CN109279595B - Preparation method of aliphatic amine modified carbon nano tube - Google Patents

Abstract

The invention discloses a preparation method of fatty amine modified carbon nano-tubes, which comprises the following steps: respectively dissolving aliphatic amine and nitrite in a solvent to obtain two solutions, and precooling the two solutions for later use; adding a carbon nano tube into a solvent, adding a small amount of acid, and controlling the temperature to be-80-20 ℃; and (3) dripping the pre-cooled aliphatic amine solution and nitrite solution into a mixture of the carbon nano tube, a small amount of acid and a solvent for reaction, recovering the solvent after the reaction is finished, and filtering and washing to obtain the aliphatic amine modified carbon nano tube. The method has the advantages of simple process operation and high product yield, improves the wave absorption of the product, and is suitable for large-scale industrial production.

Description

A kind of preparation method of aliphatic amine modified carbon nanotubes

technical field

The invention relates to the technical field of manufacture of modified carbon nanotubes, in particular to a preparation method of aliphatic amine modified carbon nanotubes.

Background technique

Carbon nanotubes have unique structural, mechanical and electrical properties, and have been widely used in the fields of light, electricity, magnetism, and biology. However, in the process of use and modification, carbon nanotubes are easily aggregated into bundles in solution, which limits their production applications. In recent years, much research has been devoted to the development of new adsorbents. Attach some groups to carbon nanotubes for improved adsorption and recovery. The introduction of carboxyl groups, amine groups, sulfonic acid groups and other groups on carbon nanotubes can increase the dispersibility of carbon nanotubes in solution. The research on improving the adsorption and selectivity of carbon nanotubes has become a new focus.

In addition, carbon nanotubes show certain wave-absorbing properties. With the continuous development of science and technology in my country, the demand for wave-absorbing is constantly increasing. Improving the wave-absorbing properties of carbon nanotube materials has become one of the hot spots. Dispersing and compounding the modified carbon nanotubes can often improve their wave-absorbing properties, and at the same time, the performance of the modified carbon nanotubes in adsorbing small molecular pollutants is also enhanced. Common modification methods include doping modification method and chemical reaction modification method. Due to the low hydrophilicity of carbon nanotubes and the immaturity of the modification method, the modification of safely connecting amine groups to carbon nanotubes. Sexual methods are a difficult problem in current research.

Therefore, in combination with the above problems, it is urgent to provide a preparation method of aliphatic amine modified carbon nanotubes that can stably connect amine groups and carbon nanotubes to obtain a high wave absorbing performance and good adsorption performance, which is urgently needed by those skilled in the art solved problem.

SUMMARY OF THE INVENTION

In view of this, the present invention provides a preparation method of aliphatic amine modified carbon nanotubes. The preparation method of the present invention has simple process operation, high product yield, improved product wave absorption, and is suitable for large-scale industrial production.

The present invention forms stable chemical bonds by reacting carbocations with carbon nanotubes, and connects amine groups with carbon nanotubes to obtain amine-modified carbon nanotubes, wherein the reaction equation is as follows:

R'ONO+RCH ₂ NH ₂ →RCH ₂ N ₂ ⁺ +R'OH

RCH ₂ N ₂ ⁺ →RCH ₂ ⁺ +N ₂

RCH ₂ ⁺ +R”C=CR”→R”CC(R”)CH ₂ R

In order to achieve the above object, the technical scheme adopted in the present invention is as follows:

S1, the aliphatic amine is dissolved in the solvent, and the obtained solution is pre-cooled for subsequent use;

S2, the nitrites are dissolved in the solvent, and the obtained solution is pre-cooled for subsequent use;

S3, adding carbon nanotubes to the solvent, adding a small amount of acid, and controlling the temperature to be -80 to 20°C;

S4, adjust the volume of S1 and S2 with a solvent to make the two volumes equal, and drop the two mixed solutions obtained in steps S1 and S2 into the mixture of carbon nanotubes, acid and solvent obtained in step S3 at the same speed at the same time and stir, After the dropwise addition is completed, a temperature-controlled reaction is performed, and after the reaction is completed, the reaction is naturally returned to room temperature, the solvent is recovered, and the aliphatic amine modified carbon nanotubes are obtained through filtration and washing;

Wherein, the solvent is one or two or a mixture of two or more of acetonitrile, tetrahydrofuran and ether;

The reaction is carried out under the protection of inert gas.

As can be seen from the above technical solutions, compared with the prior art, the beneficial effects of the present invention are as follows:

The technical scheme of the present invention forms stable chemical bonds by reacting aliphatic amines with carbon nanotubes, connects the amine groups to the carbon nanotubes, improves the dispersibility of carbon nanotubes, avoids uneven distribution of carbon nanotubes during copolymerization, and improves the The yield of the product; dropwise slowly, so that the reaction is carried out at low temperature and low concentration, to avoid the accumulation of unstable intermediates; fully stirring, so that the unstable intermediates can be rapidly diffused and reacted; the technical scheme of the present invention avoids explosion and enables the reaction to The process is carried out smoothly and safely, and the product yield is over 80%, and the final product is easily separated from the raw material. The method of the invention can prepare a large amount of amine-modified carbon nanotubes under normal temperature conditions, and is suitable for large-scale industrial production.

Preferably, the aliphatic amine in the step S1 includes but is not limited to 1,4-cyclohexanediamine, diethylenetriamine, and triethylenetetramine.

Preferably, the nitrites in the step S2 are isopropyl nitrite or methyl nitrite.

Preferably, the acid in the step S3 includes but is not limited to malonic acid and benzoic acid.

Preferably, in the steps S1 and S2, the pre-cooling treatment is performed, and the temperature is controlled to be -80-20°C.

Preferably, in the step S4, the reaction temperature is controlled to be -80-20°C.

Preferably, the dropwise addition time in the step S4 is 0.1-4h.

Preferably, the reaction time in the step S4 is 5-24h.

Preferably, the ratio of the amount of carbon in the carbon nanotube to the amount of aliphatic amine is 1:0.01-100.

Preferably, the amounts of the fatty amine and nitrite are equal.

To sum up, the technical solution disclosed in the present invention enhances the dispersibility of carbon nanotubes, ensures that carbon nanotubes are not easily aggregated into bundles in solution, and connects aliphatic amines to carbon nanotubes, aliphatic chains increase fat solubility, and amines The base enhances water solubility and modifiability, overcomes the problem that amine groups cannot be stably connected to carbon nanotubes, and the synthesis method of the present invention is beneficial to the development and application of low-concentration metal ion enrichment, and provides a candidate for the development of absorbing materials. Material.

Detailed ways

The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Example 1:

Embodiment 1 of the present invention discloses a preparation method of aliphatic amine modified carbon nanotubes, and the technical scheme adopted is as follows:

S1, dissolve 0.33moL (37.7g) of 1,4-cyclohexanediamine in solvent acetonitrile, and the volume ratio of 1,4-cyclohexanediamine to acetonitrile is 1:8 to obtain 1,4-cyclohexanediamine Solution, control the temperature to -80 ℃, pre-cool for use;

S2, dissolve 0.33moL (31.0g) of isopropyl nitrite in solvent acetonitrile, and the volume ratio of isopropyl nitrite to acetonitrile is 1:8 to obtain isopropyl nitrite solution, and the control temperature is -80 °C, and the pre- Cold standby, add a small amount of solvent acetonitrile, adjust the volume of 1,4-cyclohexanediamine solution and isopropyl nitrite solution to make the two volumes equal;

S3, under nitrogen protection, select a 500mL round-bottom flask, put 4g carbon nanotubes, 50mL acetonitrile, 0.033moL (3.4g) malonic acid, and control the temperature to -50°C;

S4, simultaneously add the solution obtained in steps S1 and S2 dropwise at the same speed to the mixture of carbon nanotubes, acid and solvent obtained in step S3, and stir and control the temperature to -50°C, the dropwise addition time is about 0.5h, after the dropwise addition, the reaction 12h, after the reaction is completed, it is naturally returned to room temperature, the solvent is recovered, filtered and washed to obtain amine group-modified carbon nanotubes.

The yield of the amine-modified carbon nanotubes prepared in this example was 80%, and the samples were taken for performance testing.

Example 2:

Embodiment 2 of the present invention discloses a preparation method of aliphatic amine modified carbon nanotubes, and the technical scheme adopted is as follows:

S1, 0.6moL (61.8g) of diethylenetriamine is dissolved in solvent tetrahydrofuran, and the volume ratio of diethylenetriamine and tetrahydrofuran is 1:10 to obtain diethylenetriamine solution, and the control temperature is -75 ° C, and precooling is for later use ;

S2, the methyl nitrite of 0.6moL (36.6g) is dissolved in solvent tetrahydrofuran, the volume ratio of methyl nitrite and tetrahydrofuran is 1:10, obtains methyl nitrite solution, the control temperature is-75 ℃, precooling is for later use , add a small amount of solvent tetrahydrofuran, adjust the volume of diethylenetriamine solution and methyl nitrite solution to make the two volumes equal;

S3, under nitrogen protection, select a 500mL round-bottom bottle, put 2g carbon nanotubes, 20mL tetrahydrofuran, 0.06moL (7.3g) benzoic acid, and control the temperature to -55°C;

S4, simultaneously add the solution obtained in steps S1 and S2 dropwise to the mixture of carbon nanotubes, acid and solvent obtained in step S3 at the same speed and stir to control the temperature to -55°C for about 2.5h. After the dropwise addition, the reaction 16h, after the reaction is completed, it is naturally returned to room temperature, the solvent is recovered, filtered and washed to obtain diethylenetriaminopropyl carbon nanotubes.

The yield of the diethylenetriamine-based carbon nanotubes prepared in this example was 84%, and the samples were taken for performance testing.

Example 3:

Embodiment 3 of the present invention discloses a preparation method of aliphatic amine modified carbon nanotubes, and the technical scheme adopted is as follows:

S1, the triethylenetetramine of 1.25moL (182g) is dissolved in solvent ether, the volume ratio of triethylenetetramine and ether is 1:15, obtains triethylenetetramine solution, controlled temperature is-70 ℃, and precooling is standby;

S2, 1.25moL (117.1g) of isopropyl nitrite is dissolved in solvent ether, and the volume ratio of isopropyl nitrite to ether is 1:15 to obtain isopropyl nitrite solution, and the control temperature is -70°C, Pre-cool for use, add a small amount of solvent ether, adjust the volume of triethylenetetramine solution and isopropyl nitrite solution to make the two volumes equal;

S3, under nitrogen protection, select a 500mL round-bottom flask, put 3g carbon nanotubes, 30mL ether, 0.1moL (16.6g) phthalic acid, and react at -40°C under temperature control;

S4, simultaneously add the solution obtained in steps S1 and S2 dropwise to the mixture of carbon nanotubes, acid and solvent obtained in step S3 at the same speed and stir to control the temperature to -40°C, the dropwise addition time is about 4h, after the dropwise addition, the reaction is performed for 24h , after the reaction is completed, it is naturally returned to room temperature, the solvent is recovered, filtered and washed to obtain triethylenetetraamine-based carbon nanotubes.

The yield of triethylenetetramine-based carbon nanotubes prepared in this example is 86%, and samples are taken for performance testing. The test results of adsorption performance and wave absorption performance are shown in Table 1 and Table 2.

Example 4:

Embodiment 4 of the present invention discloses a preparation method of aliphatic amine modified carbon nanotubes, and the technical scheme adopted is as follows:

S1, dissolve 1.0moL (114g) of 1,4-cyclohexanediamine in solvent tetrahydrofuran, and the volume ratio of 1,4-cyclohexanediamine to tetrahydrofuran is 1:10 to obtain 1,4-cyclohexanediamine solution , the control temperature is -10 ℃, pre-cooling for standby;

S2, the isopropyl nitrite of 1.0moL (93.7g) is dissolved in solvent tetrahydrofuran, the volume ratio of isopropyl nitrite and tetrahydrofuran is 1:10, obtains isopropyl nitrite solution, and the control temperature is-10 ℃, Pre-cool for later use, add a small amount of solvent tetrahydrofuran, adjust the volumes of the 1,4-cyclohexanediamine solution and the isopropyl nitrite solution to make the two volumes equal;

S3, under nitrogen protection, select a 500 mL round-bottom flask, put 0.12 g of carbon nanotubes, 20 mL of tetrahydrofuran, and 0.1 moL (16.6 g) of terephthalic acid, and the temperature-controlled reaction is -80°C;

S4, simultaneously add the solution obtained in steps S1 and S2 dropwise to the mixture of carbon nanotubes, acid and solvent obtained in step S3 at the same speed and stir to control the temperature to -80°C. The dropwise addition time is about 4h. After the reaction is completed, it is naturally returned to room temperature, the solvent is recovered, filtered and washed to obtain amine-modified carbon nanotubes.

The yield of the amine group-modified carbon nanotubes prepared in this example was 92%, and the samples were taken for performance testing.

Example 5:

Embodiment 5 of the present invention discloses a preparation method of aliphatic amine modified carbon nanotubes, and the technical scheme adopted is as follows:

S1, dissolve 0.01moL (1.14g) of 1,4-cyclohexanediamine in a solvent diethyl ether, and the volume ratio of 1,4-cyclohexanediamine to diethyl ether is 1:5 to obtain 1,4-cyclohexanediamine Solution, control the temperature to 20 ℃, pre-cool for use;

S2, dissolving 0.01moL (0.937g) of isopropyl nitrite in the solvent diethyl ether, the volume ratio of isopropyl nitrite to diethyl ether is 1:5, to obtain isopropyl nitrite solution, and the control temperature is 20° C. Cold standby, add a small amount of solvent ether, adjust the volume of 1,4-cyclohexanediamine solution and isopropyl nitrite solution to make the two volumes equal;

S3, under nitrogen protection, select a 500 mL round-bottomed flask, put 12 g of carbon nanotubes, 10 mL of diethyl ether, and 0.001 moL (0.166 g) of isophthalic acid, and the temperature-controlled reaction is 20 °C;

S4, simultaneously add the solution obtained in steps S1 and S2 dropwise to the mixture of carbon nanotubes, acid and solvent obtained in step S3 at the same speed and stir and control the temperature to 20°C, the dropwise addition time is about 0.1h, the dropwise addition is completed, and the reaction is performed for 5h. After the reaction is completed, it is naturally returned to room temperature, the solvent is recovered, filtered and washed to obtain amine-modified carbon nanotubes.

The yield of the amine-modified carbon nanotubes prepared in this example was 87%, and the samples were taken for performance testing.

Example 6:

The aliphatic amine-modified carbon nanotubes prepared in Example 1-5 were tested for performance, and the test results were shown in Table 1-2:

Table 1 Recovering methylene blue by adsorption method to detect sample stability

sample Use 3 5 times of use Use 7 Use 9 Example 1 96% 94% 92% 89% Example 2 96% 95% 93% 91% Example 3 97% 94% 93% 88% Example 4 98% 97% 95% 94% Example 5 81% 79% 74% 72%

The percentages are based on the first adsorption.

As the number of cycles increases, although the adsorption capacity of the samples decreases slightly, the samples of Examples 1-5 generally show good adsorption performance. Among them, the adsorption capacity of the sample of Example 5 decreases obviously with the increase of the number of cycles, and the adsorption capacity of the sample of Example 3 is the best.

The samples of Examples 1-5 were prepared with solid paraffin in a ratio of 1:2 to prepare coaxial test samples, and then tested with a vector network analyzer in the frequency range of 1 to 18 GHz. When the sample thickness was 2.8 mm, the The test results are shown in Table 2.

Table 2 Absorbing properties

sample reflectance minimum Bandwidth with reflectivity less than -10dB Example 1 -53dB 7.2GHz Example 2 -50dB 6.9GHz Example 3 -52dB 7.0GHz Example 4 -46dB 6.4GHz Example 5 -45dB 6.2GHz

When the thickness of the sample is 2.8mm, the minimum reflectivity of the sample in Example 1 reaches -53dB, and the frequency bandwidth with the reflectivity less than -10dB reaches 7.2GHz, which has good absorbing performance; the minimum reflectivity of the sample in Example 2 reaches - 50dB, the bandwidth of the reflectivity less than -10dB reaches 6.9GHz, and it has good absorption performance; the minimum reflectivity of the sample in Example 3 reaches -52dB, and the bandwidth of the reflectivity less than -10dB reaches 7.0GHz, which has good absorption performance. Wave performance; the minimum reflectivity of the sample in Example 4 reaches -46dB, and the bandwidth with reflectivity less than -10dB reaches 6.9GHz, which has good wave absorption performance; the minimum reflectivity of the sample in Example 5 reaches -45dB, and the reflectivity is less than - The bandwidth of 10dB reaches 6.2GHz, and has good absorbing performance; the samples of Examples 1-5 of the present invention basically meet the requirements of "thin, light, wide and strong" absorbing materials.

The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same and similar parts between the various embodiments can be referred to each other.

The above description of the disclosed embodiments enables any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (8)

1. a preparation method of aliphatic amine modified carbon nanotube, is characterized in that, concrete steps are as follows: S1, the aliphatic amine is dissolved in the solvent, and the obtained solution is pre-cooled for subsequent use; S2, the nitrites are dissolved in the solvent, and the obtained solution is pre-cooled for subsequent use; S3, adding carbon nanotubes to the solvent, adding a small amount of acid, and controlling the temperature to be -80 to 20°C; S4, adjust the volume of S1 and S2 with a solvent to make the two volumes equal, and drop the two mixed solutions obtained in steps S1 and S2 into the mixture of carbon nanotubes, acid and solvent obtained in step S3 at the same speed at the same time and stir, After the dropwise addition is completed, a temperature-controlled reaction is performed, and after the reaction is completed, the reaction is naturally returned to room temperature, the solvent is recovered, and the aliphatic amine modified carbon nanotubes are obtained through filtration and washing; Wherein, the solvent is one or more mixtures of acetonitrile, tetrahydrofuran and ether; The reaction is carried out under the protection of inert gas. 2. the preparation method of a kind of aliphatic amine modified carbon nanotubes according to claim 1, is characterized in that, the aliphatic amine in described step S1 is 1,4-cyclohexanediamine, diethylenetriamine, triethylenetriamine Ethylenetetramine. 3. the preparation method of a kind of aliphatic amine modified carbon nanotubes according to claim 1, is characterized in that, the nitrite in described step S2 is isopropyl nitrite or methyl nitrite. 4. The preparation method of a kind of aliphatic amine modified carbon nanotubes according to claim 1, is characterized in that, the acid in described step S3 is malonic acid, benzoic acid. 5 . The preparation method of aliphatic amine-modified carbon nanotubes according to claim 1 , wherein in the steps S1 and S2 , the precooling treatment is performed, and the temperature is controlled to be -80 to 20° C.; in the step S4 The reaction temperature is controlled to be -80 to 20°C. 6 . The method for preparing an aliphatic amine modified carbon nanotube according to claim 1 , wherein the dropping time in the step S4 is 0.1 to 4 hours. 7 . 7 . The method for preparing an aliphatic amine modified carbon nanotube according to claim 1 , wherein the reaction time in the step S4 is 5-24 h. 8 . 8 . The preparation method of aliphatic amine-modified carbon nanotubes according to claim 1 , wherein the ratio of the amount of carbon in the carbon nanotubes to the amount of the aliphatic amine is 1:0.01-100, 9 . The amounts of fatty amines and nitrites are equal.