A melanin / oxidized graphene layered aerogel film and a preparation method thereof

Abstract

The application discloses a kind of iso melanin / oxidized graphene layered aerogel film and preparation method thereof, method includes: 1,8-dihydroxynaphthalene is dissolved in solvent, and ultrasonic dispersion, stirring are carried out, and 1,8-dihydroxynaphthalene solution is obtained;1,8-dihydroxynaphthalene / oxidized graphene mixed solution is obtained by adding oxidized graphene aqueous dispersion and stirring;Sodium periodate solution is added, and stirring is carried out at room temperature for 4-48h, then centrifugation, washing, and iso melanin / oxidized graphene slurry is obtained;Unidirectional freeze forming is carried out using liquid nitrogen, then freeze drying is carried out, and iso melanin / oxidized graphene aerogel film is obtained.The raw materials used in the application are all common reagents, and the preparation method has good repeatability;Using the similar structure and interaction of 1,8-dihydroxynaphthalene and oxidized graphene, a one-pot in-situ polymerization is used to obtain an iso melanin intercalated oxidized graphene composite film, and the process is efficient, simple and has high process synergy.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of melanin application, and particularly relates to a melanoidin / oxidized graphene layered aerogel film and a preparation method thereof. BACKGROUND

[0002] Melanoidin is found in the cell walls of fungi in nuclear radiation areas, which can effectively resist the damage of high-energy radiation to the fungi body. Research shows that fungi containing melanoidin not only can withstand the radioactive effect of nuclear power plants, but even can convert the energy of radiation into chemical energy needed for growth. With the in-depth basic research, the molecular structure of melanoidin has been revealed, which is composed of dihydroxynaphthalene precursor. Compared with other common artificial melanin, it has attracted people's attention as an energy conversion material.

[0003] Researchers try to separate melanoidin from natural substances to realize its functional design and expansion, but melanoidin often exists in the form of polysaccharide or protein complex in nature, which is difficult to separate effectively. Therefore, researchers synthesize artificial melanoidin by chemical oxidation or bio-enzyme chemistry method with 1,8-dihydroxynaphthalene as precursor, but its application mostly stays in the field of antioxidant and light protection, and there is still a lack of a large number of exploration in more aspects of energy conversion.

[0004] The 1,8-dihydroxynaphthalene precursor of melanoidin has typical hydrogen bond interaction and Π interaction, and has similar structure and interaction with graphene oxide. However, due to the large topological structure and limited reaction sites of graphene oxide, it is often necessary to add additional components and introduce complex processes in the forming process of graphene oxide. Developing simple graphene oxide composite materials is the key to its practical application. SUMMARY

[0005] In view of the above defects or improvement needs of the prior art, the present application aims to insert 1,8-dihydroxynaphthalene into the interlayer of graphene oxide based on the similar structure and interaction of 1,8-dihydroxynaphthalene precursor molecule and graphene oxide, in-situ polymerize in the interlayer by oxidation polymerization, and obtain a melanoidin / graphene oxide layered aerogel composite film with electromagnetic shielding function by the method of unidirectional freeze forming and freeze drying.

[0006] To achieve the above-mentioned purpose, according to one aspect of the present application, a preparation method of a melanoidin / graphene oxide layered aerogel film is provided, comprising the following steps:

[0007] S1: dissolving 1,8-dihydroxynaphthalene in a solvent, and performing ultrasonic dispersion and stirring to obtain a 1,8-dihydroxynaphthalene solution;

[0008] S2: adding graphene oxide water dispersion into the 1,8-dihydroxynaphthalene solution and stirring to obtain a 1,8-dihydroxynaphthalene / graphene oxide mixed solution;

[0009] S3: adding a sodium metaperiodate solution into the 1,8-dihydroxynaphthalene / graphene oxide mixed solution, stirring at room temperature for 4-48 h, and then centrifuging and washing to obtain a melanin / graphene oxide slurry;

[0010] S4: unidirectionally freezing the melanin / graphene oxide slurry into a shape using liquid nitrogen, and then freeze-drying to obtain a melanin / graphene oxide aerogel film.

[0011] Further, the solvent in S1 is a mixture of acetonitrile and water, wherein the volume fraction of acetonitrile is 10-20% and the volume fraction of water is 80-90%.

[0012] Further, the concentration of the 1,8-dihydroxynaphthalene solution is 1-5 mg / mL.

[0013] Further, the addition amount of the graphene oxide water dispersion in S2 is 20 mL, wherein the content of graphene oxide is 1:1-4:1 in terms of the mass ratio of 1,8-dihydroxynaphthalene to graphene oxide.

[0014] Further, the concentration of the sodium metaperiodate solution in S3 is 200 mg / mL, and the addition amount of the sodium metaperiodate solution is 1:0.5-1:1 in terms of the mass ratio of 1,8-dihydroxynaphthalene to sodium metaperiodate.

[0015] Further, the stirring reaction time in S3 is 20 h.

[0016] Further, the centrifugation speed in S3 is 12000-16000 r / min, and the centrifugation time is 5-10 min.

[0017] Further, the freeze-drying temperature in S4 is -80°C.

[0018] According to another aspect of the present application, a melanin / graphene oxide layered aerogel film is provided, which is prepared according to the preparation method as described above.

[0019] Further, the thickness of the melanin / graphene oxide layered aerogel film is 2 mm-10 mm.

[0020] Compared with the prior art, the present application can achieve the following beneficial effects:

[0021] 1、The raw material used in the application is simple, the precursor molecules 1,8-dihydroxynaphthalene, graphene oxide and oxidant sodium periodate used in the synthesis process are common reagents with standard production specifications, which are very convenient to use and make the method have good repeatability; only two relatively green and environmentally friendly solvents, water and acetonitrile, are used, avoiding the introduction of a large amount of other organic solvents, ensuring the green, environmentally friendly and safe characteristics of the whole process.

[0022] 2, The application utilizes the similar structure and interaction of 1,8-dihydroxynaphthalene and graphene oxide, adopts one-pot in-situ polymerization to obtain the composite film of iso melanin intercalated graphene oxide, which has higher efficiency, simplicity and process synergy than the traditional template method or chemical crosslinking.

[0023] 3, The method adopted in the application has high efficiency, repeatability and scalability, has good industrialization prospect, and compared with the traditional preparation method of graphene oxide composite film, the process is simple, and the size can be easily enlarged according to the demand, which has great advantages in actual application.

[0024] 4, The preparation method provided by the application has good adjustability, and the film is adjusted by the amount of graphene oxide and the concentration of 1,8-dihydroxynaphthalene.

[0025] 5, The iso melanin / graphene oxide film provided by the application has very excellent electromagnetic shielding function, and the film material with different grades can be easily realized by adjusting the thickness. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 It is a scanning electron microscope graph of the iso melanin / graphene oxide aerogel film of example 1 of the application;

[0027] Figure 2 It is an X-ray diffraction graph of the iso melanin / graphene oxide aerogel film of example 1 of the application;

[0028] Figure 3 It is an element proportion distribution graph of the iso melanin / graphene oxide aerogel film of example 1 of the application;

[0029] Figure 4 It is a yield statistical graph of the iso melanin / graphene oxide aerogel film obtained by different stirring time of example 1 and 2 of the application;

[0030] Figure 5 It is an electromagnetic shielding efficiency statistical graph of the iso melanin / graphene oxide aerogel film obtained by different sodium periodate addition amount of example 1 and 3 of the application;

[0031] Figure 6A statistical chart of electromagnetic shielding efficiency of the iso-black / oxidized graphene aerogel film obtained from different amounts of graphene oxide of the embodiment 1 and 4 of the present application;

[0032] Figure 7 A statistical chart of electromagnetic shielding efficiency of the iso-black / oxidized graphene aerogel film obtained from different concentrations of 1,8-dihydroxynaphthalene solution of the embodiment 1 and 5 of the present application;

[0033] Figure 8 A statistical chart of electromagnetic shielding efficiency of the iso-black / oxidized graphene aerogel film obtained from different thicknesses of iso-black / oxidized graphene aerogel film of the embodiment 1 and 6 of the present application. DETAILED DESCRIPTION

[0034] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not used to limit the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as they do not conflict with each other.

[0035] The present application is based on the similarity of the structure and interaction of iso-black precursor small molecule 1,8-dihydroxynaphthalene and graphene oxide. 1,8-dihydroxynaphthalene and graphene oxide are in-situ polymerized under one-pot conditions using an oxidizing agent, which can quickly and conveniently form an iso-black / graphene oxide layered material. The obtained layered material is formed into an aerogel film by a unidirectional freeze casting method, which has high electromagnetic shielding efficiency, and is easy to customize the thickness of the material and the amount of graphene oxide according to the needs to achieve different levels of electromagnetic shielding efficiency.

[0036] The present application provides a preparation method of iso-black / oxidized graphene layered aerogel film, comprising the following steps:

[0037] S1: Dissolve 1,8-dihydroxynaphthalene in a solvent mixed with acetonitrile and water, and perform ultrasonic dispersion treatment for 3-10 minutes, and then fully stir at room temperature for 3-10 minutes to obtain a uniform transparent colorless 1,8-dihydroxynaphthalene solution.

[0038] Among them, the volume fraction of acetonitrile in the mixed solvent is 10-20%, and the volume fraction of water is 80-90%; the concentration of 1,8-dihydroxynaphthalene solution is 1-5 mg / mL.

[0039] S2: Slowly add graphene oxide aqueous dispersion to the 1,8-dihydroxynaphthalene solution and stir to obtain a 1,8-dihydroxynaphthalene / graphene oxide mixed solution.

[0040] The added amount of the graphene oxide aqueous dispersion is 20 mL, and the content of the graphene oxide is calculated according to the mass ratio of 1,8-dihydroxynaphthalene to graphene oxide of 1:1-4:1.

[0041] S3: slowly adding a sodium periodate solution to the 1,8-dihydroxynaphthalene / graphene oxide mixed solution, the concentration of the sodium periodate solution is 200 mg / mL, and the added amount of the potassium permanganate solution is calculated according to the mass ratio of 1,8-dihydroxynaphthalene to sodium periodate of 1:0.5-1:1; maintaining a uniform stirring speed at room temperature for 4-48 h of continuous stirring reaction to obtain a uniform and stable black turbid solution; centrifuging the black turbid solution at a speed of 12000-16000 r / min for 5-10 min, and then washing with deionized water to obtain an iso melanin / graphene oxide slurry.

[0042] During the stirring reaction, 1,8-dihydroxynaphthalene is intercalated into the graphene oxide layers through hydrogen bonding interaction and Π interaction, and after the addition of sodium periodate, 1,8-dihydroxynaphthalene is oxidized in situ to form iso melanin in the graphene oxide layers, and iso melanin is intercalated into the graphene oxide layers to form a layered composite through Π interaction.

[0043] S4: unidirectional freezing the iso melanin / graphene oxide slurry with liquid nitrogen to form a film, and then freeze-drying to obtain an iso melanin / graphene oxide aerogel film.

[0044] Specifically, the iso melanin / graphene oxide slurry is placed in a two-way polytetrafluoroethylene mold, the bottom is a 4 mm copper plate, the copper plate is immersed in liquid nitrogen, and the iso melanin / graphene oxide slurry is frozen under unidirectional freezing, and then placed in a vacuum environment at-80℃ for freeze-drying to obtain an iso melanin / graphene oxide aerogel film.

[0045] In this process, the iso melanin / graphene oxide forms unidirectional oriented ice crystals under unidirectional freezing, and further constructs a layered structure.

[0046] The application also provides an iso melanin / graphene oxide layered aerogel film prepared according to the preparation method described above, and the thickness of the iso melanin / graphene oxide layered aerogel film is 2-10 mm.

[0047] Example 1

[0048] A preparation method of an iso melanin / graphene oxide aerogel film, comprising the following steps:

[0049] (1) 1,8-dihydroxynaphthalene was dissolved in a solvent of acetonitrile and water mixed at a volume fraction of 10% acetonitrile and 90% water; ultrasonic dispersion treatment was performed for 8 minutes, and then it was stirred at room temperature for 5 minutes to obtain a uniform, transparent, colorless 1,8-dihydroxynaphthalene solution with a concentration of 3 mg / mL.

[0050] (2) A graphene oxide aqueous dispersion was slowly added to the 1,8-dihydroxynaphthalene solution and stirred to obtain a 1,8-dihydroxynaphthalene / graphene oxide mixed solution. The amount of the graphene oxide aqueous dispersion added was 20 mL, and the content of graphene oxide was 3:1 by mass ratio of 1,8-dihydroxynaphthalene to graphene oxide.

[0051] (3) A sodium periodate solution with a concentration of 200 mg / mL was slowly added to the 1,8-dihydroxynaphthalene / graphene oxide mixed solution, and the amount of the potassium permanganate solution added was 1:0.8 by mass ratio of 1,8-dihydroxynaphthalene to sodium periodate; uniform stirring was maintained at room temperature for 20 h to obtain a uniform, stable black turbid solution; the black turbid solution was centrifuged at a speed of 15000 r / min for 8 min, and then washed with deionized water three times to obtain an iso melanin / graphene oxide slurry.

[0052] (4) The iso melanin / graphene oxide slurry was placed in a two-way polytetrafluoroethylene mold with a 4 mm copper plate at the bottom, the copper plate was immersed in liquid nitrogen, and the iso melanin / graphene oxide slurry was frozen under unidirectional freezing, and then freeze-dried in a vacuum environment at -80°C to obtain an iso melanin / graphene oxide aerogel film with a thickness of 10 mm.

[0053] Example 2

[0054] The stirring time of the stirring reaction in step (3) of Example 1 was adjusted to 4 h, 10 h, 16 h, 24 h, and 48 h, respectively, to obtain an iso melanin / graphene oxide aerogel film with a thickness of 5 mm.

[0055] Example 3

[0056] The mass ratio of 1,8-dihydroxynaphthalene to sodium periodate in step (3) of Example 1 was adjusted to 1:0.5, 1:0.6, 1:0.7, 1:0.9, and 1:1, respectively, to obtain an iso melanin / graphene oxide aerogel film with a thickness of 5 mm.

[0057] Example 4

[0058] The mass ratio of 1,8-dihydroxynaphthalene to graphene oxide in step (2) of Example 1 was adjusted to 1:1, 2:1, and 4:1, respectively, to obtain an iso melanin / graphene oxide aerogel film with a thickness of 5 mm.

[0059] Example 5

[0060] The concentration of the 1,8-dihydroxynaphthalene solution in step (1) of Example 1 was adjusted to 1, 2, 4, and 5, respectively, to prepare isorubin / graphene oxide aerogel thin films with a thickness of 5 mm.

[0061] Example 6

[0062] The amount of isorubin / graphene oxide slurry in step (4) of Example 1 was adjusted to prepare isorubin / graphene oxide aerogel thin films with a thickness of 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, and 9 mm, respectively.

[0063] Table 1: Parameters of each example

[0064]

[0065]

[0066] To better understand the performance of the isorubin / graphene oxide aerogel thin films prepared in the above examples, tests and characterizations were performed, and the results are as follows:

[0067] 1. Characterization of isorubin / graphene oxide aerogel thin films - morphology

[0068] The isorubin / graphene oxide aerogel thin film samples obtained in each example were tested by table scanning electron microscopy to observe the microstructure of the samples. The specific operation method is to take a certain volume of thin film and stick it to the surface of a smooth mica sheet with conductive glue, and then observe after drying and gold spraying.

[0069] The scanning electron micrograph of the isorubin / graphene oxide aerogel thin film of Example 1 is shown in Figure 1 From which it can be directly observed that the obtained sample has a clear layered structure with obvious rough protrusions between the layers, which verifies the successful polymerization of isorubin between the graphene oxide layers. Figure 1

[0070] 2. Characterization of isorubin / graphene oxide aerogel thin films - structure

[0071] The isorubin / graphene oxide aerogel thin film samples obtained in each example were tested by X-ray diffraction, infrared spectroscopy, and X-ray photoelectron spectroscopy to characterize their chemical and physical structures.

[0072] The X-ray diffraction pattern of the isorubin / graphene oxide aerogel thin film of Example 1 is shown in Figure 2 Figure 2 ​​A large peak appeared at 20-25°, which corresponds to the interlayer spacing of 0.33-0.4 nm of the π-π interaction stacking, indicating the successful intercalation of the melanoidin into graphene oxide and the in-situ polymerization between the layers.

[0073] The element ratio distribution diagram of the melanoidin / graphene oxide aerogel film of Example 1 obtained by X-ray photoelectron spectroscopy is shown in Figure 3 Figure 3 The O element ratio is 14.17%, which is significantly reduced compared to 29.93% of the graphene oxide before the reaction, which indicates that the 1,8-dihydroxynaphthalene can reduce the graphene oxide during the reaction, thereby constructing a more complete and continuous conjugated structure, which is beneficial to the improvement of the electrical performance of the aerogel film.

[0074] 3. Characterization of melanoidin / graphene oxide aerogel film - yield

[0075] According to the test results of Example 1 and Example 2, the yield of the melanoidin / graphene oxide aerogel film obtained under different stirring times is shown in the following table: Figure 4 It can be seen that as the stirring time increases, the yield gradually increases, and when the stirring time is 20 h, the yield of the melanoidin / graphene oxide aerogel film gradually stabilizes at about 90%. Therefore, it is preferred to use 20 h of stirring treatment, which can ensure a higher yield while ensuring higher production efficiency.

[0076] 4. Characterization of melanoidin / graphene oxide aerogel film - electromagnetic shielding efficiency

[0077] The electromagnetic shielding efficiency of the melanoidin / graphene oxide aerogel film prepared in each example is determined by a vector network analyzer. First, a tablet press is used to obtain a film with a diameter of 13 mm and a thickness of 5 mm, and then a vector network analyzer is used to determine the electromagnetic wave shielding efficiency of the melanoidin / graphene oxide aerogel in the range of 8.2-12.4 GHz.

[0078] According to the test results of Example 1 and Example 3, the electromagnetic shielding efficiency of the melanoidin / graphene oxide aerogel film obtained by adding different amounts of sodium periodate is shown in the following table: Figure 5 As shown in the table, the electromagnetic shielding efficiency is the highest when the mass ratio of 1,8-dihydroxynaphthalene to sodium periodate is 1:0.8, which is due to the lower degree of polymerization of 1,8-dihydroxynaphthalene at a lower amount of addition; at a higher amount of addition, the graphene oxide is over-oxidized, thereby reducing the electrical performance of the melanoidin / graphene oxide aerogel film.

[0079] ​The electromagnetic shielding efficiency of the iso-black / oxidized graphene aerogel films obtained by using different amounts of graphene oxide can be compared according to the test results of Example 1 and Example 4, as shown in Table 1. Figure 6 As shown in Table 2, with the increase of the mass ratio of 1,8-dihydroxynaphthalene to graphene oxide, the electromagnetic wave shielding efficiency shows a trend of first increasing and then decreasing, and the best result is obtained when the mass ratio of 1,8-dihydroxynaphthalene to graphene oxide is 3:1. This is because the best effect of in-situ polymerization of iso-black intercalated graphene oxide can be achieved under the condition of 3:1, and when the amount of graphene oxide is too small or too large, the uniform aggregation and distribution of the two may occur, thereby failing to achieve the best intercalation effect.

[0080] The electromagnetic shielding efficiency of the iso-black / oxidized graphene aerogel films obtained by using different concentrations of 1,8-dihydroxynaphthalene solution can be compared according to the test results of Example 1 and Example 5, as shown in Table 3. Figure 7 As shown in Table 3, the electromagnetic shielding efficiency is the highest when the concentration of 1,8-dihydroxynaphthalene is 3 mg / mL. This is because it is difficult to achieve good dispersion of graphene oxide at a lower concentration, and at a higher concentration, iso-black itself may form agglomerates, greatly reducing its electromagnetic shielding efficiency.

[0081] The electromagnetic shielding efficiency of the iso-black / oxidized graphene aerogel films obtained by using different thicknesses can be compared according to the test results of Example 1 and Example 6, as shown in Table 4. Figure 8 As shown in Table 4, with the increase of the thickness, the electromagnetic shielding efficiency is enhanced.

[0082] The above-described examples only express the embodiments of the present application, and the description is more specific and detailed, but it should not be understood as limiting the scope of the patent of the present application. It should be noted that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are all within the scope of protection of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A method for preparing an isomelanin / graphene oxide layered aerogel film, characterized in that, Includes the following steps: S1: Dissolve 1,8-dihydroxynaphthalene in a solvent and then ultrasonically disperse and stir to obtain a 1,8-dihydroxynaphthalene solution; S2: Add graphene oxide aqueous dispersion to 1,8-dihydroxynaphthalene solution and stir to obtain 1,8-dihydroxynaphthalene / graphene oxide mixed solution; S3: Add sodium periodate solution to the 1,8-dihydroxynaphthalene / graphene oxide mixed solution, stir and react at room temperature for 4-48 h, then centrifuge and wash to obtain isomelanin / graphene oxide slurry; S4: The isomelanin / graphene oxide slurry is unidirectionally frozen and molded using liquid nitrogen, and then freeze-dried to obtain an isomelanin / graphene oxide aerogel film.

2. The method for preparing the isomelanin / graphene oxide layered aerogel film according to claim 1, characterized in that, The solvent in S1 is a mixture of acetonitrile and water, wherein the volume fraction of acetonitrile is 10-20% and the volume fraction of water is 80-90%.

3. The method for preparing the isomelanin / graphene oxide layered aerogel film according to claim 1, characterized in that, The concentration of the 1,8-dihydroxynaphthalene solution is 1–5 mg / mL.

4. The method for preparing the isomelanin / graphene oxide layered aerogel film according to claim 1, characterized in that, The amount of graphene oxide aqueous dispersion added in S2 is 20 mL, wherein the content of graphene oxide is calculated as the mass ratio of 1,8-dihydroxynaphthalene to graphene oxide being 1:1 to 4:

1.

5. The method for preparing the isomelanin / graphene oxide layered aerogel film according to claim 1, characterized in that, The concentration of the sodium periodate solution in S3 is 200 mg / mL, and the amount of sodium periodate solution added is based on a mass ratio of 1,8-dihydroxynaphthalene to sodium periodate of 1:0.5 to 1:

1.

6. The method for preparing the isomelanin / graphene oxide layered aerogel film according to claim 1, characterized in that, The stirring reaction time described in S3 is 20 hours.

7. The method for preparing the isomelanin / graphene oxide layered aerogel film according to claim 1, characterized in that, The centrifugation speed described in S3 is 12000–16000 r / min, and the centrifugation time is 5–10 min.

8. The method for preparing the isomelanin / graphene oxide layered aerogel film according to claim 1, characterized in that, The freeze-drying temperature described in S4 is -80℃.

9. A melanin / graphene oxide layered aerogel film, characterized in that, The isomelanin / graphene oxide layered aerogel film It is prepared by the preparation method according to any one of claims 1-8.

10. The isomelanin / graphene oxide layered aerogel film according to claim 9, characterized in that, The thickness of the isomelanin / graphene oxide layered aerogel film is 2 mm to 10 mm.

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