Preparation method of high-thermal-conductivity polymer film and application thereof
By adding metal salts to soluble polymers to form thermally conductive channels, high thermal conductivity polymer films are prepared, solving the problems of low thermal conductivity and salt precipitation in polymers, and achieving efficient and low-cost improvement of thermal conductivity.
Patent Information
- Application Number
- CN202310733425.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-06-20
- Publication Date
- 2026-03-03
- Estimated Expiration
- 2043-06-20
AI Technical Summary
In existing technologies, the low thermal conductivity of polymers limits their application in scenarios requiring effective heat dissipation. Traditional methods increase the impact on polymer density and mechanical properties, while also presenting the problem of salt precipitation.
By adding metal salts, such as nickel chloride, to soluble polymers to form thermally conductive channels and then preparing high thermal conductivity polymer films using spin coating technology, salt precipitation is avoided and mechanical properties are maintained.
The thermal conductivity of polymer films is significantly improved to 1.2 W·m⁻¹·K⁻¹, reducing costs and avoiding the impact of increased density and mechanical properties, thus showing broad application prospects.
Smart Images
Figure CN116606467B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of polymer thin film technology, and in particular to a method for preparing a polymer thin film with high thermal conductivity. Background Technology
[0002] Polymers, such as polyacrylamide (PAM), are widely used in numerous fields, including electronics, energy, and environmental protection, due to their excellent chemical stability and mechanical properties. However, the inherently low thermal conductivity of polymers limits their application in scenarios requiring effective heat dissipation, including heat dissipation in electronic devices and energy transmission.
[0003] To improve the thermal conductivity of polymers, traditional methods mainly rely on incorporating filler particles with high thermal conductivity, such as metals, metal oxide particles, and carbon-based materials. However, this method is not without its flaws. First, the addition of a large number of filler particles may increase the density of the composite material and potentially alter its mechanical and optoelectronic properties. Second, uniformly dispersing filler particles in the polymer is a challenge; uneven dispersion can lead to uneven composite properties. Furthermore, filler particles may cause equipment wear during use, and interfacial delamination with the polymer can increase the material's brittleness, affecting its service life. Moreover, the extensive use of high-cost filler particles also increases the cost of material preparation.
[0004] In light of these issues, researchers have recently begun to explore methods such as adding ions to improve the thermal conductivity of polymers. Ions can interact with polymers at the molecular level to form new structures, thereby enhancing the polymer's thermal conductivity. However, traditional ion addition methods often induce salt precipitation, which can negatively impact the stability and applicability of the polymer. Summary of the Invention
[0005] To address the technical problems of traditional methods of adding filler particles increasing polymer density and significantly affecting polymer mechanical properties, as well as the technical issues of traditional ion addition methods causing salt precipitation, the primary objective of this invention is to provide a method for preparing polymer films with high thermal conductivity.
[0006] Another object of the present invention is to provide a high thermal conductivity polymer film prepared by the above preparation method.
[0007] Another object of the present invention is to provide an application of the above-mentioned high thermal conductivity polymer film.
[0008] The technical problem of this invention is solved by the following technical solution:
[0009] A method for preparing a polymer thin film with high thermal conductivity includes the following steps:
[0010] S1. Dissolve the soluble polymer to obtain an aqueous solution of the soluble polymer, add the metal salt, stir in a water bath, and ultrasonically disperse to obtain a polymer ion dispersion in which the soluble polymer and the metal salt are uniformly dispersed.
[0011] S2. A polymer ion membrane with a thickness of 60-120 nm is obtained by spin coating and by controlling the rotation speed.
[0012] S3. Anneal and dry the obtained polymer ion membrane to obtain a polymer film with high thermal conductivity.
[0013] In some embodiments, in step S1, the soluble polymer is selected from one or more of polyacrylamide, polyethylene, polyvinyl alcohol, polyethylene oxide, and polyacrylic acid, preferably polyacrylamide; the weight-average molecular weight of the soluble polymer is 2 million to 6 million; the dissolution is to dissolve the soluble polymer in ultrapure water; the mass content of the soluble polymer in the aqueous solution is 1-2 wt%.
[0014] In some embodiments, in step S1, the metal salt is selected from one or more of nickel chloride, copper chloride, and lithium chloride, preferably nickel chloride; the mass ratio of the metal salt to the soluble polymer is greater than or equal to 0.3, preferably 0.3-0.7.
[0015] In some embodiments, in step S1, the water bath stirring specifically involves stirring in a water bath at 45-60°C for 60-80 minutes; the ultrasonic dispersion time is 20-40 minutes.
[0016] In some embodiments, step S2, specifically, involves spin coating and controlling the rotation speed: an acceleration of 100-150 rpm / s, a rotation speed of 1500-3000 rpm, and a spin coating time of 50-70 seconds.
[0017] In some embodiments, in step S3, the annealing specifically involves annealing on a hot plate at 80-100℃ for 20-40 minutes; the drying specifically involves drying in a vacuum drying oven at 50-70℃ for 7-9 hours.
[0018] In some embodiments, in step S3, the thermal conductivity of the high thermal conductivity polymer film is as high as 1.2 W·m. -1 ·K -1 .
[0019] The present invention also proposes a high thermal conductivity polymer film, which is prepared by the above-described method for preparing high thermal conductivity polymer films.
[0020] This invention also proposes the application of the above-mentioned high thermal conductivity polymer film in the field of heat dissipation for electronic devices.
[0021] The beneficial effects of this invention compared to the prior art include:
[0022] This invention uses a soluble polymer as the base polymer and adds a metal salt that is highly miscible at the molecular level in the same solvent to the soluble polymer at a specific mass ratio. On one hand, the metal salt forms thermally conductive channels within the soluble polymer, significantly improving the thermal conductivity of the polymer film. On the other hand, the interaction between the metal salt and the soluble polymer forms crosslinking points, increasing chain order and significantly improving the continuity of heat conduction. This results in a polymer film where the metal salt ions and the soluble polymer are incompatible at the molecular level, effectively avoiding salt precipitation. Simultaneously, it does not increase the polymer density and has minimal impact on the polymer's mechanical properties. Furthermore, the thermal conductivity of the prepared polymer film can reach up to 1.2 W·m. -1 ·K -1 Compared to commercially available polymer films, its thermal conductivity is nearly 10 times higher, and its process is simple and low-cost, demonstrating broad application prospects, especially in the field of heat dissipation for electronic devices.
[0023] Other beneficial effects of the embodiments of the present invention will be further described below. Attached Figure Description
[0024] Figure 1 This is a flowchart of the method for preparing high thermal conductivity polymer films in this invention embodiment;
[0025] Figure 2 This is a schematic diagram showing the thermal conductivity of polymer ion-exchange membranes prepared by different mass ratios of nickel chloride and polyacrylamide in embodiments of the present invention. Detailed Implementation
[0026] The present invention will be further described below with reference to the accompanying drawings and preferred embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.
[0027] It should be noted that the directional terms such as left, right, up, down, top, and bottom used in this embodiment are only relative concepts or are based on the normal use of the product, and should not be considered as restrictive.
[0028] Against this backdrop, embodiments of the present invention propose a method for enhancing the thermal conductivity of soluble polymer films by incorporating metal salt ions. This method achieves molecular-level compatibility between metal salt ions and soluble polymers, effectively avoiding the problem of salt precipitation. It is important to emphasize the adsorption and high dispersion of metal salt ions in the soluble polymer film; these two aspects are crucial for enhancing the thermal conductivity of the soluble polymer film. First, the interaction between the side groups on the soluble polymer chains and the metal salt ions forms a strengthened thermal conductivity channel. This interaction can be achieved through various mechanisms, including charge transfer, reconfiguration of charge distribution, and electron sharing. These mechanisms work synergistically to form an efficient heat transfer path, improving the overall thermal conductivity of the soluble polymer film. Second, the metal salt ions further utilize the cross-linking points formed between the soluble polymer chains to increase the orderliness of the soluble polymer chains, thereby improving the continuity of heat conduction. These cross-linking points provide additional mechanical strength and stability, effectively preventing the breakage of the soluble polymer chains and the loss of heat energy. By increasing the orderliness of soluble polymer chains, the voids between them can be reduced, further enhancing heat transfer. This innovative method provides a new perspective for preparing polymer films with high thermal conductivity and is expected to have a significant impact on the heat dissipation performance of electronic devices. The polymer films produced by this method can achieve thermal conductivity as high as 1.2 W·m. -1 ·K -1 Compared to traditional methods of adding filler particles, this method does not increase the density of the polymer, has less impact on the mechanical properties of the polymer, and is simpler and less expensive, making it a promising application.
[0029] This invention provides a method for preparing a polymer thin film with high thermal conductivity, such as... Figure 1 As shown, it includes the following steps:
[0030] S1. Dissolve the soluble polymer to obtain an aqueous solution of the soluble polymer, add the metal salt, stir in a water bath, and ultrasonically disperse to obtain a polymer ion dispersion in which the soluble polymer and the metal salt are uniformly dispersed.
[0031] The soluble polymer is selected from one or more of polyacrylamide, polyethylene, polyvinyl alcohol, polyethylene oxide, and polyacrylic acid, preferably polyacrylamide; the weight-average molecular weight of the soluble polymer is 2 million to 6 million; dissolution is performed by dissolving the soluble polymer in ultrapure water; the mass content of the soluble polymer in the aqueous solution is 1-2 wt%. The water bath stirring is specifically performed at 45-60℃ for 60-80 minutes; the ultrasonic time is 20-40 minutes.
[0032] Furthermore, the metal salt is selected from one or more of nickel chloride, copper chloride, and lithium chloride, preferably nickel chloride; the mass ratio of the metal salt to the soluble polymer is greater than or equal to 0.3, preferably 0.3-0.7.
[0033] S2. A polymer ion membrane with a thickness of 60-120 nm is obtained by spin coating and by controlling the rotation speed.
[0034] The specific methods of spin coating and rotation speed control are as follows: acceleration of 100-150 rpm, rotation speed of 1500-3000 rpm, and spin coating time of 50-70 seconds.
[0035] S3. Anneal and dry the obtained polymer ion membrane to obtain a polymer film with high thermal conductivity.
[0036] The annealing process involves annealing on a hot plate at 80-100℃ for 20-40 minutes; the drying process involves drying in a vacuum drying oven at 50-70℃ for 7-9 hours. The high thermal conductivity polymer film has a thermal conductivity as high as 1.2 W·m. -1 ·K -1 .
[0037] This invention also proposes a high thermal conductivity polymer film, which is prepared by the above-described method for preparing a high thermal conductivity polymer film, and proposes the application of the above-described high thermal conductivity polymer film in the field of heat dissipation for electronic devices.
[0038] The specific principles for implementing embodiments of the present invention are as follows:
[0039] Soluble polymers are used as the base polymer, as these polymers possess soluble properties. Adding a metal salt that is highly miscible at the molecular level with the polymer in the same solvent can significantly improve the thermal conductivity of the polymer film. The thermal conductivity characteristics of the polymer are altered by forming thermally conductive channels within the soluble polymer through the addition of the aforementioned metal salt. Crosslinking points are formed by the interaction between the metal salt and the soluble polymer, increasing chain order and improving the continuity of heat conduction. The specific process involves the molecular-level fusion of the metal salt and the soluble polymer, as well as methods to avoid salt precipitation. The resulting polymer film exhibits properties such as high thermal conductivity and advantages over methods using highly thermally conductive particles, without increasing polymer density, having minimal impact on polymer mechanical properties, and demonstrating a simple and low-cost process.
[0040] The embodiments of the present invention have the following advantages:
[0041] 1. This invention proposes a method for significantly improving the thermal conductivity of soluble polymer films by adding metal salt ions. This method is innovative in the practice of enhancing thermal conductivity, offering higher efficiency and lower complexity compared to traditional filler-based enhancement methods.
[0042] 2. Significantly Improved Thermal Conductivity: By adding metal salt ions to the soluble polymer film, the thermal conductivity of the film can be significantly improved. The highly dispersed metal salt ions successfully adsorbed in the soluble polymer film form thermally conductive channels and improve the continuity of heat conduction, thereby significantly improving the thermal conductivity of the film.
[0043] 3. Easy to implement: Compared with polymers filled with high thermal conductivity materials such as metals or carbon nanotubes, the method of this invention uses metal salt ions as additives, which are not only inexpensive and easy to obtain, but also have good controllability.
[0044] 4. Broad application prospects: The polymer film prepared by the method of this invention can achieve a thermal conductivity of up to 1.2 W·m. -1 ·K -1 Compared to commercially available polymers, its thermal conductivity is nearly 10 times higher, demonstrating broad application prospects, especially in areas such as heat dissipation for electronic devices.
[0045] 5. Minimal impact on polymer properties: The metal salt ions in this method form a close contact with the polymer chains, effectively transferring heat energy, but do not significantly alter other physical or chemical properties of the polymer, such as mechanical strength or photoelectric properties.
[0046] 6. Advantages of Molecular-Level Compatibility: In this embodiment of the invention, the addition of metal salt ions to the soluble polymer film achieves molecular-level compatibility between the polymer and the metal salt ions. This molecular-level compatibility avoids problems such as uneven dispersion and interfacial delamination that may occur when ordinary filler particles are mixed into the polymer, ensuring a stable improvement in thermal conductivity while reducing the risk of affecting equipment performance and service life.
[0047] Example:
[0048] 1. Preparation of high thermal conductivity polymer ionic dispersion:
[0049] Dissolve 1g of soluble polymer PAM (MW; 5 million) in 100ml of ultrapure water to obtain a 1-2wt% soluble polymer aqueous solution of PAM; add 0.1-0.7g of metal salt NiCl2, stir in a water bath at 45-60℃ for 60-80min, and ultrasonically disperse for 20-40min to obtain a uniformly dispersed mixed solution of soluble polymer PAM and metal salt NiCl2, i.e., polymer ionic dispersion.
[0050] 2. Preparation of high thermal conductivity polymer ion exchange membranes:
[0051] High thermal conductivity polymer films can be prepared by spin coating, and the thickness can be controlled by the spin speed. With a spin speed of 1500-3000 rpm, an acceleration of 100-150 rpm, and a spin coating time of 50-70 s, PAM / NiCl2 polymer ion-exchange films with a thickness of 60-120 nm can be obtained.
[0052] 3. Drying and annealing:
[0053] The polymer ion exchange membrane was annealed on a hot plate at 90°C for 30 minutes, and then placed in a vacuum drying oven at 60°C for 8 hours to obtain a polymer film with high thermal conductivity.
[0054] like Figure 2 The graph shown illustrates the relationship between the thermal conductivity (Λ) of the polymer film in this embodiment of the invention and different mass ratios (φ) of NiCl2 to PAM. The horizontal axis represents different mass ratios of NiCl2 to PAM, and the vertical axis represents the thermal conductivity (Λ) of the polymer film. When the mass ratio (φ) of NiCl2 to PAM reaches 0.3, and preferably 0.3-0.7, the thermal conductivity of the polymer film in this embodiment of the invention can reach up to 1.2 W·m. -1 ·K -1 Compared to traditional polymer films with thermal conductivity of 0.1-0.2 W·m, -1 ·K -1 Within this range, the thermal conductivity of the polymer film in the embodiments of the present invention is increased by an order of magnitude. NiCl2 precipitation begins when the mass ratio (φ) of NiCl2 to PAM is greater than 0.7.
[0055] In different embodiments, different metal salt ions can be considered, specifically those with high solubility in the same solvent. Stirring and ultrasonic dispersion are used to obtain a solution with uniform diffusion at the molecular level. During the solvent evaporation process for film preparation, to prevent the precipitation of metal salts during solvent evaporation, it is necessary to use metal salts and polymers with high solubility in the same solvent. For example, copper chloride (CuCl2) or lithium chloride (LiCl) (salts with water solubility greater than or equal to NiCl2) can be used instead of nickel chloride (NiCl2) in the study. Although the thermal conductivity of ion-exchange films made from these metal ions may be lower than that of NiCl2, the interaction between the metal salt ions and polyacrylamide can still form thermally conductive channels in the polymer film and improve the continuity of heat conduction. This transitional approach may not achieve the effect of the optimal embodiment, but it provides an opportunity for exploration and optimization, and may also show superiority in specific application scenarios, such as when the requirements for thermal conductivity are not particularly high.
[0056] Different types of co-soluble, non-precipitating salts can also be added to polyacrylamide. The resulting polymer ion exchange membrane is one in which ions and polymers are fused at the molecular level, allowing the interaction between the side groups on the PAM chain and nickel ions to form new, enhanced thermal conductivity channels. In other words, the thermal conductivity of the polymer is altered by introducing new ions.
[0057] Different metal salt ions can be used to form cross-linking points between different polymer chains to increase the orderliness of the polymer chains and thus change the thermal conductivity of the polymer.
[0058] Furthermore, different soluble polymer substrates, such as polyethylene (PE) or polyvinyl alcohol (PVA), can be used to study changes in thermal conductivity after ion introduction. Water-soluble polymer substrates include polyethylene oxide (PEO) and polyacrylic acid (PAA).
[0059] Other solvents can also be used, such as polymethyl methacrylate (PMMA), which is miscible in organic solvents, and metal salts that are miscible with the solvent at the molecular level.
[0060] In this embodiment of the invention, the thermal conductivity of the polymer ion exchange membrane is measured using time-domain thermal reflectance technology (TDTR).
[0061] The innovative aspects of this invention are as follows:
[0062] 1. Molecular-level dispersion: The addition of nickel chloride (NiCl2) to polyacrylamide (PAM) achieves high dispersion at the molecular level. Compared with traditional particulate fillers, this molecular-level miscibility and dispersion avoids device wear and roughness caused by particulate filling, and reduces interfacial peeling and embrittlement caused by stress and deformation.
[0063] 2. High thermal conductivity: By adding NiCl2 to PAM, the thermal conductivity of the polymer film prepared is as high as 1.2 W·m. -1 ·K -1 This significantly improves the thermal conductivity of polymer films, providing a better solution for heat dissipation in electronic devices.
[0064] 3. Anti-aging and heat resistance: The addition of nickel ions to the polymer chain increases the stability of the polymer chain, improves its heat resistance, and provides excellent anti-aging properties.
[0065] 4. Simple and environmentally friendly preparation method: This new preparation method is not only simple, but also environmentally friendly and highly productive, which can significantly reduce production costs and improve production efficiency.
[0066] The embodiments of the present invention can achieve the following effects:
[0067] 1. Improved Thermal Conductivity: Polymers often exhibit low thermal conductivity in many applications, limiting their use in fields with high thermal management requirements. This invention significantly improves the thermal conductivity of polymer films by adding nickel chloride to polyacrylamide, thereby expanding their application in fields requiring high thermal conductivity.
[0068] 2. Avoiding interfacial wear and embrittlement: Traditional methods of reinforcing polymers with fillers often lead to interfacial wear and embrittlement between the filler and the matrix, thus affecting the service life of the material. However, this invention achieves the mixing of nickel chloride and polyacrylamide at the molecular level, thereby avoiding these problems.
[0069] 3. Simplified production process: Previous methods for improving polymer thermal conductivity typically required complex production processes and incurred high costs. However, this invention provides a simple and environmentally friendly preparation method that greatly simplifies the production process and reduces costs.
[0070] 4. Wide range of applications: Due to its advantages such as high thermal conductivity, anti-aging and heat resistance, the embodiments of the present invention have broad application prospects in fields such as electronic packaging, supercapacitors, LED housings and flexible electronic devices.
[0071] The embodiments of the present invention have the following advantages compared with the prior art:
[0072] 1. Technical Advantages: Traditional polymer thermal conductivity improvement techniques typically rely on the addition of high-κ fillers, which can lead to problems such as interfacial wear, embrittlement, and device stress. However, this invention utilizes the addition of nickel chloride ions to polyacrylamide at the molecular level, effectively avoiding these problems and achieving a significant improvement in thermal conductivity.
[0073] 2. Cost advantage: The embodiments of the present invention provide a simple and environmentally friendly preparation method, which greatly simplifies the production process and reduces production costs compared with traditional thermal conductivity improvement technologies.
[0074] 3. Efficiency Advantage: Due to the molecular-level addition method, the embodiments of this invention can achieve highly efficient heat conduction, reaching 1.2 W·m⁻². -1 ·K -1 This is significantly higher than that of traditional polymer films.
[0075] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, several equivalent substitutions or obvious modifications can be made without departing from the concept of the present invention, and all such modifications, achieving the same performance or purpose, should be considered within the scope of protection of the present invention.
Claims
1. A method for preparing a polymer thin film with high thermal conductivity, characterized in that, Includes the following steps: S1. Dissolve the soluble polymer to obtain an aqueous solution of the soluble polymer, add a metal salt, stir in a water bath, and ultrasonically disperse to obtain a polymer ion dispersion in which the soluble polymer and the metal salt are uniformly dispersed; the soluble polymer is selected from one or more of polyacrylamide, polyethylene, polyvinyl alcohol, polyethylene oxide, and polyacrylic acid, and the metal salt is selected from one or more of nickel chloride, copper chloride, and lithium chloride; the mass ratio of the metal salt to the soluble polymer is 0.3-0.7, so that the metal salt ions and the soluble polymer are compatible at the molecular level to avoid salt precipitation; S2. A polymer ion membrane with a thickness of 60-120 nm is obtained by spin coating and by controlling the rotation speed. S3. Anneal and dry the obtained polymer ion membrane to obtain a polymer film with high thermal conductivity.
2. The method for preparing a high thermal conductivity polymer film as described in claim 1, characterized in that, In step S1, the soluble polymer is polyacrylamide; the weight-average molecular weight of the soluble polymer is 2 million to 6 million; the dissolution is to dissolve the soluble polymer in ultrapure water; the mass content of the soluble polymer in the aqueous solution is 1-2 wt%.
3. The method for preparing a high thermal conductivity polymer film as described in claim 1 or 2, characterized in that, In step S1, the metal salt is nickel chloride.
4. The method for preparing a high thermal conductivity polymer film as described in claim 1, characterized in that, In step S1, the water bath stirring specifically involves stirring in a water bath at 45-60℃ for 60-80 minutes; the ultrasonic dispersion time is 20-40 minutes.
5. The method for preparing a high thermal conductivity polymer film as described in claim 1, characterized in that, In step S2, the spin coating and rotation speed control specifically means: acceleration of 100-150 rmp / s, rotation speed of 1500-3000 rmp, and spin coating time of 50-70s.
6. The method for preparing a high thermal conductivity polymer film as described in claim 1, characterized in that, In step S3, the annealing specifically involves placing the item on a hot plate at 80-100℃ for annealing for 20-40 minutes; the drying specifically involves placing the item in a vacuum drying oven at 50-70℃ for drying for 7-9 hours.
7. The method for preparing a high thermal conductivity polymer film as described in claim 1, characterized in that, In step S3, the thermal conductivity of the high thermal conductivity polymer film is as high as 1.2 W·m. -1 ·K -1 .
8. A polymer film with high thermal conductivity, characterized in that, It is prepared by the method for preparing high thermal conductivity polymer films according to any one of claims 1 to 7.
9. The application of the high thermal conductivity polymer film as described in claim 8 in the field of heat dissipation for electronic devices.