A perylene ring-containing dialkyl imidazole iodide-modified graphene thermal conductive filler and a thermal conductive composite material based thereon

Abstract

The present invention discloses a perylene ring-containing dialkyl imidazolium salt-modified graphene thermal conductive filler and a thermal conductive composite material based thereon. The thermal conductive filler is obtained by blending and modifying the perylene ring-containing dialkyl imidazolium salt with graphene nanosheets. The modified filler and ANF are subjected to a vacuum-assisted filtration method to prepare a DMPDIIs@GNS / ANF composite material. The method of the present invention is to enhance the heat transfer performance between graphene and graphene and between graphene and ANF through the π-π interaction formed between the perylene ring at the center of the modifier and the graphene and the cation-π interaction between the alkyl imidazolium cation at both ends of the modifier and the graphene, and through the hydrogen bond and π-π interaction between the perylene ring-containing dialkyl imidazolium salt-modified graphene and the ANF, thereby significantly improving the thermal conductivity of the polymer.

Description

Technical Field

[0001] The present invention relates to the technical field of thermally conductive composite materials, and in particular to an ANF-based thermally conductive composite material using graphene modified with a perylene ring-containing dialkyl imidazole iodide salt as a thermally conductive filler. Background Art

[0002] In recent years, the demand for high power and high integration has set off a powerful technological wave in the development of modern microelectronic devices. In order to maintain the long-term and reliable operation of the equipment, high-performance thermal management materials have become the focus of the next generation of scientific and technological development. Polymers are widely used in the field of thermal management due to their low cost and easy processing. However, the thermal conductivity of polymers is usually very poor, and the thermal conductivity of polymers can be improved by adding high thermal conductivity fillers. Graphene (GNS) has an intrinsic high thermal conductivity (in-plane thermal conductivity of 5000W / mK) and is widely used in thermally conductive composite materials, but the phonon transmission between graphene layers is severely scattered, thereby affecting heat transfer. In view of this, it is necessary to eliminate the defects of GNS by functional modification of GNS. The non-covalent functionalization method is relatively simple and can maintain the intrinsic properties of the original filler to the greatest extent. Non-covalent functionalization mainly modifies the GNS surface through π-π interaction, avoiding damage to the GNS surface structure. The intrinsic thermal conductivity of the currently selected modifiers is very poor, and the interaction with GNS is not strong. Therefore, it is necessary to select groups that can form stronger π-π and cation-π interactions with GNS to connect GNS. Summary of the Invention

[0003] Based on the problems existing in the above-mentioned prior art, the present invention provides a graphene thermal conductive filler modified with a dialkyl imidazole iodide salt containing a perylene ring and a thermal conductive composite material based thereon, which aims to modify graphene with a dialkyl imidazole iodide salt containing a perylene ring, and then use it as a filler and ANF to prepare a high thermal conductivity composite material through vacuum-assisted filtration. Thanks to the strong π-π and cation-π interactions formed between the dialkyl imidazole iodide salt containing a perylene ring and graphene, the heat transfer performance between the graphene layers is greatly enhanced. At the same time, the hydrogen bonds between the carbonyl group and the imidazole ring on the modifier and the ANF enhance the interfacial compatibility between the graphene and the ANF, thereby improving the overall thermal conductivity of the composite material.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] The present invention first discloses a perylene ring-containing dialkyl imidazole iodide modified graphene thermal conductive filler, which is obtained by blending and modifying the perylene ring-containing dialkyl imidazole iodide with graphene nanosheets. The preparation method is as follows: first, using 3,4,9,10-perylene tetracarboxylic dianhydride as a raw material, a primary amine acylation reaction is performed to obtain N,N'-bis(3-imidazol-1-ylpropyl) perylene diimide, which is recorded as MPDI; then a quaternization reaction is performed to obtain N,N'-bis(1-dodecyl-3-ylpropyl imidazole) peroxydiimide diiodide, which is recorded as DMPDIIs; then, an electrochemical exfoliation graphite method is used to obtain graphene nanosheets, which are recorded as GNS; finally, DMPDIIs and GNS are blended and modified to obtain a perylene ring-containing dialkyl imidazole iodide modified graphene thermal conductive filler, which is recorded as DMPDIIs@GNS. Specifically comprising the following steps:

[0006] Step 1. Add 2.5-10 mmol of 3,4,9,10-perylenetetracarboxylic dianhydride to 80-320 mL of DMF and stir to form a suspension, then add 5-20 mmol of 1-(3-aminopropyl)imidazole, and heat the resulting mixture at 120-160° C. with sealed stirring for 48-72 hours; after cooling, filter, wash the filter residue with water and methanol respectively (the washing order of water and methanol is not specified), and vacuum dry to obtain MPDI.

[0007] Step 2: Add 10-50 mmol of MPDI to 200-500 mL of DMF and stir to form a suspension, then add 20-110 mmol of 1-iodododecane; heat the mixture at 120-160°C and stir in a sealed container for 48-72 hours. The brown suspension in the reaction system turns into a dark purple solution. After cooling the reaction system to room temperature, remove DMF by vacuum evaporation. Then, wash the resulting residue with water and n-hexane in large quantities (the order of washing with water and n-hexane is not critical), and vacuum dry to obtain DMPDIIs.

[0008] Step 3: Using a graphite foil as an anode, a platinum sheet as a cathode, and a 0.1-0.3 mol / L ammonium sulfate aqueous solution as an electrolyte, the graphite foil is electrochemically stripped at a constant voltage of 10-15 V, and the GNS is obtained after filtration, washing, and drying;

[0009] Step 4: Add 1-2 g of DMPDIIs to 80-500 mL of DMF and stir evenly with ultrasound to obtain a uniform solution of DMPDIIs; slowly add 1-2 g of GNS to the uniform solution of DMPDIIs, alternately stir magnetically and ultrasonically at room temperature, each for three times, each for 3-6 hours; centrifuge, wash the product with DMF to remove excess DMPDIIs, then centrifuge and wash with deionized water to remove DMF, and vacuum dry to obtain DMPDIIs@GNS.

[0010] The present invention also discloses a preparation method of a thermally conductive composite material, which specifically comprises the following steps: adding chopped K49 fibers and KOH to DMSO and stirring evenly to obtain a deep red DMSO dispersion of ANF; adding the DMSO dispersion of the above-mentioned perylene ring-containing dialkyl imidazole iodide-modified graphene DMPDIIs@GNS to the DMSO dispersion of ANF, stirring evenly, and then adding to deionized water to generate DMPDIIs@GNS / ANF flocculation; filtering the DMPDIIs@GNS / ANF flocculation through a Buchner funnel and washing with water to obtain a DMPDIIs@GNS / ANF gel; adding the DMPDIIs@GNS / ANF gel to deionized water and shearing to obtain a uniform dispersion; obtaining a DMPDIIs@GNS / ANF composite membrane by vacuum filtration, peeling off after drying, and hot pressing to obtain the MPDIIs@GNS / ANF thermally conductive composite material.

[0011] As a further preferred technical solution of the present invention, the usage ratio of K49 fiber, KOH and DMSO is 10 mg: 10-30 mg: 0.5-2 mL.

[0012] As a further preferred technical solution of the present invention, the added amount of DMPDIIs@GNS accounts for 10% to 40% of the total mass of DMPDIIs@GNS and K49 fiber (that is, the mass percentage of the thermal conductive filler in the thermal conductive composite material is 10% to 40%).

[0013] As a further preferred technical solution of the present invention, the shearing rotation speed is 6000-12000 rpm.

[0014] As a further preferred technical solution of the present invention, the vacuum filtration uses a polytetrafluoroethylene filter membrane with a pore size of 0.22 μm.

[0015] The present invention also discloses a DMPDIIs@GNS / ANF thermal conductive composite material obtained according to the preparation method.

[0016] The beneficial effects of the present invention are embodied in:

[0017] The present invention uses a dialkyl imidazolium iodide containing a perylene ring as a modifier to modify graphene to obtain DMPDIIs@GNS / ANF filler, and then prepares ANF and filler into a high thermal conductivity composite material through vacuum-assisted filtration. Perylene has a strong aromatic structure and forms a stronger π-π interaction with GNS. The imidazolium cation forms a strong cation-π interaction with GNS. The synergistic effect of the two enhances the heat transfer performance between graphene layers, which can significantly avoid the shortcoming that other molecules have weak interaction with GNS modification. In addition, the alkyl chain connecting the perylene end group can significantly improve the poor solubility of perylene imides. The hydrogen bond and cation-π interaction between the dialkyl imidazolium iodide containing a perylene ring and ANF increase the interfacial compatibility between graphene and ANF. Vacuum filtration forms a good filler orientation. Based on the above-mentioned multiple synergistic effects, the present invention constructs heat conduction paths between fillers and between fillers and the matrix, significantly enhancing the thermal conductivity of the composite material. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0019] Figure 1 Schematic diagram of the synthesis process of DMPDIIs of Example 1 of the present invention, 1 is 3,4,9,10-perylenetetracarboxylic dianhydride, 2 is N,N'-bis(3-imidazol-1-ylpropyl)perylene diimide MPDI, 3 is N,N'-bis(1-dodecyl-3-ylpropylimidazole)peroxydiimide diiodide DMPDIIs, wherein R=C 12 H 25 ;

[0020] Figure 2 The GNS obtained in Example 1 of the present invention ( Figure 2 (a) in), DMPDIIs@GNS( Figure 2 (b) in), DMPDIIs@GNS / ANF( Figure 2 SEM image of (c)).

[0021] Figure 3 The GNS obtained in Example 1 of the present invention ( Figure 3 (a) in), DMPDIIs@GNS( Figure 3 TEM image of (b)).

[0022] Figure 4 These are the Raman spectra of GNS and DMPDIIs@GNS obtained in Example 1 of the present invention.

[0023] Figure 5 These are the thermogravimetric images of GNS, DMPDIIs, and DMPDIIs@GNS obtained in Example 1 of the present invention.

[0024] Figure 6 Graph showing thermal conductivity of composite materials obtained from various embodiments of the present invention and comparative examples. DETAILED DESCRIPTION

[0025] The following describes the specific embodiments of the present invention in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0026] Unless otherwise defined, the technical terms used in the following examples have the same meanings as commonly understood by those skilled in the art to which this invention belongs. The experimental reagents used in the following examples, unless otherwise specified, are conventional biochemical reagents; the experimental methods described, unless otherwise specified, are conventional methods.

[0027] Example 1.

[0028] In this example, 10 wt% DMPDIIs@GNS / ANF composite materials were prepared according to the following steps.

[0029] Step 1: Add 5 mmol of 3,4,9,10-perylenetetracarboxylic dianhydride to 80 mL of DMF in a three-necked flask and stir at room temperature for 5 minutes to form a suspension. Then, add 10.5 mmol of 1-(3-aminopropyl)imidazole. Heat the resulting mixture in a sealed oil bath at 140°C and stir for 72 hours. After cooling the reaction system to room temperature, filter it using a Buchner funnel. The resulting residue is washed several times with 500 mL of cold deionized water and methanol, respectively, to obtain a purple solid. Dry it in vacuo at 80°C for 24 hours to obtain MPDI with a yield of 90.5%.

[0030] Step 2: Add 11.6 mmol of MPDI to a three-necked flask containing 210 mL of DMF and stir at room temperature for 5 minutes to form a suspension. Then add 25.5 mmol of 1-iodododecane. Heat the mixture in a sealed oil bath at 140°C and stir for 72 hours. The brown suspension in the reaction system turns into a dark purple solution. After cooling the reaction system to room temperature, remove DMF by vacuum evaporation. The resulting residue is washed multiple times with 500 mL of deionized water and n-hexane. The resulting reddish-brown solid is vacuum-dried at 80°C for 24 hours to obtain DMPDIIs with a yield of 84.3%.

[0031] Step 3: Using a graphite foil as an anode, a platinum sheet as a cathode, and a 0.1 mol / L ammonium sulfate aqueous solution as an electrolyte, the graphite foil is electrochemically stripped at a constant stripping voltage of 15 V. After filtration, washing, and freeze-drying, graphene nanosheets are obtained, which are recorded as GNS.

[0032] Step 4: Add 2 g of DMPDIIs to a glass bottle containing 80 mL of DMF and stir evenly with ultrasound to obtain a uniform solution of DMPDIIs; slowly add 1 g of GNS to the uniform solution of DMPDIIs, alternately perform magnetic stirring and ultrasound at room temperature, three times, each for 6 hours; centrifuge at 14,000 r / min, collect the solid, and wash it three times with DMF to remove excess DMPDIIs until the supernatant is colorless. Finally, centrifuge once with deionized water to remove DMF, collect the black solid at the bottom of the tube, and vacuum dry it at 80°C for 24 hours to obtain DMPDIIs@GNS.

[0033] Step 5: Preparation of DMPDIIs@GNS / ANF composite material

[0034] 0.75g of chopped Kevlar 49 fiber and 1.125g of KOH were added to a glass bottle containing 75mL of DMSO and magnetically stirred at 800rpm for 4 days to prepare a 10mg / mL DMSO dispersion of ANF. 9mL of the DMSO dispersion of ANF was diluted tenfold and added to 5mL of a 2mg / mL DMODIIs@GNS DMSO dispersion. Mechanical stirring was performed for 10 minutes until uniform. The mixed solution was then added to 500mL of deionized water and soaked for 30 minutes to form DMPDIIs@GNS / ANF flocculates. The DMPDIIs@GNS / ANF flocculate was filtered through a Buchner funnel and washed with water to obtain a DMPDIIs@GNS / ANF gel. The DMPDIIs@GNS / ANF gel was added to deionized water and subjected to vigorous shear stirring at 8000 rpm for 10 minutes to obtain a uniform dispersion. A composite membrane was obtained by vacuum-assisted filtration using a polytetrafluoroethylene filter membrane with a pore size of 0.22 μm. The film was dried in air at 25°C and then peeled off from the filter paper. The film was hot-pressed at 5 MPa and 120°C for five minutes to obtain a DMPDIIs@GNS / ANF thermal conductive composite material, in which the mass percentage of DMPDIIs@GNS filler was 10%.

[0035] Example 2

[0036] In this example, a DMPDIIs@GNS / ANF thermal conductive composite material with a DMPDIIs@GNS filler mass percentage of 20 wt% was prepared by the same method as in Example 1, with the only difference being that in step 5, the amount of the DMSO dispersion of ANF used was 8 mL, the amount of the DMSO dispersion of DMODIIs@GNS used was 10 mL, and the mass percentage of the DMPDIIs@GNS filler in the obtained DMPDIIs@GNS / ANF thermal conductive composite material was 20%.

[0037] Example 3

[0038] In this example, a DMPDIIs@GNS / ANF thermal conductive composite material with a mass percentage of 30 wt% of DMPDIIs@GNS filler was prepared by the same method as in Example 1, with the only difference being that in step 5, the amount of DMSO dispersion of ANF used was 7 mL, the amount of DMSO dispersion of DMODIIs@GNS used was 15 mL, and the mass percentage of DMPDIIs@GNS filler in the obtained DMPDIIs@GNS / ANF thermal conductive composite material was 30%.

[0039] Example 4

[0040] In this example, a DMPDIIs@GNS / ANF thermal conductive composite material with a mass percentage of 40 wt% of DMPDIIs@GNS filler was prepared by the same method as in Example 1, with the only difference being that in step 5, the amount of DMSO dispersion of ANF used was 6 mL, the amount of DMSO dispersion of DMODIIs@GNS used was 20 mL, and the mass percentage of DMPDIIs@GNS filler in the obtained DMPDIIs@GNS / ANF composite material was 40%.

[0041] Comparative Example 1

[0042] In this comparative example, the graphene nanosheets prepared in Example 1 were used as fillers to replace the DMPDIIs@GNS fillers, and a GNS / ANF thermal conductive composite material with a GNS filler mass percentage of 10% was prepared by the same method as in step 5 of Example 1.

[0043] Comparative Example 2

[0044] In this comparative example, the graphene nanosheets prepared in Example 1 were used as fillers to replace the DMPDIIs@GNS fillers, and a GNS / ANF thermal conductive composite material with a GNS filler mass percentage of 20% was prepared by the same method as in step 5 of Example 2.

[0045] Comparative Example 3

[0046] In this comparative example, the graphene nanosheets prepared in Example 1 were used as fillers to replace the DMPDIIs@GNS fillers, and a GNS / ANF thermal conductive composite material with a GNS filler mass percentage of 30% was prepared by the same method as in step 5 of Example 3.

[0047] Comparative Example 4

[0048] In this comparative example, the graphene nanosheets prepared in Example 4 were used as fillers to replace the DMPDIIs@GNS fillers, and a GNS / ANF thermal conductive composite material with a GNS filler mass percentage of 40% was prepared by the same method as step 5 of Example 4.

[0049] Figure 1Schematic diagram of the synthesis process of DMPDIIs in Example 1, in which 1 is 3,4,9,10-perylenetetracarboxylic dianhydride, 2 is N,N'-bis(3-imidazol-1-ylpropyl)perylene diimide MPDI, 3 is N,N'-bis(1-dodecyl-3-ylpropylimidazole)peroxydiimide diiodide DMPDIIs, wherein R=C 12 H 25 .

[0050] Figure 2 The GNS obtained in Example 1 of the present invention ( Figure 2 (a) in), DMPDIIs@GNS( Figure 2 (b) in), DMPDIIs@GNS / ANF( Figure 2 The SEM image (c) in Figure 2 shows that the surface of the unmodified GNS is relatively smooth, while small organic particles are present on the surface of the modified graphene. This indicates that the π-π and cation-π interactions between the DMPDIIs containing perylene rings and imidazolium cations and the graphene have successfully bonded the DMPDIIs to the graphene surface and achieved relatively uniform distribution. The cross-sectional SEM image of the DMPDIIs@GNS / ANF composite shows that the DMPDIIs@GNS and ANF are tightly packed together, forming an oriented layered structure.

[0051] Figure 3 The GNS obtained in Example 1 of the present invention ( Figure 3 (a) in), DMPDIIs@GNS( Figure 3 From the TEM image (b) in Figure 2, we can see that the surface of GNS is smooth and transparent, while the surface of DMPDIIs@GNS is darker and has more black spots evenly distributed, which is the result of DMPDIIs loading on the surface of GNS.

[0052] Figure 4 The Raman spectra of GNS and DMPDIIs@GNS obtained in Example 1 of the present invention are shown in Figure 1581cm -1 The nearby peaks belong to the G band peak of GNS. Compared with the G band peak of GNS, the position of the G band peak of DMPDIIs@GNS is blue-shifted to 1584 cm -1 This is because DMPDIIs attach to the GNS surface through π-π interactions, changing the charge distribution on the GNS surface. The G band of DMPDIIs@GNS shifts to a higher frequency, requiring higher energy for vibration.

[0053] Figure 5 This is the thermogravimetric diagram of GNS, DMPDIIs, and DMPDIIs@GNS obtained in Example 1 of the present invention. From the weight loss curves of each substance in the figure, it can be calculated that the loading amount of DMPDIIs on the GNS surface is 7.5%.

[0054] Figure 6 The thermal conductivity test results of the thermally conductive composite materials obtained from each example and comparative example are shown. As can be seen from the figure, the thermal conductivity of the composite material increases with increasing filler content. This is because higher filler content leads to denser thermal paths. Furthermore, at the same filler content, the thermal conductivity of the DMPDIIs@GNS / ANF composite material is significantly higher than that of the GNS / ANF composite material. This indicates that DMPDIIs, which possesses certain thermal conductivity, modifies graphene through π-π and cation-π interactions, connecting the graphene layers, effectively improving heat transfer between the graphene layers and assisting in the formation of continuous horizontal thermal paths. Furthermore, the hydrogen bonds formed between the modifier and the ANF effectively enhance the compatibility between the filler and the substrate, improving the overall thermal conductivity of the composite material.

[0055] Although specific embodiments of the present invention are described above, those skilled in the art should understand that these are merely examples and that various changes or modifications may be made to the embodiments without departing from the principles and essence of the present invention. The scope of protection of the present invention is limited only by the appended claims.

Claims

1. A method for preparing a graphene thermal conductive filler modified with a dialkyl imidazole iodide salt containing a perylene ring, characterized in that: The thermal conductive filler is obtained by blending and modifying a dialkyl imidazole iodide salt containing a perylene ring with graphene nanosheets: First, 3,4,9,10-perylenetetracarboxylic dianhydride was used as the raw material, and N,N'-bis(3-imidazol-1-ylpropyl)perylene diimide (MPDI) was obtained through primary amine acylation reaction. Then, after quaternization reaction, N,N'-bis(1-dodecyl-3-ylpropylimidazole)peroxydiimide diiodide salt was obtained, which was denoted as DMPDIIs. Then, graphene nanosheets, denoted as GNS, were obtained by electrochemical exfoliation of graphite; Finally, DMPDIIs and GNS were blended and modified to obtain a graphene thermal conductive filler modified with dialkyl imidazole iodide salt containing perylene ring, which was recorded as DMPDIIs@GNS.

2. The preparation method according to claim 1, characterized in that The following steps are involved: Step 1, adding 2.5-10 mmol of 3,4,9,10-perylenetetracarboxylic dianhydride to 80-320 mL of DMF and stirring to form a suspension, then adding 5-20 mmol of 1-(3-aminopropyl)imidazole, heating the resulting mixture at 120-160° C. and stirring in a sealed container for 48-72 hours; cooling and filtering, washing the filter residue with water and methanol, and vacuum drying to obtain MPDI; Step 2: Add 10-50 mmol of MPDI to 200-500 mL of DMF and stir to form a suspension, then add 20-110 mmol of 1-iodododecane; heat the mixture at 120-160° C. with sealed stirring for 48-72 hours; cool the reaction system to room temperature, remove DMF by vacuum rotary evaporation, and then wash the resulting residue with water and n-hexane, and vacuum dry to obtain DMPDIIs; Step 3: Using a graphite foil as an anode, a platinum sheet as a cathode, and a 0.1-0.3 mol / L ammonium sulfate aqueous solution as an electrolyte, the graphite foil is electrochemically stripped at a constant voltage of 10-15 V, and the GNS is obtained after filtration, washing, and drying; Step 4: Add 1-2 g of DMPDIIs to 80-500 mL of DMF and stir evenly with ultrasound to obtain a uniform solution of DMPDIIs; slowly add 1-2 g of GNS to the uniform solution of DMPDIIs, and alternately perform magnetic stirring and ultrasound at room temperature, each for three times, each for 3-6 hours; After centrifugation, the product was washed with DMF to remove excess DMPDIIs, then centrifuged and washed with deionized water to remove DMF, and vacuum dried to obtain DMPDIIs@GNS.

3. A perylene ring-containing dialkyl imidazole iodonium salt-modified graphene thermal conductive filler obtained by the preparation method according to claim 1 or 2.

4. A method for preparing a thermally conductive composite material, characterized in that: The chopped K49 fibers and KOH are added to DMSO and stirred evenly to obtain a DMSO dispersion of ANF; the DMSO dispersion of DMPDIIs@GNS according to claim 3 is added to the DMSO dispersion of ANF, stirred evenly, and then added to deionized water to generate DMPDIIs@GNS / ANF flocculation; the DMPDIIs@GNS / ANF flocculation is filtered and washed with water to obtain a DMPDIIs@GNS / ANF gel; the DMPDIIs@GNS / ANF gel is added to deionized water and sheared to obtain a uniform dispersion; a DMPDIIs@GNS / ANF composite membrane is obtained by vacuum filtration, which is peeled off after drying and hot pressed to obtain an MPDIIs@GNS / ANF thermal conductive composite material.

5. The preparation method according to claim 4, characterized in that: The usage ratio of K49 fiber, KOH and DMSO is 10 mg: 10-30 mg: 0.5-2 mL.

6. The preparation method according to claim 4, characterized in that: The added amount of DMPDIIs@GNS accounts for 10% to 40% of the total mass of DMPDIIs@GNS and K49 fibers.

7. The preparation method according to claim 4, characterized in that: The shearing speed is 6000-12000rpm.

8. The preparation method according to claim 4, characterized in that: The vacuum filtration uses a polytetrafluoroethylene filter membrane with a pore size of 0.22 μm.

9. A DMPDIIs@GNS / ANF thermally conductive composite material obtained by the preparation method according to any one of claims 4 to 8.

Images