Polyfluoropolyether cooling working medium with three-dimensional structure and preparation method thereof

Abstract

The invention provides a polyfluoropolyether cooling working medium with a three-dimensional structure and a preparation method thereof, and the method comprises the following steps: determining a central compound corresponding to the three-dimensional structure, and determining a branched chain compound, a solvent and an organic alkali according to the central compound; wherein when the central compound is polyisocyanate, the branched chain compound is hydroxyl-terminated polyfluoropolyether; when the central compound is polyhydric alcohol, the branched chain compound is terminal acyl halide-polyfluoropolyether; and dissolving the raw material of the central compound and the raw material of the branched chain compound to prepare a to-be-treated solution, and treating the to-be-treated solution under preset conditions to obtain the polyfluoropolyether cooling working medium. According to the polyfluoropolyether structure generated through the synthesis scheme provided by the invention, stacking among polyfluoropolyether molecules can be effectively avoided through repulsion on the three-dimensional scale, so that the density of the cooling liquid is reduced, and flowing of the cooling liquid and conduction of heat are facilitated.

Description

Technical Field

[0001] The present application relates to the field of chemical technology, and in particular to a polyfluoropolyether cooling medium with a three-dimensional structure and a preparation method thereof. Background Art

[0002] Electronic components generate a lot of heat during operation. If the heat cannot be dissipated in time, it will directly affect their performance and lifespan. Traditional coolants are hydrocarbons or silane compounds, which are widely used because of their low price. However, the thermal instability of hydrocarbons limits their application to mid- and low-end scenarios. With the rise of cloud computing and big data, conventional hydrocarbon coolants can no longer meet the high heat dissipation, thermal stability, and safety requirements of data center operations.

[0003] The CH in perfluoropolyether is replaced by CF, making it non-flammable, with a high safety factor, and high thermal conductivity and dielectric properties, playing an irreplaceable role in extreme environments. At present, the chemical structure of perfluoropolyether coolants is mostly chain-like linear polymers. In addition, the strong interaction between the positive and negative dipoles of C and O makes the molecular chains stacked tightly, resulting in a high density of perfluoropolyether, which aggravates the difficulty of the coolant circulation process and causes problems in load-bearing. Summary of the invention

[0004] In view of the above problems, the present application is proposed to provide a polyfluoropolyether cooling medium with a three-dimensional structure and a preparation method thereof, which overcomes the above problems or at least partially solves the above problems, including:

[0005] A method for preparing a polyfluoropolyether cooling medium having a three-dimensional structure, comprising the steps of:

[0006] Determine a central compound corresponding to the three-dimensional structure, and determine a branched compound, a solvent and an organic base according to the central compound; wherein the central compound is a polyisocyanate or a polyol; when the central compound is a polyisocyanate, the branched compound is a terminal hydroxyl-polyfluoropolyether; when the central compound is a polyol, the branched compound is a terminal acyl halide-polyfluoropolyether;

[0007] Dissolving and mixing the raw material of the central compound and the raw material of the branched compound to prepare a solution to be treated;

[0008] The liquid to be treated is treated under preset conditions to obtain a polyfluoropolyether cooling medium; wherein the structural formula of the polyfluoropolyether cooling medium is:

[0009]

[0010] In the structural formula, R 1It is a polyfluoropolyether molecular chain fragment with a chain length of 5 to 20 atoms including carbon and oxygen. 2 The polyfluoropolyether molecular chain fragment or hydrogen atom is a terminal acyl group, and the chain length is 5 to 20 atoms including carbon and oxygen. 3 It is an aromatic ring fragment or an alkyl chain.

[0011] Further, when the central compound is a polyisocyanate, the raw material of the central compound is a triisocyanate or a tetraisocyanate, including one of triphenylmethane triisocyanate, tris(p-isocyanate)aniline, isotriisocyanatebenzene, 1,3,5-triisocyanatecyclohexane or dimethyltritylmethane tetraisocyanate;

[0012] The raw materials of the branched compound include: one or more of hexafluoropropylene oxide, 2,3-epoxyoctafluorobutane, octafluoroepoxyisobutane, 2,3-epoxy-3-trifluoromethylperfluorobutane, and the raw materials of the branched compound are stable end-hydroxyl terminated polymers.

[0013] Further, when the central compound is a polyol, the raw materials of the central compound include polyhydroxy aldehydes, polyhydroxy ketone compounds and their cyclic structures;

[0014] The raw material of the branched compound is one or more of hexafluoropropylene oxide, 2,3-epoxyoctafluorobutane, octafluoroepoxyisobutane, and 2,3-epoxy-3-trifluoromethylperfluorobutane, and the raw material of the branched compound is a terminal acyl halide polymer.

[0015] Furthermore, in the step of dissolving the raw materials of the central compound and the raw materials of the branched compounds to prepare the solution to be treated, the solvent is one or more of ethyl acetate, tetrahydrofuran, acetonitrile, dichloromethane, chloroform, chlorobenzene, dichlorobenzene, trifluorotoluene, methyl nonafluorobutyl ether, ethyl nonafluorobutyl ether and ethyl nonafluoroisobutyl ether.

[0016] Furthermore, the step of treating the mixed liquid under the preset conditions to obtain a polyfluoropolyether cooling medium comprises:

[0017] When the central compound is polyisocyanate, 0.01 to 0.5 equivalents of a catalyst are added to the mixed solution; wherein the catalyst is a tertiary amine;

[0018] The mixed solution is heated to 25-90° C. and the polymerization end-capping reaction is carried out for 2-72 hours.

[0019] Furthermore, the step of treating the mixed liquid under the preset conditions to obtain a polyfluoropolyether cooling medium comprises:

[0020] When the central compound is a polyol, 0.01 to 0.5 equivalents of a catalyst are added to the mixed solution; wherein the catalyst is triethylamine;

[0021] The temperature of the mixed solution is maintained at 0-25°C and the reaction is carried out for 2-24 hours.

[0022] Furthermore, the molar ratio of the polyisocyanate to the terminal hydroxyl-polyfluoropolyether is 1:3-4.

[0023] Furthermore, the molar ratio of the polyol to the terminal acyl halide-polyfluoropolyether is 1:4 to 6.1.

[0024] Furthermore, the structural formula of the polyisocyanate is:

[0025]

[0026] The structural formula of the terminal hydroxyl-polyfluoropolyether is:

[0027]

[0028] The structural formula of the polyol is:

[0029]

[0030] The structural formula of the terminal acyl halide-polyfluoropolyether is:

[0031]

[0032] Among them, R 1 It is a polyfluoropolyether molecular chain fragment, and the chain length is 5 to 20 atoms including carbon and oxygen;

[0033] R 2 It is a polyfluoropolyether molecular chain fragment or a hydrogen atom of a terminal acyl group, and the chain length is 5 to 20 atoms including carbon and oxygen;

[0034] R 3 is an aromatic ring fragment or an alkyl chain;

[0035] R 4 C 1 ~C 10 Polyfluorinated linear alkanes or C 1 ~C 10 Polyfluorinated branched alkanes;

[0036] R 5 , R 6 is a polyfluoropolyether molecular chain fragment, a hydrogen atom, a fluorine atom, a trifluoromethyl group or a difluoromethyl group;

[0037] R 7 , R 8It is a polyfluoropolyether molecular chain fragment, a hydrogen atom, a trifluoromethyl group or a difluoromethyl group;

[0038] X is F, Cl or Br.

[0039] A polyfluoropolyether cooling medium with a three-dimensional structure, characterized in that the polyfluoropolyether cooling medium is prepared by any of the preparation methods described above, and the structure of the polyfluoropolyether cooling medium is:

[0040]

[0041] This application has the following advantages:

[0042] In the embodiments of the present application, in view of the shortcomings of the prior art that perfluoropolyether cooling products are all chain structures in chemical structure and the molecular chains are stacked together to cause high density, the present application provides a polyfluoropolyether cooling fluid with a three-dimensional structure and a preparation method thereof, the method comprising the steps of: determining a central compound corresponding to the three-dimensional structure, and determining a branched compound, a solvent and an organic base based on the central compound; wherein the central compound is a polyisocyanate or a polyol; when the central compound is a polyisocyanate, the branched compound is a terminal hydroxyl-polyfluoropolyether; when the central compound is a polyol, the branched compound is a terminal acyl halide-polyfluoropolyether; dissolving the raw materials of the central compound and the raw materials of the branched compounds to prepare a solution to be treated; treating the solution to be treated under preset conditions to obtain a polyfluoropolyether cooling fluid. The polyfluoropolyether structure generated by the synthesis scheme proposed in the present application can effectively avoid the stacking of polyfluoropolyether molecules through repulsion on a three-dimensional scale, thereby reducing the density of the coolant. The polyfluoropolyether in this structure is loosely stacked and has a lower density, which is conducive to the flow of the coolant and the conduction of heat. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solution of the present application, the drawings required for use in the description of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0044] Figure 1 It is a flow chart of the steps of a method for preparing a polyfluoropolyether cooling medium with a three-dimensional structure provided in one embodiment of the present application. DETAILED DESCRIPTION

[0045] In order to make the objects, features and advantages of the present application more obvious and understandable, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0046] The inventors have found through analyzing the prior art that in the prior art, conventional chain perfluoropolyether or polyfluoropolyether has only one-dimensional size, a relatively regular chemical structure, and close stacking of molecules, which makes the liquid perfluoropolyether have a very high density. This means that when preparing the coolant, the quality of the coolant is high after adding perfluoropolyether or polyfluoropolyether, and it cannot be used in lightweight and precision application environments.

[0047] Reference Figure 1 , showing a flow chart of the steps of a method for preparing a polyfluoropolyether cooling medium with a three-dimensional structure provided in one embodiment of the present application:

[0048] The method comprises:

[0049] S110, determining a central compound corresponding to the three-dimensional structure, and determining a branched compound, a solvent and an organic base according to the central compound; wherein the central compound is a polyisocyanate or a polyol; when the central compound is a polyisocyanate, the branched compound is a terminal hydroxyl-polyfluoropolyether; when the central compound is a polyol, the branched compound is a terminal acyl halide-polyfluoropolyether;

[0050] S120, dissolving the central compound raw material and the branched compound raw material to prepare a solution to be treated;

[0051] S130, treating the liquid to be treated under preset conditions to obtain a polyfluoropolyether cooling medium; wherein the structural formula of the polyfluoropolyether cooling medium is:

[0052]

[0053] In the structural formula, R 1 It is a polyfluoropolyether molecular chain fragment with a chain length of 5 to 20 atoms including carbon and oxygen. 2 The polyfluoropolyether molecular chain fragment or hydrogen atom is a terminal acyl group, and the chain length is 5 to 20 atoms including carbon and oxygen. 3 It is an aromatic ring fragment or an alkyl chain.

[0054] In the embodiments of the present application, in view of the disadvantage that the chemical structure of perfluoropolyether cooling products in the prior art is a chain structure, and the molecular chains are stacked together to cause a high density, the present application provides a polyfluoropolyether cooling medium with a three-dimensional structure and a preparation method thereof, the method comprising the steps of: determining a central compound corresponding to the three-dimensional structure, and determining a branched compound, a solvent and an organic base according to the central compound; wherein the central compound is a polyisocyanate or a polyol; when the central compound is a polyisocyanate, the branched compound is a terminal hydroxyl-polyfluoropolyether; when the central compound is a polyol, the branched compound is a terminal acyl halide-polyfluoropolyether; dissolving the central compound raw material and the branched compound raw material to prepare a solution to be treated; treating the solution to be treated under preset conditions to obtain a polyfluoropolyether cooling medium. The polyfluoropolyether structure generated by the synthesis scheme proposed in the present application can effectively avoid the stacking of polyfluoropolyether molecules through repulsion on a three-dimensional scale, thereby reducing the density of the coolant. The polyfluoropolyether of this structure is loosely stacked and has a low density, which is conducive to the flow of the coolant and the conduction of heat.

[0055] Next, a method for preparing a polyfluoropolyether cooling medium having a three-dimensional structure in this exemplary embodiment will be further described.

[0056] As described in step S110, the central compound corresponding to the three-dimensional structure is determined, and the side chain compound, solvent and organic base are determined based on the central compound; wherein the central compound is a polyisocyanate or a polyol; when the central compound is a polyisocyanate, the side chain compound is a terminal hydroxyl-polyfluoropolyether; when the central compound is a polyol, the side chain compound is a terminal acyl halide-polyfluoropolyether.

[0057] It should be noted that there are two three-dimensional structures proposed in this application. When the central compound is polyisocyanate, the corresponding three-dimensional product chemical formula is:

[0058]

[0059] When the central compound is a polyol, the corresponding three-dimensional product chemical formula is:

[0060]

[0061] When the central compound is polyisocyanate and the branched compound is terminal hydroxyl-polyfluoropolyether, the product is carbamate-type polyfluoropolyether, and the synthesis route is:

[0062]

[0063] R 1It is a polyfluoropolyether molecular chain fragment, and the chain length is 5 to 20 atoms including carbon and oxygen;

[0064] R 3 is an aromatic ring fragment or an alkyl chain;

[0065] R 4 Selected from C 1 ~C 10 Polyfluorinated linear alkanes or C 1 ~C 10 Polyfluorinated branched alkanes.

[0066] When the central compound is a polyol and the branched compound is a terminal acyl halide-polyfluoropolyether, the product is a carboxylate-type polyfluoropolyether, and the synthesis route is:

[0067]

[0068] R 2 It is a polyfluoropolyether molecular chain fragment or a hydrogen atom of a terminal acyl group, and the chain length is 5 to 20 atoms including carbon and oxygen;

[0069] R 4 Selected from C 1 ~C 10 Polyfluorinated linear alkanes or C 1 ~C 10 Polyfluorinated branched alkanes.

[0070] In one embodiment of the present application, when the central compound is a polyisocyanate, the raw material of the central compound is a triisocyanate or a tetraisocyanate, including one of triphenylmethane triisocyanate, tris(p-isocyanate)aniline, isotriisocyanatebenzene, 1,3,5-triisocyanatecyclohexane or dimethyltritylmethane tetraisocyanate;

[0071] The raw materials of the branched compound include: one or more of hexafluoropropylene oxide, 2,3-epoxyoctafluorobutane, octafluoroepoxyisobutane, and 2,3-epoxy-3-trifluoromethylperfluorobutane.

[0072] In one embodiment of the present application, when the central compound is a polyol, the raw materials of the central compound include polyhydroxy aldehydes, polyhydroxy ketone compounds and their cyclic structures;

[0073] The raw materials of the branched compound are one or more of hexafluoropropylene oxide, 2,3-epoxyoctafluorobutane, octafluoroepoxyisobutane, and 2,3-epoxy-3-trifluoromethylperfluorobutane.

[0074] As described in step S120, the central compound raw material and the branched compound raw material are prepared into a solution for dissolution and mixing to obtain a mixed solution.

[0075] In one embodiment of the present application, the solvent is one or more of ethyl acetate, tetrahydrofuran, acetonitrile, dichloromethane, chloroform, chlorobenzene, dichlorobenzene, trifluorotoluene, methyl nonafluorobutyl ether, ethyl nonafluorobutyl ether and ethyl nonafluoroisobutyl ether.

[0076] It should be noted that when the central compound is a polyisocyanate and the generated product is a carbamate-type polyfluoropolyether, the solvent is one or a mixture of several of ethyl acetate, tetrahydrofuran, acetonitrile, dichloromethane (DCM), chloroform, chlorobenzene, dichlorobenzene, trifluorotoluene, methyl nonafluorobutyl ether, ethyl nonafluorobutyl ether, and ethyl nonafluoroisobutyl ether.

[0077] When the central compound is a polyol and the product is a carboxylate-type polyfluoropolyether, the solvent used is generally dichloromethane. The raw materials are dissolved in dichloromethane, and the raw materials are mixed by dropwise addition, and the reaction temperature of the raw materials is controlled to ensure that the product content is within a preset range.

[0078] As described in step S130, the solution is treated under preset conditions to obtain a polyfluoropolyether cooling medium.

[0079] In one embodiment of the present application, when the central compound is a polyisocyanate, 0.01-0.5 equivalents of a catalyst are added to the mixed solution; wherein the catalyst is a tertiary amine; the tertiary amine includes one or more of N,N-dimethylcyclohexylamine, bis(2-dimethylaminoethyl) ether, N,N,N',N'-tetramethylalkylenediamine, triethylamine, N,N-dimethylbenzylamine, N-ethylmorpholine, N-methylmorpholine, N,N'-diethylpiperazine, pyridine, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), N,N'-dimethylpyridine, etc.

[0080] The mixed solution is heated to 25-90° C. and the polymerization end-capping reaction is carried out for 2-72 hours.

[0081] It should be noted that when the central compound is polyisocyanate and the branched compound is terminal hydroxyl-polyfluoropolyether, the generated product is carbamate-type polyfluoropolyether, which requires a higher temperature and a longer reaction time.

[0082] In one embodiment of the present application, the molar ratio of the polyisocyanate to the terminal hydroxyl-polyfluoropolyether is 1:3-4.

[0083] In one embodiment of the present application, when the central compound is a polyol, 0.01 to 0.5 equivalents of a catalyst are added to the mixed solution; wherein the catalyst is triethylamine;

[0084] The temperature of the mixed solution is maintained at 0-25°C and the reaction is carried out for 2-24 hours.

[0085] It should be noted that when the central compound is a polyol and the side-chain compound is a terminal acyl halide-polyfluoropolyether, the generated product is a carboxylate-type polyfluoropolyether. The reaction temperature cannot be too high and needs to be maintained at a low temperature to ensure smooth reaction.

[0086] In one embodiment of the present application, the molar ratio of the polyol to the terminal acyl halide-polyfluoropolyether is 1:4-6.1.

[0087] In one embodiment of the present application, the structural formula of the polyisocyanate is:

[0088]

[0089] The structural formula of the terminal hydroxyl-polyfluoropolyether is:

[0090]

[0091] The structural formula of the polyol is:

[0092]

[0093] The structural formula of the terminal acyl halide-polyfluoropolyether is:

[0094]

[0095] Among them, R 1 It is a polyfluoropolyether molecular chain fragment, and the chain length is 5 to 20 atoms including carbon and oxygen;

[0096] R 2 It is a polyfluoropolyether molecular chain fragment or a hydrogen atom of a terminal acyl group, and the chain length is 5 to 20 atoms including carbon and oxygen;

[0097] R 3 is an aromatic ring fragment or an alkyl chain;

[0098] R 4 C 1 ~C 10 Polyfluorinated linear alkanes or C 1 ~C 10 Polyfluorinated branched alkanes;

[0099] R 5 , R 6 is a polyfluoropolyether molecular chain fragment, a hydrogen atom, a fluorine atom, a trifluoromethyl group or a difluoromethyl group;

[0100] R 7 , R 8 It is a polyfluoropolyether molecular chain fragment, a hydrogen atom, a trifluoromethyl group or a difluoromethyl group;

[0101] X is F, Cl or Br.

[0102] In a specific implementation, the carbamate type polyfluoropolyether is prepared by the method proposed in the present application, and the reaction route is:

[0103]

[0104] Among them, R 9 is the alkyl fragment of the following chemical structure or alcohol:

[0105]

[0106] Preparation method: In a 50mL flask, add dimethyl trityl methane tetraisocyanate (0.436g, 1mmol, 1.0equiv), terminal hydroxy-epoxy perfluoropropane tetramer (3.257g, 4mmol, 4.0equiv), 1,8-diazabicyclo [5.4.0] undec-7-ene (DBU) (0.075g, 0.05mmol, 0.05equiv), 10mL of dichloromethane, under inert gas protection, heat to 40°C, and maintain the temperature for 10h. After the reaction is completed, cool to room temperature and add ethanol to quench. The reaction product is washed with water, dried and concentrated to obtain a carbamate type polyfluoropolyether.

[0107] In a specific implementation, the carboxylate type polyfluoropolyether is prepared by the method proposed in the present application, and the reaction route is:

[0108]

[0109] Among them, R 10 is the following chemical structure or hydrogen atom:

[0110]

[0111] Preparation method: Dissolve terminal acyl fluoride-epoxy perfluoropropane pentamer (4.234 g, 5.1 mmol, 5.1 equiv) in 10 mL of dichloromethane, keep warm at 0 ° C for 20 to 30 min, dissolve triethylamine (0.516 g, 5.1 mmol, 5.1 equiv) and glucose (0.180 g, 1 mmol, 1.0 equiv) in 5 mL of dichloromethane, and slowly add dropwise to the dichloromethane solution of terminal acyl fluoride-epoxy perfluoropropane pentamer. After the addition is complete, continue to react at 0 ° C for 10 min, transfer to room temperature for more than 12 hours. After the reaction is completed, cool it back to 0 ° C, add NaHCO 3 The aqueous solution is quenched. The liquids are separated, the aqueous phase is discarded, the organic phase is taken and washed with distilled water for 3 times, and then with ultrapure water for 3 times, and the dichloromethane is removed under reduced pressure to obtain a carboxylate type polyfluoropolyether compound.

[0112] The molecular weight distribution, boiling point, thermal stability, density, thermal conductivity, dielectric constant and aging performance of the polyfluoropolyether prepared in the present application are tested. The three-dimensional structured polyfluoropolyether electronic coolant prepared in the present application has low density, colorless transparency, high dielectric constant, ideal chemical inertness, good thermal conductivity and system matching compatibility, and can be used for the preparation of electronic coolant. The electronic coolant can be used in various temperature control and heat dissipation occasions. The low density reduces the load and makes the application scenarios wider. The single-phase cooling has a lower vapor pressure, which can reduce the sealing requirements of the equipment and the subsequent maintenance loss and reduce the cost.

[0113] Although the preferred embodiments of the present application have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the embodiments of the present application.

[0114] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or terminal device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or terminal device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or terminal device including the elements.

[0115] The above is a detailed introduction to a polyfluoropolyether cooling fluid with a three-dimensional structure and a preparation method thereof provided by the present application. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea. At the same time, for a person skilled in the art, according to the idea of ​​the present application, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A method for preparing a polyfluoropolyether cooling medium having a three-dimensional structure, characterized in that: Includes steps: Determine the central compound corresponding to the three-dimensional structure, and determine the branched compound, solvent and organic base according to the central compound; wherein the central compound is a polyisocyanate or a polyol; when the central compound is a polyisocyanate, the branched compound is a terminal hydroxyl-polyfluoropolyether; when the central compound is a polyol, the branched compound is a terminal acyl halide-polyfluoropolyether; Dissolving the raw materials of the central compound and the raw materials of the branched compounds to prepare a solution to be treated; The liquid to be treated is treated under preset conditions to obtain a polyfluoropolyether cooling medium; wherein the structural formula of the polyfluoropolyether cooling medium is: In the structural formula, R1 is a polyfluoropolyether molecular chain fragment with a chain length of 5 to 20 atoms including carbon and oxygen, R2 is a polyfluoropolyether molecular chain fragment or a hydrogen atom with a terminal acyl group with a chain length of 5 to 20 atoms including carbon and oxygen, and R3 is an aromatic ring fragment or an alkyl chain.

2. The preparation method according to claim 1, characterized in that: When the central compound is a polyisocyanate, the raw material of the central compound is a triisocyanate or a tetraisocyanate, including one of triphenylmethane triisocyanate, tris(p-isocyanate)aniline, isotriisocyanatebenzene, 1,3,5-triisocyanatecyclohexane or dimethyltritylmethane tetraisocyanate; The raw materials of the branched compound include: one or more of hexafluoropropylene oxide, 2,3-epoxyoctafluorobutane, octafluoroepoxyisobutane, 2,3-epoxy-3-trifluoromethylperfluorobutane, and the raw materials of the branched compound are stable terminal hydroxyl-terminated polymers.

3. The preparation method according to claim 1, characterized in that: When the central compound is a polyol, the central compound raw material solvent includes polyhydroxy aldehydes, polyhydroxy ketone compounds and their cyclic structures; The raw material of the branched compound is one or more of hexafluoropropylene oxide, 2,3-epoxyoctafluorobutane, octafluoroepoxyisobutane, and 2,3-epoxy-3-trifluoromethylperfluorobutane, and the raw material of the branched compound is a terminal acyl halide polymer.

4. The preparation method according to claim 1, characterized in that: In the step of dissolving the raw materials of the central compound and the raw materials of the branched compounds to prepare the solution to be treated, the solvent is one or more of ethyl acetate, tetrahydrofuran, acetonitrile, dichloromethane, chloroform, chlorobenzene, dichlorobenzene, trifluorotoluene, methyl nonafluorobutyl ether, ethyl nonafluorobutyl ether and ethyl nonafluoroisobutyl ether.

5. The preparation method according to claim 1, characterized in that: The step of treating the mixed liquid under the preset conditions to obtain a polyfluoropolyether cooling medium comprises: When the central compound is polyisocyanate, 0.01 to 0.5 equivalents of a catalyst are added to the mixed solution; wherein the catalyst is a tertiary amine; The mixed solution is heated to 25-90° C. and the polymerization end-capping reaction is carried out for 2-72 hours.

6. The preparation method according to claim 1, characterized in that: The step of treating the mixed liquid under the preset conditions to obtain a polyfluoropolyether cooling medium comprises: When the central compound is a polyol, 0.01 to 0.5 equivalents of a catalyst are added to the mixed solution; wherein the catalyst is triethylamine; The temperature of the mixed solution is maintained at 0-25°C and the reaction is carried out for 2-24 hours.

7. The preparation method according to claim 1, characterized in that: The molar ratio of the polyisocyanate to the terminal hydroxyl-polyfluoropolyether is 1:3-4.

8. The preparation method according to claim 1, characterized in that: The molar ratio of the polyol to the terminal acyl halide-polyfluoropolyether is 1:4 to 6.

1.

9. The preparation method according to claim 1, characterized in that: The structural formula of the polyisocyanate is: The structural formula of the terminal hydroxyl-polyfluoropolyether is: The structural formula of the polyol is: The structural formula of the terminal acyl halide-polyfluoropolyether is: Wherein, R1 is a polyfluoropolyether molecular chain fragment, and the chain length is 5 to 20 atoms including carbon and oxygen; R2 is a polyfluoropolyether molecular chain fragment or a hydrogen atom with a terminal acyl group, and the chain length is 5 to 20 atoms including carbon and oxygen; R3 is an aromatic ring fragment or an alkyl chain; R4 is C1~C 10 Polyfluorinated straight chain alkanes or C1~C 10 Polyfluorinated branched alkanes; R5 and R6 are polyfluoropolyether molecular chain fragments, hydrogen atoms, fluorine atoms, trifluoromethyl groups or difluoromethyl groups; R7 and R8 are polyfluoropolyether molecular chain fragments, hydrogen atoms, trifluoromethyl groups or difluoromethyl groups; X is F, Cl or Br.

10. A polyfluoropolyether cooling medium having a three-dimensional structure, characterized in that: The polyfluoropolyether cooling medium is prepared by the preparation method according to any one of claims 1 to 9, and the structure of the polyfluoropolyether cooling medium is:

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