CN111606318B - Method for dispersing carbon nano tube by wet method mechanical deagglomeration - Google Patents

Method for dispersing carbon nano tube by wet method mechanical deagglomeration Download PDF

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CN111606318B
CN111606318B CN201910132539.5A CN201910132539A CN111606318B CN 111606318 B CN111606318 B CN 111606318B CN 201910132539 A CN201910132539 A CN 201910132539A CN 111606318 B CN111606318 B CN 111606318B
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carbon nanotubes
carbon nano
dispersion
temperature
solid
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CN111606318A (en
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张经纬
庞凯祥
赵方
张文豪
张纪伟
龚春红
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Henan University
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/15—Nano-sized carbon materials
    • C01B32/158—Carbon nanotubes
    • C01B32/168—After-treatment
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Abstract

The invention provides a method for dispersing carbon nano tubes by wet mechanical deagglomeration, which comprises the following steps: a) Dispersing the carbon nano tube in the solution to obtain a mixed system, and adjusting the temperature of the mixed system to enable part of solvent or solute to undergo controllable liquid/solid phase transformation to obtain a solid/liquid two-phase flow system with periodically and dynamically changed solid content; b) And applying mechanical force in the system to deagglomerate the carbon nano tubes, so as to obtain a well-dispersed high-quality carbon nano tube dispersion liquid. The invention deagglomerates the carbon nano-tubes in a specific temperature and liquid phase environment to obtain the carbon nano-tubes with good dispersion. The preparation process has no toxic organic additive and the like, is environment-friendly, low in cost, simple in process, high in production efficiency, good in dispersion stability, low in equipment cost, easy to scale up and the like. The carbon nano tube dispersion liquid prepared by the invention has good application prospect.

Description

Method for dispersing carbon nano tube by wet method mechanical deagglomeration
Technical Field
The invention relates to the technical field of materials, in particular to a method for deagglomerating and dispersing carbon nano tubes by wet process machinery.
Background
Since carbon nanotubes were found, research on carbon nanotubes in the fields of physics, chemistry, materials, biology, information, etc., has grown geometrically. The carbon nano tube has excellent physical, chemical, electronic and optical characteristics and potential application prospect in various fields. Carbon nanotubes can be regarded as crimped graphene sheets so as to have high tensile strength in addition to graphite and graphene intrinsic characteristics such as heat resistance, corrosion resistance, thermal shock resistance, high-temperature strength, self-lubricity and biocompatibility, and are the strongest fibers; has excellent properties the electrical conductivity in the axial direction is, is a good one-dimensional quantum wire; the axial heat exchange performance is very good, the radial heat exchange performance is very poor, and the heat exchange material is an ideal anisotropic heat conduction material; the hollow structure makes it possess considerable hydrogen storage performance and is also ideal catalyst carrier material. Although carbon nanotubes have great potential for use in many applications, carbon nanotubes generally exhibit entangled agglomerated states for the treated carbon nanotubes due to their large aspect ratio and large specific surface area. At present, how to obtain carbon nanotubes with better dispersion is still a key to restrict the commercial application of the carbon nanotubes.
Although there are some methods for dispersing carbon nanotubes, such as ball milling, ultrasonic dispersion, and strong acid and alkali treatment. However, the existing dispersion technology severely damages the structure of the carbon nanotubes themselves. Such as a strong acid treatment method commonly used in scientific research, hydrophilic carbon nanotubes with certain dispersibility can be obtained. However, in this method, when the carbon nanotubes are subjected to a strong acid treatment, the outer tube wall has a certain amount of functional groups after being oxidized. Although the high-temperature treatment can remove most of functional groups, the residual defects are permanent and difficult to recover completely, carbon nano tube dispersion liquid with few high-quality defects is difficult to prepare, dangerous chemicals are needed in the preparation process, a large amount of waste liquid is generated, and the production process does not accord with the development direction of green chemical industry; the high ball milling method is another common method for dispersing carbon nanotubes, but the high energy input can lead to the breakage of the carbon nanotubes, the reduction of the length-diameter ratio, and the concentration of stress can lead to the bonding of the dispersed short carbon nanotubes, and small agglomerates are formed again. Other methods for dispersing carbon nanotubes have certain limitations and disadvantages, and it is difficult to effectively prepare high-quality high-concentration stably-dispersed carbon nanotubes.
Therefore, the development of an environment-friendly preparation process realizes high-efficiency and low-cost dispersion of the high-quality carbon nanotubes, and is a precondition for realizing commercialized application of the carbon nanotubes. The selection of the means for applying mechanical force as dispersing the carbon nanotubes can greatly avoid the generation of defects of the carbon nanotubes and the use of high-risk chemicals. Research shows that the application mode of mechanical force and the property of the solvent have significant influence on the dispersing effect. The dispersion of carbon nanotubes is generally divided into two stages: deagglomeration of the large agglomerates and dispersion of the small bundles of carbon nanotubes. There are relatively many methods to date for breaking large agglomerates of carbon nanotubes into small bundles of nanotubes, such as ball milling, ultrasonic dispersion, high-speed shearing, and the like. However, the dispersion of further bundles of small carbon nanotubes remains a limitation in the ability of carbon nanotubes to exhibit their excellent physicochemical properties.
According to Newton's law of viscosity, when the mixed fluid is in a laminar flow state, due to viscous action, a flow speed difference Deltav exists between particles in the solution and two inner and outer contact surfaces of the solution, and within a certain range, the flow speed difference Deltav of the two contact surfaces and the distance Deltax of the two contact surfaces of the particles n Linear correlation. At this time, the stress f=k to which the material is subjected 1 Δx n ＝k 2 Δv n . Where n is the rheology index, n=1 for newtonian fluids and n+.1 for non-newtonian fluids; k (k) 1 ，k 2 The linear correlation coefficients of F, deltax and Deltav are positively correlated with the system viscosity eta in a certain viscosity range. In the process of dispersing the small carbon nano tube bundles, when the included angle between the carbon nano tube and the stress direction is theta, the carbon nano tube is subjected to shearing force Fcos theta and tensile stress Fsin theta. As the tube bundle diameter decreases, i.e., Δx, Δv decreases, the force F experienced during dispersion of the carbon nanotubes also decreases accordingly. Generally, when the carbon nanotubes are subjected to a shearing force Fcos θ smaller than the frictional force f between the bundles of carbon nanotubes or a tensile stress Fsin θ smaller than the van der waals force between the bundles of carbon nanotubes, the dispersion efficiency of the carbon nanotubes is rapidly lowered so that the dispersion degree is not high. Therefore, the traditional method for dispersing the carbon nano tube by mechanical force has certain limitation, and is difficult to achieve higher dispersion degree. To increase the dispersion degree, generally, the energy input is increased or the viscosity of the solution is increased, which is favorable for increasing the cost and the difficulty; another approach is to oxidize or functionalize bundles of small carbon nanotubes, but these can destroy the structure of the carbon nanotubes themselves and cause defects that are almost impossible to recover, which all limit their commercial application.
Disclosure of Invention
In view of the above, the technical problem to be solved by the invention is to provide a method for deagglomerating and dispersing carbon nanotubes by wet-process machinery, which has the advantages of low cost, simple process, high production efficiency, high product dispersion stability and fewer defects.
The invention provides a method for dispersing carbon nano tubes by wet mechanical deagglomeration, which comprises the following steps:
dispersing the carbon nano tube in the solution to obtain a mixed system, and adjusting the temperature of the mixed system to enable part of solvent or solute to undergo controllable liquid/solid phase transformation to obtain a solid/liquid two-phase flow system with periodically and dynamically changed solid content; and applying mechanical force in the system to deagglomerate the carbon nanotubes, so as to obtain a well-dispersed carbon nanotube dispersion. The mixed system temperature range setting may follow the following principle: the solute saturation precipitation system is X+20-X-20; the temperature of the mixed system is X+5-X-5 for the solvent condensation crystallization system. Preferably, the carbon nanotubes are selected from one or more of single-walled carbon nanotubes, double-walled carbon nanotubes and multi-walled carbon nanotubes.
Preferably, the solution comprises one or more of an organic solvent, a surfactant, a soluble polymer and a soluble solid.
Preferably, the organic solvent is selected from one or more of N-alkyl-pyrrolidone, amide, alcohol, ketone, pyridine, N-formylpiperidine, 1, 3-dimethyl-2-imidazolidinone, N-methylmorpholine, N-methylmorpholine-N-oxide, bromobenzene, benzonitrile, benzyl benzoate, N-dimethyl propylene urea, gamma-butyrolactone, DMSO, dibenzyl ether, chloroform, chlorobenzene, 1-3 dioxolane, ethyl acetate, quinoline, benzaldehyde, diethyl phthalate, dimethyl phthalate, vinyl acetate, water, ammonia and carbon dioxide;
the surfactant is one or more selected from sodium alginate, sodium cholate, lithium dodecyl sulfate, sodium dodecyl benzene sulfonate, tetraethylammonium hydroxide, cetyltrimethylammonium bromide, deoxycholate, taurodeoxycholate, polyoxyethylene (40) nonylphenyl ether, branched (IGEPAL CO-890 and polyethylene glycol p- (1, 3-tetramethylbutyl) phenyl ether (Triton-x 100 (TX-100));
the soluble polymer is selected from one or more of polyethylene glycol, polyvinyl alcohol, polyvinylpyrrolidone, polybutadiene, styrene-butadiene copolymer, polystyrene, polyvinyl chloride, polyvinyl acetate, polycarbonate, polymethyl methacrylate, polyvinylidene fluoride, polyvinylidene chloride, cellulose acetate, polyimide, acrylate rubber, polyisocyanate resin and polyvinyl butyral;
the soluble solid is selected from one or more of urea, chloride, carbonate, sulfate, hydroxide and phosphate.
Preferably, the stripping temperature is 50 ℃ to-50 ℃; the stripping time is 0.5-16 h.
Preferably, the temperature of the mixed system for the solute saturated precipitation system is X+20-X-20, wherein X is the solute precipitation temperature; the temperature of the mixed system for the solvent condensation crystallization system is X+5-X-5, wherein X is the freezing point temperature.
Preferably, the mechanical force is selected from one or more of high-speed shearing, mechanical stirring and high-pressure jet flow.
Preferably, when the mechanical force is mechanical stirring, the stirring rotating speed is 100-2000 rpm, and the stirring time is 8-16h.
Preferably, when the mechanical force is high-speed shearing, the stirring rotating speed is 2000-24000 rpm; the stirring time is 0.5-12 h.
Preferably, the ratio of the mass of the carbon nanotubes to the solvent is (1): (25-250).
Compared with the prior art, the invention provides a method for mechanically deagglomerating and dispersing carbon nano tubes by a wet method, which comprises the following steps: a) Dispersing the carbon nano tube in the solution to obtain a mixed system, and adjusting the temperature of the mixed system to enable part of solvent or solute to undergo controllable liquid/solid phase transformation to obtain a solid/liquid two-phase flow system with periodically and dynamically changed solid content; b) And applying mechanical force in the system to deagglomerate the carbon nanotubes, so as to obtain a well-dispersed carbon nanotube dispersion. The invention deagglomerates the carbon nano-tubes in a specific temperature and liquid phase environment to obtain the carbon nano-tubes with good dispersion. The preparation process has no toxic organic additive and the like, is environment-friendly, low in cost, simple in process, high in production efficiency, good in dispersion stability, low in equipment cost, easy to scale up and the like. The carbon nano tube dispersion liquid prepared by the invention has good application prospect.
Drawings
FIG. 1 is an optical comparison photograph of the multiwall carbon nanotubes of example 1 before and after being dispersed with dimethyl phthalate;
FIG. 2 is a graph of the test stability analysis of the product of example 2;
FIG. 3 is a scanning electron microscope image of the product of example 3 after being combined with silicon and dried on copper foil to obtain electrode sheets;
FIG. 4 is an optical photograph of a sample after 400-fold dilution of the product of example 4 and an ultraviolet absorption spectrum;
FIG. 5 is a scanning electron microscope contrast plot of the carbon nanotubes before and after dispersion in example 5;
fig. 6 is a raman test analysis of the product of example 6.
Detailed Description
The invention provides a method for deagglomerating and dispersing carbon nano tubes by wet-process machinery, and a person skilled in the art can properly improve the technological parameters by referring to the content of the invention. It is expressly noted that all such similar substitutions and modifications will be apparent to those skilled in the art, and they are intended to be within the scope of the present invention. While the methods and applications of this invention have been described in terms of preferred embodiments, it will be apparent to those skilled in the relevant art that the invention can be practiced and practiced with modification and alteration and combination of the methods and applications herein without departing from the spirit and scope of the invention.
The invention provides a method for dispersing carbon nano tubes by wet mechanical deagglomeration, which comprises the following steps:
a) Dispersing the carbon nano tube in the solution to obtain a mixed system, and adjusting the temperature of the mixed system to enable part of solvent or solute to undergo controllable liquid/solid phase transformation to obtain a solid/liquid two-phase flow system with periodically and dynamically changed solid content;
b) And applying mechanical force in the system to deagglomerate the carbon nanotubes, so as to obtain a well-dispersed carbon nanotube dispersion.
The method for dispersing carbon nano tubes by wet mechanical deagglomeration firstly disperses the carbon nano tubes in a solution to obtain a mixed system.
The carbon nanotube is one or more selected from single-wall carbon nanotubes, double-wall carbon nanotubes and multi-wall carbon nanotubes.
The source of the carbon nanotubes is not limited, and the carbon nanotubes may be commercially available as known to those skilled in the art.
The dispersion method of dispersing the carbon nanotubes in the solution is not limited, and may be known to those skilled in the art.
The solution of the invention is a single solvent or a mixed solution which is liquid at normal temperature, or can be a single solvent or a mixed solvent which is gas or solid at normal temperature and is converted into liquid by changing temperature or pressure.
The solution of the invention preferably comprises one or more of an organic solvent, a surfactant, a soluble polymer and a soluble solid; preferably two or more of an organic solvent, a surfactant, a soluble polymer and a soluble solid;
wherein the organic solvent is preferably selected from one or more of N-alkyl-pyrrolidone, amide, alcohol, ketone, pyridine, N-formylpiperidine, 1, 3-dimethyl-2-imidazolidinone, N-methylmorpholine, N-methylmorpholine-N-oxide, bromobenzene, benzonitrile, benzyl benzoate, N-dimethyl propylene urea, gamma-butyrolactone, DMSO, dibenzyl ether, chloroform, chlorobenzene, 1-3 dioxolane, ethyl acetate, quinoline, benzaldehyde, diethyl phthalate, dimethyl phthalate, vinyl acetate, water, ammonia and carbon dioxide;
the surfactant is preferably one or more selected from sodium alginate, sodium cholate, lithium dodecyl sulfate, sodium dodecyl benzene sulfonate, tetraethylammonium hydroxide, cetyltrimethylammonium bromide, deoxycholate, taurodeoxycholate, polyoxyethylene (40) nonylphenyl ether, branched (IGEPAL CO-890 and polyethylene glycol p- (1, 3-tetramethylbutyl) phenyl ether (Triton-x 100 (TX-100));
the soluble polymer comprises thermoplastic resin, thermosetting resin, elastomer and natural polymer which is soluble in a proper solvent, preferably one or more selected from polyethylene glycol, polyvinyl alcohol, polyvinylpyrrolidone, polybutadiene, styrene-butadiene copolymer, polystyrene, polyvinyl chloride, polyvinyl acetate, polycarbonate, polymethyl methacrylate, polyvinylidene fluoride, polyvinylidene chloride, cellulose acetate, polyimide, acrylate rubber, polyisocyanate resin and polyvinyl butyral;
the soluble solid is preferably selected from one or more of urea, chloride, carbonate, sulfate, hydroxide and phosphate.
The source of the above solution is not limited in the present invention, and the present invention is commercially available as known to those skilled in the art.
After the mixed system is obtained, the temperature of the mixed system is regulated to enable part of the solvent to be subjected to controllable liquid/solid phase transformation, so that a solid/liquid two-phase flow system with dynamically changed solid content is obtained.
The temperature range of the mixed system is X+20-X-20 for a solute saturated precipitation system; wherein X is the solute precipitation temperature; the temperature of the mixed system is X+5-X-5 for the solvent condensation crystallization system; wherein X is the freezing point temperature of the mixed system.
Wherein the solute saturated precipitation system is a system containing one or more materials in soluble polymers and soluble solids, and the solid content change is mainly precipitation/dissolution between solid and liquid phases of the soluble substances; the solvent condensation crystallization system is a system without soluble polymer and soluble solid, and the solid content change is mainly solidification/melting among solid and liquid phases of the solvent.
By adjusting the system temperature, the system state is changed, and part of the solvent is controllably converted into liquid/solid phase, such as solid-liquid-solid or liquid-solid-liquid phase, so as to construct a solid/liquid two-phase flow system with dynamically changed solid content, and the viscosity and the solid content of the system are increased periodically, thereby remarkably improving the deagglomeration dispersion efficiency.
The invention carries out shearing deagglomeration and dispersion on the carbon nano tube in a specific solvent system. In the specific temperature range, the method can enhance the shearing and deagglomeration dispersing effects of mechanical force on the carbon nano tube, and the prepared carbon nano tube dispersion liquid has the characteristic of stable dispersion under high concentration.
The mechanical force is preferably selected from one or more of high-speed shearing, mechanical stirring, ball milling and high-pressure jet. The deagglomeration and dispersion process can be operated in batch or continuous mode.
The invention is not limited to the manner or apparatus in which the mechanical force is applied, but is well known to those skilled in the art; including but not limited to: mechanical stirrer, high-speed homogenizer, high-pressure homogenizer, cooking machine and high-speed emulsification dispersion machine.
According to the invention, when the mechanical force is mechanical stirring, the stirring rotating speed is 100-2000 rpm, and the stirring time is 8-16h; when the mechanical force is high-speed shearing, the stirring rotating speed is 2000-24000 rpm; the stirring time is 0.5-12 h.
Wherein, the deagglomeration temperature of the invention is selected in relation to the solidification temperature/salting-out temperature of the selected solvent, and different solution systems have different temperatures.
The inventors found that the longer the peeling time, the more uniform the dispersion of the resulting carbon nanotubes at a temperature near the freezing point of the system under the proper shear rate conditions.
The stirring speed is different according to the choice of solvent and the choice of material ratio, such as: stirring and dispersing single-wall carbon nanotubes in NMP, and selecting 400rpm for 12 hours; and shearing and dispersing the multi-wall carbon nano tube in a supersaturated urea system, and selecting 11000rpm for 4 hours.
The mass to solution ratio of the carbon nanotubes is preferably 1: (20-300); more preferably 1: (25-250). The mass ratio of the raw materials is selected depending on the type of the carbon nanotube. For example, the mass to solution ratio selected for dispersing the high purity single wall carbon nanotubes is preferably 1: (200-300); the mass to solution ratio selected for dispersing the multiwall carbon nanotubes is preferably 1: (20-100)
The viscosity change range in the dispersion process directly affects the torque under a certain volume, and the change of the torque under the same volume and the same rotating speed is essentially the change of the viscosity of the internal sizing agent. Specifically, the torque of the mixed system is 1-4 N.cm under the volume of 100 ml; the torque of the mixed system is 2-15 N.cm under the volume of 500 ml; under the volume of 1L, the torque of the mixed system is 3-40 N.cm, namely the torque is changed in a set temperature range and is changed along with the change of the temperature, and the torque is naturally changed along with the change of the type, the size and the stirring parameters of the stirring paddle.
In the set temperature range, the soluble compound is continuously separated out, dissolved and separated out in the dispersing process.
When the polymer monomer is selected as a solvent to disperse the carbon nanotubes, the polymer monomer can be induced to polymerize after the dispersion is completed, and the polymer matrix composite can be obtained.
And selecting and adding nano particles after the carbon nano tubes are dispersed, and obtaining a dispersion liquid of uniformly mixing the carbon nano tubes and the nano particles after the dispersion is completed.
And adding a stabilizer after the dispersion of the carbon nanotube dispersion is finished to obtain the carbon nanotubes which are stably dispersed in long-term storage.
The invention is not limited to the specific type of stabilizer, and can be known to those skilled in the art, for example, polyvinylidene fluoride, and the addition ratio is preferably 5: (1-3)
The carbon nanotube dispersion liquid finally prepared after stripping is the carbon nanotube dispersion liquid with high concentration, few defects and stable dispersion.
The invention provides a high-efficiency and environment-friendly wet deagglomeration carbon nano tube dispersing method, which can realize high-efficiency dispersion by applying mechanical force under the condition of no pretreatment on the original carbon nano tube, and can obtain high-concentration stable dispersion liquid. If a proper stabilizer is added, the maximum dispersion concentration and dispersion stability of the product can be further improved. The carbon nanotubes may also be directly dispersed in a suitable polymer system to produce a polymer matrix composite.
Research has shown that carbon nanotubes require two stages in the dispersion process, deagglomeration of large agglomerates and dispersion of small bundles of carbon nanotubes. The dispersion process and possible principle of the carbon nanotubes proposed by the present invention are summarized as follows:
deagglomeration process for large agglomerates: during solidification/melting of the solvent or precipitation/dissolution of the solute, a large number of solid particles are periodically generated. Under the action of mechanical force, the solid particles are difficult to grow into a macroscopic block structure, and most of the solid particles still exist in the form of fine particles. The presence of a large number of precipitated/crystallized particles serves a similar media milling and ball milling function to deagglomerate the bulk carbon nanotube agglomerates.
For the dispersion process of small carbon nanotube bundles: for small carbon nanotube bundles with length-diameter ratio, under the condition of applying mechanical force, the existence of flow velocity difference enables the small carbon nanotubes to be oriented along the flowing direction, and because the viscosity of the system is increased and solid particles attached to the walls of the carbon nanotubes exist, the flow velocity difference on two sides among the walls is increased, so that the stress of the carbon nanotubes is increased, and the carbon nanotubes are easier to fall off from the bundles. In order to further illustrate the present invention, a method for preparing a two-dimensional material by wet mechanical exfoliation is provided in the present invention in detail below with reference to examples.
Example 1
The specific preparation process of the embodiment comprises the following steps: 8g of the original multi-wall carbon nanotubes were dispersed in 400mL of dimethyl phthalate to prepare a mixed solution, and transferred to a double-layer reaction vessel.
The temperature of the system is regulated by a low-temperature cooling liquid circulating pump externally connected with the double-layer reaction kettle to be controlled near the freezing point of 2 ℃, and then the system is stirred and dispersed for 8 hours at 500rpm by a mechanical stirrer.
After stirring, the dimethyl phthalate dispersion liquid of the multiwall carbon nano tube can be obtained
FIG. 1 is a photograph showing an optical comparison of the multiwall carbon nanotubes of example 1 before and after dispersing with dimethyl phthalate. By comparison, the carbon nanotubes are changed from a bulk aggregation state to a uniform dispersion state after being dispersed.
Example 2
The specific preparation process of the embodiment comprises the following steps: 12g of the original multi-walled carbon nanotubes were dispersed in 400mLN, N-dimethylaniline to prepare a mixed solution, which was transferred to a double-layer reaction vessel.
The temperature of the system is regulated by a low-temperature cooling liquid circulating pump externally connected with the double-layer reaction kettle to be controlled to be near the freezing point of-20 ℃, and then the system is stirred and dispersed for 15 hours at 500rpm by a mechanical stirrer.
After stirring, the DMA dispersion liquid of the multiwall carbon nano tube can be obtained
FIG. 2 is a graph of stability data for the product of example 2, test conditions 1000rpm,20000s. From the result data, it can be seen that the entire transmittance is not increased after centrifugation at 1000rpm for 20000s at a portion below 108mm of the liquid surface, and that the carbon nanotubes after the dispersion treatment remain stably dispersed and no obvious sedimentation phenomenon occurs.
Example 3
The specific preparation process of the embodiment comprises the following steps: 4g of single-walled carbon nanotubes were dispersed in 400mL of N-methylpyrrolidone to prepare a mixed solution, and transferred to a double-layer reaction vessel.
The temperature of the system is regulated by a low-temperature cooling liquid circulating pump externally connected with the double-layer reaction kettle to be controlled to be near the freezing point of-24 ℃, and then the system is stirred and dispersed for 8 hours at 500rpm by a mechanical stirrer.
And after the dispersing process is finished, adding polyvinylidene fluoride (hsv 900) serving as a lithium battery adhesive into the slurry, and stirring and dispersing uniformly to obtain the high-quality dispersed carbon nanotube dispersion liquid which can be used as a lithium battery.
Fig. 3 is a scanning electron microscope image of a composite electrode sheet prepared by coating a copper foil after the product of example 3 is compounded with nano silicon spheres, and it can be seen from fig. 3 that single-walled carbon nanotubes are uniformly dispersed in the electrode sheet using nano silicon spheres and polyvinylidene fluoride as active substances.
Example 4
The specific preparation process of the embodiment comprises the following steps: 1.6g of single-walled carbon nanotubes were dispersed in 400mL of NMP to prepare a mixed solution, and transferred to a double-layer reaction vessel.
The temperature of the system is regulated by a low-temperature cooling liquid circulating pump externally connected with the double-layer reaction kettle, so that the system is controlled to be near the freezing point of-24 ℃, and then the system is stirred and dispersed for 10 hours at 500rpm by using a mechanical stirrer.
And adding polyvinylidene fluoride (5130) into the slurry after the dispersion is finished, so as to obtain the carbon nano tube transparent conductive film coating meeting the commercial standard.
Fig. 4 is an optical photograph of a sample after 400-fold dilution of the product of example 4 and an ultraviolet absorption spectrum, and it can be seen from the inset of fig. 4 that the carbon nanotubes are well dispersed by mechanical stirring and dispersion, and the absorption value of the diluted dispersion liquid at the wavelength of 500nm is 0.482, which is higher than the standard value of the commercial carbon nanotube transparent conductive film coating by 0.45.
Example 5
The specific preparation process of the embodiment comprises the following steps: 10g of multi-wall carbon nano tube is dispersed in 400mL of dimethyl sulfoxide to prepare a mixed solution, 2g of sodium cholate is added, and the mixed solution is transferred into a double-layer reaction kettle.
The temperature of the system is regulated by a low-temperature cooling liquid circulating pump externally connected with the double-layer reaction kettle to be controlled near the freezing point of 18 ℃, and then the system is stirred and dispersed for 16 hours at 400rpm by a mechanical stirrer.
The product was water-washed and lyophilized, and then sampled and taken as a scanning electron microscope picture.
Fig. 5 is a photograph of a scanning electron microscope of the product, and it can be seen from fig. 5 that the state of multi-beam agglomeration of carbon nanotubes is solved by the dispersion treatment, and the state of single-beam or few-beam deagglomeration of the carbon nanotube bundles is presented.
Example 6
The specific preparation process of the embodiment comprises the following steps: 0.8g of single-walled carbon nanotubes was dispersed in 0.4wt% of 400mL of polyvinylpyrrolidone aqueous solution, and 20mL of t-butanol was added to the mixture, followed by transfer to a double-layer reaction vessel.
The temperature of the system is regulated by a low-temperature cooling liquid circulating pump externally connected with the double-layer reaction kettle to be controlled to be near the freezing point of-5 ℃, and then the system is stirred and dispersed for 12 hours at 400rpm by a mechanical stirrer.
Fig. 6 is a raman test analysis chart of the product of example 6, showing that no significant D peak appears in the raman chart of the single-walled carbon nanotubes before and after dispersion after the dispersion treatment, indicating that no structural defect is introduced in dispersing the single-walled carbon nanotubes.
Example 7
The specific preparation process of the embodiment comprises the following steps: 0.8g of single-walled carbon nanotubes was dispersed in 0.1wt% of 400mL of an aqueous carboxymethyl cellulose solution, and 20mL of t-butanol was added to the mixture, followed by transfer to a double-layer reaction vessel.
The temperature of the system is regulated by a low-temperature cooling liquid circulating pump externally connected with the double-layer reaction kettle to be controlled near the freezing point of-7 ℃, and then the system is stirred for 12 hours at 400rpm by a mechanical stirrer, so that the single-wall carbon nanotube dispersion liquid with good dispersion can be obtained.
The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention.
The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention.

Claims (5)

1. A method of wet mechanical deagglomerating dispersed carbon nanotubes comprising:
a) Adding carbon nanotubes into the solution to obtain a mixed system, and adjusting the temperature of the mixed system to enable a part of solvent or solute to undergo controllable liquid/solid phase transformation to obtain a solid/liquid two-phase flow system with periodically and dynamically changed solid content; the solution comprises two or more of an organic solvent, a surfactant, a soluble polymer and a soluble solid; the mass to solution ratio of the carbon nanotubes is 1: (20-300);
the organic solvent is selected from one or more of N-alkyl-pyrrolidone, amide, alcohol, ketone, pyridine, N-cresol piperidine, 1, 3-dimethyl-2-imidazolidinone, N-methylmorpholine, N-methylmorpholine-N-oxide, bromobenzene, benzonitrile, benzyl benzoate, N-dimethyl propylene urea, Y-butyrolactone, DMSO, dibenzyl ether, chloroform, chlorobenzene, 1, 3-dioxolane, ethyl acetate, quinoline, benzaldehyde, diethyl phthalate, dimethyl phthalate and vinyl acetate;
the surfactant is one or more selected from sodium alginate, sodium cholate, lithium dodecyl sulfate, sodium dodecyl benzene sulfonate, tetraethylammonium hydroxide, cetyltrimethylammonium bromide, deoxycholate and taurodeoxycholate;
the soluble polymer is selected from one or more of polyethylene glycol, polyvinyl alcohol, polyvinylpyrrolidone, polybutadiene, styrene-butadiene copolymer, polystyrene, polyvinyl chloride, polyvinyl acetate, polycarbonate, polymethyl methacrylate, polyvinylidene fluoride, polyvinylidene chloride, cellulose acetate, polyimide, acrylate rubber, polyisocyanate resin and polyvinyl butyral;
the soluble solid is selected from one or more of urea, chloride, carbonate, sulfate, hydroxide and phosphate;
b) Applying mechanical force in the system to deagglomerate the carbon nanotubes, so as to obtain a well-dispersed carbon nanotube dispersion; the deagglomeration dispersion temperature is 50-50 ℃; the deagglomeration dispersion time is 0.5-16 h;
the temperature of the mixed system for the solute saturated precipitation system is X+20-X-20; the temperature of the mixed system for the solvent condensation crystallization system is X+5~X-5; and X is the freezing point temperature of the mixed system.
2. The method of claim 1, wherein the carbon nanotubes are selected from one or more of single-walled carbon nanotubes, double-walled carbon nanotubes, and multi-walled carbon nanotubes.
3. The method of claim 1, wherein the mechanical force is selected from one or more of high-speed shearing, mechanical stirring, ball milling, and high-pressure jet.
4. A method according to claim 3, wherein the mechanical force is mechanical stirring, the stirring speed is 100-2000 rpm, and the stirring time is 4-16 h.
5. A method according to claim 3, wherein the stirring speed is 2000-24000 rpm when the mechanical force is high shear; the stirring time is 0.5-12 h.
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