Functionalized graphene comprising two or more amines and methods of making same
By chemically combining monovalent amine groups and divalent amine groups with carbon materials, functionalized graphene with amphiphilicity was prepared, which solved the problem of poor kneading and dispersibility with various solvents and resins in the prior art, and achieved excellent electrical, thermal and mechanical properties.
Patent Information
- Application Number
- CN202411662855.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2015-05-28
- Filing Date
- 2016-05-30
- Publication Date
- 2025-02-25
AI Technical Summary
In the prior art, functionalized graphene has poor kneading and dispersibility with various solvents and resins, making it difficult to achieve excellent electrical, thermal and mechanical properties.
By chemically combining monovalent amine groups and divalent or higher amine groups with carbon materials, functionalized graphenes with amphiphilicity (hydrophilic and hydrophobicity) are prepared, improving its interface binding force with thermoplastic polymers and promoting its uniform dispersion.
The excellent kneading and dispersion of functionalized graphene with various solvents and resins is achieved, and its electrical, thermal and mechanical properties are improved.
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Figure CN119503785A_ABST
Abstract
Description
[0001] This application is a divisional application of a Chinese patent application filed on May 30, 2016, with application number 201680030838.2 and invention name “Functionalized graphene containing two or more amines and preparation method thereof”. Technical Field
[0002] The present invention relates to functionalized graphene containing two or more amines and a preparation method thereof, and in particular to the following functionalized graphene containing two or more amines and a preparation method thereof: the functionalized graphene has good interface bonding force with a thermoplastic polymer to uniformly disperse the thermoplastic polymer so that the electrical properties, thermal properties and mechanical properties of the functionalized graphene become excellent. Background Art
[0003] Pencil leads commonly seen in daily life are made of inexpensive graphite. Graphite is made of two-dimensional sheets of carbon crystals stacked one on top of another, with atoms in each sheet connected in a hexagonal honeycomb-like shape. One layer of graphite is called graphene. Graphene is a material that has both metallic and non-metallic properties. Graphene has a tensile strength 311 times that of steel, an electron mobility 1000 times that of silicon, and a thermal conductivity 10 times that of copper. Graphene is transparent enough to allow 98% of light to pass through it, and has the property of maintaining its characteristics even when bent or stretched. Due to these properties, graphene can be applied to a variety of fields, such as nanomaterials, inks, protective materials, heat dissipation materials, ultra-light materials, energy electrode materials, next-generation semiconductors, transparent electrodes, etc.
[0004] The graphene may be reduced graphene oxide (RGO) produced by acid-treating graphite to produce graphene oxide (GO) and then reducing the graphene oxide (GO). Recently, there is a trend to develop functionalized graphene by using graphene oxide and various functional reagents finally having an amine.
[0005] Typically, functionalized graphene can be obtained by Figure 2 Structural formula 1 indicates that the functionalized graphene is prepared by using a monovalent amine (monoamine) alone or a divalent amine (diamine) alone.
[0006] When a monovalent amine is used alone to prepare functionalized graphene, it can be seen from the following reaction formula 1 that because the reaction of the amine group with the functional group is on the surface of graphene oxide, the amine functional group is not combined with the surface of graphene, and alkylation occurs on the surface of graphene, thereby forming carbon chains such as linear, cyclic and aromatic chains on the surface of graphene. The introduction of amines makes it difficult to apply to hydrophobic solvents or polymer resins. In other words, this method has limited application.
[0007] [Reaction 1]
[0008]
[0009] Furthermore, when functionalized graphene is prepared by using a single divalent amine such as ethylenediamine (EDA), there are certain difficulties: an increase in processing steps due to the inevitable use of a catalyst and the need to pretreat graphene oxide, high production costs due to the use of a catalyst, and agglomerates generated during a reduction process using a reducing agent due to a reduction step performed after functionalizing graphene oxide.
[0010] Functionalized graphene using only one amine is known (Polymer (Korea) Vol. 35, No. 3, pp 265-271, 2011) (J. Mater. Chem. A, 2013) (Korean Patent Application No. 10-2010-7016175). However, the known functionalized graphene has poor kneading and dispersibility with various solvents and resins, so there is a problem that a specific solvent and a specific resin must be used.
[0011] Therefore, even if it has been applied to various solvents and resins, graphene having excellent kneading properties and dispersibility is required. Summary of the invention
[0012] Technical issues
[0013] Therefore, an object of the present invention is to provide a functionalized graphene having two or more amines and having both hydrophilicity and hydrophobicity, which has good kneadability and dispersibility with respect to various solvents and resins.
[0014] Technical Solution
[0015] To achieve these objectives, the present invention provides functionalized graphene with amine groups, comprising: a carbon material selected from the group consisting of graphene, reduced graphene, oxidized graphene and mixtures thereof; and a monovalent amine group and a divalent or higher valent amine group bound to the carbon material.
[0016] Further, the present invention provides a method for preparing functionalized graphene, comprising the following steps: mixing a carbon material and a first solvent to prepare a carbon material dispersion, wherein the carbon material is selected from the group consisting of graphene, reduced graphene, graphene oxide and a mixture thereof; adding an amine solution to the carbon material dispersion, in which a first amine compound having a monovalent amine group, a second amine compound having a divalent or higher valent amine group and a second solvent are mixed to chemically combine the amine group with the carbon material.
[0017] Technical Effects
[0018] According to the present invention, two or more amines have been applied to the functionalized graphene so that the functionalized graphene has hydrophilicity and hydrophobicity, and thus the functionalized graphene has excellent kneadability with various solvents and resins. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 1 and 2 are diagrams illustrating a preparation example of functionalized graphene according to the present invention (a) and products prepared using the functionalized graphene (b, c).
[0020] Figure 2 is the structure of the functionalized graphene of the present invention. DETAILED DESCRIPTION
[0021] Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.
[0022] The functionalized graphene according to the present invention has amphiphilicity, ie, hydrophilicity and hydrophobicity, and thus has excellent kneadability with various solvents and resins. The functionalized graphene further includes a carbon material and an amine group.
[0023] The carbon material is excellent in electrical conductivity, thermal conductivity, dispersibility and compatibility, and is selected from the group consisting of graphene, reduced graphene oxide (rGO), graphene oxide (GO), a mixture thereof and the like.
[0024] The amino group is chemically combined with the carbon material to improve the interfacial bonding strength with the thermoplastic polymer resin, thereby inducing uniform dispersion of the thermoplastic polymer resin, thereby improving the electrical properties, thermal properties and mechanical properties of the carbon material. The amine group includes a monovalent amine (monoamine) group and a divalent or higher amine (diamine or higher amine) group. In particular, the monovalent amine group and the divalent or higher amine group are combined at different positions of the carbon material.
[0025] The monovalent amine group may have an amine group and 1 to 40 carbon atoms, more particularly 2 to 25 carbon atoms, and most particularly 3 to 18 carbon atoms. For example, the monovalent amine group is an aliphatic monovalent amine group having 1 to 40 carbon atoms, particularly 2 to 25 carbon atoms, and more particularly 3 to 18 carbon atoms. For example, the monovalent amine group may be selected from the group consisting of a chain alkylamine group having 3 to 18 carbon atoms, a cycloalkylamine group having 6 to 15 carbon atoms, or an aromatic alkylamine group. More particularly, the monovalent amine group is a chain alkylamine group having 3 to 18 carbon atoms. Examples include n-butylamine Cyclohexylamine n-Hexylamine Phenylpropylamine Phenylbutylamine Octadecanamine Dodecylamine In the above-exemplified amine compounds, one hydrogen atom of the amine compound is replaced to form a monovalent amine group. The monovalent amine group has only one amine group in the molecule, and the only one amine group is chemically bonded to the carbon material.
[0026] The divalent or higher valent amine group includes 2 or more amine groups, and particularly includes 2 to 4 amine groups. For example, the divalent or higher valent amine group may have 2 or more amine groups and 1 to 40 carbon atoms, more particularly 2 to 25 carbon atoms, and most particularly 3 to 15 carbon atoms. For example, the divalent or higher valent amine group is an aliphatic divalent or higher valent amine group having 1 to 40 carbon atoms, more particularly 2 to 25 carbon atoms, and most particularly 3 to 15 carbon atoms. In particular, the divalent or higher valent amine group may be selected from the group consisting of a chain alkylamine group having 3 to 15 carbon atoms, a cycloalkylamine group having 6 to 15 carbon atoms, or an aromatic alkylamine group. More particularly, the divalent or higher valent amine group is a cycloalkylamine group having 6 to 15 carbon atoms. Examples include n-diaminocyclohexane n-Diaminobutane Hexamethylenediamine p-phenylenediamine Ethylenediamine Diaminododecane 3,4-Dimethyl-benzene-1,2-diamine In the above-exemplified amine compounds, one hydrogen atom of the amine compound is replaced to form a divalent or higher valent amine group. The divalent or higher valent amine group has only two or more amine groups in the molecule, one amine group is chemically bonded to the carbon material, and the other amine groups are not chemically bonded to the carbon material.
[0027] The molar ratio of the monovalent amine groups to the divalent or higher valent amine groups bonded to the carbon material is 1:9 to 9:1, particularly 1:4 to 4:1. If the molar ratio of the monovalent amine groups is too high, the distribution of the hydrophobic alkyl chains on the surface of the functionalized graphene increases, which weakens the interfacial bonding force with the hydrophilic solvent, making it difficult to disperse uniformly in the solvent. If the molar ratio of the divalent or higher valent amine groups is too high, the reaction of the divalent amine before the graphene functionalization reaction will produce side reactions (impurities) and reduce the electrical characteristics, or the binding between the amine groups present in the functionalized graphene will lead to the formation of large aggregates and reduce the dispersibility. In addition, since the monovalent amine groups and the divalent or higher valent amine groups are bonded to the carbon material at different positions, the present invention can be applied regardless of the wide polarity of the solvent.
[0028] The amount of the carbon material may be 85 to 99.9 wt %, particularly 90 to 99.9 wt %, and the amount of the amine group bonded to the carbon material may be 0.1 to 15 wt %, particularly 0.1 to 10 wt %. In terms of the amount of carbon and nitrogen components, the amount of the carbon component is 85 to 99.9 wt %, particularly 90 to 99.9 wt %, and the amount of the nitrogen component is 0.1 to 15 wt %, particularly 0.1 to 10 wt %, relative to the entire functionalized graphene. If the amount of the carbon material is too little, the graphene properties may not be imparted, and if the amount of the carbon material is too much, the dispersibility and kneading properties may be poor. If the amount of the amine group is too low, aggregation may occur due to the reduced dispersibility of the functionalized graphene, which may cause the performance degradation of the coating solution. If the amount of the amine group is too high, the hydrophilicity of the functionalized graphene increases, and it is difficult to disperse uniformly in a hydrophobic solvent. Here, the kneadability means that the fluidity of the thermoplastic polymer resin melted at an elevated temperature is improved by a shear force, and at the same time, the filler and the polymer resin are mixed to be uniformly dispersed in the thermoplastic polymer resin.
[0029] If necessary, the functionalized graphene according to the present invention can control the hydrophilicity and hydrophobicity by controlling the molar ratio of the amine groups chemically bonded to the carbon material. For example, in the above monovalent amine groups and divalent or higher valent amine groups, when the molar ratio of the monovalent amine groups is high, in particular, when the molar ratio of the monovalent amine groups to the divalent or higher valent amine groups is 6:4 to 9:1, more particularly 7:3 to 9:1, the hydrophobicity can be improved. On the contrary, in the above monovalent amine groups and divalent or higher valent amine groups, when the molar ratio of the divalent or higher valent amine groups is high, in particular, when the molar ratio is 4:6 to 1:9, more particularly 3:7 to 1:9, the hydrophilicity can be improved.
[0030] Functionalized graphene according to the present invention may further contain impurities other than carbon materials and amine groups generated during the manufacturing process. Impurities may be, for example, unreduced oxygen (O) in graphene oxide, or defects in the manufacturing process of graphene oxide and oxygen (O) in the atmosphere, or carboxyl groups (-COOH), hydroxyl groups (-OH), oxygen (O2) and mixtures thereof that may be generated by the influence of gases during reactions in the atmosphere and errors in analysis.
[0031] When impurities are included, the amount of carbon material (or carbon component) in the functionalized graphene according to the present invention can be 74.9-97.89wt%, especially 81.7-97.7wt%, the amount of amine group (or nitrogen component) can be 0.1-15wt%, especially 0.1-10wt%, the amount of oxygen (O) component can be 1-10wt%, especially 2-8wt%. The amount of other impurities (such as -COOH, -OH, O2, etc.) can be 0.001-0.1wt%, especially 0.001-0.05wt%.
[0032] The functionalized graphene according to the present invention may have Figure 2 The structures represented by structural formulas 2 and 3.
[0033] like Figure 2 As shown in structural formula 2, the functionalized graphene has a structure of a butylamine group (n-butylamine, a monovalent amine group) and a 3-aminohexylamine group (cyclohexanediamine, a divalent amine group) chemically bonded to a carbon material.
[0034] like Figure 2 As shown in structural formula 3, the functionalized graphene has a cyclohexylamine group (monovalent amine group) and a 4-aminobutylamine group (diaminobutylamine, divalent amine group) chemically bonded to the carbon material.
[0035] In order to produce functionalized graphene according to the present invention, an amine solution (amine functionalized solution) is first prepared. The amine solution comprises a first amine compound, a second amine compound and a solvent. The first amine compound includes a monovalent amine, in particular a monovalent amine having 1 to 40 carbon atoms, more particularly a monovalent amine having 2 to 25 carbon atoms, and most particularly a monovalent amine having 3 to 18 carbon atoms. The second amine compound includes a divalent or higher valent amine, in particular a divalent or higher valent amine having 1 to 40 carbon atoms, more particularly a divalent or higher valent amine having 2 to 25 carbon atoms, and most particularly a divalent or higher valent amine having 3 to 15 carbon atoms. Relative to the total amount of the amine solution, the amount of the first amine compound and the second amine compound is 0.01 to 5 wt%, in particular 0.1 to 3 wt%, and the ratio of the first amine compound to the second amine compound is 1:9 to 9:1. If the amount of the first amine compound and the second amine compound is outside the above range, the production efficiency of the amine solution may decrease.
[0036] The solvent is used to dissolve the first amine compound and the second amine compound, and can be one or more selected from the group consisting of ethanol, isopropanol, methanol, distilled water, n-butanol and mixtures thereof. The amount of the solvent to be used is not particularly limited and can be set as required, for example, it can be 95 to 99.99wt%, particularly 97 to 99.9wt% relative to the entire amine solution. If the amount of the solvent used is too small, the first amine compound and the second amine compound may not be fully dissolved. If the amount is too large, the production efficiency of the amine solution may decrease.
[0037] Next, a carbon material and a solvent are mixed to prepare a carbon material dispersion, wherein the carbon material is selected from the group consisting of graphene, reduced graphene, graphene oxide, and mixtures thereof. The amount of the carbon material is 0.1 to 30 wt%, particularly 1 to 20 wt%, relative to the entire carbon material dispersion. If the amount of the carbon material is outside the above range, graphene properties may not be imparted, or the carbon material may not be dissolved. The solvent is used to dissolve the carbon material so that there is no restriction as long as the carbon material can be dissolved. For example, as a solvent, one or more solvents selected from the group consisting of distilled water, isopropanol, methanol, ethanol, and mixtures thereof may be used, and in particular, distilled water may be used. The amount of the solvent to be used is not particularly limited and may be set as desired, for example, it may be 70 to 99.9 wt%, particularly 80 to 99 wt%, relative to the entire carbon material dispersion. If the amount of the solvent is too little, the carbon material may not be fully dissolved, and if the amount is too much, the production efficiency of the mixed solution may decrease.
[0038] Next, an amine solution is added to the carbon material dispersion, and then the mixture is stirred at a temperature of 70 to 120° C., particularly at a temperature of 80 to 110° C., and more particularly at a temperature of 85 to 105° C. for 12 to 36 hours, especially for 20 to 30 hours. Thereafter, the solvent and the amine compound not bound to the carbon material in the mixture are removed using a conventionally available method (e.g., a method using a vacuum filtration kit, etc.), and dried (e.g., freeze-dried at -80° C. for more than 10 hours) to produce functionalized graphene in which an amine group is bound to (e.g., chemically bound to) the carbon material. The amount of the amine solution added is 5 to 20 parts by weight, particularly 7 to 15 parts by weight, relative to 100 parts by weight of the carbon material dispersion. If the amount of the amine solution added is outside the above range, the amine substance may not be sufficiently bound to the carbon material, and the hydrophilicity may be poor.
[0039] The functionalized graphene according to the present invention can control the desired degree of hydrophobicity and hydrophilicity by controlling the amount of amine solution added.
[0040] Figure 1 1 is a diagram illustrating a preparation example (a) of functionalized graphene according to the present invention and a product (b, c) prepared using the functionalized graphene. Figure 1As shown, the functionalized graphene according to the present invention can be used for graphene ink compositions, graphene dispersions comprising functionalized graphene and solvents, graphene coating solutions or polymer composites, etc. In addition, the functionalized graphene according to the present invention can be applied to fillers for electrostatic discharge (ESD), electromagnetic interference (EMI) shielding, thermal radiation (heat conduction), and materials for secondary battery electrodes through the above examples. Coating solutions and ink compositions are similar in composition, but can differ according to their application and viscosity. For example, when the functionalized graphene is intended to be coated on a film, etc., the functionalized graphene is manufactured in the form of a coating solution, and when high viscosity is required and the functionalized graphene is intended to be used for printing, the functionalized graphene is manufactured in the form of an ink composition.
[0041] Functionalized graphene can be extruded with thermoplastic polymers or mixed with thermosetting resins to be used as fillers in graphene composite composites, such as fillers that can be used for ESD protection, EMI shielding, or heat dissipation (thermal conduction).
[0042] When using functionalized graphene to prepare graphene dispersion, graphene dispersion may further include solvent. In this case, the amount of functionalized graphene is 0.01-30wt%, and the amount of solvent is 70-99.99wt%. When functionalized graphene and solvent are included in the above range, the dispersion effect is more excellent. When the amount of functionalized graphene is too little, the characteristics (conductivity and heat dissipation) of graphene may not be achieved, and when the amount is too much, the values of viscosity and thixotropic index (TI) may be higher, so that the dispersibility and fluidity of the composition used for carbon material dispersion may be lower.
[0043] When functionalized graphene is used to prepare a coating solution or ink composition, a binder and a solvent may be further added. In such a case, the amount of functionalized graphene is 0.01 to 30 wt%, the amount of binder is 0.01 to 10 wt%, and the amount of solvent is 60 to 99.98 wt%. When the above components are within the above range, the dispersibility of graphene is excellent so that electrical conductivity and thermal conductivity are excellent. When the amount of functionalized graphene and binder is too small, it may be difficult to achieve the characteristics of graphene, and when the amount is too much, the dispersibility and fluidity may be low.
[0044] As the adhesive, a conventional adhesive may be used, for example, a polyurethane adhesive, an acrylic adhesive, a polyester adhesive, an epoxy resin adhesive, a polyethylene adhesive, an ethylene vinyl acetate adhesive, a melamine adhesive, and a mixture thereof.
[0045] The solvent is used to dissolve the carbon material and the dispersant of the carbon material, and can be one or more solvents selected from alcohols (such as methanol, ethanol, isopropanol, etc.), ketones (such as methyl ethyl ketone (MEK) and methyl isobutyl ketone (MIBK), etc.), pyrrolidinone (such as N-methylpyrrolidone (NMP), etc.), esters (such as ethyl acetate, etc.), aromatic esters (such as benzyl acetate, etc.), linear and / or branched hydrocarbons (such as dimethoxyethane and 1-chlorobutane, etc.), glycol ethers (cellosolves) (such as ethyl cellosolve acetate, butyl cellosolve acetate (BCA), etc.), water (H2O) and mixtures thereof.
[0046] In order to further improve the coating conditions, etc., the coating solution or ink composition may further contain 0.001 to 10 wt % of a dispersant. Examples of the dispersant include hydroxycarboxylic acid esters, acrylate copolymers, modified polyethers, mixtures thereof, and the like.
[0047] When functionalized graphene is used to prepare a polymer composite composition, a thermoplastic resin or a thermosetting resin may be included. In this case, the amount of functionalized graphene is 0.5 to 70wt%, particularly 0.5 to 75wt%, and the amount of thermoplastic resin or thermosetting resin is 30 to 99.5wt%, particularly 25 to 99.5wt%. Within this range, the dispersibility is excellent, and the electrical properties and thermal conductivity are more excellent. If the amount of graphene is too little, the properties of graphene (conductivity and heat dissipation) cannot be achieved. If the amount of graphene is too much, the viscosity or melt flow index (MFI) is high, so that the dispersibility and fluidity of the composition deteriorate, which is uneconomical.
[0048] As the thermoplastic resin, commonly used resins can be used, for example, polypropylene (PP), polyethylene (PE), ABS (acrylonitrile-butadiene-styrene resin), polyoxymethylene (POM), polycarbonate (PC), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), polyetherimide (PEI), polyetheretherketone (PEEK), liquid crystal polymer (LCP), nylon, PA6, thermoplastic elastomer (TPE), etc. As the thermosetting resin, commonly used resins can be used. For example, epoxy resins, phenolic resins, urea resins, etc. can be used.
[0049] The polymer composite may further include a lubricant and / or a dispersant for controlling the fluidity of the thermoplastic resin and the resin during extrusion. For example, when a thermosetting resin is used as the resin, a dispersant may be further included, and when a thermoplastic resin is used, a lubricant may be further included. The amount of the lubricant and / or the dispersant is 0.01 to 5 weight percent, respectively. Examples of lubricants include ester waxes, acidic polyester-based lubricants, stearamide-based lubricants, silicone-acryl lubricants, siloxane-based lubricants, and mixtures thereof, and examples of dispersants include hydroxycarboxylates, acrylate copolymers, modified polyethers, and mixtures thereof.
[0050] Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples.
[0051] [Preparation Example 1] Preparation of reduced graphene
[0052] 0.5 wt% of graphene oxide (GO) and 99.5 wt% of distilled water were mixed, and 1 part by weight of ascorbic acid (from Alfa Assar) was added thereto. After that, the temperature of the reactor was raised to 90°C, and centrifugation (reduction) was performed for 10 hours. Next, the residue was removed using a vacuum filtration kit, and washing with methanol was repeated 5 times to prepare reduced graphene (rGO).
[0053] [Example 1] Preparation of functionalized graphene
[0054] 1wt% of the reduced graphene prepared in Preparation Example 1 and 99wt% of distilled water were mixed to prepare a carbon material dispersion. 0.05w% of n-butylamine, 0.05wt% of cyclohexyldiamine and 99.9wt% of methanol were uniformly mixed at room temperature to prepare an amine solution. Based on 100 parts by weight of the carbon material dispersion, 10 parts by weight of the amine solution were added to the carbon material dispersion. The mixture solution in which the carbon material dispersion and the amine solution were mixed was stirred at 80°C for 24 hours. Afterwards, the mixture solution was passed through a vacuum filtration kit to remove the solvent and the remaining amine compound, and then washed 5 times with a solvent mixed with methanol and distilled water in a weight ratio of 8:2, and dried in a vacuum oven to prepare functionalized graphene.
[0055] [Example 2] Preparation of functionalized graphene
[0056] Functionalized graphene was prepared in the same manner as in Example 1, except that 0.05 wt % of n-butylamine and 0.05 wt % of cyclohexyldiamine were replaced with 0.025 wt % of n-butylamine and 0.075 wt % of cyclohexyldiamine in the amine solution.
[0057] [Example 3] Preparation of functionalized graphene
[0058] Functionalized graphene was prepared in the same manner as in Example 1, except that 0.05 wt % of n-butylamine and 0.05 wt % of cyclohexyldiamine were replaced with 0.075 wt % of n-butylamine and 0.025 wt % of cyclohexyldiamine in the amine solution.
[0059] [Example 4] Preparation of functionalized graphene
[0060] Functionalized graphene was prepared in the same manner as in Example 1, except that 0.05 wt % of n-butylamine and 0.05 wt % of cyclohexyldiamine were used in the amine solution instead of 0.05 wt % of cyclohexylamine and 0.05 wt % of cyclohexyldiamine.
[0061] [Example 5] Preparation of functionalized graphene
[0062] Functionalized graphene was prepared in the same manner as Example 1, except that 0.05 wt % of n-butylamine and 0.05 wt % of cyclohexyldiamine were replaced with 0.025 wt % of cyclohexylamine and 0.075 wt % of cyclohexyldiamine in the amine solution.
[0063] [Example 6] Preparation of functionalized graphene
[0064] Functionalized graphene was prepared in the same manner as in Example 1, except that 0.05 wt % of n-butylamine and 0.05 wt % of cyclohexyldiamine were replaced with 0.075 wt % of cyclohexylamine and 0.025 wt % of cyclohexyldiamine in the amine solution.
[0065] [Example 7] Preparation of functionalized graphene
[0066] Functionalized graphene was prepared in the same manner as in Example 1, except that 0.05 wt % of n-butylamine and 0.05 wt % of cyclohexyldiamine were replaced with 0.05 wt % of cyclohexylamine and 0.05 wt % of diaminobutane in the amine solution.
[0067] [Example 8] Preparation of functionalized graphene
[0068] Functionalized graphene was prepared in the same manner as in Example 1, except that 0.05 wt % of n-butylamine and 0.05 wt % of cyclohexyldiamine were replaced with 0.025 wt % of cyclohexylamine and 0.075 wt % of diaminobutane in the amine solution.
[0069] [Example 9] Preparation of functionalized graphene
[0070] Functionalized graphene was prepared in the same manner as in Example 1, except that 0.05 wt % of n-butylamine and 0.05 wt % of cyclohexyldiamine were replaced with 0.075 wt % of cyclohexylamine and 0.025 wt % of diaminobutane in the amine solution.
[0071] [Example 10] Preparation of functionalized graphene
[0072] Functionalized graphene was prepared in the same manner as in Example 1, except that 0.05 wt % of n-butylamine and 0.05 wt % of diaminobutane were used in the amine solution to replace 0.05 wt % of n-butylamine and 0.05 wt % of cyclohexyldiamine.
[0073] [Example 11] Preparation of functionalized graphene
[0074] Functionalized graphene was prepared in the same manner as Example 1, except that 0.05 wt % of n-butylamine and 0.05 wt % of cyclohexyldiamine were replaced with 0.025 wt % of n-butylamine and 0.075 wt % of diaminobutane in the amine solution.
[0075] [Example 12] Preparation of functionalized graphene
[0076] Functionalized graphene was prepared in the same manner as Example 1, except that 0.05 wt % of n-butylamine and 0.05 wt % of cyclohexyldiamine were replaced with 0.075 wt % of n-butylamine and 0.025 wt % of diaminobutane in the amine solution.
[0077] [Example 13] Preparation of functionalized graphene
[0078] Functionalized graphene was prepared in the same manner as in Example 1, except that 0.05 wt % of n-butylamine and 0.05 wt % of cyclohexyldiamine were replaced with 0.05 wt % of n-butylamine and 0.05 wt % of 1,4-phenylenediamine in the amine solution.
[0079] [Example 14] Preparation of functionalized graphene
[0080] Functionalized graphene was prepared in the same manner as in Example 1, except that 0.05 wt % of n-butylamine and 0.05 wt % of cyclohexyldiamine were replaced with 0.05 wt % of n-butylamine and 0.05 wt % of 3,4-dimethyl-benzene-1,2-diamine in the amine solution.
[0081] [Example 15] Preparation of functionalized graphene
[0082] Functionalized graphene was prepared in the same manner as in Example 1, except that 0.05 wt % of n-butylamine and 0.05 wt % of cyclohexyldiamine were replaced with 0.05 wt % of n-butylamine and 0.05 wt % of 1,3-cyclohexanebis(methylamine) in the amine solution.
[0083] [Comparative Example 1] Preparation of functionalized graphene
[0084] 2 wt % of the reduced graphene prepared in Preparation Example 1 and 98 wt % of distilled water were mixed to prepare a carbon material dispersion. The carbon material dispersion was stirred at 80° C. for 24 hours. Thereafter, the carbon material dispersion was passed through a vacuum filtration kit to remove the solvent, and then washed 5 times with a solvent mixed with methanol and distilled water at a weight ratio of 8:2, and dried in a vacuum oven to prepare functionalized graphene.
[0085] [Comparative Example 2] Preparation of functionalized graphene
[0086] 2 wt % of the reduced graphene prepared in Preparation Example 1 and 98 wt % of distilled water were mixed to prepare a carbon material dispersion. 0.1 w % of n-butylamine and 99.9 wt % of methanol were uniformly mixed at room temperature to prepare an amine solution. Based on 100 parts by weight of the carbon material dispersion, 10 parts by weight of the amine solution were added to the carbon material dispersion. The mixture solution was stirred at 80 ° C for 24 hours. Afterwards, the mixture solution was passed through a vacuum filtration kit to remove the solvent and the remaining amine compound, and then washed 5 times with a solvent mixed with methanol and distilled water in a weight ratio of 8: 2, and dried in a vacuum oven to prepare functionalized graphene.
[0087] [Comparative Example 3] Preparation of functionalized graphene
[0088] Functionalized graphene was prepared in the same manner as Comparative Example 2, except that cyclohexylamine was used instead of n-butylamine.
[0089] [Comparative Example 4] Preparation of functionalized graphene
[0090] Functionalized graphene was prepared in the same manner as Comparative Example 2, except that octadecylamine was used instead of n-butylamine.
[0091] [Comparative Example 5] Preparation of functionalized graphene
[0092] Functionalized graphene was prepared in the same manner as Comparative Example 2, except that diaminobutane was used instead of n-butylamine.
[0093] [Comparative Example 6] Preparation of functionalized graphene
[0094] Functionalized graphene was prepared in the same manner as in Comparative Example 2, except that cyclohexyldiamine was used instead of n-butylamine.
[0095] [Comparative Example 7] Preparation of functionalized graphene
[0096] Functionalized graphene was prepared in the same manner as in Comparative Example 2, except that octadecyldiamine was used instead of n-butylamine.
[0097] [Comparative Example 8] Preparation of functionalized graphene
[0098] Functionalized graphene was prepared in the same manner as Comparative Example 2, except that 1,4-phenylenediamine was used instead of n-butylamine.
[0099] [Comparative Example 9] Preparation of functionalized graphene
[0100] Functionalized graphene was prepared in the same manner as in Comparative Example 2, except that 3,4-dimethyl-benzene-1,2-diamine was used instead of n-butylamine.
[0101] [Comparative Example 10] Preparation of functionalized graphene
[0102] Functionalized graphene was prepared in the same manner as in Comparative Example 2, except that 1,3-cyclohexanebis(methylamine) was used instead of n-butylamine.
[0103] [Comparative Example 11] Preparation of functionalized graphene
[0104] Functionalized graphene was prepared in the same manner as Comparative Example 2, except that 0.05 wt % of n-butylamine and 0.05 wt % of cyclohexylamine were used instead of n-butylamine.
[0105] [Comparative Example 12] Preparation of functionalized graphene
[0106] Functionalized graphene was prepared in the same manner as Comparative Example 2, except that 0.05 wt % of diaminobutane and 0.05 wt % of cyclohexyldiamine were used instead of n-butylamine.
[0107] [Experimental Example 1] Evaluation of the electrical properties of functionalized graphene
[0108] 0.5 wt % of functionalized graphene, 94.5 wt % of methanol and 5 wt % of polyester resin (COO Chemical Co., Ltd) prepared in each of Examples 1 to 15 and Comparative Examples 1 to 12 were mixed and stirred for 30 minutes to generate a mixture solution. Ceramic beads were added to the prepared mixed solution and dispersed with an oscillator (DAS200) to prepare a dispersion. The dispersion was coated on a polyethylene terephthalate (PET) film using an automatic film applicator. The film was placed in a hot air oven set at a temperature of 100° C. for 3 minutes for drying, and the sheet resistivity of the dried film was measured using a 4-point probe. The results are shown in Table 1 below.
[0109] [Table 1]
[0110]
[0111]
[0112] As shown in Table 1 above, the sheet resistivity of the functionalized graphene prepared by adding the amine compound was measured to be lower than that of the graphene without the amine compound. Even when the amine compound was added, when both the monovalent amine and the divalent amine were included, the sheet resistivity was measured to be lower. In particular, when both the monovalent linear amine and the divalent cyclic amine group (e.g., cyclic amine group) were included (0.05 wt% of n-butylamine and 0.05 wt% of cyclohexyldiamine in Example 1), the sheet resistivity was the lowest.
[0113] [Experimental Example 2] Confirmation of graphene functionality
[0114] The functionalized graphene prepared in Examples 1 to 3 and Comparative Examples 1, 2 and 6 was analyzed by XPS (X-ray photoelectron spectroscopy, VG Microtech ESCA2000), and the results are shown in Table 2 below, where the N1S peak was observed, thereby confirming the functionalization of the functionalized graphene. Here, by using C1S, O1S and N1S, the type of each structure and bond in the functionalized graphene can be known. In this case, due to the influence of the atmosphere or external environment at the time of measurement, the N1S peak can be obtained even if amine is not included (in the case of Comparative Example 1, etc.). When N1S is 0.001 to 0.1%, it can be considered that the graphene is non-functionalized.
[0115] [Table 2]
[0116] Amine solution C1S O1S N1S Example 1 n-Butylamine (0.05wt%) + Cyclohexyldiamine (0.05wt%) 90.67 8.75 0.58 Example 2 n-Butylamine (0.025wt%) + cyclohexyldiamine (0.075wt%) 90.88 8.39 0.73 Example 3 n-Butylamine (0.075wt%) + cyclohexyldiamine (0.025wt%) 90.2 9.37 0.43 Comparative Example 1 Dispersible without adding functional agents 89.25 10.749 0.001 Comparative Example 2 n-Butylamine (0.1wt%) 89.75 9.37 0.88 Comparative Example 6 Cyclohexyl diamine (0.1 wt%) 87.245 12.476 0.279
[0117] [Experimental Example 3] Evaluation of the dispersibility of functionalized graphene
[0118] 99.5 wt % of distilled water, alcohol and solvent (dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP), propylene glycol monomethyl ether acetate (PGMEA), cyclohexene) were added to 0.5 wt % of functionalized graphene prepared in Examples 1 to 15 and Comparative Examples 1 to 12, respectively, and stirred for 30 minutes to prepare a mixture solution. Ceramic beads were mixed with each of the prepared mixture solutions and dispersed using an oscillator (DAS 200) for 80 minutes to prepare a dispersion. The dispersion was poured into each vial of 10 ml, and it was checked whether the powder was precipitated when 1 hour, 24 hours and 168 hours had passed. The results are shown in Tables 3 and 4 below, where the degree of precipitation is represented by the symbols ◎, ○, △ and X, which are represented as increasing in order to the right.
[0119] [Table 3]
[0120]
[0121]
[0122] [Table 4]
[0123]
[0124]
[0125]
[0126] As shown in Tables 3 and 4, it can be seen that when the monovalent amine group and the divalent amine group are used simultaneously (Examples 1 to 15), the dispersibility of various solvents is excellent compared with the functionalized graphene containing or not containing the monovalent amine group and the divalent amine group alone (Comparative Examples 1 to 10). In particular, even when containing two monovalent amine groups or two divalent amine groups (Comparative Examples 11 and 12), the functionalized graphene containing a monovalent amine group having a relatively small number of carbon atoms and a divalent amine group having a ring structure having a relatively large number of carbon atoms (Examples 1 and 2) has the most excellent dispersion uniformity and dispersion stability.
[0127] [Experimental Example 4] Evaluation of functionalized graphene thermoplastic resin composites
[0128] 3% of the functionalized graphene prepared in Example 1 and the non-functionalized graphene prepared in Example 1 and Comparative Examples 1 to 3 were each mixed with 97% of polyethylene terephthalate (manufactured by Samyang Corporation) in a mixing oscillator for 20 minutes, and the mixture was extruded using a twin-screw extruder (manufactured by Bautek, Ba19), and made into pellets using a pelletizer (cutting the linear composite material into pellet form). The prepared pellets were melted at 260°C using a hot press and made into test specimens in a 60×60mm×1.5T mold, and the electrical properties of the test specimens were measured using a 4-point probe, and the thermal conductivity was measured using a thermal conductivity meter (TPS500S, HOT DISK). The results are shown in Table 5 below.
[0129] [Table 5]
[0130] Sheet resistivity (Ω / sq) Thermal conductivity (W / mK) Comparative Example 1 <![CDATA[10 13 ]]> 1.0 Comparative Example 2 <![CDATA[10 10 ]]> 1.1 Comparative Example 3 <![CDATA[10 8.5 ]]> 1.4 Example 1 <![CDATA[10 8 ]]> 1.5
[0131] As shown in Table 5, it can be seen that the dispersion uniformity of the thermoplastic resin is excellent, and when the monovalent amine group and the divalent amine group are applied simultaneously (Example 1), the electrical characteristics and thermal conductivity are excellent compared to the functionalized graphene containing or not containing a monovalent or divalent amine group alone (Examples 1 to 3).
Claims
1. A functionalized graphene having an amine group, comprising: A carbon material selected from the group consisting of graphene, reduced graphene, graphene oxide, and mixtures thereof; as well as a monovalent amine group and a divalent or higher valent amine group bonded to the carbon material; Furthermore, the molar ratio of the monovalent amine group to the divalent or higher valent amine group is 1:9 to 9:
1.
2. The functionalized graphene according to claim 1, wherein The amount of the carbon material is 85-99.9 wt %, and the amount of the amine group is 0.1-15 wt %.
3. The functionalized graphene according to claim 1, wherein The monovalent amine group and the divalent or higher valent amine group are bonded to different positions of the carbon material.
4. The functionalized graphene according to claim 1, wherein The monovalent amine group is a monovalent amine having 1 to 40 carbon atoms, and the divalent or higher valent amine group is a divalent or higher valent amine having 1 to 40 carbon atoms.
5. The functionalized graphene according to claim 1, wherein The functionalized graphene has amphiphilicity.
6. The functionalized graphene according to claim 1, wherein The monovalent amine group is selected from the group consisting of n-butylamine, cyclohexylamine, n-hexylamine, phenylpropylamine, phenylbutylamine, octadecylamine, dodecylamine, and mixtures thereof.
7. The functionalized graphene according to claim 1, wherein The divalent or higher valent amine group is selected from n-diaminocyclohexane, n-diaminobutane, n-hexyldiamine, p-phenylenediamine, ethylenediamine, diaminododecane, 3,4-dimethyl-benzene-1,2-diamine and a mixture thereof.
8. A method for preparing functionalized graphene, comprising the following steps: mixing a carbon material and a first solvent to prepare a carbon material dispersion, wherein the carbon material is selected from the group consisting of graphene, reduced graphene, oxidized graphene, and a mixture thereof, and adding an amine solution to the carbon material dispersion, in which a first amine compound having a monovalent amine group, a second amine compound having a divalent or higher valent amine group, and a second solvent are mixed to chemically bond the amine group to the carbon material; Wherein, the molar ratio of the monovalent amine group to the divalent or higher valent amine group is 1:9 to 9:
1.
9. The method according to claim 8, wherein: In the carbon material dispersion, the amount of the carbon material is 0.1 to 30 wt %, the amount of the first solvent is 70 to 99.9 wt %, in the amine solution, the first amine compound is an amine compound having 1 to 40 carbon atoms, the second amine compound is an amine compound having 1 to 40 carbon atoms, relative to the total amount of the amine solution, the amount of the first amine compound and the second amine compound is 0.01 to 5 wt %, the ratio of the first amine compound to the second amine compound is 1:9 to 9:1, the amount of the second solvent is 95 to 99.9 wt %, and relative to 100 parts by weight of the carbon material dispersion, the amount of the amine solution added is 5 to 20 parts by weight.
10. The method according to claim 8, wherein: The hydrophobicity and hydrophilicity of the functionalized graphene are controlled by controlling the amount of amine groups.
11. A graphene composition comprising the amphiphilic functionalized graphene according to any one of claims 1 to 7. 12 . The graphene composition according to claim 11 , further comprising a solvent.
13. The graphene composition according to claim 12, further comprising a binder.
14. A graphene composite comprising the amphiphilic functionalized graphene according to any one of claims 1 to 7. 15 . The graphene composite according to claim 14 , further comprising a thermoplastic resin or a thermosetting resin.