chloroform (v:v=5:1) mixture and stir at 40℃ and 300 rpm for 24 h. Filter, wash with methanol and THF, and dry under vacuum to obtain surface-modified carbon nanotubes.
[0021] Example 2: A surface-modified carbon nanotube, the preparation method of which includes the following steps: S1. Add 1 g of carbon nanotubes to 100 mL of a nitric acid / sulfuric acid mixed solution. The nitric acid / sulfuric acid mixed solution is a mixture of 65 wt% concentrated nitric acid solution and 96 wt% concentrated sulfuric acid solution in a volume ratio of 1:3. Disperse the mixture by ultrasonication at 100 kHz, stir and reflux at 60 °C for 4 h, add a large amount of deionized water, cool, filter, wash with anhydrous ethanol and distilled water, and dry to obtain pretreated carbon nanotubes. S2. Mix 80 mL of anhydrous ethanol and 20 mL of distilled water, add 1 g of the pretreated carbon nanotubes obtained in step S1, add 4 mL of silane coupling agent KH-590, adjust the pH value to 4, sonicate for 1 h, reflux at 70℃ for 6 h, filter, wash with deionized water and anhydrous ethanol, and dry to obtain thiolized carbon nanotubes. S3. Dissolve 1 g of gallic acid (GA), 1.4 g of EDCI and 1 g of HOBt in 20 mL of DMF, stir in an ice-water bath at 0 °C for 1 h, add dropwise 0.5 g of 4,4'-diaminodicyclohexylmethane (HMDA) dissolved in 25 mL of DMF and 2.5 mL of triethylamine, react at 0 °C for 30 min, continue the reaction at room temperature for 24 h, wash with distilled water, remove solvent under reduced pressure, and purify by chromatography to obtain GA-HMDA; S4. Add 1 g of GA-HMDA obtained in step S3 to 6 mL of epichlorohydrin, stir and heat to 90 °C, add 2 mg of tetrabutylammonium iodide, react at 100 °C for 6 h, cool to 50 °C, add 0.4 g of NaOH in four portions at 30 min intervals, react at 70 °C for 1 h, cool to room temperature, wash with deionized water, distill under reduced pressure, and dry under vacuum to obtain epoxy GA-HMDA; S5. Add 1 g of epoxy-based GA-HMDA, 1 g of mercapto-modified carbon nanotubes and 0.5 mL of triethylamine obtained in step S4 to 100 mL of methanol / chloroform (v:v=5:1) mixture and stir at 40℃ and 200 rpm for 24 h. Filter, wash with methanol and THF, and dry under vacuum to obtain surface-modified carbon nanotubes.
[0022] Example 3: A surface-modified carbon nanotube, the preparation method of which includes the following steps: S1. Add 1 g of carbon nanotubes to 100 mL of a nitric acid / sulfuric acid mixed solution. The nitric acid / sulfuric acid mixed solution is a mixture of 65 wt% concentrated nitric acid solution and 96 wt% concentrated sulfuric acid solution in a volume ratio of 1:3. Disperse the mixture by ultrasonication at 100 kHz, stir and reflux at 65 °C for 4 h, add a large amount of deionized water, cool, filter, wash with anhydrous ethanol and distilled water, and dry to obtain pretreated carbon nanotubes. S2. Mix 80 mL of anhydrous ethanol and 20 mL of distilled water, add 1 g of the pretreated carbon nanotubes obtained in step S1, add 4 mL of silane coupling agent KH-590, adjust the pH to 4, sonicate for 1 h, reflux at 75℃ for 6 h, filter, wash with deionized water and anhydrous ethanol, and dry to obtain thiolized carbon nanotubes. S3. Dissolve 1 g of gallic acid (GA), 1.4 g of EDCI and 1 g of HOBt in 20 mL of DMF, stir in an ice-water bath at 0 °C for 1 h, add dropwise 0.5 g of 4,4'-diaminodicyclohexylmethane (HMDA) and triethylamine dissolved in 25 mL of DMF, react at 0 °C for 30 min, continue the reaction at room temperature for 24 h, wash with distilled water, remove solvent under reduced pressure, and purify by chromatography to obtain GA-HMDA; S4. Add 1 g of GA-HMDA obtained in step S3 to 6 mL of epichlorohydrin, stir and heat to 90 °C, add 2 mg of tetrabutylammonium iodide, react at 100 °C for 6 h, cool to 50 °C, add 0.4 g of NaOH in four portions at 30 min intervals, react at 70 °C for 1 h, cool to room temperature, wash with deionized water, distill under reduced pressure, and dry under vacuum to obtain epoxy GA-HMDA; S5. Add 1 g of epoxy-based GA-HMDA, 1 g of mercapto-modified carbon nanotubes and 0.5 mL of triethylamine obtained in step S4 to 100 mL of methanol / chloroform (v:v=5:1) mixture and stir at 40℃ and 250 rpm for 24 h. Filter, wash with methanol and THF, and dry under vacuum to obtain surface-modified carbon nanotubes.
[0023] The only difference between Comparative Example 1 and Example 1 is that gallic acid is used instead of GA-HMDA.
[0024] The only difference between Comparative Example 2 and Example 1 is that mercapto-modified carbon nanotubes are used instead of surface-modified carbon nanotubes.
[0025] The only difference between Comparative Example 3 and Example 1 is that pretreated carbon nanotubes are used instead of surface-modified carbon nanotubes.
[0026] Example 1: Epoxy resin E-51 was preheated at 60℃ for 30 min. Surface-modified carbon nanotubes were ground uniformly and mixed into an acetone solution. The mixture was ultrasonically dispersed for 1 h. Epoxy resin E-51 was then added to the uniformly dispersed carbon nanotube acetone solution. The mixture was magnetically stirred at 60℃ for 2 h and ultrasonically dispersed for 1 h. Acetone was removed by vacuum distillation. Diethylenetriamine (epoxy resin to curing agent ratio 10:1, surface-modified carbon nanotube mass fraction 1 wt%) was added and ultrasonically dispersed for 30 min. The mixture was poured into a mold and placed in a vacuum drying oven. Vacuum degassing was performed at 60℃ for 30 min. Curing was carried out using a process of 80℃ / 1h + 100℃ / 1h + 120℃ / 2h + 150℃ / 2h + 180℃ / 2h to obtain the composite material. The tensile strength of the composite material was tested, and the results are as follows: Figure 1 As shown.
[0027] Figure 1 The results showed that the tensile strength of the composite materials in Examples 1-3 was significantly better than that in Comparative Examples 1-3. In Comparative Example 1, the tensile strength of the material decreased when gallic acid was used to replace GA-HMDA. In Comparative Example 2, the mechanical properties of the composite material decreased and the tensile strength decreased when mercapto-modified carbon nanotubes were used to replace surface-modified carbon nanotubes. In Comparative Example 3, the tensile properties of the composite material decreased when pretreated carbon nanotubes were used to replace surface-modified carbon nanotubes.
[0028] Experimental Example 2: Epoxy-based GA-HMDA was prepared according to the method in Example 1, and its chemical structural formula is as follows: Figure 2 As shown, Figure 2 The results showed that the carboxyl group of gallic acid and the amino group of 4,4'-diaminodicyclohexylmethane underwent an amide reaction catalyzed by EDCI and HOBt. Gallic acid and 4,4'-diaminodicyclohexylmethane were covalently bonded, and the resulting product contained the phenolic hydroxyl group of gallic acid. With the aid of epichlorohydrin, an epoxy group was introduced to prepare epoxy-based GA-HMDA. The 1H NMR spectrum is shown below. Figure 3 As shown, 1 H NMR (300 MHz, DMSO-d6), chemical shifts δ: 7.82 (2H), 7.17 (4H), 4.17 (6H), 3.92 (6H), 3.54 (2H), 3.04 (6H), 2.60 (6H), 2.35 (6H), 1.77 (4H), 1.62 (4H), 1.52(4H), 1.50 (2H), 1.38 (4H), 1.13 (2H).
[0029] Experimental Example 3: Scanning electron microscopy (SEM) images were taken of untreated raw carbon nanotubes and surface-modified carbon nanotubes obtained in Example 1. The results are as follows: Figure 4 As shown, Figure 4The results showed that the unmodified carbon nanotubes were uneven in thickness and severely entangled, while the surface-modified carbon nanotubes were more uniform in thickness and their basic structure remained unchanged. This indicates that the surface-modified carbon nanotubes were successfully prepared and that surface modification does not damage the structure of the carbon nanotubes.
[0030] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.
Claims
1. A surface-modified carbon nanotube, characterized in that, The preparation method includes the following steps: S1. Carbon nanotubes are added to a nitric acid / sulfuric acid mixed solution, ultrasonically dispersed, refluxed, added to deionized water, cooled, filtered, washed, and dried to obtain pretreated carbon nanotubes; S2. Mix anhydrous ethanol and distilled water, add the pretreated carbon nanotubes obtained in step S1, add silane coupling agent KH-590, adjust the pH value, sonicate, reflux, filter, wash, and dry to obtain mercapto-modified carbon nanotubes. S3. Gallic acid, EDCI and HOBt were dissolved in DMF, stirred at 0°C, and 4,4'-diaminodicyclohexylmethane and triethylamine were added dropwise. The mixture was reacted, washed, and purified to obtain GA-HMDA. S4. Add the GA-HMDA obtained in step S3 to epichlorohydrin, stir and heat, add tetrabutylammonium iodide, react, cool, add NaOH, react, cool, wash, distill under reduced pressure, and dry to obtain epoxy GA-HMDA; S5. Add the epoxy-based GA-HMDA, mercaptoized carbon nanotubes and triethylamine obtained in step S4 to a methanol / chloroform mixture, stir and react, filter, wash and dry to obtain surface-modified carbon nanotubes.
2. The surface-modified carbon nanotubes according to claim 1, characterized in that, In step S1, the nitric acid / sulfuric acid mixed solution is prepared by mixing 65wt% concentrated nitric acid solution and 96wt% concentrated sulfuric acid solution in a volume ratio of 1:3; the mass concentration of carbon nanotubes in the nitric acid / sulfuric acid mixed solution is 10 mg / mL.
3. The surface-modified carbon nanotubes according to claim 2, characterized in that, In step S2, the volume ratio of anhydrous ethanol to distilled water is 4:1; the volume ratio of pretreated carbon nanotubes to distilled water is 1 g:20 mL; and the volume ratio of KH-590 to distilled water is 1:
5.
4. The surface-modified carbon nanotubes according to claim 3, characterized in that, In step S3, the ratio of 4,4'-diaminodicyclohexylmethane, gallic acid, EDCI, HOBt to triethylamine is 0.5 g:1 g:1.4 g:1 g:2.5 mL.
5. The surface-modified carbon nanotubes according to claim 4, characterized in that, In step S4, the ratio of GA-HMDA, epichlorohydrin, tetrabutylammonium iodide and NaOH is 1 g:6 mL:2 mg:0.4 g.
6. The surface-modified carbon nanotubes according to claim 5, characterized in that, In step S5, the ratio of epoxy group GA-HMDA, mercaptoized carbon nanotubes and triethylamine is 2 g:2 g:1 mL.