Double-phase-change temperature self-response thermal diode and preparation method thereof
Through the combination of the PNIPAM hydrogel phase change layer and the porous thermal insulation layer, the structure of the thermal diode is simplified and heat transfer is unidirectional, solving the problems of complex structure and strong direction dependence of the existing thermal diodes, and improving the thermal rectification effect and response speed.
Patent Information
- Application Number
- CN202510522182.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-24
- Publication Date
- 2025-07-29
AI Technical Summary
The existing thermal diodes have complex structures, strong direction dependence and weak thermal rectification effect, which limits their application range.
The solid-liquid phase change threshold response of PNIPAM hydrogel is used to the space-time coupling of the medium evaporation-condensation phase transition, combined with the steam channel of the porous insulation layer, and the unidirectional transfer of heat is achieved, and the heat flow directional regulation is controlled through the phase change behavior of the PNIPAM hydrogel phase change layer.
The structural design of the thermal diode is simplified, the direction dependence is weakened, the response speed and thermal rectification effect are improved, and the application range is broadened.
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Figure CN120388952A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of manufacturing phase change thermal diodes, and particularly relates to a dual-phase change temperature self-responsive thermal diode and a preparation method thereof. Background Art
[0002] A thermal diode is a device with unidirectional heat transfer characteristics and has a thermal rectification effect, that is, it allows heat to be transferred in one direction while being inhibited in the reverse direction. Analogous to the unidirectional conduction characteristic of an electronic diode for current, a thermal diode regulates the temperature dependence of the thermal conductivity of materials or structures, the interfacial contact thermal resistance, or the phase change behavior, enabling efficient heat transfer in a specific direction while being significantly blocked in the reverse path. Thermal diodes belong to passive thermal management devices and have advantages such as unidirectional controllability of heat transfer and no additional energy consumption, and have important applications in the field of thermal management. For example, in chip cooling, it can efficiently conduct heat out of a specific area, reduce the hot spot temperature, and at the same time block heat from entering in the reverse direction, thereby improving the reliability and lifespan of electronic devices. Existing thermal diodes generally achieve the thermal rectification effect through different structural designs or by utilizing the change in the heat conduction ability of materials at different temperatures. They usually have disadvantages such as a relatively complex structure, strong direction dependence, and weak thermal rectification effect, which limit their application scope. However, no method for solving related problems has been found in current research. Therefore, it is of great significance to prepare a thermal diode with a simple structure, weak direction dependence, and large thermal rectification. Summary of the Invention
[0003] Aiming at the problems existing in thermal diodes in the prior art, the present invention provides a dual-phase change temperature self-responsive thermal diode and a preparation method thereof. The heat flow directional regulation mechanism of the present invention relies on the solid-liquid phase change threshold response of PNIPAM hydrogel and the spatio-temporal coupling of medium evaporation-condensation phase change, combined with the steam channel directional guidance characteristics of the porous thermal insulation layer, to spontaneously form a unidirectional heat conduction path under a specific temperature gradient. The present invention first prepares a temperature-sensitive PNIPAM hydrogel and then uses it in the preparation of the self-responsive thermal diode. The self-responsive characteristic of the thermal diode of the present invention is adjusted through the phase change behavior of the PNIPAM hydrogel. The phase change temperature of the PNIPAM hydrogel is 32±0.5°C. After phase change, a large amount of free water is released. The free water absorbs heat and turns into water vapor, and the water vapor carries heat and flows along the evaporation channel. After reaching another heat conduction layer, the water vapor condenses into free water and releases the heat, thereby realizing unidirectional heat transfer. The present invention simplifies the structural design of the thermal diode, weakens the direction dependence, and breaks through the performance bottleneck while maintaining the advantages of passive operation (zero energy consumption) through dual-phase change collaborative regulation and adaptive interface bonding technology, broadening the application scope of the thermal diode.
[0004] The technical solution adopted by the present invention is as follows:
[0005] A dual-phase change temperature self-responsive thermal diode, comprising a support skeleton, with a first heat conduction layer and a second heat conduction layer respectively arranged at two opposite ends of the support skeleton. An insulation functional layer and a PNIPAM hydrogel phase change layer are sequentially arranged in the support skeleton from the first heat conduction layer to the second heat conduction layer, and the insulation functional layer is provided with a steam channel;
[0006] The phase change of the water medium is induced by the phase change of the PNIPAM hydrogel phase change layer, and the heat flow generated by the phase change of the water medium flows through the steam channel to achieve unidirectional heat transfer.
[0007] After adopting this technical solution, the present invention controls the startup of the thermal diode through the phase change behavior of the PNIPAM hydrogel layer, and has the advantage of rapid response speed compared with thermal diodes made of other materials; the present invention transfers heat through the natural convection of water molecules in the PNIAPM hydrogel layer, and the reverse heat transfer is hindered by the insulation functional layer, having a large heat rectification effect.
[0008] Preferably, the phase change temperature of the PNIPAM hydrogel in the PNIPAM hydrogel phase change layer is 32 ± 0.5 °C.
[0009] After adopting this technical solution, when the heat source temperature exceeds the critical phase change temperature of the hydrogel (>32 °C), the polymer network of the PNIPAM hydrogel undergoes a reversible phase change, resulting in the collapse of its internal three-dimensional network structure and the release of a large amount of bound water. These free waters are driven by heat to achieve directional transport through the steam channel, and the latent heat is rapidly transferred to the cold end of the thermal diode through the dynamic phase change cycle of evaporation-condensation. Through the double-phase change synergistic effect, the active rapid thermal management function is realized.
[0010] Preferably, the water content of the PNIPAM hydrogel phase change layer is 90-98%.
[0011] Preferably, the heat conduction coefficients of the first heat conduction layer and the second heat conduction layer are greater than 60 W / (m·K), and the thickness is 0.1-1.5 mm.
[0012] Furthermore, the first heat conduction layer and the second heat conduction layer are aluminum sheets, copper sheets, silica glass, aluminum nitride plates, beryllium oxide ceramic plates, and the thickness is 0.5-1.5 mm.
[0013] Preferably, the heat conduction coefficient of the insulation functional layer is less than 0.6 W / (m·K).
[0014] Preferably, the insulation functional layer is one or more of a porous material layer, a shaped phase change material layer, and an air cavity.
[0015] Furthermore, the porous material can be one of porous PDMS, porous organic foam, porous metal foam, and porous carbon foam, and the cavities on the porous material serve as steam channels; the shaped phase change material includes alkanes, alcohols, acids, etc., including but not limited to tetradecanol, hexadecanol, octadecanol, dodecanoic acid, tetradecanoic acid, hexadecanoic acid, octadecanoic acid, eicosanoic acid, octadecane, eicosane, paraffin, stearic acid, polyethylene glycol.
[0016] Preferably, the support framework is prepared from a heat-insulating support material. The heat-insulating support material can be a flexible material, and the overall shape of the thermal diode can be changed by changing the shape of the flexible support material to achieve operation under various working conditions; it can also be a rigid support material, and through different structural designs, the shape of the thermal diode matching different working conditions can be prepared. To ensure unidirectional heat transfer, the thermal conductivity of the surrounding heat-insulating support material should be less than that of the hydrogel (0.05 W / (m·K)), so the heat-insulating support material can be polymethyl methacrylate, polystyrene resin, and porous foam board, etc., materials with a thermal conductivity less than 0.05 W / (m·K) and certain mechanical strength.
[0017] A preparation method of a dual-phase change temperature self-responsive thermal diode includes the following steps:
[0018] S1: Prepare a PNIPAM hydrogel solution for preparing the PNIPAM hydrogel phase change layer;
[0019] S2: Inject the PNIPAM hydrogel solution into the support framework, and allow the PNIPAM hydrogel solution to naturally polymerize into PNIPAM hydrogel in the support framework by in-situ radical polymerization to form a PNIPAM hydrogel layer;
[0020] S3: Set a heat-insulating functional layer in the support framework;
[0021] S4: Carry out encapsulation.
[0022] Preferably, the raw materials for preparing the PNIPAM hydrogel solution include N-isopropylacrylamide (NIPAM), initiator, cross-linking agent, accelerator, and water. The specific preparation method is as follows: First, weigh a certain amount of NIPAM monomer, dissolve it in deionized water by magnetic stirring. After the monomer is dissolved, add the cross-linking agent MBA successively, slowly dropwise add the accelerator TEMED, continue stirring for ten minutes, and then add the initiator APS. After it is completely mixed evenly, place the solution under constant temperature conditions of 25°C / 45°C for 12 - 24 h. The hydrogel sample obtained at 25°C has a higher water content compared to that at 45°C, and the hydrogel sample obtained at 45°C has greater viscosity compared to the hydrogel at 25°C.
[0023] Preferably, the dosage ratio of N-isopropylacrylamide, water, crosslinking agent, accelerator, and initiator is 1000 mg: 25 - 50 ml: 30 - 90 mg: 200 μl: 30 - 50 mg.
[0024] Furthermore, the accelerator can be N,N,N,N-tetramethylethylenediamine (TEMED), the initiator can be ammonium persulfate (APS), and the crosslinking agent can be N,N'-methylenebisacrylamide (MBA).
[0025] Preferably, the volume of the injected PNIPAM hydrogel solution accounts for 50 - 80% of the total volume within the support framework.
[0026] Preferably, the thermal diode can be a regular cube, cuboid, or cylinder, with a first heat-conducting layer and a second heat-conducting layer provided on the top and bottom surfaces respectively, and an adiabatic support material pasted on the side to form a cavity; it can also be a cavity with an irregular shape to meet different applicable working conditions; it can also be a cavity made of a flexible material, and different working conditions can be satisfied by changing the shape of the cavity.
[0027] Preferably, the first heat-conducting layer or the second heat-conducting layer in contact with the heat insulation functional layer can be subjected to hydrophobic treatment to accelerate the heat transfer process and enhance the thermal rectification effect.
[0028] In summary, due to the adoption of the above technical solutions, the beneficial effects of the present invention are as follows:
[0029] The present invention controls the activation of the thermal diode through the phase change behavior of the PNIPAM hydrogel, and has the advantage of rapid response speed compared with thermal diodes made of other materials; the present invention transfers heat through the natural convection of water molecules in the PNIAPM hydrogel, and the reverse heat transfer is blocked by the heat insulation layer, having a large thermal rectification effect; the PNIPAM hydrogel of the present invention grows naturally in the support framework, adheres well to the first heat-conducting layer or the second heat-conducting layer located on the bottom surface, and does not change with the change of spatial position, having the advantages of simple structure and weak direction dependence. BRIEF DESCRIPTION OF THE DRAWINGS
[0030] Figure 1 is a preparation flow chart of a dual-phase change temperature self-responsive thermal diode;
[0031] Figure 2 is a phase change temperature curve graph of different crosslinking agent ratios during the preparation process of the PNIPAM hydrogel;
[0032] Figure 3 is a schematic diagram of the morphological change of water molecules during the heating and cooling process of the PNIPAM hydrogel;
[0033] Figure 4 is a physical diagram and a conceptual diagram of the thermal diode obtained in Example 1;
[0034] Figure 5 It is the temperature change curve graph of the thermal diode in Example 1 under two working modes during the heating process;
[0035] Figure 6 It is the heat transfer temperature difference result graph of the thermal diode in Example 1 under two working modes at different working temperatures;
[0036] Figure 7 It is the physical diagram and conceptual diagram of the thermal diode obtained in Example 2;
[0037] Figure 8 It is the temperature change curve graph of the thermal diode in Example 2 under two working modes during the heating process;
[0038] Figure 9 It is the heat transfer temperature difference result graph of the thermal diode in Example 2 under two working modes at different working temperatures. Detailed implementation manners
[0039] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part rather than all of the embodiments of the present application. Usually, the components of the embodiments of the present application described and illustrated herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the present application claimed, but merely represents selected embodiments of the present application. All other embodiments obtained by those skilled in the art based on the embodiments of the present application without creative efforts shall fall within the scope of protection of the present application.
[0040] In the description of the embodiments of the present application, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship when the inventive product is normally placed. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be construed as a limitation of the present application. In addition, the terms "first", "second", "third", etc. are only used for descriptive distinction and cannot be understood as indicating or implying relative importance.
[0041] Example 1
[0042] A dual-phase transition temperature self-responsive thermal diode includes a support framework. At two opposite ends of the support framework, a first heat conduction layer and a second heat conduction layer are respectively provided. Inside the support framework, a PNIPAM hydrogel phase change layer and a heat insulation functional layer are sequentially arranged from the first heat conduction layer to the second heat conduction layer. The heat insulation functional layer is provided with a steam channel.
[0043] In this embodiment, two metal aluminum sheets with a size of 50x50x1 mm are respectively used as the first heat conduction layer and the second heat conduction layer. Four polymethyl methacrylate plates with a size of 50x16x2 mm are used to form a rectangular frame with a square cross-section as the support framework. An air layer is used as the heat insulation functional layer with a self-provided steam channel.
[0044] The phase change of the water medium is induced by the phase change of the PNIPAM hydrogel phase change layer, and the heat flow generated by the phase change of the water medium flows through the steam channel to achieve unidirectional heat transfer.
[0045] As Figure 1 shown, its preparation method is as follows:
[0046] S1: Prepare a PNIPAM hydrogel solution for preparing the PNIPAM hydrogel phase change layer. The preparation process of the PNIPAM hydrogel solution is as follows:
[0047] Weigh 1 g of N-isopropylacrylamide (NIPAM) in a beaker, dissolve it in 30 ml of deionized water, add 50 mg of N,N'-methylenebisacrylamide (MBA) respectively, and use a pipette to drop 200 μl of N,N,N,N-tetramethylethylenediamine (TEMED). Continue stirring until it is mixed evenly, and then add 30 mg of ammonium persulfate (APS). All the above preparation drugs are purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. The model of N-isopropylacrylamide is I106818.
[0048] S2: First, paste the first heat conduction layer with the support framework, leaving only the opening on one side of the support framework. Then, inject the PNIPAM hydrogel solution prepared in S1 into the support framework, leaving a space with a height of 3 mm as the heat insulation functional layer. Then, put it into an oven at 25 °C for cross-linking for 8 h, so that the NIPAM hydrogel solution naturally polymerizes into PNIPAM hydrogel in the support framework by in-situ free radical polymerization to form a PNIPAM hydrogel layer.
[0049] S3: After the cross-linking is completed, pour out the excess water, and seal the top opening with the second heat conduction layer to complete the encapsulation, obtaining the thermal diode as Figure 4 shown.
[0050] Figure 2 is the phase transition temperature curve graph of different cross-linking agent ratios during the preparation process of PNIPAM hydrogel. From Figure 2It can be seen that by changing the ratio of the monomer NIPAM to the cross-linking agent BIS, the phase transition temperature of the PNIPAM hydrogel can be altered.
[0051] Figure 3 Figure for the morphological changes of water molecules during the heating and cooling process of the PNIPAM hydrogel. From Figure 3 it can be seen the state change of the PNIPAM hydrogel layer during the heat transfer process.
[0052] Thermal rectification test of this embodiment: Isothermal heating is carried out using a hydrothermal plate, and the heating temperature is 60 °C (greater than the phase transition temperature of the PNIPAM hydrogel by about 32 °C); Take two completely identical thermal diodes, which are named the first thermal diode (forward working mode) and the second thermal diode (reverse working mode) here for easy distinction. Apply thermal grease evenly on the first heat conduction layer of the first thermal diode and the second heat conduction layer of the second thermal diode (to increase the contact area with the heating surface and reduce the contact thermal resistance), and then place the ends of the first thermal diode and the second thermal diode coated with thermal grease on the heating surface of the hydrothermal plate. Paste thermocouples on the second heat conduction layer of the first thermal diode and the first heat conduction layer of the second thermal diode to record the temperature changes.
[0053] The results of the temperature change curves of the thermal diode in this embodiment under two working modes during the heating process are as Figure 5 shown, and the results of the heat transfer temperature differences between the two working modes at different working temperatures are as Figure 6 shown; From Figure 5 and Figure 6 it can be seen that when the different heating surfaces of the thermal diode are heated, the overall heat transfer rates are different. We stipulate that the thermal diode with a faster temperature rise is in the forward working mode; the thermal diode with a slower temperature rise is in the reverse working mode, that is, the thermal flow that transfers faster from the high-temperature region to the low-temperature region is the forward direction; the thermal flow that transfers slower from the high-temperature region to the low-temperature region is the reverse direction. According to the experimental results, the temperature rise in the forward mode is significantly faster than that in the reverse mode under the same heating conditions, and the maximum temperature difference reaches about 25 °C; According to the calculation formula of the thermal rectification ratio, the maximum thermal rectification factor is 4.2.
[0054] Example 2
[0055] A dual-phase transition temperature self-responsive thermal diode, comprising a support framework. The two relatively arranged ends of the support framework are respectively provided with a first heat conduction layer and a second heat conduction layer. Inside the support framework, a PNIPAM hydrogel phase transition layer and a heat insulation functional layer are sequentially arranged from the first heat conduction layer to the second heat conduction layer, and the heat insulation functional layer is provided with steam channels;
[0056] In this embodiment, two pieces of glass with dimensions of 50x50x1 mm are used as the first heat-conducting layer and the second heat-conducting layer respectively. Four polymethyl methacrylate plates with dimensions of 50x16x2 mm are used to form a rectangular frame with a square cross-section as the support skeleton, and an air layer is used as the heat-insulating functional layer with a self-contained steam channel;
[0057] The phase change of the water medium is induced by the phase change of the PNIPAM hydrogel phase change layer, and the heat flow generated by the phase change of the water medium flows through the steam channel to achieve unidirectional heat transfer;
[0058] Its preparation method is as follows:
[0059] S1: Prepare the PNIPAM hydrogel solution for preparing the PNIPAM hydrogel phase change layer. The preparation process of the PNIPAM hydrogel solution is as follows:
[0060] Weigh 1 g of N-isopropylacrylamide (NIPAM) in a beaker, dissolve it in 30 ml of deionized water, add 50 mg of N,N'-methylenebisacrylamide (MBA) respectively, and use a pipette to add 200 μl of N,N,N,N-tetramethylethylenediamine (TEMED). Continue to stir until it is evenly mixed, and then add 30 mg of ammonium persulfate (APS);
[0061] S2: First, paste the first heat-conducting layer with the support skeleton, leaving only the opening on one side of the support skeleton. Then, inject the PNIPAM hydrogel solution prepared in S1 into the support skeleton, leaving a space of 4 mm in height to set the heat-insulating functional layer. Then, put it into an oven at 45 °C and crosslink for 8 h to make the NIPAM hydrogel solution naturally polymerize into PNIPAM hydrogel in the support skeleton by in-situ free radical polymerization to form a PNIPAM hydrogel layer;
[0062] S3: After the crosslinking is completed, pour out the excess water, and install a 4-mm-thick PW44 composite form-stable phase change material in the support framework, which is placed closely against the PNIPAM hydrogel layer as the heat insulation functional layer. The preparation method of the PW44 composite form-stable phase change material is as follows: First, weigh a certain amount of PW44 paraffin (the dosage is set according to the volume of the remaining space in the support framework), place it in an oven at 60 °C to melt. After the PW44 paraffin is completely melted, add 20-30 wt% of SEBS (20% in this embodiment) to it, raise the oven temperature to 120 °C, and stir it every ten minutes until the two are completely mixed evenly. Then pour the mixture into a specific-shaped mold (i.e., a mold that matches the shape and size of the inner cavity of the support framework and can form a steam channel) for cooling. After complete cooling, a PW44 composite form-stable phase change material with a steam channel is obtained. It should be noted that regarding the size of the steam channel, without affecting the mechanical strength of the material itself, the larger the porosity, the better (in this way, the heat transfer in the forward mode is faster, and the thermal resistance in the reverse mode is greater). To enable the flow of water molecules, the pore size should be larger than the diameter of water molecules, which is 0.28 nm.
[0063] S4: Seal the top opening with the second heat-conducting layer to complete the encapsulation, and the obtained thermal diode is as Figure 7 shown.
[0064] Thermal rectification test of this embodiment: Use a heating stage for constant-temperature heating, and the heating temperature is 50 °C. Take two completely identical thermal diodes. Here, for the convenience of distinction, they are respectively named the first thermal diode (forward working mode) and the second thermal diode (reverse working mode). Apply thermal grease evenly to the first heat-conducting layer of the first thermal diode and the second heat-conducting layer of the second thermal diode (to increase the contact area with the heating surface and reduce the contact thermal resistance). Then place the ends of the first thermal diode and the second thermal diode coated with thermal grease on the heating surface of the heating stage, and paste thermocouples on the second heat-conducting layer of the first thermal diode and the first heat-conducting layer of the second thermal diode to record the temperature change.
[0065] Results of the thermal rectification experiment: The temperature change curve results of the two working modes of the thermal diode in this embodiment during the heating process are as Figure 8 shown, and the heat transfer temperature difference results of the two working modes at different working temperatures are as Figure 9 shown; from Figure 8 and Figure 9 it can be seen that after heating for the same time, the heating rates of the thermal diodes in different working modes are different. According to the experimental results, under the same heating conditions, the heating rate in the forward mode is significantly faster than that in the reverse mode, and the maximum temperature difference reaches about 22 °C; according to the calculation formula of the thermal rectification ratio, the maximum thermal rectification factor is 4.
[0066] The above-described embodiments merely represent specific implementation manners of the present application. The description thereof is relatively specific and detailed, but it should not be construed as a limitation on the protection scope of the present application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the technical solution of the present application, several modifications and improvements can still be made, and these all fall within the protection scope of the present application.
Claims
1. A dual phase change temperature self-responsive thermal diode, characterized in that: The invention comprises a supporting skeleton, wherein a first heat-conducting layer and a second heat-conducting layer are respectively provided at two opposite ends of the supporting skeleton, a PNIPAM hydrogel phase change layer and a heat-insulating functional layer are sequentially provided in the supporting skeleton from the first heat-conducting layer to the second heat-conducting layer, and the heat-insulating functional layer is provided with a steam channel; The phase change of the PNIPAM hydrogel phase change layer induces the phase change of the water medium, and the heat flow generated by the phase change of the water medium flows through the steam channel to realize unidirectional heat transfer.
2. The dual-phase transition temperature self-responsive thermal diode according to claim 1, wherein: The phase transition temperature of the PNIPAM hydrogel in the PNIPAM hydrogel phase transition layer is 32±0.5°C.
3. The dual phase-change temperature self-responsive thermal diode according to claim 1, characterized in that: The water content of the PNIPAM hydrogel phase change layer is 90-98%.
4. The dual phase-change temperature self-responsive thermal diode according to claim 1, characterized in that: The thermal conductivity of the first heat-conducting layer and the second heat-conducting layer needs to be greater than 60 W / (m·K), and the thickness is 0.1-1.5 mm.
5. A dual-phase transition temperature self-responsive thermal diode according to claim 1, wherein: The thermal conductivity of the heat-insulating functional layer is less than 0.6 W / (m·K).
6. The dual-phase change temperature self-responsive thermal diode according to claim 5, characterized in that: The support frame is prepared by using thermal insulation support material.
7. A method for preparing the dual-phase transition temperature self-responsive thermal diode according to any one of claims 1-6, characterized in that: The following steps are involved: S1: preparing PNIPAM hydrogel solution for preparing PNIPAM hydrogel phase change layer; S2: injecting the PNIPAM hydrogel solution into the support skeleton, so that the PNIPAM hydrogel solution is naturally polymerized into PNIPAM hydrogel by in situ free radical polymerization in the support skeleton to form a PNIPAM hydrogel layer; S3: Setting a heat insulation functional layer inside the supporting frame; S4: perform packaging.
8. The preparation method of a dual-phase change temperature self-responsive thermal diode according to claim 7, characterized in that: The raw materials for preparing the PNIPAM hydrogel solution include N-isopropylacrylamide, an initiator, a cross-linking agent, an accelerator, and water.
9. The preparation method of a dual-phase change temperature self-responsive thermal diode according to claim 8, characterized in that: The dosage ratio of N-isopropylacrylamide, water, crosslinking agent, accelerator and initiator is 1000 mg: 25-50 ml: 30-90 mg: 100-300 ul: 30-90 mg.
10. The preparation method of a dual-phase change temperature self-responsive thermal diode according to claim 7, characterized in that: The volume of the injected PNIPAM hydrogel solution accounts for 50-80% of the total volume within the support framework.