A method for stabilizing an oxidized carbon nanotube suspension using graphene nanoparticles

Abstract

The invention relates to a method for stabilizing an oxidized carbon nanotube suspension by using graphene nanoparticles, and belongs to the field of material science. The oxidized carbon nanotubes are added to a suspension of graphene nanoparticles as a stabilizer to obtain graphene nanoparticles with a particle size of 30-70 nm, and the graphene nanoparticle suspension is dispersed in a rotary homogenizer with a power of 4 kW for 5 minutes; in the process, a lead electrode is immersed in the carbon nanotube suspension, sulfuric acid with a concentration of 55% is added, the charge-to-mass ratio of the suspension is 200C / kg, the current density is 25-30 mA / cm2, the carbon nanotubes are washed with distilled water to pH=6.5-7, and dried at 800 DEG C for 20 seconds; the oxidized carbon nanotubes are added to the graphene nanoparticle suspension and dispersed for 10 minutes, and when the concentration of the graphene nanoparticle suspension is 0.25 g / l, 7.5 g of oxidized carbon nanotubes are added. The method can be effectively used for 30 days or more in the absence of a surfactant.

Description

Technical Field

[0001] The present invention belongs to the field of material science. Carbon nanotubes and graphene nanoparticles are promising functional elements for manufacturing composite materials, which are used for shielding electromagnetic radiation, preventing radio interference, developing antistatic and anti-friction coatings, manufacturing temperature, pressure, humidity sensors, etc. The polymer composite containing carbon nanotubes has stable performance only when the components are evenly distributed in the composite material. Background Art

[0002] Carbon nanotubes in a dry state exist in the form of aggregates and must be deagglomerated when introduced into composite material components. Under industrial and laboratory conditions, ball mills, planetary vibration mills, jet mills, pulverizers, etc. are usually used to disperse carbon nanotubes, and methods for chemically modifying carbon nanotubes are also common. The brittleness of nanotubes under mechanical action makes the deagglomeration process difficult. The method of ultrasonic dispersion in a surfactant solution to treat the suspension is energy-saving and convenient. It can be dispersed to different degrees according to the power and time of dispersion to prevent the dispersed particles from agglomerating, but the surfactant as a medium is usually a polymer with low conductivity. The dispersed carbon nanotube and graphene nanoparticle suspension remains stable for a long time in the surfactant solution and will not separate into separate fractions, but impurities have a negative impact on the further introduction of carbon nanotubes into composite materials.

[0003] The prototype selected patent RU №2746861, published on April 21, 2021, publication number №12, which describes a method for obtaining a metal dispersion coating. The method involves chemical or electrochemical deposition from a low molecular weight electrolyte solution using a broad-spectrum surfactant, dispersing a two or more component system in an aqueous medium. The common feature of the prototype and the utility model is the use of a suspension and paste method (components are carbon nanotubes, graphene, distilled water), and potassium hydroxide is used as the electrolyte solution. The disadvantages of the prototype are the large amount of strong inorganic acids and surfactants used in the technology, as well as the complexity of the technology itself. Summary of the invention

[0004] The object of the present invention is to develop a method for stabilizing oxidized carbon nanotube suspensions which are free of low-conductivity impurities.

[0005] This problem is solved by using a certain mass of oxidized carbon nanotubes and graphene nanoparticles in the composition of the resulting suspension to stabilize the suspension instead of a surfactant solution in order to prevent the suspension from demixing into separate phases.

[0006] Graphene nanoparticles are obtained by electrochemical methods. The graphite strip (anode) is placed in a potassium hydroxide electrolyte solution (pH 9) tank. The electric field strength of the electrolytic tank is 2V / cm. The membrane is divided into anode and cathode spaces. The anode space is separated by a porous filter partition to allow the graphene nanoparticle suspension to pass through and intercept the coarsely dispersed graphite suspension. The flow rate of the potassium hydroxide electrolyte solution is controlled by controlling the optical density of the resulting graphene suspension. The foil made of thermally expanded graphite powder has a bulk density of 1.5-2.0g / dm 3 Pour potassium hydroxide aqueous solution into the container, and after filling the reactor to a predetermined level, use the power supply unit to provide a voltage of 2 V / cm and a density of 3 mA / cm 2 of direct current.

[0007] The graphene nanoparticle size of the resulting graphene nanoparticle suspension is most likely 30-70 nm, as measured by laser correlation spectroscopy. Graphene nanoparticles can also be obtained in another way, provided that the specified size can be achieved.

[0008] Carbon nanotubes are electrochemically oxidized (anodized). A lead electrode is immersed in the nanotube suspension, 55% sulfuric acid is added, and a current density of 25-30 mA / cm is passed. 2 , the charge-to-mass ratio of the suspension is 200C / kg, the sample is washed with distilled water to pH = 6.5-7, and dried at 800°C for 20 seconds. [See: Simonsov Yu.I. Structure and properties of sp2-carbon nanomaterials and their functional composite materials (Foermünlüvannaya структуритавластивостейsp2-вуглецевихнаноматерiалiвiфункцiональнихкомпозитiвза хучастi) / Edited by Academician MT Kartel of the National Academy of Sciences of Ukraine, Kiev: Institute of Surface Chemistry of the National Academy of Sciences of Ukraine, Interservice Publishing Company, 2019, 364 pages).

[0009] The method for preparing a stable suspension of the present invention is as follows:

[0010] The graphene nanoparticle suspension was dispersed in a 4kW rotary homogenizer for 1 minute. Oxidized carbon nanotubes were then added to the graphene nanoparticle suspension and dispersed for 10 minutes. When the volume of the suspension was increased to 10 L, the dispersion time of the suspension with the added oxidized carbon nanotubes should increase with the increase in volume. For every 1 L increase in volume, the dispersion time increased by 1 minute, and the power remained constant.

[0011] In the method, when the concentration of the graphene nanoparticle suspension is 0.25 g / l, 7.5 g of oxidized carbon nanotubes are added, and when the concentration of the graphene nanoparticle suspension is 0.5 g / l, 5 or 10 g of oxidized carbon nanotubes are added.

[0012] The stability of the suspension was visually checked every 60 minutes for 5 hours after dispersion and twice daily thereafter. A suspension that was stable for more than three days was considered successful.

[0013] To implement suspension stabilization technology, you need:

[0014] – foil made of thermally expanded graphite TUU26.8-34743542-002:2011;

[0015] – Analytical grade or pure grade potassium hydroxide GOST 24363-80;

[0016] – Membrane made of polypropylene fabric with a thickness of 0.5 mm GOSTRISO9001:2015;

[0017] – Carbon nanotubes TUU24.1-03291669-009:2000

[0018] – Sulfuric acid GOST2184-2013

[0019] – Distilled water GOST 6709-72 DETAILED DESCRIPTION

[0020] Example 1: A graphene nanoparticle suspension having a content of 0.05 g of graphene nanoparticles and a volume of 1 L is dispersed in a rotary homogenizer for 5 minutes. A mass of 5 g of oxidized carbon nanotubes is added to the suspension and dispersed for 10 minutes. The invention task is not solved.

[0021] Example 2: Similar to Example 1, the content of graphene oxide nanoparticles is changed to 0.1 grams, and the mass of oxidized carbon nanotubes remains at 5 grams, but the invention task is not solved.

[0022] Example 3: Similar to Example 1, the content of graphene oxide nanoparticles was changed to 0.25 grams, and the mass of carbon oxide nanotubes was changed to 7.5 grams, and the invention task was solved.

[0023] Example 4: Similar to Example 1, the content of graphene oxide nanoparticles was changed to 0.5 grams, and the mass of carbon oxide nanotubes was changed to 5 grams, and the invention task was solved.

[0024] Example 5: Similar to Example 1, the content of graphene oxide nanoparticles was changed to 0.5 grams, and the mass of carbon oxide nanotubes was changed to 10 grams, and the invention task was solved.

[0025] Example 6 (Prototype): The stability of the suspension was not described.

[0026] The content and stability of the obtained suspension are shown in Table 1.

[0027] Table 1

[0028]

[0029] It can be seen from the data in the table that in the absence of a surfactant, the effective time of the method of using graphene nanoparticles to stabilize the oxidized carbon nanotube suspension of the present invention is 710 hours.

[0030] Therefore, the above examples demonstrate that the present invention achieves technical results.

Claims

1. A method for stabilizing an oxidized carbon nanotube suspension using graphene nanoparticles, wherein the suspension contains a liquid medium, solid particles and a stabilizer, the liquid medium contains distilled water, the solid particles contain carbon nanotubes, and the graphene is used to obtain the stabilizer from a potassium hydroxide electrolyte solution by an electrochemical deposition method, characterized in that: Oxidized carbon nanotubes were added to a suspension of graphene nanoparticles as a stabilizer, including: Graphene nanoparticles with a particle size of 30-70nm are obtained, and the graphene nanoparticle suspension is dispersed in a rotary homogenizer with a power of 4kW for 5 minutes; carbon nanotubes are oxidized, during which a lead electrode is immersed in the carbon nanotube suspension, sulfuric acid with a concentration of 55% is added, the charge-to-mass ratio of the suspension is 200C / kg, the current density is 25-30mA / cm2, the carbon nanotubes are washed with distilled water to pH=6.5-7, and dried at 800°C for 20 seconds; the oxidized carbon nanotubes are added to the graphene nanoparticle suspension and dispersed for 10 minutes, when the concentration of the graphene nanoparticle suspension is 0.25g / l, 7.5g of oxidized carbon nanotubes are added, and when the concentration of the graphene nanoparticle suspension is 0.5g / l, 5 or 10g of oxidized carbon nanotubes are added.

2. A method for stabilizing an oxidized carbon nanotube suspension using graphene nanoparticles as claimed in claim 1, characterized in that: For every 1L increase in the volume of the graphene nanoparticle suspension, the dispersion time of the added oxidized carbon nanotubes increased by 1 minute, while the power remained unchanged.

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