Thermal temperature response microsphere and preparation method thereof
By covering boron nitride with the polymer shell of the microspheres at thermal temperature, a three-dimensional thermal conductivity network is constructed, which solves the problem of low thermal conductivity of existing organic polymer materials and achieves more efficient thermal dissipation and expansion performance.
Patent Information
- Application Number
- CN202411784334.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-06
- Publication Date
- 2025-02-28
AI Technical Summary
The thermal conductivity of existing organic polymer materials is low and it is difficult to meet the growing heat dissipation needs of electronic components.
By covering boron nitride at the polymer shell of the microspheres at thermal temperature, a three-dimensional thermal conductivity network of boron nitride is constructed, and the use of vinyl functionalized boron nitride with an emulsifier can enhance the thermal conductivity and expansion properties of the microspheres.
It significantly improves the thermal conductivity of the thermal temperature-responsive microspheres, maintains good expansion performance, and can more effectively meet the heat dissipation needs of electronic components.
Smart Images
Figure CN119529203A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of expandable microspheres, and in particular relates to thermal temperature responsive microspheres and a preparation method thereof. Background Art
[0002] With the rapid advancement of microelectronics integration and assembly technologies, electronic components and logic circuits are becoming increasingly smaller, while operating frequencies are increasing dramatically. This has led to a shift in the ambient temperature of semiconductors towards higher temperatures. To ensure the long-term, reliable operation of electronic components, timely heat dissipation has become a limiting factor in their service life. Highly thermally conductive polymer-based composite materials play a vital role in numerous manufacturing and high-tech fields, including microelectronics, aviation, aerospace, military equipment, and electrical machinery and appliances. Consequently, the development of highly thermally conductive polymer-based composite materials with superior overall performance has become a research hotspot. However, organic polymer materials typically have low intrinsic thermal conductivity, making them difficult to meet the growing heat dissipation requirements of electronic components. Summary of the Invention
[0003] In view of the above problems existing in the prior art, the present invention provides a thermal temperature responsive microsphere and a preparation method thereof, which can obtain microspheres with excellent thermal conductivity and expansion performance.
[0004] To achieve the above-mentioned purpose, the technical solution provided by the present invention is as follows:
[0005] In a first aspect, the present application provides a method for preparing thermal temperature-responsive microspheres, comprising the following steps:
[0006] S1: mixing an ethylenically unsaturated monomer, a blowing agent, and an initiator to obtain an oil phase;
[0007] S2: mixing vinyl-functionalized boron nitride, an emulsifier, and deionized water to obtain an aqueous phase;
[0008] S3: Under stirring, the oil phase and the water phase are mixed to obtain a mixed liquid; under a nitrogen atmosphere, the mixed liquid is reacted at 60-85° C., washed and dried to obtain the thermoresponsive microspheres; the ethylenically unsaturated monomers include one or more of nitriles, acrylates and acrylic acid.
[0009] Optionally, the preparation of the vinyl-functionalized boron nitride comprises the following steps: adding boron nitride (3-50 µm), a vinyl-containing silane coupling agent, and tetraethyl orthosilicate to ethanol, adjusting the pH to between 3-11, reacting for 1-12 hours, and drying to obtain vinyl-functionalized boron nitride.
[0010] Optionally, the amount ratio of the boron nitride, the vinyl-containing silane coupling agent and tetraethyl orthosilane is 10: (0.1-0.5): (0.5-2) g / mL / mL.
[0011] Optionally, the silane coupling agent with a vinyl group includes one or more of vinyl trichlorosilane, vinyl triethoxysilane, vinyl trimethoxysilane, γ-methacryloxypropyl trimethoxysilane and vinyl methyl dimethoxysilane.
[0012] Optionally, the emulsifier is sodium lauryl sulfate.
[0013] Optionally, the emulsifier accounts for 1.5-3% of the mass of the aqueous phase, and the vinyl-functionalized boron nitride accounts for 1-5% of the mass of the aqueous phase.
[0014] Optionally, the foaming agent is n-octane, n-nonane or n-decane, the mass ratio of the foaming agent to the ethylenically unsaturated monomer is (0.7-1.1):1, and the initiator is azobisisobutyronitrile.
[0015] Optionally, the ethylenically unsaturated monomer includes the following components in parts by mass: 3-6 parts of acrylonitrile, 6-8 parts of methyl methacrylate, 4-6 parts of methyl acrylate, and 2-5 parts of methacrylic acid.
[0016] On the other hand, the present application also provides thermal temperature responsive microspheres prepared by the above method, comprising a shell formed by polymerization of ethylenically unsaturated monomers, a foaming agent encapsulated in the shell, and boron nitride wrapped outside the shell.
[0017] Compared with the prior art, this application has at least the following beneficial effects:
[0018] The present invention coats boron nitride within its polymer shell, creating a three-dimensional thermally conductive network of boron nitride when the thermoresponsive microspheres come into contact with each other. This effectively improves the thermal conductivity of the thermoresponsive microspheres, and the resulting thermoresponsive microspheres also exhibit excellent expansion properties. This application utilizes double-bond-modified boron nitride to participate in monomer polymerization, forming a covalent bond between the boron nitride and the polymer shell. By combining this with an emulsifier, the boron nitride and polymer bond are further enhanced, and the microspheres are more evenly loaded with boron nitride, resulting in superior thermal conductivity. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 This is a SEM image of the thermal temperature-responsive microspheres in Example 1 (magnification 5500 times);
[0020] Figure 2 SEM images of the thermal temperature-responsive microspheres in Example 5 (magnifications are 1550 and 5500 times);
[0021] Figure 3 TG and DTG curves of the thermoresponsive microspheres prepared in Examples 1, 6, and 7 (B-1 is Example 7, B-2 is Example 6, and B-3 is Example 1);
[0022] Figure 4 The volume changes of the thermoresponsive microspheres prepared in Example 1, Example 2 and Example 3 with equal mass at different temperatures for 2 hours (serial numbers 1, 2 and 3 correspond to Example 1, Example 2 and Example 3, respectively). DETAILED DESCRIPTION
[0023] The present invention is described in further detail below with reference to the accompanying drawings:
[0024] Unless otherwise specified, the experimental methods used in the embodiments of the present invention are conventional methods.
[0025] The reagents and materials used in this example can be purchased conventionally. The quantitative experiments involved in the examples were repeated at least three times, and the results were averaged.
[0026] Example 1
[0027] A method for preparing thermal temperature-responsive microspheres, comprising the following steps:
[0028] Weigh 5 g of acrylonitrile, 7 g of methyl methacrylate, 5 g of methyl acrylate, 3 g of methacrylic acid, 20 g of n-octane, and 0.5 g of azobisisobutyronitrile and mix them evenly as the oil phase;
[0029] Add 10 g of boron nitride, 0.4 mL of a vinyl-containing silane coupling agent (vinyltrichlorosilane), and 1 mL of tetraethyl orthosilicate to 100 mL of ethanol, adjust the pH to 6, react for 3 hours, and dry to obtain vinyl-functionalized boron nitride.
[0030] 2 g of vinyl-functionalized boron nitride and 2 g of sodium dodecyl sulfate were weighed and dissolved in 90 mL of deionized water and mixed evenly as the aqueous phase; after stirring with a high-speed stirrer at 6000 rpm for 10 minutes to mix the oil phase and the aqueous phase, the mixture was transferred to a three-necked flask, continuously stirred at 300 rpm under a nitrogen atmosphere, and reacted at 65°C for 16 hours to obtain thermoresponsive microspheres.
[0031] Example 2
[0032] A method for preparing thermal temperature-responsive microspheres, comprising the following steps:
[0033] Weigh 5 g of acrylonitrile, 7 g of methyl methacrylate, 5 g of methyl acrylate, 3 g of methacrylic acid, 20 g of n-nonane, and 0.5 g of azobisisobutyronitrile and mix them evenly as the oil phase;
[0034] Add 10 g of boron nitride, 0.4 mL of a vinyl-containing silane coupling agent (vinyltrichlorosilane), and 1 mL of tetraethyl orthosilicate to 100 mL of ethanol, adjust the pH to 6, react for 3 hours, and dry to obtain vinyl-functionalized boron nitride.
[0035] 2 g of vinyl-functionalized boron nitride and 2 g of sodium dodecyl sulfate were weighed and dissolved in 90 mL of deionized water and mixed evenly as the aqueous phase; after stirring with a high-speed stirrer at 6000 rpm for 10 minutes to mix the oil phase and the aqueous phase, the mixture was transferred to a three-necked flask, continuously stirred at 300 rpm under a nitrogen atmosphere, and reacted at 65°C for 16 hours to obtain thermoresponsive microspheres.
[0036] Example 3
[0037] A method for preparing thermal temperature-responsive microspheres, comprising the following steps:
[0038] Weigh 5 g of acrylonitrile, 7 g of methyl methacrylate, 5 g of methyl acrylate, 3 g of methacrylic acid, 20 g of n-decane, and 0.5 g of azobisisobutyronitrile and mix them evenly as the oil phase;
[0039] Add 10 g of boron nitride, 0.4 mL of a vinyl-containing silane coupling agent (vinyltrichlorosilane), and 1 mL of tetraethyl orthosilicate to 100 mL of ethanol, adjust the pH to 6, react for 3 hours, and dry to obtain vinyl-functionalized boron nitride.
[0040] 2 g of vinyl-functionalized boron nitride and 2 g of sodium dodecyl sulfate were weighed and dissolved in 90 mL of deionized water and mixed evenly as the aqueous phase; after stirring with a high-speed stirrer at 6000 rpm for 10 minutes to mix the oil phase and the aqueous phase, the mixture was transferred to a three-necked flask, continuously stirred at 300 rpm under a nitrogen atmosphere, and reacted at 65°C for 16 hours to obtain thermoresponsive microspheres.
[0041] Example 4
[0042] A method for preparing thermal temperature-responsive microspheres, comprising the following steps:
[0043] Weigh 3 g of acrylonitrile, 8 g of methyl methacrylate, 4 g of methyl acrylate, 5 g of methacrylic acid, 20 g of n-octane, and 0.5 g of azobisisobutyronitrile and mix them evenly as the oil phase;
[0044] Add 10 g of boron nitride, 0.2 mL of a vinyl-containing silane coupling agent (vinyltrimethoxysilane), and 1.5 mL of tetraethyl orthosilicate to 100 mL of ethanol, adjust the pH to 7.5, react for 3 hours, and dry to obtain vinyl-functionalized boron nitride.
[0045] 3 g of vinyl-functionalized boron nitride and 2.4 g of sodium dodecyl sulfate were weighed and dissolved in 90 mL of deionized water and mixed evenly as the aqueous phase; after stirring with a high-speed stirrer at 6000 rpm for 10 minutes to mix the oil phase and the aqueous phase, the mixture was transferred to a three-necked flask, continuously stirred at 300 rpm under a nitrogen atmosphere, and reacted at 75°C for 14 hours to obtain thermoresponsive microspheres.
[0046] Example 5
[0047] A method for preparing thermal temperature-responsive microspheres, comprising the following steps:
[0048] Weigh 5 g of acrylonitrile, 7 g of methyl methacrylate, 5 g of methyl acrylate, 3 g of methacrylic acid, 20 g of n-octane, and 0.5 g of azobisisobutyronitrile and mix them evenly as the oil phase;
[0049] 2 g of sodium dodecyl sulfate was weighed and dissolved in 90 mL of deionized water and mixed evenly as the aqueous phase; after stirring with a high-speed stirrer at 6000 rpm for 10 minutes to mix the oil phase and the aqueous phase, the mixture was transferred to a three-necked flask, stirred continuously at 300 rpm under a nitrogen atmosphere, and reacted at 65°C for 16 hours to obtain thermoresponsive microspheres.
[0050] Example 6
[0051] A method for preparing thermal temperature-responsive microspheres, comprising the following steps:
[0052] Weigh 5 g of acrylonitrile, 7 g of methyl methacrylate, 5 g of methyl acrylate, 3 g of methacrylic acid, 20 g of n-octane, and 0.5 g of azobisisobutyronitrile and mix them evenly as the oil phase;
[0053] Add 10 g of boron nitride, 0.4 mL of a vinyl-containing silane coupling agent (vinyltrichlorosilane), and 1 mL of tetraethyl orthosilicate to 100 mL of ethanol, adjust the pH to 6, react for 3 hours, and dry to obtain vinyl-functionalized boron nitride.
[0054] 2 g of vinyl-functionalized boron nitride was weighed and dissolved in 90 mL of deionized water and mixed evenly as the aqueous phase; after stirring with a high-speed stirrer at 6000 rpm for 10 minutes to mix the oil phase and the aqueous phase, the mixture was transferred to a three-necked flask, continuously stirred at 300 rpm under a nitrogen atmosphere, and reacted at 65°C for 16 hours to obtain thermoresponsive microspheres.
[0055] Example 7
[0056] A method for preparing thermal temperature-responsive microspheres, comprising the following steps:
[0057] Weigh 5 g of acrylonitrile, 7 g of methyl methacrylate, 5 g of methyl acrylate, 3 g of methacrylic acid, 20 g of n-octane, and 0.5 g of azobisisobutyronitrile and mix them evenly as the oil phase;
[0058] 2 g of boron nitride and 2 g of sodium dodecyl sulfate were weighed and dissolved in 90 mL of deionized water and mixed evenly as the aqueous phase; after stirring with a high-speed stirrer at 6000 rpm for 10 minutes to mix the oil phase and the aqueous phase, the mixture was transferred to a three-necked flask, continuously stirred at 300 rpm under a nitrogen atmosphere, and reacted at 65°C for 16 hours to obtain thermoresponsive microspheres.
[0059] The thermally responsive microspheres obtained in Examples 1-7 were tested for thermal conductivity using a German NETZSCH laser thermal conductivity tester 467. The test results are shown in Table 1.
[0060] Table 1 Thermal conductivity of thermal temperature responsive microspheres
[0061] project <![CDATA[Out-of-plane thermal conductivity (W•m -1 K -1 ).]]> Example 1 1.317 Example 2 1.442 Example 3 1.450 Example 4 1.658 Example 5 0.337 Example 6 0.726 Example 7 0.536
[0062] contrast Figure 1 and Figure 2 , Figure 1 There are flake materials attached to the surface of the medium-temperature-responsive microspheres, indicating that boron nitride is successfully coated on the surface of the thermal-temperature-responsive microspheres.
[0063] It can be concluded from Table 1 that during the polymerization process of the thermoresponsive microspheres, the thermal conductivity of the thermoresponsive microspheres can be effectively improved by coating the polymer shell with boron nitride. In Example 5, the out-of-plane thermal conductivity of the n-octane thermoresponsive microspheres without boron nitride coating is only 0.337 W·m -1 K -1 The thermal conductivity of the thermal temperature responsive microspheres prepared according to the method in Application Example 1 is 1.317 W·m -1 K -1 , nearly doubling the thermal conductivity. However, when no emulsifier was added in Example 6 or unmodified boron nitride was added in Example 7, the thermal conductivity performance also decreased significantly. This shows that vinyl-functionalized boron nitride works best when combined with an emulsifier and then loaded onto polymer microspheres.
[0064] from Figure 3It can be seen that due to the different types and boiling points of the core materials introduced, the response temperatures of the temperature-responsive microspheres show obvious differences. When the thermal temperature-responsive microspheres whose core material is n-octane are heated to 150°C, the microspheres begin to expand, showing a significant decrease in mass. This phenomenon indicates that the temperature response of the microspheres is triggered at a lower temperature and can release the encapsulated core material at an earlier stage. The thermal temperature-responsive microspheres whose core material is n-decane undergo obvious volume expansion at around 180°C. The temperature-responsive microspheres prepared in Example 1 began to decompose significantly at around 300°C, indicating that they have good thermal stability in a high-temperature environment, while in Example 6, there was a large mass loss at around 200°C, and in Example 7, the loss began at around 100°C. Thermogravimetric results show that the modification of emulsifiers and boron nitride enhances the thermal stability of the microspheres.
[0065] As the temperature gradually increases, the expansion order of the microspheres is directly related to the boiling point of the alkanes they contain. The lower the boiling point of the alkane, the lower its vaporization temperature, and the earlier the microspheres begin to expand. Specifically, under the action of lower boiling point alkanes, the microspheres can vaporize and expand in advance under lower temperature conditions. As the boiling point increases, the vaporization and expansion temperature also increases. Therefore, by precisely controlling the boiling point of the alkane, temperature-responsive microspheres with different expansion temperature ranges can be designed to meet diverse application needs. For example, Figure 4 As shown, the formulation in Example 1 uses n-octane, which has a boiling point of 125-127°C. Therefore, the microspheres begin to expand at approximately 130°C, and their volume also increases with increasing temperature, reaching their maximum volume at 180°C. In contrast, the formulation in Example 2 uses n-nonane, which has a boiling point of 151°C. The microspheres begin to expand at approximately 140°C and ultimately reach their maximum volume at 220°C. The n-decane in the formulation in Example 3 has a higher boiling point of 174°C, so the microspheres begin to expand at a higher temperature, approximately 160°C, and reach their peak volume at 200°C. Based on the application scenario, n-octane is more suitable for use in daily life.
Claims
1. A method for preparing thermal temperature responsive microspheres, characterized in that: The steps include: S1: mixing an ethylenically unsaturated monomer, a blowing agent and an initiator to obtain an oil phase; S2: mixing vinyl functionalized boron nitride, an emulsifier and deionized water to obtain an aqueous phase; S3: Under stirring, the oil phase and the water phase are mixed to obtain a mixed solution; under a nitrogen atmosphere, the mixed solution is reacted at 60-85° C., washed and dried to obtain the thermal temperature responsive microspheres; the ethylenically unsaturated monomers include one or more of nitriles, acrylates and acrylic acid.
2. The method for preparing the thermal temperature responsive microspheres according to claim 1, characterized in that: The preparation of the vinyl functionalized boron nitride comprises the following steps: adding boron nitride, a silane coupling agent with a vinyl group and tetraethyl orthosilicate into ethanol, adjusting the pH value between 3 and 11, reacting for 1 to 12 hours, and drying to obtain the vinyl functionalized boron nitride.
3. The method for preparing the thermal temperature responsive microspheres according to claim 2, characterized in that: The dosage ratio of the boron nitride, the vinyl-containing silane coupling agent and tetraethyl orthosilane is 10: (0.1-0.5): (0.5-2) g / mL / mL.
4. The method for preparing the thermal temperature responsive microspheres according to claim 2, characterized in that: The silane coupling agent with a vinyl group includes one or more of vinyl trichlorosilane, vinyl triethoxysilane, vinyl trimethoxysilane, γ-methacryloxypropyl trimethoxysilane and vinyl methyl dimethoxy silane.
5. The method for preparing the thermal temperature responsive microspheres according to claim 1, characterized in that: The emulsifier is sodium lauryl sulfate.
6. The method for preparing the thermal temperature responsive microspheres according to claim 1, characterized in that: The emulsifier accounts for 1.5-3% of the mass of the water phase, and the vinyl functionalized boron nitride accounts for 1-5% of the mass of the water phase.
7. The method for preparing the thermal temperature responsive microspheres according to claim 1, characterized in that: The foaming agent is n-octane, n-nonane or n-decane, the mass ratio of the foaming agent to the ethylenically unsaturated monomer is (0.7-1.1):1, and the initiator is azobisisobutyronitrile.
8. The method for preparing the thermal temperature responsive microspheres according to claim 1, characterized in that: The ethylenically unsaturated monomers include the following components in parts by weight: 3-6 parts of acrylonitrile, 6-8 parts of methyl methacrylate, 4-6 parts of methyl acrylate, and 2-5 parts of methacrylic acid.
9. The thermal temperature responsive microspheres prepared according to any one of claims 1 to 8, characterized in that: The invention comprises a shell formed by polymerization of ethylenically unsaturated monomers, a foaming agent encapsulated in the shell and boron nitride wrapped outside the shell.