Method for preparing silicon carbide-graphene heterostructure filler and application of silicon carbide-graphene heterostructure filler in interface self-adaptive heat-conducting composite material

Abstract

The invention provides a method for preparing a silicon carbide-graphene heterostructure filler and application of the silicon carbide-graphene heterostructure filler in an interface self-adaptive heat-conducting composite material, and belongs to the technical field of composite materials, and the method comprises the following steps: (1) adding silicon carbide into water, stirring, carrying out ultrasonic treatment, centrifugally washing and drying to obtain hydroxylated silicon carbide powder; (2) adding graphene into water, homogenizing, adding TCEP and HEPES, stirring to prepare a dispersion liquid A, mixing lysozyme, HEPES and water to prepare a solution B, adding the solution B into the dispersion liquid A, and reacting to prepare lysozyme modified graphene powder; and (3) mixing the lysozyme modified graphene powder with hydroxylated silicon carbide for reaction to prepare the silicon carbide-graphene heterostructure filler. According to the invention, the high-thermal-conductivity silicon carbide-graphene heterostructure filler is prepared by means of surface modification and chemical crosslinking. The preparation method is green, rapid and safe, and can be applied to the technical field of multiple composite materials.

Description

Technical Field

[0001] The present invention relates to the technical field of composite materials, and in particular to a method for preparing a silicon carbide-graphene heterogeneous structure filler, and application of the structure filler in an interface self-adaptive thermal conductive composite material. Background Art

[0002] Silicon carbide is a polycrystalline crystal with high thermal conductivity and small thermal expansion coefficient. Graphene is a single atomic layer material with a hexagonal honeycomb lattice of carbon atoms and has good electrical and thermal conductivity.

[0003] The existing graphene-silicon carbide composite materials are all used in functional ceramic materials to prepare conductive ceramics. Or as described in CN115928043A, graphene / silicon carbide composite materials are prepared by chemical vapor deposition technology and used in electromagnetic shielding equipment.

[0004] If silicon carbide and graphene are combined with lysozyme to prepare silicon carbide-graphene heterostructure fillers, which have good thermal and physical properties, they have broad application prospects as raw materials for interface adaptive thermal conductive composite materials. Summary of the invention

[0005] In view of the shortcomings of the existing related technologies, the present invention provides a method for preparing silicon carbide-graphene heterostructure fillers, which uses a chemical cross-linking method to make silicon carbide grow on the surface of graphene through covalent bonds. The method is green, fast and safe, and the prepared filler has excellent performance.

[0006] To this end, in a first aspect, the present invention provides a method for preparing a silicon carbide-graphene heterostructure filler, comprising the following steps:

[0007] (1) Silicon carbide is added to water, stirred, and then ultrasonicated. Hydroxylated silicon carbide powder is obtained after centrifugation, washing, and freeze-drying.

[0008] (2) Add graphene to water, homogenize, add tri(2-carboxyethyl)phosphine (TCEP) and 4-hydroxyethylpiperazineethanesulfonic acid (HEPES) and stir to obtain dispersion A, mix lysozyme, HEPES and water to obtain solution B, add solution B to dispersion A, adjust to acidic to react, wash and filter, and vacuum dry to obtain lysozyme-modified graphene powder.

[0009] (3) Add lysozyme-modified graphene powder into water, stir and sonicate, add hydroxylated silicon carbide into water, stir again and sonicate, adjust the solution to acidity and stir to complete the reaction, and then filter, wash and vacuum dry to obtain silicon carbide-graphene heterostructure filler.

[0010] Furthermore, in step (1), the silicon carbide particle size is 300-700 nm, preferably 500 nm, the stirring time after adding water is 5-15 minutes, the ultrasonic treatment power is 120-180 W, and the ultrasonic treatment time is 30-60 minutes.

[0011] Furthermore, during the centrifugation process in step (1), the speed of the centrifuge is 1000-2000 rpm; and the centrifugation time is 5-10 minutes.

[0012] Furthermore, the washing process in step (1) is to use deionized water to wash the precipitate 2-5 times.

[0013] Furthermore, in the freeze-drying process of step (1), the freeze-drying temperature is ≤-60°C, and the freeze-drying time is 10-20 hours.

[0014] Furthermore, the graphene in step (2) is graphene nanosheets; in the preparation process of dispersion A, 0.5-1 g of graphene, 0.005-0.01 mol of TCEP, and 0.001-0.002 mol of HEPES are used per 100 mL of water; the homogenization process is treated with a high shear dispersing emulsifier for 30-60 minutes; and the dispersion is stirred for 5-15 minutes.

[0015] Furthermore, in the process of preparing the solution B in step (2), 0.2-0.5 g of lysozyme and 0.001-0.002 mol of HEPES are used for every 100 mL of water, and the volumes of solution B and dispersion A are equal; the solution must be continuously stirred during the process of adding the solution to the dispersion to ensure that the graphene and lysozyme are mixed while being dispersed.

[0016] The above-mentioned TCEP is a thiol reducing agent. When the central P comes into contact with water molecules, it will capture electrons, making the H of the water molecules reducing, causing the disulfide bonds inside the lysozyme molecules to be reduced, and then the molecules fold and self-assemble to form a phase-change lysozyme PTL. The PTL is then combined and transformed into a two-dimensional nanofilm that can be stably adsorbed on the solid-liquid and liquid-gas interfaces. The use of lysozyme to modify GNPs can reduce the degree of self-polymerization of GNPs and improve their affinity with substrates such as cellulose. HEPES is a hydrogen ion buffer that ensures pH stability and may have a partial effect of assisting TCEP without reacting with lysozyme.

[0017] Furthermore, in step (2), the mixed solution is adjusted to an acidic process, pH = 4.5-5.5; the reaction time is 1.5-3 hours, and the reaction temperature is room temperature. Studies have found that for the modification process of phase-change lysozyme, low pH is more suitable for modifying nanomaterials, and high pH is suitable for modifying large-sized materials. Because the graphene sheets here are relatively large in size, a higher pH value is used. Step (3) The growth of silicon carbide belongs to the nanoscale, and a lower pH value is used.

[0018] Furthermore, the washing and filtering process in step (2) uses deionized water for washing and a mixed cellulose ester membrane with a pore size of 0.45-1.0 micrometers for filtering, and needs to be repeated 3-6 times.

[0019] Furthermore, in step (2), the vacuum drying process temperature is ≤-60°C, and the vacuum drying time is 10-20 hours.

[0020] Furthermore, in step (3), the lysozyme-modified graphene powder is added to water and the mixing time is 5-15 minutes, the ultrasonic treatment power is 120-180 W, and the ultrasonic treatment time is 20-30 minutes.

[0021] Furthermore, in step (3), during the process of adding the hydroxylated silicon carbide to the solution and stirring again and then ultrasonicating, the mixing and stirring time is 5-15 minutes, the ultrasonic treatment power is 120-180W, and the ultrasonic treatment time is 30-60 minutes.

[0022] Furthermore, in the step (3), the solution is adjusted to acidity and stirred during the reaction. The pH of the reaction solution is adjusted to 1-1.5 using a 36.5% by mass hydrogen chloride solution; the stirring time is 1.5-3 hours; and the stirring temperature is room temperature. In the step (1), silicon carbide is hydroxylated. In Si-OH, Si atoms have a larger radius and a weaker ability to bind H atoms, making them more chemically active. In the step (3), -COOH on the surface of lysozyme-modified graphene (LmGNP) undergoes a dehydration condensation reaction with Si-OH on the surface of SiC-OH to form O=CO-Si, thereby promoting the growth of SiC-OH on the surface of LmGNP.

[0023] Furthermore, in the filtering, washing and vacuum drying process of step (3), a polypropylene membrane with a pore size of 0.45-1.0 μm is used for filtering; dilute hydrochloric acid with a pH of 1.5 is used for washing 3-6 times; and the vacuum drying temperature is 90-100° C. and the time is 10-15 hours.

[0024] Furthermore, in step (3), the mass ratio of lysozyme-modified graphene powder to hydroxylated silicon carbide is (1-4):(1-4), and the most preferred ratio is 1:1.

[0025] The second aspect of the present invention provides a silicon carbide-graphene heterostructure filler, which is obtained by the preparation method of the present invention.

[0026] The third aspect of the present invention provides the use of the silicon carbide-graphene heterostructure filler in an interface self-adaptive thermal conductive composite material.

[0027] In view of the shortcomings of the prior art, the present invention proposes a method for preparing a silicon carbide-graphene heterostructure filler, which has the following significant progress and improvement:

[0028] (1) In the preparation method provided by the present invention, small particles of silicon carbide adsorbed on the surface of silicon carbide are removed by ultrasound and centrifugation, so that the final hydroxylated silicon carbide has a uniform particle size, thereby avoiding the problem of desorption or re-sorption of small particles of silicon carbide during the synthesis of silicon carbide-graphene heterostructure fillers, which leads to a decrease in the total adsorption amount.

[0029] (2) By using lysozyme to modify graphene and hydroxylated silicon carbide and mixing them under acidic conditions, graphene and silicon carbide generate Si-OC=O through dehydration condensation of -COOH and Si-OH, forming a strong covalent bond cross-linking structure between the two, giving the material a stable three-dimensional structure without destroying the lysozyme modification layer.

[0030] (3) The present invention prepares a silicon carbide-graphene heterostructure filler with excellent performance by surface modification and chemical cross-linking. The preparation method is green, fast and safe, and can be applied to multiple composite material technology fields.

[0031] (4) An interface adaptive thermal conductive composite material (see Example 1 for details) prepared using the heterogeneous structure filler has excellent thermal conductivity and adaptability. By adding ethanol aqueous solution, the surface of the composite material is softened and adaptive, so that the thermal conductive network adapts to surfaces of different roughness, thereby optimizing the thermal conductivity and adaptability of the material.

[0032] (5) The interface adaptive thermal conductive composite material has a directional thermal conductivity of 150-210 W·m depending on the filler content. -1 ·K -1 , axial thermal conductivity is 4-12 W·m -1 ·K -1 , tensile strength is 20-32 MPa, resistivity is 2-10 Ω·cm, and there is good Joule thermal effect and interface adaptability, with excellent performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0034] Figure 1This is a scanning electron microscope (SEM) image of 500 nm silicon carbide before treatment in Example 1, wherein (b) is a 60-fold magnification of a portion of (a).

[0035] Figure 2 1 is a scanning electron microscope (SEM) image of hydroxylated silicon carbide in Example 1, wherein (b) is a partial magnification of (a) by 60 times.

[0036] Figure 3 This is a scanning electron microscope (SEM) image of the silicon carbide-graphene heterostructure filler prepared in Example 1, wherein (b) is a partial magnification of (a) by 60 times.

[0037] Figure 4 These are Fourier transform infrared spectroscopy (FTIR) images of graphene (GNP), lysozyme, lysozyme-modified graphene (LmGNP), and silicon carbide-graphene heterostructure filler (SiC@LmGNP) in Example 1.

[0038] Figure 5 Fourier transform infrared spectroscopy (FTIR) images of hydroxylated silicon carbide (SiC-OH) and lysozyme modified graphene (LmGNP) in different ratios in Examples 1, 2, and 3, as well as SiC-OH and LmGNP alone.

[0039] Figure 6 This is the thermal weight loss-temperature curve of S1L1xC2P1-HS.

[0040] Figure 7 This is the FLIR image of the Joule heating effect of S1L180C2P1-HS at 10V.

[0041] Figure 8 The surface roughness characterization results of S1L180C2P1-HS using a metallographic microscope. (a) is the actual image, (b) is the roughness distribution diagram, and (c) and (d) are local position-roughness data diagrams at two random locations.

[0042] Fig. 9 The characterization results of the surface roughness of the Al2O3 heating element using a metallographic microscope. (a) is the actual image, (b) is the roughness distribution diagram, and (c) and (d) are local position-roughness data diagrams at two random locations. DETAILED DESCRIPTION

[0043] In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following will be described in detail with reference to the accompanying drawings and specific embodiments. The raw materials used in the embodiments of the present invention are all commercially available commodities, and the raw materials are easily available. If industrialized, they can be enlarged in equal proportions.

[0044] Embodiment 1:

[0045] (1) 80 mL of deionized water and 1 g of silicon carbide (500 nm particle size) were mixed and stirred for 5 minutes, and ultrasonicated at 150 W for 40 minutes to obtain a mixed solution. The mixed solution was centrifuged at 1500 rpm for 5 minutes to obtain a precipitate. The precipitate was washed 3 times with deionized water to remove a small amount of silicic acid generated by the reaction, and then freeze-dried in a freeze dryer at -60 ° C for 12 h to obtain hydroxylated silicon carbide powder.

[0046] (2) Take 0.5g of graphene and add it to 100g of deionized water. Treat it in a homogenizer for 40 minutes, add 1.43g of TCEP and 0.238g of HEPES, stir for 5 minutes, and the obtained liquid is recorded as dispersion A. Take 0.2g of lysozyme, 0.238g of HEPES and 100g of deionized water and mix them evenly, which is recorded as solution B. Add solution B to dispersion A while stirring, then adjust the pH to 5.0, and react at room temperature for 2h. Then wash the mixture with deionized water and filter it with a mixed cellulose ester membrane with a pore size of 0.8μm. Repeat the washing step 5 times. Finally, vacuum dry it in a freeze dryer at -60°C for 12h to obtain lysozyme-modified graphene powder.

[0047] (3) Take an appropriate amount of lysozyme-modified graphene powder and 80 mL of deionized water, mix and stir for 5 minutes, and then ultrasonicate at 150 W for 20 minutes to obtain a first mixed solution. Take an appropriate amount of hydroxylated silicon carbide powder, add it to the above first mixed solution, mix and stir for 5 minutes, and then ultrasonicate at 150 W for 40 minutes to obtain a second mixed solution. Subsequently, a small amount of 36.5 wt% hydrochloric acid solution is used to adjust the pH of the second mixed solution to 1.5, and stirred at room temperature for 2 hours. The second mixed solution after pH adjustment is filtered through a PP membrane with a pore size of 0.8 μm and washed three times with a dilute hydrochloric acid solution with a pH of 1.5. Then, vacuum dry at 90 ° C for 12 hours to remove the adsorbed water and HCl to obtain silicon carbide-graphene heterostructure filler powder. In the above process, the mass ratio of hydroxylated silicon carbide and lysozyme-modified graphene is 1:1.

[0048] The attached figure shows the analysis images of the materials during and after the preparation. Figure 1 This is a scanning electron microscope (SEM) image of 500nm silicon carbide before treatment in Example 1. (b) is a partial magnification of (a) by 60 times. It can be seen that small particles are adsorbed on the surface.

[0049] Figure 2 This is a scanning electron microscope (SEM) image of hydroxylated silicon carbide in Example 1, where (b) is a partial magnification of (a) by 60 times. It can be seen that the surface is smoother because the surface has been hydroxylated; at the same time, the number of small particles is reduced because the small particles of silicon carbide are desorbed and screened out during the ultrasonic and centrifugal process.

[0050] Figure 3 This is a scanning electron microscope (SEM) image of the silicon carbide-graphene heterostructure filler prepared in Example 1, where (b) is a 60-fold magnification of a part of (a). It can be seen that silicon carbide grows on the graphene surface.

[0051] Figure 4 The Fourier transform infrared spectroscopy (FTIR) images of graphene (GNP), lysozyme, lysozyme-modified graphene (LmGNP), and silicon carbide-graphene heterostructure filler (SiC@LmGNP) in Example 1. It can be seen that there are -OH and -NH2 on the surface of lysozyme, so the -1 There is an absorption peak at 1068cm. However, GNP is a pure carbon structure, so no obvious absorption peak can be found. A new absorption peak appears in the spectrum of LmGNP, 1068cm -1 The characteristic absorption peaks at 3275 and 1442 cm are caused by the CO bending of the primary alcohol. -1 The peaks at 1535 and 1662 cm-1 are related to the OH stretching and COH bending of the hydroxyl groups. -1 The characteristic peak at 1081cm is generated by -NH2 bending. -1 and 790cm -1 New peaks appeared at , corresponding to Si-OC=O and Si-C, respectively. FTIR results show that SiC-OH and LmGNP react under acidic conditions through the dehydration condensation reaction of Si-OH and -COOH to produce Si-OC=O, which then cross-linked and combined to form SiC@LmGNP. At the same time, the strong acidic reaction conditions did not destroy the lysozyme modification layer.

[0052] A mixed solution of acidic cellulose and polyvinyl alcohol was added to the silicon carbide-graphene heterostructure filler (SiC@LmGNP) prepared in Example 1 to prepare an interface adaptive thermal conductive composite material, and thermal and mechanical properties tests were performed. The specific steps are as follows:

[0053] 1) Preparation of cellulose (CNF) dispersion

[0054] First, 2 g of cellulose was dispersed in 400 mL of deionized water containing 0.032 g of TEMPO and 0.2 g of NaBr, and the dispersion was obtained by continuous stirring at room temperature. NaClO solution was added dropwise to the dispersion, and the amount of NaClO added per gram of cellulose was 10 mmol to start the oxidation reaction. During the oxidation process, 0.5 M NaOH was continuously added, and the pH value was maintained at 10 to obtain a TEMPO oxidized cellulose dispersion. The TEMPO oxidized cellulose was filtered and washed with deionized water, and the washing step was repeated 3 times. After treatment, the TEMPO oxidized cellulose suspension was sonicated at 300 W power in an ice bath for 15 min. Finally, the unoxidized cellulose was removed by centrifugation at 10,000 rpm for 10 min to obtain a CNF dispersion with a concentration of about 1 wt%, which was stored at 4 °C.

[0055] 2) Preparation of polyvinyl alcohol (PVA) solution

[0056] Weigh 200 mg of PVA particles, add them into 100 mL of deionized water, and stir at 95 °C for 2 h to obtain 2 mg·mL -1 PVA dispersion.

[0057] 3) Preparation of CNF / PVA-H mixed solution

[0058] Take 2 g of 1 wt% CNF suspension and place it in a test tube. Then take 5 mL of 2 mg mL -1 PVA dispersion. After mixing the two, use 36.5wt% hydrochloric acid to adjust the pH to 1.5 (about 0.08mL of hydrochloric acid) to obtain a CNF / PVA-H mixed solution. It should be noted that due to the presence of a large amount of -COOH on the surface of CNF, the CNF / PVA-H mixed solution is not stable. After preparation, continuous ultrasound is required to keep it in a dispersed state and use it in time.

[0059] 4) Preparation of interface adaptive thermal conductive composite materials

[0060] Take an appropriate amount of SiC@LmGNP and mix it with CNF / PVA-H dispersion, and ultrasonically treat it for 40 minutes at 0℃ and normal pressure. Then, pour the mixed solution onto the PTFE film and place it in a fume hood for 24 hours to dry and shape it. After demolding, place the film between two copper plates and keep it in a 90°C oven for 4 hours to remove the remaining water and HCl. After the material cools to room temperature, take a small amount of 95wt% ethanol aqueous solution to moisten the composite material to make it semi-gelled, and place it between the heat sink and the heating element, and apply a certain pressure to the heat sink so that the semi-gelled material fits tightly to the surface of the heat sink and the heating element. Finally, let it stand for 6 hours to allow the 95wt% ethanol aqueous solution to evaporate completely and the composite material to be reshaped. During the preparation process, the mass of SiC@LmGNP is ensured to account for 80wt% of the composite material.

[0061] The naming method of interface adaptive thermal conductive composite materials is as follows: S a L b xCyPz-HG, where a and b represent the ratio of SiC and LmGNP, and x represents S a L b The mass percentage in the composite material, y and z represent the mass ratio of CNF and PVA solid matter, H represents after acidic treatment, and S represents interface adaptive material. For example, the composite material prepared in Example 1 is named S1L180C2P1-HS, which means that SiC@LmGNP accounts for 80wt% of the composite film, and solid CNF:PVA=2:1 in the remaining mass, acidic conditions, and composite material after interface adaptive treatment.

[0062] The directional thermal conductivity of the S1L180C2P1-HS material prepared in Example 1 is 175.15 W·m -1 ·K -1 , the axial thermal conductivity is 8.50 W·m -1 ·K -1 , specific heat capacity is 6.33 J / (kg·℃), tensile strength is 24.23 MPa, and resistivity is 2.19 Ω·cm.

[0063] Figure 6 The thermal weight loss-temperature curve of S1L1xC2P1-HS. It can be seen that the thermal decomposition trend of all materials is that the mass loss before 150℃ is due to the volatilization of water in the composite material and the depolymerization of part of cellulose; the significant mass loss in the range of 150℃ to 340℃ is caused by the pyrolysis of cellulose to produce small molecular gases and large molecular condensable volatiles; and the mass decrease after 340℃ is the slow decomposition of the residue; finally, char, ash and LmGNP pyrolysis products are produced. When the thermal weight loss mass ratio is 90%, the temperatures of S1L180C2P1-HS to S1L150C2P1-HS are 277.5℃, 291.2℃, 300.8℃ and 315.7℃, respectively, with a significant increase. This may be related to the increase in filler content, the increase in Si-OC=O and hydrogen bond density inside the material. The cross-linking effect of these two chemical bonds enhances the thermal stability of the material, causing its thermal decomposition temperature to gradually increase. S1L1xC2P1-HS can meet the operating temperature of most electronic equipment (below 200℃).

[0064] Figure 7 This is the FLIR image of the Joule heating effect of S1L180C2P1-HS at a voltage of 10V. According to the Joule heating effect experiment, the material has the characteristics of fast heating up, fast cooling and rapid thermal response.

[0065] Figure 8The results of the metallographic microscope surface roughness characterization of S1L180C2P1-HS. (a) is the actual image, (b) is the roughness distribution diagram, (c) and (d) are local position-roughness data diagrams at two random positions. Comparing the composite material before and after the surface adaptive treatment, the adaptive treatment makes its roughness smaller and the roughness distribution more uniform. Compared with Fig. 9 The characterization results of the contact surface of the Al2O3 heating element show that the characteristics of the two are similar, and the surface roughness parameters are almost the same, indicating that the surface characteristics of the two are similar, which can be explained by the fact that it adapts to the surface of the heating element, making its own roughness similar to that of the heating element. This shows that S1L180C2P1-HS has a good interface adaptation effect.

[0066] Fig. 9 The results of the metallographic microscope surface roughness characterization of the Al2O3 heating element. (a) is the actual image, (b) is the roughness distribution diagram, (c) and (d) are the local position-roughness data diagrams of two random positions. Figure 8 For comparison.

[0067] Table 1 is a summary of the surface roughness of S1L180C2P1-HS and Al2O3 heating sheet. It can be seen that the roughness of S1L180C2P1-HS after adaptation is well matched with the Al2O3 heating sheet.

[0068] Table 1

[0069]

[0070] Embodiment 2:

[0071] (1) 100 mL of deionized water and 1 g of silicon carbide (500 nm particle size) were weighed, mixed and stirred for 10 minutes, and ultrasonicated at 180 W for 60 minutes to obtain a mixed solution. The mixed solution was centrifuged at 1500 rpm for 10 minutes to obtain a precipitate. The precipitate was washed with deionized water 5 times to remove a small amount of silicic acid generated by the reaction, and then freeze-dried in a freeze dryer at -60 ° C for 15 hours to obtain hydroxylated silicon carbide powder.

[0072] (2) Take 1g of graphene and add it to 200g of deionized water. Treat it in a homogenizer for 60 minutes, add 2.86g of TCEP and 0.476g of HEPES, stir for 10 minutes, and the obtained liquid is recorded as dispersion A. Take 0.4g of lysozyme, 0.476g of HEPES and 200g of deionized water and mix them evenly, which is recorded as solution B. Add solution B to dispersion A while stirring, then adjust the pH to 5.0, and react at room temperature for 3h. Then wash the mixture with deionized water and filter it with a mixed cellulose ester membrane with a pore size of 0.8μm. Repeat the washing step 5 times. Finally, vacuum dry it in a freeze dryer at -60°C for 15h to obtain lysozyme-modified graphene powder.

[0073] (3) Take an appropriate amount of lysozyme-modified graphene powder and 100 mL of deionized water, mix and stir for 5 minutes, and then ultrasonicate at 180 W for 30 minutes to obtain a first mixed solution. Take an appropriate amount of hydroxylated silicon carbide powder, add it to the above first mixed solution, mix and stir for 5 minutes, and then ultrasonicate at 180 W for 40 minutes to obtain a second mixed solution. Subsequently, a small amount of 36.5 wt% hydrochloric acid solution is used to adjust the pH of the second mixed solution to 1.5, and stirred at room temperature for 3 hours. The second mixed solution after pH adjustment is filtered using a PP membrane with a pore size of 0.8 μm and washed three times with a dilute hydrochloric acid solution with a pH of 1.5. Then, vacuum dry at 95 ° C for 12 hours to remove the adsorbed water and HCl to obtain silicon carbide-graphene heterostructure filler powder. In the above process, the mass ratio of hydroxylated silicon carbide and lysozyme-modified graphene is 2:1.

[0074] The same method as in Example 1 was used to prepare the silicon carbide-graphene heterostructure filler prepared in Example 2 into an interface adaptive thermal conductive composite material. The measured directional thermal conductivity was 170.75 W·m -1 ·K -1 , the axial thermal conductivity is 8.21 W·m -1 ·K -1 , specific heat capacity is 6.21 J / (kg·℃), tensile strength is 21.65 MPa, and resistivity is 2.34Ω·cm.

[0075] Embodiment 3:

[0076] (1) 80 mL of deionized water and 1 g of silicon carbide (500 nm particle size) were mixed and stirred for 5 minutes, and ultrasonicated at 150 W for 40 minutes to obtain a mixed solution. The mixed solution was centrifuged at 1500 rpm for 5 minutes to obtain a precipitate. The precipitate was washed 3 times with deionized water to remove a small amount of silicic acid generated by the reaction, and then freeze-dried in a freeze dryer at -60 ° C for 12 h to obtain hydroxylated silicon carbide powder.

[0077] (2) Take 0.5g of graphene and add it to 100g of deionized water. Treat it in a homogenizer for 40 minutes, add 1.43g of TCEP and 0.238g of HEPES, stir for 5 minutes, and the obtained liquid is recorded as dispersion A. Take 0.2g of lysozyme, 0.238g of HEPES and 100g of deionized water and mix them evenly, which is recorded as solution B. Add solution B to dispersion A while stirring, then adjust the pH to 5.0, and react at room temperature for 2h. Then wash the mixture with deionized water and filter it with a mixed cellulose ester membrane with a pore size of 0.8μm. Repeat the washing step 5 times. Finally, vacuum dry it in a freeze dryer at -60°C for 12h to obtain lysozyme-modified graphene powder.

[0078] (3) Take an appropriate amount of lysozyme-modified graphene powder and 80 mL of deionized water, mix and stir for 5 minutes, and then ultrasonicate at 150 W for 20 minutes to obtain a first mixed solution. Take an appropriate amount of hydroxylated silicon carbide powder, add it to the above first mixed solution, mix and stir for 5 minutes, and then ultrasonicate at 150 W for 40 minutes to obtain a second mixed solution. Subsequently, a small amount of 36.5 wt% hydrochloric acid solution is used to adjust the pH of the second mixed solution to 1.5, and stirred at room temperature for 2 hours. The second mixed solution after pH adjustment is filtered using a PP membrane with a pore size of 0.8 μm and washed three times with a dilute hydrochloric acid solution with a pH of 1.5. Then, vacuum dry at 90 ° C for 12 hours to remove the adsorbed water and HCl to obtain silicon carbide-graphene heterostructure filler powder. In the above process, the mass ratio of hydroxylated silicon carbide and lysozyme-modified graphene is 1:2.

[0079] The same method as in Example 1 was used to prepare the silicon carbide-graphene heterostructure filler prepared in Example 3 into an interface adaptive thermal conductive composite material. The measured directional thermal conductivity was 172.72 W·m -1 ·K -1 , the axial thermal conductivity is 7.93 W·m -1 ·K -1 , specific heat capacity is 6.25 J / (kg·℃), tensile strength is 26.11 MPa, and resistivity is 2.02 Ω·cm.

[0080] Figure 5 The following are Fourier transform infrared spectroscopy (FTIR) images of different ratios of hydroxylated silicon carbide (SiC-OH) and lysozyme-modified graphene (LmGNP) in Examples 1, 2, and 3, as well as SiC-OH and LmGNP alone. The filler with a mass ratio of SiC-OH to LmGNP of 1:1 is named S1L1 (Example 1), and S2L1 (Example 2) and S1L2 (Example 3) are obtained in the same way. It can be seen from the FTIR images that for the sample containing LmGNP, the wavelengths of 1660-1600 and 1570-1550 cm -1 There are two -NH3+ The peaks produced by bending are at 1410, 1600, and 1560 cm -1 There are two peaks at 2925 and 2860 cm-1 due to -COO- stretching. -1 There are two peaks generated by -CH2- stretching at 832cm. The above peaks are characteristic peaks of the phase transition lysozyme modification layer (PTL), indicating that the strong acidic environment does not destroy the modification layer, and the concentration of SiC-OH has no effect on PTL. For materials containing SiC-OH, at 832cm -1 There are characteristic peaks near 940cm, which are caused by C-Si stretching, indicating that SiC exists in the material system and the acidic reaction environment does not destroy SiC. -1 There are characteristic peaks generated by Si-O stretching at 1632 and 1428 cm for pure SiC-OH, which may be due to the oxidation of part of CC to C=C under the action of ultrasound during pretreatment. Compared with pure LmGNP and SiC-OH, S2L1, S1L1, and S1L2 have new peaks, namely at 1117 cm -1 There is a characteristic peak generated by Si-OC stretching nearby, indicating that SiC-OH reacted with -COOH on the surface of LmGNP to produce a new Si-OC bond, proving the cross-linking effect between the two. Comparing the Si-OC peak intensities of S2L1, S1L1, and S1L2, it can be found that the peak intensities of S2L1 and S1L1 are larger, indicating that the internal cross-linking effect of these two materials is stronger. Experiments have found that with the increase of SiC content, the rigidity and brittleness of the composite material become stronger, which in turn leads to poor adaptability of the material interface. Therefore, S1L1 can ensure that the material has a good thermal conductivity network while also maintaining a certain flexibility to adapt to different interfaces, which is the best ratio.

[0081] Comparative Example 1:

[0082] The preparation process of the heterogeneous structure material is the same as that of Example 1, except that HEPES is not added during the preparation process. Since the pH stability in the reaction environment cannot be ensured, the prepared material has many structural defects and the material performance is reduced.

[0083] Comparative Example 2:

[0084] The preparation process of the heterostructure material is the same as that of Example 1, except that the pH value in steps (2) and (3) of the preparation process is 5.0. Due to the high pH value in step (3), the growth effect of silicon carbide is poor, and the performance of the prepared material is reduced.

[0085] Comparative Example 3:

[0086] The preparation process of the heterostructure material is the same as that of Example 1, except that the pH of steps (2) and (3) of the preparation process is 1.5. Due to the low pH value of step (2), the effect of lysozyme modification of graphene is poor, and the performance of the prepared material is reduced.

[0087] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for preparing a silicon carbide-graphene heterostructure filler, characterized in that: The following steps are involved: (1) Add silicon carbide to water, stir, and then sonicate, and then centrifuge, wash, and freeze-dry to obtain hydroxylated silicon carbide powder; (2) adding graphene to water, homogenizing, adding TCEP and HEPES and stirring to obtain dispersion A, mixing lysozyme, HEPES and water to obtain solution B, adding solution B to dispersion A, adjusting to acidic to react, washing and filtering, and vacuum drying to obtain lysozyme-modified graphene powder; (3) Add lysozyme-modified graphene powder into water, stir and sonicate, add hydroxylated silicon carbide into water, stir again and sonicate, adjust the solution to acidity and stir to complete the reaction, and then filter, wash and vacuum dry to obtain silicon carbide-graphene heterostructure filler.

2. The method for preparing a silicon carbide-graphene heterostructure filler according to claim 1, characterized in that: In step (1), the silicon carbide particle size is 300-700 nm, the stirring time after adding water is 5-15 minutes, the ultrasonic treatment power is 120-180 W, and the ultrasonic treatment time is 30-60 minutes.

3. The method for preparing a silicon carbide-graphene heterostructure filler according to claim 1, characterized in that: During the centrifugation process in step (1), the centrifuge speed is 1000-2000 rpm; the centrifugation time is 5-10 minutes; And / or, the washing process in step (1) is to wash the precipitate with deionized water 2-5 times; And / or, in the freeze-drying process of step (1), the freeze-drying temperature is ≤-60°C and the freeze-drying time is 10-20 hours.

4. The method for preparing a silicon carbide-graphene heterostructure filler according to claim 1, characterized in that: The graphene in step (2) is graphene nanosheets; in the preparation process of dispersion A, 0.5-1 g of graphene, 0.005-0.01 mol of TCEP, and 0.001-0.002 mol of HEPES are used per 100 mL of water; the homogenization process is treated with a high shear dispersing emulsifier for 30-60 minutes; the dispersion is stirred for 5-15 minutes; And / or, in the process of preparing the solution B in step (2), 0.2-0.5 g of lysozyme and 0.001-0.002 mol of HEPES are used per 100 mL of water, and the volumes of solution B and dispersion A are equal.

5. The method for preparing a silicon carbide-graphene heterostructure filler according to claim 1, characterized in that: The mixed solution in step (2) is adjusted to an acidic process, pH = 4.5-5.5; the reaction time is 1.5-3 hours, and the reaction temperature is room temperature; And / or, the washing and filtering process in step (2) is performed using deionized water for washing and filtering through a mixed cellulose ester membrane with a pore size of 0.45-1.0 μm, and the process is repeated 3-6 times; And / or, the vacuum drying process temperature in step (2) is ≤-60°C, and the vacuum drying time is 10-20 hours.

6. The method for preparing a silicon carbide-graphene heterostructure filler according to claim 1, characterized in that: In step (3), the lysozyme-modified graphene powder is added to water and mixed for 5-15 minutes, the ultrasonic treatment power is 120-180 W, and the ultrasonic treatment time is 20-30 minutes; And / or, in step (3), during the process of adding the hydroxylated silicon carbide to the solution and stirring again and then ultrasonicating, the mixing and stirring time is 5-15 minutes, the ultrasonic treatment power is 120-180 W, and the ultrasonic treatment time is 30-60 minutes.

7. The method for preparing a silicon carbide-graphene heterostructure filler according to claim 1, characterized in that: In the step (3), during the acidic adjustment of the solution and the stirring reaction, the pH of the reaction solution is adjusted to 1-1.5 using a 36.5% by mass hydrogen chloride solution; the stirring time is 1.5-3 hours; and the stirring temperature is room temperature.

8. The method for preparing a silicon carbide-graphene heterostructure filler according to claim 1, characterized in that: In the filtering, washing and vacuum drying process of step (3), a polypropylene membrane with a pore size of 0.45-1.0 μm is used for filtering; dilute hydrochloric acid with a pH of 1.5 is used for washing 3-6 times; the vacuum drying temperature is 90-100°C and the time is 10-15 hours; And / or, in step (3), the mass ratio of lysozyme-modified graphene powder to hydroxylated silicon carbide is (1-4):(1-4), and the most preferred ratio is 1:

1.

9. The silicon carbide-graphene heterostructure filler prepared according to the method according to any one of claims 1 to 8.

10. Use of the silicon carbide-graphene heterostructure filler according to claim 9 in an interface adaptive thermal conductive composite material.

Images