N-heterocyclic carbene metal complex and preparation method thereof, NHC-M / BN preparation method and cooling liquid

Abstract

The invention discloses an N-heterocyclic carbene metal complex and a preparation method thereof, a preparation method of NHC-M / BN.The preparation method of the N-heterocyclic carbene metal complex comprises the steps that 1, 3-dimethylimidazole iodized salt, silver oxide and silver carbonate are weighed and dissolved in acetonitrile, a reflux heating reaction is carried out, after the reaction is completed, filtering is carried out, solids are removed, the solution is subpackaged in small bottles, and the N-heterocyclic carbene metal complex is obtained. The method comprises the following steps: mixing acetonitrile and acetone, sealing and pricking, sealing in a container filled with acetone, standing, mutually diffusing acetonitrile and acetone, obtaining an N-heterocyclic carbene silver complex crystal after 3-5 days, and drying to obtain a product. The hexagonal boron nitride is subjected to surface modification by adopting an N-heterocyclic carbene metal complex, a novel composite nano heat-conducting filler is developed and serves as an auxiliary component of an electronic cooling liquid formula, and the problems that the electronic cooling liquid taking the hexagonal boron nitride as a heat-conducting additive is poor in compatibility and stability and the like are solved; a novel formula with better performance and environment friendliness is provided for the field of electronic coolants.

Description

Technical Field

[0001] The present invention relates to the technical field of coolants, in particular to a nitrogen heterocyclic carbene metal complex and a preparation method thereof, and a preparation method of NHC-M / BN and a coolant. Background Art

[0002] Cooling fluids are widely used in many fields, and their main function is to absorb and dissipate heat to maintain the temperature of the equipment or system during normal operation. The formula of electronic coolant usually uses perfluoropolyether (PFPE), perfluorohexanone, etc. as the main ingredients, supplemented by some additives, such as boron nitride nanoparticles, phosphate flame retardants, etc., to meet the use requirements in different scenarios. For example, Chinese patent 118834666A discloses a method for preparing a new phase-change electronic coolant, which uses perfluoropolyether, perfluorohexanone, silicone oil, mineral white oil, transformer oil or kerosene as the coolant base liquid. By adding phase-change nano-microcapsules, the coolant can produce phase changes at low temperatures and relatively high temperatures, and has good stability, lower cost and greater power density. In addition, in the development of electronic coolants, researchers are also constantly trying to introduce new ingredients to optimize their performance. For example, Chinese patent CN117720889A mentions the use of additives such as electronic fluorinated fluid, dispersants, wetting agents, and thermally conductive fillers in the development of immersion coolant formulations. Boron nitride, as a thermally conductive filler, possesses high thermal conductivity, effectively conducting heat away from the heat source. Compared to traditional coolant additives, it can more effectively maintain the temperature balance of the cooling system in high-temperature operating environments, avoiding equipment performance degradation or even damage due to excessive temperatures. Boron nitride also possesses excellent thermal stability and chemical inertness. In the complex chemical system of the coolant and during long-term circulation, it is not prone to chemical reactions with other components, ensuring the long-term stability of its own performance, thereby guaranteeing the reliability of the overall coolant quality.

[0003] However, the application of boron nitride in coolants has a more prominent problem, that is, poor compatibility and easy aggregation and precipitation. The reason is that the surface of boron nitride lacks active groups, resulting in poor dispersibility in organic solvents and polymers, which limits its effect on improving the performance of electronic coolants. When boron nitride particles aggregate in the coolant, the uniformity of the coolant will be destroyed, and the concentration of boron nitride may be too high or too low in some areas. In areas where the concentration of boron nitride is too high, precipitation is likely to occur, causing the boron nitride thermal conductive additive to fail. It may also hinder the normal flow of the coolant due to the close accumulation between the particles, reducing the heat dissipation efficiency. Summary of the Invention

[0004] To address the above-mentioned technical problems, the present invention aims, first, to provide a nitrogen heterocyclic carbene metal complex and a method for preparing the same; second, to provide a method for preparing NHC-M / BN; and third, to provide a coolant containing NHC-M / BN. By using the nitrogen heterocyclic carbene metal complex to surface-modify hexagonal boron nitride, a novel composite nano-thermal conductive filler was developed as an auxiliary component in electronic coolant formulations. This approach addresses the poor compatibility and stability of electronic coolants containing hexagonal boron nitride as a thermally conductive additive, providing a novel, environmentally friendly, and superior performance formula for electronic coolants.

[0005] To achieve the first objective, the present invention is implemented through the following technical solution: a method for preparing an azoheterocyclic carbene metal complex, characterized in that: 1,3-dimethylimidazolium iodide, silver oxide, and silver carbonate are weighed and dissolved in acetonitrile, subjected to reflux heating for reaction, filtered after the reaction, solids removed, the solution divided into vials, sealed and punctured, then placed in a container containing acetone, sealed, and allowed to stand to allow acetonitrile and acetone to diffuse in the gas phase, obtaining azoheterocyclic carbene silver complex crystals after 3-5 days, and drying to obtain a product.

[0006] In the above scheme, the molar ratio of 1,3-dimethylimidazolium iodide, silver oxide and silver carbonate is 1-5:1:1.

[0007] In the above scheme: the reaction temperature is 50-60°C.

[0008] In the above scheme: reaction time is 20-30h.

[0009] In the above scheme: vacuum drying is adopted for drying, and the drying temperature is 40-50°C.

[0010] A nitrogen heterocyclic carbene metal complex prepared by the method for preparing a nitrogen heterocyclic carbene metal complex.

[0011] The second object of the present invention is achieved by providing a method for preparing NHC-M / BN, characterized in that hexagonal boron nitride nanosheets are dispersed in methanol, a nitrogen heterocyclic carbene silver complex is added, ultrasonically assisted dispersion and dissolution is performed, and after thorough mixing, the solvent is volatilized at room temperature to prepare the nitrogen heterocyclic carbene silver complex / boron nitride composite nanomaterial NHC-M / BN.

[0012] In the above scheme, the amount of the nitrogen heterocyclic carbene silver complex added is 3%-8% of the mass of the hexagonal boron nitride nanosheets.

[0013] The third object of the present invention is achieved as follows: a coolant, characterized in that it is made of the following raw materials in parts by weight: 85-90 parts of perfluoropolyether, 2-5 parts of NHC-M / BN, 3-5 parts of methyl ethyl ether, 4-6 parts of phosphate flame retardant, 0.1-0.15 parts of butylated hydroxytoluene, and 0.05-0.1 parts of fluorocarbon surfactant.

[0014] Hexagonal boron nitride (h-BN) not only has the characteristics of low density and graphite-like layered structure, which can significantly improve thermal conductivity, but also maintain good electrical insulation. Functional modification is the key to the widespread application of h-BN in the fields of electronic coolants and electronic devices. Functional modification includes covalent bond modification and non-covalent bond modification. Non-covalent bond modification modifies the surface of hexagonal boron nitride through van der Waals forces, hydrogen bonds, π-π interactions and non-covalent coordination bonds of organic molecules or inorganic molecules, so that it can be stably dispersed in organic solvents and polymers. The nitrogen heterocyclic carbene metal complex (NHC-M) of the present invention has a large π bond and is easy to form a composite material with other compounds with large π bonds. The invention mainly utilizes the strong π-π interaction between NHC-M and h-BN to modify the surface of hexagonal boron nitride, improve its dispersibility in fluorinated electronic coolants, and enhance the comprehensive performance of the coolant.

[0015] Compared with the prior art, the cooling liquid of the present invention has the advantages and positive effects

[0016] (1) Excellent high temperature stability

[0017] The nitrogen heterocyclic carbene metal complex added to the formula of the coolant of the present invention can form a stable composite nanomaterial with hexagonal boron nitride. Its structure is stable at high temperatures and will not be destroyed within the range of 256°C, giving the coolant excellent high-temperature stability, ensuring long-lasting and reliable performance under high-temperature conditions, and bringing an excellent performance experience to the cooling system.

[0018] (2) Low density, high resistivity, high surface tension, high boiling point, high thermal conductivity

[0019] The coolant of this invention has a low density, approximately 50% lower than similar products; a high resistivity, excellent insulation properties; a high surface tension, and good weather resistance; a high boiling point, a high safety factor, and no health risks associated with passive inhalation when used in air; and a high thermal conductivity, approximately double that of similar products. The coolant of this invention exhibits no coagulation.

[0020] (3) Environmental friendliness and low toxicity

[0021] The coolant of the present invention uses nitrogen heterocyclic carbene silver complex as a functional additive, has no environmental safety risk, is non-toxic, has extremely low volatility, and ensures material compatibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The molecular structure diagram of the nitrogen heterocyclic carbene silver complex.

[0023] Figure 2 This is the thermogravimetric diagram of NHC-M / BN composite nanomaterials. DETAILED DESCRIPTION

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0025] Example 1

[0026] Preparation of nitrogen heterocyclic carbene metal complexes:

[0027] Weigh 1,3-dimethylimidazolium iodide (1 mmol), silver oxide (1 mmol), and silver carbonate (1 mmol), dissolve them in a container containing 20 mL of acetonitrile, and place the mixture on a constant temperature heating magnetic stirrer for stirring at 50°C for 30 h. After the reaction is completed, the unreacted solid is separated by filtration to obtain a clear and transparent solution, which is then dispensed into small bottles in 2-3 ml portions, sealed, and then pierced with holes (sealing can be done with a bottle cap or a film such as plastic wrap. Acetonitrile can evaporate while acetone can enter. Multiple small holes are pierced with a needle, with a pore size of about 0.2 mm). The solution is then placed in a 50 ml beaker containing 10 ml of acetone, sealed, and allowed to stand for vapor diffusion (acetonitrile-acetone system, that is, ensuring that the liquid solvent cannot directly enter or exit, relying on vapor volatilization). A nitrogen heterocyclic carbene silver complex crystal is obtained in 3 to 5 days, and finally vacuum dried (40-50° C., drying for 6 h) to obtain dry nitrogen heterocyclic carbene silver complex crystals. The yield is calculated to be 75%.

[0028] The single crystal of the compound was obtained by vapor diffusion method using acetonitrile / acetone system, and the structure of the product was analyzed by single crystal diffractometer. Figure 1 As shown, the nitrogen heterocyclic carbene silver complex of the present invention has a unique molecular structure, with an iodine silver cluster as the structural center, bridged by nitrogen heterocyclic carbenes at both ends, and surrounded by free bicarbonate ions. The single crystal structure of the compound reveals a strong coordination interaction between the metal and the nitrogen heterocyclic ring, which significantly improves the compound's structural stability and enhances its high-temperature stability.

[0029] The skeleton structure of this complex is similar to that of hexagonal boron nitride, and it also has a graphite-like layered planar structure. This is the main intrinsic reason why it can be used to functionally modify hexagonal boron nitride. Secondly, bicarbonate ions can form hydrogen bonds with hexagonal boron nitride, fluorides such as perfluoropolyether, and some functional additives. In addition, the silver ions in the complex can also form Ag-N coordination bonds with the nitrogen atoms of hexagonal boron nitride. The above three factors can enhance the interaction between organic and inorganic materials, contribute to the stable dispersion of hexagonal boron nitride, and enhance its compatibility with the various components of electronic coolant.

[0030] Example 2

[0031] Preparation of nitrogen heterocyclic carbene metal complexes:

[0032] Weigh 5mmol of 1,3-dimethylimidazolium iodide (excess 1,3-dimethylimidazolium iodide), 1mmol of silver oxide, and 1mmol of silver carbonate, dissolve in a container filled with 30mL of acetonitrile, and place on a constant temperature heating magnetic stirrer to stir, and react and stir for 20h at 60℃. After the reaction is completed, the unreacted solid is separated by filtration to obtain a clear solution, which is then divided into 2-3ml bottles, sealed and pierced (sealing can be achieved by using a bottle cap or a film such as a preservative film. Acetonitrile can evaporate and acetone can enter at the same time), then placed in a 50ml beaker filled with 10ml of acetone, sealed, allowed to stand, and vapor diffusion (acetonitrile-acetone system) is performed. A nitrogen heterocyclic carbene silver complex crystal is obtained in 3-5 days, and finally vacuum dried (40-50℃, dried for 6h) to obtain a nitrogen heterocyclic carbene silver complex dry crystal. The calculated yield is 82%, and the single crystal structure is the same as in Example 1.

[0033] Example 3

[0034] Preparation of NHC-M / BN composite nanomaterials:

[0035] Hexagonal boron nitride nanosheets are dispersed in methanol, and a nitrogen heterocyclic carbene silver complex is added. The amount of the nitrogen heterocyclic carbene silver complex added is 5% of the mass of the hexagonal boron nitride nanosheets. Ultrasonic-assisted dispersion and dissolution are performed. After sufficient mixing, the solvent is evaporated at room temperature to prepare a nitrogen heterocyclic carbene silver complex / boron nitride composite nanomaterial NHC-M / BN.

[0036] Example 4

[0037] Preparation of NHC-M / BN composite nanomaterials:

[0038] Hexagonal boron nitride nanosheets are dispersed in methanol, and a nitrogen heterocyclic carbene silver complex is added in an amount of 8% of the mass of the hexagonal boron nitride nanosheets. Ultrasonic-assisted dispersion and dissolution are performed. After thorough mixing, the solvent is evaporated at room temperature to prepare a nitrogen heterocyclic carbene silver complex / boron nitride composite nanomaterial NHC-M / BN.

[0039] Example 5

[0040] Preparation of NHC-M / BN composite nanomaterials:

[0041] Hexagonal boron nitride nanosheets are dispersed in methanol, and a nitrogen heterocyclic carbene silver complex is added. The amount of the nitrogen heterocyclic carbene silver complex added is 3% of the mass of the hexagonal boron nitride nanosheets. Ultrasonic-assisted dispersion and dissolution are performed. After sufficient mixing, the solvent is evaporated at room temperature to prepare a nitrogen heterocyclic carbene silver complex / boron nitride composite nanomaterial NHC-M / BN.

[0042] Example 6

[0043] Electronic Coolant

[0044] The mixture is prepared by uniformly mixing 85 parts of perfluoropolyether, 2 parts of NHC-M / BN prepared in Example 3, 3 parts of methyl ethyl ether, 4 parts of phosphate flame retardant, 0.1 parts of butylated hydroxytoluene and 0.05 parts of fluorocarbon surfactant.

[0045] Example 7

[0046] Electronics Coolant

[0047] The obtained mixture is prepared by uniformly mixing 90 parts of perfluoropolyether, 5 parts of NHC-M / BN prepared in Example 4, 5 parts of methyl ethyl ether, 6 parts of phosphate flame retardant, 0.15 parts of butylated hydroxytoluene and 0.1 parts of fluorocarbon surfactant.

[0048] Example 8

[0049] Electronic Coolant

[0050] The obtained product was prepared by uniformly mixing 88 parts of perfluoropolyether, 4 parts of NHC-M / BN prepared in Example 5, 4 parts of methyl ethyl ether, 5 parts of phosphate flame retardant, 0.12 parts of butylated hydroxytoluene and 0.08 parts of fluorocarbon surfactant.

[0051] The performance of the coolant of the present invention and similar products at home and abroad were tested, and the test results are shown in the following table:

[0052] Table 1 Comparative study on the performance of the coolant of the present invention and similar products at home and abroad

[0053] Technical indicators Products of a domestic company Products of an American company Example 6 Example 7 Example 8 Appearance / smell Transparent and odorless Transparent and odorless Transparent and odorless Transparent and odorless Transparent and odorless Resistivity (Ω·cm) <![CDATA[1.0×10 14 ]]> <![CDATA[4.0×10 15 ]]> <![CDATA[2.0×10 15 ]]> <![CDATA[2.1×10 15 ]]> <![CDATA[1.95×10 15 ]]> <![CDATA[Density (kg / m 3 )]]> 1737.5 1855 879 895 889 Surface tension (mN / m) 14.2 16 36 32 33 Boiling point (℃) 107.2 165 252 254 251 Thermal conductivity (W / (m·K)) 0.0695 0.065 0.131 0.128 0.130 Material compatibility guaranteed YES YES YES YES YES

[0054] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and spirit of the invention, and the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a nitrogen heterocyclic carbene metal complex, characterized in that: 1,3-dimethylimidazolium iodide, silver oxide, and silver carbonate are weighed and dissolved in acetonitrile, and the mixture is refluxed and heated for reaction. After the reaction is completed, the mixture is filtered to remove the solid. The solution is divided into small bottles, which are sealed and pierced. The bottles are then placed in a container filled with acetone, sealed, and allowed to stand for vapor diffusion of the acetonitrile and acetone. After 3-5 days, nitrogen heterocyclic carbene silver complex crystals are obtained, which are then dried to obtain a product.

2. The method for preparing the nitrogen heterocyclic carbene metal complex according to claim 1, wherein: The molar ratio of the 1,3-dimethylimidazolium iodide, silver oxide and silver carbonate is 1-5:1:

1.

3. The method for preparing the nitrogen heterocyclic carbene metal complex according to claim 2, wherein: The reaction temperature is 50-60°C.

4. The method for preparing the nitrogen heterocyclic carbene metal complex according to any one of claims 1 to 3, wherein: Reaction time 20-30h.

5. The method for preparing the nitrogen heterocyclic carbene metal complex according to claim 4, wherein: The drying is carried out by vacuum drying at a drying temperature of 40-50°C.

6. A nitrogen heterocyclic carbene metal complex prepared by the method for preparing a nitrogen heterocyclic carbene metal complex according to any one of claims 1 to 5.

7. A method for preparing NHC-M / BN, characterized in that: The hexagonal boron nitride nanosheets are dispersed in methanol, the nitrogen heterocyclic carbene silver complex according to claim 6 is added, and ultrasonic-assisted dispersion and dissolution are performed. After sufficient mixing, the solvent is evaporated at room temperature to prepare the nitrogen heterocyclic carbene silver complex / boron nitride composite nanomaterial NHC-M / BN.

8. The method for preparing NHC-M / BN according to claim 7, characterized in that: The added amount of the nitrogen heterocyclic carbene silver complex is 3%-8% of the mass of the hexagonal boron nitride nanosheets.

9. A coolant, characterized in that: The invention is prepared from the following raw materials in parts by weight: 85-90 parts of perfluoropolyether, 2-5 parts of NHC-M / BN, 3-5 parts of methyl ethyl ether, 4-6 parts of phosphate flame retardant, 0.1-0.15 parts of butylated hydroxytoluene, and 0.05-0.1 parts of fluorocarbon surfactant.

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