2D-AgNP (at) rGO / EP heat conduction composite material and preparation method thereof

Abstract

The invention discloses a 2D-AgNP (at) rGO / EP heat-conducting composite material and a preparation method thereof. The preparation method comprises the following steps: growing a silver nanosheet on the surface of graphene oxide, and reducing by sodium borohydride to prepare a hybrid filler; the hybrid filler is directionally arranged by adopting a double-orientation ice template method and then is impregnated, poured and compounded with epoxy resin to finally obtain the 2D-AgNP (at) rGO / EP heat-conducting composite material. In the obtained hybrid filler, the silver nanosheets can effectively reduce the contact thermal resistance between the fillers and inhibit agglomeration of graphene oxide, reduction treatment can further improve the thermal conductivity of the filler, a double-orientation ice template is subsequently combined to enable the filler to achieve effective orientation, then epoxy resin is poured, and finally the thermal conductivity of the composite material is remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of thermally conductive composite materials technology, specifically to a 2D-AgNP@rGO / EP thermally conductive composite material and its preparation method. Background Technology

[0002] In recent years, the rapid development of industries such as microelectronics, aerospace, and electrical power has placed unprecedented demands on the integration and power of electronic components. While devices are evolving towards higher integration and higher power, localized overheating problems severely shorten the lifespan of electronic devices and degrade their performance. Therefore, there is an urgent need for thermal management materials with excellent heat dissipation properties to solve this problem.

[0003] Polymer materials have attracted attention as potential thermal management materials due to their electrical insulation, lightweight, and inexpensive availability. However, the thermal conductivity of polymers themselves (0.1~0.3 W·m) is limited. -1 ·K -1 Its extremely low thermal conductivity and poor thermal stability limit its application in the field of thermal conductivity. A common way to improve the thermal conductivity of polymers is to introduce various thermally conductive fillers. Graphene oxide (GO) is widely used in thermally conductive polymer composites due to its high thermal conductivity, low coefficient of thermal expansion, high melting point, excellent mechanical properties, and high chemical stability. However, GO is prone to agglomeration, making it difficult to construct long-range ordered heat transfer paths, and the interfacial thermal resistance between its layers affects the thermal conductivity of the composite material. These problems prevent GO from fully realizing its thermal conductivity advantages, greatly restricting the performance breakthroughs and industrial applications of thermally conductive polymer composites. Summary of the Invention

[0004] To address the problems of low thermal conductivity of polymers, easy aggregation of GO, and high interfacial thermal resistance in existing technologies, this invention provides a 2D-AgNP@rGO / EP thermally conductive composite material and its preparation method. The method involves growing silver nanosheets on the GO surface and reducing them with sodium borohydride to prepare a hybrid filler, 2D-AgNP@rGO. The filler is then oriented using a dual-oriented ice template, and finally compounded with epoxy resin to significantly improve the thermal conductivity of the composite material.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a method for preparing a 2D-AgNP@rGO / EP thermally conductive composite material, which includes: exfoliating graphite into graphene oxide (GO) using the Hummers method; reducing silver nitrate (AgNO3) on the GO surface to two-dimensional silver nanosheets using polyvinylpyrrolidone (PVP) as a reducing agent, obtaining graphene oxide with silver nanosheets loaded on the surface (denoted as 2D-AgNP@GO); reducing 2D-AgNP@GO with sodium borohydride (NaBH4) to obtain a reduced graphene oxide hybrid filler with silver nanosheets loaded on the surface (denoted as 2D-AgNP@rGO); achieving directional alignment of the hybrid filler using a dual-orientation ice template method to obtain a hybrid aerogel; and impregnating and infusing the hybrid aerogel with epoxy resin (EP) to finally obtain the 2D-AgNP@rGO / EP thermally conductive composite material. Specifically, the method includes the following steps: Step 1, Preparation of GO Graphite was exfoliated into graphene oxide (GO) using the Hummers method.

[0006] Step 2, Preparation of 2D-AgNP@GO 200-400 mg of GO obtained in step 1 and 1.6-3.2 g of PVP were ultrasonically dispersed in 16-32 mL of deionized water to obtain a mixed dispersion; 100-200 mg of AgNO3 was dissolved in 3-6 mL of deionized water to obtain an AgNO3 solution; the mixed dispersion was heated to 55-65 °C in a water bath, and then the AgNO3 solution was quickly added. The mixture was kept warm and stirred at 300-500 rpm for 12-24 h; the product was separated by filtration, washed and dried to obtain 2D-AgNP@GO.

[0007] Step 3: Preparation of 2D-AgNP@rGO Disperse 200-400 mg of 2D-AgNP@GO in 80-160 mL of deionized water, add 0.8-1.6 g of NaBH4, adjust the pH to 10-11, and heat and stir at 55-65℃ and 400-600 rpm for 24-48 h. Filter to separate the product and wash until neutral, then vacuum dry at 60-70℃ to obtain 2D-AgNP@rGO.

[0008] Step 4: Preparation of 2D-AgNP@rGO aerogel Disperse 200–800 mg of 2D-AgNP@rGO in 10 mL of 1–2 wt% sodium alginate solution to form a dispersion; inject the dispersion into a solution containing 15 ° In a mold of an inclined PDMS wedge, the mold is placed in a liquid nitrogen environment for directional freezing, causing ice crystals in the dispersion to grow in both vertical and horizontal directions; then, after freeze-drying, a hybrid aerogel with a dual-orientation structure is obtained.

[0009] Step 5: Preparation of 2D-AgNP@rGO / EP Mix 5-10g of epoxy resin with 5-10g of methylhexahydrophthalic anhydride, and degas under vacuum to obtain a mixture solution; immerse the hybrid aerogel in the mixture solution, and perform vacuum impregnation and curing treatments in sequence to obtain the 2D-AgNP@rGO / EP thermally conductive composite material.

[0010] As a preferred option, in step 4, the mold used is made of rubber, has a square shape with a side length of 3cm, and contains PDMS wedges with a 15° tilt angle inside.

[0011] Preferably, in step 5, the mass fraction of 2D-AgNP@rGO filler in the composite material is 3.0-10.8 wt%.

[0012] The beneficial effects of this invention are reflected in: This invention prepares a hybrid filler, 2D-AgNP@rGO, by growing silver nanosheets on the surface of GO and reducing them with sodium borohydride. The silver nanosheets can effectively reduce the contact thermal resistance between fillers and inhibit the aggregation of graphene oxide, while the reduction treatment of 2D-AgNP@GO can further improve the thermal conductivity of the filler itself. Subsequently, the filler is effectively oriented by combining a dual-oriented ice template and then infused with epoxy resin, which ultimately significantly improves the thermal conductivity of the 2D-AgNP@rGO / EP composite material. Attached Figure Description

[0013] Figure 1 This is a SEM image of GO in Embodiment 1 of the present invention; Figure 2 This is a SEM image of 2D-AgNP@GO obtained in Example 1 of the present invention; Figure 3 This is a SEM image of 2D-AgNP@rGO obtained in Example 1 of the present invention; Figure 4 This is a side view of the aerogel obtained in Example 1 of the present invention; Figure 5 This is a top view of the aerogel obtained in Example 1 of the present invention; Figure 6 This is a comparison diagram of the vertical thermal conductivity of samples obtained from various embodiments of the present invention and comparative examples; Figure 7 This is a comparison diagram of the horizontal thermal conductivity of samples obtained from various embodiments of the present invention and comparative examples. Detailed Implementation

[0014] The embodiments of the present invention are described in detail below. These embodiments are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operation processes. However, the scope of protection of the present invention is not limited to the following embodiments.

[0015] Example 1 Step 1: Exfoliate graphite into graphene oxide (GO) using the Hummers method. Add 120 mL of concentrated sulfuric acid to a reaction flask assembled in an ice-water bath and stir. Then add 5 g of graphite powder and 3 g of sodium nitrate, and stir in an ice bath for 2 hours. Add 20 g of potassium permanganate, followed by slowly adding 600 mL of deionized water. Transfer the reaction flask to an oil bath and react at 95°C for 1 hour. After cooling, add 15 mL of 30% hydrogen peroxide. Wash the dispersion with deionized water by centrifugation until neutral. Dry under vacuum at 60°C to obtain GO. The centrifugation speed is 8000-10000 rpm.

[0016] Step 2, Preparation of 2D-AgNP@GO First, 200 mg of GO obtained in step 1 and 1.6 g of PVP were ultrasonically dispersed in 16 mL of deionized water to obtain a mixed dispersion. Then, 100 mg of AgNO3 was dissolved in 3 mL of deionized water to obtain an AgNO3 solution. The mixed dispersion was heated to 60 °C in a water bath, and then the AgNO3 solution was quickly added. The mixture was stirred at 300 rpm for 12 h at 60 °C. The product was separated by filtration, washed, and dried to obtain graphene oxide with silver nanosheets loaded on its surface, denoted as 2D-AgNP@GO.

[0017] Step 3: Preparation of 2D-AgNP@rGO 200 mg of 2D-AgNP@GO was dispersed in 80 mL of deionized water, and 0.8 g of NaBH4 was added to adjust the pH to 10. The mixture was heated in a water bath at 55 °C and stirred at 400 rpm for 24 h. The product was separated by filtration and washed with deionized water until neutral. It was then dried under vacuum at 60 °C to obtain a reduced graphene oxide hybrid filler with silver nanosheets on its surface, denoted as 2D-AgNP@rGO.

[0018] Step 4: Preparation of 2D-AgNP@rGO aerogel 200 mg of 2D-AgNP@rGO was dispersed in 10 mL of 1 wt% sodium alginate solution to form a dispersion. The dispersion was injected into a mold (the mold was made of rubber, square in shape with a side length of 3 cm, and contained PDMS wedges with a 15° tilt angle). The mold was then placed in a liquid nitrogen environment for directional freezing, which caused ice crystals in the dispersion to grow in both vertical and horizontal directions. After freeze-drying at -50 °C and 20 Pa, a hybrid aerogel with a dual orientation structure was obtained.

[0019] Step 5: Preparation of 2D-AgNP@rGO / EP 5g of epoxy resin and 5g of methylhexahydrophthalic anhydride were mixed and degassed under vacuum to obtain a mixture solution. The hybrid aerogel obtained in step 4 was immersed in the mixture solution and subjected to vacuum impregnation at -0.30MPa for 12h and curing at 80℃ for 4h, respectively, to obtain the 2D-AgNP@rGO / EP thermally conductive composite material. The mass fraction of 2D-AgNP@rGO filler in the composite material was 3.0±0.2%.

[0020] Figure 1 The image shows the SEM image of GO obtained in Example 1. It can be seen that GO has a large-sized sheet-like structure, which has excellent load-bearing performance and is suitable for supporting other fillers in the future. Figure 2 The image shows a SEM image of 2D-AgNP@GO obtained in Example 1, which clearly shows the growth of triangular silver nanosheets on the graphene sheet surface, indicating a significant loading effect. Figure 3 The image shows the SEM image of 2D-AgNP@rGO obtained in Example 1. The results show that the overall structure of the hybrid filler did not change after reduction treatment, and its stability was good. Figure 4-5 The image shows the SEM image of the 2D-AgNP@rGO aerogel obtained in Example 1. It can be seen that the filler achieves effective orientation in both the vertical and horizontal directions, which not only suppresses its own agglomeration problem, but also lays a structural foundation for improving the thermal conductivity of the composite material.

[0021] Example 2 In this embodiment, the 2D-AgNP@rGO / EP composite material was prepared using the same method as in Example 1. The only difference was that the amount of 2D-AgNP@rGO filler used in step 4 was 400 mg, and the mass fraction of 2D-AgNP@rGO filler in the resulting composite material was 5.7 ± 0.2 wt%.

[0022] Example 3 In this embodiment, the 2D-AgNP@rGO / EP composite material was prepared using the same method as in Example 1. The only difference was that the amount of 2D-AgNP@rGO filler used in step 4 was 600 mg, and the mass fraction of 2D-AgNP@rGO filler in the resulting composite material was 8.3 ± 0.2 wt%.

[0023] Example 4 In this embodiment, the 2D-AgNP@rGO / EP composite material was prepared using the same method as in Example 1. The only difference was that the amount of 2D-AgNP@rGO filler used in step 4 was 800 mg, and the mass fraction of 2D-AgNP@rGO filler in the resulting composite material was 10.8 ± 0.2 wt%.

[0024] Comparative Example 1 This comparative example prepared GO / EP composite materials according to the following steps: Step 1, Preparation of GO Same as Example 1.

[0025] Step 2: Preparation of GO aerogel 200 mg of GO was dispersed in 10 mL of 1 wt% sodium alginate solution to form a dispersion. The dispersion was injected into a mold identical to that in Example 1, and then the mold was placed in a liquid nitrogen environment for directional freezing, so that ice crystals in the dispersion grew in both vertical and horizontal directions. After freeze-drying at -50 °C and 20 Pa, an aerogel with a dual orientation structure was obtained.

[0026] Step 3: Preparation of GO / EP 5g of epoxy resin and 5g of methylhexahydrophthalic anhydride were mixed and degassed under vacuum to obtain a mixture solution. The aerogel obtained in step 4 was immersed in the mixture solution and subjected to vacuum impregnation at -0.30MPa for 12h and curing at 80℃ for 4h, respectively, to obtain the GO / EP thermally conductive composite material. The mass fraction of GO filler in the composite material was 3.0±0.2%.

[0027] Comparative Example 2 The GO / EP composite material was prepared in the same way as in Comparative Example 1, except that the amount of GO filler used in step 2 was 400 mg, and the mass fraction of GO filler in the resulting composite material was 5.7 ± 0.2 wt%.

[0028] Comparative Example 3 The GO / EP composite material was prepared in the same way as in Comparative Example 1, except that the amount of GO filler used in step 2 was 600 mg, and the mass fraction of GO filler in the resulting composite material was 8.3 ± 0.2 wt%.

[0029] Comparative Example 4 This comparative example prepared GO / EP composite material using the same method as comparative example 1, except that the amount of GO filler used in step 2 was 800 mg, and the mass fraction of GO filler in the resulting composite material was 10.8 ± 0.2 wt%.

[0030] Comparative Example 5 This comparative example prepared 2D-AgNP@GO / EP composite material according to the following steps: Step 1, Preparation of GO Same as Example 1.

[0031] Step 2, Preparation of 2D-AgNP@GO Same as Example 1.

[0032] Step 3: Preparation of 2D-AgNP@GO aerogel 200 mg of 2D-AgNP@GO was dispersed in 10 mL of 1 wt% sodium alginate solution to form a dispersion. The dispersion was injected into a mold identical to that in Example 1, and then the mold was placed in a liquid nitrogen environment for directional freezing, so that ice crystals in the dispersion grew in both vertical and horizontal directions. After freeze-drying at -50 °C and 20 Pa, a hybrid aerogel with a dual orientation structure was obtained.

[0033] Step 4: Preparation of 2D-AgNP@GO / EP 5g of epoxy resin and 5g of methylhexahydrophthalic anhydride were mixed and degassed under vacuum to obtain a mixture solution. The hybrid aerogel obtained in step 4 was immersed in the mixture solution and subjected to vacuum impregnation at -0.30MPa for 12h and curing at 80℃ for 4h, respectively, to obtain the 2D-AgNP@GO / EP thermally conductive composite material. The mass fraction of 2D-AgNP@GO filler in the composite material was 3.0±0.2%.

[0034] Comparative Example 6 The 2D-AgNP@GO / EP composite material was prepared in the same way as in Comparative Example 5, except that the amount of 2D-AgNP@GO filler used in step 3 was 400 mg, and the mass fraction of 2D-AgNP@GO filler in the resulting composite material was 5.7 ± 0.2 wt%.

[0035] Comparative Example 7 The 2D-AgNP@GO / EP composite material was prepared in the same way as in Comparative Example 5, except that the amount of 2D-AgNP@GO filler used in step 3 was 600 mg, and the mass fraction of 2D-AgNP@GO filler in the resulting composite material was 8.3 ± 0.2 wt%.

[0036] Comparative Example 8 The 2D-AgNP@GO / EP composite material was prepared in the same way as in Comparative Example 5, except that the amount of 2D-AgNP@GO filler used in step 3 was 800 mg, and the mass fraction of 2D-AgNP@GO filler in the resulting composite material was 10.8 ± 0.2 wt%.

[0037] The thermal conductivity of the samples obtained in each embodiment and comparative example is as follows: Figure 6 and Figure 7 As shown. From Figure 6-7It can be seen that the thermal conductivity of the samples obtained in Examples 1-4 is significantly improved compared to Comparative Examples 1-8. Further comparison shows that, with the same filler content, graphene oxide with silver nanosheets loaded on its surface (2D-AgNP@GO) has a higher thermal conductivity than pure graphene oxide (GO); the thermal conductivity of 2D-AgNP@rGO obtained by reduction is further improved; and the thermal conductivity of the composite material increases with the increase of 2D-AgNP@rGO filler content. The core reasons for this phenomenon are twofold: first, after silver nanosheets are grown in situ on the surface of graphene oxide, the silver nanosheets can act as a "thermal bridge," effectively reducing the contact thermal resistance between fillers; second, the reduction of GO to rGO (reduced graphene oxide) with sodium borohydride reduces the oxygen-containing functional groups on the GO surface, lowers electron transport resistance, and further enhances the thermal conductivity of the filler itself. The synergistic effect of these two factors, combined with the increased thermal conductivity pathways resulting from the subsequent increase in filler content, ultimately significantly improves the overall thermal conductivity of the composite material.

[0038] The above are merely exemplary embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a 2D-AgNP@rGO / EP thermally conductive composite material, characterized in that: Graphite was exfoliated into graphene oxide (GO) using the Hummers method. Using polyvinylpyrrolidone (PVP) as a reducing agent, silver nitrate (AgNO3) was reduced to two-dimensional silver nanosheets on the GO surface, resulting in graphene oxide with silver nanosheets loaded on the surface, denoted as 2D-AgNP@GO. 2D-AgNP@GO was further reduced using sodium borohydride (NaBH4) to obtain a reduced graphene oxide hybrid filler with silver nanosheets loaded on the surface, denoted as 2D-AgNP@rGO. The hybrid filler was oriented using a dual-orientation ice template method to obtain a hybrid aerogel. The hybrid aerogel was then impregnated and infused with epoxy resin (EP) to finally obtain the 2D-AgNP@rGO / EP thermally conductive composite material.

2. The preparation method according to claim 1, characterized in that, Includes the following steps: Step 1, Preparation of GO Graphite was exfoliated into graphene oxide (GO) using the Hummers method. Step 2, Preparation of 2D-AgNP@GO 200-400 mg of GO obtained in step 1 and 1.6-3.2 g of PVP were ultrasonically dispersed in 16-32 mL of deionized water to obtain a mixed dispersion; 100-200 mg of AgNO3 was dissolved in 3-6 mL of deionized water to obtain an AgNO3 solution; the mixed dispersion was heated to 55-65℃ in a water bath, and then the AgNO3 solution was quickly added. The mixture was stirred at 300-500 rpm for 12-24 h; the product was separated by filtration, washed and dried to obtain 2D-AgNP@GO; Step 3: Preparation of 2D-AgNP@rGO Disperse 200-400 mg of 2D-AgNP@GO in 80-160 mL of deionized water, add 0.8-1.6 g of NaBH4, adjust the pH to 10-11, and heat and stir at 55-65℃ and 400-600 rpm for 24-48 h; filter to separate the product and wash until neutral, then vacuum dry at 60-70℃ to obtain 2D-AgNP@rGO; Step 4: Preparation of 2D-AgNP@rGO aerogel Disperse 200–800 mg of 2D-AgNP@rGO in 10 mL of 1–2 wt% sodium alginate solution to form a dispersion; inject the dispersion into a solution containing 15 ° In a mold of an inclined PDMS wedge, the mold is placed in a liquid nitrogen environment for directional freezing, causing ice crystals in the dispersion to grow in both vertical and horizontal directions; then, after freeze-drying, a hybrid aerogel with a dual-orientation structure is obtained. Step 5: Preparation of 2D-AgNP@rGO / EP Mix 5-10g of epoxy resin with 5-10g of methylhexahydrophthalic anhydride, and degas under vacuum to obtain a mixture solution; immerse the hybrid aerogel in the mixture solution, and perform vacuum impregnation and curing treatments in sequence to obtain the 2D-AgNP@rGO / EP thermally conductive composite material.

3. The preparation method according to claim 2, characterized in that: In step 4, the mold used is made of rubber, is square with a side length of 3cm, and contains PDMS wedges with a 15° tilt angle inside.

4. The preparation method according to claim 2, characterized in that: In step 5, the mass fraction of 2D-AgNP@rGO filler in the composite material is 3.0-10.8 wt%.

5. A 2D-AgNP@rGO / EP thermally conductive composite material obtained by the preparation method according to any one of claims 1 to 4.

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