Preparation method of graphene quantum dot cloud velvet

Abstract

The application discloses a preparation method of graphene quantum dot cloud wool, and relates to the technical field of cloud wool production. The graphene is peeled off by using citric acid assisted ultrasonic stripping, the ultrasonic cavitation effect is used to convert the three-dimensional peeling of the graphene into two-dimensional shearing, and the interaction between the citric acid and the graphene is promoted, then ball milling treatment is carried out, the obtained graphene quantum dots have a large specific surface area and high surface activity, and the antibacterial effect is realized; then, the silver nanoparticles are compounded, which not only reduces the particle self-agglomeration effect, but also enhances the reducibility of the graphene quantum dots, a large number of active oxygen free radicals are generated in the presence of oxygen molecules, the antibacterial property is improved, and the hollow short fibers are prepared through coaxial spinning, the contact space of the matrix and air is increased, and the antibacterial property is further enhanced.

Description

Technical Field

[0001] The present invention relates to the technical field of cloud velvet production, in particular to a method for preparing graphene quantum dot cloud velvet. Background Art

[0002] Graphene is a carbon material with a two-dimensional layered structure. Its extended honeycomb network is the fundamental building block of other allotropes. Graphene quantum dots are graphene fragments ranging in size from a few to tens of nanometers. Compared to graphene, the movement of electrons within graphene quantum dots is restricted in all directions, resulting in more superior properties. The emergence of graphene quantum dots has revolutionized science, with important applications in bioimaging, environmental monitoring, thermal interface materials, drug delivery, and antimicrobial applications. Notably, graphene-based cloud velvet can serve as a down alternative, offering greater potential for product upgrades in home textile thermal storage and outdoor warmth.

[0003] Currently, clothing often uses natural materials such as polyester staple fiber, cotton wool, cashmere, camel hair, and down as primary fillings. However, thermal clothing made with these fillings offers few health benefits beyond warmth and fashion. Furthermore, while down offers excellent thermal insulation, the organic matter inherent in the raw material can easily lead to bacterial growth and odor generation over time, negatively impacting human health. This is an urgent issue that needs to be addressed. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for preparing graphene quantum dot cloud velvet to solve the problems existing in the prior art.

[0005] In order to solve the above technical problems, the present invention provides the following technical solution: a method for preparing graphene quantum dot cloud velvet, comprising the following preparation steps:

[0006] (1) In an oil bath, a graphene aqueous solution with a concentration of 13.3 mg / mL and citric acid were mixed, heated to 110-150 °C, reacted for 20-30 min, deionized water was added, cooled to room temperature, ultrasonicated and ball-milled in sequence, and then centrifuged at 7000-11000 rpm for 10 min. The supernatant was taken and transferred to a 3500 Da dialysis bag, and the external solution was changed every 2 h until the pH of the external solution was 7-8. Then, the solution was freeze-dried to obtain graphene quantum dots.

[0007] (2) Graphene quantum dots and deionized water were mixed, 0.018 wt% silver nitrate aqueous solution was added, and the mixture was stirred at 60-100 rpm for 10-20 min. The mixture was heated to 95-110 °C, sodium citrate was added, and the mixture was stirred at a constant temperature for 30-70 min. The mixture was cooled to room temperature, and the mixture was transferred to a 3500 Da dialysis bag for filtration and freeze-dried to obtain graphene quantum dot composite nanosilver.

[0008] (3) Mix polyvinyl alcohol and deionized water, heat to 60-90°C, stir at 100-200 rpm for 100-200 min, add graphene quantum dot composite nanosilver, continue stirring for 30-80 min, then use air as the core for coaxial spinning, and then shear to obtain graphene quantum dot cloud velvet.

[0009] Furthermore, the power of the ultrasound in step (1) is 400-800W and the time is 5-8h.

[0010] Furthermore, the process parameters of the ball milling in step (1) are as follows: the ball milling medium is agate balls, the ball-to-material ratio is 10:1, the rotation speed is 1350 rpm, and the time is 1.5 to 3 hours.

[0011] Furthermore, the mass ratio of the graphene aqueous solution with a concentration of 13.3 mg / mL, citric acid, and deionized water in step (1) is 3:0.5:10.

[0012] Furthermore, in step (2), the mass ratio of the graphene quantum dots, deionized water, 0.018 wt% silver nitrate aqueous solution, and sodium citrate is 0.03-0.08:300-600:0.15-0.28:0.2.

[0013] Furthermore, the freeze-drying temperature in step (1) and step (2) is -24 to -40°C and the time is 20 to 30 hours.

[0014] Furthermore, the molecular weight of the polyvinyl alcohol in step (3) is 2×10 4 .

[0015] Furthermore, the process parameters of the coaxial spinning in step (3) are: inner needle diameter of 1.56 mm, outer needle diameter of 4.21 mm, receiving distance of 20 cm, and feed rate of 20-50 mL / h.

[0016] Furthermore, the mass ratio of the polyvinyl alcohol, deionized water, and graphene quantum dot composite nanosilver in step (3) is 20-30:60-100:1-5.

[0017] Furthermore, the length of the graphene quantum dot cloud fleece in step (3) is 0.5 to 1.5 cm.

[0018] Compared with the prior art, the present application has the beneficial effects that: the present application uses citric acid to assist in ultrasonic exfoliation of graphene, under the cavitation effect of ultrasonic, the molecules are strongly vibrated, the van der Waals force between the layers of layered graphene is overcome, the impact is converted into corresponding quantum dots, which are better dispersed in the solvent, and are converted from three-dimensional exfoliation to two-dimensional shearing, and are exfoliated layer by layer, meanwhile, through the ultrasonic energy, the interaction and absorption between citric acid and graphene are realized, through dehydration condensation, a large number of oxygen-containing functional groups are contained around the graphene quantum dots, and then ball milling treatment is carried out, the graphene is further exfoliated and damaged through mechanical force, so that the obtained graphene quantum dots have a large specific surface area and high surface activity, which is beneficial to the capture of bacteria, so as to kill the bacteria and realize the antibacterial effect of the substrate; then, as the anchor point for the crystallization nucleation of silver nanoparticles, and covered by the carboxyl and hydroxyl groups on the surface, the silver particles blocked by the graphene quantum dots not only reduce the self-agglomeration effect, but also enhance the reducibility of the graphene quantum dots, so that the graphene quantum dot-silver generates a large number of active oxygen free radicals in the presence of oxygen molecules, the free radicals further act on the cell membrane of bacteria, so as to improve the antibacterial property, and the hollow short fibers are prepared by spinning, the contact space of the substrate and air is increased, and the antibacterial property is further improved. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0020] In order to more clearly illustrate the method provided by the present application, the following embodiments are described in detail, and the test methods of each index of the graphene quantum dot cloud wool prepared in the following embodiments are as follows:

[0021] Antibacterial property: the same size of the embodiments and the comparative examples are taken to detect the antibacterial rate of Staphylococcus aureus and Escherichia coli according to the oscillation method of GB / T20944, and the antibacterial rate is detected again after standing for 60 days.

[0022] Example 1; (1) Under oil bath conditions, a graphene aqueous solution with a concentration of 13.3 mg / mL and citric acid were mixed, heated to 110°C, reacted for 20 minutes, deionized water was added, cooled to room temperature, and first ultrasonically treated with a power of 400 W and a time of 5 hours, and then ball milled. The process parameters were as follows: the ball milling medium was agate balls, the ball-to-material ratio was 10:1, the rotation speed was 1350 rpm, and the time was 1.5 hours. Subsequently, the supernatant was taken and transferred to a 3500 Da dialysis bag, and the external liquid was changed every 2 hours until the pH of the external liquid was 7. The mixture was then freeze-dried at -24°C for 20 hours to obtain graphene quantum dots. The mass ratio of the graphene aqueous solution with a concentration of 13.3 mg / mL, citric acid, and deionized water was 3:0.5:10.

[0023] (2) Graphene quantum dots and deionized water were mixed, 0.018 wt% silver nitrate aqueous solution was added, and the mixture was stirred at 60 rpm for 10 min. The mixture was heated to 95 °C, sodium citrate was added, and the mixture was stirred at a constant temperature for 30 min. The mixture was cooled to room temperature, and the mixture was transferred to a 3500 Da dialysis bag for filtration. The mixture was dried at -24 °C for 20 h to obtain graphene quantum dot composite nanosilver. The mass ratio of the graphene quantum dots, deionized water, 0.018 wt% silver nitrate aqueous solution, and sodium citrate was 0.03:300:0.15:0.2.

[0024] (3) The molecular weight is 2×10 4 The mixture was mixed with polyvinyl alcohol and deionized water, heated to 60°C, stirred at 100 rpm for 100 min, and graphene quantum dots composite nanosilver were added. The mixture was stirred for 30 min, and then coaxial spinning was performed with air as the core. The process parameters were as follows: inner needle diameter of 1.56 mm, outer needle diameter of 4.21 mm, receiving distance of 20 cm, and feed rate of 20 mL / h. The mixture was then sheared to obtain graphene quantum dots cloud velvet with a length of 0.5 cm. The molecular weight was 2×10 4 The mass ratio of polyvinyl alcohol, deionized water, and graphene quantum dot composite nanosilver is 20:60:1.

[0025] Example 2; (1) under oil bath condition, graphene aqueous solution with concentration of 13.3 mg / mL, citric acid were mixed, heated to 130℃, reacted for 25 min, deionized water was added, cooled to room temperature, first ultrasonic treatment was carried out, the power was 600 W, the time was 6 h, then ball milling was carried out, the process parameters were as follows: the ball milling medium was agate ball, the ball to material ratio was 10:1, the rotation speed was 1350 rpm, the time was 2 h, then centrifugation was carried out at 9000 rpm for 10 min, the supernatant was taken and transferred to a dialysis bag with a molecular weight of 3500 Da, and the outer liquid was changed every 2 h until the pH of the outer liquid was 7.5, then freeze-drying was carried out, the temperature was -32℃, the time was 25 h, graphene quantum dots were obtained; the mass ratio of the graphene aqueous solution with concentration of 13.3 mg / mL, citric acid, deionized water was 3:0.5:10;

[0026] (2) graphene quantum dots, deionized water were mixed, 0.018wt% silver nitrate aqueous solution was added, stirred at 80 rpm for 15 min, heated to 105℃, sodium citrate was added, constant temperature stirring was carried out for 50 min, cooled to room temperature, transferred to a dialysis bag with a molecular weight of 3500 Da for filtration, dried at -32℃ for 25 h, graphene quantum dots composite nano-silver was obtained; the mass ratio of the graphene quantum dots, deionized water, 0.018wt% silver nitrate aqueous solution, sodium citrate was 0.06:450:0.22:0.2;

[0027] (3) polyvinyl alcohol with molecular weight of 2×10 4 , deionized water were mixed, heated to 75℃, stirred at 150 rpm for 150 min, graphene quantum dots composite nano-silver was added, continued to stir for 55 min, then coaxial spinning was carried out with air as the core, the process parameters were as follows: the inner needle diameter was 1.56 mm, the outer needle diameter was 4.21 mm, the receiving distance was 20 cm, the feeding rate was 40 mL / h, then shearing was carried out, graphene quantum dots fleece with length of 1 cm was obtained; the mass ratio of the polyvinyl alcohol with molecular weight of 2×10 4 , deionized water, graphene quantum dots composite nano-silver was 25:80:3.

[0028] Example 3; (1) Under oil bath conditions, a graphene aqueous solution with a concentration of 13.3 mg / mL and citric acid were mixed, heated to 150°C, reacted for 30 minutes, deionized water was added, cooled to room temperature, and first subjected to ultrasonic treatment with a power of 800 W and a time of 8 hours, and then ball milling was performed. The process parameters were: the ball milling medium was agate balls, the ball-to-material ratio was 10:1, the speed was 1350 rpm, and the time was 3 hours. Subsequently, the supernatant was taken and transferred to a 3500 Da dialysis bag, and the external liquid was changed every 2 hours until the pH of the external liquid was 8. The mixture was then freeze-dried at -40°C for 30 hours to obtain graphene quantum dots. The mass ratio of the graphene aqueous solution with a concentration of 13.3 mg / mL, citric acid, and deionized water was 3:0.5:10.

[0029] (2) Graphene quantum dots and deionized water were mixed, 0.018 wt% silver nitrate aqueous solution was added, and the mixture was stirred at 100 rpm for 20 min. The mixture was heated to 110°C, sodium citrate was added, and the mixture was stirred at a constant temperature for 70 min. The mixture was cooled to room temperature, and the mixture was transferred to a 3500 Da dialysis bag for filtration. The mixture was dried at -40°C for 30 h to obtain graphene quantum dot composite nanosilver. The mass ratio of the graphene quantum dots, deionized water, 0.018 wt% silver nitrate aqueous solution, and sodium citrate was 0.08:600:0.28:0.2.

[0030] (3) The molecular weight is 2×10 4 The mixture was mixed with polyvinyl alcohol and deionized water, heated to 90°C, stirred at 200 rpm for 200 min, and graphene quantum dots composite nanosilver were added. The mixture was stirred for 80 min, and then coaxial spinning was performed with air as the core. The process parameters were as follows: inner needle diameter of 1.56 mm, outer needle diameter of 4.21 mm, receiving distance of 20 cm, and feed rate of 50 mL / h. The mixture was then sheared to obtain graphene quantum dots cloud velvet with a length of 1.5 cm. The molecular weight was 2×10 4 The mass ratio of polyvinyl alcohol, deionized water, and graphene quantum dot composite nanosilver is 30:100:5.

[0031] Comparative Example 1: The difference between Comparative Example 1 and Example 2 is that step (1) is different. Step (1) is changed to: under oil bath conditions, a graphene aqueous solution with a concentration of 13.3 mg / mL and N-methylpyrrolidone are mixed, heated to 130°C, reacted for 25 minutes, deionized water is added, cooled to room temperature, first subjected to ultrasonic treatment with a power of 600 W and a time of 6 hours, and then ball milled. The process parameters are: the ball milling medium is agate balls, the ball-to-material ratio is 10:1, and the rotation speed is 13 50 rpm, time is 2h, then centrifuged at 9000 rpm for 10 min, the supernatant is taken, transferred to a 3500Da dialysis bag, and the external liquid is changed every 2h until the pH of the external liquid is 7.5, and then freeze-dried at a temperature of -32 ° C for 25h to obtain graphene quantum dots; the mass ratio of the graphene aqueous solution with a concentration of 13.3 mg / mL, N-methylpyrrolidone, and deionized water is 3:0.5:10; the remaining steps are the same as in Example 2.

[0032] Comparative Example 2; The difference between Comparative Example 2 and Example 2 is that step (1) is different. Step (1) is changed to: under oil bath conditions, a graphene aqueous solution with a concentration of 13.3 mg / mL and citric acid are mixed, heated to 130°C, reacted for 25 minutes, deionized water is added, cooled to room temperature, and ball milled. The process parameters are: the ball milling medium is agate balls, the ball-to-material ratio is 10:1, the speed is 1350 rpm, and the time is 2 hours. Subsequently, centrifugation is performed at 9000 rpm for 10 minutes, the supernatant is taken, transferred to a 3500Da dialysis bag, and the external liquid is changed every 2 hours until the pH of the external liquid is 7.5, and then freeze-dried at a temperature of -32°C and a time of 25 hours to obtain graphene quantum dots; the mass ratio of the graphene aqueous solution with a concentration of 13.3 mg / mL, citric acid, and deionized water is 3:0.5:10; the remaining steps are the same as Example 2.

[0033] Comparative Example 3; The difference between Comparative Example 3 and Example 2 is that step (1) is different. Step (1) is changed to: under oil bath conditions, a graphene aqueous solution with a concentration of 13.3 mg / mL and citric acid are mixed, the temperature is raised to 130°C, the reaction is carried out for 25 minutes, deionized water is added, the mixture is cooled to room temperature, and ultrasonic treatment is performed with a power of 600 W and a time of 6 hours. Subsequently, the mixture is centrifuged at 9000 rpm for 10 minutes, the supernatant is taken, and the mixture is transferred to a 3500Da dialysis bag. The external liquid is changed every 2 hours until the pH of the external liquid is 7.5, and then freeze-dried at a temperature of -32°C and a time of 25 hours to obtain graphene quantum dots; the mass ratio of the graphene aqueous solution with a concentration of 13.3 mg / mL, citric acid, and deionized water is 3:0.5:10; the remaining steps are the same as in Example 2.

[0034] Comparative Example 4: The difference between Comparative Example 4 and Example 2 is that there is no step (2); the remaining steps are the same as Example 2.

[0035] Comparative Example 5: The difference between Comparative Example 5 and Example 2 is that step (3) is different. Step (3) is changed to: 4 The polyvinyl alcohol and deionized water were mixed, heated to 75 ° C, stirred at 150 rpm for 150 min, and graphene quantum dots composite nanosilver were added. The stirring was continued for 55 min, and then spinning was carried out. The process parameters were as follows: needle diameter of 2.56 mm, receiving distance of 20 cm, feed rate of 40 mL / h, and then shearing was carried out to obtain graphene quantum dot cloud velvet with a length of 1 cm; the molecular weight was 2×10 4 The mass ratio of polyvinyl alcohol, deionized water, and graphene quantum dot composite nanosilver is 25:80:3; the remaining steps are the same as those in Example 2.

[0036] Effect Examples

[0037] Table 1 below shows the performance analysis results of the graphene quantum dot cloud fleece obtained using Examples 1 to 3 of the present invention and Comparative Examples 1 to 5.

[0038] Table 1

[0039]

[0040] From the comparison of the experimental data of the embodiment and the comparative example in Table 1, it can be found that the present invention utilizes citric acid to assist ultrasonic exfoliation of graphene. Under the cavitation effect of ultrasound, the molecules vibrate strongly, overcome the van der Waals force between the layered graphene layers, and the impact is converted into corresponding quantum dots, so that they are better dispersed in the solvent. It will also convert the exfoliation from the three-dimensional direction into the shearing direction of the two-dimensional direction, exfoliating layer by layer. At the same time, through the ultrasonic energy, the citric acid interacts and absorbs with the graphene, and after dehydration condensation, a large number of oxygen-containing functional groups are contained around the graphene quantum dots. Then, ball milling is performed, and the graphene is further exfoliated and destroyed by mechanical force, thereby promoting the obtained graphite. Graphene quantum dots have a huge specific surface area and high surface activity, which are conducive to the capture of bacteria, thereby sterilizing them and making the matrix achieve antibacterial effect; then, as the anchor point for the crystallization nucleation of silver nanoparticles, and covered by the carboxyl and hydroxyl groups on the surface, the silver particles blocked by graphene quantum dots not only reduce the self-agglomeration effect, but also enhance the reducibility of graphene quantum dots, so that graphene quantum dots-silver produce a large number of active oxygen free radicals in the presence of oxygen molecules, and the free radicals further act on the cell membrane of bacteria, thereby improving the antibacterial property, and hollow short fibers are produced by coaxial spinning, which increases the contact space between the matrix and the air, thereby enhancing the antibacterial property.

[0041] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be encompassed therein. Any reference in a claim should not be construed as limiting the claim to which it relates.

Claims

1. A method for preparing graphene quantum dot cloud velvet, characterized in that: The method comprises the following preparation steps: (1) In an oil bath, a graphene aqueous solution with a concentration of 13.3 mg / mL and citric acid were mixed, heated to 110-150°C, reacted for 20-30 min, deionized water was added, cooled to room temperature, and ultrasonic and ball milling were performed in sequence. Subsequently, the mixture was centrifuged at 7000-11000 rpm for 10 min, the supernatant was taken, transferred to a 3500 Da dialysis bag, and the external solution was changed every 2 h until the pH of the external solution was 7-8, and then freeze-dried to obtain graphene quantum dots; the power of the ultrasonic treatment was 400-800 W and the time was 5-8 h; (2) Graphene quantum dots and deionized water were mixed, 0.018 wt% silver nitrate aqueous solution was added, and the mixture was stirred at 60-100 rpm for 10-20 min. The mixture was heated to 95-110 °C, sodium citrate was added, and the mixture was stirred at a constant temperature for 30-70 min. The mixture was cooled to room temperature, and the mixture was transferred to a 3500 Da dialysis bag for filtration and freeze-dried to obtain graphene quantum dot composite nanosilver. (3) Mix polyvinyl alcohol and deionized water, heat to 60-90°C, stir at 100-200 rpm for 100-200 min, add graphene quantum dot composite nanosilver, continue stirring for 30-80 min, then use air as the core for coaxial spinning, and then shear to obtain graphene quantum dot cloud velvet.

2. The method for preparing graphene quantum dot cloud velvet according to claim 1, characterized in that: The process parameters of the ball milling in step (1) are as follows: the ball milling medium is agate balls, the ball-to-material ratio is 10:1, the rotation speed is 1350 rpm, and the time is 1.5~3h.

3. The method for preparing graphene quantum dot cloud velvet according to claim 1, characterized in that: The mass ratio of the graphene aqueous solution with a concentration of 13.3 mg / mL, citric acid, and deionized water in step (1) is 3:0.5:

10.

4. The method for preparing graphene quantum dot cloud velvet according to claim 1, characterized in that: In step (2), the mass ratio of the graphene quantum dots, deionized water, 0.018 wt% silver nitrate aqueous solution, and sodium citrate is 0.03-0.08:300-600:0.15-0.28:0.

2.

5. The method for preparing graphene quantum dot cloud velvet according to claim 1, characterized in that: The freeze-drying temperature in step (1) and step (2) is -24 to -40°C and the time is 20 to 30 hours.

6. The method for preparing graphene quantum dot cloud velvet according to claim 1, characterized in that: The molecular weight of the polyvinyl alcohol in step (3) is 2×10 4 .

7. The method for preparing graphene quantum dot cloud velvet according to claim 1, characterized in that: The process parameters of the coaxial spinning in step (3) are as follows: inner needle diameter of 1.56 mm, outer needle diameter of 4.21 mm, receiving distance of 20 cm, and feed rate of 20-50 mL / h.

8. The method for preparing graphene quantum dot cloud velvet according to claim 1, characterized in that: The mass ratio of the polyvinyl alcohol, deionized water, and graphene quantum dot composite nanosilver in step (3) is 20-30:60-100:1-5.

9. The method for preparing graphene quantum dot cloud velvet according to claim 1, characterized in that: The length of the graphene quantum dot cloud fleece in step (3) is 0.5 to 1.5 cm.

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