WO2018107795A1

WO2018107795A1 - Method for exfoliating hexagonal boron nitride (h-bn) by means of ball milling

Info

Publication number: WO2018107795A1
Application number: PCT/CN2017/098056
Authority: WO
Inventors: 段曦东; 王剑; 蒋后清
Original assignee: 广东纳路纳米科技有限公司
Priority date: 2016-12-12
Filing date: 2017-08-18
Publication date: 2018-06-21
Also published as: CN107381643A; CN107352516A; CN106744875A

Abstract

The method relates to the field of nanomaterials. Specifically disclosed is a method or exfoliating hexagonal boron nitride (h-BN) by means of ball milling. The method specifically comprises: mixing raw materials, i.e., h-BN powder, a surfactant, and a ball milling medium, for dissolving, the mass ratio of the h-BN powder to the surfactant being 1:1 to 500:1, and the mass ratio of h-BN to the ball milling medium being 2:1 to 1:10, and performing closed ball milling at a ball milling speed of 200-800 rpm; continuing to add the above ball milling medium after ball milling for every period of time, the amount of the ball milling medium added being 5%-40% of the mass percentage of h-BN, and the total ball milling time being 120-480 h; after the ball milling is completed, washing the resulting powder using an alcohol, and then drying to obtain an h-BN dispersion. The method can effectively exfoliate h-BN particles; the produced h-BN has the characteristics of uniform particles, fewer layers, large area, and high purity, and can be well dispersed in an alcohol and other solvents and stored for tens of days without agglomeration and sedimentation.

Description

Method for stripping white graphene by ball milling

Technical field

The invention relates to the field of nano materials, in particular to a method for ball-peeling off white graphene.

Background technique

White graphene (h-BN) is essentially a single layer or a small layer of h-BN.

The discovery of graphene has triggered the scientific research boom of two-dimensional materials. As a new type of two-dimensional material, white graphene sheet has been widely studied due to its excellent performance. In two-dimensional h-BN, B atoms and N atoms are sp2 hybridized, and B and N are covalently bonded at 1:1 to obtain a two-dimensional plane of a graphene-like hexagonal honeycomb structure, but in layers and layers in the third dimension. The combination of van der Waals forces constitutes a van der Waals layered material.

Based on the unique two-dimensional structure of h-BN, the two-dimensional h-BN material has many excellent properties. The two-dimensional h-BN has low density and high specific strength, and can be applied to modified multifunctional composite materials; it has a low friction coefficient and is a commonly used lubricant; it has high temperature resistance and is chemically stable in air above 1000 ° C. Used in anti-oxidation coatings and other fields; large thermal conductivity, can be used as filler for thermal conductive composites; layered h-BN forbidden band width is 5.0-6.0 ev, with excellent insulation properties, single-layer H-BN tunnel The barrier height is 3.07eV, the breakdown voltage is 7.95MV/cm, which is similar to that of SO ₂ , and the surface of h-BN layer is smooth, the dangling bonds are relatively few, and the carrier trap is less. h-BN is a graphene transistor. The ideal carrier platform; at the same time, due to its large forbidden band width, it can also be used as an ultraviolet laser detector. And h-BN is a good gas sensitive material with extremely high sensitivity to CO ₂ , CH ₄ , O ₂ , H ₂ , NO ₂ and the like.

Although h-BN two-dimensional materials have many of the above-mentioned good properties, h-BN with excellent preparation performance on a large scale is still to be studied. The yield of white graphene (h-BN) prepared by traditional micro-mechanical stripping is too low, which is only suitable for laboratory production; chemical liquid phase stripping is commonly used to toxic and harmful organic solvents, and its physical structure and electrons such as oxidation and ion intercalation The structure has a certain influence, and the prepared h-BN has poor electrical properties. Chemical vapor deposition is commonly used to prepare high-performance single-layer or low-layer h-BN, but its cost and yield are affected. To the limit. At present, white graphene cannot mass-produce white graphene with high purity and excellent performance in a low-cost manner, which greatly limits its application, and improving the productivity of white graphene is one of the focuses of white graphene research. In addition, similar to many other nanomaterials, white graphene has a large specific surface area. Under the action of van der Waals force, white graphene sheets will produce irreversible agglomeration, so its dispersion performance seriously affects its performance and application, and improves h-BN. Dispersibility is also the focus of current research.

Summary of the invention

In view of the above, it is necessary to provide a method for ball-peeling off white graphene by the above method. The method can effectively strip white graphene particles, and the white graphene obtained by stripping has uniform particles, few layers, large area, and purity. High characteristics, can be well dispersed in alcohol and other solvents for dozens of days without agglomeration and sedimentation. Moreover, the method has simple operation process, low cost and high production efficiency, and is suitable for large-scale industrial production.

In order to achieve the above object, the present invention adopts the following technical solutions:

The method for ball-peeling off white graphene of the present invention, the specific steps are:

Step 1) mixing and dissolving white graphene (h-BN) powder, surfactant, and ball milling medium, and performing ball sealing at a ball milling speed of 200-800 rpm;

The mass ratio of the white graphene (h-BN) powder to the surfactant is 1:1-500:1, preferably 10:1-100:1; the white graphene (h-BN) and the ball milling medium are added. The mass ratio is 2:1-1:10, preferably 1:1 to 1:5;

Step 2) After each ball milling for a period of time, continue to add the ball milling medium in step 1, the ball milling medium is added in an amount of 5% to 40% by mass of the white graphene, and the total ball milling time is 120-480 h;

Step 3) After the completion of the grinding, the obtained powder is washed with alcohol and then dried to obtain a ball-milled white graphene dispersion.

In the ball milling process, the grinding ball is ceramic or metal grinding ball, the ball to material ratio is 3:1, the surface energy of the ball milling medium is close to the surface energy of white graphene (25-40 mJ/m ² ), and the mechanical peeling has the most Good efficiency and quality. At the same time, adding an appropriate amount of ball milling media can buffer the impact of the zirconium ball during ball milling and adjust the viscosity range of the ball mill system.

Due to the large viscosity change of the ball mill system during the h-BN stripping process, the ball mill media must be added after grinding for a period of time. To control the viscosity of the ball mill system within a reasonable range.

The surfactant can effectively adsorb on the surface of the two-dimensional h-BN to form steric hindrance and charge steric hindrance, and the prepared white graphene can be dispersed in an aqueous solution of alcohol, acetone and the like for a long time without agglomeration and sedimentation.

Further, in the step 2 ball milling process, the ball milling medium is added every 2 hours for the first 24 hours; the ball milling medium is added every 24 hours after the ball milling time exceeds 24 hours.

Further, the ball milling medium is a low molecular weight alcohol and/or aqueous ketone solution.

Preferably, in the low molecular weight alcohol and/or ketone aqueous solution, the mass ratio of the low molecular weight alcohol and/or ketone to water is from 1:10 to 2:1, more preferably from 1:5 to 2:1.

Preferably, the low molecular weight alcohol is at least one of methanol, ethanol, isopropanol, tert-butanol, and ethylene glycol; and the low molecular weight ketone is acetone.

Further, the surfactant is at least one of a surfactant having a long-chain Lewis acid or a long-chain Lewis base.

Preferably, the surfactant is at least one of a higher fatty acid, a fatty ketone, an alicyclic ketone, an aromatic ketone, and the like and a corresponding derivative thereof having a C atom number greater than 14 with a long-chain Lewis acid; or a long chain At least one of an olefin, an aromatic compound, an amine, an ether, and the like of the Lewis base.

Further preferably, the surfactant of the long-chain Lewis acid is: palmitic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, palmitic acid, octadecanone, 3-methylcyclotriene At least one of a ketone, cyclotetradecanone, 3-hexadecanone, palm aldehyde, cocoaldehyde, eicosanal, and the like;

The surfactant of the long-chain Lewis base is: palmamine, heptadecylamine, octadecylamine, oleylamine, cholestyramine, terminal aminopolyethylene glycol, polyphenylacetylene, polythiophene, polystyrene sulfonate At least one of sodium, dodecylbenzene, 4-dodecylaniline, polyoxyethylene octyl phenol ether, glycidyl 12-14 alkyl ether, hexaethylene glycol monohexadecyl ether, and the like .

The B and N atoms in h-BN have weak positive and negative points, respectively, and there is a π bond. The surfactant with long-chain Lewis acid and long-chain Lewis base of the present invention can fully adsorb on h-BN to form a space position. Resistance and charge steric hindrance promotes grinding and prevents agglomeration of isolated h-BN nanosheets.

The beneficial effects of the invention are:

The white graphene sheet stripped by the invention has large particle size, thin thickness and large specific surface area: the thickness is less than 10 nm, the thickness of the thin skin can be as low as 1 nm, the particle size is distributed in the range of hundreds of nanometers to several micrometers, and the specific surface area is as high as 100-1500 m ² /g.

The preparation process has no strong acid/alkali raw materials, toxic organic additives, etc., is environmentally friendly, has high production efficiency, large output, simple equipment, low cost and good application prospect.

DRAWINGS

1 is a SEM photograph of white graphene prepared in Example 1;

2 is an AFM photograph of white graphene prepared in Example 1.

detailed description

In order to make the objects, the technical solutions and the advantages of the present invention more clearly, the technical solutions of the present invention will be further clearly and completely described below in conjunction with the embodiments of the present invention. It should be noted that the described embodiments are only a part of the embodiments of the invention, and not all of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts are within the scope of the present invention.

Example 1

The specific preparation process steps of the present embodiment: weigh 100 g of white graphene (h-BN), 100 g of ethanol and 100 g of deionized water, measure 4 g of polythiophene, put into a ball mill jar, and stir to completely dissolve.

The ball mill jar was sealed and fixed on a planetary ball mill, and the ball mill was started and milled at 500 rpm for 240 h. 24h before ball milling, 25g ethanol solution was added every 2h (ethanol: water mass ratio was 1:1); ball milling time was 24-72h, and 25g ethanol solution was added every 24h. After the ball milling time exceeds 72 h, 10 g of an aqueous ethanol solution is added every 24 hours to ensure that the ball mill system has a suitable viscosity.

After the ball milling, the white graphene is washed with alcohol, and then dried at 60 ° C in a muffle furnace to obtain a ball-milled white graphene product.

1 is a SEM photograph of the product obtained in the present example, from which it can be seen that the obtained white graphene nanosheet has a particle diameter of more than 250 nm and a nanosheet thickness of less than 10 nm by ball mill peeling; FIG. 2 is an atomic force microscope photo, h The thickness of the -BN sheet is 6 nm, and the thickness of part of the h-BN can be as low as about 1 nm. The specific surface area was determined to be 180 m ² /g.

Example 2

The specific preparation process steps of this embodiment: weigh 100 g of white graphene (h-BN), 100 g of ethanol and 100 g of deionized water in a ball mill jar, and stir uniformly with a glass rod. 10 g of oleylamine was weighed and placed in a ball mill jar and stirred to completely dissolve.

The ball mill jar was sealed, fixed on a ball mill, and the ball mill was started and milled at 450 rpm for 240 h. During the first 24 h of the ball milling process, 25 g of an aqueous ethanol solution was added every 2 hours. The ball milling time was 24-72 h, and 25 g of an aqueous ethanol solution was added every 24 hours. After the ball milling time exceeds 72 h, 10 g of an aqueous ethanol solution is added every 24 hours to ensure that the ball milling system has a suitable viscosity.

The white graphene nanosheets obtained in this example have a particle diameter of more than 250 nm and a nanosheet thickness of less than 10 nm; most of the h-BN sheets have a thickness of 4 nm, and a part of the h-BN has a thickness as low as about 1 nm. The specific surface area was detected to be 320 m ² /g.

Example 3

The specific preparation process steps of this embodiment: weigh 100 g of white graphene (h-BN), 100 g of acetone and 100 g of deionized water in a ball mill jar, and stir uniformly with a glass rod. 2 g of palmitic acid was weighed and placed in a ball mill jar, and stirred to dissolve completely.

The ball mill jar was sealed, fixed on a planetary ball mill, and the ball mill was started and milled at 450 rpm for 240 h. During the first 24 h of the ball milling process, 25 g of aqueous acetone solution was added every 2 hours. The ball milling time was 24-72 h, and 25 g of aqueous acetone solution was added every 24 hours. After the ball milling time exceeds 72 h, 10 g of aqueous acetone solution is added every 24 hours to ensure that the ball milling system has a suitable viscosity.

After the ball milling, the white graphene is washed with alcohol and dried in a muffle furnace at 60 ° C to obtain a ball mill. White graphene product.

The white graphene nanosheets obtained in this example have a particle diameter of more than 250 nm and a nanosheet thickness of less than 10 nm; most of the h-BN sheets have a thickness of 4 nm, and a part of the h-BN has a thickness as low as about 1 nm. The specific surface area was determined to be 280 m ² /g.

Example 4

The specific preparation process steps of the present embodiment: weigh 100 g of white graphene (h-BN), 50 g of acetone and 150 g of deionized water, measure 4 g of octadecylamine, put into a ball mill jar, and stir to completely dissolve.

The ball mill jar was sealed and fixed on a planetary ball mill, and the ball mill was started and milled at 500 rpm for 240 h. 25 g of aqueous acetone solution was added every 2 h for the first 24 h during the ball milling process. The ball milling time was 24-72 h, and 25 g of aqueous acetone solution was added every 24 hours. After the ball milling time exceeds 72 h, 10 g of aqueous acetone solution is added every 24 times to ensure that the ball milling system has a suitable viscosity.

The white graphene nanosheets obtained in this example have a particle diameter of more than 250 nm, and the nanosheet thicknesses are all less than 10 nm. The thickness of most of the h-BN sheets is 3 nm, and the thickness of some of the h-BN sheets can be as low as about 1 nm. The specific surface area was determined to be 380 m ² /g.

Example 5

The specific preparation process steps in this embodiment: weigh 100g white graphene (h-BN), 100g acetone and 100g deionized water, measure 4g 3-methylcyclotridecyl ketone, put it into the ball mill jar, stir it to complete Dissolved.

The ball mill jar was sealed and fixed on a planetary ball mill, and the ball mill was started and milled at 500 rpm for 240 h. 25 g of aqueous acetone solution was added every 2 h for the first 24 h during the ball milling process. The ball milling time was 24-72 h, and 25 g of aqueous acetone solution was added every 24 hours. After the ball milling time exceeds 72 h, 10 g of aqueous acetone solution is added every 24 hours to ensure that the ball milling system has a suitable viscosity.

The white graphene nanosheets obtained in this example have a particle size greater than 250 nm and the nanosheet thicknesses are all less than 10 nm; most of the h-BN sheets have a thickness of 4 nm, and a portion of the h-BN has a thickness as low as about 1 nm. The specific surface area was determined to be 250 m ² /g.

Example 6

The specific preparation process steps in this embodiment: weighing 100 g of white graphene (h-BN), 25 g of t-butanol, 25 g of acetone and 50 g of deionized water, and measuring 1 g of 3-methylcyclotridecyl ketone into a ball mill jar Stir and dissolve completely.

The ball mill jar was sealed and fixed on a planetary ball mill, and the ball mill was started and ball milled at 700 rpm for 150 h. 40 g of t-butanol/acetone aqueous solution was added every 2 h for the first 24 h during the ball milling process. The ball milling time was 24-72 h, and 25 g of t-butanol/acetone aqueous solution was added every 24 hours. After the ball milling time exceeds 72 h, 20 g of t-butanol/acetone aqueous solution is added every 24 h to ensure that the ball milling system has a suitable viscosity.

The white graphene nanosheets obtained in this example have a particle diameter of more than 250 nm and a nanosheet thickness of less than 10 nm; most of the h-BN sheets have a thickness of 4 nm, and a part of the h-BN has a thickness as low as about 1 nm. The specific surface area was determined to be 380 m ² /g.

Example 7

In this embodiment, the specific preparation process steps: weigh 100 g of white graphene (h-BN), 250 g of methanol, 250 g of acetone and 150 g of deionized water, measure 3 g of palm aldehyde, put it into a ball mill jar, and stir to completely dissolve it.

The ball mill jar was sealed and fixed on a planetary ball mill, and the ball mill was started and ball milled at 300 rpm for 400 h. 10 g of methanol/acetone aqueous solution was added every 2 h for the first 24 h during the ball milling process. The ball milling time was 24-72 h, and 8 g of methanol/acetone aqueous solution was added every 24 hours. After the ball milling time exceeds 72 h, 8 g of methanol/acetic acid aqueous solution is added every 24 hours to ensure that the ball milling system has a suitable viscosity.

The white graphene nanosheets obtained in this example have a particle diameter of more than 250 nm, and the nanosheet thicknesses are all less than 10 nm; most of the h-BN sheets have a thickness of 5 nm, and a part of the h-BN thickness can be as low as about 1 nm. The specific surface area was detected to be 550 m ² /g.

Example 8

The specific preparation process steps of the present embodiment: weigh 100g of white graphene (h-BN), 200g of methanol, 200 isopropyl alcohol and 300g of deionized water, weigh 0.3g of polyoxyethylene octyl phenol ether, and put it into the ball mill tank. Stir and dissolve completely.

The ball mill jar was sealed and fixed on a planetary ball mill, and the ball mill was started and ball milled at 600 rpm for 300 h. 10 g of methanol/isopropanol aqueous solution was added every 2 h for the first 24 h during the ball milling process. The ball milling time was 24-72 h, and 20 g of a methanol/isopropanol aqueous solution was added every 24 hours. After the ball milling time exceeds 72 h, 8 g of methanol/isopropanol aqueous solution is added every 24 hours to ensure that the ball milling system has a suitable viscosity.

The white graphene nanosheets obtained in this example have a particle diameter of more than 250 nm and a nanosheet thickness of less than 10 nm; most of the h-BN sheets have a thickness of 2 nm, and a part of the h-BN has a thickness as low as about 1 nm. The specific surface area was found to be 120 m ² /g.

Comparative example 1

The specific preparation process steps of this comparative example: weighing 100 g of white graphene (h-BN), 50 g of acetone and 150 g of deionized water, and measuring 4 g of octadecylamine, placed in a ball mill jar, and stirred to completely dissolve.

The ball mill jar was sealed and fixed on a planetary ball mill, and the ball mill was started and milled at 500 rpm for 240 h. The dispersion medium was not replenished during the ball milling process. It was found that the dispersion medium escaped in the system after 48 hours of ball milling, and the system dried up.

The white graphene nanosheets obtained in this example have a particle diameter of more than 250 nm, and the thickness of the nanosheets is that the thickness of most of the h-BN sheets is 40 nm. The specific surface area was determined to be 10 m ² /g.

Comparative example 2

The specific preparation process steps of this comparative example: weighing 100 g of white graphene (h-BN), 50 g of acetone and 150 g of deionized water without adding a surfactant.

After the ball milling, the white graphene is washed with alcohol, and then dried at 60 ° C in a muffle furnace to obtain a ball-milled white graphene product. The white graphene nanosheets obtained in this example have a particle diameter of more than 250 nm and a nanosheet thickness of about 40 nm. The specific surface area was determined to be 28 m ² /g.

The above-mentioned embodiments are merely illustrative of several embodiments of the present invention, and the description thereof is more specific and detailed, but is not to be construed as limiting the scope of the invention. It should be noted that a number of variations and modifications may be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, the scope of the invention should be determined by the appended claims.

Claims

A method for ball-peeling off white graphene, characterized in that the specific steps are:

Step 1) After the white graphene powder, the surfactant, and the ball milling medium are mixed and dissolved, the ball milling is performed at a ball milling speed of 200-800 rpm;

The mass ratio of the white graphene powder to the surfactant is 1:1-500:1; the mass ratio of the white graphene to the ball milling medium is 2:1-1:10;

Step 2) After each ball milling for a period of time, continue to add the ball milling medium in step 1, the ball milling medium is added in an amount of 5% to 40% by mass of the white graphene, and the total ball milling time is 120-480 h;

Step 3) After the completion of the grinding, the obtained powder is washed with alcohol and then dried to obtain a ball-milled white graphene dispersion.
The method for ball-peeling off white graphene according to claim 1, wherein a mass ratio of the white graphene (h-BN) powder to the surfactant is from 10:1 to 100:1; the white graphite The mass ratio of the olefin (h-BN) to the ball milling medium is 1:1 to 1:5.
The method for ball-peeling off white graphene according to claim 1 or 2, wherein in the step 2, the ball milling medium is added every 2 hours in the first 24 hours; and the ball milling medium is added every 24 hours after the ball milling time exceeds 24 hours.
The method of ball-peeling off white graphene according to claim 1 or 2, wherein the ball milling medium is a low molecular weight alcohol and/or an aqueous ketone solution.
The method of ball-striping white graphene according to claim 4, wherein the low molecular weight alcohol and/or aqueous ketone solution is a low molecular weight alcohol and/or a ketone to water mass ratio of 1:10 to 2:1.
The method for ball-peeling off white graphene according to claim 4, wherein the low molecular weight alcohol is at least one of methanol, ethanol, isopropanol, tert-butanol, and ethylene glycol; The molecular weight ketone is acetone.
The method of ball-peeling off white graphene according to claim 1 or 2, wherein the surfactant is at least one of a surfactant having a long-chain Lewis acid or a long-chain Lewis base.
The method for ball-peeling white graphene according to claim 7, wherein the surfactant is a higher fatty acid, a fatty ketone, an alicyclic ketone, an aromatic ketone having a C atom number greater than 14 with a long-chain Lewis acid; At least one of its corresponding derivatives; or at least one of an olefin, an aromatic compound, an amine, and an ether having a long-chain Lewis base.
The method for ball-peeling white graphene according to claim 8, wherein the surfactant of the long-chain Lewis acid is: palmitic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, soft At least one of a fatty acid, octadecyl ketone, 3-methylcyclotridecyl ketone, cyclotetradecanone, 3-hexadecanone, palm aldehyde, coconut aldehyde, eicosanal;

The surfactant of the long-chain Lewis base is: palmamine, heptadecylamine, octadecylamine, oleylamine, cholestyramine, terminal aminopolyethylene glycol, polyphenylacetylene, polythiophene, polystyrene sulfonate At least one of sodium, dodecylbenzene, 4-dodecylaniline, polyoxyethylene octylphenol ether, glycidyl 12-14 alkyl ether, and hexaethylene glycol monohexadecyl ether.