Bifunctional vegetable oil / carbon-based heat-conducting interface material and preparation method thereof

Abstract

The invention relates to a bifunctional vegetable oil / carbon-based heat-conducting interface material as well as a preparation method and application thereof. The preparation method of the bifunctional vegetable oil / carbon-based heat-conducting interface material comprises the following steps: preparing a bifunctional vegetable oil resin matrix containing a thiophene group and a maleimide group by respectively utilizing thiol-ene click chemistry and epoxy ring-opening reaction, and preparing the bifunctional vegetable oil / carbon-based heat-conducting interface material by taking graphene nanosheets, graphite, carbon nanotubes and the like as cross-linking agents and heat-conducting fillers. The vegetable oil carbon-based heat-conducting interface material is constructed through a Diels-Alder reaction, and the vegetable oil carbon-based heat-conducting interface material is composed of bifunctional vegetable oil resin containing thiophene groups and maleimide groups and carbon materials such as graphene nanosheets, graphite and carbon nanotubes. The heat-conducting interface material has excellent heat-conducting property and mechanical property and relatively low thermal resistance, the heat conductivity coefficient can reach 1.2-4.6 W.m <-1 >. K <-1 >, and the thermal resistance can be reduced to 0.26-0.71 cm < 2 >. K.W <-1 >.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermal interface materials, and relates to a bifunctionalized vegetable oil / carbon-based thermal interface material, a preparation method thereof and an application thereof. Background Art

[0002] With the rapid development of the third-generation semiconductors and the post-Moore's law era microelectronic integration technology, the high-density packaging and integration of electronic components have caused the heat of electronic devices to rise sharply during operation. Research shows that more than 50% of electronic device failures are caused by excessive operating temperatures, which seriously affect the performance and service life of the devices. Therefore, it is urgent to timely dissipate this part of heat through heat sinks. Developing new thermal interface materials for filling the gas voids between solid materials, effectively improving the interfacial heat conduction, and optimizing the thermal conduction performance of power devices are effective ways to ensure the reliability and safety of devices.

[0003] Carbon materials such as graphene, carbon nanotubes and graphite have high thermal conductivity coefficients, and all their physical and chemical properties are very stable. Compared with traditional metal thermal conductive fillers such as aluminum, silver or copper, etc., as thermal conductive fillers, they can endow materials with excellent thermal conductivity. However, there are differences in chemical structure, mechanical properties, physical properties, etc. between the above carbon materials and the polymer matrix. There are a large number of interfacial structures in the polymer / carbon-based composite system, resulting in a high thermal resistance inside the material, thus affecting the heat transport. The conventional method for regulating the thermal resistance between the filler and the polymer is to modify the carbon material. For example, in Chinese published text CN201810054905.5, through hydroxylation treatment, a certain number of hydroxyl groups are connected to the edge of graphene, and then the modified graphene is used as a thermal conductive filler to prepare a thermal conductive composite silicone grease. This method improves the dispersion of graphene in the thermal conductive silicone grease, avoids the agglomeration of graphene in the thermal conductive silicone grease, and at the same time improves the compatibility between graphene and the thermal conductive silicone grease, increasing the thermal conductivity of the thermal conductive silicone grease by about 34%. In addition, in Chinese published text CN202010386524.4, hydroxy-rich graphene oxide is prepared by an optimized oxidation reaction method, and the hydroxy-rich graphene oxide is reacted with alkyl phosphate or alkyl phosphite compounds to obtain modified graphene, and then the modified graphene and other components are prepared by an ultrasonic-assisted shear dispersion process in a certain proportion.

[0004] However, the above-mentioned modification methods of graphene are uncontrollable, especially the content of oxygen-containing groups. Moreover, heteroatoms are introduced as a medium on the surface or edge of graphene. Although the compatibility between graphene and the matrix is reduced to a certain extent, the process is still complex and the compatibility is not as expected. In addition, the increasing shortage of fossil energy has also brought severe energy and resource crises. Vegetable oil containing a large number of unsaturated carbon-carbon double bonds and flexible chains is a common renewable resource, with characteristics such as biodegradability, low toxicity, and low volatility. It is an environmentally friendly raw material, and is inexpensive, widely used, and has a large output. In addition, the unsaturated carbon-carbon double bonds in vegetable oil are beneficial for involving multifunctional matrix materials, and the flexible long-chain structure can be used to reduce the modulus of the material, which has great advantages in improving the interfacial thermal resistance. Therefore, it is of great significance to use vegetable oil as a precursor to prepare thermally conductive composites, and there is no prior art for preparing thermally conductive interface materials through the structural design of vegetable oil. Summary of the Invention

[0005] The purpose of the present invention is to solve the problems existing in the prior art during the preparation of thermally conductive interface materials, such as complex process, unsatisfactory thermal conductivity, and high thermal resistance between the thermally conductive filler and the resin matrix. Therefore, a method for preparing a thermally conductive interface material using vegetable oil as a raw material and carbon material as a cross-linking agent and a thermally conductive filler is provided. It can form covalent bonds in situ between the matrix and the filler through the Diels–Alder reaction, strengthen the interfacial interaction between the polymer matrix and the thermally conductive filler, facilitate the construction of phonon transmission channels, reduce the thermal resistance, and thus effectively improve the thermal conductivity of the composite material. Moreover, the preparation process is simple, the cost is low, and it is suitable for large-scale industrial production.

[0006] To achieve the above object, the present invention is realized by the following means:

[0007] The first aspect of the present invention provides a method for preparing a bifunctionalized vegetable oil / carbon-based thermally conductive interface material, comprising the following steps:

[0008] (1) Under anhydrous conditions, vegetable oil, a mercapto compound, and a photoinitiator are added to a container, and a photoinitiation reaction is carried out under a mercury lamp at room temperature to obtain a first functionalized vegetable oil; the functionalized groups of the first functionalized vegetable oil include one or more of thiophene, pyrrole, and furan;

[0009] (2) Epoxidized vegetable oil, an epoxy curing agent, and an epoxy accelerator are added to a container and heated for reaction to obtain a second functionalized vegetable oil; the functionalized groups of the second functionalized vegetable oil include maleimide;

[0010] (3) The first functionalized vegetable oil obtained in step (1) and the second functionalized vegetable oil obtained in step (2) are mixed and stirred, and carbon material is further added for heating and stirring reaction;

[0011] (4) After the reaction is completed, it is placed in a preheated mold for curing reaction, and then cooled to room temperature to obtain the product.

[0012] Preferably, the vegetable oil in step (1) is selected from one or more of castor oil, soybean oil, olive oil, rubber seed oil, and linseed oil.

[0013] Preferably, the mercapto compound in step (1) is selected from one or more of 2-thiophenemethyl mercaptan, furfuryl mercaptan, and 11-(1H-pyrrol-1-yl)undecane-1-thiol.

[0014] Preferably, the photoinitiator in step (1) is selected from one or more of 2-methyl-1-[4-(methylthio)phenyl]-2-(4-morpholinyl)-1-propanone (907), 2-hydroxy-2-methyl-1-phenyl-1-propanone (1173), 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone (2595), 2,4,6(trimethylbenzoyl)diphenylphosphine oxide (TPO), and isopropylthioxanthone (ITX).

[0015] Preferably, the molar ratio of the unsaturated double bond in the vegetable oil to the mercapto group in the mercapto compound in step (1) is 1-3:1.

[0016] Preferably, the dosage of the photoinitiator in step (1) is 1-3% of the mass of the vegetable oil.

[0017] Preferably, the power of the mercury lamp in step (1) is 200-400W.

[0018] Preferably, the time for the photoinitiated reaction in step (1) is 3-6h.

[0019] Preferably, the epoxy vegetable oil in step (2) is selected from one or more of epoxy castor oil, epoxy soybean oil, epoxy olive oil, and epoxy rubber seed oil.

[0020] Preferably, the epoxy curing agent in step (2) is selected from one or more of 3-maleimidopropionic acid, 1-(2-aminoethyl)-1H-pyrrole-2,5-dione, 4-maleimidobutyric acid, 5-maleimidovaleric acid, 6-maleimidohexanoic acid, and 11-maleamidoundecanoic acid.

[0021] Preferably, the epoxy accelerator in step (2) is selected from one or more of 1-methylimidazole, 2-methylaminopyridine, zinc acetate, 2-ethyl-4-methylimidazole, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, and 1,8-diazabicyclo[5.4.0]-7-undecene.

[0022] Preferably, in step (2), the molar ratio of the epoxy groups in the epoxy vegetable oil to the reactive groups of the epoxy curing agent is 1-2:1, and the reactive groups of the epoxy curing agent are selected from any one of carboxyl groups and amino groups.

[0023] Preferably, the dosage of the epoxy promoter in step (2) is 0.5-2.5% of the mass of the epoxy vegetable oil.

[0024] Preferably, the temperature of the heating reaction in step (2) is 120-150 °C, and the time is 2-8 h.

[0025] Preferably, in step (3), the molar ratio of the functional groups of the first functionalized vegetable oil to the functional groups of the second functionalized vegetable oil is 1:1.

[0026] Preferably, the carbon material in step (3) is selected from one or more of graphene nanosheets, graphite, and carbon nanotubes.

[0027] Preferably, the dosage of the carbon material in step (3) is 3-20% of the total mass.

[0028] Preferably, the temperature of the heating and stirring reaction in step (3) is 100-150 °C, and the time is 3-15 min.

[0029] Preferably, the temperature of the preheated mold in step (4) is 100-150 °C.

[0030] Preferably, the curing reaction in step (4) is specifically as follows: first, carry out the first-stage curing reaction at 110-140 °C for 2-4 h, and then carry out the second-stage curing reaction at 140-170 °C for 2-6 h.

[0031] The second aspect of the present invention provides a dual-functionalized vegetable oil / carbon-based thermal conductive interface material prepared according to the above preparation method.

[0032] The third aspect of the present invention provides the application of the dual-functionalized vegetable oil / carbon-based thermal conductive interface material prepared according to the above preparation method in the heat dissipation of electronic devices.

[0033] Compared with the existing technology, the present invention has the following beneficial effects:

[0034] (1) In the present invention, vegetable oils and epoxidized vegetable oils, which are biodegradable, low-toxic, low-volatile, environmentally friendly and renewable, are used as polymer matrix materials. A thiol compound containing a thiophene group and an epoxy curing agent containing a maleimide group are used to construct a bifunctional vegetable oil-based resin through "thiol-ene" click chemistry and epoxy ring-opening reaction respectively. Graphene nanosheets, graphite, carbon nanotubes, etc. are used as crosslinking agents and thermal conductive fillers. The Diels–Alder reaction is utilized to construct a bifunctional vegetable oil / carbon-based thermal conductive interface material, optimizing the interaction between the resin matrix and the heterogeneous interface of the thermal conductive filler, improving the overall thermal conductivity of the material, reducing the surface treatment process of the thermal conductive filler, and simultaneously realizing the high-value application of the biomass resource vegetable oil.

[0035] (2) The thermal conductive interface material prepared in the present invention uses vegetable oils grafted with different thiol compounds and epoxidized vegetable oils crosslinked with epoxy curing agents containing different functional groups as polymer matrices, and graphene nanosheets, graphite, carbon nanotubes as crosslinking agents and thermal conductive fillers. It can effectively improve the thermal conductivity, thermal resistance and mechanical properties of the thermal conductive interface material, with a thermal conductivity of up to 1.2 - 4.6 W·m -1 ·K -1 , and the thermal resistance can be reduced to 0.26 - 0.71 cm 2 ·K·W -1 . BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is the DSC diagram of the soybean oil / furfuryl mercaptan resin and graphite prepared in Example 2 of the present invention.

[0037] Figure 2 is the Raman spectrum of the soybean oil / furfuryl mercaptan resin and graphite prepared in Example 2 of the present invention.

[0038] Figure 3 are the digital photos of the first functionalized vegetable oil in Comparative Example 1 (left) and Comparative Example 2 (right). DETAILED DESCRIPTION OF THE INVENTION

[0039] To make the objectives, technical solutions and effects of the present invention clearer and more definite, the present invention will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0040] Unless otherwise defined, all the technical terms used hereinafter have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the protection scope of the present invention. Unless otherwise specifically stated, all kinds of raw materials, reagents, instruments and equipment used in the present invention can be obtained through the market or can be prepared by existing methods.

[0041] Example 1

[0042] A bifunctionalized vegetable oil / carbon-based thermal conductive interface material, and its preparation method specifically includes the following steps:

[0043] (1) Based on thiol-ene click chemistry, 0.005 mol of castor oil, 0.01 mol of 2-thiophenemethyl mercaptan (where the molar ratio of the unsaturated double bond in castor oil to the mercapto group in 2-thiophenemethyl mercaptan is 1:1), and 0.047 g of 2-methyl-1-[4-(methylthio)phenyl]-2-(4-morpholinyl)-1-propanone (907) (the dosage is 1% of the mass of castor oil) are added to a round-bottom flask under anhydrous conditions, and magnetically stirred for 3 h under the conditions of a 300 W mercury lamp and room temperature (25 °C) for photoinitiated reaction to obtain a first functionalized vegetable oil containing thiophene groups.

[0044] (2) Based on ring-opening reaction, 0.002 mol of epoxidized soybean oil, 0.01 mol of 5-maleimidopentanoic acid (where the molar ratio of the epoxy group in epoxidized soybean oil to the carboxyl group in 5-maleimidopentanoic acid is 1:1), and 0.0122 g of 1-methylimidazole (the dosage is 0.5% of the mass of epoxidized soybean oil) are added to a round-bottom flask, and magnetically stirred at 130 °C for heating reaction for 5 h to obtain a second functionalized vegetable oil containing maleimide groups.

[0045] (3) Based on the Diels–Alder reaction, the first functionalized vegetable oil obtained in step (1) and the second functionalized vegetable oil obtained in step (2) are mixed and stirred, where the molar ratio of the thiophene group in the first functionalized oil to the maleimide group in the second functionalized oil is 1:1, and graphene nanosheets as a crosslinking agent and a thermal conductive filler for the bifunctionalized vegetable oil / carbon-based thermal conductive interface material are added to the round-bottom flask, and heated and stirred at 120 °C for 5 min; the dosage of graphene nanosheets is 3% of the total mass.

[0046] (4) After the reaction is completed, it is placed in a silicone mold with a preheating temperature of 120 °C, first cured at 120 °C for the first stage for 2 h, then cured at 140 °C for the second stage for 2 h, and then cooled to room temperature to obtain the bifunctionalized vegetable oil / carbon-based thermal conductive interface material.

[0047] Example 2

[0048] A bifunctionalized vegetable oil / carbon-based thermal conductive interface material, and its preparation method specifically includes the following steps:

[0049] (1) Based on thiol-ene click chemistry, 0.005 mol of soybean oil, 0.01 mol of furfuryl mercaptan (where the molar ratio of unsaturated double bonds in soybean oil to mercapto groups in furfuryl mercaptan is 2:1), and 0.112 g of 2-hydroxy-2-methyl-1-phenyl-1-propanone (1173) (the dosage is 2.5% of the mass of epoxidized soybean oil) were added to a round-bottom flask under anhydrous conditions. The mixture was magnetically stirred for 4 h under a 200 W mercury lamp at room temperature (25 °C) for photoinitiation reaction to obtain the first functionalized vegetable oil containing furan groups.

[0050] (2) Based on ring-opening reaction, 0.003 mol of epoxidized olive oil, 0.01 mol of 11-maleamidoundecanoic acid (where the molar ratio of epoxy groups in epoxidized olive oil to carboxyl groups in 11-maleamidoundecanoic acid is 1:1), and 0.038 g of 2-methylaminopyridine (the dosage is 1% of the mass of epoxidized olive oil) were added to a round-bottom flask. The mixture was magnetically stirred and heated at 140 °C for 2 h for heating reaction to obtain the second functionalized vegetable oil containing maleimide groups.

[0051] (3) Based on the Diels–Alder reaction, the first functionalized vegetable oil obtained in step (1) and the second functionalized vegetable oil obtained in step (2) were mixed and stirred. The molar ratio of furan groups in the first functionalized vegetable oil to maleimide groups in the second functionalized vegetable oil is 1:1. Graphite flakes as a cross-linking agent and a thermal conductive filler for the bifunctional vegetable oil / carbon-based thermal conductive interface material were added to the round-bottom flask, and the mixture was heated and stirred at 130 °C for 8 min; the dosage of graphite flakes is 10% of the total mass. The DSC diagram and Raman spectrum are shown respectively as Figure 1-2 shown. The results show that, compared with graphite flakes, exothermic peaks and endothermic peaks appeared at about 110 °C and 150 °C respectively in the DSC curve of the bifunctional vegetable oil / carbon-based thermal conductive interface material, confirming that the Diels–Alder reaction occurred between the resin and graphite flakes. At the same time, the microscopic structure of graphite flakes before and after the reaction was characterized by Raman. The intensity ratio of the D peak (defect peak) and G peak (band peak) of the Raman spectrum changed significantly, further confirming that the Diels–Alder reaction occurred between the resin and graphite flakes.

[0052] (4) After the reaction, it was placed in a silicone mold with a preheating temperature of 130 °C. First, the first-stage curing reaction was carried out at 130 °C for 3 h, then the second-stage curing reaction was carried out at 150 °C for 4 h, and then it was cooled to room temperature to obtain the bifunctional vegetable oil / carbon-based thermal conductive interface material.

[0053] Example 3

[0054] A bifunctional vegetable oil / carbon-based thermal conductive interface material, and its preparation method specifically includes the following steps:

[0055] (1) Based on thiol-ene click chemistry, 0.007 mol of olive oil, 0.013 mol of 11-(1H-pyrrol-1-yl)undecane-1-thiol (where the molar ratio of the unsaturated double bonds in corn oil to the mercapto groups in 11-(1H-pyrrol-1-yl)undecane-1-thiol is 1.5:1), and 0.137 g of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone (2595) (the dosage is 1.5% of the mass of olive oil) were added to a round-bottom flask, and magnetically stirred for 5 h under a 400 W mercury lamp at room temperature (25 °C) for a photoinitiation reaction to obtain a first functionalized vegetable oil containing pyrrole groups.

[0056] (2) Based on the ring-opening reaction, 0.013 mol of epoxidized castor oil, 0.013 mol of 1-(2-aminoethyl)-1H-pyrrole-2,5-dione (where the molar ratio of the epoxy groups in epoxidized castor oil to the amino groups in 1-(2-aminoethyl)-1H-pyrrole-2,5-dione is 2:1), and 0.243 g of zinc acetate (the dosage is 2% of the mass of epoxidized castor oil) were added to a round-bottom flask, and magnetically stirred at 150 °C for a heating reaction for 6 h to obtain a second functionalized vegetable oil containing maleimide groups.

[0057] (3) Based on the Diels–Alder reaction, the first functionalized vegetable oil obtained in step (1) and the second functionalized vegetable oil obtained in step (2) were mixed and stirred, where the molar ratio of the pyrrole groups in the first functionalized vegetable oil to the maleimide groups in the second functionalized vegetable oil is 1:1, and carbon nanotubes, which are used as a cross-linking agent and a thermally conductive filler for the bifunctional vegetable oil / carbon-based thermally conductive interface material, were added to a round-bottom flask, and heated and stirred at 150 °C for a reaction for 3 min; the dosage of carbon nanotubes is 15% of the total mass.

[0058] (4) After the reaction, it was placed in a silicone mold preheated to 150 °C, first cured at 130 °C for the first-stage curing reaction for 2 h, then cured at 160 °C for the second-stage curing reaction for 5 h, and then cooled to room temperature to obtain the bifunctional vegetable oil / carbon-based thermally conductive interface material.

[0059] Example 4

[0060] A bifunctional vegetable oil / carbon-based thermally conductive interface material, and its preparation method specifically includes the following steps:

[0061] (1) Based on thiol-ene click chemistry, 0.004 mol of linseed oil, 0.008 mol of 2-thiophenemethyl mercaptan (where the molar ratio of unsaturated double bonds in linseed oil to mercapto groups in 2-thiophenemethyl mercaptan is 3:1), and 0.068 g of 2,4,6-(trimethylbenzoyl) diphenylphosphine oxide (TPO) (the dosage is 1.5% of the mass of linseed oil) were added to a round-bottom flask. Under a 300 W mercury lamp and at room temperature (25 °C), magnetic stirring was carried out for 6 h for a photoinitiation reaction to obtain a first functionalized vegetable oil containing thiophene groups.

[0062] (2) Based on the ring-opening reaction, 0.0023 mol of epoxy rubber seed oil, 0.008 mol of 1-(2-aminoethyl)-1H-pyrrole-2,5-dione (where the molar ratio of epoxy groups in epoxy rubber seed oil to amino groups in 1-(2-aminoethyl)-1H-pyrrole-2,5-dione is 1:1), and 0.073 g of 2-ethyl-4-methylimidazole (the dosage is 2.5% of the mass of epoxy rubber seed oil) were added to a round-bottom flask. Magnetic stirring was carried out at 120 °C for a heating reaction for 4 h to obtain a second functionalized vegetable oil containing maleimide groups.

[0063] (3) Based on the Diels–Alder reaction, the first functionalized vegetable oil obtained in step (1) and the second functionalized vegetable oil obtained in step (2) were mixed and stirred. The molar ratio of thiophene groups in the first functionalized vegetable oil to maleimide groups in the second functionalized vegetable oil is 1:1. Graphene nanosheets and carbon nanotubes, which are cross-linking agents and thermal conductive fillers for the bifunctional vegetable oil / carbon-based thermal conductive interface material, were added to a round-bottom flask. Heating and stirring reaction were carried out at 140 °C for 5 min; the dosage of graphene nanosheets and carbon nanotubes is 8% of the total mass, and the mass ratio of graphene nanosheets to carbon nanotubes is 2:1.

[0064] (4) After the reaction, it was placed in a silicone mold with a preheating temperature of 140 °C. First, a first-stage curing reaction was carried out at 140 °C for 2 h, then a second-stage curing reaction was carried out at 170 °C for 4 h, and then it was cooled to room temperature to obtain the bifunctional vegetable oil / carbon-based thermal conductive interface material.

[0065] Example 5

[0066] A bifunctional vegetable oil / carbon-based thermal conductive interface material, and its preparation method specifically includes the following steps:

[0067] (1) Based on thiol-ene click chemistry, 0.01 mol of rubber seed oil, 0.0029 mol of furfuryl mercaptan (where the molar ratio of unsaturated double bonds in sunflower seed oil to mercapto groups in furfuryl mercaptan is 1:1), and 0.243 g of isopropyl thioxanthone (ITX) (the dosage is 2% of the mass of the rubber oil) were added to a round-bottom flask under anhydrous conditions. The mixture was magnetically stirred for 4 h under a 300 W mercury lamp at room temperature (25 °C) for a photoinitiation reaction to obtain the first functionalized vegetable oil containing furan groups.

[0068] (2) Based on the ring-opening reaction, 0.001 mol of epoxy olive oil, 0.0029 mol of 6-maleimidocaproic acid (where the molar ratio of epoxy groups in epoxy olive oil to carboxyl groups in 6-maleimidocaproic acid is 1:1), and 0.021 g of 1,5,7-triazabicyclo[4.4.0]dec-5-ene (the dosage is 2% of the mass of epoxy olive oil) were added to a round-bottom flask. The mixture was magnetically stirred at 140 °C for a heating reaction for 8 h to obtain the second functionalized vegetable oil containing maleimide groups.

[0069] (3) Based on the Diels–Alder reaction, the first functionalized vegetable oil obtained in step (1) and the second functionalized vegetable oil obtained in step (2) were mixed and stirred. The molar ratio of furan groups in the first functionalized vegetable oil to maleimide groups in the second functionalized vegetable oil was 1:1. Graphene nanosheets and carbon nanotubes, which are crosslinking agents and thermal conductive fillers for the bifunctional vegetable oil / carbon-based thermal conductive interface material, were added to a round-bottom flask. The mixture was heated and stirred at 100 °C for 15 min; the dosage of graphene nanosheets and carbon nanotubes was 15% of the total mass, and the mass ratio of graphene nanosheets to carbon nanotubes was 3:1.

[0070] (4) After the reaction was completed, the mixture was placed in a silicone mold preheated to 100 °C. First, it was subjected to a first-stage curing reaction at 110 °C for 4 h, then a second-stage curing reaction at 140 °C for 4 h, and then cooled to room temperature to obtain the bifunctional vegetable oil / carbon-based thermal conductive interface material.

[0071] Example 6

[0072] A bifunctional vegetable oil / carbon-based thermal conductive interface material, and its preparation method specifically includes the following steps:

[0073] (1) Based on thiol-ene click chemistry, 0.008 mol of soybean oil, 0.002 mol of furfuryl mercaptan (where the molar ratio of unsaturated double bonds in soybean oil to mercapto groups in furfuryl mercaptan is 1:1), and 0.1 g of isopropyl thioxanthone (ITX) (the dosage is 1% of the mass of soybean oil) were added to a round-bottom flask under anhydrous conditions. The mixture was magnetically stirred for 6 h under a 300 W mercury lamp at room temperature (25 °C) for a photoinitiation reaction to obtain the first functionalized vegetable oil containing furan groups.

[0074] (2) Based on the ring-opening reaction, 0.001 mol of epoxidized rubber seed oil, 0.002 mol of 4-maleimidocaproic acid (where the molar ratio of the epoxy groups in the epoxidized rubber seed oil to the carboxyl groups in the 4-maleimidocaproic acid is 1:1), and 0.026 g of 1,8-diazabicyclo[5.4.0]-7-undecene (the dosage is 2% of the mass of the epoxidized rubber seed oil) are added to a round-bottom flask, and heated and reacted with magnetic stirring at 150 °C for 7 h to obtain a second functionalized vegetable oil containing maleimide groups.

[0075] (3) Based on the Diels–Alder reaction, the first functionalized vegetable oil obtained in step (1) and the second functionalized vegetable oil obtained in step (2) are mixed and stirred. The molar ratio of the furan groups in the first functionalized vegetable oil to the maleimide groups in the second functionalized vegetable oil is 1:1. Graphene nanosheets and carbon nanotubes, which are used as crosslinking agents and thermal conductive fillers for the bifunctional vegetable oil / carbon-based thermal conductive interface material, are placed in a round-bottom flask, and heated and stirred at 120 °C for 10 min; the dosage of graphene nanosheets and carbon nanotubes is 20% of the total mass, and the mass ratio of graphene nanosheets to carbon nanotubes is 5:1.

[0076] (4) After the reaction is completed, it is placed in a silica gel mold preheated to 120 °C, first cured at 120 °C for the first stage for 3 h, then cured at 160 °C for the second stage for 6 h, and then cooled to room temperature to obtain the bifunctional vegetable oil / carbon-based thermal conductive interface material.

[0077] Comparative Example 1

[0078] A vegetable oil / carbon-based thermal conductive interface material, and its preparation method specifically includes the following steps:

[0079] (1) Based on thiol-ene click chemistry, 0.015 mol of rubber seed oil, 0.0044 mol of furfuryl mercaptan (where the molar ratio of the unsaturated double bonds in the sunflower seed oil to the mercapto groups in the furfuryl mercaptan is 1:1), and 0.379 g of isopropylthioxanthone (ITX) (the dosage is 2% of the mass of the rubber oil) are added to a round-bottom flask under anhydrous conditions, and photoinitiated reaction is carried out with magnetic stirring for 4 h at 300 W mercury lamp and room temperature (25 °C) to obtain a functionalized vegetable oil containing furan groups.

[0080] (2) Graphene nanosheets and carbon nanotubes are added as thermal conductive fillers to the above round-bottom flask, and heated and stirred at 120 °C for 15 min; the dosage of graphene nanosheets and carbon nanotubes is 18% of the total mass, and the mass ratio of graphene nanosheets to carbon nanotubes is 6:1.

[0081] (3) After the reaction is completed, it is placed in a silicone mold preheated to 120 °C. First, the first-stage curing reaction is carried out at 120 °C for 2 h, then the second-stage curing reaction is carried out at 150 °C for 2 h, and then it is cooled to room temperature to obtain the thermal conductive interface material.

[0082] Comparative Example 2

[0083] A vegetable oil / carbon-based thermal conductive interface material, and its preparation method specifically includes the following steps:

[0084] (1) Based on the ring-opening reaction, 0.0363 mol of epoxidized soybean oil, 0.05 mol of 1-(2-aminoethyl)-1H-pyrrole-2,5-dione (where the molar ratio of the epoxy group in epoxidized soybean oil to the amino group in 1-(2-aminoethyl)-1H-pyrrole-2,5-dione is 3:1), and 0.233 g of zinc acetate (the dosage is 0.5% of the mass of epoxidized soybean oil) are added to a round-bottom flask, and heated and reacted with magnetic stirring at 150 °C for 6 h to obtain a functionalized vegetable oil containing maleimide groups.

[0085] (2) Graphene nanosheets are added as a thermal conductive filler to the round-bottom flask, and heated and stirred at 120 °C for 15 min; the dosage of graphene nanosheets is 20% of the total mass.

[0086] (3) After the reaction is completed, it is placed in a silicone mold preheated to 120 °C. First, the first-stage curing reaction is carried out at 120 °C for 3 h, then the second-stage curing reaction is carried out at 150 °C for 2 h, and then it is cooled to room temperature to obtain the thermal conductive interface material.

[0087] Comparative Example 3

[0088] A vegetable oil / carbon-based thermal conductive interface material, and its preparation method specifically includes the following steps:

[0089] (1) Based on the ring-opening reaction, 0.01 mol of epoxidized soybean oil, 0.0025 mol of 4,4'-diaminodicyclohexylmethane (where the molar ratio of the epoxy group in epoxidized soybean oil to the amino group in 4,4'-diaminodicyclohexylmethane is 2:1), 0.192 g of 4-dimethylaminopyridine, and graphite flakes are added as a thermal conductive filler to the round-bottom flask, and heated and stirred at 120 °C for 15 min; the dosage of graphene nanosheets is 3% of the total mass.

[0090] (2) After the reaction is completed, it is placed in a silicone mold preheated to 120 °C. First, the first-stage curing reaction is carried out at 120 °C for 2 h, then the second-stage curing reaction is carried out at 150 °C for 2 h, and then it is cooled to room temperature to obtain the graphene nanosheet / vegetable oil-based thermal conductive interface material.

[0091] Verification Example 1

[0092] Respectively take the thermally conductive interface materials prepared in Examples 1-6 and Comparative Examples 1-3, and measure their thermal conductivity (W·m -1 ·K -1 ) and thermal resistance (cm 2 ·K·W -1 ) according to the conventional methods in the art (tested according to ISO 22007-2, ASTM D3574 and ASTM C1784 standards respectively). The test results are shown in Table 1 below.

[0093] Table 1 Test Results of Thermal Conductivity and Thermal Resistance of Thermally Conductive Interface Materials

[0094]

[0095] The results show that in Comparative Example 1 and Comparative Example 2, vegetable oil resin matrices containing furan groups and maleimide groups were respectively prepared. Although groups that can react with graphene or carbon nanotubes were introduced in the functionalized vegetable oils, the materials presented in liquid or paste form (as Figure 3 shown), which did not meet the morphological requirements of the solid thermally conductive interface material to be prepared in the present invention, so the performance of the materials could not be measured. In Comparative Example 3, the vegetable oil resin matrix did not undergo a Diels–Alder reaction with graphene, and no cross-interaction could be formed at the interface between the resin matrix and the filler, and graphene did not participate in the formation process of the crosslinked network of the system. The thermal conductivity of this composite material was only 0.8 W·m -1 ·K -1 , and the thermal resistance was 0.86 cm 2 ·K·W -1 . In contrast, in the first functionalized vegetable oil and the second functionalized vegetable oil prepared in the present invention, functional groups that can undergo Diels–Alder crosslinking with graphene nanosheets, graphite, carbon nanotubes, etc. were respectively introduced. Not only can covalent crosslinking occur between the two functionalized vegetable oils, but also bonding occurs with the filler, greatly enhancing the interaction between the resin matrix and the filler. Therefore, for the thermally conductive interface material prepared according to the examples of the present invention, its thermal conductivity has been significantly improved and the thermal resistance has been effectively reduced.

[0096] The above specific implementation part specifically introduced the analysis methods involved in the present invention. It should be noted that the above introduction is only to help those skilled in the art better understand the methods and ideas of the present invention, rather than a limitation on the relevant content. Without departing from the principle of the present invention, those skilled in the art can also make appropriate adjustments or modifications to the present invention, and the above adjustments and modifications should also fall within the protection scope of the present invention.

Claims

1. A preparation method of a bifunctionalized vegetable oil / carbon-based thermal conductive interface material, characterized in that, It includes the following steps: (1) Under anhydrous conditions, vegetable oil, a mercapto compound, and a photoinitiator are added to a container, and a photoinitiated reaction is carried out under a mercury lamp at room temperature to obtain a first functionalized vegetable oil; the functionalized groups of the first functionalized vegetable oil include one or more of thiophene, pyrrole, and furan; (2) Epoxidized vegetable oil, an epoxy curing agent, and an epoxy accelerator are added to a container for a heating reaction to obtain a second functionalized vegetable oil; the functionalized groups of the second functionalized vegetable oil include maleimide; (3) The first functionalized vegetable oil obtained in step (1) and the second functionalized vegetable oil obtained in step (2) are stirred and mixed, and a carbon material is further added for a heating and stirring reaction; (4) After the reaction is completed, it is placed in a preheated mold for a curing reaction, and then cooled to room temperature to obtain the product.

2. The preparation method according to claim 1, wherein, The mercapto compound in step (1) is selected from one or more of 2-thiophenemethanethiol, furfuryl mercaptan, and 11-(1H-pyrrol-1-yl)undecane-1-thiol.

3. The preparation method according to claim 1, characterized in that, The photoinitiator in step (1) is selected from one or more of 2-methyl-1-[4-(methylthio)phenyl]-2-(4-morpholinyl)-1-propanone (907), 2-hydroxy-2-methyl-1-phenyl-1-propanone (1173), 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone (2595), 2,4,6(trimethylbenzoyl)diphenylphosphine oxide (TPO), and isopropylthioxanthone (ITX).

4. The preparation method according to claim 1, wherein In step (1), the molar ratio of the unsaturated double bonds in the vegetable oil to the mercapto groups in the mercapto compound is 1-3:

1.

5. The preparation method according to claim 1, wherein The epoxy curing agent in step (2) is selected from one or more of 3-maleimidopropionic acid, 1-(2-aminoethyl)-1H-pyrrole-2,5-dione, 4-maleimidobutyric acid, 5-maleimidopentanoic acid, 6-maleimidohexanoic acid, and 11-maleamidoundecanoic acid.

6. The preparation method according to claim 1, characterized in that, The epoxy accelerator in step (2) is selected from one or more of 1-methylimidazole, 2-methylaminopyridine, zinc acetate, 2-ethyl-4-methylimidazole, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, and 1,8-diazabicyclo[5.4.0]-7-undecene.

7. The preparation method according to claim 1, wherein, In step (2), the molar ratio of the epoxy groups in the epoxidized vegetable oil to the reactive groups of the epoxy curing agent is 1-2:1, and the reactive groups of the epoxy curing agent are selected from any one of carboxyl groups and amino groups.

8. The preparation method according to claim 1, wherein, The curing reaction in step (4) is specifically: first, a first-stage curing reaction is carried out at 110-140 °C for 2-4 h, and then a second-stage curing reaction is carried out at 140-170 °C for 2-6 h.

9. A dual-functionalized vegetable oil / carbon-based thermal conductive interface material prepared by the preparation method according to any one of claims 1-8.

10. Application of the dual-functionalized vegetable oil / carbon-based thermal conductive interface material prepared by the preparation method according to any one of claims 1-8 in heat dissipation of electronic devices.

Images