WO2021157756A1 - Procédé de préparation d'un composite de nanofibres de carbone- nanotubes de carbone et composite de nanofibres de carbone- nanotubes de carbone ainsi préparé - Google Patents

Procédé de préparation d'un composite de nanofibres de carbone- nanotubes de carbone et composite de nanofibres de carbone- nanotubes de carbone ainsi préparé Download PDF

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WO2021157756A1
WO2021157756A1 PCT/KR2020/001664 KR2020001664W WO2021157756A1 WO 2021157756 A1 WO2021157756 A1 WO 2021157756A1 KR 2020001664 W KR2020001664 W KR 2020001664W WO 2021157756 A1 WO2021157756 A1 WO 2021157756A1
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carbon
alkali metal
nanofibers
metal precursor
containing polymer
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Korean (ko)
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강준
고정혁
김대영
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한국해양대학교 산학협력단
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    • D—TEXTILES; PAPER
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
    • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
    • D06M13/00—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment
    • D06M13/10—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment with compounds containing oxygen
    • D06M13/144—Alcohols; Metal alcoholates
    • 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
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
    • D01D10/00—Physical treatment of artificial filaments or the like during manufacture, i.e. during a continuous production process before the filaments have been collected
    • D01D10/02—Heat treatment
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
    • D01D5/00—Formation of filaments, threads, or the like
    • D01D5/0007—Electro-spinning
    • D01D5/0015—Electro-spinning characterised by the initial state of the material
    • D01D5/003—Electro-spinning characterised by the initial state of the material the material being a polymer solution or dispersion
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F1/00—General methods for the manufacture of artificial filaments or the like
    • D01F1/02—Addition of substances to the spinning solution or to the melt
    • D01F1/10—Other agents for modifying properties
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F9/00—Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments
    • D01F9/08—Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments of inorganic material
    • D01F9/12—Carbon filaments; Apparatus specially adapted for the manufacture thereof
    • D—TEXTILES; PAPER
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
    • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
    • D06M13/00—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment
    • D06M13/02—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment with hydrocarbons
    • D06M13/03—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment with hydrocarbons with unsaturated hydrocarbons, e.g. alkenes, or alkynes
    • D06M13/07—Aromatic hydrocarbons

Definitions

  • the present invention relates to a method for producing a carbon nanotube-carbon nanofiber composite and a carbon nanotube-carbon nanofiber composite prepared thereby.
  • Carbon is a substance that exists in various forms, and the structure and physical properties of the substance change depending on the bonding method between carbon atoms.
  • a carbon atom has four valences composed of two 2s orbitals and two other 2p orbitals, and various allotropes exist because electrons are bonded to adjacent carbon atoms in various covalent bonds. That is, when a carbon atom is covalently bonded to another atom, the four electrons in the outermost shell form sp 3 , sp 2 and sp hybrid orbital by hybridization of s orbital and p orbital.
  • Representative carbon allotropes of each hybrid orbital include diamond composed of sp 3 hybrid orbitals, graphite composed of sp 2 hybrid orbitals, and carbine composed of sp hybrid orbitals.
  • carbon nanofiber (CNF), carbon nanotube (CNT), and fullerene which are recently spotlighted as carbon nanomaterials, are composed of sp 2 hybrid orbitals, but structural forms are different. Because they are different, there is a difference in the properties of substances.
  • carbon nanofibers are in the spotlight as a reinforcing component of fiber-reinforced materials because of their excellent mechanical strength and conductivity.
  • Carbon nanotubes are attracting attention as high-performance materials because they have superior mechanical strength, excellent elasticity, thermal and electrical properties, and low density compared to carbon nanofibers. Although many efforts have been made on carbon nanotubes so far, they have a pre-emptive problem that they must be manufactured for a much longer time and at a lower cost in order to be used in more diverse fields. Although research on composite materials using carbon nanotubes and polymers has been made only recently, carbon nanotubes have a large specific surface area. There is a problem in that it is difficult to realize high thermal conductivity, which is the intrinsic property of the tube, so it is difficult to disperse the carbon nanotubes in the polymer, making practical applications difficult. Much more research is still needed before development.
  • the composite material in which carbon nanotubes are formed on carbon nanofibers can combine the advantages of both, and excellent electrical and mechanical properties can be extended not only in the longitudinal direction of the carbon nanofiber but also in the direction perpendicular to it. It can serve as an ideal two-dimensional fiber-reinforced component. Furthermore, since these composite materials can utilize the relatively large surface area of carbon nanotubes, the adhesion area can be substantially expanded, and functional groups can be introduced into the carbon nanotubes, so that the compatibility of the fiber-reinforced material with the polymer can be improved.
  • Composite materials of carbon nanotubes and carbon nanofibers to date have suggested a solution to the problem of dispersing carbon nanotubes in a polymer, but the bonding force between carbon nanotubes and carbon nanofibers is weak, and the carbon nanotubes are not aligned. When it is made of a composite material, there is a problem that the mechanical strength is rather weak.
  • FIG. 1 showing the TEM photograph of the defects occurring in the conventional composite material of carbon nanotubes and carbon nanofibers, and the defective part caused by the non-alkali metal catalyst particles in the part indicated by the arrow in FIG. This is confirmed.
  • the present invention was invented to solve the above problems, and a method for producing a carbon nanotube-carbon nanofiber composite that enables carbon nanotubes to grow from the surface of carbon nanofibers, and a carbon nanotube-carbon produced thereby It is a technical solution to provide a nanofiber composite.
  • the present invention provides a first step of dissolving an alkali metal precursor in a solvent to prepare an alkali metal precursor solution; a second step of preparing a spinning solution by dissolving a carbon-containing polymer in the alkali metal precursor solution; a third step of electrospinning the spinning solution to produce carbon-containing polymer nanofibers to which the alkali metal precursor is bonded to a surface; a fourth step of heat-treating the carbon-containing polymer nanofibers to prepare carbon nanofibers in which the alkali metal precursor is bonded to the surface; and heat treatment while supplying a carbon source to the carbon nanofibers so that the alkali metal precursor is activated as an alkali metal nanocatalyst, and the carbon source is bonded to the surface of the carbon nanofibers by the nanocatalyst as carbon nanotubes. It provides a method for producing a carbon nanotube-carbon nanofiber composite comprising; a fifth step of crystallizing and growing to produce carbon nanofibers
  • the alkali metal precursor is characterized in that it is selected from the group consisting of a lithium precursor (Li precursor), a sodium precursor (Na precursor), a potassium precursor (K precursor), and mixtures thereof.
  • the carbon-containing polymer is polyacrylonitrile (polyacrylonitrile, PAN), polyvinyl acetate (polyvinyl acetate, PVA), polyvinyl pyrrolidone (polyvinyl pyrrolidone, PVP), polycarbonate (polycarbonate, PC) , characterized in that it is selected from the group consisting of polyvinyl chloride (PVC), cellulose (cellulose), cellulose acetate (cellulose acetate), and mixtures thereof.
  • PAN polyacrylonitrile
  • PVA polyvinyl acetate
  • PVP polyvinyl pyrrolidone
  • PC polycarbonate
  • the carbon source is a liquid, gaseous or solid carbon source
  • the liquid carbon source is ethanol (C 2 H 6 O), benzene (C 6 H 6 ), xylene, toluene (C 7 H 8 ) ) and mixtures thereof
  • the gaseous carbon source is methane (CH 4 ), propylene (C 3 H 6 ), propine (C 3 H 4 ), propane (C 3 H 8 ), butane (C 4 ) H 10 ), butylene (C 4 H 8 ), butadiene (C 4 H 6 ), ethylene (C 2 H 2 ), and selected from the group consisting of mixtures thereof
  • the solid carbon source is camphor (C 10 H 16 O) characterized by being.
  • the carbon-containing polymer nanofiber is characterized in that the preliminary heat treatment at a temperature in the range of 100 to 300 °C.
  • the carbon-containing polymer is carbonized by heat treatment at a temperature in the range of 800 to 1,200° C. under an inert gas atmosphere.
  • the present invention provides a carbon nanotube-carbon nanofiber composite, characterized in that produced by the above method.
  • the carbon nanotube-carbon nanofiber composite of the present invention by means of solving the above problems, and the carbon nanotube-carbon nanofiber composite prepared by the method have the following effects.
  • lithium (Li), potassium (K) without using a catalyst based on transition metals, that is, non-alkali metals of Groups 8, 9, and 10 such as iron (Fe), cobalt (Co), and nickel (Ni)
  • transition metals that is, non-alkali metals of Groups 8, 9, and 10
  • iron (Fe), cobalt (Co), and nickel (Ni) since an alkali metal-based catalyst such as sodium (Na) is used, catalyst particles such as sodium are simply dissolved in water and can be easily removed, making the synthesis of metal-free carbon nanotube-carbon nanofiber composites easier. After completion, there is no need to go through a cleaning process such as acid treatment, which has the effect of reducing environmental costs.
  • carbon nanotubes can be easily grown from the surface of carbon nanofibers only by manufacturing carbon-containing polymer nanofibers having an alkali metal precursor bonded to their surface through electrospinning, carbonizing them, and then heat-treating them while supplying a carbon source. , carbon nanotube-carbon nanofiber composites can be mass-produced.
  • the carbon nanotube-carbon nanofiber composite produced through the present invention is an emission source of various devices, a vacuum fluorescent display (VFD), a white light source, a field emission display (FED), an electrode for a lithium ion battery, a hydrogen storage fuel cell, There is an effect that can be widely used in various energy application fields such as nanowires, gas sensors, micro-parts for biomedical engineering, and high-functional composites.
  • VFD vacuum fluorescent display
  • FED field emission display
  • an electrode for a lithium ion battery a hydrogen storage fuel cell
  • 1 is a TEM photograph showing defects occurring in a conventional composite material of carbon nanotubes and carbon nanofibers.
  • Figure 2 is a flow chart showing the manufacturing process of the carbon nanotube-carbon nanofiber composite according to the present invention.
  • Figure 3 is a schematic diagram showing a manufacturing process of the carbon nanotube-carbon nanofiber composite according to the present invention.
  • 5 is a conceptual diagram of electrospinning according to the present invention.
  • FIG. 6 is a photograph of a carbonization heat treatment furnace.
  • FIG. 7 is a photograph of a heat treatment furnace for growing carbon nanotubes on carbon nanofibers.
  • Example 8 is a SEM photograph of the carbon nanotube-carbon nanofiber composite prepared according to Example 1 of the present invention.
  • 10 is a SEM photograph showing the length of carbon nanotubes grown on carbon nanofibers.
  • 11 is a SEM photograph showing the density of carbon nanotubes grown on carbon nanofibers.
  • FIG. 2 is a flowchart showing the manufacturing process of the carbon nanotube-carbon nanofiber composite according to the present invention
  • FIG. 3 is a schematic diagram showing the manufacturing process of the carbon nanotube-carbon nanofiber composite according to the present invention, see this
  • the carbon nanotube-carbon nanofiber composite of the present invention is a first step (S10) of dissolving an alkali metal precursor in a solvent to prepare an alkali metal precursor solution
  • a carbon-containing polymer is dissolved in an alkali metal precursor solution to prepare a spinning solution
  • the fourth step (S40) of manufacturing the bonded carbon nanofibers and heat treatment while supplying a carbon source to the carbon nanofibers the alkali metal precursor is activated as an alkali metal nanocatalyst, and
  • an alkali metal precursor is dissolved in a solvent to prepare an alkali metal precursor solution (S10).
  • non-alkali metals of Groups 8, 9, and 10 such as iron (Fe), cobalt (Co), and nickel (Ni), that is, transition metal-based catalysts are mainly used.
  • an additional process such as acid treatment is required to remove the nanoparticles remaining in the metallic state of the non-alkali metal catalyst, and acid treatment In order to do this, washing water is required, so there has been a burden due to the increase in environmental costs.
  • an alkali metal precursor solution based on a Group 1 element other than hydrogen is dissolved in a solvent to prepare an alkali metal precursor solution. It allows the carbon nanotubes to grow from the surface of the nanofibers and is easily dissolved in water and removed without removing the nanocatalyst through a separate process such as acid treatment later, so that the synthesis of high-purity carbon nanotube-carbon nanofiber composites is possible. possible.
  • the alkali metal precursor is selected from the group consisting of a lithium precursor (Li precursor), a sodium precursor (Na precursor), a potassium precursor (K precursor), and a mixture thereof. That is, the alkali metal precursor is one or more alkali metal salts selected from the group consisting of lithium (Li), sodium (Na) and potassium (K), alkali metal organic compounds, or alkali metal inorganic compounds. It can be said that it is composed of alkali metal inorganic compounds.
  • lithium precursor which is a compound containing lithium
  • the sodium precursor is a compound containing sodium
  • sodium benzoate sodium benzoate
  • sodium chloride sodium chloride, NaOH
  • sodium bicarbonate sodium bicarbonate
  • potassium precursor which is a compound containing potassium, potassium benzoate
  • ate Potassium benzoate
  • potassium chloride Potassium chloride
  • potassium hydroxide Potassium hydroxide
  • the solvent consists of a polar solvent or a non-polar solvent, and is a polar solvent selected from the group consisting of water, dimethylformamide (DMF), lower alcohols having 1 to 5 carbon atoms, and mixtures thereof, or xylene, benzene ( A non-polar solvent selected from the group consisting of benzene), toluene, and mixtures thereof may be selected and used.
  • a polar solvent selected from the group consisting of water, dimethylformamide (DMF), lower alcohols having 1 to 5 carbon atoms, and mixtures thereof, or xylene, benzene ( A non-polar solvent selected from the group consisting of benzene), toluene, and mixtures thereof may be selected and used.
  • an alkali metal precursor solution in which an alkali metal precursor is mixed in a solvent is prepared in the following two ways.
  • an alkali metal precursor solution is prepared by dissolving an alkali metal precursor in a polar solvent such as dimethylformamide.
  • the amount of the alkali metal precursor used is not particularly limited, but when mixed at less than 0.01 mol per 1 liter of solvent, the alkali metal precursor cannot be activated or functionalized with the alkali metal nano catalyst when the fifth step heat treatment is performed. Not only does it take a lot of time until the point at which carbon nanotubes can be grown from the surface, but there are also cases where the carbon source supplied in the fifth step cannot be grown into carbon nanotubes, so it is limited in application to energy application fields. In particular, when the alkali metal precursor is added in an excessively small amount, the reaction rate cannot be increased, which is not preferable in terms of production efficiency.
  • the alkali metal precursor per 1 liter of solvent exceeds 0.05 mol
  • the alkali metal precursor is activated or functionalized with the alkali metal nanocatalyst during the heat treatment in the fifth step, and then the nanocatalysts remain partially attached to the carbon nanotubes.
  • the purity of the carbon nanotubes grown on the carbon nanofibers is reduced.
  • the alkali metal precursor in the range of 0.01 to 0.05 mol per 1 liter of solvent, and 0.02 mol is most preferable in consideration of the optimal activity as a nanocatalyst.
  • the alkali metal cation of the alkali metal precursor is coordinated to the cavity of the crown ether to form a complex, thereby solvating the alkali metal cation to prepare an alkali metal precursor solution.
  • Crown ether (x-Crown ether-y; x is the number of all atoms in the ring, y is the number of oxygen atoms) is an oligomer of ethylene oxide in which ethyleneoxy (-CH 2 CH 2 O-) units are repeated ( oligomer), which forms a stable structure with alkali metal cations as the alkali metal cations in the alkali metal precursor solution are put into the cavity at the center of the crown ether, so that the alkali metal cations are solvated and dissolved, especially in non-polar solvents.
  • the solubility of the phosphorus alkali metal precursor is increased.
  • crown ether forms a stable complex with metal ions, that is, alkali metal cations such as Li + , Na + , K + It will be able to bloom.
  • the alkali metal precursor When the alkali metal precursor is dissolved in the solvent through the crown ether, it is converted into a transparent alkali metal precursor solution.
  • the weight ratio of the crown ether may be 1:0.1-100.), it is also possible to control the solubility of the alkali metal precursor solution by adjusting the amount of the crown ether.
  • the amount in which the alkali metal precursor and the crown ether can be mixed is not limited.
  • crown ether it can be used by selecting from the group consisting of 12-Crown-4, 15-Crown-5, 18-Crown-6, and mixtures thereof. It can be confirmed through FIG. 4 shown.
  • Figure 4 (a) is an illustrative example of 12-Crown-4 forming a complex with Li +
  • Figure 4 (b) is an illustrative example of 15-Crown-5 forming a complex with Na +
  • FIG. 4( c ) exemplarily shows 18-Crown-6 forming a complex with K + .
  • the crown ether helps the oxygen atoms constituting the crown to coordinate alkali metal cations to the cavity in the crown, and the types of ions that form a stable complex depend on the size of the crown. That is, Li + forms the most stable complex with 12-Crown-4, Na + forms the most stable complex with 15-Crown-5, and K + forms the most stable complex with 18-Crown-6. can be checked
  • the solvents such as water or dimethylformamide presented in the first method are polar, so alkali metal precursors are easily dissolved, but in polar solvents and other non-polar solvents (eg, xylene), the alkali metal precursor does not dissolve, so crown ether is the solute. It solvates and plays an important role in increasing solubility.
  • a carbon-containing polymer is dissolved in an alkali metal precursor solution to prepare a spinning solution (S20).
  • 1 to 15 wt% of a polymer containing carbon is added to 85 to 99 wt% of the alkali metal precursor solution and dissolved while stirring to prepare a spinning solution capable of electrospinning.
  • the alkali metal precursor solution is relatively small.
  • the amount of the activated nanocatalyst is also relatively reduced, so that the amount of carbon nanotubes that can be grown from the surface of the carbon nanofibers is also reduced.
  • the alkali metal precursor solution is less than 85wt%, the amount of activated nanocatalyst is reduced, so the amount of carbon nanotubes that can be grown is also reduced.
  • the growth of carbon nanotubes cannot be stably performed due to insufficient space in which the nanocatalyst can be formed in the fiber.
  • the carbon-containing polymer be contained in an amount of 9wt% in consideration of solvent volatilization in the alkali metal precursor solution.
  • Carbon-containing polymers can be called carbon nanofiber precursors, polyacrylonitrile (PAN), polyvinyl acetate (PVA), polyvinyl pyrrolidone (PVP), polycarbonate (polycarbonate, PC), polyvinyl chloride (PVC), cellulose, cellulose acetate, and mixtures thereof may be selected from the group consisting of, and in the present invention, polyacrylonitrile is applied, but carbon It is not particularly limited as long as it is a carbon-containing polymer that can be formed into nanofibers.
  • This step is for producing a carbon-containing polymer nanofiber in the form of a fiber with a spinning solution.
  • FIG. 5 showing a conceptual diagram of electrospinning according to the present invention
  • a high voltage terminal is connected and a sufficiently high voltage is applied with the conductor connected to the ground
  • an electromagnetic field is formed between the nozzle and the conductor, and the spinning solution inside the nozzle is affected, and the electromagnetic force changes the surface tension and viscosity of the spinning solution.
  • a taylor cone is formed and stretched at the tip to form composite nanofibers, which are nano-sized composite fibers.
  • 'composite nanofibers' and 'nano-sized composite fibers' referred to in the present invention mean 'carbon-containing polymer nanofibers having an alkali metal precursor bonded to the surface'.
  • the molecular weight of the carbon-containing polymer For the production of nano-sized composite fibers through electrospinning, the molecular weight of the carbon-containing polymer, the characteristics of the spinning solution, the voltage, the distance between the nozzle and the conductor, the amount and concentration of the carbon-containing polymer, the parameters, the movement of the nozzle, the conductor It is desirable to satisfy the size and nozzle size conditions of , and each condition will be described in detail below.
  • the molecular weight conditions of the carbon-containing polymer are as follows. That is, if the molecular weight (M w ) of the polymer containing carbon is less than 45,000 or exceeds 1,000,000, it is difficult to form a composite nanofiber uniformly, so it is preferable to make it in the range of 45,000 to 1,000,000.
  • the characteristic conditions of the spinning solution are as follows. Regarding the viscosity of the spinning solution, if it is less than 1 Pa ⁇ s, the viscosity is too low and the spinning solution breaks before it is formed into nano-sized composite fibers in the process of electrospinning. If it exceeds s, the viscosity becomes too high and more electromagnetic force is required to elution from the nozzle, which causes overcurrent and burns the experimental equipment. desirable. With respect to the conductivity of the spinning solution, if it exceeds 53 ⁇ s/cm, it is not suitable for carbon nanofiber formation, so it is preferable that the spinning solution has a conductivity of 53 ⁇ s/cm or less.
  • the electromagnetic force With respect to the surface tension of the spinning solution, if it exceeds 450 dyn/cm, the electromagnetic force becomes smaller than the surface tension of the spinning solution, and Taylor cone formation does not occur, making it difficult to form a composite nanofiber. It is preferably made of 450 dyn/cm or less.
  • Voltage conditions are as follows. When a voltage of 30 kV or less is applied for electrospinning of the spinning solution, an electromagnetic field is formed between the nozzle and the conductor, so there is no need to apply a voltage exceeding 30 kV.
  • the distance condition between the nozzle and the conductor is as follows. That is, when the distance between the nozzle in which the spinning solution is accommodated and the conductor is less than 30 cm, the nano-sized composite fiber is formed. If the distance between the nozzle and the conductor exceeds 30 cm, the distance between the nozzle and the conductor is too far and the electromagnetic force is small, making it difficult to make the nano-size of the composite fiber uniform, as well as the disadvantage that the form of droplets rather than nanofibers can be seen. there is.
  • the fluid amount and concentration conditions of the carbon-containing polymer are as follows. When the amount of fluid is 25ml/min or less, the spinning solution is formed into a Taylor cone so that the nanofibers can be stretched well. The higher the probability, the higher the defect rate. In the case of concentration, 30 wt% is sufficient to be manufactured into nano-sized composite fibers.
  • the parameter conditions are as follows.
  • the parameters relate to basic environmental aspects such as temperature, humidity, and airflow.
  • a temperature of 35°C or less a humidity of 60% or less, and an airflow environment of 1 or less
  • the alkali metal precursor is bonded to the surface through electrospinning. It can be manufactured from carbon-containing polymer nanofibers.
  • the nozzle movement and conductor size conditions are as follows. First of all, the spinning solution is stably stretched to the conductor through electrospinning only when the movement of the nozzle is 0.1mm/min or less, and even if the size of the conductor is 10cm2 or more, the composite nanofibers electrospun from the nozzle are stably captured by the conductor. can be done However, if the size of the conductor is less than 10 cm 2 , the area is too small to secure a space to sufficiently collect the composite nanofibers.
  • the nozzle size conditions are as follows. If the nozzle size is less than 0.01 mm or exceeds 1.7 mm, it does not help the formation of carbon-containing polymer nanofibers bonded to the surface of the alkali metal precursor, so the nozzle size is preferably in the range of 0.01 to 1.7 mm.
  • the carbon-containing polymer nanofibers are heat-treated to prepare carbon nanofibers having an alkali metal precursor bonded to the surface (S40).
  • the carbon-containing polymer nanofibers having an alkali metal precursor bonded to the surface are heated to 100 to 300° C. at a temperature increase rate of 8 to 12° C./min in the atmosphere for 20 minutes to The carbon-containing polymer is stabilized through preliminary heat treatment for 1 hour. At this time, if the preliminary heat treatment is less than 100 °C, it is difficult to stabilize the carbon-containing polymer nanofibers, and if the preliminary heat treatment is made above 300 °C, the temperature is higher than necessary, which may cause deterioration of the shape or physical properties of the carbon-containing polymer nanofibers. .
  • a temperature increase rate it may be 8 to 12° C./min, and 10° C./min is most preferred.
  • the preliminary heat treatment is performed in less than 20 minutes, it is difficult to stabilize the carbon-containing polymer of the carbon-containing polymer nanofibers as in the temperature condition. There is no effect. In particular, it has the advantage of being able to rapidly form carbon-containing polymer nanofibers because oxygen supply is smooth only when preliminary heat treatment is performed in an oxygen environment in the atmosphere.
  • Carbonization herein refers to a heat treatment process for increasing the carbon/hydrogen ratio of the carbon-containing polymer constituting the carbon-containing polymer nanofiber, and refers to a process for converting carbon-containing components into carbon.
  • the heat treatment temperature for carbonization if the heat treatment is less than 800° C., it takes a lot of time to complete carbonization of the carbon-containing polymer due to incomplete carbonization, so that complete carbonization cannot be expected, so the surface of carbon nanofibers are damaged. On the other hand, if the temperature exceeds 1,200° C., the temperature is rather high, so that the carbon-containing polymer is not sufficiently converted to carbon or the degree of improvement in the properties of carbon nanofibers is reduced due to excessive heat treatment. The alkali metal precursor contained in the vaporized and disappeared, resulting in difficulties in the formation of the nano-catalyst in the future. For complete carbonization, it is most preferable to heat treatment at 1,000°C.
  • the reason why the temperature increase rate is relatively slow compared to when the preliminary heat treatment for stabilizing the carbon-containing polymer nanofibers is 3 to 7 °C/min is during the carbonization process while the temperature is increasing. This is to check whether there is any problem in the formation of carbon nanofibers and at the same time to prevent deterioration of the physical properties of carbon nanofibers. It is most preferably carried out at 5° C./min for stable carbon nanofiber production.
  • the target carbonization effect is insignificant, and if it exceeds 1 hour and 30 minutes, the inefficient aspect in the process is highlighted due to too long time.
  • process efficiency most preferably, it is good to heat-treat for 60 minutes to carbonize it.
  • the inert gas atmosphere may be, for example, a gas such as helium, nitrogen, argon, or carbon dioxide, more specifically, a nitrogen (N 2 ) gas. That is, the carbon-containing polymer of the carbon-containing polymer nanofiber can be converted to carbon nanofiber by being carbonized by heat treatment in an inert atmosphere.
  • the alkali metal precursor is activated as an alkali metal nanocatalyst, and the carbon source is bonded to the surface of the carbon nanofiber by the nanocatalyst to crystallize and grow into carbon nanotubes.
  • carbon nanofibers to which carbon nanotubes are bonded to the surface are prepared (S50).
  • carbon nanofibers are coated with a non-alkali metal catalyst such as iron (Fe), and carbon atoms start to dissolve in iron particles while passing carbon dioxide and other carbon-containing gases.
  • Fe iron
  • the process of forming a vertical tube of carbon atoms around carbon nanofibers was mainly based on the method in which carbon nanotubes were grown.
  • the iron particles remain in the carbon nanotubes, and eventually, there is a disadvantage that the acid treatment to remove the iron particles must be repeated several times.
  • the alkali metal of the alkali metal precursor is activated as a nanocatalyst, and the carbon source is crystallized into carbon nanotubes through this nanocatalyst so that it can be grown from the surface of the carbon nanofibers.
  • alkali metals of the alkali metal precursor cannot be activated or functionalized as a nano catalyst, and rather remain as impurities in some grown carbon nanotubes. As a result, the activity of the nanocatalyst is not stabilized, thereby hindering the growth of carbon nanotubes.
  • the heat treatment time condition if it is less than 15 minutes, it is insufficient time to induce the activation of the nanocatalyst, so it does not secure sufficient time for the carbon nanotubes to grow, and if it exceeds 30 minutes, the length of the grown carbon nanotubes It is preferable to heat treatment within 30 minutes because it becomes too long and it is difficult to achieve optimal physical properties and unnecessary side reactions may be generated.
  • the nanocatalyst is an alkali metal, in particular, sodium, which is an alkali metal of the alkali metal precursor applied in the present invention, is soluble in water, so there is no need to remove it using a separate acid, so metal-free carbon It is important to synthesize the nanotube-carbon nanofiber composite. That is, even if a part of the nanocatalyst remains in the carbon nanotube, there is an effect that it can be removed by dissolving it in general water rather than an acid treatment due to the high reactivity of the alkali metal cation.
  • the nanocatalyst can be simply vaporized or evaporated and removed by the heat treatment temperature of the fifth step, only pure carbon nanotubes can be grown from the surface of the carbon nanofibers.
  • high binding force between carbon nanofibers and carbon nanotubes is generated, and carbon nanofibers and carbon nanotubes are not separated, thereby binding carbon nanofibers and carbon nanotubes to each other. There is no need for a separate means to do this.
  • any one of a liquid type carbon source, a gaseous gas phase carbon source, and a solid type carbon source choose one or more to use.
  • the liquid phase carbon source is selected from the group consisting of ethanol (C 2 H 6 O), benzene (C 6 H 6 ), xylene, toluene (C 7 H 8 ), and mixtures thereof.
  • Gas phase carbon sources include methane (CH4), propylene (C3H6), propane (C 3 H 4 ), propane (C 3 H 8 ), butane (C 4 H 10 ), butylene (C 4 H 8 ) ), butadiene (C 4 H 6 ), ethylene (C 2 H 2 ) and mixtures thereof.
  • camphor C 10 H 16 O
  • monoterpene ketones may be used as a solid carbon source.
  • alkali metal precursors are activated as alkali metal nanocatalysts simply by heat treatment in the presence of a carbon source that helps the growth of carbon nanotubes without the need to separately prepare Group 1 elements other than hydrogen, especially sodium, as a catalyst in the form of particles,
  • the carbon source is crystallized into carbon nanotubes by the nanocatalyst, it can be grown from the surface of the carbon nanofibers, and eventually a carbon nanotube-carbon nanofiber composite in which the carbon nanotubes are bonded to the surface of the carbon nanofiber is manufactured.
  • the nanocatalyst may be vaporized and removed, so that the nanocatalyst is not attached or attached to the carbon nanotube grown on the carbon nanofiber. Therefore, there is no need to remove the nano-catalyst by performing a post-treatment process such as additional heat treatment or acid treatment. Even if a part of the nanocatalyst remains in the carbon nanotube, the advantages of the process are maintained because the alkali metal ion needs to be removed by dissolving it in general water rather than acid treatment due to the high reactivity to water.
  • Carbon-containing polymer nanofibers were heat-treated at 200°C for 40 minutes at a temperature increase rate of 10°C/min in the atmosphere, then heat-treated at 1,000°C for 60 minutes at a temperature increase rate of 5°C/min in an N 2 atmosphere, and then naturally cooled to carbonize Carbon nanofibers were prepared. This carbonization process was carried out using a heat treatment furnace as shown in the photo of the carbonization heat treatment furnace of FIG. 6 .
  • FIG. 7 showing a photo of a heat treatment furnace for growing carbon nanotubes on carbon nanofibers
  • a SUS pipe (diameter 5cm, length 20cm), which is a tube, was placed in the center of the furnace, and the temperature inside the SUS pipe was 700 It was maintained at °C, and the ethanol vapor generated while heating the ethanol using a heater was supplied to the inside of the SUS pipe through N 2 bubbling for 15 minutes so that carbon nanotubes were grown on the surface of the carbon nanofibers.
  • a carbon nanotube-carbon nanofiber composite was prepared.
  • Example 2 a spinning solution was prepared using sodium benzoate and other sodium bicarbonate of Example 1 as alkali metal precursors. That is, after dissolving sodium bicarbonate (Sigma Aldrich, BioXtra, > 99.5%) in DMF (Sigma Aldrich, for molecular biology, > 99%) solution at 0.02 mol/L, PAN (Sigma Aldrich, Mw 150,000 Typical) was added with 9 wt % ratio was dissolved again to prepare a spinning solution.
  • sodium bicarbonate Sigma Aldrich, BioXtra, > 99.5%
  • DMF Sigma Aldrich, for molecular biology, > 99%
  • PAN Sigma Aldrich, Mw 150,000 Typical
  • Carbon-containing polymer nanofibers were heat-treated at 200°C for 40 minutes at a temperature increase rate of 10°C/min in the atmosphere, then heat-treated at 1,000°C for 60 minutes at a temperature increase rate of 5°C/min in an N 2 atmosphere, and then naturally cooled to carbonize Carbon nanofibers were prepared. This carbonization process was carried out using the same heat treatment furnace shown in the photo of the carbonization heat treatment furnace of FIG. 6 mentioned in Example 1.
  • FIG. 7 showing a photo of a heat treatment furnace for growing carbon nanotubes on carbon nanofibers
  • a SUS pipe (diameter 5cm, length 20cm), which is a tube, was placed in the center of the furnace, and the temperature inside the SUS pipe was 700 It was maintained at °C, and the ethanol vapor generated while heating the ethanol using a heater was supplied to the inside of the SUS pipe through N 2 bubbling for 15 minutes so that carbon nanotubes were grown on the surface of the carbon nanofibers.
  • a carbon nanotube-carbon nanofiber composite was prepared.
  • FIGS. 8(a), 8(b) and 8(c) it is possible to confirm the crystallization and growth of carbon nanotubes on carbon nanofibers.
  • 9 is an SEM photograph of a carbon nanotube-carbon nanofiber composite prepared according to Example 2 of the present invention. It is possible to confirm the growth of the tube as it is combined.
  • 10 is an SEM photograph showing the length of carbon nanotubes grown on carbon nanofibers.
  • 10 (a) is a carbon nanotube-carbon nanofiber composite prepared when all the conditions in Example 1 are set the same, but heat-treated with only the carbon nanotube growth time of less than 5 minutes as an SEM photograph
  • Figure 10 (b) is a further enlarged SEM photograph of Figure 10 (a)
  • Figure 10 (c) is a further enlarged SEM photograph of Figure 10 (b)
  • the heat treatment time is less than 5 minutes carbon
  • 11 is a SEM photograph showing the density of carbon nanotubes grown on carbon nanofibers.
  • 11 (a) is a carbon nanotube-carbon nanofiber composite prepared when the concentration of sodium benzoate, which is an alkali metal precursor dissolved in DMF, is reduced to 1/5, except that all conditions in Example 1 are the same, SEM It is shown as a photograph, FIG. 11 (b) is an SEM photograph by further expanding FIG. 11 (a), and FIG. 11 (c) is an SEM photograph by further expanding FIG. It can be seen that it is possible to control the density of the carbon nanotubes grown from the surface of the carbon nanofibers according to the concentration of the alkali metal precursor.
  • the present invention relates to a method for producing a carbon nanotube-carbon nanofiber composite and a carbon nanotube-carbon nanofiber composite prepared thereby, by electrospinning a spinning solution in which a carbon-containing polymer is dissolved in an alkali metal precursor solution.
  • carbon nanofibers in which carbon-containing polymer nanofibers are carbonized through heat treatment are produced, and then heat-treated while supplying a carbon source to the carbon nanofibers to obtain alkali metal
  • the precursor is activated with an alkali metal nanocatalyst, and a carbon source is bonded to the surface of the carbon nanofiber by the nanocatalyst, and can be crystallized and grown into carbon nanotubes.
  • the present invention does not use a catalyst based on a non-alkali metal such as iron (Fe), cobalt (Co), or nickel (Ni), that is, a transition metal-based catalyst such as lithium (Li), potassium (K), especially sodium (Na). Since the alkali metal-based catalyst is used, catalyst particles such as sodium are simply dissolved in water and easily removed, so it is meaningful in that a metal-free carbon nanotube-carbon nanofiber composite can be synthesized. .
  • a non-alkali metal such as iron (Fe), cobalt (Co), or nickel (Ni)
  • a transition metal-based catalyst such as lithium (Li), potassium (K), especially sodium (Na). Since the alkali metal-based catalyst is used, catalyst particles such as sodium are simply dissolved in water and easily removed, so it is meaningful in that a metal-free carbon nanotube-carbon nanofiber composite can be synthesized. .
  • the present invention since there is no need for a cleaning process such as acid treatment to remove catalyst particles, washing water is unnecessary, thereby reducing environmental costs, and it is possible to easily grow carbon nanotubes from the surface of carbon nanofibers. , the carbon nanotube-carbon nanofiber composite can be mass-produced, so it is expected to be widely used in various energy application fields.

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Abstract

La présente invention concerne un procédé de préparation d'un composite de nanotubes de carbone- nanofibres de carbone et un composite de nanotubes de carbone-nanofibres de carbone ainsi préparé. L'objet de la présente invention concerne un procédé de préparation d'un composite de nanotubes de carbone- nanofibres de carbone et un composite de nanotubes de carbone- nanofibres de carbone ainsi préparé, le procédé comprenant : une première étape de dissolution d'un précurseur de métal alcalin dans un solvant pour préparer une solution de précurseur de métal alcalin ; une deuxième étape de dissolution d'un polymère contenant du carbone dans la solution de précurseur de métal alcalin pour préparer une solution de filage ; une troisième étape d'électrofilage de la solution de filage pour préparer des nanofibres polymères contenant du carbone ayant des surfaces auxquelles le précurseur de métal alcalin est lié ; une quatrième étape de traitement thermique des nanofibres de polymère contenant du carbone pour préparer des nanofibres de carbone ayant des surfaces auxquelles le précurseur de métal alcalin est lié ; et une cinquième étape de traitement thermique des nanofibres de carbone tandis qu'une source de carbone est fournie, de telle sorte que le précurseur de métal alcalin est activé en tant que nanocatalyseur de métal alcalin et la source de carbone est liée aux surfaces des nanofibres de carbone par le nanocatalyseur et cristallise et croît en nanotubes de carbone, ce qui permet de préparer des nanofibres de carbone ayant des surfaces auxquelles les nanotubes de carbone sont liés.
PCT/KR2020/001664 2020-02-04 2020-02-05 Procédé de préparation d'un composite de nanofibres de carbone- nanotubes de carbone et composite de nanofibres de carbone- nanotubes de carbone ainsi préparé WO2021157756A1 (fr)

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