Preparation method of graphene / molybdenum disulfide field-induced phase change material

Abstract

The invention belongs to the technical field of nonlinear conductive composite materials, and discloses a preparation method of a graphene / molybdenum disulfide field-induced phase change material. The method comprises the following steps: adding molybdenum disulfide powder and graphene powder into deionized water, carrying out ultrasonic treatment, then stirring for 1-1.5 hours, filtering and freeze-drying to obtain GN / MoS2 hybrid powder; mixing epoxy resin with the GN / MoS2 hybrid powder, adding absolute ethyl alcohol to adjust the viscosity, and stirring until the absolute ethyl alcohol is completely evaporated; then adding a curing agent 2E4MZ, and continuously stirring; and uniformly smearing the mixture obtained in the step (2) on a PCB, standing and curing in a vacuum environment to obtain the graphene / molybdenum disulfide field-induced phase change composite material. Graphene and MoS2 are combined to construct a hierarchical structure system, excellent non-linear conductivity can be achieved under the condition of low filler content, the risk that destructive strong electromagnetic pulses damage devices is reduced, and potential application prospects are achieved in the aspects of light weight and high precision.

Description

Technical Field

[0001] The present invention relates to the technical field of nonlinear conductive composite materials, and in particular to a method for preparing a graphene / molybdenum disulfide field-induced phase change material. Background Art

[0002] The formation mechanism of nonlinear conductive materials mainly includes the influence of factors such as the content, morphology, size of the doped filler, as well as multi-dimensional co-doping and surface modification on the electrical properties. These materials form nonlinear conductivity characteristics through the interaction between the doped filler and the polymer matrix, thereby effectively regulating the electric field distribution and reducing the electric field concentration phenomenon. They are widely used to solve the problem of electric field concentration, especially in the fields of cable accessory insulation and high-voltage motor stator insulation. Currently, the most widely studied nonlinear conductive materials are mainly composites composed of insulating polymers and micro-piezoresistive fillers (such as ZnO and SiC). Generally, a filler concentration of at least 30vol% is required for the composite material to construct an effective conductive path and exhibit significant nonlinear conductivity characteristics. However, excessively high doping rates can easily lead to an increase in the relative dielectric constant, which in turn affects data transmission speed and causes signal delay problems.

[0003] Molybdenum disulfide (MoS2) is a two-dimensional transition metal dichalcogenide with a unique "sandwich" structure. MoS2 interacts between layers through weak van der Waals forces, while strong covalent bonds exist within the layers. This material exhibits excellent electrical conductivity, optical properties, and catalytic activity, and holds significant potential for applications in energy storage and conversion, optoelectronics, and catalysis. MoS2, with its exceptional electronic properties, environmental adaptability, and sustainability, holds great promise for application in the semiconductor industry. Graphene (GN) is a two-dimensional crystalline material composed of a single layer of carbon atoms. Its unique honeycomb structure, with carbon atoms arranged in a tight hexagonal pattern and connected by single bonds, forms a robust electron network. This gives graphene a tunable electronic structure and high electrical conductivity. Graphene's three-dimensional conductive network significantly reduces the percolation threshold and facilitates the dispersion and conduction of the electric field. Semiconductor fillers, on the other hand, possess superior nonlinear coefficients. The combination of these two materials promises to yield superior performance at low filler loadings. Summary of the Invention

[0004] To solve the above technical problems, the present invention provides a method for preparing a graphene / molybdenum disulfide field-induced phase change material, which achieves excellent nonlinear conductive properties while maintaining a low filler content, reduces the risk of damage to devices caused by destructive strong electromagnetic pulses, and has potential application prospects in lightweight and high precision.

[0005] The technical solution adopted by the present invention is:

[0006] A method for preparing a graphene / molybdenum disulfide field-induced phase change material comprises the following steps:

[0007] (1) adding molybdenum disulfide powder and graphene powder to deionized water, ultrasonically treating for 20-40 minutes to form a GN / MoS2 suspension, and then stirring for 1-1.5 hours. After the stirring is completed, the GN / MoS2 hybrid particles are filtered to separate to form a filter cake, and then freeze-dried in a freeze drying oven at -40°C for 20-25 hours to obtain a dry GN / MoS2 hybrid powder;

[0008] The mass ratio of the molybdenum disulfide powder to deionized water is 1:200;

[0009] (2) Mix the epoxy resin with the GN / MoS2 hybrid powder, add anhydrous ethanol to adjust the viscosity, and stir at 55-65°C for more than 2 hours until the anhydrous ethanol is completely evaporated; then add the curing agent 2E4MZ and continue stirring for 8-15 minutes to ensure that the curing agent is evenly dispersed in the mixture;

[0010] (3) The mixture obtained in step (2) is evenly applied on a PCB board, allowed to stand at room temperature for 20-25 hours to remove residual bubbles, and finally cured in a vacuum environment at 100° C. for 3-3.5 hours to obtain a graphene / molybdenum disulfide field-induced phase change material.

[0011] Preferably, in step (1), the mass ratio of molybdenum disulfide powder to graphene powder is 5-15:1, more preferably 10:1.

[0012] Preferably, in step (1), the mass ratio of molybdenum disulfide powder to deionized water is 1:200.

[0013] Preferably, the filling amount of GN / MoS2 hybrid powder in the graphene / molybdenum disulfide field-induced phase change material is 10 wt%.

[0014] Preferably, in step (2), the curing agent 2E4MZ is added in an amount of 3-6% by weight of the epoxy resin, more preferably 4%. The molecular structure of 2E4MZ (2-ethyl-4-methylimidazole) contains two active amine groups, which can achieve efficient crosslinking and curing of the epoxy resin in the temperature range of 80-120°C, forming a thermosetting resin system and enhancing the structural stability of the composite material.

[0015] The beneficial effects of adopting the above technical solution are:

[0016] The present invention combines graphene and MoS2 to construct a hierarchical structure system. The synergistic effect of the two-dimensional conductive network of graphene and the MoS2 flakes can achieve excellent nonlinear conductive properties at a low filler content, which not only reduces the risk of damage to the device caused by destructive strong electromagnetic pulses, but also has potential application prospects in lightweight and high precision.

[0017] Figures in the specification

[0018] Figure 1a This is the SEM image of MoS2 powder;

[0019] Figure 1b SEM image of GN / MoS2 hybrid powder prepared in Example 3;

[0020] Figure 2 EDS analysis of the GN / MoS2 hybrid powder prepared in Example 3;

[0021] Figure 3 Raman spectra of MoS2 powder and GN / MoS2 hybrid powder prepared in Example 3;

[0022] Figure 4a The electric field response characteristic curves of GN / MoS2 composite materials with different graphene contents;

[0023] Figure 4b The resistivity of GN / MoS2 composite materials with different graphene contents varies with the electric field;

[0024] Figure 5 E of GN / MoS2 composites with different graphene contents b and α;

[0025] Figure 6a The strong field protection switch characteristics (E <E b );

[0026] Figure 6b The strong field protection switch characteristics of the 10wt% GN / MoS2 composite material of the present invention (E>E b ). DETAILED DESCRIPTION

[0027] The present invention will be further described in detail below with reference to specific embodiments.

[0028] The graphene powder used in the examples has a high carbon content of over 98% and was purchased from Suzhou Tanfeng Technology Co., Ltd. in China, ensuring the high quality and high purity of the material. At the same time, the purity of MoS2 in the composite material is as high as 99.9% or more and was purchased from Zhongke New Materials Co., Ltd. Epoxy resin (E-51) and 2-ethyl-4-methylimidazole (2E4MZ, purity 99%) are used as the matrix and curing agent. E-51 has good bonding properties and mechanical strength and is provided by Chuzhou Huisheng Electronic Materials Co., Ltd. It is combined with 2E4MZ provided by Shandong Xiya Reagent Co., Ltd. as a curing agent. The ratio of the two constitutes a thermosetting resin system. Anhydrous ethanol is purchased from Tianjin Yongda Chemical Reagent Co., Ltd.

[0029] Example 1

[0030] A method for preparing a graphene / molybdenum disulfide field-induced phase change material comprises the following steps:

[0031] (1) 1 g of molybdenum disulfide powder and 0.15 g of graphene powder were added to 200 g of deionized water and ultrasonically treated for 40 minutes to form a GN / MoS2 suspension, which was then stirred using a magnetic stirrer for 1.5 hours. After stirring, the GN / MoS2 hybrid particles were filtered to form a filter cake, which was then freeze-dried in a freeze drying oven at -40°C for 25 hours to obtain a dry GN / MoS2 hybrid powder;

[0032] (2) Epoxy resin and GN / MoS2 hybrid powder were mixed, and anhydrous ethanol was added to adjust the viscosity. The mixture was stirred at 65°C for more than 2 hours until the anhydrous ethanol was completely evaporated. Then, curing agent 2E4MZ was added and stirred continuously for 8 minutes to ensure that the curing agent was evenly dispersed in the mixture. The addition amount of curing agent 2E4MZ was 3% of the mass of epoxy resin, and the filling amount of GN / MoS2 hybrid powder was 10wt%;

[0033] (3) The obtained mixture was evenly spread on the PCB board, allowed to stand at room temperature for 25 hours to remove residual bubbles, and finally cured in a vacuum environment at 100°C for 3.5 hours to obtain a graphene / molybdenum disulfide field-induced phase change material.

[0034] Example 2

[0035] A method for preparing a graphene / molybdenum disulfide field-induced phase change material comprises the following steps:

[0036] (1) 1 g of molybdenum disulfide powder and 0.05 g of graphene powder were added to 200 g of deionized water and ultrasonically treated for 20 minutes to form a GN / MoS2 suspension, which was then stirred using a magnetic stirrer for 1 hour. After stirring, the GN / MoS2 hybrid particles were filtered to form a filter cake, which was then freeze-dried in a freeze drying oven at -40°C for 20 hours to obtain a dry GN / MoS2 hybrid powder;

[0037] (2) Epoxy resin and GN / MoS2 hybrid powder were mixed, and anhydrous ethanol was added to adjust the viscosity. The mixture was stirred at 55°C for more than 2 hours until the anhydrous ethanol was completely evaporated. Then, curing agent 2E4MZ was added and stirred continuously for 15 minutes to ensure that the curing agent was evenly dispersed in the mixture. The addition amount of curing agent 2E4MZ was 6% of the mass of epoxy resin, and the filling amount of GN / MoS2 hybrid powder was 10wt%.

[0038] (3) The obtained mixture was evenly spread on the PCB board, allowed to stand at room temperature for 20 hours to remove residual bubbles, and finally cured in a vacuum environment at 100°C for 3 hours to obtain a graphene / molybdenum disulfide field-induced phase change material.

[0039] Example 3

[0040] A method for preparing a graphene / molybdenum disulfide field-induced phase change material comprises the following steps:

[0041] (1) 1 g of molybdenum disulfide powder and 0.1 g of graphene powder were added to 200 g of deionized water and ultrasonicated for 30 minutes to form a GN / MoS2 suspension, which was then stirred using a magnetic stirrer for 1 hour. After stirring, the GN / MoS2 hybrid particles were filtered to form a filter cake, which was then freeze-dried in a freeze drying oven at -40°C for 24 hours to obtain a dry GN / MoS2 hybrid powder;

[0042] (2) Epoxy resin and GN / MoS2 hybrid powder were mixed, and anhydrous ethanol was added to adjust the viscosity. The mixture was stirred at 60°C for more than 2 hours until the anhydrous ethanol was completely evaporated; then, curing agent 2E4MZ was added and stirred continuously for 10 minutes to ensure that the curing agent was evenly dispersed in the mixture; the addition amount of curing agent 2E4MZ was 4% of the mass of epoxy resin, and the filling amount of GN / MoS2 hybrid powder was 10wt%.

[0043] (3) The obtained mixture was evenly spread on the PCB board, allowed to stand at room temperature for 24 hours to remove residual bubbles, and finally cured in a vacuum environment at 100°C for 3 hours to obtain a graphene / molybdenum disulfide field-induced phase change material.

[0044] MoS2 powder was examined using a scanning electron microscope, and the SEM images are shown in Figure 1a , Figure 1aThe remarkable micromorphology of the MoS2 flakes can be clearly observed, with an average length of approximately 1 μm, sharp edges, and no obvious structural defects, indicating good powder crystallinity. This high-aspect-ratio lamellar structure endows the filler with a unique percolation effect, effectively spanning the insulating matrix in three dimensions, creating more contact points and promoting electron transport. Compared to spherical ZnO fillers, the flake-shaped MoS2 can provide a more direct and efficient electron transport path under the action of an external electric field, which is of great significance for improving the nonlinear conductive properties of the composite material.

[0045] The present invention successfully prepared GN / MoS2 hybrid powder, and further used scanning electron microscopy and energy dispersive spectrometer to microscopically characterize the GN / MoS2 hybrid powder prepared in Example 3. The SEM analysis results showed that Figure 1b It is shown in Figure 2 that MoS2 nanosheets and graphene sheets form a uniform interpenetrating structure network, which constructs a three-dimensional electron transmission channel through van der Waals force coupling, which is conducive to the movement of electrons between layers or along the surface. The results of EDS elemental analysis are shown in Figure 2. Figure 2 As shown, the material has the expected chemical composition. The complete overlap of the signal lattices of the C element (green), S (red), and Mo (yellow) elements verifies the uniform anchoring of MoS2 on the graphene surface. The structural advantage of this hybrid system is reflected in the MoS2 layer acting as a dielectric reinforcement phase to effectively regulate the interfacial potential barrier, while the graphene network provides a fast charge transfer path. This synergistic effect is conducive to improving the nonlinear conductivity response characteristics of the composite material.

[0046] Raman spectroscopy experiments were conducted on MoS2 powder and GN / MoS2 (mass ratio 1:10) hybrid powder prepared in Example 3. Figure 3 .exist Figure 3 In the inset, two obvious characteristic peaks can be seen in the spectrum of the original MoS2 powder, namely E 2g and A 1g The two peaks are the characteristic vibration modes of MoS2, corresponding to the in-plane vibration and out-of-plane vibration modes of Mo-S bonds respectively. 2g The modal frequency is 381 cm -1 , A 1g The modal frequency is 408cm -1 , E 2g and A 1g The frequency difference between the modes is 26.37 cm -1 , indicating that MoS2 has a multilayer structure. Figure 3 As shown in the figure, the Raman spectrum results of the hybrid powder containing 10wt% GN / MoS2 clearly show that A 1g The peak position blue-shifted to 404 cm -1, indicating that after the introduction of graphene between the MoS2 layers, the graphene and MoS2 layers are coupled, resulting in the restriction of the out-of-plane vibration of sulfur atoms. In addition, the Raman spectrum of the hybrid powder also shows a 1357cm -1 (D band) and 1591cm -1 The graphene characteristic peak (G band) is the D band, which reflects the density of carbon lattice defect states, and the G band is related to sp 2 The planar vibration of hybridized carbon was correlated, confirming that the GN / MoS2 composite interface was successfully constructed by the solution composite method.

[0047] The nonlinear conductive properties of GN / MoS2 composite materials with different graphene contents were tested. Figure 4a-4b .Depend on Figure 4a It can be seen that the graphene content regulates the electric field response characteristics of the composite material. With the increase of graphene content, the switching field strength E b It shows a decreasing trend, indicating that the graphene sheet can reduce the interface contact resistance as a high-speed channel for electron transmission, and at the same time form a heterogeneous interface with MoS2 to enhance the interlayer charge transfer efficiency. Figure 4b It shows that as the electric field increases, the resistivity decreases. When the external electric field exceeds E b After the threshold, the resistivity of all systems approaches a constant plateau, confirming that the three-dimensional conductive network is fully activated and reaches a dynamic equilibrium state. This concentration-dependent field-induced controllable property demonstrates that by adjusting the graphene content, the intelligent switching of the nonlinear conductivity behavior of the composite material can be optimized to meet specific application requirements.

[0048] The present invention has conducted experiments on composite materials with different graphene contents. Figure 5 The effects of different graphene contents on the E b and α, the results show that with the increase of graphene content, the E b The synergistic effect of graphene's two-dimensional conductive network and MoS2 sheets, as well as the high carrier mobility of graphene, can significantly improve the charge transfer efficiency of the material and jointly reduce the threshold field strength of conductive percolation. By precisely controlling the graphene filling amount in the range of 0-1.5wt%, it can work together with MoS2. 10wt% MoS2 / EP composite materials can achieve continuous adjustment of E in the range of 0.19-0.59kV / mm. b value, while maintaining the α coefficient in the optimized range of 4.42-9.6.

[0049] The field response analysis of the 10% GN / MoS2 EP composite material prepared in Example 3 was performed. b The value is 0.45kV / mm. This property enables it to maintain insulation at an electric field strength of 0.18kV / mm. Figure 6a When the field strength reaches 0.54kV / mm, exceeding E b The critical value of the composite material percolation network is triggered and shows a conductive state, and the conductivity jumps stepwise, causing the pulse field to decay to a safe threshold within the microsecond time scale, such as Figure 6b As shown in the figure, the GN / MoS2 material, with its nonlinear conductive properties, maintains its insulating properties in low or moderate electric fields. It activates only when the charge pulse intensity exceeds the activation point, then returns to its insulating state. By regulating the switching field strength Eb of the composite material, the activation point of the intelligent electromagnetic protection material can be precisely designed to match the electric field operating conditions of the target device.

[0050] In summary, the synergistic effect of graphene's two-dimensional conductive network and MoS2 sheets to prepare GN / MoS2 / EP composite materials can not only reduce the filler content but also have excellent nonlinear conductive properties.

[0051] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing a graphene / molybdenum disulfide field-induced phase change material, characterized in that The steps include: (1) adding molybdenum disulfide powder and graphene powder to deionized water, ultrasonically treating for 20-40 minutes to form a GN / MoS2 suspension, and then stirring for 1-1.5 hours. After the stirring is completed, the GN / MoS2 hybrid particles are filtered to separate to form a filter cake, and then freeze-dried in a freeze drying oven at -40°C for 20-25 hours to obtain a dry GN / MoS2 hybrid powder; (2) Mix the epoxy resin with the GN / MoS2 hybrid powder, add anhydrous ethanol to adjust the viscosity, and stir at 55-65°C for more than 2 hours until the anhydrous ethanol is completely evaporated; then add the curing agent 2E4MZ and continue stirring for 8-15 minutes to ensure that the curing agent is evenly dispersed in the mixture; (3) The mixture obtained in step (2) is evenly applied on a PCB board, allowed to stand at room temperature for 20-25 hours to remove residual bubbles, and finally cured in a vacuum environment at 100° C. for 3-3.5 hours to obtain a graphene / molybdenum disulfide field-induced phase change material.

2. The method for preparing the graphene / molybdenum disulfide field-induced phase change material according to claim 1, wherein: In the step (1), the mass ratio of molybdenum disulfide powder to graphene powder is 5-15:

1.

3. The method for preparing the graphene / molybdenum disulfide field-induced phase change material according to claim 2, wherein: In the step (1), the mass ratio of molybdenum disulfide powder to graphene powder is 10:

1.

4. The method for preparing the graphene / molybdenum disulfide field-induced phase change material according to claim 1, wherein: In the step (1), the mass ratio of molybdenum disulfide powder to deionized water is 1:

200.

5. The method for preparing the graphene / molybdenum disulfide field-induced phase change material according to claim 1, wherein: The filling amount of GN / MoS2 hybrid powder in the graphene / molybdenum disulfide field-induced phase change material is 10wt%.

6. The method for preparing the graphene / molybdenum disulfide field-induced phase change material according to claim 1, wherein: In the step (2), the added amount of curing agent 2E4MZ is 3-6% of the mass of the epoxy resin.

7. The method for preparing the graphene / molybdenum disulfide field-induced phase change material according to claim 6, characterized in that: In the step (2), the added amount of curing agent 2E4MZ is 4% of the mass of the epoxy resin.

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