Graphene quantum dots and methods for manufacturing the same

Abstract

The present invention provides graphene quantum dots that have anti-mite, anti-mold, and deodorizing functions, excellent antibacterial properties, as well as antistatic, heat-retaining, and heat-re-radiating properties that promote blood microcirculation, and a method for producing the same. [Solution] A method for producing graphene quantum dots with a particle size of 10 nm or less includes a first aqueous dispersion preparation step of reacting graphene oxide, hydrogen peroxide, and aqueous ammonia to prepare a first aqueous dispersion of graphene quantum dots; a second aqueous dispersion preparation step of adding a reducing agent and a phosphate to the first aqueous dispersion of graphene quantum dots, irradiating it with microwaves in the range of 100 to 200°C to prepare a second aqueous dispersion of graphene quantum dots in which graphene quantum dots with a particle size of 10 nm or less are dispersed; and a freeze-drying step of freeze-drying the second aqueous dispersion of graphene quantum dots to obtain graphene quantum dots with a particle size of 10 nm or less.

Description

Technical Field

[0001] The present invention relates to graphene quantum dots and a method for manufacturing the same.

Background Art

[0002] Graphene has excellent performance and is applied in various fields. In recent years, research on the utilization of graphene in composite materials and spinning has also been progressing. For example, Patent Document 1 discloses a graphene-nano silver composite material. Patent Document 2 discloses a method for preparing a polymer-based silver-containing graphene nano antibacterial material. Patent Document 3 discloses a graphene quantum dot-modified polymer masterbatch for functional fibers and a method for manufacturing the same.

[0003] However, in the materials disclosed in Patent Documents 1 and 2, the particle size of graphene is large, the antibacterial ability is low, and since a metal silver material is used, it places a burden on the environment and is also harmful to health. The functional masterbatch obtained according to the manufacturing method disclosed in Patent Document 3, when used in spinning, is not uniformly dispersed when mixed with each raw material, cannot fully exhibit the nanoknife effect of graphene quantum dots, and has low antibacterial properties. Also, due to the aggregation of graphene, excessive pressure is applied to the spinning assembly, graphene is not uniformly dispersed in the fiber matrix, and the heat re-radiation blocking effect of graphene is reduced. Furthermore, the conductive mesh of graphene in the fiber matrix is not formed, resulting in a decrease in the antistatic performance. do In recent years, graphene quantum dots having new functions and resin compositions containing the graphene quantum dots have been in demand.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

[0005] The problem that the present invention aims to solve is to provide graphene quantum dots that have anti-mite, anti-mold, and deodorizing functions, excellent antibacterial properties, and also have antistatic, heat-retaining, and heat-re-radiating properties that promote blood microcirculation; a resin composition containing graphene and the graphene quantum dots as two components; a masterbatch; a fiber; and a method for producing the same. [Means for solving the problem]

[0006] In view of the above-mentioned problems, the inventors conducted extensive research and found that graphene quantum dots with flavonoids chemically bonded to their surface, or graphene quantum dots with a particle size of 10 nm or less, possess not only antibacterial properties but also new functionalities. The present invention was completed based on these findings. To achieve the above objective, the present invention provides the following means.

[0007] Graphene quantum dots with flavonoids chemically bonded to their surface. The particle size of the graphene quantum dots is preferably 10 nm or less.

[0008] The present invention is a method for producing graphene quantum dots with a particle size of 10 nm or less, A first aqueous dispersion preparation step involves reacting graphene oxide, hydrogen peroxide, and aqueous ammonia to prepare a first graphene quantum dot aqueous dispersion, A second aqueous dispersion preparation step involves adding a reducing agent and a phosphate to the first aqueous dispersion of graphene quantum dots, irradiating it with microwaves in the range of 100-200°C, and preparing a second aqueous dispersion of graphene quantum dots in which graphene quantum dots with a particle size of 10 nm or less are dispersed; The present invention relates to a method for producing graphene quantum dots with a particle size of 10 nm or less, comprising a freeze-drying step in which the second aqueous dispersion of graphene quantum dots is freeze-dried to obtain graphene quantum dots with a particle size of 10 nm or less.

[0009] The present invention's method for producing graphene quantum dots with a particle size of 10 nm or less preferably further includes a flavonoid reaction step in which a second aqueous dispersion of graphene quantum dots is reacted with a flavonoid. [Effects of the Invention]

[0010] The graphene quantum dots of the present invention, with a particle size of 10 nm or less, possess excellent antibacterial properties, including mite-proof, antifungal, and deodorizing functions. Furthermore, they have antistatic, heat-retaining, and heat-re-radiating properties, which can promote blood microcirculation. Because they do not use silver, they prevent contamination of the human body by heavy metals and are environmentally friendly.

[0011] The present invention provides a method for producing graphene quantum dots, which can produce graphene quantum dots with a uniform particle size of 10 nm or less. Graphene quantum dots with a particle size of 10 nm or less produced by the present invention can be efficiently dispersed in the molecular gaps between polymers during the polymerization process of polymer materials, thereby improving the physical strength of the polymer material itself, resolving internal defects, and enhancing the performance of the polymer product. [Brief explanation of the drawing]

[0012] [Figure 1] This is a TEM measurement image showing the particle size and distribution of graphene quantum dots as one embodiment of the present invention. [Modes for carrying out the invention]

[0013] The present invention will be described in more detail. Unless otherwise specified, the "~" in a numerical range indicates a range from above to below, including both values ​​at either end. Furthermore, when a numerical range is indicated, the upper and lower limits may be combined as appropriate, and the resulting numerical range is also disclosed.

[0014] <Graphene quantum dots> The graphene quantum dots of the present invention are graphene quantum dots with a particle size of 10 nm or less. These graphene quantum dots have excellent sterilization and deodorizing properties. When they come into contact with bacteria, pressure is applied to the cell membrane, and oxidation occurs between the functional groups of the graphene quantum dots and the cell membrane, causing them to break through the cell wall, resulting in the leakage of RNA or DNA from within the bacterial cell and inactivation. Furthermore, the specific surface area of ​​the graphene quantum dots of the present invention with a particle size of 10 nm or less is extremely large, ranging from 500 to 1000 m². 2 It reaches a level of / g, possesses particularly strong adsorption capacity, and has excellent adsorption and removal effects against odors. It is also highly biocompatible, toxic, safe, and environmentally friendly.

[0015] The graphene quantum dots of this invention have flavonoids chemically bonded to their surface. By grafting flavonoids onto the graphene quantum dots, the dots are modified, which helps kill mites and imparts a mite-repelling effect. It is preferable to use mugwort extract as the raw material for the flavonoids.

[0016] The graphene quantum dots of the present invention preferably have flavonoids chemically bonded to their surface and have a particle size of 10 nm or less. By grafting flavonoids onto the surface of the graphene quantum dots, a mite-repellent effect is imparted, and because the particle size is 10 nm and the specific surface area is extremely large, the deodorizing and antibacterial effect can be improved. Furthermore, the graphene quantum dots with a particle size of 10 nm or less form a prism-like diffuse reflection effect with respect to long-wavelength ultraviolet light, effectively dissipating ultraviolet light and reducing damage to the skin.

[0017] The graphene quantum dots with a particle size of 10 nm or less are preferably flavonoid-modified graphene quantum dots in which flavonoids are chemically bonded to the surface.

[0018] <Method for manufacturing graphene quantum dots> The method for manufacturing graphene quantum dots with a particle size of 10 nm or less according to the present invention comprises: a first aqueous dispersion preparation step of reacting graphene oxide, hydrogen peroxide, and aqueous ammonia to prepare a first graphene quantum dot aqueous dispersion; a second aqueous dispersion preparation step of adding a reducing agent and a phosphate to the first graphene quantum dot aqueous dispersion, irradiating microwaves in the range of 100 to 200 °C, and preparing a second graphene quantum dot aqueous dispersion in which graphene quantum dots with a particle size of 10 nm or less are dispersed; and a freeze-drying step of freeze-drying the second graphene quantum dot aqueous dispersion to obtain graphene quantum dots with a particle size of 10 nm or less.

[0019] The method for manufacturing graphene quantum dots with a particle size of 10 nm or less according to the present invention preferably further includes a flavonoid reaction step of mixing the second graphene quantum dot aqueous dispersion and a flavonoid, performing ultrasonic treatment at 185 to 200 °C for 2 to 5 hours, and reacting the graphene quantum dots with the flavonoid.

[0020] Examples of the flavonoid include flavonoid-containing substances such as mugwort extract. In the flavonoid reaction step, the mass ratio of the second graphene quantum dot aqueous dispersion to the mugwort extract is preferably in the range of 50 to 70:50 to 30.

[0021] The graphene quantum dots produced by the production method of the present invention have a particle size of 10 nm or less and a uniform particle size, and have a very large specific surface area, so that the deodorizing and antibacterial effects can be improved. In addition, by grafting flavonoids on the surface, an excellent mite repellent effect is imparted.

Example

[0022] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[0023] [Example 1] <Preparation of graphene quantum dots> Graphene oxide, hydrogen peroxide, and aqueous ammonia were reacted in a 1 L glass reaction vessel, and the temperature was gradually increased from 70°C to 90°C for 4 hours to obtain the first graphene quantum dot aqueous dispersion. 50 mL of sodium hypophosphite solution was placed in a 100 mL glass reaction vessel, 9 g of the above graphene quantum dot aqueous dispersion was added, and after stirring until homogeneous, sonication was performed for 40 minutes. The glass reaction vessel was placed in a microwave reactor, the temperature was set to 150°C and the microwave output to 600 W, and microwave treatment was performed for 30 minutes. After the obtained liquid was cooled to room temperature, it was centrifuged for 10 minutes in a high-speed centrifuge at 9000 r / min, the supernatant was removed, and a second graphene quantum dot aqueous dispersion was obtained. The above-mentioned second graphene quantum dot aqueous dispersion and mugwort extract were mixed in a glass container in a mass ratio of 70:30, and ultrasonic treatment was performed for 2 to 5 hours at 185 to 200°C using an ultrasonic rod of 200 watts or more to obtain a graphene quantum dot aqueous dispersion in which flavonoids were chemically bonded to the surface. A water dispersion of graphene quantum dots, on which flavonoids are chemically bonded to the surface, was mixed with 3.5 times its mass of deionized water and filtered three times to obtain a purified dispersion. The dispersion was freeze-dried at -70°C for 7 hours using a freeze-dryer to obtain graphene quantum dot powder with a particle size of 10 nm or less and possessing mite-repellent properties.

[0024] <Preparing the Masterbatch> 2.5 parts by mass of graphene quantum dot powder with a particle size of 10 nm or less having the above-mentioned anti-mite function and 2 parts by mass of graphene with a particle size of 500 nm or less were mixed in a negative-pressure supercritical mixing apparatus. Pre-mixing was carried out for 2.5 hours under conditions of a temperature of 55°C and a rotation speed of 16000 R / min to obtain a uniformly dispersed two-component graphene powder. A matrix powder was obtained by grinding polyester slices with a viscosity of 1.0 or higher in a liquid nitrogen pulverizer at -169°C for 45 minutes. The above two-component graphene powder, 93 parts by mass of the above matrix powder, and 2.5 parts by mass of dopamine were placed in a mixing device (developed in-house) and mixed until homogeneous to obtain a functional powder. The stirring speed was 35-65 r / min, the stirring time was 1.5-2 hours, and the heating temperature was 45-85°C. The above functional powder was fed into a high-performance twin-screw granulator (CX-HO26, manufactured by Ruiya Co., Ltd.) with ultra-high torque and co-directional properties, and granulated at a temperature of 155-285°C for 15 minutes to obtain a semi-finished masterbatch. A crystal-drying treatment was performed in a dryer at a temperature of 105°C for 3 hours to obtain a masterbatch with a moisture content of less than 1% and a uniform distribution.

[0025] <Fiber preparation> The masterbatch described above was placed in a drum drying circulator and dried at a temperature of 85°C for 8 hours until the moisture content of the masterbatch was 1% by mass or less. The above masterbatch and polyester slices with a viscosity of 1.0 or higher were mixed in a negative pressure pump circulating mixer to obtain a mixed molten material. The mixing time was 2 to 2.5 hours, the mixing temperature was 85°C, the pump pressure was 2.5 standard atmospheres, and the circulation mixing rate was 45 r / min. The above mixed molten material was sent to a spinning machine via a negative pressure extraction device and a metering pump, spun at a temperature of 150-285°C and a pressure of 20-28 standard atmospheres, and cooled through a spinning sleeve to obtain continuous filament fibers with a fineness of 0.5 Dex or less.

[0026] [Example 2] A masterbatch and fibers containing graphene quantum dots and graphene were obtained in the same manner as in Example 1, except that the material composition of 2.5 parts by mass of graphene quantum dot powder with mite-repellent properties and a particle size of 10 nm or less was replaced with 3 parts by mass of graphene quantum dot powder with mite-repellent properties and a particle size of 10 nm or less, 3 parts by mass of graphene with a particle size of 500 nm or less, 91 parts by mass of matrix powder, and 3 parts by mass of dopamine.

[0027] [Example 3] A masterbatch and fibers containing graphene quantum dots and graphene were obtained in the same manner as in Example 1, except that the material composition of 2.5 parts by mass of graphene quantum dot powder with mite-repellent properties and a particle size of 10 nm or less, 2 parts by mass of graphene with a particle size of 500 nm or less, 93 parts by mass of matrix powder, and 2.5 parts by mass of dopamine was replaced with a material composition of 5 parts by mass of graphene quantum dot powder with mite-repellent properties and a particle size of 10 nm or less, 4 parts by mass of graphene with a particle size of 500 nm or less, 86 parts by mass of matrix powder, and 5 parts by mass of dopamine.

[0028] In the examples, various physical properties were measured or calculated as follows.

[0029] The particle size of the graphene quantum dots fabricated in Example 1 was detected using a transmission electron microscope (Talos STEM, Thermo Fisher Scientific). The results are shown in Figure 1.

[0030] The heat storage and insulation performance of the graphene quantum dots and graphene-containing fibers manufactured in Examples 1-3 was detected according to JIS L 1096 Method A (constant temperature method). The results are shown in Table 1.

[0031] The thermal re-emission properties of graphene quantum dots and graphene-containing fibers manufactured in Examples 1-3 were detected according to the 45-degree parallel re-emission method, a test method certified by the Far Infrared Association for evaluating thermal re-emission characteristics. The results are shown in Table 1.

[0032] The antibacterial activity of the graphene quantum dots and graphene-containing fibers produced in Examples 1-3 was detected according to the bacterial solution absorption method of JIS L 1902. The results are shown in Table 1.

[0033] The mite-repellent properties of the graphene quantum dots and graphene-containing fibers produced in Examples 1-3 were detected according to the glass tube method A of JIS L 1920. The results are shown in Table 1.

[0034] The antistatic properties of the graphene quantum dots and graphene-containing fibers produced in Examples 1-3 were detected according to the electrostatic testing method for woven and knitted fabrics specified in JIS L 1094. The results are shown in Table 1.

[0035] Figure 1 shows the particle size of the graphene quantum dots produced in Example 1. In the transmission electron microscope image (TEM measurement image) in Figure 1, the graphene quantum dots are shown as black dots. The particle size and distribution of the graphene quantum dots were measured using the particle size distribution measurement function of the transmission electron microscope. As shown in Figure 1, the particle size of the graphene quantum dots was 10 nm or less, and graphene quantum dots with a particle size of approximately 3 nm accounted for about 70% of the total.

[0036] [Table 1]

[0037] Table 1 shows the performance parameters of the two-component fibers containing graphene quantum dots and graphene produced in Examples 1 to 3. As shown in Table 1, the two-component fibers containing graphene quantum dots and graphene of the present invention exhibited good heat retention and insulation properties, and the measured value of heat re-radiation characteristics was greater than 5%, indicating superior performance. Antibacterial activity was 2.2 or higher, and anti-mite properties were also observed. Furthermore, the two-component fibers containing graphene quantum dots and graphene of the present invention were found to have an antistatic effect.

[0038] Although the present invention has been described in detail based on the above-described embodiments, these represent only a portion of the embodiments of the present invention, not all embodiments. Furthermore, other embodiments can be obtained based on these embodiments, and it should be understood that all of these embodiments fall within the scope of protection of the present invention.

Claims

1. A method for manufacturing graphene quantum dots with a particle size of 10 nm or less, A first aqueous dispersion preparation step involves reacting graphene oxide, hydrogen peroxide, and aqueous ammonia to prepare a first graphene quantum dot aqueous dispersion, A second aqueous dispersion preparation step involves adding a reducing agent and a phosphate to the first aqueous dispersion of graphene quantum dots, irradiating it with microwaves in the range of 100 to 200°C, and preparing a second aqueous dispersion of graphene quantum dots in which graphene quantum dots with a particle size of 10 nm or less are dispersed, and A method for producing graphene quantum dots with a particle size of 10 nm or less, comprising a freeze-drying step in which the second aqueous dispersion of graphene quantum dots is freeze-dried to obtain graphene quantum dots with a particle size of 10 nm or less.

2. A method for producing graphene quantum dots with a particle size of 10 nm or less, further comprising a flavonoid reaction step, in which the second graphene quantum dot aqueous dispersion is mixed with a flavonoid, and ultrasonic treatment is performed at 185 to 200°C for 2 to 5 hours to react the graphene quantum dots with the flavonoid.

3. Graphene quantum dots with flavonoids chemically bonded to their surface.

4. The graphene quantum dot according to claim 3, having a particle size of 10 nm or less.

5. The graphene quantum dot according to claims 3 to 4, characterized in that the flavonoid is an extract of mugwort.

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