阅读说明：本技术 一种碳纳米管水分散液的制备方法 (Preparation method of carbon nano tube water dispersion ) 是由 刘家园 沈小宁 袁立焕 庚丽丽 王永利 贾延华 于 2019-11-15 设计创作，主要内容包括：本发明提供了一种碳纳米管水分散液的制备方法,以原始碳纳米管为原料,通过化学修饰活化,超声机械力外力强化分散一系列步骤,在分散剂下实现物理/化学负载起到稳定辅助分散作用,将碳纳米管分散到去离子水中,最终制备具有一定碳纳米管浓度含量的稳定的水分散液；本发明制备方法简单,过程容易控制,重复性强；所制备的碳纳米管分散稳定；碳纳米管结构保护完整,不影响碳纳米管原用功能；所制备的碳纳米管分散液的碳纳米管含量高。(The invention provides a preparation method of a carbon nano tube aqueous dispersion, which takes original carbon nano tubes as raw materials, and realizes the stable auxiliary dispersion effect of physical/chemical load under a dispersant through a series of steps of chemical modification activation and ultrasonic mechanical force external force strengthening dispersion, and the carbon nano tubes are dispersed into deionized water to finally prepare the stable aqueous dispersion with a certain concentration content of the carbon nano tubes; the preparation method is simple, the process is easy to control, and the repeatability is strong; the prepared carbon nano tube is stable in dispersion; the carbon nano tube has complete protection, and the original functions of the carbon nano tube are not influenced; the prepared carbon nanotube dispersion liquid has high carbon nanotube content.)

1. A preparation method of a carbon nano tube water dispersion liquid is characterized by comprising the following steps:

(1) mixing the carbon nano tube, the acid agent and the oxidant, performing ultrasonic treatment, centrifuging, and washing to obtain a mixture with a pH value: 6.5-7, drying and grinding to obtain an activated carbon nanotube;

the mass ratio of the carbon nano tube to the acid agent to the oxidant is 0.1-10: 100: 20-100 parts of;

(2) mixing the activated carbon nanotube prepared in the step (1), deionized water and a dispersing agent, adjusting the pH to 7 by using a pH regulator, sealing, and performing ultrasonic dispersion, ball milling and ultrasonic dispersion again in sequence to obtain the carbon nanotube water dispersion;

the mass ratio of the activated carbon nanotube to the deionized water to the dispersant is 0.01-10: 100: 0.005 to 1.

2. The method for preparing an aqueous dispersion of carbon nanotubes according to claim 1, wherein in the step (1), the carbon nanotubes are multi-walled carbon nanotubes or single-walled carbon nanotubes, and have an inner diameter of 5 to 10nm, an outer diameter of 10 to 50nm and a length of 10 to 30 μm.

3. The method for preparing an aqueous dispersion of carbon nanotubes according to claim 1, wherein in step (1), the acid agent is one or more of concentrated sulfuric acid, concentrated nitric acid, concentrated hydrochloric acid, and permanganic acid.

4. The method for preparing an aqueous dispersion of carbon nanotubes according to claim 1, wherein in step (1), the oxidizing agent is one or more of concentrated sulfuric acid, concentrated nitric acid, potassium permanganate, aqueous hydrogen peroxide, and ammonium peroxodisulfate.

5. The method for preparing an aqueous dispersion of carbon nanotubes according to claim 1, wherein in the step (2), the dispersing agent is: one or more of hydroxypropyl methylcellulose, polyvinyl alcohol, gelatin, polyacrylamide, polyacrylic acid, polyvinylpyrrolidone, ethyl cellulose, hydroxyethyl cellulose, methylcellulose, sodium dodecyl benzene sulfonate, sodium dodecyl sulfate and sodium dodecyl sulfonate.

6. The method for preparing an aqueous dispersion of carbon nanotubes according to claim 1, wherein in step (2), the pH regulator is an aqueous solution of an alkaline substance with a mass concentration of 2%, and the alkaline substance is one or more of ammonium bicarbonate, sodium hydroxide and sodium carbonate.

7. The method for preparing the carbon nanotube aqueous dispersion according to claim 1, wherein in the step (2), the rotation speed of the ball mill is 200-3000 rpm, the time is 0.5-15 h, and the temperature is 35-40 ℃.

Technical Field

The invention relates to the technical field of carbon nanotube modification, in particular to a preparation method of a carbon nanotube aqueous dispersion.

Background

The carbon nano tube has unique surface effect, small size effect and quantum size effect, and the unique hollow tubular structure endows the carbon nano tube with excellent mechanical, magnetic, thermal and other properties, so that the carbon nano tube is widely applied to the advanced fields of aerospace and the like. However, the carbon nanotubes themselves have special structures which are easily intertwined with each other, so that the carbon nanotubes are unevenly dispersed in a solvent and a polymer matrix, and the application field of the carbon nanotubes is severely limited. With the continuous perfection of the preparation technology of the carbon nano tube, people can produce a large amount of carbon nano tubes with low cost, but have some problems, such as chemical inertness on the surface of the carbon nano tube, lack of active groups and low solubility in various solvents; in addition, van der waals forces, large aspect ratios, and high specific surface areas make carbon nanotubes highly susceptible to agglomeration and entanglement. These severely restrict the application of carbon nanotubes in many fields, and the surface performance needs to be improved by surface functional modification to solve the problem of dispersibility.

The surface functionalization modification of carbon nanotubes is generally classified into covalent functionalization and non-covalent functionalization. The covalent functionalization method achieves the purpose of improving the dispersibility of the carbon nano tube by forming functional groups on the surface of the carbon nano tube, but the process has certain damage to the structure of the carbon nano tube, thereby influencing the electrical property and the mechanical property of the carbon nano tube. The non-covalent functionalization method is mainly to modify the carbon nano-tube by using a surfactant, a macromolecule or a biological macromolecule, the structural integrity of the carbon nano-tube can be kept to the maximum extent after the treatment, but the amount of the modifier on the carbon nano-tube needs to be controlled after the treatment. The use amount of the modifier is too large, which not only increases the cost, but also influences the interface combination of the carbon nano tube and the matrix material.

The physical method is simple and easy to operate, and mainly adopts an adsorption or loading mode to carry out functional modification on the surface of the single-walled carbon nanotube or the multi-walled carbon nanotube; the chemical method is to introduce some chemical reagents capable of performing functional modification on the surface of the carbon nanotube and react with the carbon nanotube to achieve the purpose of the functional modification on the surface of the carbon nanotube. At present, a method of performing functional modification on carbon nanotubes by using a strong oxidant or a strong acid is widely used, which can introduce some special functional groups, such as-COOH, into the surface of the carbon nanotubes while purifying the carbon nanotubes; -OH; -C ═ O and the like. The carbon nano tube is treated by strong acid more thoroughly, and the functionalization effect is better.

The dispersing agent can effectively disperse the activated carbon nano tubes into deionized water by modifying the carbon nano tubes through physical/chemical load and strengthening the dispersing action by combining ultrasound with mechanical force and external force, so as to prepare the stable carbon nano tube water dispersion liquid with a certain concentration content of the carbon nano tubes, and simultaneously, the original structure and performance of the carbon nano tubes can be effectively maintained.

Disclosure of Invention

The invention aims to provide a preparation method of a carbon nano tube water dispersion liquid, the carbon nano tube in the dispersion liquid prepared by the method is stably dispersed, the preparation process is simple, the cost is low, and the original structure and performance of the carbon nano tube can be effectively maintained.

The method takes original carbon nano tubes as raw materials, and realizes a stable auxiliary dispersion effect by physical/chemical load under a dispersant through a series of steps of chemical modification activation and ultrasonic mechanical force external force reinforcement dispersion, and the carbon nano tubes are dispersed into deionized water to finally prepare the stable aqueous dispersion with a certain concentration content of the carbon nano tubes.

The technical scheme of the invention is as follows:

a method for preparing a carbon nanotube aqueous dispersion, the method comprising the steps of:

(1) mixing the carbon nano tube, an acid agent and an oxidant, performing ultrasonic treatment (0.5-15 h), centrifuging, and washing to a pH value: 6.5-7, drying (110 ℃) and grinding to obtain an activated carbon nanotube;

the mass ratio of the carbon nano tube to the acid agent to the oxidant is 0.1-10: 100: 20-100 parts of;

the carbon nano tube is a multi-wall carbon nano tube or a single-wall carbon nano tube, the inner diameter of the carbon nano tube is 5-10 nm, the outer diameter of the carbon nano tube is 10-50 nm, and the length of the carbon nano tube is 10-30 mu m;

the acid agent is one or more of concentrated sulfuric acid (98 wt%), concentrated nitric acid (65 wt%), concentrated hydrochloric acid (37 wt%) and permanganic acid (98 wt%);

the oxidant is one or more of concentrated sulfuric acid (98 wt%), concentrated nitric acid (65 wt%), potassium permanganate, aqueous hydrogen peroxide (30 wt%) and ammonium peroxydisulfate;

the power of the ultrasonic is 500-2000 w, and the temperature is 30-40 ℃;

the washing uses 95% ethanol water solution;

(2) mixing the activated carbon nanotube prepared in the step (1), deionized water and a dispersing agent, adjusting the pH to 7 by using a pH regulator, sealing, performing ultrasonic dispersion (0.5-15 h), performing ball milling (0.5-15 h), and performing ultrasonic dispersion again (0.5-15 h) in sequence to obtain the carbon nanotube aqueous dispersion;

the mass ratio of the activated carbon nanotube to the deionized water to the dispersant is 0.01-10: 100: 0.005 to 1;

the dispersing agent is: one or more of hydroxypropyl methylcellulose, polyvinyl alcohol, gelatin, polyacrylamide, polyacrylic acid, polyvinylpyrrolidone, ethyl cellulose, hydroxyethyl cellulose, methylcellulose, sodium dodecyl benzene sulfonate, sodium dodecyl sulfate and sodium dodecyl sulfonate;

the pH regulator is an aqueous solution of an alkaline substance with the mass concentration of 2%, and the alkaline substance is one or more of ammonium bicarbonate, sodium hydroxide and sodium carbonate;

the conductivity of the deionized water is less than 0.055 mu S/cm (25 ℃);

the ball milling speed is 200-3000 rpm, the time is 0.5-15 h, and the temperature is 35-40 ℃;

the power of the first ultrasonic is 500-2000 w, and the temperature is 30-40 ℃;

the power of the second ultrasonic wave is 500-2000 w, and the temperature is 35-40 ℃.

The carbon nano tube aqueous dispersion prepared by the invention is stable. Wherein the carboxyl content of the activated carbon nanotube is not less than 2.5 wt%, and the hydroxyl content is not less than 1.5 wt%.

The invention adopts carbon nano-tubes as main raw materials, and the carbon nano-tubes are activated by mixed acid, added with a dispersant, deionized water and a pH value regulator, and alternately strengthened and dispersed by ultrasonic waves and mechanical force external force to finally obtain the uniform and stable carbon nano-tube water dispersion with certain concentration.

The invention utilizes the physical and chemical load dispersion effect of the dispersant, and simultaneously utilizes the ultrasonic and mechanical force external force to alternately strengthen the dispersion effect to disperse the activated carbon nano tube in the deionized water, thereby finally obtaining the carbon nano tube water dispersion with excellent and stable performance and higher concentration content.

The carbon nano tube aqueous dispersion prepared by the method overcomes the defect that the compatibility of the carbon nano tube with a solvent or a polymer is improved by a chemical modification method, avoids the use of the solvent, overcomes the defects of complex reaction and poor repeatability, can realize large-scale preparation, expands the application range of the carbon nano tube, and can be used in the fields of biotechnology, medicine, aerospace materials, electronic products and the like.

The invention has the following advantages:

1. the preparation method is simple, the process is easy to control, and the repeatability is strong;

2. the prepared carbon nano tube is stable in dispersion;

3. the carbon nano tube has complete protection, and the original functions of the carbon nano tube are not influenced;

4. the prepared carbon nanotube dispersion liquid has high carbon nanotube content.

The carbon nano tube dispersion liquid prepared by the invention has high production efficiency, low cost, high concentration and good stability, and can be used in the fields of biotechnology, medicine, aerospace materials, electronic products and the like.

Detailed Description

The present invention is further illustrated by the following specific examples, but the scope of the invention is not limited thereto.

The ball mill pot used in the following examples was an XQM-4 model vertical planetary ball mill manufactured by Changsha Tianchu powder technology Limited, and the ball mill pot was made of zirconia.